Thymic abnormalities: antigen or antibody? Response to thymectomy in myasthenia gravis

The therapeutic value of thymectomy for myasthenia is still questioned although it retains an important place among management modalities that strive for sustained remission. Questions derive from uncertainty as to appropriate timing, variable extent of resection and quantitation of response. Forty-seven patients, followed one to seven years, underwent an extended transsternal or combined transcervical-transsternal procedure with anterior mediastinal exenteration. Sixteen have been in complete remission from six months to six years, four are asymptomatic on occasional pyridostigmine and eight are significantly improved. Evaluation of thymic pathology (hyperplasic, involuted areas, and thymoma) included a search for thymic myoid cells by fluorescence cytochemistry. Antibodies to acetylcholine receptor present in 38 of 43, decreased post-operatively to normal in four, by 50% to 80% in 14, by 20 to 50% in three and were unchanged in 14. Most remissions occurred in young women with noninvoluted hyperplastic glands and variably high anti-AChR titers which dropped toward normal in seven of 15. These results encourage us to utilize this procedure routinely.