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Video-EEG functional seizure — SCE Neurology MCQ

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HardNeurological InvestigationsVideo-EEG functional seizureSCE Neurology

A 24-year-old with childhood-onset epilepsy, developmental impairment and progressive ataxia has very low CSF 5-methyltetrahydrofolate despite normal serum folate. Biallelic FOLR1 variants are found. Which treatment is mechanistically appropriate?

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Correct answer: C — High-dose oral folinic acid replacement

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

B is correct: FOLR1-related cerebral folate transport deficiency requires reduced folate replacement with folinic acid, which can improve or stabilise seizures and neurological deterioration. Folic acid is not interchangeable and may compete at folate receptors, so it is specifically avoided. Normal serum folate does not correct the CNS transport defect. Vitamin B12 treats a different one-carbon metabolic problem. A ketogenic diet may help selected epilepsies but does not replace the missing cerebral folate pathway.

Reference: Investigating adults with early-onset epilepsy and intellectual or physical disability: https://pn.bmj.com/content/19/2/115