An aneurysm is a bulge in a blood vessel that is caused by a weakness in the blood vessel wall, usually where it branches.
Aneurysms can develop in any blood vessel, but they most commonly develop in the brain and abdominal aorta (the large artery that carries blood from the heart to the rest of the body).
An abdominal aortic aneurysm (AAA) is a bulge or swelling in the aorta, the main blood vessel that runs from the heart down through the chest and tummy.
It is not possible to completely prevent a brain aneurysm. However, you can reduce your risk of getting an aneurysm or of an aneurysm growing bigger and rupturing by:
Aneurysms most commonly occur in the brain and abdomen (abdominal aortic aneurysm, also known as an AAA). Both brain and abdominal aortic aneurysms do not usually cause noticeable symptoms unless they rupture.
However, some people with an abdominal aortic aneurysm may have:
If an abdominal aortic aneurysm bursts (ruptures), it can cause:
Call an ambulance if you have, or think you may have, a burst aneurysm.
Most brain aneurysms only cause symptoms when they burst (rupture). This means that there are often no warning signs of a brain aneurysm. But in some cases, there may be warning signs. These include:
Yes. Most brain aneurysms do not rupture, and brain aneurysms are usually only fatal when they burst.
A brain aneurysm rupture is a serious condition. It causes a type of bleeding in the brain called a subarachnoid haemorrhage. Around three in five people with a subarachnoid haemorrhage die within two weeks. Half of those who survive are left with severe brain damage and disability.
It is difficult to know exactly how common brain aneurysms are, as most brain aneurysms cause no symptoms and are never diagnosed.
However, estimates suggest that the frequency of brain aneurysms may range from as high as one in 20 people to as low as one in 100 people.
Important: Our website provides useful information but is not a substitute for medical advice. You should always seek the advice of your doctor when making decisions about your health.