Paroxysmal Slowing Linked to Drug-resistant Epilepsy and Poor Surgical Outcomes
Abstract number :
3.262
Submission category :
3. Neurophysiology / 3C. Other Clinical EEG
Year :
2024
Submission ID :
37
Source :
www.aesnet.org
Presentation date :
12/9/2024 12:00:00 AM
Published date :
Authors :
Presenting Author: Yonatan Serlin, MD – National Institutes of Health
Hamza Imtiaz, MEng – Dalhousie University, Faculty of Medicine
Tamir Avigdor, MSc – Analytical Neurophysiology Laboratory, Montreal Neurological Institute and Hospital, McGill University, Montreal, QC, Canada
Anna Minarik, BSc – Dalhousie University
Sina Lash, BSc – Dalhousie University
Timothy Bardouille, PhD – Dalhousie University
Ben Whatley, MD – Dalhousie University
Kristin M. Ikeda, MD – Dalhousie University
Dan Z. Milikovsky, MD PhD – Tel Aviv University
Sara Inati, MD – National Institutes of Health
Theodor Rüber, MD – University of Bonn
Rainer Surges, Univ.-Prof. Dr. med. – Department of Epileptology, University of Bonn Medical Center, Bonn, Germany
Felix Benninger, MD PhD – Tel Aviv University
Attila Rácz, MD – University of Bonn
Alon Friedman, MD PhD – Dalhousie University
Rationale: Intermittent periods of slowing in EEG, where the median power frequency drops below 6 Hz for ≥5 consecutive seconds, are defined as paroxysmal slow wave events (PSWEs). Recent studies have demonstrated that PSWEs can predict epilepsy in patients after their first seizure and are associated with a higher risk for drug-resistant epilepsy (DRE) using data from routine outpatient EEGs in a large open-source database (Temple University Hospital). Our current study aimed to assess and validate the potential of PSWEs as predictive biomarkers for treatment outcomes and their co-occurrence with ictal activity, in a well-defined cohort of epilepsy patients.
Methods: For EEG preprocessing and signal analysis, we used EEGLAB and custom-developed MATLAB scripts. PSWEs were detected and quantified in routine EEG recordings of 95 patients with either drug-responsive or drug-resistant focal epilepsy at the University Hospital Bonn, Germany. Patients were followed for at least 12 months and had in-depth clinical data and documented follow-up outcomes. In a subset of patients, simultaneous surface and stereotactic EEG (sEEG) recordings were obtained during invasive pre-surgical evaluation.
Results: There was significantly prolonged time in PSWEs (P < 0.0001, AUC = 0.740) and increased mean PSWEs duration (P < 0.0001, AUC = 0.829) in DRE (n = 44) compared with drug-responsive patients (n = 51), indicating fair-to-good DRE classification. Similarly, in patients with poor surgical outcomes (Engel IB-IV, n = 13), pre-surgical EEGs showed significantly prolonged time in PSWEs compared with Engel IA patients (n = 24, P = 0.038). In seizures recorded during pre-surgical evaluations, the onset and propagation of ictal activity were captured early via sEEG, while scalp EEGs failed to detect early ictal changes. Quantitative analysis revealed an increase in the rate, percentage of time, and duration of PSWEs prior to the detection of electrographic seizures on scalp EEG or any clinical manifestations.
Conclusions: Quantitative analysis of PSWEs identifies frequently visibly undetected slow network alterations. Using a well-characterized validation cohort, we confirmed that PSWEs are more prevalent and prolonged in DRE and can indicate a lack of therapeutic response. Additionally, our findings suggest that variations in PSWEs metrics may indicate early, non-propagating ictal activity within deep-seated foci.
Funding: The Canadian Institute for Health Research (CIHR)-ERA-NET grant #168164 (A.F.); CIHR project grant #180636 (B.W., A.F.); The Israel Science Foundation grant #096409 (A.F.); The Israel-USA binational Science Foundation grant # 2021133 (A.F.).
Neurophysiology