Thymectomy for Myasthenia Gravis: Complete Stable Remission and Associated Prognostic Factors in Over 1000 Cases

Abstract

The efficacy of thymectomy and the optimal surgical technique in the treatment of myasthenia gravis (MG) remain controversial. Long-term outcomes are lacking and remission rates are based on small populations. We reviewed our institutional experience of thymectomy for MG focusing on long-term outcomes, complete stable remission (CSR), improvement of symptoms, after transcervical, transsternal, thoracotomy, and VATS thymectomy. A retrospective review of a prospectively maintained database of 3017 patients from 1941-2013 with MG was performed. Patients who underwent thymectomy with follow-up data including age at the time of surgery, sex, date of onset of symptoms, date of surgery, Osserman classification before and after surgery, surgical technique, date of remission, and status at last follow-up were included in the analysis. CSR and prognostic factors were analyzed by crude rate, Kaplan-Meier estimate, chi-squared test, Wilcoxon test, and a Cox proportional model. Overall, 1002 thymectomy patients with complete data were analyzed, and 35.5% (n = 355) derived benefit from surgery. Crude rate CSR was 19% (n = 191) and an additional 16% (n = 164) symptomatically improved requiring less medication after thymectomy. Also, 58% (n = 580) were stable after resection, and 6.7% (n = 67) developed progressive disease. Kaplan-Meier estimates of CSR were 27.7%, 36.7%, and 47.3% at 10, 25, and 40 years, respectively. On multivariate analysis, transsternal technique, thymoma, and preoperative Osserman classification were significantly associated with failure to achieve CSR. Thymectomy provides long-term CSR in 47.3% of patients with long-term follow-up. Patients with MG should be offered thymectomy when possible.