Epidural injections are used to treat radicular pain caused by nerve irritation. This type of pain is usually caused by herniated discs or spinal stenosis. A herniated disc occurs when pressure or degeneration produces a tear in the disc's outer ring (the annulus), and the nucleus ruptures out of its normal space. If it rips near the spinal canal, the bulging disc can push out of its space and into the spinal canal, placing inappropriate pressure on the spinal cord and nerve roots. Spinal stenosis is a narrowing of the spinal canal that can cause pressure on the spinal cord and spinal nerves.
Epidural injections are also helpful when the main problem is arthritis of the facet joints in multiple areas of the spine. The medication coats the outside of the problem joints and absorbs into the joints. This type of injection reduces the inflammation in the joint. The injection is sometimes aimed at the small nerves that supply the joints.
It may be necessary to have several epidural injections in a series over a
period of a few weeks. This is because the relief from the epidural injection
usually decreases with time. It is not uncommon to have three lumbar epidural
injections, each about ten days apart.
