Hemiplegic migraine (HM) is a rare subtype of migraine with aura, associated with one-sided motor weakness during the aura phase. The motor weakness is often present with other aura symptoms such as impairment of vision, sensation, or speech. There are two categories of hemiplegic migraines; familial hemiplegic migraine (FHM) where there is a family history in first and second degree relatives, and sporadic hemiplegic (SHM) migraine where there is no family history.

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While migraine affects about 15-20% of the population, the overall prevalence of hemiplegic migraine is much more rare. It occurs in about .01%, reported in a population study from Denmark. It usually starts in the first and second decade of life. Hemiplegic migraine is also is more prevalent in females than males.

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Causes of Hemiplegic Migraine

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The aura of HM is most likely to be caused by cortical spreading depression across the brain.

Genetic studies have shown the involvement of a few genes - CACNA1A, ATP1A2, PRRT2, and SCN1A. Other genetic mechanisms may play a role although further studies are necessary. The pathophysiology of HM is similar to migraine with aura although we do see a lower migraine threshold and increase in severity of migraine episodes.

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Symptoms of Hemiplegic Migraine

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HM is characterized by recurrent migraine episodes associated with motor weakness. Motor aura is the hallmark of HM. However, typically there are two or more auras present during a HM attack. Each aura can evolve over 20 to 30 minutes and may also take hours to improve. Often an episode can begin with visual aura then followed by sensory, motor, speech changes, and brainstem symptoms. The aura symptoms associated with brainstem aura include vertigo, speech changes, balance and coordination impairments, bilateral visual symptoms, sensory or motor symptoms, sensitivity to sounds, tinnitus, and diminished alertness. Motor symptoms often start in the hand and gradually spread into the arm and then the face. Although episodes are one-sided this can switch sides between or during attacks. Most patients will have headaches with each attack. Additionally, motor and aura symptoms are fully reversible. We do see that the frequency and severity of episodes improve with age typically after age 50, and can evolve into more typical migraine episodes without hemiparesis. Most common triggers reported include acute stress, bright lights, changes in sleep patterns, exertion, and mild head trauma although episodes can also occur without being exposed to triggers.

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Symptoms associated with HM are similar to stroke and epilepsy, so it is absolutely crucial that other neurological conditions are ruled out. It is important to be seen by a healthcare provider (in person or via video visit) for a complete neurological exam in addition to the review of family and medical history. Imaging may also be necessary to look at the brain and the blood vessels.

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To receive this diagnosis, the patient should have at least two episodes meeting criteria for migraine with aura. A person must also have experienced temporary symptoms involving motor weakness, visual, sensory, or speech changes. In addition, the aura symptoms are fully reversible.

Treatments for Hemiplegic Migraine

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Treatment is always considered based on severity and frequency of episodes. Symptom management is essential for those experiencing HM. Since HM is a subtype of migraine with aura, similar preventive treatment is considered. This includes blood pressure agents, anti-seizure medications, and antidepressants. For acute treatment, NSAIDS may often be prescribed and anti-nausea medications. We generally avoid triptans and ergotamine derivatives because they constrict blood vessels and may increase the risk of stroke in this population.

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If you think you may be experiencing hemiplegic migraine, it's important to speak with a doctor. Neura's headache specialists treat many hemiplegic migraine cases, and would be glad to meet with you via video consultation. Click here to start your trial and book a visit.

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