Pediatric Atlanto-Occipital Dissociation

  • Etiology: Trauma causing separation of skull base from cervical spine
  • Imaging Radiograph:
    — Frequently missed on initial lateral cervical spine radiographs
    — Basion dens interval should be greater than 12 millimeters on radiograph to make the diagnosis
  • Imaging CT:
    — Basion dens interval should be greater than 8.5 millimeters on CT to make the diagnosis
    — May have a retroclival hematoma associated with it
  • DDX:
  • Complications:
    — Can be fatal due to devastating neurologic sequelae if not recognized and treated
  • Treatment:
  • Clinical: Less than 1% of cervical spine trauma

Radiology Cases of Atlanto-Occipital Dissociation

CT of atlanto-occipital dissociation
Coronal CT without contrast of the cervical spine (above left) shows a fracture through the left occipital condyle with the fracture fragment displaced inferiorly. Additionally, the occipital condyles do not articulate with the lateral masses of the C1 vertebral body. Left sagittal CT (above middle) again shows the left occipital condyle fracture and increased space between the left occipital condyle and the left lateral mass of C1. Right sagittal CT (above right) shows even more clearly the increased space between the right occipital condyle and the right lateral mass of C1. Midline sagittal CT (below) shows the basion-dens interval to be abnormally increased.