QUANTIFICATION OF CHANGES NORMAL NEONATAL EEGs WITH GESTATION FROM CONTINUOUS FIVE‐DAY RECORDINGS

Abstract

It is now possible to make a good-quality, continuous electroencephalogram (EEG) record of sick newborn babies receiving intensive care, from which seizure activity can be identified readily (Eyre et al. 1983a, b). The background EEG can be difficult to interpret, however, because it changes with increasing gestational age. In addition, there are cyclical changes in the EEG during sleep that are dependent not only on the baby's sleep state but also on the length of the preceding sleep epoch (Roffwarg et al. 1966, Eyre 1984. Therefore the normal pattern of the EEG cannot be described fully from intermittent, short records. The aim of this study was to describe the range of normal EEG activity at different gestational ages during the first five days after birth by analysing continuous recordings. Subjects and methodThis study of normal babies was approved by the Central Oxford Hospitals' Ethical Committee and informed consent was obtained from the parents. 25 babies were studied, 12 girls and 13 boys. They were all healthy, with no medical problems during the first five days. Their gestational ages ranged from 26 to 42 weeks and their birthweights from 990 to 4120g. All had a normal neurological examination and cerebral ultrasonogram at the beginning and end of the recording. All were examined at a postconceptional age of 18 months by an independent investigator and were found to be within the normal range for development, with no abnormal neurological signs.A small battery-powered four-channel tape-recorder was used to record two channels of EEG, one of electrocardiogram (ECG) and one of transthoracic impedence. The EEG record was bi-polar, F3-P3, and F4-P4, with an indifferent electrode placed on the scalp. The filter band-width was 0.5 to 1oc)Hz. A more detailed description of the recording technique has been published (Eyre et al. 1983a). The record was started within the first 24 hours after birth and continued, where possible, for five days. The EEG was analysed using two methods: ( 1 ) replay on an automatic visual-display unit with an amplification of 50pv/cm at 15cm/sec; and (2) the data were transcribed onto paper, using an inkjet recorder at a speed of lmm/sec and an amplification of 10pv/mm. EEG records associated with movement on the ECG or transthoracic impedance record were excluded from further analysis. The remaining EEG was subdivided into two distinct patterns, trace-alternant activity and continuous activity. Trace-alternant m 03 z 599

Electroencephalography of the Newborn: Normal Features

“…9,19,20 Anderson and associates 16 found that 60% of EEG recordings consisted of discontinuity. [21][22][23][24][25] This is sharp contrast to earlier descriptions of interburst intervals as long as 2 minutes in duration. Similar ranges for the duration of interburst intervals have been found by other authors, as listed in Table 2-1.…”

Ontogeny of EEG sleep from neonatal through infancy periods

“…Previous neonatal sleep studies initially applied automated techniques to assess functional brain maturation, using analyses that were based on assumptions of linearity, without consideration of time-dependent changes (Havlicek et al, 1975;Giaquinto et al, 1977;Sterman et al, 1977;Lombroso, 1979;Willekens et al, 1984;Connell et al, 1987;Bes et al, 1988;Eyre et al, 1988; Kuks et al, 1988). The preferred methodological approach has been fast Fourier transform analyses, studied initially with full-term neonates (Ktonas et al, 1995;Witte et al, 1997;Lehtonen et al, 1998;Eiselt et al, 2001;Field et al, 2002), followed by more recent reports in preterm infants (Sawaguchi et al, 1996;Eiselt et al, 1997;Myers et al, 1997;Holthausen et al, 2000;Schramm et al, 2000;Kuhle et al, 2001;Vanhatalo et al, 2002).…”

Quantitative Analysis of Amplitude-Integrated Electroencephalogram Patterns in Stable Preterm Infants, with Normal Neurological Development at One Year

“…These investigators found a decrease in discontinuous activity from 27% at 28 weeks GA to 10% at 38 weeks. Eyre et al [22] also investigated first week EEG recordings and found a decrease in discontinuity from 35% at 28 weeks GA to 10% at 36 weeks. However, both authors used different definitions of discontinuous EEG activity and definitions were not quantitative, making this technique difficult to reproduce.…”