Carotid artery stenosis is mostly due to narrowing of the carotid artery lumen resulting in inadequate blood supply to the brain, and its incidence is high. Some stenotic lesions may even progress to complete occlusive lesions. The main causes of carotid stenosis are atherosclerosis, aortitis, and fibromuscular dysplasia. Clinical symptoms: Carotid stenosis itself has no typical clinical manifestations and is often not easily detected. In the early stages, the clinical manifestations include sudden onset of numbness, hypesthesia or abnormal sensation, weakness of the upper or lower extremities, facial muscle paralysis and sudden darkening of one eye, etc. If it occurs in the dominant hemisphere of the brain, it may cause speech impairment. This symptom appears only for a few minutes or hours, but disappears completely within 24 hours, which is often referred to as “mini-stroke” or transient ischemia (TIA). In severe cases, the symptoms of cerebral infarction will appear, which may cause death or leave serious neurological dysfunction, such as hemiplegia, aphasia, hemianopia, sensory impairment, etc. In addition to hemiplegia and aphasia, vascular dementia may also occur in recurrent lacunar cerebral infarction. Auxiliary examination 1.Doppler ultrasound: It is the preferred non-invasive means of carotid artery examination, which is simple, safe and inexpensive. It can not only show the anatomical image of carotid artery and perform the morphological examination of plaque, such as distinguishing intraplaque hemorrhage and plaque ulcer, but also show the arterial blood flow, flow rate, flow direction and intra-arterial thrombus. 2.CTA or MRA: It can clearly show the three-dimensional morphology and structure of carotid artery and its branches, and it can reconstruct the intracranial artery image. MRA can accurately show the thrombotic plaque, the presence or absence of clotted aneurysm and intracranial artery, and CTA can find the calcified plaque of artery, which is helpful for diagnosis and determining the plan. Digital subtraction angiography (DSA): Still the “gold standard” for the diagnosis of carotid stenosis, DSA can provide detailed information on the location, extent and degree of lesions and the formation of side branches; help determine the nature of lesions such as ulcers, calcified lesions and thrombosis; and understand coexisting vascular lesions such as aneurysms and vascular malformations. The degree of internal carotid artery stenosis is divided into 4 levels: (1) mild stenosis, where the internal diameter of the artery is reduced by <30%; (2) moderate stenosis, where the internal diameter of the artery is reduced by 30% to 69%; (3) severe stenosis, where the internal diameter of the artery is reduced by 70% to 99%; and (4) complete occlusion. Treatment: The treatment of carotid stenosis aims to improve cerebral blood supply, correct or relieve the symptoms of cerebral ischemia, and prevent the occurrence of TIA and ischemic stroke. Treatment is based on the degree of carotid stenosis and the patient's symptoms, and includes medical treatment, surgical treatment and interventional treatment. Internal treatment: includes the following: weight reduction, smoking cessation, limiting alcohol consumption, antiplatelet aggregation therapy, improving symptoms of cerebral ischemia, and regular ultrasound examinations to monitor the changes of the disease dynamically. Surgical treatment: The standard surgical procedure is carotid endarterectomy (CE). Patients with carotid stenosis of 70% to 99% benefit significantly from surgery; patients with stenosis of 30% to 69% are initially considered not suitable for CE, but surgery is feasible if they have clear symptoms. Interventional treatment: Carotid percutaneous transluminal angioplasty (PTA) and carotid stenting are divided into carotid stenosis (70% to 99%) with ipsilateral symptoms of stenosis are suitable for stenting. At present, the technical success rate of carotid stenting is greater than 98%, the complication rate is 2%-6%, and the mortality rate is less than 1%, indicating that carotid stenting may be safe and effective in treating carotid stenosis.