Studies in myasthenia gravis: early thymectomy. Electrophysiologic and pathologic correlations.

Indications for thymectomy in myasthenia gravis have been recently expanded to include all cases with extraocular symptoms as a result of the minimal morbidity and negligible mortality of the transcervical approach. As increasing numbers of patients with myasthenia gravis, covering the entire spectrum of generalized disease, have been added to the thymectomy population, a more accurate evaluation of the effects of the operation is possible. Our experience with 353 patients who have undergone thymectomy indicates that early thymectomy, particularly in patients who do not have germinal centers, is followed by early remission of the disease. Delayed remission after thymectomy is related to the duration and severity of the disease, and to presence of thymic germinal centers. Germinal centers were found more frequently in patients with long duration of the disease and in patients in whom the disease had progressed to respiratory involvement. Marked improvement in electromyographic findings immediately after thymectomy was observed in the majority of patients who had had the disease for 1 year of less and where germinal centers were absent. The percentage of malignant thymomas was higher in patients who underwent thymectomy 1 year or more after the onset of symptoms of myasthenia gravis. These data indicate the importance of early thymectomy while the disease is still in the mild stages. Transcervical thymectomy is the treatment of choice as it is followed by a higher percentage of remissions and by less morbidity than other forms of treatment.