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

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.

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.

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).

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