Strokes caused by a break in the wall of a blood vessel in the brain are called haemorrhagic strokes (hemm-orr-ragic).
This causes blood to leak into the brain, stopping the delivery of oxygen and nutrients.
Types of haemorrhagic stroke
Haemorrhagic strokes are described by their location in the brain. There are two types:
- Intracerebral haemorrhage occurs when an artery inside the brain bursts and bleeds into the brain. The most common cause is high blood pressure (hypertension).
- Subarachnoid haemorrhage (SAH) is bleeding on the surface of the brain. There are 3 layers of membrane (or meninges) that cover the brain. A subarachnoid haemorrhage is a bleed that happens between the layer closest to the brain and the second layer.
Causes of haemorrhagic stroke
Haemorrhagic stroke can be caused by a number of disorders which affect the blood vessels, including long-standing high blood pressure and cerebral aneurysms.
This is a weak or thin spot in the wall of an artery that balloons out. As the aneurysm gets bigger, it gets weaker and can burst. If the aneurysm bursts, it leaks blood into the brain.
The weak spots that cause aneurysms are usually present at birth. Aneurysms develop over a number of years and usually don't cause detectable problems until they break.
A burst aneurysm is usually caused by high blood pressure (hypertension) or trauma (a sudden injury to the head).
Arteriovenous malformation (AVM)
An AVM is a tangled mass of blood vessels (arteries and veins). It can occur anywhere in the body, including the brain.
An AVM is usually present at birth. It may be that as you get older the blood vessels get bigger and weaker.
If the AVM is located in the brain and the blood vessel walls burst, then you will have a haemorrhagic stroke.
If you or a loved one has had a stroke, there is support available. See our help after stroke section for more information.