For the brain to function, it needs a constant supply of blood to deliver vital nutrients and oxygen to the brain cells. A stroke occurs when this supply is impaired or cut off.
There are two main causes of stroke:
1. Ischemic Stroke
This is the most common type of stroke and happens when a blockage forms in a blood vessel (ischemic stroke).
What causes ischemic stroke?
This can be due to a number of factors:
• A blood clot forms in a main artery to the brain (sometimes called a cerebral thrombosis)
• A blockage, usually a blood clot from the heart, is carried in the bloodstream to one of the arteries supplying the brain (called a cerebral embolism)
• A blockage forms in the tiny blood vessels deep within the brain (called a lacunar stroke)
2. Hemorrhagic stroke
The other main type of stroke is caused by bleeding in or around the brain. This type of stroke is called a hemorrhagic stroke.
What causes hemorrhagic stroke?
There are two main causes of hemorrhagic stroke:
• A blood vessel bursts within the brain (an intracerebral hemorrhage)
• A blood vessel on the surface of the brain bursts, causing bleeding into the area between the brain and the skull (called a subarachnoid hemorrhage)