Evidence for thymectomy in myasthenia gravis: Getting stronger?

Abstract

Thymectomy is part of the therapeutic armamentarium for myasthenia gravis (MG). During the past 80 years, multiple observational studies have shown that thymectomy can potentially fasten stabilization of the disease, reduce the need for corticosteroids, and in some patients lead to complete remission. The benefit from thymectomy in MG is supported by propensity score analysis. A randomized control trial looking at the role of thymectomy in nonthymomatous MG patients was recently completed, but the results are not yet available. The approach and extent of thymectomy remain a topic of intense discussion, particularly with the development of minimally invasive surgery. Although the presence of extracapsular thymic tissue is frequent and well described, the accessibility of these ectopic thymic foci as well as their function and impact on outcome after surgery have been unclear, leading to divergent views between proponents of a maximal cervicomediastinal thymectomy with en bloc resection of all fatty tissue between the thyroid grand and the diaphragm and those of a less extensive approach. In the future, better definition of the type of thymectomy will be important, particularly if prospective studies and randomized trials are performed to compare different surgical approaches. One possibility would be to reserve the term "extended thymectomy" to resection of the thymus with the anterior mediastinal fat between both pleura, the pericardium and diaphragm. More extensive surgery should be specified when it encompasses sites such as the right and left pericardiophrenic angles, the aortopulmonary window, the aortocaval groove and retroinnominate space, and the perithyroid area.