SNRB targets the nerve root where it comes out of the foramen, or the hole located between the vertebral bodies. It includes a mixture of lidocaine which numbs the area and a steroid to alleviate inflammation. An ESI also delivers numbing and anti-inflammatory medicines via a needle. However, for this, your doctor injects the ESI into a different area. The injection goes into the epidural space, located between the spinal cord and nerve’s protective sac and bone. Fat-filled areas make up this sac.