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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:

  • Genetic disorders - Inheritance plays a role in about 20 percent of aortic aneurysms. Hereditary conditions like Marfan syndrome and Ehlers-Danlos syndrome can weaken the walls of the arteries.
  • Congenital malformation - Some people are born with defects to the aorta, heart valves or brain arteries that make them susceptible to aneurysms.
  • Trauma - A blow to the head or chest can injure and weaken the arteries.
  • Atherosclerosis - In this chronic condition, fatty “plaque” builds up on the insides of the arteries, causing them to harden, narrow and weaken.
  • Infection - Syphilis, tuberculosis and other infections can attack and weaken the artery walls.
  • Vasculitis - In this autoimmune condition, the body’s own immune system attacks the blood vessels, causing damage and inflammation.
  • Lifestyle factors - Smoking, heavy drinking and cocaine use have all been linked to aneurysms.
  • Menopause - In women, dropping estrogen levels can weaken the arteries and increase the risk of 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

  • Pain in the abdomen, chest, back or scrotum, sometimes described as “gnawing,” “steady,” or “deep”
  • Pulsating sensation in the abdomen.

Ruptured AAA Symptoms

  • Sudden, severe pain in the abdomen or low back that may spread to the groin, buttocks and legs
  • Nausea and vomiting
  • Signs of shock, including rapid heartbeat; cool, moist skin; light-headedness; confusion; anxiety; bluish lips and fingernails; and passing out.

Unruptured Thoracic Aortic Aneurysm (TAA) Symptoms

  • Pain in the jaw, neck, back or chest
  • Coughing
  • Hoarse voice
  • Difficulty swallowing
  • Shortness of breath, difficulty breathing.

Ruptured TAA Symptoms

  • Sudden, severe pain in the back, abdomen, chest or arms
  • Shock.

Symptoms of an Unruptured Brain Aneurysm

  • Loss of balance
  • Speech problems
  • Double or blurred vision
  • Dilated pupil
  • Numbness on one side of the face
  • Pain around or behind the eyes
  • Facial weakness or paralysis (may present as a drooping eyelid).

Symptoms of a Ruptured Brain Aneurysm

  • Sudden, severe headache
  • Blurred or double vision
  • Neck pain and stiffness
  • Sensitivity to light
  • Facial weakness or paralysis
  • Seizure
  • Shock.

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:

  • Physical exam - The physician checks blood pressure, feels the body for masses and listens to blood flow sounds.
  • Imaging tests - These are used to determine the size, shape and location of the aneurysm and to aid in treatment planning. The most common test is computed tomography (CT), which uses X-rays to visualize body structures in two-dimensional “slices.” Other useful tests include ultrasound, echocardiography and MRI. A contrast agent (dye) may be injected into the blood to improve clarity of the images.
  • Angiography - In this test, a flexible tube called a catheter is inserted through an artery in the groin and threaded to the site of the suspected aneurysm under X-ray guidance. Contrast agent is then injected through the catheter, and a special X-ray machine is used to visualize the blood and arteries.
  • Lumbar puncture - A physician inserts a needle through the skin into the hollow space around the spinal cord and draws a sample of cerebrospinal fluid. Blood in this fluid could indicate a ruptured brain aneurysm.


Treatment of aneurysm has several goals:

  • Prevent growth.
  • Prevent rupture or leaking.
  • Prevent or treat damage caused by the aneurysm to other body structures (for example, the nerves).
  • Preserve quality of life.

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:

  • Open surgery - An incision is made above the aneurysm site. The bulging portion of the blood vessel is removed and replaced by a section of tubing. In the case of a brain aneurysm, a clip is placed around the “stem” of the aneurysm to seal it off from the artery.
  • Endovascular surgery - The surgeon makes an incision into the artery at the groin and inserts a catheter. The catheter is threaded under X-ray guidance through the arteries to the location of the aneurysm. A tube called a stent is then passed through the catheter and placed inside the aneurysm. The ends of the stent are sealed to the healthy blood vessel walls on either side of the aneurysm. This “bypass” prevents rupture and promotes healthy blood flow.
  • Endovascular coiling - This is a specialized endovascular procedure that’s used to treat brain aneurysms. A catheter is inserted and guided through the aorta and into the brain arteries. A special coil in the catheter’s tip initiates a clotting reaction inside the “berry” part of the brain aneurysm. The clot fills the “berry” and seals off the opening through the “stem,” preventing rupture.

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:

  • Are male, between ages 65 and 75, with a history of smoking
  • Are between ages 65 to 75, and have at least two first-degree relatives who experienced an aneurysm
  • Have a congenital abnormality or genetic condition that increases the risk of aneurysms.

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

  • Quit smoking and drink in moderation, if at all.
  • Avoid recreational drugs.
  • Eat a healthy diet rich in whole grains, fruits, vegetables, lean meats and low-fat dairy.
  • Reduce your intake of saturated fat, trans fat, sodium (salt) and sugar.
  • Be physically active. Try to get at least 30 minutes of moderate activity on most days.
  • Get screened regularly for high blood pressure. If you know you have high blood pressure, work with your physician to manage the condition.


  • “Abdominal aortic aneurysm.” MedlinePlus, National Institutes of Health, 2014. Accessed June 3, 2014.
  • “Brain aneurysm.” Mayo Foundation for Medical Education and Research, 2014. Accessed June 3, 2014.
  • “Understanding: Brain Aneurysm Statistics and Facts.” Brain Aneurysm Foundation, 2014. Accessed June 3, 2014.
  • “What Is an Aneurysm?” National Heart, Lung and Blood Institute, 2011. Accessed June 2, 2014.
  • “When Blood Vessels Bulge: All About Aneurysms.” News In Health, National Institutes of Health, 2010. Accessed June 2, 2014.

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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.