Neurologic outcomes of thymectomy in myasthenia gravis: Comparative analysis of the effect of thymoma

Objectives: The objectives of this study were to compare the clinical features and the outcomes after thymectomy between patients with and without thymoma and to evaluate the influence of thymectomy on the subsequent clinical course of myasthenia gravis. Methods: Between 1995 and 2003, 64 consecutive patients underwent thymectomy, and of these, 60 patients were followed up for at least 12 months postoperatively. The study population was divided into 2 groups based on the presence of thymoma. We performed a retrospective analysis to compare the neurologic outcomes of thymectomy between patients with thymomatous myasthenia gravis and those with nonthymomatous myasthenia gravis. Results: Twenty-four patients had a thymoma. No significant differences were observed between the 2 groups regarding the preoperative severity of myasthenia gravis. There was no significant difference in the follow-up duration between the 2 groups. There was no significant difference in the overall remission rate between the 2 groups ( P = .064). The mean time required to reach a remission was 10.6 months and 23.5 months in the thymoma and nonthymoma groups, respectively. The mean duration of remission was 43.1 months and 30.8 months in the thymoma and nonthymoma groups, respectively. In the early phase of follow-up, more patients reached remission in the thymoma group than those in the nonthymoma group ( P = .040). Conclusions: Neurologic outcomes of the thymoma group were no worse than those of the nonthymoma group. It is expected that earlier thymectomy is likely to result in a better prognosis by shortening the disease period, even for patients with nonthymomatous myasthenia gravis.