Electroencephalographic focal epileptic discharge and determinants of generalizations

Following the stroke, epilepsy is the second wide-ranging neurological disease in the world. In spide of the valuable and updated treatment approachs, even in the countries in those the health care and patient management systems are well developed, the seizures are not controlled in 20-35% of patients. The concept of estimation of seizure before occurrence through clinical and/or electrophysiological signs manifasted in such patients is challenging and in the last few decades the research in this direction is increasingly continuing. Herein, the main purpose is to prevent seizures by an early alarming system. However a safe seizure or a seizure at a desired place is important in the planning of the treatment.Using the electromagnetic brain waves that we have considered as important in seizure prediction, a variety of signal processing algorithms were conducted on the EEG for investigation of the electrical properties of spikes emerged in the EEG in terms of how they do generalize, either there is an marker or particular pattern before their generalization.In this study, firstly the time-frequency characteristic of EEG and the spikes were represented. It was found that as the seizure time approaches the energy content of the electrical signal is gradually reduces until the occurrence of seizure. This reduction was much evident in the particular sites that were considered as epileptic focus.The temporal and spatial synchronization between the recording sites were quantified in terms of signal?s phase and energy content. A nonuniform reduction in the phase and energy synchronisation index was observed before the partial or absolute spike generalization those were not leading to seizure. It was found that the energy synchronisation index is decay to below 0.2 just before the emergence of spike generalization and after the generalization this index was raises back to its normal value; around 0.3-0.4. Interestingly these characteristics found in the epileptic EEG was not encountered in the nonepileptic EEG.From an alternative point of wiev, if the whole brain medium considered as an electromagnetic system, one may consider that minor and/or major ubnormal structures within the brain might have affected the funcion of the system and this had reflected into the EEG records. The spikes found in the EEG, in this case, may be considered as the reflections of the controlling mechanizm (in the form of exitation or inhibition) for preventig the brain from unexpected circumstances. In other words, in case of considering the brain is an electromagnetic system each time of the reduction observed in the energy index we thought that the structures that provides energy for brain functioning are controlled somehow with the involvement of the controlling mechanisms. If this is the case, we wonder if the the required energy sources for sustaining brain functioning in a reliable way dos not function well or the need for energy is extremely increased? is the energy provided to the system is a rapid correcting action? Therefore we have considered the spikes are the sign of the struggle of brain for maintaining its function reflected into EEG.If the occurance of spikes could be considered as a result of such a process, a supeculation for the occurrence of seizure may be made: The seizure is the reflection of a secondary controlling mechanism in case of the failure or insufficiency of the primary controlling mechanism.The results found in this study implied that, the markers attached to spikes need to be considered in the seizure prediction algorithms based on EEG.