A brain aneurysm occurs when a weak spot in your brain’s arterial wall bulges and fills with blood. It may also be called an intracranial (skull) aneurysm or a cerebral (brain) aneurysm. A brain aneurysm is a potentially life-threatening condition that can affect a person at any age. If a brain aneurysm bursts, it’s an emergency situation that can result in a stroke, brain damage, and even death if not treated immediately.

What Does a Brain Aneurysm Look Like? What Causes It?

Brain aneurysms can take several forms. Almost 90 percent are saccular aneurysms. This type forms a sac outside the artery that looks like a berry (another name for it is a “berry aneurysm”). A fusiform aneurysm is an uncommon aneurysm that causes the artery to bulge all the way around. A dissecting aneurysm is a tear in one of the several linings of an artery. It can leak blood into the other layers and balloon out or block the artery.

Some events encourage the development of an aneurysm in the brain. Some aneurysms develop over the course of a person’s lifetime, some are inherited, and some are a result of brain injuries.

Autosomal dominant polycystic kidney disease (ADPKD) is an inherited condition that affects kidney function and also produces cobweb-like, fluid-filled pockets (cysts) in brain tissue. The condition raises blood pressure, which weakens blood vessels in the brain and elsewhere in the body.

Marfan’s syndrome is also an inherited condition and affects the genes that control the formation of the body’s connective tissue. Damage to the structure of the arteries creates weaknesses that can lead to brain aneurysms.

A traumatic brain injury can tear the tissue and create what’s known as a dissecting aneurysm. A serious infection in the body can lead to an aneurysm if the infection damages the arteries. Smoking and chronic high blood pressure are also sources of many brain aneurysms.

Who’s at Risk for a Brain Aneurysm?

Brain aneurysms can affect anyone, but people with atherosclerosis (hardening of the arteries) are at high risk of forming brain aneurysms. Women over the age of 40 are at an increased risk as well. Other people at risk for brain aneurysms are those who:

  • smoke
  • abuse drugs
  • have high blood pressure
  • have congenital problems that affect the arterial walls
  • have had abnormal growths in the head or body (tumors)
  • have brain injuries
  • have had severe infections of the blood or brain
  • have high LDL cholesterol
  • have a family history of aneurysms

What Are the Symptoms of a Brain Aneurysm?

Aneurysms are unpredictable and may not show any symptoms until they rupture. Large or ruptured aneurysms will usually show definite symptoms and require emergency medical care.

The following are symptoms and warning signs of an aneurysm or a ruptured aneurysm:

  • headache or pain behind or above the eye (can be mild or severe)
  • dilated pupils
  • drooping eyelids
  • sensitivity to light
  • blurred or double vision
  • weakness or numbness on one or both sides of the body
  • trouble speaking or a change in awareness and mental state
  • trouble walking or dizziness
  • nausea or vomiting
  • seizure (convulsion)
  • loss of consciousness

How Is a Brain Aneurysm Diagnosed?

Unless an aneurysm ruptures, it may be difficult to diagnose the condition. There are tests that can help doctors locate aneurysms in people who have family histories of the condition, high-risk factors, and inherited, aneurysm-related health issues.

Computerized tomography (CT) and magnetic resonance imaging (MRI) scans take pictures of the brain tissues and arteries. CT scans are usually better at revealing any cranial bleeding that may already be present. A spinal tap, where a doctor draws fluid from the spine, can check for signs of bleeding in the brain. Cerebral angiograms can also check for bleeding and any abnormalities in the brain arteries.

Treating Brain Aneurysms

Treatments for aneurysms are usually based on the size, location, and severity of the condition. Pain medication can soothe headaches and eye pain. Your doctor can also prescribe medication designed to prevent blockage of the blood vessels or relieve cranial pressure. If the aneurysm is accessible, surgery can repair or cut off blood flow to the aneurysm. This can help prevent further growth or a rupture.

What Is the Outlook for Someone With a Brain Aneurysm?

It’s important to be vigilant in monitoring an aneurysm for signs of a rupture. People who get immediate treatment for ruptures have much higher survival and recovery rates than those who don’t seek emergency medical care right away. Be alert to the warning signs, and if you have any of the risk factors, see your doctor immediately for an examination.

That said, not all aneurysms will rupture. According to the Brain Aneurysm Foundation in Boston, an estimated 50 to 80 percent of all aneurysms never rupture in a person's lifetime.

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