1. What is Carotid Stenosis?
Carotid atherosclerosis is the build up of plaque in the arteries of the neck that supply the brain. It has been in the news a lot lately. In many recent studies of cholesterol lowering drugs the amount of plaque in the carotid artery has been used to measure the effectiveness of many cholesterol drugs. For years the carotid artery has been a target for medical treatment of atherosclerosis because the prevalence of stroke from carotid stenosis is very high. Patients with carotid stenosis will often present with stroke of mini-stroke (TIA). Symptoms may be severe as unilateral paralysis and language disturbances or as mild as transient visual loss. In rare cases syncope or loss of consciousness can be the first symptmom of carotid stenosis.
2. Detection of Carotid Stenosis
When a patient has a clinical syndrome like a stroke or TIA, the work up usually includes a carotid ultrasound. This study measures the speed of blood flowing through the neck vessels and can determine if a blockage is significant. Ultrasound can also see the amount of plaque and the quality of the plaque (calcified or soft). The gold standard for the detection of carotid stenosis is a cerebral angiogram. This is an invasive procedure and has a minor risk of stroke. In patients that have no symptoms this is less practical. These patients often undergo ultrasound because their doctor has heard a "bruit" in the carotid artery during an examination. A bruit is harsh, high pitched sound heard with the stethoscope over the carotids and is an integral part of a comprehensive physical exam. The severity of the bruit does not indicate the severity of the narrowing. In lieu of a conventional angiogram, MRI or CAT scanning can be used to perform a non-invaive angiogram as well but is somewhat less accurate.
3. Surgical Treatment of Carotid Stenosis
Treatment of carotid disease is often surgical. At this time carotid endarterectomy is probably the most effective and safe way to improve blood flow to the brain and prevent another stroke or TIA. The surgeon removes the plaque through an incision in the neck. During the procedure there is a small albeit real risk of stroke. There have been many large studies that demonstrate this is more effective when the degree of narrowing is in excess of 60% in patients without symptoms. In patients with carotid stenosis of 50% or more and stroke or TIA, endarterectomy is recommended.
4. Non-Surgical Treatment of Carotid Stenosis
In the last decade the development of carotid stenting has progressed to be a viable option for many patients that are not good surgical candidates. The stents are inserted after an angioplasty pushes the plaque against the wall of the carotid artery. Stroke is a major risk during the procedure and has been its Achilles heel in comparison to endarterectomy. The use of specialized filters to catch debris has been effective in reducing the rate of significant stroke during stent procedures. At this time a fair amount of controversy exists as to if there is a true advantage of one procedure over the other. In certain groups medical treatment is more advantageous. This includes patients without symptoms and a narrowing less than 60%. Some data suggest that women often benefit less from surgery in comparison to men when they are asymptomatic. The cornerstone of medical treatment is aspirin to reduce clot formation at the site of narrowing. Plavix is used after stenting and at times instead of aspirin in some patients.
5. Implications of Carotid Stenosis
Patients with carotid stenosis have peripheral arterial disease (PAD). If they have a stroke or TIA they are at risk for another stroke until the blockage has been treated. Patients with PAD are at increased risk of suffering a heart attack. The atherosclerotic process is often present in multiple vascular beds including the legs, brain and heart. Data from large population based studies have shown approximately 60% of patients with stroke and atherosclerosis of the cerebral vessels have co-existing coronary artery disease. In the first 30 days after a stroke the majority of deaths are not related to another stroke but due to heart attack. In patients with carotid stenosis aggressive cholesterol lowering therapy, treatment of blood pressure and management of diabetes can reduce the risk of a future heart attack.
