Brain Aneurysm

Brain aneurysms can occur when areas of weakened arteries balloon under pressure. Arteries, which carry oxygen-rich blood and nutrients throughout the body, are structured to withstand the pressure caused by normal blood flow. However, they can become damaged as a result of hypertension, the condition when the force of blood pushing against an artery’s interior wall is consistently too high.

Usually located along the major arteries deep within the brain, aneurysms vary in shape and size, sometimes grow over time, and can rupture. The sudden rupture of an aneurysm, known as hemorrhagic stroke, leaks blood directly into the brain or into the space between the brain and the skull.

IMPORTANT NOTE: This overview is provided for informational purposes only and should not be used as a substitute for talking with your doctor. Be sure to talk with your doctor for a complete discussion of this condition as well as the benefits and risks of any treatment options.


Some aneurysms are quite large in size and may push on a nerve in the brain creating a “mass effect.” An upruptured aneurysm may cause symptoms such as blurring of vision and headaches prior to bleeding. However, most unruptured aneurysms are discovered by chance during routine imaging of the brain.

For hemorrhagic stroke, symptoms vary depending on the location of the bleed and the amount of brain tissue affected.

Symptoms may include:

  • Sudden tingling, weakness, numbness, or paralysis of the face, arm, or leg, particularly on one side of the body
  • Sudden, severe headache
  • Difficulty with swallowing or vision
  • Loss of balance or coordination
  • Difficulty understanding, speaking (slurring nonsensical speech), reading, or writing
  • Change in level of consciousness or alertness, marked by stupor, lethargy, sleepiness, or coma


Your doctor may:

  • Ask you or your family member about your risk factors, such as high blood pressure, smoking, heart disease, and a personal or family history of stroke.
  • Ask about your signs and symptoms and when they began.
  • Conduct a physical examination to assess your mental alertness and your coordination and balance. He or she may check for numbness or weakness in your face, arms, and legs; trouble speaking and seeing clearly; and confusion.

Your doctor may order one or more of the following tests:

  • Cerebral angiography , also called cerebral arteriography, uses an injection of a water-soluble dye, called a contrast agent, to highlight the affected area so that it can be seen on X-rays.
  • Computed tomography (CT scan) uses X-rays to take clear, detailed pictures of your brain.
  • Computed tomography angiography (CTA) uses a combination of CT scanning, special computer techniques, and dye injected into the blood to produce images of blood vessels.
  • Magnetic resonance imaging (MRI) uses magnetic fields and radio waves to create detailed images that can show subtle changes in neurological tissues.
  • Magnetic resonance angiography (MRA) can record the pattern and velocity of blood flow through vascular lesions as well as the flow of cerebrospinal fluid throughout the brain.
  • Transcranial Doppler ultrasound evaluates blood flow through the brain by directing high-frequency sound waves through the skull at particular arteries. The resulting sound wave signals that bounce back from blood cells are interpreted by a computer to make an image of the speed of blood flow.


Treatment for this condition must always be discussed with your doctor
for a full discussion of options, risks, benefits, and other information.

Small, unruptured aneurysms generally do not require treatment unless they grow, trigger symptoms, or rupture. Larger aneurysms may interfere with blood flow, preventing oxygen and nutrients from reaching other parts of the body. A ruptured aneurysm is considered a medical emergency and immediate treatment may be necessary.

Endovascular embolization is the primary endovascular procedure used to treat both unruptured and ruptured brain aneurysms. A minimally-invasive treatment, embolization blocks blood flow to problem areas. To reach an aneurysm, a catheter (tube) is inserted through an incision in the femoral artery at the groin and guided towards the brain. Fluoroscopy (a type of X-ray) is used to track the catheter through the arteries. Once in position, soft platinum metal coils are pushed through the tube and released into the enlarged space. The coils mechanically occlude (block) the space and induce clotting (embolization) to cut off blood flow to the affected site. Coils are very small and thin, ranging in size from about twice the width of a human hair (largest) to less than one hair’s width (smallest). The number of coils used depends on the size of the lesion.

Surgical clipping is an open surgical procedure in which blood flow to an aneurysm is cut off by placing a clip at its base.