Plenary Session V – General Epilepsy I Functional Connectivity In Epileptic Brain

Brain is a large-scale network of specific functions interconnected to each other. These connections have been described anatomically as bundles of nerve fibers, a part of which can be visualized, recently, by MRI diffusion tensor imaging (DTI). However, those anatomical, or structural, connections do not seem to represent all the connections functionally important for integrated neural activities. In the present study, we analyzed MRI data with graph theory to find alterations in structural as well as functional connectivity in patients with epilepsy. Methods: Interictal MRI of patients with mesial (n=3) and non-mesial (n=6) temporal lobe epilepsy were studied. Structural connectivity was analyzed with DTI-statistical parametric mapping (SPM) and tract-based special statistics (TBSS) for fraction anisotropy (FA). Functional connectivity was studied by analyzing MRI-echo-planner imaging (EPI) with independent component analysis (ICA). Results: In all patients with mesial temporal lobe epilepsy, FA was decreased bilaterally in the hippocampus. In patients with non-mesial temporal lobe epilepsy, FA was decreased only in the side of hippocampal sclerosis ( n=4). Although functional connectivity was affected in the hippocampus of lesion side in patients with mesial temporal lobe epilepsy, it was also affected in a large area of both hemispheres. Conclusions: The present study suggested that wide ranges of connections are affected in the epileptic brain, not limited to the epileptogenic lesions. Those quantitative understanding of the pathophysiology of neural connections may lead to the more sophisticated approach for surgical intervention of this disease