Causes
A stroke happens when blood flow to part of the brain is interrupted due to a blood vessel in the liver is blocked or broken. If blood flow is stopped for more than a few seconds, the brain can not get blood and oxygen. Brain cells can die, causing permanent damage. There are two main types of stroke: ischemic stroke and hemorrhagic stroke.
Ischemic stroke occurs when a blood vessel supplying blood to the brain is blocked by a blood clot. This can happen in two ways:
* You can form a clot in an artery that is already very close, which is called a thrombus. If you block the artery completely, is called a thrombotic stroke.
* A clot can break off from somewhere in the body and travel to the brain to block a smaller artery. This is called an embolism, causing an embolic stroke.
Ischemic strokes can result from clogged arteries, a condition called atherosclerosis (See stroke secondary to atherosclerosis). This can affect the arteries within the brain or neck arteries that carry blood to the brain. The fat, cholesterol and other substances accumulate in the wall of the arteries, forming a sticky substance called plaque. Over time, plaque builds up. This often hinders the proper flow of blood, which can cause the blood to clot.
Ischemic strokes can also be caused by blood clots that form in the heart. These clots travel through the blood and can get stuck in small arteries of the brain, which is known as stroke.
Certain drugs and medical conditions can make blood more likely to clot and increase the risk of ischemic stroke. A common cause of ischemic stroke in people under 40 years is carotid dissection or tear in the lining of the carotid artery. The rupture allows blood flow between the layers of the aorta. This causes narrowing of the artery that is not due to plaque accumulation.
HEMORRHAGIC STROKE
Hemorrhagic stroke occurs when a blood vessel in the brain part weakens and ruptures, causing blood to leak back into the brain. Some people have defects in blood vessels of the brain that make this more likely. Blood flow after the blood vessel ruptures damages the brain cells.
Tags: Brain, Causes, Hemorrhagic stroke., Ischemic stroke, Stroke
