Hemiplegic Migraine: When Migraine Mimics a Stroke

Understanding Hemiplegic Migraine

Hemiplegic migraine represents a rare and distinct form of migraine that includes neurological symptoms not typically seen in other types of migraines. One hallmark feature of this condition is motor aura, which refers to temporary muscle weakness or paralysis on one side of the body. While the severity and duration of this weakness can vary significantly between individuals, its presence is a defining characteristic that often leads to diagnostic challenges. Hemiplegic migraine is technically an outdated term with the more accurate and current term being migraine with motor aura. In this blog, these terms will be used interchangeably.

This type of migraine is further categorized into two subtypes: familial hemiplegic migraine and sporadic hemiplegic migraine. Familial hemiplegic migraine (FHM) occurs in individuals with a family history of the condition, suggesting a genetic predisposition. FHM makes up the majority of cases (50-60%). In contrast, sporadic hemiplegic migraine arises in individuals without any known family history, emphasizing the condition’s variability and complexity. 

What makes hemiplegic migraine particularly alarming is its ability to mimic other serious neurological conditions, particularly stroke. The neurological symptoms that accompany an attack can include visual disturbances, sensory changes, and speech difficulties. These symptoms are typically temporary but can nonetheless create significant anxiety and diagnostic confusion for both patients and healthcare providers. 

Though rare, this condition has profound implications for the lives of those affected. It requires careful and precise diagnostic evaluation to ensure that other, potentially life-threatening conditions such as stroke are not missed. Recognizing the key features of hemiplegic migraine is critical for providing appropriate care and minimizing unnecessary worry for patients.

Hemiplegic Migraine Symptoms and Signs

The symptoms of hemiplegic migraine center around the hallmark feature of one-sided muscle weakness or paralysis, which distinguishes this condition from other types of migraines. This weakness, which may affect the arm, leg, and/or facial muscles on one side of the body only, can last anywhere between 5 minutes up to 3 days. Most of the time it lasts less than an hour though. The weakness can only be on one side, it cannot be on both sides simultaneously. Accompanying this weakness are usually additional aura symptoms, such as visual disruptions, including flashes of light, blind spots, or zigzag patterns. 

The motor aura of hemiplegic migraine is distinct from all other types of migraine aura not only in its character, but in the fact that it can last up to 3 days, per diagnostic criteria. All other types of migraine aura can only last up to 60 minutes per criteria.

Beyond visual disturbances, sensory changes are another common feature, with patients frequently describing numbness or tingling in the affected areas (but it can also be weakness only). These sensations can spread or shift across different parts of the body as the attack progresses. Speech difficulties are also a concerning aspect of hemiplegic migraines. Some individuals may find it hard to articulate words or may experience a temporary inability to speak altogether. Cognitive challenges, such as confusion or difficulty concentrating, can further compound the distress experienced during an episode.

While many of these symptoms are temporary, they often appear in a sequence, beginning with aura features (usually visual) and progressing to motor symptoms. This gradual development of aura sequencing can help distinguish hemiplegic migraine from other neurological conditions, but it can still cause alarm due to its resemblance to stroke symptoms.

Hemiplegic Migraine vs. Stroke

The similarities between hemiplegic migraine, stroke and TIA (transient ischemic attack) can make it difficult to distinguish between them, especially during the initial onset of symptoms. All conditions can result in sudden neurological changes, such as weakness or paralysis on one side of the body, slurred speech, or visual symptoms. These overlapping features often lead to significant concern, as stroke is a medical emergency that requires immediate attention. However, there are important differences in how the symptoms develop and resolve. So how can you tell the difference between hemiplegic migraine and stroke or TIA?

In the case of a hemiplegic migraine, the progression of symptoms typically follows a pattern that unfolds more gradually. By diagnostic criteria, hemiplegic migraine must be associated with at least one of visual, sensory, or speech/language aura symptoms which usually appear first, followed by the one sided motor weakness symptoms. A headache (usually migraine) is most often associated with or follows the aura symptoms. In contrast, aura and/or migraine are not typically a sign of a stroke (unless it’s a bleeding stroke). 

However, technically the diagnosis of hemiplegic migraine can still be made if there is no headache, but there must be at least one other aura symptom. By criteria, if there is no other associated aura symptom (visual, sensory, speech), it doesn’t meet criteria for hemiplegic migraine even if there is a headache. With that said, if all other evaluations rule out concerns such as stroke, TIA, seizures, and other mimics, we still often treat empirically as hemiplegic migraine even if it doesn’t match these strict diagnostic criteria exactly. The key is excluding everything else first though, especially if the set of symptoms do not meet the International Headache Society classification system exactly.

Another key point to consider is the duration of symptoms. While hemiplegic migraine-related weakness can last 5 minutes up to 3 days, it is usually short-lived lasting less than an hour most of the time. The resolution of these symptoms is a hallmark of the condition. On the other hand, stroke symptoms tend to persist indefinitely unless swift medical intervention, such as clot removal or medication, is provided early in symptom onset. This distinction is critical in understanding the nature of the underlying issue and directing appropriate care.

Transient ischemic attacks (TIA) have symptoms that also overlap with hemiplegic migraine. A TIA is sometimes called a “mini-stroke”. It represents a temporary blockage of an artery causing stroke symptoms which spontaneously resolve when the clot breaks up. Like hemiplegic migraine, these are also temporary and fully reversible symptoms, usually within 24 hours. TIAs are often warning signs for a larger true stroke in the future, so warrant full stroke evaluations to prevent a permanent stroke. A true TIA will not show an area of acute stroke on MRI. If there is, then it is classified as a stroke. 

Although much less common, I occasionally see patients in clinic referred for “hemiplegic migraine” with one sided weakness which has been going on continuously for months or many weeks with or without headache. Their MRIs have shown no evidence for stroke. Some have even gone through physical therapy. This is NOT hemiplegic migraine. Hemiplegic migraine will not cause continuous indefinite one sided weakness. The International Classification of Headache Disorders allows for a duration of hemiplegic motor weakness lasting 5 minutes up to 3 days, but for most it resolves well before 3 days. The definition also requires that the weakness is fully reversible. If it isn’t, then it’s not hemiplegic migraine. There are a few rare cases reported where it was felt to last a couple weeks, but not beyond that. For prolonged motor aura symptoms lasting weeks to months, other investigations are needed including evaluations for functional neurologic disorders (FND), spinal cord lesions, neuropathy, radiculopathy, and seizures to name a few.

Despite these differences, it is crucial to err on the side of caution when these symptoms arise, especially for initial attacks, until a consistent recognizable pattern of symptom sequences has been established for a patient. Because the overlap between hemiplegic migraine, stroke, and TIA is significant, any sudden onset of neurological symptoms warrants immediate medical evaluation. Emergency services will often conduct imaging studies and other diagnostic tests to differentiate between these two conditions, ensuring that patients receive the right treatment in a timely manner.

Pathophysiology: What Happens in the Brain During a Hemiplegic Migraine

The underlying mechanisms of hemiplegic migraine are highly intricate, involving disruptions in normal brain activity. One critical process implicated in this condition is cortical spreading depression (CSD), a wave of intense neuronal excitation followed by a period of suppressed brain activity. This wave spreads across the cerebral cortex and is thought to trigger the visual, sensory, speech and motor aura symptoms commonly experienced during hemiplegic migraine attacks. Depending on where the electrical wave is spreading dictates the type of aura experienced.

A key contributor to this condition is genetic mutations, which interfere with the proper functioning of brain cells. In general, about 50–60% of hemiplegic migraine cases are familial with identifiable genetic mutations, and 40–50% are sporadic without a family history or an identifiable genetic mutation.

The most common subtype of familial hemiplegic migraine (FHM) is FHM type 1 (FHM1) from a mutation in the CACNA1A gene on chromosome 19, responsible for controlling calcium channels in nerve cells. This mutation leads to an increased influx of calcium into cells, disrupting the release of neurotransmitters like glutamate, which plays a role in signaling between neurons. This mutation linked to FHM1 accounts for 50–75% of familial hemiplegic migraine cases.

FHM type 2 (FHM2) accounts for about 20% of familial hemiplegic cases. It is caused by mutations in the ATP1A2 gene on chromosome 1. This mutation affects the ability of brain cells to regulate potassium and clear excess glutamate, further disrupting normal brain function which contributes to an environment where cortical spreading depression is more likely to occur.

FHM type 3 (FHM3) is less common, and is due to a mutation in the SCN1A gene on chromosome 2. This alters the function of sodium channels in the brain, leading to increased neuronal excitability.

Hemiplegic Migraine Testing

Diagnosing hemiplegic migraine requires careful consideration to differentiate it from other conditions with similar presentations, such as stroke, TIA, seizures, or other neurological disorders. Neurologists often begin with a detailed discussion about the patient’s medical history, focusing on the onset, duration, and nature of symptoms, as well as any family history of similar issues. A physical and neurological examination is performed to assess motor function, sensory responses, and other neurological signs that could provide clues about the underlying condition.

Imaging techniques with MRI or CT scans, including brain arteries with MRA or CTA, are crucial diagnostic tools in the evaluation process. These tests help exclude structural abnormalities, blocked arteries, or other brain lesions that could account for the symptoms.

Electroencephalography (EEG) may be used in some cases to rule out seizure disorders, especially if the patient had shaking of the extremity prior to the weakness (Todd’s paralysis following a seizure), or experienced confusion or altered consciousness, bit their tongue, or had incontinence during an episode.

In atypical cases with prolonged symptoms, MRI of the spine may also be considered to exclude a spinal lesion. EMG and nerve studies may also be done if there is suspicion for pinched nerves from the spine.

In cases where hemiplegic migraine is suspected, genetic testing can play a pivotal role, especially in patients with a family history of the condition. Testing can identify mutations in genes like CACNA1A, ATP1A2, or SCN1A, which are known to be associated with familial hemiplegic migraine. However, it is important to note that approximately 75% of hemiplegic migraine patients do not show mutations in the three known genes, indicating that other genetic factors might be involved. This highlights the need for a comprehensive approach that combines genetic insights with clinical evaluation.

It is essential for healthcare providers to closely observe the pattern and evolution of symptoms over time. The sequence in which aura symptoms appear, such as sensory changes or visual disturbances followed by motor weakness, can provide important diagnostic clues. However, because the symptoms of hemiplegic migraine overlap significantly with those of stroke, clinicians often prioritize immediate testing to rule out life-threatening conditions before arriving at a definitive diagnosis, especially for the first time.

Treatment Options for Hemiplegic Migraine

Treatment for hemiplegic migraine requires collaboration between patients and their healthcare providers to find the most effective strategy. Managing it involves both acute treatments for managing attacks and preventive measures to reduce their frequency and severity.

For acute management, the focus is on alleviating the immediate symptoms of a hemiplegic migraine attack. Common migraine medications like triptans and ergotamines such as DHE are generally avoided due to their potential to constrict blood vessels, raising concerns about safety in individuals with stroke-like symptoms. There is a theoretical concern for further decreased blood flow to areas of the brain which are already in a lower oxygen demanding underactive metabolic state following aura symptoms. This has become a debatable topic on whether triptans are safe to use or not though, as I’ll explain below.

I’d like to give a bit of perspective here on triptans, DHE, and hemiplegic migraine because this is a very common question. Historically, triptans and DHE have been considered medically contraindicated in hemiplegic migraine. However, this contraindication is a gray area and is debated among some headache specialists. The reasoning was rooted in the older, now defunct, vascular theory of migraine. The older vascular theory of migraine assumed there was vasoconstriction and blood vessel narrowing which caused the aura symptoms. This has since been disproven. The prior concern was that adding a triptan and causing further vasoconstriction might lead to ischemia (lack of blood flow) and stroke. This is why patients with hemiplegic migraine had been excluded from the triptan studies.

We now know that migraine is more of an electrical event (not considered a “vascular headache” anymore) with some vascular effects (blood vessel dilation, not constriction). So migraine is considered a neurovascular event, but primarily neurological.

The main residual theoretical concern for why triptans are often still avoided relates to the fact that following an aura, the tissue becomes metabolically hypoactive (underactive), thus there is less blood flow and oxygen delivery to that region already. The concern is that if you cause further vasoconstriction and less blood flow with triptans or DHE to this hypometabolic and hypoperfused area, does it hit a threshold of ischemia for some patients which might lead to stroke. With that said, there’s been no great evidence confirming this concern, but this is why it is still a bit of a gray area despite the classic vascular theory of migraine now being defunct.

Nonsteroidal anti-inflammatory drugs (NSAIDs), such as ibuprofen or naproxen, are frequently employed to reduce pain and inflammation. Antiemetics may be prescribed to control nausea and vomiting, which can occur during an attack. Gepants such as Nurtec, Ubrelvy and Zavzpret are felt to be safe in hemiplegic migraine. Neuromodulation devices can also be considered.

For severe episodes, some patients benefit from intravenous medication (migraine cocktail) administered in a hospital setting, particularly if hydration or rapid symptom relief is needed.

Preventive treatment is a cornerstone of care for individuals who experience recurrent or debilitating hemiplegic migraine attacks. A variety of medications may be considered, depending on the patient’s specific needs and medical history. Calcium channel blockers are often recommended, as they have shown promise in reducing attack frequency in some patients. Anticonvulsants like topiramate or valproate may also be prescribed for their ability to stabilize neuronal activity and prevent attacks. Beta-blockers, which are more commonly used for general migraine prevention, can also be considered in certain cases. However, not all preventive medications are suitable for everyone, and side effects must be carefully weighed against potential benefits. The newer options including CGRP monoclonal antibodies and gepants are also good considerations. Botox can also be used for chronic migraine (15-30 days of headache per month with at least 8 being migraine days).

For those with familial hemiplegic migraine, where specific genetic mutations are implicated, additional considerations may come into play. While targeted treatments based on genetic findings are not yet widely available, understanding a patient’s genetic background can guide medication choices and inform risk assessments. Research into gene-specific therapies continues to evolve, offering hope for more personalized treatment approaches in the future.

Beyond medications, lifestyle modifications play an important role in managing hemiplegic migraines. Since certain environmental or lifestyle factors can trigger attacks, identifying and minimizing these triggers is critical. Keeping a headache diary can help patients and their healthcare providers pinpoint patterns and potential triggers, such as specific foods, stress, sleep disturbances, or hormonal changes. 

Adopting consistent sleep habits, managing stress through techniques like mindfulness or yoga, and maintaining a well-balanced diet can contribute to reducing the likelihood of attacks. Avoiding known triggers, such as caffeine or alcohol, may also help some individuals.

For those living with chronic or severe hemiplegic migraines, a multidisciplinary approach may be beneficial. Working with neurologists, pain specialists, physical therapists, or mental health professionals can address the condition’s diverse impacts. Physical therapy can address neck pain or occipital neuralgia, which can be migraine triggers. Psychological support can help patients navigate the emotional toll of living with a chronic and unpredictable condition. Cognitive-behavioral therapy (CBT) has been shown to improve outcomes in some patients by addressing anxiety and stress, which can contribute to symptom severity.

Emergency planning is also an important aspect of managing hemiplegic migraines, particularly because the symptoms can mimic a stroke. Recognizing a consistent pattern and sequence of symptoms can help patients determine if their symptoms are their typical attacks, or something entirely new that requires emergent evaluation. Patients are encouraged to carry medical alert cards or wear identification that outlines their diagnosis to ensure proper care during an attack. This is especially critical for patients who experience severe symptoms, such as prolonged muscle weakness or speech difficulties, which may require emergency evaluation. Discussing an action plan with healthcare providers can help prepare patients and their families for these situations.

Patients are encouraged to maintain open communication with their healthcare providers, regularly reviewing and adjusting their treatment plans as needed.

Conclusions

Hemiplegic migraine is a rare type of migraine and complex condition that requires a nuanced approach to diagnosis and treatment. Its symptoms, particularly the one-sided muscle weakness and aura features, often mimic more serious conditions like stroke or TIA, making immediate medical evaluation critical for accurate differentiation. Understanding the underlying mechanisms, such as cortical spreading depression and genetic mutations, highlights the intricate processes in the brain that contribute to these attacks.

Proper testing, including imaging and occasionally genetic evaluations, is essential for ruling out other neurological disorders and establishing a definitive diagnosis.

Once diagnosed, a combination of acute and preventive treatments, tailored to the patient’s needs, can help manage symptoms and reduce the frequency of attacks. Additionally, lifestyle modifications, trigger avoidance, and stress management play a vital role in long-term care. For patients and their families, having an emergency plan and maintaining open communication with your healthcare provider ensures a more prepared and proactive approach to managing this challenging condition.

While hemiplegic migraine can be distressing, advances in understanding and treatment options continue to provide hope for improved outcomes and quality of life for those affected.