Modified maximal thymectomy for myasthenia gravis: effect of maximal resection on late neurologic outcome and predictors of disease remission.

Background: Although thymectomy is a standard practice of care in patients with myasthenia gravis, the best approach to thymic resection remains controversial. This study was conducted to assess the effect of maximal resection on neurologic outcome and identify predictors of disease remission.
Methods: Data of 78 myasthenic patients who underwent modified maximal thymectomy during a 17-year period were retrospectively analyzed. The primary study end point was the achievement of complete remission. Separate analysis was performed for thymoma and nonthymoma patients regarding the factors predicting the neurologic outcome.
Results: No patients died perioperatively. Surgical morbidity was 7.7%. The rate of postoperative myasthenic crisis was 3.8%. Thymoma and nonthymoma patients experienced comparable complete stable remission prediction (74.5% vs 85.7% at 15 years; p = 0.632). The absence of steroids in the preoperative medical treatment was statistically related to the prediction for complete stable remission in both thymoma (95% confidence interval [CI], 2.687 to 339.182, p = 0.006) and nonthymoma patients (95% CI, 1.607 to 19.183; p = 0.007) in multivariate analysis. In thymomatous myasthenia gravis, there was a statistically significant association between disease remission and the World Health Organization (WHO) histologic classification (95% CI, 0.262 to 0.827; p = 0.009).
Conclusions: Maximal resections are recommended in myasthenic patients. Disease severity represents the prime determinant of the neurologic outcome after thymectomy. The neurologic outcome in patients after thymectomy may be statistically associated with the WHO classification subtypes but not necessarily with the aggressiveness of these tumors.