OBSERVATIONS ON THE NATURE OF MYASTHENIA GRAVIS. THE EFFECT OF THYMECTOMY ON NEURO-MUSCULAR TRANSMISSION 1

Abstract

Five patients with severe myasthenia were studied 5 mos. after total extirpation of the thymus; 3 having shown great clinical improvement. Elec-tromyographic studies showed a larger number of muscle fibers responded to a maximal motor nerve stimulus and that the efficiency of transmission across the neuromuscular junction was greatly improved. In contrast to its effect before thymectomy in these patients, [see B. A. 16(5) entries 12240, 12241, 12242] prostigmine injected into the brachial artery now produced fascicular twitching, repetitive response to a single stimulus, and normal local prostigmine paresis. These observations support the hypothesis that the local defect in myasthenia gravis results from an inadequate amt. of transmitter substance, and suggests that in certain individuals the thymus plays a role in the pathogenesis of myasthenia gravis.