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

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.