Myasthenic crisis. Response to plasmapheresis following failure of intravenous gamma-globulin.

Myasthenic crisis is a potentially life-threatening complication of myasthenia gravis that requires aggressive therapy. We describe four patients in whom myasthenic crisis developed and who failed to respond to initial treatment with intravenous gamma-globulin. All four patients subsequently responded to intensive plasma exchange. Based on our experience, plasmapheresis appears to be superior to intravenous gamma-globulin for the treatment of myasthenic crisis in certain patients. Prognostic factors that determine the effectiveness of intravenous gamma-globulin vs plasmapheresis in these patients merit further investigation.