Aneurysm: Definition, Causes & Symptoms

Instructor: Danielle Haak

Danielle has a PhD in Natural Resource Sciences and a MSc in Biological Sciences

You've probably heard of someone having an aneurysm, but what exactly does that mean? Read this lesson to learn what an aneurysm is, what causes it, and what the symptoms are.

What is an Aneurysm?

An aneurysm occurs when an artery bulges or balloons out in a particular area of the body. This is dangerous because, like a balloon, if an artery stretches too much it will eventually burst. And the outcome can be much more dangerous than when a balloon pops.

Aneurysms usually occur in the aorta, which is the main artery running from your heart to your chest cavity; however, they can also occur in the brain, heart, or anywhere else in the body. Aneurysms that burst in the brain are a type of stroke.

Normal conditions are shown in Panel A, while two types of aneurysms are shown in Panels B and C.

Causes of Aneurysms

So what causes an aneurysm to form in the first place? While the specific cause is often hard to pinpoint, there are some general characteristics that can increase the likelihood of an aneurysm forming. These include smoking, high blood pressure, a congenital condition where artery walls are compromised, a family history of aneurysms, age (they are more common over age 40), drug use, complications due to other medical conditions, tumors, or even injury. Smoking and high blood pressure also increase the likelihood of the aneurysm not just forming, but bursting as well.


Brain aneurysms have specific symptoms or warning signs, which can include nausea, severe headaches, a stiff or sore neck, blurred vision, difficulty seeing, sensitivity to light, loss of consciousness, seizures, or drooping eyelids.

An angiography image of a brain aneurysm.

Abdominal aneurysms have specific symptoms of their own. A patient may feel pressure in their abdomen or a deep, throbbing pain which usually manifests in the lower back. If the aneurysm bursts, the person will feel sharp pains and may go into shock without realizing what has happened. Unfortunately, there are often no symptoms of abdominal aneurysms; rather, they are commonly found during routine checkups or exams.

Treatment Options

If an aneurysm has already ruptured, surgery or an endovascular approach are required to completely seal off the burst artery so that it is unlikely to bleed again. If an aneurysm is found before it has ruptured, the consulting doctor will decide whether to continue monitoring its progress or take preventative actions.

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