[Non-verbal facial and topographic visual object agnosia--a problem of familiarity in prosopagnosia and topographic disorientation].

In recent years, prosopagnosia is defined as the "loss of ability to recognize the well-acquainted persons like the family members by their physiognomy." There are many reports based on this definition. However, from the viewpoint of symptomatology, there are many problems not entirely solved yet. And the mechanism of its manifestation is not clearly explained. Topographic disorientation, which often accompanies prosopagnosia, is studied even less. From the results of the postmortem examination in the literature, bilateral occipito-temporal lesions have been known to cause prosopagnosia. However, the recent radiographical examination by the computed tomography revealed that the prosopagnosia is also caused by the right occipito-temporal lesions only. We experienced a case with prosopagnosia and topographic disorientation which were considered to be caused by infarction in the territory of the right posterior cerebral artery. Detailed symptomatological, morphological and functional examinations were carried out by means of various psychological testing, X-ray computed tomography (CT), magnetic resonance imaging (MRI) and positron emission tomography (PET). The patient was a 70-year-old right-handed man who suffered from sudden visual loss on both eyes, and was admitted to our hospital after four weeks. On examination, a decrease of visual acuity and right homonymous hemianopsia were recognized. When visual acuity was recovered, he was unable to recognize the faces of his relatives and friends, with whom he has been well acquainted for many years. He also found his own house, the buildings and streets around it as entirely unfamiliar. Seven months after the onset of the disease, examination showed he had definite prosopagnosia and topographic disorientation.(ABSTRACT TRUNCATED AT 250 WORDS)