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Summary

Stiff person syndrome (SPS) is a rare disease with an unclear pathogenesis, which presents with muscle stiffness and spasms. Symptoms are usually progressive and begin with gradual, intermittent, mildly painful muscle spasms that primarily affect the lower extremities and paraspinal muscles. These localized spasms later increase in frequency and intensity, occasionally becoming so severe that they produce painful abnormal postures, disability, and even fractured bones. Spasms can also be highly susceptible to multiple triggers such as touch, loud noise, and even emotion, and typically resolve with sleep.