There are two types of strokes – ischaemic (clot) and haemorrhagic (bleed). About 85% of all strokes are ischaemic and 15% haemorrhagic.
Ischaemic strokes are caused by a blockage cutting off the blood supply to the brain. The blockage can be caused by a blood clot forming in an artery leading to the brain or within one of the small vessels deep inside the brain.
Haemorrhagic strokes are caused when a blood vessel bursts within or on the surface of the brain. Because the blood leaks out into the brain tissue at high pressure, the damage caused can be greater than the damage caused by strokes due to a clot.
There are two types of haemorrhagic stroke:
Haemorrhagic strokes are generally more severe and are associated with a considerably higher risk of mortality within three months and beyond, when compared to ischaemic strokes.
10–15% of people affected with SAH die before reaching hospital and 25% die within 24 hours.
Without treatment 25–30% will re-bleed within the first four weeks – 70% of these people will die as a result.
It is not unusual for strokes to be of an undetermined cause.
For more information visit stroke.org.uk