Os odontoideum

FACTS

  • Definition: round/oval ossicle w/ smooth cortical margins separate from base of odontoid
  • Can lead to atlantoaxial instability, because the odontoid is no longer firmly attached to C2
  • associated syndromes: Down’s Syndrome, Klippel-Feil syndrome, Morquoi syndrome

HPI

  • universal ROS
    • neck pain
    • HA
    • abnormal posture
    • myelopathy (mJOA)
    • trauma history in childhood
    • is this the first time we discover this?
    • infants: unsteady crawling/walking
    • impaired vision, hearing, fainting

PHYSICAL EXAM

  • universal spine exam
    • extra attention to myelopathy

IMAGING

  • Can be seen on XR Spine, CT, MRI
A/P
  • Asymptomatic, stable cases: Often monitored with serial imaging.
  • Symptomatic / unstable: fuse
    • must fuse in Down’s Syndrome