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INTRODUCTION/BACKGROUND: Recent studies have found that a reduced growth of the cerebellum is associated with poorer scores on both general intelligence tests and motor balance tests (Matthews et al., 2018) in children born preterm (PT), and that lower test scores may be persistent in adolescents born very PT (Allin et al., 2001). Notably, even low-risk children born PT at 9-years of age have been reported displaying regional brain volume reduction in the cerebellum (Arhan et al., 2017). So far, however, few studies have been conducted on cerebellar volumes and the role of its myelinated content, and if/how cerebellar myelination is associated with cognitive and kinematic outcome performance in children born PT.

To this end, the present study aim was to investigate whether cerebellar volumes were associated with gestational age (GA) and/or birth weight (BW) in a sample of children born PT (without known focal lesions) compared to controls (term born). We also wished to explore whether the cerebellum volumetric analyses, targeting the amount of myelinated content, would be linked to the children’s cognitive and motor performance. 

PATIENTS AND METHODS: The sample consisted of 59 children investigated at early school-age (M = 8.17 years), 27 born PT (divided into moderately PT, MPT, and very PT, VPT) and 32 born full-term (FT). Brain scans were conducted by a 3.0-Tesla MRI scanner and Synthetic MRI (SyMRI) was used to investigate brain and cerebellar volumes and additionally, the amount of myelin content. Cognitive performance was assessed by the Wechsler Intelligence Scale for Children, 4th Edition (WISC-IV), and goal-directed upper-limb movement kinematics were recorded by a 6-camera, optoelectronic 3D registrations system (240Hz). 

RESULTS: The results displayed reduced volumes of the cerebellum for children born VPT (see Table 1), and  smaller volumes were significantly associated with lower GA and BW. Children born VPT showed significantly lower full scale intelligence quotient (FSIQ) scores than children born MPT and FT. Overall, reduced myelinated content in the cerebellum was also significantly associated with lower FSIQ scores (see Fig.1). The children born VPT further displayed significantly poorer upper-limb kinematics than the other groups. However, no evident overall (independent of GA at birth) correlation was found between reduced volumes of the cerebellum and the kinematic performance. 

CONCLUSIONS: A very preterm birth (< 32 weeks’ of gestation) increases the risk for long-term effects on cerebellar volumes, including less myelin content, and poorer cognitive and motor performance. The findings emphasize the importance of myelinated content in cerebellum and its role for cognitive function and upper-limb movement performance in children born very preterm. These findings merit for further longitudinal studies including bigger samples of both preterm and term born infants and children.

Keywords: preterm, children, cerebellum, brain volumes, myelin, cognitive functioning, motor functioning

References:

Matthews et al., Longitudinal preterm cerebellar volume: perinatal and neurodevelopmental outcome associations. The Cerebellum, 2018, 17(5), 610-627.

Allin et al., Cognitive and motor function and the size of the cerebellum in adolescents born very pre-term. Brain, 2001, 124(1), 60-66.

Arhan et al., Regional brain volume reduction and cognitive outcomes in preterm children at low risk at 9 years of age. Child's Nervous System, 2017, 33, 8, 1317–1326.