What is a Stroke and why does it happen?

According to the National Institute of Neurological Disorders and Stroke, stroke is the leading serious neurological disorder in the United States. It ranks third among all causes of death and is a major cause of long-term disability in Americans.

A stroke is the disruption of the blood supply to, or within, the brain. When the blood supply is cut off, the brain does not receive the oxygen and nutrients it needs. The result is an injury to the brain cells.

The brain is the nerve centre of the body. If the cells are injured or die from lack of oxygen, the body functions controlled by those brain cells are affected. Unlike other cells in the body, brain cells do not regenerate.

Types of stroke

There are four main types of stroke – two caused by blood clots and two by haemorrhage.

1. Cerebral thrombus stroke is a blood clot that forms in a brain artery, blocking the flow of blood to the brain. Blood clots usually form in arteries damaged by atherosclerosis.
2. Cerebral embolus is a blood clot, or an air bubble or fat globule, formed elsewhere in the body. It then travels to a brain artery, lodges there and cuts off the supply of blood. The most common cause of these emboli is blood clots; that form in the heart of a person who has atrial fibrillation. In this stroke disorder, the two small upper chambers of the heart, the atria; quiver and don’t pump blood out completely.
3. Cerebral haemorrhage is the rupturing of a brain artery that results in bleeding into the surrounding area of the brain. A cerebral aneurysm is the ballooning out of a blood vessel. It may rupture and cause haemorrhage.
4. Subarachnoid haemorrhage stroke occurs when a blood vessel on the surface of the brain ruptures and bleeds into the space between the brain and the skull (but not into the brain itself.)

Reference

1. American Heart Association