Numbness on the left side of the body may be related to the following reasons: 1, there may be damage to the spinal cord, for example, in a relatively high position, such as the cervical medulla where there is damage to one side of the spinal cord, it may lead to a large area of numbness on the left side of the body. 2, there may be occupational diseases of the spinal cord, such as fracture blocks in the spinal canal, foreign bodies or tumors leading to spinal cord compression, if the right side of the spinal cord compression, there may also be numbness on the left side of the body. 3, may be caused by brain-related lesions, the left side of the body numbness may exist on the right side of the internal capsule or the left side of the brain stem parts of the lesions, such as cerebral infarction, cerebral hemorrhage and other lesions. In addition to this, brain tumors may also cause this symptom. If the patient has just developed this symptom, he/she should go to an orthopedic department of a secondary or higher hospital as soon as possible to clarify the cause and then deal with it.