The peroneal and tibial nerves in lepromatous leprosy. Clinical and electrophysiologic observations

Clinical examination and segmental nerve conduction velocity studies of peroneal and tibial nerves were carried out on 25 patients with lepromatous leprosy and on 16 control subjects. Muscle atrophy and weakness occurred most often in extensor digitorum brevis muscle (15 of 50 legs) and intrinsic foot muscles (12 of 50 legs), with lesser instances of weakness in other muscles. Nerve enlargement and nerve pain were common for the peroneal nerve and less common for the tibial nerve. Nerve conductions and latencies revealed significant slowing in the patients in the segment of the peroneal nerve from the popliteal fossa to the head of the fibula and in the latency from the ankle to the extensor digitorum brevis muscle. Tibial slowing occurred in the segment from the popliteal fossa to the ankle and in the latency from the popliteal fossa to the lateral head of the gastrocnemius. This study shows that clinical and electrical evidence of segmental involvement of both nerves is common in lepromatous leprosy, and points out the importance of performing nerve conduction velocity studies on the segment of the peroneal nerve between the popliteal fossa and the head of the fibula.