Cognitive dysfunction in a patient with brainstem hemorrhage.

A 54-year-old, right-handed male suffered sudden onset of vertigo and vomiting. He was diagnosed with brainstem hemorrhage, and treatment was administered. After the vertigo improved, he showed disturbance of attention and anterograde amnesia. Magnetic resonance imaging revealed a hematoma across the pons on both sides, but no lesions were obvious in the cerebellum or the cerebrum. Single photon emission tomography showed decreased perfusion not only in the brainstem but also in the bilateral frontal and temporal lobes. Amnesia and executive dysfunction decreased in the 8 months following the stroke onset, with improvement in regional cerebral blood flow to the frontal and temporal lobes. These findings suggest that a hemorrhage in the pons caused diaschisis resulting in a secondary reduction of activity in the cerebral cortex and the occurrence of cortical symptoms.