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Normal EEG of premature infants born between 24 and 30 weeks gestational age: terminology, definitions and maturation
M-F Vecchierini1, M André, A M d'Allest
1Laboratoire d'explorations fonctionnelles, hôpital Bichat-Claude-Bernard, AP-HP, université Paris-VII, 46, rue Henri-Huchard, 75722 Paris cedex 18, France. marie-francoise.vecchierini@bch.aphp.fr
Insights
This study details normal electroencephalogram (EEG) patterns in premature infants (24-30 weeks gestation). Understanding these EEG characteristics is vital for predicting neurological outcomes in early development.
Area of Science:
- Neonatal neurology
- Neurophysiology
Background:
- Electroencephalogram (EEG) is crucial for neurological prognosis in premature infants.
- Normal EEG patterns in very premature infants (24-30 weeks gestational age) are not widely documented but are essential for outcome prediction.
Purpose of the Study:
- To describe the normal electroencephalogram (EEG) characteristics and maturational patterns in premature infants between 24 and 30 weeks of gestational age.
- To establish a baseline for neurological assessment and prognosis in this vulnerable population.
Main Methods:
- Observational study analyzing EEG recordings from premature infants.
- Correlation of EEG patterns with gestational age and sleep states (active sleep, slow-wave sleep).
- Identification and tracking of specific EEG features like delta waves and theta bursts over time.
Main Results:
- Background EEG activity transitions from discontinuous to continuous between 24 and 30 weeks, with decreasing interburst intervals.
- Sleep state differentiation (based on EEG and eye movements) emerges by 25 weeks and is complete by 30 weeks.
- Specific EEG features like temporal and frontal delta waves and diffuse theta bursts show distinct maturational trajectories, disappearing or localizing with increasing gestational age.
Conclusions:
- Normal EEG patterns exhibit significant maturational changes between 24 and 30 weeks gestational age.
- These maturational EEG characteristics provide a basis for neurological assessment and prognosis in very premature infants.
- The study establishes normative EEG data crucial for identifying deviations from normal development.
Abstract:
This article presents normal EEG characteristics and their maturational pattern in premature infants of 24-30 weeks gestational age. Although the very premature infants with a normal outcome are not that numerous, their normal EEG pattern should be known, as EEG constitutes a basis for neurological prognosis. Background activity is first discontinuous but the discontinuity gradually decreases and the activity is completely continuous at 30 weeks of age, during active sleep. At the same time, interburst intervals become shorter so that the proportion of time without EEG activity decreases. Based on EEG activity and eyes movements, a rough sleep state differentiation appears as early as 25 weeks of gestational age and is complete at 30 weeks. The main EEG figures are high-voltage delta waves, whose frequency is slower and amplitude higher in younger infants. Temporal delta waves occur in sequences and are characteristic of the very premature infant; they progressively become smaller and less numerous and disappear around 27-28 weeks. In contrast, occipital delta waves remain numerous; they are of high voltage and usually bilaterally superimposed with fast rhythms. Both types of frontal delta waves that are seen in 24-27 weeks premature babies disappear with maturation. Bursts of synchronized delta waves, which are less numerous than localized delta waves, also disappear before 28 weeks of gestational age. Finally, diffuse theta bursts which are mainly recorded at 26-27 weeks, progressively focus on temporal areas with maturation. At 30 weeks, they are observed on temporal areas, mainly during slow-wave sleep.
