Patterns of Epidural Patch Distribution: The Influence of Spinal Level, Injection Technique, and Patch Volume/Composition on Craniocaudal and Ventral Epidural Dispersion.

Abstract

Background and purpose: Epidural patching with autologous blood and/or fibrin sealant is a common treatment for spinal cerebrospinal fluid (CSF) leaks, yet the factors influencing patch distribution remain poorly understood. This study aimed to analyze the craniocaudal (CC) and ventral epidural (VE) extent of epidural patch material and investigate the impact of variables such as patch volume, composition, spinal level of injection, and patient habitus on distribution patterns.

Materials and methods: This retrospective, cross-sectional cohort study included patients who underwent CT-guided epidural patching from January to September 2024. Inclusion criteria were age ≥18 years, dorsal interlaminar (DI) or transforaminal (TFO) epidural patching using blood, fibrin, or both, and immediate post-patch imaging capturing the entire patch extent. Patch distribution was assessed for CC and VE spread. Statistical analyses included linear and logistic regression models, with multivariate analyses adjusting for confounders.

Results: Of 152 patients patched during the study period, 33 met inclusion criteria (mean age 45.4 years; 84.1% female) with 44 spinal levels patched: cervical (6.8%), thoracic (68.2%), and lumbar (25%). Mean patch volume (PV) per needle was 7.2 mL, with a mean CC spread of 4.6 spinal levels. There was a positive relationship between PV and CC spread across all spinal levels (β = 0.29, p = 0.001). Patches in the cervical region demonstrated the highest CC spread efficiency (0.77 levels/mL) compared to thoracic (0.56 levels/mL) and lumbar patches (0.47 levels/mL; p < 0.01). DI injections achieved greater CC spread but less VE dispersion than TFO injections (5.0 vs. 3.2 levels; p = 0.02; 58.8% vs 70.0%, p = 0.52). VE spread occurred in 61.4% of cases and followed a non-linear pattern along the spine, with an inflection point at T3.

Conclusions: The distribution of epidural patch material is influenced by spinal level, PV, composition, and injection approach. Cervical patches provide the greatest spread efficiency relative to volume, while DI approaches enhance craniocaudal spread but reduce ventral dispersion.

Abbreviations: CSF = cerebrospinal fluid; CC = craniocaudal; VE = ventral epidural; DI = dorsal interlaminar; TFO = transforaminal.