Purpose of Brain Aneurysm Surgery

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Brain aneurysm surgery is considered a lifesaving procedure that is done to prevent or minimize the potential consequences of a brain aneurysm bleed. The operation can be done to repair an unruptured brain aneurysm so that it won’t bleed. It can also be done to remove blood and to prevent bleeding after a brain aneurysm has already ruptured.

Brain aneurysm surgery is a highly specialized neurosurgical procedure that involves extensive and careful planning, even when it is done as an emergency.

Brain aneurysm surgery prevents brain damage
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Diagnosis Related to Brain Aneurysm Surgery 

A brain aneurysm (also called a cerebral aneurysm) is a defect in an artery of the brain. The defect forms an outpouching in the arterial wall. Usually, the outpouching is fairly thin and weak. 

Blood can trickle out of the artery through a small tear in the aneurysm. Or the aneurysm can rupture, rapidly leaking blood into the brain. Any bleeding from an artery in the brain is dangerous, but rapid bleeding from a ruptured aneurysm is especially dangerous. 

An unruptured brain aneurysm can press on nearby regions of the brain. Brain aneurysms tend to form in the arteries of the circle of Willis, a vascular structure in the brain.

The symptoms of an unruptured brain aneurysm correspond to the location of nearby areas that are compressed or deprived of blood supply.

Brain aneurysms in the circle of Willis generally impair the function of cranial nerves on the brain stem. 

Common symptoms of unruptured brain aneurysms include:

  • Dizziness 
  • Double vision 
  • Headaches 
  • Seizures 
  • Weakness of the face, arm, or leg on one side of the body

These symptoms can come and go intermittently, or they can be persistent. Generally, with a growing brain aneurysm or a brain aneurysm that is tricking small amounts of blood, the symptoms tend to gradually worsen over time. And often, the symptoms suddenly become noticeable once the aneurysm reaches a certain point in which it compresses or irritates adjacent structures. 

A ruptured brain aneurysm can cause abrupt, intense effects. You can have a ruptured cerebral aneurysm if you’ve already been diagnosed with a brain aneurysm, or you could develop a ruptured aneurysm even if you never knew that you had the defect. The effects of a ruptured brain aneurysm are sudden and worsen rapidly. 

Symptoms of a ruptured brain aneurysm can include:

  • Intense, throbbing headache 
  • Difficulty concentrating 
  • Impaired speech 
  • Behavioral changes
  • Confusion 
  • Lethargy
  • Loss of consciousness 
  • Involuntary movements
  • Seizures 
  • Inability to move the face, arm, and/or leg on one or both sides of the body

A ruptured brain aneurysm can cause severe bleeding in the brain, profound edema (swelling), and may result in death before a person can reach medical help. 


The decision about whether to have surgery for treatment of a brain aneurysm involves a highly complex process that takes a number of factors into account. This is because a ruptured brain aneurysm can be deadly, but surgery is also risky.

The likelihood of rupture is weighed against the risk of surgery. And the possible outcomes differ for each person. You and your healthcare provider will discuss your situation as you make the decision about whether to proceed with surgery, and which type of surgery would be most beneficial and safest for you.

According to the American Heart Association, people who have cerebral aneurysms that are smaller than 7 millimeters (mm) in diameter and who don’t have a history of aneurysm bleed have a lower than 2.5% risk per year of having a ruptured aneurysm. And people whose aneurysms are growing have an 18.5% risk per year of having a ruptured aneurysm.

For people who have aneurysms that are larger than 12 mm, the reported rate of a bad outcome from surgical treatment ranges from 13.5% to 27.6%, and the risk of death from surgical treatment ranges from 0.7% to 3.5%.

Factors that your healthcare provider will discuss with you include:

  • Your overall health and ability to recover after surgery 
  • The size of your aneurysm
  • The location of your aneurysm
  • Whether your aneurysm has changed in shape or size 
  • The likelihood that your aneurysm will bleed
  • Whether your aneurysm is bleeding

Factors such as smoking, high blood pressure, atherosclerosis (hardened arteries), and young age increase the risk of an aneurysm rupture.

If you have a bleeding brain aneurysm, your likelihood of recovering from surgery is a major consideration in the decision about whether or not to have surgery, and in determining the optimal timing of surgery.

Tests and Labs

You would have diagnostic testing to identify a possible brain aneurysm if you develop symptoms and/or physical examination findings that raise a concern that you could have a ruptured or unruptured brain aneurysm. 

Physical Examination

Given that the symptoms of a ruptured brain aneurysm are so alarming, your physical examination would be prompt, and you would have your diagnostic tests on an emergency basis. 

Signs of a ruptured brain aneurysm include:

  • Extremely high or low blood pressure 
  • Stiff neck 
  • Respiratory distress 
  • Seizures 
  • Inability to communicate 
  • Unresponsiveness 

If you have symptoms of an unruptured brain aneurysm, your physical examination findings could be subtle.

Your healthcare provider might detect any of the following changes with an unruptured brain aneurysm: 

  • Uneven eye movements
  • Nystagmus (jerky eye movements)
  • Ptosis (a droopy eyelid)
  • Papilledema (swelling inside the eye)
  • Weakness or reflex changes on one side of the face or body

Further diagnostic testing is largely determined based on your symptoms and physical examination. 


A brain aneurysm can be detected with an angiogram, which is an imaging study that is done for visualization of the blood vessels in the brain. Computerized tomography angiogram (CTA), magnetic resonance angiogram (MRA) are commonly used tests for identifying cerebral aneurysms.

Digital subtraction angiography (DSA) is an interventional diagnostic test in which a catheter is inserted into an artery to visualize the blood vessel of concern.

DSA is considered the gold standard in diagnostic testing of cerebral aneurysms, but it is invasive and presents a risk of adverse effects.

Diagnostic Tests for Bleeding Aneurysms

A bleeding brain aneurysm can leak blood into the brain. Generally, acute blood is detected with a computerized tomography (CT) scan. A brain magnetic resonance imaging (MRI) study can be used to visualize blood in the brain after several hours, but it might not detect blood immediately. 

A lumbar puncture is an invasive test in which a sample of cerebrospinal fluid (CSF) is taken from around the spine for laboratory analysis. The fluid may contain blood if you have a ruptured brain aneurysm, but this test is not usually needed to confirm the diagnosis of a ruptured brain aneurysm if blood is detected on a brain CT scan. 

A Word From Verywell

Brain aneurysm surgery requires a substantial amount of planning. Due to its potential impact on consciousness, if you have a ruptured brain aneurysm, you might not be able to participate in the surgical decision making.

However, you will likely have many questions if you are considering whether or not you should have prophylactic surgery to repair an unruptured brain aneurysm. And if you and your healthcare provider decide that surgery is the right decision for you, then you will also discuss whether surgical clipping or endovascular coiling is the right procedure for you.

3 Sources
Verywell Health uses only high-quality sources, including peer-reviewed studies, to support the facts within our articles. Read our editorial process to learn more about how we fact-check and keep our content accurate, reliable, and trustworthy.
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  2. National Institute of Neurological Disorders and Stroke. Cerebral aneurysms fact sheet. March 13, 2020.

  3. Thompson BG, Brown RD Jr, Amin-Hanjani S, Broderick JP, Cockroft KM, Connolly ES Jr, Duckwiler GR, Harris CC, Howard VJ, Johnston SC, Meyers PM, Molyneux A, Ogilvy CS, Ringer AJ, Torner J, American Heart Association Stroke Council, Council on Cardiovascular and Stroke Nursing, Council on Epidemiology and Prevention, American Heart Association, American Stroke Association. Guidelines for the management of patients with unruptured intracranial aneurysms: A guideline for healthcare professionals from the American Heart Association/American Stroke Association. Stroke. 2015 Aug;46(8):2368-400. doi: 10.1161/STR.0000000000000070

By Heidi Moawad, MD
Heidi Moawad is a neurologist and expert in the field of brain health and neurological disorders. Dr. Moawad regularly writes and edits health and career content for medical books and publications.