Carotid Artery Disease
What is Carotid Artery Disease?
Carotid artery disease is a disease in which fatty deposits, called plaque, accumulate on the inner walls of the carotid arteries, typically where it branches in the neck into its two major divisions. The narrowing of the arteries due to the plaque buildup reduces blood flow to the brain and increases the risk of stroke. This can occur anywhere in the body’s blood vessels, but most commonly occurs in the main arteries of the neck going to the brain, called the carotid arteries. If plaque builds up in the arteries, the condition is called atherosclerosis. Carotid artery disease is usually caused by atherosclerosis but it can also be caused by dissection. Carotid artery disease can eventually cause the following types of obstruction:
- Cerebral thrombosis refers to a thrombus (blood clot) that develops at the clogged part of the vessel, blocking an artery to the brain and stopping blood flow.
- Cerebral embolism occurs when a piece of plaque or thrombus travels from its original site and blocks an artery downstream. The material that has moved is called an embolus. How much of the brain is damaged or affected depends on exactly how far downstream in the artery the blockage occurs.
- Arteries can sometimes tear or split into layers with bleeding in-between each layer due to trauma, simple manipulation of the neck, or spontaneous occurrence. Known as dissection, this process can block blood flow to the brain, lead to the formation of blood clots, and eventually result in a stroke. Dissections are often the main cause of stroke in individuals under 40 years of age.
Causes and Risk Factors
Healthy carotid arteries are smooth and flexible and provide a clear pathway of blood flow. However, factors that stress your arteries and increase the risk of injury, buildup of plaques, and disease include the following:
- Aging – with age arteries become less elastic and more prone to injury
- High blood pressure is an important risk factor for carotid artery disease. Excess pressure on the walls of your arteries can weaken them and leave them more vulnerable to damage.
- Smoking causes an increase in heart rate and blood pressure, due to the nicotine, which also can irritate the inner lining of arteries.
- Abnormal blood-fat levels. High levels of “bad” cholesterol and triglycerides encourage the accumulation of plaques.
- Diabetes affects not only the ability to handle glucose appropriately but also the ability to process fats efficiently, placing people with diabetes at a greater risk of high blood pressure and atherosclerosis.
- Obesity. Excess weight increases the chances of high blood pressure, atherosclerosis and diabetes.
- Heredity. Having a family history of atherosclerosis or coronary artery disease increases your risk of developing these conditions as well.
- Physical inactivity contributes to a number of conditions including high blood pressure, diabetes and obesity, thereby putting you at higher risk for atherosclerosis.
These risk factors tend to occur together, creating an even greater risk for carotid artery disease. For more in depth causes and risk factors please see stroke section.
Carotid artery disease doesn’t produce any warning signs or symptoms in the early stages. Most patients are unaware that they have carotid artery disease until it’s serious enough to deprive the brain of blood. At this point the patient develops signs and symptoms of a stroke or TIA (LINK TO STROKE section). These symptoms may include any of the following:
- Sudden numbness or weakness involving your face, arm or leg, typically on one side of your body.
- Inability to move one or more of your limbs
- Slurred or garbled speech or difficulty understanding others
- Sudden trouble seeing in one or both eyes
- Dizziness or loss of balance
- A sudden, severe headache with no known cause
If you experience any of these symptoms, you may be experiencing TIAs or a stroke. Seek immediate medical attention even if the symptoms only last only a short while. Make sure your family and friends know the signs and symptoms for stroke and understand that it is critical to act fast in the event of a stroke. See Stroke section for a more complete list of TIA and stroke symptoms.
If you have risk factors for carotid artery disease it is a good idea to discuss this with your primary care physician. They can order the correct tests to evaluate the health of your arteries and may recommend treatments and lifestyle changes to reduce your risks of stroke. If anything out of the ordinary shows up on your scan, you will then be referred to our office for a consult. If you are experiencing any symptoms, be sure to write them down, along with the date and time and how long these symptoms lasted. This will help the doctor determine how urgent your condition is.
The patient’s degree of carotid artery disease is initially diagnosed by a Magnetic resonance imaging (MRI) of the brain and magnetic resonance angiography (MRA) scan of the head and neck with NOVA. MRI produces images of body structures using magnetic fields and computer technology. These images clearly show various types of nerve tissue and clear pictures of the brain stem and posterior brain. MRI of the brain can also help to determine whether there are signs of prior mini-strokes (TIA’s). MRI shows the location and extent of brain injury in the same way that a CT would, however, the image produced by MRI is sharper and more detailed than a CT. This is what makes MRI the scan of choice when diagnosing small, deep injuries. MRA is a noninvasive study also conducted in a magnetic resonance imager. The only difference is that this study provides an image of the arteries in your head and neck and can help detect blockage and aneurysms. NOVA software is a flow analysis system that works with MRA to produce a 3D model of the vasculature, allowing the anatomy to be viewed from all angles. NOVA is the first system to offer fast, accurate, and non invasive determination of volumetric flow rates, velocity, waveforms, and flow direction. MRI and MRA with NOVA sequencing are almost always ordered when patients are suspected of stroke. Together these tests allow the physician to diagnose the problem and come up with the best treatment option. These are both noninvasive tests, although some patients may experience claustrophobia in the imager. It is important to let the office know if you are claustrophobic when they call to schedule your scan.
If the tests reveal a critical stenosis of the carotid artery, we recommend treatment. The physician may also recommend a diagnostic cerebral angiogram to further assess the degree of carotid stenosis. Please see Diagnostic Cerebral Angiogram for more information on this procedure.
Carotid duplex (carotid ultrasound) is an ultrasound procedure that can be done to help detect plaque, blood clots, or other problems with blood flow in the carotid arteries. A water-soluble gel is placed on the skin where the transducer (a handheld device that directs the high-frequency sound waves to the arteries being tested) is then placed. The gel helps transmit the sound to your skin surface. The ultrasound is turned on and images of the carotid arteries and pulse wave forms are obtained.
Treatment of carotid artery disease usually involves a combination of lifestyle changes, conservative management (medications) and, in some cases, surgery or a stenting procedure. Treatment aims to reduce the risk of stroke by controlling or removing plaque buildup and preventing blood clots. If a surgical approach is decided upon, we perform one of two procedures:
- Microsurgical Carotid endarterectomy is the surgical approach used to treat carotid stenosis and reduce the risk of a stroke. In carotid endarterectomy, the neurosurgeon accesses the artery through an incision in the neck. A measurement of the pressure inside the vessel is taken to evaluate the degree of blockage. The carotid is then clamped above and below the incision and a temporary shunt is inserted on either sides of the incision to maintain blood flow. Plaque lining the endothelium (inner layer of the artery) is removed, the incisions are repaired, and the shunt is taken out. This procedure continues to be a very safe and effective surgical approach, although there are patients whose risk factors make surgery difficult. All of these factors are carefully assessed by the doctor before proceeding.
- Endovascular angioplasty and stenting involves introducing a balloon angioplasty into the inside of the carotid artery, displacing the plaque, and placing a stent to reinforce the walls. Please see Neurointerventional Procedures (LINK) for more information about this procedure and the recovery process.
Recovery and Prevention
Despite treatment of carotid artery disease, re-stenosis can occur in less than two years following treatment and is usually not symptomatic. These re-grown plaques can be treated with angioplasty and stenting when stenosis exceeds 80%.
It is important to remember that carotid artery disease is a progressive disease and that, if left untreated, it has a stroke rate of 13% per year in people with symptoms and 2.2% per year in people without symptoms.
There are many preventative measures that patients can do to decrease their risks of stroke. These include:
- Quitting smoking
- Limiting alcohol consumption
- Maintaining good blood-sugar control (if diabetic)
- Lowering your cholesterol
- Taking medications as prescribed.