Near-nerve needle sensory conduction study of the medial calcaneal nerve: New method and report of four cases of medial calcaneal neuropathy.

There has been one previously published antidromic method for studying medial calcaneal nerve (MCN) conduction. However, the origin of the compound nerve action potentials (CNAPs) with this technique is uncertain because of the antidromic nature of stimulation. We report a new orthodromic method for MCN conduction study using the near-nerve needle technique. In 35 normal controls, maximum nerve conduction velocity (NCV) and negative-peak NCV of MCN were 42.4 +/- 3.9 m/s and 33.6 +/- 3.0 m/s, respectively. The amplitude of the CNAP was 4.1 +/- 2.2 micro V. We also report four cases of medial calcaneal neuropathy, three of which were confirmed by this technique. We conclude that the present technique is capable of recording the sensory nerve action potentials of MCN in isolation and confirming the diagnosis of medial calcaneal neuropathy electrophysiologically.