Extended thymectomy for myasthenia gravis patients: a 20-year review

Abstract

Background: Since 1973 we have performed extended thymectomy for myasthenia gravis because of the presence of thymic tissue in the anterior mediastinal fatty tissue. Follow-up results were reviewed and influencing factors were investigated.

Methods: Three hundred seventy-five patients with myasthenia gravis (286 nonthymomatous and 89 thymomatous) who have undergone extended thymectomies were reviewed. The status of the patients was evaluated as follows: A (remission), B (improvement), C (no change), D (deterioration), E (death due to myasthenia gravis). Evaluation was performed at 3 and 6 months, and at 1, 3, 5, 10, 15, and 20 years. The effectiveness of the operation was estimated by the remission rate (RR = A/Total number of patients evaluated) and the palliation rate (PR = A + B/Total number of patients evaluated) at each point.

Results: Remission rates of the nonthymomatous patients were 15.2% (3 months), 15.9% (6 months), 22.4% (1 year), 36.9% (3 years), 45.8% (5 years), 55.7% (10 years), 67.2% (15 years), and 50.0% (20 years). Remission rates in the thymomatous patients were 13.6% (3 months), 17.5% (6 months), 27.5% (1 year), 32.4% (3 years), 23.0% (5 years), 30.0% (10 years), 31.8% (15 years), and 37.5% (20 years). Absence of thymoma, younger age, and short duration of the disease were favorable prognostic factors. Thymectomy was effective also in patients with ocular myasthenia gravis. Preoperative steroid administration did not improve the outcome.

Conclusions: Extended thymectomy is an excellent operative procedure for myasthenia gravis in both nonthymomatous and thymomatous patients.