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​Brain Aneurysm (Cerebral Aneurysm)

A brain (or cerebral) aneurysm is a weak spot in a brain artery that balloons out and fills with blood.

If an aneurysm ruptures, the blood briefly but seriously spreads throughout the spaces of the brain.

This is a life-threatening issue that needs urgent care to:

  1. Treat the high pressure in the brain that results from the rupture.
  2. Prevent a high risk of rebleeding from the aneurysm.

Not all brain aneurysms burst. Many are very small, cause no symptoms, and need no treatment. You can live your whole life without knowing you have one, and they're often found by chance.

The two main treatments for aneurysms are open microsurgery and endovascular therapy.

Learn more about:

Looking for brain aneurysm care?

Contact the UPMC Department of Neurosurgery

To schedule an appointment or ask a question:

  • Call us at 1-412-647-3685.
  • Call us at 1-877-320-8762 (international calls).

What Is a Brain Aneurysm?

A brain aneurysm is a cerebrovascular disorder.

An aneurysm occurs when the wall of an artery in the brain becomes weak and balloons outward.

The ballooned part of the artery is the aneurysm. It has thin walls and can leak or burst.

Brain aneurysms:

  • Tend to form where arteries branch, because these are the weakest places in the artery walls.
  • Come in many sizes and can burst at any time.
  • Are more common in older people and women.

What causes a brain aneurysm?

There may be a genetic link to brain aneurysms.

You're at a higher risk of getting one if you have:

  • A first-degree relative who has had an aneurysm.
  • Certain genetic connective tissue disorders.

Whether a brain aneurysm ruptures or not may depend on its size and where it is.

Factors that can increase the odds of ruptured aneurysms are:

  • Large aneurysms or ones that keep growing.
  • A family history of ruptures.
  • Smoking.
  • High blood pressure.

What are the complications if a brain aneurysm bursts?

When an aneurysm ruptures, blood leaks into the fluid-filled space around the brain.

This bleeding is very dangerous and can cause:

  • Brain damage.
  • Disability.
  • Death.
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Brain Aneurysm Symptoms and Diagnosis

What are the warning signs and symptoms of a brain aneurysm?

You may not have any symptoms if your aneurysm is small and doesn't cause any problems. Most aneurysms have no symptoms until they're large or they rupture.

An aneurysm that's growing large enough to press on tissues or nerves may cause symptoms such as:

  • Pain above or behind the eye, often with a dilated pupil.
  • Double vision or other vision issues.

As for ruptured aneurysms, the biggest symptom is a severe and sudden headache.

Most people who've had a rupture describe it as the worst headache of their life.

How do you diagnose a brain aneurysm?

Your doctor will ask about your symptoms.

If they suspect an aneurysm, they'll order either a:

  • CT scan with dye (CTA).
  • Special type of MRI scan (MRA) that takes pictures of the blood vessels.

We'll order a standard CT scan of your head if:

  • You come to the ER with the worst headache of your life.
  • There's concern for a brain bleed.
If the CT scan doesn't show blood in the brain or other problems, we'll do a lumbar puncture (spinal tap).

This test checks for blood in the cerebrospinal fluid. If we find blood, this means your brain aneurysm ruptured.

Once doctors learn you've had a rupture, they'll do either a CTA or MRA to find the bleed's source.

Then your doctor will advise the best treatment plan for you.

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Brain Aneurysm Treatments

Treatment depends on where the aneurysm is, and may include:

  • Open microsurgery.
    • Most often in the form of clipping.
    • More complex cases may need clipping and bypass to ensure good blood flow to parts of the brain.
  • Endovascular surgery.
    • Often in the form of coiling, with or without a stent, or an intrasaccular device instead of coils.
    • May use flow-diverting stents for unruptured aneurysms.
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