同步EEG-功能性MRI对颞叶癫痫致痫灶的定位作用

目的 探讨同步EEG-功能性MRI(fMRI)对颞叶癫痫致痫灶的定位作用.方法 对17例症状性颞叶癫痫患者进行同步EEG-fMRI检查.对EEG出现痫样放电时的fMRI数据进行分析,将痫样放电导致的脑组织血氧水平依赖信号改变区域叠加在MRI图像上,确定癫痫灶的位置;并与手术中脑皮质电极和深部电极EEG确定的致痫灶位置进行比较.结果 10例患者同步EEG-fMRI与皮质电极和深部电极EEG确定的致痫灶的位置和范围完全相同;另外7例患者同步EEG-fMRI确定的致痫灶中心位置与皮质电极和深部电极EEG相同,但范围比后者显示的扩大.癫痫灶切除术后14例发作控制,3例发作频率明显降低.结论 同步EEG-fMRI对颞叶癫痫致痫灶的定位准确,无创伤性;对手术定位具有可靠的指导作用.     

TCA-fMRI技术在难治性癫痫致痫灶术前定位中的应用

目的探讨静息态功能性磁共振时间簇分析（TCA-fMRI）应用于难治性癫痫致痫灶术前定位的方法和价值。方法对11例难治性癫痫病人,在癫痫发作间期行静息态功能磁共振（fMRI）检查,应用TCA-fMRI技术计算与癫痫发作相关的脑内激活区（致区）,并分析比较该激活区与术中皮质电极定位致痫灶之间的吻合程度。结果 TCA-fMRI确定的激活区与术中皮质电极定位的致痫灶一致6例;激活区范围扩大3例,但最强激活区仍与皮质电极定位的癫痫灶一致;激活区较弥散2例。术后病理显示：胶质瘤3例,脑软化灶4例,灰质异位症2例,海绵状血管瘤1例,海马萎缩1例。随访1年,术后3个月、6个月及1年均复查脑电图,癫痫发作消失8例,明显减少3例;无严重并发症。结论静息态TCA-fMRI技术是一种新型、无创性的致痫灶定位方法,将静息状态下致痫灶异常放电所导致的血氧依赖水平变化在MRI三维结构图像上显示,能在术前精确定位致痫灶。     

难治性癫痫致病灶术前定位EEG联合fMRI检查的临床研究

目的探讨对难治性癫痫患者术前进行EEG联合fMRI检查确定癫痫致病灶的准确性。方法选取行外科手术的难治性癫痫患者23例为研究对象,患者佩戴能在高场强MR室中使用的EEG高级电极帽,在MR扫描的同时采集EEG数据,记录棘波发生时间,并根据棘波的发放时间输入信号曲线,找出fMRI数据,求fMRI数据体与该曲线的相应关系,将相应程度高的区域(激活区)叠加在MRI的三维图像上,从而对癫痫致病灶进行定位。将该致病灶的位置、范围与手术中脑皮质电极及深部电极中显示的致痫灶进行比较。结果 13例(56.52%)EEG联合fMRI检查显示的癫痫致病灶与术中通过皮质电极及深部电极EEG所描记、确定的致病灶位置和范围完全相同。另外10例(43.48%)EEG联合fMRI检查显示的癫痫致病灶与术中通过皮质电极及深部电极EEG所描记、确定的致病灶位置相同,但是范围明显大于术中所确定的致病灶范围;对患者出院后进行随访6个月以上,其中15例(65.22%)癫痫未再发作,5例(14.29%)术后3周内出现癫痫发作1~4次,给予抗癫痫药物治疗后得到控制,3例(13.04%)仍有发作,给予药物控制后仍无法控制,但发作频率为每月(3.1±1.4)次,较术前发作次数明显降低。结论对难治性癫痫患者术前进行EEG联合fMRI检查定位致病灶,其定位准确,时间及空间分辨率均较高且是无创性的。     

TCA-fMRI技术在难治性癫致灶术前定位中的应用

目的探讨静息态功能性磁共振时间簇分析(TCA-fMRI)应用于难治性癫致灶术前定位的方法和价值。方法对11例难治性癫病人,在癫发作间期行静息态功能磁共振(fMRI)检查,应用TCA-fMRI技术计算与癫发作相关的脑内激活区(致区),并分析比较该激活区与术中皮质电极定位致灶之间的吻合程度。结果 TCA-fMRI确定的激活区与术中皮质电极定位的致灶一致6例;激活区范围扩大3例,但最强激活区仍与皮质电极定位的癫灶一致;激活区较弥散2例。术后病理显示:胶质瘤3例,脑软化灶4例,灰质异位症2例,海绵状血管瘤1例,海马萎缩1例。随访1年,术后3个月、6个月及1年均复查脑电图,癫发作消失8例,明显减少3例;无严重并发症。结论静息态TCA-fMRI技术是一种新型、无创性的致灶定位方法,将静息状态下致灶异常放电所导致的血氧依赖水平变化在MRI三维结构图像上显示,能在术前精确定位致灶。     

功能磁共振与皮层电刺激定位感觉运动区的比较

目的 通过功能磁共振(fMRI)与皮层电刺激做点对点的比较,以判断fMRI对感觉运动区定位的精确性,从而评价其在功能定位中的意义及其临床应用价值.方法 对14例EEG示异常放电部位位于感觉运动区的难治性癫痫患者,术前采用双手握拳-伸缩运动任务进行血氧依赖水平(BOLD)扫描,运用BOLD技术的fMRI定位皮质感觉运动区.皮层电极植入术后给予头颅连续无间断CT扫描获取电极与颅骨的对应关系,通过神经导航仪将CT、fMRI影像与导航序列MRI图像融合后,得出含有皮层激活区和电极的融合图像建立三维立体图像,与皮层电刺激.结果进行比较,以评价fMRI定位皮质感觉运动区的准确性.结果 14例fMRI可见激活部位主要分布于对侧中央区、辅助运动区和小脑.其中11例成功完成皮层电刺激,结果显示fMRI与电刺激的吻合率为91.7%.结论 BOLD技术具有较高的敏感性和精确率,对感觉运动区定位有重要的临床应用价值.     

伴有中央颞区棘波的儿童良性癫痫同步脑电图-功能磁共振研究

目的 研究伴有中央颞区棘波的儿童良性癫痫(BCECTS)患者发作间期棘波相关的血氧依赖水平(BOLD)变化情况. 方法 选择海南医学院附属医院神经内科自2010年1月至2011年12月收治的频繁出现发作间期放电的BCECTS患者进行同步脑电图(EEG)联合功能磁共振(EEG-fMRI)扫描,将离线EEG滤波后确定棘波的时间点,采用统计参数图软件(SPM)提供的经典血氧动力学函数(HRF)模型计算棘波相关的BOLD变化. 结果 共纳入6例BCECTS患者,常规EEG显示频繁出现发作间期中央区和中颞区棘波.EEG-fRI扫描时1例未见放电,获得5例患者5个序列的fMRI数据,5个序列均出现BOLD激活信号,两侧中央颞区同时出现激活信号2例,单侧中央颞区出现激活信号3例,4例最大激活区位于中央-中颞区,1例位于枕叶.5例在中央颞区外的其他脑区具有激活信号. 结论 中央颢区可能是BCECTS的致痫灶,致痫灶与其他部位共同构成的神经网络可能与BCECTS的发生相关.     

同步EEG-fMRI的研究方法及其在难治性癫痫致痫灶术前定位中的应用

20世纪80年代起,由于术前评估手段的快速发展和临床的广泛应用,通过手术治疗难治性癫痫的例数显著增加。对难治性癫痫致痫灶的术前精确定位是手术能否成功的关键;近年来,同步脑电图-功能性磁共振(Simultaneous EEG-fMRI)作为一种无创的术前定位方法逐渐应用于临床,在进行功能性磁共振扫描的同时描记脑电数据,根据EEG出现癫痫波的时间点作为时间相关曲线对fMRI数据进行分析,通过测定发作间期痫样放电的血流动力学效应来定位致痫灶,可以将解剖定位与功能定位相结合,为临床医师提供一种新的、精确度较高的定位方法。     

功能性磁共振导航结合皮质电极描记切除功能区及其附近的癫痫灶

目的探讨利用fMRI导航结合皮质电极描记切除功能区及其附近癫痫灶的临床疗效。方法回顾性分析11例癫痫灶起源于功能区及其附近的癫痫病人的手术经验。病人术前发作频率（2．63±1．68）次／月。术前利用fMRI检查确定功能区位置并与导航图像进行融合,术中使用皮质电极描记标记出癫痫波的位置,通过导航系统了解功能区与癫痫波起源的关系。在保留功能区皮质的基础上,将病灶和癫痫波起源处皮质切除,而位于功能区皮质上的癫痫波起源处则给予小功率皮质热灼。结果皮质发育不全8例,灰质异位症2例,脑外伤后局部皮质软化1例。术后随访6～12个月,癫痫发作完全消失9例,术后3-6d内发作1次2例,随后未再出现癫痫发作。术后未出现明显的神经功能损害加重的情况。术后3个月复查脑电图显示基本正常。结论fMRI导航结合皮质电极描记切除起源于功能区及其附近的癫痫灶是一种微侵袭的手术方法,在切除癫痫灶的同时能最大限度地保留功能区的神经功能。     

局灶性皮质发育不良所致难治性癫痫的微创神经外科治疗

目的应用神经导航结合术中皮质电极描记,微创治疗局灶性皮质发育不良(focal cortical dysplasia,FCD)所致的难治性癫痫。方法 26例局灶性皮质发育不良所致的难治性癫痫患者,术前常规使用CT、磁共振成像(magnetic resonanceimaging,MRI)、长程视频脑电图(digital video signal and electroencephalogram,VEEG)、磁共振波谱分析(MR Spectroscopy,MRS)等检查,如病灶位于功能区则行功能性磁共振成像(functional magnetic resonance imaging,fMRI)。术中通过神经导航确定的病灶与ECoG确定的致痫灶位置及范围进行对比,了解两者的吻合程度及差异,综合分析后精确并标记出癫痫波的起源位置和范围,将局灶性皮质发育不良病灶和周边的致痫皮质切除;如致痫灶位于功能区或附近,在保留功能区皮质的基础上,给予低功率皮质热灼。结果术后病理结果:26例患者病理标本符合FCD。术后患者无明显并发症出现。根据Engel术后效果分级进行评估,Ⅰ级23例,Ⅱ级2例,Ⅲ级1例。结论神经导航结合术中皮质电极描记在局灶性皮质发育不良所致的难治性癫痫手术中,具有定位准确、损伤少的优点,在切除致痫灶的同时能最大程度保护脑功能。     

颅内电极埋藏在枕叶癫痫中的作用

目的探讨运用颅内电极埋藏进行视频脑电图监测在定位困难的枕叶癫痫中的作用。方法通过对9例枕叶癫痫但定侧定位困难的患者,向颅内可疑部位植入硬膜下条状电极,进行视频脑电图监测,记录发作间期及发作期脑电图变化,确定癫痫病灶起始区。通过手术切除致痫灶。结果本组9例埋藏时间为3～9d,平均5d,均记录到间歇期痫样放电及发作期脑电图情况。行枕叶局部皮层切除6例及枕叶切除3例。术后按照Engel评分,I级7例,II级2例。所有病例均未出现埋藏电极引起的并发症。结论在致痫灶定位困难的顽固性枕叶癫痫中,采用颅内电极埋藏进行脑电图监测,可以精确定位致痫灶,从而提高癫痫的治愈率。     

Prächirurgische Epilepsiediagnostik bei Kindern und Jugendlichen

Simultaneous recording by electroencephalography (EEG) and functional magnetic resonance imaging (EEG–fMRI) is used to investigate the hemodynamic changes associated with interictal epileptiform discharges in patients with epilepsy. The aim of this study was to evaluate whether the combination of EEG–fMRI and EEG source analysis could improve localization of epileptogenic foci in children with pharmacoresistant epilepsy. In six children with a clear epileptogenic focus EEG-fMRI and EEG source analysis were applied and i five patients hemodynamic changes in the epileptogenic zone were detected. However, additional distant regions with hemodynamic responses were observed. Source analysis located the source in the presumed epileptogenic zone in all patients and revealed propagation patterns in five cases. A correspondence between source localization and hemodynamic changes outside the epileptogenic zone was found so that EEG source analysis may help to interpret the results of EEG-fMRI.     

Combining EEG and fMRI in the study of epileptic discharges

The combining of electroencephalography (EEG) and functional magnetic resonance imaging (fMRI) is a unique noninvasive method for investigating the brain regions involved at the time of epileptic discharges. The neuronal discharges taking place during an interictal spike or spike-wave burst result in an increase in metabolism and blood flow, which is reflected in the blood oxygen-level dependent (BOLD) signal measured by fMRI. This increase is most intense in the region generating the discharge but is also present in regions affected by the discharge. On occasion, epileptic discharges result in decreased metabolism, the origin of which is only partially understood. EEG-fMRI applied to focal epilepsy results in maxima of the BOLD signal most often concordant with other methods of localization and has been shown to help in localizing epileptic foci in nonlesional frontal lobe epilepsy. It has also demonstrated the involvement of the thalamus in generalized epileptic discharges. In patients with new-onset epilepsy it could be used to evaluate the source and extent of the brain structures involved during discharges and their evolution as the disease progresses.     

Detecting sub-second changes in brain activation patterns during interictal epileptic spike using simultaneous EEG-fMRI

Objective

Epileptic spikes are associated with rapidly changing brain activation involving the epileptic foci and other brain regions in the “epileptic network”. We aim to resolve these activation changes using simultaneous electroencephalography (EEG) and functional magnetic resonance imaging (fMRI) recordings.

EEG-fMRI study of the interictal epileptic activity in patients with partial epilepsy

PURPOSE: To investigate Blood Oxygen Level Dependent (BOLD) responses to interictal epileptic discharges (IEDs) during EEG-correlated functional MRI (EEG-fMRI) in patients with partial epilepsy. METHODS: We studied eight patients who had a diagnosis of partial epilepsy and active spiking on routine scalp EEG recording. Sessions of continuous EEG-fMRI were recorded, and spikes (identified after online artifact removal) were used as events in the fMRI analysis. Regions of BOLD signal change in response to interictal epileptic discharge were assessed and epileptogenic zone localization was electroclinically identified. RESULTS: Eight patients with partial epilepsy were recruited (6 males, 2 females, mean age 18.5, mean onset age range 0.5-29). Two who underwent EEG-fMRI were excluded from further analysis: one due to absence of epileptic discharges, the other due to excessive head motion. Eight sessions of EEG-fMRI scanning in 6 patients were obtained: 6 with activation and deactivation, one with activation only, and one with deactivation only. Focal activations corresponding to electroclinical localization occurred in 7 sessions, 5 of which were maximal. CONCLUSIONS: Maximally activated areas detected by EEG-fMRI in patients with partial epilepsy appear to be concordant with epileptogenic areas as defined by electroclinical localization data. In most patients with focal epilepsy, positive BOLD responses seem to be mainly in epileptogenic zones and the corresponding contralateral areas. Responses to deactivation seem less associated with IEDs. So EEG-fMRI is a useful tool to study the pathophysiological mechanisms of epilepsy and may assist in presurgical evaluation of epilepsy.     

fMRI activation in continuous and spike-triggered EEG-fMRI studies of epileptic spikes

PURPOSE: To evaluate functional magnetic resonance imaging (fMRI) with simultaneous EEG for finding metabolic sources of epileptic spikes. To find the localizing value of activated regions and factors influencing fMRI responses. METHODS: Patients with focal epilepsy and frequent spikes were subjected to spike-triggered or continuous fMRI with simultaneous EEG. Results were analyzed in terms of fMRI activation, concordance with the location of EEG spiking and anatomic MRI abnormalities, and other EEG and clinical variables. In four patients, results also were compared with those of intracerebral EEG. RESULTS: Forty-eight studies were performed on 38 patients. Seventeen studies were not analyzed, primarily because no spikes occurred during scanning. Activation was obtained in 39% of 31 studies, with an activation volume of 2.55 +/- 4.84 cc. Activated regions were concordant with EEG localization in almost all studies and confirmed by intracerebral EEG in four patients. Forty percent of patients without an MRI lesion showed activation; 37.5% of patients with a lesion had an activation; the activation was near or inside the lesion. Bursts of spikes were more likely to generate an fMRI response than were isolated spikes (76 vs. 11%; p < 0.05). CONCLUSIONS: Combining EEG and fMRI in focal epilepsy yields regions of activation that are presumably the source of spiking activity. These regions are highly linked with epileptic foci and epileptogenic lesions in a significant number of patients. Activation also is found in patients with no visible MRI lesion. Intracerebral recordings largely confirm that these activation regions represent epileptogenic areas. It is still unclear why many patients show no activation.     

Moving GLM ballistocardiogram artifact reduction for EEG acquired simultaneously with fMRI.

OBJECTIVE: Simultaneous acquisition of electroencephalogram (EEG) and functional magnetic resonance imaging (fMRI) enables studies of brain activity at both high temporal and high spatial resolution. However, EEG acquired in a magnetic field is contaminated by ballistocardiogram (BKG) artifact. The most commonly used method of BKG artifact reduction, averaged artifact subtraction (AAS), was not designed to account for overlapping BKG waveforms generated by adjacent beats. We describe a new method based on a moving general linear model (mGLM) that accounts for overlapping BKG waveforms. METHODS: Simultaneous EEG-fMRI at 3 Tesla was performed in nine normal human subjects (8-11 runs/subject, 5.52 min/run). Gradient switching artifact was effectively reduced using commercially supplied procedures. Cardiac beats were detected using a novel correlation detector algorithm applied to the EKG trace. BKG artifact was reduced using both mGLM and AAS. RESULTS: mGLM recovered BKG waveforms outlasting the median inter-beat interval. mGLM more effectively than AAS removed variance in the EEG attributable to BKG artifact. CONCLUSIONS: mGLM offers advantages over AAS especially in the presence of variable heart rate. SIGNIFICANCE: The BKG artifact reduction procedure described herein improves the technique of simultaneous EEG-fMRI. Potential applications include basic investigations of the relationship between scalp potentials and functional imaging signals as well as clinical localization of epileptic foci.     

Metabolic correlates of epileptic spikes in cerebral cavernous angiomas

BACKGROUND: Cerebral cavernous angiomas (CCA) are frequently associated with focal intractable epilepsy. Epileptogenicity is usually attributed to hemosiderin deposits. Combined recording of electroencephalogram (EEG) and functional magnetic resonance imaging (fMRI) is a new method to investigate epileptic discharges. METHODS: We used EEG-fMRI to identify BOLD responses to interictal spikes in patients with CCA. Responses were analyzed in the lesional and perilesional area, and at distance. RESULTS: Eight patients were scanned, all with temporal lobe epilepsy and spikes. One patient had bilateral spikes, analyzed separately, and three studies with less than two spikes were excluded. All six studies analyzed showed BOLD responses. No response was found in the lesion itself or immediate periphery, and the raw fMRI signal showed signal loss in lesional and perilesional areas in all patients. Responses were close to the perilesional area in 2/6 studies. All patients showed responses at a distance from the lesions. CONCLUSIONS: Despite susceptibility artifacts caused by iron deposits, we demonstrated EEG-fMRI responses involving the perilesional areas in 33% of studies. We also demonstrated diffuse rather than focal responses, in accordance with previous studies in lesional and non-lesional temporal lobe epilepsy, confirming the frequent distant effect of epileptic spikes.     

Temporal and extratemporal BOLD responses to temporal lobe interictal spikes

PURPOSE: Simultaneous EEG and functional MRI (fMRI) allows measuring metabolic changes related to interictal spikes. Our objective was to investigate blood oxygenation level-dependent (BOLD) responses to temporal lobe (TL) spikes by using EEG-fMRI recording. METHODS: We studied 35 patients who had a diagnosis of temporal lobe epilepsy (TLE) and active TL spiking on routine scalp EEG recording. Two-hour sessions of continuous EEG-fMRI were recorded, and spikes were identified after offline artifact removal and used as events in the fMRI analysis. Each type of spike was analyzed separately, as one EEG-fMRI study. We determined significant (p < 0.05) positive (activation) and negative (deactivation) BOLD responses for each study. RESULTS: Twenty-seven patients had spikes during scanning (19 unilateral and eight bilateral). From a total of 35 fMRI studies, 29 (83%) showed BOLD responses: 14 had both activations and deactivations; 12, activations only; and three, deactivations only. Six (17%) showed no responses. Nineteen studies had mainly neocortical TL activation: Sixteen (84%) of 19 concordant with spikes, 12 of 16 with concomitant activation of the contralateral TL, and 16 of 19 with additional extratemporal activation; few showed exclusively mesial TL activation. Seventeen studies showed deactivation, either extratemporal plus temporal (n = 8) or exclusively extratemporal (n = 9). CONCLUSIONS: BOLD responses to TL spikes occurred in 83% of studies, predominated in the spiking temporal lobe, and manifested as activation or deactivation. Responses often involved the contralateral homologous cortex at the time of unilateral spikes and were frequently observed in extratemporal regions, suggesting that TL epileptic spikes can affect neuronal activity at a distance through synaptic connections.     

Use of functional MRI in epilepsy]

For the purpose of examining pathophysiological mechanisms of a memory function in epileptic patients or an utility of fMRI for a presurgical assessment in neurosurgical treatment of epilepsy, activated areas in fMRI during verbal or visual memory task were investigated in patient group of temporal lobe epilepsy and normal subject group. Patient group of temporal lobe epilepsy consisted of 7 cases, of which 3 and 3 cases had left and right temporal foci, respectively, except 1 case having undetermined laterality of temporal foci. Normal subjects were 16 cases. All the epileptic and normal subjects were right-handed except for 1 lefty normal subject. Verbal memory tasks were composed of covert and overt recall tasks of 10 words given auditorily, while visual ones were recall tasks of 6 figures given visually. Eventually, in normal subjects, the left side-dominant medial frontal lobes including the superior frontal and anterior cingulate gyri were mainly activated in fMRI during the covert recall tasks of verbal memory, while the left side-dominant inferior frontal and precentral gyri as the motor language areas were chiefly activated in addition to the medial frontal lobe during the overt recall tasks. Further, the bilateral occipital lobes were activated in fMRI during the recall tasks of visual memory. Also in patient groups of temporal lobe epilepsy, the activated areas in fMRI during these tasks were the same as in normal subject group, regardless of the laterality of epileptic temporal foci. These results suggest that fMRI is useful for the determination of the lateralization of the cerebral hemisphere contributing to verbal memory function and therefore for the presurgical assessment of memory function in neurosurgical treatment of epilepsy.