An epidural steroid injection is performed to help reduce inflammation and pain associated with nerve root compression. Nerve roots can be compressed by a herniated disc, spinal stenosis and bone spurs, resulting in inflammation, pain, numbness, tingling or weakness along the course of the nerve. Epidural steroid injections help lessen the inflammation of the nerve root. The epidural space is located above the outer layer of the spine surrounding the spinal cord and nerve roots.