title: Segmental cervical spine motion during orotracheal intubation of the intact and injured spine with and without external stabilization.
abstract: OBJECTIVE
  The purpose of this study was to establish a cadaveric model for evaluating cervical spine motion in both the intact and injured states and to examine the efficacy of commonly used stabilization techniques in limiting that motion.
  
  
  METHODS
  Intubation was performed in fresh human cadavers with intact cervical spines, following the creation of a C4-5 posterior ligamentous injury. Movement of the cervical spine during direct laryngoscopy and intubation was recorded using video fluoroscopy and examined under the following conditions: 1) without external stabilization; 2) with manual in-line cervical immobilization; and 3) with Gardner-Wells traction. Subsequently, segmental motion of the occiput through C-5 (Oc-C5) was measured from digitized frames of the recorded video fluoroscopy. The predominant motion, at all levels measured in the intact spine, was extension. The greatest degree of motion occurred at the atlantooccipital (Oc-C1) junction, followed by the C1-2 junction, with progressively less motion at each more caudal level. After posterior destabilization was induced, the predominant direction of motion at C4-5 changed from extension to flexion, but the degree of motion remained among the least of all levels measured. Traction limited but did not prevent motion at the Oc-C1 junction, but neither traction nor immobilization limited motion at the destabilized C4-5 level.
  
  
  CONCLUSIONS
  Cadaveric cervical spine motion accurately reflected previously reported motion in living, anesthetized patients. Traction was the most effective method of reducing motion at the occipitocervical junction, but none of the interventions significantly reduced movement at the subaxial site of injury. These findings should be considered when treating injured patients requiring orotracheal intubation.
authors.affiliation: Division of Neurosurgery, The University of Iowa Hospitals and Clinics, Iowa City 52242, USA.
authors.forename: P J
authors.initials: PJ
authors.lastname: Lennarson
authors.forename: D
authors.initials: D
authors.lastname: Smith
authors.forename: M M
authors.initials: MM
authors.lastname: Todd
authors.forename: D
authors.initials: D
authors.lastname: Carras
authors.forename: P D
authors.initials: PD
authors.lastname: Sawin
authors.forename: J
authors.initials: J
authors.lastname: Brayton
authors.forename: Y
authors.initials: Y
authors.lastname: Sato
authors.forename: V C
authors.initials: VC
authors.lastname: Traynelis
mesh_terms: D000368:Aged; D000369:Aged, 80 and over; D002574:Cervical Vertebrae / Q000293:injuries* / Q000503:physiopathology; D004632:Emergency Medical Services; D005260:Female; D019416:Head Movements / Q000502:physiology*; D006801:Humans; D007103:Immobilization; D007442:Intubation, Intratracheal; D008023:Ligaments, Articular / Q000293:injuries / Q000503:physiopathology; D008297:Male; D008875:Middle Aged; D016059:Range of Motion, Articular / Q000502:physiology; D013124:Spinal Injuries / Q000503:physiopathology*; D014143:Traction; D016896:Treatment Outcome