title: Use of electrical nerve stimulation to monitor lumbosacral epidural needle placement in cats.
abstract: OBJECTIVE
  To determine the minimal electrical threshold (MET) necessary to elicit muscle contraction of the pelvic limb or tail when an insulated needle is positioned outside (METout) and inside (METin) the lumbosacral epidural space in cats.
  
  
  METHODS
  Prospective, blinded study.
  
  
  METHODS
  Twelve mixed-breed healthy adult cats, scheduled for a therapeutic procedure where lumbosacral epidural administration was indicated.
  
  
  METHODS
  Under general anesthesia, an insulated needle was advanced through tissues of the lumbosacral interspace until its tip was thought to be just dorsal to the interarcuate ligament. An increasing electrical current (0.1 ms, 2 Hz) was applied through the stimulating needle in order to determine the MET necessary to obtain a muscle contraction of the pelvic limb or tail (METout), and then 0.05 mL kg−1 of iohexol was injected. The needle was further advanced until its tip was thought to be in the epidural space. The MET was determined again (METin) and 0.2 mL kg−1 of iohexol was injected. The cats were maintained in sternal position. Contrast medium spread was determined through lateral radiographic projections.
  
  
  RESULTS
  The radiographic study confirmed the correct needle placement dorsal to the interarcuate ligament in all cats. When the needle was placed ventrally to the interarcuate ligament, iohexol was injected epidurally in ten and intrathecally in two cats. The METout and METin was 1.76 ± 0.34 mA and 0.34 ± 0.07 mA, respectively (p < 0.0001).
  
  
  CONCLUSIONS
  Nerve stimulation can be employed as a tool to determine penetration of the interarcuate ligament but not the piercing of the dura mater at the lumbosacral space in cats.
authors.forename: Pablo E
authors.initials: PE
authors.lastname: Otero
authors.forename: Andrea S
authors.initials: AS
authors.lastname: Zaccagnini
authors.forename: Santiago E
authors.initials: SE
authors.lastname: Fuensalida
authors.forename: Natali
authors.initials: N
authors.lastname: Verdier
authors.forename: Matias
authors.initials: M
authors.lastname: Sciocco
authors.forename: Diego A
authors.initials: DA
authors.lastname: Portela
mesh_terms: D000767:Anesthesia, Epidural / Q000379:methods / Q000662:veterinary*; D000818:Animals; D002415:Cats; D003287:Contrast Media / Q000008:administration & dosage / Q000494:pharmacology; D004558:Electric Stimulation / Q000379:methods*; D005260:Female; D007268:Injections, Epidural / Q000662:veterinary; D007472:Iohexol / Q000008:administration & dosage / Q000494:pharmacology; D008161:Lumbosacral Region / Q000502:physiology; D008297:Male; D009119:Muscle Contraction; D018482:Muscle, Skeletal / Q000502:physiology; D009339:Needles
chemical_list: D003287:Contrast Media; D007472:Iohexol