title: Craniocervical junction subarachnoid hemorrhage associated with atlanto-occipital dislocation.
abstract: METHODS
  The sensitivity of plain radiographs for diagnosing traumatic atlanto-occipital dislocation and its association with craniocervical junction subarachnoid hemorrhage was examined in a retrospective review of seven patients.
  
  
  OBJECTIVE
  The purpose of this study was to demonstrate the frequency of nondiagnostic plain radiographs and the common association of craniocervical junction subarachnoid hemorrhage in the context of reported cases of atlanto-occipital dislocation to facilitate better recognition of this injury. The use of sagittal reconstructions of computed tomography or sagittal magnetic resonance imaging for diagnosis was evaluated.
  
  
  BACKGROUND
  Although traumatic atlanto-occipital dislocation is a common cause of motor vehicle fatalities, survival has been more common in the last 16 years. However, the diagnosis was missed on lateral cervical radiographs in 38% of children and 59% of adults; fewer than half were diagnosed subsequently with plain radiography. Moreover, the diagnosis of traumatic atlanto-occipital dislocation often was not considered, because more than half of the survivors had no neurologic abnormality or unilateral deficit. Consequently, more than one third of initially undiagnosed patients experienced neurologic deterioration due to inadequate cervical immobilization. Additional radiographic studies allowing diagnosis were prompted by the neurologic worsening.
  
  
  METHODS
  The authors reviewed seven patients treated with traumatic atlanto-occipital dislocation during a 14-year period. Emergency department records were compared with reexamination of initial cervical radiographs to determine the success in diagnosis by means of published methods. The frequency of cranio-cervical junction subarachnoid hemorrhage on computed tomography was determined, and the use of sagittal imaging for subsequent diagnosis was evaluated.
  
  
  RESULTS
  In the emergency department, only one patient's condition was diagnosed as atlanto-occipital dislocation. Review of the initial radiographs identified an additional four patients for whom atlanto-occipital dislocation could be diagnosed. Sagittal computed tomography reconstruction or sagittal magnetic resonance imaging identified the remaining two. All but one patient had craniocervical junction subarachnoid hemorrhage. A review of reported cases revealed a common association of craniocervical junction subarachnoid hemorrhage with traumatic atlanto-occipital dislocation but not with traumatic head injury.
  
  
  CONCLUSIONS
  The diagnosis of traumatic atlanto-occipital dislocation is often missed in the emergency department, and current methods for evaluating the integrity of the atlanto-occipital joint on cervical radiographs fail to identify all patients with this injury. Although infratentorial subarachnoid hemorrhage is uncommon in traumatic head injury, craniocervical junction subarachnoid hemorrhage is often associated with atlanto-occipital dislocation and should raise the suspicion of severe craniocervical ligamentous injury. Sagittal computed tomography reconstructions or sagittal magnetic resonance imaging can allow for the diagnosis when plain radiography is inconclusive.
authors.affiliation: Department of Neurosurgery, University of Pittsburgh Medical Center, Presbyterian University Hospital, Pennsylvania, USA.
authors.forename: G J
authors.initials: GJ
authors.lastname: Przybylski
authors.forename: B L
authors.initials: BL
authors.lastname: Clyde
authors.forename: C R
authors.initials: CR
authors.lastname: Fitz
mesh_terms: D000293:Adolescent; D000328:Adult; D001269:Atlanto-Occipital Joint / Q000000981:diagnostic imaging / Q000293:injuries* / Q000473:pathology; D002574:Cervical Vertebrae; D002648:Child; D002675:Child, Preschool; D005260:Female; D005500:Follow-Up Studies; D006801:Humans; D007103:Immobilization; D004204:Joint Dislocations / Q000175:diagnosis* / Q000209:etiology; D008279:Magnetic Resonance Imaging; D008297:Male; D008875:Middle Aged; D012189:Retrospective Studies; D012886:Skull; D013345:Subarachnoid Hemorrhage / Q000175:diagnosis* / Q000209:etiology; D014057:Tomography, X-Ray Computed