Ictal gamma-band interactions localize ictogenic nodes of the epileptic network in focal cortical dysplasia. Issue 8 (August 2021)

• Record Type: Journal Article
• Authors: Janca, Radek; Jahodova, Alena; Hlinka, Jaroslav; Jezdik, Petr; Svobodova, Lenka; Kudr, Martin; Kalina, Adam; Marusic, Petr; Krsek, Pavel; Jiruska, Premysl
• Is Part Of: Clinical neurophysiology. Volume 132:Issue 8(2021)
• Page Start: 1927
• Page End: 1936
• Publication Date: 2021-08
• Subjects: Epilepsy -- Effective connectivity -- Intracranial EEG -- Networks -- Seizure onset zone -- Outcome; AIC Akaike information criterion -- DTF directed transfer function -- ECoG electrocorticography -- EZ epileptogenic zone -- FCD focal cortical dysplasia -- FFT fast Fourier transform -- FN false negative -- FP false positive -- ICN ictogenic node -- iEEG intracranial EEG -- MCC Matthews correlation coefficient -- MNI Montreal Neurological Institute -- MVAR multivariate autoregression -- OUT outside the seizure onset zone -- PPV positive predictive value -- PSD power spectral density -- RES resection -- SEEG stereo-EEG -- SEN sensitivity -- SOZ seizure onset zone -- TN true negative -- TP true positive; Neurophysiology -- Periodicals; Electroencephalography -- Periodicals; Electromyography -- Periodicals; Neurology -- Periodicals; 612.8
• DOI: 10.1016/j.clinph.2021.04.016
• Languages: English
• ISSNs: 1388-2457

Abstract

Highlights: Decreased effective gamma-band connectivity represents a seizure-related reconfiguration of the epileptic network. Ictogenic nodes discriminate areas actively generating seizure activity from areas of passive propagation. Resection of ictogenic nodes is a key factor associated with favorable surgical outcome. Abstract: Objective: Epilepsy surgery fails in > 30% of patients with focal cortical dysplasia (FCD). The seizure persistence after surgery can be attributed to the inability to precisely localize the tissue with an endogenous potential to generate seizures. In this study, we aimed to identify the critical components of the epileptic network that were actively involved in seizure genesis. Methods: The directed transfer function was applied to intracranial EEG recordings and the effective connectivity was determined with a high temporal and frequency resolution. Pre-ictal network properties were compared with ictal epochs to identify regions actively generating ictal activity and discriminate them from the areas of propagation. Results: Analysis of 276 seizures from 30 patients revealed the existence of a seizure-related network reconfiguration in the gamma-band (25–170 Hz; p < 0.005) – ictogenic nodes. Unlike seizure onset zone, resecting the majority of ictogenic nodes correlated with favorable outcomes ( p < 0.012). Conclusion: The prerequisite to successful epilepsy surgery is the accurate identification of brain areas from which seizures arise. We show that in FCD-related epilepsy, gamma-band network markers can reliably identify and distinguish ictogenic areas in macroelectrode recordings, improve intracranial EEG interpretation and better delineate the epileptogenic zone. Significance: Ictogenic nodes localize the critical parts of the epileptogenic tissue and increase the diagnostic yield of intracranial evaluation.