Developmental Atlas of Physiological High-frequency Oscillations Coupled with Delta Waves
Abstract number :
3.026
Submission category :
1. Basic Mechanisms / 1C. Electrophysiology/High frequency oscillations
Year :
2022
Submission ID :
2203917
Source :
www.aesnet.org
Presentation date :
12/5/2022 12:00:00 PM
Published date :
Nov 22, 2022, 05:22 AM
Authors :
Kazuki Sakakura, MD – Wayne State University; Naoto Kuroda, MD – Wayne State University; Masaki Sonoda, MD.,PhD. – Yokohama City University; Takumi Mitsuhashi, MD.,PhD. – Juntendo University; Ethan Firestone, MS – Wayne State University; Aimee Luat, MD – Wayne State University; Neena Marupudi, MD – Wayne State University; Sandeep Sood, MD – Wayne State University; Eishi Asano, MD.,PhD. – Wayne State University
Rationale: Spontaneous high-frequency oscillations (HFOs) are nested in delta waves during sleep. Modulation index - a quantitative measure of coupling strength between HFO amplitude and delta phase - is an excellent epilepsy biomarker. Investigators indicate that modulation index is also elevated in the nonepileptic occipital lobes of older children and adults. However, the developmental sequelae of this physiologic distrubition is currently unknown, and illuminating this knowledge is expected to improve age-appropriate localization of the epileptogenic zone. To address this issue, we built a dynamic atlas demonstrating the developmental changes of modulation index across nonepileptic brain regions.
Methods: We studied 114 patients with focal epilepsy (age range: 1.0 to 41.5 years) who underwent extraoperative, intracranial EEG recording and achieved ILAE class I outcomes following resective surgery. During 20-minute slow-wave sleep epochs, at least two hours apart from ictal events, we computed modulation index at 8,248 artifact-free nonepileptic electrode sites (i.e. those outside the seizure onset zone, MRI-visible lesions, and interictal spike zone). We then linearly interpolated the modulation index across cortical mesh points on the FreeSurfer standard brain template. Linear and nonlinear regression models determined the developmental slope of the modulation index at each cortical mesh point. Finally, mixed model analysis determined whether the developmental changes in modulation index remained significant when accounting for the independent effects of patient and epilepsy profiles.
Results: Both linear and nonlinear regression models revealed that modulation index in the nonepileptic occipital regions increased as a function of age, although the latter model incorporating √age had a better fit. Hence, the resulting dynamic atlas visualized the spatial pattern of modulation index changing as a function of √age. Mixed model analysis revealed that √age was independently associated with increased modulation index in the nonepileptic occipital regions.
Conclusions: In the nonepileptic occipital lobes, phase-amplitude coupling between physiologic HFOs and delta waves is strengthened during development. The dynamic atlas provides a critical reference for modulation index-based presurgical evaluation of the epileptogenic zone.
Funding: NIH grant NS64033 (to E. Asano)
Basic Mechanisms