Series of Epidural Steroid Injections May Not Be Helpful for Treatment of Radicular Low Back Pain
Chronic lower back pain caused by radiculopathy (inflammation and irritation of a nerve root) is sometimes treated with a series of epidural steroid injections. The injection is meant to relieve the pain and symptoms caused by the nerve irritation. The usual schedule is one injection followed by more injections - one every two weeks - usually up to three injections total, if there are no improvements or only partial improvement.

The decision whether to use the series of injections has been found, by research, to depend on the treating physician's personal preferences and experience, anecdotal (stories from patients and physicians) evidence of its success, and/or findings in the literature. However, according to the literature, there is no indication either way as to whether the series of injections is helpful or not, with a minimum or maximum of injections total for one patient or treatment.

The authors of this literature review sought to determine if there was evidence for the frequency and timing of such injections for patients with radiculopathy and if there is evidence to help determine what a partial response is. Finally, the authors wanted to draw up an outline for the type of research needed to clarify this issue.

While searching through the literature, the criteria for studies were that the injections be more than one per patient for radiculopathy and/or any evidence that helped establish a protocol for the injections, as well as studies that did only use one injection but had protocols that could have called for further injections if needed.

The researchers found 11 randomized controlled trials, one prospective controlled trial, and two prospective cohort studies, as well as one qualitative survey an five review articles that fit their requirements for this review. Some recommendations from the studies were:

1- "A 2nd injection be given a few days to a week after the first if there was evidence of negative or partial response. A third injection was rarely helpful. This was based on previous experience."
2- "Long-term follow-up (average, 20 months) failed to show the efficacy of a second injection administered to patients whose pain did not respond within 24 hours to either injection."
3- "Repeated injections could produce a more sustained effect."
4- "There is no consensus on frequency and interval of injections."
5- "Fewer injections were required than usually required with blind injections."
6- "The protocol most closely mirrored local practice. There was no advantage to performing more than one injection."
7- "Corticosteroids did not provide any additional benefit. Multiple injections may produce a more sustained effect."

After reviewing the protocols and the study findings, the authors concluded that a second injection was commonly recommended before the introduction of fluoroscopic guidance to allow for more accurate injecting techniques. It has not been determined why the second injection was recommended. It was thought, in some instances, repeat injections could be needed if the first one missed the mark, particularly before the guided injections were available. One researcher said that the repeat injections had greater success, but a subsequent study found otherwise.

The authors of this study point out that their own study was limited in a few ways. They used a particular grading system to choose the articles to include in the review and this grading system may have affected the findings they drew from the studies. As well, the cause of the patients' radiculopathy wasn't always understood or known. They conclude that the evidence for repeat injections is limited so it is not possible to suggest guidelines for the number of epidural steroid injections for radicular low back pain. They also suggest that a randomized controlled trial with patients who have a confirmed single diagnosis, with set symptom duration, and who received guided injections, would be the most appropriate type of trial.
Suzanne Novak, MD, PhD, and William C. Nemeth, MD. The Basis for Recommending Repeating Epidural Steroid Injections for Radicular Low Back Pain: A Literature Review. In Archives of Phys Medicine & Rehabilitation. March 2008. Vol. 89. Issue 3. Pp. 543-552.