Brain (Cerebral) Aneurysm: Symptoms, Causes, Treatment


A brain aneurysm is a bulge in a weak area of a blood vessel in or around your brain. The constant pressure of blood flow pushes the weakened section outward, creating a blister-like bump.

When blood rushes into this bulge, the aneurysm stretches even further. It’s similar to how a balloon gets thinner and is more likely to pop as it fills with air. If the aneurysm leaks or ruptures (bursts open), it causes bleeding in your brain. Sometimes it causes a hemorrhagic stroke, bleeding in or around the brain that can lead to brain damage and be fatal.

These aneurysms are also called cerebral aneurysms. Cerebral means in the brain.

brain (cerebral) aneurysm

How common are brain aneurysms?

Up to 6% of people in the U.S. have an aneurysm in their brain that isn’t bleeding (called an unruptured aneurysm). Ruptured brain aneurysms are rare. They occur in approximately 30,000 Americans a year.

Who gets brain aneurysms?

You’re more likely to develop a brain aneurysm if you:

  • Are female.
  • Are 40 to 60 years old.
  • Have a family history of aneurysms
  • Have a rare blood-vessel disorder like arterial dissection, fibromuscular dysplasia or cerebral arteritis.
  • Have a genetic disorder that affects connective tissue such as Ehlers-Danlos syndrome, Marfan syndrome, neurofibromatosis type 1 or Loeys-Dietz syndrome.
  • Have polycystic kidney disease.
  • Are born with brain aneurysm as a birth defect.

Are aneurysms hereditary?

Among first-degree relatives, if one person has a cerebral aneurysm it would be appropriate to have the rest of the family, children or siblings, checked out after a discussion with your primary care physician. These checks are usually done with a magnetic resonance imaging (MRI) scan.

Studies suggest the link may vary between 10% and 20%. But all have shown that doctors find that relatives of aneurysm patients occasionally have an aneurysm too. That risk becomes even more likely if you or your family members have other risk factors for cerebral aneurysms.

What causes brain aneurysms?

It’s not clear why a brain aneurysm forms. Researchers believe these factors irritate and weaken blood vessels:

  • Smoking.
  • Blood infection.
  • High blood pressure (hypertension).
  • Amphetamine and cocaine use.
  • Traumatic brain injury (often caused by car crashes).
  • Atherosclerosis (fatty buildup on blood-vessel walls).

When do brain aneurysms develop?

Brain aneurysms can form in people as young as 30, rarely even earlier, but they’re more likely after age 40.

What causes brain aneurysms to bleed?

Researchers haven’t discovered exactly what causes an aneurysm to leak or rupture, which causes bleeding in or around the brain. But anything that increases your blood pressure can be dangerous. Higher blood pressure makes blood push harder against blood vessel walls. Things that may increase blood pressure include:

  • Ongoing stress or a sudden burst of anger or other strong emotion.
  • Working hard to lift, carry or push something heavy like weights or furniture.
  • Known high blood pressure that is not treated appropriately with medications.

Are brain aneurysms painful?

Most people who have an unruptured brain aneurysm don’t even know it’s there. It usually doesn’t cause pain or any symptoms at all.

However, many smaller (not only larger) aneurysms are actually found when investigating causes of chronic headache. Researchers don't know for sure if headaches are directly related to an unruptured aneurysm. One thought is that the swollen blood vessel is pressing into the nerves and membranes/tissues around the brain, causing the headache.

A sudden, severe headache (sometimes called “thunderclap headache”) can be a sign of a ruptured aneurysm. Rarely, you can also have a headache that lasts for days or weeks from an aneurysm that’s leaking a small amount of blood. This type of lingering headache is called a sentinel headache. It’s a warning that the aneurysm is about to burst.

What are the symptoms of an unruptured brain aneurysm?

The most common signs of an intact aneurysm are headaches. Other signs may include:

  • Vision changes.
  • Enlarged (dilated) pupil, the black part of the eye.
  • Seizures.
  • Numbness or tingling on the head or face.
  • Pain above and behind the eye.
  • Neck pain.
  • Nausea and vomiting.

What are the symptoms of a ruptured brain aneurysm?

A brain aneurysm that is leaking or has burst open is life-threatening. It requires emergency medical treatment. People with a ruptured brain aneurysm often say the headache is the worst headache of their lives. The severe headache comes on suddenly and lasts for hours to days.

Besides a severe headache, you may have some of the same symptoms of an unruptured aneurysm (see list above). You might also have:

  • Stiff neck.
  • Drowsiness or even coma.
  • Mental confusion.
  • Dizziness or problems with your balance.
  • Difficulty speaking.
  • Weakness or no feeling in an arm or leg.
  • Heart attack.

How is a brain aneurysm detected?

To find out if you have a brain aneurysm, your healthcare provider will order an imaging test. These tests show the size, shape and location of brain aneurysms:

  • MRI (magnetic resonance imaging).
  • CT (computed tomography).
  • Diagnostic cerebral angiogram
  • MRA (magnetic resonance angiography).
  • CTA (computed tomography angiography).

Occasionally, a ruptured aneurysm may not show on the initial imaging test. If your symptoms point to a ruptured aneurysm, your doctor may order a lumbar puncture (spinal tap). This test shows whether there’s blood in the fluid surrounding your brain.

Who should get treatment for a brain aneurysm?

A leaking or ruptured brain aneurysm requires emergency surgery. But you might only find out about a brain aneurysm when you have an imaging test for an unrelated condition.

If you have a small brain aneurysm that isn’t causing symptoms, and you do not have other relevant risk factors, your healthcare provider may recommend not treating it. Instead, your provider will order regular imaging tests to rule out any change or growth over time. They will also recommend you quit smoking (if you are a smoker) and require that your blood pressure control is under control. You’ll need to get help right away if you develop symptoms, or aneurysm change/growth occurs on follow-up imaging.

If you have symptoms, positive risk factors, and/or the aneurysm is large, you and your healthcare provider will discuss the benefits, risks and alternatives of surgical and/or endovascular treatment. The decision depends on several factors, including but not limited to your:

  • Age
  • Overall health and your medical conditions
  • Aneurysm location, size and other characteristics
  • Vascular anatomy
  • Family history
  • Risk of a brain bleed (rupture)

How are brain aneurysms treated?

Surgery and/or endovascular therapy are the treatment for brain aneurysms, whether they are ruptured or unruptured.

Open surgical (microvascular) clipping

During this procedure, your surgeon cuts a small opening in your skull to access the aneurysm. Using a tiny microscope and instruments, your surgeon attaches a small metal clip at the base of the aneurysm to pinch it off. This blocks blood from flowing into the aneurysm. The surgery can stop a brain bleed or keep an intact aneurysm from breaking open. Recovery time is different for ruptured (several weeks to months) and unruptured (usually two to four weeks) aneurysms. This procedure is considered to be durable with a low recurrence rate.

Endovascular therapy (coil embolization, stenting, balloon remodeling, flow diversion, intraluminal web device)

For this procedure, your surgeon doesn’t need to create an opening in your skull. Instead, a doctor inserts a catheter (a flexible tube) in a blood vessel, usually in the groin or wrist, and threads it to your brain.

Through the catheter, your doctor places a ball of wires (it looks like a tiny ball of yarn), most often made of platinum, in the aneurysm, sometimes with the help of small stents or balloons. Recently another small device (called Web), which looks like a mesh ball, made of nickel titanium, also became available, and works in a similar fashion as coils. Both methods result in blood clot formation around and inside the wire ball or web device, and block blood flow into the aneurysm, reducing or eliminating the risk of rupture.

Another technique, called ‘flow diversion’ also involves weaving a catheter up a blood vessel from the groin or wrist to the brain. Then your doctor uses the catheter to place a mesh tube in the part of the blood vessel that contains the aneurysm. The mesh encourages or diverts the blood to flow over instead of into the aneurysm.

Your doctor will recommend the best treatment option(s) to you based on and tailored to your vascular anatomy, aneurysm size and location, and several other characteristics.

Just like with open surgery, recovery time can be several weeks to months for ruptured aneurysms. However, a much shorter recovery, only a few days, is expected for unruptured aneurysms treated with endovascular therapy. Depending on the specific endovascular method, some may have a low risk of aneurysm recurrence.

How can a brain aneurysm growth or new aneurysm formation be prevented?

Once an aneurysm is found, it is not expected to resolve on its own. However, aneurysm growth, change, risk of aneurysm rupture, or new aneurysm formation can be reduced by having a healthy lifestyle. Steps you can take include:

  • Quit smoking.
  • Exercise regularly (and moderately) without excessive heavy lifting.
  • Eat a balanced diet.
  • Get help for alcohol or drug use disorder and don’t use cocaine or other stimulant drugs.
  • Control high blood pressure with medications and lifestyle changes
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