Cerebral artery steal syndrome (STEALSYNDROME) is a condition in which severe stenosis and occlusion of the aortic arch and adjacent large arteries due to various causes results in a significant decrease in pressure in the distal cerebral artery of the stenosis, causing other adjacent cerebral arteries to siphon off blood flow to supply the lower pressure artery to compensate for its blood supply. Subclavian artery steal syndrome is one of these conditions. When the subclavian artery or the unnamed artery is narrowed or occluded on one side, it steals blood from the contralateral vertebral artery due to siphoning and enters the subclavian artery via the affected vertebral artery to supply the affected upper extremity, and symptoms of insufficient blood supply to the vertebrobasilar artery occur during the activities of the affected upper extremity, such as episodes of dizziness, visual rotation, diplopia, ataxia, dysarthria, dysphagia, syncope, etc. In severe cases, blood from the internal carotid artery may flow backwards through the posterior communicating artery, and the internal carotid artery system may appear. In severe cases, the blood of internal carotid artery may flow backwards through the posterior communicating artery, resulting in ischemic symptoms of internal carotid artery system, such as hemiparesis, profound sensory impairment and aphasia. Atherosclerosis is the most common cause, followed by atopic and nonspecific arteritis. The clinical diagnosis is based on the significant weakening or disappearance of arterial pulsation in the affected upper limb, low blood pressure of more than 20 mmHg compared with the healthy side, systolic murmur in the ipsilateral neck, narrowing or occlusion of blood vessels on ultrasonography, and movement of the affected limb may induce or aggravate the symptoms of insufficient blood supply to the vertebrobasilar artery, etc. The diagnosis can be confirmed by DSA examination, which reveals the backflow of the contrast medium into the affected vessel.