efficacy of clinical the diagnosis of · clinical examination is an important cornponent in the...
TRANSCRIPT
EFFICACY OF CLINICAL TESTS IN THE DIAGNOSIS OF
CARPAL TUNNEL SYNDROME
Brent Edward Faught
A thesis submitted in confomity with the requirements
for the degree of Doctor of Philosophy
Graduate Department of Exercise Sciences
University of Toronto
O Copyright by Brent E. Faught ( 2 0 1 )
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Efficacy of CIinical Tests in the Diagnosis of Carpal Tunnel Syndrome Brenr Edward Faught, Doctor of Phitosophy (200f 1, D e p m e n t of Exmise Sciences. Universis- of Toronto
AB STRACT
Clinical examination is an important cornponent in the diagnosis of carpat tunnel syndrome (CTS).
The ptirnruj; objcctivc of this study was to dcterminc the efficacy of clinics! tests in the diagnosis of carpal
tunnel syndrome. A sample of 92 patients ( 173 hands) including 65 females i Tage 3 8 ~ 1 5 y ) and 27 males
( T a g e 53213 y) rckrred for examination of possible carpal tunnel syndrome formed the subject base. The
attending surgeon administered Phalen's test. the pressure provocative test. the Ten tcst and Tinel's sign.
Patients returned for an indcpendént and blinded electrodiagnostic cvaluation by the attending physiatrist. A
positive elcctrodiagnosis cornbined with a "classic" or "probable" rating from Stinat's symptorn rcporting
questionnaire was the gold standard. Overall. hond prevalence of carpal tunnel syndrome was 0.62 + 0.07 ( 108
'CTS and 65 'CTS hands). Diagnostic éfficacy was eealuated using mesures of scnsitiviij (Sens). specificity
(Spec). and likelihood ratio (LR) with conesponding 95% confidence interval (CI) as well ûs Cohen's Kappa
statistic. Tinel's sien ( {Sens=79%; CI. 7 1-87 1 {Spec=65%; CI. 55-75 }. ( LR=2.22; CI. 2.08-2.36)), the Ten
test ( (Sens=87%; CI. 79-95), (Spec=52%; CI. 44 1-63]. (LR= 1.8; CI. 1.66- 1.94) ), and Phalen's test
( ( Sens=SO%; CI. 72-88 1. ( Spcc=48%; CI. 37-59 1. {LR= 1.52; CI. 1.38- 1.66) ) demonstrated significant Kappa
agreement (p<0.001) with the confirmed diagnosis for carpal tunnel syndrome. The pressure provocative test
( (Sens=76%: CI. 68-83). (Spec=34%; CI. 23-45 1, ( LR=1.15; CI. 1 .O1 - 1.39)). did not indicate sipnificant
Kappa agreement (p>0.05). Finally. the serial combination of Tinel's sign with either the Ten test ({Sens=73%;
CI 65-8 1 1. { Spec=50%; CI. 39-61 ), ( LR=l.46; CI, 1.32-1.6)) or Phden's test ( (Sens=73%; CI. 65-8 1 ).
{ Spec=46%; CI. 34-58 ). ( LR= 1.36: CI. 1.2 1 - 1 X I ) , demonsuated signiticant Kappa agreement (pc0.0 1 ). A
secondary objective of the cunent study was to establish positivity criterion for the Ten tcst using ROC c w e
andysis. Positivity criterion for CTS was identified as subject hand sensibility values cl0 in at least three of
the thumb. index, middle and ring fineers. The Ten test proved to be a valid clinical test with a sensitivity,
specificity and likelihood ratio that rival those obtained by traditional clinical tests. includinz Tinel's sign and
Phden's test. This study concluded that Tinel's sign; Phaien's test and the Ten test are efficacious clinical tests
in the diagnosis of carpal tunnel syndrome.
This academic exercise is dedicated to my best friend Tarnmy and my pride and joy - Brock. Christian and Zachary
for the sacrifices the y have made.
ACKNOWLEDGEMENTS
1 wish to acknowledge the assistance, guidance, and expertise of many individuals that supported this
dissertation to fruition. First. much appreciation is extended to my supervisor. Dr. Nancy McKee and
committce members. Drs. Panagiota KIentrou, William McIlroy, William Montelpare and Gaylene Pron. I am
indebted to these scientists who have provided invaluable advice and teaching throughout the past 6 years. 1
look forward to collaborating and learning more from these professionals in years to corne. Furthermore. 1
wish to thank Drs. Nancy McKtx. Mark Thibert. Michael Dcvlin. Denyse Richardson and Nancy Ryan for
çollecting c l in id data ris weIl as the numerous paricnts chat graciously volunteered for this study. Certainly,
your invcstmcnt truly coninbuted to the cornpletion of this research venture. 1 wish to acknowledge the
comrnitmcnt of Nancy Montelpare and Tina Kiivcrs in the efficient management of the study sites in both
Thunder Bay and Toronto. respectivcly. Thank you very much for your enthusiasm, optimisrn and
organization throughout this diagnostic trial. Finally, 1 am gratelul to Dr. Michael Plyley and Dr. Joy
MacDermid for their cornmitment of tirne and philosophical insights during the final stage in completing this
dissertation.
This academic joumey could not have been completed without thc unselfishness of numerous caring
individuals. The accumulation of words and calculated numbers in the following pages are the composite
efforts of many extrriordinary persons chat 1 have been honoured to have been associated over the put 35 years.
Therefore, 1 wish to cxtend a sincere thank you to Clen Closs, for stopping the bus; . . . the "Croup of Seven" at
CDES. . . . Brock University. for giving me a chance; . . . Professor Robert (Bob) Davis. for inspiring me with
my inaugural university !ecture; . . . Dr. Roy J. Shephard for supervisin? me during rny doctoral residency at
the University of Toronto: . . . Dr. Alex Dagum for his clinicaI insight and allowing me to "scrub in"; . . . Dr.
John Hay and Canadian Tire Acceptance Limited for financial support of my research; . . . faculty and staff
members in the Department of Cornmunity Health Sciences at Brock University for their vote of confidence
and encouragement; . . . Dr. William J. Montelpare for aliowing me to discover what was "behind the curtain";
, , , former BU students Roger Hughes, Jennifer Soucie. David Sciberras, Rob Hriwes, Wayne De Ruiter and
Glenys Jenkyns for accepting academic challenges and exercising their inquisitivc minds; . . . Lloyd. Ron.
Lucio. Jackie, Tad. Donna. Murray and Special "K" for friendship; . . . Dad and Mom. for believing,
sacrificing. Ioving, wishing, praying ris wcll as filling out the application to university (and a 3 leaf clover); . . .
Karen. for leadership and the walk back to the Little bush; . . . Sheryl, for her laughter, intuition and
perseverance: . . . Paul, for being the consumate of a gentleman as well as choosing Brock over Western; . , . Mark, for being so briIIiant. talented and humble; . . . my three beautiful sons, Brock. Christkm and Zachary for
never ceasinp to amaze me and making daddy laugh; . . . and especially my wife and best friend. Tammy for
being more wonderful than 1 had ever imagined. Finally. a sincere thank you to Jesus Christ for always being
there. just Iike He promised (James 1: 19).
TABLE OF CONTENTS
Page
Title Page ...................................................................................................................... ........................................................................................................................ Abstract
.................................................................................................................... Dedication.
...................................................................................................... Acknowledgements
......................................................................................................... Table of Contents
List of Tables ............................................................................................................... List of Figures ..............................................................................................................
....................................................................................................... List of Appendices
Glossary of Terms ........................................................................................................ List of Abbreviations ....................................................................................................
1
i i ... 111
iv
v
ix
X
X
xi
xiv
CHAPTER 1 - INTRODUCTION
1 .1 Theme ........................................................................................................ 1
1.2 Objectives .................................................................................................. 3
1.3 Hypothesis ................................................................................................. 3
CHAPTER II - REVIEW OF LITERATURE
............................................................................................. Introduction
Diagnosis of a syndrome ........................................................................ ..................................................................... 2.2.1 Defining a syndrome
2.2.2 Diagnostic algorithm ..................................................................... 2.2.3 Challenge of a "gold standard" ..................................................... Defining carpal tunnel syndrome ............................................................ Anatomy of the carpal tunnel ..................................................................
................................................................. Etiology and pathophysiology
................................................................................................. Diagnosis
v
............................................................... 2.6.1 Electmdiagxiostic studies
.................................................................................. 2.6.2 ClinicaI tests
.................................. 2 - 6 2 1 S ymptom reporting questionnaires
2.6.2.2 Provocative tests ............................................................. ............................................................... 2.6.2.3 Sensibility tests
Combined influence of clinical tests ....................................................... ................................................................................................ Treatment
.................................. S ystematic literature review of diagnostic studies
2.9.1 Criteria for study evaluation .......................................................... 2.9.2 Blind cornparison .......................................................................... 2.9.3 Acceptable gold standard ..............................................................
............................................................................ 2.9.4 Patient spectmm
2.9.5 Diagnostic utility ........................................................................... 2.9.6 Summary of systematic literature review ......................................
2.10 Summary ................................................................................................
CHAPTER III . METHODOLOGY ............................................................................................. 3.1 Introduction
.......................................................................................... 3.2 Study ~ample
....................................................................................... 3.3 Research design
.............................................. 3.4 Stirrat's symptorn reporting questionnaire
............................................................................... 3.5 Clinical examination
................................................................................... 3.5.1 Phalen's test
............................................................... 3-52 Pressure provocative test
......................................................................................... 3.5.3 Ten test
................................................................................... 3.5.4 Tinel's sign
................................................................... 3.6 Electrodiagnostic evaluation
.................................................................................... 3 -7 Data management
3.7.1 Defining the variables ................................................................... ................................................................................... 3 J . 2 Data coding
........................................................... 3.7.3 Data checkhg and cleaning
3.8 Declaration of the gold standard ............................................................. ................................................................................. 3.9 S tatistical Analyses
3.9.1 Evaluating subject demographics and ........................................................... symptom reporting profiles
......................................................... 3.9.2 Electrodiagnostic evciluation
3.9.3 Designing and establishing positivity criterion for the Ten test ... 3.9.4 Evaluating diagnostic . . efficacy of independent and
.................................................................... cornbined clintcal tests
3.9.5 Prevalence and predictive value estimation ...................................
CHAPTER IV . RESULTS
.............. Subject response to Stimt's symptom reporting questionnaire
Description of sensory and rnotor nerve conduction studies .................. Diagnostic confirmation using the gold standard ................................... Data completion and non-responders .....................................................
............................................... Subject and hand diagnostic presentation
......................................................................................... De rnograph ics
.......................................................................... Subject mcdical profiles
Electrodiagnostic evaluation ................................................................... Establishing positivity cnterion for the Ten test models
................................................................... using ROC curve techniques
Evaluating the efficacy of the Ten test models ....................................... Cornparison between individual ciinicai tests ......................................... Distribution of clinical tests compared to the gold standard ..................
Diagnostic efficacy of clinicai tests compared to the goid standard ....... Prevalence rates and predictive value estimation ....................................
CHAPTER V . DISCUSSION
5.1 Introduction ........................................................................................... ....................................................................................... 5.2 Subject profiles
vii
.......................................................................... 5.3 Efficacy of clinical tests 80
.................................................................................... 5.3.1 Tinel's sign 81
5.3.2 Phaien's test ............................................................................... 83
............................................................... 5.3.3 Pressure provocative test 83
5.3.3 Ten test .......................................................................................... 85
5.3.5 Combined clinical tests ................................................................. 87
5.4 Limitations .............................................................................................. 89
CHAPTER VI . CONCLUSION
............................................................................................. 6.1 Conclusions 93
................................................................ 6.2 Future research considerations 93
........................................................................................................... REFERENCES 95
LIST OF TABLES
Table 2 . t Table 2.2
Table 2.3
Table 2.4
Table 2.5
Table 4.1
Table 4.2
Table 4.3
Table 4.4
Table 4.5
Table 4.6
Table 4.7
Table 4.8
Table 4.9
Table 3.10
Table 4.1 1
Table 4.1 2
Table 4.1 3
Table 4.14
Table 4.15
Stirrat's symptom reporting questionnaire article summary .............. Phden's test article summary ............................................................. Tinel's sign article summary ..............................................................
Pressure provocative test article sumrnary ......................................... S ys tematic review of clinical tests for diagnosing carpal tunnel syndrome ......................................................................
..................................... Sensory and rnotor nerve conduction studies
Segmental sensory conduction velocity and latency location ............ Diagnostic confirmation using Stinat's SRQ and nerve conduction studies .................................................................... Summary of missing subject and hand data ....................................... Subject and hand diagnostic presentation .........................................
................................................... Subject demographics by diagnosis
................................................................. Subject medical conditions
Syrnptom complex of subject hands with carpal tunnel syndrome .... Velocity measures using the segmental sensory conduction velocity technique in subject hands with and without carpal tunnel syndrome ...................................................................... Velocity measures using the 7-cm motor distal latency
............... in subject hands with and without carpal tunnel syndrome
Ten test rnodels .................................................................................. Ten test Mode1 2 criteria .................................................................... McNemar chi square cornparison between individual clinical tests .. Kappa agreement between independent . combined clinical results and gold standard ...............................................................................
...................... Prevalence rates and corresponding predictive values
LIST OF FIGüRES
Figure 2.1
Figure 4.1
Appendix 1
Appendix 2
Appendix 3
Appendix 4
Appendix 5
Appendix 6
Appendix 7
Appendix 8
Appendix 9
Appendix 10
Appendix 1 1
Appendix 13
Appendix 13
Appendix 14
Appendix 15
Carpal bones and their relationship to the median nerve ................... Il
Ten test Model 2 ROC curve ............................................................. 71
LIST OF APPENDICES
Chart Summary of Diagnostic Li terature .... Sample Size Estimation ...............................
.............................
............................ Post-hoc Sample Size Determination ................................................. Logistic Procedures ........................................................................... Information Sheet (Mount Sinai Hospital) ......................................... Letter of Informed Consent ................................................................ Demographics Questionnaire ............................................................. Symptom Reporting Questionnaire ................................................ Surgeon's Clinical Report ................................................................... Electrodiagnostic Report .................................................................... Stirrat's Symptom Response Diagnostic Report ................................ Data Management ..............................................................................
.............................................. Ten Test Models ROC Curve Analysis
Sensitivity and Specificity Analysis of Individual and Combined Clinical Tests ....................................................................
.............................. Kappa Agreement Complete Statistical Analysis
Curpal rlinnel svndrome
The rnost common nerve entrapment syndrome. characterized by pain and paresthesia in the median nerve distribution of the hand: caused by compression of the median nerve at the wrist. within the carpal tunnel (Stedman's Concise Medical Dictionary. 1997).
Disease
A morbid entity characterized by an identifiable group of signs and symptoms with consistent anatomical alterations. Literaily, dis-ease, the opposite of rase. when something is wrong with a bodily function (Stedman's Concise Medical Dictionary. 1997).
The extent to which a specific intervention. regimen. procedure, or service produces a useful result among those in an ideal and controlled clinical setting. Efficacy is established by restricting patients in a study to those who will cooperatr fully to medical advice (Fletcher, Fletcher and Wagner, 1996).
Effectiveness
The extent to which a specific intervention, regimen, procedure. or service produces a useful result among those in a less controlled population setting. Effectiveness is established by offering a program to patients and allowing them to accept or reject it as they might ordinarily do (Fletcher, Fietcher and Wagner. 1996).
Fdse negative
A diseased individual who is incorrectly identified by a negative test result (Knapp & Miller, 1992).
Fcrlse negative rate
The probability that a diseased individual will have a negative test result (Knapp & Miller. 1992).
False positive
A disease-free individual who is incorrectly identified by a positive test result (Knapp & Miller, 1992).
False positive rote
The probability that a disease-free individual will have a positive test result (Knapp & Miller. 1992).
Gold Standard
An accepted reference test (Knapp & Miller. 1992).
Likelihood ratio
The odds that a given level of a diagnostic test result would be expected in a patient with the targrt disorder (Sackett et al., 199 1 ).
Negative predictive valrie
The probability that an individuai with a negative test result does not have the disease (Knapp & Miller. 1993).
Nerve condriction study Var carpal tunnel syndrome)
An electrophysiological test designed to measure distal and/or sensory motor latency of the median nerve (Sesor. 1994).
The proportion of individuals in a population who have the disease (Knapp & Miller, 1 992).
Positive predictive value
The probability that an individual with a positive test result has the disease (Knapp & Miller, 1993).
xii
Receiver ope rat or characte ristic crtrve
A graphic representation of the relationship between sensitivity and specificity for a diagnostic test. It provides a simple tool for applying the predictive value method to the choice of a positivity criterion (Knapp & Miller, 1992).
Syndrome
The aggregate of signs and symptoms associated with any morbid process. and constituting together the picture of the disease (Stedrnan's Concise ~Medicai Dictionary. 1 997).
The probability of a positive test in those who have the target condition (Ponney & Watkins. 2000).
The probability of a negative test in those who do not have the target condition (Portney & Watkins, 2000).
A disease-free individual who is correctly identified by a negative test result (Knapp & Miller, 1992).
Tnte positive
A diseased individual who is conectly identified by a positive test result (Knapp & Miller, 1992).
A numerical estimate (ie. sensitivity, specificity, likelihood ratio) of the worth or value of a given outcome (Knapp & Miller, 1992). With respect to diagosis, utility determines whether the patient is better off for having undergone the test given the diagnostic outcome (Sackett et ai, 199 1 ).
LIST OF ABBREVIATIONS
a Alpha
ANOVA analysis of variance
CTS
cm
x' CI
O C
DWC
FN
FNR
FP
FPR
Kg LR - .Y
m
tnm Hg m.
MDL
'CTS
'PV
carpal tunnel syndrome
centimetre
Chi-square
confidence intenta1
degrees Celsius
distal wrist crease
false negative
false negative rate
falsr positive
false positive rate
ki logram
likelihood ratio
Mean
met re
millimetres mercury
Millisecond
motor dista1 latency
negative carpal tunnel syndrome
negative predictive value
NCS
00
PT
* 'CTS
'PV
Pm
P
9
ROC
N
SCV
SD
SRQ TN
TP
TS
TT
Y
zc
nerve conduction studies
numerical infinity
Phalen's test
plus/minus
positive carpal tunnel syndrome
positive predictive value
pressure provocative test
proportion of sample with CTS
proportion of sample without CTS
receiver operator characteristic
sarnple size
sensory conduction velocity
standard deviation
symptom reporting questionnaire
true negative
true positive
Tinel's sign
Ten Test
years
Z-value for Kappa statistic
xiv
CHAPTER 1
INTRODUCTION
1.1 Theme
Carpal tunnel syndrome (CTS) is a compression neuropathy of the median nerve at
the wrisr (Phalen, 1966; Szabo et al., 1999). Current controversy exists regarding a decisive
criterion measure in identifying patients with carpal tunnel syndrome (Rempel et al.. 1998).
The most commonly accepted method of confirming a diagnosis in symptomatic patients is
an electrophysiologic examination including nerve conduction and electromyography studies
(Jablecki. et al. 1993: Nathan. et. al.. 1993; Katz. 1991). Electrodlagnostic studies are
regarded by some to be the only valid objective method available for diagnosing carpal
tunnel syndrome. while clinical tests are considered subjective in nature (deKrom et al.,
1 990; Buch-Jaeger and Foucher, 1994). However, electrodiagnostic studies have
consistently dernonstrated an inability to definitively diagnose carpal tunnel syndrome or
accurately determine the degree of compression severity (MacDennid. 1991). in fact. a
cross-sectional survey indicated that only one third of surgeons systematically use
electrodiagnostic studies in their practice (Duncan et al.. 1987). A number of
electrodiagnostic studies have reported varying degrees of false negative (Grundberg. 1983)
and false positive rates (Redmond and Rimer, 1988). These studies concluded that nerve
conduction studies have limited ability to identify al1 patients with CTS and that clinicd
finding are invaluable in diagnosing carpal tunnel syndrome. Therefore, no perfect gold
standard for carpal tunnel syndrome exisü (Rempel et al., 1998).
Chica i tests are considered by many surgeons to be vaIuabIe in accuratery
diagnosing carpal tunnel syndrome (Rernpel et al., 1998, Tetro et al., 1998). Aside from the
diagnostic benefit. Katz et al. ( 1990b) suggest that clinical tests are useful in diagnosing
carpal tunnel syndrome due to the financial savings cornpared to the more extensive costs
with respect to time and equipment afforded by electrodiagnostic evaluation. Currently,
there are several convenient clinical tests used to evaluate patients suspected of suffering
from carpal tunnel syndrome. The list of clinical tests used to diagnose carpal tunnel
syndrome is extensive. Such tests include self-administered symptorn reponing dizgrams
(Katz et al., 1 WOa), symptorn severity and functional status questionnaires (Levine et al..
1993), Phalen's wrist flexion test (Phaien et al., 1966), wrist extension test (de Krom et aI.,
1990). wrist flexion with median nerve compression (Tetro, et al.. 19~8) . Tinel's sign
(Heller et al.. 1986). pressure provocative test (Kaul et al., 2001: Williams et al., f992), Ten
test (Berish Strauch. persona1 communication), carpal compression test (Wainner et al.,
2000: Durkan et al., 199 l ) , pneumatic-tourniquet test (GilIiat and Wilson, 1953). lumbrical
provocation test (Ku1 et al., 2001). static and moving 2-point discrimination (Mackinnon et
al., 1985), von Frey hairs or Sernmes-Weinstein monofilament test (Borg, 1988), tethered
median nerve stress test (Raudino, 2000; LaBan et al., 1986) and vibrometry sensibility
(Kamon, 1994; Szabo et al., 1984). Furthemore, interactive microcornputer programs for
clinical screening of carpal tunnel syndrome have demonstrated a successful degree of
accuracy (Rudolfer. 1988; 1992).
Despite the number of clinicd tests used in diagnosing carpal tunnel syndrome, these
tests are plagued with disagreement (Hadler, 1997). Concems regarding the usefulness of
clinical tests in the diagnostic aigorithm are consistently raised as a problem facing the
medical community stemming from discrepant resuks (Buch-Jaeger et ai.. 1995; Iablecki et
al., 1993). The literature has reported a wide range of utility measures including sensitivity
and specificity for diagnosing carpal tunnel syndrome. resulting in a tack of confidence in
their accuracy. Furthemore, diagnostic articles regarding carpal tunnel syndrome
demonstrate a necessity for well-controtled studies with special regard for clinicai
epidemiology standards including an appropriate spectnim of patients. blinding of examiners
and adopting the most recognized goid standard. Regardless. independent and combined
clinical test results continue to be a popular component in the decision making process for
diagnosing carpal tunnel syndrome. Therefore. the main purpose of this study was to
evaluate the efficacy of clinical tests in the diagnosis of carpal tunnel syndrome.
1.2 Objectives
The primary objective of this study was to determine the efficacy of independent and
combined clinicai tests in the diagnosis of carpal tunnel syndrome.
A secondary objective of this study was to establish positivity cnterion for the Ten test
in the diagnosis of carpal tunnel syndrome.
1.3 Hypothesis
It was hypothesized that Phalen's test. Tinel's sign. the pressure provocative test and
the Ten test would demonstrate clinicai efficacy in the diagnosis of carpal tunnel syndrome.
CHAPTER 11
REVlEW OF LITERATURE
2.1 Introduction
This chapter will review historical and curent literature surrounding carpal tunnel
syndrome. However, antecedent to specifically reviewing carpal tunnel syndrome. this
review will initially examine the challenges of diagnosing a syndrome and the importance of
a reference or gold standard in validating a diagnosis. Moreover. an appraisal of literature
surrounding the definition, anatomy. etiology. pathophysiology. diagnosis and treatment of
carpal tunnel syndrome will be conducted. Finaily, a systematic appraisal of studies
outlining clinical tests adopted to diagnose carpal tunnel syndrome will be surveyed with
regard to appropriate methodological criterion (Sackett et ai., 199 1 ). Appendix 1 provides a
complete chart of the individuai studies with particular detail to the clinical tests measured,
reference standard. blinding, patient spectrurn and diagnostic outcorne.
2.2 Diagnosis of a syndrome
The diagnosis of carpal tunnel syndrome can be made confidently in patients who
present with the characteristic history, physical examination findings and electrodiagnostic
abnormalities. However, confidence decreases as the presentation deviates from this
diagnostic profile (Rempel et al., 1998). The medical literature demonstrates controveny
regarding a case definition for diagnosing carpal tunnel syndrome. This disagreement could
be in part to: i) defining a syndrome, ii) identifying an appropriate diagnostic algorithm and
iii) recognizing an acceptabIe gold standard. These disputed details wil1 be discussed with
specific reference to carpal tunnel syndrome.
2.2.1 Defining a syndrome
A syndrome is defined as 'the aggregate of signs and symptoms associated with any
morbid process and constituting together the picture of the disease' (Stedman's Concise
Medicai Dictionary. 1997). Similady, disease is identified as 'a morbid entity characterized
by an identifiable group of signs and symptoms with a consistent anatomical mutation'
(Stedman's Concise Medical Dictionary. 1997). However. a critical difference between
these definitions is the consistency to which signs and symptorns are allied with physical
abnormality characteristic of a disease. which is not always identifiable in a syndrome. The
literature clearly demonstrates the inability to definitively confinn a diagnosis of carpal
tunnel syndrome in patients with symptoms in the median nerve distribution using signs
including clinical tests (Buch-laeger and Foucher. 1994) and nerve conduction studies
(Jablecki et al.. 1993: Grundberg, 1983).
A symptom is referred to as covert details perceived by the patient and cannot be
observed by others (Sims et al.. 1995). Conversely, a sign is defined as oven information
observed or measured by a health care professional. usually during a physical exarnination
(Sims et ai.. 1995). In practice. the definitions for sign and symptom wouid propose that the
suspicion of carpal tunnel syndrome is reinforced by subjective symptoms identified in a
patient's history in conjunction with an objective physical examination (Johnson, 1993).
However. there is a wide range of opinion from medical and surgical specidists when
acknowledging what constitutes an objective physical examination (Szabo et al.. 1999).
Buch-Jaeger and Foucher (1994) state that electrodiagnostic studies are the onIy tme
objective method available for diagnosing carpal tunnel syndrome. Meanwhile. Szabo and
colleagues ( 1999) suggest that electrodiagnostic tests do not increase the probabili ty of
diagnosing CTS any more than clinical tests. However, both electrodiagnostic studies and
clinical provocative tests have consistently demonstrated an inability to definitively predict
carpal tunnel syndrome. which funher complicates the diagnosis (Rempel et al.. 1998).
Therefore, the literature indicates a discrepancy with regard to what constitutes an objective
diagnostic sign that accurztely identifies and localizes dysfunction of the median nerve in
the carpal tunnel.
2.2.2 Diagnostic algorithm
The American Academy of Neurology (Altrocchi et al.. 1993) have reported practice
parameters for carpal tunnel syndrome. Specificaily, Altrocchi and colleagues provide a
descriptive and graphical illustration of a diagnostic algorithm outlining the decision process
in validating a compression neuropathy at the wrist. The algorithm begins with a patient
history including standard symptoms of pain and paresthesia in the median nerve
distribution as well as provocative factors such as nocturnal wakening or repetitive
movement of the hand or wrist. The likelihood of definite carpal tunnel syndrome increases
with the number of standard symptoms and provocative factors (Szabo et al.. 1999).
Altrocchi and colleagues advocate confirmatory nerve conduction examinations in patients
demonstrating definite CTS syrnptoms. However, if the patient's symptorns are less definite,
a standard physicai examination including Tinel's sign, Phaien's test. thenar weakness and
atrophy is recommended. However, Altrocchi and colleagues ( 1993) suggest that regardless
of the physicai examination results, aiT patients should stïil undergo nerve conduction or
electromyographic studies. They propose that an electrodiagnostic examination not only
confirms a diagnosis. but d so classifies the severity of damage to the peripheral nerve. In
contrast. a recent prospective study constmc:ed a diagnostic algonthm based on Bayes's
theorem using clinical tests to accurately diagnose without reson to electrophysiologic
examination. O'Gradaigh and iMerry (2000) found this algorithm demonstrated high
accuracy when compared to nerve conduction studies in diagnosing carpal tunnel syndrome
regardless of the reported symptoms. They concluded that an algorithm of clinical tests can
confirm CTS patients without electrophysiologic studies and therefore contribute to an
expeditious treatment. Again. the current lirerature demonstrates two theories regarding the
importance and function of clinical tests and electrophysiologic examinations as diagnostic
criteria.
1.2.3 Challenge of a "gold standard"
Gold standard is defined as an accepted reference test (Knapp and Miller, 1992).
The presrnce of a gold standard is imperative in establishing cnterion vdidity of new or
existing diagnostic tests (Streiner et al., 1989). Rempel and colleagues ( 1998) attempted to
establish diagnostic criteria for carpal iunnel syndrome and concluded that there is no
perfect gold standard. Two factors contributing to the inability to establish a definitive case
definition for carpal tunnel syndrome include the inconsistent clinical presentation that a
syndrome demonstrates as well as the impractical use of electrodiagnostic examinations in
some epidemiologic settings.
CIinicaI presentation of carpal tunnel syndrome does not aiways demonstrate a
consistency between signs and symptoms. particularly in acute or mild cases (Rempel et al.,
1998). Researchers have attempted to establish a gold standard using everything from
symptom reponing to nerve conduction studies. but with iittle success. Electrodiagnostic
studies alone are considered by some to be the gold standard (Johnson, 1993). However,
certain patients with abnormal nerve conduction studies will demonstrate insignificant or no
symptoms of the median nerve. Rempel and colleagues (1998) refer to these patients as
"silent carpal tunnel syndrome" cases. but concluded that an asyrnptomatic patient with a
positive electrodiagnostic finding should not constitute a diagnosis of carpal tunnel
syndrome. Conversely. other medical professionals rely on symptoiiis and clinical tests in
diagnosing carpai tunnel syndrome. Furthemore. there is evidence of successful surgicd
decompression in patients demonstratinp abnormal clinical findings in light of a normal
nerve conduction evaluütion (Finsen and Russwurm, 200 1 : Gmndberg, 1983). Finsen and
Russwurm (2001) performed surgery in 68 patients with typical CTS who had undenvent
neurophysiological investigations pre-operatively, but were not assessed until the end of the
snidy. Prompt resolution of pre-operative symptoms was used as the benchmark for
confimiing a CTS diagnosis. Sixty-three of the patients responded favorably to surgery.
Three patients had equivocal outcornes, while two did not improve and were considered not
to have CTS. Subsequently. the neurophysiologicai tests were nonnal in these two patients,
but were also normal in 14 of the 63 patients who demonstrated positive resolution of
symptoms following carpal tunnel surgery. Finsen and Russwurm (2001) concluded that
nerve conduction studies contributed minimal to the diagnosis in t-ical cases of carpal
tunnel syndrome. and more o ften cornplicate the diagnosis. However, surgicd intervention
in s ymptomatic patients with negative electroph ysiologicd evidence is not completery
supported. nor undentood in the medicai community. Rempel and an ad-hoc cornmittee of
experienced research physicians could not reach a consensus regarding diagnosis of patients
with classic or probable CTS symptoms in combination with a negative electrodiagnosis
(Rempel et al., 1998).
Finally, screening criterion that requires nerve conduction studies is often impractical
in population-based settings. such as occupationai environments (Szabo et al.. 1999).
Fletcher et al. (1996) suggests that the gold standard for many medicai conditions is often
impractical due to medical costs or discomfon to the patient. With regard to diagnosing
carpal tunnel syndrome. Katz and colleagues ( 1990b) agree that nerve conduction studies are
expensive with costs between $150 to $500 (US cunency) and painful compared to
symptom reponing. As a result. simpler tests are often used as proxies for an impractical
reference standard. Rempel and colleagues (1998) concluded that clinical tests are an
acceptable replacement in the absence of electrodiagnosric findings. particularly for
screening purposes in community settings. Furthemore, they recornmended that patients
diagnosed with CTS demonstrate abnomal clinical test or electrodiagnostic findings in
combination widi classic or probable symptoms as outlined by Stirrat's symptom reponing
questionnaire.
2.3 Defining carpd tunnel syndrome
Carpal tunnel syndrome is a common penpheral neuropathy and occurs when the
median nerve that channels through the wrist to the hand becomes compressed (Nathan and
Keniston, 1993). Carpal tunnel syndrome was first described in 1854 as a "complication of
trauma" (Pfeffer et al., 1988). Since then, carpal tunnel syndrome has increased in epidemic
proportions and has a current prevalence of 2.74 in the general population (Atroshi et al..
1999). The classic patient suffering from carpai tunnel syndrome is the middle-aged femaie
exposed to work requiring repetitive activity causing wrist strain who suffers frorn pain and
parethesias in the thumb. index. long and radial side of the ring finger (Ditmars, 1993).
Thus. carpal tunnel syndrome is considered a disorder of practical importance since it is a
source of poor productivity in a modem post-industridized society (Nathan and Keniston,
1993).
2.4 Anatomy of the carpal tunnel
The carpal tunnel is a narrow cornpartment comprised of an arch of carpal bones and
the transverse carpal ligament (Figure 2.1). The tunnel extends from the middle of the wrist,
as characterized by a skin crease on the antenor side when the wrist is in full flexion, distally
to the edge of the fully abducted thumb (Ditmars. 1993). The contents of the carpal tunnel
include nine flexor tendons. accompanying tenospovium and the median nerve (Schenck,
1989). In the wrist. the median nerve is routed through a small passage bound by eight
c q a l bones and the rigid transverse ligament tissue connecting them. The median nerve
has both sensory and motor functions. The sensory branches innervate receptors in the
thumb, index. middle and radial half of the ring finger. The motor branches supply thenar
muscles and lumbrical musculature of the index and middle finger (Ditmars, 1993). Since
the carpal tunnel is a ngid structure, any influence chat promotes tissue swelling within the
tunnel or reduces its size tends to cornpress and pinch the median nerve (Nathan and
Keniston, 1993).
Figure 2.1 Carpal bones and their relarionship to the rnedian nerve
2.5 Etiology and pathophysiology
Carpal tunnel syndrome and its associated risk facton have been a topic of research
for several years. Any factor considered to compromise the space of the c q a l canal,
thereby causing pressure on the median nerve. can cause the symptoms of carpal tunnel
syndrome (Kulick. 1996). Ischemia in the median nerve is considered to be the predominant
factor associated with the signs and symptoms on the median nerve. The increased pressure
occludes intraneural vessels. compromising nutrition and impairing conduction (Sunderland,
1976). Research over the p s t decade has closely examined a multitude of potential risk
factors that are important in the etiology of carpal tunnel syndrome. The occurrence of
carpai tunnel syndrome has been associated with diverse etiological factors, including
medicaIIy predisposed disease as welI as independent personal and occupational factors.
Predisposing injuries include externai factors. such as Colles' fracture (Lusthaus et al.. 1993;
Stevens et al.. 1992; Wainapel, Davis. and Rogoff. 198 1 ) and dislocation of carpal bones
within the carpal canal (Monsivais and Scully. 1992). Kulick ( 1996) suggests that CTS
symptoms following a wnst fracture are more commonly due to ederna, rather than an
anatomical compression. Fluid retention conditions can be attributed to the development of
carpal tunnel syndrome by engorging the synovium. Researchers have demonstrated a
predisposed association with the onset of carpai tunnel syndrome and patients suffering from
long-term hemodialysis (Sivri et al., 1994: ikegaya et al.. 1995: Gilbert et al.. 1988). Semer
and colleagues ( 1989) suggest that rend dialysis is thought to increase intravascuiar flow.
causing synovial edema in patients undergoing hemodialysis. Furthemore. the carpal canal
can be compromised by arnyloid deposits in the transverse carpal ligament. which are
characteristic of dialysis patients (Kulick. 1996). Other medical conditions characteristic of
edema in the wrist include hypothyroidism (Chishoim, 198 1: Rao et al.. 1980),
hypenhyroidism (Roquer and Cano, 1993). and pregnancy (Al Qattan. Manktelow and
Bowen. 1994: Voitk et al.. 1983: Gould and Wissinger, 1978). Hormonal fluctuations are
considered the contributing factor of CTS symptorns during pregnancy. Furthemore, the
hormone relaxin. which is secreted during pregnancy, causes the transverse carpal ligament
to loosen thereby collapsing the carpal arch (Nichols et al.. 197 1). Inflammatory conditions
have been associated wirh the onset of carpal iunnel syndrome. Studies have provided
evidence of a CO-existence between carpal tunnel syndrome and rheumatoid arthritis
(Vemireddi, Redford and Pombejara, 1979) with prevalence rates ranging from 6% (Stevens
et al., 1992) to 438 (Florack et al., 1992). Similady, tophaceous gout can cause the
tenosynovium of the wrist be become ihickened (Ogilvie and Kay, 1988). Lumbricd
hypertrophy is an intnnsic factor thought to be associated with carpal tunnel syndrome.
Activities that require repetitive wrist flexion, strong gripping and finger flexion result in
over-developed forearm muscles (Robinson et al.. 1988). The hypertrophy causes the
lumbrical muscle bed to be pushed down into the carpal canal compressing the rnedian nerve
(Cobb et al.. 1994: Yii and Elliot. 1994. Erikson. 1973). Finally. other rnedical conditions
associated with carpal tunnel syndrome include vitamins Bs and C deficiency (Keniston et
al.. 1997). acromegaiy (Woo. 1988). type I and II diabetes mellitus (Chammas et ai.. 1995:
Casey and Pamela. 1972) and hormonal agents. such as oral contraceptives (Stevens et al..
1 992).
Penonal and occupational factors are considered idiopathic representation of carpal
tunnel syndrome and make up half of ail cases in the general population (Stevens et al..
1992). There is mounting evidence suggesting that some worken exposed to high risk
activities involving repetitive and forceful movements of the hands and wrists experience
symptoms characteristic of carpal tunnel syndrome. These occupations include fish (Chiang
et al.. 1993; Ohlsson et. al., 1989) and poultry process workers (Schottland et al.. 199 1 ), data
enuy operators (Pickett and Lees, 199 l), platen and truck assemblers (Nilsson et al.. 1994),
ski manufacturing workers (Barnhart et al., 199 1). grocery store cierks (Osorio et ai., 1994).
and video display terminal workee (Bergqvist et ai.. 1995; Bernard et al.. 1994). Currently.
Pascarelli and Quilter (1994) considered carpal tunnel syndrome to be the most common
repetitive strain injury with incidence rates ranging from 5 to 25%. The high prevalence of
carpal tunnel syndrome in our industrialized society has also been referred to as a "repetitive
strain injury" (English et al., 1995: Ranney, Wells and Moore. 1995)- "industrial epidemic"
(Schenck, 1989) and "cumulative trauma disorder" (Young et al.. 1995: Silventein. Fine and
Armstrong, 1 986).
A well-recognized correlation between certain work-related tasks and idiopathic
carpal tunnel syndrome has been documented. such as repetitive wrist flexion and extension.
strong gripping with ulnar deviation. impact forces on the palm and weak vibratory forces
(Ranney, Wells and ~Moore, 1995). The literature has also indicated inconsistencies with
regard to this b'job-relatedness hypothesis". First, compensated carpal tunnel syndrome
cases were reported from a nurnber of different occupations that did not require forceful or
repetitive use of the wrists. Second. a closer analysis of speciîïc repetitive strain type
occupations at a variety of industries demonstrated that the majority of employees did not
have carpal tunnel syndrome. Finally. the relatively short average duration of employment
of workers' compensation patients indicated that one third of al1 carpal tunnel syndrome
claims were for individu& who had been employed for 1 year or less (Nathan and Keniston.
1993). It appean carpal tunnel syndrome may not be solely occupation-related due to the
brevity of cumulative trauma required to manifest CTS symptoms in employees exposed to
repetitive wrist activity.
Curren t researchen have argued kat individual charac teristics. unrelated to the
frequency of wrist movements, are the p r i m q deteminants of idiopathic carpal tunnel
syndrome in the generai population. These perscnal characteristics include age (Hennessey
et ai.. 1991). gender (de Krom et al., 1992: Dieck and Kelsey, 1985). body mass index
(Stallings et ai., 1997; Werner et al., 1994; Nathan and Keniston, 19931, avocational
physical activity level (Nathan and Keniston, 1993; Nathan et al.. 1992), race (Widgerow et
al.. 1996: Goga, 1990). familial predisposition (Michaud et al., 1990: Barfred and Ipsen.
1985). sleeping behavior (Luchetti et al., 1994: Radecki, 1996). and wnst dimension
(Radrcki, 1994: Bleeker et al.. 1985: Johnson et al.. 1983). A convincing degree of
epidemiological evidence has concluded that such penonal factors are important precurson
of clinicai carpal tunnel syndrome aside from the number or intensity of repetitive
rnovements (Nathan and Keniston. 1993). Despite the overwhelming evidence suggesting
that carpal tunnel syndrome can be a work-related or ergonornic condition, no clear dose-
response relationship has been established between the amount or intensity of repetitive
work and the incidence or severity of the syndrome (Agee et al.. 1992). Likewise,
considering the occurrence of idiopathic carpal tunnel syndrome in the general population, it
has been difficult to speculate what degree of risk can be attributed to ergonornic activity
(Katz. 1994) or any of the aforementioned penonal iîsk factors.
2.6 Diagnosis
Appendix 1 provides a complete chart of the individual diagnostic studies with
particular reference to the clinical tests measured and diagnostic outcorne. Controversy
regarding a decisive criterion measure in diagnosing carpal tunnel syndrome exists in the
literature (Rempel et al.. 1998). It is proposed by many that the most accurate method of
confirming a diagnosis in symptomatic patients includes nerve conduction and
electrornyography snidies (Jablecki et al. 1993: Nathan et. ai.. 1993: Katz. 1991). However,
electrodiagnostic studies have consistently demonstrated an inability to identify ail patients
with CTS and that clinical tïndings are invaluable in diagnosing carpd tunnel syndrome.
Rempel and colleagues (1998) suggest that no perfect gold standard for carpal tunnei
syndrome exists. but that both clinical and electrodiagnostic tests are important cornponents
in the diagnostic dgorithrn for carpal tunnel syndrome. The foiIowing review of diagnostic
literature will specifically address the efficacy of both electrodiagnostic studies and clinicd
tests.
2.6.1 Electrodiagnostic studies
Lmprovements in nerve conduction techniques have lead to its popular use in
diagnosing carpal tunnel syndrome. Currently, nerve conduction studies are considered by
many to be the most effective rnethod of confinning an objective diagnosis in symptornatic
patients suspect of carpal tunnel syndrome (Jablecki et al.. 1993; Nathan et al.. 1993: Katz et
al., 199 1 : Kimura, 1979). Nerve conduction studies encompass many techniques including:
i ) median nerve motor distal latency (Kimura. 1979): ii) median sensory nerve conduction
between the wrist and middle or index finger - usually a distance of 14 cm in normal adults
(Carroll. 1987): iii) median sensory and mixed nerve conduction between the wrist and palm
between the second and third metacarpal (Jablecki et al., 1993); iv) segmental or inching of
the sensory nerve across the carpal tunnel (Kimura 1979): v) cornparison of median and
ulnar rnixed nerve sensory conduction between the wrist and palm berween the fourth and
fifth metacarpal heads or ring finger (Uncini et al., 1993) and vi) comparison of rnedian and
radial sensory conduction between wrist and thumb (Carroll, 1987).
Electrodiagnostic techniques have been modified and revised in an attempt ro
identify mild compression neuropathy in the carpal tunnel (Kimura, 1979). It is important to
recognize the standard to which electrodiagnostic studies are compared since they are
considered by many to be the rnost objective reference standard available in diagnosing
carpal tunnel syndrome. Use of clinicd criteria, including classic pain and paresthesia in the
rnedian nerve distribution of the hand and clinical test provocation (i.e.. Phden's test. finel's
sign), permit identification of CTS patients in which to test the sensitivity of the
electrodiagnostic procedure to confirm a diagnosis of carpal tunnel syndrome. Furthemore,
the results of electrodiagnostic procedures in control subjects are required to determine the
specificity of the electrodiagnostic test (Jablecki et al., 1993).
The most common neurophysiological abnormalities found in carpal tunnel
syndrome are the increases in distal motor and sensory median nerve latencies.
Funhermore, electrodiagnosis of the median nerve has demonstrated that sensory conduction
techniques are more sensitive than motor conduction techniques (Jablecki et al.. 1993: Cioni
et ai.. 1989). According to the Quality Assurance Committee of the American Association of
Electrodiagnostic Medicine. the most sensitive techniques supporting the diagnosis of carpal
tunnel syndrome are those that evaluate sensory nerve conduction across a short distance of
the carpal tunnel. particularly in patients with mild CTS. However. rnotor distal latency is
still considered efficacious in identifying patients with a compression neuropathy of the
wrist in moderate and severe CTS (Jablecki et al.. 1993). Irnaoka ( 1992) demonstrated the
efficacy of sensory and motor nerve activity indicating a fdse-negative rate of IO% and 25%
in sensory and motor nerve conduction studies, respectively. Furthemore, Jablecki and
colleagues ( 1993) suggested that "speciaiized nerve conduciion examinations, such as the
segmental stimulation technique, or comparative exarninations. such as median to ulnar or
median to radial sensory conduction in the same hand. are the most sensitive of ail nerve
conduction studies. More recently, the segmental stimulation technique has been described
as the most reliable, highly sensitive and specific procedure for diagnosing carpal tunnel
syndrome (Irnaoka et al.. 1992). This electrodiagnostic procedure. sometimes referred to as
the b'centimetnc" or "inching" technique, because of its abiîity to measure sensory Iatency of
the median nerve across the carpai tunnel in one centimeter increments. is effective in
localizing the exact conduction deficit. Therefore. mild carpal tunnel syndrome and the
precise compression site dong the median nerve are more identifiable in patients that would
have otherwise been overlooked using less sensitive nerve conduction techniques (Nathan,
Meadows. and Doyle. 1988).
Segmental stimulation has demonstrated sensitivity and specificity vaiues as high as
100% (Seror. 1994) and 97% (Nathan et al.. 1988). respectively. Nathan and colleagues
( 1988) adopted receiver operator characteristic curves to establish the most appropriate cut-
off in establishing positivity criterion for segmental technique at sensory latencies of 0.5 and
0.4 ms. The resul ts demonstrated sensitivities of 5 4 8 and 8 1 5% and specificities of 97% and
8 1% with a cut-offs of 0.5 and 0.4 ms.. respectively. Although sensitivity and specificity
increased by altering the cut-off, the predictive accuracy decreased from 93% at 0.5 ms. to
77% at 0.4 ms. However, a cut-off at 0.4 ms. is particular valuable since sensitivity
significantly increased to an acceptable level. while the high specificity level remained
relatively unchanged. Nathan and colleagues concluded that a segmenta1 latency value of
0.4 ms. for a k m segment of the median nerve lies outside the nomal range and is a
sensitive, specific and accurate predictor of carpai tunnel syndrome. Similarly, Seror (1994)
deemed the segmental stimulation technique to be the most reliable and specific in
diagnosing carpal tunnel syndrome using a cut-point of 0.4 m. compared to nine other
electrophysiological tests, including the specialized median to ulnar sensory nerve
comparative technique. Finally, Luchetti and colleagues ( 199 1 ) exarnined the effectiveness
of surgical r e l e ~ e in 14 mild CTS patients. The results demonstrated the superior ability of
segmentai stimuration compared to both wrïst to digit and wrist to pdm conduction
techniques in localizing the site of sensory nerve latency across the carpal tunnel being
between 1 to 2 cm from the distal wrist crease in 57% and 2 CO 3 cm in 2 1% of cases.
Furthemore, the diagnostic sensitivity of the segmental sensory nerve conduction velocity
at I-cm increments was 87%. Luchetti et al. (1991) concluded that the segmental technique
was the most sensitive diagnostic method in detecting early carpal tunnel syndrome.
However. despite the evolution of electrophysiological examinations. nerve conduction
studies are not considered to be completely exact (Jablecki et al.. 1993).
2.6.2 Clinicd tests
Despite the evolution in specialized electrophysiological techniques, clinical tests
continue to be a popular component in the diagnostic algorithm of carpai tunnel syndrome.
Three types of clinical tests are currently used to diagnose carpal tunnel syndrome. including
i) symptoms reporting (Le.. Stirrat's symptom reporting diagram and Levine's symptom
severiry and functional status questionnaire), ii) provocative tests (e.g.. Phalen's wrist
flexion test, wrist extension test, reverse Phalen's test, Tinel's sign, pressure provocative test,
carpal compression test. lumbrical provocation test, tethered median nerve stress test and
combined wrist flexion. and carpal compression) and iii) sensibility tests (e.g.. Ten test,
static and moving 2-point discrimination, von Frey hairs or Semmes-Weinstein
monofilament test, and vibrometry sensibility). A 20-year summary of diagnostic studies
and corresponding utility measures, including sensitivity, specificity, positive and negative
predictive values. are condensed in Appendix 1.
Despite the number of tests used to diagnose carpal tunnel syndrome, lhis
compression neuropathy continues to be plagued with controveny (Hadler. 1997). The
literature demonstrates numerous inconsistencies between electrophysiological studies and
clinical tests (Buch-Jaeger et al.. 1995: Jablecki et al.. 1993: Katz et al. 1990a,c).
Subsequently. concems regarding discrepant clinical results are consistently challenged and
have provoked the medical community to question their tme accuracy (Buch-Jaeger and
Foucher, 1995). Technical variations in test administration as well as patient differences
(e.g.. limb temperature) are factors contributing to variations in diagnostic outcome
(Mossman and Blau, 1987: Hilbum, 1996). Furthemore, methodological pinciples
consistent with clinicd research are often neglected or violated In diagnostic trials leading to
various forms of bias (Sackett et al., 1991). Possible violations attributing to inaccurate
clinical results include i ) less effective design types. such as retrospective cohon studies.
which contribute to recall bias, ii) failure to independently blind the clinical test and
reference standard, which results in diagnostic suspicion bias or ii i) limited patient spectrum
as a result of referral bias (Massy-Westropp, Grimmer and Bain. 2000: Tetro et al., 1998).
A number of clinicat tests have diminished in popularity over the years due to
expense such as vibrometry (Katz et ai., 1990a) Other clinical tests such as Semmes-
Weinstein monofilment are considered to be time consuming and less reliable under
distracting conditions (MacDermid et ai., 1992). However. a battery of clinical tests
cumently in use have demonstrated inconsistencies and therefore require funher review.
This battery includes Stirrat's self-adrninistered symptom reporting questionnaire, Phalen's
test, Tinel's sign, the pressure provocative test and the Ten test.
2.6.2.1 S ymptom reporting questionnaires
Stirrat's self-administered symptom reporting questionnaire (SRQ) is frequently
referred in the Iiterature as Katz's SRQ. However. C.R. Stirrat was confirmed as the onginal
designer of this self-administered symptorn reporting questionnaire (personal
communication with J. N. Katz and C. R. Stirrat). Therefore. this SRQ will be referred to as
that of the designer. Stirrat's self-administered symptom reponing questionnaire (SRQ) has
demonstrated excellent inter-rater reliability (r=0.84) and test-retest reliability (r=0.9 1 ) (Katz
et al.. 1990a). Table 2.1 provides a summary of four studies that examined the diagnostic
efficacy of Stirrat's SRQ (Katz et al.. 1990a. 1990b. 1990~: Gunnarsson. 1997). These
studies reported an independent and blind cornparison between Stirrat's SRQ and nerve
conduction studies. Furthemore. ail studies, except Katz et ai. (1990b), confirmed a CTS
diagnosis in symptomatic patients with a positive nerve conduction examination. This study
confirmed a diagnosis for carpal tunnel syndrome using one of the following, i) nerve
conduction studies, ii) unequivocd response to corticosteroid injection in the carpal tunnel
or iii) cessation of hand symptoms follow ing surgical release of the transverse ligament.
The therapeutic intervention of corticosteroid into the carpal tunnel has only proven as a
sensitive and specfic reference in mild cases of CTS in conjunction with behavior
modification (i.e., decreased repetitive activity), which was not the case in the Katz et al.
(1990b) investigation. This could have attributed to the inflated sensitivity (808) and
specificity (90%) values using Stirrat's SRQ found by Katz and colleagues ( 1990b) that were
not demonstrated in the other studies. Furthemore, Katz and colleagues (1990b) reported
an exaggeratedly high CTS prevaience (Le., 8 8 4 ) . Patients were eliminated from their
smdy if ihey demonstrated an equivocal C î S diagnosis, including those with thoracic outiet
symptoms and positive overhead and shoulder abduction maneuvers. A prevalence of 88% is
considered to be an oventated number of confirmed CTS patients. even by clinical
standards. and thus represents an inappropriate spectmm of patients. Two studies by Katz
and colleagues ( 1 WOa) and f 1990~) reported more reasonable clinical pre-test probabilities
of 488 and 405. respectively. Both these studies demonstrated acceptabie. albeit lower,
sensitivities (6 1%-64%) and specificities (7 1 %-73%). Regardless. Stirrat's hand diagram
appeared to be a valuable diagnostic aid for directing early management of carpal tunnel
syndrome care. Stirrat's self-administered questionnaire is a visual presentation of a hand
diagram that appears to be more useful in reponing CTS symptoms compared to other non-
diagram questionnaire (Levine et al.. 1993). Atroshi and colIeagues ( 1997) compared Stirrat
and Levine's symptom reporting questionnaires in 156 consecutive new patients presenting
with pain. numbness, or tingling of the upper extremity. They concluded that Stirrat's SRQ
was more accurate in diagnosing CTS with measures for sensitivity and specificity that
exceeded those of Levine's questionnaire.
Not only is symptom reporting dependent upon the manner in which the symptoms
are reported. but also upon the specific population. In a five year longitudinal study of
symptomatic industrial workers. Nathan and c o l l ~ u e s ( 1992) found symptom reporting to
be variable and a poor predictor of future carpal tunnel syndrome. Aside from the subjective
custom in which employees reported symptoms (verbal cues during a history taking
examination), complaints of pain and clurnsiness were frequent. These complaints were
often due to musculoskeletal aches and pains associated with vigorous work rather than the
symptorns characteristic of carpal tunnel syndrome, which can be difficult to distinguish.
Therefore, reported hand symptoms by industrial worken rnay be a product of the physical
chaITenges of work rather than the tme etiorogy of a compression neuropathy in the carpai
tunnel. A few recent studies have recommended diagnosing carpal tunnel syndrome by
combining the resul ts of Stirrat's SRQ with electrodiagnosis (Gunnarsson et al., 1997;
Rempel et al.. 1998). Rempel and colleagues (1998) concluded that a classic or probable
Stirrat classification in conjunction with a positive electrodiagnosis would be an important
component in the CTS diagnostic algorithm for both population-based and clinicai-based
research.
Table 2.1 Stirrat's symptom reporting questionnaire article summary - -- --
Reference Y ear Hands Sens Spec 'PV -PV LRt
Katz et al. 1990b 149 0.80 0.90 8 .O0 Katz et al. 1990a 110 0.64 0.73 0.58 0.9 1 2.37 Gunnarsson et al. 1997 100 0.66 0.69 2.13 Katz et ai. 1990c 110 0.6 1 0.7 1 0.59 0.73 2.10 Sens = Sensiuviry; Spec = Spccificity; 'PV = Positive predictive vdue; 'PV = Negattvc pdicavr: value; LR = Likelihood ntio t Liktlihood ntio was not nponcd. but cdculated from existing scnsiiivity and specificity vducs reponed in the litcnnire.
2.6.2.3 Provocative tests
Provocative testing is based on the premise that compression of the median nerve
causes aggravation resulting in pain and paresthesia (MacDemid. 1991). Despite their
clinical popularity, the scienti fic literature has demonstrated variable results of these
provocative tests with regard to accurately diagnosing carpal tunnel syndrome. Phalen's
test, Tinel's sign and pressure provocative test are commonly used clinicd tests.
Table 2.2 provides a summary of articles that examine the diagnostic efficacy of
Phalen's wrist flexion test. In the early 1950's. G.S. Phalen popularized his own wrist
flexion test. which was designed to provoke symptorns in the hand following spontaneous
compression of the median nerve (Phalen, 1951). Since then, Phalen's wrist flexion test
continues to be a recommended provocative test for diagnosing carpal tunnel syndrome
(Gellman et al.. 1986; Gonziiez Del Pino et al.. 1997). However, Phaien's test has
demonstrated a wide accuracy range for sensitivity frorn 3 3 6 (Mossman and Blau. 1987) to
91% (De Smet et al., 1995) and specificity from 33% (De Smet. et al., 1995) to 100%
(Williams et al., 1997). Williams and colleagues (1992) exarnined only a srnail patient
spectrurn (Le.. 30 CTS hands and 30 control hands). failed to independently blind the
examiner and adopted an unacceptable reference standard (i.e.. no ilectrodiagnostic
examination) that may have attnbuted ro the high sensitivity and specificity values.
Furthemore. discrepancies exist with positive and negative predictive values as low as 49%
and 48% (de Krom et al.. 1990) and as high as 94% and 73% (Fertl et al., 1998),
respectively. Since the studies of de Krom et ai. (1990) and Fertl et al. (t998) were well
designed diagnostic trials. it is difficult to determine the efficacy of Phalen's test based on
these conficting results and ttierefore requires hinher investigation.
Tinel's sign continues to be commonly used. albeit inconsistently as a clinical test in
diagnosing carpal tunnel syndrome (Table 2.3). Values range for sensitivity and specificity
as high as 100% (De Smet et al., 1995) and 1 0 % (Williams et al., 1992) to as low as 32%
(Ghavanini et al.. 1998) and 42% (De Smet et al.. 1995), respectively. Mossman and Blau
(1987) suggested rhat failure to elicit pain and paraesthesia from percussion of the median
nerve at the wnst have resulted from "gentle tapping" with smdler hammen or fingertips
rather than a larger broader based Queen hamrner as well as failure to percuss the median
nerve with the wrist in an extended position. which tenses the coqtents of the carpal tunnel
so that percussion is transmitted to the median nerve. Furthemore. Novak. and colleagues
( 1992) attributed inferior efficacy measures of Tinel's sign to the pathological stage of
carpal tunnel syndrome. Since a positive Tinel's sign indicates regeneration of nerve fibres:
this percussion test would have increased sensitivity in the later stages of CTS when the
nerve has already undergone physiological degeneration and is in the process of
regenerating. Therefore. Tinel's sign appears to be vulnenble to variability in both the
technical administration of the test as well as the severity of the patient's condition.
Pathological differences and examiner error in association with a weak clinical trial may
contribute to the variable results.
Table 2.2 Phalen's test article surnmary
Reference Year Hands Sens Spec 'PV LRi
Williams et al. Fertl et al. Gonzilez et al. Durkan Kuschner et al. Tetro et al. Gellman et aI. Szabo et al. Mossman et al. Gunnarsson et al. HelIer et al. Ghavanini et al. Katz et al. De Smet, et al. Buch-Jaeger et al. Katz et al. de Krom et al. 1990 50 0.48 0.45 0.49 0.48 0.87
Sens = Sensitivity; Spec = Spccificity; 'PV = Positive p d c t i v c vduc: 'PV = Ntgativc prcdictive value: LR = Lihlihood d o t Likelihood ncio was noi reporteci. but cdculated fmm uristing scnsitiviiy and specifiàty values reportcd in the tirtnnirt.
TabIe 2.3 Tinel's sign article summary
Reference Year Handc Sens Spec 'PV 'PV LRP
De Smet, et al. Williams et al. Gonzalez et ai. Tetro et al. Mossman et al.
Szabo et al. Durkan Heller et al. Ghavanini et al. Katz et al. Katz et al. Stewart et al. Gunnarsson et al. Kuschner et al. Buch-Jaeger et al. 1994 172 0.42 0.63 1.14 de Krom et al. 1990 50 0.33 0.68 0.35 0.53 1 .O3 Sens = Scnsitivity; Speç = Spccificity: 'PV = Postcive prcdictivc vduc: PV = Negativc prcdictive value: LR = Likclihoad ntio t L tkc l ihd ratio w u not rcponcd. but cdcuhted from existing xnsitivity md specificity vdues rcponcd in the liteniurc.
Aside from Phalen's test, various forms of compression tests thar position direct
manual pressure on the carpal tunnel have recently been presented in the literature as
alternative or cornplementriry types of provocative tests in diagnosing carpal tunnel
syndrome. Table 1.4 provides a summary of articles that examine the diagnostic efficacy of
pressure provocative test and carpal compression test. Pressure provocative test (Kaul et al.,
2001 ; Williams et al.. 1992; Novak et al.. 1992) or carpal compression test (Durkan, 199 1;
1994: De Smet et al., 1995; Fenl et ai., 1998; Gonzalez et al., 1997: Szabo et al., 1999; Tetro
et al., 1998) provoke symptoms in the dismbution of the median nerve. They are considered
a valuable alternative for patients suffering frorn restricted range of wnst flexion and
therefore not capable of performing Phaien's test (Gonzalez et ai.. 1997: Williams et al.,
1992). Durkan ( 199 1 ) conducted the original study on the carpai compression test adopting
both a manometer bulb with pressure equivalent CO 150 mm Hg as well as direct thumb over
the carpal tunnel. The results indicated high sensitivity (87%) and specificity (90%). but the
article did not clearly outline which technique was responsible for these accuracy values.
Gonzalez Del Pino and colleagues (1997) repeated the study using the direct thumb
technique with favorable results (sensitivity=87%). However. this study did not incorporate
nerve conduction studies as the diagnostic criteria. Gonziiez Dei Pino and colleagues ( 1997)
relied one of three possible criteria including i) hand symptoms and weakness of the
abductor pollicis brevis muscle. i i ) positive 2-point discrimination or i i i ) resoived symptoms
following surgery rather than electrodiagnosis. Furthemore. the results of the carpal
compression test and the confirmed diagnosis were not independently blinded during the
clinical trial. Fertl and colleagues (1998) repeated the work of Durkm adopting the direct
thumb pressure method in a group of electrodiagnostic confirmed CTS patients and controls
subjects. The carpal compression test indicated favorable results as ;in independent test
(sensitivity=83%. specificity=92%) and in combination with Phalen's test (sensitivity=92%,
specificity=92%). The pressure provocative test is similar to the carpal compression test
whereby it applies direct pressure over the carpal tunnel. However. the exact pressure
applied is variable in the carpal compression test, while the pressure provocative test applies
a standard pressure (100 or 150 mm Hg) using a sphygmomanometer. Williams et al.
(1992) reported high sensitivity and specificity values at pressures of 100 mm Hg (908,
100%) and ISO mm Hg ( 1004, 97%). respectively. Furthemore, the pressure provocative
test indicated a faster provocation of syrnptoms (Le., mean of 9 seconds) compared to
PhaIenTs test. Williams and colleagues (1992) conduded that pressure provocative test
could demonstrate an accurate diagnosis of carpal tunnel syndrome either independently or
in combination with Phalen's test and Tinel's sign. Similady. Novak et al. (1992) found the
pressure provocative test using direct thumb pressure and Phalen's test tend to be more likely
to occur together than separate. However. the sensitivity measures reponed in both studies
Vary significantly and therefore warrant funher review. The pressure provocative test is a
simple and objective clinical test that requires expanded examination to determine its
diagnostic e fficac y.
Table 3.4 Pressure provocative test article summary
Reference Year Hands Sens Spec 'PV 'PV LRt. - --
Williams et al. 1992 60 1 .O0 0.97 1 .O0 33.3 Durkan 1994 55 0.89 0.96 22.3 Gonzilez et al. 1997 300 0.87 0.95 17.4 Tetro et al. 1998 114 0.75 0.93 0.9 1 0.79 10.7 Fertl et al. 1998 67 0.83 0.92 0.95 0.77 10.4 Durkan 1991 8 1 0.87 0.90 8.70 Szabo et al. 1999 150 0.89 0.66 0.12 0.99 2.62 Kaul et al. 200 1 369 0.55 0.68 0.70 0.53 1.72
0.53 0.62 0.67 0.47 1.39 Ghavanini et ai. 1998 132 0.48 0.62 1.26 De Smet, et al. 1995 163 0.62 0.33 0.8 1 0.17 0.93 de Krom et al. 1990 50 O. 10 0.07 0.40 0.48 0.1 1 Sens = Sensitivity; Spec = Sptcificity: 'PV = Positive pdic t ive value: 'PV = Ncgative prtdictivc value: LR = L i k d i h d ntio t Ltkclihood ntio was not reportcd. but dculatcd h m cxisting stnsirivity and specificity values rtponed in the 1iter;in.u~.
2.6.2.3 Sensibility tests
Alterations in hand sensation are typically the initial cornplaints from patients with
rnedian nerve compression (Szabo et al.. 1984). However. sensory tests that are not properly
defined or poorly executed c m produced false-positive and false-negative results
(MacDemiid, 199 1). Some sensory examination tests such as vibrometry are considered
expensive (Katz et al., 1990a: MacDermid, 1991), while Semmes-Weinstein monofilament
test is considered time consuming and less reliable under distracting conditions (MacDermid
et al.. 1992). Nevertheless. sensibility tests such as vibrometry and Semmes-Weinstein
monofilament have demonstrated strong inter-rater agreement and accuracy compared with
other clinicai test in diagnosing carpal tunnel syndrome (MacDermid et al.. 1397). Static
and moving 2-point discrimination has also been demonstrated to be accurate in diagnosing
CTS. However. this sensibility test is most valuable in patients with severe compression of
the median nerve (Gelberman et al., 1983).
A new clinical sensibility test called the Ten test has demonstrated promise in
detecting decreased finger sensibiiity and is neither expensive or time consuming (Strauch et
al., 1997). The test is administered by initially establishing a "reference body part" by the
examiner lightly stroking their finger on the subject's non-symptomatic hand. If the patient
demonstrates bilateral symptoms and there are no normal digits. then the examiner uses the
patient's lip. cheek or bridge of the nose as the reference body part (Strauch et al., 1997).
When the reference body part is selected, the examiner instructs the patient that "this is the
best that can be felt and is equivalent to a score of 10 on a scale of 1 to 10". The test is then
administered by lightly stroking each finger individually on the symptomatic hand's palmar
side and the reference body part simultaneously. Light stroking continues until the patient
had responded with respect to "how the test area compares" to the reference body part. This
procedure is repeated for each of the five fingers, with the patient reporting a sensibility
score from I to 10 (Strauch et al., 1997). To date, the accuracy of the Ten test has not been
completely established. However. the Ten test has demonstrated excellent interobserver
reliability (rd.91) (Strauch et al.. 1997). Correlation analysis demonstrated a high degree
of association between the Ten test and Semmes-Weinstein monofilament test. However,
Strauch et al. (1997) did not biind the Ten test results from the Semmes-Weinstein test.
Furthemore. Strauch and colleagues used a small sample size of 49 patients suspected of
carpal tunnel syndrome. Similarly. Patel and Bassini ( 1999) found the Ten test to be a valid
sensibili ty test cornpared to the Weinstein Enhanced Sensory Test. static and moving 2-point
discrimination. Comparable to Strauch et al. (1997), the Ten test results were not blinded
from the Semmes Weinstein test, which was used to confirm abnormal finger sensibility.
Despite the simpiicity and repeatability of this clinical test, funher research is required in
detemining its overall efficacy, particularly in diagnosing carpal tunnel syndrome.
2.7 Combined influence of clinical tests
Since most diagnostic tests are less than perfeci, a single test is frequently
insufficient in making an unequivocal diagnosis (Knapp and Miller. 1992). Hand surgeons
often utilize a number of clinical tests in their diagnostic algorithm. A growing number of
studies have exarnined the efficacy of a combined battery of tests (Szabo et al., 1999; Borg,
1988; Katz et al., 1990a: de Krom et al., 1990; Novak et al., 1992; Buch-Jaeger et al., 1994;
Gerr et al.. 1995; Gunnarsson et al., 1997). Sackett and colleagues (1991) suggest that it is
"clinically nonsensical" to make a diagnostic decision based on the accuncy of a single
clinical test. To date. Buch-laeger and Foucher (1994) have conducted the Targest siudy in
determining the utility of 1 1 clinical tests. independently and combined. in diagnosing carpal
tunnel syndrome. Combined results of Phaien's test and symptom reporting elevated the
sensitivity of Phalen's test from 58% to 62%. while specificity remained relatively stable.
However. this interpretation may be biased since symprom reponing was initially used in the
diagnosis of these patients. Fletcher and colleagues (1996) state that sensitivity and
specificity should not be considered valid indicaton when the clinical test is adopted as a
component of the criterion standard. Nevertheless, combining the responses of a cluster of
clinicai tests, independent of the diagnostic outcome. can be an effective assessrnent of its
va!idity and clinical usefulness (Sackett et al.. 199 1). Efficacy of clinical tests in diagnosing
carpal tunnel syndrome has practical importance since electrodi;ignostic findings may not be
available. especially in some epidemiologic settings (Rempel et al.. 1998). The efficacy of a
cluster of clinical tests in not completely undentood and therefore research is necessary in
determining the combined influence in diagnosing carpal tunnel syndrome.
2.8 Treatrnent
Carpal tunnel syndrome can be treated non-operat ive y or surgicall y. Initial1 y,
patients should be treated for underiying medical conditions. such as rheumatoid anhritis,
hypothyroidism or diabetes mellitus. These conditions have been identified as contnbuting
factors in eliciting CTS symptoms (Szabo and Madison, 1992). Mild symptoms or an
equivocal diagnosis are initially treated conservatively by suggesting an abstinence from
activities that provoke symptoms. such as repetitive work habits or splinting the wnst in
conjunction with job modifications (Ditmars, 1993). Splinting with the wrist in neutral
position maximizes carpal tunnel space and reduces compression on the median nerve
(Sailer. 1996). Gelberman and colleagues ( 198 1 ) reported increased carpal canal pressure
due to wrist flexion and extension and prescnbed resting the wrist in a neutral position.
Mahoney and Dagum (1992) suggested splinting at night to contend with noctumal
wakening resulting from increased pressures on the median nerve. Anti-inflarnmatory drugs
provide minimal effect in reducing the swelling of the tenosynovium and decreasing
symptoms (Tubiana. 1990). Ditmars (1993) suggests prescribing 200 mg of vitamin B6 per
day until symptoms are decreased and then reduce to 50 mg daily for maintenance.
However. Schaumburg et al. (1983) cautions that excessively high doses (e.g., 300 mg daily)
are counterprodactive, causing sensory neuropathy. Corticosteriod injections into the carpal
tunnel is used in an attempt to reduce non-specific tenosynovitis. which is presumed to be
responsible in many cases for the increased pressure on the median nerve. Irnrnediate
symptomatic relief is common. but is often transitory with symptoms recumng in 18 months
following injection (Gelberman et al., 1980). Injection directly into the median nerve is
undesirable as permanent damage to the median nerve can result (Fredenck et al.. 1992).
Ditmars (1993) suggests injecting at the level of the proximal wrist crease between the
palmaris Longus and flexor carpi ulnaris tendons. Finally . stretching and strengthening
exercises are effective in providing a nerve gliding mechanism whereby the median nerve in
the carpal canal moves more freely from its traditional position and break-up fibrous
adhesions (Mooney, 1998).
Surgical intervention is recommended if the patient does not respond to conservative
treatment or is diagnosed with severe carpal tunnel syndrome (Ditman. 1993).
Furthemore. surgery is recomrnended for patients suspicious of carpal tunnel syndrome
with a positive nerve conduction evaluation. However, successfu1 cessation of symptoms
has been reponed in patients who dernonstrated a normal electrophysiological examination
(Finsen and Russwurm, 2001; Grundberg. 1983). Moreover. a national survey of hand
surgeons indicated that only 33% rely on nerve conduction studies (Duncan et al.. 1987).
Endoscopie and open carpal tunnel release are two common procedures used to relieve
pressure on the median nerve in the carpal tunnel by making a longitudinal incision and
dividing the transverse ligament (Szabo and Madison. 1992). Proponents of endoscopic
surgery daim less pst-operative discomfon, quicker recovery of strength. and earlier retum
to work and daily activities (Erdmann, 1993). Furthemore. Chung and colleagues (1998)
concluded that endoscopic surgery is more cost-effective compared to open release in
treating carpal tunnel syndrome. However, Ditmars (1993) and Evans ( 1 994) suggest that
inexperienced surgeons should perforrn a carpal tunnel release using the open procedure
since the learning curve will be met with inevitable nerve injuries.
Traditional post-operative care requires a gauze dressing and volar splint with the
wrist in neutral position (Szabo and Madison, 1992) or at 20 degrees extension (Ditmars,
1993) for several weeks. tinger motion is advocated immediately following surgery. Cook
et al. ( 1 995) compared surgical recovery of a random sarnple of patients with restricted
(volar splint) and unrestricted (soft dressing) wrist rnobility. Active mobilization patients
demonstrated a faster recovery and earlier return to work compared to patients splinted for
two weeks. Furthemore, patients who were splinted experienced increased pain and scar
tendemess in the first month after surgery. However, no differences in the incidence of
complications. including bowstringing of the tendon or entrapment of the median nerve in
scar tissue, were dernonstrated between the groups. Patients with mild to moderate carpal
tunnel syndrome demonstrate the most successfuul post-operative recovery. A lower success
rate is indicative of patients with severe carpal tunnel syndrome and is attnbuted to
permanent nerve damage due to neglect of treating the condition (Mahoney and Dagum,
1 992).
2.9 S ystematic literature review of diagnostic studies
A specific approach to the practice of medicine and clinical epidemiology in the past
10 years is referred to as "evidence-based medicine" (Sackett et al ., 199 1 ). It is recognized
that clinicians and researchers need to base their diagnostic decisions and actions on
appropriate evidence from the hedth care literature. For the most part. information
searching is subject or content directed. A systematic review was conducted on CTS
diagnostic literature, which incorporated a Boolean search of Index Medicus. PubMed and
CMAHL frorn 1970 to 200 1. The peer reviewed literature search focused on studies that
examined the efficacy of Tinel's sign, Phalen's test, pressure provocative test and the Ten
test used to diagnose carpal tunnel syndrome. Phalen's test, Tinel's sign and the pressure
provocative tests were selected because they are three commonly utilized clinical tests
identified in the literature that have demonstrated inconsistent accuracy, and therefore
warrant further investigation (Buch-Jaeger et al.. 1994; Novak et al.. 1992). Furthermore.
the Ten test was selected based on the fact that it is a reasonabiy novel clinicai test requiring
expanded research in determining a positivity criterion as well as overall efficacy in
diagnosing carpal tunnel syndrome (Strauch et al.. 1997).
Medicd subject heading (i.e., MeSH) tems selected in capturing the most
appropriate diagnostic literature included carpal tunnel syndrome. diagnosis, efficacy,
accuracy, validity, sensitivity. specificity, positive predictive value, negative predictive
value. likelihood ratio and receiver-operator characteristic (ROC) curve. Funhermore.
articles were also selected from the references listed in the initial articles based on their
relevance. The 27 articles selected cover English-language literature for the period frorn
1978 to 2001. Appendix 1 provides a complete chart of the individual studies with specific
reference to the clinical tests measured. reference standard. blinding, patient spectrurn and
diagnostic outcome.
2.9.1 Criteria for study evaluation
These articles were evaluated on a Cpoint rating scale (Sackett et al.. 199 1 ) based on
specific methodologicai questions pertaining to the appraisal of journal articles that
proposed to validate clinical tests in diagnosing carpal tunnel syndrome. The 27 articles
selected were evaluated based on the following criteria: i) was there an independent. "blind
cornparison? ii) was the acceptable "gold standard for diagnosis of this disorder or
condition used? iü) did the patient sample include an appropriate spectrurn of mild. and
severe, treated and untreated disease, plus individuals with different but commonly
confusing disorders? iv) was the "utility" of the test determined? Table 2.5 outlines the
results of a systematic review designed to appraise scientific methods of the aforementioned
articles used to validate efficacy of clinical tests in the diagnosis of carpal tunnel syndrome.
2.9.2 Blind cornparison
An important criterion in determining the accuracy of a diagnostic tool is whether the
clinical test of interest and reference standard were assessed independently of one another.
Sackett et al. (1991) outlines the importance of conducting a clinicd test independent of a
gold standard examination in order to avoid conscious awareness of the diagnostic outcome
prior to conducting the clinical examination. Despite the importance of a blinded trial to
avoid a diagnostic suspicion bias. only 302 (8 of 27) of the articles examined. reported an
independent examination of clinical tests from the electrodiagnostic results.
2.9.3 Acceptable gold standard
As was mentioned previously, the question as to whether there is an acceptable gold
standard test in diagnosing carpal tunnel syndrome is still somewhat debated by medical
professionals. Rempel and colleagues (1998) refer to the gold standard for CTS as being
"imperfect" due to the inconsistency between signs and symptoms of this condition.
Nevenheless. a general consensus of physicians and researchers alike recognize the
combination of a positive nerve conduction evaluation with symptoms. such as pain.
numbness. tingling or decreased s e d o n in the median nerve distribution OF the hand. as
the most accurate information for diagnosing CTS. Therefore, this composite cnterion was
used as the recognized gold standard for this systematic review. Twenty of 27 articles
(748) reviewed incorporated an appropriate reference standard in diagnosing their patients.
S peci fical1 y, 1 5 studies emplo yed nerve conduction, 3 implemented electrom yograph y and 2
adopted nerve conduction and electromyography to confirrn a CTS diagnosis. The
remaining studies (7) relied on a combination of symptoms and clinicd provocative tests
(Strauch. et al., 1997; Novak et al.. 1992: Pater and Bassini, 1999: Williams et al.. 1992). a
choice of nerve conduction, positive response to cortisone injection or surgical open release
(Katz et al.. 1990b: Gonzalez Del Pino et al.. 1997) or not reported (Kuschner et al.. 1992).
2.9.4 Patient spectrum
The strength of a diagnostic test often lies in iü ability to distinguish between the
disease of interest and other similar conditions (Sackea. et al.. 1991). Therefore. a large
spectrum of patients including those suffering from conditions similar to carpal tunnel
syndrome such as cervical radiculopathy (Anto and Aradhye 1996) is important. especially
when their therapies significantly differ. The studies reviewed predominantly exarnined
patients suspected of carpal tunnel syndrome or a combination of confirmed CTS patients
and control subjects. Five articles failed to provide an appropriate spectrum of subjects in
their studies. insufficient sample size was demonstrated by Koris et al. (1990) (21 CTS
patients and 3 control subjects). Mossman et al. (1987) (27 suspect CTS patients), Strauch et
al. ( 1997) (49 patients) and Williams et al. ( 1992) (30 CTS patients and 30 controI subjects).
Meanwhile. Katz et al. (1990b) indicated an exaggented prevalence rate of 88%. An
excessiuely high prevaience rate can create a bias by increasing the probability of over-
estimating positive predictive values and under-estimating negative predictive values.
2.9.5 Diagnostic utility
Utility is defined as a numericd estimate of the wonh or value of a given outcorne
(Knapp & Miller, 1992). More specificdly, diagnostic utility of a clinicd test is important
to establish as it determines whether the patient is better off for having undergone the
ciinicd test. UtiTity is dependent on the practicdity of the ciinicaI test. diagnostic accuracy
as well as concems for costs and benefits (Sackett et al.. 1991). The weight of evidence
conceming diagnostic utility for this systernatic review considered the accuracy of the
clinical tests since the ease of technically administrating the test protocols as well as
discornfort and expense of conducting the clinical tests is considered minimal (Katz et al.,
1990b). Ali studies reviewed incorporated descriptive evidence (e.g.. sensitivity, specificity,
positive and negative predictive values. false-positive and false-negative rates) or analyticai
statistics ( McNemar chi-square. Kappa statistic, Pearson product moment correlation or
Spearman rank correlation) to evaluate the accuracy and diagnostic utility of their clinical
tests. Furthemore, all but three studies (Novak et al.. 1992: Strauch et al., 1997: Patel and
Bassini. 1999) incorporated both descriptive and analytical evidence. Strauch et al. (1997)
and Patel et al. (1999) attempted to evduate the accuracy of the T'en test by incorporated
analytical statistics. However, both studies were not recognized for establishing diagnostic
utility since they did not report sensitivity and specificity. To date. the Ten test sensibility
andog scale has not been structured CO include a positivity criterion. Therefore, the âbility
to measure sensitivity and specificity is unattainable. The studies by Strauch et al. (1997)
and Patel et al, (1999) were intended to establish reliability and validity of the Ten test in
evaluating abnormal finger sensibility.
2.9.6 Sumrnary of systematic literature review
The majority of diagnostic articles reviewed herein failed to meet the standard
criterion to accurately vaiidate clinical tests. Overall, only seven articles (26%) satisfied the
cnteria and received a perfect 4-point rating. Eleven studies were given a 3-point rating; al1
of which negIected to biind the chicai examiner from the results of the electrodiagnosis.
Six articles received a 2-point rating and two articles received a 1-point rating for including
an appropriate patient spectrum (Patel and Bassini. 1999) or reporting diagnostic utility
(Williams et al.. 1992). Findly. Strauch and colleagues (1997) received a O-point rating for
failing to meet any of the four standard criterion.
2.10 Surnrnary
Carpal tunnel syndrome is currently the most common peripheral neuropathy found
in the medical community. Not surpnsing, Index Medicus reports over 4200 epidemiologic
and clinical documents on the etiology. diagnosis, treatment and prognosis o l c ~ p a l tunnel
syndrome. Aside from the medical conditions associated with carpal tunnel syndrome, the
literature has indicated that various idiopathic factors. including persona1 characteristics and
occupationai repetitive wnst activity. are strong predictors of CTS. Numerous conservative
and surgical modaiities are commonly used in treating this compression neuropathy.
Surgical intervention is typically reserved for patients demonstrating persistent moderate to
severe symptoms, with or without a positive electrophysiological examination (Ditman,
1993)-
Rempel and colleagues (1998) recommend an electrophysiological examination
allied with a careful symptom assessrnent (i.e.. Stirrat symptom questionnaire) as the most
effective method of confirming a diagnosis and therefore should be considered the standard
by which al1 clinical tests are compared. Furthemore, they advocate the use of clinical tests
in conjunction with classic or probable syrnptoms in diagnosing CTS (Rempel et al.. 1998).
A systematic review of the literature demonstrated numerous methodologicd limitations in
studies specifically concerned with validating clinicd tests in diagnosing carpai tunnel
syndrome. These inconsistencies create a diagnostic conundrum for the hand surgeon
attempting to make appropriate decisions concerning the well being of their patients.
Therefore. future investigations that adopt proper methodological criteria. including an
appropriate patient spectmm, independent blinding of the examiner(s) and adoption of a
recognized gold standard for confirming a diagnosis. will enhance the quality of research
required in determining the efficacy of C T S clinical tests. Furthemore. this would allow
surgeons the benefit of making judgements based on accurate evidence from health care
li terature.
Table 2.5 Systematic review of clinicai tests for diagnosing carpal tunneI syndrome
Reference Rating Summary of diagnostic articles
AGS
Buch-Jaeger et al. ( 1994)
de Krom et al. (1990)
De Smet. et al. (1995)
Durkan (1991)
Durkan (1994)
Fertl et al. ( 1998)
Gellman et al. ( 1986)
Ghavanini et al. ( 19%)
Gonzilez Del Pino et al. ( 1997)
Gunnarsson et al. ( 1997)
Heller et al. ( 1986)
Katz et al. ( 1990a)
Katz et al. ( 1 99Ob)
Katz et al. ( 1990~)
Katz et al. ( 199 1 )
Kaul et al. (2001)
Koris et al. (1990)
Kuschner et al. ( 1992)
Mossman et al. ( 1987)
Novak et al. ( 1992)
Patel et al. ( 1999)
Seror ( 1988)
Stewart et al. ( 1978)
S trauch et al. ( 1 997)
Szabo et al. ( 1999)
Tetro et al, ( 1998)
Williams et al, ( 1992) El d
PS = patient spectntm; BT = blinded inal: XGS = acceptable gold siuidard; DU = diagnosac u t i l i l
CHAPTER rn
METHODOLOGY
3.1 Introduction
The literature regarding the diagnosis of carpal tunnel syndrome using clinical tests
have clearly demonstrated a need to implement well-controlled clinical epidemiological
standards. The main purpose of this study was to determine the efficacy of four clinical
tests. including Tinel's sign. Phalen's test. the pressure provocative test and the Ten test. in
the diagnosis of carpal tunnel syndrome.
3.2 S tudy sample
A sample of incident cases suspected of suffering from carpal tunnel syndrome and
referred for further assessment to a plastic surgeon at the Thibert Surgical Clinic (Thunder
Bay) and The Mount Sinai Hospital (Toronto) formed the base of subjects for this study.
Inclusion criteria allowed only subjects 2 18 yean of age based on the hand syrnptoms
outlined in the refemng physician's "referral letter" such as pain. numbness. tingling,
decreased sensation andor nocturnal pain in the hand. Subjects excluded from the study
included those that had previous nerve conduction studies or surgery of the carpal tunnel.
Appendix 2 outlines the sarnple size estimation based on an initial population size
(N) of 500 accessible subjects. which represented the approximate number of patients with
symptoms in the hand referred to Dr. Mark Thibert (N=200) and Dr. Nancy McKee (N=300)
over the course of one year. Expecred proportions for prevalence (0.33), sensitivity (0.62),
42
specificity (.33), positive (.8 1) and negative (. 17) predictive values were selected from De
Smet et al. (1995) for a consemative estimation of sarnple size. Based on the expected
proportions from this study, sample size was estimated at 178 subject han& considenng a
95% confidence level (a= 0.05) and maximum error of 5%.
3.3 Research design
The following steps were implemented in the recniitment of subjects and distribution
of testing material at both The Mount Sinai Hospital and Thibert Surgical Clinic. In order to
solidify administrative efficiency of the protocol steps and avoid potential problems during
the clinical triai. the surgeon. surgeon's administrative assistant and physiatrist were briefed
as to the logistic procedures necessary in conducting the research testing methods (Appendix
4). AI1 subjects were informed as to the nature of the study during initial contact with the
surgeon by reading a research information sheet ( Appendix 5). Subjects were asked to dlow
clinical examination and electrodiagnosis of s ymptomatic and asymptomatic hands.
Subjects agreeing to participate were asked to complete a letter of consent (Appendix 6).
Upon completion of the consent form. subjects were instructed to cornplete a demographics
ques t ionnak ( Appendix 7) and S tirrat's self-adrninistered s y mptorn reporti ng questionnaire
(Appendix 8). These forms were immediately retumed to the surgeon's office administrator
in order to blind the surgeon from the results of the symptom reporting questionnaire. The
subject was then required to undergo an examination of al1 clinical tests. including Phalen's
test, the pressure provocative test. the Ten test and Tinel's sign on both hands by the
attending surgeon. ResuIts from the clinical tests were recorded (Appendix 9) and retumed
by the surgeon to the office administrator to complete the subject study file. Al1 snidy files
were stored in a locked cabinet until delivery by the office adrninistrator to the research
principle investigator.
Subjects rehirned for nerve conduction exarninations, including segmental sensory
nerve conduction and 7-cm median nerve motor distal latency to both hands by the attending
physiatrist. within two weeks of the clinical examination. The attending physiatrist was
instructed not to perform any clinical tests prior to the nerve conduction evaluations.
Furthemore. the physiatnst was blinded to the results of the surgeon's clinical examination
and Stirrat's symptom reporting questionnaire. Results from the nerve conduction studies
were recorded ( Appendix 10).
3.4 Stirrat's symptom reporting questionnaire
The subjects were instructed to cornplete a self-administered hand symptom diagrarn
for both hands by drawing in the appropriate symbols for pain, tingling, decreased sensation
and numbness on the hand diagram. which depicts dorsal and palmar views of both hands
and m s (Appendix 8). The following rating system, as outlined by Katz et al. (1990b),
was used to assess the subjects hand symptom diagrarn. A classic carpal tunnel rating was
indicated if the subject had tingling, numbness. or decreased sensation with or without pain
in at least two of either the index, middle or ring fingers. A probable rating replicated
classic symptoms, except paimar symptoms, was included unless confined solely to the
ulnar aspect. A possible rating occurred when tingling. numbness. or decreased sensation
was present in one of the index. middle or ring fingers. An unlikely rating was indicative of
the subject with no symptoms in the index, middle or ring fingen (Ka& et al., 1990b). The
principle investigator evaluated al1 subject diagrams independently in order to blind the
surgeon as to the classification of each subject. CIassification of each hand diagram was
recorded as either classic. probable, possible or unlikely CTS in Stirrat's Symptom Response
Diagnostic Report (Appendix I 1).
3-5 Clinical examination
Four clinical tests were administered on both hands in a systematic (non-randomized)
order. including i) Phalen's test. ii) the pressure provocative test. iii) the Ten test and iv)
Tinel's sign by the attending surgeon. A one minute rest interval was allowed between each
clinical test in order to control for residual syrnptoms that may have lingered as a result of
provoking the median nerve. Residual symptoms provoked from a clinical test that
exceeded beyond the one-minute interval were identified and controlled for in the statistical
analyses.
3.5.1 Phalen's test
The surgeon passively placed the subject's wrist in a paimar flexion position. This
position was held for a maximum 60 seconds or until pain or paraesthesia was elicited. A
positive test was considered if symptomatology (i.e., numbness, tingling or pain) occurred
within a 60-second time period in the median nerve distribution of the hand (Williams et al.,
1992; Novak et ai., 1992; Gonzalez Del Pino et ai., 1997). The test was considered negative
if the subject remained asymptomatic in the distribution of the median nerve after a 60-
second period. This test was conducted on both hands, whereby the symptomatic hand was
evaluated initially in the case of a unilateral symptomatic subject.
3.5.2 Pressure provocative test
The subject was instructed to supinate the forearm and rest the wrist in neutral on the
examination table. An infant sphygmomanometer cuff was inflated to 100 mm Hg over the
median nerve at the crease of the wrist. Direct thumb pressure was then applied over the
subject's transverse carpal ligament by the surgeon to increase pressure to 150 mm Hg. A
stopwatch was held in the surgeon's other hand and pressure was held constant for one
minute. The test was considered positive if symptomatology (i.e.. numbness. tingling or
pain) occurred within a 60-second time period in the median nerve distribution of the wrist
or hand (Williams et al.. 1992). The test was considered negative if the subject remained
asymptomatic in the distribution of the median nerve following a 60-second period. This
test was conducted individually on both hands. The symptomûtic hand was evaluated
initially in the case of a unilateral symptornatic subject.
3.5.3 Ten test
The surgeon initially established a "reference body part" by lightly stroking a finger
on the subject's non-symptomatic hand. If there are no normal digits as in the case of a
subject with bilaterai symptoms. then die surgeon used the subject's lip, cheek or bridge of
nose as the reference body part (Strauch et al.. 1997). When the reference body part was
selected. the surgeon instructed the subject that "this is the best that cm be felt and is
equivalent to a score of 10 o n a scale of 1 to 10". The test was then recorded by lightly
stroking each digit individually on the syrnptomatic hand's palmar side and the reference
body part sirnultaneously. Light stroking continued until the subject had responded with
respect to "how the test area compared to the reference body part. This procedure was
repeated for each of the fïve digits, with the subject reporting a score from 1 to 10 (Strauch
et al., 1997). This test was conducted individuaily on both hands. The symptomatic hand
was evaluated initially in the case of a unilateral symptomatic subject. To date. the validity
of the Ten test has not k e n complete l y established. A secondary objective of the current
study was to establish positivity criterion for the Ten test in diagnosing carpal tunnel
syndrome.
3.5.4 Tinel's sign
The test was performed by percussing firmly the subject's extended wrist, over and
immediately proximal to the carpal tunnel at the distribution of the median nerve with a
Queen's Square tendon harnmer (head diameter 5.2 cm: head width I cm: shaft length 38
cm; head weight 90 gram: Almedic. St. Laurent, QC: Item #: AI-126} (Mossman and Blau,
1987). Tapping was performed three consecutive times. A positive test was considered
when tingling was felt in the fingers of the rnedian nerve distribution with each successive
tap. The test w u considered negative if the subject remained asymptomatic following any
tap. If a test was equivocal (Le., tingling following one or two taps). the subject was given
one minute to recover before the test was repeated by conducting an additional three taps
(Kuschner et al.. 1992). This test was conducted individually on both hands. The
symptomatic hand was evaluated initially in the case of a unilateral symptomatic subject.
3.6 Electrodiagnostic evduation
Limb temperature was monitored using an electncal thermometer probe (TRI-R
Instruments; Rockville Centre. NY) and controlled between 32 and 35°C by ninning wam
water over the subject's wrist for each examination (Imaoka et al.. 1992). The attending
physiatnst administered the nerve conduction studies to both hands beginning with the
segmental stimulation technique and followed by the 7srn motor disial latency study. The
symptomatic hand was evaluated initially in the case of a unilateral symptomatic subject.
The segmenta1 nerve conduction evaluation was conducted by secunng an electrode on the
anterior side of the forearm, k m proximal to the distal crease of the wrist. A recording
ring electrode was piaced 14-cm distal to the stimulating electrode on the middle finger. A
square wave electric stimulus was used at each stimulation site for a duration of O. 1 m., a
level of stimulation that causes little pain to the subject (Imaoka et al.. 1992). The electrode
was advanced in 1-cm increments towards (antidromic) the hand. Sensory latency values
were recorded at each increment dong the midline of the third metacarpal. The electrode
was advanced antidromic until 6-cm distal to the wrist crease was attained. Nine sensory
latency values in total were recorded from 2-cm proximal to 6-cm distal to the distal wnst
crease in the electrdiagnostic report (Appendix 10). The subject was considered to have a
positive electrodiagnostic evaluation if at least one incremental sensory value (difference
between the peak latency for successive sensory nerve action potentials) was 2 0.4 ms.
(Seror, 1994; Nathan et al., 1988). The 7-cm motor distd latency study was perfomed by
securing surface recording electrodes over the thenar eminence and thumb and stimulation
of the median nerve with surface electrodes 7-cm proximal io the distal wrist crease. Again,
a square wave electric stimulus was used on the stimulation site for a duration of O. 1 ms., a
levcl of stimulation that causes little pain to the subject (Jackson and Clifford, 1989). The
median nerve motor distai latency value was recorded in the electrodiagnostic report
(Appendix 10). The subject was considered to have a positive electrodiagnostic evaluation if
the motor distal latency was 2 4.0 ms. (Jackson and Clifford. 1989).
3.7 Data management
Completed data forms. including: i) Demographics Questionnaire, which included
symptorn type and severity (Appendix 7). i i ) Stirrat's Symptom Reponing Questionnaire
( Appendix 8). i i i ) Surgeon's Clinical Report (Appendix 9) and iv) Electrodiagnostic Report
(Appendix 10). were convened to a numerical fomat that could be analyzed statistically.
Data entry was conducted by the principle investigator and involved defining the variables.
data coding as well as checking and cleaning the database. Data was entered into a
spreadsheet of the statistical program NCSS 2000 (Hintze. 1998).
3.7.1 Defining the variables
Each variable was identified and provided a name. The variable name was
subsequently used tu identify variables in the database and for analysis. Appendix 12
presents the names chosen for each variable from the four data forms. Each variable was
given an abbreviated name that was seif-explanatory for each variable measured. For
exarnple. "prehand" pertained to the question "Please circle the hand that you predominantly
use for everyday activity"? This abbreviated format ailowed for the data analysis output to
be more clearly read and undeniood.
3.7.2 Data coding
Data was coded with respect to level of measurement. formatting and conditional
outcomes ( Appendix 1 2). Level of measurement included nominal, ordinal, interval and
ratio type data. Consistency in coding was rnaintained for all dichotomous measures. For
example. the forrnatting of "yes" and "no" responses were consistently coded as " 1 " and "2".
respectively. Coding the gold standard variable was an example of creating a new variable
based on conditions of existing variables. A positive electrodiagnosis combined with a
"classic" or "probable" rating from Stirrat's syrnptom reporting questionnaire was required to
classify a diagnosis for carpal tunnel syndrome. The classi fied diagnosis (variable name =
"CTS") was generzted using a conditional "and" statement. Therefore. CTS positive subject
hands were identified as classic or probable on Stirrat's symptom reporting questionnaire
(i.e., SR*?: classic= l and probable-2) and positive median nene latency from sensory (ie.
SCV positive= 1 ) or motor (Le.. MDL positive= l ) electrodiagnosis. Classified CTS negative
subject hands represented al1 remaining electrodiagnostic and symptom reporting outcomes.
3.7.3 Data checking and cleaning
Ali subject files were re-exiunined io verify the recorded information. Furthemore, a
range of pemissible values were assigned for al1 nominal and ordinal data. The purpose of
defining variable ranges was to guide data editing, whereby values outside the defined range
were checked for accuracy. Finally, frequency distributions and histograms were conducted
on dl discrete and continuous variables, respectively, in order to identify "outlier" or
erroneous data. The purpose of the data cleaning process was to validate al1 information
prior to the final statistical analyses.
3.8 Declaration of the gold standard
The gold standard was based on conditions of existing variables as previously
outlined in the data management. A positive electrodiagnosis combined with a "classic" or
"probable" rating from Stirrat's s ymptom reporting questionnaire was required to classi fy a
diagnosis for carpal tunnel syndrome. Therefore, CTS positive subject hands were identified
as classic or probable on Stirrat's symptom reporting questionnaire and positive median
nerve latency from sensory or motor electrodiagnosis. Classified CTS negative subject
hands included those with "possible" or unlikely" reported symptoms. regardless of their
electrodiagnostic findings. Furthemore, subjects were also classified negative CTS if they
reported classic or probable symptorns with a negative nerve conduction examination
(Rempel et al.. 1998).
3.9 Statistical Analyses
Statistical analyses of the data were evaluated using NCSS 2000 (Hintze, 1998) and
webulatorD (Montelpare and McPherson, 1999) statistical programs. A number of statistical
procedures were used to evaluate the data collected in this study. The statistical analyses
were divided into five components, including: i) subject derno,gapphic and symptom
reporting profiles, ii) electrodiagnostic evaluation, iii) ROC curve techniques for
establishing a positivity criterion of the Ten test. iv) diagnostic efficacy of independent and
combined clinical test and v) estimation of predictive values at varying prevaience rates.
3.9.1 Evaluating subject demographic and symptom reporting profiles
Frequency distributions summarized diagnostic outcome for subjects with unilateral
and bilateral carpal tunnel syndrome as well as those subjects that were only evaluated on
one hand. Prevalence rates and accompanying confidence intervais were calculated for
diagnosed CTS hands at both clinical settings (i.e.. Thibert Surgicd Clinic and Mount Sinai
Hospital) as well as the overall study. Descriptive statistics including mean. standard
deviation and range descnbed subject age. height and weight profiles. One-way analysis of
variance (ANOVA) was used to determine gender differences for age. height and weight
with respect to clinical setting and diagnostic outcome. The ANOVA level of significance
was set at a= 0.05. Furthermore, calculated rnean and standard deviation described the
duration of years that CTS subjects suffered with symptorns. Frequency distribution and
cumulative percent values summarized hand symptoms, frequency and intensity of
symptoms, noctumal wakening provoked by pain or paresthesia in the hand as well as other
medical conditions reported by subjects diagnosed with carpal tunnel syndrome. Finally,
Speman rho analysis was used to determine association between reported symptoms from
the Demographics questionnaire including, numbness, tingling, pain and decreased sensation
with Stirrat's symptom reporthg questionnaire. The acceptable level of significance was set
at a= 0.05.
3.9.2 Electrodiagnostic evaluation
Frequency distributions summarized the electrodiagnosis used to evaluate the
conduction velociiies of motor ( 7 c m MDL technique) and sensory (segmentai SCV
technique) nerves of dl subject hands. Descriptive statistics, including rnean and standard
deviation, descrïbed measured vebcity for segmental nerve conductiort evduation and ?-cm
motor distal latency in subjects with and without carpal tunnel syndrome.
3.9.3 Designing and establishing positivity critenon for the Ten test
As indicated previously. the Ten test was designed by Strauch and colleagues (1997)
to identify patients with varying degrees of sensibility in fingers innervated by the median
nerve. They considered a finger sensibility score of 10 to be normal and any value c i0 to be
progressively abnormal. Therefore, patients with numerous fingers with sensibility scores
cl0 were considered to have a higher probability of carpai tunnel syndrome (Patel and
Bassini, 1999). In the curent study. sensibility scores were consrnicted into three models
designed io represent different presentations of values observed in a clinical settinp. Models
1 and 2 adopted Strauch and colleagues criterion measure of I O as normal finger sensibility.
Model I was represented by four classifications involving sensibility scores for the index,
middle and ring fingers. Classification 1 represented subject sensibility scores < 10 in the
index. middle and ring fingen. Subjects with sensibility values 4 0 in two of the index,
middle or ring fingen were considered classification II. Classification III represented
subjects with sensibility scores 4 0 in one of the index, middle or ring fingen. Finally,
sensibility scores of 10 in the index, middle and ring fingers were characteristic of
classification IV.
Model 2 was represented by five classifications involving sensibility scores for the
thurnb, index, middle and ring fingen, unlike mode1 1. Classification 1 represented subject
sensibility scores 4 0 in the thumb, index, middle and ring fingen. Subjects with sensibility
values c l 0 in three of the thurnb, index, rniddle or ring fingen were considered
cIassification II. ctassifichm m -en& subjects with ~ n s i b a t y scores in two of
the bumb, index, middle or ring fingers. Subjects with sensibility values in one of the
thumb. index. middle or ring fingen were considered classification N. Sensibility scores of
10 in the index, middle and ring fingen were characteristic of cbsification V. Finally.
Mode1 3 was designed as an aggregate score from the thumb. index. middle and ring finger
sensibility scores. Therefore. a sum score of 40 would be indicative of normal sensibility in
al1 four fingers. whereas an aggregate score c40 demonstrates abnormal ftnger sensation.
Recei ver-operator characteristic curve techniques were adopted to establish a
positivity criterion for each of the three Ten test models. Selection of the optimal cut-off for
each model was based on the classification with the lowest simultaneous frequency of false-
positives and fdse-negatives (Gunnanson et al.. 1997). Following the detemination of
positivity criterion for the Ten test models. it was necessary to select one of the ihree models
to represent the Ten test in determining efficacy compared to the gold standard. Two
conditional cnterion measures were used in selecting one of the three Ten test models. First,
the model's li kelihood ratio must be statistically superior compared to the other models. as
determined by a 2-test for cornparison of likelihood ratios. Second, if one model fails to be
statistically superior. the model with the highest likelihood ratio would be selected. The
Iikelihood ratio is a valuable utility measure that accounts for both sensitivity and specificity
when anal yzing the overall accuracy of clinical tests (Sacken et al.. 199 1 ).
Finally, McNemar chi-square analyses determined significant differences of paired
proponions for sensitivity, specificity. positive and negative predictive values between the
four clinical tests (i-e.. the Ten test, Tinel's sign, Phalen's test and the pressure provocative
test). The acceptabIe level of significant difference between clinical tests was set at a= 0.05.
3.9.4 Evaluating diagirostic effrcacy of independent and combined chical tests
Distribution tables summarized true-positive (TP). false-positive (Pl. false-negative
(M) and tme-negative (TN) frequencies for each independent clinical test (i.e.. Tinel's sign,
Phden's test. the Ten test and the pressure provocative test) as well as I l combinations of
the individuai clinical tests (Appendix 14). Contingency tables were used to calculate
sensitivi ty. specificity and likelihood ratio wi th accompan ying confidence intervais
(Appendix 15). The equation used to calculate sensitivity was TP/(TP+FN). Specificity was
calculated using the following equation: TN/(TN+FP). The likelihood ratio was calculated
using the equation: sensitivity/( l -specificity). Overall accuracy of the physicians diagnostic
consensus was determined for the surgeons and physiatrists independent and blinded
responses compared to the gold standard. Overdl accuracy was calculated from the
equation: (TP+TN / TP+FP+TN+EW). The combinations included: i) Phalen's test and
Tinel's sign. i i ) Tinel's sign and the Ten test. iii) Phalen's test and the Ten test, iv) Phalen's
test and the pressure provocative test, v) Tinel's sign and the pressure provocative test, vi)
the pressure provocative test and Tinel's sign, vii) Phaien's test, Tinel's sign and the Ten test,
viii) Phalen's test, the pressure provocative test and Tinel's sign, ix) Phalen's test, the
pressure provocative test and the Ten test, x) the pressure provocative test. Tinel's sign and
the Ten test. xi) Phalen's test, the pressure provocative test. Tinel's sign and the Ten test.
Finally, Cohen's Kappa statistic was adopted to determine overall efficacy for each
independent and combined clinical test compared with a confirrned diagnosis for carpal
tunnel syndrome. Kappa statistic is a valuable analysis in detemining the overali agreement
between the clinical test results and gold standard outcome (Streiner et al., 1989: Norman
and Streiner. 2 0 ) . The acceptable level of significance was set at a = 0.05. A complete
summary of Cohen's Kappa statistic of the four independent and 1 1 combined clinical tests
is outlined in Appendix 15.
3.9.5 Prevalence and predictive value estimation
Since positive predictive and negative predictive value are dependent upon
prevalence rates. hypothetical prevalence rates and corresponding predictive values.
corresponding confidence limits were determined for independent and combined clinical test
results that demonstrated significant agreement using a back calcuiation method (Knapp and
Miller. 1992). Positive predictive values were caiculated using the formula TP/(TP+FP).
Negative predictive values were calculate using the formula TN/(TN+M). Three
prevalence rates were setected, including: i) the current study prevaience. ii) a 20%
prevalence portraying the proportion of CTS patients typicaily screened by a general
practitioner. and iii) a 5% prevalence reflecting an occupational setting identified at risk of
carpal tunnel syndrome (Tetro et al.. 1998). The purpose of exarnining positive and negative
predictive values at various prevalence rates is to estimate the ability of clinical tests to
predict a diagnostic outcorne in both clinical ( e g , present study) and population-based
settings (Le.. occupational worksite and general practitioner chic). Finally, McNernar chi-
square analyses determined significant differences between positive and negative predictive
values for the independent and combined clinical tests across the three prevdence rates. The
acceptable level of significant difference between pairrd proportions was set at a= 0.05.
RESULTS
4.1 Subject response to Stirrat's symptom reporting questionnaire
Ninety-two subjects completed Stirrat's symptom reporting questionnaire (SRQ) by
outlining the distribution of their symptoms. A total of 173 hands were classified according
to the criteria established by Katz and colleagues (1990b) as most subjects completed
Stirrat's SRQ for both hands. Appendix 3 outlines a pst-hoc sample size determination with
a prevalence (0.62). sensitivity (0.76) and specificity (.34) selected from the least efficacious
clinical test (i-e., pressure provocative test) in the current study. Based on a 95% confidence
level (a= 0.05). a final accuracy estimate of 5.8% was determined in the current study.
A classic carpal tunnel rating was classified in 56 hands as indicated by tingfing,
numbness. or decreased sensation with or without pain in at least two of the index. middle or
ring fingers. A probable rating was found in 66 hands that simulated a classic rating with
symptoms in the median nerve distribution of the palm. A possible rating was indicated in
12 hands that described symptoms as tingling, numbness. or decreased sensation in one of
the index, middle or ring fingers. Finally. an unlikely rating was found in 39 hands that
reported no symptoms in the index. middle or ring fingers. Spearman's rho analysis
indicated a positive correlation between Stirrat's SRQ and reported symptoms. including
numbness (rd.273. pc0.00 1 ), tingling (r=O-42, p<O.OO 1 ) and pain @=O. 199, p<0.01).
However, no significant correlation was found between Stirrat's SRQ and decreased
sensation (1-4 .1 24, pN.05 j.
4.2 Description of sensory and motor nerve conduction studies
Table 4.1 outlines the sensory and motor nerve conduction studies used in the current
study. Sensory conduction velocity (SCV) using the segmental stimulation technique was
conducted on 167 subject hands. One-hundred and thirty-six segmentai SCV subject hands
indicated a positive sensory conduction latency 0 . 4 ms. Motor distal latency technique was
conducted on 43 subject hands with 18 of these hands demonstrating a positive motor distal
latency &.O ms. A total of 37 subject hands received both segmental SCV and 7-cm MDL
techniques. The results indicated a consistency of positive and negative neme conduction
studies between both techniques in 9 and 8 subject hands. respectively. Lack of similar
findings in sensory versus motor nerve conduction studies were found in 13 subject hands
with positive SCV and negative MDL, and 7 hands demonstrated negative SCV and positive
MDL. The preponderance of subject hands ( 130) were examined using only segmental SCV
technique, while the majority of these hands ( 1 14) indicated a positive latency across the
carpal tunnel. Finally, six subject hands received only the 7-cm MDL technique.
Table 4.2 outlines the 167 hand sensory conduction velocity values for positive (136)
and negative (31) electrodiagnosis for nine stimulation sites as well as the location of the
median nerue compression. A positive elecuodiagnostic evaluation was identified in subject
hands if at Ieast one incrernental sensory value (difference between the peak latency for
successive sensory nerve action potentiais) was 0 . 4 ms. (Seror, 1994). The nine
stimulation sites across the carpal tunnel demonstrated progressively shorter sensory
conduction velocities moving 2-cm proximal from the distal wrist crease (DWC) to 6cm
distd from the DWC in subject hands regardless of electrodiagnosis. Sensory conduction
velocities were consistently slower a each stimulation site in subject hands with a positive
SCV latency compared to hands with a negative etectrodiagnosis. The most m u e n t
stimulation sites in the 136 subject hands demonstrating a sensory latency 0 . 4 ms. were
between '1 cm to DWC (22), DWC to -1 cm (37), -1 cm to 2 cm (31), '2 cm to -3 cm (18)
and -3 cm to '4 cm (24). The 7-cm MDL technique was performed on 43 subject hands. A
positive electrodiagnostic evaluation based on a motor distal latency 4.0 msec (Jackson and
Clifford, 1989) and was identified in 18 subject hands. Conduction velocities for positive
and negative 7-cm MDL technique were 5.18k1.36 and 3.3H.36 ms.. respectively.
Table 4.1 Sensory and motor nerve conduction studies ---
Nerve Conduction Studies N (% of hands)
'SCV + %DL 9 5 'SCV + ' MDL 13 8 ' SCV + 'MDL 7 4 'SCV + 'MDL 8 5 'SCV only 114 66 - SCV only 16 9 'MDL only 2 I - MDL only 4 2 SCV= Scnsoq conduction vclocity; MDL= Motor d i sd lritcncy
Table 4.2 Segmental sensory conduction velocity and latency location - - - - - - - - -
S tirnulation ‘ SCV ' SCV SCV Frequency Location Velocity (ms.) Velocity (ms.) of Latency (n)
+2 2.99 + 1.39 3.65 + 1 .O3 I
+ 1 2.87 + 1 .JO 3.37 + 1.01 W h 77
DWC 2.55 + 1.22 3.25 + 1 .û4 37
-6 1.28 + 0.69 1.59 + 0.78 -- SCV= Scnsory conduccion velocity; DWC = Distd Wrisi Crrrise
4.3 Diagnostic classification using the gold standard
Table 4.3 summarizes the diagnosis of subjects classified using Stirrat's SRQ in
conjunction with nerve conduction studies. A classified positive diagnosis for carpal tunnel
syndrome required classic or probable symptoms combined with a positive nerve conduction
evaluation. A total of 173 subject hands were assessed to classify a diagnosis for carpal
tunnel syndrome. Carpal tunnel syndrome was diagnostically classified positive in 108
hands and negative in 65 hands. Overall, hand prevalence of carpal tunnel syndrome was
0.62fl.07. Independent hand prevalence rates for Thibert Surgical Clinic and Mount Sinai
Hospital were 0.719.08 and 0.42fl. 12, respectively. Approximately half of these hands
(46%) demonstrated classic CTS symptoms according to Stirrat's cnteria of paresthesia with
or without pain in at least two of the index, rniddle or ring fingers. Furthemore. the
preponderance (92%) of these classic CTS subject han& was diagnosed using the segmental
sensory conduction velocity technique. A total of 65 subject hands were confirrned negative
for carpal tunnel syndrome. The majority of negative CTS subject hands were classified as
unlikely. which is indicative of the subject with no syrnptoms in the index. middle or ring
fingers. and thus met the negative syrnptom critena for the gold standard. However, a large
number (29) of CTS negative hands that indicated unlikely symptoms were positive for
sensory nerve conduction latencies. Sirnilarly. a small number of negative CTS hands
demonstrated classic (6) and probable (8) symptoms with negative sensory nerve conduction
latencies.
Table 4.3 Diagnostic classification using Stirrat's SRQ and nerve conduction studies
Stirrat's SRQ %CS Classified Diagnosis 'NCS Classification SCV MDL 'CTS 'CTS SCV MDL
NCS= Neme conduction smdits; SCV= Sensory conduction vclocity: MDLF Motor d i s d latency = -CTS (Nepave c q d NMCI syndrome); . . ,;-_ ='a (Positive cYp;il tunnel syndrome)
4.4 Data completion and non-responders
Subject data files with a completed Stirrat's SRQ and electrodiagnostic evaluation
were considered acceptable and complete information. Missing variable information is
summarized in Table 4.4. AU non-responder information remaineci &tank in the NCSS
database since statistical programs acknowledge al1 numencally coded figures as facnial
data. A minimal number of subjects failed to report age. height, weight. occupation and
restricted hand use. A higher proportion of subjects failed to report hand symptoms
including duration, intensity. frequency, and noctumal wakening. Finally. Phalen's test (2)
and the Ten test ( 1 ) were not reported for three CTS negative subject hands. Overall,
physician reports (i.e.. Surgeon's Clinical Report, Electrodiagnostic Report) were more
complete ihan the patient's demographics questionnaire. Furthemore. failure of patients to
complete a description of symptoms in negative CTS hands could be due to the fact that
these hands did not demonstrate the characteristic symptoms that thesr questions were used
to evaluate.
Table 4.4 Summary of missing subject and hand data
Su bjec ts Hands
Variable 'CTS (n=73) 'CTS (n= 19) Variable 'CTS (n= 108) -CTS (n=65)
Age 11 O Duration 1 26 Height I I 1 Intensity 1 1 20 Weight 9 4 Frequenc y 17 28 Occupation 9 O NO-d wakmkg 10 20 Restricted hand use 9 1 Phalen's test O 2
CTS = Negauvc carpd tunnel syndrome; 'CTS =Posiave c q d tunnel syndrome
4.5 Su bject and hand diagnostic presentation
Table 4.5 outlines subject and hmd frequency distribution according to diagnostic
outcome. A sarnple of 92 subjects, including 65 femaies and 27 males, with symptoms in at
least one of their hands, were assessed by a plastic surgeon at either the Thibert Surgicai
Clinic (64 subjects: 121 hands) or Mount Sinai Hospital (28 subjects: 52 hands). Thirty-five
subjects were diagnosed with bilaterd carpal tunnel syndrome. Furthemore. 38 subjects
were confimed positive CTS in one hand, while eight of these subjects were assessed on
only one hand. The eight subjects refused electrophysiological examination of their
contralateral hand. Negative carpal tunnel syndrome was confirmed in the contralateral
hand of 31 CTS subjects. Finally. negative carpi ~ n n e i syndrome was diagnosed in both
hands of 15 subjects. while four individuals demonstrated negative carpal tunnel syndrome
in only one hand tested. These four subjects refused nerve conduction studies on their
contralateral hand.
Table 4.5 Subject and hand diagnostic distribution
Diagnostic Outcome Subjects (N) Hands (N)
'CTS (only 1 hand tested) 7 7 'CTS (bilateral) 35 70 'CTS (unilateral) 'CTS (contrafateral hand) --- 'CTS (bilateral)
l I:: f 15 30
'CTS (only 1 hand tested) ffi 5 92 173
'CTS = N q t i v c cvpal tumci syndrome; ' C T S =Positive cvpd tunnef syndrome
4.6 Demographics
Subjects reflected the epidemiology of CTS in that the majority of subjects
diagnosed with carpal tunnel syndrome were femde (68%). One-way ANOVA indicated no
significant differences (pM.05) for age, height or weight between the two clinical seitings
for male and fernale subjects. OveralI, age (Fd8.3+I5. I y; M=52.9212.9 y) was not
significantly different (pN.05) between genders, while height (F= 1.62fl.08 m;
M4.77fl.08 m) and weight (F=75.5220.3 kg; M=93.0&18.0 kg) were significantly greater
(pcû.001) in males subjects upon combining the subject files from both clinics. Table 4.6
outlines demographic profiles of male and fernale subjects according to diagnostic outcome.
No significant age, height, or weight differences were found (p>0.05) with respect to
diagnostic outcome.
Table 4.6 Subject demographics by diagnosis
- ~ g e (Y) - Height (m) - Weight (kg) X + SD Range X + SD Range X + S D Range
' CTS F 47.5 + 13.5 25-87 1.63 I 0.08 1.47-1.99 73.5 + 16.1 45.5- 1 13.6 M 53.1 + 13.7 25-73 1.76 + 0.06 1.66-1.85 94.9 + 20.6 68.2- 136.4
- CTS F 48.8 + 18.4 24-84 1.6 1 + 0.07 1.45- 1.73 80.9 + 27.7 47.7- 136.4 M 52.4k11.3 38-68 1.80+0.13 1.68-2.06 87.5t4.2379.6-91.8
' CTS = Ncgtitivt c m tunnel syndmmc; CTS =Positive c e tunnel syndrome
1.7 Subject medical profiles
TabIe 4.7 summan-zes reported medicai conditions of study subjects. Thiny-three
CTS subjects reported suffering from medical conditions. This high incidence of co-
morbidity between carpal tunnel syndrome and other medical conditions is consistent with
the literature (Stevens et al.. 1992). The most prevalent conditions included hypothyroidism
(8), diabetes (6) and gout (4). The most commonly reported conditions in negative C ï S
subjects included hypothyroidism (4). hypertension (4) and osteoanhriiis (3). Table 4.8
outlines the frequency, intensity, duration as well as specific types of syrnptoms reported by
subjects with carpal tunnel syndrome. The average duration of syrnptoms in subjects with
carpal tunnel syndrome was 1.96fl.2 years. The CTS subject symptorn complex included:
tingling (90%). numbness (79%) and pain (69%). As reported earlier, tingling, numbness
and pain wece positively correlated (p<0.01) with Stirrat's SRQ. Noctumal wakening (804)
was also reported by the preponderance of positive CTS subjects. The majority of CTS
subjects reported hand syrnptoms more than 6 times daily. Finally. subjects rated their
intensity of hand pain near "maximal discornfort" (median score =7+1).
Table 4.7 Subject medical conditions
Condition 'CTS (n) CTS (n)
Rheumatoid arthritis Pregnanc y H ypo th yroidi srn Rend failure Gout Diabetes Wnst fracture Wrist laceration Hypertension Fi brom ydgia Ganglion excision Osteoarthritis Myocardial infarction Pol yrnyalgia De pression
' C T S = Ncptive c q d tunnel syndrome 'CTS =Positive urpiû tunnel syndmmc
Table 4.8 Symptom complex of subject hands with carpal tunnel syndrome
Symptom Variable Frequency (%)
Noctumai wakening Symptorn Reporting:
= Numbness Tingling Pain Decreased sensation Loss of strength/weakness
= Cold sensation Nerve twitch
Frequenc y: 1 to?times/day 3 t o 4 times/day 5 to 6 tirnedday > 6 tirnedday
Intensity: (Likert Scale) = Ranking 1 "minimum discornfort"
Ranking 2 Ranking 3 Ranking4 Ranking 5 Ranking 6 Ranking 7
= Ranking 8 Ranking 9 Ranking 10 "maximum discornfort"
4.8 Electrodiagnostic evaluation
Table 4.9 summarizes the average sensory conduction velocities for the segmental
nerve conduction study. Segmentai sensory conduction velocity technique was conducted on
160 subject hands ('CTS, n=99: C T S , n=61). Positive CTS subject hands demonstrated a
consistent trend for slower conduction velocities at each of the stimulation points.
Table 4.9 Velocity measures using the segmentid serisory conduction velocity technique in subject hands with and without carpal tunnel syndrome
S tirnulation 'CTS (n=99) 'CTS (n=6 1 ) Location m.) (ms.)
+2 + 1
DWC - 1 - 7
-3 -4
- -- - -
DWC = Disd Wnst Crcase: 'CTS = Negative cupd tunnel syndrome: 'CTS =Positive c q n l tunnel syndrome
The 7-cm motor distal latency technique was used to confirm a diagnosis in an
additional 13 subject hands ('CTS, n=9: 'CTS, n=4). Average velocity measure for the 7-cm
MDL conduction technique was 6.1-1.6 1 and 3.05g.19 ms. in subject han& with positive
and negative carpal tunnel syndrome, respectively (Table 4. IO). No statistical analysis was
conducted on the 7-cm motor distal latency values due to the small available sample of
hands. However, the mem latency values demonstrate a trend towards slower conduction
velocities found in subjects with positive CTS hands.
Table 4.10 Velocity measures using the 7-cm motor distal latency in subject hands with and without carpal tunnel syndrome
Diagnostic Subject Outcorne (NI
4.9 Establishing positivity criterion for the Ten test models using ROC curve techniques
Receiver-operator characteristic (ROC) curve techniques were adopted to establish
positivity criterion for each of the three Ten test models. Selection of the optimal cut-off
was based on the classification with the lowest simultaneous frequency of faise-positives
and false-negatives (Gunnarsson et al., 1997) for each model. Model 1 ROC curve results
indicated an optimal cut-off between classification 2 and 3. Therefore. subject hands
dernonstniing sensibility scores <IO in at lem two of the index, middle and ring fingen
were considered positive for carpal tunnel syndrome. Furthemore, subject hands indicating
finger sensibility values <10 in one or none of the index. middle or ring fingers were
considered negative for carpal tunnel syndrome. Model 2 ROC curve results also indicated
an oprimal cut-off between classification 2 and 3. Therefore, subject hands demonstrating
sensibility scores ç10 in at least three of the thumb, index. middle and ring fingers were
considered positive for carpal tunnel syndrome. Furthermore, subjects with sensibility
values c l 0 in two, one or none of the thumb, index, middle and ring fingers were considered
negative for carpal tunnel syndrome. Finally, ROC curve results for Model 3 indicated an
optimd cut-off berween a composite sensibility score of 36 and 37. Therefore, subject hands
dernonstrating an aggregate sensibility score for the thumb. index. middle and ring fiers
536 were considered positive for carpal tunnel syndrome, while those with a sum score of
37 to 40 were considered negative for carpal tunnel syndrome. Model 3 aggregate sensibility
scores ranged from 5 to 40. The total frequency of fdse-positives (FP) and false-negatives
(M) for ~Models 1, 2 and 3 were r14 (FP=32, FN=12), 45 (FP=3 1, FN=14) and 44 (FP=32,
M=12), respectively. Appendix 13 summarizes the ROC curve results used in selecting an
optimal cut-off for the three Ten test models. Furthermore. ROC curve illustrations for al1
three Ten test models, demonstrating the trade-off between sensitivity and specificity, are
graphicall y presented in Appendix 1 3.
4.10 Evaluating the efficacy of the Ten test models
Calculated sensitivity. speci ficity and likelihood rati a with accompan ying confidence
intervals for the Ten test Models 1 to 3 are presented in Table 4.1 1 . Models I and 3 shared
the highest sensitivity (0.89) and lowest specificity (0.50). Not surprising, Models 1 and 3
shared the lowest identical IikeIihood ratio (1.78). Conversely, Model 2 indicated the lowest
sensitivity (0.87) and the highest specificity (0.52). Findly. Model 2 demonstrated the
highest likelihood ratio ( 1.8).
Table 4.1 1 Ten test models
Hand Digit Sensitivity (CT) Specificity (CI) Likelihood Ratio (Cr)
Model l 0.89 (0.8 1 - 0.97) 0.50 (0.39 - 0.6 1 ) 1 -78 ( 1.62 - 1.92) Model 2 0.87 (0.79 - 0.95) 0.52 (0.4 1 - 0.63) 1.80 ( 1.65 - i .93) Mode13 0.89 (0.81-0.97) 0.50 (0.39-0.61) 1.78 (1.63-1.91)
The likelihood ratio is a valuable utility measure that accounts for both sensitivity
and specificity when analyzing the overall accuracy of clinical tests (Sackett et al., 1991).
The z-test comparative analysis of likelihood ratios indicated no significant difference
(p9.05) between the three Ten test models. Therefore. none of the Ten test models were
significantly superior in determining the likelihood of diagnosing carpal tunnel syndrome
given a positive test resuit. Modeis I and 2 were designed based on the criteria outtined by
Strauch and colleagues (19971, whereby a sensibility score of 10 was considered normal and
sensations between one and nine are considered abnormal. Furthemore, Model 2 was
further designed to include al1 hand digits innervated by the median nerve (i.e.. thumb,
index. rniddle and ring fingers). However, Mode1 I involved only the index. middle and
ring fingers. while omitting the contribution of the thumb. From a theoretical viewpoint.
Model 2 more closely encornpasses the criteria outlined by Strauch et al. ( 1997) as well as
the physiological contribution of median nerve sensory enervation to the thumb. index,
middle and ring fingers.
A secondary objective of the current study was to estabtish positivity critenon for the
Ten test. Selection of the optimal cut-off classification for the Ten test Model 2 detem.ined
positivity critenon as hand sensibility values 4 0 in ai least three of the thumb. index.
middle and ring fingers. Subject hand sensibility scores not meeting this minimal criteria
were considered CTS negative. A cornpiete description of the Ten test Model 2 is outlined
in Table 3.12. A ROC curve for the Ten test Model 2 illustrates the trade-off between
sensitivity and specificity in determining positivity criterion (Figure 4.1).
Table 4.12 Ten test Model 2 criteria --
Class Criteria - -
1 The patient has a score c 10 in the thumb. index, middle and ring fingea. II The patient has a score c 10 in three of the thumb, index, middle or ring fingen. III The patient has a score < 10 in two of the thumb. index. middle or ring fingen. IV The patient has a score 4 0 in one of the thumb, index, middle or ring fingers. V The batient has a score of 10 in the thumb, index, middle and ring fingen.
Sensitivity
4.1 1 Cornparison between individual clinical tests
Table 4.13 outlines the results of the McNemar chi-square analyses used to
determine significant differences of proportions for sensitivity. specificity. positive and
negative predictive values between the four individual clinical tests. The Ten test sensitivity
was significantly supetior (p4.05) compared to the pressure provocative test, but not
significantly different from that of Tinel's sign and Phalen's test (pS.05). Furthemore, the
Ten test and Tinel's sign specificity were significanrly superior ( ~ 4 . 0 5 ) compared to the
pressure provocative test, but comparable (p9.05) with Phalen's test. Similarly, the Ten test
and Tinel's sign negative predictive value was significantly superior (p<0.05) compared to
the pressure provocative, but not significantly different (pN.05) compared to Phalen's test.
Finally, Tinel's sign positive predictive value was significantly supenor (pcû.05) compared
to the pressure provocative test. but comparable to the Ten test and Phalen's test (pc0.05).
Table 4.1 3 McNemar chi square cornparison between individual clinical tests
Test Sensitivity (CI) Specificity (CI) 'PV (CI) - PV (CI)
.. . - - - -
' TT was significuirly superior c o m p ~ to PPT (pc0.05); t TS wris signific~idy superior cornpared IO PPT (p4I.05) TS = lincl's sign: Ti = Ten ra t ; PT = Phdcn's test: PFT = Pressure pmvocativc ta t ; 'PV= Positive Predictivc Vduc; ' PV= Ncptive Pdicavc Value
4.12 Distribution of clinical tests compared to the gold standard
Frequency distributions for the 4 independent and 1 lcombined clinical tests are
summarized in Appendix 14. Among independent clinical tests, the Ten test reported the
highest true-positive (94) and lowest false-negative (14) frequencies. Tinel's sign
demonstrated the highest frequency of true-negatives (42) as we11 as the lowest number of
false-positives (23). Finally, the pressure provocative indicated the highest number of false-
negatives (26) and false-positives (43) as well as the lowest number of true-positives (82)
and me-negatives (22) among individual clinical tests. As a combination, Tinel's sign with
the Ten test reported the lowest number of fdse-positives (32). highest frequency of tme-
negatives (32) and shared the highest number of true-positives (79) with the combination of
Tinel's test and Phalen's test. Tinel's sign combined with either the Ten test or Phalens' test
also shared the Iowest number of false-negatives (29) among 2-test combinations.
Conversel y. the pressure provocative test combined with the Ten test demonstrated the
lowest nurnber of tnie-negatives (16) and highest false-positives (48). Finally. Tinel's sign
combined with the pressure provocative test indicated the lowest frequency of true-positives
(73) and highest false-negatives (35) frequencies among 2-test combinations. A cornparison
of 3-test combinations showed that Phalen's test, Tinel's sign and the Ten test had the highest
frequency of true-positives (75) and tme-negatives (23) as well as the lowest number of
false-posi tives (39) and false-negatives (33). The combined influence of the pressure
provocative test. Phalen's test and the Ten test reponed the lowest number of tme-negatives
( 1 3) among 3-test combinations. Finally, the pressure provocative test cornbined with the
Ten test and Tinel's sign indicated the lowest number of true-positives (70). highest false-
negatives (38) and shared the most false-positives (49) with the combination of Phalen's test,
the Ten test and the pressure provocative test. The combination of al1 four clinical tests
reported either independently or shared the highest frequency of false-positives (49) and
false-negatives (38) as well as the lowest number of true-positives (70) and true-negatives
( 13). Overdl, frequency of true-positives and true-negatives decreased and false-positives
and false-negatives increased with a greater number of combined tests.
4.13 Diagnostic eficacy of clinicai tests compared to the gold standard
The diagnostic efficacy of the individual and combined clinical tests is summarized
in Table 4.14. Among al1 independent clinical tests. the Ten test indicated the highest
sensitivity (0.87). while Tinel's sign demonstrated the highest specificity (0.65) and
Iikelihood ratio (2.22). Conversely, the pressure provocative test presented the lowest
sensitivity (0.76). specificity (0.34) and likelihood ratio (1.15). A cornparison of 2-test
combinations demonstrated that the Ten test combined with Tinel's sign had the highest
specificity (0.50). likelihood ratio (1.46) and shared the highest sensitivity (0.73) with the
combination of the Ten test and Phalen's test. Furthermore. the combined influence of the
pressure provocative test and the Ten test indicated the lowest specificity (0.45) and
likelihood ratio (0.9 1). Finally, Tinel's sign combined with the pressure provocative test
indicated the lowest sensitivity (0.68). Among 3-test cornbinations. Phaien's test combined
with Tinel's sign and the Ten test demonstrated the highest sensitivity (0.69). specificity
(0.37) and likelihood ratio (1.1). Conversely, Phalen's test combined with the pressure
provocative test and the Ten test indicated the lowest specificity (0.21) and likelihood ratio
(0.84). Furthermore. the Ten test combined with the pressure provocative test and Tinel's
sign indicated the lowest sensitivity (0.65). Final1 y, diagnostic contribution from the
combined four clinical tests indicated either independently or shared the lowest sensitivity
(0.65), specificity (0.21) and likelihood ratio (0.82) of dl individual and cornbined tests. As
a whole, sensitivity, specificity and likelihood ratio progressively decreased with a greater
number of combined clinical tests. The overall accuracy of the surgeons and physiavists
diagnostic consensus, which was blinded from the gold standard, as well as each other's
diagnostic tests, was 70% and 68%. respectively.
Cohen's Kappa statistic was used to evduate the statisticai eficacy of independent
and combined clinical tests with a confirmed diagnosis. Tinel's sign. the Ten test. and
Phalen's test demonstrated significant Kappa agreement ( p 4 . 0 5 ) with the confirmed
diagnosis for carpal tunnel syndrome. The pressure provocative test did not indicate
significant Kappa agreement (pN.05). Furthemore. Tinel's sign combined with either the
Ten test or Phalen's test demonstrated the only combined clinical test results with significant
Kappa agreement (~4.05). AH remaining clinical test combinations demonstrated
progressively less Kappa agreement with the confinned diagnosis ( Appendix 15).
Table 1.14 Kappa agreement between clinical tests and the gold standard --
Test(~) Sensitivity (CI) Specificity (CD Likelihood Ratio (CI) --
TS 0.79 (0.7 1 - 0.87) 0.65 (0.55 - 0.75) 2.22 (2.08 - 2.36) t TT 0.87 (0.79 - 0.95) 0.52 (0.41 - 0.63) 1.80 (1.66- 1.94)T PT 0.80 (0.72 - 0.88) 0.48 (0.37 - 0.59) 1.52 (1.38- 1.66)"r PPT 0.76 (0.68 - 0.84) 0.34 (0.23 - 0.45) 1.15 (1.01 - 1.29) TS+TT 0.73 (0.65 - 0.8 1) 0.50 (0.39 - 0.6 1 ) 1.46 ( 1.32 - 1.60) t. TS+PT 0.73 (0.65 - 0.8 1) 0.46 (0.34 - 0.58) 1.36 (1.21 - 1.52) t t Kappa signtficant agreement ( p 5 0.05)
1.14 Prevalence rates and predictive value estimation
Since positive predictive value (TV) and negative predictive value ('PV) are
dependent upon prevalence rates, hypothetical prevalence rates with parallel 'PV's, -PV's
and confidence intervals were calcuiated for al1 independent and combined clinical tests that
demonstrated significant Kappa agreement (Table 3.15). Prevalence rates selected were
62% (observed in the currenr study), 20% which portrays the proportion of CTS patients
typically seen by a general practitioner. and 5% which was selected to reflect an
occupational setting with carpal tunnel syndrome (Tetro et al., 1998). Tinel's sign indicated
the highest 'TV (0.79). while the Ten test demonstrated the highest 'PV (0.70) in the current
study. Conversely. Tinel's sign cornbined with Phalen's test indicated the lowest 'PV (0.70)
and 'PV (0.50) in the current study. McNemar chi-square indicated no significant
differences (pc0.05) between the high and low +PV and -PV in the current study. Tinel's
sign or the Ten test consistently demonstrated the highest 'PV and 'PV and Tinel's sign
combined with Phalen's test consistently demonstrated the lowest 'PV and 'PV across al1
prevalence rates. McNemar chi-square analyses evaiuated significant differences for 'PV
and 'PV each individual and combined test across the three prevalence rates. The 'TV of
each independent and combined test was significantly inferior (p~0.001) progressing from a
high (i.e.. 62%) to lower (20% and 5%) prevalence rates. Furthemore. the *PV of al1
individual or combined clinical tests were significantl y superior (pc0.00 1 ), ranging from a
high (62%) to low (5%) prevalence rate.
Table 4.15 Prevalence rates md corresponding predictive values
Test(s) 'PV (CI) - PV (CI) T V (Cr) T V (CI) 'PV (CI) - PV (CI)
TS -79 (.OS) .65 (. 12) 3 1 1) .92 (-05) 1 O (-08) * .98 (.02) t TT .75(.08) .70(.12) .32 (. 10) .95 (-06) .O9 (.07) * -99 (.O 1) t. PT .72 (-09) .58 (. 12) .28 (. 1 O) -90 (.06) -07 (.OS) * .98 (.OZ) t TS+TT .7 1 (.OS) 52 (. 12) .27 (. 1 O) .90 (-06) .O8 (.OS) * -98 (.02) t TS+PT .70 (.08) .50 (. 12) .26 (.09) -89 (.07) .O7 (-04) * -97 (.03) 7
*PV sigmlicuitly infenor fmm .62 IO 20;uid .62 to .O5 (p<0.05) t ' PV significuidy superiar frorn .6Z to 20 md .62 to -05 (pd.05) 'PV = Positive pceiftctive value; 'PV = N e p i v c p d c b v e value
CHAPTER V
DISCUSSION
5.1 Introduction
A variety of clinical tests have demonstrated a wide variance of utility measures in
diagnosing carpal tunnel syndrome. Furthemore, there are a limited number of well-
conducted studies regarding the efficacy of ciinicd tests in diagnosing carpal tunnel
syndrome. The rnost cornmon methodological violations include i) failure to independently
blind the clinical examiner from the results of the electrodiagnostic outcome, ii) neglect in
adopting a recognized gold standard or iii) implementation of an appropriate spectmm of
patients. The current study accounted for these important methodological criteria in
evaiuating the efficacy of Tinel's sign, Phalen's test, the pressure provocative test and the
Ten test in diagnosing carpai tunnel syndrome.
All subjects received the recognized gold standard for the diagnosis of CTS,
including electrodiagnosis combined with S tirrat's SRQ. S peci ficall y, subjects' symptoms
were reported using Stirrat's standardized self-administered symptom reporting
questionnaire. S ymptom questionnaires, such as Levine and colleagues sel f-administered
symptom severity and functionai status questionnaire, have been recognized as a valid tool
in evduating a CTS patient's history (Levine et al., 1993). However, Stirrat's SRQ is
considered more accurate in diagnosing CTS with measures for sensitivity and specificity
that exceeded those of Levine's questionnaire (Atroshi et ai., 1997). Currently, Stirrat's SRQ
is recommended in diagnosing CTS as it more definitively identifies a patient's symptom
cornplex, and therefore reduces the opportunity for faIse-negative and idse-positive
diagnoses (Rempel et ai.. 1998). Furthermore. the current study demonstrated a significant
correlation between Stirrat's SRQ and common symptoms of carpal tunnel syndrome.
including numbness. tingling and pain. The majority (92%) of subjects in the current study
were examined using the segrnental SCV technique. This electrophysiological technique is
recognized as one of the most sensitive tests supponing the diagnosis of CTS. particularly in
patients with mild carpal tunnel syndrome (Jablecki et al.. 1993). The remaining subject
hands in the current study were diagnosed using the 7-cm MDL technique. This
electrodiagnostic test is less sensitive compared to the segrnental SCV technique. especially
in patients with questionable symptoms. However. al1 subjects diagnosed positive C S with
the 7-cm MDL technique reported classic or probable CTS symptoms.
Al1 subjects were independently examined for the surgeon's clinical evaluation and the
physiatrist's electrodiagnostic assessment. Furthermore. the physicians were intentionally
blinded from the subject's responses to Stirrat's SRQ and each other's evaluations in order to
control for systematic bias. The surgeons and physiatrists were instructed to provide a
diagnostic consensus of carpai tunnel syndrome based on their clinical and
elecuophysiologîc examinations. The surgeons diagnostic consensus based on the clinicai
test results including Phalen's test, the pressure provocative test, the Ten test and Tinel's sign
indicated an overall accuracy of 702 when cornpared with the gold standard. Similady, the
physiatrists diagnostic consensus demonstrated an overall accuracy of 68% when compared
to the gold standard. The physiatrists diagnostic decision was based on the
electrophysiological examinations, including segmental SCV and 7cm MDL techniques.
Finally, the current study incorporated subjects with a varied spectnim of symptoms, as well
as a number of control hands. Subjects demonstrated a large distribution of symptom
classification according to Stirrat's SRQ. This latger spectmm increases the strength of the
study by demonstrating that the clinicd tests of interest illustrate the ability to distinguish
between those subjects with and without carpal tunnel syndrome (Sackett et al.. 199 1).
5.2 Subject profiles
Carpal tunnel syndrome is the most common compression neuropathy with many
clinical presentations (Rosenbaum. 1999). A total of 92 subjects suspected of suffenng from
carpal tunnel syndrome forrned the base of subjects for this study. The majority of
confimird CTS subjects were middle-aged femaies, which is consistent with the literanire
(Szabo and Madison, 1992). Schenck (1989) suggests carpal tunnel syndrome effects
women as much as three tirnes more than men and patients are typically diagnosed between
the ages of 10 and 60 years. Bilateral carpal tunnel syndrome was diagnosed in half of al1
subjects diagnosed with CTS in the current study, which is consistent with the literature
(Katz, 1994). Hand discomfort leading to noctumal wakening was also reported by a large
majority of subjects suffering from carpal tunnel syndrome. Katz (1994) supports this
finding suggesting that up to 95% of CTS patients experience sleep disturbances due to pain
and numbness in the hand. Finaily. nearly haif the CTS subjects in the current study reported
a large range of CO-morbid medical conditions. including rheumatoid arthritis. gout, rend
failure, hypothyroidism, diabetes, and wrist fractures. These conditions are believed to
compromise the carpal canai by compressing the median nerve (Szabo and Madison. 1992;
Mahoney and Dagum, 1992). Finally, idiopathic carpal tunnel syndrome represents
approximately half of al1 cases in the generd population (Stevens et al.. 1992). which is
consistent with the current study.
5.3 Efficacy of ciinical tests
According to Valanis ( 1999). the term efficacy is defined as the extent to which a
specific test or procedure demonstrates a useful outcome under ideal and controlled
conditions. The incorporation of inclusion and exclusion criteria as well as blinding
throughout the clinical examination of experienced physicians enhanced the opportunity to
evaluate efficacy of CTS clinical tests in the current study. The results of the current study
demonstrated that Tinel's sign, Phalen's test and the Ten test are efficacious clinical tests,
while the pressure provocative is not an accurate test in diagnosing carpal tunnel syndrome.
Furthemore, Tinel's sign combined with either the Ten test or Phalen's test have indicated
significant efficacy in diagnosing patients with symptoms of carpal tunnel syndrome.
The likelihood ratio contrasts the proportion of patients with and without the target
disorder who display a given level of a diagnostic test result (Sackett et al.. 1991). The
likelihood ratios for independent and combined clinical tests in the current study indicated a
sip i f icant Kappa agreement with the gold standard ranging from 1.36 to 2.22. A
cornparison of clinical test likelihood ratios of other diseases, such as coron. artery
stenosis (LR=39) (Diarnond and Forrester, 1979), tuberculosis (LR=31) (Boyd and Man,
1975) and pancreatic disease (LR=5.6) (Hesse1 et al.. 1982), would regard these reported
likelihood values for CTS as modest. However, a cornparison of these likelihood ratios to
diseases of this severe nature cm be misleading since these conditions place a strong
emphasis on a high sensitivity, which contributes to a high fdse-positive rate and
corresponding Iow faIse-negative rate. As was previously indicated, the current study took a
conservative approach, whereby the patient could suffer equally from a false-positive and
faise-negative diagnosis upon selecting an appropriate cut-off for the Ten test. Therefore,
the Ten test ROC analysis in the current study dictated an optimal cut-off based on
minimizing the sum of false-positives plus faise-negatives. A closer analysis of the studies
by Diamond and Forrester (1979). Boyd et al. (1975) and Hesse1 et al. (1982) conducred by
Sackett et al. (1991) indicated that if these studies had taken a conservative approach in
minimizing false-negative and false-positive diagnosis, their likelihood ratios would have
ranged from 1.4 and 2.1 (these calculations were confirmed by the author of the current
study. B. Faught). These likelihood ratios are similar to the current study as well as previous
well conducted CTS diagnostic studies (de Krom et al.. 1990: Gunnarsson et a!., 1997: Katz
et al., 1990a, 1990~). Therefore. the likelihood ratios reponed in the current study are
realistic considering the nature of carpal tunnel syndrome.
5.3.1 Tinel's sign
Tinel's sign demonstrated significant efficacy with a confirmed diagnosis for carpal
tunnel syndrome in the current study. Paresthesia in the median nerve distribution of the
hand exemplifies a positive Tinel's sign in patients with carpal tunnel syndrome (Williams et
al., 1992). A variety of techniques and interpretations of Tinel's sign are known (De Smet et
ai., 1995: Kuschner et al., 1992: Mossman and Blau, 1978). In the current study, paresthesia
was provoked by firmly tapping with a large Queen's Square tendon harnmer (head diameter
5.2 cm; head width 1 cm; shaft length 38 cm; head weight 90 grarns) on the extended wrist,
over and immediately proximal to the carpal tunnel at the distribution of the median nerve.
The technique is important when provoking symptoms and slight differences contnbute to
conflicting and erroneous diagnostic information. Fint, excessive force to provoke Tinel's
sign over a healthy median nerve will produce finger tingling. and manufacture a false-
positive response (Slater and Bynum. 1993). Mossman and Blau ( 1987) examined different
techniques in administering Tinel's sign in a group of symptomatic patients and control
subjects. They concluded that failure to elicit symptoms resulted from "gentle tapping"
using smaller harnmen or fingertips rather than a iarger broader based Queen's Square
tendon hammer. Furthemore. failure to percuss the median nerve several millimetres
proximal to the carpal tunnel with the wrist in extension. which tenses the contents of the
carpal tunnel SC that percussion is transmitted to the median nerve. is alsc important in
provoking paresthesia of the median nerve.
Interpretation of equivocal results is another important factor when examining the
efficacy of Tinel's sign in diagnosing carpal tunnel syndrome. In the current study. the same
interpretation strategy used by Mossman and Blau (1987) was adopted. resulting in similarly
high sensitivity and specificity. According to this strategy. three successive percussions are
administered and followed by three additional percussions in the event that the initial
percussions were ambiguou (Mossman and Blau, L987). if the second set of percussions
remained equivocal, Tinel's sign was tenned negative. In the current study. only three
subject hands demonstrated equivocal results following a second set of percussions; each of
these subjects had been diagnosed negative for carpal tunnel syndrome.
5.3.2 Phalen's test
Phalen's test reported high sensitivity, but average specificity in the current study.
Phalen's test is one of the most commonly performed provocative tests when evaluating
patients with CTS syrnptoms (Williams et al.. 1992). The patient's hand is placed in
complete flexion at the wrist for one minute in a positional attempt to increase the pressure
in the carpal canal. The increased pressure evokes symptoms of pain and paresthesia in the
distribution of the median nerve. During flexion, the pisiform and hook of the hamate
decrease the cross-sectional area of the carpal canal (Kerwin et al.. 1996). Gelberman and
colleagues (198 1 ) found that carpal tunnel interstitial pressure increased from 2.5 to 3 1 mm
Hg when the neutral position wrist is placed in forward flexion. The current study
demonstrated the ability of Phalen's test (80%) to accurately identify subjects with carpal
tunnel syndrome. This is well documented in other studies (Gunnarsson et al., 1997: Katz et
al., 1990~). The current study also found Phalen's test (48%) to be less specific than Tinel's
sign (65%). which is also consistent with other studies (Szabo et al.. 1999; De Smet et al.,
1995: Katz et al., 1990~; Heller. 1986). Despite the reported low specificity. Phalen's test
continues to be one of the rnost efficacious tests in diagnosing carpd tunnel syndrome.
5.3.3 Pressure provocative test
The intent of the pressure provocative test is similar to Phalen's test. whereby
cornpressing the median nerve at the wrist for one minute provokes symptoms (Novak et al..
1992). However, the literature has reported technical variations in applying force on the
carpal canal, such as direct thumb pressure (Novak et al., L992), a manorneter bulb (Durkan,
1991) or sphygmomanometer cuff (Williams et ai., 1992). Standardizing exact force using
the thumb is difficult to quantify. Williams et al. (1992) found the sphygmomanometer
technique with a constant pressure of 150-mm Hg for one minute to be an accurate clinical
test as demonstrated by a sensitivity of 100% and specificity of 97%. The current study
administered the same constant pressure using a sphygmomanometer for one minute. The
lower sensitivity (76%) and specificity (34%) in the current study were not consistent with
those reported by Williams et al. ( 1992). However, the study by Williams and colleagues
(1992) had a number of problems, including failure to confim a diagnosis using an
electrophysiological examination as well as neglecting to blind the examiner. These
rnethodological flaws could have contributed to the rather infiated sensitivity and specificity
values, especially in a study that examined a small sample size (30 patients and 30 controls).
The results of the current study demonstrated a high sensitivity and low specificity. similar
to Phalen's test. The pressure provocative test and Phalen's test are similarly designed to
provoke pain and paresthesia following compression of the carpal canal (Gonzalez et al..
1997; Williams et al., 1992). Furthemore, the excessively high false-positive rate of the
pressure provocative test negated any significant agreement when cornpared to the gold
standard. This was most evident in the low likelihood ratio ( 1.15) compared to the other
independent clinical tests (Table 4.14). Therefore, the pressure provocative test is not
considered an efficacious clinical test based on the results of the current study, panicularly
in term of identifying subjects not suffering from carpal tunnel syndrome.
5.3.4 Ten test
The sensitivity and specificity values for the Ten test demonstrated a high degree of
efficacy in the current study. The Ten test is a quick and easily administered clinical test.
requiring only a normal standard of sensibili ty (e.g., asyrnptornatic finger) for cornparison
with the abnormal fingers (Strauch et al.. 1997). As alterations in hand sensation are
typically the initial complaints f r ~ m patients with median nerve compression (Szabo et al.,
1984). this relatively new clinical test is designed to subjectively detect sensibility changes
in the rnedian nerve innervated fingen on the palmar side of the hand. Currently. two
studies have reported the Ten test as being reliable and accurate in evaluating finger
sensibility (Strauch et al., 1997; Patel and Bassini. 1999). The Ten test measures sensibility
on a continuous analog scale from 1 to 10. A 10 is considered a "normal" sensibility. while
sensations gradually approaching one are perceived as revealing an increased probability of
carpal tunnel syndrome. A limitation of the aforementioned studies was the inability to
report measures of sensitivity, specificity and likelihood ratio. To date. the Ten test does not
identify a definitive positivity criterion similar to Phalen's test. Tinel's sign or the pressure
provocative test. but the test's analog scale is considered as a abnonnality continuum. This
makes calculating sensitivity and specificity a challenge in evaluating diagnostic utility in
determining the overall efficacy of this clinical test.
A secondary objective of the cunent study was to establish a positivity critenon for
the Ten test. The intent of the Ten test modeling conducted in the current snidy was not to
dispute the work of Strauch, but to further validate the overall efficacy of Ten test as a
valuable clinical test in diagnosing carpai tunnel syndrome. Therefore, the current study
adopted ROC curve techniques to establish positivity criterion for a new Ten test model. The
optimal cut-off in establishing a positivity cnterion was determined by selecting the point
that indicated the lowest simultaneous frequency of false-negatives and false-positives. This
conservative approach is essential during a clinical examination from the patient's
perspective as it limits both needless surgery Ifalse-positive) in some patients and
unnecessary suffering tfalse-negative) in others that would have otherwise benefited from
surgical intervention (Gunnarsson et al.. 1997). The ROC analysis in the current study
indicated that a subject reporting sensibiIity vaIues <IO in at Ieast three of the thumb. index.
middle and ring fingers were considered as a positivity diagnosis for carpal tunnel
syndrome. Therefore. the subjects reponing sensibility values of C I O in none. one or two of
these fingen were considered negative for carpal tunnel syndrome. It is important to
recognize the contribution of the subject's thumb sensibility score in the Ten test model.
Since the median nerve on the palmer side of the hand innervates the thumb. it is expected
that its contribution would be acknowledged in this sensibility test. However. a closer
examination of Stirrat's SRQ critena indicates that symptoms in the thumb are recognized as
insignificant in diagnosing carpal tunnel syndrome. Nevenheless. the ROC analysis and
modeling in the current study provide an expanded interpreiation by establishing a positivity
criterion for the Ten test. This prouides the oppominity to compare utility rneasures with
other clinical tests. The Ten test sensitivity (87%) and specificity (52%) were comparable to
Tinel's sign and Phalen's test in the current study. Furthermore. the Ten test demonstrated
supenor sensitivity and specificity cornpared to the pressure provocative test. Overdl. the
Ten test was an accurate clinical test in diagnosing carpal tunnel syndrome.
5.3.5 Combined clinicai tests
Since a single test is frequently insuficient for making an unequivocal diagnosis of
carpal tunnel syndrome. hand surgeons often use multiple clinical tests. Multiple clinical
tests are administered either in parallel or senally (Knapp and Miller. 1992). The present
study adopted a serial approach in administering four clinical tests. Hand surgeons often
utilize multiple clinical tests in their diagnostic algorithm. A growing number of studies
have examined the efficacy of a combined battery of tests (Szabo et al., 1999; Borg, 1988:
Katz et ai.. 1 WOa; de Krom et al.. 1990: Novak et al., 1992; Buch-laeger et al., 1994; Gerr et
al.. 1995: Gunnarsson et al.. 1997). To date, Buch-Jaeger and Foucher (1994) have
conducted the largest study in determining the utility of I l clinical tests. independently and
combined, in diagnosing carpal tunnel syndrome.
In the current study, Tinel's sign linked with either the Ten test or Phalen's test
demonstrated the greatest diagnostic efficacy among combined clinical tests. The combined
influence of Tinel's sign and the Ten test reported the highest sensitivity. specificity and
likelihood ratio among al1 cornbined tests. The Ten test is a sensibility test used to evaluate
sensory enervation on the palrnar side of the symptomatic hand. unlike Tinel's sign that
p~ovokes paresthesia in the median nerve distribution of the han& The Ten test positive
criterion for CTS in the current study was identified as patient hand sensibility values cl0 in
at l e s t three of the thumb, index, rniddle and ring fingers. Dissimilar to Tinel's sign.
Phalen's test combined with the Ten test indicated a high degree of sensitivity (724).
However. Phalen's test combined with the Ten test did not demonstrate significant
agreement with a confirmed diagnosis for carpal tunnel syndrome. in part due to a low
degree of specificity (37%).
Katz and coIleagues (199ûc) reported that the combined effect of Phden's test and
Tinel's sign decreased sensitivity and increased specificity compared to their respective
individual cl inical results. This pattern was not supported in the current study . Sensitivity
and specificity from the combined influence of Tinel's sign with either the Ten test or
Phalen's test was lower than individual values for each of these tests. This pattem could
suggest that combining clinicai test outcornes increase the probability of false-positive and
faise-negative rates. In generd. al1 combinations demonstrated tower diagnostic efficacy
compared to individual clinical test results. Furthemore, a similar study by O'Gradaigh and
Merry (2000) constructed a diagnostic algorithm based on Stirrat's SRQ, Phden's test and
Tinel's sign io both independently and in serial combination for deterrnining their xcuracy
in diagnosing carpal tunnel syndrome without reson to nerve conduction studies. They
found that the SRQ sensitivity of 92% decreased to 87% when combined with Phalen's test
and Tinel's sign. Conversely, individual sensitivity for Phalen's test (55%) and Tinel's sign
(72%) increased considerably when combined seridly with Stirrat's SRQ. O'Gradaigh and
Merry (3000) concluded that an algorithm with these clinical tests could confirm CTS
patients without electrophysiologic studies. The current study incorporated Stirrat's SRQ as
a composite with nerve conduction studies as the gold standard, whereas O'Gradaigh and
Merry (2000) used the SRQ as a clinicd test. Furthemore, the sensitivities of the cornbined
influence of Tinel's sign with either Phalen's test (738) or the Ten test (734) does not
completely agree with that of O'Gradaigh and Merry (2000). Therefore, the current study
does not entirely support the conclusions made by O'Gradaigh and Merry (2000), despite the
overall strength of Tinel's sign combined with either the Ten test or Phalen's test. Therefore,
the combination of Tinel's sign with either Phalen's test or the Ten test would be valuable
crinicd tests in supponing the resuIts of nerve conduction studies in assisiing a physician
accurately diagnosing carpal tunnel syndrome.
5.4 Limitations
A high prevalence rate, an imperfect gold standard, non-randomized clinical test
order and neglect in evaluating other recognized CTS clinical tests were three limitations
identified in the current study. Overail prevalence of subject hands with a confirmed
diagnosis for carpal tunnel syndrome was 62% in the current study and is consistent with the
Iiterature (Buch-Jaeger and Foucher. 1994). Individual prevalence rates in Toronto (42%)
and Thunder Bay (7 1%) varied significantly despite being within range of CTS subjects
diagnosed by hand surgeons (Katz et al.. 1990b. c). A large majority of CTS subject hands
in the current study reported a high severity of discomfon (median pain score=7+1) on the
10-point pain scale and frequency of symptorns >6 times daily. which is indicative of
moderate to severe carpal tunnel syndrome (Table 4.8). Katz and colleagues ( 199 1) suggest
that a large number of patients suffering frorn severe carpal tunnel syndrome cm contribute
to increasing sensitivity of clinical tests (Katz et al., 1991). However, the overall sensitivity
values of the clinicd tests in the current study were within range of the majority reported in
the Iiterature.
WhiIe nerve conduction studies are a recognized component in confirming a
diagnosis for carpal tunnel syndrome. false negative (Grundberg et al., 1983) and false
positive (Redrnond and Rimer. 1988) rates have k e n reported. Given the documented
limitations of fdse positive and false negative rates. it could therefore be potentially
recognized as an irnperfect gold standard (Rempel et al. 1998). Knapp and Miller (1992)
suggest that cornparison with an imperfect gold standard rnay Iead to an inaccurate judgment
that the clinical test of interest is wone. when it is acnially better. In the current study
context, this would suggest that the high degree of sensitivity. specificity and likelihood
ratio of these independent and combined clinical tests rnay yield results that rival those
obtained by electrodiagnosis in patients suspected of carpal tunnel syndrome (Rempel et al.,
1998). OtGradaigh and Merry (2000) found that an algorithm requiring clinical tests as the
confirmatory test in diagnosing carpal tunnel syndrome is rnost valuable, regardless of nerve
conduction studies. Furthermore. they suggest that a diagnosis based on clinical tests
without nsrve conduction studies would contribute to a more expeditious treatment.
Stirrat's SQR was important in controlling for a false positive electrodiagnosis in the
current study since al1 confirmed CTS hands required classic or probable symptorns (Katz et
al.. 1990a). However. Stirrat's SRQ did demonstrate inconsistencies with the nerve
conduction studies. This was particularly true in subjects who reported trivial or no
symptoms. but indicated a positive nerve conduction evaluation. Rempel and colleagues
(1998) consider these patients to have "silent carpal tunnel syndrome". The clinicd
presentation in these 29 subjects was also inconsistent. Positive clinical test results utilizing
Tinel's sign (38%), Phden's test (59%). the Ten test (48%) and the pressure provocative test
(59%) were found in only a moderate number of subjects. Furthemore. combined positive
results from the four clinical tests were found in 38% (1 1 of 29) of these silent CTS subjects.
It can be speculated that these 1 1 subject hands may have a mild form of carpal tunnel
syndrome. Nevertheless, Stirrat's SRQ has dernonstrated strong diagnostic validity as an
independent clinical tool (Katz et al., 1990a) or cornbined with nerve conduction studies
(Gunnarsson et al., 1997) in confirming a diagnosis in patients with carpal tunnel syndrome.
Furthemore, Stirrat's SRQ indicated a signifiant correlation with reported CTS symptoms.
including numbness, tingling and pain. in the current study. Rempel and colleagues (1998)
suggest that classic or probable symptoms according to Stirrat's questionnaire combined
with positive nerve conduction studies should be adopted as the criteria for screening and
diagnostic purposes in future population and clinical investigations. respectively.
The effect of test order in the administration of the clinical tests in the current study
was not considered. Each test was conducted in a non-randornized order including. Phalen's
test, the pressure provocative test. the Ten test and Tinel's sign. Each test was separated by a
1 -minute interval to control for residual syrnptoms. Furthemore. the current study proposed
to control for residual symptoms in those subjects that did present symptomatology following
the 1-minute interval. The current study did not report any residual symptoms following the
clinical tests suggesting that a 1 -minute recovery was sufficient in eliminating relative
symptoms following provocative and sensory clinical tests. Nevenheless. test order was not
randornized in the current study and therefore must be recognized as a potentid limitation.
Finaily, the current study examined the efficacy of only four clinical tests in
diagnosing carpal tunnel syndrome. Comparative studies have adopted different or a larger
batte~y of clinical tests (Buch-Jaeger et al-. 1994. de Krom et ai., 1990, De Smet, et al.,
1995). Additional clinical tests would have provided more individual and combined utility
measures that were not identified in the current study. Phalen's test. Tinel's sign and the
pressure provocative tests were selected because they are three commoniy utilized clinical
tests identified in the literature that have demonstrated inconsistent utility measures. and
therefore wanant further investigation. Furthermore. the Ten test was selected based on the
fact that it is a reasonably novel clinical tesr requiring expanded research in determining
positivity criterion as well as overall efficacy in diagnosing carpal tunnel syndrome.
CHAPTER VI
CONCLUSION
6.1 Conclusions
The following general conclusions can be drawn based on the study results:
Tinel's sign. Phalen's test and the Ten test are efficacious clinical tests in the diagnosis of
carpal tunnel syndrome.
Tinel's sign combined with either the Ten test or Phalen's test demonstrated strong
accuracy in confirming a diagnosis for carpal tunnel syndrome.
The pressure provocative test is not an efficacious clinical test either independently or
combined with Tinel's sign. Phalen's test or the Ten test in the diagnosis of carpai tunnel
syndrome.
A positivity criterion for carpal tunnel syndrome was identified for the Ten test as patient
hand sensibility values 4 0 in at least three of the thumb. index. middle and ring fingers.
The Ten test proved to be an accurate clinical test with a sensitivity. specificity and
Iikelihood ratio that rival those obtained by traditional clinical tests, including Tinel's
sign and Phalen's test.
6.2 Future research considerations
Future research is needed to confirm the diagnostic utility of these independent and
combined clinical tests in less prevdent settings, including general practitioner clinics and
occupational worksites. Tetro and colleagues (1998) indicated that studies including only
9 3
patients referred with a suspicion of carpal tunnel syndrome. such as the current study. are
vulnerable to spectrum bias. Therefore, including patients with a more arnbiguous
presentation or less severe symptorns of carpal tunnel syndrome may change the
performance outcome of clinicai tests. Katz et al. 11990~) concluded that it would be
especially useful if clinical tests could diagnose cohorts. such as occupational workers or
outpatients of primary heal th providers, w hom can be effective1 y treated without nerve
conduction studies. Administering Tinel's sign, Phalen's test and the Ten test in a
population-based setting by less experienced physician's or occupational health workers
should not be a targe concem. considenng the ease and robust nature of these three clinicd
tests.
Buch-Jaeger and Foucher (1994) suggest that clinical tests rre ü popular cornponent
in diagnosing carpai tunnel syndrome due to the financial swings compared to the more
extensive costs with respect to time and equiprnent afforded by an electrodiagnostic
evaluation. To date. no study has examined whether clinical tests are financially beneficial
compared to electrophysiological examinations in diagnosing c q a l tunnel syndrome.
Therefore, a greater undentanding of the monetary impact of adopting clinical tests instead
of newe conduction studies would prouide important information for surgeons in deciding
on the most appropriate diagnostic strategy.
This study demonstrated the overail efficacy of Tinel's sign combined with either the
Ten test or Phalen's test in diagnosing carpal tunnel syndrome. Therefore, the serial
combination of these tests would be valuable in supporting the results of nerve conduction
studies in assisting a physician accurately diagnose carpal tunnel syndrome.
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'P.
II"' ci 2 - cl
n II) n II)
Cl
Appendk 2 - Sample Size Estimation
The following sample size formula has been selected to provide valid
cohon of patients suspected of carpal tunnel syndrome referred for clinical
sample size formula used for calculüting n is:
inferences from a
examination. The
The present study inrended to accept a level of 95% confidence tZa) and maximum
error of 10%. The table below present a 95% confidence level and degrees of error ranging
from 5 to 108. Initial population size (N) was set at 500. which represents the total number
of patients expected to be referred at both dinical practices involved in this study. Expected
proportions (piq) { p = proportion of 'CTS: q = proportion of -CTS} for prevalence (0.33).
sensitivity (0.62) and specificity (.33) for the carpai compression test were seiected from De
Smet et al. ( 1995) for a conservative estimation of sample size.
I Initial Population
t N=500)
Expccicd Proportion
( ~ * 9 )
Pcrccnt Contidence
(ZU)
Perçcnt Srimple Error Sire c C 4 , in )
Prevalence (0.33) 0.22 1 1
Sensitivity t 0.62)
tippendrr 3 - Posf-hoc Sample Size Determination
Posr-hoc sample size determination outlined below was calculated based on a 95%
confidence level and degrees of error ranging from 5 to 10%. The initial population size (N)
of 500 remained the same. which represents the total number of patients referred to both
clinical practices involved in this study over the course of one year. However. expected
proportions (p*q) for prevalence (0.62). sensitivity (0.76) and speci ficit y ( . 3 4 selected from
the least accurate clinical test study (Le.. the pressure provocative test) in the current wcre
different from the previous sarnple size calculations based on the proponions reponed by De
Smet et al.. ( 1995). Therefore. a pusr-hoc sample size determination was required.
Initial Population ( N=SOO )
Expec ted Proportion
(PW
Percent Con fidencc
(Za)
Percent Sampfe Error Size (96) (n
Prevalcncc 0.62) 0.2356
Sensitivtty (0.76)
Specificity (0.33)
Appendix 4 - Logistic Procedures
STEP # 1 Surgeon ( 1 Encounter)
Identify the patient as a potential subject by a referral letter outlining hand symptoms such as numbness. tingfing, pain, and decreased sensat~on i n either or both hands. Deterrnine if patient is 218 y e m old. has hiid CTS surgery or hand electrodiagnosis prior this appointment. Explain the research protocol to the patient outlining that al l clinical and electrodiagnosis will be perforrned regardless and that essentidly they would merely be permitting the research team access to the data. which will be recording with strict anonymity of the patient. Ask the patient if they have any questions regarding your instructions. Patients willing to partake in the research will leave the examination room and go to the surgeon's administrative assistant.
STEP #2 Surgeon's Administrative Assistant ( 1 '' Encounter)
Provide coded serial number on the Demographic Questionnaire and Stirrat's Syrnptorn Reponing Questionnaire for the patient. Provide the patient with a folder that contains the following: Information sheet (Tell the patient that thry can keep this sheet): 2 copies of the Lettcr of Informed Consent (Tell the patient to complete both sheets): Demographic Questionnaire (Tell the patient to complete this sheet and to pay panicular attention to the correct hand with this questionnaire): Symptorn Reporting Questionnaire (Tell the patient to complete this sheet and to pay particular attention to the correct hand with the diagram): instnict the patient to complete the 4 sheets and return them to her. Ask the patient if they have any questions regarding your instn~ctions.
STEP #3 Patient
1. Patient completes the 4 sheets and returns to surgeon's administrative assistant. 2. Administrative assistant adds the Surgeon's Clinicd Report to the file and escorts the
patient to a clinical room.
STEP #J Surgeon (znd Encounter)
1 . Signs both letters of informed consent as the "Investigator signature" and "date" and instructs the patient to keep one of the copies for iheir own personal record.
2 Complete the Surgeon's Clinical Repon by administering the clinical tests i n the order that they are presented on the clinical test sheet.
3. Do not treat the patient for the hand symptoms; provide only behaviour modification strategies or splinting for the patient.
4. Ask the patient if they have any questions regarding their upcuming visit to the physiatrist.
STEP #5 Surgeon's Administrative Assistant (znd Encounter)
1. Surgeon escorts the patient back to administrative assistant who receives the patient file from the surgeon and places it in a locked filing cabinet: separate from the coded seriül datasheet.
7. Administrative assistant books an appointment for the patient wiih the Physiatrist. 3. Administrative assistant sends a copy of surgeon's clinical report to physiatrist with a
"red sticker" on the top right hand corner indicating chat this is a research subject dong wi th the "Electrodiagnostic Report".
4. The Electrodiagnostic Report will have a 3-M "sticky" with the patient's name posted over the serial number.
STEP #5 Physiatrist
1. Physiatrist receives Ietter from hand surgeon with the Electrodiagnostic Report. 2. Aside from the routine electrodiagnostic tests. the physiatnst will administer the
following tests to both hands in this order: Segmenta1 sensory conduction test:
8 7-cm rnotor distal latency test: 3. Check to see that you have completed al1 questions on both sides of the
Electrodiagnostic report. 4. Mail the Electrodiagnostic report bück to surgeon's administrative assistant.
STEP #6 Surgeon's Administrative Assistant (3"1 Encounter)
1. Administrative assistant receives the Electrodiagnostic Report from the physiatrist and completes the subject file by adding them with the original 4 sheets.
1. Administrative assistant checks that al1 datasheets have been returned to complete the file and checks each item off on the coded serial data sheet as well as the individual checklist found on the inside of each subject file jacket.
3. AI1 subject files are kept in a locked filing cabinet.
Appendix 5 - In formation Sheet (Mount Sinai Hospital)
TitZe ofproject: Deterrnining the Usefulness of Clinicai Tests in the Diagnosis of Carpal Tunnel Syndrome.
In vestigutors: Brent E . Faught, 1M.Sc. Ph.D. Candidate. Depanment of Community Wealth. University of Toronto
Dr. Nancy McKee, M.D. Professor. The moun nt Sinai Hospital. Faculty of Medicine, University of Toronto.
Purpose of the study: The purpose of this study is to determine the usefulness of clinical tests in the diagnosis of
carpal tunnel syndrome.
Subjects: A sampie of patients suspected of sufiring from carpal tunnel syndrome referred for tùrther
assessrnent to Dr. Nancy McKee at the Division of Plastic Surgery. The Mount Sinai Hospital wili form the base of subjects for this study. Patients will be restricted to IS years or older.
What dues participation in this study involve? You will be requested to complete two items. The first item is the Demographics
Questionnaire. which focuses on persona1 information. Feel free to answer al1 questions. as you will not be required to identify yourself by name. A coded seriai number will be assigned to you at the outset of the study. so that your name wiIl remain confidential. Your patient record will be referred to by subject serial number only. The second item to be compieted by the patient is the Symptom Reporting Questionnaire as it relates to the symptorns that you are experiencing in your handts). You will then undergo a clinicd exnmination inciuding four tests conducred by Dr. Nancy McKee that will take approximately 15 minutes. Finally, you will undergo two nerve conduction examinations that will include a total of ten slectrical shocks to each hand causing minimai discomfon. The electrical shocks that you will experience are similar to that of static electricity. which you can receive while removing clothes from a drying machine. The nerve conduction enamination will take approximately 30 minutes. The four dinical tests and the nerve conduction examination are al1 potentïally a part of a thorough evaluation for carpal tunnel syndronie, You will be required to complete a consent form pnor to the study. You may. at any time. revoke your consent and withdraw from the study without fear of recourse by any means.
Risks and Benefis: There are no known risks or direct benefits in participating in this study. Patients will make
an appointment with Dr. Nancy McKee following the nerve conduction evahation for a finai diagnostic briefing regarding their medical condition. There is no remuneration for participation. Ftirrher inq~iiries shorild be made tu: Brent E. Faitght. Department of Cornrnuniy Health Sciences, Brock uni ver si^, St. Catharines. ON, t2S 3A 1. Tele: 905-688-5550 f ext. 3586). Far: 905-688-8954, Email: ht-rnr@ hrtlckrt.cu.
Appendix 6 - Letter of Informed Consent
Title: Deterrnining the Usefulness of Clinical Tests in the Diagnosis of Carpal Tunnel Syndrome.
Principal Investigatoc Brent E . Faught ( Department of Cornmunity Hsalth. Lrniversity of Toronto) Co-lnvesiigator: Dr. Nancy McKee (Division of Plastics. The Mount Sinai Hospital)
I (full name) have read and understand the information sheet for the above study. 1 have been given a copy of this information shert to kcep. The study and the researcher's expcictations of me have been explained to me in detail. and 1 have had the opportunity to rtsk any questions that 1 have regarding this project. 1 thereby volunteer to participate as a test subject in this study that wilI examine the effectiveness of clinical procedures in diagnosing a condition called carpal tunneI syndrome. 1 understand that there are no known direct risk factors or direct benefits from participation in this study.
1 am aware that 1 will be requested to complete a Dernographics Questionnaire regarding personal information and a Symptom Reporting Questionnaire as it relates to carpal tunnel syndrome.
I understand that I will undergo a clinical examination including four provocative tests including the pressure provocative test, Phalen's wrist flexion test, the Ten test and Tinel's sign.
1 understand that 1 will undergo two nerve conduction examinations that will include a total of ten electrical shocks to each hand causing minimal discomfort. The elect~icrtl shocks that I will experience are similar to that of static electricity. which 1 can receive while removing ctothes from a drying machine.
1 acknowledge that 1 have read this form and 1 understand that my consent is voluntan, and has been given under circurnstances in which I c m exercise free power of choice. 1 have been informed that 1 may. at any time. revoke rny consent and withdraw from the study without fear of recourse by any means. Furthemore, 1 understand that my involvernent tn this research project will be kept in strict confidence between the researcher and myself.
Patient Signature:
hvestigator Signature:
Date:
AppendUc 7 - Dernographies Questionnaire
Your answers to these questions are rcquired. Please answer al1 questions completely and pnnt clearly so that recognition is possible. Notice that Question #4 CO 8 have been repeated twice in case you suffer from hand symptoms in both your hands. However, if you only suffer from symptoms in one hmd, oniy fil1 out the necessriry information for that particular hmd.
Date: Age: ( y cars) Gender: M or F
Height: (inches)/ (cm) Weight: clbs.) / (kg)
......................................*..........................*,.......,.....*...............................................................,.....,....
1 . Please circle the hand that you predominantly use for everyday activity? L R Both
2. What is your current occupation? ( Plem print clearly !)
3. Do your hand symptoms restrict your performance at work or home? Yes 3 No 3
4. i) What type of symptoms do you feel in your rtght wristlhand? Numbness Tingling Pain Decreased Sensation Other:
3 J 2 3 (Speciîj)
i i ) What type of symptoms do you feel in your Ieft wrist/hand? Yumbness Tingling Pain Decreased Sensation Other:
II 3 1 3
5. i ) How long have you been experiencing these syrnptoms in your right wristhand?
ii) How long have you been experiencing these symptoms in your left wristlhand?
6. i ) Circle the number on the discomfort scde that best describes the intensity of symptom discomfort in your right wristhand.
Minimal 1 2 3 4 5 6 7 S 9 10 The musr dixcornfin discom fort I I I 1 I t I I I I yoti c m inin-eine!
i i ) Circle the number on the discornfort scds that best describes the intensity of symptom discomfort in your left wristjhand.
Minimal 1 7 3 3 5 6 7 8 9 10 Tircniostdiscomfon <iisconrfort 1 l I I I I I l I !.ou cun iniagirrr!
7. i ) How frequent do you experience the symptoms in your rigirr wrist/hand over the course of one day?
/ day .
ii) How frequent do you experience the symptoms in your lefi wristlhünd over the course of one day?
/ day.
8. i ) Do symptoms in your right wridhand cause you to wake at night?
YES 2
i i ) Do symptoms in your left wrisdhand cause you to wake at night?
YES '3
9. Are you currently applying or receiving workers' compensation for this wrist/hand problem?
YES 3
Thank you for cornpietirtg the Demographics Questionnaire!
Appendix 8 - Symptom Reporting Questionnaire
Plerise fil1 out this diasram as accurately as possible. using the symbols provided klow to describe your hand and limb symptorns as part of the evalurition. Notice that the diagram below illustrates both the front and back of the teft and nght hmds and arrns. Be as clear and precise as possible when drawing in the symbols so that an accurate diagnosis of your condition can be determined.
Pain Tinghg Otlzer ( , Sensariori
LRfr Hand Side Right Hand Side
Appendix 9 - Surgeon's Clinical Report
1. 1s the patient directly associated/suffer with any of the following conditions? 'r Rheumatoid arthritis YES 3 1V0 3 3. Prepant YES II NO LI 'i Hypothyroidisrn YES 13 N O 3 ;i. Rend friilure YES *I3 ,VO 3 ;i Xcromegaly YES 3 LVU 3 i Gout YES 2 .VO 3 > iMultiplemyeloma YES 3 'VO J
Amyloidosis YES 3 ,VU 3 > Diabetes YES 2 LVO 3 i- Wtist fracture (Right hand) YES 3 NO 3 3. Wrist fracture (Left hand) YES 2 ,VU 3 i Other (Specify )
2. Does this patient have a positive Phalen's test? ( R) NO 3 YES 23 timc: sec residual: 2 (L) NO 3 YES 2 time: sec residual: 3
3. Does this patient have a positive PPT? (R) N O 3 YES LI time: sec residual: 12 (L) NO Ci YES 3 time: sec residual: 3
4. What is the patient's score on the T m test for the:
(right) thumb /IO (right) index /IO (right) middle /10 (right) ring / I O (righti baby /IO
(left) thumb /IO (left) index /IO ( left) middle /IO (left) ring /IO (left) baby /1 O
( left) 1 - 7 3 3 3 cl
N e c a s q if percussion t 10 3 are qutvocal
6. Based on your complete clinical examination. what is your diagnostic consensus of carpal tunnei syndrome for this patient3
(right) ClasvicCTS Probable CTS Possible CTS b'nlikely CTS C1 'LI 3 LI
(left) C h s i c CTS Probable CTS Possible CTS Untikely CTS 3 9 Z1 3
Appendix 10 - Electrodiagnostic Report
1 . Circle the hand in which you are assessing? Right Left
2. Please record the sensory nerve conduction values beside each of the 9 stimulation sites on the fines provided.
Sensory Conduction Values
ms. ( -6 cm) ms. ( - 5 cm) ms. (-4 cm) ms. ( - 3 cm) ml;. ( -2 c m ) ms. ( - 1 cm) ms. (DWC) ms. ( + I cm) ms. (+2 cm)
3. What is the rnotor distal latency based on the 7-cm nerve conduction study? ms.
4. Based on the EMG results; this patient's hand is/has: normal Zl / abnomid 2 not denervated 2 / denervated 53 no decreased recruitment 2 / decreased recruitment 3
5. 1s their evidence of any other neuropathy? YES 2
6. If you answered YES to Question #5; please specify the neuropathy?
7. Bmed on your complete electrodiagnosis. what is your diagnostic consensus of carpaI tunnel syndrome for this patient?
Classic CTS Probable CTS Possible CTS 3 3 Ll
Unlikelj CTS 3
AppendU: 2 I - Stirrat 's Symptom Response Diagnostic Report
Based on this patient's response to Stimr's Symptom Rsponing Questionnaire; I would classify this individual as:
( right ) Classic CTS 2
Probable CTS Possible CTS Unlikely CTS 3 3 3
(left) Classic CTS Probable CTS 3 3
Possible CTS Unlikely CTS ZI 2
Appendix 12 - Data Management
- - -
Level of Coded Açronym Variable Name ~Measurement Format Values
ID serial
location
are pendcr
hcipht wcight pre hand
occupation
ordinal nominal
nominal
interval nominal
intcrval interval nominal
nominal
Thibcn Surgiçal Clinic Mount Sinai Hospital Thunder Bay Toronto y cars malt fcmalc meters kilotmms left ri@ ambidcxtrous (both hands) Houseclerini ng Uncmploycd Rctircd iMedical Lab Tcchnoiugist Paper Mill workcr Mining Shift Manager Property ~Manriger RCLr Operator File CIerk Welder Fitter Lab Personal Technician Reccptionist / Secrctary Floor Covcring Estimator Elcçtrical Finisher Crüpenter Business Owner 1 Store Owner Director 1 Art Director Waitress Tacher Office Workcr Resourcc Technician .Mec hanic Library Technician Accountant S y stems Programmer Software Engineer Administration Assistant Investment Banking CSR at Bell P r o g m Manager Bone & Tissue Bank Specialist Repistered Practical Nurse Charnber Maid Computer Writer
DQ- 3 rcstrict
DQ4.1 nurn bness
DQ-4.2 tingle
DQ-4.3 pain
DQ-4.4 decsensa
DQ-4.5 othersymp
DQ hrindreport
DQ-5 duration DQ-6 intensity
DQ-7 freq uent
DQ-8 nocturnl
SCR-1.1 conl(arthntis)
SCR- 1.7 con2 (pregnant)
nomi na1
nominal
nominal
nominal
nomi na1
no mi na1
nominal
Eiectrician Stock Shetves Cashier Shrift Attendant Operate C o o k c ~ 1 Cook Sales pers on Daycare Provider Loitcier Operdtor Truck Driver Clerical Chemical Pracess Operator Designer 1 Ceramic Xrtist Ticket Collecter Real Estatc Agent Painter / Scams tress Practice Devclopment Supervisor ycs no Yes no VCS
no ves no ycs no tightness Ioss of strengh/wcrikness stcad y pain/sore sleeping cold loss of control/droppin~ things difficult to close/opt.n hand nervous twist swelling right left years minimal discornfort
maximal discornfort nominal 1 to 1 times a day
3 to 4 times a da! 5 to 6 times a day >6 times ri day
nominal Yes no
nominai Y es no
nominal Yes no
SCR- 1 -3
SCR- 1 .4
SCR- 1.5
SCR- 1.6
SCR- I .7
SCR- 1 .S
SCR- 1 .r)
SCR-1-10
SCR-1.1 I
SCR- 1.12
SCR-4.1 SCR-4.2 SCR-4.3 SCR-4.4 SCR4.5 SCR
SCR
con3 (hypothyroid)
con4 (rend )
con5 (acrornegaly )
con6 (gout)
con7 (myeloma)
con8 (amy loid)
con9 (diabetes
con i0 (Rt. wrist frac J
con 1 1 (Lt. wrist frac)
con 12 (other)
thumb index middle r i n ~ baby Classify-M 1
I T h I 1 (Tm Test M 1 )
nominal
nominal
nominal
nominal
nominal
nominal
nominal
nominal
nominal
nominal
nominal
interval nominal
nominal
interval nominal
ratio ratio ratio ntio ratio no minal
nominal
Yes no yes no y es no yes no yes no yes no VCS
no yes no Y es no Amputation left baby finger Lung cancer Laceration @ wrist Hypertension Ostcoarthri tis Myocardial int'arction Hip replacement Poly my algia Fibromy rzlgia Hem trouble Depression positive CTS negativc CTS seconds yes no CTS positive CTS negative seconds yes no / 10 / 10 110 / 10 110 Classification I Classification 11 Classification III Classification iV CTS positive CTS negative
SCR
SCR
SCR SCR
SCR-S. 1 SCR-3.2 SCR-5.3
SCR-6
SRQ- 1
EDR- I
Tinell Tinel2 Tinel
clindiag
Scvneg6 Scvneg5 ScvnegJ Scvncg3 Scvneg2 Scvneg l Scvdwc Scvpcis 1 ScvposZ SCV65 SCVSJ SCVJ3 SCV32 SCVZ 1 SCViO SCVO l SCVIZ SCVlatenc y
EDR SCV
nominal
nominal
interval nominal
ratio ratio nominal
nominal
nominal
nominal
interval interval interval interval inierval interval intcrval interval interval intcrval interval intemal interval interval interval interval interval nominal
nominal
Classification 1 Classification II Classification III Classification IV Classification V CTS positive CTS ncgative sum score (ihurnb T indra - riuddlc - nng)
CTS positive CTS nepativc /3 /3 CTS posttrvtz CTS ncgritivc Classic CTS Probable Ci's Possible C T S Unlikcly CTS Classic CTS Probable CTS Possible CTS Unlikely C T S right lcft scnsory vclocity u -6 (ms. j scnsory velocity e -5 (ms. J
sensory velocity @ -4 (m.) sensory velocity @ -3 ( m . ) sensory velocity @ -2 (ms. i scnsory velocity @ - 1 (ms.) sensory velocity @ DWC i ms. ) scnsory velocity e + l (rns.1 sensory velocit y ca +2 ( ms. i scnsory velocity 1 c -6 ro -5 ( ms. sensory velocity 1 @ -5 to 4 (ms.) sensory velocity 1 GC -4 to -3 c ms., sensory vclocity 1 @ -3 to -2 1 ms.) sensory velocity 1 @ -2. to - 1 ( ms.1 sensory vefocity 1 ~m -1 to DWC (ms. J
sensory velocity 1 @ DWC to + 1 c ms. i sensory velocity 1 @ + I to t 2 (ms.) no latency latency between -6 and -5 latency between -5 and 1 latency between 4 and -3 latency between -3 and -2 latency between -2 and - t latency between - 1 and DWC Iatency between DWC and + 1 Iatency between + 1 and +2 CTS positive (ie. 2 0.3 ms.) CTS negative ( ie.c 0.3 ms.)
MDLscore MDL
Emp 1
ocherneurop
CTS
Uni-bilateral
interval nominal
nomi na1
nominal
nominal
nominal
nominal nominal
nominal
nominal
rnotor velocity (mseç) CTS positive f ic. 3 3.0 ms. ) CTS negative (ie.< 3.0 ms.) normal abnormal non denervated abnormal no decreued recruitment decreased recruitmcn t VCS
no
CIrissic C T S Probable CTS Possible CTS Unli kcl y CTS CTS positive ~ S R Q 51 - SCV=I I MDLI i
CTS negative ~ S R Q >1) CTS negative (bilateral ) CTS positive ( unilaterril) CTS positive (bilatcral ) CTS negative t only I hand tcsted J
CTS positive (only 1 hand tcsted) = 4
DQ= Dernographic Qursironnarc; SCR= Surgeon's Clinicd Report: SRQ= Symptom Rrponing Qurstionnarr: EDR= Elrctrdiagnostic Rcpan
AppendLx 13 - Ten Test Models ROC Curve Analysis
Ten Test Model 1
Class Criteria
1 The patient bas a score <IO in the index. middle and ring fingers. [I The patient ha a score <IO in two of the index. middle or ring tïngers. III The patient has a score < 10 in one of the index. middle or ring fïngers. IV The patient ha'; a score of 10 in the index, middle and ring fingers.
Mode1 1 TF FP FLV TX Sens Fake- False+ Spec Likelilrood R (CI) C h s B C D MA+C) C/fA+C) B/I B+D) D/( B+D) fSens/l-Spec)
1 71 24 36 JO 0.6667 0.3333 0.3750 0.6250 1 .y778 1 1.62- 1.92, 11 96 32 12 32 0.8889 0.1 1 1 1 0.500O C.5000 1.7778 i I .61- 1.921 III 97 37 1 I 27 0.898 1 O. 1019 9.578 1 0.42 19 1.5536 t 1.40-1.70 IV { O S 64 O tl 1.0000 0.Q000 1.0000 0.0000 1 .OWO
Sensitivity
0.00 0.25 0.50 0.75 1 .O0
1 -Speci ficity
Ten test model 1 ROC curve
Ten Test Mode12
I The patient has a score cl0 in the rhumb, index. middle and ring fingers. II The patient has a score 4 0 in three o f the thumb. index. middle or ring fingers. III The patient has a score 4 0 in two of the thumb. index. middle or ring fingen. IV The patient has a score 4 0 in one o f the thumb, index, middle or ring fingers. V The patient has a score of 10 in the thumb. index. middle and ring fingen.
Model 2 TP FP F.V TN Sens Fcrlse- Fuise+ Spec Likeliiiuod R (Cf) CIass A B C D M A +C) C/fA +Cl BA B+D) D/IB+D) fSens/l -Spec)
Sensitivity
Ten test mode1 2 ROC curve
139
Ten Test Model 3 (Aggregate sum score of thumb, index, rniddle and ring fingers)
Mode1 3 TP FP FX TA' Sens Faise- Faise+ Spec Likelihood R ICI) Scores A B C D .UfA+C) C/(A+C) B/fB+D) D/fB+D) (Sendi-Spec)
Sensitivity
0.00 0.25 0.50 0.75 1 .O0
1 Specificity
Ten test mode1 3 ROC curve
Ten Test Individual Finger ROC Curve Analysis
Thumb Finger TP FP FN TIV Sens Fuise- False+ Spec tikelihood Ratio Sensibiliry A B C D A C C/(rl+C) B/(B+D) D/(B+D) fSens/l-Spec)
Index Finger TP FP FN TN Sens Fuise- F&e+ Spec Likelihood Ratio Sensibility B C D U(A+C) C/(A +C) B/(B+DJ D/IB+D) (Sendl -Spec)
6 66 22 42 42 0.61 1 1 0.3889 O. 3438 0.6563 1.7778
7 79 13 29 -Il 0.73 15 0.2685 0.3594 0.6306 2.0354
8 94 31 I - i 31 0.8703 O. 1296 0.4844 0.5 156 1.7969
9 95 35 13 19 0.8796 O. 1204 0.5469 0.453 l 1 .Ci085
Middle Finger TP FP FIV TN Sens FaLe- FaLre+ Spec Likelihood Raiio Sensibility A B C D r V ( A 4 ) C/(A +C) B/(B+D) D/f B+D) f Sendl -Spec)
Ring Finger TP F P F N TN Sens Faise- FaLre+ Spec Likelihood Ratio Sensibitity A B C D M A +C) C/(A+C) B/f B+D) D/f B+D) f Sendl-Spec)
Additional Ten Test Models Based on Individual Finger ROC Curve Analysis
Ten Test Mode1 4
I The patient has a score of < 8 in the thumb and index fingers and a score of < 9 in the middle and ring fingers.
II The patient has a score of < 8 in either the thumb or index fingers and a score of < 9 in either the middle or ring fingers.
III The patient has a score of < 8 in either the thumb or index fingers or a score of < 9 in either the middle or ring fingers.
rV The patient has a score 2 8 in the thumb and index fingen and a score 2 9 in the middle and ring fingers.
Mudel 4 TP FP Fi;V TN Sens FatSe- False+ Spec Likelihood R (CI) Class B C D .-WA+C) C/fA+C) B/(B+D) D/(B+D) (Sens/[-Spec)
1 62 17 46 47 0.5741 0.4259 O. 2656 (1.7344 2.1615(2.02-2.30) 11 80 24 28 40 0.7407 0.2593 0.3750 0.6250 1.9752 ( 1.83-2.1 1 1 III 95 32 13 32 0.8796 0.1 2OJ 0.5000 0.5000 1.7592 i 1.61-1.89) IV 108 64 O O 1.0000 0.0000 1 .0000 0.0000 1.0000
Ten Test Mode1 5
I The patient meets the above criteria in three of the index. middle and ring fingers.
n The patient meets the above criteria in two of the index. middle and ring fingers.
III The patient meets the above criteria in one of the index. middle and ring fingers.
IV The patient meets none of the above cnteria in the index. middle and ring fingers.
Modei 5 TP FP FLV KV Sens Faise- Fuise+ Spec Likelihood R C I ) CIass A B C D A/(A +C) C/fA +Cl B/fB+D) D/f B+D) fSens/l-Spec)
1 67 19 41 45 0.6203 0.3796 0.2969 0.703 1 2.0896 t 1.94-2.22) II 82 77 16 37 0.7593 0.2407 0.42 19 0.578 1 1.7997 (1.64-1-94)
III 95 32 13 32 0.8796 O. 1203 0.5000 0.5000 1.7592 i 1.61-1.931 IV IO8 64 O O 1 .0000 0.0000 1 .0000 0.0000 1.0000
Appendix 14 - Sensitiviîy and Specificty Analysis of Individual and Combined Clinical Tests
Clinicrrl TP FP FN TN Sens Faise- False+ Spec LR Testfs) A B C D rV(A +C) C4.4 +C) B/f B+D) D/fB+D) ( S e n d l -Spec)
PT
PPT
TT
TS
TS+tT
TS+ PT
TT+PT
PT- Pm
TS+ PPT
PPT+T
TS+FT+ 77
TS+PT+ Pm
FT+TT+PPT
T S t r r + P P T
TS+ TT+ PT+ P P T
$1 -- 'ri
I 5
2.1
29
29
30
3 0
3 5
34
3 3
35
76
3 s
!P
Appendix 15 - Kappa Agreement Complete Statistical Analysis
Clinicd Test(s) Sensitivity (CI) Specificity (CI) Likelihood Ratio (CI) ZK
TS 0.79 (0.71 - 0.87) 0.65 (0.55 - 0.75) 2.22 (2.08 - 2.36, 5.70 t.
TT 0.87 (0.79 - 0.95) 0.52 (0.41 -0.63) 1.80 ( 1.66 - 1.94) 5.31 + PT 0.80 (0.72 - 0.88) 0.48 (0.37 - 0.59) 1.52 (1.38- 1.66) 3.72 +
PPT 0.76 (0.68 - 0.84) 0.34 i 0.23 - 0.45 1.15 t 1.01 - 1.29) 1.39
TS+ïT 0.73 (0.65 - 0.8 1 ) 0.50 (0.39 - 0.6 1 ) 1.46 (1.32- 1.60) 3.08 * TS+PT 0.73 (0.65 - 0.8 1 ) 0.46 (0.34 - 0.55) 1.36 (1.21 - 1.52) 2.57 + TT+PT 0.72 (0.64 - 0.80) 0.37 (0.26 - 0.48) 1.15 t 1.01 - 1.29) 1 .27
PT+PPT 0.72 (0.64 - 0.80) 0.30 (0.19-0.41) 1.03 (0.89- 1.17) 0.34
TS+PPT 0.68 (0.60 - 0.76) 0.32 (0.21 -0.43) 1.00 (0.86 - 1.14) -0.0 1
PfT+TT 0.69 i 0.6 1 - 0.77 i 0.25 (O. 15 - 0.35 i 0.91 (0.77-1.05) -0.90
TS+PT+TT 0.69 ( 0.6 1 - 0.77) 0.37 (0.25 - 0.49) 1.10 (0.96- 1.24) 0.88
TS+PT+PPT 0.68 (0.60 - 0.76) 0.30 (O. 19 - 0.4 1 ) 0.98 (0.84 - 1.12) - 0.30
PT+TT+PfT 0.66 (0.58 - 0.73) 0.21 (0.11 -0.31) 0.84 (0.70 - 0.98) - 1.7 1
TS+ïT+PPT 0.65 t 0.57 - 0.73) 0.23 CO. 13 - 0.33) 0.85 (0.7 1 - 0.99) - 1.62
TS+TT+PT+PPT 0.65 (0.57 - 0.73) 0.21 (0.11 -0.311 0.82 (0.68 - 0.96) - I .9J