Orthodromic sensory nerve conduction of the medial and lateral plantar nerves. A standardization.

A standardized method of obtaining orthodromic distal sensory latencies of the medial and lateral plantar nerves is presented. Forty-one normal volunteer subjects were tested. Stimulation is carried out on the plantar aspect of the base of each toe using ring electrodes. Surface recording electrodes are placed posterior to the medial malleolus over the tarsal tunnel at points measuring 14, 16, 18 and 20 centimeters from the dorsum of the base of the great toe. Sixty-four evoked responses were averaged utilizing an electronic averaging technique and temperature was maintained at 31 degrees centigrade. Mean and standard deviation values of the distal sensory latency are reported for each toe. The reliability and ease in performance of these conduction studies will make them necessary and useful aids in the electrodiagnostic evaluation of tarsal tunnel syndrome, peripheral neuropathies and other local neuropathic conditions. Case studies are presented demonstrating the usefulness of this testing.