Poster 267: The Incidence of Intravascular Needle Placement While Performing Medial Branch Nerve Blocks in the Lumbar Spine

Abstract

Objective: To record the incidence of intravascular needle placement during fluoroscopically guided, contrast-enhanced, medial branch nerve blocks performed at the zygapophyseal joints in the lumbar spine. Design: A prospective, observational study. Setting: Ambulatory surgery center. Participants: Private practice patients with a chief complaint of axial low back pain, clinical signs, and radiographic findings suggestive of zygapophyseal joint-mediated pain. Interventions: 361 consecutive fluoroscopic-guided nerve blocks of the L2, L3, and L4 medial branch nerves and the L5 dorsal rami were performed using International Spine Intervention Society practice guidelines protocol. Once proper needle placement was established, the presence or absence of intravascular needle-tip placement was identified by the performing physician while injecting contrast dye through the needle during live fluoroscopy. Main Outcome Measures: The lumbar level and side-specific presence of vascular flow of contrast injected under live fluoroscopy. Results: In 361 lumbar medial branch nerve blocks, the overall rate of intravascular needle placement was 13.6%. The level with the highest incidence was L4 (18.2%). The level with the lowest incidence was L5 (6.0%). There was no significant side-to-side difference at each respective lumbar nerve level. Conclusions: There is a significant incidence of intravascular needle placement using standard medial branch nerve block techniques, especially at the L4 medial branch nerve level. Performing medial branch nerve blocks without fluoroscopic confirmation of contrast flow may lead to intravascular administration of medication and may therefore potentially lead to an increase in false negative results and/or potential health risks to patients undergoing these procedures.