[A case of incarceration of the vertebral and basilar arteries in a longitudinal fracture of the clivus].

We report a case of incarceration of the right vertebral and basilar arteries in a longitudinal fracture of the clivus. A 80-year-old man was struck on the occiput in a traffic accident and was admitted to our hospital. He was in coma on admission. Neurological examination revealed that the left pupil was dilated, the light reflex was bilaterally sluggish, the left corneal reflex was absent, and the pharyngeal reflex was absent. Computed tomography showed fractures in the occipital bone and clivus. His general condition rapidly deteriorated, and he died 4 hours after the injury. The autopsy revealed a longitudinal fracture of the clivus incarcerating the right vertebral artery together with the origin of the basilar artery. It also revealed primary brain stem injury. We presented clinical features, mechanisms of the injury, and radiological findings for three types of clivus fracture; longitudinal, transverse, and a fracture of the lower clivus extending into the occipital condyle. It is unusual to see incarceration of the basilar or the vertebral artery in a longitudinal fracture of the clivus. We found only five reported cases. Each case presented a variety of brainstem dysfunctions. Three died of brainstem infarction, and one died of aspiration pneumonia. The remaining patient is in a chronic vegetative state. In our case, the history and autopsy findings suggested that the patient died of the primary brainstem injury. We proposed two mechanisms of incarceration; one is a midline occipital blow as in our case, and the other is axially transmitted force.