Groeschel S, et al. – The involvement of the motor fibres of the corpus callosum after unilateral neonatal arterial ischemic stroke (NAIS) of the middle cerebral artery territory and the relationship to both ipsilesional and contralesional hand function were examined in this study. Children after NAIS demonstrated a smaller motor part of their corpus callosum associated with reduced contralesional but also ipsilesional manual dexterity than typically developing children. These outcomes showed that the affection of transcallosal motor fibres in unilateral NAIS could be of functional relevance and an important part of the involved structural network that needed to be clarified in additional studies.

• The clinicians compared the midsagittal area of the motor part of the corpus callosum (defined by the fibres connecting the precentral gyri) between 33 7-year-old children after unilateral NAIS and 31 typically developing 7-year-old children using high-resolution structural magnetic resonance imaging (MRI), functional MRI, and magnetic resonance diffusion-tractography.
• They evaluated hand motor performance by the box and blocks test.

• Compared to typically developing children, children after NAIS demonstrated on average significantly smaller motor corpus callosum area (p<0.001, without differences of the non-motor corpus callosum area).
• Moreover, after controlling for lesion volume and sex, there was a significant positive correlation between the motor part of the corpus callosum and both contralesional (Pr(>|t|)=0.034) and ipsilesional hand motor performance (Pr(>|t|)=0.006).
• The clinicians evaluated the additional contribution of corticospinal tract damage in a post-hoc analysis.