Understanding Carotid Artery Stenosis

Arteries are the blood vessels responsible for transporting oxygen- and nutrient-rich blood from the heart throughout the body. The carotid arteries are located on the right and left sides of the neck and carry blood to the brain, face, and neck. Each artery splits into an external and internal carotid artery. The internal carotid artery, specifically, supplies blood to the frontal lobe of the brain, the region instrumental in cognition, sensory and motor function, and personality.

Stenosis refers to the narrowing of a canal or vessel in the body. Carotid artery stenosis, then, is the narrowing of the carotid arteries. Stenosis restricts blood flow, in this case starving brain tissue of the oxygen and nutrients it needs to function and survive. This narrowing might eventually lead to a blockage in the artery, cutting off blood supply entirely.

Carotid artery stenosis is most often caused by atherosclerosis: the arteries are narrowed or blocked by the build-up of called plaque. Cholesterol, fat, and inflammatory cells combine to form this sticky substance, which adheres to the walls of the vessels and clogs the arteries, restricting blood flow to the brain.

Risk factors for the development of carotid artery stenosis are clearly defined. A family history of atherosclerosis increases a person's risk of developing the disease. Cigarette smoking, high blood pressure, diabetes, and obesity are the most common risk factors. High levels of low-density lipoprotein (LDL, or "bad" cholesterol) also puts a person at high risk for stenosis of the arteries.

Carotid artery stenosis is often asymptomatic and may go unnoticed until the disease progresses, particularly in the absence of family history or other risk factors. A doctor may hear bruits, abnormal blood flow sounds, through a stethoscope placed on the carotid arteries, and this can indicate obstructed blood flow caused by stenosis. A bruit, however, is often not a reliable indication of the disease. In some cases, doctors do not know to check for carotid artery stenosis until an individual experiences a transient ischemic attack or stroke.

The narrowing of the carotid arteries by stenosis may lead to a transient ischemic attack (TIA) or stroke. A TIA or mini-stroke results from a temporary blockage of blood flow to the brain.

Symptoms of a TIA include:

• Blurred vision
• Weakness or numbness on one side of the body
• Slurred speech
• Confusion

A TIA and stroke share symptoms, but stroke is a life-threatening event that occurs when the artery is blocked entirely. Stroke requires urgent medical intervention to open the blockage and prevent permanent tissue damage, long-term complications, or death. A TIA indicates a high risk for stroke, and diagnosing and treating carotid stenosis following the event is critical.

Carotid artery stenosis may be diagnosed following a TIA or stroke, the discovery of a bruit, or through the identification of risk factors. The most successful diagnostic tool is the carotid duplex ultrasound (CDU). In CDU, the doctor observes the arteries through high-frequency sound waves to identify narrowed or blocked areas. Carotid angiography, magnetic resonance angiogram, and computerized tomography angiogram are less common in diagnosing stenosis of the arteries.

Asymptomatic or minor stenosis of the carotid arteries is often manageable with drug therapy. The most common medicines prescribed are those used to prevent blood platelets from clustering together, to reduce the risk of blockage in the narrowed artery. The individual may also require drugs to treat the underlying risk factors for atherosclerosis and carotid stenosis. These include statins to lower cholesterol or medication to control blood pressure and blood sugar levels.

People with severe blockages or a high risk of stroke may require surgical intervention. These procedures include endarterectomy and stenting. In carotid endarterectomy, the surgeon removes plaque from the artery through an incision in the neck and vessel. In stenting, a catheter is guided into the artery and through the plaque build-up. A cylindrical, mesh tube called a stent is placed to widen the artery and prevent future narrowing. Though stenting is less invasive, endarterectomy is the preferred method of treatment.

Changes in lifestyle are critical in managing minor stenosis, avoiding severe blockages and surgical intervention, and preventing stroke. A diet low in saturated fats, cholesterol, and sodium is ideal, and exercise and weight management are vital. Doctors also advise those at risk to avoid alcohol and cigarettes. A healthy, active lifestyle can help prevent the development of carotid artery stenosis, particularly in those with a family history of the disease.