The symptoms of numbness and pain in the left hand can be caused by many diseases clinically, depending mainly on the specific extent of the numbness, the common ones are as follows: 1. Nerve compression caused by neurogenic cervical spondylosis, most of which, in addition to hand numbness, will also have upper limb soreness as well as cervical discomfort or restricted movement. 2. ulnar neuritis, lesions at the elbow, because of the osteophytes or tissue hyperplasia there, resulting in The numbness of the skin of the 4th-5th finger and the weakening of the clamping force between these two fingers can be caused by the compression of the nerve by carpal tunnel syndrome. 3, the numbness of the skin of the 1st, 2nd and 3rd finger can be caused by the compression of the nerve by carpal tunnel syndrome, while the whole lesion is formed in the carpal joint area due to excessive strain and strain resulting in a smaller carpal tunnel and compression of the median nerve. In addition, if there is severe diabetic peripheral neuropathy, it may also be caused. Therefore, the symptoms of numbness alone cannot confirm the diagnosis of what disease is causing it, and should be further clarified based on other ancillary symptoms or the specific distribution of numbness in the fingers.