If you feel numbness and weakness in your legs, you should consider the following diseases: First, if you have numbness and weakness in one leg, which is related to activity, ask the patient if he has any pain in the lower back, and if he may have a lumbar disc herniation, he needs to have an MRI of the lumbar spine. Second, if the numbness and weakness of both legs, and the numbness is mainly below the knee, and the body is wearing socks like a sock-like shallow sensory loss, ask the patient if he has previous diabetes. If the peripheral nerve changes caused by diabetes, there will also be numbness and weakness of the legs. Third, if the patient has numbness and weakness in both legs, progressive development from distal to proximal, and if there is weakness in both upper limbs. For young patients, ask the patient if there is any history of cold, fever, or vaccination before the disease, and be alert to the possibility of Grinbarr’s syndrome, which requires cranial MRI and lumbar puncture.