Stiff person syndrome associated with thymoma. Efficacy of thymectomy

Stiff person syndrome is a rare autoimmune neurologic disorder characterized by axial muscular rigidity and intermittent painful spasms. Three distinct forms are described: auto-immune, paraneoplastic and idiopathic. We report the case of a 51-year-old man with an history of Stiff Person Syndrome with typical clinical, electrophysiological and immunological findings. Anti-glutamic acid decarboxylase antibodies were present, as well as anti-amphiphysin antibodies, commonly reported in the paraneoplastic syndrome. CT scan revealed a thymoma. Surgical resection was followed by reduction of the neurologic symptoms, without lowering the auto antibodies titer. The association between Stiff Person Syndrome and thymoma is exceptional. Thymectomy is an effective treatment and may act without change of the autoantibodies titer. Patients with Stiff Person Syndrome should be systematically tested for thymoma.