Disrupted Global and Regional Structural Networks and Subnetworks in Children with Localization-Related Epilepsy.
OBJECTIVE
Structural connectivity has been thought to be a less sensitive measure of network changes relative to functional connectivity in children with localization-related epilepsy. The aims of this study were to investigate the structural networks in children with localization-related epilepsy and to assess the relation among structural connectivity, intelligence quotient, and clinical parameters.


METHODS
Forty-five children with nonlesional localization-related epilepsy and 28 healthy controls underwent DTI. Global network (network strength, clustering coefficient, characteristic path length, global efficiency, and small-world parameters), regional network (nodal efficiency), and the network-based statistic were compared between patients and controls and correlated with intelligence quotient and clinical parameters.


RESULTS
Patients showed disrupted global network connectivity relative to controls, including reduced network strength, increased characteristic path length and reduced global efficiency, and reduced nodal efficiency in the frontal, temporal, and occipital lobes. Connectivity in multiple subnetworks was reduced in patients, including the frontal-temporal, insula-temporal, temporal-temporal, frontal-occipital, and temporal-occipital lobes. The frontal lobe epilepsy subgroup demonstrated more areas with reduced nodal efficiency and more impaired subnetworks than the temporal lobe epilepsy subgroup. Network parameters were not significantly associated with intelligence quotient, age at seizure onset, or duration of epilepsy.


CONCLUSIONS
We found disruption in global and regional networks and subnetworks in children with localization-related epilepsy. Regional efficiency and subnetworks were more impaired in frontal lobe epilepsy than in temporal lobe epilepsy. Future studies are needed to evaluate the implications of disrupted networks for surgical resection and outcomes for specific epileptogenic zones and the relation of disrupted networks to more complex cognitive function.
From the Department of Diagnostic Imaging (E.W., M.Z., C.R., S.M.D.) Division of Neurology (E.W., O.C.S.) Elysa.Widjaja@sickkids.ca.
E
E
Widjaja
From the Department of Diagnostic Imaging (E.W., M.Z., C.R., S.M.D.).
M
M
Zamyadi
From the Department of Diagnostic Imaging (E.W., M.Z., C.R., S.M.D.).
C
C
Raybaud
Division of Neurology (E.W., O.C.S.).
O C
OC
Snead
From the Department of Diagnostic Imaging (E.W., M.Z., C.R., S.M.D.) Neuroscience and Mental Health at Research Institute (S.M.D.), Hospital for Sick Children, Toronto, Ontario, Canada.
S M
SM
Doesburg
Department of Psychology (M.L.S.), University of Toronto, Toronto, Ontario, Canada.
M L
ML
Smith
D000293:Adolescent; D001921:Brain / Q000503:physiopathology*; D002648:Child; D002675:Child, Preschool; D017034:Epilepsy, Frontal Lobe / Q000503:physiopathology*; D004833:Epilepsy, Temporal Lobe / Q000503:physiopathology*; D005260:Female; D006801:Humans; D008297:Male; D009415:Nerve Net / Q000503:physiopathology*