Brain aneurysm


A bulge that forms in the blood vessels of your brain

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What is a brain aneurysm?

An aneurysm is an abnormal weak spot on a blood vessel wall that causes bulging like a balloon, usually where the artery divides and branches. Aneurysms can develop in any blood vessel in your body, with brain aneurysms affected in approximately 1% of the population.

Individuals are not born with arterial aneurysms, they arise during life and the risk factors include smoking and high blood pressure. Other diseases such as polycystic kidneys can also play a role.

Brain aneurysms are more common in people over the age of 40, and women tend to be affected more than men.

Need to know

Most brain aneurysms only cause symptoms if they rupture. This is a medical emergency. Symptoms may include an excruciating headache, which comes on suddenly and is associated with:

  • neck pain
  • nausea and/or vomiting
  • numbness or weakness in one side of your face and/or body
  • dizziness and/or disorientation
  • cute sensitivity to light

Your consultant will perform some, or all, of the following tests to confirm a diagnosis:

  • MRI scan. This is usually used to detect brain aneurysms that have not ruptured, but is also used to look at the arteries in detail (MR angiogram).
  • CT scan. This is usually the preferred type of scan if there is a history suggestive of haemorrhage. CT scans within 3 days of a bleed are very reliable at detecting blood.
  • Angiography (digital subtraction — DSA). This involves injecting contrast into the arteries of your brain through a catheter (narrow tube) to give clear pictures of the brain arteries.
  • Monitoring with MRI scans at yearly intervals, if the aneurysm has not burst and is considered low-risk (normally under 5mm in diameter).
  • Coiling or stenting of the aneurysm using minimally invasive radiology techniques.
  • Clipping. Increasingly this is not necessary but sometimes remains the best option for treatment. A titanium spring clip is placed across the ‘neck’ of the aneurysm where it arises from the parent artery, so it can no longer fill, removing the risk of a future bleed.

Our Brain aneurysm locations

SPECIALIST UNIT  London Neurosurgery Partnership

SPECIALIST UNIT London Neurosurgery Partnership

78 Harley Street W1G 7HJ London
The Harley Street Clinic

The Harley Street Clinic

35 Weymouth Street W1G 8BJ London
The Portland Hospital

The Portland Hospital

205-209 Great Portland Street W1W 5AH London
The Lister Hospital

The Lister Hospital

Chelsea Bridge Road, SW1W 8RH London
The Shard Outpatients

The Shard Outpatients

The Shard, 32 St Thomas Street SE1 9BS London
London Bridge Hospital

London Bridge Hospital

27 Tooley Street SE1 2PR London

Patient stories

This content is intended for general information only and does not replace the need for personal advice from a qualified health professional.