Numbness and weakness in the legs are mainly due to the following reasons: 1. If there is numbness and weakness in both legs, with obvious sensory planes, or with dysfunction of urination and defecation, it is necessary to consider the possible existence of spinal cord disease, which requires magnetic resonance examination of the lumbar or thoracic spine. 2. 3. If the numbness and weakness of one leg is accompanied by unilateral leg pain, mainly neuralgia, consider whether the patient has lumbar disc herniation. 4. It may be due to peripheral neuropathy caused by diabetes.