Early extra-uterine exposure alters regional cerebellar growth in infants born preterm

Abstract

Objectives: To compare third trimester global and regional cerebellar volumetric growth at two time-points between very preterm (PT) infants and healthy gestational age-matched fetuses in the PT period and at term equivalent age (TEA).

Study design: Using a prospective study design, high resolution anatomic magnetic resonance images (MRI) were acquired in PT infants (gestational age at birth < 32 weeks; birthweight < 1500 g) without cerebellar injury and healthy full-term controls. PT infants completed two MRIs, one as soon as medically stable and the other around TEA. Controls also completed two MRIs, one in utero (i.e. fetal MRI) and a postnatal MRI shortly after birth. The cerebellum of each participant was parcellated into 5 regions: left and right hemispheres, the anterior, neo and posterior vermis. Evidence of differences in regional volumes between term and pre-term infants matched for gestational age (GA) at the time of the first MRI were assessed using multiple linear regression.

Results: WE STUDIED 76 SUBJECTS: 38 PT infants were matched to 38 healthy fetuses. At MRI-1, PT infants demonstrated decreased cerebellar hemispheric volumes and increased anterior, neo- and posterior vermian regional volumes when compared to healthy fetuses. At TEA, PT infants demonstrated a persistent increase in anterior, neo- and posterior vermian regional volumes but no longer showed reductions in cerebellar hemispheric volume. Only the neovermis volume demonstrated a significant negative association with birthweight, male gender and supratentorial injury.

Conclusions: In the absence of demonstrable cerebellar parenchymal injury evident on conventional MRI, PT birth is associated with cerebellar growth alterations that are regionally- and temporally-specific.

Keywords: Cerebellum; Fetus; Growth; Prematurity; Volume.

Fig. 1

Parcellation of the cerebellum on coronal (top) and sagittal (bottom) T2 images in a healthy fetus at 25 2/7 weeks GA (left) and neonate 40 5/7 weeks GA (right). Color legend: Blue = left hemisphere, green = anterior vermis, cyan = neovermis, yellow = posterior vermis, red = right hemisphere.