Stiff person syndrome spectrum disorders; more than meets the eye

Stiff person syndrome spectrum disorders (SPSD) are a group of rare neuroimmunological disorders that often include painful spasms and rigidity. However, patients have highly heterogeneous signs and symptoms which may reflect different mechanistic disease processes. Understanding subsets of patients based on clinical phenotype may be important for prognosis and guiding treatment. The goal of this review is to provide updates on SPSD and its expanding clinical spectrum, prognostic markers, and treatment considerations. Further, we describe the current understanding in immunopathogenesis and highlight gaps in our knowledge appropriate for future research directions. Examples of revised diagnostic criteria for SPSD based on phenotype are also presented. [Display omitted] •Stiff person syndrome spectrum disorders (SPSD) are immune mediated and impact different regions of the nervous system.•SPSD have heterogenous presentations and are under-recognized.•A combination of pharmacological and non-pharmacological interventions can help mitigate the burden of disease in SPSD.•Advances in understanding of pathogenic mechanisms are important for guiding therapy development.