stroboscopic examination of the larynx - alexorl · stroboscopic examination of the larynx •...

Stroboscopic examination Stroboscopic examination of the larynxof the larynx

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Dr. Tamer AbouDr. Tamer Abou--Elsaad, MDElsaad, MDA. Prof. Of Phoniatrics , ORL DepartmentA. Prof. Of Phoniatrics , ORL Department

Director of Medical Centre of Phoniatrics and Director of Medical Centre of Phoniatrics and Communication Disorders (MCPCD) Communication Disorders (MCPCD)

Faculty Of MedicineFaculty Of MedicineMansoura UniversityMansoura University

April, 2007, Alex.April, 2007, Alex.

Structure Of The Vocal FoldStructure Of The Vocal Fold

Normal Vibratory Cycle Of The Vocal FoldNormal Vibratory Cycle Of The Vocal FoldOne cycle of the V.F. vibration is divided One cycle of the V.F. vibration is divided into three phases:into three phases:

•• Opening phase:Opening phase: The V.F. is blown The V.F. is blown upward on the whole by the increasing upward on the whole by the increasing Psub, and the undulating wave moves on Psub, and the undulating wave moves on the m.m. from the lower part to the upper the m.m. from the lower part to the upper part. A puff of air is released as the V.Fs. part. A puff of air is released as the V.Fs. are separated.are separated.

•• Closing phase:Closing phase: After the width of the After the width of the glottis reaches a maximum, elastic recoil glottis reaches a maximum, elastic recoil and aerodynamic forces draw the V.Fs. and aerodynamic forces draw the V.Fs. toward the midline and the glottis begins toward the midline and the glottis begins to be closed by the protruding lower lip.to be closed by the protruding lower lip.

•• Closed phase:Closed phase: The upper lip moves The upper lip moves inward and the closure of the glottis inward and the closure of the glottis becomes firm. The folds remain becomes firm. The folds remain approximated for a brief portion of the approximated for a brief portion of the cycle. Psub builds up again and the next cycle. Psub builds up again and the next cycle begins.cycle begins.

PrePre--requisites of normal voice productionrequisites of normal voice production

1 ) Normal range of movement of the vocal folds.1 ) Normal range of movement of the vocal folds.

2 ) Normal mobility of mucosa on deep layers.2 ) Normal mobility of mucosa on deep layers.

3 ) Optimal coaptation of vocal folds3 ) Optimal coaptation of vocal folds’’ edges.edges.

4 ) Optimal motor force at glottic closure.4 ) Optimal motor force at glottic closure.

5 ) Optimal pulmonary support.5 ) Optimal pulmonary support.

6 ) Optimal timing of the glottic closure in relation 6 ) Optimal timing of the glottic closure in relation to the onset of the phonatory expiration.to the onset of the phonatory expiration.

7 ) Optimal muscular tuning of vocal fold tension 7 ) Optimal muscular tuning of vocal fold tension (int. & ext.). (int. & ext.). (Kotby, 1986)

Diagnosis of Voice DisordersDiagnosis of Voice DisordersI - Elementary Diagnostic Procedures :( A ) Patient’s interview .( B ) Auditory Perceptual Assessment (APA).( C ) Visual impression of the voice source: (Laryngeal examination)

1 . External laryngeal examination .2 . Elementary visual impression (indirect laryngoscopy).

II - Clinical Diagnostic Aids :( A ) Augmentation and documentation of the glottic picture:

Video recording (video laryngo-stroboscopy):( B ) Voice recording.

III - Additional Instrumental Measures :( A ) Aerodynamic Measures .( B ) Acoustic analysis .( C ) Voice Range Profile ( Phonetogram ) .( D ) Radiological studies .( E ) Electroglottography ( EGG ) .( F ) Electromyography ( EMG ) .

(Kotby, 1995)

Stroboscopic examination Stroboscopic examination of the larynxof the larynx

Stroboscopic examination of the larynxStroboscopic examination of the larynx

•• TalbotTalbot’’s law states that once an image is presented to the eye, it s law states that once an image is presented to the eye, it persists on the retina for 0.2 sec. (1/5 cycle/sec.).persists on the retina for 0.2 sec. (1/5 cycle/sec.).

•• A rabidly rotating or vibrating object can not be seen if the spA rabidly rotating or vibrating object can not be seen if the speed eed of repetition of movements exceeds 5 per sec.of repetition of movements exceeds 5 per sec.

•• Since the V.Fs. are very rapidly rotating ( 100Since the V.Fs. are very rapidly rotating ( 100--300 Hz), the eyes 300 Hz), the eyes fuses the image of successive cyclesfuses the image of successive cycles . . So that the V.Fs. seen So that the V.Fs. seen during phonation in continuous light of an ordinary lamp ( 50 during phonation in continuous light of an ordinary lamp ( 50 cycles/sec) seem to be standstill and blurred. cycles/sec) seem to be standstill and blurred.

•• If the flashes of light are triggered after the onset of the vibIf the flashes of light are triggered after the onset of the vibratory ratory cycle by a fixed time interval, the adjacent phases of several cycle by a fixed time interval, the adjacent phases of several vibratory cycles will be illuminated successively. vibratory cycles will be illuminated successively.

• Rationale of stroboscopic light:


•• The perceived stroboscopic motion The perceived stroboscopic motion of the vocal fold is an optical of the vocal fold is an optical illusion created by fusing multiple illusion created by fusing multiple points of several successive points of several successive vibratory cycles. vibratory cycles. This motion is This motion is referred to as the glottic wave.referred to as the glottic wave.

• Rationale of stroboscopic light: (cont.)

•• If the flashes of light If the flashes of light are exactly equal to are exactly equal to and in phase with the and in phase with the vocal fold vibratory vocal fold vibratory cycles the folds will cycles the folds will appear motionless.appear motionless.

Stroboscopic examination of the larynxStroboscopic examination of the larynx• Rationale of stroboscopic light: (cont.)


•• Amplitude Of Vibration. Amplitude Of Vibration.

•• Mucosal Wave.Mucosal Wave.

•• Symmetry.Symmetry.

•• Periodicity.Periodicity.

•• Glottic Closure Patterns:Glottic Closure Patterns:

-- Phase of glottic closure.Phase of glottic closure.

-- Configuration of glottic closure. Configuration of glottic closure.

•• NonNon--Vibrating Portions.Vibrating Portions.

•• Ventricular vibrations.Ventricular vibrations.

STROBOSCOPICSTROBOSCOPIC FEATURES:FEATURES:

(Bless et al., 1987)


�� Definition:Definition:Is the extent of movement of the Is the extent of movement of the muscular body of the vocal fold muscular body of the vocal fold in the horizontal plane.in the horizontal plane.

�� In normal habitual phonatory In normal habitual phonatory conditionsconditions the extent of the the extent of the horizontal excursion of the VF horizontal excursion of the VF approximates one half the width approximates one half the width of the visible part of the VF.of the visible part of the VF.

�� Normally the amplitude of Normally the amplitude of vibration:vibration:---- Decreases with raising the Decreases with raising the pitch of phonation. pitch of phonation. -- Increases with increasing the Increases with increasing the loudness of phonation.loudness of phonation.

(1) Amplitude of Vibration:(1) Amplitude of Vibration:


The four point rating The four point rating scale for the amplitude scale for the amplitude of vibration:of vibration:

•• 0 =0 = No observable No observable horizontal excursions. horizontal excursions.

•• 1 =1 = Diminished Diminished amplitude of Vibration.amplitude of Vibration.

•• 2 =2 = Normal amplitude Normal amplitude of Vibration.of Vibration.

•• 3 =3 = Greater amplitude of Greater amplitude of Vibration.Vibration.

(1) Amplitude of Vibration(1) Amplitude of Vibration: (cont.): (cont.)


�� The amplitude of vibration The amplitude of vibration is affected byis affected by VF stiffness VF stiffness and subglottal pressure.and subglottal pressure.

�� Pathological conditions Pathological conditions leading to decreased leading to decreased amplitude of vibration:amplitude of vibration:

-- Increased VF stiffness e.g. Increased VF stiffness e.g. Sulcus VocalisSulcus Vocalis

-- Tight glottic closure Tight glottic closure patterns e.g. patterns e.g. hyperfunctional dysphonia.hyperfunctional dysphonia.

(1) Amplitude of Vibration: (1) Amplitude of Vibration: (cont.)(cont.)


•• Pathological conditions Pathological conditions leading to increased leading to increased amplitude of vibration:amplitude of vibration:

-- Increased Psub e.g. Increased Psub e.g. Reinke's oedema (where Reinke's oedema (where patient needs larger patient needs larger Psub to put the bulky Psub to put the bulky yet pliable VF into yet pliable VF into vibration). vibration).

-- Decreased Laryngeal Decreased Laryngeal muscle tone e.g. VF muscle tone e.g. VF paresis (where VFs paresis (where VFs display large excursions display large excursions as a flag fluttering in the as a flag fluttering in the wind).wind).

(1) Amplitude of Vibration: (1) Amplitude of Vibration: (cont.)(cont.)


•• Definition:Definition:Is the wave motion of the mucosal Is the wave motion of the mucosal cover traveling along both the cover traveling along both the vertical and horizontal planes of the vertical and horizontal planes of the vocal fold. vocal fold.

•• In normal habitual phonatoryIn normal habitual phonatoryconditions the mucosal wave travels conditions the mucosal wave travels across the vertical plane of the vocal across the vertical plane of the vocal fold then rolls laterally across at fold then rolls laterally across at least 50% of the width of visible part least 50% of the width of visible part of the vocal fold.of the vocal fold.

•• It is affected byIt is affected by the pliability of the the pliability of the covering mucosa and the presence covering mucosa and the presence of the natural difference in the of the natural difference in the mechanical properties between the mechanical properties between the pliable mucosal cover and stiffer pliable mucosal cover and stiffer muscular core.muscular core.

22-- Mucosal Wave:Mucosal Wave:


•• Normally the mucosal wave: Normally the mucosal wave: -- Decreases with raising the Decreases with raising the pitch of phonation. pitch of phonation. -- Increases with increasing Increases with increasing the loudness of phonation.the loudness of phonation.

•• The four point rating scale The four point rating scale for the mucosal wave:for the mucosal wave:0 =0 = No observable traveling No observable traveling wave wave 1 =1 = Restricted mucosal wave Restricted mucosal wave 2 =2 = Normal mucosal wave Normal mucosal wave 3 =3 = Greater mucosal wave in Greater mucosal wave in which the traveling wave which the traveling wave moves from the glottal moves from the glottal margin to the most lateral margin to the most lateral portion of the vocal fold.portion of the vocal fold.

22-- Mucosal WaveMucosal Wave: (cont.): (cont.)


•• Pathological conditions leading to Pathological conditions leading to decreased mucosal waves:decreased mucosal waves:

* Increased stiffness of the VF due to:* Increased stiffness of the VF due to:(a) Structural changes in the mucosa (a) Structural changes in the mucosa

(cover) e.g. (cover) e.g. -- Polypoid degeneration. Polypoid degeneration. -- Sulcus vocalis.Sulcus vocalis.-- V.F. dysplasia.V.F. dysplasia.(b) Increased muscle tension (body) (b) Increased muscle tension (body)

leading to tight glottic closure leading to tight glottic closure patterns e.g. hyperfunctional patterns e.g. hyperfunctional dysphonia (long closed phase).dysphonia (long closed phase).

* Decreased muscle tension (body) * Decreased muscle tension (body) leading to weak glottic closure leading to weak glottic closure patterns e.g. hypofunctional patterns e.g. hypofunctional dysphonia (long open phase and dysphonia (long open phase and short closed phase).short closed phase).


•• Pathological conditions leading to Pathological conditions leading to loss of mucosal wavesloss of mucosal waves (stroboscopic (stroboscopic fixation) as in:fixation) as in:

-- Any infiltrative process that fixes the Any infiltrative process that fixes the mobile mucosa to the deeper structure mobile mucosa to the deeper structure e.g. malignant neoplasm of the V. Fs.e.g. malignant neoplasm of the V. Fs.

-- Vocal fold scaring.Vocal fold scaring.-- Rec. Lx. nerve paralysis lesions (where Rec. Lx. nerve paralysis lesions (where

vocalis muscle loses its natural tone vocalis muscle loses its natural tone and the VF body becomes as flaccid and the VF body becomes as flaccid as the covering mucosa) as the covering mucosa)

Stroboscopic examination of the larynxStroboscopic examination of the larynx22-- Mucosal WaveMucosal Wave: (cont.): (cont.)


•• Pathological conditions Pathological conditions leading to increased leading to increased mucosal wave are mucosal wave are usually associated usually associated with:with:

-- increased Psub as in increased Psub as in Reinke's oedemaReinke's oedema..



•• Definition:Definition:Is the degree to which the V.Fs Is the degree to which the V.Fs provide mirror images to one provide mirror images to one another during vibration both another during vibration both in in Timing (phase)Timing (phase) and in the and in the Extent of the horizontal Extent of the horizontal excursion (amplitude)excursion (amplitude)..

•• In all normal phonatory In all normal phonatory conditionsconditions whether habitual or whether habitual or extremes of pitch or loudness: extremes of pitch or loudness: -- The timing of both V.Fs The timing of both V.Fs opening and closing patterns is opening and closing patterns is equal.equal.-- The extent of the horizontal The extent of the horizontal excursion of both V.Fs is excursion of both V.Fs is equal.equal.

33-- Symmetry:Symmetry:


•• Graph AGraph A displays displays the normal the normal amplitude and timing patternsamplitude and timing patterns of of both VFs. The upper graph both VFs. The upper graph represents the RVF movement represents the RVF movement during the opening, closing and during the opening, closing and closed phase of the glottal cycle. closed phase of the glottal cycle. The lower graph represents the The lower graph represents the LVF movement during the LVF movement during the opening, closing and closed opening, closing and closed phases of the same glottic cycle.phases of the same glottic cycle.

•• Graph BGraph B displays displays asymmetry in asymmetry in amplitudeamplitude where the range of the where the range of the LVF excursion is less than that of LVF excursion is less than that of the RVF.the RVF.

•• Graph CGraph C displays displays asymmetry in asymmetry in phasephase where the RVF is closing where the RVF is closing while the LVF is opening. while the LVF is opening.

•• Graph DGraph D displays displays asymmetry both asymmetry both in phase and amplitude.in phase and amplitude.

33-- Symmetry: (cont.)Symmetry: (cont.)


•• Asymmetry in phase or Asymmetry in phase or amplitude between both amplitude between both V.Fs. is caused by V.Fs. is caused by induced differences in the induced differences in the mechanical properties mechanical properties between both VFs as in:between both VFs as in:-- Laryngeal lesions Laryngeal lesions affecting mass, tension or affecting mass, tension or shape of VF.shape of VF.-- Neurological lesions Neurological lesions affecting neuromuscular affecting neuromuscular control of VF.control of VF.-- Functional conditions Functional conditions affecting laryngeal affecting laryngeal muscle tension.muscle tension.

33-- Symmetry: (cont.)Symmetry: (cont.)

Asymmetry in phaseAsymmetry in phase

Asymmetry in amplitudeAsymmetry in amplitude


•• Definition:Definition:Is the degree of regularity of Is the degree of regularity of

successive apparent glottal cycles successive apparent glottal cycles during vibration. during vibration. Aperiodicity between successive Aperiodicity between successive glottal cycles can be either in glottal cycles can be either in amplitude or in timing or in both. amplitude or in timing or in both.

•• In order to evaluate this parameter In order to evaluate this parameter we shift to the we shift to the "in phase""in phase" modum of modum of the stroboscope unit where the light the stroboscope unit where the light flashes are executed at the same flashes are executed at the same frequency of the VF vibrations.frequency of the VF vibrations.

•• In all normal phonatory conditionsIn all normal phonatory conditionswith periodic successive glottal with periodic successive glottal cycles this will lead to repeated cycles this will lead to repeated illumination of the same phase of illumination of the same phase of the glottal cycle resulting in a clear the glottal cycle resulting in a clear static laryngeal image at that certain static laryngeal image at that certain phase of the cycle.phase of the cycle.

4. Periodicity: 4. Periodicity:

Locked (periodic) mode in fully adducted position


•• In cases with In cases with irregular successive irregular successive glottal cycles glottal cycles (Aperiodicity)(Aperiodicity) the the flashes will not flashes will not coincide with the coincide with the same phase of the same phase of the glottal cycle. This glottal cycle. This will result in a hazy will result in a hazy shivering laryngeal shivering laryngeal image. image.

4. Periodicity: 4. Periodicity:


•• Graph AGraph A displays the glottal displays the glottal waveform of waveform of normal periodic normal periodic vibrationsvibrations where successive where successive glottal cycles are uniform in glottal cycles are uniform in amplitude and timing.amplitude and timing.

•• Graph BGraph B displays displays aperiodicity aperiodicity in timingin timing between successive between successive glottal cycles.glottal cycles.

•• Graph CGraph C displays displays aperiodicity aperiodicity in amplitudein amplitude between between successive glottal cycles.successive glottal cycles.

•• Graph DGraph D displays displays total total aperiodicityaperiodicity in timing and in timing and Amplitude.Amplitude.

4. Periodicity: (cont.)4. Periodicity: (cont.)


•• Aperiodicity is caused by Aperiodicity is caused by disturbance in the balance disturbance in the balance between the mechanical between the mechanical properties of the VFs and the properties of the VFs and the applied aerodynamic forces. applied aerodynamic forces. This may be due to:This may be due to:

�� Inadequate expiatory air Inadequate expiatory air during phonation.during phonation.

�� Disrupted laryngeal muscle Disrupted laryngeal muscle tension.tension.

�� Imbalance of neuromuscular Imbalance of neuromuscular control of the larynx.control of the larynx.

�� Disturbed mechanical Disturbed mechanical properties of the VFs.properties of the VFs.

4. Periodicity: (cont.)4. Periodicity: (cont.)


•• Definition:Definition:Is the average timing of the Is the average timing of the closed phase in relation to the closed phase in relation to the whole golttic cycle.whole golttic cycle.

•• In normal habitual phonatory In normal habitual phonatory conditionsconditions the timing of the the timing of the opening phase, closing phase opening phase, closing phase and, closed phase are nearly and, closed phase are nearly identical.identical.

•• The opening phase predominatesThe opening phase predominateswith raising the pitch of with raising the pitch of phonation and with decreasing phonation and with decreasing the loudness of phonation.the loudness of phonation.

•• On the other hand , On the other hand , the closed the closed phase predominatesphase predominates with raising with raising the loudness of phonation.the loudness of phonation.

5. Glottic Closure Patterns:5. Glottic Closure Patterns:(A) Phase of glottic Closure:(A) Phase of glottic Closure:


•• Pathological conditionsPathological conditionsleading to leading to predominance of predominance of the opening phasethe opening phase during during habitual phonation are usually habitual phonation are usually associated with decreased associated with decreased laryngeal muscle tension as in laryngeal muscle tension as in hypofunctional dysphonia.hypofunctional dysphonia.

•• Pathological conditionsPathological conditionsleading to leading to predominance of predominance of the closing phasethe closing phase during during habitual phonation are usually habitual phonation are usually associated with increased associated with increased glottal resistance as in cases glottal resistance as in cases of hyperfunctional dysphonia. of hyperfunctional dysphonia.

5. Glottic Closure Patterns5. Glottic Closure Patterns:(cont.):(cont.)(A) Phase of glottic Closure:(A) Phase of glottic Closure:(cont.)(cont.)


•• Definition:Definition:

This is the shape of the This is the shape of the glottis at maximum closure glottis at maximum closure under stroboscopic light.under stroboscopic light.

•• In normal habitual phonationIn normal habitual phonationthere is complete closure there is complete closure along the vocal fold edges in along the vocal fold edges in males and closure along the males and closure along the vibrating edges with a small vibrating edges with a small triangular posterior chink in triangular posterior chink in females.females.

5. Glottic Closure Patterns5. Glottic Closure Patterns:(cont.):(cont.)(B) Configuration of glottic Closure:(B) Configuration of glottic Closure:


•• Abnormal closure patterns Abnormal closure patterns may be seen associated with may be seen associated with different pathological different pathological conditions such as :conditions such as :--

* The hour* The hour--glass shape glass shape phonatory gapphonatory gap that may be that may be seen with vocal fold nodules. seen with vocal fold nodules.

* The slit shape phonatory gap* The slit shape phonatory gapthat may be seen in in that may be seen in in patients with hyperfunctional patients with hyperfunctional dysphonia. dysphonia.

5. Glottic Closure Patterns5. Glottic Closure Patterns:(cont.):(cont.)(B) Configuration of glottic Closure:(B) Configuration of glottic Closure:

* The oval shape * The oval shape phonatory gapphonatory gapthat may be seen that may be seen in patients with in patients with hypofunctional hypofunctional dysphonia.dysphonia.

* Irregular * Irregular phonatory gapphonatory gap as as in cancer larynx.in cancer larynx.

* No closure* No closure as in as in bilateral V.Fs. bilateral V.Fs. paralysis.paralysis.

Stroboscopic examination of the larynxStroboscopic examination of the larynx5. Glottic Closure Patterns5. Glottic Closure Patterns:(cont.):(cont.)(B) Configuration of glottic Closure:(cont.)(B) Configuration of glottic Closure:(cont.)


•• Describing the site, extent Describing the site, extent and persistence of adynamic and persistence of adynamic segments of the vocal folds segments of the vocal folds during vibration.during vibration.

•• This may be due to:This may be due to:---- Laryngeal Scaring. Laryngeal Scaring. -- Dysplastic Patches.Dysplastic Patches.-- Mucosal Fixation.Mucosal Fixation.

66--NonNon--Vibrating Portions:Vibrating Portions:

77--Ventricular vibrations:Ventricular vibrations:Describing whether unilateral or bilateral and whether or not sharing in phonation.

Value of VideoValue of Video--LaryngostroboscopyLaryngostroboscopy•• Detect early stages of cancer and determine the degree of Detect early stages of cancer and determine the degree of

cancerous infiltration.cancerous infiltration.•• Differentiate functional and subtle structural abnormalities of Differentiate functional and subtle structural abnormalities of

the larynx.the larynx.•• Determine the changes not visible to the unaided eye such as:Determine the changes not visible to the unaided eye such as:

-- NonNon--vibrating segments of the vocal fold.vibrating segments of the vocal fold.-- Changes in stiffness resulting from laryngeal carcinoma, Changes in stiffness resulting from laryngeal carcinoma, papilloma, or scar tissue.papilloma, or scar tissue.

•• The onset of any improvement can be observed in patients with The onset of any improvement can be observed in patients with vocal fold paralysis earlier and with greater accuracy than withvocal fold paralysis earlier and with greater accuracy than withthe eye or ear. the eye or ear.

•• PrePre-- and postand post--treatment comparisons (restoration of the treatment comparisons (restoration of the symmetry of the vibrator).symmetry of the vibrator).

•• Does not offer a continuous registration of successive Does not offer a continuous registration of successive vibratory cycles.vibratory cycles.

•• Difficult to visualize irregular vibrations. Difficult to visualize irregular vibrations.

Disadvantages of VideoDisadvantages of Video--LaryngostroboscopyLaryngostroboscopy

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