Definition and Overview
The carotid arteries are the two large blood vessels on each side of the neck that supply oxygenated blood to the head and the brain. Just like the blood vessels that supply oxygen to the heart, carotid arteries can also narrow (stenosis of carotid artery) when fatty substances and cholesterol build up inside them. When these arteries are obstructed, normal blood flow to the brain is interrupted, which significantly increases a person’s risk of stroke. Also referred to as a “brain attack”, a stroke occurs when blood flow to the brain is cut off leaving brain cells without oxygen. This results in patients losing certain abilities such as muscle control and memory. The severity of symptoms depends on whether the patient suffers from a transient ischemic attack (TIA) or major stroke.
TIA occurs when a clot briefly blocks the carotid artery causing minor problems such as temporary weakness of an arm or leg. A major stroke, on the other hand, is when blood flow to the brain is cut off for hours putting patients at risk of paralysis or permanently losing their ability to speak. They can also experience permanent brain damage unless they receive immediate treatment (within three to six hours from the onset of symptoms). Although some patients are able to recover completely from TIAs and major strokes, more than 75% of patients suffer from some type of disability for the rest of their lives.
Causes of the Condition
Stenosis of the carotid artery is caused by atherosclerosis, a disease characterised by plaque build up inside an artery. This results in low blood flow and prevents oxygen and other nutrients from reaching the brain. If the blood vessel is totally blocked (carotid artery occlusion), brain tissue will start to die and the patient will have a stroke.
Certain factors can increase the risk of developing occlusion and stenosis of carotid artery. These include:
Age – Arteries, in general, become more prone to injury with age
Diabetes and obesity – Both conditions place patients at a greater risk of high blood pressure, which causes the walls of arteries to weaken and more vulnerable to damage
Family history of carotid or coronary artery disease
High levels of triglycerides and bad cholesterol in the blood
Smoking – Nicotine irritates the inner lining of the artery
Carotid artery stenosis symptoms often do not appear until patients suffer from transient ischemic attack or a stroke, which causes the following symptoms:
Loss of balance or coordination
Severe headaches with no known cause
Sudden confusion or dizziness
Sudden memory problems
Sudden trouble understanding and speaking
Sudden trouble walking
Sudden vision problems
Sudden weakness or numbness of one side of the body
Although symptoms of carotid artery stenosis are not apparent during the initial stages of the condition, warning signs of a stroke, such as TIAS, should prompt patients to seek immediate medical attention. TIAS, also called mini-strokes, are temporary episodes of tingling, dizziness, headache, blurred vision, paralysis, and confusion that last between a few minutes and a couple of hours.
Who to See and Types of Treatments Available
Men and women who have an increased risk of stroke are encouraged to undergo periodic physical exams that allow doctors to find the disease before symptoms even appear. When diagnosed early, the condition can be treated with minimal to zero risks of temporary or permanent disabilities.
During a preventive check-up, doctors would normally place a stethoscope over the carotid artery to listen for a whooshing sound (bruit), which can give them an idea if blood flow is interrupted. Other diagnostic tools include:
Carotid ultrasound or sonography – A standard diagnostic test that estimates the degree of obstruction and measures the speed of blood flow in the carotid artery. It is non-invasive and uses sound waves to create images of the carotid arteries.
Magnetic resonance angiography (MRA) – An imaging test that uses magnetic field radio waves to evaluate blood vessels and helps identify abnormalities of the carotid artery.
Computerised tomography (CT) angiography – Another non-invasive imaging test that uses low levels of radiation to produce cross-sectional images of the carotid arteries. It can also produce images of the brain, which can help doctors identify areas of damage.
Carotid angiogram – Considered the gold standard for imaging of the carotid arteries because it provides the best information and carries a small risk of serious complications.
Carotid artery stenosis treatment depends on the extent of the disease and the patient’s overall health condition. Treatment may include conservative therapies and surgical procedures. Drugs, such as antihypertensives and diabetes medications, are prescribed to treat underlying risk factors. Meanwhile, procedures to treat carotid artery stenosis include:
Carotid endarterectomy – This carotid artery stenosis surgery removes plaque build up inside the artery to reduce the risk of stroke. A vascular surgeon performs this procedure if patients have a moderate blockage (50-79%) and are already experiencing symptoms of stroke. It is also recommended for the treatment of internal carotid artery stenosis and bilateral carotid artery stenosis or when both the carotid arteries have narrowed. This procedure is performed under either local or general anaesthesia and requires an incision in front of the neck to gain access to the carotid artery.
Carotid angioplasty – This is a less invasive procedure that uses a catheter with a small balloon on its tip. The catheter is inserted in the groin and threaded to the blocked artery under x-ray guidance. A contrast material is then injected to determine the location of the blockage. Once found, the balloon is inflated to push the plaques and widen the vessel. In some cases, a stent is used to support the repaired vessel to avoid it from weakening and causing problems in the future. This procedure is performed under local anaesthetic.
Patients who have undergone treatment for stenosis carotid artery must make certain lifestyle changes to minimise the risk of suffering from a stroke. They are advised to:
Stop smoking immediately
Maintain a healthy weight
Eat a variety of fruits and vegetables
Seek medical treatment for the management of chronic conditions such as diabetes and high blood pressure.
Bope ET, et al. Conn's Current Therapy. Philadelphia, Pa.: Saunders Elsevier; 2013. https://www.clinicalkey.com.
Morales-Volero SF, et al. Asymptomatic carotid artery stenosis: Time to rethink our therapeutic options? Neurosurgery Focus.