Stiff person syndrome spectrum disorder (SPSSD) consists of a rare set of diseases characterized by severe muscle stiffness and rigidity with decline in function. Although poorly understood, an underlying autoimmune disorder interfering with the CNS inhibitory mechanism is likely the culprit. The spectrum ranges from a mild disease affecting focal muscles to a severe form that also includes the development of seizures and myoclonus.
GAD-abs are frequently positive, especially in classic SPS. In SPS-plus/PERM, GlyR-abs are more commonly found. Patients with amphiphysin-ab should be screened for cancer. Treatment includes the GABA agonists, especially diazepam and baclofen. Patients with SPS-plus or refractory forms of the disease should be treated with immunomodulation, especially IVIG.
KeywordsStiff-person syndrome Stiff-person syndrome spectrum disorders (SPSSD) Autoimmune disease Muscle rigidity Classic SPS Stiff-limb syndrome SPS-plus Progressive encephalomyelitis with rigidity and myoclonus (PERM) Encephalomyelitis Seizures Myoclonus Diabetes mellitus Pernicious anemia Vitiligo Autoimmune thyroid disease DQB1∗0201 allele
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