Lumbar Interlaminar Ventral Epidural Injection Without Catheter at L5-S1 for Lumbosacral Radicular Pain: A Pilot Feasibility Study.

Background and Objectives: Lumbar interlaminar ventral epidural injection (LIVEI) offers a promising alternative to transforaminal epidural injection (TFEI) by enabling ventral epidural delivery while minimizing complication risks. While previous approaches often required catheter assistance, this pilot study evaluates the safety, technical feasibility, and early outcomes of a simplified LIVEI method at L5-S1 without catheter insertion. Materials and Methods: Twelve patients with lumbosacral radicular pain received unilateral catheter-free LIVEI at L5-S1 between October 2021 and September 2022. This small retrospective pilot cohort did not include a control group. Contrast spread patterns were evaluated fluoroscopically based on AP and lateral views. Spread was classified into three grades depending on anterior epidural distribution, cranio-caudal extent, and foraminal involvement. Visual Analog Scale (VAS) scores were assessed before and two weeks after the procedure. Spread was classified into three grades depending on anterior epidural distribution, cranio-caudal extent, and foraminal involvement. Results: Fluoroscopic images confirmed ventral epidural spread in all patients, with 75% showing foraminal extension and 67% demonstrating cranio-caudal spread over two or more levels. Baseline VAS scores averaged 6.5 ± 1.0, decreasing to 3.42 ± 1.31 two weeks post-procedure (p < 0.0001), with a mean reduction of 3.08 ± 1.00. No adverse events or complications were observed. Conclusions: Catheter-free LIVEI at the L5-S1 level demonstrated consistent anterior and multi-level ventral epidural contrast distribution on fluoroscopy, supporting the technical feasibility of this approach. In addition to this radiographic validation, patients achieved clinically meaningful pain relief with excellent tolerability. Further confirmation through larger-scale controlled studies is warranted to validate long-term clinical effectiveness.