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:
Elective spinal injections should be performed with imaging guidance, such as fluoroscopy or the use of a radiocontrast agent , unless that guidance is contraindicated.  Imaging guidance ensures the correct placement of the needle and maximizes the physician's ability to make an accurate diagnosis and administer effective therapy.  Without imaging, the risk increases for the injection to be incorrectly placed, and this would in turn lower the therapy's efficacy and increase subsequent risk of need for more treatment.  While traditional techniques without image guidance, also known as blind injections , can assure a degree of accuracy using anatomical landmarks, it has been shown in studies that image guidance provides much more reliable localization and accuracy in comparison.