Remission of myasthenia gravis following plasma-exchange.

A course of daily plasma-exchange was undertaken in 3 patients with severe myasthenia gravis (M.G.) who had failed to respond to anticholinesterases, thymectomy, and steroids. In the 2 cases with acquired M.G., exchange was associated with an unequivocal improvement in muscle weakness and fatiguability, indicating that a humoral factor in plasma is directly concerned in causing the disorder of neuromuscular transmission. The improvement began within a few days of initiating exchange and continued for several days after exchange ceased. Preliminary evidence suggests that the beneficial effect can be maintained with subsequent immunosuppressive therapy. The patient with congenital M.G. failed to improve, suggesting that its pathogenesis may differ from that of the acquired disease.