Cervicovertebral Junction Instability

  • Etiology: ligamentous laxity of cruciform ligament causes occiput-C1 + C1-C2 instability in Trisomy 21
  • Imaging: Predental space (atlanto-dental interval) should be < 4 mm — Occiput-C1 instability – posterior translation of opisthion on extension, see incongruence of Wackenheim’s line — C1-C2 instability – see widening of atlanto-dens interval on flexion, atlanto-dens interval > 5 mm on any lateral c-spine is abnormal, if there is any motion at atlanto-dens interval between flexion + extension it is abnormal
  • Clinical: can be exacerbated after minor trauma, can cause chronic cord injury with cord narrowing

Cases of Cervicovertebral Junction Instability