If one side of the arm, leg or hand is numb, it is often due to a head disease or a tumor of the cervical spinal cord that compresses the nerves and causes numbness in one side of the arm, leg or hand, which should be diagnosed by an MRI of the head and cervical spine and, if necessary, requires surgery. When there is a bilateral tumor in the head or a large cerebral infarction, it can lead to numbness in the arms, legs and hands, often bilaterally, which can be diagnosed by early examination of CT and MRI of the head. If cervical spondylosis compresses the spinal cord, it can lead to symptoms of numbness in the limbs, which can be accompanied by weakness, and in severe cases, there can be dysfunctional bowel movements, which should be diagnosed by MRI of the cervical spine.