Definition: A subtype of migraine with aura, characterized by symptoms referable to the brainstem and cerebellum, often due to vasospasm of the basilar artery.
Headache may be absent initially, but typically develops later.
Diagnostic Criteria (IHS):
At least two attacks fulfilling criteria A–D.
Aura symptoms develop over ≥5 minutes, last 5–60 minutes, and are not better explained by another disorder.
At least three of the following: dysarthria, vertigo, tinnitus, decreased hearing, diplopia, ataxia, decreased level of consciousness, or bilateral paresthesias.
Not attributed to another disorder.
Differential Diagnosis:
Basilar Artery Occlusion (BAO): Sudden onset of brainstem symptoms (e.g., crossed hemiparesis, cranial nerve palsies) with prolonged deficits (>24 hours), often with imaging evidence of infarction.
Vertebrobasilar TIA: Symptoms similar to BAM but shorter duration (5–30 minutes), often repetitive.
Posterior Circulation Stroke: Persistent deficits, often with imaging confirmation.
Management:
Acute: Triptans (e.g., sumatriptan 6 mg SC) or dihydroergotamine 1 mg IV (if no contraindications).
Prophylaxis: Beta-blockers (e.g., metoprolol), calcium channel blockers (e.g., verapamil), or topiramate (if vascular risk factors are absent).
Avoid vasoconstrictors (e.g., ergotamines) in suspected BAO.
Rationale: BAM is a functional disorder with reversible vasospasm, while BAO/TIA/stroke require urgent vascular workup (e.g., MRI/MRA, echo, Holter) and secondary prevention (e.g., antiplatelets, statins).
Key Distinction:
BAM: Symptoms resolve without infarction; no vascular risk factors typically present.
BAO/TIA/Stroke: Persistent deficits, vascular risk factors, and imaging abnormalities.