Brain aneurysm

What is a brain aneurysm?

A brain aneurysm is a blister-like swelling in the wall of a weakened blood vessel in the brain.

A large or growing aneurysm can put pressure on the surrounding brain tissue. This can disrupt vital blood and oxygen flow in the brain. In rare cases, there is a risk that the aneurysm may burst (this is called 'rupturing'), causing blood to leak around the brain.

A brain aneurysm that has already burst is a very serious condition known as a subarachnoid haemorrhage, and it needs urgent treatment.

A brain aneurysm that is small, is not causing symptoms or is assessed as having a low risk of rupturing is usually not considered to be a brain injury. However, it is still important for the person to monitor for symptoms, follow medical advice given by specialists, continue to attend routine appointments and discuss any concerns with their GP.

What causes a brain aneurysm?

It is not always clear why a brain aneurysm develops, but several factors are associated with an increased risk. These include:

• Smoking;

• High blood pressure;

• Cocaine use;

• Family history of brain aneurysm;

• Certain medical or inherited conditions.

In rare cases, a severe head injury can cause an aneurysm to develop. This is known as a traumatic intracranial aneurysm, meaning an aneurysm inside the skull caused by an injury.

What happens in a brain aneurysm?

When the wall of a blood vessel is weakened, the pressure from blood passing through can cause part of it to swell into an aneurysm.

Most brain aneurysms do not cause any symptoms, and many people will be unaware that they have one unless it is found by chance, such as if they have a brain scan for a separate medical issue.

Larger brain aneurysms may cause symptoms such as:

• Headaches;

• Vision changes;

• Pain around the eyes;

• Problems with balance or dizziness;

• Facial numbness.

If a person with a brain aneurysm has these symptoms and they are either not going away or are getting worse, they should ask for an urgent GP appointment or contact NHS 111 immediately.

A brain aneurysm that bursts can cause blood to leak around the brain. This is a medical emergency known as a subarachnoid haemorrhage. Symptoms include:

• A sudden, agonising headache known as a ‘thunderclap headache’;

• Feeling or being sick;

• Stiff neck or neck pain;

• Weakness or drooping on one side of the face;

• Weakness on one side of the body or in any limbs;

• Sensitivity to light;

• Blurred vision or loss of sight;

• Sudden confusion;

• Speech problems;

• Loss of consciousness;

• Seizures.

Call 999 immediately if you or someone else develops a sudden, extremely painful headache. You should also call 999 for sudden facial weakness, weakness or numbness on one side of the body, speech problems such as slurred speech or vision problems such as blurred vision or loss of vision. If you are experiencing these symptoms, do not drive yourself to A&E.

How is a brain aneurysm treated?

A brain aneurysm that is assessed as being at low risk of bursting will usually be monitored rather than treated with a procedure. For instance, the person may need to have regular, follow-up brain scans to monitor for any growth of the aneurysm. This is because the risk of treating it may outweigh any benefit, especially if the aneurysm is small, is not causing symptoms or is assessed as having a low risk of rupturing.

It can be upsetting and frightening to know that you have a brain aneurysm that is being monitored rather than treated. However, be assured that your medical team will consider and discuss the benefits and risks of treatment with you. It may help to know that most brain aneurysms do not grow, and they are often only detected by chance. If you are concerned about symptoms, talk to your GP or neurologist.

An aneurysm that is at risk of bursting or has already burst may be treated with surgery. There are two main procedures that can be performed.

• Endovascular surgery

  Coils may be placed inside the aneurysm to seal it, or a mesh device may be used to divert blood flow away from it. This stops further blood from flowing into it and can help a blood clot to form. The coil or mesh is threaded through an artery in a thin tube called a catheter up to the aneurysm.

• Surgical clipping

  This is where a section of skull is removed (called a craniotomy) to reach the aneurysm. A metal clip is then attached to the ‘neck’ of the aneurysm to stop blood from flowing into it.

Both procedures are carried out under general anaesthetic, which means the person is asleep during the procedure. The medical team will discuss details of the chosen procedure with the person beforehand, including what may happen during the recovery phase.

What happens after a brain aneurysm is treated?

Following treatment for a brain aneurysm that was large, was at risk of bursting or had already burst, a person will usually need to stay in hospital for several weeks to recover from their treatment. They will continue to be monitored by the medical team.

The person may need to undergo a period of rehabilitation to cope with the physical, cognitive or emotional impact of the brain aneurysm. This can take place within the hospital, at a specialist brain injury rehabilitation unit or through community-based teams.

A person may be able to return directly home from hospital, but they will need to continue resting. The time needed to recover and return to usual activities varies from person to person.

For more information on these next stages, visit Treatment and rehabilitation.