Aneurysm: Causes, symptoms, and treatments

An aneurysm is the enlargement of an artery caused by weakness in the arterial wall. Often there are no symptoms, but a ruptured aneurysm can lead to fatal complications.

An aneurysm refers to a weakening of an artery wall that creates a bulge, or distention, of the artery.

Most aneurysms do not show symptoms and are not dangerous. However, at their most severe stage, some can rupture, leading to life-threatening internal bleeding.

The Centers for Disease Control and Prevention (CDC) advise that aortic aneurysms contribute to over 25,000 deaths in the United States (U.S.) each year.

Around 30,000 brain aneurysms rupture in the U.S. each year. An estimated 40 percent of these cases cause death within 24 hours.

Fast facts on aneurysms

Aneurysms affect a variety of arteries. The most significant aneurysms affect the arteries supplying the brain and the heart. An aortic aneurysm affects the body’s main artery.

The rupture of an aneurysm causes internal bleeding.

The risk of an aneurysm developing and rupturing varies between individuals. Smoking and high blood pressure are major risk factors for the development of an aneurysm.

Some types of aneurysm may need surgical treatment to prevent rupture. Doctors will only operate on others if they are life-threatening.


Aneurysm rupture
The rupture of an aneurysm can be fatal.

Aneurysms are classified by their location in the body. The arteries of the brain and heart are the two most common sites of a serious aneurysm.

The bulge can take two main shapes:

Fusiform aneurysms bulge all sides of a blood vessel

Saccular aneurysms bulge only on one side

The risk of rupture depends on the size of the bulge.

Aortic aneurysm

The aorta is the large artery that begins at the left ventricle of the heart and passes through the chest and abdominal cavities. The normal diameter of the aorta is between 2 and 3 centimeters (cm) but can bulge to beyond 5 cm with an aneurysm.

The most common aneurysm of the aorta is an abdominal aortic aneurysm (AAA). This occurs in the part of the aorta that runs through the abdomen. Without surgery, the annual survival rate for an AAA of over 6 cm is 20 percent.

AAA can rapidly become fatal, but those that survive the transfer to a hospital have a 50 percent chance of overall survival.

Less commonly, a thoracic aortic aneurysm (TAA) can affect the part of the aorta running through the chest. TAA has a survival rate of 56 percent without treatment and 85 percent following surgery. It is a rare condition, as only 25 percent of aortic aneurysms occur in the chest.

Cerebral aneurysm

Aneurysms of the arteries that supply the brain with blood are known as intracranial aneurysms. Due to their appearance, they are also known as “berry” aneurysms.

A ruptured aneurysm of the brain can be fatal within 24 hours. Forty percent of brain aneurysms are fatal, and around 66 percent of those who survive will experience a resulting neurological impairment or disability.

Ruptured cerebral aneurysms are the most common cause of a type of stroke known as subarachnoid hemorrhage (SAH).

Peripheral aneurysm

An aneurysm can also occur in a peripheral artery. Types of peripheral aneurysm include:

Popliteal aneurysm: This happens behind the knee. It is the most common peripheral aneurysm.

Splenic artery aneurysm: This type of aneurysm occurs near the spleen.

Mesenteric artery aneurysm: This affects the artery that transports blood to the intestines.

Femoral artery aneurysm: The femoral artery is in the groin.

Carotid artery aneurysm: This occurs in the neck.

Visceral aneurysm: This is a bulge of the arteries that supply blood to the bowel or kidneys.

Peripheral aneurysms are less likely to rupture than aortic aneurysms.


Not all cases of unruptured aneurysm need active treatment. When an aneurysm ruptures, however, emergency surgery is needed.

Aortic aneurysm treatment options

The doctor may monitor an unruptured aortic aneurysm, if no symptoms are evident. Medications and preventive measures may form part of conservative management, or they may accompany active surgical treatment.

A ruptured aneurysm needs emergency surgery. Without immediate repair, patients have a low chance of survival.

The decision to operate on an unruptured aneurysm in the aorta depends on a number of factors related to the individual patient and features of the aneurysm.

These include:

the age, general health, coexisting conditions and personal choice of the patient

the size of the aneurysm relative to its location in the thorax or abdomen, and the aneurysm’s rate of growth

the presence of chronic abdominal pain or risk of thromboembolism, as these may also necessitate surgery

A large or rapidly growing aortic aneurysm is more likely to need surgery. There are two options for surgery:

open surgery to fit a synthetic or stent graft

endovascular stent-graft surgery.

In endovascular surgery, the surgeon accesses the blood vessels through a small incision near the hip. Stent-graft surgery inserts an endovascular graft through this incision using a catheter. The graft is then positioned in the aorta to seal off the aneurysm.

In an open AAA repair, a large incision is made in the abdomen to expose the aorta. A graft can then be applied to repair the aneurysm.

Endovascular surgery for the repair of aortic aneurysms carries the following risks:

bleeding around the graft

bleeding before or after the procedure

blockage of the stent

nerve damage, resulting in weakness, pain or numbness in the leg

kidney failure

reduced blood supply to the legs, kidneys or other organs

erectile dysfunction

unsuccessful surgery that then needs further open surgery

slippage of the stent

Some of these complications, such as bleeding around the graft, will lead to further surgery.

Cerebral aneurysm treatment options

Cerebral aneurysm
A ruptured intracerebral aneurysm will usually need emergency surgery.

In the case of a brain aneurysm, the surgeon will normally operate only if there is a high risk of rupture. The potential risk of brain damage resulting from surgical complications is too great.

As for AAA, the likelihood of a rupture depends on the size and location of the aneurysm.

Instead of surgery, patients receive guidance on how to monitor and manage the risk factors for a ruptured brain aneurysm, for example, monitoring blood pressure.

If a ruptured cranial aneurysm results in a subarachnoid hemorrhage, surgery is likely. This is considered a medical emergency.

This procedure would aim to close off the ruptured artery in the hope of preventing another bleed.

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