Numbness in the left hand should be alert to the presence of radial nerve injury in the left hand, or suspected cervical spondylosis. 1. Radial nerve injury: patients with numbness in the left hand tiger’s mouth, highly suspicious of radial nerve injury, resulting in localized numbness or soreness in the left hand. If necessary, nerve exploration can be performed to anastomose the radial nerve injury. 2. Cervical spondylosis: left hand numbness also need to be alert to the patient is due to disc herniation or osteophytes leading to brachial plexus nerve compression, triggered by the arm area and the hand to appear such numbness symptoms. Patients with numbness in the left hand should be highly attentive, if the symptoms continue to be unrelieved or gradually aggravated, you need to consult a doctor as soon as possible to diagnose the cause of the disease, in order to carry out early treatment to avoid the development of the disease.