Vertebral artery injury after acute cervical spine trauma: rate of occurrence as detected by MR angiography and assessment of clinical consequences.

OBJECTIVE The purposes of this study were to assess prospectively the frequency of vertebral artery injuries after major acute cervical spine trauma as determined by MR angiography and to assess the clinical consequences of these injuries. SUBJECTS AND METHODS During a 6-month period, 37 patients who had major acute nonpenetrating cervical spine trauma were examined with MR imaging, usually within 24 hr of the injury. Routine spin-echo and gradient-echo images were supplemented by two-dimensional time-of-flight MR angiography of the extracranial head and neck vessels. The vertebral arteries were independently assessed by two neuroradiologists for nonvisualization, focal narrowing, or focal widening. Two patients had conventional angiographic correlation. The medical records of these 37 patients were also reviewed to determine the type of spinal injury, neurologic deficit on admission, and evidence of an intracranial neurologic deficit due to vertebral artery injury. The MR angiograms of 37 control subjects were interpreted to help determine the specificity of MR angiography; those studies were assessed only for the presence or absence of the vertebral arteries. RESULTS Findings on MR angiograms were abnormal in nine patients (24%). In seven cases, one vertebral artery was diagnosed as nonvisualized (occluded) or focally narrowed; one patient had bilateral vertebral artery injuries; and one patient had nonvisualization of the left common carotid and left vertebral arteries. In all 37 control subjects, both vertebral arteries were identified on MR angiograms. A significant difference in the frequency of vertebral artery nonvisualization (occlusion) was found between the trauma and control populations. The patient with bilateral vertebral artery injuries died 2 days after hospital admission of a massive infarction of the right cerebellar hemisphere. The other eight patients with vertebral artery injuries, and the remaining 28 patients with normal findings on MR angiograms, had no intracranial neurologic deficits that could be ascribed to a major arterial injury. CONCLUSION In our experience, vertebral artery injuries due to major cervical spine trauma as determined by MR angiography are common. Although these vascular abnormalities usually remain clinically occult, a small percentage of patients may suffer devastating neurologic complications of posterior fossa infarction. Noninvasive assessment of the vertebral arteries by means of MR imaging should be an integral part of the evaluation of the acutely injured cervical spine.