A case of associative visual agnosia: neuropsychological findings and theoretical considerations.

A 61-year-old right-handed man fell downstairs and was found unconscious. There was no abnormality in the general physical examinations. Neurological examinations revealed a quadrantanopia. Neuropsychological examination revealed an impairment in recent verbal memory, alexia, agraphia, object agnosia, color naming difficulty, prosopagnosia, and visuospatial constructional disability. CT scan demonstrated subcortical hematomas in the temporo-occipital regions of both hemispheres. MRI demonstrated extensive low-intensity lesions in the lingual, fusiform and posterior inferior temporal gyri on both hemispheres. Both inferior longitudinal fasciculi were also affected. His neuropsychological deficits seem best described as a typical form of associative visual agnosia. From the results of neuroradiological findings, the authors emphasize that associative visual agnosia might be produced by an intrahemispheric disconnection between the visual cortices and the temporal lobes which are supposed to be the storage site of the engrams of visual memories. Moreover, the neuropsychological findings suggest that the visuo-constructional ability to convert the two-dimensional input to the three-dimensional construction and the capacity of three-dimensional imagination were severely impaired in our patient. It was considered that these neuropsychological features play an important role in the recognition difficulties of associative visual agnosia.