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Understanding Hemiplegic Migraine: Finding Your Balance

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Hemiplegic migraine is a rare condition that causes temporary weakness on one side of the body, often mimicking a stroke. Whether familial or sporadic, these severe attacks are caused by a wave of electrical activity in the brain and are almost always fully reversible.

Key Takeaways

  • • Hemiplegic migraine is a rare condition affecting approximately 0.01% of the population.
  • • During an attack, patients experience temporary one-sided weakness (hemiparesis) and sometimes difficulty speaking (aphasia).
  • • The symptoms mimic a stroke but are almost always completely reversible.
  • • The underlying cause is a wave of brain electrical activity known as Cortical Spreading Depolarization.
  • • The condition is categorized as familial (FHM) or sporadic (SHM) depending on your family history.

If you or your child have just experienced an episode of one-sided weakness or difficulty speaking, the word “migraine” might feel far too small for what you went through. It is natural to feel a sense of terror when symptoms look so much like a stroke [1]. This guide is designed to help you catch your breath, understand the science of what happened, and move forward with a clear sense of what this diagnosis means.

A hemiplegic migraine is a rare and specialized type of migraine. It is estimated to affect only about 0.01% of the population [2]. During an attack, a person experiences hemiparesis (weakness on one side of the body) along with other symptoms like aphasia (difficulty speaking or understanding language) [1][3].

Because these symptoms are so dramatic, they often lead to an emergency room visit to rule out a stroke or seizure. While the experience is frightening, the most stabilizing fact is that these symptoms are almost always reversible [4]. For most people, the weakness resolves completely, though it may take anywhere from a few hours to several days for everything to return to normal [4][5].

Why It Happens: The “Brain Tsunami”

The primary mechanism behind this condition is a phenomenon called Cortical Spreading Depolarization (CSD) [6].

Imagine a slow-moving wave or a “tsunami” of electrical activity that travels across the surface of the brain [7]. As this wave passes, it leaves a temporary “electrochemical silence” in its wake [7][8].

  • When this wave passes through the part of the brain that controls movement, you feel weakness [9].
  • When it passes through the language center, you may struggle to speak or find words [9][10].

In hemiplegic migraine, this wave is often more intense or lasts longer than in a typical migraine with aura [10].

Understanding Your Type: FHM vs. SHM

Doctors categorize hemiplegic migraine into two types based on your family history. The symptoms and the underlying science are essentially the same for both [11][12].

  • Familial Hemiplegic Migraine (FHM): Diagnosed if you have at least one close relative who experiences these specific attacks [1][11].
  • Sporadic Hemiplegic Migraine (SHM): Diagnosed when no other family members have the condition, often due to a new (“de novo”) genetic change [1][13].

Guide Index

To help you navigate this complex diagnosis, we have created dedicated pages covering everything from the biology of the disease to how to manage it:

Frequently Asked Questions

What is the difference between familial and sporadic hemiplegic migraine?
Familial hemiplegic migraine (FHM) means you have at least one close relative who experiences these specific attacks. Sporadic hemiplegic migraine (SHM) is diagnosed when no other family members have the condition, often due to a new genetic change.
Why does a hemiplegic migraine cause weakness on one side of the body?
The weakness is caused by a phenomenon called Cortical Spreading Depolarization. This acts like a slow-moving wave of electrical activity across the brain. When this wave passes through the part of the brain that controls movement, it causes temporary one-sided weakness.
Are the symptoms of a hemiplegic migraine permanent?
No, the symptoms of a hemiplegic migraine are almost always temporary and completely reversible. While the weakness or difficulty speaking can last from a few hours to several days, most people make a full recovery after an attack.
When should I go to the ER for a hemiplegic migraine?
If you experience new one-sided weakness or difficulty speaking, you should seek emergency medical care to rule out a stroke or seizure. Once you have an established diagnosis, work with your doctor to define specific 'red flag' symptoms that warrant an ER visit.

Questions for Your Doctor

  • • Based on our family history, do you suspect this is Familial (FHM) or Sporadic (SHM) Hemiplegic Migraine?
  • • What is the typical duration of symptoms for someone with this specific profile?
  • • Are there any medications that we should specifically avoid because of the risk of one-sided weakness?
  • • What are the 'red flag' symptoms that should trigger an immediate call to your office or a trip to the ER?

Questions for You

  • • What specific symptoms occurred before the weakness started (e.g., seeing spots, feeling numb, or trouble finding words)?
  • • How long did the weakness last, and did it resolve completely or gradually?
  • • Are there any first- or second-degree relatives who have ever had similar episodes of weakness with a headache?

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References

  1. 1

    A case report of sporadic hemiplegic migraine associated cerebral hypoperfusion: comparison of arterial spin labeling and dynamic susceptibility contrast perfusion MR imaging.

    Kim S, Kang M, Choi S

    European journal of pediatrics 2016; (175(2)):295-8 doi:10.1007/s00431-015-2609-2.

    PMID: 26250760
  2. 2

    [Familial hemiplegic migraine].

    Starikova NL, Kulesh AA

    Zhurnal nevrologii i psikhiatrii imeni S.S. Korsakova 2021; (121(7)):114-117 doi:10.17116/jnevro2021121071114.

    PMID: 34460166
  3. 3

    A Chinese family with familial hemiplegic migraine type 2 due to a novel missense mutation in ATP1A2.

    Tang W, Zhang M, Qiu E, et al.

    Cephalalgia : an international journal of headache 2019; (39(11)):1382-1395 doi:10.1177/0333102419847738.

    PMID: 31053037
  4. 4

    Familial "Diplegic" Migraine - Description of a Family With a Novel CACNA1A Mutation.

    Sprouse Blum AS, Couperus CJ, Rosen BJ, et al.

    Headache 2020; (60(3)):600-606 doi:10.1111/head.13741.

    PMID: 31967333
  5. 5

    Familial hemiplegic migraine in Indian children-a tertiary center experience.

    Saini L, Gunasekaran PK, Tiwari S, et al.

    Journal of tropical pediatrics 2024; (70(3)) doi:10.1093/tropej/fmae008.

    PMID: 38580379
  6. 6

    First FHM3 mouse model shows spontaneous cortical spreading depolarizations.

    Jansen NA, Dehghani A, Linssen MML, et al.

    Annals of clinical and translational neurology 2020; (7(1)):132-138 doi:10.1002/acn3.50971.

    PMID: 31880072
  7. 7

    Upregulation of IL-1 Receptor Antagonist in a Mouse Model of Migraine.

    Lombardo SD, Mazzon E, Basile MS, et al.

    Brain sciences 2019; (9(7)) doi:10.3390/brainsci9070172.

    PMID: 31331109
  8. 8

    Caffeine does not affect susceptibility to cortical spreading depolarization in mice.

    Yalcin N, Chen SP, Yu ES, et al.

    Journal of cerebral blood flow and metabolism : official journal of the International Society of Cerebral Blood Flow and Metabolism 2019; (39(4)):740-750 doi:10.1177/0271678X18768955.

    PMID: 29651899
  9. 9

    Specific activation of GluN1-N2B NMDA receptors underlies facilitation of cortical spreading depression in a genetic mouse model of migraine with reduced astrocytic glutamate clearance.

    Crivellaro G, Tottene A, Vitale M, et al.

    Neurobiology of disease 2021; (156()):105419 doi:10.1016/j.nbd.2021.105419.

    PMID: 34111520
  10. 10

    Hyperexcitable interneurons trigger cortical spreading depression in an Scn1a migraine model.

    Auffenberg E, Hedrich UB, Barbieri R, et al.

    The Journal of clinical investigation 2021; (131(21)).

    PMID: 34546973
  11. 11

    Serial magnetic resonance imaging findings during severe attacks of familial hemiplegic migraine type 2: a case report.

    Fear D, Patel M, Zand R

    BMC neurology 2021; (21(1)):173 doi:10.1186/s12883-021-02201-z.

    PMID: 33882852
  12. 12

    Familial hemiplegic migraine.

    Villar-Martinez MD, Moreno-Ajona D, Goadsby PJ

    Handbook of clinical neurology 2024; (203()):135-144 doi:10.1016/B978-0-323-90820-7.00007-0.

    PMID: 39174245
  13. 13

    De novo exonic duplication of ATP1A2 in Italian patient with hemiplegic migraine: a case report.

    Gagliardi S, Grieco GS, Gualandi F, et al.

    The journal of headache and pain 2017; (18(1)):63 doi:10.1186/s10194-017-0770-x.

    PMID: 28593511

This page provides an overview of hemiplegic migraine for educational purposes only. Because its symptoms closely mimic those of a stroke, new episodes of one-sided weakness require immediate professional medical evaluation.

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