What is carotid stenosis?
Carotid stenosis is a gradual narrowing of the carotid arteries. These arteries are found in the neck, one on each side, and they supply the brain with blood. Healthy normal arteries are flexible and have smooth inner walls. As people age, hypertension, and other diseases like diabetes and elevated cholesterol, and activities like tobacco use, can cause minor injuries to the blood vessel wall, permitting plaque build up in the wall of the vessel. This process is known as atherosclerosis. Atherosclerotic plaque is made of cholesterol, fat, calcium, and inflammatory cells, and often involves clot formation. As time goes by plaque and clot can create narrowing of the inside diameter of the carotid artery, causing a blockage. Atherosclerosis also causes arteries to become rigid; a process often referred to as “hardening of the arteries.” Carotid stenosis, when severe can be a source of stroke, especially when clots form on carotid plaque and break off to close areteries supplying the brain with blood.
Carotid stenosis increases the risk of stroke three ways:
- Plaque deposits can become bigger and significantly narrow the artery and reduce blood flow to the brain. Eventually, plaque can completely block the artery.
- Plaque deposits can abrade and distort the artery wall; this will cause blood clots to develop and block blood flow to the brain.
- Plaque deposits can tear and separate and then travel downstream to embed in a smaller artery and block blood flow to the brain.
Symptoms of carotid stenosis
Many people with carotid stenosis don’t have any symptoms until the artery becomes significantly narrowed or a clot forms. Frequently, symptoms first emerge when the patient has a mini-stroke, also called a transient ischemic attack (TIA). TIAs are triggered when blood flow to the brain is temporarily disrupted and then returned. The symptoms normally last a couple of minutes to hours, and then resolve entirely, and the patient returns to normal. TIAs should not be disregarded; they are an indication that an ischemic stroke and permanent brain injury may be imminent. Symptoms of a TIA may include difficulty speaking, weakness or numbness in an arm or leg, a drooping face on one side, visual changes, or paralysis affecting one side of the body. If you or someone you know develops these symptoms, call 911 immediately, as they may represent an impending stroke.
Symptoms of a mini-stroke or a TIA may include:
- Difficulty speaking or understanding words
- Blindness, blurry or dim vision
- Weakness, numbness, or tingling in the face, arm, leg, or one side of the body
- Nausea or vomiting
- Trouble with balance or coordination
- Lose consciousness
- Abrupt confusion or loss of memory
Causes of carotid stenosis
Atherosclerosis is the chief cause of carotid artery disease. Frequently it starts in early adulthood, but in most cases it takes decades to cause symptoms. Some people have quickly advancing atherosclerosis in their thirties, others in their fifties or sixties. Atherosclerosis starts with damage to the inner wall of the artery caused by high blood pressure, and high cholesterol, diabetes, smoking. Other risk factors include:
- Coronary artery disease
- A family history of carotid stenosis.
- Advanced age
- Less often, carotid aneurysm and fibromuscular dysplasia can produce carotid stenosis.
Individuals who already have heart disease are at an increased risk for developing carotid stenosis. Normally, the coronary arteries become diseased a few years after the carotid arteries.
Who is affected?
People who more likely to be affected by carotid stenosis are the following:
- Older people – prior to age 75, men are more at risk than women.
- A person, who has high cholesterol.
- An individual with high blood pressure.
- Sedentary lifestyle.
- Smokers are eight times more likely to develop atherosclerosis than someone without these risk factors.
In excess of 500,000 new strokes occur in the U.S. each year and 20 to 30% are caused by carotid stenosis.
How is a diagnosis made?
Your physician will diagnose carotid artery disease based on a physical, your medical history and test results. Your doctor will perform a physical exam. He may listen to the carotid artery with a stethoscope in order to detect a swishing noise called a “bruit.” A bruit may be an indication of disorderly blood flow produced by atherosclerosis, blockage or a tortuous vessel. A few diagnostic tests may be performed to identify narrowing of the carotid arteries. Carotid stenosis is diagnosed by either a CT angiogram of the neck, a Doppler vascular ultrasound of the neck, magnetic resonance angiography or a cerebral/carotid angiogram.
Imaging can also show evidence of numerous small strokes. Doctors can generate a diagnosis of carotid stenosis if tests reveal diminished blood flow in one or both carotid arteries.
CT Angiogram (Computed Tomography Angiography), is a noninvasive X-ray that delivers comprehensive images of anatomical structures within the brain. A CT angiogram requires injecting a contrast agent into the blood stream so that the arteries of the brain can be ascertained. This type of procedure offers the best pictures of both blood vessels (through angiography) and soft tissues (through CT). It allows doctors to visualize the narrowed artery and to establish how much it has narrowed.
Doppler vascular ultrasound is a noninvasive test that utilizes reflected sound waves in order to evaluate blood flow through a vessel. The ultrasound probe is placed on the neck over the carotid arteries. This test will reveal how much blood is flowing through the artery and to what degree the artery has narrowed.
MRA (Magnetic Resonance Angiography) of the neck is similar to the CT angiogram. Contrast dye is injected through an IV to illuminate blood vessels in the neck.
Cerebral Angiogram is a minimally invasive test that uses X-rays and a contrast agent injected into the arteries through a catheter in the groin. It enables doctors to visualize all arteries in the brain.
Treatment for carotid stenosis.