Prosopagnosia

[A patient with prosopagnosia which developed after an infarction in the left occipital lobe in addition to an old infarction in the right occipital lobe]

A 66-year-old, right-handed male, was admitted to our hospital with difficulty in recognizing faces and colors. He had suffered a stroke in the right occipital region three years earlier that had induced left homonymous hemianopsia, but not prosopagnosia. A neurological examination revealed prosopagnosia, color agnosia, constructional apraxia, and topographical disorientation, but not either hemineglect or dressing apraxia. The patient was unable to distinguish faces of familiar persons such as his family and friends, as well as those of unfamiliar persons such as doctors and nurses. Brain MRI demonstrated an old infarction in the right medial occipital lobe and a new hemorrhagic infarction in the left medial occipital lobe, including the fusiform and lingual gyrus. It is unclear whether a purely right medial occipital lesion can be responsible for prosopagnosia, or whether bilateral medial occipital lesions are necessary for this occurrence. The current case indicated that bilateral medial occipital lesions play an important role in inducing porsopagnosia.

Prosopagnosia without topographagnosia and object agnosia associated with a lesion confined to the right occipitotemporal region

A patient is presented who developed prosopagnosia with a recent occipitotemporal infarct in the distribution of the right posterior cerebral artery. He did not have topographical agnosia or object agnosia. He regained the ability to recognize faces of familiar persons, whereas he remained unable to identify faces of persons whom he met after the disease onset. This case demonstrates that prosopagnosia may occur as a deficit of matching a perceived face to a memory store of the face, and that the failure to recognize unfamiliar faces may be due to the inability to form memory stores of new faces. These deficits can occur in association with a lesion confined to the right occipitotemporal region.

Are unilateral right posterior cerebral lesions sufficient to cause prosopagnosia? Clinical and radiological findings in six additional patients

Controversy has arisen regarding the neuropathological basis of prosopagnosia. Some investigators suggest that bilateral lesions are needed to cause the deficit, whereas others felt that a unilateral right posterior lesion is sufficient. Six patients with prosopagnosia with clinical and radiological evidence of unilateral right posterior lesions are presented. Our observations together with evidence from similar cases described in the literature suggest that an appropriately placed right hemispheric lesion may be sufficient to produce prosopagnosia.

Is prosopagnosia more frequent in males than in females?

A case review of prosopagnosia was carried out and male-female incidence of the disorder compared to relative male-female incidence of cerebro-vascular disease in general. Prosopagnosia was found to occur significantly more frequently in males than in females. Possible implications of this finding vis-à-vis male-female differences in cerebral organization are discussed and topics for further investigation are suggested.