Hemiplegic migraine is a rare form of migraine with aura in which the migraine aura is characterised by motor weakness, usually on one side of the body.
Hemiplegic migraine can be genetic (known as familial hemiplegic migraine) or sporadic. Some, but not all, gene mutations have been identified as causing familial hemiplegic migraine.
Hemiplegic migraine can be dangerous because its symptoms are similar to those for stroke, epilepsy and other potentially serious neurological conditions, meaning hemiplegic migraine attacks can mask other serious medical issues.
This article can help you understand the symptoms and treatment of Hemiplegic Migraine. Click the headings below to jump to a specific section.
- What is Hemiplegic Migraine?
- Types and causes of Hemiplegic Migraine
- What happens during a hemiplegic migraine attack?
- Triggers for hemiplegic migraine attacks
- Medical assistance
- Further information & resources
What is Hemiplegic Migraine?
Hemiplegic migraine is a rare migraine disorder characterised by a specific type of aura that people with hemiplegic migraine experience.
Migraine aura refers to a collection of fully reversible neurological symptoms that many people with migraine experience before or during an attack.
In typical migraine with aura, the aura can affect one or more of a person’s visual, sensory or language and speech functions. The most common aura is visual (eg blind spots, pixelated vision, flashing lights).
Hemiplegic migraine is migraine with aura, in which the migraine aura also affects the person’s motor function (1). That is, people with hemiplegic migraine experience motor weakness in addition to the symptoms of typical migraine with aura.
These hemiplegic symptoms are caused when electrical nerve impulses in the brain malfunction and cause neurotransmitters (the brain’s chemical ‘messengers’) to be released in an abnormal way.
The term, ‘hemiplegia’, is derived from the Greek, ‘hemi’ meaning ‘half’, and ‘plegia’ meaning ‘to strike’, or ‘stroke’. In modern usage, ‘plegia’ means paralysis, although most people with hemiplegia experience weakness rather than paralysis. As the name suggests, hemiplegic migraine symptoms are often experienced on one side of the body, and are stroke-like. In addition to motor weakness, symptoms during an attack can include confusion and speaking difficulties.
This stroke-like aspect of hemiplegic migraine can be dangerous. Because these symptoms are similar to those for stroke, seizures and other potentially serious neurological conditions, there’s a risk that what you think is a hemiplegic migraine attack is actually something more serious. Proper diagnosis of hemiplegic migraine is therefore critical for the right migraine management, care and treatment, and to rule out other causes.
Hemiplegic migraine is a rare form of migraine affecting 0.01% of the 1 billion people worldwide who have migraine. It affects three times as many women as men, and the average age of onset is 12 to 17 years old (2).
Types and causes of Hemiplegic Migraine
Hemiplegic migraine is categorised into two types according to its cause:
- Familial hemiplegic migraine (FHM), which runs in families and is genetically inherited, and
- Sporadic hemiplegic migraine (SHM), which is diagnosed when a person has the symptoms of hemiplegic migraine but does not have any known family history of it.
Familial hemiplegic migraine (FHM)
Offspring of a parent who has FHM has a 50% chance of inheriting the condition by inheriting a gene mutation that causes it. So far, three gene mutations have been conclusively identified as being found in FHM, and one further gene is suspected to play a part. Specifically, variations in:
- the CACNA1A gene cause FHM type 1
- the ATP1A2 gene cause FHM type 2, and
- the SCN1A gene cause FHM type 3.
In addition, some research suggests that PRRT2 gene may cause FHM but this has not been proven conclusively and is controversial (3).
Not all families with FHM have one of these genes, so it’s thought that there are yet-to-be identified genes that also cause FHM. When a person is genetically tested for FHM but no mutation is demonstrated for the CACNA1A, ATP1A2 or SCN1A gene, the person will be diagnosed with “FHM other loci”.
Sporadic hemiplegic migraine (SHM)
People who are the first in their family to have hemiplegic migraine are described as having sporadic hemiplegic migraine. Researchers think that SHM is caused in two ways, either by:
- a new mutation in one of the three genes associated with FHM in the sperm or egg for that child only, meaning the condition is not inherited – such gene mutations are called ‘sporadic’ or ‘de novo’, or
- inheriting the condition from a parent who was asymptomatic, meaning the parent never experienced a hemiplegic migraine attack.
What happens during a hemiplegic migraine attack?
The genes that we know cause FHM provide instructions for making proteins that help nerve cells communicate. The mutations in these genes cause calcium-related channels in nerve cells to work incorrectly from time to time, which in turn affects the transference of signals between nerve cells in the brain, disrupting how neurotransmitters or ‘chemical messengers’ (one of which is serotonin) would normally behave. This interruption to the normal functioning of communication between certain nerve cells is what leads to the symptoms of a hemiplegic migraine attack, including severe headaches and visual disturbances.
Figure 1: Gene mutations from time to time temporarily disrupt neurotransmission in the brain leading to hemiplegic migraine attack symptoms.
Triggers for hemiplegic migraine attacks
Like other migraine types, there are various triggers for hemiplegic migraine attacks. Some people can always identify the trigger, some can sometimes identify triggers, and others never identify trigger factors. People who are currently having attacks identify their triggers at a much higher rate than people who have had attacks in the past but don’t anymore (4).
Triggers for hemiplegic migraine are the same as those that trigger common migraine, although some triggers are more prevalent among people with hemiplegic migraine, especially:
- stress, both during and after experiencing stress
- sunlight and bright lights
- intense emotional influences
- too much or not enough sleep (4), and
- in children, viral illness (5).
Conversely, people with hemiplegic migraine say that odours and vigorous exercise are less likely to be triggers compared to people with typical migraine with aura (4).
Other triggers seem to affect people with hemiplegic migraine and common migraine in similar proportions. Common triggers include:
- menstruation or a break in taking the pill
- alcohol or caffeine intake
- food and seasoning, especially processed foods, salty foods, aged cheeses and MSG
- skipping meals
- weather changes, and
- minor head traumas.
A type of x-ray for examining blood vessels in the brain, known as a cerebral angiography, can also trigger hemiplegic migraine attacks (6).
You can read more about migraine triggers and trigger management here >
Like typical migraine with aura, hemiplegic migraine attacks comprise an aura phase and a headache phase. However unlike most migraine types, hemiplegic migraine does not have a predictable pattern. Attacks, and each phase of an attack, can vary in severity and duration. Usually a headache phase follows the aura phase, but it might not. Headache can precede aura or not develop at all. One attack might be characterised by mild pain and severe weakness, and in the next, it could be the reverse.
In hemiplegic migraine, the aura phase often lasts longer than it does for typical migraine with aura. It usually lasts an hour, but it can take several days or up to a week to fully resolve, often outlasting the headache phase itself.
By definition, hemiplegic migraine attacks always involve weakness on one side of the body, that is, ‘hemiplegia’ in the aura phase, or during the headache phase. Weakness can be mild to severe and may affect all or just part of one side of the body (eg, hands, hand and arms or the face) (3). Sometimes it can manifest as paralysis down one side of the body.
Hemiplegic migraine attacks also involve at least one other visual, sensory and speech or language aura symptom, such as:
- Visual – bright lights causing blind spots (scintillating scotoma), double vision, flashing lights (photopsia), bright, shimmering, jagged lines (fortification spectra), foggy vision, and loss of one half of the visual field
- Sensory – prickly sensations, tingling or pins-and-needles on the face, arms or legs (paraesthesia), imbalance, and numbness
- Speech or language – slurring or mixing words, trouble remembering words, being unable to understand or express speech (aphasia) and having problems writing, reading, and listening.
Other aura symptoms may include brainstem symptoms such as sensitivity to sound, ear-ringing (tinnitus), room spinning (vertigo), impaired coordination, decreased level of alertness.
Aura symptoms can vary from one attack to the next, for example some people with hemiplegic migraine may experience a typical migraine aura during a migraine attack but no hemiplegic aura.
In general, auras come on gradually over half an hour, last for one or more hours, and usually go away within 24 hours, though they can last for days. The slow build of aura symptoms can be contrasted with stroke symptoms, which are sudden.
In general, people with SHM experience more aura symptoms than what is typical for common migraine as part of their hemiplegic migraine attacks, especially visual disturbances.
Headache might start shortly before, during or after the aura phase of a hemiplegic migraine attack. Like other types of migraine, the headache phase is characterised by intense pain that is worse than regular headaches and can be throbbing and sometimes debilitating. It can be on one or both sides of the head. It can cause nausea and vomiting and be accompanied by sensitivity to light (photophobia) and sound (phonophobia). Other symptoms can include dizziness, vertigo and confusion.
Severe and rarer symptoms
In severe cases, a person with hemiplegic migraine may experience prolonged weakness, seizures, confusion, memory loss (which can last for months) and behaviour change. This can continue for days or, in rare cases, weeks but usually goes away.
In rare cases, the severity of a hemiplegic migraine attack can cause changes in consciousness, from confusion to profound coma.
Some people with hemiplegic migraine may have symptoms that appear to affect the part of the brain, known as the cerebellum, which controls coordination and balance and plays a part in cognition and behaviour. Signs that the cerebellum is affected include uncontrolled, repetitive movements of the eyes (nystagmus), slurred speech (dysarthria), and a lack of coordination of voluntary movements (ataxia) (3).
Most symptoms go away but in rare cases, some people with hemiplegic migraine have long-lasting or permanent trouble with movement and coordination or develop intellectual disability. Some people may also develop epileptic seizures between migraine attacks.
Hemiplegic migraine is diagnosed when a person has had at least two migraine attacks with aura and the auras have certain characteristics. For diagnosis, the auras must include fully reversible (1):
- motor weakness, and
- visual, sensory and/or speech/language symptoms.
Aura symptoms must also have at least three of the following characteristics (1):
- at least one spreads gradually over 5 minutes
- two or more occur in succession
- each lasts for 5 to 60 minutes
- at least one is unilateral, ie on one side of the body (usually hemiplegia)
- at least one is ‘positive’ (eg for visual, a ‘positive’ symptom would be seeing things that aren’t there such as flashes or distortions as opposed to ‘negative’ visual symptoms that detract from the field of vision such as blurring or dark spots), and
- aura is accompanied by headache, or headache follows within 60 minutes (3).
In addition, FHM is diagnosed when one of your parents, siblings, children (first degree relatives) or grandparents, grandchildren, uncles/aunts, nieces/nephews or half-siblings (second degree relatives) also has hemiplegic migraine. The diagnosis can be confirmed with gene testing in cases where one of the gene mutations known to be associated with hemiplegic migraine is present.
Treatment for hemiplegic migraine has commonalities with treatments for other types of migraine. The treatment you receive will depend on your medical history and symptoms.
As for other forms of migraine, your doctor may prescribe preventives to prevent migraine attacks before they occur, or acute medications to stop or mitigate the symptoms of a migraine attack as it’s occurring.
Some medications used for migraine are generally not used for hemiplegic migraine. There are concerns that triptans (an acute medication) and beta blockers (a preventive), which constrict the blood vessels, increase the risk of stroke, which could be masked in people with hemiplegic migraine. However the risk is considered small. If triptans are prescribed, they are generally not taken during the aura phase when the risk is considered greatest.
You can read more about treatment options for migraine here >
Medications to reduce the frequency of migraine attacks are usually used for hemiplegic migraine, especially because the symptoms of hemiplegic migraine attacks can be so severe. These preventives include (7):
- Beta blockers
- Onabotulinumtoxin-A (Botox)
- Anti-seizure medications,
- Calcium channel blockers, and
- CGRP inhibitors.
Acute medications are taken at the onset of a migraine attack to reduce the symptoms. These include:
- non-steroidal, anti-inflammatory medication (NSAID) such as Aspirin, paracetamol, naproxen and Celebrex
- anti-nausea drugs (antiemetics), such as metoclopramide (Maxolon), which can help with nausea and increase the efficacy of other medications by helping with absorption, and
- anti-seizure medication to treat seizures which are seen in FHM type 2.
Other acute treatments include use-at-home nerve stimulation devices (such as Cefaly), and procedures which require hospitalisation or an infusion clinic such as:
- nerve blocks, and
- greater occipital nerve block (which has been found to be effective for up to three months).
Severe hemiplegic migraine attacks may require hospitalisation, especially for changes in consciousness, high fever, or seizures.
You should seek medical attention immediately if you experience hemiplegic migraine aura symptoms for the first time, such as:
- slurred speech
- weakness (especially sudden weakness)
- loss of consciousness, or
Such symptoms are similar to a stroke which requires immediate medical attention. For that reason, even if you’ve been diagnosed with hemiplegic migraine, you should always seek medical attention for these types of symptoms if you are unsure whether it is a migraine attack.
When investigating your symptoms, doctors often order head scans to rule out other causes. In addition to stroke, it can be hard to differentiate hemiplegic migraine from conditions such as multiple sclerosis and epilepsy. Your doctor will also ask about your family’s medical history if FHM is likely.
Hemiplegic migraine is a chronic disorder and can be extremely painful and debilitating. However people with hemiplegic migraine often have long attack-free periods over their lifetime, and attacks generally (though not always) become less frequent as you age. Some people only ever have a few attacks in a lifetime, while others may have to manage attacks throughout their life. The severity of attacks also varies from person to person, and attack to attack.
You may not be able to avoid familial hemiplegic migraine attacks if FHM runs in your family, but managing triggers and working with clinicians to minimise attacks and treat acute symptoms can lessen the impact of the condition on the lives of people with hemiplegic migraine.
Further information & resources
If you would like to learn more about migraine or other headache types, you can check out the following articles & resources:
- International Headache Society, 2018, 1.2.3 Hemiplegic migraine. Retrieved from: https://ichd-3.org/1-migraine/1-2-migraine-with-aura/1-2-3-hemiplegic-migraine/
- A Kumar et al, 2022, Hemiplegic Migraine [eBook]. StatPearls. Bookshelf ID: NBK513302
- NORD – National Organization for Rare Disorders, 2019, Hemiplegic Migraine. Retrieved from: https://rarediseases.org/rare-diseases/hemiplegic-migraine/
- JM Hansen et al, 2011, Trigger factors for familial hemiplegic migraine. DOI: 10.1177/0333102411415878
- I Toldo et al, 2019, First attack and clinical presentation of hemiplegic migraine in pediatric age: a multicenter retrospective study and literature review. DOI: 10.3389/fneur.2019.01079
- N Pelzer et al, 2013, Familial and sporadic hemiplegic migraine: diagnosis and treatment. DOI: 10.1007/s11940-012-0208-3
- Di Stefano V et al, 2020, Diagnosis and therapeutic aspects of hemiplegic migraine. DOI: 10.1136/jnnp-2020-322850
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