[Indications and value of thymectomy in myasthenia gravis]

The therapeutic impact of thymectomy on the clinical course of myasthenia gravis is still a matter of debate. Issues in this discussion that are clinically relevant are reviewed. While the surgical procedure is accepted for thymomas its performance is controversial in cases with no thymomatous tissue. Outcome studies show a weak correlation between clinical course and thymus histology, but there is some doubt about the maximum age for thymectomy and about the therapeutic regimen following surgery. Retrospective studies show that thymectomy has a beneficial influence on the natural course of myasthenia. This positive effect is enhanced by appropriate immunosuppressive therapy together with anticholinesterase inhibitor substitution. Unfortunately, the different forms of myasthenia do not all respond in the same manner. Studies have shown that thymoma-associated myasthenia is more difficult to control than non-thymoma-associated myasthenic states. In both groups some patients go into remission after thymectomy alone, and the majority of patients with the institution of additional immunosuppression. In clinically mild cases thymectomy should not immediately be followed by immunosuppression. This will help to identify those patients responding with remission to thymectomy alone. Mostly these are young women with a hyperplastic thymus. Overall, thymectomy is beneficial and should be considered in all patients with generalized myasthenia who are still under 60 years of age.