Morphometrics of the preserved post-surgical hemisphere in pediatric drug-resistant epilepsy and implications for post-operative cognition.

Characterization of the structural integrity of cortex in adults who have undergone resection for epilepsy treatment has revealed persistent or even accelerated cortical atrophy in some cases, but, in other cases, the converse is evident, and atrophy can decelerate or even be reversed. Whether this variability applies to a pediatric population, for whom postoperative plasticity may be greater than in adulthood, remains to be determined. Furthermore, understanding the morphometrics of this patient population is important, as cognitive gains have been associated with the anatomical status of the preserved cortex post-resection. Here, we used high-resolution structural T1 magnetic resonance imaging data to compare the (1) gross anatomy, (2) cortical thickness, volume, and surface area for 34 cortical regions, and (3) volume for nine subcortical regions of 32 pediatric post-surgical cases and 51 healthy controls. We only analyze the metrics from the preserved hemisphere. Relative to controls, patients with either a preserved right hemisphere (RH) or left hemisphere (LH) had significantly lower total white matter volume and larger lateral ventricle size, as well as a reduction of the volume of select subcortical structures. However, relative to controls, only patients with a preserved RH had significantly lower total gray matter volume and lower thickness, volume, and surface area in multiple cortical regions, primarily in the frontal and temporal cortex. The differences in the preserved RH cortex of LH resection patients may relate to transfer of language function from the affected LH. Our findings lay the foundation for future studies probing associations of the morphometric differences in pediatric epilepsy surgery patients with neuropsychological outcomes.