Event-Triggered Visualization Identifies Distinct Ictogenesis Epileptiform Discharge Metamorphosis in Mesial Temporal Lobe Epilepsy
Abstract number :
3.042
Submission category :
1. Basic Mechanisms / 1C. Electrophysiology/High frequency oscillations
Year :
2025
Submission ID :
161
Source :
www.aesnet.org
Presentation date :
12/8/2025 12:00:00 AM
Published date :
Authors :
Presenting Author: Spencer Chen, PhD – Rutgers University
Celina Zhou, BSE – Rutgers University
Isaac Huang, BA – Rutgers University
Fabio Tescarollo, PhD – Rutgers University
Ezequiel Gleichgerrcht, M.D., Ph.D. – Emory University
Hai Sun, MD, PhD – Rutgers University
Rationale: Seizure initiation on EEG is typically identified with escalating epileptiform discharges (ED), either in amplitude and/or frequency. Previous reports also found changing morphology of ED associated with the ictogenesis process, such as the emergence of spike-and-wave or high-frequency oscillations. By adopting an event-triggered rearrangement of EEG recording, we exploit this changing ED morphology to visualize and investigate the activity escalation process that initiates seizures.
Methods: Intracortical EEG recordings of seizures were obtained from 15 mice with the intrahippocampal kainic acid (IHKA) model of mesial temporal lobe epilepsy (MTLE) and 10 human MTLE patients who underwent SEEG assessment at Emory University. Peak detection was performed on the EEG recordings to identify events above a set threshold (typically 3-5x the median absolute deviation). EEG segments were extracted around each detected peak, rearranged into a voltage heatmap, with the y-axis representing millisecond-scale voltage fluctuations, and the x-axis indexing successive detected peaks to visualize the evolution of the ED morphology over time (the Pulsogram, Fig. 1a).
Results: ED morphology undergoes a step-wise transition from inter-ictal baseline as it progresses into a seizure. This transition was clearly identified on the Pulsogram in the seizures of all 15 IHKA mice (Fig. 1b) and 10 out of 11 human patients (Fig. 2a,b). Several variants of metamorphosis patterns were found. The initial ED transitional point is typically marked by multiphasic activity centered around the main peak, appearing like zebra bands on the Pulsogram. The spacing between the zebra bands often compresses or expands over time, creating a concertina effect, followed by a second transitional point marked by either an abrupt increase in ED amplitude and/or a new phase of morphological evolution. Additional transitional points are often also visible. We refer to the activity between the first and second transitional points as the Reverberant Phase (RP) of ictogenesis, representing the escalation towards seizure initiation. In IHKA animals, RP was observed in 95% of the seizures. The median duration of IHKA RP was 10.0s (2.4-46.4s, 95th percentile) and was uncorrelated with the Racine seizure severity (r=0.0, p=0.79). RP was observed in the hippocampus concurrently on both the ipsilateral and contralateral sides of the IHKA injection. We are currently analyzing these for potential synergistic ictogenic interactions. The human MTLE RP is currently being reviewed for quantitative analysis.
Conclusions: We present a novel approach to analyzing ictogenic ED associated with seizures, applicable to various seizure phenotypes and across both preclinical and clinical intracranial EEG recordings. We believe this captures a recurring pattern of escalating activity that underlies the initiations of seizures. Understanding the mechanisms behind seizure initiation can revolutionize seizure treatment for epilepsy patients. We anticipate analysis of the captured escalation patterns to provide insight into therapeutic seizure control by specifically targeting the mechanisms through which seizures are initiated.
Funding: N/A
Basic Mechanisms