Symptomatic stenosis (ICA, CA stenosis >70%, MCA, BA stenosis >50%) Type I stenosis: ischemia in the blood supply area of the stenotic vessel, with clinical manifestations of ischemia in the associated area. Type II stenosis: ischemia (blood theft) in the region of the blood supply of the collateral vessels caused by the stenosis, the blood supply area of the stenotic vessels is compensated, and a blood theft syndrome appears. Type III stenosis: mixed type. Each type is subdivided into three subtypes A, B and C, namely: Type A: no infarction in the corresponding area, or luminal infarction but no sequelae of neurological deficit, abnormal acetazolamide excitation test, and the patient is expected to benefit after revascularization. Type B: Small infarct in the corresponding area or combined with tandem stenosis of the distal vessels, or occlusion of the distal trunk, but the artery is still involved in the collateral blood supply of other stenosed vessels, and it is expected that the patient can partially benefit after revascularization. Type C: Large infarct in the corresponding area, with major stroke sequelae, or chronic occlusion of the distal trunk, and the artery is not involved in the collateral blood supply of other stenoses, the patient is not expected to benefit after revascularization.