Long-term outcome of thoracoscopic extended thymectomy for nonthymomatous myasthenia gravis.

BACKGROUND: Thoracoscopic thymectomy has shown promise in the integrated management of myasthenia gravis (MG) although there is still scant data on long-term results. The aim of this study was to analyze long-term (>5 years) results of thoracoscopic extended thymectomy in nonthymomatous MG.

METHODS: We retrospectively reviewed 32 patients operated on between 1995 and 2003. MG foundation of America clinical classification (MGFA), symptoms' duration, preoperative crisis, anticholinesterase-drugs dosage, steroid use, and acetylcholine receptor antibodies were evaluated in all patients with annual follow-up. Anti-MuSK antibody titer was also assessed at the last follow-up.

RESULTS: There were 21 females and 11 males with a median age of 36 years. Ten patients were seronegative for acetylcholine receptor antibodies. Patients in MGFA class I, II, III and IV were 7 (22%), 15 (44%), 9 (28%), 2 (6%) patients, respectively. Median symptoms duration was 11 months. There was no mortality or major morbidity. Median hospital stay was 4.0 days. Ectopic thymic tissue was found in 18 (56%) patients. Median follow-up was 119 months (range 60-156 months). There was no residual thoracic pain. Estimated 10-year remission rate was 50%. At 72 months, 27 (84.3%) patients were improved or in complete remission. At the univariate analysis, shorter duration of symptoms (<12 months) and absence of oropharyngeal involvement were both predictors of response to thymectomy (p<0.02) whereas positivity for anti-MuSK antibody was a predictor of non-response (p=0.0007).

CONCLUSIONS: Thoracoscopic extended thymectomy yields satisfactory long-term results in patients with nonthymomatous myasthenia gravis although anti-MuSK positivity correlated with poor response to operation.