Carotid Stenosis Health Article

Definition

Carotid stenosis is the medical description of the narrowing or constriction of the carotid artery. The artery is located in the neck, and the narrowing of the artery is caused by the buildup of plaque (fatty deposits). The process of atherosclerosis causes a hardening of the walls of the arteries and, in the case of atherosclerosis in the carotid artery, results in a carotid stenosis that reduces the flow of blood and nutrients to the brain.

Description

The carotid arteries run up the sides of the neck. They are vital arteries, and are a route of blood to the anterior part of the brain and, via branches, to the eyes, forehead, and nose. The deposition of plaque along the inner wall of an artery narrows its diameter. This makes the clogged artery less efficient in transporting blood. Plaque formation can become so severe that an artery is effectively blocked.

Carotid stenosis poses another danger when bits of the plaque dislodge. These pieces, which are referred to as blood clots or emboli, can move upward with the flow of blood towards the brain and can become lodged, blocking blood flow. This blockage interrupts the supply of nutrients and oxygen to the brain, and is one of the causes of cerebral vascular accidents, known as stroke. Carotid stenosis is a form of cerebral vascular disease and atherosclerosis.

Demographics

Stroke is the third leading cause of death in the United States after coronary artery disease and cancer, with approximately 750,000 strokes and more than 150,000 deaths occurring each year in the United States. Approximately 50% of these strokes are thought to be the result of carotid stenosis.

Causes and symptoms

The cause of carotid stenosis is the buildup of plaque on the inner wall of the carotid artery. The reduced blood flow to the brain and the blockage of other arteries following the release of emboli can cause a stroke. Increased risk of carotid stenosis is associated with smoking, hypertension, elevated levels of cholesterol, obesity, and a sedentary lifestyle. Some of these factors such as hypertension and cholesterol level may also be related to a person's physiology. Another risk factor is diabetes. Older, less active people are more prone to carotid stenosis. Additionally, the older a person is, the greater the risk posed by carotid stenosis.

Sometimes, prior to a major stroke, a person can be temporarily affected by the arterial blockage or release of a small embolus. The interrupted flow of blood to the brain, which can be very brief or last a few hours, does not persist longer than 24 hours. Symptoms of this transient event, called a transient ischemic attack (TIA), include weakness, as well as visual and speech difficulties. The exact symptoms of carotid stenosis depend on the area of the brain that is affected. Symptoms can also be absent, with the stenosis discovered only incidentally during a clinical examination.

In the event of a stroke, if the blocked blood flow is not restored, brain cells can die, causing permanent brain damage.

Diagnosis

Although not as accurate as other methods, a physician can listen to the pulsing of blood through the carotid artery by means of a stethoscope. The weaker pulse that is a result of stenosis will be evident in the form of altered sounds (bruits) as the blood flows past the area of disturbance.

Sometimes, carotid stenosis is suspected if a person has a transient malfunction of blood flow to the brain, or a TIA. A TIA can last anywhere from a few seconds to several hours. The temporary blockage of the artery can

cause a momentary loss of vision in one eye, a weak or numb sensation on one side of the body, slurred speech, or inability to speak. A TIA can be a warning to a physician of the potential presence of carotid stenosis.

Three main diagnostic tests aid in the diagnosis of carotid stenosis. The first is known as a duplex sonogram, or a carotid duplex. The procedure involves the use of highfrequency sound waves (ultrasound). The ultrasonic waves echo off of the carotid artery to produce a two-dimensional image on a monitor. If narrowing or obstruction of the carotid artery is present, it is often apparent in the image.

Another powerful imaging technique is magnetic resonance imaging (MRI) or magnetic resonance angiography (MRA). Both rely on the use of magnetism. Pulses of magnetic energy can be used to image the targeted area of the body, based on the interruption of the flow of the electrons in the magnetic field. This information is then converted to a visual image.

The third technique is known as an angiogram or arteriogram. An angiogram is an examination that utilizes x rays after a small tube (catheter) is inserted into the base of the carotid artery. An x-ray dye is then injected. The dye reveals the areas of the regions of the artery that are narrowed or blocked.