Spatial and temporal analysis of interictal activity in the epileptic brain

Abstract

In clinical and research settings numerous algorithms have been developed for the analysis of electroencephalographic (EEG) data in the diagnosis of epilepsy and throughout the process of localizing the seizure onset zone (SOZ). This research highlights the merging of two major detection algorithms for the identification of High-Frequency Oscillations (HFO), also known as ripples, and Interictal Spikes (IIS) in both the spatial and temporal domain. IIS and HFO have become recognized as reliable biomarkers in identification of the epileptic focus in the cortex of epileptic patients. While IIS, commonly referred to as spikes, have classically been used for the diagnosis of epilepsy and for source localization techniques, ripples have been associated with more generalized cortex regions of interest and surrogate biomarkers for the seizure onset zone (SOZ). This research aims to combine these two analyses by correlating HFO and IIS events in the time domain for each electrode recording with the goal of yielding a more complete understanding of the abnormal electrical activity of the cortex in epileptic patients. Results are offered in the form HFO and IIS events per electrode as well as a surface representation of the number of temporally superimposed HFO and IIS per electrode.