Associative Visual Agnosia

Following an acute hypotensive episode, a patient had unusual residual visual difficulties. A right homonymous hemianopsia was the only primary neurologic deficit, but there were specific behavioral disturbances. He could not read but could write (alexia without agraphia), had difficulty in color recognition (color agnosia), facial recognition (prosopagnosia), and object recognition (visual agnosia). Despite these visual disturbances, adequate primary visual function was demonstrated by his ability to copy drawings. Clinical evidence suggests that the underlying lesion was infarction involving the left medial occipital region and the splenium of the corpus callosum. The possibility of a second lesion in the right hemisphere can be conjectured but not supported by available data. Inability to identify or recognize visually presented objects with preservation of ability to draw them is unusual and can best be termed associative visual agnosia. Key Words.— Visual agnosia; prosopagnosia; color agnosia; alexia without agraphia; corpus callosum.