Evoked sensory nerve action potentials: effect of different recording electrodes on distal latencies and amplitudes

The evoked sensory nerve action potentials (ESAP) of the median nerve were studied in 20 subjects using an antidromic technique, recording the distal latency to onset and to peak, and peak to peak amplitude, using three different recording electrodes. The electrodes used were the TECA digital ring electrodes, AERO MED wire loop stretch and squeeze-type electrodes, and Neurodiagnostic finger clip electrodes. Because the Neurodiagnostic finger clip electrodes are wider than the others, they were placed at different points over the proximal and distal interphalangeal joints to evaluate any changes in the ESAP caused by different interelectrode distance. The values obtained for the distal latencies and amplitudes for each electrode were compared using the unpaired Student's t-test. There were no statistically significant differences found in the ESAP distal latencies to onset or peak using any of the electrodes or various placements. When comparing the amplitude responses, the only statistically significant difference was noted when the TECA digital ring electrodes were compared to a particular arrangement of the Neurodiagnostic finger clip electrodes (p less than 0.05). It was therefore concluded that any of these electrodes can be used to obtain reliable reproducible data for nerve conduction studies.