Microstructural alterations of the corticospinal tract are associated with poor motor function in patients with severe congenital heart disease

Congenital heart disease (CHD) patients are at risk for neurodevelopmental impairments, including altered motor function. However, little is known about the neuroanatomical correlates of persistent motor deficits in CHD. Thus, we examined the link between corticospinal tract (CST) microstructure and motor function in adolescent and adult CHD patients compared to healthy controls. This study investigated 89 CHD patients (N((adolescents)) = 47, N((adults)) = 42, mean age = 19.9 years) and 97 age-matched healthy controls (N((adolescents)) = 44, N((adults)) = 53, mean age = 20.6 years). Diffusion tensor imaging was conducted and fractional anisotropy (FA) of the left and right CST was extracted for each participant. Fine (pegboard) and pure motor (repeated finger, hand and foot movements) performance was evaluated with a standardized test battery. FA and motor performance were correlated and the effect of CHD complexity was tested using multivariate linear regression. Clinically relevant motor impairments (>2SD below normative mean) were evident in 24% of patients and 9% of controls. On average, motor performance was lower in CHD patients compared to controls, particularly in those with more complex CHD (fine motor: p = 0.023; pure motor: p < 0.001). FA CST was lower in patients compared to controls, particularly in those with more complex CHD (left: p < 0.001, right: p = 0.003). There was a significant interaction between CHD complexity and FA CST (left: p = 0.025, right: p = 0.025), indicating that FA correlates significantly with pure motor in patients with severe CHD, while there is only a weak association in moderate CHD and no association in patients with simple CHD and controls. Microstructure of the CST is altered in CHD patients, and is associated with pure motor impairments in patients with severe CHD. This indicates that persistent motor impairments may arise from atypical development of the primary motor pathway in the presence of a complex CHD. Early interventions promoting brain maturation in infancy may prevent persisting impairments across the lifetime.