Anti-LGI1 Encephalitis – Faciobrachial Dystonic Seizures — SCE Neurology MCQ

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HardCNS InfectionsAnti-LGI1 Encephalitis – Faciobrachial Dystonic SeizuresSCE Neurology

A 63-year-old develops severe insomnia, fluctuating confusion, profuse sweating, constipation, burning neuropathic pain and continuous calf myokymia. MRI brain is normal; EEG shows diffuse slowing and electromyography shows neuromyotonic discharges. Which antibody is the best fit?

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Correct answer: B — CASPR2 antibody

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

A is more strongly linked to faciobrachial dystonic seizures, hyponatraemia and limbic encephalitis without prominent neuromyotonia. B is correct: Morvan syndrome combines encephalopathy, agrypnia, dysautonomia, pain and peripheral nerve hyperexcitability and is classically CASPR2-associated. C usually causes limbic seizures and has a strong small-cell-lung-cancer association. D causes stiff-person/PERM phenotypes. E may cause encephalopathy, startle and gastrointestinal hyperexcitability but does not best explain neuromyotonia.

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