The common causes of numbness in the patient’s big toe are peripheral neuritis, lumbar spinal stenosis, and lumbar disc herniation, as follows: first, peripheral neuritis: when the peripheral nerves are inflamed, the numbness of the big toe starts, and gradually goes up to the dorsum of the foot. Second, lumbar spinal stenosis: if the lumbar spinal stenosis compresses the lumbar 5 nerve, the patient will experience numbness on the outside of the toes and toes. Third, lumbar disc herniation: If the lumbar disc herniation occurs in the lumbar 4-5 area and the herniated nucleus pulposus compresses the lumbar 5 nerve, the patient will experience numbness in the big toe and between the web of the first and second toes because the lumbar 5 nerve innervates the sensation of the skin of the toes and the movement of the toes, so as long as a disease that can cause pressure on the lumbar 5 nerve, the numbness in the big toe will occur. For the above diseases, lumbar disc herniation is the most common. Patients are advised to check the lumbar disc MRI or CT film, which can make a clear diagnosis.