Survival of atlanto-occipital dissociation correlates with atlanto-occipital distraction, injury severity score, and neurologic status

Background: Case series suggest that atlanto-occipital dissociation (AOD) is a potentially survivable injury. Intuitively, a significant neurologic injury, a high degree of initial distraction, and more severe associated injuries would decrease the likelihood of survival. However, this has never been demonstrated for this injury pattern in a statistically meaningful way. The purpose of this study was to assess the relationship of atlanto-occipital distraction, presence of a complete neurologic injury, and Injury Severity Score (ISS) to the rate of survival in AOD. Methods: One thousand one hundred seventy-four patients from 2005 to 2009 comprehensive trauma database were retrospectively reviewed. Fourteen patients diagnosed with AOD were included in the study. Outcome measures assessed included survival, neurologic status, and ISS. The basion-dens interval (BDI) was measured on the computed tomography scan. Fisher's exact test and Wilcoxon's test were used to evaluate possible associations. Results: Six patients died with complete, high cervical, spinal cord injuries. Follow-up for survivors ranged from 6 months to 2 years. Mortality was associated with the presence of complete neurologic deficit (p = 0.0047), a high basion-dens interval (>16 mm, p = 0.015), and a high ISS (p = 0.0373). Conclusions: AOD is a potentially survivable injury; however, there may be identifiable subsets of patients where the injury is so severe that treatment is unlikely to change the outcome. This is the first study to show that the ISS and the presence of a complete neurologic injury correlate with nonsurvivability of this devastating injury. A larger case series would help to generalize the results, given the small sample size.