A stroke occurs when the blood supply to the brain or part of the brain is disrupted causing death of brain tissue and loss of function.
Usually this is the result of blockage of an artery to the brain either by narrowing of the arteries or hardening of the arteries (atherosclerosis).
Sometimes blood clots from the heart circulate to the brain and cause sudden blockage, or arteries can burst or rupture.
Stroke is more common in people with diabetes, blood pressure, high cholesterol and smokers. Patients who have suffered a stroke are usually looked after by doctors who specialise in stroke medicine.