A transforaminal epidural steroid injection is a steroid injection into an opening at the side of the spine at the exit point of a specific nerve root (also known as a foramen). A small covering of epidural tissue extends just beyond the spine at that point and out over the nerve root. This injection is also known as a root block or transforaminal epidural block. The steroid injection reduces inflammation and irritation of the spinal nerve roots and the surrounding area. This reduces pain and other related symptoms such as numbness or swelling. A transforaminal epidural steroid injection can treat patients with pain radiating into the arms and legs from the spine and those with localized neck or back pain.