Significance of complex analysis of electrical activity in temporal lobe epilepsy: electrocorticography

Locating and excising epileptogenic zones is the traditional treatment in pharmacoresistant temporal lobe epilepsy. Some patients, however, continue to suffer from attacks even after surgery. Therefore, new hypotheses must be formulated in order to account for the apparent shortcomings of correctly performed surgical procedures. An approach that is not traditional in the field, namely complex networks, is used to attempt to show that modifying the properties of the limbic network can lead to the elimination of the attacks, regardless of the location of the epileptogenic zones. The intraoperative electrocorticographic recordings of 20 patients with pharmacoresistant temporal lobe epilepsy were utilised in the study. An analysis of complex networks was used to study the local synchronisation activity in the lateral and mesial cortex of the temporal lobe and, essentially, the zones with the highest temporal stability were determined. Those cortical zones with higher synchronic activity are associated with a greater temporal stability and when these zones are excised during surgery, the patient no longer suffers any disabling attacks. In contrast, when these zones are not excised, the patient continues to have attacks in the post-operative period. The findings support the hypothesis of the existence of a limbic network, which the lateral and mesial cortices of the temporal lobe are part of, and whose capacity to establish an overall synchronisation is affected when certain zones are removed.