The Electroencephalogram in Diffuse Encephalopathies

Abstract

Introduction This report deals with clinical and laboratory findings in a group of 11 patients who were seen at the Neurological Institute between 1950 and 1956. The patients, all of whom suffered from encephalopathies, had in common distinctive abnormalities in the electroencephalogram (EEG), namely, periodic synchronous bursts of high-amplitude slow-wave activity, at times irregular in pattern but usually with spike-and-wave-like components. The bursts in most instances lasted for a few seconds and recurred periodically every 5 to 10 seconds. Between these bursts depressed activity was seen. The underlying illnesses represent a wide range of etiologies, apparently unrelated. The clinical course and final outcome also varied widely. Upon analysis of the clinical features, however, a number of similarities among the cases were found, namely, "organic" mental impairment, myoclonic seizures and generalized convulsions, choreoathetoid dyskinesia, and rigidity. While all these features did not occur in all cases, most of them were present