Dynamics of Epileptic Seizures During Evolution and Propagation

Epileptic seizures are rapidly evolving dynamic events which typically last less than two minutes. The need to understand better the dynamics of these transient events is important in part because of increased interest in responsive neurostimulation as potential therapy for epileptic seizures. The matching pursuit (MP) decomposition and Gabor atom density (GAD) are modern techniques which allow detailed time-frequency decomposition (MP) and quantification of complexity changes (GAD). This allows investigations of seizure onset, evolution and propagation of rapidly changing epileptic phenomena with a new perspective and a new level of precision. Using these methods has revealed increased complexity at the onset of many seizures and remarkable similarity of ictal onset patterns from multiple seizures from a single focus in a given patient. These methods can potentially provide insights into network mechanisms contributing to seizure generation and propagation. This chapter illustrates the application of these techniques to partial seizures recorded from intracranial arrays in humans undergoing presurgical evaluations and demonstrates the possibility to identify specific ictal phases. Understanding these specific ictal dynamics can provide information that may assist seizure detection and understanding of the dynamics that contribute to propagation and seizure termination.