Stroke
A serious medical condition which occurs when the blood supply to part of the brain is cut off. The brain needs the oxygen and nutrients provided by blood to function properly. If the supply of blood is restricted, brain cells begin to die, which may lead to brain damage and, possibly, death.
Symptoms...

There are two main causes of stroke:
IschaemicThe blood supply is stopped due to a blood clot (over 80% of all cases).
HaemorrhagicA blood vessel supplying the brain bursts and causes brain damage.