The MRI and CT evidence of primary brain stem injury.

A 61-year-old man made a good recovery from posttraumatic right hemiparesis and prolonged disturbance of consciousness. Computed tomography (CT) showed a hematoma in the interpeduncular cistern. Magnetic resonance imaging (MRI) pinpointed an injury between the left cerebral peduncle and the reticular formation. Apart from contusion, the mechanism of injury may have been disruption of the paramedian branches of the basilar artery as the brain stem impacted on the clivus during the traffic accident. In contrast with reported autopsy findings that brain stem injury must be associated with severe supratentorial brain trauma (Adams et al., Brain 1977; 100:489-502), this case suggests that primary brain stem injury may occur and run a benign course.