In its early stages, carotid artery disease often doesn't have symptoms. The condition might not be obvious until it's serious enough to deprive the brain of blood, causing a stroke or TIA.

Symptoms of a stroke or TIA include:

• Sudden numbness or weakness in the face or limbs, often on one side of the body.
• Sudden trouble speaking and understanding speech.
• Sudden trouble seeing in one or both eyes.
• Sudden dizziness or loss of balance.
• Sudden, severe headache with no known cause.

When to see a doctor

Seek emergency care for any symptoms of a stroke. Even if they last only a short while and then you feel OK, see a healthcare professional right away. You might have had a TIA. A TIA puts you at risk of a stroke.

Talk to your healthcare professional if you have risk factors for carotid artery disease, even if you don't have symptoms. Managing the risk factors might protect you from a stroke. Seeing a healthcare professional early increases your chances of finding carotid artery disease and getting treatment before a stroke occurs.

Carotid artery disease is caused by a buildup of fatty deposits, known as plaques, in the arteries that send blood to the brain. Plaques are clumps that include cholesterol, fat and blood cells that form in the artery. This process is called atherosclerosis.

Carotid arteries narrow when they are clogged with plaques. A clog in carotid arteries makes it hard for oxygen and nutrients to reach the brain.

Factors that increase the risk of carotid artery disease include:

• High blood pressure. Too much pressure on artery walls can weaken them and make them easier to damage.
• Tobacco use. Nicotine can irritate the inner lining of the arteries. Smoking also increases heart rate and blood pressure.
• Diabetes. Diabetes lowers the ability to process fats, creating a greater risk of high blood pressure and atherosclerosis.
• High blood-fat levels. High levels of low-density lipoprotein cholesterol and high levels of triglycerides, a blood fat, help the buildup of plaques.
• Family history. The risk of carotid artery disease is higher if a relative has atherosclerosis or coronary artery disease.
• Age. Arteries become less flexible and more likely to be injured with age.
• Obesity. Excess weight increases the chances of high blood pressure, atherosclerosis and diabetes. Eating a high-fat diet can contribute to obesity and increase the risk of carotid artery disease.
• Sleep apnea. Pauses in breathing at night might increase the risk of stroke.
• Lack of exercise. Not exercising leads to conditions that can damage the arteries, including high blood pressure, diabetes and obesity.

Carotid artery disease causes about 10% of strokes. A stroke is a medical emergency that can cause brain damage, muscle weakness and possibly death.

Carotid artery disease can lead to stroke through:

• Reduced blood flow. A carotid artery might get so narrow because of atherosclerosis that not enough blood reaches parts of the brain.
• Ruptured plaques. A piece of a plaque can break off and travel to smaller arteries in the brain. The piece of plaque can get stuck in one of these smaller arteries. This blockage cuts off blood supply to part of the brain.
• Blood clot blockage. Some plaques are prone to cracking and forming irregular surfaces on the artery wall. The body reacts as it does to an injury. It sends blood cells that help the clotting process to the area. The result can be a large clot that blocks or slows blood flow to the brain, causing a stroke.

These steps can help prevent carotid artery disease or keep it from getting worse:

• Don't smoke. Within a few years of quitting, a former smoker's risk of stroke is like a nonsmoker's.
• Maintain a healthy weight. Being overweight increases other risk factors, such as high blood pressure, cardiovascular disease, diabetes and sleep apnea.
• Eat a healthy diet. Focus on fruits and vegetables, whole grains and fish, nuts and legumes. Limit cholesterol and fat, especially saturated and trans fats.
• Limit salt. Too much salt can increase blood pressure in some people. Experts recommend that healthy adults eat less than 1,500 milligrams of salt a day.
• Exercise regularly. Exercise can lower blood pressure and improve the overall health of your blood vessels and heart. It also can increase high-density lipoprotein (HDL) cholesterol, called the "good" cholesterol. It also helps you lose weight, control diabetes and reduce stress.
• Limit or avoid alcohol. If you choose to drink alcohol, do so in moderation. For healthy adults, that means up to one drink a day for women and up to two drinks a day for men.
• Control illnesses. Managing conditions such as diabetes and high blood pressure helps protect arteries.

Diagnosis usually starts with a medical history and physical exam. The exam generally includes listening for a swooshing sound, known as bruit, over the carotid artery in the neck. A narrowed artery causes the sound. The next step might be a test of physical and mental abilities such as strength, memory and speech.

Imaging tests

These might include:

• Ultrasound. This looks at blood flow and pressure in the carotid arteries.
• CT and MRI. These can show if you've had a stroke or other issues.
• CT angiography or MR angiography. These give more information about blood flow in the carotid arteries. These scans make images of the neck and brain after a contrast dye is put into a blood vessel. The dye makes areas of the images stand out.

If these tests cannot determine the cause of your symptoms and carotid artery disease is suspected, you may need a more invasive test. Catheter cerebral angiography involves placing a long, thin tube called a catheter into an artery in the groin or wrist. The catheter is threaded to the brain using X-ray imaging. A dye is injected into the blood vessels of the brain to make them visible under X-ray imaging. This test may help identify the type of plaque clogging your arteries.

Your healthcare professional might refer you to a doctor who specializes in conditions of the brain and nervous system, known as a neurologist.

What you can do

Ask a friend or relative to go with you to your appointment to help you remember all the information you get.

Make a list of:

• Your symptoms, and when they began.
• All the medicines, vitamins and supplements you take, including doses.
• Key medical information, including other conditions you have and family history of heart attack and stroke.
• Questions to ask your health care provider.

Questions to ask your doctor

• What's the most likely cause of my symptoms?
• What tests do I need?
• What treatments do I need?
• What lifestyle changes do I need to make?

Ask all the questions you have.

What to expect from your doctor

Your healthcare professional is likely to ask you questions, such as:

• Have you had any stroke-like signs and symptoms, such as weakness on one side of your body, trouble speaking or sudden vision problems?
• Do you smoke?
• How much alcohol do you drink?
• Do you exercise regularly?
• What do you eat in a typical day?
• Do you have symptoms of sleep apnea?