[Segmental ulnar nerve conduction in Hansen's disease]

In leprosy, ulnar neuritis is considered to be selectively localised at the elbow and is often treated by surgical decompression when pain and/or neurological deficit occurs. The aim of this prospective study is to assess the prevalence, localisation and severity of ulnar nerve damage in leprosy. Motor nerve conduction velocity (MNC) was measured at 3 different segments: arm, elbow and forearm, and was expressed both in meters/second and percentage of the mean normal values found in our laboratory or as reported in other studies. The patient group consisted of 123 consecutive new leprosy sufferers (228 ulnar nerves only) who attended the Institut de Léprologie Appliquée de Dakar over the period of one year. Diagnosis and classification were based on Ridley & Jopling's criteria, including skin and nerve biopsy. Mean MNC was reduced by 13.5 m/s at the arm, 19.8 m/s at the elbow and 7.8 m/s at the forearm as compared to the mean normal values. Increased distal latency as an isolated finding was rare (0.9%). Mean MNC was more reduced in the BL, LL (lepromatous) than in the TT, BT (tuberculoid) subgroups, despite similar disease durations (22.3 +/- 18.7 months and 24.2 +/- 26.4 months respectively (n.s.). Using different normal MNC values did not affect the conclusion: we did not see any selective slowing of ulnar MNC at the elbow suggesting that nerve damage is not primarily related to mechanical factors.