Types of Stroke
A stroke occurs when blood flow to the brain is interrupted. This can happen when:
- A blood clot blocks an artery (a blood vessel that carries blood from the heart to the body).
- A blood vessel (a tube through which the blood moves through the body) breaks.
When either of these events occurs, brain cells begin to die.
When brain cells die during a stroke, abilities controlled by that area of the brain are lost. These abilities include speech, movement and memory. How a stroke patient is affected depends on where the stroke occurs in the brain and how much the brain is damaged.
There are several types of strokes, each with different causes and effects.
Ischemic stroke is a type of stroke that accounts for about 83 percent of all cases, according to the American Stroke Association. Ischemic strokes occur as a result of an obstruction within a blood vessel supplying blood to the brain.
This blockage may stem from several sources, including clots from the heart or legs, plaque from the valves of the heart or other blood vessels. If a clot or plaque breaks free and travels to the brain, stroke occurs. An ischemic stroke can occur in two ways: embolic and thrombotic strokes.
Embolic strokes are caused by a blood clot or plaque debris that develops in another part of the bloodstream and travels to a blood vessel in the brain. Thrombotic strokes are caused by a clot that develops in blood vessels in the brain.
Transient Ischemic Attack (TIA)
A TIA is sometimes called a '”mini-stroke.” It is usually due to a blockage caused by platelets clumping together. After a short period of time, these clumps break up, allowing the blood flow to resume and the symptoms resolve. Having experienced a TIA increases the chance that a patient will experience a full-blown stroke. It is important to determine the cause of the symptoms and thereby reduce the risk of stroke.
Hemorrhagic stroke accounts for about 17 percent of stroke cases, according to the American Stroke Association. In hemorrhagic strokes, a blood vessel in the brain leaks or ruptures. Hemorrhagic stroke can be caused by a number of disorders which affect the blood vessels, including arteriosclerosis and long-standing high blood pressure. Two types of weakened blood vessels usually cause hemorrhagic stroke: aneurysms and arteriovenous malformations (AVMs).