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What Is Stroke?

A stroke, or a brain attack, occurs when a blood vessel carrying blood and oxygen to the brain gets blocked or ruptures, preventing the brain from getting enough oxygen. Strokes can happen at any age, but nearly one-third of all strokes happen to people under age 65. Stroke is the third leading cause of death in the United States and the number one cause of disability in adults.

There are two types of stroke (brain attack):

Ischemic Stroke

An ischemic stroke is caused by blocked arteries, cutting off blood flow to the brain. This can occur as either an embolic or thrombotic stroke:

Thrombotic: Blood flow is impaired by a blockage to one or more of the arteries supplying blood to the brain. The blockage can be caused by fatty deposits (plaque) and cholesterol. The body responds to these deposits by forming clots.
Embolic: A blood clot forms somewhere in the body (usually the heart) and travels through the bloodstream to the brain. Once in the artery the clot travels until it blocks a blood vessel that is too small to let it pass.

Hemorrhagic Stroke

Not all strokes are caused by blockages in the arteries. Nearly 20 percent occur when a blood vessel ruptures in or near the brain. This is a hemorrhagic stroke. There are two kinds of hemorrhagic stroke:

Subarachnoid hemorrhage: Occurs when a blood vessel on the surface of the brain ruptures and bleeds into the space between the brain and the skull. A ruptured aneurysm or ateriovenous malformation (AVM) can be the cause. An AVM is a collection of arteries and veins abnormally formed at birth. A ruptured aneurysm is a blood-filled pouch that balloons out from an artery wall.
Intracerebral hemorrhage: A blood vessel bleeds into the tissue deep within the brain. High blood pressure or aging blood vessels are the main causes of this type of stroke.

What is a TIA?

Transient ischemic attack (TIA) occurs when a blood clot blocks an artery for a short time. The symptoms of TIA are the same as the stroke warning signs but last only for a few minutes or hours. About 10 percent of all ischemic strokes are preceded by TIAs. TIAs are strong predictors of ischemic stroke risk. If you are diagnosed with a TIA, it should put you on "high alert" to reduce your risk factors. People who experience TIA have a very high chance of having a stroke and should seek medical treatment for any warning signs without delay.