Brain aneurysm: symptoms, causes, treatment and when it bursts

The NHS says that most brain aneurysms are small and do not cause symptoms, and are often found during a test for another condition. A larger aneurysm may cause symptoms such as those in the table. Because these symptoms have many other causes, they are not specific to an aneurysm.

The NHS says that if a brain aneurysm bursts, it can cause a bleed on the brain called a subarachnoid haemorrhage (SAH). This is a rare type of stroke that causes bleeding on the brain and is a life-threatening emergency. It can happen at any time, but may be more likely when you are doing something like coughing, going to the toilet, lifting something heavy or having sex.

The Stroke Association says subarachnoid haemorrhage causes about 5% of all strokes in the UK, and that it is the less common type of stroke. About 15% of strokes in the UK are haemorrhagic, caused by bleeding in or around the brain. A subarachnoid haemorrhage most commonly affects people who have a brain aneurysm, but can also be caused by a severe head injury or a problem with the way blood vessels in the brain have formed.

The NHS says to call 999 if you or someone else suddenly gets any of the following. Do not drive yourself to A&E. The person you speak to at 999 will give you advice about what to do.

• A headache that is extremely painful and does not go away.

• Weakness in the face: one side of the face may droop and it might be hard to smile.

• Weakness or numbness in one arm or down one side of the body, so you cannot fully lift both arms and keep them there.

• Speech problems, such as slurring words, sounding confused, or finding it difficult to find the right words.

• Blurred vision or loss of sight in one or both eyes.

The NHS says it is not always clear what causes brain aneurysms, but that things that increase your chances of getting one include smoking, high blood pressure, having a close relative who has had a brain aneurysm, an injury to a blood vessel in your brain, taking drugs such as cocaine, and certain genetic conditions, such as autosomal dominant polycystic kidney disease (ADPKD) or Ehlers-Danlos syndrome.

For subarachnoid haemorrhage the NHS adds that some people have aneurysms from birth while others get them later, and that you may be more likely to have one if other people in your family have them.

The NHS says treatment is not usually needed for small brain aneurysms that are not causing symptoms, because they often do not get bigger and have a low risk of bursting. You may just need regular follow-up scans to check whether it is getting bigger. If there is a risk of the aneurysm bursting, or if it has already burst, surgery will usually be needed.

The NHS says how a subarachnoid haemorrhage affects your life varies from person to person and depends on where in the brain the bleeding happened and the amount of damage it caused. Although it can take months or years to get better, most people improve with treatment and some recover fully. But it is a very serious condition that can lead to mental and physical disability and significantly affect quality of life.

Possible effects include seizures, heart, lung or liver problems, cognitive difficulties such as problems with memory, concentration and communication, depression and mood changes, fatigue, and headaches and unusual feelings. A small number of people develop epilepsy. Rehabilitation may include physiotherapy, speech and language therapy, cognitive behavioural therapy and cognitive exercises, and you will have regular follow-up with your doctor and recovery team.

The NHS says that if you have a brain aneurysm there are things you can do to reduce the risk of it getting bigger and bursting. Stop smoking, keep your blood pressure at a healthy level, and make healthy lifestyle changes such as eating a balanced diet, exercising regularly and losing weight if you are overweight. Do not drink too much alcohol and do not take illegal drugs.

You may not be allowed to drive if you have a brain aneurysm. Your doctor can advise whether it is safe for you to drive and if you need to tell the DVLA. Support is available from Headway and the Brain and Spine Foundation, which the NHS signposts.

The NHS says to ask for an urgent GP appointment or get help from NHS 111 if you keep getting headaches and they do not go away or are getting worse, you have pain above or around your eye, or you have any other symptoms of a brain aneurysm that do not go away. Most headaches are not caused by aneurysms, but these need assessment.

A suspected ruptured aneurysm is an emergency pathway through 999 to a hospital with neurosurgical services; it is not something to arrange privately. NICE guideline NG228 covers the diagnosis and management of aneurysmal subarachnoid haemorrhage and its complications, including follow-up care and information for people and carers.

An aneurysm found by chance on a scan is usually assessed by a neurosurgical or neuroradiology team, who decide between monitoring and treatment. Private scans and consultations are available, but the decision about intervention is made by a specialist team, so ask who will follow you up and how often scans are planned.