Dynamic Tractography-based Assessment of Neural Propagations Between Cortex and Thalamic Nuclei
Abstract number :
1.278
Submission category :
3. Neurophysiology / 3E. Brain Stimulation
Year :
2024
Submission ID :
763
Source :
www.aesnet.org
Presentation date :
12/7/2024 12:00:00 AM
Published date :
Authors :
Presenting Author: Naoto Kuroda, MD – Wayne State University
Kazuki Sakakura, MD, PhD – Rush University
Kanako Tsuchimoto, MD – Kagoshima University Graduate School of Medicine and Dental Sciences
Kotaro Saito, MD – Kagoshima University Graduate School of Medicine and Dental Sciences
Aya Kanno, MD, PhD – Sapporo medical university
Takumi Mitsuhashi, MD, PhD – Juntendo University, School of Medicine
Masaki Sonoda, MD, PhD – Yokohama City University
Aimee Luat, MD – Wayne State University
Nobukazu Nakasato, MD, PhD – Tohoku University Graduate School of Medicine
Eishi Asano, MD/PhD – Wayne State University
Rationale: Using dynamic tractography, we investigated the speed, topographic specificity, and diagnostic potential of stimulation-evoked neural propagations between cortex and thalamus in drug-resistant epilepsy.
Methods: We studied patients who underwent stereoencephalography (sEEG) recording involving both thalamic and cortical regions. As part of our routine presurgical evaluation to understand brain network dynamics, we applied single-pulse electrical stimulation (SPES) to adjacent pairs of sEEG electrodes (at 5.0 mA, 1 Hz, for a total of 40 stimuli) to generate thalamo-cortical and cortico-thalamic evoked potentials (Figure 1). We assessed the magnitude of these potentials using peak voltage values within 11-50 ms after SPES, which were z-scores normalized to the baseline period defined as 200-50 ms before SPES. We employed linear mixed model analysis on sEEG data from non-seizure onset sites at the cortex and thalamus and examined the relationship between the magnitude of evoked potentials and the presence of direct white matter streamlines between the cortex and thalamus on MRI tractography. Subsequently, we estimated the velocity of neural propagations, which is defined as the length of the direct white matter streamlines on MRI tractography divided by the peak latency of the evoked potential, and animated the spatiotemporal dynamics of these stimulation-induced neural propagations. We also evaluated the diagnostic potential of evoked potential magnitude to classify seizure onset zone (SOZ) sites.
Results: Four patients with drug-resistant epilepsy met the eligibility criteria. In total, 223 sEEG electrode sites were localized at the cortical level, with 54 within the SOZ. Sixteen thalamic electrode sites were also examined, distributed across anterior, centro-median, ventral lateral, and pulvinar nuclei. We found that a direct thalamo-cortical white matter streamline was associated with an increased magnitude of stimulation-evoked potentials (+5.41 z-score normalized peak voltage under the presence of direct white matter streamlines; p< 0.001). Neural propagations were typically completed within 40 milliseconds (Figure 2). A greater magnitude of thalamo-cortical evoked potentials, adjusted for the distance between stimulating and recording sites, was associated with a higher probability of being within the SOZ (area under the receiver operating characteristic curve to classify the SOZ: 0.699; 95% Confidence Interval: 0.648-0.749), while cortico-thalamic potentials did not show significant associations with the SOZ.
Conclusions: Dynamic tractography can visualize the spatiotemporal dynamics of neural communications between the cortex and thalamus. Single-pulse electrical stimulation-evoked neural propagation has the potential to serve as a biomarker for assessing the severity of epileptic networks between the cortex and thalamus in drug-resistant epilepsy.
Funding: JSPS JP22J23281 (N.K.), JSPS JP22KJ0323 (N.K.), NIH NS064033 (E.A.).
Neurophysiology