A stroke occurs when blood flow to a part of the brain stops. A stroke is sometimes called a "brain attack."
If blood flow is cut off for longer than a few seconds, the brain cannot get nutrients and oxygen. Brain cells can die, causing lasting damage.
Causes
There are two major types of stroke:
1.Ischemic stroke
2.Hemorrhagic stroke
Ischemic stroke occurs when a blood vessel that supplies blood to the brain is blocked by a blood clot. This may happen in two ways:
A clot may form in an artery that is already very narrow. This is called a thrombotic stroke.
A clot may break off from another place in the blood vessels of the brain, or from some other part of the body, and travel up to the brain. This is called cerebral embolism, or an embolic stroke.
Ischemic strokes may also be caused by a sticky substance called plaque that can clog arteries.
Stroke - secondary to cardiogenic embolism
A hemorrhagic stroke occurs when a blood vessel in part of the brain becomes weak and bursts open. This causes blood to leak into the brain. Some people have defects in the blood vessels of the brain that make this more likely. These defects may include:
Aneurysm (weak area in the wall of a blood vessel that causes the blood vessel to bulge or balloon out)
Arteriovenous malformation (AVM; abnormal connection between the arteries and veins)
Cerebral amyloid angiopathy (CAA; condition in which proteins called amyloid build up on the walls of the arteries in the brain)
Hemorrhagic strokes may also occur when someone is taking blood thinners, such as warfarin (Coumadin). Very high blood pressure may cause blood vessels to burst, leading to hemorrhagic stroke.
An ischemic stroke can develop bleeding and become a hemorrhagic stroke.
High blood pressure is the main risk factor for strokes. Other major risk factors are:
Irregular heartbeat, called atrial fibrillation
Diabetes
Family history of stroke
Being male
High cholesterol
Increasing age, especially after age 55
Ethnicity (African Americans are more likely to die of a stroke)
Obesity
History of prior stroke or transient ischemic attack (occurs when blood flow to a part of the brain stops for a brief time)
Stroke risk is also higher in:
People who have heart disease or poor blood flow in their legs caused by narrowed arteries
People who have unhealthy lifestyle habits such as smoking, excessive use of alcohol, use recreational drugs, a high-fat diet, and lack of exercise
Women who take birth control pills (especially those who smoke and are older than 35)
Women who are pregnant have an increased risk while pregnant
Women who take hormone replacement therapy
