Thumb Abduction Strength Measurement in Carpal Tunnel Syndrome

doi:10.1016/j.jhsa.2007.04.007

The Journal of Hand Surgery

Volume 32, Issue 6, July–August 2007, Pages 859-866

https://doi.org/10.1016/j.jhsa.2007.04.007 Get rights and content

Purpose

The strength of thumb abduction and index finger flexion was measured with a load cell mounted on a custom-made device. The resulting ratio (thumb-index ratio, or TIR) was used to diagnose carpal tunnel syndrome (CTS) and was compared with the gold standard (electrodiagnostic studies). The ratio was used as an internal control in each subject.

Methods

Sixty-one patients (80 hands) with a clinically and electrodiagnostically confirmed diagnosis of idiopathic CTS and a control group of 51 asymptomatic volunteers (102 hands) were evaluated. The strength of thumb abduction and index finger flexion was measured in standardized fashion in each hand three times, and the mean was taken to calculate TIR.

Results

Thumb-index ratio was statistically significant in differentiating between a CTS patient and a normal control. A TIR of 0.51 had a 98% specificity and a 92% positive predictive value for diagnosing CTS. Thumb-index ratio greater than 0.51 was neither sensitive nor specific for diagnosis of CTS. Twenty-four (30%) hands in the investigational group had a TIR ≤0.51 compared with 1 hand (1%) in the control group. There was a significant difference in the TIR between hands with a motor amplitude of ≤4.0 mV and those with an amplitude >4.0 mV.

Conclusions

Most patients with CTS do not appear to have notable weakness of thumb abduction strength. A TIR ≤0.51 had high specificity for differentiating between CTS and controls. However, the performance of this device needs to be evaluated in a general population of patients who present with signs and symptoms of CTS before it would be clinically applicable.

Type of study/level of evidence

Diagnostic III.

Section snippets

Materials and Methods

The institutional review board approved the human protocol for this study, and informed consent was obtained from all subjects.

Results

Data regarding age, TIR, absolute thumb strength, and electrodiagnostic parameters for each group are shown in Table 1.

Discussion

The objectives of this study were to determine whether there is a significant difference in the TIR between patients with CTS and asymptomatic controls and, if so, whether a threshold cutoff point can be determined to have high sensitivity and/or specificity for diagnosis of CTS. Our second objective was to find a correlation, if one exists, between the TIR and electrodiagnostic parameters of DML and amplitude. Both of these objectives were designed to answer the question whether thumb

References (17)

M.C. deKrom et al.
Efficacy of provocative tests for diagnosis of carpal tunnel syndrome
Lancet
(1990)
C.B. Novak et al.
Provocative sensory testing in carpal tunnel syndrome
J Hand Surg [Br]
(1992)
R.M. Szabo et al.
The value of diagnostic testing in carpal tunnel syndrome
J Hand Surg [Am]
(1999)
C.A. Crosby et al.
Hand strength: normative values
J Hand Surg [Am]
(1994)
J.R. Boatright et al.
The effects of low median nerve block on thumb abduction strength
J Hand Surg [Am]
(1997)
J.R. Boatright et al.
Measurement of thumb abduction strength: normatic data and a comparison with grip and pinch strength
J Hand Surg [Am]
(1997)
W.P. Cooney et al.
Electromyographic analysis of the thumb: a study of isometric forces in pinch and grasp
J Hand Surg [Am]
(1985)
N. Buch-Jaeger et al.
Correlation of clinical signs with nerve condution tests in the diagnosis of carpal tunnel syndrome
J Hand Surg [Br]
(1994)

There are more references available in the full text version of this article.

Cited by (12)

The value of provocative tests for the wrist and elbow: A literature review
2013, Journal of Hand Therapy
Citation Excerpt :
Three tests met our requirements to be considered not recommended. The ratio of thumb abduction strength to the index finger42 requires special testing apparatus that is not available to the clinician. A limitation of the pivot shift test for posterolateral instability of elbow test is that it requires general anesthesia to optimize accuracy.38
To describe and determine the usefulness of provocative tests for the wrist and elbow a literature search was performed. A total of 31 diagnostic studies were identified, assessed, and ranked. The highest ranking tests had a mean positive likelihood ratio of ≥2.0, or a mean negative likelihood ratio of ≤0.5, from more than one study. The highly recommended tests were found to be the Phalen's, Tinel's test for carpal tunnel and cubital tunnel, and modified compression test, scaphoid shift test, and elbow flexion test. A total of 14 tests met our requirements to be considered a recommended test. A greater number of provocative tests either do not have adequate data to support their usefulness or their clinical utility has not been assessed. This information may assist hand therapists in choosing which provocative tests are considered clinically useful in improving the probability of the presence or absence of pathology in the hand, wrist, and elbow.
NA.
Intrarater and interrater reliability of a hand-held dynamometric technique to quantify palmar thumb abduction strength in individuals with and without carpal tunnel syndrome
2018, Journal of Hand Therapy
Citation Excerpt :
Variability in the different handheld dynamometric testing methods for assessing thumb abduction (APB) strength reported in the literature is vast with differing positioning of the thumb, the rest of the hand, and upper extremity,2,3,9,17,18,20,22 differing contact points for the dynamometric device,2,9
Clinical measurement.
Individuals with carpal tunnel syndrome (CTS) sometimes exhibit weakness of palmar abduction strength (TAS). Reliable assessment of this strength in both subjects with and without CTS with the commonly available Microfet 2 is not known.
The purpose of this study was to determine the intrarater and interrater reliabilities of a handheld dynamometric (HHD) method to assess TAS in individuals with and without CTS using the commercially available MicroFET2 and to examine the association between TAS in individuals with CTS and the Carpal Tunnel Symptom Questionnaire (CTSQ) scores.
In 2 different study phases, individuals with and without CTS were assessed for TAS by 2 different examiners. The CTSQ was administered to the individuals with CTS.
Intrarater and interrater reliability coefficients (0.89-0.93 and 0.82-0.90, respectively) were excellent in individuals with and without CTS. Weak negative correlations were found between TAS and overall CTSQ and symptom severity subscale scores, and a moderate negative correlation was found between TAS and functional Status Subscale score.
This HHD method of reliably assessing TAS better quantifies deficits and progress than traditional manual muscle testing for muscle grades greater than 3/5.
This method of HHD reliably quantifies TAS but is more reliable with the same than different raters.
Sonographic evaluation of the abductor pollicis brevis muscle reflects muscle strength recovery after carpal tunnel release
2022, Journal of Medical Ultrasonics
Effects of Carpal Tunnel Syndrome on Force Coordination and Muscle Coherence during Precision Pinch
2017, Journal of Medical and Biological Engineering
Quantitative evaluation of median nerve motor function in carpal tunnel syndrome using load cell: Correlation with clinical, electrodiagnostic, and ultrasonographic findings
2013, Journal of Korean Neurosurgical Society
The effect of blocking radial abduction on palmar abduction strength of the thumb
2012, Journal of Hand Surgery: European Volume

View all citing articles on Scopus

No benefits in any form have been received or will be received from a commercial party related directly or indirectly to the subject of this article.

Supported by the University of Cincinnati Orthopaedic Research and Education Foundation.

View full text

Carpal tunnel syndromeThumb Abduction Strength Measurement in Carpal Tunnel Syndrome

Purpose

Methods

Results

Conclusions

Type of study/level of evidence

Section snippets

Materials and Methods

Results

Discussion

Lancet

J Hand Surg [Br]

J Hand Surg [Am]

J Hand Surg [Am]

J Hand Surg [Am]

J Hand Surg [Am]

J Hand Surg [Am]

J Hand Surg [Br]

Carpal tunnel syndrome
Thumb Abduction Strength Measurement in Carpal Tunnel Syndrome