Abstracts

Rationale:
Frequent focal seizures carry a high risk of significant disability and cognitive impairment. Recent high-density EEG work suggests the presence of local connectivity increases in focal epilepsy networks (Boly et al., Brain 2017). Because intracranially, focal seizures propagate in a nearest-neighbor fashion, we hypothesize that they may induce increases in cortico-cortical connectivity that are especially pronounced in the short distance range in the epileptic network of patients with temporal lobe epilepsy (TLE). We also hypothesized that secondarily generalized seizures may be accompanied by connectivity changes outside of the limbic network.
Method:
We analyzed data from 51 TLE patients (age range 20-57) part of the Epilepsy Connectome Project (ECP). Resting-state fMRI data were obtained using 3T MRI Human Connectome Project (HCP) sequences and preprocessed using the HCP pipeline (Glasser et al. 2013) plus a nuisance regression approach (Satterthwaite et al. 2013). For each subject, vertex-wise matrices of correlation with neighbors at short (0-6mm) and long (105-175) distances as well as the average connectivity across all distances were computed. Using Statistical Parametric Mapping software (SPM), random effects models assessed for a correlation between the monthly frequency of focal aware/focal impaired partial seizures (FA/FI), and general tonic-clonic seizures (GTC) with short range, long range and average connectivity. Results were considered significant at p< 0.05 corrected for multiple comparisons at the cluster level using SPM and/or using Probabilistic Threshold-free Cluster Enhancement (pTFCE) as implemented in SPM.