Abstract Details

Title Long-term Stability of Interictal Spike Trajectories in Pediatric Invasive EEG Recordings

Topic Epilepsy/Clinical Neurophysiology (EEG)

Presentation(s) P4 - Poster Session 4 (5:30 PM-6:30 PM)

Poster/Presentation
Number 6-003

Objective To understand the temporal relationship between interictal spike propagation and seizures.

Background Interictal spikes frequently propagate from regions of onset (i.e., ‘leaders’) to distant targets (i.e., ‘followers’). Previous studies suggest that ‘leader’ regions have greater epileptogenic potential than ‘follower’ regions, but this claim remains contentious. The present study aimed to: (1) assess the reproducibility of spike trajectories over long interictal recordings; and (2) describe the relationship between spike trajectories and seizures.

Design/Methods Invasive EEG recordings were obtained from 25 children monitored with subdural electrodes. Seizures were manually excluded, and interictal spikes were detected with validated algorithms. Spikes with a peak time <50 ms from the ‘leader’ were grouped as a propagation trajectory. Trajectories were clustered based on the extent of spatiotemporal overlap. Each trajectory cluster was assigned a ‘reproducibility coefficient’ ranging from 0 (i.e., no spatiotemporal reproducibility across trajectories) to 1 (i.e., all trajectories were identical), which was evaluated against a surrogate distribution. Two-year surgical outcomes were classified using the Engel scale (Class I: Seizure-Free, n = 11; Class ≥II: Seizure-Persistent, n = 14).

Results In total, >2,300 hours of interictal EEG were examined (Mean ± SD/patient = 105.4 ± 113.3 hours). Of 82 trajectory clusters identified across patients, 70/82 (85.4%) had a statistically-significant reproducibility coefficient. The average reproducibility coefficient across clusters was 0.32 ± 0.18 (mean for surrogate clusters: 0.04 ± 0.03; p <0.001). ‘Leader’ regions localized to the seizure onset zone more frequently than ‘follower’ regions (Chi-squared, p <0.001). The number of significant trajectory clusters per patient did not differ by surgical outcome (Seizure-Free: 2.4 ± 0.9; Seizure-Persistent: 2.5 ± 1.3; p = 0.68).

Conclusions Interictal spike trajectories were remarkably stable over hours to days of interictal recording. ‘Leader’ regions appear to localize preferentially to the seizure onset zone. Mapping propagation ‘leaders’ may help identify hubs of increased epileptogenicity.

Authors/Disclosures
Samuel Tomlinson (University of Rochester School of Medicine and Dentistry) PRESENTER	No disclosure on file
Jeremy Wong, MD (Montefiore Medical Center)	Dr. Wong has nothing to disclose.
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.
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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