View source for Atlanto-occipital dissociation

==Background==
*[[Unstable spine fractures]]
*Tectorial membrane and alar ligaments provide stability to atlanto-occipital joint
**Injury or laxity of these ligaments can lead to subluxation or dislocation
*Also referred to as internal decapitation
*[[Down syndrome]] predisposes to atlanto-occipital dislocation

{{Vertebral fractures and dislocations types}}

==Clinical Features==
*Pure flexion injury involving C1-C2, with or without [[odontoid fracture]]
*Often associated with brain injury, which predicts mortality<ref>Mendenhall, S. K., Sivaganesan, A., Mistry, A., Sivasubramaniam, P., McGirt, M. J. and Devin, C. J. (2015) ‘Traumatic atlantooccipital dislocation: Comprehensive assessment of mortality, neurologic improvement, and patient-reported outcomes at a level 1 trauma center over 15 years’, The Spine Journal, 15(11), pp. 2385–2395</ref>

==Differential Diagnosis==
{{Blunt neck trauma DDX}}

==Evaluation==
[[File:Atlanto-occipital Dissociation.jpeg|thumbnail|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 <ref>Riascos R, Bonfante E, Cotes C et-al. Imaging of Atlanto-Occipital and Atlantoaxial Traumatic Injuries: What the Radiologist Needs to Know. Radiographics. 2015;35</ref>

==Management==
===Prehospital Immobilization===
See the [[EBQ:Prehospital Spine Immobilization|NAEMSP National Guidelines for Spinal Immobilization]]

===Hospital===
{{Unstable cervical spine fracture management}}

==Disposition==
*Admit

==See Also==
*[[Spinal Cord Trauma]]
*[[Neurogenic Shock]]
*[[C-Spine X-Ray]]
*[[Unstable spine fractures]]
*[[Cervical spine injuries]]

==External Links==

==References==
<references/>

[[Category:Trauma]]
[[Category:Orthopedics]]