Brain Aneurysm

Overview

A brain aneurysm is a weak, balloon-like bulge in the wall of an artery that supplies the brain. Because the artery wall is thinner and weaker at that spot, it can stretch and, in some cases, leak or burst. When an aneurysm ruptures, blood spills into or around the brain, an event that is often life-threatening and needs emergency care.

Many brain aneurysms are small, never rupture, and cause no symptoms; some are found by chance during scans done for other reasons. The main concern is rupture, which most commonly causes bleeding into the space around the brain, known as a subarachnoid hemorrhage. Knowing the sudden warning signs and acting fast can be lifesaving.

Symptoms

Most unruptured aneurysms cause no symptoms. A large one pressing on nearby structures may cause:

• Pain above or behind one eye
• A drooping eyelid or a dilated pupil
• Double vision or other vision changes
• Numbness on one side of the face

A ruptured aneurysm is a medical emergency. Warning signs include:

• A sudden, extremely severe headache, often described as the worst of your life (a thunderclap headache)
• A stiff neck, nausea, and vomiting
• Sensitivity to light
• Sudden confusion, seizure, drooping eyelid, or loss of consciousness

If these occur, call emergency services immediately.

Causes

Brain aneurysms develop where the wall of an artery becomes weakened, often at branch points where vessels divide and stress on the wall is greatest. Over time, blood pressure can push the weak area outward into a bulge.

Some people are born with a tendency toward weaker artery walls, and certain inherited conditions increase the risk. In others, lifelong factors such as high blood pressure, smoking, and the natural aging of blood vessels contribute. Head injury and certain infections can rarely cause aneurysms as well.

Risk Factors

• High blood pressure
• Smoking
• A family history of brain aneurysm
• Older age
• Inherited conditions such as polycystic kidney disease or certain connective tissue disorders
• Heavy alcohol use and stimulant drug use such as cocaine
• Female sex, as aneurysms are somewhat more common in women

Diagnosis

Brain aneurysms are diagnosed with imaging of the brain and its blood vessels:

• CT scan: Often the first test in an emergency, it can quickly show bleeding from a ruptured aneurysm.
• CT angiography or MR angiography: Detailed scans that map the blood vessels and reveal the aneurysm's size and location.
• Lumbar puncture: A sample of the fluid around the spine and brain may be checked for blood if a rupture is suspected but not seen on a scan.
• Cerebral angiography: A catheter-based test that gives the most detailed pictures of the brain's arteries.

Treatment

Treatment depends on whether the aneurysm has ruptured and on its size, location, and shape.

• Emergency care for rupture: A ruptured aneurysm needs urgent treatment to stop the bleeding and prevent it from bleeding again, along with intensive monitoring.
• Surgical clipping: A surgeon places a tiny clip across the base of the aneurysm to seal it off from blood flow.
• Endovascular coiling: A catheter is threaded through blood vessels to fill the aneurysm with soft coils so it clots and stops filling with blood; sometimes a small stent is also used.
• Monitoring: Small, low-risk unruptured aneurysms may simply be watched with regular scans, along with control of blood pressure and stopping smoking.

Prevention

You cannot always prevent a brain aneurysm, but you can lower the risk of one forming or rupturing:

• Do not smoke, and avoid secondhand smoke
• Keep blood pressure well controlled
• Limit alcohol and avoid stimulant drugs such as cocaine
• Eat a balanced diet and stay physically active
• If you have a strong family history or an inherited condition, ask your doctor whether screening is appropriate

When to See a Doctor

Call emergency services immediately for a sudden, severe headache unlike any you have had before, especially with a stiff neck, vomiting, vision changes, confusion, seizure, or loss of consciousness. These can signal a ruptured aneurysm.

See a doctor in a non-emergency setting if you have a strong family history of brain aneurysm, or new symptoms such as eye pain, a drooping eyelid, or double vision, so an unruptured aneurysm can be evaluated.

Related Topics

Frequently Asked Questions

References

1. National Institute of Neurological Disorders and Stroke (NINDS). Cerebral Aneurysms.
2. Mayo Clinic. Brain aneurysm — Symptoms and causes.
3. MedlinePlus, U.S. National Library of Medicine. Brain aneurysm.
4. American Stroke Association. Brain Aneurysm.