Atlanto-occipital dislocation

Abstract

Atlanto-occipital dislocation (AOD) is being increasingly recognized as a potentially survivable injury as a result of improved prehospital management of polytrauma patients and increased awareness of this entity, leading to earlier diagnosis and more aggressive treatment. However, despite overall improved outcomes, AOD is still associated with significant morbidity and mortality. The purpose of this paper is to review the biomechanical aspects, clinical features, radiologic criteria, and treatment strategies of AOD. Given that the diagnosis of AOD can be very challenging, a high degree of clinical suspicion is essential to ensure timely recognition and treatment, thus preventing neurological decline or death.

Keywords: Atlanto-occipital dislocation; Cervical spine; Craniocervical junction; Occipitocervical fusion; Trauma.

Figure 1

Anatomy of the craniocervical junction (reproduced with permission from Ref. [13]).

Figure 2

The Traynelis classification.

Figure 3

Diagnostic methods for atlanto-occipital dislocation (see text for details). A: Powers’ ratio; B: X-line method; C: Basion-dens interval; D: Basion-axis interval; E: Occipital condyle-C1 interval.

Figure 4

Nineteen years old woman with traumatic atlanto-occipital dislocation following high-speed motor vehicle accident. A and B: CT of the cervical spine demonstrates no significant abnormalities in the midsagittal plane (A), but clear asymmetry of the occipito-atlantal joints in the coronal plane (B). The left occipital condyle-C1 interval is increased, measuring 6 mm; C: MRI of the cervical spine (T2WI) reveals abnormal signal suggesting disruption of the cruciate ligament; D: Post-operative cervical radiographs show O-C2 fusion using bicortical occipital screws and C2 pedicle screws; E: Post-operative CT of the cervical spine demonstrates reduction of the left occipital condyle-C1 interval to 4 mm. CT: Computed tomography; MRI: Magnetic resonance imaging.