Functional brain connectome and sensorimotor networks in rolandic epilepsy

Rolandic epilepsy (RE) is a form of well-characterized childhood epilepsy whose focal electroencephalographic abnormalities affect the same well-delineated local brain regions. Little is known about how the focal electroencephalographic discharges interfere with the topological organization of whole-brain networks in RE patients.

Seventy-three patients RE patients and 73 healthy children underwent rsfMRI. The whole-brain functional networks were constructed by thresholding the partial correlation matrices of 90 brain regions, and their topological properties were analyzed using graph theory-based approaches. We used network-based statistics to evaluate functional connectivity. The correlations between the network properties and the clinical and cognitive characteristics were calculated.

The global topologic organization of the functional brain network was disrupted in RE patients, as manifested by reduced clustering coefficient and local and global efficiency and increased characteristic path length. The RE patients exhibited less connectivity among the sensorimotor areas; this reduction in the mean functional connectivity in this network correlated to altered global small-world properties. The RE patients exhibited decreased nodal centralities, predominantly in the bilateral postcentral gyrus, in the frontal, parietal and temporal lobes around the rolandic fissure and in areas related to linguistics and attention control (p<0.05, FDR-corrected). The altered nodal centralities in the bilateral postcentral gyrus and the left posterior cingulate cortex were correlated with subscales in Child Behavior Checklist.

These results support the hypothesis that RE is associated with systemic brain disorganization and that the functional defect in rolandic areas contribute to symptomatology and electrophysiology in RE. Nodal abnormalities appear to imply the disturbances in linguistics and attention observed in RE patients.