Long-term alterations of cerebellar structure after premature birth

• Adults born prematurely show cerebellar volume changes • Consistent reductions of cerebellar white matter volume • Focal and less consistent alterations for cerebellar cortex subregions • Methodological factors like intracranial volume correction warrant attention Alterations of cerebellar volume were reported in prematurely-born children, adolescents and adults, suggesting long-lasting effects on cerebellar growth. However, studies mostly examined global cerebellar volumes, which could disguise focal, subregional differences. Based on T1-/T2-weighted MRI, this voxel-based morphometry study used the SUIT toolbox for optimized analysis of cerebellar and brainstem gray matter (GM) and white matter (WM) volumes in young adults born very preterm (<32 gestational weeks) and/or with very low birth weight (<1500g; N=101, M=26.7 years) and full-term controls (N=109, M=26.8 years) from the Bavarian Longitudinal study. Voxel-wise group differences for GM and WM tissue maps, and correlation with prematurity-related variables were analyzed. For comparison, an automated, deep learning-based segmentation of cerebellar regions of interest (ROI) was performed using CerebNet. Preterms showed lower cerebellar (and brainstem) WM volume, which correlated with prematurity-related variables. While voxel-based analyses observed higher preterm GM volume in anterior vermal and superior-posterior foci, these were sensitive to modeling strategies for intracranial volume confounds. Among preterms, GM volume showed positive associations with GA only, in distinct inferior-posterior regions. ROI-based analyses observed no significant GM differences except for lower preterm GM volume in right lobule X, but broader associations between subregional GM volumes and prematurity-related variables. Present data suggest that premature birth has a long-lasting influence on cerebellar morphology, preferentially its white matter aspects. The impact on cerebellar cortex volume may be more diffuse due to differential sensitivity of the growth trajectories of cerebellar subregions to perinatal and postnatal adversities.