title: Symptomatic vertebral artery compression by the rod of a C1-C2 posterior fusion construct: case report and review of the literature.
abstract: METHODS
  Case report.
  
  
  OBJECTIVE
  To report a rare complication of atlantoaxial fusion.
  
  
  BACKGROUND
  Vertebral artery injury is a serious complication of screw-based atlantoaxial fusion. To our knowledge, injury to the vertebral artery has only been described as a result of screw placement. We describe the first case of atlantoaxial fixation complicated by symptomatic and reversible external compression of the vertebral artery by the rod in a Harms construct.
  
  
  METHODS
  Medical records and imaging reports were reviewed.
  
  
  RESULTS
  A neurologically intact 84-year-old woman presented after a ground-level fall. Imaging revealed a nondisplaced type II odontoid fracture associated with a C1 ring fracture. She underwent a minimally invasive Harms atlantoaxial fusion. After surgery, she developed fluctuating level of consciousness in the setting of an otherwise normal neurologic and metabolic workup. A computed tomographic angiogram was obtained and showed good screw placement except for compression of the right vertebral artery from the right transfixing rod causing 75% luminal narrowing. She underwent a revision with rod shortening, and after surgery, improved neurologically, without any further episodes of altered mental status.
  
  
  CONCLUSIONS
  In atlantoaxial fusion, the incidence of vertebral artery compression by the rod component of fusion construct may be underreported because it is difficult to detect with noncontrast computed tomography without computed tomographic angiography, which is not routinely obtained unless there is a high suspicion for vascular injury. We recommend inserting the rods with the cut (sharp) end pointing inferiorly, to avoid lacerating the vertebral artery. A vertebral artery compression from the rod in the absence of screw violation of the foramen transversarium should be considered in a patient with altered mental status after atlantoaxial fusion.
authors.affiliation: Department of Neurological Surgery, Keck School of Medicine, University of Southern California, Los Angeles, CA, USA. sterterov@mednet.ucla.edu
authors.forename: Sergei
authors.initials: S
authors.lastname: Terterov
authors.forename: Alexander
authors.initials: A
authors.lastname: Taghva
authors.forename: Alexander A
authors.initials: AA
authors.lastname: Khalessi
authors.forename: Patrick C
authors.initials: PC
authors.lastname: Hsieh
mesh_terms: D000369:Aged, 80 and over; D001157:Arterial Occlusive Diseases / Q000209:etiology* / Q000473:pathology; D001268:Atlanto-Axial Joint / Q000002:abnormalities; D001858:Bone Nails / Q000009:adverse effects*; D002574:Cervical Vertebrae / Q000473:pathology / Q000601:surgery*; D003251:Constriction, Pathologic / Q000209:etiology / Q000473:pathology; D005260:Female; D006801:Humans; D007431:Intraoperative Complications / Q000209:etiology* / Q000473:pathology / Q000517:prevention & control; D009809:Odontoid Process / Q000293:injuries; D011183:Postoperative Complications; D012086:Reoperation; D016103:Spinal Fractures / Q000601:surgery; D013123:Spinal Fusion / Q000009:adverse effects / Q000295:instrumentation / Q000379:methods; D016896:Treatment Outcome; D014711:Vertebral Artery / Q000473:pathology*