Atlanto-occipital dissociation

Abstract

Introduction: Atlanto-occipital dissociation (AOD) is a rare and unstable injury of the craniocervical junction, associated with very high morbidity and mortality. The most common cause of this injury is high energy trauma with hyperextension of the cranium, such as car accidents. Due to specific anatomical predispositions, children and young adults are the frequently affected populations. Improving pre-hospital and early emergency care has resulted in a higher sensitivity of AOD diagnosis.

Methods: A retrospective analysis of all patients with cervical spine trauma, treated at the Masaryk Hospital Trauma Center between 2008 and 2018, identified 7 patients with AOD. The cohort consisted of 5 males and 2 females, with a mean age of 19,6 years and with the age range 9 to 35 years. All cases occurred as a result of a car accident.

Results: All patients in the cohort had findings of a highly unstable C0-C1 injury on their CT scans on admission. Four patients died early, while undergoing CPR in the emergency department. Two patients were in severe neurological states, with lesions of the upper cervical spinal cord and medulla oblongata on MRI. These patients were treated with external halo fixation and died within 3 days of the trauma. Only one patient with a new progressive neurological deficit was successfully treated using acute occipitocervical stabilization and fusion.

Conclusion: The increasing incidence of AOD requires an early diagnosis, which minimizes the risk of successive clinical deterioration. The diagnostic method of choice is the C1-condyle interval (CCI) CT assessment along with cervical spine MRI. Standard treatment of stable patients with unstable AOD injuries consists in posterior occipitocervical stabilization and fusion of C0-C2.

Keywords: atlanto-occipital dissociation; craniocervical junction; occipitocervical fusion; upper cervical spine.