Cortical thickness asymmetries and surgical outcome in neocortical epilepsy

Abstract

Purpose We evaluated if cortical thickness measures were associated with surgical outcome in patients with non-lesional neocortical epilepsy. Methods Twenty-one young patients (age: 2.4–19.7 years) with epilepsy of neocortical origin and normal MRI underwent two-stage epilepsy surgery with subdural EEG monitoring. Cortical thickness was measured on presurgical volumetric MRI using the FreeSurfer software. The prognostic value of hemispheric and lobar/regional cortical thickness measures for 1-year and 2-year post-surgical seizure outcome has been analyzed. Results At one-year follow-up, 14 patients (67%) were seizure-free. Hemispheric and frontal lobe cortical thickness showed no/minimal asymmetry in seizure-free patients but thinner cortex ipsilateral to the seizure focus in those with recurrent seizures (p=0.02). More robust differences were found in patients ≥6 years of age (p=0.006 for frontal asymmetries), whose cortical thickness asymmetries remained prognostic for 2-year post-surgical outcome (p=0.007). By using an optimal cutoff threshold based on a receiver operating characteristic analysis, mean hemispheric asymmetry predicted one-year seizure freedom with 93% sensitivity and 71% specificity in the whole group, and with 100% sensitivity and 92% specificity in patients ≥6 years of age. Conclusion In patients with neocortical epilepsy and normal MRI, neocortical thinning in the epileptic hemisphere, particularly in frontal cortex, is associated with poor surgical outcome. Although these results require validation in a larger cohort prospectively, these data suggest that presurgical evaluation of cortical thickness may assist in identification of patients at high risk for surgical failure.

Utility of MRI, PET, and ictal SPECT in presurgical evaluation of non-lesional pediatric epilepsy

“…By using a machine learning approach of regional cortical thickness data, the authors were able to lateralize the epileptic focus (with 92% accuracy in FCD type I and 86% accuracy in FCD type II) and predict surgical outcome (accuracy: 92% in type I and 82% in type II) in the majority of individual subjects. Consistent with these findings, our group reported that neocortical thinning in the epileptic hemisphere, most robust in the frontal lobe, predicted one-year postsurgical seizure freedom with 93% sensitivity and 73% specificity in a pediatric population; these numbers were even better in a subgroup of children above 6 years of age (100%/ 92%, respectively) [15].…”

Regional cortical thickness changes accompanying generalized tonic-clonic seizures

“…Here, we report extensive neocortical thinning in selected areas in patients with GTCS relative to controls, particularly in frontal cortex. Frontal neocortex thinning is common in frontal or idiopathic generalized epilepsies ( Bernhardt et al, 2009 ; Hong et al, 2016 ), but also occurs in temporal lobe epilepsy ( Bernhardt et al, 2008 ; Lin et al, 2007 ), where such thinning is associated with poor surgical outcome ( Kamson et al, 2016 ), and tends to correlate with duration of epilepsy and seizure frequency ( Bernhardt et al, 2009 ; Lin et al, 2007 ). Neocortical thinning, particularly of the frontal cortex, may stem from remodeling of thalamocortical networks, brought on by repeated GTCS ( Bernhardt et al, 2009 ), a possibility consistent with reported thalamic gray matter reductions in SUDEP and high SUDEP-risk patients ( Wandschneider et al, 2015 ).…”

Intracranial hypertension and cortical thickness in syndromic craniosynostosis

“…It remains unclear what effects ICH may have on structural neurological development in syndromic craniosynostosis. Cortical thickness is an important in vivo biomarker for cognitive ability and may provide valuable insight regarding potential changes due to ICH . As a subcomponent of cortical volume, cortical thickness reflects neuronal density per column, dendritic arborization, and glial support .…”