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Ultrasound-Guided Approach for L5 Dorsal Ramus Block and Fluoroscopic Evaluation in Unpreselected Cadavers
  1. Manfred Greher, MD, MBA*,
  2. Bernhard Moriggl, MD, PhD, FIACA,
  3. Philip W.H. Peng, MBBS, FRCPC,
  4. Cristina E. Minella, MD§,
  5. Michela Zacchino, MD and
  6. Urs Eichenberger, MD#
  1. From the *Department of Anesthesiology, Intensive Care and Pain Therapy, Sacred Heart of Jesus Hospital, Vienna; and †Department of Anatomy, Histology and Embryology, Division of Clinical and Functional Anatomy, Medical University of Innsbruck, Innsbruck, Austria; ‡Department of Anesthesia and Pain Management, Toronto Western Hospital, University of Toronto, Toronto, Ontario, Canada; §Pain Therapy Service and ∥Department of Radiology, Foundation IRCCS Policlinico San Matteo, Pavia, Italy; and #Department of Anaesthesiology, St. Anna Clinic, Lucerne, Switzerland
  1. Address correspondence to: Manfred Greher, MD, MBA, Medical Director and Chair, Department of Anesthesiology, Intensive Care and Pain Therapy, Sacred Heart of Jesus Hospital, Baumgasse 20A, 1030 Vienna, Austria (e-mail: manfred.greher{at}


Background and Objectives Medial branch blocks are frequently performed to diagnose lumbar facet-joint–mediated pain. Ultrasound guidance can increase practicability and eliminate exposure to ionizing radiation when compared with fluoroscopy. However, ultrasound-guided L5 dorsal ramus block, which, together with L4 medial branch block is necessary to anesthetize the most commonly affected facet joint L5/S1, has not been described so far. The objective of this study was to develop a technique and to evaluate its accuracy with standard fluoroscopy in unpreselected cadavers.

Methods Twenty ultrasound-guided L5 dorsal ramus block approaches were performed with a new oblique out-of-plane technique in a rotated cross-axis view bilaterally in 10 cadavers. After checking the needle position in a second perpendicular sonographic plane, the final needle position was confirmed with conventional fluoroscopy by an independent observer.

Results All cadavers had significant degenerations of the lumbar spine, and 5 of them had moderate to severe spondylolisthesis. Skin-to-target distances were 42 ±7 mm. Sixteen L5 dorsal ramus block attempts were located at the exact radiological target, 1 was slightly too lateral, and 3 were slightly too caudal (3–10 mm away). The overall success rate in unpreselected cadavers reached 80% (95% confidence interval, 56%–94%) and in the subgroup of corpses without spondylolisthesis 100% (95% confidence interval, 69%–100%).

Conclusions This is the first study to show that ultrasound-guided L5 dorsal ramus block is accurate and feasible in the absence of significant spondylolisthesis when performed with an oblique out-of-plane technique.

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  • The authors declare no conflict of interest.

    GE Healthcare Inc, Europe, provided equipment support for this study. Philip Peng received equipment support from Sonosite Fujifilm Canada. Urs Eichenberger received equipment support from SonoSite Fujifilm Europe and Philips Europe.