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Last Updated: Mar 1, 2019


An aneurysm is a balloon-like bulge in the wall of a blood vessel. It usually occurs in an artery, a type of blood vessel that carries oxygen-rich blood from the heart and lungs to the body.

The most common location for aneurysms is the aorta, the body’s largest artery. The aorta carries blood from the heart downward to the abdomen, pelvis and lower body before branching into each leg. About 75 percent of aortic aneurysms occur in its lower section and are known as abdominal aortic aneurysms (AAAs). Aneurysms in the upper part of the aorta are called thoracic aortic aneurysms (TAAs).

Aorta highlighted in an image of torso vasculature

Aneurysms can also affect the arteries that carry oxygen-rich blood to the brain. In appearance, brain aneurysms resemble a berry on a stem. About one person in 50 has a brain aneurysm, and in most cases, the condition doesn’t cause any health problems.

Aneurysms can also form in the arteries of the legs, neck, kidneys and even within the wall of the heart itself.

Most aneurysms develop slowly over months or years, though they can appear suddenly when an artery is damaged by trauma. As an aneurysm grows, it becomes more likely to rupture or leak. A ruptured aortic aneurysm can cause severe internal bleeding and rapid death due to blood loss. A ruptured brain aneurysm can bleed into the brain, causing a stroke. Hemorrhagic strokes damage brain cells, increase the pressure within the skull, and are likely to cause death or significant disability.

Blood clots, which tend to form around the aneurysm site, are another potential complication. A clot that breaks away from the artery wall can travel through the body and lodge in smaller arteries, causing a stroke, heart attack or pulmonary embolism.

In addition, large aneurysms can press on nearby nerves, causing pain, tingling or swelling.

Aneurysms are a significant public health problem. Ruptured AAAs kill about 14,000 Americans annually. About 27,000 Americans experience a ruptured brain aneurysm each year, and the majority of these cases result in death or disability.


The underlying cause of an aneurysm is a weak spot in the artery wall. Over time, repetitive pounding by the blood as it’s forced through the veins with each heartbeat causes the weak spot to bulge. The higher the person’s blood pressure, the more likely an aneurysm is to form.

Aneurysms impact men and women of all ages. Aortic aneurysms usually occur after age 65 and are more common in men. However, brain aneurysms are more common in women by a 3:2 ratio and usually occur between ages 30 and 60.

The following factors may contribute to the development of an aneurysm:


Many aneurysms, even very large ones, cause no outward symptoms. In fact, they’re often diagnosed by accident when a patient undergoes an imaging test for an unrelated condition.

When symptoms do occur, they differ based on location of the aneurysm as well as whether or not it has ruptured.

Unruptured Abdominal Aortic Aneurysm (AAA) Symptoms

Ruptured AAA Symptoms

Unruptured Thoracic Aortic Aneurysm (TAA) Symptoms

Ruptured TAA Symptoms

Symptoms of an Unruptured Brain Aneurysm

Symptoms of a Ruptured Brain Aneurysm

A ruptured aneurysm is a life-threatening emergency. Seek immediate medical attention if you experience sudden severe pain in the head, torso or abdomen.


When an aneurysm is suspected, patients may be referred to a surgeon for specialized diagnosis and treatment. The workup may include:


Treatment of aneurysm has several goals:

Treatment decisions are based on the aneurysm’s size, the probability of complications and the person’s overall health.

For small aneurysms with a low risk of rupture, the doctor and patient may agree to simply monitor the condition for while. The patient receives regular CT scans to check for growth or changes in the aneurysm. The patient may also be advised to avoid certain activities that can raise blood pressure, such as drinking caffeine or straining to lift a load.

Medication therapy can also be beneficial for people with aneurysms. Drugs called beta-blockers and calcium channel blockers can help to reduce blood pressure and relax the blood vessels. This makes the aneurysm less likely to grow or rupture.

For ruptured aneurysms (or those at risk for rupture), surgical repair many be necessary:

People who have experienced a brain hemorrhage may need additional surgery to relieve pressure inside the skull. This usually involves placement of a special catheter that drains excess fluid to an external collection bag or into the patient’s abdomen, where the body reabsorbs it.

The prognosis for aneurysm patients is generally good when the condition is diagnosed early, monitored and treated. However, ruptured aneurysms often have serious or fatal consequences. Only about 20 percent of patients survive rupture of an AAA. Ruptured brain aneurysms are fatal in about 40 percent of cases, and about two-thirds of survivors experience some form of permanent disability.


Aneurysms are most treatable when diagnosed early. Regular screenings aren’t recommended for everyone but may be appropriate for some at-risk people. Ask your doctor about screening if you:

Aneurysms aren’t always preventable, but you can take the following steps to promote the health of your blood vessels:


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Tina Shahian, PhD

Tina is a writer for Innerbody Research, where she has written a large body of informative guides about health conditions.


A communication specialist in life science and biotech subjects, Tina’s successful career is rooted in her ability to convey complex scientific topics to diverse audiences. Tina earned her PhD in Biochemistry from the University of California, San Francisco and her BS degree in Cell Biology from U.C. Davis. Tina Shahian’s Linkedin profile.


In her spare time, Tina enjoys drawing science-related cartoons.