Thymectomy in Patients with Myasthenia Gravis

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Myasthenia gravis is a neuromuscular transmission disorder characterized by fatigue and weakness of voluntary muscles. Although the pathogenesis is known as reduction of available acetylcholine receptors at neuromuscular junctions by autoimmune attack, the thymic role in myasthenia gravis is still unclear and under investigation. But thymectomy in the management of myasthenia gravis has become increasingly important since the first successful operation with remission of symptoms in 1939 by Blalock. From January 1983 to June 1985, authors performed 17 thymectomies for patients with myasthenia gravis. Among them, 12 patients were free from thymoma [Croup A] and 5 were coupled with thymoma [Group B]. The results were as follows: 1] Sex distribution was 11 females and 6 males. Mean age of the patients was 32.2 year old. Sex and age distribution by the Group A and B are shown Table 1. 2] Clinical manifestations of ocular symptoms were seen in 5 patients [88.2%], extremity weakness in 13 patients, bulbar weakness in 12 patients and dyspnea in 6 patients. According to the Osserman`s classification, 5 patients were in group IIA, 6 in IIB and 6 in IIC. 3] Pre-operatively, all patients were positive response to the anti-cholinesterase test and 12 patients [92.3%] revealed positive findings in electromyography [EMC] which was done in 13 patients. 4] The postoperative complications were respiratory distress in 3 patients, myasthenic crisis in 2 patients and wound disruption in one patients. 5] Pathologic examination of the thymus showed hyperplasia in 10 patients [90%] and thymoma in 5 patients, of which 4 were mixed type with invasion to the adjacent tissues and one lymphocytic type without invasion. Normal thymus was noticed in only 2 patients. 6] In postoperative evaluations, among the 12 patients c free from thymoma [Group A], complete remission of symptoms was noticed in 3 patients and improvement in 7 patients. But among the 5 patients coupled with thymoma [Group B], only one patients showed improvement [Table 8]. Therefore, remission and clinical improvement were noticed in 11 patients [64.7%] of the all and complete remission was noticed in 3 patients [17.6%].