The medial plantar nerve is the terminal sensory branch of the tibial nerve an the most distal nerve that is easily recorded in the lower extremities, but it is not generally included in nerve conduction studies of diabetic peripheral neuropathy.
We recorded the orthodromic compound sensory and motor nerve action potentials of the medial and lateral plantar nerves across the tarsal tunnel in 47 adults aged from 22 to 78 (mean, 42.8 years) and studies those medial and lateral plantar
nerves
in 24
patients with diabetes mellitus aged from 46 to 76 (mean 57.6 years).
The compound nerve action potentials (CNAPs) were recorded from the posterior tibial nerved proximal to he flexor retinaculum and the medial and lateral plantar nerve were stimulated with a bipolar surface stimulator at a distance of 14 cm of the
medial
and lateral plantar surface of the foot, respectively.
The normal distal latencies were 2.98±0.26 msec and the amplitudes 19.36±10.41 uV for the medial plantar mixed nerve and 3.05±0.28 msec and 10.42±5.18 uV for the lateral plantar mixed nerve. All the CNAPs of medial plantar nerve were evoked
and
in
only 9.5% the potentials were not evoked in lateral plantar nerve.
In patients with diabetes, the distal latencies of medial plantar nerve were 3.13±0.32 msec and the amplitude 11.67±4.89 uV, and those of lateral plantar nerve were 3.13±0.35 msec, 4.28±3.47 uV, respectively. In 55.3% of patients CNAPs were
evoked
in medial plantar nerves, and 14.9% for lateral plantar nerve.
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