Atlanto-occipital dissociation

Background

• Is an unstable spine injury
• Also referred to as internal decapitation
• Down syndome predisposes to atlanto-occipital dislocation

Clinical Features

• Often associated w/ brain injury

Differential Diagnosis

Vertebral fractures and dislocations types

Vertebral anatomy.

Numbering order of vertebrae.

• Cervical fractures and dislocations
  • Atlanto-occipital dissociation
  • C1
    • Jefferson fracture
    • C1 isolated anterior arch fracture
    • C1 isolated posterior arch fracture
  • C2
    • Odontoid fracture
    • Hangman's fracture
  • C3-C7
    • Cervical burst fracture
    • Cervical spinous process fracture
    • Extension cervical teardrop fracture
    • Flexion cervical teardrop fracture
    • Anterior cervical wedge fracture
  • Cervical facet dislocation
  • Isolated transverse process fracture
• Thoracic and lumbar fractures and dislocations
  • Chance fracture
  • Thoracic burst fracture
  • Lumbar burst fracture
  • Isolated transverse process fracture
  • Thoracic and lumbar compression fractures

Workup

Atlanto-occipital Dissociation

• Evaluate with the Powers ratio
  • Ratio of BC:OA > 1 suggests anterior subluxation
  • BC = distance between basion and midpoint of C2 post laminar line
  • OA = Distance between opisthion and ant arch of C2
• Basion to dens interval of > 10mm

Management

Prehospital Immobilization

See the NAEMSP National Guidelines for Spinal Immobilization

Hospital

• C-collar
• Consult ortho or spine as needed

Disposition

• Admit

See Also

• Spinal Cord Trauma
• Neurogenic Shock
• C-Spine X-Ray
• Unstable spine fractures
• Cervical spine injuries