Can Repeat Injection Provide Clinical Benefit in Patients with Lumbosacral Diseases When First Epidural Injection Results Only in Partial Response?

BACKGROUND Epidural steroid injection (ESI) is known to be an effective treatment for lower back or radicular pain due to herniated intervertebral disc (HIVD) and spinal stenosis (SS). Although repeat ESI has generally been indicated to provide more pain relief in partial responders after a single ESI, there has been little evidence supporting the usefulness of repeat injections in cumulative clinical pain reduction. OBJECTIVES The purpose of this study was to determine whether repeat ESI at a prescribed interval of 2 to 3 weeks after the first injection would provide greater clinical benefit in patients with partial pain reduction than that provided by intermittent injection performed only when pain was aggravated. STUDY DESIGN An Institutional Review Board (IRB)-approved retrospective chart review. SETTING Spine hospital. METHODS Two hundred and four patients who had underwent transforaminal ESI (TFESI) for treatment of lower back and radicular pain due to HIVD or SS and could be followed-up for one year were enrolled. We divided the patients into 2 groups. Group A (N = 108) comprised partial responders (NRS = 3 after first injection) who underwent repeat injection at a prescribed interval of 2 to 3 weeks after the first injection. Group B (N = 96) comprised partial responders who did not receive a repeat injection at the prescribed interval, but received repeat injections only for aggravation of pain. Various clinical data including total number of injections during one year, duration of NRS < 3 during one year (NRS < 3 duration), and time interval until aggravation of pain required additional injections after repeat injection in group A, or after first injection in group B (time to reinjection), were assessed. These data were compared between groups A and B in terms of total population, HIVD, and SS. RESULTS In the whole population, the mean time to reinjection was 6.09 ± 3.02 months in group A and 3.69 ± 2.07 months in group B. The NRS < 3 duration was 9.72 ± 2.86 months and 6.2 ± 2.61 months in groups A and B, respectively. In HIVD patients, the mean time to reinjection was 5.82 ± 3.23 months in group A and 3.84 ± 2.34 months in group B, and NRS < 3 duration was 9.40 ± 3.34 months and 7.15 ± 2.40 months in groups A and B, respectively. In SS patients, the mean time to reinjection was 6.40 ± 2.85 months in group A and 3.59 ± 1.88 months in group B, and NRS < 3 duration was 9.98 ± 2.41 months and 5.52 ± 2.55 months in groups A and B, respectively. Group A had a significantly longer time to reinjection and longer NRS < 3 duration than group B in the whole population, HIVD, and SS. LIMITATION Retrospective design. CONCLUSIONS Repeat TFESI conducted at 2- to 3-week intervals after the first injection in partial responders contributed to greater clinical benefit compared to intermittent TFESI performed only upon pain aggravation. These benefits were observed in patients with HIVD and in those with SS, irrespective of severity or location of disease.