the distribution and severity of tremor in speech structures of persons with vocal tremor
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University of Iowa University of Iowa
Iowa Research Online Iowa Research Online
Theses and Dissertations
Spring 2012
The distribution and severity of tremor in speech structures of The distribution and severity of tremor in speech structures of
persons with vocal tremor persons with vocal tremor
Abby Leigh Hemmerich University of Iowa
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Part of the Speech and Hearing Science Commons
Copyright 2012 Abby Leigh Hemmerich
This dissertation is available at Iowa Research Online: https://ir.uiowa.edu/etd/2891
Recommended Citation Recommended Citation Hemmerich, Abby Leigh. "The distribution and severity of tremor in speech structures of persons with vocal tremor." PhD (Doctor of Philosophy) thesis, University of Iowa, 2012. https://doi.org/10.17077/etd.d8cjw4fi
Follow this and additional works at: https://ir.uiowa.edu/etd
Part of the Speech and Hearing Science Commons
THE DISTRIBUTION AND SEVERITY OF TREMOR IN SPEECH STRUCTURES OF PERSONS WITH VOCAL TREMOR
by
Abby Leigh Hemmerich
An Abstract
Of a thesis submitted in partial fulfillment of the requirements for the Doctor of Philosophy degree
in Speech and Hearing Science in the Graduate College of The University of Iowa
May 2012
Thesis Supervisor: Associate Professor Eileen Finnegan
1
ABSTRACT
Background: Vocal tremor affects over half a million Americans. Tremor can
affect structures within the respiratory, laryngeal, velopharyngeal, or oral regions
(Critchley, 1949). No study has related the of tremor severity in structures in all four of
these regions to the severity of vocal tremor.
Purpose: The purpose of this study was (a) to describe the distribution and
severity of tremor throughout the vocal tract and (b) to relate that to the severity of the
voice tremor. We hypothesized that tremor would be widespread throughout the vocal
tract, but most prevalent in the larynx, specifically in the true vocal folds. Additionally,
we expected vocal tremor severity to be directly related to the distribution and severity of
tremor in structures of the vocal tract.
Method: Twenty adults with vocal tremor and two age-matched controls
participated in the study. Two judges, experienced in assessment of laryngeal movement
disorders, rated the tremor severity in each of 15 structures during sustained /i/, /s/, /h/,
and rest breathing, and the severity of the voice tremor during sustained /i/, /s/, and /h/.
Results: A novel finding of this study was the identification of distribution and
severity of tremor in vocal tract structures associated with mild, moderate, and severe
vocal tremor. Participants with mild voice tremor tended to show tremor limited to
structures of the larynx, and in some cases, the velopharynx, and on average, had three
structures affected (most commonly true vocal folds, supraglottic structures, and
hypopharynx). Participants with moderate voice tremor tended to show tremor in the
larynx and velopharynx, and on average, had five structures affected (most commonly
true vocal folds, supraglottic structures, hypopharynx, vertical laryngeal movement, and
some other velar, oral, or respiratory structure). Those with severe voice tremor showed
tremor in the larynx, velopharynx, and beyond and on average, had eight structures
affected (most commonly true vocal folds, supraglottic structures, hypopharynx, vertical
laryngeal movement, anterior and lateral chest movement, velum, and jaw).
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A second novel finding, obtained through regression analyses, was that tremor
severity of the supraglottic structures and vertical laryngeal movement contributed the
most to the voice tremor severity during sustained phonation (r=0.77, F=16.17,
p<0.0001). A strong positive correlation (r=0.72) was found between the Tremor Index, a
composite value of the distribution and severity of structural tremor, and the severity of
the voice tremor during sustained phonation. The correlation between the severity of
tremor in the true vocal folds and the voice tremor was moderate (r=0.46).
Mean voice tremor severity was greater in participants over age 75 (mean=2.25)
than those between 66 and 75 years (mean=1.5) and under age 65 (mean=1.8). Mean
Tremor Index, was greater in participants over age 65 (mean TI=68) than those under age
65 (mean=41).
In this group of 20 participants, laryngeal/hypopharyngeal structures were most
frequently (95%) and severely (rated 1.7 out of 3) affected, followed by velopharyngeal
(40% occurrence, 1.3 severity), respiratory (40% occurrence, 1.1 severity), and oral (40%
occurrence, 1.0 severity) regions during sustained phonation. Tremor was also identified
more often and with greater severity in the larynx for sustained /s/ (70% occurrence, 1.7
severity), /h/ (40% occurrence, 1.7 severity), and rest breathing (45% occurrence, 1.6
severity) than other regions. During the voiceless and rest breathing tasks, the greatest
tremor severity was noted in the true vocal folds.
Conclusion: Evaluation of the distribution and severity of tremor may be useful in
guiding behavioral and medical treatment of voice tremor and for providing prognostic
information regarding response to laryngeal botulinum toxin injection.
Abstract Approved: ______________________________________________________
Thesis Supervisor
______________________________________________________ Title and Department
______________________________________________________ Date
THE DISTRIBUTION AND SEVERITY OF TREMOR IN SPEECH STRUCTURES OF PERSONS WITH VOCAL TREMOR
by
Abby Leigh Hemmerich
A thesis submitted in partial fulfillment of the requirements for the Doctor of Philosophy degree
in Speech and Hearing Science in the Graduate College of The University of Iowa
May 2012
Thesis Supervisor: Associate Professor Eileen Finnegan
Copyright by
ABBY LEIGH HEMMERICH
2012
All Rights Reserved
Graduate College The University of Iowa
Iowa City, Iowa
CERTIFICATE OF APPROVAL
______________________________
PH.D. THESIS
______________
This is to certify that the Ph. D. thesis of
Abby Leigh Hemmerich
has been approved by the Examining Committee for the thesis requirement for the Doctor of Philosophy degree in Speech and Hearing Science at the May 2012 graduation.
Thesis Committee: ________________________________________________
Eileen M. Finnegan, Thesis Supervisor ________________________________________________ Henry T. Hoffman ________________________________________________ Michael P. Karnell ________________________________________________ Jerald Moon ________________________________________________ Ingo R. Titze
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ACKNOWLEDGEMENTS
I would like to thank Dr. Henry Hoffman and his wonderful group of resident
physicians for their assistance with the nasendoscopic procedures during this study. I
would also like to thank Dr. Hoffman for his expertise and support throughout the
project. Thank you also to Pam Grecian, RN for her assistance in gathering participant
information, as well as helping me identify potential participants, setting up and cleaning
up each session, and general support! Thank you to Dr. Rhonda DeCook for her
suggestions and guidance in the statistical arena. Finally, I would like to extend a huge
thank you to Dr. Eileen Finnegan for her patience, support, time, expertise, and
painstaking efforts to ensure my success.
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TABLE OF CONTENTS
LIST OF TABLES ...................................................................................................v
LIST OF FIGURES ............................................................................................... vi
CHAPTER 1 INTRODUCTION ...............................................................1 Literature Review.........................................................................................1 Respiratory Musculature ..................................................................5 Laryngeal Musculature ....................................................................9 Velopharyngeal Musculature .........................................................14 Oral Musculature ...........................................................................15 Rating Severity of Tremor .............................................................17 Statement of the Problem ...........................................................................19 Hypotheses .................................................................................................22
CHAPTER 2 METHOD ..........................................................................24 Participants .................................................................................................24 Procedure ...................................................................................................25 Clinical Exam.................................................................................25 Respitrace Recordings ...................................................................27 Audio Recordings ..........................................................................28 Nasendoscopic Evaluation .............................................................28 Data Measurement .....................................................................................29 Reliability ...................................................................................................33 Analysis......................................................................................................33 Regions Affected by Tremor .........................................................34 Structures Affected by Tremor ......................................................34 Severity of Tremor Throughout the Vocal Tract ...........................34 Relating Distribution and Severity of Tremor to Voice Tremor Severity ..........................................................................................34
CHAPTER 3 RESULTS ..........................................................................38 Sustained Phonation ...................................................................................40 Respiratory Structures Affected by Tremor During /i/ ..................42 Laryngeal Structures Affected by Tremor During /i/ ....................42 Velopharyngeal Structures Affected by Tremor During /i/ ...........43 Oral Structures Affected by Tremor During /i/..............................43 Distribution and Severity of Tremor in Structures as a Function of Voice Tremor Severity During Sustained Phonation ............................44 Relating Distribution and Severity of Tremor to Severity of Voice Tremor........................................................................................................44 Does Voice Tremor Severity Increase with Age?......................................47 Sustained Voiceless Sounds .......................................................................47 Distribution and Severity of Tremor in Structures as a Function Of Voice Tremor Severity During Sustained Voiceless Sounds ...............48 Relating Distribution and Severity of Tremor to Severity of Voice Tremor of Sustained Voiceless Sounds .....................................................49 Rest Breathing ............................................................................................51 Respitrace Ratings .....................................................................................52 Reliability ...................................................................................................54
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Interjudge Reliability .....................................................................54 Intrajudge Reliability .....................................................................56
CHAPTER 4 DISCUSSION ....................................................................90
Purpose .......................................................................................................90 Does the Distribution and Severity of Tremor in Structures of the Vocal Tract Predict Severity of the Voice Tremor ....................................90 Clinical Implications ..................................................................................92 Does the Distribution and Severity of Tremor Change With Age .............96
Comparison of Results to the Literature ....................................................97 Does Tremor During Voiceless Sounds Relate to Respiratory
Tremor......................................................................................................103 Problems and Difficulties ........................................................................105 Conclusion ...............................................................................................106
REFERENCES ....................................................................................................109
APPENDIX A MOVEMENT DISORDER VOICE EVALUATION .....113
APPENDIX B CLINICAL TREMOR EVALUATION FORM ..............116
APPENDIX C AUDIO CLIP RATING FORM.......................................119
APPENDIX D VIDEO CLIP RATING FORM – VELO- PHARYNGEAL VIEW ...................................................121 APPENDIX E VIDEO CLIP RATING FORM - LARYNGEAL VIEW ...............................................................................126
APPENDIX F RESPITRACE DATA .....................................................132
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LIST OF TABLES
Table 1. Participant demographics ...........................................................................37
Table 2. Mean ratings of tremor severity in each structure for sustained phonation. ...................................................................................57
Table 3. Pearson correlation coefficients for ratings of tremor in each structure
(listed in column one) with ratings of voice tremor severity. ....................58
Table 4. Pearson correlation coefficients between structures for sustained phonation (p-values provided in parentheses). ..........................................59
Table 5. Multiple regression equations for sustained phonation. ............................60
Table 6. Mean ratings of tremor severity in each structure for sustained /s/. ..........61 Table 7. Mean ratings of tremor severity in each structure for sustained /h/. ..........62 Table 8. Pearson correlation coefficients for each structure with sustained /s/
tremor severity rating. ................................................................................63 Table 9. Pearson correlation coefficients for each structure with sustained /h/
tremor severity rating. ................................................................................63
Table 10. Pearson correlation coefficients between structures (p-values) for sustained /s/ ................................................................................................64
Table 11. Pearson correlation coefficients between structures (p-values) for
sustained /h/. ..............................................................................................65
Table 12. Multiple regression equations for sustained /s/ and sustained /h/. .............66
Table 13. Mean ratings of tremor severity in each structure for rest breathing. ........67 Table 14. Pearson correlation coefficients between structures (p-values) for rest
breathing. ...................................................................................................68
Table 15. Respiratory region ratings with Respitrace readings for sustained phonation....................................................................................................69
Table 16. Respiratory region ratings with Respitrace readings for sustained /s/. ......70
Table 17. Respiratory region ratings with Respitrace readings for sustained /h/. .....71
Table 18. Respiratory region ratings with Respitrace readings for rest breathing. ....72
Table 19. Interjudge reliability...................................................................................73
Table 20. Interjudge reliability for voice tremor severity. .........................................74
Table 21. Intrajudge reliability...................................................................................74
Table 22. Structures and innervations of the vocal tract ..........................................108
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LIST OF FIGURES
Figure 1. Tremor distribution. Regions of the speech mechanism affected by tremor as a function of severity of voice tremor during /i/. ..................75 Figure 2. Tremor distribution. Number of structures affected in each of 20 participants as a function of the severity of voice tremor during sustained /i/. ...............................................................................................76
Figure 3. Tremor distribution. Number of participants affected by tremor in each structure. ........................................................................................77
Figure 4. Tremor severity. Mean severity of tremor in each structure. .....................78
Figure 5. Rate of occurrence and severity (indicated by color) of tremor in each structure. ........................................................................................79
Figure 6. Voice tremor severity during sustained /i/ as a function of Tremor Index. ............................................................................................80
Figure 7. Relationship of age with a) voice tremor severity during sustained /i/, and b) Tremor Index during sustained /i/. ..................................................81
Figure 8. Tremor distribution. Regions of the speech mechanism affected by tremor as a function of severity of voice tremor during a) sustained /i/, b) sustained /s/, c) sustained /h/, and d) rest breathing. ........................82
Figure 9. Rate of occurrence and severity (indicated by color) of tremor in each
structure for a) sustained /i/, b) sustained /s/, c) sustained /h/, and d) rest breathing. ........................................................................................83
Figure 10. Sustained /s/ tremor severity as a function of Tremor Index. ....................84
Figure 11. Sustained /h/ tremor severity as a function of Tremor Index.....................85
Figure 12. Interjudge agreement on a) number of participants with tremor and b)
severity of tremor for sustained phonation ................................................86
Figure 13. Interjudge agreement on a) number of participants with tremor and b) severity of tremor for sustained /s/.............................................................87
Figure 14. Interjudge agreement on a) number of participants with tremor and b)
severity of tremor for sustained /h/. ...........................................................88 Figure 15. Interjudge agreement on a) number of participants with tremor and b)
severity of tremor for rest breathing. .........................................................89
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CHAPTER 1
INTRODUCTION
Literature Review
Approximately 4.6% of individuals over the age of 65 have some form of
essential tremor, including limb, head, and voice tremor (Benito-Leon, Bermejo-Pareja,
Morales, Vega, & Molina, 2002). About 30% of individuals with essential tremor
experience vocal tremor (Merati et al., 2005), which amounts to about 560,000 people
with vocal tremor in the United States alone (USCensusBureau, 2009c) and 7.4 million
people worldwide (USCensusBureau, 2009a). The number of individuals with vocal
tremor in the general population is likely even higher than the estimates provided in these
studies for several reasons. First, some estimates of essential tremor are as high as 23% of
those over age 70 (Elble, 1998), which if true, would mean nearly five times as many
individuals are affected by tremor than previously thought. Second, it is estimated that
50-99.5% of individuals have mild tremor and are not identified by clinics (Louis, Ford,
Wendt, & Cameron, 1998; Elble, 2000, as cited in Merati et al., 2005); including these
individuals would raise the number of affected individuals even further. The prevalence
of tremor increases with age, so the number of Americans affected by vocal tremor and
seeking treatment will likely increase over the next 40 years (USCensusBureau, 2009b)
as the population ages.
Vocal tremor is a neurological disorder characterized by nearly rhythmic
oscillations in muscles associated with phonation. The neurological source of tremor has
been frequently studied in limb tremor, but very little in vocal tremor. The olivocerebellar
tracts (Deuschl & Bergman, 2002; Llinas & Yarom, 1986; Rothwell, 1998), the
extrapyramidal system (Critchley, 1939), and peripheral reflex loops (Rack & Ross,
1986) have been suggested as potential sources of the oscillations seen in tremor. Other
studies identify the thalamus as a potential source, because patients receiving deep brain
stimulation of the thalamus demonstrate reduction or elimination of vocal tremor
2
symptoms (Abosch & Lozano, 2003; Carpenter et al., 1998; Moringlane, Putzer, & Barry,
2004; Rothwell, 1998; Sataloff, Heuer, Munz, Yoon, & Spiegel, 2002; Taha, Janszen, &
Favre, 1999).
Vocal tremor can occur in isolation (called essential voice tremor or essential
tremor of the voice) or as part of a larger essential tremor. Vocal tremor is often
associated with head or limb tremor (Massey & Paulson, 1985). It can also occur
concurrently with another disorder (e.g., spasmodic dysphonia) (Hillel, 2001; Klotz,
Maronian, Waugh, Shahinfar, Robinson, & Hillel, 2004), or as a component of other
disorders (e.g., Parkinson’s disease, supranuclear palsy, or amyotrophic lateral sclerosis
(Lundy, Roy, Xue, Casiano, & Jassir, 2002)). “Essential tremor is a postural tremor that
is accentuated by voluntary movement (Elble & Koller, 1990, p. 55),” which generally
disappears when the individual is completely at rest, such as during sleep. This is
different from tremor associated with Parkinson’s disease, which is generally a rest
tremor (Elble & Koller, 1990; Jankovic, 1995) or cerebellar tremor, which is generally
more irregular than essential tremor (Ackermann & Ziegler, 1991).
Vocal tremor is characterized by modulations in pitch, loudness, or voicing.
Modulations occur in both the frequency and the amplitude of the signal, which correlate
to modulations in both the pitch and loudness of the voice. The frequency of the
modulations in both the pitch and loudness usually occur at 4-8 Hz (Brown & Simonson,
1963), with amplitude modulations often between 40-100% (Brown & Simonson, 1963).
These modulations are generally measured during production of a sustained vowel, but
can be noticeable during connected speech as well, which can cause diminished
intelligibility; the tremor can escalate to include complete voice breaks in severe cases
(Ardran, Kinsbourne, & Rushworth, 1966).
Vocal tremor can have a major effect on an individual’s daily life. People with
mild tremor may complain of a wavering voice. People with severe tremor may
experience complete voice breaks, preventing the individual from speaking intelligibly
3
(Ardran et al., 1966; Brown & Simonson, 1963). Vocal tremor can prevent some
individuals from participating in their favorite social activities (Hachinski, Thomsen, &
Buch, 1975), from singing in church to talking on the telephone to dining in restaurants.
Treatment of vocal tremor generally focuses on reduction of the symptoms, often
through the use of botulinum toxin injections to the larynx. These injections provide
temporary muscle paralysis of the targeted muscle(s). Multiple studies have examined the
effectiveness of these injections (Adler, Bansberg, Hentz, Ramig, Buder, Witt, et. al.,
2004; Hertegard, Granqvist, & Lindestad, 2000; Christy L. Ludlow, Sedory, Fujita, &
Naunton, 1989; Warrick, Dromey, Irish, & Durkin, 2000; Warrick, Dromey, Irish, Durkin
et al., 2000) with approximately 74% of participants experiencing an improvement in
symptoms of vocal tremor following the injection; however, results can vary from
injection to injection and some individuals do not show improvement following the
injection.
One possible reason for the varied results of laryngeal botulinum toxin injections
for vocal tremor may be differences in the distribution and severity of tremor across
patients. Individuals with widespread tremor may not be as likely to show improvement
with localized laryngeal botulinum toxin injections (Sulica & Louis, 2010). However,
studies describing the distribution of tremor are limited. Several studies have examined
tremor in muscles of the larynx (Ardran et al., 1966; Brown & Simonson, 1963;
Finnegan, Luschei, Barkmeier, & Hoffman, 2003; Hachinski et al., 1975; Hillel, 2001;
Klotz et al., 2004; Koda & Ludlow, 1992; Massey & Paulson, 1985; Tomoda, Shibasaki,
Kuroda, & Shin, 1987), respiratory system (Ardran et al., 1966; Hachinski et al., 1975;
Lebrun, Devreux, Rousseau, & Darimont, 1982; Massey & Paulson, 1985; Tomoda et al.,
1987), or articulatory region (Ardran et al., 1966; Biary & Koller, 1987; Brown &
Simonson, 1963; Hachinski et al., 1975; Koller, Glatt, Biary, & Rubino, 1987; Lebrun et
al., 1982; Warrick, Dromey, Irish, Durkin et al., 2000) and most authors agree that
patients with vocal tremor experience muscle contractions in multiple muscles. Sulica
4
and Louis (2010) demonstrated that individuals with essential voice tremor have multiple
structures affected by tremor, including the palate, base of tongue, pharyngeal walls,
supraglottis, and true vocal folds. Bove, Daamen, Rosen, Wang, Sulica, and Gartner-
Schmidt (2006) showed that individuals with greater tremor in structures other than the
true vocal folds had poorer responses to laryngeal botulinum toxin injections than those
with greater tremor in the true vocal folds. However, Sulica and Louis (2010), replicating
the study by Bove and colleagues (2006), reported findings that conflict with the results
of Bove and colleagues (2006). Sulica and Louis (2010) found that there was no
difference between those who responded to botulinum toxin injections and those who did
not in severity of tremor in the true vocal folds compared to other stuctures of the larynx.
This suggests that improved knowledge of the distribution and severity of tremor would
be useful in determining treatment and predicting outcomes in patients receiving
laryngeal botulinum toxin injections.
Critchley (1949) suggested that muscles within the respiratory, laryngeal, and/or
articulatory regions may be affected by tremor and result in the perception of vocal
tremor. No study to date has prospectively examined the prevalence of tremor in muscles
of the respiratory, laryngeal, velopharyngeal, and oral regions in a cohort of patients with
vocal tremor. The aim of this study, therefore, was to describe the prevalence of tremor in
these four regions to assist in treatment decisions for these individuals, using botulinum
toxin injections or other methods.
The following review of the literature was organized to provide a summary of
studies to date examining muscles and structures affected by vocal tremor separated by
region, the effects of tremor in each region on vocal quality, and studies evaluating the
severity of vocal tremor. For the purposes of this study, the respiratory region was
defined as any structure below the glottis, including muscles of the chest and abdomen
which contribute to respiration. The laryngeal region was defined as intrinsic and
extrinsic structures of the larynx, including the true vocal folds, false vocal folds,
5
aryepiglottic folds, epiglottis, base of the tongue, pharyngeal walls posterior to the larynx,
and muscles of the neck which support the larynx (strap muscles). The velopharyngeal
region was defined as structures making up the velopharyngeal port, including the velum,
posterior pharnyngeal wall, and lateral pharyngeal walls. The oral region was defined as
structures within the oral cavity, including the jaw, tongue, and lips.
Respiratory Musculature
Vocal tremor due to respiratory muscle oscillation has been reported in 12 of 17
cases (71%), but varies from estimates of 25% to 100% depending on the number of
participants, muscles studied, and method of measurement. Muscles involved in
inspiration, including the diaphragm, external intercostals, and strap muscles of the neck,
as well as muscles of expiration, including the internal intercostals and the abdominal
muscles could be potential sources of vocal tremor. These muscles control the air source
for phonation, so oscillations occurring in these muscles could lead to modulations in the
subglottic air pressure, causing modulations in the amplitude and frequency of vocal fold
vibration, perceived as vocal tremor.
Tremor of the diaphragm was observed in five of six case studies (83%), based on
fluoroscopic evaluation (participants were assessed during phonation in only three cases).
Hachinski, Thomsen, and Buch (1975) examined the diaphragm under fluoroscopy, as
well as completing aerometry and voice oscillography, in three participants with vocal
tremor. They observed irregular, jerky movements of the diaphragm near the end of
inspiration, as well as “interruption of the normally smooth downward movement of the
diaphragm (Hachinski et al., 1975, p. 196)” during expiration, sustained phonation, and
connected speech in all three. All three participants were able to temporarily halt the
tremor by a breath hold maneuver. Aerometry and voice oscillography showed tremor
between 4-5 Hz for all three participants with voice breaks appearing at points where
irregularities in respiration occurred. The authors describe the movement of the
diaphragm as downward during expiration and phonation, with jerky movements
6
interrupting this motion; this movement of the diaphragm is inconsistent with normal
respiratory physiology. Massey and Paulson (1985) examined the diaphragm under
fluoroscopy in two participants with vocal tremor; diaphragmatic tremor was identified in
one of the two participants. The authors did not describe the tasks completed while under
fluoroscopy or whether the diaphragmatic tremor was correlated to the voice signal.
Examination of the vocal folds in these two participants showed no tremor, however the
authors did not comment on any other structures of the vocal tract, and attributed the
vocal tremor to the respiratory movements observed. Tomoda, Shibasaki, Kuroda, and
Shin (1987) examined the diaphragm under fluoroscopy, while also recording voice
samples, in one participant with vocal tremor. This participant showed rhythmic vertical
diaphragmatic movements “synchronous with voice tremor (Tomoda et al., 1987, p.
119)” during voluntary expiration. Behavior of the diaphragm during phonation was not
discussed. The participant did not show diaphragmatic tremor during voluntary
inspiration or involuntary breathing.
The sternocleidomastoid was shown to be involved in vocal tremor in two of three
cases (67%). Tomoda, Shibasaki, Kuroda, and Shin (1987) recorded surface
electromyography (EMG) of the sternocleidomastoid with concurrent voice recordings
from three participants with vocal tremor. Two of the participants demonstrated
synchrony between the voice signal and surface EMG from the sternocleidomastoid,
which was present during voluntary phonation tasks, but generally was not present during
involuntary phonation tasks, such as laughing or yawning. Tremor was also noted in the
cricothyroid and thyroarytenoid muscles.
Tremor activity has been recorded from the pectoralis major in two of four
participants (50%) with vocal tremor, but was slightly higher in frequency and not
synchronous with vocal tremor. Ardran, Kinsbourne, and Rushworth (1966) recorded
EMG from the pectoralis major of a single participant with benign essential vocal tremor
and found no tremor activity during phonation, although there was a 6 Hz rest tremor.
7
Tomoda, Shibasaki, Kuroda, and Shin (1987) recorded surface EMG from the pectoralis
major of three participants with vocal tremor (two participants also had hand tremor).
Two of the three participants demonstrated tremor in the pectoralis major during
phonation; however, this tremor was not synchronous with the vocal tremor and was
higher in frequency (pectoralis tremor: 6-8 Hz, vocal tremor: 4-5 Hz), suggesting that the
pectoralis tremor was related to the limb tremor these participants experienced and not
the vocal tremor.
No tremor was recorded for the external intercostals in a single participant from
whom data was obtained (Ardran et al., 1966). Ardran, Kinsbourne, and Rushworth
(1966) recorded EMG from the external intercostals in a single participant with vocal
tremor, but found no tremor activity during phonation. Further study of these muscles
would be beneficial in determining whether the intercostals are involved in vocal tremor.
The rectus abdominis, an expiratory muscle, was shown to be involved in vocal
tremor in three cases (Tomoda et al., 1987). Tomoda, Shibasaki, Kuroda, Shin (1987)
recorded surface EMG and accelerometry from the rectus abdominis, with concurrent
voice samples, from three participants with vocal tremor. Two of the three (67%)
participants demonstrated synchrony between the voice signal and the surface EMG of
the rectus abdominis; the third participant showed synchrony between the voice signal
and accelerometry of the rectus abdominis. The tremor was present during voluntary
phonation tasks (sustained “ah”), but generally was not present during involuntary
phonation tasks, such as laughing or coughing. Two participants also demonstrated
tremor on EMG during voluntary expiration; none of the participants demonstrated
tremor during voluntary inspiration or involuntary (rest) breathing.
Broad measures of respiratory region involvement in tremor have indicated
tremor was present in about 25% of cases. Koda and Ludlow (1992) used respiratory
plethysmography (Respitrace) to assess the respiratory component of tremor in seven
participants with vocal tremor. Tremor was identified through visual inspection of the
8
Respitrace output in two of the seven participants during phonation and whisper. The
tremor on Respitrace was not well-correlated with the audible voice tremor, indicating
these oscillations may not have been responsible for the vocal tremor.
The perception of vocal tremor can be generated when the respiratory system is
forced into oscillation; the alterations in pressure and airflow for voicing can be
perceived as modulations in the frequency and amplitude of the voice signal. This
relationship between oscillations of muscles within the respiratory system and the
perception of vocal tremor was demonstrated by Farinella, Hixon, Hoit, Story, and Jones
(2006). Five normal speakers produced various sustained and connected speech samples
with forced oscillation of the respiratory system by a body plethysmograph. The forced
respiratory oscillations varied in frequency (5-12 Hz) and amplitude (0-4 cm H2O). Six
listeners rated the sustained phonation and connected speech samples, and detection
thresholds for tremor were calculated. Tremor was detected by the listeners with 1.37 cm
H20 of oscillatory pressure on the thorax for sustained vowels and 2.16 cm H20 of
oscillatory pressure on the thorax for connected speech. Listeners also rated the sustained
vowels as having more severe tremor than connected speech, and vowels produced in a
breathy or normal voice quality as having more severe tremor than a pressed quality. The
results of this study indicate two things: 1) respiratory oscillations can result in the
perception of vocal tremor; and 2) these oscillations must reach a particular magnitude
before vocal tremor is perceived.
The available data indicate that the respiratory system may contribute to the
perception of vocal tremor, with conservative estimates of a respiratory component in
about 25% of cases. In all of the above case studies, it was not clear whether individuals
were included because they had voice tremor or because they had respiratory tremor, so
the more conservative level of tremor based on the study using Respitrace may be a better
estimate. The limited amount of data and frequent case study designs suggest that the
respiratory region may not be a primary source of vocal tremor.
9
Laryngeal Musculature
Most individuals with vocal tremor described in the literature experience
oscillations in muscles within the laryngeal region. Both intrinsic laryngeal muscles (e.g.,
thyroarytenoid, cricothyroid) and extrinsic laryngeal muscles (e.g., sternothyroid,
thyrohyoid) are potential sources of vocal tremor.
The thyroarytenoid and cricothyroid were the intrinsic muscles in which tremor
has been recorded most frequently, although all five of the intrinsic muscles of the larynx
have been shown to exhibit tremor during phonation on EMG. Specifically, tremor
activity was noted in the cricothyroid in 23 of 31 participants (74%) (Ardran et al., 1966;
Finnegan et al., 2003; Hillel, 2001; Koda & Ludlow, 1992; Tomoda et al., 1987), the
thyroarytenoid muscles in 71 of 110 participants (65%) (Finnegan et al., 2003; Hillel,
2001; Klotz et al., 2004; Koda & Ludlow, 1992; Tomoda et al., 1987), the posterior
cricoarytenoid in nine of 16 participants (56%) (Hillel, 2001; Koda & Ludlow, 1992), the
lateral cricoarytenoid in 36 of 67 participants (54%) (Hillel, 2001; Klotz et al., 2004), and
the interarytenoid in eight of 49 participants (16%) (Hillel, 2001; Klotz et al., 2004).
Ardran, Kinsbourne, and Rushworth (1966) recorded EMG from the cricothyroid muscle
of a single participant with severe vocal tremor. A 5-6 Hz tremor was recorded at rest,
which became an 8 Hz irregular tremor during sustained phonation (“eee”). Tomoda,
Shibasaki, Kuroda, and Shin (1987) recorded simultaneous voice samples and EMG from
the thyroarytenoid and cricothyroid muscles during sustained phonation (“ah”) in three
participants with vocal tremor. Rhythmic oscillations of the voice samples were
synchronous with oscillations in the EMG signal from the cricothyroid muscle in all three
participants and from the thyroarytenoid muscle in one of three participants. Koda and
Ludlow (1992) recorded EMG from the thyroarytenoid and cricothyroid muscles in eight
participants during sustained phonation (“eee”), with three of these also including
recordings from the posterior cricoarytenoid. The thyroarytenoid muscle was affected by
tremor in all eight participants (100%), while the cricothyroid muscle was affected in six
10
of the eight participants (75%). The posterior cricoarytenoid muscle was affected by
tremor in all three participants (100%) from which EMG was recorded. The authors did
not state whether the tremor activity was synchronous with the voice signal. Finnegan,
Luschei, Barkmeier, and Hoffman (2003) recorded voice samples and EMG from the
thyroarytenoid and cricothyroid muscles of six participants during sustained phonation.
All six participants (100%) showed tremor activity in the thyroarytenoid and cricothyroid
muscles. Muscle activity was correlated with the voice signal in three participants (50%)
for the thyroarytenoid and in one participant (17%) for the cricothyroid. Hillel (2001)
recorded EMG from the thyroarytenoid muscle and two other intrinsic laryngeal muscles
(cricothyroid in 12 participants, posterior cricoarytenoid in 11 participants, lateral
cricoarytenoid in 7 participants, and interarytenoid in 7 participants) during phonation
and connected speech in 20 participants with tremor spasmodic dysphonia. Tremor
spasmodic dysphonia was defined as a variant of adductor spasmodic dysphonia in which
tremor was the primary characteristic with concurrent strain and/or vocal breaks. Tremor
activity was noted in the thyroarytenoid muscle in 14 of the 20 participants (70%), the
cricothyroid muscle in eight of 14 participants (57%), the lateral cricoarytenoid muscle in
four of seven participants (57%), the posterior cricoarytenoid muscle in six of 13
participants (46%), and the interarytenoid muscle in two of seven participants (29%)
during sustained phonation. Klotz, Maronian, Waugh, Shahinfar, Robinson, and Hillel
(2004) recorded EMG from the thyroarytenoid, lateral cricoarytenoid, and interarytenoid
muscles in 77 participants with tremor spasmodic dysphonia. Tremor activity was
recorded from the thyroarytenoid muscle in 42 of 73 participants (57%), the lateral
cricoarytenoid muscle in 32 of 60 participants (53%), and the interarytenoid muscle in six
of 42 participants (14%).
Tremor of the structures of the larynx, including the true vocal folds, false vocal
folds, and epiglottis, has often been observed using laryngoscopy; visual inspection of the
true vocal folds during phonation showed tremor activity in 110 of 140 reported cases
11
(79%) (Bove et al., 2006; Brown & Simonson, 1963; Hachinski et al., 1975; Klotz et al.,
2004; Koda & Ludlow, 1992; Massey & Paulson, 1985, Sulica & Louis, 2010). Brown
and Simonson (1963) viewed the larynx of 14 participants with vocal tremor using
laryngoscopy but did not identify tremor of the true vocal folds in any of the participants;
the vocal tremor was attributed to vertical oscillations of the larynx within the neck.
These authors completed laryngoscopy on only 14 of the 31 participants included in their
overall study, so it was unclear whether some of the other participants may have
exhibited vocal fold tremor when the larynx was visualized. Additionally, 17 of these 31
participants showed additional neurologic signs, such as spasmodic torticollis, sucking
reflex, incoordination/adiadochokinesis, intellectual impairment, or focal ischemic
episodes, potentially indicating that these participants were not experiencing essential
voice tremor, but some other disorder which included vocal tremor. Hachinski, Thomsen,
and Buck (1975) completed laryngoscopy on three participants with vocal tremor and
found no tremor in any of the participants. The authors did not describe the tasks
completed by the participants during laryngoscopy however, so tremor may have been
present but not observed on the tasks chosen. Massey and Paulson (1985) completed
laryngoscopy in four participants with vocal tremor. They reported normal laryngeal
exams in all four, showing “no vocal cord tremor (Massey & Paulson, 1985, p. 317).”
Again, the tasks completed during laryngoscopy were not described. Koda and Ludlow
(1992) completed laryngoscopy in eight participants with vocal tremor. They identified
tremor activity in the true vocal folds in all eight participants during sustained phonation.
Tremor was first identified as present or not present, and where present, the severity was
rated using a 0-3 severity scale. The authors described the observed tremor motion as
rhythmic modulations of the folds for most participants, but in one participant, it was
described as rhythmic opening and closing of the vocal folds. Klotz and colleagues
(2004) compared laryngoscopy to voice tremor in 77 participants with tremor spasmodic
dysphonia. They noted that tremor was identified on laryngoscopy in 68 of 77
12
participants (88%). The identification of tremor during laryngoscopy was completed by
one of two laryngologists; specific criteria used to identify the tremor and descriptions of
the movement observed were not provided. Warrick, Dromey, Irish, Durkin, Pakiam, and
Lang (2000) used laryngoscopy to identify tremor in ten participants with vocal tremor.
Tremor activity in the true vocal folds was noted in all 10 participants (100%) in the
medial-lateral direction and in five of 10 participants (50%) in the superior-inferior
direction. Tremor was also noted in the strap muscles of the neck in one participant.
Criteria for identification of tremor were not provided, however. Bove, Daamen, Rosen,
Wang, Sulica, and Gartner-Schmidt (2006) used flexible laryngoscopy with ten
participants with vocal tremor to identify tremor in multiple structures, including the
palate, base of tongue, pharyngeal walls, supraglottis, and true vocal folds. Individual
data were not provided, however, so it was unclear how many participants experienced
tremor in each structure. Sulica and Louis (2010) used the Vocal Tremor Scoring System
created by Bove and colleagues (2006) to assess 34 participants with vocal tremor. They
identified tremor in the palate (30 participants, or 88%), base of tongue (8 participants, or
24%), pharyngeal walls (20 participants, or 59%), vertical movement of the larynx (29
participants, or 85%), supraglottis (32 participants, or 94%), and true vocal folds (34
participants, or 100%).
Tremor activity was recorded in the extrinsic laryngeal muscles in approximately
4 of 9 (45%) reported cases (Koda & Ludlow, 1992; Finnegan et al., 2003). The two
extrinsic laryngeal muscles have been assessed using EMG, the sternothyroid and
thyrohyoid; tremor was identified in at least one of these muscles in five of nine
participants (56%). Koda and Ludlow (1992) recorded EMG from the sternothyroid and
thyrohyoid muscles of three participants with vocal tremor. All three participants
demonstrated rhythmic oscillations in both of these muscles during sustained phonation.
Finnegan, Luschei, Barkmeier, and Hoffman (2003) recorded EMG from the
sternothyroid and thyrohyoid muscles of six participants with vocal tremor. Only one of
13
the six (17%) showed tremor in both muscles during phonation; however, another
participant showed tremor in the sternothyroid alone and a third participant showed
tremor in the thyrohyoid alone. The limited number of participants (and muscles) studied
to date makes it difficult to determine the true prevalence of tremor in the extrinsic
musculature, although it is clear that the extrinsic muscles can be affected by tremor and
contribute to the perception of vocal tremor.
Rhythmic vertical movements of the larynx synchronous with vocal tremor have
been observed in 41 of 56 cases (73%) (Ardran et al., 1966; Brown & Simonson, 1963;
Hachinski et al., 1975; Koda & Ludlow, 1992; Warrick, Dromey, Irish, Durkin et al.,
2000; Sulica and Louis, 2010). Adran, Kinsbourne, and Rushworth (1966) described one
participant with tremor in multiple structures, including vertical oscillations of the larynx.
These oscillations were described as “in sympathy with the tremor elsewhere (Ardran et
al., 1966, pp. 219-220),” but the relationship to the vocal tremor was not described.
Brown and Simonson (1963) made observations of vertical movements of the larynx in
31 participants with vocal tremor. The authors said, “In some patients, the tremor on
sustained phonation was observed to be accompanied by vigorous up-and-down laryngeal
movement synchronous with the oscillations of the tremor (Brown & Simonson, 1963, p.
521),” although the exact number of participants affected was not provided. Hachinski,
Thomsen, and Buch (1975) observed vertical movement of the larynx in two of three
participants with vocal tremor, but did not report whether this movement correlated with
the voice signal. Koda and Ludlow (1992) used direct observation and flexible
laryngoscopy of the larynx to identify vertical laryngeal movement in eight of eight
participants (100%) with vocal tremor during sustained phonation. Warrick, Dromey,
Irish, Durkin, Pakiam, and Lang (2000) used flexible laryngoscopy to observe the larynx
in ten participants with vocal tremor. Vertical laryngeal tremor movements were
observed in one participant (10%). The use of laryngoscopy alone to identify vertical
movement of the larynx may account for the differences between the prevalence of
14
tremor in extrinsic muscles in this study and the previous study (Koda & Ludlow, 1992).
Sulica and Louis (2010) identified vertical global movement of the larynx using flexible
laryngoscopy in 29 of 34 participants (85%).
Most individuals experiencing tremor of the larynx have multiple intrinsic
muscles involved. Koda and Ludlow (1992) reported all eight of the participants (100%)
showed involvement of more than one muscle. Finnegan, Luschei, Barkmeier, and
Hoffman (2003) reported five of six participants (83%) showed tremor in both the
cricothyroid and thyroarytenoid; three participants showed additional involvement of
extrinsic muscles. Hillel reported that 11 of 20 participants (55%) with tremor spasmodic
dysphonia had tremor in multiple intrinsic laryngeal muscles. Klotz, Maronian, Waugh,
Shahinfar, Robinson, and Hillel (2004) found 48 of 59 participants (81%) with tremor
spasmodic dysphonia showed tremor in more than one muscle. Tremor is not often
isolated to a single muscle or structure within the larynx. The distribution of tremor to
other regions outside the larynx has not been well-studied in individuals with vocal
tremor.
Velopharyngeal Musculature
Structures of the velopharyngeal region, including the soft palate and pharyngeal
walls, have been identified as being involved in vocal tremor in 47% of cases for the
pharynx and 78% of cases for the palate (Ardran et al., 1966; Brown & Simonson, 1963;
Hachinski et al., 1975; Lebrun et al., 1982; Warrick, Dromey, Irish, Durkin et al., 2000;
Sulica & Louis, 2010). Brown and Simonson studied the base of tongue and soft palate
through direct examination in 31 participants with voice tremor stemming from a variety
of potential neurologic disorders. They found that “some” of their patients showed tremor
activity of these structures during phonation. Adran, Kinsbourne, and Rushworth (1966)
used x-ray cinematography to identify tremor in the palate of a single adult female with
vocal tremor. Hachinski, Thomsen, and Buch (1975) examined the pharynx and nose in
three participants with vocal tremor. No tremor activity was noted in any of these
15
structures, but it was unclear whether the participants were asked to phonate or otherwise
activate the structures during the exam. Lebrun, Devreux, Rousseau, and Darimont
(1982) examined a single participant with vocal tremor and identified tremor of the
velum during sustained phonation; tremor of the lateral neck walls was noted during
conversation. Warrick, Dromey, Irish, Durkin, Pakiam, and Lang (2000) used flexible
laryngoscopy to identify tremor activity in ten participants with vocal tremor. Tremor
activity was noted in the pharynx in two of 10 participants (20%) and the palate in six of
10 participants (60%). Sulica and Louis (2010) also used flexible laryngoscopy to
identify tremor activity in the palate in 30 of 34 participants (88%) and in the pharyngeal
walls of 20 of their 34 participants (59%).
Velopharyngeal structures, such as the velum and pharyngeal walls, could affect
the resonance of the vocal tract and result in the perception of vocal tremor. No study to
date has examined the effect of velar or pharyngeal tremor on the voice beyond
identifying the presence of tremor in these structures.
Oral Musculature
Structures of the oral region, including the jaw, tongue, and lips, have been
identified as being involved in vocal tremor in 10-30% of cases (Ardran et al., 1966;
Biary & Koller, 1987; Brown & Simonson, 1963; Hachinski et al., 1975; Koller et al.,
1987; Lebrun et al., 1982; Warrick, Dromey, Irish, Durkin et al., 2000) with a limited
number of participants studied. Brown and Simonson (1963) studied the base of tongue
through direct examination in 31 participants with voice tremor stemming from a variety
of potential neurologic disorders. They found that “some” of their patients showed tremor
activity of this structure during phonation. Adran, Kinsbourne, and Rushworth (1966)
used color cinematography, x-ray cinematography, EMG, and direct observation to
examine a single adult female with vocal tremor. Tremor was noted in the jaw and facial
muscles using color cinematography during speech; tremor was also noted in the tongue,
mandible, and larynx on x-ray cinematography. EMG recorded from the left cricothyroid
16
and right hyoglossus muscles showed 5-6 Hz tremor activity at rest, which became
extremely irregular during phonation. The authors in this study concluded, even though
oral tremor was present, that “the interruption of the voice appeared to be due to rhythmic
wide separation of the vocal cords (Ardran et al., 1966, p. 223).” Hachinski, Thomsen,
and Buch (1975) examined the mouth in three participants with vocal tremor. No tremor
activity was noted in any of the structures, but it was unclear whether the participants
were asked to phonate or otherwise activate muscles of the articulators during the exam;
if they did not phonate, tremor would likely not be observed. Hornabrook (1976)
identified jaw and mouth tremor in 44 of 175 individuals (25%) with essential tremor (not
specifically vocal tremor) using direct observation during a general examination.
Specifically, rest tremor was observed in the jaw in 47 of 175 cases (27%), the mouth in
46 of 175 cases (26%), and in “speech” in 14 of 175 cases (8%). Speech tremor was
identified during conversation and structures involved were not specified, so it is unclear
how many individuals with vocal tremor had tremor of the oral structures. Lebrun,
Devreux, Rousseau, and Darimont (1982) used direct examination to study a single
participant with vocal tremor. Tremor activity of the tongue and jaw were noted during
tongue protrusion. Biary and Koller (1987) used direct observation to study 20 patients
with essential tremor of the tongue, ranging from mild to severe. Of these, three had
isolated tongue tremor; all others had associated tremor of the head, hands, or lips, and
only one of the 20 patients reported voice tremor. Koller, Glatt, Biary, and Rubino (1987)
reported two cases of isolated tongue tremor, which was noted during tongue protrusion;
one participant experienced dysarthria on lingual sounds, but no other speech or voice
deficits were reported. Warrick, Dromey, Irish, Durkin, Pakiam, and Lang (2000) used
flexible laryngoscopy to identify tremor activity in ten participants with vocal tremor.
Tremor activity was noted in the tongue in three of 10 participants (30%) and the lips in
one of 10 participants (10%). The authors did not correlate this tremor to the voice
tremor, however. Koller and colleagues (1994) studied 678 patients with essential tremor;
17
of these, 30% had voice tremor, 15% had chin tremor, 5% had tongue tremor. The
authors did not report whether patients who had voice tremor had concurrent chin or
tongue tremor. Mancini, Stracci, Tambasco, Sarchielli, Rossi, and Calabresi (2007)
reported that 12% of the 108 individuals with essential tremor in their study had tremor in
perioral structures, but did not report on specific structures or provide any voice tremor
data.
Oscillations in muscle of the oral region can have a variety of effects on the voice
and speech, but likely have more of an effect on intelligibility than resonance. Tremor of
these structures may result in dysarthria-like symptoms (Biary & Koller, 1987; Koller et
al., 1987). Biary and Koller (1987) described the effects of tongue tremor on speech as
mild-moderate dysarthria in three participants; in one participant, voice disturbance was
reported, but no description of the vocal quality was provided or whether the voice
disturbance was vocal tremor. Koller and colleagues (1987) found that in two participants
with tongue tremor, one experienced dysarthria, while the other had no speech or voice
disturbance.
Rating Severity of Tremor
The severity of tremor can be rated auditorily, based on the voice quality, or
visually, when examining structures through laryngoscopy or direct observation. To date,
only five studies have described tremor severity. Two of the studies rated the severity of
vocal tremor, while the other three studies rated the severity of tremor observed in
various structures of the vocal tract. None of these have correlated the severity observed
visually to the severity noted auditorily.
The severity of vocal tremor has been rated in two studies (Finnegan et al., 2003;
Tomoda et al., 1987). Tomoda, Shibasaki, Kuroda, and Shin (1987) rated the severity of
tremor during voluntary phonation and voluntary expiration on a 0-3 severity scale (0=no
tremor, 1=mild tremor, 2=moderate tremor, and 3=severe tremor) in three cases of vocal
tremor. One participant had mild tremor during both tasks, one had moderate tremor
18
during phonation only, and the third participant had severe tremor during phonation and
moderate tremor during voluntary expiration. The authors did not describe the voluntary
expiration task in any more detail. Finnegan, Luschei, Barkmeier, and Hoffman (2003)
rated severity and regularity of the voice tremor in six participants using a 1-5 scale
(1=mild, 5=severe for the severity and 1=very regular, 5=very irregular for the regularity
of tremor). Tremor severity ranged from 2-5, while regularity ranged from 2-4. The
authors correlated the tremor of the muscle from EMG to the vocal intensity recordings,
but no relationship was identified between the ratings of voice tremor and these
correlations.
The severity of tremor observed in various structures of the vocal tract has been
rated in three studies (Bove et al., 2006; Koda & Ludlow, 1992; Sulica & Louis, 2010)
using laryngoscopy. Koda and Ludlow (1992) visually inspected the true vocal folds and
the entire larynx of eight participants during fiberoptic examination to rate the severity of
tremor using a 0-3 severity scale (0=no tremor, 3=severe tremor). Tasks included
inhalation, exhalation, phonation, and whisper. Seven of eight participants (88%) showed
tremor of the larynx (3 mild, 2 moderate, 2 severe) and all participants showed tremor of
the vocal folds (1 mild, 4 moderate, 3 severe) during phonation. Bove, Daamen, Rosen,
Wang, Sulica, and Gartner-Schmidt developed a Vocal Tremor Scoring System, in which
five second video clips from flexible laryngoscopy were rated by five judges for tremor
severity using a 0-3 severity scale (0=no tremor, 3=severe tremor). Structures rated
included the true vocal folds, supraglottis (false vocal folds, aryepiglottic folds, and
epiglottis), larynx (vertical movement within the neck), pharyngeal walls, base of tongue,
and palate. Individual ratings for each participant were not provided. Results indicated
that individuals who experienced more severe tremor in the vocal folds than the other
structures (grouped together and reported as a mean) responded well to botulinum toxin
injection to the thyroarytenoid muscles, while individuals who experienced less severe
tremor in the vocal folds than the other structures did not respond well to the botulinum
19
toxin injection to the thyroarytenoid muscles. Sulica and Louis (2010) replicated the
study by Bove and colleagues (2006), using the Vocal Tremor Scoring System. Of the 34
participants evaluated, all showed tremor in the true vocal folds (13 mild, 15 moderate, 6
severe). Nearly all participants also showed tremor in the palate, supraglottis, and global
laryngeal movement, generally in the mild or moderate range (palate=18 mild, 10
moderate, 2 severe; supraglottis=8 mild, 16 moderate, 8 severe; global larynx=9 mild, 18
moderate, 2 severe). About half of the participants showed tremor in the pharyngeal
walls, again with mostly mild to moderate severity (11 mild, 5 moderate, 4 severe).
Tremor in the base of tongue was identified in few participants, and was mild (7
participants) or moderate (1 participant).
Studies of the severity of tremor have either examined the vocal tremor severity
or the severity of the tremor observed in the structures of the vocal tract, but none have
related the two. Describing this relationship was the second goal of the current study.
Statement of the Problem
Vocal tremor can be a debilitating disorder, affecting over half a million people in
the United States alone. Treatment of tremor is possible with laryngeal botulinum toxin
injections and possibly behavioral methods, but choosing the most appropriate treatment
or target can be challenging. Knowing the locations of tremor within the vocal tract,
including the respiratory, laryngeal, velopharyngeal, and oral regions, may help
practitioners determine the most appropriate treatment for a particular individual to
maximize response.
A variety of muscles throughout the vocal tract have been suggested as potential
sources of vocal tremor, with the laryngeal muscles most frequently studied. The
literature to date supports intrinsic and extrinsic muscles of the larynx as the primary
location of tremor causing oscillations in the voice signal. The strongest studies, those
that included EMG of multiple laryngeal muscles, indicate that the thyroarytenoid (65%
of cases) and cricothyroid (74% of cases) muscles were affected in most individuals,
20
although all five intrinsic laryngeal muscles were shown to experience tremor (lateral
cricoarytenoid=54%, posterior cricoarytenoid=56%, interarytenoid=16%). Tremor of the
true vocal folds was identified in 80% (120/150) of cases. The extrinsic laryngeal
muscles studied include the thyrohyoid and sternothyroid, and were involved in
approximately half of cases (17/31 or 55%). Respiratory tremor was reported in case
studies, but the actual prevalence remains unclear. When studied, the diaphragm (5/6
cases or 83%), rectus abdominis (3/3 cases or 100%), and sternocleidomastoid (2/3 cases
or 67%) were most often linked to the presence of vocal tremor. Based on the only
prospective study of respiratory tremor (Koda & Ludlow, 1992), approximately 25% of
individuals with vocal tremor may experience respiratory symptoms. Velopharyngeal and
oral tremor have been studied more often than respiratory tremor, but the prevalence also
remains unclear. An estimated 50-75% of individuals may experience velopharyngeal
tremor, including the palate (78%) and pharynx (47%). Approximately 25% of
individuals may experience vocal tremor in oral structures, including the jaw (27%), chin
(15%), tongue (9%), and lips (8%).
The difficulty in determining the true prevalence of respiratory, velopharyngeal,
and oral tremor lies in the limitations of the studies which have reported this
phenomenon. First, most of the studies of these three regions have been case studies,
which limit extrapolation to the general vocal tremor population. Second, many of the
cases in which respiratory, velopharyngeal, or oral tremor activity was recorded, the
oscillations are not correlated to the voice signal, or more frequently, no attempt was
made to correlate the observed tremor to the voice tremor. Third, many of the studies do
not describe the tasks used to identify tremor or the tasks that were chosen may not have
activated the muscles being studied. Tremor observed in structures at rest may not be
correlated to the perception of tremor during speech.
The data available provide some clues to the prevalence of tremor in each region,
but it is not clear how often one could expect to see tremor in each region in a particular
21
participant or group of participants or whether multiple regions may be affected. Most
authors agree that multiple muscles may be involved in vocal tremor. However, most
studies to date examine only one or two regions when describing the location of tremor.
No prospective study has examined the distribution and severity of tremor in the
respiratory, laryngeal, velopharyngeal, and oral regions of a cohort of participants
identified as having voice tremor.
In addition to the lack of information regarding the distribution and severity of
tremor in structures of the vocal tract, the relationship of this information to perceived
severity of vocal tremor has not been reported in any previous study. Three studies to
date have examined the severity of tremor in structures of the vocal tract (Bove et al.,
2006; Koda & Ludlow, 1992; Sulica and Louis, 2010), while two other studies have
described the severity of the voice tremor (Finnegan et al., 2003; Tomoda et al., 1987).
Identifying a relationship between these two parameters may be useful in determining the
most appropriate treatment for individuals with vocal tremor.
The purposes of the current study were to: 1) provide a first step in describing the
distribution and severity of tremor within the respiratory, laryngeal, velopharyngeal, and
oral regions; and 2) relate the distribution and severity of tremor to the voice tremor
severity. First, to better determine the prevalence of tremor in the respiratory,
velopharyngeal, and oral regions in particular, a prospective participant recruitment
procedure was used in which all participants had the respiratory, laryngeal,
velopharyngeal, and oral structures assessed for the presence of tremor. To relate the
voice tremor severity and the severity of tremor within structures of the vocal tract, the
Tremor Index was created and correlated to the severity ratings of the vocal tremor.
The results of this study provide useful information for both the diagnosis and the
treatment of vocal tremor. Inclusion of simple assessments of all four regions can allow
clinicians to efficiently document the distribution and severity of tremor in patients
presenting to the clinic. Identification of tremor within these regions may also determine
22
treatment options. For example, individuals with tremor isolated primarily to the larynx
would likely benefit from laryngeal botulinum toxin injections, while individuals with
tremor widespread throughout the vocal tract may not benefit from a laryngeal botulinum
toxin injection, but rather a behavioral treatment technique or a combination treatment
approach. Improved knowledge of the structures affected by tremor may also help
researchers to develop alternative treatments for vocal tremor focused on the particular
structures affected in each individual.
Hypotheses
To address the two major goals of this study, the following hypotheses were
tested.
Distribution and severity of tremor
Regions affected by tremor
1) Half of the participants will have tremor in more than one region.
2) The laryngeal region will be the most commonly affected region, with
approximately 75% of participants showing tremor. The velopharyngeal region
will be affected in over half of the participants, while the oral and respiratory
regions will be affected in approximately 25% of participants.
Structures affected by tremor
3) All participants will show tremor in more than one structure.
4) The true vocal folds will be the structure most commonly affected by tremor,
with approximately 80% of participants showing true vocal fold tremor. Vertical
movement of the larynx will be present in 75% of participants.
Relating Distribution and Severity of Tremor to Voice tremor Severity
5) Voice tremor severity during sustained phonation will be most correlated to the
observed structural tremor of the true vocal folds.
6) Voice tremor severity during sustained voiceless sounds, such as /s/ or /h/ will
be most correlated to the observed structural tremor of the respiratory region.
23
7) As the distribution and severity of tremor in affected structures increases, the
voice tremor severity will also increase.
24
CHAPTER 2
METHOD
Participants
Twenty adults with vocal tremor (two males, 18 females, mean age=70 years,
range 45-88 years) and two adults with no vocal tremor (one male, one female, mean
age=54 years) participated in this study. Participant characteristics are presented in Table
1. Control participants were recruited through an advertisement in a weekly e-news
release at the University of Iowa. Participants with vocal tremor were recruited from the
Laryngeal Movement Disorders Clinic at the University of Iowa. The diagnosis of vocal
tremor was made based on voice and videolaryngoscopy assessments completed by a
speech-language pathologist and an otolaryngologist during a standard voice evaluation
appointment completed independently and prior to participation in the current study.
Participants were screened for other disorders (i.e., spasmodic dysphonia, muscle tension
dysphonia, and Parkinson’s disease) during the collection of a clinical history, which
included a brief chart review and an interview (Appendix A). Any individuals with signs
of or diagnosis of Parkinson’s disease or cerebellar deficits were excluded from the study.
Individuals with Parkinson’s disease experience primarily rest tremor, which is different
from the postural/action tremor in essential tremor (Elble & Koller, 1995; Jankovic,
1995; Lundy et al., 2002); individuals with cerebellar dysfunction experience primarily
ataxic-like symptoms, which are also different from the tremor of essential tremor
(Ackermann & Ziegler, 1991). Six individuals with spasmodic dysphonia were included;
all six had concurrent symptoms of spasmodic dysphonia and vocal tremor, with the
tremor symptoms more severe than the strain associated with spasmodic dysphonia.
Some authors include tremor as a type of laryngeal dystonia in which greater severity of
tremor is associated with greater irregularity in movements of tremulous structures
(Woodson, Zwirner, Murry, & Swenson, 1991; Hillel, 2001; Klotz, et al., 2004). Thirteen
of the participants had previously received botulinum toxin injections to the larynx for
25
the tremor; however, they were at least three months post-injection to reduce under-
estimation of vocal fold tremor. The two age-matched control participants were included
(one male and one female) to provide a full range of assessment from no tremor to severe
tremor.
Two speech-language pathologists were recruited as judges to rate the voice
tremor and structural tremor in each of the participants. Both judges were selected
because they had experience working with individuals with voice disorders, and in
particular, individuals with laryngeal movement disorders. One judge had 18 years of
experience working with individuals with laryngeal movement disorders, while the other
had three years of experience. Two judges were included to improve reliability of the
subjective ratings performed in the study.
Procedure
The data collection procedure included a clinical exam, respiratory recordings,
audio recordings, and a nasendoscopic evaluation. Each is described in detail below. For
12 participants, all components were completed at one visit. For the other 10 participants,
the clinical exam and Respitrace were completed at a separate visit from the
nasendoscopy and audio recordings due to a change in the procedure after pilot data was
collected from the first 10 participants. Full data sets were obtained from 20 of the 22
participants, with two participants missing the Respitrace and some portions of the
clinical exam because they failed to return after their initial visits during which the pilot
data were collected.
Clinical Exam
The clinical exam included assessment of tremor in specific structures of the
respiratory, laryngeal, and oral regions through direct observation and palpation. The
form used to collect and rate this data during data collection is presented in Appendix B.
The participant was seated in a clinic chair throughout this exam. Each judge
26
independently rated each structure during separate sessions with the participant; therefore
some variability may have existed between productions for the same participant.
To assess respiratory tremor, visual observation and palpation were completed
during four tasks: 1) rest breathing, 2) sustained /h/, 3) sustained /s/, and 4) sustained /a/
at comfortable pitch and volume. The sustained /s/ and /h/ were included to elicit and
isolate respiratory tremor, as the vocal folds are abducted during this sound. The clinician
placed a hand on the participant’s chest in a horizontal position over the mid-section of
the sternum during each of the four tasks to palpate for tremulous anterior-posterior
movements of the chest wall during these productions. Next, the clinician placed each
hand on the lateral walls of the rib cage, one under each axilla in a vertical direction to
palpate for tremulous medial-lateral movements during the same four tasks. The clinician
then placed a hand on the participant’s abdomen in a horizontal position directly over the
navel during the same four tasks to palpate for tremulous anterior-posterior movements of
the abdomen. This position was chosen because the rectus abdominis has been implicated
in respiratory tremor (Tomoda et al., 1987). Finally, the clinician placed each hand on the
lateral abdominal walls in a vertical position between the hip bones and the rib cage to
palpate for medial-lateral movements of the abdomen during the same four tasks. Each
palpation was rated for severity on a 0-3 scale, with no tremor rated as zero and severe
tremor rated as three. The severity rating scale used will be described in more detail later.
Tasks were repeated as needed for the judges to make their ratings; judges made their
ratings with three or fewer repetitions per task. As palpation of tremulous movements
could be affected by the amount of adipose tissue present, body mass index information
from each participant’s medical chart was recorded. Three of the participants had body
mass index values over 30, which is considered obese; the judges did not feel palpation
was limited in any participant, however. Body mass index numbers are reported in Table
1.
27
To assess vertical laryngeal movements, the clinician palpated the larynx within
the neck by placing two fingers over the thyroid and cricoid cartilages of the larynx
during rest breathing, and the production of sustained /s/, /h/, and /a/ at comfortable pitch
and volume. Palpation for vertical movements of the larynx was rated for severity using
the 0-3 scale. Tasks were repeated as needed for judges to make their ratings; judges
made their ratings with three or fewer repetitions per task.
To assess for tremor of oral structures, the jaw, lips, and tongue were observed
during rest breathing, sustained /h/ and /a/ at a comfortable pitch and volume. The jaw
and lips were also observed for tremor during sustained /s/, but the tongue was not visible
during the production of this sound. Each observation was rated for severity using the 0-3
scale and tasks were repeated as needed for judges to make their ratings; judges made
their ratings with three or fewer repetitions per task.
Respitrace Recordings
Palpation has not been used to assess respiratory tremor in any studies to date,
while Respitrace has been shown to identify tremulous movements of the respiratory
region in one study (Koda & Ludlow, 1992). Therefore, Respitrace was included for
comparison to the palpation data; if the palpation method was as sensitive as Respitrace,
it would be more efficient and less invasive for use with tremor patients in the future.
Respiratory recordings of rest breathing, sustained /s/, /h/, and /a/ were obtained using
Respitrace (Ambulatory Monitoring, Inc., Ardsley, NY). Two elastic bands (Respibands)
were placed around the participant’s body. The upper band was placed around the chest
just under the axilla, with the coil pins directed downward. The lower band was placed
around the abdomen, between the lowest vertebral rib and the iliac crest, with the coil
pins directed upward. The coil pins were inserted into the oscillator cable, which was
then connected to the Calbox. The Calbox converted the changes in inductance associated
with changes in cross-sectional area of the abdomen and chest to voltages. The Calbox
28
was connected to a laptop computer (Dell Latitude CPX) for recording the voltages using
Windaq (Dataq Instruments, Inc., Akron, OH).
The Respitrace was calibrated for each participant using an isovolume task
(breathing into a Spirobag with a volume of 800 cc). Each participant exhaled into the
Spirobag to fully inflate it, then inhaled to fully deflate the bag to produce changes in the
abdominal and chest diameter associated with a known volume of air. This was repeated
five times. Following calibration, each participant produced a 10 second period of rest
breathing, and two 5-second repetitions of sustained /s/, /h/, and /a/ at comfortable pitch
and volume. Respitrace data were recorded in Windaq (Dataq Instruments, Inc., Akron,
OH), with each task labeled within the recorded waveform as it was completed.
Audio Recordings
To obtain measures of the voice tremor severity, audio samples were transduced
by a lapel microphone (RadioShack 33-3013) placed 15 cm from the participant’s mouth
and recorded on a digital voice recorder (Olympus WS-100 or WS-110, sampling rate of
44.1 kHz) during production of sustained /s/, /h/, and three repetitions of sustained /a/ at a
comfortable pitch and volume, with the first production held as long as possible for
determination of maximum phonation time.
Nasendoscopic Evaluation
Flexible nasendoscopy was completed to provide a view of the larynx,
oropharynx, and velopharyngeal mechanism during speech production. For the
nasendoscopic examination, the participant was seated upright in the clinic chair. A
topical anesthetic (4% lidocaine with phenyl epinephrine) was used to prepare the nasal
passage according to standard otolaryngology practice. An endoscope (Pentax FNL
10RP3) was placed transnasally and advanced to view the superior surface of the palate
and velopharyngeal walls. While viewing the palate, the participant was asked to sustain
/s/, /h/, and /i/ at a comfortable pitch and volume, as well as to breathe normally for five
seconds. After completing these tasks, the endoscope was advanced below the
29
velopharyngeal port to view the base of the tongue, pharynx, and larynx. In this view, the
participant again was asked to sustain /s/, /h/, and /i/ at a comfortable pitch and volume,
and to breathe normally for five seconds. Participants were asked to repeat any task that
was sustained for less than five seconds or in which a structure was obscured, as tolerated
by the participant.
Nasendoscopy data were digitally recorded (30 frames per second) to the
endoscopy software, EndoPro (EndoPRO Management Systems v6.5.1, Pentax Medical
Company, 2005) for seven participants, and to Olympus (nStream G3, ImageStream
Medical) for the remaining participants; two software programs were used because the
University of Iowa Otolaryngology department converted to the new Olympus software
during the course of the study. The software in EndoPro only allowed 30 seconds of
video to be recorded at a time and did not record audio. The Olympus endoscopy system
allowed continuous recording of the entire procedure with simultaneous audio recordings.
Data Measurement
Ratings of the severity of tremor during the clinical exam were made at the time
of data collection, and recorded on the Clinical Tremor Evaluation Form (Appendix B),
using a 7-point severity scale ranging from no tremor (rating of 0) to severe tremor
(rating of 3). Ratings of full and half points were allowed, to provide a range of no tremor
(0), slight/inconsistent tremor (0.5), mild tremor (1), mild-moderate tremor (1.5),
moderate tremor (2), moderate-severe tremor (2.5), and severe tremor (3). The 7-point
severity scale was chosen to provide adequate differentiation between participants’
severity levels, while improving agreement between and within raters (Yiu & Ng, 2004).
Respiratory structures rated include anterior-posterior and medial-lateral movements of
the rib cage and abdomen. Vertical movement of the larynx was rated for superior-
inferior oscillations. Oral structures rated include the jaw, tongue, and lips; all three
structures were rated for superior-inferior oscillations.
30
Respitrace waveforms were recorded in Windaq (Dataq Instruments, Inc., Akron,
OH). The waveform was visually inspected by the author for oscillations superimposed
upon the respiratory waveform. Respitrace waveforms were difficult to interpret, so
ratings were made using the descriptors positive, possible, and negative for the presence
of tremor. Positive ratings were made when oscillations of 3-8 Hz were superimposed
upon the respiratory waveform. The judges discussed any waveforms that were
inconclusive to reach a consensus on the classification of positive, possible, or negative
presence of tremor.
The audio recordings were converted from Windows Media Audio (wma) format
to waveform audio file format (.wav) for analysis and storage using dBpoweramp Music
Converter (illustrate, r10.1). Recordings were converted to wav format for ease of
playback on any computer and for potential acoustic analyses. Audio recordings were
divided into individual clips using Audacity (SourceForge.net, Version 1.3.12-beta). For
each sustained /s/, /h/, and /a/, a three-second portion of the sound selected from the
middle of the production was used for rating. Although some participants occasionally
showed tremor that varied slightly in severity from the beginning to the end of a sample,
a representative portion was obtained within each clip; no participant showed tremor only
at the beginning or end of a production, so clips from the middle portion were deemed
acceptable. A three-second portion of the sound was chosen to standardize the samples
and prevent bias toward more severe ratings in participants with shorter phonation times.
A total of 78 clips were created (three tasks for each of 22 participants, plus 12 repeated
clips for reliability).
Audio clips were randomized and stored in two PowerPoint presentations on a
flashdrive (Patriot Xporter Razzo USB drive, 8GB) without identifying information about
the participants. The judges used the 0-3 severity scale to rate each audio clip. The 0-3
severity scale has been used previously in rating the voice tremor severity (Koda &
Ludlow, 1992). The 0-3 severity rating scale and a 100 mm visual analog scale (VAS)
31
were piloted with 10 participants by this author. It was noted that significant drifting
toward higher ratings occurred when multiple samples were presented when rating audio
samples using the VAS. In addition, the 7-point equal interval scale allowed adequate
range of severities for describing the audio samples. Prior to rating the clips, the judges
reviewed descriptions associated with each severity rating (these descriptions are
included on the Audio Rating Form in Appendix C). The judges rated the audio clips over
two 20-minute listening sessions in which half of the clips were presented in each session
(for rating form, see Appendix C); clips included twice for reliability purposes were
randomized to the opposite listening session so the same two samples did not occur
together. Judges listened to each clip as many times as necessary for rating, with ratings
completed in three or fewer repetitions.
Video clips of each speech sound maneuver from the nasendoscopy were created
using Windows Movie Maker (Microsoft, Version 2.1). Three seconds from the mid-
section of each sound production were selected and saved as an individual clip. The mid-
section of the production was chosen to avoid movements associated with onset and
offset positioning of articulators for each sound. Three second clips were chosen to
provide a standardized amount of time for the judges to view movement of the structures
and based on some participants’ inability to sustain sounds for five or more seconds.
These clips were saved without sound associated with them to prevent bias from auditory
input during the judges’ rating. A total of 196 video clips were created (four tasks in two
views for each of 22 participants plus 20 repeated clips for reliability).
Video clips from the laryngoscopy were randomized and stored in two
PowerPoint presentations on a flash drive (Patriot Xporter Razzo USB drive, 8GB)
without identifying information about the participants. The judges used the same 0-3
seven-point severity scale ranging from no tremor (rating of 0) to severe tremor (rating of
3) to assess the video clips. Prior to rating the clips, the judges reviewed descriptions
associated with each severity rating (these descriptions are included on the Video Rating
32
Forms in Appendices D and E). The judges rated the video clips over four 45-minute
viewing sessions in which one-quarter of the clips were presented during each session;
two sessions included clips in the palatal view and the other two sessions included clips
in the laryngeal view. Clips were viewed as many times as necessary to allow rating of all
structures, with ratings completed in eight or fewer repetitions. More repetitions were
required for video clips than audio clips due to the need to rate multiple structures in each
video clip.
Judges rated two structures in the palatal view, including the superior surface of
the velum, and the nasopharyngeal walls, which included movement of the Eustachian
tube. The superior surface of the velum was defined as the structure forming the floor of
the posterior nasal cavity and was rated for superior-inferior oscillations. The lateral
nasopharyngeal walls were defined as the tissue connecting the velum to the roof of the
nasal cavity and posterior pharyngeal wall and were rated for medial-lateral oscillations.
The velum and nasopharyngeal walls together were defined as the velopharyngeal region.
Judges rated four structures in the laryngeal view, including the true vocal folds,
supraglottic structures, the base of tongue, and the hypopharyngeal walls. The true vocal
folds were defined as the tissue stretching from (and including movement of) the
arytenoids to the anterior commissure and were rated for medial-lateral and/or anterior-
posterior oscillations. The supraglottic structures included the false vocal folds,
aryepiglottic folds, and the epiglottis and were rated for medial-lateral and/or anterior-
posterior oscillations. The base of tongue was defined as running from the vallecula to
the edge of the viewable area of the laryngoscopic clip and was rated for anterior-
posterior oscillations; the base of tongue was obscured from view during sustained
phonation, so was only rated during sustained voiceless sounds and rest breathing. The
hypopharyngeal walls were identified as the lateral and posterior walls of the vocal tract,
running from one side of the base of tongue/epiglottis to the other and were rated for
medial-lateral and/or anterior-posterior oscillations. These structures were chosen for
33
rating based in part on the Vocal Tremor Scoring System by Bove, et al. (2006), where
raters were asked to rate the palate, base of tongue, pharyngeal walls, supraglottis, and
true vocal folds in laryngoscopy clips of individuals with tremor. Results of their study
indicated these structures were the most salient for identifying tremor in the pharynx and
larynx during laryngoscopy. All of these structures, in addition to the vertical laryngeal
movement, were included in the laryngeal region.
Reliability
Intrajudge reliability was determined through re-evaluation of 10% of randomly
chosen video clips and audio clips. For the video clips, 20 clips were selected and
included twice in the group of clips to be rated. Judges were not aware of which clips
were repeated; repeated clips were presented in the opposite PowerPoint from the original
clip. A similar process was used with the audio clips, in which 16 clips were selected and
included twice for rating, again in the opposite PowerPoint presentation. An Intraclass
Correlation Coefficient (ICC) and Cronbach’s Alpha were used to determine intrajudge
reliability for both the audio and video ratings. Interjudge reliability was determined
through Pearson correlation coefficients and percent agreement for all ratings. Percent
agreement was calculated for exact agreement between the judges, as well as agreement
within 0.5 (e.g., ratings of 1 (mild) and 1.5 (mild-moderate)). The rate of occurrence and
severity ratings from each judge were plotted and compared to identify any discrepancies.
Analysis
Ratings of the video and audio clips were compiled in spreadsheets. For two
participants, only one judge rated structures on palpation and observation due to the
participants not returning for a second visit at the clinic. These data are included but
marked for identification. For all other participants, mean severity ratings were
determined by taking the average of the ratings by the two judges in each task. Means are
reported.
34
Regions Affected by Tremor
Rate of occurrence histograms were generated to show the location of tremor
throughout the vocal tract in the participants during sustained phonation, sustained /s/,
sustained /h/ and rest breathing to address the first and second hypotheses. A region was
considered to be “affected” by tremor if the mean tremor rating was at least 0.75 in at
least one of the structures rated for that region. The respiratory region included the
anterior and lateral movements of the chest and abdomen. The laryngeal region included
the true vocal folds, supraglottic structures, vertical laryngeal movement, and
hypopharyngeal walls. The velopharyngeal region included the velum and
nasopharyngeal walls. The oral region included the jaw, tongue, and lips.
Structures Affected by Tremor
To address the third and fourth hypotheses, the number of structures rated as
having tremor for each task was totaled and displayed in a scatterplot. Participants were
grouped by the severity of the voice tremor. The rate of occurrence of tremor in each
structure was displayed in a histogram.
Severity of Tremor Throughout the Vocal Tract
Mean severity ratings for each structure and task were organized into tables. Line
charts were generated by plotting the average severity of tremor in all structures;
participants were grouped by severity of the voice tremor for each task. Rate of
occurrence and severity data were combined into histograms with bar height indicating
rate of occurrence of tremor and color indicating severity of tremor in all speech
structures for each group.
Relating Distribution and Severity of Tremor to Voice Tremor Severity
To address hypotheses five and six, three methods were used. First, Pearson
correlation coefficients were calculated between structural severity ratings and voice
tremor severity ratings using SAS (SAS Institute Inc., Cary, NC); correlation coefficients
were compiled in tables. Statistical significance for each correlation was identified using
35
a Bonferroni correction for multiple tests at p < 0.0038 (alpha = 0.05 / 13 structures
analyzed = 0.0038) for sustained /i/ and /s/, and at p < 0.0033 for sustained /h/ (alpha =
0.05 / 14 structures analyzed = 0.0036). Correlations between structures were also
calculated to provide an estimate of the amount of co-variability in the severity ratings of
the structures assessed. Correlation coefficients 0.1 ≤ r <0.3 indicated a weak correlation,
0.3 ≤ r < 0.5 indicated a moderate correlation, and r ≥ 0.5 indicated a strong correlation.
The second method to relate distribution and severity of tremor in structures of
the speech mechanism to voice tremor severity was a regression analysis for variable
selection using SAS (SAS Institute Inc., Cary, NC). This method was used to identify
which structures contributed most to the severity of the voice tremor. The stepwise
selection method was used to determine the variables that accounted for the greatest
proportion of the variance without overlapping. Variables selected in this manner were
then included in a multiple regression analysis, described below. To accurately utilize this
method and avoid violating assumptions for the analysis, the number of participants
needed to be greater than the number of structures included in the analysis (at least 15
participants were necessary). Because many participants were missing data for a variety
of reasons in the sustained /h/ task (e.g., the task wasn’t completed, a structure wasn’t
visible on endoscopy), the analysis was not completed for this task.
To summarize the distribution and severity of structures affected by tremor for
comparison against the voice tremor severity ratings, the Tremor Index was calculated by
multiplying the percentage of structures affected by tremor by the mean severity of
tremor in those affected structures. Values for the Tremor Index could range from 0-300.
A value of 0 would indicate no tremor in any structure observed. A value of 300 would
indicate severe tremor in every structure. The Tremor Index was calculated for each
participant for each task and was then plotted against the mean voice tremor severity
rated by the judges for each task.
36
Finally, several multiple regression analyses were completed using SAS (SAS
Institute Inc., Cary, NC) to describe the relationship between the distribution and severity
of tremor throughout the speech structures and voice tremor severity. The first model
included all variables assessed for each task. The second model included any variables
identified by the stepwise variable selection procedure. The third model included only the
Tremor Index. For all analyses, the regression equation, R2, and p-values are reported.
Analyses were completed separately for each task (i.e., sustained phonation, sustained /s/,
and sustained /h/).
37
Table 1. Participant demographics.
Gender
Age
Body
Mass
Index
Tremor
Severity in
Connected
Speech
Presence
of SD
Family
History of
tremor
Effect on
Daily Life
(1=none,
10=severe)
Current
Medications
for Tremor
Prior
Botox
F50 22.5 None None No 0 None No
M58 None None No 0 None No
F65 35.4 Slight Yes Yes Not rated None Yes
F72 27.3 Slight None No 5 Primidone Yes
F66 25.9 Mild None No 9 None No
F45 22.9 Mild-
Moderate Yes Unknown 7 None Yes
F57 23.2 Mild-
Moderate None Yes 8 None No
F62 21.6 Mild-
Moderate None No 8 None No
F77 25.6 Mild-
Moderate None No 5 None Yes
F86 22.5 Mild-
Moderate None Yes 10 None Yes
F67 23.9 Moderate None No 1 None No
F69 21.1 Moderate Yes No 8 None Yes
F79 24.2 Moderate Yes No 4 None No
F52 31.8 Moderate None No 7 None No
F61 27.9 Moderate-
Severe Yes Unknown 9 Arcane Yes
F80 32.3 Moderate-
Severe None Yes 7
Primidon,
Remeron Yes
F84 24.7 Moderate-
Severe None Unknown 9 None Yes
M84 20.5 Moderate-
Severe None Unknown 6 None No
F88 27.0 Moderate-
Severe Yes No 3 None Yes
M62 24.3 Severe None Yes 7 Propranolol Yes
F71-1 22.4 Severe None No 10 None Yes
F71-2 27.9 Severe None Yes 3 Propranolol Yes
38
CHAPTER 3
RESULTS
Mean ratings of the distribution and severity of tremor in speech structures during
sustained phonation of /i/ for all participants are presented in Table 2. The table is
organized vertically by the severity of the voice tremor during sustained /i/ (listed in the
final column), with control participants at the top and individuals with severe voice
tremor at the bottom. Participant identification numbers are listed in the first column, and
indicate participant gender and age. The next 13 columns provide mean severity ratings
in each structure assessed, beginning at the far left with inferior structures in the
respiratory region and moving superiorly to the larynx, then velopharynx, and finally the
oral region at the far right.
Mean ratings were grouped by severity into the categories of “no tremor” (mean
less than 0.75), mild (0.75 ≤ x < 1.25, shaded light blue), mild-moderate (1.25 ≤ x < 1.75,
shaded blue), moderate (1.75 ≤ x < 2.25, shaded yellow), moderate-severe (2.25 ≤ x <
2.75, shaded orange), and severe (x ≥ 2.75, shaded red). Ratings of less than 0.75 were
identified as no tremor, based on the definitions of each severity level provided on the
rating sheets; these definitions stated that a rating of 0.5 indicated inconsistent
movements that might be tremor, while a rating of 1 indicated barely visible tremor.
Therefore, individuals with a mean rating of 0.75 were rated as having at least mild
tremor by at least one judge.
The three columns to the right of the bold line indicate the number of structures
rated, number of structures affected, and the percentage of structures affected. Not all
participants had all 13 structures rated, so the percentage of structures affected was
computed to allow comparisons across participants. Next, the average severity of tremor
in affected structures was calculated by taking the mean of the structures showing tremor
ratings of 0.75 and greater. For example, for participant F69, two structures were affected
during sustained phonation (Table 2), so the mean severity of the affected structures is
39
the average of the severity in the true vocal folds (1.5) and the supraglottic structures
(1.25). The next column to the right is the Tremor Index. This value was calculated by
multiplying the two previous columns (the percentage of structures affected and the
average severity of the affected structures). It is a number meant to summarize the
distribution and severity of tremor and can range from 0-300, with larger numbers
indicating more widespread and more severe tremor.
At the bottom of the table, summary data for each structure is presented. First, the
number of participants with tremor in each structure is listed, followed by the average
severity of tremor across all participants for each structure and mean severity values for
each group of participants (mild voice tremor, moderate voice tremor, severe voice
tremor). The final row provides the correlation between the two judges’ ratings.
Mean severity ratings were calculated from the ratings of the two judges, except
for those in bold, which represent the ratings from judge one only. Two participants (F52
and F67) completed only the pilot portion of the study, and therefore were assessed by
only one judge for all respiratory and oral structures, as well as the vertical laryngeal
movement. Boxes marked with an asterisk indicate that ratings were not completed for
that structure in that participant. For these same two participants, lateral movement of
respiratory structures was not rated, as the assessment of lateral movements was added
after the pilot portion of the study. Laryngeal and velopharyngeal ratings are missing for
some participants because the structures were not visible in the video clips from the
endoscopy during a particular task.
Two control participants were recruited for the study to provide a range of tremor
which included a normal, no tremor condition. Initially, the video clips for the control
participants were rated as having tremor in the velopharyngeal region; after further
review, the judges determined that what was rated as tremor was actually positioning of
structures surrounding the velopharyngeal port. As a result, the judges re-rated all
participants’ velopharyngeal structures using the movement in the control participants as
40
a baseline. The velopharyngeal ratings reported in this dissertation are based on those re-
ratings. The control participants were rated as having no voice tremor and no tremor in
any structure included in the study. Respitrace also showed no tremor during any task in
the control participants. The control participants’ data are included in Table 2, and were
included in the correlations and regression analyses.
The data in Table 2 provides the basis for the following graphs which will be
used to illustrate the findings regarding the distribution and severity of tremor in the
speech structures of the respiratory region, larynx, velopharynx, and oral region and how
tremor in these structures is related to the perception of voice tremor. Findings will be
presented by task, beginning with sustained phonation.
Sustained Phonation
Tremor distribution. As seen in Figure 1, the distribution of tremor, in terms of
the number of regions affected by tremor, tended to increase with the severity of voice
tremor during sustained /i/ from mild (mean = one region) to moderate (mean = two
regions) to severe (mean = three regions). The respiratory region included anterior and
lateral movements of the chest and abdomen. The laryngeal region included the true
vocal folds, supraglottic structures, vertical laryngeal movement, and the hypopharyngeal
walls. The velopharyngeal region included the velum and nasopharyngeal walls. The oral
region included the jaw, tongue, and lips. A region was defined as affected if at least one
of the structures of the region received mean tremor ratings of at least 0.75; structures and
regions affected by tremor were shaded in Table 2 and correlate to the regions affected in
Figure 1. Black bars indicate tremor within the laryngeal region, which was affected in
all but one participant. This participant had very mild voice tremor which was perceived
during voicing, but was not apparent in any structure during assessment which was
recorded separately from the audio recordings. Five participants with vocal tremor (25%)
showed tremor restricted to the laryngeal region, which included true vocal folds,
supraglottic structures, vertical laryngeal movement and hypopharyngeal walls. Fourteen
41
participants with vocal tremor (70%) showed tremor in at least two regions. Four
participants with vocal tremor (20%) showed tremor in all four regions. The laryngeal
region was affected in 95% of participants with vocal tremor. The velopharyngeal,
respiratory, and oral regions were each affected in 40% of the participants with vocal
tremor (8/20).
As shown in Figure 2, the distribution of tremor, in terms of the number of
structures affected by tremor, tended to increase with the severity of voice tremor from
mild (mean = three structures) to moderate (mean = five structures) to severe (mean =
eight structures). Each data point represents an individual participant with vocal tremor,
while filled data points indicate group means. Those with mild voice tremor showed
tremor in less than half of the structures assessed, while most of those with severe voice
tremor showed tremor in more than half of the structures.
Figure 3 shows tremor occurred most often in structures of the laryngeal region,
including the supraglottic structures (95%), hypopharyngeal walls (94%), true vocal folds
(90%), and vertical laryngeal movement (65%). The structures listed on the x-axis of the
figure are organized based on proximity to the larynx, which is located in the center of
the axis. Structures closer to the larynx tended to show tremor more frequently than
structures further from the larynx (e.g., lips, lateral abdominals). Those with mild voice
tremor only showed tremor in structures of the larynx and velopharynx.
Tremor severity. Figure 4 shows that tremor was rated as most severe in
structures near or in the larynx, including the hypopharyngeal walls (mean = 2.1),
supraglottic structures (mean = 1.7), and true vocal folds (mean = 1.6). Individuals with
severe voice tremor showed greater mean severity ratings in every structure than
individuals with moderate voice tremor and mild voice tremor, respectively. For all three
groups, tremor severity in the respiratory and oral regions was generally mild (mean
ratings ≤ 1).
42
Respiratory Structures Affected by Tremor During /i/
Tremor distribution. Figure 3 shows tremor distribution within the respiratory
region was identified more frequently in the chest (affecting 35% in anterior chest and
33% in lateral chest) than the abdomen (affecting 20% in anterior abdominals and 17% in
lateral abdominals). Table 2 shows tremor in respiratory structures occurred more often
in participants with severe voice tremor than those with moderate voice tremor; none of
the participants with mild voice tremor demonstrated tremor in the respiratory structures.
Tremor severity. Figure 4 shows tremor severity within the respiratory region was
generally mild (group means ≤ 1). Mean tremor ratings for the respiratory structures were
presented in Table 2. Individuals with severe voice tremor showed greater severity across
all structures in this region than individuals with mild or moderate voice tremor. Only
three participants were rated as having severity of greater than one in any structure in the
region.
Laryngeal Structures Affected by Tremor During /i/
Tremor distribution. Figure 3 shows tremor within the laryngeal region was
identified most often in the supraglottic structures (19/20 or 95%), hypopharyngeal walls
(16/17 or 94%), and true vocal folds (18/20 or 90%). Vertical laryngeal movement was
observed in over half of the participants with vocal tremor (13/20 or 65%).
Tremor severity. Figure 4 shows tremor severity was generally in the mild to
moderate range (overall mean ratings between 0.91 for the vertical laryngeal movement
and 2 for the hypopharyngeal walls). Mean tremor ratings for the laryngeal structures
were presented in Table 2. Similar to the respiratory structures, the participants with
severe voice tremor showed greater severity of tremor across all structures of the
laryngeal region (mean severity of laryngeal structures = 1.77) than participants with
mild (mean severity of laryngeal structures = 1.04) or moderate voice tremor (mean
severity of laryngeal structures = 1.52). The greatest severity was noted in the
43
hypopharyngeal walls for all groups. Most ratings of moderate-severe or severe tremor
occurred in the structures of the laryngeal region (orange and red boxes in Table 2).
Velopharyngeal Structures Affected by Tremor During /i/
Tremor distribution. Figure 3 shows tremor within the velopharyngeal region was
identified in the velum in seven of the 20 participants with vocal tremor (35%) and lateral
nasopharyngeal walls in four of the 20 participants with vocal tremor (20%). Over half of
the participants with vocal tremor demonstrating tremor in the velum were individuals
with severe voice tremor.
Tremor severity. Figure 4 shows tremor in the velopharyngeal structures was
generally mild (group means ≤ 1). Mean tremor ratings for the velopharyngeal structures
were presented in Table 2. Participants with more severe voice tremor had greater
severity ratings in the velum and lateral pharyngeal walls, although this was generally
mild-moderate in nature (Figure 4). Two participants demonstrated mild-moderate
tremor in the velum (F77 and F57) or velum and lateral pharyngeal walls (F66 and F80),
while one participant demonstrated moderate tremor in the velum and lateral pharyngeal
walls (F71).
Oral Structures Affected by Tremor During /i/
Tremor distribution. Figure 3 shows tremor within the oral region was identified
more often in the jaw (7/20 or 35%) and tongue (4/20 or 20%) than the lips (2/20 or
10%). Oral tremor was only identified in individuals with moderate or severe voice
tremor.
Tremor severity. Figure 4 shows tremor was generally mild in nature in all oral
structures (mean ratings ≤ 1). Mean tremor ratings for the oral structures were presented
in Table 2. Those with severe voice tremor showed slightly greater severity ratings in the
jaw and tongue than those with moderate voice tremor (Figure 4). Only one participant
was rated as having moderate tremor in the jaw (F71-2). Mild-moderate tremor was
44
identified in the jaw and tongue of one participant (F80) and in the tongue of another
participant (F71).
Distribution and Severity of Tremor in Structures as a Function of
Voice Tremor Severity During Sustained Phonation
Tremor occurred more often and with greater severity in the larynx than other
structures (Figure 5) for all groups (i.e., mild, moderate, and severe voice tremor). Half
of the participants with vocal tremor showed tremor in all four structures of the region.
However, tremor was also often identified in the structures outside the larynx.
Specifically, the chest, velum, and the jaw were rated as having tremor in 35% of the
participants with vocal tremor. The closer a structure was to the larynx, the more likely it
was affected by tremor (Figure 5) and the more likely it was affected with greater
severity. Individuals with mild voice tremor only showed tremor in structures of the
larynx and velopharynx. Individuals with moderate voice tremor showed more structures
outside the larynx affected by tremor, but the greatest severity was found in the larynx.
Individuals with severe voice tremor showed tremor in nearly all structures, with some
structures outside the larynx rated as mild-moderate in severity.
Relating Distribution and Severity of Tremor to Severity of Voice Tremor
The relationship between the distribution and severity of tremor in structures of
the vocal tract and the voice tremor was assessed using three methods. First, Pearson
correlation coefficients were calculated between each structure and the voice tremor to
determine if one or more structures seemed to be significantly related to the severity of
the voice tremor. Second, the Tremor Index combined the distribution and severity of
tremor throughout the vocal tract into a single number to be compared to ratings of voice
tremor. Third, a stepwise variable-selection regression analysis was completed to help
determine which structures contributed most to the severity of the voice tremor. Multiple
regression models to predict the severity of the voice tremor were then created with 1) all
45
variables, 2) vertical laryngeal movement and supraglottic structures, and 3) Tremor
Index.
Pearson correlations. Table 3 shows that Pearson correlation coefficients
between tremor severity ratings for each structure and the voice tremor severity ratings
were strong for vertical laryngeal movement (r = 0.69, p = 0.0003) and the supraglottic
structures (r = 0.69, p = 0.0004). Pearson correlation coefficients were calculated using
SAS (SAS Institute Inc, Cary, NC). Statistical significance was defined as p < 0.0038,
using a Bonferroni correction to account for 13 comparisons (alpha of 0.5 / 13 = 0.0038).
The correlations for the vertical laryngeal movement and supraglottic structures were the
only correlations to reach statistical significance.
Table 4 shows that ratings of tremor severity in structures within each region
were moderately to strongly correlated (e.g., lateral abdominals and anterior abdominals,
r = 0.85, p < 0.0001), as shown by the high Pearson correlation coefficients within the
bold boxes. Pearson correlation coefficients were calculated between all structures using
SAS (SAS Institute Inc., Cary, NC). These correlations describe how closely related
ratings of tremor severity were between any two structures. Several interesting
correlations were identified, and these are highlighted within the table. The anterior chest
movement was strongly correlated with the lateral nasopharyngeal walls (r = 0.57, p =
0.006). The vertical movement of the larynx was only moderately correlated with
laryngeal structures (other than the hypopharyngeal walls), but strongly correlated with
movement of lateral chest (r = 0.68, p = 0.001), anterior chest (r = 0.63, p = 0.002), and
the tongue (r = 0.60, p = 0.003). Severity in structures of the velopharyngeal region were
strongly correlated with movement of the tongue (velum, r = 0.52, p = 0.01; lateral
pharyngeal walls, r = 0.64, p = 0.0013). The importance of these relationships will be
addressed in the discussion section.
Tremor Index. As shown in Figure 6, the Tremor Index, a combination of the
distribution and severity of the tremor within structures of the vocal tract, was higher in
46
participants with severe voice tremor (mean = 84) than participants with moderate voice
tremor (mean = 55) or participants with mild voice tremor (mean = 34). The Tremor
Index was calculated by multiplying the percentage of structures affected by the severity
in those affected structures. This number was then compared to the mean voice tremor
ratings for sustained phonation. Table 2 displays the Tremor Index and voice tremor
ratings for each participant in the final two columns.
Regression Analysis. A stepwise variable selection regression analysis identified
the vertical laryngeal movement and the supraglottic structures as the structures
contributing most to the severity of voice tremor. This analysis was completed using SAS
(SAS Institute Inc., Cary, NC). In the stepwise variable selection method, the first
variable was selected based on the correlation with the voice tremor rating. Then, a
second variable was chosen to maximize the fit of the model, which includes identifying
variables that co-vary. Following this step, the variables were reassessed and removed if
they no longer contributed significantly to the model. This process continued until the
best model was chosen, which included only the vertical laryngeal movement and the
supraglottic structures.
A multiple regression analysis including the vertical laryngeal movement and
supraglottic structures was statistically significant (R2 = 0.60, F = 16.17, p < 0.0001); the
vertical laryngeal movement and supraglottic structures account for 60% of the variance
in voice tremor severity. These structures were included in the model based on the
stepwise variable selection analysis described above. Another regression analysis,
including only the Tremor Index, was also significant (R2 = 0.52, F = 23.34, p<0.0001);
in other words, the Tremor Index accounts for 52% of the variance in voice tremor
severity. A third analysis, including all structures assessed, was not significant (R2 =
0.28, F = 1.41, p=0.59). Regression equations for all three models are presented in Table
5.
47
Does Voice Tremor Severity Increase With Age?
Figure 7a shows the severity of voice tremor was greater for individuals over the
age of 75 (mean = 2.25) than individuals under age 65 (mean = 1.8) or individuals
between 66 and 75 (mean = 1.5). All of those over age 75 had voice tremor rated
moderate, moderate-severe, or severe. Those in the under 65 and the 66-75 groups had
more variable voice tremor severity, ranging from mild to severe. Figure 7b shows the
Tremor Index, the composite measure of tremor distribution and severity, was greater for
individuals over the age of 65 (mean for 66-75 years = 67.3, mean for over 75 years =
67.7) than individuals under age 65 (mean = 41).
Sustained Voiceless Sounds
The sustained voiceless sounds /s/ and /h/ were included as tasks in the study to
try to isolate tremor within the respiratory region. Mean severity ratings for these tasks
are presented in Table 6 (sustained /s/) and Table 7 (sustained /h/). The tables are
organized in the same manner as Table 2, except that the order of the participants is
organized by severity of tremor in /s/ and /h/, respectively. Note that not all participants
with vocal tremor on /i/ demonstrated perceptible voice tremor during these tasks; in fact,
for sustained /s/, 55% (11/20) had no voice tremor and for sustained /h/, 60% (12/20) had
no voice tremor. Also, many participants are missing data for the true vocal folds and
supraglottic structures during sustained /h/ due to approximation of the epiglottis and
pharyngeal wall.
Figure 8 shows the number of regions affected by tremor was greater during
sustained phonation than any other task, but that tremor still tended to affect more regions
in individuals with greater severity of the voice tremor during each task. For sustained /s/
(Figure 8b), the number of regions affected increased from no perceptible tremor and
mild tremor (mean = 0.8 regions) to moderate and severe tremor (mean = 2-3 regions).
The number of regions affected by tremor also tended to increase with the severity of the
tremor noted during sustained /h/ (Figure 8c) from no perceptible tremor (mean = 0.8
48
regions) to mild tremor (mean = 1.2 regions) to moderate tremor (mean = 2 regions).
Black bars indicate tremor within the laryngeal region, which, similar to sustained
phonation, was the most frequently affected region for sustained /s/ (70% of participants),
and /h/ (40%). Tremor within the velopharyngeal region occurred in 40% of participants
during sustained /h/, similar to sustained phonation, but was much less prevalent during
sustained /s/ (25%). The respiratory region was affected in only 15% of participants in
each voiceless task (/s/ and /h/), which was much less often than in sustained phonation.
The oral region was rarely affected in the voiceless tasks.
Figure 9 shows occurrence of tremor was greatest in laryngeal structures for all
tasks, and in particular, in the true vocal folds, supraglottic structures, and
hypopharyngeal walls. The velum and lateral nasopharyngeal walls were affected in
about 30% of participants with tremor across tasks, while tremor in structures of the
respiratory and oral regions was rare.
Figure 9 also shows that tremor was rated as most severe in structures of the
larynx for all tasks, generally in the mild-moderate to moderate range. The velum and
lateral nasopharyngeal walls showed mild to mild-moderate tremor across tasks, with
greater severity noted during sustained phonation than other tasks. Tremor within the
respiratory and oral regions was generally mild for all tasks, except for one individual
with mild-moderate tremor of the jaw during sustained /s/.
Distribution and Severity of Tremor in Structures as a Function of
Voice Tremor During Sustained Voiceless Sounds
The occurrence and severity of tremor during sustained voiceless sounds was
greatest in the larynx (Figure 9), with about a third of participants with vocal tremor also
showing tremor within the velopharynx. The majority of participants, however, did not
demonstrate tremor during these tasks, and specifically did not show respiratory tremor
as predicted.
49
Relating Distribution and Severity of Tremor to Severity of Voice Tremor
of Sustained Voiceless Sounds
The relationship between distribution and severity of tremor in structures of the
vocal tract during sustained voiceless sounds was assessed in the same ways as for
sustained phonation. Pearson correlation coefficients were calculated to determine which
structures contributed most to the perception of voice tremor during each voiceless task.
The Tremor Index was also calculated and compared to the severity of the voice tremor
for each task. Finally, a stepwise variable selection regression analysis was completed for
each task to determine which structures contributed most to the severity of the voice
tremor for that task, with results applied to a multiple regression analysis.
Pearson correlation. Table 8 shows that Pearson correlation coefficients between
tremor severity ratings for each structure and the voice tremor during sustained /s/ were
strong for the lateral nasopharyngeal walls (r = 0.78, p < 0.0001) and the velum (r = 0.76,
p = 0.0001). Pearson correlation coefficients were calculated using SAS (SAS Institute
Inc, Cary, NC). Statistical significance was defined as p < 0.0038, using a Bonferroni
correction to account for 13 comparisons (alpha of 0.5 / 13 = 0.0038). The correlations
for the lateral nasopharyngeal walls and velum were the only correlations to reach
statistical significance.
Table 9 shows none of the Pearson correlation coefficients between tremor
severity ratings for each structure and the voice tremor during sustained /h/ reached
statistical significance. Correlation coefficients were strong for the vertical laryngeal
movement (r = 0.58, p = 0.01), the lateral chest (r = 0.52, p = 0.02), and the lateral
abdominals (r = 0.51, p = 0.02). Pearson correlation coefficients were calculated using
SAS (SAS Institute Inc, Cary, NC). Statistical significance was defined as p < 0.0036,
using a Bonferroni correction to account for 14 comparisons (alpha of 0.5 / 14 = 0.0036).
Tables 10 and 11 show that ratings of tremor severity in structures within each
region were not always highly correlated, which is different from the sustained phonation
50
condition. For sustained /s/, strongly correlated structures (see highlighted boxes) were
the true vocal folds and supraglottic structures (r = 0.94, p < 0.0001) and the velum and
lateral nasopharyngeal walls (r = 0.96, p < 0.0001). The severity of tremor in the base of
tongue was strongly correlated to severity ratings in the jaw (r = 0.73, p = 0.0004). For
sustained /h/, strong correlations were found between the velum and lateral
nasopharyngeal walls (r = 0.95, p < 0.0001), tongue and jaw (r = 0.81, p < 0.0001), and
hypopharyngeal walls and the velum (r = 0.80, p = 0.0003), lateral nasopharyngeal walls
(r = 0.73, p = 0.002), and the base of tongue (r = 0.83, p = 0.0001). The severity of tremor
in the velum was also strongly correlated to the severity of vertical laryngeal movement
(r = 0.65, p = 0.003).
Tremor Index. As shown in Figure 10, the Tremor Index, a combination of the
distribution and severity of tremor within structures of the vocal tract, was higher in
participants with moderate voice tremor (mean = 58) than participants with mild voice
tremor (mean = 21) or no perceptible tremor (mean = 18) during sustained /s/. Figure 11
shows Tremor Index was higher in participants with moderate voice tremor (mean = 32)
and mild voice tremor (mean = 42) than participants with no perceptible tremor (mean =
13) during sustained /h/. Tremor Index and voice tremor ratings for each participant were
displayed in Table 6 (sustained /s/) and Table 7 (sustained /h/).
Regression Analysis. A stepwise variable selection regression analysis identified
the anterior abdominals and the lateral nasopharyngeal walls as the structures
contributing most to the severity of voice tremor during sustained /s/. The same method
was attempted with the data for sustained /h/, but too many participants had incomplete
data sets to complete the analysis.
Table 12 displays the equation for the multiple regression analysis for sustained
/s/, including the anterior abdominals and lateral nasopharyngeal walls based on the
stepwise variable selection analysis above, which was statistically significant (R2
= 0.57,
F = 13.41, p = 0.0003); the anterior abdominals and lateral nasopharyngeal walls account
51
for 57% of the variance in the voice tremor severity during /s/. Another regression
analysis, including only the Tremor Index, was also significant (R2
= 0.25, F = 7.95, p =
0.01), as was the model including all variables (R2
= 0.91, F = 16.22, p = 0.008); the
Tremor Index accounted for 91% of the variance in the voice tremor severity during /s/.
A multiple regression analysis for sustained /h/ with the Tremor Index was not significant
(R2
= 0.03, F = 1.55, p = 0.23); a model with all variables could not be completed due to
missing data.
Rest Breathing
The rest breathing condition was included to assess the presence and severity of
tremor in the structures of the vocal mechanism during rest breathing. Rest breathing data
are presented in Table 13; because the rest breathing condition did not measure severity
of voice tremor, the participants are listed in the same order as in the sustained phonation
table.
Figure 8 shows the number of regions affected by tremor was greater during
sustained phonation (95%) than during rest breathing (45%), and that tremor was more
frequently isolated to the larynx during rest breathing than during sustained phonation.
The respiratory region was not affected in any participants during rest breathing, while
the velopharyngeal (10%) and oral regions (15%) were affected much less often than
during sustained phonation. For rest breathing (Figure 8d), the number of regions
affected was greater for participants with more severe voice tremor (mean = 0.4 for those
with mild tremor on sustained /i/, mean = 1.11 for moderate tremor on /i/, and mean =
0.83 for severe tremor on /i/).
Figure 9 shows tremor occurrence and severity was greatest in structures of the
larynx for the rest breathing condition, similar to sustained phonation. Fewer participants
demonstrated tremor at rest when compared to phonation, but severity of tremor was
generally mild-moderate to moderate in affected structures.
52
Table 14 shows that tremor severity ratings within each region were strongly
correlated (highlighted boxes), but correlations between structures outside each region
were weakly or moderately correlated. The base of tongue and hypopharyngeal walls
were strongly correlated with both structures of the velopharynx (correlations >0.7). The
severity of tremor of the larynx moving vertically was strongly correlated to tremor
severity in the velum (r = 0.72, p = 0.001).
Respitrace Ratings
Respitrace was included across all four tasks to compare to the measurement of
tremor in respiratory structures using the new palpation technique described in the
methods section, to determine if palpation was as sensitive to tremor as the Respitrace.
Respitrace tracings (see Appendix F for tracings), were rated as positive, possible, and
negative for the presence of tremor. Respitrace data are presented in Tables 15-18,
including palpation ratings by each judge for comparison; palpation ratings are a mean of
each judge’s ratings of the two structures of the chest or abdomen, respectively.
Agreement between Respitrace and palpation was defined as at least one judge
identifying tremor as present when Respitrace was positive/possible or as absent when
Respitrace was negative.
Table 15 shows the occurrence of tremor, identified by positive ratings of
Respitrace during sustained phonation, was comparable to palpation data for the chest
(33% for Respitrace, 33% and 35% for palpation for the anterior chest and lateral chest,
respectively from Table 2) and slightly higher than palpation data for the abdomen (33%
for Respitrace, 17% and 20% for palpation of the anterior abdomen and lateral abdomen,
respectively, from Table 2). In addition, possible signs of tremor (rated as 0.5) were
noted in the chest in three participants (17%) and in the abdomen in five participants
(28%). Agreement between Respitrace and palpation occurred in 17 of 20 cases for the
chest (85%) and in 15 of 20 cases (75%) for the abdomen.
53
Table 16 shows the occurrence of tremor, identified by positive ratings of
Respitrace during sustained /s/, was higher for both the chest (22% for Respitrace, 5% for
palpation from Figure 9) and abdomen (28% for Respitrace, 5% for palpation from
Figure 9). Possible signs of tremor were noted in the chest in two additional participants
(11%) and in the abdomen in two additional participants (11%). Agreement between
Respitrace and palpation occurred in 80% of cases for the chest and 75% of cases for the
abdomen, as shown in Table 16.
Table 17 shows the occurrence of tremor, identified by positive ratings of
Respitrace during sustained /h/, was comparable to palpation data for both the chest (6%
for Respitrace, 11% and 10% for palpation, from Figure 9) and abdomen (11% for
Respitrace, 10% for palpation from Figure 9). Possible signs of tremor were noted in the
chest in one additional participant (6%). Agreement between Respitrace and palpation
occurred in 95% of cases for the chest and 90% of cases for the abdomen.
Table 18 shows the occurrence of tremor, identified by positive ratings of
Respitrace during rest breathing, was higher than palpation data for both the chest and
abdomen (11% for Respitrace in both the chest and abdomen, 0% for palpation in both
the chest and abdomen from Figure 9). Possible signs of tremor were noted in two
participants (11%) in the chest and in the abdomen, as shown in Table 18. Agreement
between Respitrace and palpation ratings occurred in 80% of cases for the chest and in
75% of cases for the abdomen.
Overall, Respitrace seems to support the palpation data. In sum, palpation and
Respitrace showed agreement in 85% of cases for the chest (68/80) and 79% of cases for
the abdomen (63/80). Palpation may be more sensitive than Respitrace, as many of the
cases of disagreement occurred when Respitrace was unclear but the judges either
identified mild tremor or no tremor.
54
Reliability
Interjudge Reliability
Structural tremor ratings
Pearson correlation coefficients for interjudge reliability in rating tremor for each
structure were strong for the occurrence of tremor (r = 0.67-0.88) and severity of tremor
(r=0.65-0.75) across tasks (Table 19). Pearson correlation coefficients were calculated
between the judges’ ratings for each structure and for all four tasks. In addition, percent
exact agreement and agreement within 0.5 (e.g., ratings of 1.5, or mild-moderate tremor,
and 2, moderate tremor, are within 0.5) were calculated and included in Table 19. Most
correlations were moderate to strong, indicating good agreement between the judges in
severity of tremor noted in a particular structure. Weak correlations are highlighted
within the table; most of these occurred in the respiratory region. Weak correlations (e.g.,
lateral abdominals and lateral chest) likely resulted from mild severity ratings and minor
differences in the judges ratings. In the respiratory region in particular, percent agreement
between the judges within 0.5 was over 80% for all tasks.
Reliability correlations for video clips were moderate to strong across tasks (r ≥
0.5 in all cases except base of tongue during rest breathing), higher than for palpation
(0.08 ≤ r ≤ 0.72) and observation (0.29 ≤ r ≤ 0.85) where correlations were generally
weak or moderate. This is likely due to the judges rating the same behavior; with the
video clips, there was no opportunity for variability within participants between the
judges’ viewings.
Several discrepancies were noted in both the occurrence and severity of tremor
rated by each of the judges in sustained phonation. Figure 12 illustrates the agreement
between the judges in a) the number of participants with tremor in a particular structure
and b) the severity of tremor in each structure for sustained phonation. The only major
discrepancy in the occurrence of tremor was noted in the vertical movement of the larynx
(Figure 12a). This occurred for two reasons. First, two participants completed only a
55
portion of the data collection process, and were not seen by the second judge for
palpation and observations. Second, the judges completed palpation ratings at separate
times (which also could affect respiratory and oral structures), potentially allowing some
fluctuation in the tremor affecting a participant at a particular time and resulting in
different ratings by each judge. When comparing the ratings of severity, the judges were
fairly consistent (Figure 12b). Discrepancies in severity were noted for the lateral
abdominals and the lips. For the lateral abdominals, this discrepancy occurred due to two
individuals rated as having moderate and severe tremor by judge two and as having no
tremor by judge one. For the lips, the discrepancy occurred because judge two did not
identify any participants as having tremor in the lips, while judge one identified mild
tremor in three of them. Both may have resulted from the judges completing ratings
separately.
Discrepancies were noted in the occurrence of tremor in the true vocal folds,
supraglottic structures, and base of tongue during sustained /s/ (Figure 13a), while
severity ratings were fairly consistent (Figure 13b). This discrepancy in the occurrence
appears to be a function of the number of participants rated by each judge. For the true
vocal folds and base of tongue, judge one completed ratings on 17 of the 22 participants
while judge two completed ratings on only 14 (and those not rated were identified with
tremor by judge 1). For the supraglottic structures, the opposite was true; judge two rated
19 of 22 participants while judge one rated 16 of the 22. Judges were allowed to avoid
rating a particular structure if they felt they could not adequately observe it.
Discrepancies in the occurrence and severity of tremor during sustained /h/ were
noted as well, and are displayed in Figure 14. Discrepancies in the occurrence of tremor
were noted for the base of tongue, where judge one identified tremor more frequently
(Figure 14a). Judge one rated 16 of the 22 participants for this region, while judge two
rated only 12; several of those not rated by judge two were identified as having tremor by
judge one. Discrepancies in severity were noted for the vertical laryngeal movement,
56
tongue, and lips (Figure 14b); this was due to judge two not identifying tremor in any
individuals in these structures and not having the opportunity to rate two participants who
completed only the pilot portion of the study.
No major discrepancies were noted between the judges for the occurrence of
tremor during rest breathing, as shown in Figure 15a; the judges differed on severity of
tremor in the base of tongue and lips when rating severity, as shown in Figure 15b. For
both structures, this difference was due to judge two not rating tremor in any participants,
while judge one identified mild tremor in one participant.
Voice tremor ratings
Table 20 shows interjudge reliability for the severity of the voice tremor was
strong (Pearson r > 0.7 for all tasks). The Pearson correlation coefficient was particularly
strong (r = 0.9) for sustained phonation. In addition, the percent agreement within 0.5 was
over 95% for sustained phonation. Severity of sustained voiceless sounds was not judged
as reliably.
Intrajudge Reliability
The intrajudge reliability ratings were strong for both judges for the video (ICC
for judge 1 = 0.71, judge 2 = 0.81) and very strong for audio ratings (ICC for judge 1 =
0.92, judge 2 = 0.92), and are shown in Table 21. Intrajudge reliability was measured
using a Single Measures Intraclass Correlation Coefficient and Cronbach’s Alpha.
Table 2. Mean ratings of tremor severity in each structure for sustained phonation. Respiratory region Laryngeal region V-P region Oral region
Sub
ject
ID
Lat A
bs
Ant
Abs
Lat C
hest
Ant
Che
st
Ver
t Lar
ynx
Tru
e V
ocal
Fol
ds
Sup
ragl
ottic
Hyp
o P
W
Vel
um
Nas
opha
r.
Wal
l
Jaw
Ton
gue
Lips
# S
truc
t.
Rat
ed
# st
ruct
.
affe
cted
% s
truc
t.
affe
cted
avg
sev.
of
affe
cted
trem
or
inde
x
Voi
ce
trem
or
sust
aine
d i
F50 0 0 0 0 0 0 0 * 0 0 0 0 0 12 0 0 0 0 0
M58 0 0 0 0 0 0 0 0 0 0 0 0 0 13 0 0 0 0 0
F69 0 0.5 0.25 0.25 0 1.5 1.25 * 0 0 0 0 0 12 2 17 1.4 23 0.25
F66 0 0 0.5 0.25 0 1.5 1.5 1.5 1.5 1.25 0.5 0 0 13 5 38 1.5 56 0.5
F65 0.25 0 0.5 0.5 0.75 1.75 1.5 1.75 0.25 0 0.25 0.25 0 13 4 31 1.4 44 0.75
F45 0 0 0 0 0 0 0 0 0 0 0 0 0 13 0 0 0.0 0 1
F67 * 0 * 0 1.5 1.5 1.5 2 0 0 0.5 0.5 0 11 4 36 1.6 59 1.25
F72 0 0 0.25 0.5 1 0 0.75 2.5 0 0 0.75 0.5 0 13 4 31 1.3 38 1.75
F52 * 0.5 * 0 1.5 1.25 0.75 2.5 0.25 0.25 0 0 0 11 4 36 1.5 55 1.75
F62 0 0.25 0 0 0.5 2.5 2 2.5 0.5 0.5 0.5 0.75 0.25 13 4 31 1.9 60 1.75
F77 0.25 0.25 0.25 0.5 1.25 0.75 1.25 2.75 1.25 1 0.5 0.5 0 13 6 46 1.4 64 1.75
F86 0.5 0.75 1 1.25 1 1.25 1.75 1.25 0 0 0 0 0 13 7 54 1.2 64 1.75
M62 0 0 0.25 0.5 0.5 1 2.25 1.5 0.75 0.5 0 0.5 0 13 4 31 1.4 42 2.25
F88 0.25 0 0.25 0.5 1.25 1.75 1.75 2 0.25 0 0.25 0 0 13 4 31 1.7 52 2.25
M84 0.5 1.25 0.5 0.75 0.5 2 2.25 2.25 0 0.5 0.75 0.25 0.75 13 7 54 1.4 77 2.25
F71-2 0.25 0 0.25 1 1.25 1.5 1.5 2.5 0.25 0.25 1.75 1 0.5 13 7 54 1.5 81 2.25
F57 0.25 0 0.25 0.25 0.5 0.75 1.25 1.75 1.5 0.5 0 0.25 0 13 4 31 1.3 40 2.5
F84 0.5 0.5 0.75 0.5 1.25 2.5 2.5 * 0 0 1 0.25 0 12 5 42 1.6 62 2.5
F79 0.75 0.5 0.75 0.75 0.75 1 1.5 1.75 1 0.5 0.75 0.25 0 13 9 69 1.0 69 2.5
F61 0.75 0.75 0.75 0.75 1.25 2.5 1.25 3 0.5 0 0 0.25 0 13 8 62 1.4 85 2.5
F80 0 0.25 0.75 1 1.25 1 2.5 * 1.25 1.25 1.5 1.25 0.75 12 10 83 1.3 104 2.75
F71 1.5 2 1.25 2.75 2.25 2.5 2.5 2.5 2 1.75 0.75 1.5 0 13 12 92 1.9 179 3
Number affected (%)
3 (17)
4 (20)
6 (33)
7 (35)
13 (65)
18 (90)
19 (95)
16 (94)
7 (35)
4 (20)
7 (35)
4 (20)
2 (10)
Avg sev. .32 .19 0.88 1.18 1.25 1.58 1.66 2.13 1.32 1.31 1.04 1.13 0.75
Mild Mean .06 0.1 0.31 0.2 0.45 1.25 1.15 1.31 0.35 0.25 0.25 0.15 0 12.4 3 24 1.2 36 0.75
Mod. Mean .22 0.33 0.34 0.56 0.97 1.33 1.58 2.19 0.36 0.33 0.5 0.39 0.17 12.78 5.22 41 1.5 59 1.97
Sev. Mean .63 0.67 0.75 1 1.21 1.71 1.92 2.25 1.04 0.67 0.67 0.63 0.13 12.67 8 63 1.4 91 2.63
Correlation b/n judges
0.16 0.6 -0.12 0.72 0.45 0.79 0.65 0.87 0.71 0.67 0.59 0.29 0.61
Colors indicate severity from mild (blue) to severe (red). Missing values are marked with an asterisk. Ratings made by only one judge
are bolded.
57
58
Table 3. Pearson correlation coefficients for ratings of tremor in each structure (listed in
column one) with ratings of voice tremor severity.
Structure
Correlation
coefficient p-value
Number of
observations
Vertical laryngeal
movement 0.69* 0.0003 22
Supraglottic structures 0.69* 0.0004 22
Hypopharyngeal walls 0.62 0.006 18
Anterior chest 0.59 0.004 22
Lateral abdominals 0.58 0.007 20
Lateral chest 0.57 0.009 20
Tongue 0.57 0.005 22
Jaw 0.47 0.03 22
True vocal folds 0.46 0.03 22
Anterior abdominals 0.45 0.04 22
Velum 0.43 0.05 22
Nasopharyngeal Walls 0.38 0.08 22
Lips 0.33 0.14 22
*Indicates statistical significance at α = 0.05 with Bonferroni correction for 13
comparisons; correlation coefficients 0.1≤ r <0.3 indicated a weak correlation, 0.3≤ r
<0.5 indicated a moderate correlation, and r ≥0.5 a strong correlation.
Table 4. Pearson correlation coefficients between structures for sustained phonation (p-values provided in parentheses).
Structure Ant
.
Abs
Lat.
Che
st
Ant
.
Che
st
Ver
t.
Lary
nx
TV
F
Sup
ra
Hyp
o
PW
Vel
um
Nas
o.
Pha
r.
Wal
ls
Jaw
Ton
gue
Lips
Lat. Abs 0.85 (<0.0001)
0.80 (<0.0001)
0.83 (<0.0001)
0.71 (0.0005)
0.55 (0.01)
0.43 (0.06)
0.39 (0.14)
0.39 (0.09)
0.36 (0.12)
0.16 (0.51)
0.38 (0.10)
-0.08 (0.73)
Ant. Abs 0.74 (0.0002)
0.76 (<0.0001)
0.48 (0.03)
0.55 (0.009)
0.46 (0.03)
0.34 (0.17)
0.29 (0.19)
0.44 (0.04)
0.11 (0.61)
0.36 (0.10)
0.17 (0.46)
Lat. Chest 0.83 (<0.0001)
0.68 (0.001)
0.53 (0.02)
0.63 (0.002)
0.31 (0.24)
0.41 (0.07)
0.43 (0.06)
0.29 (0.22)
0.38 (0.10)
0.06 (0.79)
Ant. Chest 0.63 (0.002)
0.40 (0.06)
0.56 (0.006)
0.31 (0.21)
0.49 (0.02)
0.57 (0.006)
0.40 (0.06)
0.66 (0.0009)
0.19 (0.40)
Vert. Larynx 0.47
(0.03) 0.50 (0.02)
0.68 (0.002)
0.28 (0.21)
0.30 (0.18)
0.42 (0.05)
0.60 (0.003)
0.06 (0.78)
TVF
0.73 (<0.0001)
0.61 (0.008)
0.17 (0.46)
0.21 (0.35)
0.24 (0.28)
0.30 (0.17)
0.17 (0.45)
Supra
0.51 (0.03)
0.38 (0.07)
0.48 (0.02)
0.50 (0.02)
0.56 (0.007)
0.41 (0.06)
Hypo PW
0.25 (0.32)
0.27 (0.28)
0.42 (0.08)
0.50 (0.04)
0.24 (0.33)
Velum
0.89 (<0.0001)
0.20 (0.37)
0.52 (0.01)
0.01 (0.96)
Nasopharyn. Walls
0.39 (0.08)
0.64 (0.0013)
0.28 (0.21)
Jaw
0.69 (0.0004)
0.66 (0.0008)
Tongue
0.46 (0.03)
Correlations between structures within the same region are outlined in bold. Highlighted values indicate pairs of structures with strongly correlated severity ratings (i.e. 0.5 or above). Correlation coefficients 0.1≤ r <0.3 indicated a weak correlation, 0.3≤ r <0.5 indicated a moderate correlation, and r ≥0.5 a strong correlation.
59
60
Table 5. Multiple regression equations for sustained phonation.
Variables in
Model Equation R
2 F-statistic p-value
All variables Y = 0.46 + -0.19*Lat. Abs + 2.01*Ant.
Abs + -3.09*Lat. Chest +
1.31*Ant. Chest + -0.62*Vert.
Larynx + -0.35*TVF +
0.95*Supra +
0.48*Hypopharyngeal walls +
2.04*Velum + -
3.16*Nasophar. Walls +
1.01*Jaw + -0.95*Tongue + -
1.45*Lip
0.28 1.45 0.48
Vertical larynx
and supraglottic
Y = 0.35 + 0.7*Vert. Larynx +
0.54*Supra
0.60 16.67 <0.0001
Tremor Index Y = 0.69 + 0.017*Tremor Index 0.52 23.70 <0.0001
Table 6. Mean ratings of tremor severity in each structure for sustained /s/.
Respiratory region Laryngeal region V-P region Oral region
Sub
ject
ID
Lat A
bs
Ant
Abs
Lat C
hest
Ant
Che
st
Ver
t Lar
ynx
Tru
e V
ocal
Fol
ds
Sup
ra-
glot
tic
Hyp
o P
har.
Bas
e of
Ton
gue
Vel
um
Nas
opha
r.
Wal
ls
Jaw
Lips
# S
truc
t.
Rat
ed
# S
truc
t.
affe
cted
% S
truc
t.
affe
cted
avg
sev.
of
affe
ct.
trem
or
inde
x
Voi
ce
trem
or s
ust.
/s/
F50 0 0 0 0 0 0 0 0 0 0 0 0 0 13 0 0 0.0 0 0.25
M58 0 0 0 0 0 0 0 0 0.25 0.25 0 0 0 13 0 0 0.0 0 0
F69 0 0 0 0 0 0 0 0 0 0 0 0 0 13 0 0 0.0 0 0
F65 0 0 0 0 0 3 2 1 0.5 0.5 0 0 0 13 3 23 2.0 46 0
F45 0 0 0 0 0 0.75 0.5 0.25 0 0 0 0 0 13 1 8 0.8 6 0
F72 0 0 0 0 0 0 0 0.5 0.5 0.5 0 0 0 13 0 0 0.0 0 0.25
F79 0 0 0 0 0 0.25 0.25 0.25 0 0 0 0 0 13 0 0 0.0 0 0.25
F52 * 0 * 0 0 0.75 0.25 0.25 * * 0 0 0.5 10 1 10 0.8 8 0.25
M62 0 0 0 0 0 * 1 0.5 0.75 0.75 0 0 0 12 2 17 0.9 15 0.25
M84 0.25 0 0 0.75 0.25 3 2.25 2.5 1 1 0 0 0.5 13 5 38 1.9 73 0.25
F86 0 0 0 0.25 0.25 * * * * * 0.25 0 0 9 0 0 0.0 0 0.5
F84 0 0 0 0 0 3 3 1 0.5 0.5 0 0 0.25 13 3 23 2.3 54 0.5
F71 0.5 0.25 0.25 0.25 0 0 0.5 0.5 0 0 0.75 0 0 13 2 15 0.8 12 0.5
F67 * 0 * 0 0 2.5 1.25 0.25 0 0 0.75 0 0 11 3 27 1.5 41 0.75
F57 0 0 0 0 0 * * * * * * * 0 6 0 0 0.0 0 1
F77 0 0 0 0 0 1 1 0.75 0.5 0.5 0 0 0 13 3 23 0.9 21 1
F66 0 0 0 0 0 0 0.25 0 0 0 0 0 0 13 0 0 0.0 0 1.25
F61 0.5 0.5 0.5 0.5 0 1.5 1.5 1 1 1 * * 0.25 10 4 40 1.3 50 1.25
F80 0 0.25 0.5 0.25 0 2.5 2.5 * 3 3 0.75 0.25 0.5 12 5 42 2.0 83 1.5
F88 0 0 0.25 0 0.5 2.5 2.5 0 0 0 0.25 0 0 13 2 15 2.5 38 1.75
F62 0 0.75 0 0.25 1 * 1 2.5 0 0 1.5 0 0 12 6 50 1.3 67 1.75
F71-2 0 0.25 0 0.25 0 0 0 1.5 2 2 1.5 0 1.5 13 5 38 1.6 62 2.5
Number affected(%)
0 (0)
1 (5)
0 (0)
1 (5)
1 (5)
10 (63)
10 (56)
7 (41)
5 (29)
5 (29)
5 (28)
0 (0)
1 (5)
Avg sev. 0.07 0.10 0.08 0.13 0.10 1.30 1.10 0.75 0.57 0.57 0.32 0.01 0.18
No tremor mean
0.08 0.02 0.03 0.11 0.05 1.19 0.98 0.68 0.36 0.36 0.09 0.00 0.11 12.27 1.55 12.21 0.86 19.32 0.25
Mild Mean 0.13 0.10 0.13 0.10 0.00 1.25 1.00 0.50 0.38 0.38 0.25 0.00 0.05 10.60 2.00 18.07 0.74 22.41 1.05
Mod. Mean 0.00 0.33 0.25 0.17 0.50 2.50 2.00 1.25 1.00 1.00 0.83 0.08 0.17 12.33 4.33 35.68 1.93 62.82 1.67
Correlation b/n judges
-0.08 0.29
0.20 0.61 0.91 0.78 0.71 0.62 0.58 0.79 0.85 0.33
0.74
Colors indicate severity from mild (blue) to severe (red). Missing values are marked with an asterisk. Ratings made by only one judge are bolded.
61
Table 7. Mean ratings of tremor severity in each structure for sustained /h/. Respiratory region Laryngeal region V-P region Oral region
Sub
ject
ID
Lat A
bs
Ant
Abs
Lat
Che
st
Ant
Che
st
Ver
t
Lary
nx
Tru
e
Voc
al
Fol
ds
Sup
ra-
glot
tic
Hyp
o
Pha
r.
Bas
e of
Ton
gue
Vel
um
Nas
opha
Wal
ls
Jaw
Ton
gue
Lips
# S
truc
t.
Rat
ed
# st
ruct
affe
cted
% s
truc
t
affe
cted
avg
sev
of a
ffect
trem
or
inde
x
/h/ v
oice
trem
or
F50 0 0 0 0 0 * * 0 0 0 0 0 0 0 12 0 0 0.0 0 0.25
M58 0 0 0 0 0 * * * 0 0 0 0 0 0 11 0 0 0.0 0 0
F57 0 0 0 0 0 * * * * * * 0 0 0 7 0 0 0.0 0 0
F79 0 0 0 0 0 * * 0 0 0.25 0 0 0 0 12 0 0 0.0 0 0
M62 0 0 0 0 0 * * 0 0 0 0 0 0 0 12 0 0 0.0 0 0
F84 0 0 0 0 0 0.25 0.25 0.25 1.5 0.25 0.25 0 0.25 0 14 1 7 1.5 11 0
F77 0 0 0 0 0 * * 0.75 0.75 0 0 0 0 0 12 2 17 0.8 13 0
F45 0 0 0 0 0 * * 0.25 0.25 0 0 0 0 0 12 0 0 0.0 0 0.25
F72 0 0 0 0 0 * * 0 0 0.25 0 0 0 0 12 0 0 0.0 0 0.25
F65 0 0 0 0 0 2 * 1.25 1.25 0 0 0 0 0 13 3 23 1.5 35 0.25
F66 0 0 0 0 0 * 1 1 1 1 1 0 0 0 13 5 38 1.0 38 0.25
F80 0.25 0.5 0.75 0.75 0.25 * * * * 1.5 1.5 1 0.5 0 10 5 50 1.1 55 0.25
F52 * 0 * 0 0 0.5 0 0 * 0 0 0 0 0 11 0 0 0.0 0 0.5
F88 0.25 0 0.25 0.25 0.25 2.5 2.5 2 2.5 0.5 0 0 0 0 14 4 29 2.4 68 0.5
F69 0 0 0 0 0 0.25 0.25 * * 0 0 0 0 0 12 0 0 0.0 0 1
F71-2 0 0 0 0 0 * * 0.5 0.5 0.25 0.25 0 0 0 12 0 0 0.0 0 1.5
F67 * 0.5 * 0 0 3 2.75 2.5 2 2 1.75 0 0 0 12 6 50 2.3 117 1.5
F71 0 0 0 0.5 0 0 0 0 0 0.25 0.25 0 0 0 14 0 0 0.0 0 1.75
F61 0.25 0.75 0.75 0.75 0 * * 0.75 1 * * 0 0 0 9 5 56 0.8 44 1.75
F62 0 0.75 0.25 0 0.75 * * 2.75 1.25 2 2 0 0 0 12 6 50 1.5 73 2
M84 0.5 0.25 0.5 0 0.25 * * * * 0.75 0.75 0.75 0.25 0.75 10 4 40 0.8 30 2
F86 0.25 0 0.5 0.25 0.5 * * * * * * 0 0.25 0 7 0 0 0.0 0 2.5
Number aff. (%)
0 (0)
2 (10)
2 (11)
2 (10)
1 (5)
3 (43)
3 (43)
7 (47)
8 (57)
5 (28)
5 (29)
2 (10)
0 (0)
1 (5)
Avg sev. 0.08 0.14 0.17 0.13 0.10 1.21 0.96 0.80 0.86 0.53 0.41 0.09 0.06 0.04
No tremor mean
0.03 0.05 0.08 0.07 0.02 0.92 0.42 0.39 0.59 0.33 0.28 0.09 0.07 0.00 11.64 1.45 12.30 0.53 13.75 0.25
Mild Mean 0.13 0.25 0.25 0.20 0.05 1.92 1.83 1.44 1.50 0.69 0.50 0.00 0.00 0.00 11.80 3.00 26.83 1.10 45.79 1.05
Mod. Mean 0.17 0.33 0.25 0.17 0.33 0.00 0.00 1.38 0.63 1.00 0.75 0.25 0.08 0.25 12.00 3.33 30.00 0.74 34.31 1.67
Correlation b/n judges
0.22 0.19 0.27 0.28 0.36 0.85 0.94 0.88 0.50 0.66 0.68 0.52 1.00 0.85
Colors indicate severity from mild (blue) to severe (red). Missing values are marked with an asterisk. Ratings made by only one judge
are bolded.
62
63
Table 8. Pearson correlation coefficients for each structure with sustained /s/ tremor severity
rating.
Structure Correlation p-value Number of observations
Nasopharyngeal walls 0.78* <0.0001 20
Velum 0.76* 0.00 20
Anterior abdominals 0.57 0.01 22
Jaw 0.52 0.01 22
Base of Tongue 0.44 0.06 19
Vertical larynx 0.40 0.07 22
Lateral chest 0.37 0.11 20
Hypopharyngeal walls 0.35 0.14 19
Anterior chest 0.24 0.28 22
Supraglottic structures 0.19 0.42 20
Lips 0.18 0.41 22
True vocal folds 0.08 0.74 18
Lateral abdominals 0.01 0.98 20
*Indicates statistical significance at α = 0.05 with Bonferroni correction for 13 comparisons;
correlation coefficients 0.1≤ r <0.3 indicated a weak correlation, 0.3≤ r <0.5 indicated a
moderate correlation, and r ≥0.5 a strong correlation.
Table 9. Pearson correlation coefficients for each structure with sustained /h/ tremor severity
rating.
Structure Correlation* p-value Number of observations
Vertical larynx 0.58 0.01 22
Lateral chest 0.52 0.02 20
Lateral abdominals 0.51 0.02 20
Velum 0.51 0.03 19
Hypopharyngeal walls 0.47 0.06 16
Nasopharyngeal walls 0.47 0.04 19
Anterior abdominals 0.46 0.03 22
Lips 0.32 0.14 22
Anterior chest 0.30 0.18 22
Base of Tongue 0.24 0.37 16
Tongue 0.15 0.50 22
Supraglottic structures 0.12 0.79 7
Jaw 0.09 0.69 22
True vocal folds 0.01 0.98 7
*None of the correlations were statistically significant at α = 0.05 with Bonferroni correction for
14 comparisons; correlation coefficients 0.1≤ r <0.3 indicated a weak correlation, 0.3≤ r <0.5
indicated a moderate correlation, and r ≥0.5 a strong correlation.
Table 10. Pearson correlation coefficients between structures (p-values) for sustained /s/.
Late
ral c
hest
Ant
erio
r
abdo
min
als
Late
ral
abdo
min
als
Ver
tical
lary
nx
Tru
e vo
cal f
olds
Sup
ragl
ottic
stru
ctur
es
Hyp
opha
ryng
eal
wal
ls
Bas
e of
Ton
gue
Vel
um
Nas
opha
ryng
eal
wal
ls
Jaw
Lips
Anterior chest .39 (.09)
.48 (.02)
.65 (.002)
.27 (.22)
.29 (.24)
.31 (.18)
.74 (.0003)
.44 (.06)
.35 (.14)
.38 (.10)
.41 (.06)
.76 (<.0001)
Lateral chest .45 (.05)
.56 (.01)
-.03 (.89)
.29 (.28)
.41 (.09)
-.05 (.84)
.50 (.04)
.29 (.24)
.48 (.04)
.13 (.57)
.51 (.02)
Anterior abdominals .40 (.08)
.58 (.005)
-.02 (.93)
.07 (.76)
.59 (.008)
.23 (.34)
.84 (<.0001)
.80 (<.0001)
.21 (.34)
.13 (.55)
Lateral abdominals -.08 (.73)
.04 (.88)
.10 (.69)
.21 (.41)
.02 (.92)
.15 (.55)
.14 (.58)
.06 (.81)
.42 (.07)
Vertical larynx .42 (.08)
.23 (.32)
.55 (.01) -.19 (.45)
.48 (.03)
.37 (.11)
-.11 (.62)
.21 (.36)
True vocal folds .94 (<.0001)
.48 (.05)
.27 (.29)
-.02 (.95)
.02 (.92)
.03 (.91)
.55 (.02)
Supraglottic structures
.39 (.10)
.33 (.17)
.003 (.99)
.08 (.75)
.02 (.92)
.59 (.007)
Hypopharyngeal walls
.51 (.03)
.50 (.03)
.50 (.04)
.42 (.08)
.45 (.06)
Base of Tongue .35 (.15)
.56 (.02)
.73 (.0004)
.42 (.07)
Velum .96 (<.0001)
.49 (.03)
-.03 (.90)
Nasopharyngealwalls .56 (.01)
.07 (.77)
Jaw .25 (.27)
Correlations between structures within the same region are outlined in bold. Highlighted values indicate pairs of structures with
strongly correlated severity ratings. Correlation coefficients 0.1≤ r <0.3 indicated a weak correlation, 0.3≤ r <0.5 indicated a moderate
correlation, and r ≥0.5 a strong correlation.
64
Table 11. Pearson correlation coefficients between structures (p-values) for sustained /h/.
Late
ral c
hest
Ant
erio
r
abdo
min
als
Late
ral
abdo
min
als
Ver
tical
lary
nx
Tru
e vo
cal
fold
s
Sup
ragl
ottic
Str
uctu
res
Hyp
opha
ryn.
wal
ls
Bas
e of
Ton
gue
Vel
um
Nas
opha
ryn.
wal
ls
Jaw
Ton
gue
Lips
Anterior chest .75 (.0001)
.49 (.02)
.46 (.04)
.15 (.51)
-.19 (.68)
.07 (.88)
-.02 (.94)
.09 (.73)
.27 (.27)
.33 (.17)
.42 (.05)
.44 (.04)
-.11 (.64)
Lateral chest .74
(.0002) .83 (<.0001)
.50 (.02)
.72 (.17)
.93 (.02)
.39 (.17)
.40 (.14)
.69 (.002)
.74 (.0008)
.64 (.002)
.31 (.18)
.74 (.0002)
Anterior abdominals
.40 (.08)
.48 (.02)
.63 (.13)
.66 (.10)
.62 (.01)
.36 (.17)
.91 (<.0001)
.86 (<.0001) .34 (.13)
.22 (.32)
.11 (.62)
Lateral abdominals
.40 (.08)
.72 (.17)
.93 (.02)
.35 (.22)
.59 (.02)
.35 (.17)
.40 (.12)
.67 (.001)
.59 (.007)
.70 (.0006)
Vertical larynx
.46 (.30)
.57 (.18)
.67 (.004)
.35 (.18)
.65 (.003)
.48 (.04)
.26 (.25)
.36 (.10)
.18 (.42)
True vocal folds .99
(.0002) .98 (.0006)
.76 (.13)
.68 (.09)
.54 (.21)
-.34 (.45)
Supraglottic structures
.995 (<.0001)
.83 (.09)
.78 (.04)
.58 (.18)
-.27 (.56)
Hypopharyngeal walls
.80 (.0003)
.83 (.0001)
.73 (.002)
-.14 (.59)
Base of Tongue
.55 (.03)
.48 (.07)
.25 (.35)
Velum
.95 (<.0001)
.37 (.12)
.33 (.17)
.10 (.68)
Nasopharyngeal walls
.49 (.03)
.45 (.05)
.16 (.51)
Jaw
.81 (<.0001)
.58 (.005)
Tongue
.33 (.14)
Correlations between structures within the same region are outlined in bold. Highlighted values indicate pairs of structures with
strongly correlated severity ratings. Correlation coefficients 0.1≤ r <0.3 indicated a weak correlation, 0.3≤ r <0.5 indicated a moderate
correlation, and r ≥0.5 a strong correlation.
65
66
Table 12. Multiple regression equations for sustained /s/ and sustained /h/.
Variables in Model
Equation R2 F-statistic p-value
Sust
ained
/s/
All variables**
Y = 0.13 + -39.6*Lat. Abs + 58.7*Ant. Abs + -5.00*Lat. Chest + 20.6*Ant. Chest + -2.33*TVF + 3.5*Supra + -0.26*Hypopharyngeal walls + 0.16*BoT + -11.6*Jaw
.91 16.22 .008
Anterior
abdominals and
nasopharyngeal
walls
Y = 0.35 - 0.57 * Ant. Abs + 1.3 *
Nasophar.Walls .57 13.41 .0003
Tremor Index Y = .038 + .014 * Tremor Index .25 7.97 .011
Sust
ained
/h/
All variables Not completed - missing too many
values
Tremor Index Y = 0.61 + 0.007 * Tremor Index .03 1.57 .22
**A number of the variables in the model for sustained /s/ were set to zero because they
were linear combinations of other variables.
Table 13. Mean ratings of tremor severity in each structure for rest breathing.
Respiratory region Laryngeal region Velopharyngeal
region Oral region
Sub
ject
ID
Lat A
bs
Ant
Abs
Lat C
hest
Ant
Che
st
Ver
t Lar
ynx
Tru
e V
ocal
Fol
ds
Sup
ragl
ottic
Hyp
o P
W
Bas
e of
Ton
gue
Vel
um
Nas
opha
r.
Wal
l
Jaw
Ton
gue
Lips
# S
truc
t.
Rat
ed
# st
ruct
.
affe
cted
% s
truc
t
affe
cted
avg
sev.
of
affe
cted
trem
or
inde
x
F50 0 0 0 0 0 0 0 0 0 0 0 0 0 0 14 0 0 0.00 0
M58 0 0 0 0 0 0.25 0.25 0 0.25 0 0 0 0 0 14 0 0 0.00 0
F69 0 0 0 0 0 0 0 0 0 0 0 0 0 0 14 0 0 0.00 0
F66 0 0 0 0 0 0 0 0 0 0 0 0 0 0 14 0 0 0.00 0
F65 0 0 0 0 0 2.5 2.5 0.75 0 0 0 0 0.25 0 14 3 21 1.92 41
F45 0 0 0 0 0 0 0 0 0 0.25 0 0 0 0 14 0 0 0.00 0
F67 * 0 * 0 0 1 1 0 0 0 0 0 0 0 12 2 14 1.00 14
F72 0 0 0 0 0 0 0 0 0 * * 0 0 0 12 2 0 0.75 0
F52 * 0 * 0 0 0 0 0 0 0 0 0 0 0 12 0 0 0.00 0
F62 0 0 0 0 0.5 2.5 2 3 2.5 1.75 2.25 0 0 0 14 6 43 2.33 100
F77 0 0 0 0 0 1 1 0 0.5 0 0 0 0 0.25 14 2 14 1.00 14
F86 0 0 0 0 0 * * * * 0 0 0 0.25 0 10 0 0 0.00 0
M62 0 0 0 0 0 1.5 1 0 0 * * 0 0 0 12 3 17 1.25 21
F88 0 0 0 0 0 0.25 0.25 0 * 0 0 0 0 0 12 0 0 0.00 0
M84 0.25 0.25 0 0 0 0
0 0.25 * 1 1.75 0.25 0.25 12 2 17 1.38 23
F71-2 0 0 0 0 0.75 2 2.25 0.5 0.5 0.5 0.25 1 0 0 14 4 29 1.5 43
F57 0 0 0 0 0 0 0 0 0 * * 0.25 0 0 12 0 0 0.00 0
F84 0 0 0 0 0 1.75 1.75 1.5 1 0 0 0 0 0 14 4 29 1.50 43
F79 0 0 0 0 0 0 0 0 0 0 0 0 0 0 14 0 0 0.00 0
F61 0.25 0.25 0.25 0.25 0 0 0.5 0.75 0.25 * * 0.25 0.25 0 12 1 8 0.75 6
F80 0 0 0.25 0 0 0 0.25 * * 0 0 0.75 0 0.75 12 2 17 0.75 13
F71 0 0 0 0 0 0 0 1 0 0 0 0 0 0 14 1 7 1.00 7
Number affected (%)
0 (0)
0 (0)
0 (0)
0 (0)
1 (5)
7 (37)
7 (38)
5 (28)
2 (12)
1 (7)
2 (13)
3 (15)
0 (0)
1 (5)
Avg severity
0.03 0.03 0.03 0.01 0.06 0.66 0.69 0.42 0.29 0.35 0.24 0.20 0.05 0.06
Correlation between judges
0.41 0.75 0.62 0.74 0.27 0.63 0.45 0.75 0.59
Colors indicate severity from mild (blue) to severe (red). Missing values are marked with an asterisk. Ratings made by only one judge
are bolded.
67
Table 14. Pearson correlation coefficients between structures (p-values) for rest breathing.
Late
ral
ches
t
Ant
erio
r
abdo
min
al
Late
ral
abdo
min
al
Ver
tical
lary
nx
Tru
e vo
cal
fold
s
Sup
ragl
otti
c.st
ruct
ure
Hyp
opha
ry
wal
ls
Bas
e of
Ton
gue
Vel
um
Nas
opha
ry
wal
ls
Jaw
Ton
gue
Lips
Anterior chest .69 (.0008)
.69 (.0004)
.69 (.0008)
-.07 (.77)
-.15 (.50)
-.04 (.87)
.12 (.62)
-.01 (.97)
.03 (.88)
.46 (.03)
-.07 (.74)
Lateral chest .44 (.05)
.44 (.05)
-.11 (.65)
-.23 (.34)
-.11 (.65)
.11 (.68)
-.02 (.93)
-.10 (.72)
-.10 (.71)
.23 (.34)
.25 (.29)
.60 (.006)
Anterior abdominals
1.0 (<.0001)
-.10 (.66)
-.22 (.33)
-.04 (.87)
0 (1.0)
-.02 (.95)
.35 (.17)
.61 (.003)
.67 (.0006)
.13 (.57)
Lateral abdominals
-.11 (.65)
-.24 (.34)
-.04 (.86)
-.02 (.94)
-.04 (.89)
.34 (.21)
.60 (.005)
.67 (.001)
.12 (.62)
Vertical larynx .58 (.006)
.60 (.006)
.50 (.03)
.59 (.008)
.72 (.001)
.53 (.03)
.30 (.17)
-.15 (.52)
-.11 (.64)
True vocal folds .97 (<.0001)
.63 (.003)
.61 (.006)
.56 (.02)
.43 (.10)
-.05 (.82)
.11 (.65)
-.16 (.48)
Supraglottic structures
.59 (.008)
.55 (.02)
.47 (.07)
.42 (.12)
.25 (.28)
.35 (.13)
-.07 (.76)
Hypopharyngeal walls
.89 (<.0001)
.80 (.0003)
.73 (.002)
-.08 (.72)
.07 (.76)
-.17 (.47)
Base of Tongue .89 (<.0001)
.84 (<.0001)
.02 (.93)
-.08 (.74)
.06 (.81)
Velum .98 (<.0001)
.12 (.65)
-.13 (.63)
-.11 (.67)
Nasopharyngeal walls
.28 (.28)
.10 (.69)
-.004 (.99)
Jaw .35 (.11)
.49 (.02)
Tongue .02 (.94)
Correlations between structures within the same region are outlined in bold. Highlighted values indicate pairs of structures with
strongly correlated severity ratings. Correlation coefficients 0.1≤ r <0.3 indicated a weak correlation, 0.3≤ r <0.5 indicated a moderate
correlation, and r ≥0.5 a strong correlation.
68
69
Table 15. Respiratory region ratings with Respitrace readings for sustained phonation.
Part. ID Chest Abdomen
Judge
1
Judge
2
Respitrace Agreement Judge
1
Judge
2
Respitrace Agreement
F50 0 0 0 √ 0 0 0 √
M58 0 0 0 √ 0 0 0 √
F69 0 0.5 0 √ 0 0.5 0 √
F66 0.75 0 0 √ 0 0 0 √
F65 0.5 0.5 0.5
0.25 0 0.5
F45 0 0 0 √ 0 0 0 √
F72 0.5 0.25 0.5
0 0 0.5
F62 0 0 1
0.25 0 1
F77 0.25 0.5 0 √ 0 0.5 0.5
F86 1.5 0.75 1 √ 1 0.25 1 √
M62 0.75 0 0 √ 0 0 0.5
F88 0.5 0.25 0 √ 0.25 0 0 √
M84 0.75 0.5 0 √ 1.25 0.5 0 √
F71-2 0.5 0.75 0 √ 0 0.25 0 √
F57 0.25 0.25 0 √ 0 0.25 0 √
F84 0.75 0.5 1 √ 0.75 0.25 0.5 √
F79 0.75 0.75 0.5 √ 0.75 0.75 1 √
F61 0.25 1.25 1 √ 0 1.25 1 √
F80 0.75 1 1 √ 0 0.25 1
F71 1.25 2.75 1 √ 0.75 2.75 1 √
Agreement Agreement
Controls 0 0 0 Total = 2 0 0 0 Total = 2
Mild 1 0 0 Total = 3 0 0 0 Total = 3
Moderate 3 2 2 Total = 6 2 0 2 Total = 4
Severe 4 4 4 Total = 6 3 3 4 Total =
Overall 8 6 Total = 6 Total =
17/20
5 3 Total = 6 Total =
15/20
If the Respitrace record was positive, it was given a value of 1, if tremor was rated as
possible it was given a value of 0.5, and if no tremor was noted, it was given a value of 0.
Agreement was defined as at least one judge rating tremor as present on palpation (0.75
or greater) when Respitrace was positive/possible or as absent on palpation (0.5 or less)
when Respitrace was negative.
70
Table 16. Respiratory region ratings with Respitrace readings for sustained /s/.
Part. ID Chest Abdomen Judge
1
Judge
2
Respitrace Agreement Judge
1
Judge
2
Respitrace Agreement
F50 0 0 0 √ 0 0 0 √
M58 0 0 0 √ 0 0 0 √
F69 0 0 0 √ 0 0 0 √
F65 0 0 0 √ 0 0 0 √
F45 0 0 0 √ 0 0 0 √
F72 0 0 0 √ 0 0 0 √
F79 0 0 0 √ 0 0 1
M62 0 0 0 √ 0 0 1
M84 0.25 0.5 0 √ 0.25 0 1
F86 0 0.25 0 √ 0 0 0 √
F84 0 0 0 √ 0 0 0.5
F71 0.25 0.25 1
0 0.75 0.5 √
F57 0 0 0.5
0 0 0 √
F77 0 0 0 √ 0 0 0 √
F66 0 0 0.5
0 0 0 √
F61 0 1 1 √ 0 1 1 √
F80 0 0.75 1 √ 0 0.25 1
F88 0 0.25 0 √ 0 0 0 √
F62 0 0.25 1
0.5 0.25 0 √
F71-2 0.25 0 0 √ 0 0.25 0 √
Agreement Agreement
Controls 0 0 0 Total = 2 0 0 0 Total = 2
No tremor 0 0 1 Total = 9 0 1 3 Total = 6 Mild 0 1 1 Total = 2 0 1 1 Total = 4 Moderate 0 1 2 Total = 2 0 0 1 Total = 2 Severe 0 0 0 Total = 1 0 0 0 Total = 1
Overall 0 2 Total = 4 Total =
16/20 0 2 Total = 5
Total =
15/20
If the Respitrace record was positive, it was given a value of 1, if tremor was rated as
possible it was given a value of 0.5, and if no tremor was noted, it was given a value of 0.
Agreement was defined as at least one judge rating tremor as present (0.75 or greater)
when Respitrace was positive/possible or as absent (0.5 or less) when Respitrace was
negative.
71
Table 17. Respiratory region ratings with Respitrace readings for sustained /h/.
Part. ID Chest Abdomen
Judge
1
Judge
2
Respitrace Agreement Judge
1
Judge
2
Respitrace Agreement
F50 0 0 0 √ 0 0 0 √
M58 0 0 0 √ 0 0 0 √
F57 0 0 0 √ 0 0 0 √
F79 0 0 0 √ 0 0 1
M62 0 0 0 √ 0 0 0 √
F77 0 0 0 √ 0 0 0 √
F84 0 0 0 √ 0 0 0.5
F45 0 0 0 √ 0 0 0 √
F72 0 0 0 √ 0 0 0 √
F65 0 0 0 √ 0 0 0 √
F66 0 0 0.5 0 0 0 √
F80 1 0.5 1 √ 0 0.75 1 √
F88 0.25 0.25 0 √ 0.25 0 0 √
F69 0 0 0 √ 0 0 0 √
F71-2 0 0 0 √ 0 0 0 √
F61 0.25 1.25 0 √ 0 1 0 √
F71 0.25 0.25 0 √ 0 0 0 √
F62 0 0.25 0 √ 0.5 0.25 0 √
M84 0 0.5 0 √ 0.25 0.5 0 √
F86 0.5 0.25 0 √ 0.25 0 0 √
Agreement Agreement
Controls 0 0 0 Total = 2 0 0 0 Total = 2
No tremor 1 0 1 Total = 9 0 1 2 Total = 8 Mild 0 1 0 Total = 4 0 1 0 Total = 4 Moderate 0 0 0 Total = 3 0 0 0 Total = 3 Severe 0 0 0 Total = 1 0 0 0 Total = 1 Overall 1 1
Total = 1 Total =
19/20
0 2 Total = 2
Total =
18/20
If the Respitrace record was positive, it was given a value of 1, if tremor was rated as
possible it was given a value of 0.5, and if no tremor was noted, it was given a value of 0.
Agreement was defined as at least one judge rating tremor as present (0.75 or greater)
when Respitrace was positive/possible or as absent (0.5 or less) when Respitrace was
negative.
72
Table 18. Respiratory region ratings with Respitrace readings for rest breathing.
Part. ID Chest Abdomen Judge
1
Judge
2
Respitrace Agreement Judge
1
Judge
2
Respitrace Agreement
F50 0 0 0 √ 0 0 0 √
M58 0 0 0 √ 0 0 0 √
F69 0 0 0 √ 0 0 0 √
F66 0 0 0 √ 0 0 0 √
F65 0 0 0 √ 0 0 0 √
F45 0 0 0 √ 0 0 0 √
F72 0 0 0 √ 0 0 0 √
F62 0 0 0.5
0 0 0.5
F77 0 0 0 √ 0 0 0 √
F86 0 0 1
0 0 1
M62 0 0 0 √ 0 0 0 √
F88 0 0 0 √ 0 0 0 √
M84 0 0 0 √ 0 0.5 0.5
F71-2 0 0 0 √ 0 0 0 √
F57 0 0 0.5
0 0 0 √
F84 0 0 0 √ 0 0 0.5
F79 0 0 0 √ 0 0 0 √
F61 0 0.5 0 √ 0 0.5 0 √
F80 0 0.25 1
0 0 1
F71 0 0 0 √ 0 0 0 √ Agreement Agreement
Controls 0 0 0 Total = 2 0 0 0 Total = 2
Mild 0 0 0 Total = 4 0 0 0 Total = 4 Moderate 0 0 1 Total = 6 0 0 1 Total = 5 Severe 0 0 1 Total = 4 0 0 1 Total = 4
Overall 0 0 Total = 2 Total =
16/20 0 0 Total = 2
Total =
15/20
If the Respitrace record was positive, it was given a value of 1, if tremor was rated as
possible it was given a value of 0.5, and if no tremor was noted, it was given a value of 0.
Agreement was defined as at least one judge rating tremor as present (0.75 or greater)
when Respitrace was positive/possible or as absent (0.5 or less) when Respitrace was
negative.
73
Table 19. Interjudge reliability for structural severity ratings.
Sustained phonation Sustained /s/ Sustained /h/ Rest breathing
Structure
Cor
rela
tion
Exa
ct
agre
emen
t
Agr
eem
ent
with
in 0
.5
Cor
rela
tion
Exa
ct
agre
emen
t
Agr
eem
ent
with
in 0
.5
Cor
rela
tion
Exa
ct
agre
emen
t
Agr
eem
ent
with
in 0
.5
Cor
rela
tion
Exa
ct
agre
emen
t
Agr
eem
ent
with
in 0
.5
Lateral Abdominals
0.16 0.55 0.82 -0.08 0.85 0.90 0.22 0.80 1.00 - 0.90 1.00
Anterior Abdominals
0.60 0.45 0.73 0.29 0.75 1.00 0.19 0.80 0.90 - 0.90 1.00
Lateral Chest
-0.12 0.32 0.82 - 0.80 0.90 0.27 0.70 0.90 - 0.90 1.00
Anterior Chest
0.72 0.50 0.82 0.20 0.65 0.95 0.28 0.80 0.95 - 0.95 1.00
Vertical Larynx
0.45 0.36 0.64 0.61 0.85 0.95 0.36 0.75 0.95 0.41 0.90 0.95
True Vocal Folds
0.79 0.41 0.64 0.91 0.46 0.69 0.85 0.00 0.50 0.75 0.53 0.68
Supraglottic Structures
0.65 0.41 0.73 0.78 0.33 0.60 0.94 0.20 0.80 0.62 0.53 0.79
Hypophar. Walls
0.87 0.28 0.56 0.71 0.33 0.61 0.88 0.40 0.73 0.74 0.75 0.85
Base of Tongue
N/A N/A N/A 0.62 0.50 0.58 0.50 0.58 0.75 0.27 0.77 1.00
Velum
0.71 0.41 0.68 0.58 0.70 0.90 0.66 0.53 0.84 0.91 0.70 0.75
Nasophar. Walls
0.67 0.59 0.86 0.79 0.70 0.90 0.68 0.56 0.89 0.89 0.75 0.80
Jaw
0.59 0.45 0.68 0.85 0.85 0.95 0.52 0.95 0.95 0.75 0.80 0.95
Tongue
0.29 0.36 0.73 N/A N/A N/A - 0.80 0.95 - 0.80 1.00
Lips
0.61 0.73 0.86 0.33 0.85 1.00 1.00 0.95 1.00 0.59 0.85 1.00
Overall for severity
0.70 0.49 0.74 0.75 0.70 0.87 0.69 0.73 0.91 0.73 0.79 0.90
Overall for rate of occurrence
0.88 0.67 0.84 0.87
Pearson correlation coefficients, percent exact agreement, and percent agreement within
one rating category (e.g., 1.0 and 1.5) are listed by structure for each task. Correlation
coefficients 0.1≤ r <0.3 indicated a weak correlation, 0.3≤ r <0.5 indicated a moderate
correlation, and r ≥0.5 a strong correlation. Highlighted values indicate correlations that
were weak. All other correlations were moderate to strong.
74
Table 20. Interjudge reliability for voice tremor severity.
Correlation Exact agreement Within one
agreement
Sustained phonation 0.90 0.36 0.96
Sustained /s/ 0.74 0.23 0.68
Sustained /h/ 0.85 0.46 0.86
Overall 0.87 0.35 0.83
Correlation coefficients 0.1≤ r <0.3 indicated a weak correlation, 0.3≤ r <0.5 indicated a
moderate correlation, and r ≥0.5 a strong correlation.
Table 21. Intrajudge reliability.
Judge Single Measures
ICC Cronbach’s Alpha
Audio ratings 1 0.919 0.963
2 0.924 0.959
Video ratings 1 0.708 0.832
2 0.807 0.892
75
Figure 1. Tremor distribution. Regions of the speech mechanism affected by tremor as a
function of severity of voice tremor during /i/. Regions were identified as affected if one
or more of the structures in that region received a mean rating of 0.75. Each column
represents one participant. Participants are arranged in order of severity of voice tremor
with controls at the bottom and participants with severe voice tremor at the top.
Regions affected by tremor
Part
icip
an
ts
Contr
ols
Mil
d
Sev
ere
Moder
ate
Respiratory Laryngeal Velopharyngeal Oral
76
Figure 2. Tremor distribution. Number of structures affected in each of 20 participants as
a function of the severity of voice tremor during sustained /i/. Each open data point
represents one participant; filled points indicate means for the group.
0
2
4
6
8
10
12
14N
um
ber
of
stru
ctu
res
aff
ecte
d
(of
a t
ota
l of
13 a
sses
sed
)
Severity of vocal tremor during /i/
Mild Moderate Severe
77
Figure 3. Tremor distribution. Number of participants affected by tremor in each
structure. Tremor was identified as present if the mean rating was 0.75 or greater.
0
2
4
6
8
10
12
14
16
18
20
Nu
mb
er o
f p
art
icip
an
ts a
ffec
ted
Severe voice tremorModerate voice tremorMild voice tremorNot rated
Respiratory Laryngeal
V-P Oral
78
Figure 4. Tremor severity. Mean severity of tremor in each structure. Participants were
groups by severity of voice tremor.
0.0
0.5
1.0
1.5
2.0
2.5
3.0M
ean
tre
mor
sever
ity i
n s
tru
ctu
res Mild voice tremor
Moderate voice tremorSevere voice tremorOverall
Respiratory Laryngeal
V-P Oral
79
Figure 5. Rate of occurrence and severity (indicated by color) of tremor in each structure.
Average severity was calculated by taking the mean of all ratings (even those less than 0.75)
for each structure.
0
20
40
60
80
100 Mild
voice tremor
0
20
40
60
80
100Moderate
voice tremor
0
20
40
60
80
100
Severe
voice tremor
Mild structural severity
Mild-Moderate structural severity
Moderate structural severity
Moderate-Severe structural severity
Not rated
Per
cen
t p
arti
cip
ants
wit
h t
rem
or
in e
ach
str
uct
ure
80
Figure 6. Voice tremor severity during sustained /i/ as a function of Tremor Index. Tremor
Index can range from 0 (no tremor in any structure) to 3 (severe tremor in all structures), and
is calculated by multiplying the % of structures affected by the severity of tremor in those
structures. Filled shapes indicate group means.
0.0
0.5
1.0
1.5
2.0
2.5
3.0
0 50 100 150 200
Vo
ice
trem
or
sev
erit
y d
uri
ng
/i/
(0=
no
ne,
3=
sev
ere)
Tremor Index
(0=no tremor, 300=severe tremor in all 13 structures)
Mild voice tremor
Moderate voice tremor
Severe voice tremor
300
81
Figure 7. Relationship of age with a) voice tremor severity during sustained /i/, and b)
Tremor Index during sustained /i/.
a) Voice tremor severity as a function of age
b) Tremor Index as a function of age. Filled shapes indicate group means.
0.0
0.5
1.0
1.5
2.0
2.5
3.0
0 20 40 60 80 100
Vo
ice
trem
or
sev
erit
y
Age
(years)
65 and under
66-75 years
over 75
0
25
50
75
100
125
150
0 20 40 60 80 100
Tre
mo
r In
dex
(0 =
no
tre
mo
r, 3
00
= s
ever
e tr
emo
r
in a
ll s
tru
ctu
res)
Age
(years)
65 and under
66-75
over 75
Figure 8. Tremor distribution. Regions of the speech mechanism affected by tremor as a function of severity of voice tremor during a)
sustained /i/, b) sustained /s/, c) sustained /h/, and d) rest breathing.
a) Sustained /i/ b) Sustained /s/
c) Sustained /h/ d) Rest breathing
Regions affected
Sev
erit
y o
f voic
e tr
emor
du
rin
g s
ust
ain
ed /
i/
Respiratory Laryngeal Velophar. Oral
Co
ntr
ols
M
ild
M
od
erat
e S
ever
e
Regions affected
Sev
erit
y o
f voic
e tr
emor
du
rin
g s
ust
ain
ed /
s/
Oral Velophar. Laryngeal Respiratory
Co
ntr
ols
M
ild
M
od
N
o t
rem
or
Sev
Regions affected
Sev
erit
y o
f v
oic
e tr
emo
r
du
rin
g s
ust
ain
ed /
h/
Oral Velophar Laryngeal Respiratory
Co
ntr
ols
M
ild
M
od
N
o t
rem
or
Sev
Regions affected
Sev
erit
y o
f v
oic
e tr
emo
r
du
rin
g s
ust
ain
ed /
i/
Respiratory Laryngeal Velophar. Oral
Co
ntr
ols
M
ild
M
od
erat
e S
ever
e
82
Figure 9. Rate of occurrence and severity (indicated by color) of tremor in each structure for a) sustained /i/, b) sustained /s/, c)
sustained /h/, and d) rest breathing. Average severity was calculated by taking the mean of all ratings of 0.75 or greater for each
structure.
a) Sustained /i/ b) Sustained /s/
c) Sustained /h/ d) Rest breathing
17 20
33 35
65
90 95 94
35
20
35
20 10
0102030405060708090
100
0 5
0 5 5
63 56
41
29 28 22
5 0
0102030405060708090
100
0
10 11 10 5
43 43 44 53
29 29
10 0
5
0102030405060708090
100Mild structural severityMild-moderate structural severityModerate structural severityModerate-severe structural severityNot rated
0 0 0 0 5
37 39 28
12 7
13 15
0 5
0102030405060708090
100
Per
centa
ge
of
par
tici
pan
ts w
ith
tre
mor
(rat
ed 0
.75 o
r P
erce
nta
ge
of
par
tici
pan
ts w
ith
tre
mo
r (r
ated
0.7
5 o
r g
reat
er)
83
84
Figure 10. Sustained /s/ tremor severity as a function of Tremor Index. Filled shapes
indicate group means.
0.0
0.5
1.0
1.5
2.0
2.5
3.0
0 50 100 150
Voic
e tr
emor
sever
ity d
uri
ng s
ust
ain
ed /
s/
(0=
non
e, 3
=se
ver
e)
Tremor Index
(0=no tremor, 300=severe tremor in all 13 structures)
No voice tremor on /s/
Mild voice tremor on /s/
Moderate voice tremor on /s/
Severe voice tremor on /s/
300
85
Figure 11. Sustained /h/ tremor severity as a function of Tremor Index. Filled shapes
indicate group means.
0.0
0.5
1.0
1.5
2.0
2.5
3.0
0 50 100 150
Voic
e tr
emor
sever
ity d
uri
ng s
ust
ain
ed /
h/
(0=
non
e, 3
=se
ver
e)
Tremor Index
(0=no tremor, 300=severe tremor in all 14 structures)
No voice tremor on /h/
Mild voice tremor on /h/
Moderate voice tremor on /h/
Severe voice tremor on /h/
300
86
Figure 12. Interjudge agreement on a) number of participants with tremor and b) severity
of tremor for sustained phonation.
a)
b)
0
2
4
6
8
10
12
14
16
18
20N
um
ber
of
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ts a
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Mean
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Tre
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(0=
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rem
or,
3=
sever
e tr
emor)
Judge 1
Judge 2
Mean
87
Figure 13. Interjudge agreement on a) number of participants with tremor and b) severity
of tremor for sustained /s/.
a)
b)
0
2
4
6
8
10
12
14
16
18
20N
um
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0.0
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2.0
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Tre
mor
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ity i
n a
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str
uct
ure
s
(0=
no t
rem
or,
3=
sever
e tr
emor)
Judge 1
Judge 2
Mean
88
Figure 14. Interjudge agreement on a) number of participants with tremor and b) severity
of tremor for sustained /h/.
a)
b)
0
2
4
6
8
10
12
14
16
18
20N
um
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Judge 1
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0.0
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Tre
mor
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n a
ffec
ted
str
uct
ure
s
(0=
no t
rem
or,
3=
sever
e tr
emor)
Judge 1
Judge 2
Mean
89
Figure 15. Interjudge agreement on a) number of participants with tremor and b) severity
of tremor for rest breathing.
a)
b)
0
2
4
6
8
10
12
14
16
18
20N
um
ver
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Judge 1
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Mean
0.0
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1.0
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Tre
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n a
ffec
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(0=
no t
rem
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3=
sever
e tr
emor)
Judge 1
Judge 2
Mean
90
CHAPTER 4
DISCUSSION
Purpose
The purpose of this study was twofold: first, to describe the distribution and
severity of tremor in structures throughout the vocal tract in individuals with essential
vocal tremor, and second, to relate the distribution and severity data to the severity of
vocal tremor in these individuals. The main hypotheses underlying the study were that 1)
tremor is widespread in individuals with essential vocal tremor and not isolated to the
larynx or vocal folds and 2) the severity of the voice tremor is directly related to the
distribution and severity of the tremor throughout the vocal tract. The following
discussion will be divided into five major sections; first, the relationship of the
distribution and severity data to the severity of the voice tremor will be addressed.
Second, clinical implications related to assessment and treatment of vocal tremor will be
discussed. Third, the relationship between age and the severity of tremor will be
addressed. Fourth, the distribution and severity of tremor during sustained phonation will
be discussed in relation to the literature. And finally, the relationship between voiceless
sounds and respiratory tremor will be explored. Limitations of the study and future
directions will also be presented.
Does the Distribution and Severity of Tremor in Structures of the Vocal Tract
Predict Severity of the Voice Tremor?
This study was the first to examine all four regions of the vocal tract (respiratory,
laryngeal, velopharyngeal, and oral) in a cohort of participants with voice tremor and
relate that information to the severity of the voice tremor in those participants. The most
important, and clinically relevant finding, was that tremor distribution varied with the
severity of the voice tremor. In other words, individuals with severe voice tremor tended
to have greater distribution of tremor outside the larynx than individuals with mild or
moderate voice tremor. Although the laryngeal region was the primary location of tremor
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(i.e., where tremor was observed most often and with the greatest severity in all
participants) the results showed tremor was noted in other regions as well, particularly in
individuals with greater severity of voice tremor (see Figure 5). Those with mild voice
tremor tended to show tremor limited to structures of the larynx/hypopharynx, and in
some cases, the velopharynx, and on average, had three structures affected (most
commonly true vocal folds, supraglottic structures, and hypopharynx). Those with
moderate voice tremor tended to show tremor in the larynx and velopharynx, and on
average, had five structures affected (most commonly true vocal folds, supraglottic
structures, hypopharynx, vertical laryngeal movement, and some other velar, oral, or
respiratory structure). Those with severe voice tremor often showed tremor in the larynx,
velopharynx, and beyond; on average, those with severe voice tremor had eight structures
affected (most commonly true vocal folds, supraglottic structures, hypopharynx, vertical
laryngeal movement, anterior and lateral chest movement, velum, and jaw).
It seems that the combination of tremor in multiple structures contributes most to
the severity of the voice tremor. The supraglottic structures and vertical laryngeal
movement were identified as most correlated to voice tremor severity during sustained /i/.
The regression model using these variables was statistically significant, suggesting that
using these two variables could be a good predictor of voice tremor severity. The Tremor
Index, a composite number incorporating both distribution and severity of tremor
throughout the vocal tract, was strongly correlated to the severity of voice tremor (r =
0.72) and was statistically significant when used as a predictor variable in regression
modeling. This relationship suggests that as tremor is more widespread and greater in
severity, the severity of the voice tremor is likely to be higher. Further studies, with a
greater number of participants, may be able to determine whether particular structures or
regions should be weighted more heavily in the regression equation. For the purposes of
the current study, examining regression models with only one (Tremor Index) or two
variables (supraglottic structures and vertical laryngeal movement), the sample size was
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adequate. However, to analyze models with more variables (including the model with all
variables), a greater sample size should be used. (The regression analyses can be
completed as long as there are more participants than variables; however, best results are
achieved when the number of participants is 10 times the number of variables (Harrell,
Lee, Califf, Pryor, and Rosati, 1984).)
Clinical Implications
The findings presented in this study have important clinical implications for
practitioners working with patients with vocal tremor, both in terms of assessment and
treatment.
Assessment of voice and speech in individuals with voice tremor should include
evaluation of all four regions of the vocal tract (respiratory, laryngeal, velopharyngeal,
and oral). Typical assessments for individuals with movement disorders involve
endoscopy, mainly to view the structures of the larynx. However, as shown in Figure 5,
tremor often affects structures outside the larynx. Therefore, assessment of all regions
should be included in every evaluation.
Nasendoscopy, with a wide view allowing observation of the pharyngeal walls
and base of tongue in addition to the vocal folds and supraglottic structures should be the
procedure of choice for viewing both the velopharynx and larynx in individuals with
movement disorders. Few studies have provided detailed descriptions of endoscopic
evaluations during phonation in individuals with voice tremor (Bove, et al., 2006; Sulica
& Louis, 2010; Warrick, et al., 2000). Some studies have utilized laryngoscopy
(Hertegard, et al., 2000; Koda & Ludlow, 1992; Klotz et al., 2004), but have focused
assessment on the true vocal folds, failing to assess tremor in other structures near the
larynx, and especially, missing tremor in the velopharynx. Other studies (Brown &
Simonson, 1963; Hachinski et al., 1975; Massey & Paulson, 1985) have reported no
tremor in the true vocal folds, but failed to have patients phonate during the assessment.
Those studies that have used endoscopy to assess multiple structures during phonation
93
(Bove, et al., 2006; Sulica & Louis, 2010; Warrick, et al., 2000) showed results similar to
those reported in the current study (and will be discussed in detail later). In order to view
and assess for tremor of the velum and nasopharyngeal walls, a nasendoscopic procedure
must be used. Based on the relative frequency of occurrence of tremor in structures of the
velopharynx, this assessment is essential. The use of flexible nasendoscopy is also
beneficial for allowing the patient to perform a variety of speaking tasks during
assessment.
In addition to assessing the larynx and velopharynx, which has already been
reported in the literature, the results of the current study suggest assessment of the
respiratory and oral structures is essential in getting the “whole picture” of a patient’s
tremor. One previous study (Koda & Ludlow, 1992) has identified respiratory
involvement in individuals with voice tremor based on Respitrace. The comparison
between Respitrace and palpation presented in the current study suggests that using
palpation to assess tremor in the chest and abdomen would be a more efficient method,
and just as effective as Respitrace. It requires no extra equipment and can be performed
quickly. Palpation is also valuable in determining the severity of tremor affecting the
vertical movement of the larynx, rather than relying on endoscopic images comparing the
global movement of the larynx to surrounding tissue. Using endoscopy to identify
vertical laryngeal movement may lead to over-identification of tremor due to the
movement of the endoscope from velar tremor. For oral structures, direct observation
during sustained phonation is the most efficient method for determining severity of
tremor. Similar to palpation, direct observation of tremor in the oral structures is quick
and does not require extra equipment for assessment.
As practitioners assess the structures throughout the vocal tract for the presence of
tremor, it is also essential to rate the severity of tremor in those structures. To date, only
three studies described tremor severity ratings in structures of the vocal tract. Severity
ratings in all three of those studies were limited to structures in the larynx/hypopharynx
94
and velopharynx. Figure 5 showed that the severity of the voice tremor is related to both
the distribution of tremor and the severity of tremor throughout the vocal tract and it may
be useful to include all four regions.
The distribution and severity of tremor within an individual may directly relate to
treatment effectiveness, particularly with botulinum toxin injections to the larynx. The
most common treatment, currently, is botulinum toxin injection to the larynx, which is
likely to be most successful in individuals with tremor relatively limited to the larynx.
Generally, the injection is made into the thyroarytenoid muscle, which would be expected
to reduce the amplitude of the tremor in the vocal folds by temporarily weakening them.
The hypothesis that severity of tremor would be greatest within the true vocal folds,
however, was not supported by the data presented in this study. Although the true vocal
folds were frequently affected, the supraglottic and hypopharyngeal walls were just as
frequently affected and were rated as more severely affected. This suggests that other
targets may also be appropriate for therapy.
Knowing which structures are most affected by tremor in a particular individual
may help not only choose the most appropriate muscle to inject, but also improve
prognostic information provided to patients. Those with severe tremor in the true vocal
folds and less severe tremor elsewhere may respond better than those with severe tremor
in structures other than the true vocal folds (e.g., supraglottic structures and vertical
laryngeal movement). In fact, two studies have examined this matter, with equivocal
results. Bove and colleagues (2006) showed that those with more severe tremor in the
true vocal folds than in other structures benefitted more from thyroarytenoid botulinum
toxin injections than those with more severe tremor in other structures. However, Sulica
and Louis (2010) showed that participants grouped in the same way (participants with
more severe tremor in the true vocal folds than other structures vs participants with more
severe tremor in structures other than the vocal folds) did not respond differently to
botulinum toxin injections to the thyroarytenoid. The equivocal results between these two
95
studies could be related to the fact that only structures within the larynx and velopharynx
were assessed. Perhaps tremor of the respiratory or oral regions was a factor. The current
study shows that the distribution and severity of tremor throughout the entire vocal tract
is related to the severity of the voice tremor, and that individuals with mild voice tremor
tend to have the tremor limited to the larynx and velopharynx. These may be the
individuals that respond best to laryngeal botulinum toxin injections. The previous
studies alluded to a range of severities of voice tremor in their participants, but did not
provide ratings of the voice tremor severity or expand on whether the severity of the
voice tremor related to responsiveness to botulinum toxin injections to the larynx. Further
research is required to determine whether other locations would be better for injection,
but some potential injection sites may be the lateral cricoarytenoid (Maronian, Waugh,
Robinson, & Hillel, 2004), interarytenoids (Kendall & Leonard, 2011), false vocal folds
(Rosen & Murry, 1999), cricothyroid (Zalvan & Blitzer, 2004), thyrohyoid (Hertegard,
Granqvist, & Lindestad, 2006), and velum (Penney, Bruce & Saeed, 2006). The case
reporting botulinum toxin injection to the false vocal folds (Rosen & Murry, 1999) was in
a patient with hyperadduction of the false folds, not vocal tremor. Some authors have
suggested the sternothyroid muscles as a potential injection site (Zalvan & Blitzer, 2004),
but to date, no data has been published.
Identification of tremor within the velopharyngeal region may also influence
medical treatment with botulinum toxin injections. One study (Penney, Bruce, & Saeed,
2006) showed palatal botulinum toxin injections to be safe and effective for decreasing
oscillations in four of five individuals with palatal myoclonus. The injections reduced the
clicking associated with the palatal myoclonus. Although myoclonus is somewhat
different than essential tremor because it is isolated to the palate and has a slower rate of
oscillation, the results of that study indicate that botulinum toxin injections to the palate
are possible and could be considered for individuals with essential tremor affecting the
velum. The relatively high incidence of tremor in velopharyngeal structures suggests the
96
need for further research to determine the risks and benefits of palatal botulinum toxin
injection for tremor.
Individuals who experience widespread and severe tremor outside the larynx may
benefit from the addition of a behavioral therapy approach for improving voice. Little
evidence is available on the effectiveness of behavioral techniques for improving
intelligibility, however. One potential technique that has shown promise is shortening
vowel durations during connected speech (Lederle, Barkmeier-Kraemer, & Finnegan,
2007; Twohig, Hemmerich, & Finnegan, 2009). Future studies should further examine
the effectiveness of this technique, as well as techniques aimed at changing respiratory
support for speech or altering speaking style (e.g., using a breathy quality) to reduce the
effects of the tremor on the voice.
Does the Distribution and Severity of Tremor Change With Age?
Although assessing age-related changes in tremor was not a primary goal of this
study, the results did indicate that older individuals tended to have a more severe voice
tremor than younger individuals. This idea that voice tremor worsens with age has been
suggested frequently in the literature, and the results presented in Figure 7a support that
hypothesis. In addition to worsening voice tremor severity, however, the current study
has also shown that the distribution and severity of tremor, as summarized by the Tremor
Index, is also greater in older individuals (Figure 7b). In particular, those over the age of
65 showed greater Tremor Index values than those under age 65. As tremor has been
shown to have a bimodal age of onset, with the upper age of onset in the 6th
decade (Lou
& Jankovic, 1991), it is not surprising that those individuals over 65, who have had
tremor for years, show greater severity of symptoms. The question to be answered in a
future study, however, is why some individuals in the middle range (66-75 years) show
greater distribution and severity of tremor in structures of the vocal tract, but do not show
greater severity of voice symptoms. This suggests that another factor may play a role in
the severity of the voice tremor.
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Comparison of Results to the Literature
Mean tremor ratings for each participant support the hypotheses that multiple
structures and regions are affected by tremor in individuals with voice tremor, as 95%
had tremor in more than one structure and 70% of participants with vocal tremor had
tremor in multiple regions. These ratings also support the hypothesis that the
larynx/hypopharynx is one of the most frequently affected structures, but that tremor is
rarely limited to the true vocal folds.
The frequent occurrence of tremor in the larynx was similar to that reported in the
literature (Koda & Ludlow, 1992; Warrick et al., 2000; Sulica & Louis, 2010), as was the
frequency of occurrence reported for the respiratory (Koda & Ludlow, 1992) and oral
regions (Warrick, et al., 2000); the occurrence of tremor was about half of that reported in
the literature for the velopharyngeal region (Warrick, et al., 2000; Sulica & Louis, 2010).
However, this study was the first to examine all of those regions in the same group of
participants. Each region will be described separately below.
Respiratory region. The tremor occurrence in 33% of participants based on
Respitrace was equivalent to previously reported data (Koda & Ludlow, 1992). The
previous study using Respitrace found two of seven participants had respiratory tremor
(roughly 25%), but did not report whether differences in chest and abdominal tremor
were noted. The current study included twenty participants (with tremor found in 33% in
both the chest and the abdomen, although participants did not always show tremor in both
the chest and abdomen).
Tremor occurrence based on palpation was also equivalent to the occurrence
reported by Koda and Ludlow (1992). Palpation is a more efficient method of assessing
tremor within the chest and abdomen than using Respitrace because no extra equipment
is needed. Identification of tremor using palpation resulted in similar numbers of
participants being identified as in Respitrace. Additional support for the validity of the
palpation method was the rating of no tremor for both control participants. Further study
98
is required to determine the best severity rating scale for assessment of movements of the
chest and abdomen.
The comparison of the presence of tremor within specific structures, including the
diaphragm, sternocleidomastoid, and rectus abdominis, as reported in the case studies in
the literature, cannot be completed (Ardran, et al., 1966; Hachinski et al., 1975; Massey
& Paulson, 1985; Tomoda et al., 1987). The limitation of the current study was that only
broad sections of the respiratory region were assessed by the palpation method utilized,
limiting extrapolation to particular muscles. It could be inferred that anterior abdominal
movement may correspond to rectus abdominus tremor, for example, but EMG studies
would be needed to corroborate that hypothesis. Specific muscles corresponding to the
lateral abdominals, anterior chest, and lateral chest assessed by palpation cannot be
clearly differentiated.
Laryngeal region. The high occurrence of tremor in the true vocal folds (90%) and
supraglottic structures (95%) was similar to Sulica and Louis (2010), Warrick and
colleagues (2000), and Koda and Ludlow (1992) who used a nearly identical
methodology for assessment for these structures, including phonation during assessment.
The occurrence of tremor was also similar to the compiled frequency from all reports
using laryngoscopy, although in those studies, it was unclear whether participants were
phonating during assessment (Brown & Simonson, 1963; Hachinski et al., 1975; Klotz et
al., 2004; Massey & Paulson, 1985). Specifically, Sulica and Louis (2010) found tremor
in 100% of participants for the true vocal folds and in 94% for the supraglottic structures,
while Warrick and colleagues (2000) and Koda and Ludlow (1992) identified tremor in
100% of participants for the true vocal folds.
Tremor in the hypopharyngeal walls was identified much more often (94%) than
previous studies (50%) (Sulica & Louis, 2010; Warrick et al., 2000). The difference in
pharyngeal wall occurrence is likely related to the definition of the structure being rated.
Sulica and Louis (2010), following the instructions for the Vocal Tremor Scoring System
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(Bove et al, 2006), rated the pharyngeal wall tremor only in the medial-lateral dimension
(in 59%), while in the current study, medial-lateral and antero-posterior movement were
included as pharyngeal wall tremor. Warrick and colleagues (2000) reported a frequency
of 20% when rating the “pharyngeal” structures but did not define that parameter, so it is
unclear exactly what portion of the pharynx was being rated.
Vertical movements of the larynx were identified in 65%, roughly as often as
expected (71%) based on compiled reports from the literature (Finnegan et al., 2003;
Koda & Ludlow, 1992; Sulica & Louis, 2010; Warrick et al., 2000). Several studies
identified vertical movement less often (Finnegan et al., 2003; Warrick et al., 2000),
while others identified it more often (Koda & Ludlow, 1992; Sulica & Louis, 2010). The
difference in vertical laryngeal movement is likely related to the method of assessment.
Both Finnegan et al. (2003) and Koda & Ludlow (1992) assessed tremor within specific
extrinsic muscles using EMG. Finnegan and colleagues found tremor in the sternothyroid
and thyrohyoid muscles in one of six participants. It is possible that other extrinsic
muscles besides the sternothyroid and thyrohyoid muscles (such as suprahyoid muscles
like the anterior digastric, mylohyoid, and geniohyoid) may result in the vertical
movements, although the sternothyroid and thyrohyoid do seem to be likely contributors.
Koda and Ludlow (1992) found tremor in the sternothyroid and thyrohyoid muscles of all
three of the participants they assessed. Sulica and Louis (2010) used the Vocal Tremor
Scoring System (Bove, et al., 2006), while Warrick et al. (2000) and Koda and Ludlow
(1992) assessed vertical movement during endoscopy, by comparing the laryngeal unit to
the surrounding tissue. Warrick and colleagues (2000) identified tremor in only 10% of
participants, but Sulica and Louis (2010) and Koda and Ludlow (1992) found tremor in
nearly all participants (85% for Sulica & Louis, 100% for Koda and Ludlow). The
experience of the primary investigator was that movement of the palate, and thus the
endoscope, could affect this perception of movement of the larynx as a unit. It was for
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this reason that palpation of the larynx was used in the current study in an effort to get a
more accurate assessment of the movement.
Velopharyngeal region. Palatal tremor was identified less often (35%) than
reports in the literature (82%) (Sulica & Louis, 2010; Warrick et al., 2000). Using
flexible laryngoscopy to view the superior surface of the palate, Sulica and Louis (2010)
reported occurrence of tremor in 88% for the velar tremor, while Warrick and colleagues
reported 60% of participants experienced velar tremor. These high frequencies of
occurrence of tremor may be related to posturing movements of the velum. In the current
study, during assessment of tremor of the superior surface of the velum and the
pharyngeal walls surrounding the velopharyngeal port, the judges noted that postural
movements, such as preparing to speak or swallow, were easily mistaken for tremor
during short video clips. Therefore, two control participants were included and used as
guides as to what was normal movement of the velum and velopharyngeal walls during
each task. Previous studies did not include control participants, so it is unclear whether
they may have rated some normal positioning-type movements of the velum and
pharyngeal walls as tremulous.
Occurrence of tremor within the velopharyngeal walls (20%) was lower than the
occurrence reported by Sulica and Louis (2010), but equivalent to the occurrence
reported by Warrick and colleagues (2000). The higher occurrence of tremor reported by
Sulica and Louis (2010) may be due to the definition of the pharyngeal walls. Based on
the VTSS (Bove et al., 2006) used by Sulica and Louis (2010) and the methodology
reported by Warrick and colleagues (2000), it is not clear whether the pharyngeal wall
being assessed is in the nasopharynx, oropharynx, or hypopharynx.
Oral region. Tremor occurrence within the tongue (20%) and lips (10%) are
comparable to data reported by Warrick and colleagues (2000) (30% with tongue tremor
and 10% with lip tremor); this was the only study that assessed any oral structures in a
group of participants with vocal tremor during sustained phonation. Other studies in the
101
literature were either case studies or prevalence studies, and often did not require
participants to phonate during assessment.
Jaw tremor occurred more often than that reported in the literature (Hornabrook,
1976), where 25% of individuals with essential tremor were observed to have jaw tremor.
That study did not elaborate on the presence of voice tremor, nor did it describe what task
individuals were performing. It is possible that activation of jaw muscles during
production of a sustained vowel, such as /a/, would lead to tremor more often.
No previous study has assessed tremor distribution throughout the vocal tract.
Although the frequency of occurrence of tremor in each region was comparable to
previous studies, until this study, it was not clear how often each region would be
expected to be affected in a particular individual with voice tremor. Based on the results
presented here, individuals with severe voice tremor could be expected to show tremor in
most regions of the vocal tract, while individuals with mild voice tremor could be
expected to show tremor restricted to the larynx.
Tremor severity. Tremor severity ratings for structures within the respiratory and
oral regions have not been reported previously. Therefore, this section will focus on
tremor severity in laryngeal and velopharyngeal structures.
Tremor severity ratings were mild-moderate for the true vocal folds (mean=1.58,
7 mild, 7 moderate, 4 severe), supraglottic structures (mean=1.66, 6 mild, 9 moderate, 3
severe), and velum (mean=1.32, 4 mild, 3 moderate), which was less severe than those
reported by Koda & Ludlow, 1992 but similar to those reported by Sulica & Louis, 2010.
Koda and Ludlow (1992) reported moderate-severe vocal fold tremor during phonation
(mean=2.25, 1 mild, 4 moderate, 3 severe). The smaller number of participants with mild
tremor may be related to the smaller sample size. Sulica and Louis (2010) reported mild
levels of vocal fold tremor severity with almost the exact same ratio of mild-to-moderate-
to-severe (mean=1.8, 13 mild, 15 moderate, 6 severe) as the current study. Severity
ratings for the supraglottic structures (mean=1.9, 8 mild, 16 moderate, 8 severe) and the
102
velum (mean=1.3, 18 mild, 10 moderate, 2 severe) reported by Sulica and Louis (2010)
were also comparable.
Tremor severity was mild for the vertical laryngeal movement (mean=1.25, 10
mild, 3 moderate) and moderate for the hypopharyngeal walls (mean=2.13, 1 mild, 8
moderate, 7 severe), more severe than previously reported (Sulica & Louis, 2010).
Vertical laryngeal movement was rated as absent or mild more often in this study than by
Sulica and Louis (2010) (mean=1.5, 9 mild, 18 moderate, 2 severe), as evidenced by
more participants found in the mild category and no participants rated as having severe
vertical laryngeal movement in this study. This could have been due to the use of
palpation rather than endoscopy for assessment. Pharyngeal wall tremor was rated as
moderate and severe more frequently than Sulica and Louis (2010) (mean=1.0, 11 mild, 5
moderate, 4 severe). The greater severity ratings could be explained by the rating of
anterior-posterior movements in additional to medial-lateral movements in the current
study, and a separation of the pharyngeal walls into superior and inferior portions. The
lateral nasopharyngeal wall severity ratings from the current study, which were made
based on medial-lateral movement of the velopharyngeal walls (mean=1.31, 3 mild, 1
moderate), were comparable to Sulica and Louis (2010). Based on the use of the Vocal
Tremor Scoring System (Bove et al., 2006), it is likely Sulica and Louis (2010) rated
more superior portions of the pharyngeal wall (probably corresponding to the upper
portion of the middle pharyngeal constrictor).
As stated previously, tremor severity in respiratory and oral structures has not
been reported prior to this study. Tremor was generally mild in both regions across tasks.
Four participants showed mild-moderate to moderate severity of tremor in the chest and
abdomen and oral structures. Future research could further assess tremor severity in these
structures, possibly in relation to connected speech.
Structures located near one another within the vocal tract tended to have similar
levels of severity. The correlations presented in Table 4 showed that some structures
103
varied together (e.g., the true vocal folds and supraglottic structures). There are two
potential explanations for the similar severity ratings in nearby structures. First, because
tremor is a neurological condition, it could be expected that structures with the same
innervation would show similar ratings of severity of tremor. This hypothesis is
supported by the fact that within any particular region, where most structures have similar
innervations (except for the oral region), ratings of severity were closely related (see
Table 22 for a list of structures and innervations). Of note, the severity of tremor in the
true vocal folds (with the thyroarytenoid muscle innervated by the recurrent laryngeal
nerve) and the vertical laryngeal movement (anterior neck muscles innervated by a
combination of facial, trigeminal, and ansa cervicalis) were not as highly correlated as
other structures in the laryngeal region during sustained phonation. The second potential
explanation for the similar severity ratings in structures is a mechanical linkage between
the structures (i.e., tissue is actually connecting the two structures, so when one moves,
the other is forced to move as well). Many of the highly correlated severity ratings within
a particular region would support this hypothesis as well. For example, the true vocal
folds are connected to the supraglottic structures via mucosal tissue and attachments to
the arytenoids, so as the vocal folds show tremor, the supraglottic structures would also
show tremor. This hypothesis better explains the relationship between structures in the
oral region, where the innervations for the jaw, lips, and tongue are all from different
cranial nerves but similar levels of tremor severity were seen. An additional support for
this explanation is provided by the similar ratings of severity noted in the velopharyngeal
region and the tongue, which are linked via the palatoglossus muscle and mucosal tissue.
Does Tremor During Voiceless Sounds Relate to Respiratory Tremor?
Respiratory tremor has only been reported in a small number of studies, likely due
to the difficult nature in assessing its presence and severity. The current study aimed to
isolate the presence of respiratory tremor by rating tremor in structures of the vocal tract
during sustained voiceless sounds. The hypothesis was that, with structures of the upper
104
vocal tract in a relaxed position, if tremor was present, it would be due to oscillations
within muscles of either the chest or abdomen. Data obtained from sustained /s/ and /h/
do not support this hypothesis, however, as the most frequent locations of tremor during
these tasks were the larynx and velopharynx. Because there was no improvement in
identification of respiratory tremor by using voiceless sounds, these could be eliminated
from the assessment protocol for individuals with voice tremor.
Specifically, tremor was observed in the vocal folds in 63% (10/16) of the
participants for /s/ and 43% (3/7) for /h/ and vertical laryngeal movement was observed
in 5% (1/20) of the participants for /s/ and /h/. Koda and Ludlow (1992) observed tremor
in the vocal folds in 63% (5/8) of participants and vertical laryngeal movement in 50%
(4/8) of participants during whispered phonation. The findings for vocal fold tremor in
the current study were consistent with findings by Koda and Ludlow (1992), but much
lower for vertical laryngeal movement. The severity of the tremor in the true vocal folds
(mean=1.30) was similar to that found by Koda and Ludlow (1992) (1.25), while the
severity of the vertical laryngeal movement (mean=0.10) was lower than their finding
(mean=0.75). The participants in the study by Koda and Ludlow (1992) were asked to
whisper, which may have resulted in slightly different laryngeal behavior than when a
participant is asked to sustain an /s/ or /h/ sound.
Rest breathing, another task where the upper vocal tract structures are activated
less than during phonation, also showed tremor often in structures of the larynx (9/20 or
45%). Laryngeal tremor during breathing has been reported previously (Koda & Ludlow,
1992; Sulica & Louis, 2010). Specifically, Koda and Ludlow (1992) found that one of
their eight participants (13%) had tremor in the true vocal folds during inhalation, but six
of eight (75%) had tremor during exhalation. Sulica and Louis (2010) observed tremor in
74% of their patients during quiet respiration, which was generally mild or intermittent.
The presence of tremor at “rest” may relate to the fact that laryngeal muscles are never
fully relaxed (Sulica & Louis, 2010). Therefore, it is always possible to observe
105
tremulous movements. A similar explanation could be applied to the laryngeal structures
during sustained /s/ and /h/, where the vocal folds should be abducted and relatively
relaxed, but are probably not fully at rest.
Problems and Difficulties
Several problems arose during the course of the study that may be addressed in
future studies. First, tremor was identified in structures rather than specific muscles.
Although this study serves as a starting point, knowledge of specific muscles would
improve treatment planning. Future studies could use EMG to assess particular muscles
within areas where multiple muscles could be affected by tremor, such as the vertical
laryngeal movement. Second, out of necessity for making individual ratings of severity
via palpation, the judges assessed the participants at different times (usually within
minutes of each other). On some occasions, however, the judges saw participants on
different days. These differing times of assessment, even over the matter of minutes, may
allow for different amounts of tremor to be observed. Tremor is not perfectly consistent
all the time within an individual, so it is possible that one judge observed and assessed
different tremor symptoms than the other judge. In future studies, judges should assess
participants as closely together as possible to minimize variability in tremor observed.
Oral structure exams could be also included as part of the endoscopy, capturing video of
the participant’s face and inside the oral cavity as they phonated.
A third issue was the assessment of the respiratory region structures. Palpation of
the chest and abdomen was included to try to assess the tremor in the respiratory region
in a more efficient manner than using Respitrace, which requires extra equipment that not
all clinicians have available. This method of assessment had not been used previously,
and although there was good agreement between Respitrace and palpation regarding the
presence of tremor, the judges had difficulty calibrating their severity ratings, resulting in
low correlations between the judges’ ratings. Although the rating scale provided options
for rating the tremor as absent to severe, perhaps a better option would be to rate tremor
106
as present or absent. Using a simplified severity scale for palpation (perhaps ratings of
0=no tremor, 1=mild tremor, 2=moderate tremor, and 3=severe tremor) may also improve
reliability between judges.
A fourth problem that arose was the inability to view some structures within the
velopharyngeal region or laryngeal region for some participants due to difficulty
tolerating the nasendoscope or closing off the pharynx during production of some sounds
(particularly /h/). This resulted in a number of participants missing data for some tasks,
which limits the power of the statistical analyses. Correlations and other statistics
reported in this study should be interpreted with caution due to the small number of
participants relative to the number of structures assessed. It is a helpful starting point, but
further study, with many more participants, is required to gain stronger support. Based on
the results of this study, the use of voiceless sounds does not appear to improve
assessment of the chest or abdominal tremor. Perhaps assessment of only sustained
phonation and rest breathing is necessary, which many participants tolerated without
difficulty.
Conclusion
The current study showed that tremor often affects multiple structures involved in
phonation, including structures within and outside the larynx. The first hypothesis, that
half of the participants would show tremor in multiple regions, was supported, as 70% of
participants with vocal tremor showed tremor in more than one region. Individuals with
mild voice tremor often showed tremor only in the larynx, while individuals with severe
voice tremor often showed tremor in all four regions. The second hypothesis stated that
75% of participants would show tremor in the larynx, 50% would show tremor in the
velopharynx, and 25% would show tremor in the respiratory and oral regions. Tremor
was identified in the larynx in 95% of participants, but the velopharyngeal, respiratory,
and oral regions were affected in 40%. The third hypothesis, that all participants would
show tremor in more than one structure, was supported. All but one participant did show
107
tremor in multiple structures. The fourth hypothesis stated that tremor would occur most
often in the true vocal folds (affecting 80%), while 75% of participants would show
vertical laryngeal movement. Data presented in this study were slightly higher for the true
vocal folds (90%), and slightly lower for the vertical movement of the larynx (65%).
The fifth hypothesis stated that tremor of the true vocal folds would be more
correlated to the severity of the voice tremor than other structures. This was not
supported, as other structures of the larynx, the supraglottic structures and vertical
laryngeal movement, were identified as those contributing most to the voice tremor
severity. The sixth hypothesis stated that the respiratory structures would be most
correlated to the severity of the voice tremor during voiceless sounds. This was partially
supported, as tremor was identified most often within the larynx during sustained /s/ and
/h/, but statistical analyses identified the velum and anterior movement of the abdomen as
most correlated to the severity of voice tremor during sustained /s/.
The seventh hypothesis stated that as the distribution and severity of tremor
within the vocal tract increased, the severity of the voice tremor would increase. This
hypothesis was supported (Figure 5); in particular, the Tremor Index demonstrated a
strong correlation to the severity of the voice tremor.
Information presented in this study may be useful in treatment for individuals
with voice tremor, both in terms of behavioral treatment and the use of botulinum toxin
injections. Those individuals wishing to reduce the severity of the tremor through
behavioral treatment methods may require techniques addressing the entire vocal tract,
including respiratory training, laryngeal maneuvers, and possibly velopharyngeal
maneuvers, while those receiving botulinum toxin injections may benefit from alternate
locations for injection.
108
Table 22. Structures and innervations of the vocal tract.
Structure Innervation
Abdominals T7-T12, L1-L2, Iliohypogastric,
Ilioinguinal
Chest T1-T11
Vertical Laryngeal Movement Trigeminal, Facial, Spinal Accessory,
Hypoglossal, Superior Root of Ansa
Cervicalis (C1)
True Vocal Folds Vagus - Recurrent Laryngeal Nerve
Supraglottic Structures Vagus – Recurrent Laryngeal Nerve
Medial Pharyngeal Walls Vagus - Pharyngeal Branch
Base of Tongue Hypoglossal
Velum Vagus - Pharyngeal Branch
Superior Pharyngeal Walls Vagus - Pharyngeal Branch,
Glossopharyngeal – Pharyngeal Branch (for
stylopharyngeus)
Jaw Trigeminal – Mandibular Branch
Tongue Hypoglossal
Lips Facial
109
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113
APPENDIX A
MOVEMENT DISORDER VOICE EVALUATION
History Form (tremor vs PD vs SD vs dystonia vs MTD)
Name: _______________________ Date: _______________________
Address: _______________________ Botox Dose: _______________________
_______________________ Last Inj.: _______________________
Total # of Injections: _______________
Birthdate _______________________ Age: _______________________
Phone: _______________________ Examiner: _______________________
History
Laryngoscopy: (date, findings, attach evaluation sheet)
Description of the problem and cause (onset, symptoms, variability):
When did your voice problem begin?
Was the onset gradual or sudden?
Describe your voice problem:
Are there times of day (or of the year) that your voice is better or worse?
How does your voice problem affect your daily life?
On a scale of 1-10, how much of an effect does it have? (1=no effect, 10=severe effect)
Treated?
Untreated?
Tremor:
Do you experience tremor? Where?
114
Any sign of tremor in: If yes, rate severity:
Head yes no 1 2 3
Hand yes no 1 2 3
Upper extremities yes no 1 2 3
Lower extremities yes no 1 2 3
Scale: 1=mild, 2=moderate, 3=severe
Does anyone in your family have tremor? If so, who and what type (head, hand, voice,
etc.)?
Dystonia:
Are there particular sounds that are more difficult for you to say?
Do you have dystonia anywhere in your body? Where?
__ Blepharospasm
__ Midface (Meige’s Syndrome)
__ Spasmodic torticollis
__ Jaw dystonia
__ Writers’ cramp
__ Laryngeal dystonia
Have you received Botox for dystonia? (Duration, dosage, and physician)
Stress:
Have you recently, chronically, or at the time of onset experienced a traumatic or
stressful event? Describe…
Do you currently have, or have you ever experienced any of the following:
Anterior neck tenderness
Neck and shoulder tension/pain
Facial tension/TMJ
Back pain
Gastroesophageal reflux (GERD/LPR)
Ulcers
Headaches
Anxiety
Depression
115
Parkinson’s Disease:
Have you noticed changes in motor function? Describe.
Any indicators of PD
__ Masked facies
__ Fenestrated gait
__ Rapid bursts of speech
__ Monotone
__ Monoloudness
Have you seen a neurologist? If so, when?
Voice Therapy:
Have you ever tried voice therapy?
Was it effective?
What did you do in therapy?
(When, how long, with whom, strategies, do you still use the strategies?)
Medical Information
Foods/Medications:
Alcohol (effect on voice): ____________ Caffeine (effect on voice) ____________
Aspirin containing painkillers: ____________
Effects of Botox
Do you usually respond well to Botox injection? Yes No
Have you ever noticed that the effects of the Botox injection seem to affect other
structures? *(especially for patients with tremor in multiple structures)
Yes No
If yes, which structures?
116
APPENDIX B
CLINICAL TREMOR EVALUATION FORM
Participant ID:_____________________ Date: __________________
Evaluator:__________________
PERCEPTUAL RATINGS
Take a deep breath and sustain each sound as long and steady as you can. For the
sustained phonation, use a comfortable pitch and volume.
Rate perceptual severity:
Scale: 0=no tremor, 0.5=slight, 1=mild, 1.5=mild-moderate, 2=moderate, 2.5=moderate-
severe, 3=severe
Sustained h 0 0.5 1 1.5 2 2.5 3
Sustained s 0 0.5 1 1.5 2 2.5 3
Sustained ah 0 0.5 1 1.5 2 2.5 3
During reading: 0 0.5 1 1.5 2 2.5 3
Is the tremor more evident at the beginning, middle, or end of each sustained sound?
Voice quality: (Describe in terms of consistency, severity, and quality and any related
observation: pitch breaks, phonation breaks, hard glottal attack, glottal fry, tremor,
monotone… Describe the conversational voice as completely and concisely as possible)
Comments:
117
RESPIRATION
Palpate the chest wall and abdominals during the following tasks. Place one hand
horizontally over the sternum for the anterior chest wall. Place each hand vertically just
below the armpit for the lateral chest walls. Place one hand horizontally over the belly
button for the anterior abdominals. Place each hand vertically just above the hip bone for
the lateral abdominals. For sustained sounds, take a deep breath and sustain them as long
and steady as you can.
Rate severity of movement: Scale: 0=no tremor,0.5=slight, 1=mild, 1.5=mild-moderate, 2=moderate, 2.5=moderate-
severe, 3=severe
Rest breathing
Anterior Chest Wall 0 0.5 1 1.5 2 2.5 3
Lateral Chest Wall 0 0.5 1 1.5 2 2.5 3
Anterior Abdominals 0 0.5 1 1.5 2 2.5 3
Lateral Abdominals 0 0.5 1 1.5 2 2.5 3
Sustained h
Anterior Chest Wall 0 0.5 1 1.5 2 2.5 3
Lateral Chest Wall 0 0.5 1 1.5 2 2.5 3
Anterior Abdominals 0 0.5 1 1.5 2 2.5 3
Lateral Abdominals 0 0.5 1 1.5 2 2.5 3
Sustained s
Anterior Chest Wall 0 0.5 1 1.5 2 2.5 3
Lateral Chest Wall 0 0.5 1 1.5 2 2.5 3
Anterior Abdominals 0 0.5 1 1.5 2 2.5 3
Lateral Abdominals 0 0.5 1 1.5 2 2.5 3
Sustained ah
Anterior Chest Wall 0 0.5 1 1.5 2 2.5 3
Lateral Chest Wall 0 0.5 1 1.5 2 2.5 3
Anterior Abdominals 0 0.5 1 1.5 2 2.5 3
Lateral Abdominals 0 0.5 1 1.5 2 2.5 3
Loud sustained ah (Take a deep breath and say ah loudly)
Anterior Chest Wall 0 0.5 1 1.5 2 2.5 3
Lateral Chest Wall 0 0.5 1 1.5 2 2.5 3
Anterior Abdominals 0 0.5 1 1.5 2 2.5 3
Lateral Abdominals 0 0.5 1 1.5 2 2.5 3
Soft sustained ah (Take a small breath and say ah softly, pushing the air out at the end)
Anterior Chest Wall 0 0.5 1 1.5 2 2.5 3
Lateral Chest Wall 0 0.5 1 1.5 2 2.5 3
Anterior Abdominals 0 0.5 1 1.5 2 2.5 3
Lateral Abdominals 0 0.5 1 1.5 2 2.5 3
Comments:
118
LARYNGEAL FUNCTION
Palpate and visualize the position of the larynx in the neck during the following tasks.
Place the 1nd
, 1.5rd
, and 2th
fingers over the thyroid and cricoid cartilages and feel for
rhythmic vertical movement of the larynx. For sustained sounds, take a deep breath and
sustain them as long and steady as you can.
Rate severity of vertical movement of the larynx:
Scale: 0=no tremor, 0.5=slight, 1=mild, 1.5=mild-moderate, 2=moderate, 2.5=moderate-
severe, 3=severe
Rest breathing 0 0.5 1 1.5 2 2.5 3
Sustained h 0 0.5 1 1.5 2 2.5 3
Sustained s 0 0.5 1 1.5 2 2.5 3
Sustained ah 0 0.5 1 1.5 2 2.5 3
Loud sustained ah 0 0.5 1 1.5 2 2.5 3
Soft sustained ah 0 0.5 1 1.5 2 2.5 3
Comments:
ORAL MECHANISM EXAMINATION
Observe the oral structures with the patient’s mouth open at rest and during sustained /h/
and /a/. Observe structures outside the oral cavity during a sustained /s/ for any
movement.
Rate severity of movement of structures:
Scale: 0=no tremor, 0.5=slight, 1=mild, 1.5=mild-moderate, 2=moderate, 2.5=moderate-
severe, 3=severe
Rest breathing
Chin/jaw 0 0.5 1 1.5 2 2.5 3
Lips 0 0.5 1 1.5 2 2.5 3
Tongue 0 0.5 1 1.5 2 2.5 3
Sustained h
Chin/jaw 0 0.5 1 1.5 2 2.5 3
Lips 0 0.5 1 1.5 2 2.5 3
Tongue 0 0.5 1 1.5 2 2.5 3
Sustained s
Chin/jaw 0 0.5 1 1.5 2 2.5 3
Lips 0 0.5 1 1.5 2 2.5 3
Sustained ah
Chin/jaw 0 0.5 1 1.5 2 2.5 3
Lips 0 0.5 1 1.5 2 2.5 3
Tongue 0 0.5 1 1.5 2 2.5 3
Comments:
119
APPENDIX C
AUDIO CLIP RATING FORM
Evaluator:____________________________
Listen to each clip and rate the severity of the tremor using the scale provided. Please
rate only the tremor severity, ignoring breathiness, roughness, or harshness and any other
voice characteristics. Descriptions of each severity level are provided below. You may
listen to each clip as many times as necessary to make your rating. You may go back and
listen to previous clips as needed.
Scale: Description
0 I don’t hear any tremor.
0.5 I think I hear tremor, but it’s inconsistent and hard to tell.
1 I hear tremor (shakiness), but it’s just barely noticeable.
1.5 I definitely hear periodic modulations that are small to moderate,
making the voice sound mildly shaky.
2 I hear moderate to large periodic modulations, making the voice
sound moderately shaky.
2.5 I hear moderate to large periodic modulations, making the voice
sound moderately or severely shaky with occasional breaks.
3 I hear large periodic modulations, making the voice sound severely
shaky with frequent breaks.
Sustained /s/
Clip 1 0 0.5 1 1.5 2 2.5 3
Clip 2 0 0.5 1 1.5 2 2.5 3
Clip 3 0 0.5 1 1.5 2 2.5 3
Clip 4 0 0.5 1 1.5 2 2.5 3
Clip 5 0 0.5 1 1.5 2 2.5 3
Clip 6 0 0.5 1 1.5 2 2.5 3
Clip 7 0 0.5 1 1.5 2 2.5 3
Clip 8 0 0.5 1 1.5 2 2.5 3
Clip 9 0 0.5 1 1.5 2 2.5 3
Clip 10 0 0.5 1 1.5 2 2.5 3
Clip 11 0 0.5 1 1.5 2 2.5 3
Clip 12 0 0.5 1 1.5 2 2.5 3
Clip 13 0 0.5 1 1.5 2 2.5 3
120
Sustained /h/
Clip 1 0 0.5 1 1.5 2 2.5 3
Clip 2 0 0.5 1 1.5 2 2.5 3
Clip 3 0 0.5 1 1.5 2 2.5 3
Clip 4 0 0.5 1 1.5 2 2.5 3
Clip 5 0 0.5 1 1.5 2 2.5 3
Clip 6 0 0.5 1 1.5 2 2.5 3
Clip 7 0 0.5 1 1.5 2 2.5 3
Clip 8 0 0.5 1 1.5 2 2.5 3
Clip 9 0 0.5 1 1.5 2 2.5 3
Clip 10 0 0.5 1 1.5 2 2.5 3
Clip 11 0 0.5 1 1.5 2 2.5 3
Clip 12 0 0.5 1 1.5 2 2.5 3
Clip 13 0 0.5 1 1.5 2 2.5 3
Sustained /a/
Clip 1 0 0.5 1 1.5 2 2.5 3
Clip 2 0 0.5 1 1.5 2 2.5 3
Clip 3 0 0.5 1 1.5 2 2.5 3
Clip 4 0 0.5 1 1.5 2 2.5 3
Clip 5 0 0.5 1 1.5 2 2.5 3
Clip 6 0 0.5 1 1.5 2 2.5 3
Clip 7 0 0.5 1 1.5 2 2.5 3
Clip 8 0 0.5 1 1.5 2 2.5 3
Clip 9 0 0.5 1 1.5 2 2.5 3
Clip 10 0 0.5 1 1.5 2 2.5 3
Clip 11 0 0.5 1 1.5 2 2.5 3
Clip 12 0 0.5 1 1.5 2 2.5 3
Clip 13 0 0.5 1 1.5 2 2.5 3
Rainbow Passage
Clip 1 0 0.5 1 1.5 2 2.5 3
Clip 2 0 0.5 1 1.5 2 2.5 3
Clip 3 0 0.5 1 1.5 2 2.5 3
Clip 4 0 0.5 1 1.5 2 2.5 3
Clip 5 0 0.5 1 1.5 2 2.5 3
Clip 6 0 0.5 1 1.5 2 2.5 3
Clip 7 0 0.5 1 1.5 2 2.5 3
Clip 8 0 0.5 1 1.5 2 2.5 3
Clip 9 0 0.5 1 1.5 2 2.5 3
Clip 10 0 0.5 1 1.5 2 2.5 3
Clip 11 0 0.5 1 1.5 2 2.5 3
Clip 12 0 0.5 1 1.5 2 2.5 3
Clip 13 0 0.5 1 1.5 2 2.5 3
121
APPENDIX D
VIDEO CLIP RATING FORM - VELOPHARYNGEAL VIEW Evaluator:____________________________
View each clip and rate the severity of the tremor using the scale provided. Please rate
only the tremor severity, ignoring redness, swelling, or any other characteristics. Tremor
is observed as back and forth movements of a structure in a relatively regular fashion.
Descriptions of each severity level are provided below. You may view each clip as many
times as necessary to make your rating. You may go back and view previous clips as
needed.
Scale: Description
0 I don’t see any tremor.
0.5 I think I see tremor, but it’s inconsistent and hard to tell.
1 I see tremor movements, but it’s just barely noticeable.
1.5 I definitely see tremor movements that are small.
2 I see moderate tremor movements.
2.5 I see moderate to large tremor movements.
3 I see large to very large tremor movements.
Clip 1
Superior surface of velum 0 0.5 1 1.5 2 2.5 3
Posterior pharyngeal wall 0 0.5 1 1.5 2 2.5 3
Lateral pharyngeal walls 0 0.5 1 1.5 2 2.5 3
Clip 2
Superior surface of velum 0 0.5 1 1.5 2 2.5 3
Posterior pharyngeal wall 0 0.5 1 1.5 2 2.5 3
Lateral pharyngeal walls 0 0.5 1 1.5 2 2.5 3
Clip 3
Superior surface of velum 0 0.5 1 1.5 2 2.5 3
Posterior pharyngeal wall 0 0.5 1 1.5 2 2.5 3
Lateral pharyngeal walls 0 0.5 1 1.5 2 2.5 3
Clip 4
Superior surface of velum 0 0.5 1 1.5 2 2.5 3
Posterior pharyngeal wall 0 0.5 1 1.5 2 2.5 3
Lateral pharyngeal walls 0 0.5 1 1.5 2 2.5 3
Clip 5
Superior surface of velum 0 0.5 1 1.5 2 2.5 3
Posterior pharyngeal wall 0 0.5 1 1.5 2 2.5 3
Lateral pharyngeal walls 0 0.5 1 1.5 2 2.5 3
Clip 6
Superior surface of velum 0 0.5 1 1.5 2 2.5 3
Posterior pharyngeal wall 0 0.5 1 1.5 2 2.5 3
Lateral pharyngeal walls 0 0.5 1 1.5 2 2.5 3
122
Clip 7
Superior surface of velum 0 0.5 1 1.5 2 2.5 3
Posterior pharyngeal wall 0 0.5 1 1.5 2 2.5 3
Lateral pharyngeal walls 0 0.5 1 1.5 2 2.5 3
Clip 8
Superior surface of velum 0 0.5 1 1.5 2 2.5 3
Posterior pharyngeal wall 0 0.5 1 1.5 2 2.5 3
Lateral pharyngeal walls 0 0.5 1 1.5 2 2.5 3
Clip 9
Superior surface of velum 0 0.5 1 1.5 2 2.5 3
Posterior pharyngeal wall 0 0.5 1 1.5 2 2.5 3
Lateral pharyngeal walls 0 0.5 1 1.5 2 2.5 3
Clip 10
Superior surface of velum 0 0.5 1 1.5 2 2.5 3
Posterior pharyngeal wall 0 0.5 1 1.5 2 2.5 3
Lateral pharyngeal walls 0 0.5 1 1.5 2 2.5 3
Clip 11
Superior surface of velum 0 0.5 1 1.5 2 2.5 3
Posterior pharyngeal wall 0 0.5 1 1.5 2 2.5 3
Lateral pharyngeal walls 0 0.5 1 1.5 2 2.5 3
Clip 12
Superior surface of velum 0 0.5 1 1.5 2 2.5 3
Posterior pharyngeal wall 0 0.5 1 1.5 2 2.5 3
Lateral pharyngeal walls 0 0.5 1 1.5 2 2.5 3
Clip 13
Superior surface of velum 0 0.5 1 1.5 2 2.5 3
Posterior pharyngeal wall 0 0.5 1 1.5 2 2.5 3
Lateral pharyngeal walls 0 0.5 1 1.5 2 2.5 3
Clip 14
Superior surface of velum 0 0.5 1 1.5 2 2.5 3
Posterior pharyngeal wall 0 0.5 1 1.5 2 2.5 3
Lateral pharyngeal walls 0 0.5 1 1.5 2 2.5 3
Clip 15
Superior surface of velum 0 0.5 1 1.5 2 2.5 3
Posterior pharyngeal wall 0 0.5 1 1.5 2 2.5 3
Lateral pharyngeal walls 0 0.5 1 1.5 2 2.5 3
Clip 16
Superior surface of velum 0 0.5 1 1.5 2 2.5 3
Posterior pharyngeal wall 0 0.5 1 1.5 2 2.5 3
Lateral pharyngeal walls 0 0.5 1 1.5 2 2.5 3
Clip 17
Superior surface of velum 0 0.5 1 1.5 2 2.5 3
Posterior pharyngeal wall 0 0.5 1 1.5 2 2.5 3
Lateral pharyngeal walls 0 0.5 1 1.5 2 2.5 3
123
Clip 18
Superior surface of velum 0 0.5 1 1.5 2 2.5 3
Posterior pharyngeal wall 0 0.5 1 1.5 2 2.5 3
Lateral pharyngeal walls 0 0.5 1 1.5 2 2.5 3
Clip 19
Superior surface of velum 0 0.5 1 1.5 2 2.5 3
Posterior pharyngeal wall 0 0.5 1 1.5 2 2.5 3
Lateral pharyngeal walls 0 0.5 1 1.5 2 2.5 3
Clip 20
Superior surface of velum 0 0.5 1 1.5 2 2.5 3
Posterior pharyngeal wall 0 0.5 1 1.5 2 2.5 3
Lateral pharyngeal walls 0 0.5 1 1.5 2 2.5 3
Clip 21
Superior surface of velum 0 0.5 1 1.5 2 2.5 3
Posterior pharyngeal wall 0 0.5 1 1.5 2 2.5 3
Lateral pharyngeal walls 0 0.5 1 1.5 2 2.5 3
Clip 22
Superior surface of velum 0 0.5 1 1.5 2 2.5 3
Posterior pharyngeal wall 0 0.5 1 1.5 2 2.5 3
Lateral pharyngeal walls 0 0.5 1 1.5 2 2.5 3
Clip 23
Superior surface of velum 0 0.5 1 1.5 2 2.5 3
Posterior pharyngeal wall 0 0.5 1 1.5 2 2.5 3
Lateral pharyngeal walls 0 0.5 1 1.5 2 2.5 3
Clip 24
Superior surface of velum 0 0.5 1 1.5 2 2.5 3
Posterior pharyngeal wall 0 0.5 1 1.5 2 2.5 3
Lateral pharyngeal walls 0 0.5 1 1.5 2 2.5 3
Clip 25
Superior surface of velum 0 0.5 1 1.5 2 2.5 3
Posterior pharyngeal wall 0 0.5 1 1.5 2 2.5 3
Lateral pharyngeal walls 0 0.5 1 1.5 2 2.5 3
Clip 26
Superior surface of velum 0 0.5 1 1.5 2 2.5 3
Posterior pharyngeal wall 0 0.5 1 1.5 2 2.5 3
Lateral pharyngeal walls 0 0.5 1 1.5 2 2.5 3
Clip 27
Superior surface of velum 0 0.5 1 1.5 2 2.5 3
Posterior pharyngeal wall 0 0.5 1 1.5 2 2.5 3
Lateral pharyngeal walls 0 0.5 1 1.5 2 2.5 3
Clip 28
Superior surface of velum 0 0.5 1 1.5 2 2.5 3
Posterior pharyngeal wall 0 0.5 1 1.5 2 2.5 3
Lateral pharyngeal walls 0 0.5 1 1.5 2 2.5 3
124
Clip 29
Superior surface of velum 0 0.5 1 1.5 2 2.5 3
Posterior pharyngeal wall 0 0.5 1 1.5 2 2.5 3
Lateral pharyngeal walls 0 0.5 1 1.5 2 2.5 3
Clip 30
Superior surface of velum 0 0.5 1 1.5 2 2.5 3
Posterior pharyngeal wall 0 0.5 1 1.5 2 2.5 3
Lateral pharyngeal walls 0 0.5 1 1.5 2 2.5 3
Clip 31
Superior surface of velum 0 0.5 1 1.5 2 2.5 3
Posterior pharyngeal wall 0 0.5 1 1.5 2 2.5 3
Lateral pharyngeal walls 0 0.5 1 1.5 2 2.5 3
Clip 32
Superior surface of velum 0 0.5 1 1.5 2 2.5 3
Posterior pharyngeal wall 0 0.5 1 1.5 2 2.5 3
Lateral pharyngeal walls 0 0.5 1 1.5 2 2.5 3
Clip 33
Superior surface of velum 0 0.5 1 1.5 2 2.5 3
Posterior pharyngeal wall 0 0.5 1 1.5 2 2.5 3
Lateral pharyngeal walls 0 0.5 1 1.5 2 2.5 3
Clip 34
Superior surface of velum 0 0.5 1 1.5 2 2.5 3
Posterior pharyngeal wall 0 0.5 1 1.5 2 2.5 3
Lateral pharyngeal walls 0 0.5 1 1.5 2 2.5 3
Clip 35
Superior surface of velum 0 0.5 1 1.5 2 2.5 3
Posterior pharyngeal wall 0 0.5 1 1.5 2 2.5 3
Lateral pharyngeal walls 0 0.5 1 1.5 2 2.5 3
Clip 36
Superior surface of velum 0 0.5 1 1.5 2 2.5 3
Posterior pharyngeal wall 0 0.5 1 1.5 2 2.5 3
Lateral pharyngeal walls 0 0.5 1 1.5 2 2.5 3
Clip 37
Superior surface of velum 0 0.5 1 1.5 2 2.5 3
Posterior pharyngeal wall 0 0.5 1 1.5 2 2.5 3
Lateral pharyngeal walls 0 0.5 1 1.5 2 2.5 3
Clip 38
Superior surface of velum 0 0.5 1 1.5 2 2.5 3
Posterior pharyngeal wall 0 0.5 1 1.5 2 2.5 3
Lateral pharyngeal walls 0 0.5 1 1.5 2 2.5 3
Clip 39
Superior surface of velum 0 0.5 1 1.5 2 2.5 3
Posterior pharyngeal wall 0 0.5 1 1.5 2 2.5 3
Lateral pharyngeal walls 0 0.5 1 1.5 2 2.5 3
125
Clip 40
Superior surface of velum 0 0.5 1 1.5 2 2.5 3
Posterior pharyngeal wall 0 0.5 1 1.5 2 2.5 3
Lateral pharyngeal walls 0 0.5 1 1.5 2 2.5 3
Clip 41
Superior surface of velum 0 0.5 1 1.5 2 2.5 3
Posterior pharyngeal wall 0 0.5 1 1.5 2 2.5 3
Lateral pharyngeal walls 0 0.5 1 1.5 2 2.5 3
Clip 42
Superior surface of velum 0 0.5 1 1.5 2 2.5 3
Posterior pharyngeal wall 0 0.5 1 1.5 2 2.5 3
Lateral pharyngeal walls 0 0.5 1 1.5 2 2.5 3
Clip 43
Superior surface of velum 0 0.5 1 1.5 2 2.5 3
Posterior pharyngeal wall 0 0.5 1 1.5 2 2.5 3
Lateral pharyngeal walls 0 0.5 1 1.5 2 2.5 3
Clip 44
Superior surface of velum 0 0.5 1 1.5 2 2.5 3
Posterior pharyngeal wall 0 0.5 1 1.5 2 2.5 3
Lateral pharyngeal walls 0 0.5 1 1.5 2 2.5 3
Clip 45
Superior surface of velum 0 0.5 1 1.5 2 2.5 3
Posterior pharyngeal wall 0 0.5 1 1.5 2 2.5 3
Lateral pharyngeal walls 0 0.5 1 1.5 2 2.5 3
Clip 46
Superior surface of velum 0 0.5 1 1.5 2 2.5 3
Posterior pharyngeal wall 0 0.5 1 1.5 2 2.5 3
Lateral pharyngeal walls 0 0.5 1 1.5 2 2.5 3
Clip 47
Superior surface of velum 0 0.5 1 1.5 2 2.5 3
Posterior pharyngeal wall 0 0.5 1 1.5 2 2.5 3
Lateral pharyngeal walls 0 0.5 1 1.5 2 2.5 3
Clip 48
Superior surface of velum 0 0.5 1 1.5 2 2.5 3
Posterior pharyngeal wall 0 0.5 1 1.5 2 2.5 3
Lateral pharyngeal walls 0 0.5 1 1.5 2 2.5 3
Clip 49
Superior surface of velum 0 0.5 1 1.5 2 2.5 3
Posterior pharyngeal wall 0 0.5 1 1.5 2 2.5 3
Lateral pharyngeal walls 0 0.5 1 1.5 2 2.5 3
126
APPENDIX E
VIDEO CLIP RATING FORM - LARYNGEAL VIEW Evaluator:____________________________
View each clip and rate the severity of the tremor using the scale provided. Please rate
only the tremor severity, ignoring redness, swelling, or any other characteristics. Tremor
is observed as back and forth movements of a structure in a relatively regular fashion.
Descriptions of each severity level are provided below. You may view each clip as many
times as necessary to make your rating. You may go back and view previous clips as
needed.
Scale: Description
0 I don’t see any tremor.
0.5 I think I see tremor, but it’s inconsistent and hard to tell.
1 I see tremor movements, but it’s just barely noticeable.
1.5 I definitely see tremor movements that are small.
2 I see moderate tremor movements.
2.5 I see moderate to large tremor movements.
3 I see large to very large tremor movements.
Clip 1
True vocal folds 0 0.5 1 1.5 2 2.5 3
Supraglottic structures 0 0.5 1 1.5 2 2.5 3
Pharyngeal walls 0 0.5 1 1.5 2 2.5 3
Base of tongue 0 0.5 1 1.5 2 2.5 3
Clip 2
True vocal folds 0 0.5 1 1.5 2 2.5 3
Supraglottic structures 0 0.5 1 1.5 2 2.5 3
Pharyngeal walls 0 0.5 1 1.5 2 2.5 3
Base of tongue 0 0.5 1 1.5 2 2.5 3
Clip 3
True vocal folds 0 0.5 1 1.5 2 2.5 3
Supraglottic structures 0 0.5 1 1.5 2 2.5 3
Pharyngeal walls 0 0.5 1 1.5 2 2.5 3
Base of tongue 0 0.5 1 1.5 2 2.5 3
Clip 4
True vocal folds 0 0.5 1 1.5 2 2.5 3
Supraglottic structures 0 0.5 1 1.5 2 2.5 3
Pharyngeal walls 0 0.5 1 1.5 2 2.5 3
Base of tongue 0 0.5 1 1.5 2 2.5 3
127
Clip 5
True vocal folds 0 0.5 1 1.5 2 2.5 3
Supraglottic structures 0 0.5 1 1.5 2 2.5 3
Pharyngeal walls 0 0.5 1 1.5 2 2.5 3
Base of tongue 0 0.5 1 1.5 2 2.5 3
Clip 6
True vocal folds 0 0.5 1 1.5 2 2.5 3
Supraglottic structures 0 0.5 1 1.5 2 2.5 3
Pharyngeal walls 0 0.5 1 1.5 2 2.5 3
Base of tongue 0 0.5 1 1.5 2 2.5 3
Clip 7
True vocal folds 0 0.5 1 1.5 2 2.5 3
Supraglottic structures 0 0.5 1 1.5 2 2.5 3
Pharyngeal walls 0 0.5 1 1.5 2 2.5 3
Base of tongue 0 0.5 1 1.5 2 2.5 3
Clip 8
True vocal folds 0 0.5 1 1.5 2 2.5 3
Supraglottic structures 0 0.5 1 1.5 2 2.5 3
Pharyngeal walls 0 0.5 1 1.5 2 2.5 3
Base of tongue 0 0.5 1 1.5 2 2.5 3
Clip 9
True vocal folds 0 0.5 1 1.5 2 2.5 3
Supraglottic structures 0 0.5 1 1.5 2 2.5 3
Pharyngeal walls 0 0.5 1 1.5 2 2.5 3
Base of tongue 0 0.5 1 1.5 2 2.5 3
Clip 10
True vocal folds 0 0.5 1 1.5 2 2.5 3
Supraglottic structures 0 0.5 1 1.5 2 2.5 3
Pharyngeal walls 0 0.5 1 1.5 2 2.5 3
Base of tongue 0 0.5 1 1.5 2 2.5 3
Clip 11
True vocal folds 0 0.5 1 1.5 2 2.5 3
Supraglottic structures 0 0.5 1 1.5 2 2.5 3
Pharyngeal walls 0 0.5 1 1.5 2 2.5 3
Base of tongue 0 0.5 1 1.5 2 2.5 3
Clip 12
True vocal folds 0 0.5 1 1.5 2 2.5 3
Supraglottic structures 0 0.5 1 1.5 2 2.5 3
Pharyngeal walls 0 0.5 1 1.5 2 2.5 3
Base of tongue 0 0.5 1 1.5 2 2.5 3
Clip 13
True vocal folds 0 0.5 1 1.5 2 2.5 3
Supraglottic structures 0 0.5 1 1.5 2 2.5 3
Pharyngeal walls 0 0.5 1 1.5 2 2.5 3
Base of tongue 0 0.5 1 1.5 2 2.5 3
128
Clip 14
True vocal folds 0 0.5 1 1.5 2 2.5 3
Supraglottic structures 0 0.5 1 1.5 2 2.5 3
Pharyngeal walls 0 0.5 1 1.5 2 2.5 3
Base of tongue 0 0.5 1 1.5 2 2.5 3
Clip 15
True vocal folds 0 0.5 1 1.5 2 2.5 3
Supraglottic structures 0 0.5 1 1.5 2 2.5 3
Pharyngeal walls 0 0.5 1 1.5 2 2.5 3
Base of tongue 0 0.5 1 1.5 2 2.5 3
Clip 16
True vocal folds 0 0.5 1 1.5 2 2.5 3
Supraglottic structures 0 0.5 1 1.5 2 2.5 3
Pharyngeal walls 0 0.5 1 1.5 2 2.5 3
Base of tongue 0 0.5 1 1.5 2 2.5 3
Clip 17
True vocal folds 0 0.5 1 1.5 2 2.5 3
Supraglottic structures 0 0.5 1 1.5 2 2.5 3
Pharyngeal walls 0 0.5 1 1.5 2 2.5 3
Base of tongue 0 0.5 1 1.5 2 2.5 3
Clip 18
True vocal folds 0 0.5 1 1.5 2 2.5 3
Supraglottic structures 0 0.5 1 1.5 2 2.5 3
Pharyngeal walls 0 0.5 1 1.5 2 2.5 3
Base of tongue 0 0.5 1 1.5 2 2.5 3
Clip 19
True vocal folds 0 0.5 1 1.5 2 2.5 3
Supraglottic structures 0 0.5 1 1.5 2 2.5 3
Pharyngeal walls 0 0.5 1 1.5 2 2.5 3
Base of tongue 0 0.5 1 1.5 2 2.5 3
Clip 20
True vocal folds 0 0.5 1 1.5 2 2.5 3
Supraglottic structures 0 0.5 1 1.5 2 2.5 3
Pharyngeal walls 0 0.5 1 1.5 2 2.5 3
Base of tongue 0 0.5 1 1.5 2 2.5 3
Clip 21
True vocal folds 0 0.5 1 1.5 2 2.5 3
Supraglottic structures 0 0.5 1 1.5 2 2.5 3
Pharyngeal walls 0 0.5 1 1.5 2 2.5 3
Base of tongue 0 0.5 1 1.5 2 2.5 3
Clip 22
True vocal folds 0 0.5 1 1.5 2 2.5 3
Supraglottic structures 0 0.5 1 1.5 2 2.5 3
Pharyngeal walls 0 0.5 1 1.5 2 2.5 3
Base of tongue 0 0.5 1 1.5 2 2.5 3
129
Clip 23
True vocal folds 0 0.5 1 1.5 2 2.5 3
Supraglottic structures 0 0.5 1 1.5 2 2.5 3
Pharyngeal walls 0 0.5 1 1.5 2 2.5 3
Base of tongue 0 0.5 1 1.5 2 2.5 3
Clip 24
True vocal folds 0 0.5 1 1.5 2 2.5 3
Supraglottic structures 0 0.5 1 1.5 2 2.5 3
Pharyngeal walls 0 0.5 1 1.5 2 2.5 3
Base of tongue 0 0.5 1 1.5 2 2.5 3
Clip 25
True vocal folds 0 0.5 1 1.5 2 2.5 3
Supraglottic structures 0 0.5 1 1.5 2 2.5 3
Pharyngeal walls 0 0.5 1 1.5 2 2.5 3
Base of tongue 0 0.5 1 1.5 2 2.5 3
Clip 26
True vocal folds 0 0.5 1 1.5 2 2.5 3
Supraglottic structures 0 0.5 1 1.5 2 2.5 3
Pharyngeal walls 0 0.5 1 1.5 2 2.5 3
Base of tongue 0 0.5 1 1.5 2 2.5 3
Clip 27
True vocal folds 0 0.5 1 1.5 2 2.5 3
Supraglottic structures 0 0.5 1 1.5 2 2.5 3
Pharyngeal walls 0 0.5 1 1.5 2 2.5 3
Base of tongue 0 0.5 1 1.5 2 2.5 3
Clip 28
True vocal folds 0 0.5 1 1.5 2 2.5 3
Supraglottic structures 0 0.5 1 1.5 2 2.5 3
Pharyngeal walls 0 0.5 1 1.5 2 2.5 3
Base of tongue 0 0.5 1 1.5 2 2.5 3
Clip 29
True vocal folds 0 0.5 1 1.5 2 2.5 3
Supraglottic structures 0 0.5 1 1.5 2 2.5 3
Pharyngeal walls 0 0.5 1 1.5 2 2.5 3
Base of tongue 0 0.5 1 1.5 2 2.5 3
Clip 30
True vocal folds 0 0.5 1 1.5 2 2.5 3
Supraglottic structures 0 0.5 1 1.5 2 2.5 3
Pharyngeal walls 0 0.5 1 1.5 2 2.5 3
Base of tongue 0 0.5 1 1.5 2 2.5 3
Clip 31
True vocal folds 0 0.5 1 1.5 2 2.5 3
Supraglottic structures 0 0.5 1 1.5 2 2.5 3
Pharyngeal walls 0 0.5 1 1.5 2 2.5 3
Base of tongue 0 0.5 1 1.5 2 2.5 3
130
Clip 32
True vocal folds 0 0.5 1 1.5 2 2.5 3
Supraglottic structures 0 0.5 1 1.5 2 2.5 3
Pharyngeal walls 0 0.5 1 1.5 2 2.5 3
Base of tongue 0 0.5 1 1.5 2 2.5 3
Clip 33
True vocal folds 0 0.5 1 1.5 2 2.5 3
Supraglottic structures 0 0.5 1 1.5 2 2.5 3
Pharyngeal walls 0 0.5 1 1.5 2 2.5 3
Base of tongue 0 0.5 1 1.5 2 2.5 3
Clip 34
True vocal folds 0 0.5 1 1.5 2 2.5 3
Supraglottic structures 0 0.5 1 1.5 2 2.5 3
Pharyngeal walls 0 0.5 1 1.5 2 2.5 3
Base of tongue 0 0.5 1 1.5 2 2.5 3
Clip 35
True vocal folds 0 0.5 1 1.5 2 2.5 3
Supraglottic structures 0 0.5 1 1.5 2 2.5 3
Pharyngeal walls 0 0.5 1 1.5 2 2.5 3
Base of tongue 0 0.5 1 1.5 2 2.5 3
Clip 36
True vocal folds 0 0.5 1 1.5 2 2.5 3
Supraglottic structures 0 0.5 1 1.5 2 2.5 3
Pharyngeal walls 0 0.5 1 1.5 2 2.5 3
Base of tongue 0 0.5 1 1.5 2 2.5 3
Clip 37
True vocal folds 0 0.5 1 1.5 2 2.5 3
Supraglottic structures 0 0.5 1 1.5 2 2.5 3
Pharyngeal walls 0 0.5 1 1.5 2 2.5 3
Base of tongue 0 0.5 1 1.5 2 2.5 3
Clip 38
True vocal folds 0 0.5 1 1.5 2 2.5 3
Supraglottic structures 0 0.5 1 1.5 2 2.5 3
Pharyngeal walls 0 0.5 1 1.5 2 2.5 3
Base of tongue 0 0.5 1 1.5 2 2.5 3
Clip 39
True vocal folds 0 0.5 1 1.5 2 2.5 3
Supraglottic structures 0 0.5 1 1.5 2 2.5 3
Pharyngeal walls 0 0.5 1 1.5 2 2.5 3
Base of tongue 0 0.5 1 1.5 2 2.5 3
Clip 40
True vocal folds 0 0.5 1 1.5 2 2.5 3
Supraglottic structures 0 0.5 1 1.5 2 2.5 3
Pharyngeal walls 0 0.5 1 1.5 2 2.5 3
Base of tongue 0 0.5 1 1.5 2 2.5 3
131
Clip 41
True vocal folds 0 0.5 1 1.5 2 2.5 3
Supraglottic structures 0 0.5 1 1.5 2 2.5 3
Pharyngeal walls 0 0.5 1 1.5 2 2.5 3
Base of tongue 0 0.5 1 1.5 2 2.5 3
Clip 42
True vocal folds 0 0.5 1 1.5 2 2.5 3
Supraglottic structures 0 0.5 1 1.5 2 2.5 3
Pharyngeal walls 0 0.5 1 1.5 2 2.5 3
Base of tongue 0 0.5 1 1.5 2 2.5 3
Clip 43
True vocal folds 0 0.5 1 1.5 2 2.5 3
Supraglottic structures 0 0.5 1 1.5 2 2.5 3
Pharyngeal walls 0 0.5 1 1.5 2 2.5 3
Base of tongue 0 0.5 1 1.5 2 2.5 3
Clip 44
True vocal folds 0 0.5 1 1.5 2 2.5 3
Supraglottic structures 0 0.5 1 1.5 2 2.5 3
Pharyngeal walls 0 0.5 1 1.5 2 2.5 3
Base of tongue 0 0.5 1 1.5 2 2.5 3
Clip 45
True vocal folds 0 0.5 1 1.5 2 2.5 3
Supraglottic structures 0 0.5 1 1.5 2 2.5 3
Pharyngeal walls 0 0.5 1 1.5 2 2.5 3
Base of tongue 0 0.5 1 1.5 2 2.5 3
Clip 46
True vocal folds 0 0.5 1 1.5 2 2.5 3
Supraglottic structures 0 0.5 1 1.5 2 2.5 3
Pharyngeal walls 0 0.5 1 1.5 2 2.5 3
Base of tongue 0 0.5 1 1.5 2 2.5 3
Clip 47
True vocal folds 0 0.5 1 1.5 2 2.5 3
Supraglottic structures 0 0.5 1 1.5 2 2.5 3
Pharyngeal walls 0 0.5 1 1.5 2 2.5 3
Base of tongue 0 0.5 1 1.5 2 2.5 3
Clip 48
True vocal folds 0 0.5 1 1.5 2 2.5 3
Supraglottic structures 0 0.5 1 1.5 2 2.5 3
Pharyngeal walls 0 0.5 1 1.5 2 2.5 3
Base of tongue 0 0.5 1 1.5 2 2.5 3
Clip 49
True vocal folds 0 0.5 1 1.5 2 2.5 3
Supraglottic structures 0 0.5 1 1.5 2 2.5 3
Pharyngeal walls 0 0.5 1 1.5 2 2.5 3
Base of tongue 0 0.5 1 1.5 2 2.5 3
132
APPENDIX F
RESPITRACE DATA Sustained /i/ F50 M58
F69 F66
133
F65 F45
F72 F62
134
F77 F86
M62 F88
135
M84 F71-2
F57 F84
136
F79 F61
F80 F71
137
Sustained /s/
F50 M58
F69 F65
138
F45 F72
F79 M62
139
M84 F86
F84 F71
140
F57 F77
F66 F61
141
F80 F88
F62 F71-2
142
Sustained /h/
F50 M58
F57 F79
143
M62 F77
F84 F45
144
F72 F65
F66 F80
145
F88 F69
F61 F71-2
146
F71 F62
M84 F86
147
Rest breathing
F50 M58
F69 F66
148
F65 F45
F72 F62
149
F77 F86
M62 F88
150
M84 F71-2
F57 F84
151
F79 F61
F80 F71