Objective: This study sought to determine the efficacy and prognostic factors of extended transsternal thymectomy as a treatment for myasthenia gravis (MG). Methods: Medical records of 147 patients who underwent extended transsternal thymectomy for MG from January 1991 to December 2002 were reviewed retrospectively. The complete stable remission (CSR) rate and prognostic factors for CSR were assessed in 106 female and 41 male patients. Results: The median age was 35 years (range 11—75 years). Ninety-eight patients had non-thymomatous MG and 49 patients had thymomatous MG. The median follow-up time was 89.7 months (range 12—167 months). Both non-thymomatous MG and thymomatous MG exhibited significant differences in population characteristics and CSR rates (29.6% vs 13.3% at 5 years, 45.2% vs 27.7% at 10 years, p = 0.022). Steroid therapy (hazard ratio: 0.234, p = 0.003) was a poor prognostic factor, while early onset (hazard ratio: 3.519, p = 0.048) was a good prognostic factor for CSR in non-thymomatous MG. In contrast, steroid therapy (hazard ratio: 0.061, p = 0.034) was poor prognostic factor for thymomatous MG. Conclusions: Extended transsternal thymectomy is a good treatment tool to achieve CSR in MG. Thymomatous MG and non-thymomatous MG were significantly different in patient characteristics and prognosis. Prognostic factors were steroid therapy and age of onset in non-thymomatous MG, and steroid therapy in thymomatous MG.
