Carotid artery stenosis is a narrowing of the major blood vessels in your neck that carry oxygen-rich blood to your brain. This condition develops quietly over many years and can put you at serious risk of stroke if left unmanaged.

Understanding Carotid Artery Stenosis

Carotid artery stenosis happens when the large arteries on either side of your neck become narrowed or blocked. You have two carotid arteries—one on each side of your neck—and they play a vital role in keeping your brain healthy by delivering blood containing oxygen and nutrients. When these arteries are healthy, they work like clean, smooth pipes that allow blood to flow freely without any obstruction.^[1]

The narrowing is usually caused by a buildup of a substance called plaque, which is made up of fatty cholesterol deposits, calcium, and other materials found in the blood. This process of plaque accumulation on the inside walls of arteries is known as atherosclerosis. As plaque grows larger over time, it reduces the opening inside the artery where blood flows, making it harder for blood to reach your brain.^[4]

You can develop this narrowing in one carotid artery or both. The condition typically worsens gradually if not treated, and without proper medical care, it can lead to stroke—a medical emergency that can result in severe complications or even death. The plaque usually builds up at a specific spot where the artery divides, or “bifurcates,” into two branches: the internal carotid artery that supplies blood to the brain, and the external carotid artery that supplies the neck, face, thyroid gland, and scalp.^[9]

How Common Is This Condition

Carotid artery stenosis affects a notable portion of the population. The prevalence in the general population is estimated to be as high as 5%, meaning that up to one in twenty people may have some degree of narrowing in their carotid arteries.^[1]

This condition is closely linked to stroke, which ranks as the fifth leading cause of death according to the American Stroke Association. Carotid artery stenosis is something that typically develops over many years as people age. The risk for both this condition and stroke increases significantly with advancing age. Studies suggest that extracranial carotid atherosclerosis may account for up to 20% of ischemic strokes, making it a major contributor to stroke-related disability and death worldwide.^[10]

What Causes Carotid Artery Stenosis

The underlying cause of carotid artery stenosis is atherosclerosis—the gradual buildup of plaque inside the artery walls. This process begins when excess cholesterol in the blood starts to change the blood vessel. Specifically, low density lipoprotein (LDL) cholesterol, often called “bad cholesterol,” plays a heavy role in this process. The body sends inflammatory cells to help manage these changes, but over time, the LDL cholesterol begins to get trapped inside the artery wall and eventually sticks to the outside of the blood vessel. As this process continues year after year, plaque forms and grows, narrowing the artery’s opening.^[9]

In some cases, carotid artery stenosis can develop from causes other than typical atherosclerosis. Patients who have undergone radiation treatment for head and neck cancers may develop narrowing in their carotid arteries as a result of radiation damage to the vessel walls, rather than from plaque buildup. Additionally, certain inflammatory conditions affecting blood vessels can cause irregularities and narrowing in the carotid arteries.^[9]

Risk Factors That Increase Your Chances

Several factors can increase your chance of developing carotid artery stenosis over time. Some of these are within your control and can be changed through lifestyle modifications or medical treatment. Understanding these risk factors is important because some contribute to and compound other factors, creating a cycle that accelerates disease progression.^[1]

Smoking and using tobacco products is one of the most significant modifiable risk factors. Tobacco damages blood vessel walls and accelerates the buildup of plaque in arteries throughout your body, including the carotid arteries. Having obesity puts extra strain on your cardiovascular system and is often associated with other risk factors like high cholesterol and diabetes.^[1]

A sedentary lifestyle—meaning little to no regular physical activity—contributes to poor cardiovascular health and increases your risk for many conditions including carotid artery disease. High blood pressure, also called hypertension, damages artery walls over time and creates conditions that favor plaque formation. High cholesterol levels, especially high LDL cholesterol, provide the raw material that forms plaque deposits.^[1]

Diabetes affects how your body processes sugar and can damage blood vessels throughout your body, making plaque buildup more likely. Age is a non-modifiable risk factor—the older you get, the more time plaque has had to accumulate, and the more your arteries have been exposed to other risk factors. Studies have consistently shown that lifestyle aspects including smoking, along with comorbid conditions like hypertension, diabetes, and chronic kidney disease all play significant roles in the development of carotid stenosis.^[3]

Recognizing the Symptoms

One of the most concerning aspects of carotid artery stenosis is that it often causes no noticeable symptoms until the narrowing becomes severe or until a stroke occurs. Many people who have significant narrowing in their carotid arteries feel perfectly normal and have no idea anything is wrong. This is why the condition is sometimes discovered only after a person experiences a stroke or during a routine physical examination when a doctor detects an abnormal sound in the neck.^[5]

When carotid artery stenosis does cause symptoms, they typically appear as either a transient ischemic attack (TIA) or a full stroke. A TIA, often called a “mini-stroke,” occurs when blood flow to part of your brain is temporarily blocked. This temporary blockage happens when pieces of plaque or blood clots that form on the plaque break loose and travel up to the brain, where they lodge in a smaller artery. Unlike a full stroke, a TIA is brief and the blockage is only temporary, so it doesn’t cause permanent brain damage. However, experiencing a TIA is a serious warning sign that should never be ignored, as it often precedes an actual stroke.^[1]

A stroke, medically known as an ischemic stroke when caused by carotid stenosis, occurs when blood flow to a portion of your brain is cut off permanently. When this happens, brain cells begin to die within minutes due to lack of oxygen. The kind of stroke that usually results from carotid stenosis happens when pieces of plaque or blood clots travel from the narrowed carotid artery into the brain and block a smaller vessel there.^[8]

The symptoms of both TIA and stroke are similar and include several distinctive signs that you should recognize immediately. One side of your face may droop, making it difficult to smile evenly. You might experience slurred speech or have trouble forming words and communicating clearly with others. Some people lose vision in one eye, often described as having a dark shade come down over their field of vision—a condition called amaurosis fugax. You may lose feeling or sensation on one side of your body, or experience muscle weakness affecting one side more than the other. Additional symptoms can include sudden numbness or paralysis on one side of the body, blurred vision, sudden severe headache with no known cause, dizziness, loss of balance, confusion, and memory problems.^[1][5]

How Doctors Diagnose This Condition

Carotid artery stenosis is often diagnosed after someone has experienced symptoms of a stroke or TIA. When these symptoms occur, they prompt healthcare providers to thoroughly investigate for any blockages that might be restricting blood flow to the brain, which can lead to the discovery of carotid artery stenosis. However, sometimes the condition is discovered before symptoms occur during a routine physical examination.^[1]

Diagnosis usually starts with a medical history review and physical examination. During the physical exam, your doctor will typically use a stethoscope to listen for an abnormal swooshing sound called a bruit over your carotid artery in the neck. This distinctive sound is created by turbulent blood flow through a narrowed artery. The doctor may also perform tests to assess your physical and mental abilities, including checking your strength, memory, and speech.^[7]

Several imaging tests can be used to confirm the presence of carotid artery stenosis and determine its severity. Carotid ultrasound, including a specialized technique called Doppler ultrasound, uses sound waves to create real-time pictures of your arteries and can detect areas where blood flow is restricted. This is often the first imaging test performed because it is noninvasive, widely available, and very effective at showing narrowing in the carotid arteries.^[4]

Computed tomography angiography (CTA) uses a CT scanner to produce detailed views of the arteries in your neck after a contrast dye is injected into a blood vessel. This test is particularly useful for patients who have pacemakers or stents. Magnetic resonance angiography (MRA) provides similar information to CTA but without using ionizing radiation, making it another noninvasive option for examining the carotid arteries.^[4]

In cases where other tests cannot determine the cause of symptoms or when more detailed information is needed, doctors may recommend cerebral angiography, also known as intra-arterial digital subtraction angiography. This minimally invasive test involves guiding a thin tube called a catheter through an artery in the groin up to the area of interest near the brain. Contrast material is then injected through the catheter, and detailed X-ray images are captured. This test can help identify the exact type and characteristics of plaque that is clogging your arteries.^[4][7]

Prevention Strategies

Preventing carotid artery stenosis or slowing its progression involves addressing the risk factors that contribute to plaque buildup. Because many risk factors are modifiable, you have significant power to reduce your risk through lifestyle changes and medical management.^[11]

Making healthy dietary changes is fundamental to prevention. You should eat a healthy, low-fat diet rich in fruits and vegetables—fresh or frozen options are better than canned, which often contain added salt or sugar. Choose high-fiber foods such as whole-grain breads, pastas, cereals, and crackers. Opt for lean meats and skinless chicken and turkey, and try to eat fish twice a week, as fish contains beneficial fats that are good for your arteries. It’s equally important to cut back on saturated fat, cholesterol, and added salt and sugar in your diet.^[15]

Increasing your physical activity level is another crucial preventive measure. Before starting any exercise program, talk with your healthcare provider to make sure you are healthy enough to exercise safely. Walking is an easy and accessible way to add activity to your day—start with just 10 to 15 minutes daily if you’re not used to exercising. Gradually build up your activity level with a goal of reaching 150 minutes of moderate exercise each week.^[15]

If you smoke, quitting is one of the single most important steps you can take. Smoking dramatically increases your risk of developing carotid artery disease and having a stroke. Talk with your provider about quit-smoking programs and resources that can help you successfully stop using tobacco products.^[15]

Managing other health conditions is also essential for prevention. If you have high blood pressure, high cholesterol, or diabetes, working with your healthcare provider to keep these conditions well-controlled can significantly reduce your risk of developing carotid artery stenosis or prevent existing narrowing from getting worse. This often involves a combination of lifestyle modifications and medications.^[11]

How the Disease Affects Your Body

Understanding the physical and biological changes that occur with carotid artery stenosis helps explain why this condition is so dangerous. The process begins at the microscopic level within the artery walls and gradually progresses to cause significant changes in blood flow to the brain.^[3]

Atherosclerosis—the underlying process causing carotid stenosis—follows a predictable pattern. It begins with damage to the endothelium, which is the thin layer of cells lining the inside of your arteries. This damage can be caused by high blood pressure, smoking, high cholesterol, or other factors. Once the endothelium is damaged, LDL cholesterol particles begin to penetrate into the artery wall where they become trapped and oxidized. Your body recognizes this as abnormal and sends white blood cells called monocytes to the area to help clean up.^[3]

These monocytes transform into specialized cells called macrophages that engulf the oxidized cholesterol, becoming what scientists call “foam cells” because of their foamy appearance under a microscope. As more and more foam cells accumulate, along with smooth muscle cells from the artery wall, a plaque begins to form. This plaque has a lipid-filled core covered by a fibrous cap made of collagen and other proteins.^[3]

As the plaque grows larger over time, it narrows the lumen—the open channel inside the artery where blood flows. This narrowing changes the normal smooth flow of blood and can create turbulent flow patterns. The reduced opening means less blood can pass through to reach your brain. However, it’s interesting to note that in many cases, one carotid artery can be severely narrowed without causing symptoms because the brain has a remarkable ability to compensate. Blood vessels inside the brain connect with each other in a network, so blood from the unaffected carotid artery can supply both sides of the brain in many people—in fact, four out of five people only need one functioning carotid artery because of how these vessels join up inside the skull.^[9]

The real danger comes not just from the narrowing itself, but from the plaque’s potential to cause blood clots or to break apart. The surface of the plaque can become unstable and rupture, exposing material that triggers blood clotting. Platelets in your blood stick to the exposed plaque material and form clots. Small pieces of plaque or these blood clots can break free and travel up the artery into the brain. Once there, they can plug a smaller artery that the brain depends on, cutting off the blood supply to that region. When brain tissue doesn’t receive oxygen-rich blood, the cells begin to die rapidly—within minutes in many cases. This is what causes a stroke and the resulting permanent brain damage.^[8]