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Neurosciences and Behavioral Health Center

Cerebral Aneurysm

cerebral aneurysm, also called an intracranial aneurysm or brain aneurysm, is a bulging, weakened area in the wall of an artery in the brain. This results in an abnormal widening or ballooning that increases your risk for a rupture or bursting of the aneurysm.

A cerebral aneurysm generally occurs in an artery located in the front part of the brain that supplies oxygen-rich blood to the brain tissue. A normal artery wall consists of three layers. The aneurysm wall has only two layers.

Types of Cerebral Aneurysm

More than one aneurysm may be present at the same time.

  • Cerebral aneurysm — This saccular or berry aneurysm accounts for 90 percent of cerebral aneurysms
  • Fusiform aneurysms — A fusiform aneurysm bulges out on all sides and is generally associated with atherosclerosis
  • Dissecting aneurysms — May result from a tear in the inner layer of the artery wall, which causes blood to leak into the layers. This may cause a ballooning out on one side of the artery wall or it may block off or obstruct blood flow through the artery.

What Causes Cerebral Aneurysms?

While experts do not clearly understand the cause of cerebral aneurysms, two factors exist:

  • An abnormal degenerative (breaking down) change in the wall of an artery
  • The effects of pressure from the pulsations of blood being pumped forward through the arteries in the brain

Certain locations of an aneurysm may create greater pressure on the aneurysm, such as at a bifurcation or where the artery divides.

Risk Factors for Cerebral Aneurysms

Genetic risk factors may include:

  • Alpha-glucosidase deficiency
  • Alpha 1-antitrypsin deficiency
  • Arteriovenous malformation (AVM)
  • Coarctation of the aorta
  • Ehlers-Danlos syndrome (less common)
  • Family history of aneurysms
  • Female gender
  • Fibromuscular dysplasia
  • Hereditary hemorrhagic telangiectasia
  • Klinefelter syndrome
  • Noonan's syndrome
  • Polycystic kidney disease (PCKD)
  • Tuberous sclerosis

Risk factors developed after birth may include:

  • Age  greater than 40 years of age
  • Alcohol consumption, especially binge drinking
  • Atherosclerosis
  • Current cigarette use
  • Use of illicit drugs like cocaine or amphetamines
  • High blood pressure
  • Head injury
  • Infection

These risk factors do not necessarily cause the disease. Some people with one or more risk factors never develop the disease, while others develop the disease and have no known risk factors.

Symptoms of Cerebral Aneurysms

You might not know that you have a cerebral aneurysm until it ruptures. However, there may be symptoms that occur before an actual rupture when a small amount of blood leaks into the brain.

The symptoms of an unruptured cerebral aneurysm may include:

  • Headaches
  • Dizziness
  • Eye pain
  • Vision deficits

The first evidence of a cerebral aneurysm may be a subarachnoid hemorrhage (SAH), due to rupture of the aneurysm. Symptoms that may occur at the time of SAH may include:

  • Rapid onset of a terrible headache
  • Stiff neck
  • Nausea and vomiting
  • Changes in mental status, such as drowsiness
  • Pain in specific areas, such as the eyes
  • Dilated pupils
  • Loss of consciousness
  • High blood pressure
  • Loss of balance or coordination
  • Sensitivity to light
  • Back or leg pain
  • Problems with certain functions of the eyes, nose, tongue and/or ears

The symptoms of a cerebral aneurysm may resemble other problems or medical conditions. 


A cerebral aneurysm is often discovered after it has ruptured. Your doctor may discover the aneurysm by chance during diagnostic tests like a CT scan, MRI scan or angiography that are being done for other conditions.

Learn about cerebral aneurysm treatment options.


Content was created using EBSCO’s Health Library. Edits to original content made by Rector and Visitors of the University of Virginia. This information is not a substitute for professional medical advice.