Abstract

A 61-year old engineer was referred for a fourth opinion regarding visual symptoms. He had a recent history of depression, and was taking fluoxetine. He reported an eight-year history of progressive visual symptoms, manifest particularly as difficulty judging distances and depth. He acknowledged visual misperceptions and rare visual hallucinations; his reading had deteriorated; he complained of loss of mathematical skills. There had been episodic topographical disorientation. Memory and insight were preserved. There were no extrapyramidal symptoms. Examination (see video) revealed evidence of significant parietal and some frontal dysfunction. Visuospatial and visuoperceptual impairments were particularly marked. There was no evidence of parkinsonism. A diagnosis of posterior cortical atrophy (PCA) syndrome was made. Structural imaging was reported as normal but SPECT imaging revealed bilateral presynaptic dopaminergic denervation and FDG-PET demonstrated significant parieto-occipital hypometabolism. CSF tau and beta-amyloid levels were normal. A diagnosis of probable dementia with Lewy bodies (DLB) was made. PCA is a relatively rare and often under-recognised neurodegenerative syndrome, most frequently associated with Alzheimer pathology. The clinical and paraclinical findings in this case suggest a Lewy body process, which very rarely presents as PCA. The challenges pertaining to the accurate diagnosis of PCA and the implications for management are discussed.