[Stiff-Person Syndrome: Results of the First Nationwide Survey in Japan].

Stiff-person syndrome (SPS) is a rare autoimmune neurological disorder characterized by progressive axial muscle stiffness, central nervous system hyperexcitability, and painful stimulus-sensitive muscle spasms. A nationwide survey performed in 2018 showed the estimated prevalence of SPS was 0.2 per 100,000 population. Most patients with SPS had antibodies against glutamic acid decarboxylase 65, followed by antibodies to the glycine receptor α-subunit. Usually, patients with SPS showed favorable outcomes; however, some studies have reported intractable SPS. Early diagnosis and aggressive immunotherapy are necessary for management of patients with SPS.