Sedation may be offered for sympathetic nerve blocks. For blocks of the lower extremity, you will be lying comfortably on your abdomen and an X-ray machine is used to visualize the vertebrae in your lower back. The skin on your back is then sterilized and numbed with local anesthetic. After that, a small needle is safely guided to the front of your spine where your sympathetic nerves lie. Sometimes a second needle is guided to the opposite side as well. Once the correct position is confirmed, local anesthetic is injected through the needles. You may experience warmth in your legs and feet. This is a normal and expected reaction.