The sensitivity and specificity of ultrasound for the diagnosis of carpal tunnel syndrome: a meta-analysis

Abstract

Background: Carpal tunnel syndrome (CTS) is the most commonly diagnosed compression neuropathy of the upper extremity. Current AAOS recommendations are to obtain a confirmatory electrodiagnostic test in patients for whom surgery is being considered. Ultrasound has emerged as an alternative confirmatory test for CTS; however, its potential role is limited by lack of adequate data for sensitivity and specificity relative to electrodiagnostic testing.

Questions/purposes: In this meta-analysis we determined the sensitivity and specificity of ultrasound in the diagnosis of CTS.

Methods: A PubMed/MEDLINE search identified 323 articles for review. After applying exclusion criteria, 19 articles with a total sample size of 3131 wrists were included for meta-analysis. Three groups were created: a composite of all studies, studies using clinical diagnosis as the reference standard, and studies using electrodiagnostic testing as the reference standard.

Results: The composite sensitivity and specificity of ultrasound for the diagnosis of CTS, using all studies, were 77.6% (95% CI 71.6-83.6%) and 86.8% (95% CI 78.9-94.8%), respectively.

Conclusions: The wide variations of sensitivities and specificities reported in the literature have prevented meaningful analysis of ultrasound as either a screening or confirmatory tool in the diagnosis of CTS. The sensitivity and specificity of ultrasound in the diagnosis of CTS are 77.6% and 86.8%, respectively. Although ultrasound may not replace electrodiagnostic testing as the most sensitive and specific test for the diagnosis of CTS given the values reported in this meta-analysis, it may be a feasible alternative to electrodiagnostic testing as the first-line confirmatory test.

Level of evidence: Level III, systematic review of Level III studies. See Guidelines for Authors for a complete description of levels of evidence.

Fig. 1

A flow diagram shows the inclusion and exclusion criteria of articles based on our systematic review of the literature.

Fig. 2

A forest plot shows the sensitivity and 95% CI for each study and the composite sensitivity with the 95% CI. Symbol size reflects the sample size of each study and of the combined results. NCS = electrodiagnostic studies; C = clinical.

Fig. 3

A forest plot shows the specificity for each study and the composite specificity with the 95% CI. Symbol size reflects the sample size of each study and of the combined results. NCS = electrodiagnostic studies; C = clinical.

Fig. 4

A funnel plot of sensitivities indicated a trend in publication bias, with larger studies reporting higher sensitivities. The standard error (SE) reflects the variability and relative sample size of each study and when plotted shows trends toward biased estimates. The dotted line is provided as a reference to the composite estimate from the combined studies.