Background: Epidural injections (EI) are the most commonly performed minimally invasive intervention to manage chronic low back pain (CLBP) with lumbosacral radicular pain (LRP). Local anesthetic (LA) and/or steroids are frequently used injectates for EI and are reported with variable effectiveness. The majority of earlier studies have used either caudal, transforaminal (TF), or undefined interlaminar approaches for EI. The parasaggital interlaminar (PIL) approach route is reported to have good ventral epidural spread and comparable effectiveness to the TF route. However, there is a lack of head-to-head comparative effectiveness research of LA with or without steroid for managing CLBP with LRP using a PIL approach.
Objective: To compare the effectiveness of EI of LA alone and LA with steroid using a PIL approach for managing CLBP with LRP.
Study design: Randomized, double blind, active control one year follow-up study.
Setting: Interventional pain management clinic in a tertiary care center in India.
Methods: Sixty-nine patients were randomized to receive fluoroscopic guided EI of either 8 mL of 0.5% lidocaine (group L, n = 34) or 6 mL of 0.5% lidocaine mixed with 80 mg (2 mL) of methylprednisolone acetate (group LS, n = 35). Patients were evaluated for pain intensity using 0 - 10 numerical rating scale (NRS) and functional disability using Modified Oswestry Disability Questionnaire (MODQ) at baseline; and 2 weeks, one, 2, 3, 6, 9, and 12 months after injection. Patients with inefficacy with the initial injection or response deterioration received an additional injection of the same injectate and dose. Patients were evaluated for achieving effective pain relief (EPR, i.e., ≥ 50% from baseline), overall NRS and MODQ, number of injections, and presence of ventral and perineural spread over one year follow-up. Primary outcome was proportion of patients achieving EPR at 3 months.
Results: A significantly higher proportion of patients achieved EPR at 3 months in group LS [30 (86%, 90% CI 73% - 93%)] as compared to group L [17 (50%, 90% CI 36% - 64%)] (P = 0.02). Similar results were obtained at 6, 9, and 12 months, respectively. The probability of achieving EPR was significantly higher in group LS at various time-points during the one year follow-up as compared to group L (P = 0.01) A significant reduction in NRS and improvement in MODQ were observed at all time-points post-intervention compared to baseline (P < 0.001) in both groups. NRS and MODQ scores were significantly lower in group LS as compared to group L at all time intervals post baseline. On average patients in group L received 2.0 (0.85) and group LS received 1.7 (0.71) injections annually (P = 0.07). Ventral epidural spread was comparable in both groups (97%). No major complications were encountered in either group; however, intravascular spread of contrast was noted during 2 injections (one in each group) requiring relocation.
Limitations: A single center study, lack of documentation of adjuvant therapies like individual analgesic medication, and lack of placebo group.
Conclusions: Using a PIL approach and the addition of steroid to LA for EI may provide superior effectiveness in terms of extent and duration of pain relief for managing CLBP with unilateral LRP, even though, local anesthetic alone also was effective.
Trial registration: CTRI/2014/04/004572