Cerebellar pathway changes following cerebral hemispherectomy.

Following unilateral cerebral injury, several patterns of cerebellar metabolism have been noted on positron emission tomography (PET); these changes have been attributed both to the distant diaschisis as well as to reorganizational changes within the cerebellum. We used diffusion tensor magnetic resonance imaging (MRI) to study 14 children who had undergone cerebral hemispherectomy because of intractable epilepsy and compared them with those from 17 controls. In 10 children who had preoperative and postoperative scans, a paired comparison was performed. Our findings showed significantly higher fractional anisotropy values in corticopontocerebellar pathways postoperatively compared to preoperatively. When compared to controls, we found a higher rate of age-related fractional anisotropy changes of corticopontocerebellar pathways in the postoperative scans. Our results indicate reorganizational changes in the contralateral (intact) corticopontocerebellar pathway and the cerebellar white matter. These changes likely contribute to the far better motor outcomes seen in children compared to adults sustaining such cortical injuries.