Migraine and Stroke: The Connection Between Migraine and Stroke

It has been known for sometime that people who suffer from migraine headaches have an increased risk of stroke. Why this happens, however, is a matter of intense investigation. People with migraine may suffer a stroke during a typical migraine attack, during or after a "thunderclap headache" (which is much more sudden and severe than a typical migraine), or in between typical migraine attacks.

Am I at risk?

Most migraine sufferers who are affected by stroke are women, younger than 45, who do not have the traditional risk factors for stroke, such as high blood pressure, diabetes or high cholesterol. They are more likely, however, to suffer a stroke if they are smokers and/or take birth control pills.

Some strokes that occur in association with migraine headaches are the result of a syndrome called "reversible cerebral vaso-constriction syndrome" (RCV). By one study, more than 50% of patients who suffer from such a syndrome have a history of migraine headaches. In RCV, blood vessels in the brain undergo vasoconstriction (spasm), which is severe enough to stop blood flow to some areas of the brain. Like other causes of ischemia, such an event can lead to stroke.

Migraine as a Cause of Stroke

Ischemic Stroke
Although strokes can occur during a migraine attack, a cause-effect relationship between them has been difficult to establish. Nonetheless, migraine and stroke occur together often enough that in 1988 the International Headache Society coined the term "migranous infarction" specifically to describe strokes that occur during migraine attacks preceded by an aura.

Hemorrhagic Stroke
Several studies have addressed the question of whether people who suffer from migraine headaches are at risk of suffering hemorrhagic strokes. Based on the available evidence, however, it appears that this is not the case.

Migraine as a Risk Factor for Silent Stroke

Recent studies of people with migraine have brought to light an important observation: people who suffer from the type of migraine headaches that are preceded by an aura are more likely to suffer one or more clinically silent strokes. Such strokes, which are usually small, are most commonly found in the back parts of the brain, especially in an area called the "cerebellum." One recent study showed that people who suffer more than one migraine with aura per month have an almost 16-fold higher chance of suffering silent strokes.

Migraine as a Risk Factor for Stroke

Up until now, the evidence on this subject indicates that people who suffer from migraine headaches, especially those which occur in association with an aura, have an increased risk of suffering ischemic strokes. As stated above, this risk is highest in women who are younger than 45 and who smoke and/or use birth control pills. This increased risk tends to normalize in the elderly, probably because migraine headaches improve or disappear as people age.

What is the Difference Between a Mini-Stroke and a Silent Stroke?

Why would migraines cause strokes?

The connection between migraine and stroke is a matter of intense research. To date, however, there is no explanation for this unexpected association. An important link between these two diseases is a heart condition called "patent foramen ovale," which is present in a significant portion of young people with migraines and strokes. A cause-effect relationship remains speculative to date, though. Other known possible links between migraine and stroke include elevated homocysteine levels and coagulation abnormalities.

_Sources:

Maria Carola Narborne, Santo Gangemi and Maria Abatte; Neurol Sci (2008) 29-S7-S11

Headache Classification Committee of The International Headache Society (1988) Classification and diagnostic criteria for headache disorders, cranial neuralgias and facial pain; Cephalgia 8[Suppl 7]:1-96