Autologous stem cell transplantation for stiff person syndrome: two cases from the Ottawa blood and marrow transplant program.

IMPORTANCE Stiff person syndrome (SPS) is a rare neurological disease causing significant functional disability for patients and presenting a therapeutic challenge for clinicians. Autologous hematopoietic stem cell transplantation (auto-HSCT) has been used successfully to remit autoimmune-mediated neurological diseases. We report 2 cases of severe SPS treated with auto-HSCT, a novel therapy for this disease. OBSERVATIONS Two anti-glutamic acid decarboxylase antibody-positive patients with SPS had an autologous hematopoietic stem cell graft collected and stored. Subsequently, the patients underwent auto-HSCT. Both patients achieved clinical remission with sustained, marked improvement in symptoms and a return to premorbid functioning, now more than 2.5 and 4.5 years after the procedure. CONCLUSIONS AND RELEVANCE Stiff person syndrome represents a novel indication for auto-HSCT. The resolution of clinical manifestations of SPS despite the persistence of anti-glutamic acid decarboxylase antibodies following auto-HSCT suggests that the antibody does not play a direct role in pathogenesis of SPS.