A stroke happens when the blood supply to part of the brain is cut off.
There are two main types of stroke.
Ischaemic strokes are caused by a blockage in the blood supply to the brain.
Haemorrhagic strokes occur when blood leaks from a burst blood vessel into the brain. In adults, 80 per cent of strokes are caused by a blockage and 20 per cent by a bleed in the brain. In children both types of stroke are equally common.
Children can also have transient ischaemic attacks (TIAs). A TIA happens when the brains blood supply is interrupted for a very brief time. The symptoms only last for a few minutes or hours and then completely disappear, usually within 24 hours.
In adults, a TIA does not cause any permanent damage to the brain. However, research has shown that children who have TIAs often have an area of brain injury even if they have no remaining symptoms.