Sevoflurane-based enhancement of phase-amplitude coupling and localization of the epileptogenic zone

Objective: Phase-amplitude coupling between high-frequency (>150 Hz) and delta (3-4 Hz) oscillations - modulation index (MI) - is a promising, objective biomarker of epileptogenicity. We determined whether sevoflurane anesthesia preferentially enhances this metric within the epileptogenic zone. Methods: This is an observational study of intraoperative electrocorticography data from 621 electrodes chronically implanted into eight patients with drug-resistant, focal epilepsy. All patients were anesthetized with sevoflurane during resective surgery, which subsequently resulted in seizure control. We classified "removed" and "retained" brain sites as epileptogenic and non-epileptogenic, respectively. Mixed model analysis determined which anesthetic stage optimized MI-based classification of epileptogenic sites. Results: MI increased as a function of anesthetic stage, ranging from baseline (i.e., oxygen alone) to 2 minimum alveolar concentration (MAC) of sevoflurane, preferentially at sites showing higher initial MI values. This phenomenon was accentuated just prior to sevoflurane reaching 2 MAC, at which time, the odds of a site being classified as epileptogenic were enhanced by 86.6 times for every increase of 1 MI. Conclusions: Intraoperative MI best localized the epileptogenic zone immediately before sevoflurane reaching 2 MAC in this small cohort of patients. Significance: Prospective, large cohort studies are warranted to determine whether sevoflurane anesthesia can reduce the need for extraoperative, invasive evaluation.

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Phase–Amplitude Coupling and Epileptogenic Zone Localization of Frontal Epilepsy Based on Intracranial EEG

Frontiers in Neurology ◽

10.3389/fneur.2021.718683 ◽

2021 ◽

Vol 12 ◽

Author(s):

Huijuan Ma ◽

Zeyu Wang ◽

Chunsheng Li ◽

Jia Chen ◽

Yuping Wang

Keyword(s):

Epileptic Seizure ◽

Receiver Operating Curve ◽

Epileptic Focus ◽

Epileptogenic Zone ◽

Seizure Onset ◽

Intracranial Eeg ◽

Seizure Onset Zone ◽

Phase Amplitude ◽

Frontal Epilepsy

Objective: This study aimed to explore the characteristics of phase-amplitude coupling in patients with frontal epilepsy based on their electrocorticography data, in order to identify the localization of epileptic regions and further guide clinical resection surgery.Methods: We adopted the modulation index based on the Kullback-Leibler distance, phase-amplitude coupling co-modulogram, and time-varying phase-amplitude modulogram to explore the temporal-spatial patterns and characterization of PAC strength during the period from inter- seizure to post-seizure. Taking the resected area as the gold standard, the epileptogenic zone was located based on MI values of 7 different seizure periods, and the accuracy of localization was measured by the area under the receiver operating curve.Results: (1) The PAC in the inter- and pre-seizure periods was weak and paroxysmal, but strong PAC channels were confined more to the seizure-onset zone and resection region. PAC during the seizure period was intense and persistent, but gradually deviated from the seizure-onset zone. (2) The characteristics of coupling strength of the inter- and pre-seizure EEG can be used to accurately locate the epileptogenic zone, which is better than that in periods after the beginning of a seizure. (3) In an epileptic seizure, the preferred phases of coupling were usually in the rising branches at the pre- and early-seizure stages, while those in the middle- and terminal-seizure were usually in the falling branch. We thus speculate that the coupling occurred in the rising branch can promote the recruitment of abnormal discharge, while the coupling occurred in the falling branch can inhibit the abnormal discharge.Conclusion: The findings suggest that the phase-amplitude coupling during inter- and pre-seizure is a promising marker of epileptic focus location. The preferred phase of coupling changed regularly with the time of epileptic seizure, suggesting that the surge and suppression of abnormal discharges are related to different phases.

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Manipulation of the Phase-Amplitude Coupling Factor in Quantum Nanostructure Based Devices for On-Chip Chirp Compensation and Low-Cost Applications

10.21236/ada619855 ◽

2014 ◽

Author(s):

Frederic Grillot

Keyword(s):

Low Cost ◽

Coupling Factor ◽

Chirp Compensation ◽

On Chip ◽

Phase Amplitude

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Doubler lattice and phase - amplitude functions

10.2172/1155967 ◽

1978 ◽

Author(s):

T. Collins

Keyword(s):

Phase Amplitude

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Hamilton-Jacobi Theory

10.1093/oso/9780198822370.003.0019 ◽

2018 ◽

Author(s):

Peter Mann

Keyword(s):

Phase Space ◽

Bbgky Hierarchy ◽

Distribution Functions ◽

Symplectic Integrators ◽

Partition Functions ◽

Von Neumann ◽

Equipartition Theorem ◽

Recurrence Theorem ◽

Phase Amplitude ◽

Canonical Ensembles

This chapter focuses on Liouville’s theorem and classical statistical mechanics, deriving the classical propagator. The terms ‘phase space volume element’ and ‘Liouville operator’ are defined and an n-particle phase space probability density function is constructed to derive the Liouville equation. This is deconstructed into the BBGKY hierarchy, and radial distribution functions are used to develop n-body correlation functions. Koopman–von Neumann theory is investigated as a classical wavefunction approach. The chapter develops an operatorial mechanics based on classical Hilbert space, and discusses the de Broglie–Bohm formulation of quantum mechanics. Partition functions, ensemble averages and the virial theorem of Clausius are defined and Poincaré’s recurrence theorem, the Gibbs H-theorem and the Gibbs paradox are discussed. The chapter also discusses commuting observables, phase–amplitude decoupling, microcanonical ensembles, canonical ensembles, grand canonical ensembles, the Boltzmann factor, Mayer–Montroll cluster expansion and the equipartition theorem and investigates symplectic integrators, focusing on molecular dynamics.

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Synaptic Reshaping and Neuronal Outcomes in the Temporal Lobe Epilepsy

International Journal of Molecular Sciences ◽

10.3390/ijms22083860 ◽

2021 ◽

Vol 22 (8) ◽

pp. 3860

Author(s):

Elisa Ren ◽

Giulia Curia

Keyword(s):

Animal Models ◽

Temporal Lobe Epilepsy ◽

Temporal Lobe ◽

Current Knowledge ◽

Focal Epilepsy ◽

Ex Vivo ◽

Hippocampal Sclerosis ◽

Control Group ◽

Epileptogenic Zone ◽

Epileptiform Discharges

Temporal lobe epilepsy (TLE) is one of the most common types of focal epilepsy, characterized by recurrent spontaneous seizures originating in the temporal lobe(s), with mesial TLE (mTLE) as the worst form of TLE, often associated with hippocampal sclerosis. Abnormal epileptiform discharges are the result, among others, of altered cell-to-cell communication in both chemical and electrical transmissions. Current knowledge about the neurobiology of TLE in human patients emerges from pathological studies of biopsy specimens isolated from the epileptogenic zone or, in a few more recent investigations, from living subjects using positron emission tomography (PET). To overcome limitations related to the use of human tissue, animal models are of great help as they allow the selection of homogeneous samples still presenting a more various scenario of the epileptic syndrome, the presence of a comparable control group, and the availability of a greater amount of tissue for in vitro/ex vivo investigations. This review provides an overview of the structural and functional alterations of synaptic connections in the brain of TLE/mTLE patients and animal models.

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Efficient automated localization of ECoG electrodes in CT images via shape analysis

International Journal of Computer Assisted Radiology and Surgery ◽

10.1007/s11548-021-02325-0 ◽

2021 ◽

Vol 16 (4) ◽

pp. 543-554

Author(s):

Jessica Centracchio ◽

Antonio Sarno ◽

Daniele Esposito ◽

Emilio Andreozzi ◽

Luigi Pavone ◽

...

Keyword(s):

Shape Analysis ◽

Focal Epilepsy ◽

Support Vector ◽

Epileptogenic Zone ◽

Platinum Electrodes ◽

Public Repository ◽

Automated Method ◽

Depth Electrodes ◽

Ethical Approval ◽

Cortical Regions

Abstract Purpose People with drug-refractory epilepsy are potential candidates for surgery. In many cases, epileptogenic zone localization requires intracranial investigations, e.g., via ElectroCorticoGraphy (ECoG), which uses subdural electrodes to map eloquent areas of large cortical regions. Precise electrodes localization on cortical surface is mandatory to delineate the seizure onset zone. Simple thresholding operations performed on patients’ computed tomography (CT) volumes recognize electrodes but also other metal objects (e.g., wires, stitches), which need to be manually removed. A new automated method based on shape analysis is proposed, which provides substantially improved performances in ECoG electrodes recognition. Methods The proposed method was retrospectively tested on 24 CT volumes of subjects with drug-refractory focal epilepsy, presenting a large number (> 1700) of round platinum electrodes. After CT volume thresholding, six geometric features of voxel clusters (volume, symmetry axes lengths, circularity and cylinder similarity) were used to recognize the actual electrodes among all metal objects via a Gaussian support vector machine (G-SVM). The proposed method was further tested on seven CT volumes from a public repository. Simultaneous recognition of depth and ECoG electrodes was also investigated on three additional CT volumes, containing penetrating depth electrodes. Results The G-SVM provided a 99.74% mean classification accuracy across all 24 single-patient datasets, as well as on the combined dataset. High accuracies were obtained also on the CT volumes from public repository (98.27% across all patients, 99.68% on combined dataset). An overall accuracy of 99.34% was achieved for the recognition of depth and ECoG electrodes. Conclusions The proposed method accomplishes automated ECoG electrodes localization with unprecedented accuracy and can be easily implemented into existing software for preoperative analysis process. The preliminary yet surprisingly good results achieved for the simultaneous depth and ECoG electrodes recognition are encouraging. Ethical approval n°NCT04479410 by “IRCCS Neuromed” (Pozzilli, Italy), 30th July 2020.

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Dissociating harmonic and non-harmonic phase-amplitude coupling in the human brain

NeuroImage ◽

10.1016/j.neuroimage.2020.117648 ◽

2021 ◽

Vol 227 ◽

pp. 117648

Author(s):

Janet Giehl ◽

Nima Noury ◽

Markus Siegel

Keyword(s):

Human Brain ◽

Harmonic Phase ◽

Phase Amplitude

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The benefit of the diffusion kurtosis imaging in presurgical evaluation in patients with focal MR-negative epilepsy

Scientific Reports ◽

10.1038/s41598-021-92804-w ◽

2021 ◽

Vol 11 (1) ◽

Author(s):

Michaela Bartoňová ◽

Marek Bartoň ◽

Pavel Říha ◽

Lubomír Vojtíšek ◽

Milan Brázdil ◽

...

Keyword(s):

Refractory Epilepsy ◽

Diffusion Kurtosis Imaging ◽

Epileptogenic Zone ◽

Diffusion Weighted Mri ◽

Specific Detection ◽

Presurgical Evaluation ◽

Brain Areas ◽

Specific Restriction ◽

Diffusion Kurtosis ◽

Selection Of

AbstractThe effectivity of diffusion-weighted MRI methods in detecting the epileptogenic zone (EZ) was tested. Patients with refractory epilepsy (N=25) who subsequently underwent resective surgery were recruited. First, the extent of white matter (WM) asymmetry from mean kurtosis (MK) was calculated in order to detect the lobe with the strongest impairment. Second, a newly developed metric was used, reflecting a selection of brain areas with concurrently increased mean Diffusivity, reduced fractional Anisotropy, and reduced mean Kurtosis (iDrArK). A two-step EZ detection was performed as (1) lobe-specific detection, (2) iDrArK voxel-wise detection (with a possible lobe-specific restriction if the result of the first step was significant in a given subject). The method results were compared with the surgery resection zones. From the whole cohort (N=25), the numbers of patients with significant results were: 10 patients in lobe detection and 9 patients in EZ detection. From these subsets of patients with significant results, the impaired lobe was successfully detected with 100% accuracy; the EZ was successfully detected with 89% accuracy. The detection of the EZ using iDrArK was substantially more successful when compared with solo diffusional parameters (or their pairwise combinations). For a subgroup with significant results from step one (N=10), iDrArK without lobe restriction achieved 37.5% accuracy; lobe-restricted iDrArK achieved 100% accuracy. The study shows the plausibility of MK for detecting widespread WM changes and the benefit of combining different diffusional voxel-wise parameters.

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