Background electroencephalographic (EEG) activities of very preterm infants born at less than 27 weeks gestation: a study on the degree of continuity

Aims-To clarify the features of the background electroencephalographic (EEG ) activities in clinically well preterm infants born at less than 27 weeks gestation and to outline their chronological changes with increasing postco nceptional age (PCA). Methods-EEGs of clinically well premature infants born at less than 27 week s gestation were recorded during the early postnatal period. The infants we re separated into three groups according to their PCA at the time of EEG re cording (21-22 weeks PCA, 23-24 weeks PCA, and 25-26 weeks PCA). The mean a nd maximum duration of interburst intervals (IBIs), the mean duration of bu rsts, and the percent:Ige of continuous and discontinuous patterns in each PCA group were evaluated. Results-There were three infants at 21-22 weeks PCA, seven at 23-24 weeks P CA, and five at 25-26 weeks PCA. Eighteen EEG recordings were obtained. The mean :md maximum IBI duration decreased with increasing PCA. The percentag e of continuous patterns increased with increasing PCA. Conversely, the per centage of discontinuous patterns decreased with increasing PCA. Conclusions-In premature infants born at less than 27 weeks gestation, the characteristics of the background EEG activities were similar to those of o lder premature infants. These changes reflect the development of the centra l nervous system in this period.