What are the recommended diagnostic criteria, acute treatment options, and preventive strategies for hemiplegic migraine?

Hemiplegic Migraine: Diagnostic Criteria, Acute Treatment, and Prevention

Diagnostic Criteria

Hemiplegic migraine is diagnosed when a patient experiences motor weakness during the aura phase, distinguishing it from typical migraine with aura. 1

• Motor aura must include transient hemiparesis lasting <72 hours, often accompanied by visual or sensory symptoms, speech impairment, or brainstem aura 1
• Two subtypes exist: familial hemiplegic migraine (FHM) with autosomal dominant inheritance, and sporadic hemiplegic migraine (SHM) with no family history 1, 2
• Genetic mutations in CACNA1A, ATP1A2, and SCN1A are implicated in approximately 50% of FHM cases, though other unknown genes are involved 1, 2
• Red-flag exclusion is mandatory: rule out stroke, transient ischemic attack, cerebral venous thrombosis, and other secondary causes through neuroimaging (MRI preferred), CSF analysis if indicated, and EEG 1, 2
• Conventional cerebral angiography is absolutely contraindicated in hemiplegic migraine because it can provoke a severe attack 2
• Additional features that may accompany attacks include impaired consciousness, cerebellar ataxia, intellectual disability, and prolonged aura symptoms lasting days 1, 3

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Acute Treatment Options

Acetaminophen and NSAIDs are the first-line acute treatments for hemiplegic migraine attacks. 2

First-Line Acute Therapy

• Acetaminophen 1000 mg or NSAIDs (ibuprofen 400–800 mg, naproxen 500–825 mg) should be administered at the earliest sign of headache 2, 4
• These agents are safe and do not carry the theoretical risks associated with triptans in hemiplegic migraine 2

Triptan Use: Controversial but Not Absolutely Contraindicated

• Triptans can be prescribed when common analgesics fail, despite historical concerns about their use in hemiplegic migraine 2
• The evidence for adverse effects from triptans in hemiplegic migraine is insufficient to contraindicate them entirely 2
• Subcutaneous sumatriptan 6 mg provides the highest efficacy (59% pain-free at 2 hours) and may be considered for severe attacks when NSAIDs fail 5, 6
• Clinical judgment is required: avoid triptans if the patient has cardiovascular disease, uncontrolled hypertension, or cerebrovascular disease 2

Emergency Department Parenteral Options

• Prochlorperazine 10 mg IV is highly likely to be effective and must be offered to eligible adults presenting to the ED with severe migraine 5
• Metoclopramide 10 mg IV provides direct analgesia through central dopamine antagonism and should be offered 5
• Ketorolac 30 mg IV has rapid onset with approximately 6 hours of analgesia and should be offered 5
• Greater occipital nerve block (GONB) is highly likely to be effective and must be offered as a non-pharmacologic parenteral option 5

Medications to Absolutely Avoid

• Opioids (hydromorphone, morphine, codeine, tramadol) must not be offered because they are likely ineffective and carry high risk of medication-overuse headache and dependence 5
• Propofol IV must not be offered because it is likely ineffective for acute migraine treatment 5

Treatment of Prolonged Aura

• No effective acute treatment exists for the motor aura symptoms themselves, which may last hours to days 2
• Hospitalization may be required for long-lasting auras to monitor for complications and provide supportive care 1

Medication-Overuse Prevention

• Limit all acute medications to ≤2 days per week (≤10 days per month) to prevent medication-overuse headache, which can convert episodic hemiplegic migraine into chronic daily headache 2, 4

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Preventive Strategies

Preventive therapy is indicated when attack frequency exceeds 2 attacks per month or when severe attacks pose a great burden requiring reduction of severity and frequency. 2

First-Line Preventive Options

Verapamil is traditionally considered the safest first-line preventive agent for hemiplegic migraine. 7, 2, 8

• Verapamil (dose not specified in guidelines but typically 120–480 mg/day) has shown promise in clinical experience and lacks the neurological side effects of other agents 7, 2, 8
• Flunarizine is another calcium channel blocker option with evidence in hemiplegic migraine 2
• Acetazolamide has shown promise, particularly in familial hemiplegic migraine 2, 8

Second-Line Preventive Options

• Sodium valproate 800–1500 mg/day or divalproex sodium 500–1500 mg/day can be tried, but are strictly contraindicated in all individuals of child-bearing potential due to teratogenic risk 9, 2
• Lamotrigine can be considered as a second-line option 2

Topiramate: Use with Caution

• Topiramate should be used cautiously in hemiplegic migraine because its carbonic anhydrase inhibition can induce metabolic acidosis, theoretically worsening neurological function during hemiplegic episodes 7
• If topiramate must be used: monitor serum bicarbonate levels before and during treatment, and discontinue immediately if new or worsening motor symptoms develop 7

Beta-Blockers: Controversial

• Propranolol use is controversial in hemiplegic migraine, though evidence of adverse effects is insufficient to contraindicate beta-blockers entirely 2, 6
• Propranolol 80–240 mg/day was effective in one case report of sporadic hemiplegic migraine, preventing recurrent paralysis over 2 years 6

Novel CGRP Monoclonal Antibodies: Emerging Evidence

CGRP monoclonal antibodies represent a promising new option for hemiplegic migraine prevention with strong safety profiles. 7, 10

• Galcanezumab reduced monthly headache days and days with motor weakness in 4 of 6 patients with hemiplegic migraine after 3 months of treatment 10
• Erenumab, fremanezumab, and galcanezumab have strong evidence for migraine prevention and lack the neurological side effects of topiramate 7
• No adverse events were reported in the hemiplegic migraine case series treated with galcanezumab 10
• CGRP antibodies should be considered first-line alternatives to topiramate, especially when neurological side effects are a concern 7

Other Options with Limited Evidence

• Candesartan and pizotifen can be considered, though less evidence is available 2

Trial Duration

• Maintain the target dose for 2–3 months before judging efficacy of oral preventive agents 9
• CGRP monoclonal antibodies require 3–6 months for full efficacy assessment 10

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Common Pitfalls and Caveats

• Do not perform conventional cerebral angiography in patients with suspected hemiplegic migraine, as it can trigger a severe attack 2
• Do not assume all transient hemiplegia is hemiplegic migraine: always exclude stroke, TIA, and other secondary causes with appropriate neuroimaging 1, 2
• Do not withhold triptans categorically in hemiplegic migraine; the evidence for harm is insufficient, and they may be necessary when NSAIDs fail 2
• Do not prescribe opioids or butalbital compounds as rescue therapy, as they worsen long-term outcomes and increase medication-overuse headache risk 5
• Do not use topiramate as first-line prevention without considering safer alternatives like verapamil or CGRP antibodies, especially given the theoretical risk of worsening motor symptoms 7
• Genetic testing can confirm but not rule out hemiplegic migraine, as many cases involve unknown genes 1, 2