Epilepsy identification based on EEG signal using RQA method

PurposeEpilepsy is one of the most common neurological diseases and its cause is not unequivocal. Thus, additional methods and searches that may help to diagnose the disease are used in the clinical practice. In this study, we tested the possibility of using the Recurrence Quantification Analysis (RQA) method to identify epilepsy and present the analysis of EEG signals of healthy patients and epileptic patients by the RQA method.Materials/methodsThe recordings of signals belong to 13 patients, which were divided into 2 groups: Group A (5 epileptic patients) and Group B (8 healthy patients). In this study Fp1, Fp2, T3 and T4 electrodes were considered in the analysis using the RQA method.ResultsIt is difficult to explore the dynamics of signals by linear methods. In this study, another way of analyzing the dynamics of signals by the RQA method is presented. The RQA method revealed differences in the dynamics between the epileptic and normal signals, which seemed important in an organoleptic way. It was found that the dynamics of epileptic signals is more periodic than normal signals. To confirm the correctness of the statements issued for the RQA data the Principal Component Analysis mapping was applied. This method showed more clearly the differences in the dynamics of both signals.ConclusionsThe RQA method can be used to identify nonlinear biomedical signals such as EEG signals.     

脑电近似熵分析对帕金森病患者认知功能障碍的评估作用

目的：观察帕金森病（PD）患者与对照者的脑电近似熵的差异,并探讨其对PD认知功能障碍的评估作用。方法：对31例PD患者和31例对照组进行简易精神状态检查量表（MMsE）测试、蒙特利尔认知评估量表（MoCA）测试、事件相关电位（ERP）检测P300波潜伏期（P3PL）,采集安静闭眼、闭眼心算、安静睁眼三种状态下的脑电信号,利用非线性参数近似熵对脑电数据进行分析。结果：①与对照组相比,PD组MMSE评分和MoCA评分均降低,P3PL延长,差异有统计学意义;②与对照组相比,在安静闭眼、闭眼心算、安静睁眼三种状态下,PD组的近似熵在大部分脑区降低,差异有统计学意义这些脑区在安静闭眼状态时是Fp1、Fp2、F4、O2、F8、T3、T4、T5、T6,在闭眼心算状态时是Fp1、F3、F4、C3、P3、O1、T3、T5、T6,在安静睁眼状态时除C4外的15个脑区;③与对照组相比,PD患者近似熵变化值于F3、C3、P3、O1降低,差异有统计学意义;④所有受试者安静闭眼、闭眼心算、安静睁眼三种状态下大部分脑区近似熵值与MMSE评分、MoCA评分呈正相关,与P3PL呈负相关。结论：脑电近似熵可以作为一项客观评定PD患者认知功能障碍的电生理指标。     

缺血性脑卒中后癫癎发作的脑电图动态观察

目的：观察缺血性脑卒中后癫痫发作病人脑电图（EEG）的动态改变。方法：对40例缺血性脑卒中后癫痫发作病人（观察组）和20例缺血性脑卒中后无癫痫发作病人（病例对照组）的EEG和卒中病灶分布、范围、美国国立卫生研究院卒中量表（NIHSS）评分、癫痫发作形式及频数进行分析比较。结果：观察组40例的病灶分布主要在颞叶、额叶及顶叶,初次NIHSS评分为4．8（±2．03）分,癫痫发作类型主要为全面性强直阵挛发作;病例对照组20例的病灶分布在顶、枕、额、颞叶、基底节和小脑,初次NIHSS评分为4．7（±2．27）分,经t检验统计表明,NIHSS评分两者差异无显著意义（P〉0．50）;初次检查病例对照组的EEG异常率为50％,其中轻度异常占异常总数的70％,中度占30％;观察组的EEG异常率为95％,其中轻度异常仅占异常总数的21％,中度和重度异常占79％;健康对照组的EEG异常率很低,仅为20％,且仅表现为轻度异常;经Х^2检验,Х^2=46．54,P〈0．005,表明三组间EEG的异常率差异有显著意义。在随后的3次复查中,随着NIHSS评分的改善,癫痫发作的频数降低,EEG的异常程度也下降,以第60天时最为显著。结论：缺血性脑卒中后癫痫发作病人的EEG检查有较高的异常率,对指导其临床治疗和判断预后具有一定的价值。     

Factor analysis of climacteric symptoms in Japan

OBJECTIVES: To identify menopausal and climacteric symptoms among midlife Japanese women by factor analysis of symptom frequency and severity data. METHODS: Demographic information, anthropometric data, 2-week recalls of 82 symptoms, and assessment of epidemiological menopausal and self-defined konenki (climacteric) status were collected from 140 Japanese women living in Kyoto and Fukushima prefectures. Factor analysis was performed using symptom frequency scores and frequency-severity scores. To identify the symptoms constituting menopausal and climacteric syndromes in Japan, regression scores for individual factors were compared by menopausal and konenki status groups using non-parametric tests. RESULTS: Among 140 women aged 49.5+/-3.0 years (mean+/-S.D.), the three most prevalent symptoms were shoulder stiffness, memory loss, and stress. Analysis of frequency data resulted in an eight-factor solution, and frequency-severity data in a seven-factor solution. Anxiety and depression factors and a sexual-vasomotor factor were observed in almost all factor solutions, with additional factors comprised of psychosomatic and somatic symptoms. Anxiety scores differed by menopausal status, depression scores by konenki status, and sexual-vasomotor scores by both. Chilliness was highly correlated with sexual-vasomotor symptoms and frequency scores differed significantly between menopausal but not konenki groups. CONCLUSIONS: Sexual-vasomotor symptoms constitute a robust menopausal and konenki symptom grouping among Japanese women, but do not include night sweats or the foreign word hotto furasshu, yet do include chilliness, which may reflect thermoregulatory instability. Overlap of factors displaying significant differences between menopausal and konenki groups indicate a transition to a more medicalized concept of konenki in use by Japanese women.     

癫痫发作类型与EEG的相关性

目的：分析各种发作类型癫痫及其与脑电图（EEG）表现的关系。方法：对352例确诊癫痫患者行规范的病史询问及长程EEG监测（描记时间10～15h）,并按照1981年ILAE分类和名词委员会推荐的癫痫发作的分类方案进行发作症状的分类,按照1989年II,AE推荐的癫痫和癫痫综合征的分类作出诊断,分析其发作类型和EEG之间的相关性。结果：在352例中,EEG异常246例,异常率为69．9％,24例（6．8％）记录到临床发作。EEG异常率与发作频率相关,每月发作大于4次者较每月发作少于4次者EEG异常率显著升高（P=0．014）。部分性发作和全面性发作的患者异常率比较差异无显著意义（P=0．929）,但前者更多表现为EEG局限性异常（P=0．014）。结论：规范的长程EEG检查异常率较高,EEG异常率与发作频率相关,不同癫痫发作类型患者的EEG表现有差异。     

自回归模型和隐马尔可夫模型在癫痫脑电识别中的应用

目的研究自回归(autoregressive model,AR)模型和隐马尔可夫模型(hidden Markov model,HMM)在癫痫脑电(electroencephalogram,EEG)识别中的应用,以期减轻医生工作量,减少人工识别主观因素的影响。方法使用基于联合信息准则(combined information criterion,CIC)的最佳阶数AR模型对脑电信号进行特征提取,连续密度隐马尔可夫模型(continuous density hidden Markov model,CD-HMM)作为正常脑电和癫痫脑电的分类工具,对南京军区总医院的临床脑电数据(8组采样频率为512 Hz的16导正常、癫痫脑电信号)进行分析和识别。实验时对每一例样本选取T3、T4、FP1、FP2、C3、C4六个导联的数据。使用训练集中的15段样本进行HMM建模,剩下35段用作测试。结果癫痫脑电的识别率可达90%。结论 AR模型结合HMM建模的方法对正常脑电信号和癫痫脑电的识别率较高,在脑-机接口设备的开发中有一定的应用前景。     

一种基于自适应的脑电滤波技术

本文提出了一种基于自适应的脑电滤波技术,即用ＬＭＳ自适应预测滤波器来分离脑电中的平稳和不平稳成分,提取非平稳成分来压缩脑电处理数据量。为进一步设计脑电图的计算机自动分析和诊断系统,打下基础。     

基于相位斜率指数的脑电信号方向研究

目的将相位斜率指数(phase-slope index,PSI)算法应用在健康及癫痫患者的脑电数据上,分析导联间信息流的方向和强度,拟为临床医学研究癫痫提供借鉴方法。方法首先在相位斜率指数理论方法的基础上研究了不同脑区间的信息流向的因果关系,并取合适的阈值2作为有效结果;然后对来自军区总医院采集的健康人和癫痫患者的最新脑电数据进行分析,用t检验方法考量健康数据和癫痫数据所得到的有效结果百分比是否具有显著性差异。结果左右区没有明确的方向,前后区在alpha频段有清晰的从前到后的方向;在宽带方法(所有频率)下,健康人数据所得到的有效结果百分比与癫痫患者数据所得到的有效结果百分比的差异无统计意义;在窄带方法(alpha频段)下,健康人数据所得到的有效结果百分比要高于癫痫患者数据所得到的有效结果百分比。结论基于相位斜率指数的脑电信号研究方法得出两种信号的有效结果百分比的差异有统计意义,对临床医学分析癫痫数据具有借鉴意义。     

抗癫痫药物或非药物治疗反射性癫痫伴异常脑电图的临床观察

目的i比较抗癫痫药物或非药物治疗反射性癫痫的临床疗效和脑电图改变。方法i将27例患者分为3组：第1组为反射性癫痫伴脑电图异常（痫样放电1～4次／24h）,未用抗癫痫药者;第2组：反射性癫痫伴脑电图异常（痫样放电1～4次／24h）,使用抗癫痫药者;第3组为反射性癫痫伴脑电图异常（痫样放电≥5次／24h）,使用抗癫痫药者。各组均需避开诱因。根据患者既往最长癫痫发作间期的3倍时间随访其癫痫发作次数和视频脑电图表现。结果：各组无1例临床加重患者,临床总有效率为63％～100％,各组之间比较差异无统计学意义。脑电图改善总有效率3个组之间有明显差异（P〈0．05）。脑电图异常（痫样放电1～4次／24h）病人用药与否脑电图改善总有效率比较差异有显著意义（P〈0．01）。结论：各组反射性癫痫预后良好,伴脑电图异常的反射性癫痫建议给予抗癫痫药治疗。     

Prediction of epileptic seizures from two-channel EEG

Multivariate spectral estimation based on parametric modelling has been applied to epileptic surface EEG in order to detect EEG changes that occur prior to the clinical outbreak of the seizure. A better time/frequency resolution has been achieved using residual energy ratios (Dickinson’s method). Prediction of oncoming seizures was based on detection of increased preictal synchronisation by calculation of coherence and pole trajectories. The method has been tested on simulated EEG data and on real EEG data from patients with primary generalised epilepsy. Prediction times of 1–6 s have been found in several seizures from five patients.     

应用因果分析方法对癫痫发作间期头皮脑电信号进行致痫灶定侧

目的利用因果分析方法对癫痫发作间期的头皮脑电信号进行致痫灶定侧。方法在频域因果分析方法——自适应直接传递函数（ADTF）的基础上提出功率谱加权ADTF（psADTF）法,以给定频段内信号的功率谱对ADTF的标准化做加权,以适应不同癫痫波频域信息不同的特点。利用该方法对2组共30例患者的头皮脑电信号进行分析,含组1癫痫手术患者15例,组2门诊癫痫患者15例。其中组1患者共截取癫痫波样本数104个,组2患者共截取癫痫波样本数98个。结果组1患者通过psADTF分析对致痫灶定侧与手术侧一致的有96个,平均单个癫痫波致痫灶定侧准确率可达92％;组2患者通过psADTF分析对致痫灶定侧与专家判读结果一致的有94个,平均单个癫痫波致痫灶定侧准确率达96％。结论发作间期头皮脑电癫痫波信号的psADTF分析能够很好地辅助临床致痫灶定侧。     

Detection of Signs of Brain Dysfunction in Epileptic Children by Recognition of Transient Changes in the Correlation of Seizure-Free EEG

Seizure-free EEG signals recorded from epileptic children were compared with EEG signals recorded from normal children. The comparison was based on the detection of transient events characterized by decrease in the correlation between different traces. For this purpose, a conceptually and mathematically simple method was applied. Two clear and remarkable phenomena, able to quantitatively discriminate between the two groups of subjects, were evidenced, with high statistical significance. In fact, it was observed that: (a) The number of events for the epileptic group was larger; (b) Applying restrictive criteria for event definition, the number of subjects in the epileptic group presenting events was larger. The results support the hypothesis of a decrease in brain correlation in children with epilepsy under treatment. This confirms the efficacy of the EEG signal in evaluating cortical functional differences not visible by visual inspection, independently of the cause (epilepsy or drugs), and demonstrate the specific effectiveness of the analysis method applied.     

Decreased global field synchronization of multichannel frontal EEG measurements in obsessive-compulsive disorders

Global field synchronization (GFS) quantifies the synchronization level of brain oscillations. The GFS method has been introduced to measure functional synchronization of EEG data in the frequency domain. GFS also detects phase interactions between EEG signals acquired from all of the electrodes. If a considerable amount of local brain neurons has the same phase, these neurons appear to interact with each other. EEG data were received from 17 obsessive-compulsive disorder (OCD) patients and 17 healthy controls (HC). OCD effects on local and large-scale brain circuits were studied. Analysis of the GFS results showed significantly decreased values in the delta and full frequency bands. This research suggests that OCD causes synchronization disconnection in both the frontal and large-scale regions. This may be related to motivational, emotional and cognitive dysfunctions.     

Mobile phone emission increases inter-hemispheric functional coupling of electroencephalographic alpha rhythms in epileptic patients

It has been reported that GSM electromagnetic fields (GSM-EMFs) of mobile phones modulate - after a prolonged exposure - inter-hemispheric synchronization of temporal and frontal resting electroencephalographic (EEG) rhythms in normal young and elderly subjects (Vecchio et al., 2007, 2010). Here we tested the hypothesis that this can be even more evident in epileptic patients, who typically suffer from abnormal mechanisms governing synchronization of rhythmic firing of cortical neurons. Eyes-closed resting EEG data were recorded in ten patients affected by focal epilepsy in real and sham exposure conditions. These data were compared with those obtained from 15 age-matched normal subjects of the previous reference studies. The GSM device was turned on (45 min) in the "GSM" condition and was turned off (45 min) in the other condition ("sham"). The mobile phone was always positioned on the left side in both patients and control subjects. Spectral coherence evaluated the inter-hemispheric synchronization of EEG rhythms at the following frequency bands: delta (about 2-4 Hz), theta (about 4-6 Hz), alpha1 (about 6-8 Hz), alpha2 (about 8-10 Hz), and alpha3 (about 10-12 Hz). The effects on the patients were investigated comparing the inter-hemispheric EEG coherence in the epileptic patients with the control group of subjects evaluated in the previous reference studies. Compared with the control subjects, epileptic patients showed a statistically significant higher inter-hemispheric coherence of temporal and frontal alpha rhythms (about 8-12 Hz) in the GSM than "Sham" condition. These results suggest that GSM-EMFs of mobile phone may affect inter-hemispheric synchronization of the dominant (alpha) EEG rhythms in epileptic patients. If confirmed by future studies on a larger group of epilepsy patients, the modulation of the inter-hemispheric alpha coherence due to the GSM-EMFs could have clinical implications and be related to changes in cognitive-motor function.     

EEG reactivity in high and low symptomatic schizophrenics,using source modelling in the frequency domain

Summary A dipole localization method in the frequency domain was used (FFT Dipole Approximation) to assess spatial differences in the spectral EEG reactivity (orienting response) between high and low symptomatic schizophrenics. Frequency bands of interest were determined empirically by comparing the two dichotomized patient groups with two matched control groups. Evidence for a correlation between EEG reactivity and severity of schizophrenic symptomatology was found, especially in the higher beta frequency range (16 – 25.5 Hz). Opposite effects were found in the two beta ranges of 20.5–22.5 Hz and 23.0–25.5 Hz, supporting the hypothesis that different EEG frequency bands have specific functional significances and that these bands are not necessarily those that are conventionally selected.We thank W. Manske and E. Tremel for their collaboration in conducting the recordings and initial steps of data treatment, and Dr. R. D. Pascual-Marqui for his contribution to the statistical analysis of the data.     

癫癎发作早期Video-EEG监测的临床价值

目的 :探讨Video -EEG监测癫发作早期脑电变化的临床应用价值。方法 :对 96例临床确诊的癫患者进行发作早期Video -EEG监测并分析其结果。结果 :共监测到 3 2例癫发作(3 3 % ) ,其中全身性癫 4例 ;颞叶癫 16例 ,颞外癫 12例。发作早期脑电异常主要分快活动、慢活动及快慢混合活动三大类。根据发作早期脑电变化 ,2 3例 (72 % )作出定位诊断。结论 :癫发作早期脑电图脑电变化对致灶的定位 (定侧 )诊断有重要价值     

Evoked potential topography in major depression. I. Comparisons with nonpatients and schizophrenics.

This study compared evoked potential (EP) topography in major depression (MD), schizophrenia and nonpatient controls. EPs to four kinds of stimuli were recorded from 15 locations. Patients were 69 MDs and 52 schizophrenics, currently unmedicated. EP waveforms of 195 controls were subjected to principal component factor analysis (PCA). The structures of 32 factors so extracted have been shown to encompass the data space of disparate groups; they were used to compute factor scores for all subjects. Age- and gender-matched groups were compared. Factor scores were normalized across leads (Z-transform) to distinguish between topographic and mean level differences. Topographic differences (P < 0.05) between MD and controls were demonstrated for scores of 8 factors, with 2 others at P = 0.053. Unlike those for schizophrenia/control comparisons, these topographic differences did not converge regionally in MD. EP findings were not related to duration of withdrawal from drugs. There were few differences between bipolar and unipolar patients. Topographies of 5 factors differed between MDs and schizophrenics; these involved all modalities and reflected long latency, cognition-related events, such as P300. These topographic differences were antero-posterior (AP); values were greater posteriorly in MDs and anteriorly in schizophrenics. Deviant AP gradients appear specific to MD; gradients were similar in schizophrenics and controls.     

基于多特征多关系图卷积神经网络的癫痫脑电分类

目的:提出一种基于多特征多关系图卷积神经网络的癫痫脑电分类方法,改进图卷积神经网络在癫痫脑电分类领域的应用,提升分类准确率。方法:分别提取癫痫脑电信号的1个频域特征、3个时频域特征和2个非线性动力学特征作为模型节点的特征。提取脑电通道之间的空间相似性和频谱相似性,融合两种通道相似性作为整体图节点之间的边关系矩阵。结果:在TUEP数据集上进行实验,准确率、精确率、召回率、F1分数、AUC结果分别为:0.87±0.02、0.91±0.04、0.82±0.04、0.86±0.02、0.90±0.03。结论:提出的模型与单特征和单关系的图卷积神经网络相比,对于癫痫脑电分类的提升效果明显。     

Synchrony in normal and focal epileptic brain: the seizure onset zone is functionally disconnected

Synchronization of local and distributed neuronal assemblies is thought to underlie fundamental brain processes such as perception, learning, and cognition. In neurological disease, neuronal synchrony can be altered and in epilepsy may play an important role in the generation of seizures. Linear cross-correlation and mean phase coherence of local field potentials (LFPs) are commonly used measures of neuronal synchrony and have been studied extensively in epileptic brain. Multiple studies have reported that epileptic brain is characterized by increased neuronal synchrony except possibly prior to seizure onset when synchrony may decrease. Previous studies using intracranial electroencephalography (EEG), however, have been limited to patients with epilepsy. Here we investigate neuronal synchrony in epileptic and control brain using intracranial EEG recordings from patients with medically resistant partial epilepsy and control subjects with intractable facial pain. For both epilepsy and control patients, average LFP synchrony decreases with increasing interelectrode distance. Results in epilepsy patients show lower LFP synchrony between seizure-generating brain and other brain regions. This relative isolation of seizure-generating brain underlies the paradoxical finding that control patients without epilepsy have greater average LFP synchrony than patients with epilepsy. In conclusion, we show that in patients with focal epilepsy, the region of epileptic brain generating seizures is functionally isolated from surrounding brain regions. We further speculate that this functional isolation may contribute to spontaneous seizure generation and may represent a clinically useful electrophysiological signature for mapping epileptic brain.     

Automatic seizure detection in SEEG using high frequency activities in wavelet domain

Existing automatic detection techniques show high sensitivity and moderate specificity, and detect seizures a relatively long time after onset. High frequency (80–500 Hz) activity has recently been shown to be prominent in the intracranial EEG of epileptic patients but has not been used in seizure detection. The purpose of this study is to investigate if these frequencies can contribute to seizure detection. The system was designed using 30 h of intracranial EEG, including 15 seizures in 15 patients. Wavelet decomposition, feature extraction, adaptive thresholding and artifact removal were employed in training data. An EMG removal algorithm was developed based on two features: Lack of correlation between frequency bands and energy-spread in frequency. Results based on the analysis of testing data (36 h of intracranial EEG, including 18 seizures) show a sensitivity of 72%, a false detection of 0.7/h and a median delay of 5.7 s. Missed seizures originated mainly from seizures with subtle or absent high frequencies or from EMG removal procedures. False detections were mainly due to weak EMG or interictal high frequency activities. The system performed sufficiently well to be considered for clinical use, despite the exclusive use of frequencies not usually considered in clinical interpretation. High frequencies have the potential to contribute significantly to the detection of epileptic seizures.