Background: Extended thymectomy is one of several types of thymectomy. Literature suggests that the outcome and prognosis will be enhanced by performing a more extensive resection of the gland and of the anterior mediastinum tissue. Objective: To retrospectively evaluate response of MG patients to extended thymectomy. Method: From August 1992 to January 2003, forty-six MG patients were submitted to preoperative plasmapheresis and extended thymectomy. According to the time elapsed since onset of symptom they were divided into three groups; < 12 months, 13 to 24 months, and > 25 months. Results: There were 31 female and 15 male patients, mean age 30 years and average evolution time 26.3 months. Outpatient post-operative follow-up was on the average of 26.6 months. Level of response was good, 50% had full remission and a further 39% had good response. There was one death. The most common histopathology finding was thymic hyperplasia. Only 3 patients (6.5%) had benign thymomas; 5 (10.8%) had extra glandular thymic tissue: 2 in the perithymic fat and 3 in the pericardiac fat adjacent to the left phrenic nerve and aortal-pulmonary window. Conclusion: Treatment of MG by extended thymectomy is safe and efficient with high levels of complete remission. Extra glandular thymic tissue was found in some patients. As soon as diagnosis is completed, thymectomy is indicated together with plasmapheresis and medication, independent of age, onset of symptoms, and thymus pathology.

Keywords: Thymectomy/methods. Myasthenia gravis/pathology. Neuromuscular diseases/rehabilitation.