Peripheral motor neuropathy caused by excessive intake of dapsone (Avlosulfon)

A case of selective peripheral motor polyneuropathy caused by excessive intake of dapsone is described. The condition was characterized by a peripheral muscle weakness in all limbs, normal sensitivity and present, although weak, muscle reflexes. Neurophysiologically, low amplitude muscle responses, prolonged distal latencies and reduced motor conduction velocities were found together with electromyographic signs of denervation. Sensory neurography was normal. The patient showed a complete clinical recovery and a marked neurophysiological restitution after termination of the excessive drug intake. The patient was found to acetylate dapsone at a slow rate. The case is compared with those previously reported in the literature.