Numbness in the left hand and foot may have the following causes: First, head disease, when there is a tumor in the head or cerebral thrombosis, cerebral hemorrhage, there can be symptoms of hemiplegia on one side, there can be numbness in the left side of the limb, which can be manifested as numbness in the left hand and left foot, then the early diagnosis and treatment should be carried out by MRI and CT examination of the head. Second, cervical spondylosis, when the cervical spondylosis is spinal cord type cervical spondylosis can compress the spinal cord, resulting in numbness of one side of the hands and feet, then early diagnosis and treatment should be carried out by cervical spine X-ray and nuclear magnetic examination. Third, cervical spine tumor, cervical spine tumor can also compress the nerve, resulting in numbness in the left hand and foot, and in this case, cervical spine nuclear magnetic examination should be conducted for early diagnosis and treatment.