Brain structural and microstructural alterations associated with cerebral palsy and motor impairments in adolescents born extremely preterm and/or extremely low birthweight

Aim To elucidate neurobiological changes underlying motor impairments in adolescents born extremely preterm (gestation <28wks) and/or with extremely low birthweight ( ELBW , <1000g), our aims were the following: (1) to compare corticospinal tract ( CST ) microstructure and primary motor cortex (M1) volume, area, and thickness between extremely preterm/ ELBW adolescents and a comparison group with normal birthweight (>2499g); (2) to compare CST microstructure and M1 volume, area, and thickness between extremely preterm/ ELBW adolescents with cerebral palsy ( CP ), motor impairment without CP , and no motor impairment; and (3) to investigate associations between CST microstructure and M1 measures. Method This study used diffusion and structural magnetic resonance imaging to examine the CST and M1 in a geographical cohort of 191 extremely preterm/ ELBW adolescents (mean age 18y 2.4mo [ SD 9.6mo]; 87 males, 104 females) and 141 adolescents in the comparison group (mean age 18y 1.2mo [ SD 9.6mo]; 59 males, 82 females). Results Extremely preterm/ ELBW adolescents had higher CST axial, radial, and mean diffusivities and lower M1 thickness than the comparison group. Extremely preterm/ ELBW adolescents with CP had higher CST diffusivities than non‐motor‐impaired extremely preterm/ ELBW adolescents. CST diffusivities correlated with M1 volume and area. Interpretation Extremely preterm/ ELBW adolescents have altered CST microstructure, which is associated with CP . Furthermore, the results elucidate how CST and M1 alterations interrelate to potentially influence motor function in extremely preterm/ ELBW adolescents.