Stroke is a cardiovascular disease that affects the blood vessels supplying blood to the brain.
It occurs when a blood vessel that carries oxygen and nutrients to the brain bursts or is clogged by a blood clot. Because of this rupture or blockage, part of the brain does not get the blood flow it needs. Deprived of oxygen, nerve cells in the affected area of the brain cannot function and die within minutes. When nerve cells cannot function, the part of the body controlled by these cells cannot function either. The devastating effects of stroke are often permanent because dead brain cells cannot be replaced.