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.
- Ischemic stroke
- 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. 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:
- Arteriovenous malformation (AVM)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.