A review of important electroencephalogram features for the assessment of brain maturation in premature infants

Abstract

This review describes the maturational features of the baseline electroencephalogram (EEG) in the neurologically healthy preterm infant. Features such as continuity, sleep state, synchrony and transient waveforms are described, even from extremely preterm infants and includes abundant illustrated examples. The physiological significance of these EEG features and their relationship to neurodevelopment are highlighted where known. This review also demonstrates the importance of multichannel conventional EEG monitoring for preterm infants as many of the features described are not apparent if limited channel EEG monitors are used. Conclusion: This review aims to provide healthcare professionals in the neonatal intensive care unit with guidance on the more common normal maturational features seen in the EEG of preterm infants. INTRODUCTIONDespite increased survival of premature infants and some improvements in major disabilities, disability rates remain high particularly in extremely low birthweight infants (1,2). It is simply very hard to mimic the intrauterine environment in the neonatal intensive care unit (NICU). For babies born too soon, too small and too sick and who need intensive care, information about the function of the brain is essential. The electroencephalogram (EEG), which measures cerebral electrical activity recorded from electrodes placed on the scalp in predefined regions, provides critical real-time information about cerebral function. The EEG can also provide real-time markers of cerebral dysfunction, even when it is secondary to systemic disease and macroscopic cerebral lesions are not evident (3).The neonatal EEG contains complex spatiotemporal information that can be difficult to interpret. It is certainly more complex than the interpretation of other vital sign signals such as heart rate or respiratory rate. As a result, in many NICUs around the world, a simpler EEG methodology, using a restricted number of channels (1-2 channels)

Comparison of conventional, amplitude-integrated and geodesic sensor net EEG used in premature neonates: a systematic review

“…In seizure-related studies, it was found that both aEEG and conventional EEG may help to detect seizures, as well as allowing monitoring of the effect of treatment with antiepileptic drugs, analysis of background activity of the EEG and the characterization of diagnoses and prognostics 38 . However, with the low number of channels, not all seizures are detectable by aEEG 34,37 . Other studies have suggested the use of video-EEG to allow the analysis and validation of abnormal movements, such as epileptic seizures, and the location of the origin of possible artifacts 24,38 .…”

“…Although it has problems related to its interpretation, when used by experienced clinicians, aEEG has been shown to be of great relevance in providing an overview of conventional EEG activity 37 .…”

“…The use of the aEEG for the detection of neonatal seizures is controversial because of the fact that many of them last less than 90 seconds and are spatially restricted, which makes it very difficult to interpret the results 10,18 . Thus, it was concluded that the limited ability of aEEG to identify seizures does not allow it to be considered a substitute equivalent to a conventional EEG in terms of the detection of seizures 10,37,38 , although it has been stated that the use of an aEEG is recommended if there is no other electrographic monitoring 10,38 . The aEEG may be used initially in high-risk prematurity for long-term monitoring, with a conventional EEG used sequentially to assess more subtle abnormalities that are not described in an aEEG.…”

Swedish consensus reached on recording, interpretation and reporting of neonatal continuous simplified electroencephalography that is supported by amplitude‐integrated trend analysis

“…The amplitude of the activity between bursts increases gradually and the proportion of bursts and the duration of activity periods also increase. These patterns are summarised as background EEG activity and provide important information related to maturation and prognosis after an insult (4,(19)(20)(21)(22)(23).…”

Highlights in this issue

“…This review by Pavlidis et al. describes the maturational features of the baseline electroencephalogram (EEG) in the neurologically healthy preterm infant . Features such as continuity, sleep state, synchrony and transient waveforms are described also in extremely preterm infants.…”