Twelve years ago two patients with a syndrome of continuous muscle fibre activity were described and the site of the abnormal discharge localised to the motor nerve terminals. These cases have been restudied electrophysiologically, by muscle histology and histochemistry and by motor nerve terminal and end-plate preparations. The neurological nature of the disorder is confirmed, and the relevant effects of drugs acting on motor nerve terminals discussed. The original cases responded dramatically to diphenylhydantoinate, and one of the patients has improved to a point where he no longer requires therapy, thus confirming the acquired nature of the disorder.S. Afr. Med. J., 48, 1601 (1974)
