A migraine is a neurological disorder characterized by recurrent, often severe, headaches, typically accompanied by sensitivity to light and sound. A stroke, in contrast, is a medical emergency that occurs when blood flow to a part of the brain is interrupted, causing brain cells to die. Strokes are broadly categorized as ischemic, where a vessel is blocked by a clot, or hemorrhagic, where a vessel ruptures and bleeds into the brain. Medical research has documented a specific, though rare, association between migraines and an increased vulnerability to ischemic stroke. Understanding this link is important for individuals who experience frequent migraine attacks.
Defining the Specific Connection
The question of whether a migraine can directly cause a stroke is complex, and current medical consensus points toward a strong association rather than direct causation for most sufferers. The specific event linking the two is known as migrainous infarction, which is a rare type of ischemic stroke that occurs during a migraine attack accompanied by aura. For a diagnosis of migrainous infarction to be confirmed, the stroke symptoms must occur during the aura phase, and all other possible causes of stroke must be ruled out through diagnostic testing.
Migrainous infarction is considered a diagnosis of exclusion, meaning doctors must confirm that the symptoms are not merely a stroke or a transient ischemic attack that coincidentally occurred in a person who happens to have migraines. This particular type of stroke accounts for less than one percent of all ischemic stroke cases. The mechanism is theorized to involve temporary changes in blood flow within the brain.
One proposed mechanism involves transient cerebral vasoconstriction, which is a temporary narrowing of blood vessels in the brain that occurs during the aura phase. This vasoconstriction can significantly reduce the regional cerebral blood flow, potentially leading to tissue ischemia. Some research also suggests that heightened platelet activation during a migraine may increase the tendency for clot formation, further contributing to the risk of an ischemic event.
The Critical Role of Migraine with Aura
The most significant differentiator of stroke risk among migraine sufferers is the presence of aura, the transient neurological symptoms that precede or accompany the headache phase. Migraine with aura (MA) is the primary type associated with an elevated risk of ischemic stroke. The risk for those with migraine without aura is generally considered negligible or only minimally above the baseline population risk. A meta-analysis suggests that individuals who experience MA have approximately a twofold increased lifetime risk of ischemic stroke compared to those who do not have migraines.
Aura symptoms typically involve visual disturbances, such as seeing zigzag lines, shimmering spots, or temporary blind spots. They can also include sensory changes like numbness or tingling in the face or limbs. These symptoms are thought to be caused by a slow wave of electrical and blood flow changes across the brain’s surface, known as cortical spreading depression. It is this unique physiological event that is most strongly implicated in the higher stroke risk.
The increased association with stroke is particularly pronounced for younger women who experience MA. The majority of stroke events linked to MA are ischemic, meaning they are caused by a blockage rather than a bleed. For most people with MA, the absolute risk remains very low.
Key Risk Factors That Increase Vulnerability
While migraine with aura introduces a baseline increase in stroke risk, several compounding factors can significantly amplify this vulnerability. These factors relate to lifestyle choices and underlying health conditions, which interact with the migraine-related vascular changes. Smoking, for example, is a major risk factor for stroke in the general population, and its combination with MA creates a much higher risk profile.
The use of combined oral contraceptives, particularly those containing higher doses of estrogen, is another factor that interacts negatively with MA. Estrogen-containing contraceptives increase the tendency for blood clotting. When combined with the vascular instability characteristic of migraine aura, the potential for an ischemic event rises. Healthcare providers often advise women with MA to avoid these specific types of birth control to mitigate this heightened risk.
Underlying cardiovascular conditions also worsen the risk for migraine sufferers. Uncontrolled hypertension, high cholesterol, and diabetes further contribute to the risk by promoting vessel narrowing and plaque buildup. Managing these traditional vascular risk factors is a primary strategy for reducing the stroke risk in individuals who experience MA.
Differentiating Migraine Symptoms from Stroke
Because the symptoms of a severe migraine, especially one with aura, can mimic the symptoms of a stroke, it is important to know the signs that require immediate medical attention. The symptoms of a migraine aura, such as one-sided weakness or speech difficulty, tend to develop gradually and spread over several minutes, and they usually resolve within 60 minutes. In contrast, stroke symptoms typically have a sudden onset, reaching their maximum severity almost immediately.
A sudden, explosive onset of the “worst headache of your life,” known as a “thunderclap” headache, is a serious red flag that warrants an immediate emergency medical evaluation, as it is often a symptom of a subarachnoid hemorrhage. Additionally, any migraine-like symptom that lasts significantly longer than the typical aura duration, or a new type of severe symptom that is different from previous migraine attacks, should be treated as a potential stroke.
The most important tool for recognizing a stroke is the FAST acronym.
- Face drooping
- Arm weakness
- Speech difficulty
- Time to call emergency services
If any of these signs appear, immediate action is necessary because clot-busting treatments for ischemic stroke are time-sensitive. Recognizing the sudden, uncharacteristic nature of stroke symptoms is paramount for receiving timely care.