Longitudinal growth of the basal ganglia and thalamus in very preterm children.

The impact of very preterm (VP) birth on the development of individual basal ganglia nuclei and the thalamus during childhood remains unclear. We first aimed to compare (1a) the volumes of individual basal ganglia nuclei (nucleus accumbens, caudate nucleus, pallidum, putamen) and the thalamus at age 7 years, and (1b) their volumetric change from infancy to 7 years, in VP children with term-born children. Secondly, we aimed to (2a) determine whether basal ganglia and thalamic volumes at 7 years, or (2b) basal ganglia and thalamic growth rates from infancy to 7 years were associated with neurodevelopmental outcomes at 7 years, and whether these associations differed between the VP and term-born children. One hundred and fifty-four VP (<30 weeks' gestational age or birth weight < 1250 g) and 35 term-born children had useable magnetic resonance imaging (MRI) scans that could be analyzed at 7 years. Of these, 149 VP and 30 term-born infants also had useable MRI scans at term-equivalent age. Volumes of the individual basal ganglia nuclei and the thalamus were automatically generated from the MRI scans. Compared with the term-born group, the VP group had smaller basal ganglia and thalamic volumes at 7 years and slower growth rates from birth to 7 years. After controlling for overall brain size, VP children still had smaller thalamic volumes but the deep grey matter volume growth rates from birth to 7 years were similar between groups. Reduced basal ganglia and thalamic volumes and slower growth rates in the VP group were associated with poorer cognition, academic achievement and motor function at 7 years. After controlling for overall brain size, the nucleus accumbens and pallidum were the deep grey matter structures most strongly associated with 7-year neurodevelopmental outcomes. In conclusion, basal ganglia and thalamic growth is delayed during early childhood in VP children, with delayed development contributing to poorer functional outcomes.