An aneurysm is a bulge in a blood vessel caused by a weakness in the blood vessel wall, usually where it branches.
A brain aneurysm is a bulge in a blood vessel in your brain. It can be very serious if it bursts.
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