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Stiff Person Syndrome — SCE Neurology MCQ

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HardPeripheral Neuropathy & NeuromuscularStiff Person SyndromeSCE Neurology

A 38-year-old woman presents with stiffness and spasms of the trunk and proximal limbs, a lumbar hyperlordosis, and falls due to sudden startle-induced spasms. She has type 1 diabetes mellitus. EMG shows continuous motor unit activity in paraspinal and abdominal muscles. Which antibody is most likely to be found?

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Correct answer: C — Anti-GAD65 antibodies

Stiff person syndrome (SPS) is characterised by progressive axial rigidity (lumbar hyperlordosis), episodic painful spasms triggered by startle, and continuous motor unit activity on EMG. Anti-GAD65 antibodies are positive in approximately 80% of cases and are associated with type 1 diabetes mellitus. A: Anti-NMDA receptor antibodies cause autoimmune encephalitis. C: Anti-Hu causes paraneoplastic syndromes. D: Anti-amphiphysin antibodies can cause SPS variant (paraneoplastic stiff person syndrome – associated with breast cancer). E: Anti-CASPR2 causes Morvan syndrome/neuromyotonia.

Reference: EAN SPS Guidelines; ABN Autoimmune Neurology Guidelines