Relationship between functional and microstructural brain maturation in preterm infants with brain injury

Preterm infants are at high risk for brain injury, which contributes to poor long-term neurodevelopmental outcome. Amplitude-integrated electroencephalography (aEEG) is a reliable tool to assess electrocortical activity and provides continuous evaluation of neonatal brain function at the bedside. Magnetic resonance imaging (MRI) gives detailed information about brain abnormalities, which are related to long-term neurodevelopmental outcome in preterm infants. Diffusion tensor imaging (DTI) is a powerful MRI-technique, which, by measuring brain-water diffusion and maturation of the myelin sheath of white matter fiber bundles, provides valuable information about microstructural brain development.

This study aims to investigate a possible correlation between functional and microstructural brain maturation of preterm infants with brain injury using early aEEG and DTI-MRI at term equivalent age (TEA).

The study was conducted as a retrospective single centre study of prospectively collected data. 124 infants born between 2011 and 2018 at Innsbruck Medical University Hospital were included in the study. Inclusion criteria were defined as being born before 32 gestational weeks, diagnosed with brain injury (intraventricular/cerebellar hemorrhage and/or white matter injury) by MRI and having both, early aEEG monitoring in the first 72 hours of life and DTI-MRI at TEA. Two-channel obtained aEEG recordings were interpreted at three defined time points (day 1, 2 and 3 of life, each a defined 6-hour aEEG interval) according to Burdjalov et al. for the total maturation score (TMS). In MRI, fractional anisotropy (FA) and apparent diffusion coefficient (ADC) were measured in 14 defined brain regions; increased FA and decreased ADC correspond to an advanced maturation. Statistical correlation between TMS and FA/ADC values was performed by virtue of Spearman Rho.

TMS at day 1 correlated positively with FA of left posterior limb of the internal capsule (PLIC), right and left pons, left occipital white matter (OcWM), genu and splenium of the corpus callosum (CC), and negatively with ADC of genu of the CC. TMS at day 2 correlated positively with FA of right centrum semiovale, right and left PLIC, right and left pons, left OcWM, genu and splenium of the CC; correlation was negatively with ADC of right PLIC, genu and splenium of the CC. TMS at day 3 correlated positively with FA of left pons, left OcWM, genu and splenium of the CC, and negatively with ADC of genu and splenium of the CC.

Results of the study indicate that early monitoring of functional maturation may anticipate later assessment of microstructural brain development in preterm infants with brain injury. Thus, aEEG could be used to early identify neonates who might benefit from occupational and physical therapies. A potential positive effect of pre-TEA applied therapies on microstructural brain maturation and its possible correlation with the neurodevelopmental outcome have to be evaluated further in detail.

Publication History

Article published online:
06 June 2023