P.008 Functional network reorganization in temporal lobe epilepsy: looking beyond the hippocampus

Abstract

Background: Temporal lobe epilepsy (TLE) has been redefined as a disorder associated with network-level dysfunction not limited to the epileptic zone. As such, as resting state (rs) fMRI has been used to evaluate the implicated resting state networks (RSN) and their ensuing functional impairments. However, few studies have analyzed patients with (TLE-HS) and without (TLE-nonHS) hippocampal sclerosis independently. Whereas TLE-HS often warrants surgical intervention, drug-resistant TLE-nonHS might pose challenges for diagnosis and treatment decisions. Methods: This study aimed to investigate functional connectivity changes (FC) of RSNs beyond the hippocampus using rs-fMRI. Rs-fMRI data was acquired from 16 TLE-HS and nine TLE-nonHS, along with 25 healthy controls (HC). RSNs were established using a data-driven independent component analysis approach, in order to determine significant connections between HC and patient groups ipsilateral and contralateral to the seizure focus. Results: When comparing TLE-HS to HC, FC changes were found for the dorsal-attentional (DAN), visual, fronto-parietal (FPN), sensorimotor and default-mode networks (DMN). Alterations in the DAN, DMN and FPN were found when comparing TLE-nonHS to HC. Conclusions: This study demonstrated widespread network reorganization across TLE subtypes. These FC patterns hold promise as a prognostic biomarker, and may be used to define subsequent function and dysfunction in this patient population.