Finger cyanosis or necrosis is an ischemic symptom of the upper extremity in the clinical manifestations of subclavian artery steal syndrome: the common ones are intermittent dyskinesia, upper extremity weakness, pain and sensory abnormalities in that order, and very rarely cause finger cyanosis or necrosis. The initial examination is usually performed by typical clinical manifestations. Three groups of symptoms are common clinically: 1) inadequate blood supply to the vertebrobasilar artery; 2) ischemia of the affected upper extremity; and 3) subclavian artery steal syndrome. The most common symptoms, such as vertigo, light paralysis of the limbs, sensory abnormalities, bilateral visual impairment, ataxia, diplopia, and syncope, are more common in men than in women. Rarely, intermittent claudication, dysphonia, dysphagia, tinnitus, convulsions, headache and mental disorders are also seen. A small number of patients may experience “tipping syndrome”, a sudden loss of muscle strength in the lower extremities and a fall, but there may be no impairment of consciousness and a rapid recovery. Some patients may have upper limb fatigue, aching, cold and abnormal sensation, etc. Very few of them may cause cyanosis or necrosis of the fingers. Most of the radial artery pulsations on the affected side are weak or absent, and some of the brachial or subclavian artery pulsations are also weak or absent. The blood pressure of the affected upper extremity is reduced, and the difference in systolic blood pressure between the upper extremities is usually more than 20 mmHg. A systolic murmur can be heard in the supraclavicular fossa.