Brain aneurysms are caused by a weakness in the walls of blood vessels in the brain. There are several reasons why this may happen, although an exact cause isn't always clear.
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Brain aneurysms are usually treated with surgery if they have burst or there's a risk they will burst.
It's not clear what causes brain aneurysms. You're more likely to get them if you smoke, have high blood pressure or have family members with them.
Symptoms of a brain aneurysm can include headaches or changes in your vision. If it bursts, it can cause a sudden and very severe headache.
Page last reviewed: 16/08/2018
Next review due: 16/08/2021