title: Persistent first intersegmental vertebral artery in association with type II odontoid fracture: surgical treatment utilizing a novel C1 posterior arch screw: case report.
abstract: OBJECTIVE
  Posterior cervical stabilization for cervical fractures is common, and numerous techniques for fixation have been described. This case describes the novel usage of C1 laminar screws due to a persistent intersegmental artery and congenital fusion of C2-C3.
  
  
  METHODS
  A 64-year-old woman presented with loss of consciousness after falling down a flight of stairs. Initial CT scan showed a type II odontoid fracture with significant malalignment, as well as an anomalous congenital fusion of C2-C3 and degenerative spondylolisthesis of C3 to C4. CT angiogram demonstrated bilateral persistent first intersegmental arteries coursing through the C1-C2 neural foramina.
  
  
  METHODS
  The patient underwent C2 fracture reduction and posterior C1-C4 fusion. C1 posterior arch screws were placed due to the patient's anomalous vertebral artery location. The construct was anchored caudally by C2 pars interarticularis screws and C4 lateral mass screws. The patient experienced an excellent neurologic and radiographic outcome at 12.5 months.
  
  
  CONCLUSIONS
  Posterior fixation for fractures of the cervical spine is common; however, the use of C1 posterior arch screws for fractures has not previously been described. The presence of a persistent intersegmental course of the vertebral artery, a rare but reported anomaly, should be regarded as a contraindication to placement of C1 lateral mass screws and necessitates careful consideration of the available surgical options.
authors.affiliation: Department of Neurosurgery, The Medical College of Wisconsin, Milwaukee, Wisconsin 53226, USA.
authors.forename: Margaret A
authors.initials: MA
authors.lastname: Carmody
authors.forename: Michael D
authors.initials: MD
authors.lastname: Martin
authors.forename: Christopher E
authors.initials: CE
authors.lastname: Wolfla
mesh_terms: D001863:Bone Screws / Q000592:standards / Q000639:trends*; D001270:Cervical Atlas / Q000473:pathology / Q000601:surgery*; D005260:Female; D006801:Humans; D008875:Middle Aged; D009809:Odontoid Process / Q000293:injuries / Q000473:pathology / Q000601:surgery*; D016103:Spinal Fractures / Q000473:pathology / Q000503:physiopathology / Q000601:surgery*; D013123:Spinal Fusion / Q000295:instrumentation* / Q000379:methods; D014711:Vertebral Artery / Q000002:abnormalities*