Abstract
We report a case of a 65-year-old right-handed man who developed a left posterior cerebral artery infarct and subsequently developed associative visual agnosia that evolved to optic aphasia. MRI revealed lesions around the interior of the left lateral occipital lobe, the splenium of the corpus callosum, and the thalamus. Approximately 2.5 months after the onset, the patient's visual naming ability was severely impaired, although tactile naming, auditory naming, and naming of objects in response to verbal descriptions were preserved. He could copy geometric figures and distinguish matching forms from differing forms. However, he could not categorize visually presented pictures. These results suggested that his visual form perception was preserved and that his visual agnosia involved associative disturbance in processing visual form perception to semantic memory. Approximately 3.5 months after the onset, he could gradually determine with certainty whether he had ever seen the stimulus presented, that is, his subjective familiarity recovered. He could simultaneously point to and describe pictures named by the examiner. Approximately 4.5 months after the onset, he could categorize visually presented pictures that he could not name. The disturbance in visual recognition gradually improved, with visual agnosia evolving to optic aphasia. The improvement observed in this patient appeared to be affected by the semantic potential of his right hemisphere, which was in compliance with De Renzi's hypothesis. Although the patient could categorize visually presented pictures and the disturbance in visual recognition improved to some extent, the deep test results showed that the visual recognition in the right hemisphere was more incomplete and less developed than the verbal recognition in the left hemisphere. Optic aphasia leads to difficulties in visual naming although it is possible to visually recognize pictures, ; therefore, we thought that the recognition in the right hemisphere was too incomplete to name the visually presented pictures.
