Effectiveness of Parasagittal Interlaminar Epidural Local Anesthetic with or without Steroid in Chronic Lumbosacral Pain: A Randomized, Double-Blind Clinical Trial

Background: Epidural injections (EI) are the most commonly performed minimally invasive interventionto 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 majorityof earlier studies have used either caudal, transforaminal (TF), or undefined interlaminar approaches forEI. The parasaggital interlaminar (PIL) approach route is reported to have good ventral epidural spreadand comparable effectiveness to the TF route. However, there is a lack of head-to-head comparativeeffectiveness 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 approachfor 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 methylprednisoloneacetate (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; and2 weeks, one, 2, 3, 6, 9, and 12 months after injection. Patients with inefficacy with the initial injectionor response deterioration received an additional injection of the same injectate and dose. Patients wereevaluated 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. Primaryoutcome 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 resultswere obtained at 6, 9, and 12 months, respectively. The probability of achieving EPR was significantly higherin group LS at various time-points during the one year follow-up as compared to group L (P = 0.01) Asignificant reduction in NRS and improvement in MODQ were observed at all time-points post-interventioncompared to baseline (P < 0.001) in both groups. NRS and MODQ scores were significantly lower in groupLS as compared to group L at all time intervals post baseline. On average patients in group L received2.0 (0.85) and group LS received 1.7 (0.71) injections annually (P = 0.07). Ventral epidural spread wascomparable 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 individualanalgesic medication, and lack of placebo group.Conclusions: Using a PIL approach and the addition of steroid to LA for EI may provide superioreffectiveness 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/2014/04/004572Key words: Epidural injection, epidural steroid, chronic low back pain, chronic lumbosacral pain,parasagittal interlaminar