发作期及发作间期痫性放电对癫痫的诊断价值

目的探讨发作期及发作间期脑电图对癫痫诊断的意义。方法对５６例癫痫患者常规脑电图（ＲＥＥＧ）与２４ｈ脑电图（ＡＥＥＧ）进行比较研究。结果①ＲＥＥＧ的阳性率为３０％，而ＡＥＥＧ的阳性率为８６％；②不同类型癫痫在发作期和发作间期大脑活动的规律和特点，ＲＥＥＧ无１例记录到癫痫发作，而ＡＥＥＧ有２７例（４８％）记录到癫痫发作全过程的大脑电活动变化。结论发作期的ＥＥＧ对确定癫痫类型有重要意义，全身性癫痫在发作的同时发作波在两侧半球同时出现，而部分性发作患者在临床发作的同时ＥＥＧ常局限在某一脑叶有单个棘波发放，此棘波处是癫痫的病灶的部位，这种局限棘波可扩散至全脑而临床出现全身阵挛发作，此类患者为部分性癫痫并非全身性癫痫。     

85例癫痫儿童发作间期动态脑电图分析

目的：探讨动态脑电图（AEEG）对发作间期儿童癫痫的诊疗价值。方法：对85例癫痫儿童于发作间期监测24hAEEG并对其相关因素进行比较分析。结果：AEEG监测异常者74例（87．1％）,其中有痫样放电者49例（57．6％）;发作越频繁,AEEG痫样放电检出率越高（P〈0．01）;睡眠期痫样放电检出率显著高于清醒期（P〈0．01）。治疗后复查组较新诊断组癫痫儿童痫样放电显著减少（P〈0．05）。结论：发作间期AEEG监测有助于儿童癫痫的临床诊断及疗效评估     

癫痫性痉挛发作的头皮及颅内脑电图特点

目的：研究难治性癫痫性痉挛发作患者的头皮及颅内脑电图（EEG）特点,探讨与痉挛发作相关的EEG变化及其与发作间期放电、神经影像学之间的关系。方法：回顾性分析经外科手术治疗的11例患者的临床资料,分析头皮同步视频脑电图（V-EEG）。此11例患者均行术中皮层EEG监测30～60min,其中4例术前行颅内电极长程EEG监测。结果：8例患者表现为双侧基本对称的痉挛发作,发作期头皮EEG为全导高波幅慢波、尖波伴低波幅快波活动或广泛低波幅快波活动发放;另3例患者表现为一侧肢体的痉挛发作,EEG为局灶性棘慢波发放。术中皮层监测5例患者为反复的、暴发出现的多棘波活动,2例患者见持续性的棘波、尖波活动,4例未见明显的癫痫样电活动。4例行颅内电极监测者发作期EEG表现,2例为“前导性”的高波幅棘波伴随20Hz左右的低波幅快波发放;另2例为局灶性低波幅快波活动并迅速扩散,无“前导性棘波”。手术切除“前导性棘波”或反复性、节律性痫样放电的皮层可消除发作。结论：在一部分癫痫性痉挛发作患者,其痉挛发作可能因新皮层局灶的电发放点燃,颅内EEG如果存在前导性的棘波,这个棘波部位可能是促发痉挛发作的点燃灶。完整切除术中监测呈现反复性、节律性痫样放电的皮层可取得较好的手术效果。     

长程视频脑电图监测癫痫发作及在致痫灶定位中的意义

目的：探讨癫痫发作间期和发作期脑电图（EEG）变化特点与发作症状在致痫灶定位中的作用。方法：对80例癫痫患者进行视频脑电图（VEEG）监测,分析其发作间期、发作期EEG特点及临床发作表现作致痫灶定位。结果：80例癫痫患者中,发作间期38例和发作期60例EEG及59例临床发作症状可提供明确的致痫灶定位信息。结论：在致痫灶定位中,发作期与发作间期EEG相比,可提供较高比例的定位信息;综合分析发作问期、发作期EEG和临床发作症状,可以获得大部分癫痫患者致痫灶的定位信息,为放置颅内电极作准确致痫灶定位的重要参考。     

发作间期癫痫患者脑电非线性分析

目的：通过比较癫痫发作间期不同发作类型患者与正常对照组之间脑电非线性特点,探讨非线性脑电图在发作间期癫痫患者脑功能评价中的意义及应用价值。方法：对发作间期36例癫痫发作患者（其中2i例强直阵挛发作患者和15例复杂部分性发作）和32例健康对照组分别行安静闭眼、闭眼心算、安静睁眼3种脑功能活动状态下的脑电图检查,经专门软件采样处理得出相应的关联维数、近似熵并加以分析。结果：强直阵挛发作组不同脑功能活动状态下关联维数、近似熵与健康对照组相比在安静闭眼、闭眼心算、安静睁眼状态下均无明显差异,复杂部分性发作组与健康对照组相比在安静闭眼状态下于额、顶、颞叶相关导联的关联维数、近似熵下降,闭眼心算状态下近似熵在顶叶、颞叶导联下降。结论：脑电图之关联维数、近似熵有助于评价不同癫痫发作类型患者发作间期的脑功能状态。     

儿童癫痫发作间期SPECT高灌注灶与EEG致痫区之间的关系

目的：观察早期儿童癫痫病例单光子发射计算机层体摄影（SPECT）高灌注灶与脑电图（EEG）致痫灶之间的相关性。方法：对30例儿童癫痫SPECT高灌注显像病例进行同步录像脑电图（V-EEG）进行12h长程监测,分析这两种方法结果的相关性。结果：发作间期SPECT显像高灌注灶者29例（97％）,高低灌注灶者1例（3％）;单灶者13例（43％）13个灶,多灶者17例（57％）41个灶,共54个灶。EEG30例均异常,有痫样放电者29例（97％）,其中局限性异常18例（60％）,广泛性异常11例（37％）,另有慢波异常者1例。SPECT高灌注灶与EEG的致痢灶相符者7例（23％）,相近者7例（23％）,不相符者16例（54％）。结论：早期儿童癫痫病例SPECT的高灌注灶与EEG的致痫灶的相关性较低。     

癫痫发作脑电信号的相位幅度调制研究

脑电图是癫痫诊治中一种最为重要的工具,而大数据量的脑电记录给人工分析带来困难,计算机分类则可减轻此负担。从相位幅度调制角度研究癫痫脑电低频节律相位与高频节律幅度间的耦合关系,利用归一化后的调制指数(MI)来量化各频段间的耦合强度。基于波恩癫痫发作间期和发作期脑电的200个样本数据集,提出依据高低频节律范围对MI图进行分区,再利用分区后的耦合系数对不同状态下的脑电进行分类。结果显示,发作期Gamma节律与Delta(2～4 Hz)节律的MI值(0.009 9±0.009 6)相比发作间期(0.003 6±0.008 7)显著增加(P<0.01)。Gamma节律与Theta(4～8 Hz)节律的发作期MI值(0.008 7±0.006 2)相比发作间期(0.001 4±0.003 2)也有显著增加(P<0.01);Theta Beta节律间耦合强度在发作期(0.002 2±0.001 3)与发作间期(0.000 5±0.000 7)也存在显著差异。利用支持向量机在五折交叉验证下,波恩癫痫脑电数据MI特征对发作期和间期数据分类准确率达到97%;采用随机森林分类方法,同样得到一致结果。所提出方法的应用可有效提高对临床视频脑电图分析的效率。     

基于PCA多导联的癫痫脑电信号分类及致痫灶定位研究

为了更好的对致痫灶进行准确定位,提出了一种基于PCA(主成分分析)的定位方法.针对非线性动力学方法从不同角度提取癫痫脑电信号特征,首先采用主成分分析对高维特征向量进行降维处理,用随机森林进行分类;随后利用医学参考值范围找出各导联的差异变化,进而实现对致痫灶的初步定位.     

基于Granger因果分析的癫痫发作间歇期EEG在δ频段的功能连接模式

目的 应用频域Granger因果分析方法,研究颞叶癫痫发作间歇期16导脑电图(EEG)在与癫痫发作相关的δ频段的过度放电功能连接特性.方法 实验数据来自颞叶癫痫9例患者(6例左颞叶癫痫,3例右颞叶癫痫),9例正常对照受试者.记录每例颞叶癫痫受试者在发作间歇期的痫样放电、非痫样放电以及正常对照组的共3个状态的16导EEG;每个状态下各记录10个EEG数据段,每个数据段长度为20s,采样频率为200 Hz;应用带通滤波提取EEG的δ分量(1～4 Hz).应用频域Granger因果分析方法,分别计算痫样放电组、非痫样放电组和正常组10次记录的16通道EEGδ频段分量之间的频域因果度量平均值Iδ;分析以上3个组颞叶区(左颞叶癫痫:T3、T5,右颞叶癫痫:T4、T6)与额区(Fp1、Fp2、F3、F4)和顶区(C3、C4)之间EEG在δ频段的功能连接模式.结果 痫样放电组:下颞叶区(左下颞叶区T5,右下颞叶区T6)与额区、顶区之间Iδ在0.1323±0.0329～0.1670±0.0289;非痫样放电组:下颞叶区与额区、顶区之间的Iδ在0.0300±0.0130～0.0420±0.0072;正常对照组:下颞叶区与额区、顶区之间的Iδ在0.0153±0.0028～0.0193±0.0057.统计结果表明:痫样放电组下颞叶区与额区、顶区之间的Iδ值与非痫样放电组相比差异有统计学意义(P＜0.05),与正常对照组相比差异有统计学意义(P＜0.01);非痫样放电组下颞叶区与额叶、顶叶之间的Iδ值和正常对照组相比差异无统计学意义(P＞0.05).结论 颞叶癫痫发作间歇期在痫样放电状态下,EEGδ频段在下颞叶区与额区、顶区之间存在较强连接,过度放电从下颞叶区传递到额区和顶区.非痫样放电组和正常组的EEGδ频段,下颞叶区与额叶、顶叶之间连接弱,下颞叶区不是EEG信号传导的起始区.     

青少年肌阵挛癫痫发作间期EEG-fMRI的研究

采用同步脑电与功能磁共振(Simultaneous electroencephalography-correlated functional magnetic resonance imaging,EEG-fMRI)技术,研究青少年肌阵挛癫痫患者发作间期痫样放电时脑部血氧水平依赖(Blood oxygen level-dependent,BOLD)信号变化。结果发现:双侧大脑半球的激活及失活信号变化普遍对称且各自独立存在,信号由枕顶至额区逐渐减少。阳性激活区有:楔叶、岛叶、额中部内侧、小脑中线两侧及丘脑。阴性激活区有:双侧额前部、顶部及扣带后回。由此推断:以棘慢复合波为表现形式的同步的神经元活动可能反映了丘脑皮层BOLD信号的激活,而失活区域反映了异常放电时的脑功能的静息状态;这类激活在神经元的活动(EEG)与fMRI结果之间有很好的对应关系;EEG-fMRI是研究脑功能状态有效的方式。     

Correlation Dimension Maps of EEG from Epileptic Absences

The understanding of brain activity, and in particular events such as epileptic seizures, lies on the characterisation of the dynamics of the neural networks. The theory of non-linear dynamics provides signal analysis techniques which may give new information on the behaviour of such networks. Methods: We calculated correlation dimension maps for 19-channel EEG data from 3 patients with a total of 7 absence seizures. The signals were analysed before, during and after the seizures. Phase randomised surrogate data was used to test chaos. Results: In the seizures of two patients we could distinguish two dynamical regions on the cerebral cortex, one that seemed to exhibit chaos whereas the other seemed to exhibit noise. The pattern shown is essentially the same for seizures triggered by hyperventilation, but differ for seizures triggered by light flashes. The chaotic dynamics that one seems to observe is determined by a small number of variables and has low complexity. On the other hand, in the seizures of another patient no chaotic region was found. Before and during the seizures no chaos was found either, in all cases. Conclusions: The application of non-linear signal analysis revealed the existence of differences in the spatial dynamics associated to absence seizures. This may contribute to the understanding of those seizures and be of assistance in clinical diagnosis.     

3-D Source Localization of Epileptic Foci Integrating EEG and MRI Data

This study evaluates the utility of 3-D localization of interictal spike activity on the electroencephalographs (EEG) superimposed on magnetic resonance imagery (MRI) in a pediatric population with extra-temporal lesional epileptic foci. 3-D software programming based on the CURRY platform (a multimodal neuro-imaging software) was adapted for analyzing scalp EEG data and reconstructing superimposed images in 10 children who underwent extensive pre-surgical evaluation for intractable partial seizures. The results of 3-D spike source localization were assessed in relationship to focal lesions evident on the patient's MRI scans. Calculated spike sources were closest to the lesions during intervals corresponding to the spike peaks. The information was useful in surgical planning in six children that underwent successful resections.     

Estimation of obscure ictal epileptic activity in scalp EEG

Summary We have produced a method to estimate ictal localized epileptic activity hidden among the background in scalp EEGs. When the visually completely different waveforms of the epileptic and background activities are nearly orthogonal, epileptic activity may be approximately extracted from the EEG data matrix by singular value decomposition with subsequent orthogonal rotation to match the distribution of one component with that of the epileptic source. A simulation study was carried out using a matrix mimicking the scalp EEG with an inconspicuous ictal epileptic activity from a dipole source. This hidden epileptic activity was approximately recovered by matching the dipole of interest with the epileptic dipole, even when the simulated waveforms of the epileptic and background activities were not exactly orthogonal. High linear correlation between these two types of waveforms hampered the recovery of the epileptic activity. In another simulation study employing two epileptic dipoles producing activities with the same waveform and a brief time lag, it was indicated that the temporal relationship between the epileptic activities could be also estimated using the cross-correlation function. In the preliminary clinical application of this method to the ictal EEGs of complex partial seizures, rhythmic activities with seemingly epileptic waveforms were estimated at the dipoles which were located in the vicinity of cortical lesions revealed by neuroimaging studies. These activities were indicated to appear before any change in the scalp EEG. We hope for the clinical application of this method for noninvasive estimation of inconspicuous ictal epileptic activity.The authors thank Prof. Peter K.H. Wong of the Department of Paediatrics, University of British Columbia, Canada, and Prof. Yutaka Tanaka and Mr. Kim Hyun Bin of the Department of Environmental and Mathematical Sciences, Faculty of Environmental Science and Technology, Okayama University, Japan, for their technical suggestions. This study was aided by a grant from the Japan Epilepsy Research Foundation.     

匹罗卡品诱导的癎样放电大鼠EEG节律的同步分析

目的：了解癎样放电不同阶段脑电信号各节律的同步关系及其在不同脑功能状态间转换时的变化。方法：用似然同步方法分析由匹罗卡品（pilocarpine）诱导的癎样放电大鼠的大脑皮层和海马的不同节律脑电信号。结果：在同一种脑功能状态下,左右皮层和左右海马脑电信号各节律的同步性之间存在显著差异。其中无癎样放电时,δ节律的同步性显著高于α,σ,β节律的同步性（P〈0．01）;连续性癎样放电时,δ节律的同步性显著低于θ,α节律的同步性（P〈0．05）。当脑功能状态从无癎样放电向连续性癎样放电转换时,不同脑区间脑电信号各节律的同步性显著增强（P〈0．01）;从连续性癎样放电向周期性癎样放电转换时,不同脑区间脑电信号除δ节律外,其余各节律的同步性显著降低（P〈0．05）。结论：大鼠在癎样放电前δ节律可能已先于其它节律产生了类似于癎样放电的同步现象;但在癎样放电过程中则是较高节律的同步化活动占优势;而在癎样放电终止过程中,δ节律始终维持在较高的同步状态,因而推测δ节律在痴样放电过程中可能起着重要的作用。     

Localization of the Epileptic Focus by Low-Resolution Electromagnetic Tomography in Patients with a Lesion Demonstrated by MRI

Patients with medically intractable partial epilepsy and well-defined symptomatic MRI lesions were studied using phase-encoded frequency spectral analysis (PEFSA) combined with low-resolution electromagnetic tomography (LORETA). Ten patients admitted to the epilepsy monitoring unit with MRI-identified lesions and intractable partial epilepsy were studied using 31-electrode scalp EEG. The scalp electrodes were located in three-dimensional space using a magnetic digitizer and coregistered with the patient's MRI. PEFSA was used to obtain a phase-encoded scalp map for the ictal frequencies. The ictal generators were obtained from the scalp map using LORETA. In addition, the generators of interictal epileptogenic spikes were identified using time-domain LORETA. The LORETA generators were rostral to the MRI lesion in 87% (7/8) of patients with temporal lobe lesions, but all were located in the mesial temporal lobe in concordance with the patients' MRI lesions. In patients with frontal lobe epilepsy, the ictal generators at the time that the spectral power was maximal localized to the MRI lesions. Eight of 10 patients had interictal spikes, of which 4 were bilateral independent temporal lobe spikes. Only generators of the interictal spikes that were ipsilateral to seizure onset correlated with the ictal generators. LORETA combined with PEFSA of the ictal discharge can localize ictal EEG discharges accurately and improve correlation with brain anatomy by allowing coregistration of the ictal generator with the MRI. Analysis of interictal spikes was less useful than analysis of the ictal discharge.     

Tracking and detection of epileptiform activity in multichannel ictal EEG using signal subspace correlation of seizure source scalp topographies

Conventional methods for monitoring clinical (epileptiform) multichannel electroencephalogram (EEG) signals often involve morphological, spectral or time-frequency analysis on individual channels to determine waveform features for detecting and classifying ictal events (seizures) and inter-ictal spikes. Blind source separation (BSS) methods, such as independent component analysis (ICA), are increasingly being used in biomedical signal processing and EEG analysis for extracting a set of underlying source waveforms and sensor projections from multivariate time-series data, some of which reflect clinically relevant neurophysiological (epileptiform) activity. The work presents an alternative spatial approach to source tracking and detection in multichannel EEG that exploits prior knowledge of the spatial topographies of the sensor projections associated with the target sources. The target source sensor projections are obtained by ICA decomposition of data segments containing representative examples of target source activity, e.g. a seizure or ocular artifact. Source tracking and detection are then based on the subspace correlation between individual target sensor projections and the signal subspace over a moving window. Different window lengths and subspace correlation threshold criteria reflect transient or sustained target source activity. To study the behaviour and potential application of this spatial source tracking and detection approach, the method was used to detect (transient) ocular artifacts and (sustained) seizure activity in two segments of 25-channel EEG data recorded from one epilepsy patient on two separate occasions, with promising and intuitive results.     

Tracking and detection of epileptiform activity in multichannel ictal EEG using signal subspace correlation of seizure source scalp topographies

Conventional methods for monitoring clinical (epileptiform) multichannel electroencephalogram (EEG) signals often involve morphological, spectral or time-frequency analysis on individual channels to determine waveform features for detecting and classifying ictal events (seizures) and inter-ictal spikes. Blind source separation (BSS) methods, such as independent component analysis (ICA), are increasingly being used in biomedical signal processing and EEG analysis for extracting a set of underlying source waveforms and sensor projections from multivariate time-series data, some of which reflect clinically relevant neurophysiological (epileptiform) activity. The work presents an alternative spatial approach to source tracking and detection in multichannel EEG that exploits prior knowledge of the spatial topographies of the sensor projections associated with the target sources. The target source sensor projections are obtained by ICA decomposition of data segments containing representative examples of target source activity, e.g. a seizure or ocular artifact. Source tracking and detection are then based on the subspace correlation between individual target sensor projections and the signal subspace over a moving window. Different window lengths and subspace correlation threshold criteria reflect transient or sustained target source activity. To study the behaviour and potential application of this spatial source tracking and detection approach, the method was used to detect (transient) ocular artifacts and (sustained) seizure activity in two segments of 25-channel EEG data recorded from one epilepsy patient on two separate occasions, with promising and intuitive results.     

Investigation of bilateral synchronous spike-wave discharge by EEG topography

Summary To investigate the generator mechanism of the generalized discharge in childhood epilepsy, we studied its voltage field distribution using linked ear reference (L+R), common averaged reference (CA), and source derivation methods (SD). Two cases of epilepsy with clinical lapse of consciousness, and diffuse EEG spike-wave burst were divided into primary bilateral synchrony (PBS) and secondary bilateral synchrony (SBS), using coherence-phase analysis. Spike topograph images were shown by three different references. The difference in spike voltage between CA and SD was also investigated (CA-SD). By all three different references, PBS spike topography showed a broad symmetrical voltage gradient. In SBS, a left frontal focal negativity was shown with a steep voltage gradient in the topographic images of spikes by L+R, CA and SD. This asymmetry disappeared gradually at the end of the spike-wave burst. Both patients showed almost identical broad symmetrical voltage gradients on CA-SD topogram. EEG topography using various references suggested that the potential fields produced by deep generators were identical for PBS and SBS, although those generated by surface generators were different. These findings support the hypothesis that SBS may be projected from the subcortical system, and activated by cortical firing.