Posterior Cortical Atrophy: Unusual Feature of Alzheimer's Disease

We present two patients with symptoms suggestive of bilateral posterior cortical dysfunction: loss of topographic familiarity, alexla, progressive visual agnosia for objects and pictures, agraphia, visuospatial compromise. Colour agnosia and prosopagnosia were present in one case. Primary motor and sensory modalities were intact. Within a few years, constructional apraxia, Baht's syndrome, components of Gerstmann's syndrome and transcortical sensory aphasla progressively appeared. Mild memory impairment was present early In the course of the disease but gradually worsened and late clinical presentation was consistent with end-stage dementia, but with preserved insight and judgement. Predominant parieto-occipital atrophy was demonstrated on CT scan. Cerebral biopsy of the frontal lobe showed typical Alzheimer-type changes in the two cases. Late clinical features of mild or severe dementia and the results of biopsy examination suggested Alzheimer's disease, but initial progressive parleto-occipital dysfunctlon supported the concept of posterior cortical atrophy. These cases suggest that posterior cortical atrophy could be an unusual initial feature of Alzheimer's disease.