Objective evaluation of sensory function in patients with carpal tunnel syndrome using the current perception threshold.

The purpose of this study was to determine the sensitivity and specificity for the current perception threshold (CPT) test during clinical examination of idiopathic carpal tunnel syndrome (CTS). We studied 71 patients (102 hands) with CTS; 50 healthy individuals (100 hands) served as a control group. Using a neurometer, we investigated standard CPT values to obtain the sensitivity and specificity of the CPT test in the clinical examination of CTS. In the CTS group, cases that had abnormal values in the range analysis, the ratio analysis, or both were called "true-positive CPTs"; in the control group cases that had normal values in the range and ratio analyses were called "true-negative CPTs." We defined the sensitivity as the percentage of true-positive CPTs in the CTS group and the specificity as the percentage of true-negative CPTs in the control group. The sensitivity of the CPT test using both range and ratio analyses was 73%, and its specificity was 74%. Based on these results we concluded that the CPT test is a reliable quantitative sensory function test.