Transforaminal versus lateral parasagittal versus midline interlaminar lumbar epidural steroid injection for management of unilateral radicular lumbar pain: A randomized doubleblind trial

Background: Epidural steroid injections (ESIs) are commonly used for management of lumbosacral radicular pain. Midline interlaminar (MIL) or transforaminal (TF) routes are commonly used. The TF route, although associated with higher delivery of drug to the ventral epidural space, has serious complications including spinal cord injury and permanent paralysis reported in literature. Therefore, there is a search for a technically better route with fewer complications and greater drug delivery into the ventral epidural space. Recently, a parasagittal interlaminar (PIL) approach has been defined. Objectives: We conducted this study to compare therapeutic effectiveness of 3 techniques of ESIs in patients having unilateral lumbar radiculopathy. Further, effect of ESI on bone mineral density (BMD) and serum osteocalcin levels were studied. Study Design: Randomized double-blind trial. Setting: Pain clinic of a tertiary care hospital. Methods: Sixty-five patients were randomly allocated into group MIL, group PIL, and group TF to receive epidural injection with 80 mg of methylprednisolone and 2 mL of 2% lidocaine. Effective pain relief and improvement in disability were assessed using Visual Analog Scale (VAS) and Modified Oswestry Disability Questionnaire (MODQ) scores at 2 weeks, 4 weeks, 3 months, and 6 months, respectively. Patients with < 50% relief received additional injection. Primary outcome of study was effective pain relief at 6 months. Mean change in VAS and MODQ scores, BMD, and serum osteocalcin levels were secondary outcome assessed. Results: Patients having effective pain relief were significantly higher in group PIL (16 of 20 [80%]) and group TF (15 of 20 [75%]) compared with group MIL. Patients receiving ESI in group PIL and group TF showed significantly lower VAS scores than group MIL (P = 0.02, P = 0.50 at 3 months and P = 0.00, P = 0.02 at 6 months, respectively). Mean MODQ scores in group PIL and group TF were significantly lower than group MIL. However, group PIL and group TF did not significantly differ in MODQ scores. There was no significant change in serum osteocalcin and BMD, as assessed by dual energy x-ray absorptiometry scan at 3 months. Limitations: The absence of a placebo control group, small sample size, and relatively short follow-up of 6 months were limitations. Conclusions: PIL approach is equivalent to TF and superior to MIL approach in terms of effective pain relief and decrease in disability in patients with unilateral lumbar radiculopathy. This study showed no deleterious effect on BMD.