To determine the current evidence to support guidelines for frequency and timing of epidural steroid injections (ESIs), to help determine what sort of response should occur to repeat an injection, and to outline specific research needs in these areas.
A PubMed, Medline (EBSCO), and Cochrane library search (January 1971-December 2005), as well as additional references found from the initial search.
There were no studies that specifically addressed the objectives outlined. Eleven randomized controlled trials, 1 prospective controlled trial, and 2 prospective cohort studies were identified that included a protocol involving repeat epidural injections for radicular pain secondary to herniated nucleus pulposus or spinal stenosis. One qualitative survey was also identified. Five review articles were also included that discussed this topic.
Data were extracted from clinical trials if they included the following: (1) protocols in clinical trials on ESIs that included repeat injections and the response required to trigger these injections, (2) any evidence given for establishing these protocols, and (3) similar studies that included only 1 injection. Specific mention of repeat ESIs and partial response that was mentioned in review articles was also included.
There is limited evidence to suggest guidelines for frequency and timing of ESIs or to help to define what constitutes the appropriate partial response to trigger a repeat injection. No study has specifically evaluated these objectives. Methodologically limited research suggests that repeat injections may improve outcomes, but the evidence is insufficient to make any conclusions.
There does not appear to be any evidence to support the current common practice of a series of injections. Recommendations for further research are made, including a possible study design.