An unruptured brain aneurysm is a bulging blood vessel in your brain that has not burst. It may pose serious health risks and is usually treated with surgery or medication.

Healthcare professionals often find unruptured brain aneurysms by chance during imaging for unrelated reasons since brain aneurysms often do not cause noticeable symptoms until they burst.

Surgery is the only potentially curative treatment for an aneurysm, but small aneurysms with a small risk of rupturing are often treated only with monitoring during regular follow-ups.

Large aneurysms at risk of rupturing are usually treated with endovascular coiling or a type of open brain surgery called neurosurgical clipping. Endovascular coiling involves repairing an aneurysm with a long tube inserted through a blood vessel to place a coil over the bulging blood vessel. Neurosurgical clipping involves placing clips over the damaged vessels.

Read on to learn more about unruptured brain aneurysms, including when they need treatment and how they’re usually treated.

Brain aneurysms occur in roughly 3.2% of people in the general population. The best treatment depends on the size of your aneurysm and the chances that it could rupture.

Observation

Your doctor may recommend active observation if your aneurysm is small and unlikely to rupture. Active observation involves having regular checkups with your doctor to monitor whether your aneurysm is changing.

Medication

If your doctor decides you don’t need surgery, they may recommend medications to lower your blood pressure and reduce pressure against your aneurysm.

Some early research suggests that eplerenone (Inspra) may help prevent the growth and rupture of small aneurysms.

Lifestyle changes

Along with medications, your doctor may recommend any of the following lifestyle changes to help lower your blood pressure, if they apply to you:

Surgery

Surgery is the only potentially curative procedure for a brain aneurysm to prevent a rupture before it happens. Ruptured brain aneurysms cause death at a high rate — about 25% of people who experience one die within 24 hours and 50% die within 3 months.

Surgeons can repair aneurysms through neurosurgical clipping or endovascular coiling.

Both surgical procedures come with a small risk of complications. It’s often not clear whether an unruptured aneurysm needs to be treated, and preventive treatment may lead to death in up to 5% of cases.

Neurosurgical clipping has a higher complication rate, but the risk of rupture seems to be slightly higher after endovascular coiling.

Neurosurgical clipping

During neurosurgical clipping, a surgeon removes a flap of your skull to access your brain. They then use tiny metal clips to clamp the aneurysm and keep it from rupturing.

Endovascular coiling

Endovascular coiling is a minimally invasive procedure that involves inserting a long tube into a blood vessel, often in your groin, and threading it through your bloodstream until it reaches your brain. Your surgeon then uses a tiny coil to seal the aneurysm.

The survival rate for an unruptured aneurysm depends on factors such as:

  • the exact location of your aneurysm
  • your overall health
  • the size of your aneurysm
  • whether your aneurysm is stable or continuing to grow

According to a 2022 research review, autopsy studies suggest that 50% to 80% of aneurysms remain unruptured throughout a person’s life.

A ruptured brain aneurysm can cause a hemorrhagic stroke, which is life threatening bleeding in your brain. And even if you survive a ruptured aneurysm, you might have permanent disabilities such as:

  • difficulty understanding or producing language
  • difficulties with movement
  • paralysis
  • trouble walking or moving
  • loss of sensation in certain body parts

The outlook for an unruptured brain aneurysm depends on its size. Small aneurysms might never cause any problems, and many people go their entire lives without a rupture. Aneurysms larger than about 1 inch across have about a 6% risk of rupturing each year.

Your doctor may not recommend neurosurgical clipping if they do not think you’re in good enough overall health to undergo such an invasive procedure. Endovascular coiling is less invasive and generally has lower complication rates.

If you’ve received an aneurysm diagnosis, it’s important to visit your doctor for all your scheduled follow-up appointments to make sure your aneurysm isn’t getting bigger over time.

Medical emergency

Call emergency medical services or go to the nearest emergency room if you have a brain aneurysm diagnosis and you experience:

What happens if an unruptured aneurysm is not treated?

Without treatment, an aneurysm has a risk of rupturing and causing a stroke. The risk of rupture is higher for larger aneurysms.

How fast do brain aneurysms grow?

The rate at which aneurysms develop varies significantly. Some aneurysms may stabilize, while others may continue to grow rapidly.

Surgery is the only potential way to cure an unruptured brain aneurysm. Surgery comes with a small risk of death or other serious complications, but the risk is much higher for aneurysms that rupture.

Not all aneurysms need treatment, and the decision of whether to surgically treat an aneurysm is often not clear. Your surgeon can best advise you on whether your aneurysm needs treatment or whether regular follow-ups may be enough.