COMPARISONS OF EEG SLEEP STATE-SPECIFIC SPECTRAL VALUES BETWEEN HEALTHY FULL-TERM AND PRETERM INFANTS AT COMPARABLE POSTCONCEPTIONAL AGES

Differences in state-specific electroencephalographic (EEG) spectral v alues are described between groups of preterm and full-term neonates a t comparable postconceptional term ages. Eighteen healthy preterm neon ates of less-than-or-equal-to 32 weeks gestation were selected from an inborn population of a neonatal intensive care unit. Twenty-four-chan nel recordings were obtained at a full-term age and compared with stud ies of 22 healthy full-term neonates. The initial three hours of each 12-hour study were recorded on paper from which EEG sleep state scores per minute were visually assessed. Six mean spectral values (i.e. tot al EEG, electromyogram, delta, theta, alpha and beta energies) were ca lculated from each corresponding minute of digitized data, which was a lso assigned one of six EEG sleep states. Each neonatal group displaye d statistically significant differences among sleep-state segments for all spectral values. The alpha- and beta-range spectral values of the preterm group, compared to the full-term control group, were lower du ring all sleep state segments. Spectral values for the theta band were lower during both quiet sleep segments only, whereas spectral values for delta were lower during all sleep stages, except trace-alternant q uiet sleep. Significant differences in EEG spectral values were noted among states of sleep for both preterm and full-term infants of simila r postconceptional term ages. These data also suggest differences in c entral nervous system maturation between neonatal populations. These f indings strengthen our previously stated contention that there is a fu nctional alteration in brain development of the preterm infant as refl ected in sleep organization that results from a prolonged extrauterine experience and/or prematurity.