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LGI1 antibody encephalitis — SCE Neurology MCQ

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HardCNS inflammationLGI1 antibody encephalitisSCE Neurology

A 27-year-old develops focal seizures, fever and aphasia. MRI shows unilateral cortical FLAIR hyperintensity with overlying leptomeningeal enhancement and no white-matter lesion. CSF has 22 lymphocytes/µL; HSV PCR is repeatedly negative. Which antibody test is most relevant next?

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Correct answer: E — Serum MOG-IgG using a live cell-based assay

Explanation lettering: E = shown as A · C = shown as B · D = shown as C · A = shown as D · B = shown as E

B is correct: MOG-IgG-associated cortical encephalitis can present with seizures, cortical FLAIR hyperintensity and leptomeningeal enhancement, sometimes without optic neuritis or myelitis. A validated serum cell-based assay is the preferred test. AQP4 disease rarely produces this isolated cortical seizure syndrome. Hu autoimmunity is generally a paraneoplastic intracellular-antigen syndrome and a line blot alone is insufficient. Glycine-receptor antibodies fit PERM or hyperekplexia rather than unilateral cortical encephalitis.

Reference: Autoimmune encephalitis: clinical spectrum and management: https://pn.bmj.com/content/21/5/412