Fig. 1.

Anatomical involvement of musculoskeletal symptoms among stiff person syndrome spectrum disorders. Locations where participants experienced stiffness and/or spasms based on phenotype. In classic stiff person syndrome (SPS), SPS-plus, and progressive encephalomyelitis with rigidity and myoclonus (PERM) phenotypes, the most commonly affected regions were the axial musculature (torso, back) and lower limbs. PERM had higher proportion of neck/cervical musculature affected. In partial SPS, lower limb was most commonly affected. Color scheme with red indicating higher and blue indicating lower proportion affected