Clinical and pathological evaluation of periodic synchronous discharge observed in advanced dementia of Alzheimer type

Abstract

Among 78 carefully diagnosed dementia of Alzheimer type (DAT) patients, periodic synchronous discharges (PSD) on electroencephalograms (EEGs) were observed in 12 advanced cases. Although several case studies have been made since 1970, it is not widely recognized that PSD can be observed in advanced DAT patients. In this study the clinical picture, the nature of PSD, background activity of EEGs and 2 autopsied cases have been clinicopathologically investigated. The mean duration of the disease in the 12 cases was 6.7 years. The mean age of onset of the disease was 67 years of age. Among the 12 cases, 9 patients presented akinetic mutism or symptoms closely resembling akinetic mutism, who were completely bed-ridden with their extremities fixed in flexion. The other 3 patients were severely demented. They presented various degrees of Parkinsonian syndromes or paratonic rigidity accompanied by some infection and general fatigue. In one of these 3 patients, PSD were observed during the transient apallic state and the PSD themselves were also transient. The basic rhythm in EEGs were 4-6 c/s: middle amplitude theta waves dominant with delta waves on frontal leads. Triphasic delta, theta and sharp waves of PSD were dominant on centro-parieto-occipital leads. Background activity was not suppressed differing from that of Creutzfeld Jacob disease (CJD). According to the interval histograms of PSD, the majority presented an interval of 1-2 s (1.5 s mean) with some lability which was relatively slower than that of CJD. Fronto-parieto-occipital delay was not observed. By 1 c/s photic stimulation, PSD was not driven.(ABSTRACT TRUNCATED AT 250 WORDS)