What is a brain aneurysm?

A brain (cerebral) aneurysm is a bulging, weak area in the wall of an artery that supplies blood to the brain. Most brain aneurysms don't cause problems.

Sometimes an aneurysm bursts, or ruptures. Blood may spill into the area between the brain and the skull (subarachnoid hemorrhage). This bleeding in the brain is also called a hemorrhagic stroke. The bleeding may lead to brain damage or even death.

What causes it?

Brain aneurysms seem to run in some families. They may also form because of hardening of the arteries (atherosclerosis) and aging.

Some things can increase your risk for an aneurysm. They may also increase the risk that an aneurysm will rupture. These include:

Family history.

You may be more likely to have a brain aneurysm if someone else in your family had one. Aneurysms may also be linked to certain inherited diseases.

Previous aneurysm.

If you had one brain aneurysm, you're more likely to have another.

Being a woman.

Women have a higher risk of brain aneurysms than men do.

High blood pressure.

High blood pressure damages artery walls and makes an aneurysm more likely to rupture.

Smoking.

Tobacco use damages arteries and increases the risk that an aneurysm will rupture.

Drugs or heavy alcohol use.

Drugs, such as cocaine, or drinking a lot of alcohol raises the risk of an aneurysm.

What are the symptoms?

Most brain aneurysms don't cause symptoms. But in some cases, an aneurysm may press on areas in the brain. This may cause symptoms such as headaches, vision problems, changes in speech, or neck pain. The symptoms depend on what areas of the brain are affected and how big the aneurysm is.

If a brain aneurysm ruptures, symptoms often come on suddenly. They may include:

• A sudden, severe headache that is different from past headaches.
• Neck pain.
• Nausea and vomiting.
• Sensitivity to light.
• Fainting or loss of consciousness.
• Seizures.

How is it diagnosed?

Brain aneurysms are sometimes found by chance during tests done for another condition.

If your doctor thinks you have a brain aneurysm, you may have tests such as:

Computed tomography (CT) scan.

A CT scan can help a doctor find bleeding in the brain.

CT angiogram.

This is a CT scan in which dye (contrast material) is injected into the blood. It gives more detailed images of blood vessels than a standard CT scan.

Magnetic resonance angiogram (MRA).

An MRA uses a magnetic field and radio waves to provide pictures of blood vessels. A dye may be used to make blood vessels show up more clearly.

Cerebral angiogram.

A doctor puts a thin tube (catheter) through a blood vessel in the groin or arm and moves it up into one of the brain arteries. A dye is injected to help problems show up in an X-ray.

How is it treated?

Procedures to treat aneurysms have risks, and treatment isn't always needed. To decide what's best, you and your doctor will think about things like the aneurysm's size and location, your age, and your medical history.

• If the aneurysm has a low risk of rupture, you may have regular tests to check it.
• If the aneurysm is large or causing symptoms or if you've had a ruptured aneurysm in the past, your doctor may recommend treatment. An aneurysm that has bled needs to be treated right away.

Treatments include:

A catheter procedure.

Tools such as tiny coils may be used to stop blood flow to the aneurysm.

A surgery called clipping.

Placing a clip around the base of the aneurysm stops blood flow.

It's important to take steps to reduce your risk of rupture. This includes managing high blood pressure and not smoking.