Perioperative and long-term outcome of thymectomy for myasthenia gravis： comparison of surgical approaches and prognostic analysis

Background Thymectomy is an established treatment for myasthenia gravis （MG）, and video-assisted thoracoscopic surgery （VATS） thymectomy has become an acceptable surgical procedure. This study aimed to compare the results of VATS thymectomy and open thymectomy and to identify the prognostic factors after thymectomy. Methods The clinical data of 187 consecutive thymectomies performed between July 2000 and December 2009 were retrospectively reviewed; 75 open thymectomies and 112 VATS thymectomies. Clinical efficacy and variables influencing outcome were assessed by Kaplan-Meier survival curves and Cox proportional hazards regression analysis. Results The operative blood loss in the VATS group was significantly less than that in the open group （（62.14＋55.43） ml vs. （137.87＋165.25） ml, P 〈0.05）. The postoperative crisis rate increased with the severity of preoperative MG and the prescription dose of anticholinesterase. Complete follow-up information of patients more than 12 months after the thymectomy was obtained on 151 cases, 89 cases from the VATS group and 62 cases from the open group, with a mean follow-up period of 59.3 months, range from 12 to 117 months. Complete stable remission （CSR） was the end point for evaluation of the treatment results. The overall five-year CSR rate was 57.5%. Two good prognostic factors were identified; preoperative prescription of anticholinesterase alone （P=0.035） and non-thymomatous MG （P=0.003）. The five-year CSR rate of the ocular type of MG reached a high level of 67.4%. Conclusions Thymectomy can achieve good long-term CSR in MG, and VATS is an ideal alternative method. High-dose prescription of anticholinesterase and the advanced stage by Myasthenia Gravis Foundation of America （MGFA） classification have higher risks of postoperative crisis. Preoperative prescription of anticholinesterase alone and non-thymomatous MG are good prognostic factors. Thymectomy should also be considered for the ocular tvioe of MG.