Accuracy of a portable electroneurometer for measuring distal motor latency

Background. A facile electromyographic test in the outpatient clinic is needed to evaluate the outcome of screening for carpal tunnel syndrome. The purpose of the current prospective study was to compare the accuracy of Nervepace digital electroneurometer (Nervepace) and Dantec Neuromatic 2000M (Dantec) measurements of a wide range of distal motor latency (DML) of the median nerve. Methods. The DML values for 112 of 126 median nerves examined with Nervepace and conventional electromyography, Dantec were statistically analyzed in this prospective study. The 30 hands of 15 clinically healthy adults 20-24 years old served as the reference group. Sixty consecutive patients (96 hands) with idiopathic carpal tunnel syndrome provided a wider range of DML values. All of the patients had standard clinical tests and standard motor (Dantec and Nervepace) and sensory (Dantec) electrodiagostic tests before endoscopic carpal tunnel release. Results. The DML was measurable in all 30 hands of the reference group, in all 96 hands of the patients by Dantec, but in only 82 hands (52 patients) by Nervepace. Nervepace and Dantec DML values of 6.0 ms or less had high correlation and agreement. Conclusions. Correlation and agreement decreased significantly among values greater than 6.0 ms.