Early Electroencephalography Suppression and Postnatal Morbidities Correlate with Cerebral Volume at Term-Equivalent Age in Very Preterm Infants.

BACKGROUND: Early brain activity is associated with long-term outcome. Establishing a relation also with postnatal brain growth may increase our understanding of early life influences on preterm brain development.

OBJECTIVES: The aim of this study was to investigate whether early electroencephalography (EEG) activity in infants born very preterm is associated with brain volumes at term, and whether postnatal morbidity affects this association.

METHODS: Very preterm infants (n = 38) with a median gestational age (GA) of 25.6 weeks had early recordings of single-channel EEG. The percentage of suppressed EEG, i.e., interburst intervals (IBI%) between 24 and 72 h of age, was analyzed in relation to brain volumes on magnetic resonance imaging performed at term-equivalent age, taking into account neonatal morbidities.

RESULTS: Early electrocortical depression and a higher IBI% were associated with increased cerebrospinal fluid volume (CSFV) and lower total brain volume relative to intracranial volume, also after adjustment for GA, postnatal morbidities, morphine administration, and postnatal head growth. Overall, an increase in IBI% to 1 SD from the mean corresponded with an increase in CSFV to +0.7 SD and a decrease in brain volume to -0.7 SD. The presence of 2 or more postnatal morbidities were associated with around 10% lower brain volumes.

CONCLUSIONS: More suppressed early EEG activity of very preterm infants is associated with lower brain volume and increased CSFV at term age, also when adjusting for postnatal morbidities. The findings indicate the importance of pre- and early postpartal determinants of postnatal brain growth, possibly also including activity-dependent mechanisms for brain growth.