Dementia with Lewy bodies studied with positron emission tomography

Objective: To report a case initially fulfilling the clinical criteria for probable Alzheimer disease, although later clinical features suggested deme ntia with Lewy bodies. Oxygen 15-labeled positron emission tomograms reveal ed a pattern of hypometabolism characteristic of Alzheimer disease. At post mortem, there was no evidence of the pathological features of Alzheimer di sease, but diffuse cortical Lewy bodies were seen in the pigmented brainste m nuclei and cerebral cortex. Design: A case report. Setting: Tertiary referral center. Patient: A 65-year-old white man presented with a 3-year history of memory loss and language difficulties. Results: Oxygen 15-labeled positron emission tomograms revealed hypometabol ism in the frontal, temporal, and parietal lobes, more severe on the left t han right. Metabolism in the left caudate was just outside the 95% referenc e range. Occipital metabolism was normal. Conclusions: Positron emission tomographic studies have been reported to sh ow occipital hypometabolism in dementia with Lewy bodies, in addition to th e characteristic posterior bitemporal biparietal pattern of Alzheimer disea se. We suggest that although this finding may favor a diagnosis of dementia with Lewy bodies, it is not necessary for diagnosis.