Chapter 2. Mechanisms of changes in dynamic complexity of EEG patterns in epileptic brain injury

Abstract

The second chapter is devoted to elucidating the mechanisms underlying the changes in the dynamic complexity of EEG patterns in disorders of the functional state of the brain associated with epileptic injuries, and modeling the possibility of automatic detection of epileptic discharges based on a comparative study of changes in wavelet spectra and the degree of multifractality of EEG patterns in patients with partial symptomatic epilepsy before, during and after epileptic discharges, as well as when opening the eyes and during hyperventilation during periods of absence of epileptic discharges. Comparative analysis of changes in wavelet spectra and in degree of multifractality of EEG patterns in patients with partial symptomatic epilepsy before, during and after epileptic discharges, as well as during covering the eyes and with hyperventilation during periods of absence of epileptic discharges, proved that changes in the values of multifractal parameters and the maximum of the global energy of the EEG wavelet spectrum can be used to automatically distinguish between periods before, during and after an epileptic discharge. Using multifractal analysis, it was found that the mechanism of changes in the dynamic complexity of EEG patterns during the occurrence of epileptic discharges is based on an increase in the contribution of weak fluctuations of successive EEG values, leading to an increase in their correlation and a significant increase in the energy of the wavelet spectrum and the degree of multifractality of the pattern in the preictal period.