Sleep-wake cycles in preterm infants below 30 weeks of gestational age. Preliminary results of a prospective amplitude-integrated EEG study

In the newborn, presence of sleep-wake cycles indicates integrity and matur ity of the central nervous system. By spectral EEG analysis and polygraphic recordings subtle variations of EEG background activity and behavioural pa tterns corresponding to early sleep-wake cycles have been found in preterm infants as young as 27 weeks of gestation. The emergence of sleep-wake cycl es at early gestational ages may have a positive predictive value for long- term neurological outcome. Sleep-wake cycles and their significance for lat er outcome have not been studied in very preterm infants so far. Accordingl y, we prospectively investigated maturational changes of EEG activity and s leep-wake cycles in preterm infants below 30 weeks of gestational age using the Cerebral Function Monitor, an amplitude-integrated EEG. We present pre liminary data on the emergence of sleep-wake cycles in preterm infants from this ongoing study. Of 100 infants enrolled during a 1-year period, 38 inf ants without neurological complications were included in the reference grou p. In this group (mean gestational age 27 weeks), we observed cyclical vari ations of EEG background activity resembling early sleep-wake cycles at a m ean gestational age of 28 weeks and a median postnatal age of 6 days. It is hypothesised that these cyclical variations of EEG background activity may represent switches between thalamo-cortical and neo-cortical pattern gener ators and indicate integrity of central nervous system function. Amplitude- integrated EEG may thus serve as a useful noninvasive test for brain functi on in preterm infants.