Your brain gets blood mainly through two arteries in your neck (carotid arteries) and two arteries near your spine (vertebral arteries). They branch into other blood vessels that supply your brain with blood.
When the blood can't flow to your brain, your brain cells start to die. Stroke symptoms will start to appear.
There are two types of stroke: ischemic and hemorrhagic.
There are two main types of ischemic stroke:
Thrombotic: This is the most common type.
Over time, fatty deposits (plaque) attach inside the artery walls. The plaque may narrow or close the artery, preventing normal blood to flow to the brain.
Another type of thrombotic stroke occurs deep in the brain. It involves smaller vessels and causes damage to small areas of brain tissue. This type is called lacunar. The location of the lacunar stroke determines how extensive the stroke symptoms will be.
Embolic: This occurs when a small blood clot breaks off from a blood vessel in the heart or one of the larger blood vessels leading to the brain.
This clot travels in the bloodstream to the brain until it becomes stuck and blocks a blood vessel.
In more severe strokes, the large cerebral blood vessels, the carotid arteries or the vertebral arteries can be blocked. This blockage may result in permanent injury to the large area of the brain.
This type of stroke often causes more serious problems due to widespread brain damage. This damage can cause swelling in the brain, which may lead to more injury and, sometimes, death.
Blood carries oxygen and nutrients through your body.
This type of stroke happens when a blood vessel in the brain ruptures and bleeds.
It can be caused by a weakened area in the wall of a blood vessel or by abnormal branching of blood vessels. This is knows as an arteriovenous malformation (AVM).
It can also be caused by dangerously high blood pressure.
About 15 percent of all strokes are hemorrhagic. Also, bleeding can occur in the area of the brain already damaged by an ischemic stroke. (See treatment for more information.)
Allina Health Patient Education, Understanding Stroke: Information about Stroke and Recovery, fourth edition, ISBN 1-931876-13-4
Allina Health Patient Education experts