Traumatic vertebral artery injury: proposal for classification of the severity of trauma and likelihood of fatal outcome.

Vertebral artery injury (VAI) occurs after (blunt) trauma as well as spontaneously. The risk of incurring VAI from a blunt trauma probably parallels the severity of trauma, often referred to as major- and minor-trauma. However, the literature does not provide concrete definitions of these terms. This study aims to define minor- and major-trauma and to analyze the likelihood of fatal outcome in VAI. For this purpose, classification criteria of major- and minor-trauma were developed and a PubMed database search was performed for articles on VAI published prior to 2013. The definitions of minor- and major-trauma, derived mainly from radiological screening criteria in cervical spine injury and based on the mechanism leading to the injury, were used in the analysis of the literature. The search produced 241 VAI cases with sufficiently detailed data for the comparison of major-trauma (52 cases, 50 lethal), minor-trauma (8 cases, none lethal), and no-trauma (182 cases, 69 lethal). The numbers of lethal cases in the total study population and subgroups differed significantly between the groups (Fisher's exact test) and the likelihood ratios (LRs) of lethal outcome were substantially higher in the major-trauma group compared to the other groups. The highly significant p values show that the proposed criteria differentiate between trauma types with regard to fatal outcome. The presented results can assist in the evaluation of forensic cases of VAI.