Abstract Details

Title Virtual Cortical Resection Reveals Epileptic Network Characteristics in Pediatric Patients with Focal Cortical Dysplasia.

Topic Epilepsy/Clinical Neurophysiology (EEG)

Presentation(s) S36 - Epilepsy/Clinical Neurophysiology (EEG) II (1:22 PM-1:33 PM)

Poster/Presentation
Number 003

Background Synchronizability measures the efficiency of signal diffusion through an interconnected network with synchronizing (promoting) or desynchronizing (impeding) brain regions altering overall network function. Understanding the interplay between synchronizing and desynchronizing regions may shed light upon mechanisms of seizure onset, propagation, and epilepsy surgery failure. This study uses the virtual cortical resection technique to study synchronizability in children.

Objective To identify regions that synchronize or desynchronize the epileptic network in children with focal cortical dysplasia (FCD).

Design/Methods Eight pediatric patients with Taylor-type II FCD (IIa: n = 4, IIb: n = 4) underwent invasive intracranial grid EEG monitoring. Two electrophysiologists blinded to histopathological diagnosis marked the seizure onset electrodes. Functional connectivity networks were derived from two minute pre-ictal segments using magnitude-squared coherence. Each node’s ‘synchronizing’ or ‘desynchronizing’ influence was determined by removing the node and calculating the change in network synchronizability. Two-year surgical outcome was assessed using the Engel Outcome Scale.

Results Overall network synchronizability did not significantly differ between FCD IIa and FCD IIb patients, or between seizure-free and seizure-persistent patients. Highly desynchronizing nodes were more likely to localize within the seizure onset zone in the FCD IIa group compared to FCD IIb group (42% vs 21%, p = 0.21), but less likely to localize in the resection zone (11% vs 56%, p = 0.25). All patients, independent of histopathologic diagnosis and outcome, had highly desynchronizing nodes located largely outside the margins of the seizure onset (68%) and resection (67%) zones.

Conclusions Seizure generation is a complex process that likely involves dynamic interactions between brain regions. This study validates previous work on virtual cortical resection and suggests interplay between ‘synchronizing’ and ‘desynchronizing’ brain regions that drive seizure activity. Additionally, our data trends toward a correlation between localization of desynchronizing nodes correlate with histopathologic subtype, suggesting the underlying pathology drives the different local network properties.

Authors/Disclosures
Jeremy Wong, MD (Montefiore Medical Center) PRESENTER	Dr. Wong has nothing to disclose.
Samuel Tomlinson (University of Rochester School of Medicine and Dentistry)	No disclosure on file
Erin C. Conrad, MD (University of Pennsylvania)	Dr. Conrad has received personal compensation in the range of $10,000-$49,999 for serving as a Consultant for Epiminder. Dr. Conrad has stock in Humana. Dr. Conrad has stock in Lilly Eli. Dr. Conrad has stock in Medtronic. Dr. Conrad has stock in Merck. Dr. Conrad has stock in Nevro. Dr. Conrad has stock in Sanofi. Dr. Conrad has stock in United Health Group.
	No disclosure on file
Eric D. Marsh, MD, PhD (Children's Hospital of Philadlephia)	Dr. Marsh has received personal compensation in the range of $500-$4,999 for serving as a Consultant for Acadia Pharmacuticals. Dr. Marsh has received personal compensation in the range of $500-$4,999 for serving as a Consultant for Stoke Therapeutics. Dr. Marsh has received personal compensation in the range of $500-$4,999 for serving on a Scientific Advisory or Data Safety Monitoring board for Acadia Pharmaceuticals. The institution of Dr. Marsh has received research support from NIH. The institution of Dr. Marsh has received research support from Rett Syndrome Research Trust. The institution of Dr. Marsh has received research support from International Rett Syndrome Foundation. The institution of Dr. Marsh has received research support from Eagles Autism Challenge. The institution of Dr. Marsh has received research support from LouLou Foundation. The institution of Dr. Marsh has received research support from International CDKL5 Resarch Foundation. The institution of Dr. Marsh has received research support from Acadia Pharmaceuticals. The institution of Dr. Marsh has received research support from Marinus. The institution of Dr. Marsh has received research support from Stoke Therapeutics. The institution of Dr. Marsh has received research support from Takeda Pharmaceuticals. Dr. Marsh has received personal compensation in the range of $500-$4,999 for serving as a Grant Review with NIH. Dr. Marsh has received personal compensation in the range of $5,000-$9,999 for serving as a Expert Witness with Department of Human Services. Dr. Marsh has received personal compensation in the range of $500-$4,999 for serving as a Speaker with Medscape.

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