Abstract
We report a case of a 76-year-old man who was transferred to our emergency room in a comatose state with right hemiplegia, right pupillary dilatation, and conjugate deviation of eyes to the right. Computed tomography revealed a huge left putaminal hemorrhage extending to the frontotemporal subcortical region, with a displacement of midline structures. To elucidate the lesion responsible for the right pupillary dilatation and conjugate deviation of eyes, we performed brain magnetic resonance imaging (MRI). The coronal section of fluid-attenuated inversion recovery (FLAIR) image showed that the brainstem was distorted along with the displacement of midline structures to the right. The diffusion-weighted MRI showed a right paramedian midbrain infarction, which could have caused the right pupillary dilatation. Contralateral pupillary dilation at the onset of putaminal hemorrhage is a very rare symptom, and its mechanism remains uncertain. This report revealed that a contralateral midbrain infarction could be one of the causes of this rare symptom.
