Treatment of myasthenia gravis

In this issue of Neurology, two articles address important issues in the treatment of myasthenia gravis (MG).1,2 Gronseth and Barohn review the role of thymectomy1 and the Task Force of the Medical Scientific Advisory Board of the MG Foundation of America outlines a comprehensive grading system for classifying and following patients.2 Although these two articles are different in their approach and scope, both are important pieces of work that represent significant contributions to the literature on MG.

MG represents one of the great medical triumphs of the last half century. In 1960, Simpson first proposed that MG was an autoimmune disease and hypothesized that it resulted from an antibody-dependent block in neuromuscular transmission. Investigations in the 1970s demonstrated the deficiency of acetylcholine receptors at the neuromuscular junction in MG, the production of animal models by immunization with acetylcholine receptors, the passive transfer of the disease between species with immunoglobulin G, and the presence of antibodies to acetylcholine receptors in most patients with MG.3 Subsequently, the immunopathogenic and electrophysiologic mechanisms involved in the disease were elucidated.

Coincident with these discoveries, effective treatments were developed, including acetylcholinesterase inhibitors in the 1950s, and by 1970, prednisone and other immunosuppressive medications were available. In the 1970s, thymectomy—first described as a treatment modality in 1936—became an increasingly accepted form of therapy. In the 1980s, both plasma exchange and intravenous immunoglobulin were used to treat MG, particularly in patients with life-threatening illness.

However, problems and questions remain. …