An aneurysm is a swelling in a blood vessel that occurs when its wall is weakened. Aneurysms can form in blood vessels in almost any part of the body, but among the most common types are brain aneurysms and aortic aneurysms (which affect the largest artery in the body – the aorta).

The greatest danger from an aneurysm is that it may rupture (burst). This may happen after many years of increasing pressure and thinning of the wall of the affected blood vessel, rather like a balloon that is over-inflated. When a brain aneurysm ruptures and bleeds (haemorrhages), it can cause a stroke. A ruptured aortic aneurysm can cause dangerous internal bleeding.


Symptoms will depend on where the aneurysm is and whether it has ruptured.

Brain aneurysms

Brain aneurysms that have not ruptured generally do not cause any symptoms, and may only be noticed when brain scans are done for other conditions. However, sometimes a growing aneurysm can put pressure on the surrounding brain tissue and nerves. This may cause symptoms such as:

  • headaches;
  • weakness or numbness affecting one side of the face;
  • vision problems such as double vision; or
  • pain behind or around one eye.

A ruptured aneurysm can cause a subarachnoid haemorrhage (when blood collects between the brain and the membranes that surround it) or, less often, an intracerebral haemorrhage (bleeding within the brain). The first symptom of a haemorrhage is usually a headache. The headache comes on suddenly, and is severe – many people have described it as ‘the worst headache they have ever had’. It is also described as a ‘thunderclap’ headache. Sometimes a brain aneurysm will leak a small amount of blood, causing a sudden headache. It is almost always followed by a more severe bleed several weeks later.

In addition to a sudden, severe headache, other symptoms of a brain haemorrhage include:

  • nausea and vomiting;
  • stiff neck;
  • photophobia (dislike or extreme sensitivity to lights);
  • weakness of arms or legs, or one side of the face;
  • problems with eyesight (such as double vision or blurry vision);
  • confusion;
  • seizures; and
  • loss of consciousness.

If you or someone you are with has any of these symptoms, call 000 for an ambulance. A brain haemorrhage is a medical emergency and needs urgent medical attention.

Aortic aneurysms

Aortic aneurysms (aneurysms that affect the aorta – the largest artery in the body) can occur anywhere along the length of this large blood vessel.

Abdominal aortic aneurysms (called AAAs) affect the lower aorta where it passes through the abdomen. People with abdominal aortic aneurysms may have pain in the abdomen (tummy), back or groin, but most people don’t notice any symptoms unless they burst. Sometimes aortic aneurysms are noticed during a physical examination or seen on imaging tests that are done for other reasons.

A ruptured abdominal aortic aneurysm is a life-threatening condition. Symptoms can include:

  • severe abdominal and/or back pain;
  • feeling light-headed;
  • fainting;
  • nausea; and
  • vomiting.

Thoracic aortic aneurysms affect the first part of the aorta where it emerges from the heart in the chest. They rarely cause symptoms unless they rupture or the wall of the artery tears (called dissection) – both of which are life-threatening.

Symptoms of a ruptured or dissecting thoracic aortic aneurysm can include:

  • sudden, severe pain in the chest, upper back and/or neck;
  • collapse;
  • difficulty breathing; and
  • difficulty swallowing.

If you have any of these symptoms, call 000 for an ambulance. A ruptured or dissecting aortic aneurysm is a medical emergency and needs urgent medical attention.

Other aneurysms

Popliteal aneurysms can be found at the back of the knee and femoral artery aneurysms in the groin. Aneurysms can also affect the arteries supplying blood to internal organs such as the spleen, bowel and kidneys. These types of aneurysms tend to be less likely to rupture than aortic aneurysms.

Who gets aneurysms?

Brain aneurysms can affect Australians of any age, however they are most commonly found in people aged 40 to 60 years. Women tend to be affected slightly more often than men. Overall, brain aneurysms are found in up to 5 per cent of people, but many of these people will not have a ruptured aneurysm.

Aortic aneurysms are more common in people older than 65 years, and men are affected more often than women. Smokers have a higher risk of developing aneurysms than non-smokers.


There are several reasons why people develop aneurysms.

  • Smoking is the main risk factor for abdominal aortic aneurysms and can also increase the risk of brain aneurysms.
  • High blood pressure increases the risk of getting an aneurysm.
  • Having a family history of aneurysms increases your risk. Certain genes can increase your risk of developing both aortic and brain aneurysms.
  • Atherosclerosis, a condition that affects blood vessels and results in a build-up of fatty deposits and reduced elasticity of arteries, can cause some aneurysms.
  • Inflammation of the walls of blood vessels due to problems with the immune system or (rarely) infection can lead to the development of aneurysms.
  • Having a certain heart valve abnormality – a bicuspid aortic valve – increases the risk of thoracic aortic aneurysm.
  • Connective tissue conditions that can weaken the walls of blood vessels (and cause aneurysms) include Ehlers-Danlos syndrome and Marfan syndrome. Polycystic kidney disease is an inherited condition that is associated with an increased risk of brain aneurysm.
  • Rarely, an injury can lead to the development of an aneurysm.
  • Drug abuse (especially ongoing cocaine or amphetamine abuse) is a risk factor for brain aneurysms.

Some types of aneurysm may be present at birth (congenital aneurysm).

Risk factors for aneurysm rupture

The risk of an aneurysm bursting is increased if you:

  • have untreated high blood pressure;
  • have a sudden rise in blood pressure due to straining or heavy lifting, or stress or other strong emotions;
  • drink alcohol in excess;
  • are a smoker; or
  • abuse illicit drugs such as cocaine.

The size of the aneurysm also affects whether it is more likely to rupture, with very small aneurysms having a low risk of rupture.


Aside from the main risk of rupture and bleeding, there are other complications associated with aneurysms. In general, complications will depend on where the aneurysm is and how big it is.

Blood clots can develop in aortic aneurysms. If blood clots detach from the aneurysm and travel through the bloodstream to other areas, they can affect the blood supply to those areas.

Tests and diagnosis

Your doctor will ask about your symptoms and perform a physical examination looking for signs of an aneurysm. Abdominal aortic aneurysms and some other aneurysms (such as popliteal and femoral aneurysms) can sometimes be felt as a ‘pulsatile mass’. This means that a doctor can feel a lump that expands in time with your pulse.

Imaging tests can confirm whether or not you have an aneurysm.

Tests for a brain aneurysm

In many cases, a brain aneurysm will not have any symptoms until it ruptures, causing a brain haemorrhage. A brain haemorrhage is an emergency that needs immediate medical attention in hospital. A brain scan (CT scan of the brain) will most likely be done to confirm the diagnosis and show the extent of the bleeding.

Doctors sometimes also recommend doing a test called a lumbar puncture to confirm a diagnosis of subarachnoid haemorrhage. This test involves taking a sample of cerebrospinal fluid (CSF) – the fluid that surrounds your brain and spinal cord – by inserting a small needle into the back (usually under local anaesthetic).

CT or MRI scans may be recommended for people with symptoms of an unruptured brain aneurysm. Sometimes a contrast material is injected into a vein before a CT scan to highlight blood flow in the brain – this type of scan is called CT angiography. Magnetic resonance angiography (MRA) is another type of scan that can give more detailed images of blood vessels.

An angiogram may be recommended to detect a small aneurysm or if other scans have not provided detailed images of an aneurysm. This test is more invasive than other imaging tests.

Tests for aortic aneurysms

An ultrasound examination of the abdomen is usually the first test recommended to detect an abdominal aortic aneurysm.

Thoracic aortic aneurysms may be detected by chest X-ray or echocardiogram (a special ultrasound of the heart and surrounding arteries).

Further imaging tests to outline the arteries – CT angiography or magnetic resonance angiography (MRA) – may be recommended to help work out the best treatment.


Treatment will depend on the location and size of the aneurysm and whether it has ruptured or is likely to rupture.

Monitoring and treating risk factors may be the only treatment needed for some people with small aneurysms that are not causing symptoms and thought to have a low risk of rupture. Regular scans to check the size of the aneurysm are usually recommended, as well as monitoring of blood pressure and other risk factors for rupture.

Treating brain aneurysms

Procedures can be performed to prevent a brain aneurysm from rupturing.

  • Surgical clipping involves a neurosurgeon putting a tiny metal clip around the aneurysm to stop blood flowing through it.
  • Endovascular coiling is a procedure where a thin tube is inserted into a blood vessel in the groin and then gently threaded through to the blood vessel in your head that has the aneurysm. Tiny, soft metal coils are then inserted into the aneurysm, blocking blood flow and stimulating the formation of a blood clot in the aneurysm. Endovascular coiling is less invasive than surgical clipping, but sometimes the procedure needs to be performed more than once.

These treatments are associated with some risks – your doctor can discuss the risks and benefits of treating an aneurysm to prevent bleeding. Your doctor will take into account your age, general health, family history and medical conditions that may increase the risk of rupture.

Treating brain haemorrhages

A ruptured brain aneurysm that causes a brain haemorrhage is a serious condition that needs immediate treatment in hospital.

Treatment will depend on:

  • the location of the bleeding;
  • the extent of possible damage to the brain; and
  • the general health of the person.

Treatment may include clipping or endovascular coiling of the aneurysm to prevent further bleeding.

Other treatments may be given to reduce brain swelling, optimise blood pressure and blood flow to the brain and prevent fluid build-up in the brain. Rehabilitation may be needed to help recovery if there is any permanent brain damage.

Treating aortic aneurysms

Treatment for aortic aneurysms depends on their size and the likelihood of them bursting or dissecting. Ongoing scans are usually recommended to monitor whether the aneurysm is expanding, and if so how quickly.

If the aneurysm is small and considered low risk, ongoing monitoring may be recommended.

To reduce the risk of the aneurysm expanding and rupturing, your doctor will also recommend you stop smoking if you are a smoker. Treating high cholesterol and high blood pressure are also usually recommended.

Aneurysms that are large, causing symptoms or expanding rapidly need to be treated. Treatment involves inserting a graft made of synthetic material to reinforce or replace the section of the aorta that has the aneurysm. This reduces the risk of rupture and can be done by traditional (open) surgery or endovascular surgery, where the graft is inserted into a large artery in the groin and then threaded through to the aorta under X-ray guidance.

A ruptured or dissecting aortic aneurysm is a life-threatening condition and requires emergency surgical treatment.


It may be possible to prevent the development of some types of aneurysms, and to slow down the growth of aneurysms that have already developed. Healthy eating, not smoking, and getting recommended amounts of physical activity are a good place to start.

You can also help reduce the risk of an aneurysm rupturing by:

  • stopping smoking;
  • treating high blood pressure; and
  • avoiding stimulant drugs such as cocaine.

High blood pressure can be treated with medicines, but your doctor will also recommend you manage stress, avoid heavy lifting and vigorous physical activity to keep your blood pressure under control.

Screening tests for aneurysms

It’s recommended that people with a family history of aneurysms or certain conditions that can increase your risk (such as Ehlers-Danlos syndrome, Marfan syndrome, neurofibromatosis type 1 and polycystic kidney disease) have screening tests. These are imaging tests to check whether there is an aneurysm that is not causing symptoms.

Screening for abdominal aortic aneurysms may also be recommended for men older than 65 who have been smokers.

Support groups

There is support available for people affected by aneurysms. Ask your doctor or search online to find a group that suits your needs.