Homonymous Hemianopsia Due to the Infarction in the Splenium of the Corpus Callosum.

The precise functions of the splenium of the corpus callosum (CC) remain unclear, and infarction of this location manifests varied clinical symptoms. We describe a rare case of right homonymous hemianopsia resulting from pure infarction in the right-side splenium of the CC. An 85-year-old man presented with right homonymous hemianopsia lasting for a week. Diffusion-weighted imaging showed a high-intensity area in the right-side splenium of the CC and did not show any other lesions in other portions of the visual pathways. Magnetic resonance angiography demonstrated anterior and posterior cerebral arteries, indicating that no large vessel occlusion existed. The visual field examination revealed right homonymous hemianopsia. The diagnosis was atherothrombotic infarction in the splenium of the CC, which resulted in right homonymous hemianopsia. Two months later, T2-weighted imaging showed a high-intensity lesion localizing the right-side splenium with shrinkage of the lesion compared to that on the acute phase, and his visual field was slightly improved. There are few reports on the splenial infarction of the CC, and this is the first case manifesting as homonymous hemianopsia, to our knowledge. Our case might help to understand complicated visual information processing involving the splenium of the CC.