The left side of the body appears numbness, usually consider two situations: First, craniocerebral lesions, such as cerebral infarction and brain tumors in the cranium, affecting the normal function of the brain, it is possible to appear on one side of the limb numbness, which is due to the central nervous innervation. Second, patients with cervical spondylosis and lumbar intervertebral disc herniation, if the left cervical intervertebral disc herniation or bony stenosis, the nerve root of the cervical vertebrae is squeezed, and the nerve bundles are ischemic for a long time, the numbness of the left upper limb will occur. If the patient is combined with lumbar disc herniation, and also the left side of the herniation, the herniated position of the lumbar spine compressed to the nerve root, the nerve is compressed, ischemia, the same numbness will occur. These are the two reasons about the numbness on the left side of the body.