Sensory nerve action potentials of the medial and lateral plantar nerve.

A simple, reliable method of recording sensory nerve action potentials (SNAP) from the medial and lateral plantar nerves was established using 30 healthy adults as subjects. Potentials were recorded with surface electrodes both antidromically and orthodromically. The mean latency and amplitude of the SNAP of the medial plantar nerve using antidromic stimulation were 2.5msec (+/- 0.32) and 16.3microV (+/- 6.5), respectively. Orthodromically, the latency was 2.5msec (+/- 0.35) and the amplitude 16.5microV (+/- 7.14). For the lateral plantar, antidromically the nerve latency was 2.5msec (+/- 0.35) and the amplitude 14.8microV (+/- 4.41). With the orthodromic procedure, the latency remained unchanged but the amplitude was 11.0microV (+/- 5.59). In the case of the lateral plantar nerve, the antidromic technique consistently resulted in higher amplitude responses.