Stiff person syndrome with ampiphysin antibodies: distinctive feature of a rare disease

Murinson BB, Guarnaccia JB. Neurology 2008; 71: 1955-58.

Principal form of SPS has stiffness of the spine and legs with spasms worse with emotional stress and triggers, and associated with anti GAD antibodies. Variants include less strong association with anti GAD AB, and limited stiff limb syndrome, and a progressive variant with encephalomyelitis, rigidity and myoclonus (PERM).

A distinct form with ampiphysin antibodies is a small subset (11/126 cases) and has the following distinctive features: association with breast cancer (10/11), female exclusively, mean age close to 58, association with other paraneoplastic antibodies and other neurologic disorders including sensory neuronopathy, encephalopathy, and myelopathy. Treatment may involve steroids, plasmapx or cancer treatment rather than IVIG as in anti GAD ab associated disease.

Clinically, all had stiffness and rigidity, half had pain, NONE had diabetes, EMG was positive for continuous motor activity or consistent with SPS. Nine were responsive to very high dose benzodiazepines (> 50 mg.day diazepam), none responsed to IVIG. Arm or neck involvement was specifically cited by referring physician in 80 % of the cases. Some patients responded completely to excision of the tumor.

Lab testing with immunocytochemisty is not sufficient, ELISA or RIA is needed and special labs are needed to test for this antibody.