Having one may lead to the other, but they’re not the same.
You might’ve heard someone casually say they were “about to have an aneurysm” because they were so stressed or upset during a meeting. You could imagine them at the conference table, clenching their teeth and holding their breath so tightly that their face would go crimson, until the force of their anger caused the arteries to burst beneath their skull.
It’s a provocative metaphor, but in reality, aneurysms have nothing to do with your mood or temporary stress. Plus, the word aneurysm refers not to the “burst,” but to the ballooning blood vessel itself. Clearly, this term is not well understood by the general public, despite its regular appearance in our conversations.
What Is an Aneurysm?
“Aneurysms are really the ballooning of the wall of an artery,” says Carolyn Brockington, MD, neurologist at Mount Sinai Hospital. These can occur throughout the body, but they most commonly happen in the brain and the aorta of the heart.
Brain aneurysms (also called cerebral aneurysms) affect about 30,000 Americans a year, according to NINDS, and may be caused by a range of factors, including genetics, cigarette smoking, or untreated high blood pressure. (Learn more about what high blood pressure does to your body.)
Blood vessels are lined with three layers of muscle, which help the arteries pump, contract, and dilate to assist with blood flow. The arteries form branches like a tree, and the aneurysms usually develop at the points where one vessel branches off, according to the American Stroke Association (ASA).
Aneurysms occur when there’s a weak spot in the artery wall. Because of pressure in the artery, the aneurysm starts to balloon with blood. Aneurysms can vary in size—usually between the size of a pencil eraser and a quarter—according to the National Institute of Neurological Disorders and Stroke (NINDS).
“People start off with maybe a small aneurysm,” says Dr. Brockington, “but if we see it growing, we get more concerned. The reason is [that] the balloon is filled with blood. The bigger the aneurysm, the bigger the balloon, the more likely maybe over time it might rupture.”
If the aneurysm ruptures, it can spill blood into the area around the brain. This is called a subarachnoid hemorrhage. A subarachnoid hemorrhage is a medical emergency that can cause permanent brain damage or death of not treated promptly.
How Is that Different Than a Stroke?
This gets a little tricky, because a brain aneurysm can actually result in a hemorrhagic stroke. During a hemorrhagic stroke, blood spills into the brain itself, which causes direct damage to the brain cells, according to ASA. Find out how stroke affects the brain here.
But stroke and aneurysm are not the same thing, and not every cerebral aneurysm will lead to a hemorrhagic stroke.
The majority of strokes are actually not caused by a “spilling” of the blood. Ischemic strokes account for 87 percent of strokes, according to ASA, and they’re caused by a blood clot that interrupts the blood flow to the brain. (Learn more about ischemic and hemorrhagic strokes here.)
The key difference here is that an aneurysm does not necessarily result in a stroke or cause brain damage—and some small aneurysms may not even bleed at all.
Since aneurysms often do not cause symptoms until they are large or rupturing, catching an aneurysm before it becomes a medical emergency requires you to know your risk factors, such as having high blood pressure or smoking.
If your risk of an aneurysm is above average, your doctor can use angiograms or CT scans to diagnose a potential aneurysm, according to the American Heart Association. Catching an aneurysm early allows you and your doctor to find the appropriate treatment and ensure the aneurysm isn’t enlarging.
Dr. Brockington is a neurologist and director of the Stroke Center at Mount Sinai St. Luke’s and Mount Sinai West Hospital in New York City.
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There is a difference between stroke and
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So aneurysms are really a ballooning
of the wall of an artery.
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The majority of strokes
are called ischemic stroke.
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ischemia means reduction in blood flow.
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That happens about 80% of the time.
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20% of the time is hemorrhagic stroke,
hemorrhage means bleeding.
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So in this case, instead of the blood
vessel being blocked, it ruptures,
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it spills or it opens up suddenly and
allows blood to spill into the brain.
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Stroke is really because one of the blood
vessels becomes blocked versus aneurysm
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is a weakening of the wall of the artery
causing a ballooning of that artery.
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Arteries have three muscle layers,
they have to constrict and
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dilate to push blood through.
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Aneurysms are congenital,
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meaning they start off with
a weakened wall around the artery.
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But the aneurysm or
balloon may grow over a time, and
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that's because of pressure
differences inside the artery.
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If we see it growing,
we get more concerned.
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The balloon is filled with blood, right?
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So the bigger the aneurysm,
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the bigger the balloon, the more likely
maybe over time it might rupture.
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And if the aneurysm bursts,
it produces bleeding in the brain but
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in a different way.
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We usually call that
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There are three layers of the brain,
called the meninges.
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One of the layers is called the arachnoid
layer, that's where the blood vessels and
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nerves sort of sit or live.
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And so if someone has an aneurysm,
you get subarachnoid hemorrhage, so
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bleeding sub, underneath, that layer.
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So that's why it's a different type of
injury, but it is bleeding in the brain.
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Cerebral aneurysms fact sheet. Bethesda, MD: National Institute of Neurological Disorders and Stroke. (Accessed on February 4, 2022 at https://www.ninds.nih.gov/Disorders/Patient-Caregiver-Education/Fact-Sheets/Cerebral-Aneurysms-Fact-Sheet.)
Hemorrhagic strokes (bleeds). Dallas, TX: American Heart Association. (Accessed on February 4, 2022 at http://www.strokeassociation.org/STROKEORG/AboutStroke/TypesofStroke/HemorrhagicBleeds/Hemorrhagic-Strokes-Bleeds_UCM_310940_Article.jsp#.W2si0JM-fVo.)
Ischemic strokes (clots). Dallas, TX: American Heart Association. (Accessed on February 4, 2022 at http://www.strokeassociation.org/STROKEORG/AboutStroke/TypesofStroke/IschemicClots/Ischemic-Strokes-Clots_UCM_310939_Article.jsp#.W2shG5M-fVo.)
Types of aneurysms. Dallas, TX: American Heart Association. (Accessed on February 4, 2022 at https://www.heart.org/en/health-topics/aortic-aneurysm/types-of-aneurysms.)
What is an aneurysm? Dallas, TX: American Heart Association. (Accessed on February 4, 2022 at https://www.heart.org/en/health-topics/aortic-aneurysm/what-is-an-aneurysm.)
What you should know about cerebral aneurysms. Dallas, TX: American Stroke Association, 2016. (Accessed on February 4, 2022 at http://www.strokeassociation.org/STROKEORG/AboutStroke/TypesofStroke/HemorrhagicBleeds/What-You-Should-Know-About-Cerebral-Aneurysms_UCM_310103_Article.jsp#.W2sAppM-fVo.)