Reliability of a digital electroneurometer for the determination of motor latency of the median nerve.

Measurement of distal motor latencies of the median nerve are often part of electrodiagnostic studies used to verify a diagnosis of peripheral neuropathy. Since electrodiagnostic studies are time consuming, expensive, and impractical for large-scale screening of at-risk individuals, a portable digital electroneurometer was developed for measuring motor latencies as a screening tool for early detection of nerve compression syndromes, including carpal tunnel syndrome. The purpose of this study was to determine the intertester and intratester reliability of a digital electroneurometer in subjects with (n=12) and without (n=20) clinical signs of carpal tunnel syndrome. This study addressed only the reliability and not the validity of this device. Using a repeated measures design, three evaluators performed two distal motor latency tests on the median nerve of each of the subjects. Pearson product-moment correlations for intratester reliability ranged from 0.94 to 0.99, and the intraclass correlation coefficient for intertester reliability was 0.96. Two examiners obtained statistically larger latency values on the second test, although these differences are judged to be clinically insignificant. Use of an electroneurometer may expand motor latency testing to a wider variety of settings.