Pediatric stiff limb syndrome with polyautoimmunity of anti-GAD-65, anti-islet cell, and thyroid peroxidase antibodies: A case report and review of literature.

We report an early childhood onset Stiff Limb Syndrome (SLS) in association with unusual polyautoimmunity of GAD-65, anti-islet cell, and Thyroid Peroxidase (TPO) autoantibodies, who has achieved a nearly complete neurological recovery following combined immunotherapy, symptomatic and physical therapy. The patient had normal MRIs of the brain and spinal cord and a negative paraneoplastic work-up. Subsequently, she developed hypothyroidism requiring levothyroxine supplementation. We then conducted an extensive review of literature and identified 52 previously reported pediatric Stiff Man Syndrome (SMS)/Stiff Person Syndrome (SPS) or SLS cases, which has demonstrated a common association with other systemic autoimmune conditions. In the available literature, screening for concurrent autoimmunity has only been reported infrequently. We found that a paraneoplastic process is extremely rare in pediatric cases. Timely diagnosis and initiation of immunotherapy are critical to a favorable outcome. Therefore, we recommend to include SMS/SPS or SLS as an important differential diagnosis for MRI-negative myelopathy. Further clinical and research efforts should be focused on understanding the role of both genetic predisposition and environmental insults in the autoimmunity of pediatric SMS/SPS or SLS.