Signs and Symptoms of Blood Clots in the Brain

Treatment should be provided within 4.5 hours of the first symptom

Blood clots in or on the brain can only be confirmed through an MRI or CT scan.

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Kimberly Goad,

AARP

En español

Published July 18, 2017

/ Updated January 09, 2024

Weakness or numbness in one arm, slurred speech, facial drooping on one side — these unmistakable signs serve as a clear warning that something is terribly wrong. Even experiencing just one of these symptoms could be a sign that you have a blood clot in the brain.

Understanding the gravity of these symptoms is crucial. Here’s what you need to know.

What is a blood clot in the brain?

“A blood clot in the brain is a serious condition that can cause stroke or death by blocking or bursting blood vessels,” says Deepak Gulati, MD, a vascular neurologist and medical director of telestroke services at The Ohio State University Wexner Medical Center. “It is commonly referred to as ischemic stroke, but a blood clot in the brain could also mean a hemorrhagic stroke, which is less common.”

An ischemic stroke, which accounts for around 85 percent of strokes, “happens when a blood clot blocks the blood vessel” resulting in lack of blood flow to the brain, whereas during a hemorrhagic stroke, a blood vessel ruptures and leads to accumulation of blood inside the brain,” adds Gulati.

“The word ‘ischemic’ means lack of blood flow,” says Jayne Zhang, MD, assistant professor of neurology at Johns Hopkins Medicine. “As you can imagine, if there’s a blood clot blocking flow to the brain, then you have a lack of oxygen, and that part of the brain dies. That’s when you end up with a stroke.”

There are two types of ischemic stroke: Cerebral thrombosis happens when a blood clot forms in one of the arteries supplying blood to the brain. The other kind, a cerebral embolism, is caused by a clot that forms elsewhere in the body, usually in the heart or neck arteries, and travels to a blood vessel within or leading to the brain.

Either way, the brain is deprived of what it needs to function.

Signs and symptoms

“Many blood clots send advance warning. Chest pain or shortness of breath can be symptoms of a blood clot in your lungs or heart; leg pain, swollen legs or a change in skin color may be symptoms of a deep vein blood clot,” says Zhang. Conversely, when there is a blood clot in the brain, patients usually develop sudden onset neurological deficits, she says.

How to know if you or someone you’re with is experiencing a stroke?

Remember B.E. F.A.S.T. (Balance, Eyes, Face, Arms, Speech, Time) for recognizing stroke symptoms:

Balance: Do you have a loss of balance or feel dizzy? Are you walking differently?
Eyes: Are you able to see out of both eyes? Take note of any sudden vision loss, blurry or double vision.
Face Drooping: Is your smile uneven? Weakness or numbness in the face — especially on one side of the body — are all signs of a stroke.
Arm Weakness: Try to raise both arms. Does one drift downward?
Speech Difficulty: Do you suddenly sound as if you’ve got a mouthful of cotton when you speak? Trouble talking, confusion and understanding speech are all tip-offs that you may be having a stroke and “that the part of the brain that controls these functions is compromised due to a blood clot that’s formed,” says Zhang.
Time to call 911: In the same way time is of the essence with a heart attack, the same goes with a stroke, often called a brain attack. “There is a precious window of four and a half hours” to receive treatment, says Zhang. “If you get to the hospital within that window, you may qualify for a clot-busting medicine that could make the symptoms of the stroke better or go away completely,” she says. That’s why the phrase “time lost is brain lost” holds great significance. On average, 1.9 million brain cells die every minute that a stroke goes untreated, according to the American Stroke Association.

Other symptoms of a blood clot-induced stroke include a sudden and severe headache, trouble seeing, dizziness and a loss of balance or coordination that’s bad enough to affect walking.

Diagnosis and testing

A lot happens within that 4.5-hour time frame, which starts with the first symptom.

“When someone who’s potentially having a stroke comes to the ER, we first do an assessment of the symptoms and get a medical history of the patient,” says Zhang. “A bedside neurological exam follows to find out which blood vessel may be blocked and why they’re having symptoms.”

CT (computed tomography) and MRI (magnetic resonance imaging) scans will then confirm the diagnosis. Both offer a picture of the brain showing the location of the stroke and the extent of damage, but an MRI is more detailed.

Treatment options

The body will naturally absorb a blood clot on its own, but it takes days to weeks for it to do so, says Zhang. However, two treatments speed up the process considerably.

One, a clot-busting drug called tissue plasminogen activator (tPA), treats ischemic stroke by doing exactly as its name suggests: It breaks up the clot that’s stopping blood flow to the brain. To be considered a good candidate for tPA, you must receive treatment within 4.5 hours of the onset of stroke symptoms.

Outside that window, depending on the size and location of the blood clot, you may qualify for what’s known as a mechanical thrombectomy. In this procedure, doctors thread a catheter through an artery in the groin up to the blocked artery in the brain to grab the clot and retrieve it.

Both treatments have dramatically changed what life after stroke looks like. “It used to be much worse before the advent of the treatments we now have,” says Zhang. “Unless it’s a really big stroke where it ends up causing other organ damage, the survival rate for most strokes these days — if they come to the hospital in time and get the appropriate treatment — is over 90 percent.”

Recovery depends on a number of factors including “size, location and type of stroke,” says Gulati. “Most patients improve significantly in the first few weeks or months and then they continue to improve for up to one year.”

Video: Stroke of Discovery

Editor’s note: This article, originally published July 18, 2017, has been updated to reflect new reporting from Kimberly Goad.

Kimberly Goad is a New York-based journalist who has covered health for some of the nation’s top consumer publications. Her work has appeared in Women’s Health, Prevention, Health and Reader's Digest.