Myoclonus associated with hyperthyroidism and thymoma: a case report.

Movement disorders associated with hyperthyroidism or thymoma are extremely rare. A 52-year-old woman had developed myoclonus since June, 1989. Hyperthyroidism and thymoma were diagnosed 1 month and 9 months later. Myoclonus improved after thyroid treatment and thymectomy. If the association was not only a coincident phenomenon, autoimmunity should be considered in this previously unrecognized association.