Epidural steroid injections are most commonly used in situations of radicular pain, which is a radiating pain that is transmitted away from the spine by an irritated spinal nerve. Irritation of a spinal nerve in the low back ( lumbar radiculopathy ), such as from lumbar spinal stenosis , cervical spinal stenosis, herniated disc , and foraminal encroachment, causes back pain that goes down the leg. Epidural injection is also used as a minimally invasive procedure to treat nerve compression in the neck (cervical spine), referred to as cervical radiculopathy , which causes pain.
Radiculopathy occurs when something irritates a spinal nerve—say a “slipped disc” causing a pinched nerve. This is also called sciatica . There are resident stem and other cells in the local tissues everywhere in our body. Many live around blood vessels. These are obviously also present in the disc and nerves in the epidural space and they usually play an important role in suppressing inflammation and repairing damage. We know, based on a copious in vitro (lab) data, that the high-dose steroids used in epidural injections can kill these cells. So the progression of the series of epidural steroid injections looks a little something like this: