Abstract：Objective To explore the clinical significance of electroencephalographic (EEG) hypsarrhythmia and its variants. Methods We reviewed case histories of 181 patients whose EEG manifested hypsarrhy thmia. Results Of the 181 patients, there were 109 cases of the West syndrome (60%), 60 cases of non West syndrome epilepsy (33%), and 11 cases with no convulsive history (6%). Among the 60 cases with non West syndrome epilepsy, 37 cases were complicated by cerebral organic insults and 21 by psychomotor retardation. The most common hypsarrhythmic variant was burst suppression (n=100, 55%), wherease typical hypsarrhythmia existed in only 74 cases (41%). Other common variants were periodic hypsarrhythmia, interhemispheric asymmetry, and increased interhemispheric synchrony. As sleep advanced, 43 cases with typical hypsarrhythmia changed into a burst suppression pattern. Conclusions Understanding hypsarrhythmia and its variants is important in the diagnostic evaluation of EEGs.
