Tanoue Yuta, Uda Takehiro, Hoshi Hideyuki, Shigihara Yoshihito, Kawashima Toshiyuki, Nakajo Kosuke, Tsuyuguchi Naohiro, Goto Takeo
Department of Neurosurgery, Graduate School of Medicine, Osaka City University, Osaka, Japan.
Precision Medicine Centre, Hokuto Hospital, Obihiro City, Japan.
Front Neurol. 2021 Feb 9;12:617291. doi: 10.3389/fneur.2021.617291. eCollection 2021.
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.
准确确定癫痫病灶及其偏侧性对于内侧颞叶癫痫（MTLE）的诊断至关重要。本研究的目的是通过对脑磁图（MEG）进行频率分析，确定单侧MTLE中振荡功率的特定振荡分布及其偏侧性，并确认它们携带的用于确定癫痫病灶偏侧化的重要信息的潜力。招募了35例MTLE患者[左侧（LtMTLE），16例；右侧（RtMTLE），19例]和102名健康对照志愿者（CTR）。通过使用单向方差分析模型对每个频段的源图像进行对比，比较各组之间的皮质振荡功率。此外，为了比较LtMTLE和RtMTLE之间区域振荡功率的偏侧化，计算每个频段四个脑区（额叶、颞叶、顶叶和枕叶）的偏侧化指数（LI），并在患者组（LtMTLE、RtMTLE和CTR）之间进行比较，并用于支持向量机（SVM）线性核函数对各组进行机器学习预测。在某些区域发现MTLE和CTR之间存在显著的振荡功率差异。在θ到高频振荡频段，LtMTLE患者的顶叶，尤其是左侧，振荡功率显著增加。在θ、α和高γ频段，RtMTLE患者的顶叶，尤其是右侧，振荡功率显著增加。与CTR相比，LtMTLE患者28个区域中的24个区域的LI显著更高，但RtMTLE患者4个区域的LI更低，10个区域的LI更高。θ频段颞叶的LI在LtMTLE中显著更高，在RtMTLE中显著更低。比较LtMTLE和RtMTLE，大多数区域和频率（21/28个区域）存在显著的LI差异。在所有频段中，颞叶和顶叶的LtMTLE和RtMTLE之间存在显著差异。线性SVM的留一法交叉验证显示分类准确率超过91%，其中模型具有超过96%的高特异性和约68-75%的中等敏感性。通过MEG频率分析，证明了MTLE中振荡功率分布的特征。与CTR相比，θ频段颞叶的LI向癫痫病灶侧偏移。机器学习方法也证实了LI在癫痫病灶偏侧化方面具有显著的预测能力。这些结果为确定病灶的偏侧性提供了有用的额外信息。
