Stiff Person Syndrome: A Case Report with Sudden Onset and Coexistence of Sero-Positive Antibodies to Glutamic Acid Decarboxylase and Anti-SOX1 Antibodies.

Stiff Person Syndrome (SPS) is an extremely rare neurological condition characterized by muscle stiffness and painful muscle spasms. The symptoms often progress slowly and can cause disability. Antibodies to glutamic acid decarboxylase (anti-GAD) have been reported in up to 80% of the classic type of SPS. Paraneoplastic syndrome comprises 5% of SPS cases. These patients present with different malignancies including lung, thymus, breast, colon, and lymph nodes. In this paper, we report a case of a 25-year-old Vietnamese female patient with SPS presenting with unusual clinical manifestations of sudden onset, rapidly progressive spinal, abdominal, and lower limb rigidity accompanied by painful spasms, autonomic disorders, and severe, multiple bone fractures. Serologic tests detected high-titer anti-GAD, combined with anti-SOX1 antibodies, suggesting paraneoplastic SPS. Intravenous immunoglobulin has been employed as the main treatment therapy, and the patient has had a complete remission.