Diffusion tractography predicts propagated high‐frequency activity during epileptic spasms

O'Hara, Nolan; Lee, Min Hee; Juhász, Csaba; Asano, Eishi; Jeong, Jeong‐Won

doi:10.1111/epi.17251

Cited by 3 publications

(1 citation statement)

References 49 publications

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“…37 Once initiated, however, seizures follow a set trajectory within the epileptogenic network that is shaped primarily by regions that have increased structural and functional connectivity to the SOZ, thus enabling propagation, and regions that are prevented from recruitment to ictal activity potentially due to feedforward inhibitory mechanisms. 45,[47][48][49] In this respect, it can be argued that it is not surprising that the local neural changes underlying NREM sleep, which have relatively low synchrony, are unable to modify the spatiotemporal trajectory of seizures. 38,39 These findings also offer insights into the complex relationship between interictal and ictal activity.…”

Section: Seizure Dynamics Are Independent Of the Vigilance Statementioning

confidence: 99%

The Differing Effects of Sleep on Ictal and Interictal Network Dynamics in Drug‐Resistant Epilepsy

Hannan,

Thomas,

Jaber

et al. 2023

Annals of Neurology

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ObjectiveSleep has important influences on focal interictal epileptiform discharges (IEDs), and the rates and spatial extent of IEDs are increased in non‐rapid eye movement (NREM) sleep. In contrast, the influence of sleep on seizures is less clear and its effects on seizure topography are poorly documented. We evaluated the influences of NREM sleep on ictal spatiotemporal dynamics and contrasted these with interictal network dynamics.MethodsWe included patients with drug‐resistant focal epilepsy who underwent continuous intracranial EEG with depth electrodes. Patients were selected if they had 1‐3 seizures from each vigilance state, wakefulness and NREM sleep, within a 48‐hour window and under the same anti‐seizure medication. A 10‐min epoch of the interictal iEEG was selected per state, and IEDs were detected automatically. Twenty‐five patients (13 females; 32.5±7.1 years) were included.ResultsThe seizure onset pattern, duration, spatiotemporal propagation and latency of ictal high‐frequency activity did not differ significantly between wakefulness and NREM sleep (all p>0.05). In contrast, IED rates and spatial distribution were increased in NREM compared to wakefulness (p<0.001, Cliff's d=0.48 and 0.49). The spatial overlap between vigilance states was higher for seizures (57.1±40.1%) than IEDs (41.7±46.2%) (p=0.001, Cliff's d=0.51).InterpretationIn contrast to its effects on IEDs, NREM sleep does not affect ictal spatiotemporal dynamics. This suggests that once the brain surpasses the seizure threshold, it will follow the underlying epileptic network irrespective of the vigilance state. These findings offer valuable insights into neural network dynamics in epilepsy and have important clinical implications for localizing seizure foci.This article is protected by copyright. All rights reserved.

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Section: Seizure Dynamics Are Independent Of the Vigilance Statementioning

confidence: 99%

The Differing Effects of Sleep on Ictal and Interictal Network Dynamics in Drug‐Resistant Epilepsy

Hannan,

Thomas,

Jaber

et al. 2023

Annals of Neurology

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Sevoflurane-induced high-frequency oscillations, effective connectivity and intraoperative classification of epileptic brain areas

Firestone

Sonoda

Sakakura

et al. 2023

Clinical Neurophysiology

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EEG Ictal Power Dynamics, Function-Structure Associations, and Epilepsy Surgical Outcomes

Gong,

Roth,

Chang

et al. 2024

Neurology

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Background and ObjectivesPostoperative seizure control in drug-resistant temporal lobe epilepsy (TLE) remains variable, and the causes for this variability are not well understood. One contributing factor could be the extensive spread of synchronized ictal activity across networks. Our study used novel quantifiable assessments from intracranial EEG (iEEG) to test this hypothesis and investigated how the spread of seizures is determined by underlying structural network topological properties. MethodsWe evaluated iEEG data from 157 seizures in 27 patients with TLE: 100 seizures from 17 patients with postoperative seizure control (Engel score I) vs 57 seizures from 10 patients with unfavorable surgical outcomes (Engel score II-IV). We introduced a quantifiable method to measure seizure power dynamics within anatomical regions, refining existing seizure imaging frameworks and minimizing reliance on subjective human decision-making. Time-frequency power representations were obtained in 6 frequency bands ranging from theta to gamma. Ictal power spectrums were normalized against a baseline clip taken at least 6 hours away from ictal events. Electrodes' time-frequency power spectrums were then mapped onto individual T1weighted MRIs and grouped based on a standard brain atlas. We compared spatiotemporal dynamics for seizures between groups with favorable and unfavorable surgical outcomes. This comparison included examining the range of activated brain regions and the spreading rate of ictal activities. We then evaluated whether regional iEEG power values were a function of fractional anisotropy (FA) from diffusion tensor imaging across regions over time. ResultsSeizures from patients with unfavorable outcomes exhibited significantly higher maximum activation sizes in various frequency bands. Notably, we provided quantifiable evidence that in seizures associated with unfavorable surgical outcomes, the spread of beta-band power across brain regions is significantly faster, detectable as early as the first second after seizure onset. There was a significant correlation between beta power during seizures and FA in the corresponding areas, particularly in the unfavorable outcome group. Our findings further suggest that integrating structural and functional features could improve the prediction of epilepsy surgical outcomes. DiscussionOur findings suggest that ictal iEEG power dynamics and the structural-functional relationship are mechanistic factors associated with surgical outcomes in TLE.

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Diffusion tractography predicts propagated high‐frequency activity during epileptic spasms

Cited by 3 publications

References 49 publications

The Differing Effects of Sleep on Ictal and Interictal Network Dynamics in Drug‐Resistant Epilepsy

The Differing Effects of Sleep on Ictal and Interictal Network Dynamics in Drug‐Resistant Epilepsy

Sevoflurane-induced high-frequency oscillations, effective connectivity and intraoperative classification of epileptic brain areas

EEG Ictal Power Dynamics, Function-Structure Associations, and Epilepsy Surgical Outcomes

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