Extracranial carotid atherosclerotic occlusive disease due to carotid stenosis Prevalent site: the bifurcation of the common carotid artery, especially the dilated portion of the internal carotid artery, is an important factor in causing cerebral ischemic disease. Some patients with mild to moderate carotid stenosis in the early stage may have no clinical symptoms. For those who have clinical symptoms of cerebral ischemia associated with stenosis, it is called “symptomatic carotid stenosis”. Symptoms of ischemia due to carotid stenosis include ischemic stroke, dizziness, memory, disorientation, dark haze, tongue extension, and poor speech. There are two types of ischemic stroke attacks due to carotid stenosis. One type is a transient ischemic attack, which has a sudden onset and lasts for a short period of time, and can be without impairment of consciousness or with a brief loss of consciousness. Patients can report a sudden effect on some neurological function, such as weakness or numbness in one limb, or difficulty with speech or blackness in front of the eyes for a short period of time. It usually lasts for several minutes or hours, and often recovers completely within 24 hours without sequelae. However, the symptoms are recurrent, ranging from several times a day to once every few weeks, months or years. Another type of ischemic stroke attack due to carotid stenosis can cause persistent cerebral ischemia, which often starts during sleep and develops slightly more slowly, with symptoms peaking in about a few hours to 1 to 2 days, and neurological dysfunction usually does not return to normal completely, all with varying degrees of sequelae. Commonly used ancillary tests: carotid vascular ultrasound, CT arteriography (CTA), magnetic arteriography (MRA), or arteriography. Treatment of carotid artery stenosis: conservative treatment, carotid endarterectomy, carotid stenting. Conservative treatment is mainly to control the risk factors that can lead to atherosclerosis, including: controlling blood pressure, blood sugar, blood lipids, quitting smoking, adjusting the diet structure, proper exercise, and weight control. Pharmacological treatment mainly includes stabilization of atherosclerotic plaque and anti-platelet aggregation drugs. Statin lipid-lowering drugs and enteric aspirin are commonly used in clinical practice. Drug therapy can only stabilize the atherosclerotic plaque, minimize thrombosis and slow down the progression of atherosclerosis, thus reducing the occurrence of cerebral ischemic events, but cannot fundamentally remove the plaque or restore blood flow to the brain tissue. When a carotid plaque is found, the treatment plan depends on the size of the plaque, its hardness and softness, and the presence or absence of plaque rupture: small plaques, those that do not cause carotid stenosis and non-ulcerous plaques can be treated temporarily without surgery and should be followed up and observed, but anti-platelet drugs must be applied to prevent microthrombosis. When carotid artery stenosis is detected, appropriate treatment measures should be taken depending on the degree of stenosis. If the stenosis is less than 50%, it can be treated with thrombosis prevention drugs and surgery is not necessary; if the stenosis is 50% to 70%, it can be closely observed and treated with drugs if there are no clinical symptoms, and surgery should be performed if there are symptoms; if the stenosis is greater than 70%, the hemodynamics will be significantly affected and there is a high chance of cerebral infarction, so surgery should be performed. Surgical treatment mainly includes carotid endarterectomy and carotid stenting. Carotid endarterectomy is the only method that can remove atherosclerotic plaque and reestablish normal lumen and blood flow, and is the “gold standard” for treatment of carotid stenosis in the carotid segment.