Migraines, particularly those accompanied by aura -- visual disturbances such as flashing lights -- boost the risk of stroke by 21 percent. This comes from long-term studies in Iceland that followed men and women for 26 years. Researchers are looking for an underlying genetic risk factor that could contribute to migraine, heart attack, and stroke.

Scary fact: Migraine sufferers are also more likely to have a heart attack or peripheral artery disease, which causes narrowing blood vessels in the legs.

Best bet: The precise connection between migraines and stroke isn't understood, but both conditions involve blood vessels in the brain. Migraines occur when the blood vessels in the brain constrict, then swell, while ischemic strokes -- the most common kind -- are caused by a blood clot blocking an artery in the brain. With that in mind, some experts recommend taking steps to prevent and treat migraines, either with natural remedies or medication to minimize effects on blood vessels.

http://health.yahoo.net/articles/stroke/photos/10-surprising-clues-stroke-risk#1