Brain Aneurysm

A brain aneurysm is a balloon or bubble-like growth that typically develops where a major artery branches into smaller arteries, often at the base of the brain.

Aneurysms have the potential to leak or rupture, causing bleeding into the brain or the surrounding area called the subarachnoid space. This subarachnoid hemorrhage can cause a stroke, leading to brain damage or death.

About 3 percent to 5 percent of the American population is affected by a brain aneurysm. The condition most commonly affects adults between the ages of 35 to 60 years old, although children can develop aneurysms. Aneurysms affect women more frequently than men. They can develop from continuous wear and tear on the artery walls and can be caused by factors such as genetics, injury or infection

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At UCSF Medical Center, our Neurovascular Disease and Stroke Center is recognized as one of the world's leaders in diagnosing and treating brain aneurysms. We care for more than 300 aneurysm patients each year. Our team includes neurologists, neurosurgeons and neuroradiologists who are experts in a wide range of treatment approaches, including microsurgical techniques, skull base surgery and advanced therapies such as blocking the artery with platinum coils.

We also treat complex and "giant" aneurysms that cannot be treated with conventional surgery.

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Brain aneurysms typically don't cause symptoms until they leak or rupture, causing bleeding into the brain and are discovered during tests for other conditions. Even when they cause no symptoms, these aneurysms should be treated to prevent future ruptures.

The hallmark symptom of a ruptured aneurysm is a sudden and extremely severe headache that may occur with nausea, vomiting, stiff neck, impaired consciousness, seizures or coma.

Symptoms of an unruptured aneurysm may include:

  • Cranial nerve palsy or erratic muscle movements
  • Dilated pupils
  • Double vision
  • Localized headache
  • Pain above and behind the eye

A ruptured brain aneurysm is a very serious conditions that in some cases can be fatal. A quick and accurate diagnosis is essential for your recovery. Tests commonly used in the diagnosis of aneurysms include:

  • Cerebral Angiography — This test is commonly used to diagnose aneurysms. A special dye that can be seen on X-rays is injected into an artery that supplies blood to the brain. The dye flows through the brains blood vessels and can show any obstructions or leaks.
  • Magnetic Resonance Angiography (MRA) — Using a strong magnetic field, an MRI can generate a 3-D image of the brain and a detailed image of blood vessels that can be used to detect, diagnose and aid the treatment of aneurysms. The procedure is painless.
  • Computed Tomography (CT) Scan — With this test, X-ray beams create a 3-D image of the brain. A CT scan can detect bleeding in the artery after the aneurysm has burst.

Almost all brain aneurysms should be treated to prevent them from rupturing or repair ruptured aneurysms as quickly as possible and strengthen the arteries to prevent future ruptures.


The following are some of the surgical techniques used to treat aneurysms.

3-D Computer Modeling — This technique, first performed by neurosurgeons at UCSF Medical Center, is used for difficult to treat and rare aneurysms. It produces 3-D images of the aneurysm and blood flowing through the arteries to the aneurysm. Dye is injected into arteries to track blood flow. A computer superimposes that information over brain scans to compose a 3-D model of the aneurysm. Using a computer, surgeons can test if different surgical techniques would alter blood flow enough to ease "hot spots" of pressure inside the aneurysm.

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Reviewed by health care specialists at UCSF Medical Center.

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