Myasthenia gravis and multiple sclerosis: an unusual combination of diseases.

Abstract

Four cases are presented that illustrate the unusual occurrence of both myasthenia gravis and multiple sclerosis in the same patient. The manifestations of myasthenia gravis in our patients included fatigability, electromyographically demonstrated decrementing responses, incrementing responses, or posttetanic potentiation with repetitive stimulation, clinical and electromyographic improvement following the use of anticholinesterase agents, and clinical improvement after thymectomy. Multiple sclerosis was manifested by exacerbations and remissions of central nervous system signs and symptoms that were disseminated in time and space, by abnormalities of the cerebrospinal fluid colloidal gold curve or gamma globulin, or both, and by the scattered demyelinating lesions of the central nervous system that varied in cellular reaction and age, as seen in case 2. On the basis of our four cases, plus other similar, previously reported cases, we propose that a little-noted syndrome exists in which the patients may have clinical, laboratory and pathologic manifestations of both myasthenia gravis and multiple sclerosis.