Abstracts

Rationale: Neuroimaging studies of functional connectivity (FC) using graph theory have furthered our understanding of the network structure in temporal lobe epilepsy (TLE) and its relation to clinical features. Potential brain network effects of antiepileptic drugs (AEDs) could influence such studies, but have not been systematically studied. Methods: Resting state fMRI was analyzed in 37 subjects (14 left TLE, 11 right TLE, 12 healthy controls) using graph theory analysis. Patients were divided into four groups for analysis based on AED usage as follows: (1) carbamazepine/ oxcarbazepine, (2) levetiracetam, (3) lamotrigine, (4) lacosamide. The following graph topology metrics were analyzed: global efficiency, betweenness centrality, clustering coefficient, and small-world index. Multiple linear regression techniques were used to examine the association of AEDs with graph topology adjusting for other potential confounds. Results: The four groups did not differ from each other based on epilepsy characteristics. The following associations were determined with the different AED groups: (1) Use of carbamazepine/ oxcarbazepine and "other AEDs" were associated with a higher global efficiency and small-world index; (2) AED polytherapy was associated with a higher betweenness centrality and lower small-world index; (3) independent of AED use, epilepsy duration was associated with decreased betweenness centrality and clustering coefficient; and (4) left TLE was associated with lower global efficiency compared to controls. Conclusions: AED use seems to be associated with various changes in network small-world metrics. These findings can inform graph theory based studies in patients with TLE. The changes we observed could be related to the mechanism of action, or adverse effect profiles of AEDs.