Epidural contrast flow patterns of retrograde interlaminar ventral epidural injections stratified by the final catheter tip placement

Abstract

Background: The aim of the study is to evaluate the relevant spreading for contrasts in the ventral and dorsal epidural space during retrograde interlaminar ventral epidural injections (RIVEIs)with the catheter tip placed ventral or dorsal to the spinal nerve. Methods: For RIVEIs, a 17G Tuohy needle was inserted in retrograde fashion. Catheter containing a removable stylet was inserted and advanced via the needle and passed to the lower aspect of contralateral pedicles in 75 patients. Fluoroscopic images were recorded at 1.5 ml increments of contrast. Using the fluoroscopy,the contrast spreading pattern and whether the contrast spread to the specific anatomic landmarks (superior aspect of the supra-adjacent intervertebral disc [SIVD] and inferior aspect of the infra-adjacent intervertebral disc [IIVD]) were evaluated. Whether the catheter was placed ventral or dorsal to the spinal nerve was assessed with the computed tomography axial and sagittal views. Results: There were no significant differences in the mean levels of epidural contrast spreading extents between ventral and dorsal catheter placements. Ventral or dorsal catheter tip placements demonstrated ventral concurrent flows over to the SIVD and IIVD over 80% of subjects with 3.0 ml of contrast. Conclusions: During RIVEIs, the catheter tip placed ventral to the spinal nerve did not show superiority with regards to epidural spreading extent as compared with dorsal catheter placement. One-level instead of a two-level injection may be considered for the two-level central pathology.