Study of evolution of nerve damage in leprosy. Part II--Observations on the index branch of the radial cutaneous nerve in contacts of leprosy.

A total of 35 contacts from 20 families of lepromatous index cases were screened clinically. All of them were subjected for nerve conduction velocity (NCV) studies of both left and right index branch of the radial cutaneous (IRC) nerve. Fifteen of these nerves were biopsied. Out of 15 IRC nerves biopsied 10 had slightly reduced average NCV values and 5 were normal. Four nerves out of 10 where average NCV was reduced and 1 nerve out of 5 where NCV was normal showed significant ultrastructural changes and higher percentage of segmental demyelination (10%--13%). There was a striking similarity between the changes seen in the IRC nerves of early cases of leprosy and of contacts.