Association of corpus callosum and corticospinal tract microstructure with bimanual coordination in children with unilateral cerebral palsy.

Bimanual actions involve the coordinated use of both hands and are supported in part by the corticospinal tract (CST) for motor execution and the corpus callosum (CC) for bimanual coordination. In children with unilateral cerebral palsy (CP), disruptions in the microstructural properties of the CST and CC have been associated with reduced bimanual motor functions. However, their specific contributions to bimanual motor control remain to be fully understood. Seventeen children with unilateral CP (mean age 10.7 ± 2.1 years, 7 females) with mild to moderate motor impairments were recruited. Several types of diffusion magnetic resonance imaging metrics were collected in the CC and in the CST. Two behavioral tasks (cooperative and asymmetric independent goals) using the Kinarm exoskeleton were used, and spatiotemporal and bimanual coupling parameters were extracted. Nonparametric correlations were used to quantify the associations between neuroimaging metrics and behavioral parameters. The CC metrics showed multiple correlations with spatiotemporal parameter in both tasks with corrected p-values. In contrast, most of the CST metrics were only correlated with spatiotemporal parameters during the asymmetric independent goals task. No correlation was found between diffusion metrics and bimanual coupling parameter in either task. These findings highlight the significant role of the CST and CC microstructure in spatiotemporal characterization of bimanual movement. Although not definitive, the findings suggest that corpus callosum microstructure broadly supports bimanual motor function in children with unilateral CP and highlight the need to examine its interaction with the corticospinal tract.