Stiff person syndrome variant form (Q100609)

A number of variant forms of stiff person syndrome may occur as an autoimmune phenomenon without cancer or as a paraneoplastic autoimmune disorder. The major subtypes include stiff limb (involving only one extremity), stiff trunk (isolated to the trunk) and progressive encephalomyelitis rigidity and myoclonus (a more severe presentation involving multiple facets of the nervous system). Similar to classic stiff person syndrome [see classic stiff person syndrome] they are often accompanied by GAD65 autoantibodies but other neural autoantibodies may be found.