Brain Aneurysm

A brain aneurysm is a blister on a blood vessel in your brain. This occurs when the wall of the vessel becomes weak and starts to stretch. If the area becomes so weak that it tears, it can cause bleeding – a hemorrhage – inside the fluid spaces of your brain.



You may not notice any signs or symptoms of a brain aneurysm until it becomes large enough to press on a nerve or it leaks or ruptures. That means you may not know you have one unless it’s found on a scan or test, such as an angiogram or MRA. 

Just before a tear (or rupture) occurs, you may experience a severe headache (usually the worst headache you ever experienced), along with weakness, loss of consciousness or numbness. You may also have trouble seeing or speaking.

If the aneurysm is pressing on a nerve, you may experience: 

  • A dilated pupil
  • Numbness on one side of your body
  • A droopy eyelid
  • Pain above one eye


Diagnosing a brain aneurysm will begin with your doctor giving you a physical exam and discussing your symptoms. Then, you’ll likely have an imaging test such as an MRI or a CT scan that may show evidence of a bulge or bleeding. Your doctor may also recommend a spinal fluid test. 

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Treatment Options

If you have a test or scan that shows an unruptured brain aneurysm, there are typically two options: 

  • Have doctors keep an eye on it
  • Repair it so it won’t cause you trouble in the future

When deciding your treatment, you and your neuroscience care team will consider the aneurysm’s size and shape, as well as where it is in your brain, how old you are and your family history. 

To repair a brain aneurysm, your team will often take one of these approaches:  

  • A type of surgery called “clipping,” where your doctor finds the blood vessel that's causing the aneurysm and uses a small metal clip to shut off the blood flow. This relieves the pressure on the vessel wall. 
  • A noninvasive procedure that uses special coils to stop blood flow to the aneurysm. Your doctor will set these coils into place by going through your blood vessels. They’ll remain in the aneurysm permanently. 

You and your team of specialist can discuss the best treatment option based on your individual needs.

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