Brain aneurysm

Overview

A brain aneurysm is a bulge or ballooning in a blood vessel in or around the brain. Most never cause symptoms and are found incidentally on scans. However, if one ruptures it causes a subarachnoid haemorrhage, a sudden, catastrophic bleed into the space around the brain.

How common is it?

Many brain aneurysms cause no symptoms and are discovered during scans for another reason. Most do not rupture, but a rupture is a medical emergency.

Causes and risk factors

Aneurysms form where artery walls are weak, often at branch points of blood vessels at the base of the brain. Factors that damage or stress artery walls increase risk.

Common risk factors

• High blood pressure
• Smoking
• Family history of brain aneurysm
• Female sex (more common in women over 40)
• Certain inherited connective tissue conditions
• Polycystic kidney disease
• Previous head trauma

Symptoms

• Most unruptured aneurysms cause no symptoms
• Sudden severe headache described as the worst of your life (ruptured aneurysm)
• Neck stiffness and sensitivity to light after sudden headache
• Nausea and vomiting with severe headache
• Vision changes or double vision (if pressing on a nerve)
• Loss of consciousness or seizure

When to see a doctor

Call your local emergency number for a sudden, extremely severe headache, sudden vision loss or double vision, new weakness, speech difficulty, collapse or a seizure. A new drooping eyelid or enlarged pupil also needs urgent medical assessment. Do not drive yourself.

Diagnosis

An urgent CT head scan is usually the first test for suspected bleeding. Further tests, sometimes including lumbar puncture, depend on the scan findings, timing and clinical concern. CT or MR angiography can show an aneurysm.

Treatments

Self-care and lifestyle

• Controlling blood pressure is the most important step to reduce rupture risk
• Stop smoking immediately
• Discuss exercise and heavy lifting with your specialist; stay active at a level appropriate to your condition
• Discuss whether family members should be screened if you have a family history

Prevention

Not smoking, maintaining normal blood pressure, and limiting alcohol reduce aneurysm formation risk. Screening is offered to close relatives of people who have had subarachnoid haemorrhage in some centres.