Familial Hemiplegic Migraine Type 1 — SCE Neurology MCQ

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HardHeadache & Facial PainFamilial Hemiplegic Migraine Type 1SCE Neurology

A 22-year-old woman presents with sudden onset of bilateral arm and leg weakness during an episode of migraine with visual aura. She has a family history of similar episodes in her mother and brother. Genetic testing reveals a mutation in the CACNA1A gene. What is the diagnosis?

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Correct answer: D — Familial hemiplegic migraine type 1

Familial hemiplegic migraine type 1 (FHM1) is caused by mutations in the CACNA1A gene (P/Q-type calcium channel subunit). It is autosomal dominant and characterised by migraine with aura including reversible motor weakness (hemiplegia or bilateral weakness). FHM2 involves ATP1A2 (Na+/K+ ATPase), and FHM3 involves SCN1A (sodium channel). Interestingly, CACNA1A mutations also cause episodic ataxia type 2 and SCA6, representing a phenotypic spectrum. A: Typical aura does not include motor weakness. B: Sporadic HM has no family history. D: Basilar-type migraine lacks motor weakness. E: EA2 has episodic ataxia without hemiplegia (though caused by the same gene).

Reference: ICHD-3 (2018); EAN Headache Guidelines