Numbness of the legs may be caused by the following reasons: First, lumbar spine diseases, such as lumbar disc herniation, lumbar spinal stenosis or lumbar nerve tumors that compress the nerves and cause numbness of the legs. Numbness of the thighs, calves or sciatica can often occur, such as numbness from the buttocks all the way along the back of the thighs, radiating to the dorsum of the calves and soles of the feet. Second, due to pyriformis syndrome, pyriformis syndrome can occur in the lower extremity sciatic nerve compression, resulting in numbness of the legs, this time to carry out the relevant physical examination and check the neuromuscular electromyography, to carry out the diagnosis. Third, due to dermal neuritis, for example, the dermal nerve innervating a certain area of the leg is damaged or inflamed, can also lead to symptoms of leg numbness.