Carotid stenosis is the narrowing of the carotid artery in the neck. The narrowing is the result of the build-up of a plaque inside the carotid artery typically where it branches in the neck into its two major divisions. The build-up of plaque is associated with several risk factors such as smoking, hypertension, elevated cholesterol, diabetes and obesity. The most serious consequence of carotid stenosis is a stroke. A stroke results either when the narrowing in the carotid artery reduces blood flow to the brain below critical levels or when small pieces of the plaque (called emboli) become detached and flow up into the brain and clog a major artery. There are approximately 750,000 strokes per year in the United States and more than 150,000 patients die because of the stroke. Stroke is the third leading cause of death after coronary artery disease and cancer. It is believed that approximately half of strokes are due to narrowing of and emboli from the carotid arteries. Although we find many patients to have carotid stenosis after they have a stroke, many are found to have this problem before having a stroke. Currently, we can diagnose carotid stenosis by one of three tests: (1) Duplex sonogram of the neck, (2) MRI and MRA scan of the neck, or (3) angiogram or arteriogram of the carotid arteries. Often, we can hear turbulent flow over the carotid arteries when we listen with a stethoscope. We then obtain a test to assess the degree of carotid stenosis. If we find critical stenosis of the carotid artery, then we recommend treatment. When patients present with either a stroke or a transient ischemic attack (TIA or mini-stroke), we assess the degree of carotid stenosis and recommend treatment if we find critical stenosis. At Hopkins, we treat carotid stenosis by performing either a microsurgical carotid endarterectomy or endovascular angioplasty and stenting. Microsurgical carotid endarterectomy is the treatment of choice for most patients with critical carotid stenosis. During microsurgical carotid endarterectomy, we remove the plaque from the inside of the carotid artery and re-establish uninterrupted flow to the brain. Endovascular angioplasty and stenting is reserved for patients who cannot undergo surgery. During endovascular angioplasty and stenting, we introduce a balloon into the inside of the carotid artery, displace the plaque, and place a stent to reinforce the walls. Johns Hopkins has among the best results in the country for surgery for carotid stenosis, with a published rate of 0.8% mortality and 1.8% morbidity.