Radial motor nerve conduction studies

The radial motor nerve fibers were studied in 30 subjects using a technique of surface stimulation in the axilla and the antecubital fossa. Surface recording over the extensor digitorum communis 8cm from the distal stimulation site was done. Mean distal latency was 2.6msec (SD = 0.44), amplitude 11.24mV (SD = 3.5), and conduction velocity 68m/sec (SD = 7.0). Side-to-side comparison using the t-test demonstrated no significant differences. Five subjects were tested 75 more times on two successive days and showed a variation in latency of 0.2msec or less in 74 of 75 trials. Amplitude was consistent during each day's trial, but it varied slightly from one day to the next. Three case reports show the usefulness of the procedure.