EEG in presenile dementia related to cerebral blood flow and autopsy findings

Abstract

EEG, regional cerebral blood flow (rCBF) and neuropathological autopsy data were studied in 17 patients with presenile dementia. RCBF was measured in 14 cases using the intra-arterial-133-Xenon clearance technique. The neuropathological study included semi-serial whole brain microscopical sections in which the severity and regional distribution of the neuronal degeneration was studied, particularly in the cortex and the brain stem. There were two main diagnostic groups, seven cases of Alzheimer's disease and five cases with a cortical atrophy of the Pick (DFT) type. Both groups showed fronto-temporal cortical degeneration. In addition the Alzheimer group showed severe postcentral and posterior-temporal loss of neurons. There were also three cases with degenerative changes, suggesting Jacob-Creutzfeldt's disease. The Alzheimer cases had EEG abnormalities which progressed slowly. In contrast, the Pick (DFT) patients had normal EEGs which remained so even late in the course when the signs of dementia were marked. A positive correlation between rCBF reduction in postcentral areas (as evidence of neuronal loss in these regions) and an increase of EEG abnormality could be established. Degenerative changes confined to frontal and anterior-temporal cortical regions with concomitant flow reduction, on the other hand, appeared to leave the alpha rhythm essentially undisturbed. Finally, the relationship between bifrontal delta-episodes in EEG and neuropathological evidence of brain stem lesions was confirmed.