High-dose intravenous immunoglobulin in the management of myasthenia gravis.

Intravenous immunoglobulin, 400 mg/kg, was administered daily for five days to 12 patients with exacerbation of generalized myasthenia gravis. Degree of weakness, duration of illness, use of prednisone, and history of thymectomy or thymoma did not affect the response to intravenous immunoglobulin. Eleven patients improved, beginning 3.6 +/- 2.7 (mean +/- SD) days after the start of treatment and becoming maximal in 8.6 +/- 4.6 days, with sustained improvement lasting 52 +/- 37 days. Vital capacity increased from 1748 +/- 510 to 2700 +/- 614 mL at peak effect. Decreases in strength occurred in four patients beginning on day 3.2 +/- 2.5, lasted 1.5 +/- 0.6 days, and were mild in three patients. Other effects were minimal. There was no significant change in acetylcholine receptor antibody titers, which were elevated in all patients. Immunoglobulin seemed to produce a more rapid improvement than corticosteroids and is recommended as an adjunct in the management of myasthenia gravis exacerbations.