Healthy arteries are flexible and have little or no plaque buildup. They allow blood to flow freely and can constrict or dilate in response to changes in blood pressure and your body's varying needs for blood supply. But in atherosclerosis, plaques accumulate and arterial walls swell and become thick and stiff. Arteries clogged by atherosclerosis are susceptible to partial or complete blockage by debris or blood clots. The result may be a transient ischemic attack (TIA) or an ischemic stroke.

Transient Ischemic Attacks (TIAs)
Although strokes strike suddenly and without warning, there is one possible indication that a person might suffer a stroke in the future: a transient ischemic attack (TIA), or "ministroke." TIAs are caused by a brief interruption of blood supply to part of the brain, usually due to a blood clot or small debris that temporarily block an artery. The symptoms of a TIA resemble those of ischemic stroke, except that the symptoms resolve within 1 hour, and often no permanent damage is done. One out of three people who have had one or more TIAs will have a stroke at a later date.

Ischemic Stroke
When one of the large arteries that supply the brain is blocked, some people have few or no symptoms, whereas others have a massive ischemic stroke. This is because some people are born with larger collateral arteries than others. Collateral arteries run between other arteries, providing extra connections. When one artery is blocked, blood can run through a collateral artery instead. But small collateral arteries may not be able to deliver enough blood to the affected area, and a stroke is the result.

More on this topic

What Is Stroke? (VIDEO)
Your Brain Needs Oxygen
Clogged Carotids
Degree of Blockage
Types of Stroke
Risk Factors
Symptoms, Test & Diagnosis
Treating Stroke
Life After Stroke

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