title: Fluoroscopic analysis of lumbar epidural contrast spread after retrograde interlaminar ventral epidural injection (RIVEI).
abstract: BACKGROUND
  Retrograde interlaminar ventral epidural injection (RIVEI) may hypothetically be more effective if the catheter is placed at the ventrocaudal aspect of the exiting nerve. We tested that hypothesis by measuring ventral and dorsal epidural contrast flow during RIVEI.
  
  
  METHODS
  To perform RIVEI, a 17 G Tuohy needle was inserted to access the epidural space. A 19 G epidural catheter was inserted and advanced through the needle, passing in a caudal direction to the lower aspect of the contralateral pedicle. Fluoroscopic images were recorded at 1.5 ml increments of contrast. Based on the images of contrast dispersal, the extent of contrast spreading was assessed in 82 patients.
  
  
  RESULTS
  All 82 patients (100%) injected with 3.0 ml contrast medium demonstrated ventral epidural spreading. Mean spreading level from the catheter tip was 2.21 ± 0.93 with 3.0 ml of contrast. Spreading to the superior aspect of the supra-adjacent intervertebral disc was observed in 67/82 (81.7%) of RIVEIs with 3.0 ml of contrast injected into the ventral epidural space. We found that 3.0 ml of contrast reached the inferior aspect of the infra-adjacent intervertebral disc in 95.1% (78/82) of RIVEIs performed.
  
  
  CONCLUSIONS
  Our findings imply that a one-level RIVEI may be sufficient in situations where a two-level injection would currently be used.
authors.affiliation: Department of Anesthesiology and Pain Medicine, School of Medicine, Hanyang University, Seoul, Korea.
authors.forename: Ji Seon
authors.initials: JS
authors.lastname: Jeong
authors.affiliation: Department of Anesthesiology and Pain Medicine, School of Medicine, Hanyang University, Seoul, Korea.
authors.forename: Jae Chol
authors.initials: JC
authors.lastname: Shim
authors.affiliation: Department of Anesthesiology and Pain Medicine, School of Medicine, Hanyang University, Seoul, Korea.
authors.forename: Jung Pil
authors.initials: JP
authors.lastname: Woo
authors.affiliation: Department of Anesthesiology and Pain Medicine, School of Medicine, Hanyang University, Seoul, Korea.
authors.forename: Jae Hang
authors.initials: JH
authors.lastname: Shim
keywords: Contrast media; Epidural injections