Pediatric Atlanto Occipital Instability

  • Etiology: Ligamentous laxity of cruciform ligament causes occiput-C1 instability
  • Imaging:
    — Posterior translation of opisthion on extension
    — See incongruence of Wackenheim’s line
  • DDX:
  • Complications: Can cause chronic cord injury with cord narrowing
  • Treatment:
  • Clinical:
    — Can be exacerbated after minor trauma
    — Often seen in Trisomy 21

Radiology Cases of Atlanto Occipital Instability

Radiograph of atlanto occipital instability
Lateral radiograph of the cervical spine in flexion (left) shows a normal atlanto dens interval and normal relationship of the occipital condyles to the lateral masses of C1 while on extension (right) there is posterior translation of the occipital condyles in relation to the lateral masses of C1.
Radiograph of atlanto occipital instability
Lateral flexion view of the cervical spine (left) shows a normal relationship of the occipital condyles to the articular facets of the atlas. The atlanto dental interval is also normal. Lateral extension view of the cervical spine (right) shows posterior displacement of the occipital condyles in relation to the articular facets of the atlas. There is posterior positioning of Wackenheim line and retrolisthesis of the C3 on C4 vertebral body. The atlanto dental interval remains normal.