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Brain Aneurysm

Know the #1 sign and when to go to the ER.
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Last updated February 9, 2022

Brain aneurysm quiz

Take a quiz to find out if you have brain aneurysm.

What is a brain aneurysm?

A brain aneurysm is a bulge in the wall of an artery inside or near the brain. This usually happens because part of the blood vessel wall is weak, which lets blood fill up in a balloon-like pouch. Most aneurysms have no symptoms or cause no problems.

But in some cases, the wall of the aneurysm becomes too thin and the pouch can burst. This ruptured brain aneurysm causes bleeding around the brain and can cause symptoms like a severe headache. It can cause brain damage and be life-threatening. It requires immediate treatment at the ER.

Fortunately, a brain aneurysm that bursts is very rare. But aneurysms happen to about 1% to 2% of all people.

Most common symptoms

Pro Tip

If you have a headache, there is an overwhelming chance that it is not due to an aneurysm. Headache from a ruptured aneurysm is very characteristic: it is sudden, severe, described as a “thunderclap,” and is often associated with nausea and vomiting. —Dr. Brian Walcott

The vast majority of brain aneurysms have no symptoms at all. They usually only cause problems or symptoms if they burst, or if they become so large that they press on nerves near the brain.

If an aneurysm bursts, it will cause a severe and sudden headache that does not get better. People often describe it as the “worst headache of their life.”

Neck stiffness and sensitivity to bright lights are also common symptoms. Sometimes, people get drowsy along with the headache. If the bleeding is very bad, it can cause someone to have trouble breathing or fall into a coma (become unconscious).

Main symptoms

Other symptoms you may have

If the aneurysm does not burst but grows large enough to press on nerves (which is rare), you may have:

  • Double vision
  • Blurry vision
  • Difficulty with balance and walking

There are a few things that feel similar to an aneurysm rupture, such as very bad tension-type headaches or migraines. Even a sinus infection can sometimes cause a headache that is similar to an aneurysm rupture. Rarely, meningitis (inflammation in the brain and spine) can also cause similar symptoms.

If you normally get headaches or migraines, you wouldn’t go to the ER unless a headache felt very different or a lot more intense than your typical headache.

Next steps

If a severe headache—the worst of your life—hits you very suddenly, call 911 or go to the ER immediately. If it is a brain aneurysm, immediate medical attention is needed to help prevent life-threatening complications.

At the hospital, it is especially important to be screened for a brain aneurysm if you have two or more first-degree relatives (parents, siblings, or children) who have had one.

Dr. Rx

Many people think that all aneurysms need to be repaired. For small aneurysms, sometimes the safest thing to do is to observe them, since the risk of bleeding is very close to zero. —Dr. Walcott

Brain aneurysm treatment

If you have symptoms of an aneurysm that’s pressing on a nerve, or if one shows up unexpectedly on a brain scan (like for a concussion), there are several treatment options or you may take a wait-and-see approach. If an aneurysm ruptures, it is almost always repaired with surgery to prevent another episode of bleeding.


If you have a small aneurysm that is not likely to burst, your doctors will want to see you periodically for observation, to keep track of the aneurysm’s size. You probably will not need surgery.

If the aneurysm is at a high risk for bursting, you might need a procedure to repair the blood vessel and prevent bleeding. One option is surgery to open the skull (craniotomy for aneurysm clipping). Another is a procedure where the doctor will go inside the blood vessel to repair it (endovascular coiling or stenting).

  • Craniotomy. The surgeon will repair the aneurysm by using a microscope to place a clip across the bottom of the bulge to seal it off. The surgery is done under general anesthesia and you will stay in the hospital for a few days after the surgery. Most people feel a mild to moderate headache afterward, and they are given pain medication for it. You might have some swelling in the scalp and around the eye during the healing process. This will get better with time.
  • Endovascular repair. To repair the aneurysm, the surgeon will place metallic coils or a metallic mesh basket inside of the aneurysm. Sometimes it’s repaired with a stent that redirects blood flow away from the aneurysm. Every aneurysm and every person is different. You’ll just stay in the hospital one night after the procedure.

If an aneurysm ruptures, it is almost always repaired with surgery to prevent another episode of bleeding. You can expect to be in the hospital for about two weeks. The doctors will want to monitor you since you will be at a high risk for delayed stroke complications.


There are no specific medications to make an aneurysm smaller or keep it from bursting. If your doctor suggests endovascular repair, you may be required to take blood thinners afterward to prevent clotting and stroke. These may include aspirin or prescription blood thinners such as clopidogrel (Plavix), prasugrel (Effient), or ticagrelor (Brilinta).

Ready to treat your brain aneurysm?

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Follow up

Follow-up depends on the type of brain aneurysm and treatment. If the aneurysm is small and the doctors decide to monitor it, they’ll probably suggest you get MRI or CT scans annually or every other year. Sometimes they will want to do a test called an angiogram—essentially an X-ray movie of blood flow in the brain—to get the most detailed picture possible.

If you have had treatment for an aneurysm, you’ll need follow-up to make sure it doesn’t grow back. This follow-up can include MRI scans, CT scans, or an angiogram.

What can cause a brain aneurysm?

Pro Tip

There are actually two new ways to treat aneurysms that have been approved by the FDA in recent years: flow diverting stents and intrasaccular flow diversion. —Dr. Walcott

Doctors don’t know what exactly causes a brain aneurysm, but they seem to be more common as we get older. That suggests that aneurysms develop over time, probably from a weakness in the wall of a blood vessel.

Since there is high pressure from blood flow inside your arteries (compared with lower pressure in veins), a small spot of weakness in the wall of an artery can make that area bulge out.

Risk factors

Researchers are still looking for answers about who is most at risk for a brain aneurysm, and who is at risk for having an aneurysm burst. Aneurysms are much more common in people who smoke cigarettes or have high blood pressure. Smoking raises blood pressure and high blood pressure puts more stress on the walls of your arteries.

But brain aneurysms do sometimes happen to people who don’t smoke and who have healthy blood pressure levels.

Brain aneurysms are also more commonly found in people with polycystic kidney disease. Very rarely, aneurysms can occur frequently in families, so there might be a genetic link.

Preventative tips

Doctors don’t know how to prevent a brain aneurysm. But they do know that cigarette smoking and high blood pressure are two of the biggest risk factors seen in research studies.

You can lower your risk of developing an aneurysm by quitting smoking and getting your blood pressure to a healthy level.

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Once your story receives approval from our editors, it will exist on Buoy as a helpful resource for others who may experience something similar.
The stories shared below are not written by Buoy employees. Buoy does not endorse any of the information in these stories. Whenever you have questions or concerns about a medical condition, you should always contact your doctor or a healthcare provider.
Dr. Le obtained his MD from Harvard Medical School and his BA from Harvard College. Before Buoy, his research focused on glioblastoma, a deadly form of brain cancer. Outside of work, Dr. Le enjoys cooking and struggling to run up-and-down the floor in an adult basketball league.

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