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Brain aneurysm

4-minute read

A brain aneurysm is a bulge in an artery within the brain. Many people have a brain aneurysm without realising it. If the aneurysm leaks or bursts, however, it can cause bleeding on the brain, which can very quickly become life threatening. 

The main symptom of a burst aneurysm is a sudden, very severe headache. If this happens to you, seek medical attention immediately by calling triple zero (000) and asking for an ambulance.

What is a brain aneurysm?

Aneurysms can happen almost anywhere in the body. They develop when a weakness in the wall of an artery causes a swelling. Aneurysms that occur in the brain are also called intracerebral or intracranial aneurysms.

Brain aneurysms are quite common. Some people are born with a weakness in an artery in their brain; in other people, health conditions, such as high blood pressure, atherosclerosis or a head injury, cause the aneurysm. They are more common in adults and in women, although anyone can have a brain aneurysm.

Brain aneurysms can happen anywhere in the brain, but they are most common in the major arteries found along the base of the skull.

There are different types of brain aneurysm:

  • saccular aneurysm: the most common type of aneurysm, which can cause bleeding on the brain
  • fusiform aneurysm: this type is less likely to burst 

When a brain aneurysm bursts and bleeds it can cause a stroke. If the bleeding occurs in the space around the brain, it’s called a subarachnoid haemorrhage (SAH). If it occurs in the brain itself, it’s known as an intracerebral haemorrhage.

About 1 in 5 people who have one brain aneurysm will have another. 

Brain aneurysm symptoms

Many people have a brain aneurysm without realising it. It may only be found when the person has a brain scan for another reason. Usually there are no symptoms. Sometimes, if the aneurysm becomes very large, it can cause pain behind the eyes, numbness, weakness, vision changes or paralysis on the side of the face.

When an aneurysm bursts, it always causes a sudden and extremely bad headache.

Other symptoms of a burst aneurysm include: 

  • double vision
  • nausea and vomiting
  • a stiff neck
  • sensitivity to light
  • weakness in the arms, legs or one side of the face
  • confusion
  • seizures
  • loss of consciousness (briefly or for a long time)
  • cardiac arrest

Brain aneurysm diagnosis

A brain aneurysm is often found during a brain scan such as a  or MRI. These scans or other scans may also be done if the aneurysm bursts, to show where the bleeding is. 

Sometimes your doctor might do a lumbar puncture, which involves taking a sample of the fluid that surrounds your brain and spinal cord by inserting a thin needle into your back. This is to confirm whether you have a subarachnoid haemorrhage.

Sometimes you will have an angiogram, where a thin tube, inserted into your artery along with a special dye, is used to provide detailed information about the aneurysm. 

Brain aneurysm treatment

If the aneurysm is less than 10mm in size, there is only a very small risk it will burst. You will probably be recommended to have regular scans to monitor it, and treatment for any other conditions, such as high blood pressure.

If you have had a burst aneurysm, you will be told to stay in bed and to take pain relief medication for any pain you might be experiencing. You will then have surgery to clip the aneurysm so that it does not bleed again. Another type of surgery involves threading a thin tube through the artery from the groin and using it to insert a tiny metal coil into the aneurysm. This causes a blood clot, which prevents the aneurysm from bursting.

If the aneurysm caused a brain haemorrhage, you may need other treatments for complications, such as reduced blood flow to the brain or fluid on the brain. 

Brain aneurysm prevention

It is not always possible to prevent a brain aneurysm from forming, but you can take steps to prevent it from bursting. If you have been diagnosed with a brain aneurysm:

When to seek help

If you have a sudden, severe headache, call triple zero (000) and ask for an ambulance.

Not sure what to do next? healthdirect’s online Symptom Checker can help.

Learn more here about the development and quality assurance of healthdirect content.

Last reviewed: January 2019

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