Myasthenia gravis: options and timing of immunomodulatory treatment.

The autoimmune pathogenesis of myasthenia gravis is relatively well understood. The current options for treatment of this disease are acute and long term immunotherapies, acetylcholinesterase inhibitors and thymectomy. Many factors influence the timing of initiation of immunomodulatory therapy in myasthenia gravis and both disease factors, such as stage and severity, and patient factors, such as age, pregnancy and intercurrent illness, must be considered. Decisions regarding the choice of therapy can be difficult because of the limited number of randomised controlled trials that have been performed in myasthenic patients. In general, acetylcholinesterase inhibitors alone are used only in mild ocular disease, and in the majority of other patients immunomodulatory therapy is begun early. Corticosteroids are the most commonly used initial therapy, followed by azathioprine. In refractory cases, the available options include immunosuppressants such as cyclosporin, mycophenolate mofetil and cyclophosphamide. Plasmapheresis and intravenous immunoglobulin are important in the treatment of acute exacerbations and myasthenic crisis and in the perioperative setting. Despite many years of experience, the role of thymectomy in improving long term outcome in nonthymomatous myasthenia gravis remains controversial.