title: Comparison of three ultrasound guided approaches to the lumbar plexus in dogs: a cadaveric study.
abstract: OBJECTIVE
  To assess the accuracy of contrast material injection and the dispersion of injectate following ultrasound guided injections at the level of L6 and L7, in canine cadavers.
  
  
  METHODS
  Prospective, randomized, experimental study.
  
  
  METHODS
  Twenty nine mixed breed canine cadavers (28.9 ± 6.0 kg).
  
  
  METHODS
  Three ultrasound-guided approaches to the lumbar plexus (LP) were compared: 1) a dorsal pre-iliac approach at the level of L6; 2) a lateral paravertebral approach at mid-L6; and 3) a lateral paravertebral approach at mid-L7. An isovolumic mixture of iodine-based contrast with new methylene blue (0.1 mL kg(-1)) was injected bilaterally in the juxta-foraminal region along the L6 or L7 nerve root. Computed tomography was performed followed by segmentation and 3D reconstruction of the lumbar spine and contrast material volumes using dedicated software. Distances between contrast material and the fifth through seventh lumbar foraminae, and length of femoral (FN) and obturator (ON) nerve staining were measured and compared between approaches (p < 0.05).
  
  
  RESULTS
  Injectate moved cranial and caudal to the site of injection, and dispersed into an ovoid shape between the quadratus lumborum, iliopsoas and psoas minor muscles. Injections at L7 resulted in significantly closer contrast proximity to the L6 and L7 foraminae (p < 0.001). Femoral nerve staining was similar for all approaches, ON staining was more consistent after L7 injections (p < 0.001).
  
  
  CONCLUSIONS
  An ultrasound-guided lateral paravertebral approach to the LP proved very practical and accurate, with easy visualization of the plexus and associated nerves. To ensure that the ON is covered by injectate, an approach at the level of L7 is recommended. Further studies are necessary to determine if this correlates with clinically effective local anesthesia.
authors.affiliation: Department of Small Animal Clinical Sciences, College of Veterinary Medicine, Michigan State University, East Lansing, MI, USA.
authors.forename: Sophie M
authors.initials: SM
authors.lastname: Graff
authors.affiliation: Department of Large Animal Clinical Sciences, College of Veterinary Medicine, Michigan State University, East Lansing, MI, USA.
authors.forename: Deborah V
authors.initials: DV
authors.lastname: Wilson
authors.affiliation: Department of Veterinary Clinical Sciences, College of Veterinary Medicine, The Ohio State University, Dublin, OH, USA.
authors.forename: Laurent P
authors.initials: LP
authors.lastname: Guiot
authors.affiliation: Department of Small Animal Clinical Sciences, College of Veterinary Medicine, Michigan State University, East Lansing, MI, USA.
authors.forename: Nathan C
authors.initials: NC
authors.lastname: Nelson
mesh_terms: D000818:Animals; D002102:Cadaver; D003287:Contrast Media / Q000008:administration & dosage*; D004285:Dogs / Q000033:anatomy & histology*; D008160:Lumbosacral Plexus / Q000033:anatomy & histology* / Q000000981:diagnostic imaging; D009407:Nerve Block / Q000662:veterinary*; D011446:Prospective Studies; D018084:Ultrasonography, Interventional / Q000662:veterinary
chemical_list: D003287:Contrast Media
keywords: canine; local anesthesia; nerve block; ultrasound