Current Conceptual Understanding of the Epileptogenic Network From Stereoelectroencephalography-Based Connectivity Inferences

Kanupriya Gupta; Pulkit Grover; Taylor J Abel

doi:10.3389/fneur.2020.569699

Current Conceptual Understanding of the Epileptogenic Network From Stereoelectroencephalography-Based Connectivity Inferences

Front Neurol. 2020 Nov 25:11:569699. doi: 10.3389/fneur.2020.569699. eCollection 2020.

Authors

Kanupriya Gupta^{1

2}, Pulkit Grover^{3

4}, Taylor J Abel^{1

2

3

5}

Affiliations

¹ University of Pittsburgh School of Medicine, Pittsburgh, PA, United States.
² Department of Neurological Surgery, University of Pittsburgh, Pittsburgh, PA, United States.
³ Center for the Neural Basis of Cognition, Carnegie Mellon University/University of Pittsburgh, Pittsburgh, PA, United States.
⁴ Department of Electrical and Computer Engineering, Carnegie Mellon University, Pittsburgh, PA, United States.
⁵ Department of Bioengineering, University of Pittsburgh, Pittsburgh, PA, United States.

Abstract

Localization of the epileptogenic zone (EZ) is crucial in the surgical treatment of focal epilepsy. Recently, EEG studies have revealed that the EZ exhibits abnormal connectivity, which has led investigators to now consider connectivity as a biomarker to localize the EZ. Further, abnormal connectivity of the EZ may provide an explanation for the impact of focal epilepsy on more widespread brain networks involved in typical cognition and development. Stereo-electroencephalography (sEEG) is a well-established method for localizing the EZ that has recently been applied to examine altered brain connectivity in epilepsy. In this manuscript, we review recent computational methods for identifying the EZ using sEEG connectivity. Findings from previous sEEG studies indicate that during interictal periods, the EZ is prone to seizure generation but concurrently receives inward connectivity preventing seizures. At seizure onset, this control is lost, allowing seizure activity to spread from the EZ. Regulatory areas within the EZ may be important for subsequently ending the seizure. After the seizure, the EZ appears to regain its influence on the network, which may be how it is able to regenerate epileptiform activity. However, more research is needed on the dynamic connectivity of the EZ in order to build a biomarker for EZ localization. Such a biomarker would allow for patients undergoing sEEG to have electrode implantation, localization of the EZ, and resection in a fraction of the time currently needed, preventing patients from having to endure long hospital stays and induced seizures.

Keywords: EZ; Granger causality; SEEG; biomarker; connectivity; epileptogenic; focal epilepsy.

Publication types

Review