Epileptic focus location in the cerebral cortex using linear techniques and complex networks

The epileptic focus is an area of the cerebral cortex that is essential for the generation of seizures. It is the region where epileptic seizures begin, or the site with the most ictal activity, also known as the epileptogenic zone. On a clinical approach, the identification and study of the epileptic focus can aid in the diagnosis and treatment of patients with epilepsy; thereby, the automatic determination of its quantitative characteristics could be helpful. In this paper, we present a methodology based on clinical guidelines for the automatic identification of the epileptic focus and its dynamics using complex networks and linear techniques. This methodology identifies the EEG channels with the most frequent and lasting ictal events. Furthermore, the propagation of seizures on the cortex can be determined as well as the EEG channels through which seizures propagate. Our approach leads to estimate the connectivity parameters of the cerebral networks generated during seizure events such as the degree and clustering coefficient of the network’s nodes with the highest prevalence. The efficiency of seizure identification was computed in about 97.2%. This methodology allows to identify the zone with the highest ictal activity and its dynamical characteristics, and whether the identified channels are located in the same region in the cerebral cortex or if they are contiguous. All this information could help neurologists in the diagnosis and analysis of the dynamics of epileptic seizures in case the primary studies were non-conclusive.