title: Atlantoaxial instability complicating radiation therapy for recurrent nasopharyngeal carcinoma. A case report.
abstract: METHODS
  A case report of a patient in whom atlantoaxial instability developed secondary to repeat radiation therapy for recurrent nasopharyngeal carcinoma.
  
  
  OBJECTIVE
  To illustrate a dramatic and previously unreported complication of local radiation to the posterior nasopharynx.
  
  
  BACKGROUND
  Nasopharyngeal carcinoma is an unusual tumor that usually is managed with local, external-beam radiation. It is not thought to involve the cervical spine directly, although local invasion of the skull base is common.
  
  
  METHODS
  A review of the medical records and radiographs of the only patient known to develop this complication of radiation used to manage nasopharyngeal carcinoma.
  
  
  RESULTS
  Atlantoaxial instability developed in a patient as a result of repeat radiation for a locally recurrent tumor. The instability was associated with intrusion of the anterior arch of C1 into the posterior nasopharynx and was managed successfully with a posterior stabilization using transarticular screws and supplemental wiring.
  
  
  CONCLUSIONS
  Patients who have undergone local irradiation for nasopharyngeal carcinoma may be at risk for developing atlantoaxial instability.
authors.affiliation: Toronto Hospital Spine Program, Department of Surgery, University of Toronto, Canada.
authors.forename: R D
authors.initials: RD
authors.lastname: Orr
authors.forename: P T
authors.initials: PT
authors.lastname: Salo
mesh_terms: D000328:Adult; D001268:Atlanto-Axial Joint / Q000000981:diagnostic imaging / Q000473:pathology / Q000528:radiation effects*; D002294:Carcinoma, Squamous Cell / Q000175:diagnosis / Q000532:radiotherapy*; D005260:Female; D005500:Follow-Up Studies; D006801:Humans; D007593:Joint Instability / Q000175:diagnosis / Q000209:etiology* / Q000601:surgery; D008279:Magnetic Resonance Imaging; D009303:Nasopharyngeal Neoplasms / Q000175:diagnosis / Q000532:radiotherapy*; D009364:Neoplasm Recurrence, Local / Q000175:diagnosis / Q000532:radiotherapy*; D011832:Radiation Injuries / Q000175:diagnosis / Q000209:etiology*; D013123:Spinal Fusion; D014057:Tomography, X-Ray Computed