Effect of drug treatment on electroneurological measures of peripheral nerve function in leprosy patients.

OBJECTIVE: To investigate whether drug treatment improves the electroneurological measures of affected peripheral nerve function in leprosy patients. DESIGN: Clinical status of patients determined on the first visit by an investigator administered, pre-designed questionnaire, followed by measurement of motor conduction velocity (MCV) and distal latency (DL) of ulnar, median, common peroneal and posterior tibial nerves bilaterally in patients referred consecutively from the dermatology unit and leprosy clinic, Teaching Hospital, Galle. MCV and DL measurements were repeated after 6 to 12 months of treatment. SETTING: Department of Physiology, Faculty of Medicine, University of Ruhuna, Galle. SUBJECTS: 24 diagnosed leprosy patients; tuberculoid, lepromatous and borderline in clinical type. INTERVENTIONS: Based on clinical typing. Tuberculoid (paucibacillary) type rifampicin 600 mg monthly and dapsone 100 mg daily for six months. Lepromatous and borderline (multibacillary) type rifampicin 600 mg and clofazimine 300 mg monthly and dapsone 100 mg and clofazimine 50 mg daily for 24 months. RESULTS: DL in all 4 nerves and MCV in 3 nerves tested were significantly different (p > 0.001) to those for the normal population and remained so after 6 to 12 months of treatment. The DL in the ulnar nerve showed significant improvement (p < 0.05) after treatment. When analysed in each patient individually, before and after treatment, the MCV showed an improvement in 48 to 72% of patients and the DL in 41 to 59%, but differences were not significant. CONCLUSIONS: Electroneurological recovery (return to normal state) of the affected peripheral nerves of leprosy patients does not occur after 6 to 12 months of drug treatment. The significant (p < 0.05) improvement (becoming better) of ulnar nerve DL indicates that, if at all, electroneurologically detectable improvement of nerve function occurs in the early stages of nerve damage, and that it may take longer than one year after starting treatment.