We aimed to describe the findings of traumatic atlanto-occipital dislocation (AOD) on cervical spine CTs and differences leading to varying treatment of these patients.
We retrospectively identified 20 adult patients with AOD from cervical spine CTs demonstrating fracture or fracture dislocations over 19 years at 2 major trauma centers. Medical records were reviewed and craniovertebral junction (CVJ) metrics measured on CT. Intubation, Glasgow Coma Scale (GCS), additional injuries, occiput/atlas/axis fracture, concurrent atlantoaxial subluxation, vascular injury on CT angiography, and ligamentous injury on MRI were noted.
Using the Traynelis Classification, eight patients had type 2 and eight patients type 3 AOD. Four of 5 patients who died within 14 days of CT had type 2 AOD. Three patients had medial/lateral AOD. Of the patients who survived initial injuries, a greater percentage who underwent surgical or halo fixation versus non-operatively treated patients had abnormal CVJ measurements including BDI (62.5% vs 0%), atlantoaxial subluxation (75% vs 14.3%), ligamentous injury (80% vs 66.7%), intubation (62.5% vs 28.6%), GCS<8 (62.5% vs 14.3%), and additional injuries (75% vs 71.4%) on presentation. MRI helped identify 2 cases of type 2 AOD and surgical decision making in 8 cases.
Types 2 and 3 were the most common, and type 2 is the deadliest type of AOD. A greater proportion of patients who undergo surgical or halo fixation have abnormal CT/MR findings with neurologic impairment at presentation. MRI aided detection of potentially missed type 2 AOD and was critical for surgical decision making.
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Type 1 AOD: anterior displacement of the occiput relative to the atlas. Type 2 AOD: vertical distraction of the occiput from the atlas. Type 3 AOD: posterior displacement of the occiput relative to the atlas .
The distance between the anterior cortex of the dens and the posterior cortex of the C1 anterior arch .
The distance between the basion and posterior arch of the atlas divided by the distance between the opisthion and the anterior arch of the atlas 
An abnormal X-line is defined as lack of intersection both between the posterosuperior surface of the dens with a line drawn from the basion to the C2 spinolaminar junction, and between C1 and a line drawn between the opisthion and the inferoposterior aspect of the C2 vertebra 
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Availability of data and material
Our database is accessible to all employees of the two tertiary centers from which electronic medical records were obtained.
The dislocation database for this study was funded by GE Healthcare LLC.
Approval was obtained from the institutional review board at our institution.
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The authors declare that they have no conflict of interest. Bharti Khurana- GE Healthcare Research Support; Book Royalties, Cambridge University Press; Section Editor Royalities, UptoDate, Wolter Kluwer.
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Tang, A., Tobert, D., Kakarmath, S. et al. Radiological and clinical features of traumatic atlanto-occipital dislocation. Emerg Radiol (2021). https://doi.org/10.1007/s10140-021-01912-7
- Atlanto-occipital dislocation
- Cervical spine CT
- Craniovertebral junction measurements
- Vascular injury
- Ligamentous injury
- Instrumented surgical fixation