Mechanism and patterns of cervical spine fractures-dislocations in vertebral artery injury

PURPOSE: To identify the fracture patterns and mechanism of injury, based on subaxial cervical spine injury classification system (SLIC), on non-contrast computed tomography (NCCT) of cervical spine predictive of vertebral artery injury (VAI). PATIENTS AND METHODS: We retrospectively analyzed cervical spine magnetic resonance imaging (MRI) of 320 patients who were admitted with cervical spine injury in our level I regional trauma center over a period of two years (April 2010 to April 2012). Diagnosis of VAI was based on hyperintensity replacing the flow void on a T2-weighted axial image. NCCT images of the selected 43 patients with MRI diagnosis of VAI were then assessed for the pattern of injury. The cervical spinal injuries were classified into those involving the C1 and C2 and subaxial spine. For the latter, SLIC was used. RESULTS: A total of 47 VAI were analyzed in 43 patients. Only one patient with VAI on MRI had no detectable abnormality on NCCT. C1 and C2 injuries were found in one and six patients respectively. In subaxial injuries, the most common mechanism of injury was distraction (37.5%) with facet dislocation with or without fracture representing the most common pattern of injury (55%). C5 was the single most common affected vertebral level. Extension to foramen transversarium was present in 20 (42.5%) cases. CONCLUSION: CT represents a robust screening tool for patients with VAI. VAI should be suspected in patients with facet dislocation with or without fractures, foramina transversarium fractures and C1-C3 fractures, especially type III odontoid fractures and distraction mechanism of injury.