Traumatic Basilar Artery Entrapment without Longitudinal Clivus Fracture: A Case Report and Review of the Literature

In blunt cerebrovascular injury, reported traumatic basilar artery occlusions have involved dissection of the basilar artery, distal embolization due to traumatic vertebral artery dissection, or entrapment of the basilar artery into the clivus fracture. To date, however, there are no reports of traumatic basilar artery entrapment without a clivus fracture. Here, we report the first case of traumatic basilar artery occlusion caused by entrapment into an originally existing bone defect. A 67-year-old man with a history of treatment for intracranial aneurysm suffered multiple traumatic injuries in a fall. On arrival at our hospital, he presented with neurogenic shock with quadriplegia. Computed tomography (CT) showed small epidural hematoma, C4-6 cervical spinous process fracture, and Th2-3 vertebral body fracture. CT angiography revealed occlusion of the basilar artery trunk. As vertebrobasilar artery dissections and clivus fracture were not observed; however, we could not elucidate the pathology of the basilar artery occlusion. On day 4, after surgery for the cervical and thoracic lesions, he exhibited consciousness disturbance. Diffusion-weighted imaging on day 5 showed hyperintensities in the brainstem and cerebellum. Basiparallel anatomic scanning magnetic resonance imaging showed that the basilar artery, while lacking vascular wall injuries, was tethered into the clivus. Antithrombotic therapy was performed, but the patient progressed to a locked-in state. Previous head CT before the trauma revealed a bone defect already present in the clivus. We speculated basilar artery entrapment into this preexisting bone defect. We must look for basilar artery injury in trauma patients even in the absence of clivus fracture.