Accuracy of Ultrasonography for the Diagnosis of Carpal Tunnel Syndrome: A Systematic Review and Meta-Analysis

Objective: To evaluate the accuracy of inlet and outlet ultrasonography measurements for the diagnosis of carpal tunnel syndrome (CTS).

Data sources: MEDLINE, EMBASE, the Cochrane Library, and the Web of Science databases were systematically searched from inception to February 2017.

Study selection: Observational studies comparing the diagnostic accuracy of inlet and outlet ultrasonography measurements were selected.

Data extraction: Random-effects models for the diagnostic odds ratio (dOR) values computed by Moses' constant for a linear model and 95% confidence intervals (CIs) were used to calculate the accuracy of the test. Hierarchical summary receiver operating characteristic curves were used to summarize overall test performance.

Data synthesis: Twenty-eight published studies were included in the meta-analysis. The pooled dOR values for the diagnosis of CTS were 31.11 (95% CI, 20.42-47.40) for inlet-level and 16.94 (95% CI, 7.58-37.86) for outlet-level measurements. The 95% confidence region for the point that summarizes overall test performance of the included studies occurred where the cutoffs ranged from 9.0 to 12.6mm² for inlet-level measurements and from 9.5 to 10.0mm² for outlet-level measurements.

Conclusions: Both ultrasonography measurements for the diagnosis of CTS showed sufficient accuracy for their use in clinical settings, although the overall accuracy was slightly higher for inlet-level than for outlet-level measurements. The addition of outlet and inlet measurements does not increase the accuracy for the diagnosis. Therefore, the inlet-level ultrasonography measurement appears to be an appropriate method for the diagnosis of CTS.