Independent predictors of survival after traumatic atlanto-occipital dissociation

Atlanto-occipital dissociation (AOD) occurs when the skull base is forcibly separated from the vertebral column. Existing literature on AOD is sparse and risk factors for mortality are unknown. This study determined independent predictors of survival after AOD.

Patients who sustained AOD were identified from the National Trauma Data Bank (2007-2014). Those arriving without signs of life or with missing mortality data were excluded. Study groups were defined as patients who survived to hospital discharge versus patients who died in hospital. Demographics, injury data, interventions, and outcomes were compared between groups using univariate analysis. Multivariate logistic regression was used to determine independent predictors of survival.

After applying exclusion criteria, 1,489 patients (<1% of National Trauma Data Bank) were identified. Median age was 37 years (interquartile range [IQR), 20-59 years], and 59% of patients were male. Atlanto-occipital dissociation occurred almost exclusively after blunt mechanisms (97%), most commonly motor vehicle collisions (66%). Median injury severity score (ISS) was 25 (IQR, 10-36), with 22% mortality. Median time to death was 1,358 minutes (IQR, 281-4,451 minutes), approximately 23 hours. Independent predictors of survival were higher Glasgow Coma Scale score on admission (p < 0.001), lower ISS (p = 0.011), lower Abbreviated Injury Scale score for the head (p = 0.001), and the lack of need for exploratory laparotomy (p < 0.001). Time to neurosurgical intervention of the spine was not predictive of survival (p > 0.05). Patients who survived had a median hospital length of stay of 5 days (IQR, 1-14 days) and intensive care unit length of stay of 1 day (IQR, 0-7 days). The most common discharge destination was home (n = 393 [34%]).

Traumatic AOD is not uniformly fatal, with 78% of patients who arrive alive to hospital surviving to discharge. When death occurs, it is typically within the first 23 hours. Lower ISS and higher Glasgow Coma Scale score on admission independently predict survival, while time to neurosurgical intervention does not. Survivors have a short hospital stay and are commonly discharged home. This study suggests that AOD among patients who arrive alive to hospital may not be as devastating as previously considered.

Progonostic/Epidemiological, level III; Therapeutic, level IV.