Ictal high-frequency oscillations and hyperexcitability in refractory epilepsy

Leung, Howan; Zhu, Cannon Xian Lun; Chan, Danny Tat Ming; Poon, Wai Sang; Shi, Lin; Mok, Vincent; Wong, Ka Sing

doi:10.1016/j.clinph.2015.01.009

Cited by 15 publications

(16 citation statements)

References 27 publications

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“…Our study found that FRs could occur in the normal hippocampus, although their amplitude or spectral power appeared to be stationary and significantly lower than the epileptic hippocampus. Parallel to previous studies (2, 23), dynamic changes in the spectral power of ripples and FRs were in agreement with the state of epilepsy, suggesting that the spectral power of HFOs may be utilized to distinguish between normal and pHFOs, rather than the frequency of HFOs.…”

Section: Discussionsupporting

confidence: 84%

“…Patients undergoing complete resection of FR-generating tissue generally have a good surgical outcome (23, 30–32). Higher rates of HFOs were observed in the SOZ compared to other areas, particularly during interictal periods (33).…”

Section: Discussionmentioning

confidence: 99%

“…Third, the frequency resolution (number of frequency bins) in our time–frequency transform could be theoretically increased or decreased to infinity. This is important because the exact frequency signatures of EEG signals vary among brain areas (23). …”

Section: Methodsmentioning

confidence: 99%

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Dynamic Changes in Spectral and Spatial Signatures of High Frequency Oscillations in Rat Hippocampi during Epileptogenesis in Acute and Chronic Stages

et al. 2016

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ObjectiveTo analyze spectral and spatial signatures of high frequency oscillations (HFOs), which include ripples and fast ripples (FRs, >200 Hz) by quantitatively assessing average and peak spectral power in a rat model of different stages of epileptogenesis.MethodsThe lithium–pilocarpine model of temporal lobe epilepsy was used. The acute phase of epilepsy was assessed by recording intracranial electroencephalography (EEG) activity for 1 day after status epilepticus (SE). The chronic phase of epilepsy, including spontaneous recurrent seizures (SRSs), was assessed by recording EEG activity for 28 days after SE. Average and peak spectral power of five frequency bands of EEG signals in CA1, CA3, and DG regions of the hippocampus were analyzed with wavelet and digital filter.ResultsFRs occurred in the hippocampus in the animal model. Significant dynamic changes in the spectral power of FRS were identified in CA1 and CA3. The average spectral power of ripples increased at 20 min before SE (p < 0.05), peaked at 10 min before diazepam injection. It decreased at 10 min after diazepam (p < 0.05) and returned to baseline after 1 h. The average spectral power of FRs increased at 30 min before SE (p < 0.05) and peaked at 10 min before diazepam. It decreased at 10 min after diazepam (p < 0.05) and returned to baseline at 2 h after injection. The dynamic changes were similar between average and peak spectral power of FRs. Average and peak spectral power of both ripples and FRs in the chronic phase showed a gradual downward trend compared with normal rats 14 days after SE.SignificanceThe spectral power of HFOs may be utilized to distinguish between normal and pathologic HFOs. Ictal average and peak spectral power of FRs were two parameters for predicting acute epileptic seizures, which could be used as a new quantitative biomarker and early warning marker of seizure. Changes in interictal HFOs power in the hippocampus at the chronic stage may be not related to seizure occurrence.

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Section: Discussionsupporting

confidence: 84%

Section: Discussionmentioning

confidence: 99%

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Dynamic Changes in Spectral and Spatial Signatures of High Frequency Oscillations in Rat Hippocampi during Epileptogenesis in Acute and Chronic Stages

et al. 2016

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“…Typically, the presurgical evaluation was performed using MRI, SPECT, PET, fMRI, or MEG [17]- [19]. Although developed in brain glioma cases, our SPAM-assisted presurgical mapping technique could apply to presurgical mapping for epilepsy surgery as well.…”

Section: Discussionmentioning

confidence: 99%

Presurgical Mapping of Brain Tumors Using Statistical Probabilistic Anatomical Maps

Kim¹,

Cheon²,

Lim³

2015

JBiSE

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Purpose: Multi-tracer neuroimaging is widely used for the diagnosis, radiotherapy, and neurosurgery of brain gliomas. Anatomical and functional information is important to avoid having neurological deficits induced during the resection or radiation therapy of brain gliomas. The aim of this study was to investigate presurgical anatomical labeling of brain gliomas on FLT and FET using statistical probabilistic anatomic maps (SPAM), which are images of cerebral cortical, cerebellar, and subcortical volumes of interest (VOIs). Methods: FDG, FLT, and FET PET scans were acquired. FLT and FET PET images were coregistered to the FDG PET images, which were then spatially normalized onto the target brain. An inverse spatial normalization parameter was calculated and applied to SPAM. For the anatomical labeling of brain glioma regions, the volumes of brain gliomason FLT and FET images were extracted using segmentation. Probabilistic information of the glioma region was then calculated using SPAM and the segmented glioma volumes. SPM and an in-house program were used for image processing. Results: The probability of SPAM labeling a brain glioma region could be extracted using the inverse normalized SPAM and segmented glioma regions. In a sample case, the probabilistic anatomical region of the glioma included 21% of the postcentral gyrus, 12% of the superior parietal gyrus, and 6% of the angular gyrus. Conclusion: Anatomical information about brain gliomas could be extracted using SPAM. This proposed method would be optional for presurgical mapping, to avoid an additional functional mapping study that might otherwise be necessary to avoid producing neurological deficits.

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“…The clinical importance of HFOs as markers of epileptogenicity and their application in different types of epilepsies are emphasized. From this review, it becomes evident that the utilization of HFOs in the identification of epileptogenic zone and presur-gical evaluation 4 has strong potential to improve surgical outcomes.…”

mentioning

confidence: 99%

Advances of Electrophysiological Techniques in Pediatric Epilepsy

Korostenskaja

2015

J Pediatr Epilepsy

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Ictal high-frequency oscillations and hyperexcitability in refractory epilepsy

Cited by 15 publications

References 27 publications

Dynamic Changes in Spectral and Spatial Signatures of High Frequency Oscillations in Rat Hippocampi during Epileptogenesis in Acute and Chronic Stages

Dynamic Changes in Spectral and Spatial Signatures of High Frequency Oscillations in Rat Hippocampi during Epileptogenesis in Acute and Chronic Stages

Presurgical Mapping of Brain Tumors Using Statistical Probabilistic Anatomical Maps

Advances of Electrophysiological Techniques in Pediatric Epilepsy

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