Lateralization Value of Low Frequency Band Beamformer Magnetoencephalography Source Imaging in Temporal Lobe Epilepsy

Lin, Yicong; Zhang, Zhiguo; Zhang, Xiating; Yang, Yingxue; Huang, Zhaoyang; Zhu, Yu; Li, Liping; Hu, Ningning; Zhang, Junpeng; Wang, Yuping

doi:10.3389/fneur.2018.00829

Cited by 6 publications

(8 citation statements)

References 40 publications

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“…25 We tried to quantify lateralization by computing a lateralization index (LI) for the alpha power ratio. 16 However, LIs were very low (−0.05 < LI < 0.05) and there were no significant differences in LIs between groups. Nevertheless, several areas (eg, thalamus and temporal or frontal areas) showed a significant increase of alpha power ratio in the right hemisphere alone.…”

Section: Discussionmentioning

confidence: 83%

Magnetoencephalography reveals increased slow-to-fast alpha power ratios in patients with chronic pain

Witjes

Baillet

Roy

et al. 2021

PR9

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Section: Discussionmentioning

confidence: 83%

Magnetoencephalography reveals increased slow-to-fast alpha power ratios in patients with chronic pain

Witjes

Baillet

Roy

et al. 2021

PR9

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“…The source images were averaged within four regions using the spm_summarize function (implemented in SPM-12) with the ROI masks. LI was calculated using the well-known basic formula ( 28 , 29 ):…”

Section: Methodsmentioning

confidence: 99%

Specific Oscillatory Power Changes and Their Efficacy for Determining Laterality in Mesial Temporal Lobe Epilepsy: A Magnetoencephalographic Study

et al. 2021

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Appropriate determination of the epileptic focus and its laterality are important for the diagnosis of mesial temporal lobe epilepsy (MTLE). The aims of this study are to establish a specific oscillatory distribution and laterality of the oscillatory power in unilateral MTLE with frequency analysis of magnetoencephalography (MEG), and to confirm their potential to carry significant information for determining lateralization of the epileptic focus. Thirty-five patients with MTLE [left (LtMTLE), 16; right (RtMTLE), 19] and 102 healthy control volunteers (CTR) were enrolled. Cortical oscillatory powers were compared among the groups by contrasting the source images using a one-way ANOVA model for each frequency band. Further, to compare the lateralization of regional oscillatory powers between LtMTLEs and RtMTLEs, the laterality index (LI) was calculated for four brain regions (frontal, temporal, parietal, and occipital) in each frequency band, which were compared between patient groups (LtMTLE, RtMTLE, and CTR), and used for machine learning prediction of the groups with support vector machine (SVM) with linear kernel function. Significant oscillatory power differences between MTLE and CTR were found in certain areas. In the theta to high-frequency oscillation bands, there were marked increases in the parietal lobe, especially on the left side, in LtMTLE. In the theta, alpha, and high-gamma bands, there were marked increases in the parietal lobe, especially on the right side in RtMTLE. Compared with CTR, LIs were significantly higher in 24/28 regions in LtMTLE, but lower in 4/28 regions and higher in 10/28 regions in RtMTLE. LI at the temporal lobe in the theta band was significantly higher in LtMTLE and significantly lower in RtMTLE. Comparing LtMTLE and RtMTLE, there were significant LI differences in most regions and frequencies (21/28 regions). In all frequency bands, there were significant differences between LtMTLE and RtMTLE in the temporal and parietal lobes. The leave-one-out cross-validation of the linear-SVM showed the classification accuracy to be over 91%, where the model had high specificity over 96% and mild sensitivity ~68–75%. Using MEG frequency analysis, the characteristics of the oscillatory power distribution in the MTLE were demonstrated. Compared with CTR, LIs shifted to the side of the epileptic focus in the temporal lobe in the theta band. The machine learning approach also confirmed that LIs have significant predictive ability in the lateralization of the epileptic focus. These results provide useful additional information for determining the laterality of the focus.

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“…As hypothesized, an increased global delta power was found in FE patients compared to healthy controls. This is a common finding in epilepsy patients often indicating pathological processes (Di Gennaro et al, 2003;Ishibashi et al, 2002;Knyazev, 2012;Laufs et al, 2006;Lin et al, 2018;Pellegrino et al, 2017). Even though there are studies showing that delta power increases occur regionally and somewhat limited to the affected hemisphere (ipsilateral to epileptogenic zone; Pellegrino et al, 2017), other recent literature indicates that delta activity can also occur bilaterally and further away from the epileptogenic zone (Lundstrom et al, 2019;Sachdev et al, 2015).…”

Section: Delta Power In Patients With Focal Epilepsymentioning

confidence: 98%

“…To control for confounding variables, (1, 2) Chi-square, (3) Spearman rank, and ( 4 Lin et al, 2018). For explorative purposes, the co-fluctuation of delta power between hemisphere ipsi-and contralateral to the epileptogenic zone was additionally examined using Spearman rank correlations.…”

Section: Statistical Analysesmentioning

confidence: 99%

“…In epilepsy, increases in delta power are known to occur in many patients with temporal (TLE) and extratemporal lobe epilepsy, as regional or global, intermittent, or continuous slowing of background activity (Fisher et al, 2017;Kamada et al, 2001). Although several studies indicate a correlation with lateralization and localization of the epileptogenic zone (Di Gennaro et al, 2003;Ishibashi et al, 2002;Lin et al, 2018;Pellegrino et al, 2017;Tao et al, 2011), other recent findings indicate that delta band activity also occurs bilaterally and distantly to the epileptogenic zone (Lundstrom et al, 2019;Sachdev et al, 2015). Thus, the exact diagnostic relevance is still uncertain.…”

Section: Introductionmentioning

confidence: 99%

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Lateralization of delta band power in magnetoencephalography (MEG) in patients with unilateral focal epilepsy and its relation to verbal fluency

Süß,

Hug,

Conradi

et al. 2023

Brain and Behavior

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IntroductionDelta power is a clinically established biomarker for abnormal brain processes. However, in patients with unilateral focal epilepsy (FE) it is still not well understood, how it relates to the epileptogenic zone and to neurocognitive functioning. The aim of the present study was thus to assess how delta power relates to the affected hemisphere, whether lateralization strength differs between the patients, and how changes in delta power correlate with cognitive functioning.MethodWe retrospectively studied patients with left (LFE) and right FE (RFE) who had undergone a resting‐state magnetoencephalography measurement. We computed global and hemispheric delta power and lateralization indices and examined whether delta power correlates with semantic and letter verbal fluency (former being a marker for language and verbal memory, latter for executive functions) in 26 FE patients (15 LFE, 11 RFE) and 10 healthy controls.ResultsDelta power was increased in FE patients compared to healthy controls. However, the increase across hemispheres was related to the site of the epileptic focus: On group level, LFE patients showed higher delta power in both hemispheres, whereas RFE patients primarily exhibited higher delta power in the ipsilateral right hemisphere. Both groups showed co‐fluctuations of delta power between the hemispheres. Besides, delta power correlated negatively only with letter verbal fluency.ConclusionThe findings confirm and provide further evidence that delta power is a marker of pathological activity and abnormal brain processes in FE. Delta power dynamics differ between patient groups, indicating that delta power could offer additional diagnostic value. The negative association of delta power and letter verbal fluency suggests that executive dysfunctions are related to low frequency abnormalities.

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Lateralization Value of Low Frequency Band Beamformer Magnetoencephalography Source Imaging in Temporal Lobe Epilepsy

Cited by 6 publications

References 40 publications

Magnetoencephalography reveals increased slow-to-fast alpha power ratios in patients with chronic pain

Magnetoencephalography reveals increased slow-to-fast alpha power ratios in patients with chronic pain

Specific Oscillatory Power Changes and Their Efficacy for Determining Laterality in Mesial Temporal Lobe Epilepsy: A Magnetoencephalographic Study

Lateralization of delta band power in magnetoencephalography (MEG) in patients with unilateral focal epilepsy and its relation to verbal fluency

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