[Treatment of myasthenia gravis]

The strategy of myasthenia gravis has been progressed during recent 30 years. Extended thymectomy and alternate-day prednisolone administration remarkably improved therapeutic effect in myasthenia gravis. Besides of these therapies, plasmapheresis and immunoadsorption plasmapheresis extremely improved mortality in myasthenia gravis. 1. Corticosteroid therapy Usually initial doses of PSL is 20-30 mg every other day in the morning after thymectomy, and increased 5 mg every on-day. Maximum PSL doses is 80-100 mg alternate-day, then this doses will be maintained over 4 weeks. After these procedures, PSL is gyradually decreased and discontinued within 2-3 years. 2. Thymectomy Extended transsternal thymectomy is the most useful method, because many authors have reported that re-thymectomy reveals re-appearance of thymus. 3. Invasive thymoma Although this type of thymoma has been called malignant thymoma, it should be called as invasive thymoma since any thymoma can invade surrounding tissues for a long subclinical period. Strategy of treating invasive thymoma is PSL administration, radiation and chemotherapy. Chemotherapy should be performed depend on histopathological findings of thymoma. CHOP therapy is useful for the lymphocytic cell predominant type of thymoma, however CHOP + cis-platin therapy is useful for the epithelial cell predominant type. Treatment of myasthenia gravis has been improved, however it is still unclear that how to treat invasive thymoma, and how to prevent re-appearance of symptoms by decrease or discontinuity of PSL administration.