Mapping Structural Compromise in Spiking Epileptic Cortex and Connected Tissue: A Multimodal MRI and HD-EEG Study
Abstract number :
3.522
Submission category :
5. Neuro Imaging / 5A. Structural Imaging
Year :
2024
Submission ID :
1607
Source :
www.aesnet.org
Presentation date :
12/9/2024 12:00:00 AM
Published date :
Authors :
Presenting Author: Ella Sahlas, BS – McGill University
Tamir Avigdor, MSc – Analytical Neurophysiology Laboratory, Montreal Neurological Institute and Hospital, McGill University, Montreal, QC, Canada
Alexander Ngo, BS – McGill University
Jessica Royer, PsyD – McGill University
Sara Larivière, PhD – Centre for Brain Circuit Therapeutics, Brigham and Women’s Hospital, Harvard University, Boston, MA, USA
Judy Chen, BS – McGill University
Ke Xie, MSc – McGill University
Yezhou Wang, MSc – Multimodal Imaging and Connectome Analysis Laboratory, McConnell Brain Imaging Centre, Montreal Neurological Institute and Hospital, McGill University, Montreal, QC, Canada
Hans Auer, BSc – Multimodal Imaging and Connectome Analysis Laboratory, McConnell Brain Imaging Centre, Montreal Neurological Institute and Hospital, McGill University, Montreal, QC, Canada
Raul Rodriguez-Cruces, PhD – Multimodal Imaging and Connectome Analysis Laboratory, McConnell Brain Imaging Centre, Montreal Neurological Institute and Hospital, McGill University, Montreal, QC, Canada
Thaera Arafat, MD – Montreal Neurological Institute and Hospital, McGill University
Raluca Pana, MD – McGill University
Andrea Bernasconi, MD – McGill University
Neda Bernasconi, MD, PhD – McGill University
Birgit Frauscher, MD, PhD – Department of Neurology, Duke University School of Medicine, Durham, NC, USA
Boris Bernhardt, PhD – McGill University
Rationale: The advent of high-resolution neuroimaging has revolutionized how epilepsy is understood, diagnosed, and treated. Localizing lesions that harbor epileptogenic activity is especially critical to the care of patients with pharmaco-resistant seizures, which markedly reduce quality of life1. Surgical resection or neutralization of the epileptogenic zone is the most effective treatment for pharmaco-resistant epilepsy2. However, epilepsy surgery remains underutilized3, frequently requires invasive investigations4, and could be optimized by improving pre-operative delineations of the epileptogenic zone and networks5. Further developing non-invasive cartographies of the epileptic brain is thus critical to understanding complex epilepsy pathophysiology and ultimately improving diagnostics. Here, we combined multimodal magnetic resonance imaging (MRI) and high-density electrophysiology (HD-EEG) to interrogate alterations in cortical microstructure, morphology, and local function within and beyond spiking tissue.
Methods: We studied 25 patients with focal epilepsy (12F, mean ± SD age = 31.28 ± 9.30 years) and 55 age- and sex-matched healthy controls, subdivided into a control group of 30 for feature normalization (15F, 31.40 ± 8.74 years) and a control group of 25 for replication of findings (12F, 31.04 ± 5.65 years). All underwent 3T MRI (T1-weighted, diffusion, quantitative relaxometry, and resting-state functional). We derived maps of cortical thickness, mean diffusivity, quantitative T1 relaxometry, intrinsic neural timescales, connectivity distance coefficient, and node degree. We then derived vertex-wise structural and functional alteration multivariate scores. Using HD-EEG, the average preponement spike type was localized at time of maximum amplitude using coherent maximum entropy on the mean. We quantified alteration scores within spike sources, within their neighbors in terms of functional coupling, structural connectivity, and anatomical distance (Fig. 1), and across the rest of the brain.
Results: HD-EEG spike sources showed increased structural MRI alterations: a significantly greater percentage of vertices were structurally altered within spike sources than in the rest of the brain. Significant structural compromise extended to all regions with close functional coupling to spike sources, but not to anatomical neighbors of spike sources (Fig. 2).
Conclusions: Mapping alterations in cortical microstructure and morphology may carry potential to help localize epileptogenic tissue non-invasively. Moreover, our study employs a novel method of vertex-wise multiparametric scoring of alterations in regions with varying connections to spike sources. Results indicate that functional and structural relationships to spike sources may impact the magnitude of alterations in other cortical regions. Results also suggest synergy between MRI and EEG findings for identifying epileptogenic tissue.
1. Loscher et al. 2020. Pharmacol Rev 72(3):606-638.
2. Thijs et al. 2019. Lancet 393(10172):689-701.
3. Samanta et al. 2021. Epilepsy Behav 117:107837.
4. Jirsa et al. 2023. Lancet Neurol 22(5):443-454.
5. Makhalova et al. 2022. Epilepsia 63(8):1942-1955.
Funding: Funded via Fonds de recherche du Québec-Santé.
Neuro Imaging