Authors :
Presenting Author: Bruno Hidalgo, BS – Vanderbilt University Medical Center
Ghassan Makhoul, BS – Vanderbilt University Medical Center
Derek Doss, PhD – Vanderbilt University
Anas Reda, MS – Vanderbilt University Medical Center
Addison Cavender, BS – Vanderbilt University Medical Center
Emily Liao, BE – Vanderbilt University Medical Center
Sameer Sundrani, – Vanderbilt University Medical Center
Kate Wang, BE – Vanderbilt University Medical Center
Graham Johnson, MD, PhD – Mayo Clinic
Angela Crudele, MD – Vanderbilt University Medical Center
Catie Chang, PhD – Vanderbilt University
Shawniqua Williams Roberson, MEng, MD – Vanderbilt University Medical Center
Victoria Morgan, PhD – Vanderbilt University Medical Center
Dario Englot, MD PhD – Vanderbilt University Medical Center
Rationale:
Seizures in focal epilepsy are increasingly regarded to emerge from network interactions with seizure onset zones (SOZs) and early propagative zones (EPZs)[1]. The Interictal Suppression Hypothesis (ISH) posits that SOZs and EPZs receive interictal network suppression which increases during the preictal state and subsequently collapses as seizures propagate[2]. Although closed-loop neuromodulation (CLN) is thought to intervene on epileptic networks, the optimal timing and network targets for stimulation remain unclear. Further elucidating the mechanisms described by the ISH may offer insights to improve CLN. In this work, we show that increased suppression of SOZs and EPZs may serve as an interictal biomarker of seizure risk and demonstrates band-specificity.
Methods:
We studied 30 patients with drug-resistant focal epilepsy undergoing presurgical evaluation with stereo-EEG electrodes at Vanderbilt University Medical Center. Regions are designated as SOZs if they initiate seizures and EPZs if they are recruited within 10 seconds of seizure onset. Directed connectivity between regions was calculated using partial directed coherence (PDC) across frequency bands, where greater net PDC indicates more inward connectivity. We defined 30-minute interictal epochs as either baseline (no seizures within 4 hours) or high risk (HR; seizure within 30 minutes). Preictal and ictal epochs were defined as the 5 minutes before seizure onset and the seizure duration, respectively. A linear mixed effects model was used to assess band-wise statistical differences across regions and states. Asterisks on figures indicate p-value < 0.01.