Corticospinal tract integrity and motor function following neonatal stroke: a case study

New MRI techniques enable visualisation of corticospinal tracts and cortical motor activity. The objective of this case study was to describe the magnetic resonance evidence of corticospinal pathway reorganisation following neonatal stroke.

An 11 year old boy with a neonatal right middle cerebral artery territory ischaemic stroke was studied. Functional MRI was undertaken with a whole hand squeezing task, comparing areas of cortical activation between hands. White matter tracts, seeded from the area of peak activation in the cortex, were visualised using a diffusion weighted imaging probabilistic tractography method. Standardised evaluations of unilateral and bilateral motor function were undertaken. Clinically, the child presented with a left hemiparesis. Functional MRI demonstrated that movement of the hemiparetic hand resulted in activation in the ipsi-lesional (right) hemisphere only. Diffusion tractography revealed pathways in the right (lesioned) hemisphere tracked perilesionally to the cortical area identified by functional MRI.

Our case demonstrates that neonatal stroke is associated with maintenance of organization of corticospinal pathways sufficient to maintain some degree of hand function in the affected hemisphere. Functional MRI and diffusion weighted imaging tractography may inform our understanding of recovery, organisation and reorganisation and have the potential to monitor responses to intervention following neonatal stroke.