Brain Aneurysm

(Cerebral Aneurysm; Intracranial Aneurysm; Intracerebral Aneurysm; Aneurysm, Brain; Aneurysm, Cerebral; Aneurysm, Intracranial; Aneurysm, Intracerebral)

How to Say It: brain an-your-ih-sym


A brain aneurysm is a bulge in a blood vessel in the brain. The bulge is filled with blood. It can put pressure on parts of the brain. The blood vessel can also burst and cause bleeding in the brain. Finding an aneurysm early can help prevent severe or fatal problems in some people.

Brain Aneurysm
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Brain aneurysms are caused by weakness in the walls of a brain artery. This may be due to aging, genes, and certain conditions.

Risk Factors

Brain aneurysms are more common in older adults and women. Other things that raise the risk are:


Symptoms may include:

  • Pain behind the eye
  • Numbness
  • Weakness
  • Changes in eyesight
  • Drooping eyelid
  • A large pupil (black area) in the eye
  • Problems speaking

A leaking or burst aneurysm may cause:

  • Headache
  • Nausea and vomiting
  • Stiff neck
  • Confusion or sleepiness
  • Loss of consciousness
  • Seizures


The doctor will ask about symptoms and past health. A physical exam will be done. Tests may include:


Treatment depends on the type, size, and site of the aneurysm. It also depends on the person's health.

If the aneurysm is not leaking or burst, options may be:

  • Watching for symptoms, leaking, and changes in the size of the aneurysm
  • Medicines to treat:
    • Any underlying conditions—and those that raise the risk of a burst
    • Symptoms of the aneurysm

Procedures may be done to prevent or treat a burst aneurysm. They include:

  • Endovascular procedures to block blood flow to the aneurysm, such as:
    • Embolization—Uses a threaded tube to place coils in the aneurysm
    • Flow diversion—Uses a threaded tube to place a stent outside the aneurysm
  • Microvascular clipping—Brain surgery to clip and cut off blood flow to the aneurysm

Therapy can help with physical function, speech, and coping—for those who had a burst aneurysm


A brain aneurysm cannot always be prevented. To help reduce the risk:

  • Control high blood pressure.
  • Do not smoke or drink too much alcohol.
  • Do not use illegal drugs.

Brain Aneurysm Foundation

National Institute of Neurological Disorders and Stroke


Brain Injury Canada

Heart and Stroke Foundation of Canada


Cerebral aneurysm. American Association of Neurological Surgeons website. Available at: Accessed September 6, 2021.

Cerebral aneurysms fact sheet. National Institute of Neurological Disorders and Stroke website. Available at: Accessed September 6, 2021.

Flow diversion on aneurysms with stents. Neurology and Neurosurgery—Johns Hopkins Medicine website. Available at: Accessed September 6, 2021.

Hu S, Yu N, et al. A meta-analysis of risk factors for the formation of de novo intracranial aneurysms. Neurosurgery. 2019;85(4):454-465.

Subarachnoid hemorrhage. EBSCO DynaMed website. Available at: Accessed September 6, 2021.

Last reviewed July 2021 by EBSCO Medical Review Board Nicole Meregian, PA  Last Updated: 9/6/2021