Outcomes after thymectomy in class I myasthenia gravis

The role of extended thymectomy in the treatment of class I myasthenia gravis is still controversial. This study compared the long-term outcomes of operated and nonoperated patients allocated according to their will.

We retrospectively reviewed 47 patients with class I nonthymomatous myasthenia gravis undergoing extended thymectomy between 1980 and 2007. These patients were matched with 62 class I patients who refused surgery and received only pharmacologic therapy. Outcomes were stable remission and clinical or pharmacologic improvement. Predictors of remission were analyzed by Kaplan-Meier and Cox regression.

We observed low postoperative major morbidity (n = 2; 4.2%) and no perioperative mortality. Heterotopic thymus was found in 22 patients (46%). Twenty-one patients showed active germinal centers, in the heterotopic thymus in 12 patients (57.1%). Thirty operated patients (64%) versus 34 nonoperated patients (55%) achieved stable remission, and 8 patients (17%) versus 5 patients (9%) showed pharmacologic improvement. Nine patients who had no postoperative improvement showed active ectopic thymus. Surgery was a marginal prognosticator (P = .053). Early treatment (≤6 months from symptoms onset) was the unique significant prognosticator (P = .045), but this was due to the contribution of the operated patients (P = .002). Other predictors of remission in the operated group were the absence of ectopic thymus (P = .007) with no germinal centers (P = .009). No significant predictor of remission was found in the nonoperated group.

Extended thymectomy achieved a more rapid remission than after nonsurgical treatment of class I myasthenia gravis. Significantly better outcomes resulted when thymectomy was performed within 6 months from the onset of symptoms.