Nerve conduction in leprosy: in vivo and in vitro study.

Sensory and mixed nerve conduction studies were performed on the distal segments of the radial, sural, median and ulnar nerves of leprosy patients from the entire spectrum of the disease. The values obtained were compared with those of age matched normal controls. All the clinically involved nerves, and about 30% of the clinically normal patient nerves showed a delayed conduction velocity. The conduction velocity difference was most significant (P less than 0.001) for the cutaneous branch of the radial, and sural nerves as compared to the ulnar and median. Five patients nerves that were clinically normal and showed a normal conduction velocity when tested in vivo, were biopsies and studied in vitro to determine the type of early nerve damage. C and A delta fibre involvement was found in all these nerves. It is concluded that leprosy is a diffuse neuropathy and there is early detectable nerve involvement even in clinically normal nerves of leprosy patients.