There is no known cure for MG, but there are effective treatments available. Common treatments include medications, thymectomy and plasmapheresis. Spontaneous improvement and even remission may occur without specific therapy.
Medications are most frequently used in treatment. Anticholinesterase agents (e.g., Mestinon®) allow acetylcholine to remain at the neuromuscular junction longer than usual so that more receptor sites can be activated. Corticosteroids (e.g., prednisone) and immunosuppressant agents (e.g., Imuran®) may be used to suppress the abnormal action of the immune system that occurs in MG. Intravenous immunoglobulins (IVIg) are sometimes used to affect the function or production of the abnormal antibodies also.
Thymectomy (surgical removal of the thymus gland) is another treatment used in some patients. The thymus gland lies behind the breastbone and is an important part of the immune system. When there is a tumor of the thymus gland (in 10-15% of patients with MG), it is always removed because of the risk of malignancy. Thymectomy frequently lessens the severity of the MG weakness after some months. In some people, the weakness may completely disappear. This is called a remission. The degree to which the thymectomy helps varies with each patient.
Plasmapheresis, or plasma exchange, may be useful in the treatment of MG also. This procedure removes the abnormal antibodies from the plasma of the blood. The improvement in muscle strength may be striking, but is usually short-lived, since production of the abnormal antibodies continues. When plasmapheresis is used, it may require repeated exchanges. Plasma exchange may be especially useful during severe MG weakness or prior to surgery.
Treatment decisions are based on knowledge of the natural history of MG in each patient and the predicted response to a specific form of therapy. Treatment goals are individualized according to the severity of the MG weakness, the patient's age and sex, and the degree of impairment.
The current treatments for MG are sufficiently effective that the outlook for most patients is bright. Although the treatments will not cure MG, most patients will have improvement in their muscle strength. In some cases, MG may go into remission, during which no treatment is necessary. There is much that can be done, but still much to understand. New drugs to improve treatments are needed. Research plays an important role in finding new answers and treatments for MG.
Reviewed by the MGFA's Medical Advisory Board, June 2010