Median nerve latency measurement agreement between portable and conventional methods

A portable nerve conduction testing de, ice was compared with a conventiona l method of measuring median nerve distal latencies. In a population-based study, a health questionnaire was mailed to a random sample of 3000 partici pants (aged 25 to 74 years). Two hundred and sixty-two responders with numb ness and/or tingling in the median nerve distribution, and 125 asymptomatic responders underwent clinical examination as well as portable and conventi onal median nerve distal latency measurements. Motor latency measured with the portable device was on average 0.1 millisecond (ms) lower than motor la tency measured with the conventional method (95% limits of agreement, -0.8- 0.5 ms). Sensory latency (wrist-to-index finger) measured with the portable device was on average 0.3 ms lower than sensory latency (long finger-to-wr ist) measured with the conventional method (95% limits of agreement, -0.7-0 .1 ms). Strong correlations were found between the latencies measured by th e portable and conventional methods (Pearson correlation coefficient, 0.90- 0.93), The agreement between the portable and conventional methods in measu ring median nerve distal latencies appears to be acceptable, The cut-off va lue for abnormal sensory latency needs to be lower for the portable than th e conventional method if the present measurement techniques are used.