Corticotropin and corticosteroids in generalized myasthenia gravis: comparative studies and role in management

The effect of 310 courses of corticotropin, methylprednisolone, prednisone, and dexamethasone were studied in 62 patients with generalized myasthenia gravis who were poorly responsive to anticholinesterase medication and most of whom required assisted respiration. Improvement in strength and response to anticholinesterase medication occurred in 91% of the courses, and was moderate or marked in 63%. The incidence, degree, and duration of improvement appeared to be dose related. High doses of dexamethasone (20 mg orally each day for 10 days, repeated if necessary), which had 75% more glucocorticoid effect than any other regimen studied, produced the highest incidence of both improvement (100%) and moderate-to-marked improvement (75%), and the greatest duration of improvement (more than 3 months after 40% of the courses). The duration of improvement following intensive courses of any of the corticosteroids was approximately doubled by the subsequent administration of smaller doses of dexamethasone or prednisone on alternate days. Most patients with severe disease relapsed after 3 to 6 months of corticosteroid treatment, but increase in the dose of corticosteroid, and daily administration, which was more effective than alternate-day administratin, almost always again resulted in improvement. Corticotropin and corticosteroids were equally effective before and after thymectomy. High doses of corticotropin and corticosteroid produced an initial exacerbation of the disease in 80% of the courses, which was moderate or marked in 57%. Reduction in dose reduced the incidence of severe exacerbation, but did not prevent it, and also resulted in slower and less marked improvement. Withholding anticholinesterase medication did not prevent exacerbation or increase improvement, and afforded no advantage, though it was usually helpful to reduce the dose of this medication. Because of the hazard of initial exacerbation and the occurrence of other serious side effects in 15% of the patients. (bleeding ulcer, vertebral compression, aseptic necrosis of the femoral head or tibia, and subcapsular cataracts), it is recommended that corticosteroid treatment be limited to myasthenic patients who are not responding satifactorily to anticholinesterase medication, that smaller doses be employed in patients whose disease is not life threatening, and that higher doses be reserved for patients who are critically ill and are being managed, at least initially, in an intensive care unit.