Study of nerve conduction velocity, somatosensory-evoked potential and late responses (H-reflex and F-wave) of posterior tibial nerve in leprosy.

The present study was conducted in 25 leprosy patients (of different age and sex) with or without clinical evidence of neuropathy. The diagnosis was confirmed by skin biopsy. A group of 15 age- and sex-matched, healthy persons also were studied for comparison and served as controls. Motor nerve conduction velocity (MNCV) was reduced in nine patients (36%) and sensory nerve conduction velocity (SNCV) was reduced in three patients (12%). Late responses (H-reflex and F-wave) were deranged in 16 patients (64%). Somatosensory evoked potential (SSEP) was deranged in 13 patients (52%). N7-N18 interpeak latency (PCT) was prolonged in two patients (8%); none showed prolongation of N18-N35 interpeak latency (CCT). We observed that nerve conduction velocity, late responses, and SSEPs were deranged in all types of leprosy, regardless of clinical evidence of neuropathy, and were more prominently affected in the tuberculoid (TT) type of leprosy. A study of late responses is more informative than conventional nerve conduction studies for the detection of early lesions of the nerves. The study of SSEP shows involvement of the peripheral part of the nervous system and complete sparing of the central part of the nervous system.