Effects of thymectomy on late-onset myasthenia gravis without thymoma

Objectives This study aims to investigate whether thymectomy is beneficial for late-onset (>50 years) myasthenia gravis patients with no thymoma, particularly for those with mild generalized weakness. Patients and methods A total of 34 patients were included in the study. The clinical course and long-term outcomes over 2 years were reviewed in 20 patients who underwent thymectomy and in 14 without thymectomy. Results Of the 34 patients, 20 (59%) underwent thymectomy. Thymectomized patients had more severe disability at entry than non-thymectomized patients, but outcome measures did not significantly differ between the two patient groups. Moreover, subgroup analyses including 22 patients with mild generalized weakness at entry showed that the thymectomized group (n = 10) showed a greater percentage of clinical remission (no symptoms; 50% versus 17%; p = 0.11) and a lower frequency of the presence of generalized symptoms (30% versus 75%; p < 0.05) than the non-thymectomized group (n = 12) at the end of follow-up (means 9.6 years after onset). Conclusions Thymectomy is a potentially effective treatment for late onset, non-thymomatous patients with mild generalized myasthenia gravis.