Stiff person syndrome
（重定向自Stiff man syndrome）
Stiff person syndrome (SPS) is a rare neurologic disorder of unclear etiology characterized by progressive rigidity and stiffness. The stiffness primarily affects the truncal muscles and is superimposed by spasms, resulting in postural deformities. Chronic pain, impaired mobility, and lumbar hyperlordosis are common symptoms. The exact mechanism of the condition is unclear.