Dapsone-induced neuropathy compounds Hansen's disease nerve damage: an electrophysiological study in tuberculoid patients.

In 17 previous cases of dermatological disorders, an axonal motor neuropathy was described as a dapsone (DDS) therapy side effect. In this study, we attempted to assess DDS-induced neuropathy in the ulnar and popliteal nerves of 39 tuberculoid Hansen's disease patients using electrophysiological recordings at the time of DDS withdrawal, owing to dermatological improvement, and 4 months after. Distal motor latencies, conduction velocities at forearm and leg and above the epicondyle and the neck of the fibula were improved at a highly significant level. Twenty-five percent of the patients presented abnormal values (outside of the 95% confidence interval) at the first recording session compared to those at the second session. By contrast, parameters exploring the degree of innervation of distal muscles showed a progressive denervation. These results lead to an impairment of Hansen's disease neuropathy during DDS therapy affecting the motor conduction velocities of one quarter of the patients, and are discussed in terms of physiopathological mechanisms.