Clinical outcome and predictive factors of postoperative myasthenic crisis in 173 thymomatous myasthenia gravis patients

Purpose: Thymectomy is the first-line therapy for thymomatous myasthenia gravis patients. The aim of this study is to explore the clinical outcome and predictors of postoperative myasthenic crisis (POMC) in these patients.

Method: Clinical data of 173 thymomatous myasthenia gravis patients undergoing thymectomy from January 2000 to March 2013 were, retrospectively reviewed. Variables potentially affecting the occurrence of POMC were evaluated using binary logistic regression analysis. The difference in survival was determined by the log-rank test.

Result: Fifty-one patients experienced POMC. Univariate analysis revealed that events significantly associated with increased risk of POMC include symptom duration before operation >2.75months, preoperative bulbar symptoms, incomplete resection, operation time ≥122.5 min and advanced stages (stage III or IV). Multivariate logistic regression analysis showed that preoperative bulbar symptoms (OR = 3.207 [1.413–7.278]; P = 0.005) and incomplete resection (OR = 4.182 [1.332–13.135]; P = 0.014) were independent risk factors for POMC. Twenty-eight patients (16.9%) died during the follow-up. The log-rank test revealed survival for patients with POMC was significantly worse than that for patients without POMC (P = 0.042).

Conclusion: The important risk factors for developing POMC in thymomatous myasthenia gravis patients include the preoperative bulbar symptoms and incomplete resection of thymoma. Moreover, the patients with POMC had a worse prognosis compared with patients without POMC. Our study highlights the need of appropriate preoperative management of thymomatous myasthenia gravis patients to prevent the occurrence of POMC.