Women with a history of migraine headache with aura (transient neurological symptoms, mostly visual impairments) are at increased risk of stroke. However, according to new research reported in Circulation: Journal of the American Heart Association stroke events in women with migraine with aura are more likely to have mild or no disability compared to those without migraine.

In a new analysis of the Women's Health Study involving 27,852 women over 13.5 years, researchers found those who have migraine with aura and who experience an were twice as likely to have no significant disability from stroke.

"The message from this study should be reassuring for migraineurs," said Tobias Kurth, M.D., Sc.D., the study's principal author and associate epidemiologist at Brigham and Women's Hospital in Boston, Mass.

"It is important for women who have migraine with aura to know that their risk of stroke is considerably low and there is high likelihood of a migraine-associated stroke being mild."

The reason for these results is unclear. But Kurth, who is also director of research at INSERM in Paris, France, speculated that mechanisms, perhaps involving smaller vessels – not the traditional mechanisms for stroke, lead to a smaller size stroke.

Compared to those without migraine history, women with migraine and aura were more likely to have a good to excellent functional outcome — defined as having no symptoms and no significant disability, researchers said.

Women participating in the study were divided into four groups: 22,723 who reported no migraine history; 5,129 who reported a migraine history; 3,612 who had active migraine; and of those who reported active migraine, 1,435 reported active migraine with aura.

Researchers evaluated functional ability after stroke at hospital discharge using the modified Rankin Scale, a seven-point scale that measures degree of impairment.

At the onset of the study, women completed a questionnaire about their headaches that allowed classification into the groups of migraine with and without , history of migraine or no history of . Each following year, the women reported new medical conditions, including transient ischemic attack (TIA) or , which were confirmed after medical record review.

During 13.5 years of follow-up, 398 TIAs and 345 ischemic strokes occurred.

Women in the study were primarily Caucasian, average age 55, healthy and working in the healthcare field.

There is currently little reason to believe that the association differs for women with other characteristics or men, Kurth said.