Pre-seizure architecture of the local connections of the epileptic focus examined via graph-theory

- Graph theory application on brain connectivity is useful to analyze brain information processing.
- Firing abnormalities in synchronized neuronal assemblies are involved in “aberrant” connectivity in pathological processes.
- Excessive binding of “aberrant” connections can progressively lead to electroclinical seizure attacks.

ObjectiveEpilepsy is characterized by unpredictable and sudden paroxysmal neuronal firing occurrences and sometimes evolving in clinically evident seizure. To predict seizure event, small-world characteristic in nine minutes before seizure, divided in three 3-min periods (T0, T1, T2) were investigated.MethodsIntracerebral recordings were obtained from 10 patients with drug resistant focal epilepsy examined by means of stereotactically implanted electrodes; analysis was focused in a period of low spiking (Baseline) and during two seizures. Networks' architecture is undirected and weighted. Electrodes' contacts close to epileptic focus are the vertices, edges are weighted by mscohere (=magnitude squared coherence).ResultsDifferences were observed between Baseline and T1 and between Baseline and T2 in theta band; and between Baseline and T1, Baseline and T2, and near-significant difference between T0 and T2 in Alpha 2 band. Moreover, an intra-band index was computed for small worldness as difference between Theta and Alpha 2. It was found a growing index trend from Baseline to T2.ConclusionsCortical network features a specific pre-seizure architecture which could predict the incoming epileptic seizure.SignificanceThrough this study future researches could investigate brain connectivity modifications approximating a clinical seizure also in order to address a preventive therapy.