Rituximab treatment of stiff-person syndrome in a patient with thymoma, diabetes mellitus and autoimmune thyroiditis.

Stiff-person syndrome (SPS) is an autoimmune neurological disorder characterized by stiffness of the skeletal muscle with superimposed spasms and production of autoantibodies to glutamic acid decarboxylase (GAD) and amphiphysin. The disorder results from B cell-mediated clonal production of autoantibodies, requiring treatment with immunosuppressors; however, treatment results have been somewhat inconsistent. We report the results of rituximab treatment in a patient with SPS associated with a thymoma, diabetes mellitus, autoimmune thyroiditis and the presence of anti-GAD and anti-amphiphysin autoantibodies. The patient experienced a partial improvement following a thymectomy and the administration of prednisone, intravenous immunoglobulins and mycophenolate mofetil. Treatment with rituximab was followed by a complete sustained remission and the disappearance of serum anti-amphiphysin antibodies.

[Stiff person syndrome associated with thymoma. Efficacy of thymectomy]. / Syndrome de la personne raide associé à un thymome: efficacité de la thymectomie.

INTRODUCTION: 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. EXEGESIS: 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. CONCLUSIONS: 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.