Abstract Details

Title Interictal Spike Propagation Patterns in Adults with Epilepsy Evolve Over Time

Topic Epilepsy/Clinical Neurophysiology (EEG)

Presentation(s) S3 - Epilepsy/Clinical Neurophysiology (EEG) I (2:28 PM-2:39 PM)

Poster/Presentation
Number 009

Background Interictal spikes play an important role in the diagnosis of epilepsy. The propagation of interictal spikes elucidates seizure networks and predicts seizure outcomes in epilepsy surgery. An improved understanding of the temporal evolution of spike propagation will have implications for sampling times needed to capture the interictal network.

Objective To determine the temporal evolution of interictal spike propagation patterns.

Design/Methods We prospectively collected intracranial EEG (iEEG) data from 46 patients with localization related epilepsy, implanted with a combination of grids, strips, and depth electrodes. We selected nine patients with frequent visually recognizable spikes. We analyzed the iEEG in the 24 hours surrounding each seizure using our published spike sequence detector. For each sequence, we calculated the direction vector between the mean location of the earliest activated electrodes to the mean location of the terminal electrodes. We compared these spike sequence-specific direction vectors across hour-long EEG segments using MANOVA.

Results The range of spike sequences detected per patient was 329 to 13,049. The number of electrodes accounting for 90% of the total spikes in sequences ranged from 20-79 (17-78% of all electrodes) across the nine patients. Spike propagation vectors varied significantly in the 24 hours surrounding seizures for eight of the nine patients (p = 0.02 - < 0.001). One patient had no significant change in the spike propagation vectors over time (p = 0.16).

Conclusions Spike propagation patterns evolved from hour to hour for the majority of studied patients. This temporal change in spike vector trajectory suggests underlying variability in network dynamics over time and implies that at least several hours of iEEG data are needed to establish spike propagation patterns. Future work will focus on elucidating the mechanisms underlying the temporal evolution of spike propagation.

Authors/Disclosures
Erin C. Conrad, MD (University of Pennsylvania) PRESENTER	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.
Samuel Tomlinson (University of Rochester School of Medicine and Dentistry)	No disclosure on file
Jeremy Wong, MD (Montefiore Medical Center)	Dr. Wong has nothing to disclose.
Kathryn A. Davis, MD (University of Pennsylvania)	Dr. Davis has received personal compensation in the range of $500-$4,999 for serving as a Consultant for GW Pharmaceuticals/Jazz Pharmaceuticals. Dr. Davis has received personal compensation in the range of $500-$4,999 for serving as a Consultant for Spark Therapeutics. Dr. Davis has received personal compensation in the range of $500-$4,999 for serving on a Scientific Advisory or Data Safety Monitoring board for UCB. Dr. Davis has received personal compensation in the range of $500-$4,999 for serving on a Scientific Advisory or Data Safety Monitoring board for UNEEG. Dr. Davis has received personal compensation in the range of $500-$4,999 for serving as an Editor, Associate Editor, or Editorial Advisory Board Member for Epilepsia Open. Dr. Davis has received personal compensation in the range of $10,000-$49,999 for serving as an Expert Witness for Pfizer. The institution of Dr. Davis has received research support from Eisai. The institution of Dr. Davis has received research support from Liminal. Dr. Davis has received publishing royalties from a publication relating to health care.
Brian Litt, MD (Univ of Penn Dept of Neurology)	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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