Thymectomy in thymomatous and non-thymomatous myasthenia gravis: analysis of a cohort of 46 patients

Background: Factors predicting remission after thymectomy for myasthenia gravis are not well known.

Objective: To analyze the clinical evolution of the patients after this intervention and discuss about predictors of response.

Methods: We retrospectively reviewed all clinical data of thymectomies in myasthenia gravis patients performed at our hospital between 2006 from 2016. Using the MGFA-PIS classification, «complete stable remission», «pharmacologic remission», «minimal manifestations» and «improved» were defined as «good clinical outcome», and «unchanged», «worse», «exacerbation» or «died», as «poor clinical outcome».

Results: In 46 consecutive thymectomies for myasthenia gravis, women comprised 71.7%. Median age was 37 years and 10.9% had concomitant autoimmune disorders associated. Thymoma (23.96%) was more frequent in older patients (53 ± 20 vs 33 ± 24 years) and men (54.5% vs 18.8%). A year after thymectomy, 28.2% of patients were in poor clinical outcome group and 54.3% had good clinical outcome. On univariate analysis, thymomatous myasthenia was associated with poor clinical outcome a year after surgical intervention. After ten years of follow-up, 9.8% reached complete stable remission, a total of 32 patients (78%) had a favourable outcome and thymoma was not correlated.

Conclusions: Thymectomy is considered an effective treatment for myasthenia gravis but the benefit is not immediate. The presence of thymoma may determine a worse initial clinical response following thymectomy in patients with myasthenia gravis.