Brain Aneurysm

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Our expert neurosurgery team is committed to providing the finest and most comprehensive patient care. For help finding a neurosurgeon, call 310-825-5111.

What is a Brain Aneurysm?


A brain aneurysm is a protruding bubble or sac on a blood vessel caused by a weak spot in the vessel wall that balloons out over time.

  • Brain Aneurysms have thin, weak walls and a tendency to rupture, causing bleeding into and around vital brain structures.
  • Causes include blood vessel defects at birth, a blockage or thinning of a blood vessel opening, infection or head trauma.
  • Diseases associated with brain aneurysms include polycystic kidney disease, fibromuscular dysplasia, arteriovenous malformations, connective tissue disorders, other family members with brain aneurysms, and Osler-Weber-Rendu syndrome.
  • Autopsy studies indicate a prevalence of approximately 5 percent. About half of brain aneurysms rupture.

Brain Aneurysm Symptoms

  • Most brain aneurysms are undetected until they rupture.
  • Some are discovered after they cause mass effect, or compression of the brain or sensitive structures such as cranial nerves.
  • Brain aneurysms also are discovered during diagnosis of small strokes and seizures.

Brain Aneurysm Diagnoses

  • A computed tomography (CT) scan can identify presence of a brain aneurysm that bleeds into the space surrounding the brain.
  • Cerebral angiography provides important information regarding the location of the brain aneurysm and the presence or absence of vasospasm, or the sudden constriction of an artery.

Brain Aneurysm Treatment

  • The optimal treatment depends upon the patient's history, physical examination, age and risk factors, and the characteristics of the brain aneurysm.
  • Ruptured brain aneurysms require immediate treatment to prevent another rupture. Rebleeding is very common, especially within the first two weeks after rupture, and usually more severe than the initial rupture.
  • Surgical treatment involves either surgical clipping or endovascular coiling to stop the flow of blood into the weakened artery.
  • Giant and complex aneurysms often require combined treatment using endovascular techniques in conjunction with extracranial-intracranial arterial bypass, or surgery under hypothermic circulatory arrest.
    • Endoscopic visualization around all sides of a brain aneurysm may be possible, alerting the surgeon to the hidden vessels.
    • Following aneurysm clipping, endoscopic evaluation may help to prevent incomplete aneurysm clipping.
    • On rare occasions, a brain aneurysm can be clipped solely with endoscopic visualization, limiting the size of a cranial incision and speeding recovery.
  • Postoperatively, transcranial Doppler and cerebral blood flow studies are available to check for the development of vasospasm. Severe, medically refractory vasospasm is treated using balloon dilation angioplasty, performed by the interventional neuroradiology team.

The Neuro-ICU cares for patients with all types of neurosurgical and neurological injuries, including stroke, brain hemorrhage, trauma and tumors. We work in close cooperation with your surgeon or medical doctor with whom you have had initial contact. Together with the surgeon or medical doctor, the Neuro-ICU attending physician and team members direct your family member's care while in the ICU. The Neuro-ICU team consists of the bedside nurses, nurse practitioners, physicians in specialty training (Fellows) and attending physicians. UCLA Neuro ICU Family Guide