Prophylaxis of Hemiplegic Migraine
For hemiplegic migraine prophylaxis, start with flunarizine, sodium valproate (men only), lamotrigine, verapamil, or acetazolamide as first-line options, with anti-CGRP monoclonal antibodies emerging as highly effective alternatives when traditional agents fail or are contraindicated.
First-Line Prophylactic Medications
The evidence base for hemiplegic migraine (HM) prophylaxis differs substantially from typical migraine because HM patients are systematically excluded from randomized controlled trials. Treatment relies on empirical data and expert consensus 1.
Traditional first-line options include:
- Flunarizine (5-10 mg oral once daily) 2
- Sodium valproate (600-1,500 mg oral once daily) - absolutely contraindicated in women of childbearing potential 2, 1
- Lamotrigine - particularly useful given its anti-epileptic properties 1
- Verapamil (calcium channel blocker) 1
- Acetazolamide 1
Second-line options:
Critical Contraindications and Controversies
Beta-blockers (propranolol) remain controversial in HM. While one case report showed successful prophylaxis with propranolol in sporadic HM 3, and insufficient evidence exists to contraindicate beta-blockers outright 1, many experts exercise caution. The 2025 ACP guidelines recommend beta-blockers for typical episodic migraine 4, but their use in HM requires careful consideration given theoretical concerns about hemodynamic effects during motor aura.
Triptans are controversial for acute treatment and should be avoided during aura, though they may be considered for headache phase when common analgesics fail 1. This caution extends to the prophylactic decision-making process.
Emerging Evidence: Anti-CGRP Monoclonal Antibodies
The most compelling recent evidence supports anti-CGRP mAbs as highly effective in HM 5, 6. A 2026 quantitative analysis of 13 HM patients treated with anti-CGRP mAbs showed:
- 83% achieved >50% reduction in monthly headache days and aura frequency
- Median monthly days with aura decreased from 3 to 0.6 (p=0.018)
- MIDAS disability scores decreased from 88 to 28 (p=0.018)
- No adverse events reported 5
Available anti-CGRP mAbs include:
- Erenumab (70 or 140 mg subcutaneous monthly) 2
- Fremanezumab (225 mg subcutaneous monthly or 675 mg quarterly) 2
- Galcanezumab 7
- Eptinezumab (100 or 300 mg intravenous quarterly) 2
Treatment Algorithm
Step 1: Initiate prophylaxis when attack frequency exceeds 2 attacks per month or when severe attacks cause significant disability 1.
Step 2: Choose initial agent based on:
- Women of childbearing potential: Flunarizine, lamotrigine, verapamil, or acetazolamide (avoid valproate absolutely)
- Men: Any of the above plus sodium valproate
- Comorbid conditions: Consider topiramate if obesity present, verapamil if hypertension present
Step 3: Trial duration of 2-3 months for oral medications before declaring failure 2.
Step 4: If 2-3 traditional oral agents fail, strongly consider anti-CGRP mAbs given their superior tolerability and emerging evidence of effectiveness specifically in HM 5, 6.
Step 5: For anti-CGRP mAbs, assess efficacy after 3-6 months 2.
Dosing and Monitoring
Flunarizine: Start 5 mg daily, increase to 10 mg if needed. Monitor for depression and parkinsonism 2.
Sodium valproate: 600-1,500 mg daily. Monitor liver function and platelet counts. Never use in women of childbearing potential 2.
Lamotrigine: Titrate slowly to avoid rash (start 25 mg daily, increase by 25-50 mg every 1-2 weeks to target 100-200 mg daily).
Verapamil: Start 80 mg twice daily, titrate to 240-480 mg daily. Monitor ECG for PR interval prolongation.
Anti-CGRP mAbs: No routine monitoring required. Assess response at 3 months 5.
Critical Pitfalls to Avoid
- Never perform conventional cerebral angiography in HM - it may provoke an attack 1
- Do not use sodium valproate in any woman of childbearing potential - it is teratogenic 2
- Avoid premature discontinuation - allow adequate trial duration (2-3 months for oral agents, 3-6 months for mAbs)
- Do not assume beta-blockers are safe - while not absolutely contraindicated, use with caution 1
- Consider genetic testing but recognize it confirms rather than rules out diagnosis - only 3 genes identified (CACNA1A, ATP1A2, SCN1A) 1
Quality of Evidence Considerations
The evidence for HM prophylaxis is very low quality overall due to systematic exclusion from RCTs 5. However, the 2026 anti-CGRP mAb data represents the highest quality evidence specifically for HM, showing statistically significant reductions in aura burden and disability 5. Traditional recommendations rely on expert opinion and extrapolation from typical migraine studies 1.