Brain aneurysm

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Brain aneurysm

Deciding whether to have brain aneurysm surgery

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Most brain aneurysms do not rupture (burst). But various factors increase the risk of a rupture, causing bleeding in the brain. Surgery can prevent this from happening, but is itself associated with risks. So it’s important to carefully consider the pros and cons of surgery before making a decision.

Brain aneurysms are often discovered by chance. A brain aneurysm is a small, sac-like bulge in a blood vessel in the brain. In most cases, these aneurysms don't cause any problems. But they can sometimes rupture without warning and cause life-threatening bleeding in the brain (a brain hemorrhage).

In about 3 out of 100 people with a brain aneurysm, the aneurysm ruptures within 5 years. This is only a rough estimate, though, because the risk of a rupture is influenced by many different factors. For example, the risk is higher if the aneurysm has particular characteristics or if you have certain other medical conditions. If you don't have any risk factors, your risk of a rupture is a lot lower. But the risk is higher in people who have a number of different risk factors, or any serious risk factors. Then the aneurysm may rupture in up to 15 out of 100 people.

There are surgical procedures that can prevent ruptures. They come with a risk of serious complications such as a stroke or paralysis, though. To determine whether surgery is a suitable option, doctors try to assess your individual risk of a rupture – as well as the likelihood that the surgery will be successful.

What increases the likelihood of rupture?

The bigger an aneurysm is, the more likely it is to rupture. But it's not possible to say for sure whether an aneurysm is “harmless” or “dangerous,” and even small aneurysms may sometimes rupture. Because of this, other risk factors should also be taken into account when deciding whether or not to have surgery for prevention. The risk of a rupture is considered to be higher if

  • the aneurysm grows over time,
  • it is located in a brain artery that supplies the back part of the brain,
  • it has an irregular shape, and
  • the person has more than one brain aneurysm.

Aside from the characteristics of the aneurysm itself, ruptures are more common in

  • people with high blood pressure,
  • smokers,
  • women,
  • people over the age of 70,
  • people who have already had a brain hemorrhage caused by an aneurysm, and
  • people with a family history of the condition. In other words, those with close relatives (such as brothers, sisters or parents) who have already had a ruptured aneurysm.

How can you lower your risk?

You can influence two of the risk factors for a ruptured aneurysm yourself: High blood pressure and smoking.

You can lower high blood pressure by changing your diet and losing weight, and by getting more exercise. There are also effective medications for high blood pressure.

If you smoke, it is a good idea to quit. Various things can help you quit smoking.

When is surgery recommended?

After a brain aneurysm is diagnosed, the issue usually turns to deciding whether or not surgery is needed. To make a decision, it's important to know how likely it is that the person's aneurysm will eventually rupture, and what risks and benefits are associated with preventive surgery in their specific case.

  • If the risk of a rupture is low, the potential risks associated with preventive surgery might outweigh the potential benefits.
  • In people whose risk of a rupture is high, on the other hand, this treatment could prevent life-threatening bleeding in the brain. For them, the potential benefits of surgery might outweigh the risks.

Whether an aneurysm will eventually rupture depends on many different factors. The risks associated with surgery vary from person to person too, depending on a number of factors such as your overall health. So it's important to see a doctor who is specialized in the treatment of brain aneurysms. They are best able to assess your personal risks. Suitable doctors may include specialists in neurology, neurosurgery and neuroradiology.

Brain aneurysm: What are your treatment options?

When deciding whether or not to have surgery, it's a good idea to find out about the pros and cons first. This decision aid can help here.

What happens if you decide not to have surgery?

If you don't have surgery for a brain aneurysm, doctors recommend that it is monitored. This involves having regular check-ups to see whether the aneurysm has changed. If the risk of a rupture increases, you and your doctor can consider preventive surgery again.

If you experience sudden symptoms like a very bad headache, it's important to call an ambulance immediately. Bleeding in the brain has to be treated quickly in a hospital.

Backes D, Rinkel GJ, Laban KG et al. Patient- and Aneurysm-Specific Risk Factors for Intracranial Aneurysm Growth: A Systematic Review and Meta-Analysis. Stroke 2016; 47(4): 951-957.

Brinjikji W, Zhu YQ, Lanzino G et al. Risk Factors for Growth of Intracranial Aneurysms: A Systematic Review and Meta-Analysis. AJNR Am J Neuroradiol 2016; 37(4): 615-620.

Etminan N, de Sousa DA, Tiseo C et al. European Stroke Organisation (ESO) guidelines on management of unruptured intracranial aneurysms. Eur Stroke J 2022; 7(3): V.

Hacke W. Neurologie. Berlin: Springer; 2016.

Han P, Jin D, Wei W et al. The prognostic effects of hemodynamic parameters on rupture of intracranial aneurysm: A systematic review and meta-analysis. Int J Surg 2021; 86: 15-23.

Kleinloog R, de Mul N, Verweij BH et al. Risk Factors for Intracranial Aneurysm Rupture: A Systematic Review. Neurosurgery 2018; 82(4): 431-440.

Malhotra A, Wu X, Forman HP et al. Growth and Rupture Risk of Small Unruptured Intracranial Aneurysms: A Systematic Review. Ann Intern Med 2017; 167(1): 26-33.

Meyers PM, Schumacher HC, Higashida RT et al. Indications for the Performance of Intracranial Endovascular Neurointerventional Procedures. Circulation 2009; 137: 2235-2249.

National Institute for Health and Care Excellence (NICE). Subarachnoid haemorrhage caused by a ruptured aneurysm: diagnosis and management (NICE guidelines; No. NG228). 2022.

Pontes FG, da Silva EM, Baptista-Silva JC et al. Treatments for unruptured intracranial aneurysms. Cochrane Database Syst Rev 2021; (5): CD013312.

Steiner T, Juvela S, Unterberg A et al. European Stroke Organization guidelines for the management of intracranial aneurysms and subarachnoid haemorrhage. Cerebrovasc Dis 2013; 35(2): 93-112.

IQWiG health information is written with the aim of helping people understand the advantages and disadvantages of the main treatment options and health care services.

Because IQWiG is a German institute, some of the information provided here is specific to the German health care system. The suitability of any of the described options in an individual case can be determined by talking to a doctor. informedhealth.org can provide support for talks with doctors and other medical professionals, but cannot replace them. We do not offer individual consultations.

Our information is based on the results of good-quality studies. It is written by a team of health care professionals, scientists and editors, and reviewed by external experts. You can find a detailed description of how our health information is produced and updated in our methods.

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Deciding whether to have brain aneurysm surgery

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Updated on April 27, 2026

Next planned update: 2029

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Institute for Quality and Efficiency in Health Care (IQWiG, Germany)

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