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 doesn't get the blood flow it needs. Deprived of oxygen, nerve cells in the affected area of the brain can't function and die within minutes. When nerve cells can't function, the part of the body controlled by these cells can't function either. The devastating effects of stroke are often permanent because dead brain cells can't be replaced.