脑磁图在神经外科中的应用

目的 探讨脑磁图（MEG）在癫痫外科中的定位价值。方法 本组26例癫痫患，男18例，女8例，术前均行脑电图（EEG）检查和影像学检查，同时做了脑磁图（MEG）检查。所有患手术均在MEG指导下进行，术中加用皮层脑电图（ECoG)监测。结果 26例患均能通过MEG进行术前致痫灶与功能定位，其阳性率明显高于EEG和影像学检查。术后复查EEG，22例患较好。短期随访1－3个月，25例患癫痫发作完全消失。结论 MEG是一项术前痫灶定位和功能保护的有效检查方法。     

脑磁图静息态脑网络定位与皮质脑电图的对照研究

目的：探讨脑磁图（ MEG）静息态脑网络定位与皮质脑电图（ ECoG）的一致性。方法选取难治性癫痫患者16例,术前均运用脑磁图静息态网络定位,同时运用传统的脑磁图Dipole法和SAM法皮质脑电图定位,与皮质脑电图的结果对照,分别比较两种技术的吻合度。结果16例患者均有明显的棘波放电, Dipole定位局限10例,散发6例,SAM值升高单病灶11例,多病灶5例。16例患者均显示静息态脑网络异常,敏感度100％（16／16）。 Dipole定位ECoG的定位符合率为62．5％（10／16）,SAM与ECoG的定位符合率为68．7％（11／16）,MEG脑网络功能异常与ECoG 的定侧符合率为100％,定位符合率为81．2％（13／16）。结论脑磁图静息态网络定位可以敏感地定位癫痫放电区,可以为癫痫手术规划提供帮助。     

顽固性癫痫患者术前MEG、V-EEG、MRI与术中ECoG的对比

目的　探讨脑磁图 (magnetoencephalography ,MEG)对顽固性癫痫患者致痫灶定位的可行性及临床应用价值。方法　本组 6 3例患者中 ,男 4 4例 ,女 19例 ,年龄 5～ 5 2岁 (平均 2 2 .9岁 ) ,病程 1～ 2 0年 (平均 7.7年 )。所有患者术前均行MEG检查 ,同时还行了视频脑电图 (V EEG)和磁共振成像 (MRI)检查 ,将它们的检查结果与术中皮质脑电图 (ECoG)监测进行对比。结果　术前MEG、V EEG和MRI检查的阳性率分别为 81.0 % (5 1/ 6 3)、85 .7% (5 4 / 6 3)和 88.9% (5 6 / 6 3) ,三者比较差异性不显著 (P >0 .0 5 )。而术前MEG、V EEG和MRI检查与术中ECoG监测结果的符合率分别为 90 .2 % (46 / 5 1)、74 .1% (40 / 5 4 )和 76 .8% (43/ 5 6 ) ,MEG的符合率与V EEG、MRI相比较有极显著性差异 (P <0 .0 1)。MEG、V EEG和MRI三项检查的结果结合起来与术中ECoG监测结果总的符合率为 96 .8% (6 1/ 6 3)。结论　MEG是一种无创性术前致痫灶定位技术 ,其与术中ECoG检测的符合率明显高于V EEG和MRI。MEG联合V EEG和MRI等多种术前检查技术 ,可进一步提高顽固性癫痫患者的致痫灶的定位准确性     

磁共振阴性的局灶性脑皮质发育不良的手术治疗

目的探讨磁共振难以确定病灶的致痫性局灶性脑皮质发育不良的诊断和定位方法,提高手术治疗效果。方法回顾性分析联合应用视频脑电图(VEEG)、脑磁图(MEG)及术中皮层电极脑电图监测(ECo G)检查,诊断、定位并经手术后病理证实为局灶性皮质发育不良(FCD)的24例磁共振检查阴性的难治性癫痫患者的临床资料。结果 24例癫痫患者行手术治疗,病理FCDⅠa型5例,FCDⅠb型3例,FCDⅠc型5例,FCDⅡa型6例,FCDⅡb型5例。术后随访1~5年,EngelⅠ级9例,EngelⅡ级5例,EngelⅢ级8例,EngelⅣ级2例。结论联合应用VEEG、MEG和(或)ECo G技术有助于准确诊断和定位磁共振阴性的FCD,提高FCD致难治性癫痫的手术疗效。     

脑磁图对有颅内肿瘤的癫痫病人局部致痫灶的定位价值

目的研究脑磁图（magnetoencephlography,MEG）在颅内肿瘤的癫痫病人中致痫灶的定位价值.方法选择经手术、病理证实的颅内肿瘤25例,术前通过148信道MEG系统记录和分析自发脑磁活动.结果本组25例患者中有21例术前致癫灶MEG定位结果与术中ECoG证明的一致,两者符合率达84%.术后随访3～37个月,平均17个月.手术总有效率达96%.25例患者中19例肿瘤的位置和癫痫灶的位置一致,致癫灶位于肿瘤边缘者10例;距肿瘤约2cm者9例;远隔部位异常者4例;MEG检查没有阳性发现者2例.结论MEG对于预测颅内肿瘤的致痫灶是一种有用的方法,它有助于制定切除病变并同时处理癫痫外科的手术计划.     

脑磁图定位顽固性癫痫手术治疗51例临床分析

目的　探讨脑磁图在顽固性癫痫术前评估的价值。方法　术前对 5 1例顽固性癫痫患者行脑磁图、磁共振及视频脑电检查 ,结合术中皮层脑电图分别进行选择性海马杏仁核切除术、标准前颞叶切除术及致痫灶切除术等手术 ;并用脑磁图定位神经导航下手术切除致痫灶 2例 ,神经导航下海马杏仁核切除 2例。结果　术后发作完全停止的占 76 5 % ,发作减少 >75 %的占 11 8% ,发作减少>5 0 %的占 5 8% ,发作减少不足 5 0 %的占 5 8% ;脑磁图与视频脑电及皮层脑电图的定位符合率分别为 82 %和 96 % ;脑磁图对内侧颞叶癫痫的定位敏感性较差 ;脑磁图定位导航手术可在切除致痫灶的同时保护脑的重要结构。结论　脑磁图是一项灵敏的无创性癫痫灶定位方法 ,是癫痫外科术前评估中的一项技术突破     

脑磁图联合颅内电极脑电图在癫痫外科治疗中的应用

目的研究脑磁图(MEG)与颅内电极脑电图(i EEG)联合在癫痫外科治疗中的应用价值。方法应用MEG参与到将行颅内电极埋置患者的术前评估中:根据电-临床症状学、影像学、脑电图、MEG等结果设计出颅内电极埋置方案,进而行颅内电极置入并监测i EEG,捕捉发作期,最终根据定位结果行手术治疗。结果最终成功定位癫痫发作起始区并手术治疗者38例。其中证实为颞叶癫痫(TLE)的16例中,MEG与i EEG定位一致者仅6例,而颞叶以外癫痫(NTLE)22例中两者一致者达16例,两组结果有统计学差异。所有患者术后随访:EngelⅠ级28例,Ⅱ级5例,Ⅲ级3例,Ⅳ级2例。结论 MEG运用于NTLE时较TLE有着更高的与i EEG的一致率。区别于视频脑电图、MRI等其它的无创检查,MEG能够对有创的i EEG电极埋置起到额外指导作用。MEG与i EEG联合,能使电极埋置更合理精确、有针对性,能获得较高的癫痫手术疗效。     

PET与MEG定位伽玛刀治疗顽固性癫痫临床及脑电图研究

目的 评估PET与MEG定位、伽玛刀治疗顽固性癫痫临床效果和脑电图变化.方法 Leksell-C型伽玛刀治疗难治性癫痫33例,30例获得随访列入研究,EEG检查26例异常.分为PET组(22例)和MEG组(8例),发作频率分别为4.8±1.9次/月和4.6±2.2次/月.根据癫痫发作特点、脑电图、PET或脑磁图、CT或MRI定位致痫灶.周边剂量为8～13Gy,中心剂量为16～45Gy,照射范围略大于PET和MEG所提示的致痫区范围.术后每3个月复查EEG,并对照术前EEG,观察癫痫发作控制情况,按国际癫痫学会分类法分为6级进行疗效判定.结果 随访时间6～19个月,Ⅰ～Ⅱ级10例(33.3%),Ⅲ～Ⅳ级14例(46.7%),Ⅴ级4例(13.3%),Ⅵ级2例(6.7%).总有效率80.0%.PET与MEG两组病例癫痫发作频次皆较术前明显减少,术后12个月分别降至2.0±1.3次/月和1.8±1.1次/月.随访EEG逐渐恢复正常12例(48.0%),好转9例(36.0%),无变化2例(8.0%),恶化2例(8.0%).PET与MEG两组之间在治疗前后都没有差别.结论 PET或MEG定位致痫灶,伽玛刀治疗顽固性癫痫疗效肯定,EEG可以在术后随访中发挥作用.     

脑磁图对难治性癫痫致痫区定位价值

目的探讨脑磁图癫痫定位技术对难治性癫痫致痫区定位的价值。方法回顾性分析难治性癫痫病人58例,术前行视频头皮脑电图、磁共振、脑磁图、颅内埋藏电极皮层脑电图等检查,综合评估确定致痫灶的位置。根据综合评估致痫区制定手术方案并实施,随访并判定疗效。根据脑磁图癫痫定位和综合评估致痫区吻合度分为3组,Ⅰa组：完全吻合一两区域中心位置在1cm以内,Ⅰb组：基本吻合一两区域中心位置在1～3cm;Ⅱ组：不吻合一两区域中心位置在3cm以外或其他。统计分析各组间疗效的差异。结果本组总有效率为77．6％（45／58）,其中癫痫完全消失18例;Ⅰa、Ⅰb组手术疗效无明显差异,但Ⅰ组手术疗效明显优于Ⅱ组。结论脑磁图癫痫定位是难治性癫痫术前评估的重要方法之一,当脑磁图癫痫定位和术前综合评估致痫区基本一致时,手术疗效相对较好。     

视频脑电图结合磁共振扫描对颞叶癫痫术前定位的探讨

目的 探讨视频脑电图及磁共振扫描对颢叶癫痫术前定位的准确性.方法 回顾分析146例颞叶癫痫病例,术前均行长程视频脑电图(V/EEG)监测及磁共振扫描(MRI),发作时V/EEG所示的痫样放电部位与MRI检查所发现的病变同侧时,将此侧颞叶作为癫痫灶颞叶;MRI未见异常,则根据三次以上发作时V/EEG定侧.所有患者经术中皮层脑电图和深部脑电监测后,行前颞叶切除术.结果 术中皮层脑电图及深部脑电监测均发现有痫样放电,与术前V/EEG监测吻合.术后102例(70%)癫痫发作完全消失,显著改善35例(24%),良好6例(4%),无改善3例(2%).结论 V/EEG结合MRI对颞叶癫痫术前能进行准确定位.     

联合应用电生理技术对癫痫灶精确定位的研究

目的:联合应用多种电生理技术(EEG)对痫灶进行定位。方法:运用多种EEG技术对50例癫痫患者行痫灶定位,并与各种神经影像学检查方法进行比较。定位明确患者行手术治疗,标本行光镜及透射电镜检查,治疗结果以Engel疗效分级评价。结果:使用EEG技术对痫灶定位,其准确率为83.3％,以EEG技术为基础,并与神经影像学方法联合应用,痫灶定位准确率则达到100％。具有EEG异常的癫痫患者,痫灶必然伴有相应病理性损害。结论:反复、多次视频脑电(VEEG)监测,是痫灶定位的首选方法。多种类型的EEG在不同的时段进行监测,是高效、经济、安全无创,可明显提高癫痫灶的检出率及定位的准确性,提高手术疗效。     

Magnetoencephalographic and electroencephalographic evaluation in patients with cryptogenetic partial epilepsy.

Magnetoencephalography (MEG) has been applied for more than 20 years to the localization of the epileptic focus in partial epilepsies, but correlation with electroencephalographic (EEG) data in homogeneous groups of patients is scarce. OBJECTIVE: The aim of our work was to use EEG and MEG for the study of a group of adults and children affected by cryptogenetic partial epilepsy. METHODS: We analyzed the traces obtained from electroencephalographic and magnetoencephalographic recordings of 10 patients of ages ranging from 7 to 38 years affected by cryptogenetic partial epilepsy. We evaluated the presence of commonly detected or uniquely detected spikes, and, whenever possible, we used MEG for localization of the epileptic focus. RESULTS: Three patients showed no epileptic activity during the EEG and MEG sessions. Overall agreement between EEG and MEG (presence of concordant spikes with the same localization shown by both techniques) was obtained in five patients. In one patient the spikes detected by EEG and MEG were different, and in another patient interictal activity was demonstrated exclusively by EEG. CONCLUSIONS: EEG in this series was not inferior to MEG in terms of spike detection. Combination of EEG and MEG is feasible, better than each technique alone, and may be useful for non-invasive diagnosis and monitoring of pediatric and adult patients with partial epilepsies.     

Benefit of simultaneous recording of EEG and MEG in dipole localization

PURPOSE: In this study, we tried to show that EEG and magnetoencephalography (MEG) are clinically complementary to each other and that a combination of both technologies is useful for the precise diagnosis of epileptic focus. METHODS: We recorded EEGs and MEGs simultaneously and analyzed dipoles in seven patients with intractable localization-related epilepsy. MEG dipoles were analyzed by using a BTI Magnes 148-channel magnetometer. EEG dipoles were analyzed by using a realistically shaped four-layered head model (scalp-skull-fluid-brain) built from 2.0-mm slice magnetic resonance imaging (MRI) images. RESULTS: (a) In two of seven patients, MEG could not detect any epileptiform discharges, whereas EEG showed clear spikes. However, dipoles estimated from the MEG data corresponding to the early phase of EEG spikes clustered at a location close to that of the EEG-detected dipole. (b) In two of seven patients, EEG showed only intermittent high-voltage slow waves (HVSs) without definite spikes. However, MEG showed clear epileptiform discharges preceding these EEG-detected HVSs. Dipoles estimated for these EEG-detected HVSs were located at a location close to that of the MEG-detected dipoles. (c) Based on the agreement of the results of these two techniques, surgical resection was performed in one patient with good results. CONCLUSIONS: Dipole modeling of epileptiform activity by MEG and EEG sometimes provides information not obtainable with either modality used alone.     

Characterizing magnetoencephalographic spike sources in children with tuberous sclerosis complex

PURPOSE: Tuberous sclerosis complex (TSC) often causes medically intractable seizures. Magnetoencephalography (MEG) localizes epileptiform discharges. To evaluate the use of MEG spike sources (MEGSSs) for localizing epileptic zones in TSC patients, we characterized MEGSSs and correlated them to EEG and magnetic resonance imaging (MRI) results. METHODS: We analyzed data from seven children who underwent prolonged video-EEG, MEG, and MRI. We classified MEGSSs as clusters (six or more spike sources, 1 cm between sources regardless of number of sources). RESULTS: A single, unilateral cluster with additional scatters occurred in two patients; these predominantly lateralized dipoles correlated to prominent tubers on MRI and ictal/interictal EEG zones. Bilateral clusters with scatters existed in two patients; cluster locations partly overlapped multiple prominent tubers. These patients also had bilateral or diffuse interictal discharges, bilateral or generalized seizures, and changing seizure types and EEG findings. Only bilateral scatters occurred in three patients; scatters partly overlapped EEG interictal/ictal-onset regions; one patient had coexisting generalized seizures. In one patient with equally bilateral scatters, scatters overlapped a prominent tuber and interictal/ictal-onset zones in the right frontal region. CONCLUSIONS: MEG contributes to information from EEG and MRI for localizing epileptogenic zones in children with TSC. A single cluster with scatters in a unilateral hemisphere predicts a primary epileptogenic zone or hemisphere; bilateral or multiple clusters indicate bilateral primary or potential epileptogenic zones; and bilateral scatters without clusters may indicate epileptogenic zones that are hidden within extensive areas of scattered MEGSSs.     

High-resolution source imaging in mesiotemporal lobe epilepsy: a comparison between MEG and simultaneous EEG.

Magnetic source imaging is claimed to have a high accuracy in epileptic focus localization and may be a guide for epilepsy surgery. Non-lesional mesiotemporal lobe epilepsy (MTLE), the most common form of epilepsy operated on, has different etiologies, which may affect the choice of surgical approach. The authors compared whole-head magnetoencephalography (MEG) with high-resolution EEG for source identification in MTLE. Nineteen patients with unilateral, nonlesional MTLE underwent a simultaneous 151-channel CTF MEG (CTF Systems, Inc., Port Coquitlam, British Columbia, Canada) and 64-channel EEG recordings with sleep induction. Three independent observers selected spikes from the EEG and MEG recordings separately. Only when there was interobserver agreement (kappa>0.4) on the presence of spikes in recordings were consensus spikes averaged. EEG and MEG equivalent current dipoles (ECD) were then integrated in the head model of the patient reconstructed from MRI. The results were compared with intraoperative electrocorticography findings. Spikes were detected in 32% of MEGs and 42% of EEGs. No patient showed MEG spikes only. Equivalent current dipole modeling correctly localized the source to the temporal lobe in four out of five MEG and three out of eight EEG recordings. MEG localized sources were more superficial and EEG localized sources were deeper. Unfortunately, basal temporal lobe areas were only partially covered by the sensor helmet of the MEG setup. Best correlation between EEG or MEG findings and electrocorticography findings was between horizontal EEG dipole orientation and prominent neocortical spiking; these patients also had a less favorable prognosis. Magnetic source imaging is currently unlikely to alter the surgical management of MTLE. The yield of spikes is too low, and ECD modeling shows only partial correlation with electrocorticography findings. Moreover, the whole-head MEG helmet provides insufficient coverage of the temporal lobe.     

Magnetoencephalographic studies of focal epileptic activity in three patients with epilepsy suggestive of Lennox-Gastaut syndrome.

PURPOSE: To determine the electromagnetic sources of localized epileptic activities using magnetoencephalography (MEG) in three adult patients with epilepsy suggestive of Lennox-Gastaut syndrome (LGS).METHODS: MEG and simultaneous electroencephalography (EEG) were recorded from three adult patients using a 204-channel, whole-head MEG system. Equivalent current dipoles (ECDs) were calculated for epileptic spikes on MEG according to the single dipole model.RESULTS: In two patients, MEG showed epileptiform discharges restricted to the unilateral temporal area, corresponding to the EEG spikes. The ECDs calculated from these MEG spikes were clustered in the unilateral temporal lobe. In our third patient, MEG spikes appeared in the right centroparietal area; ECDs were located to the right parietal lobe.CONCLUSIONS: The sources of epileptiform discharges that were detected in a restricted area were localized to specific parts of the brain cortex. Despite certain limitations (small number of patients; atypical late-onset epilepsy in one) our study suggests that MEG may prove to be a useful tool for investigating electromagnetic features of localized epileptic discharges in patients with LGS. Based on these preliminary results, further studies performed in patients with typical LGS features are justified.     

100例癫痫患者脑电图与磁共振分析

目的:观察脑电图和头颅MRI在确诊癫痫及其病因诊治方面的应用,探讨痫性放电与结构异常之间的关系。方法:选100例癫痫患者,均作REEG、AEEG、头颅CT和MRI检查。比较四种检查方法的阳性率和异常病灶的分布。应用卡方检验,比较痫性放电与结构异常之间的关系。结果;REEG痫性放电35例(35%),AEEG76例(76%),比REEG多提供了41%的异常信息。CT发现颅内异常25例(25%),MRI发现异常58例(58%)。在EEG单侧局灶放电的53例中,MRI异常42例,18例双侧半球放电中,MRI异常5例,经x2检验,局灶痫性放电者MRI异常率显著高于双侧半球痫性放电者(P<0.01);MRI正常的42例患者中EEG痫性放电26例,异常率为61.9%,MRI发现结构异常的58例患者中,EEG异常放电50例,异常率为86.2%,经x2检验发现MRI结构异常患者,痫性放电出现率高(P<0.01)。结沦:AEEG是确诊癫痫、指导治疗的有利依据;MRI可作为癫痫患者病因诊断的首选影像检查。痫性放电与结构异常有一定关系。     

Periventricular nodular heterotopia: classification, epileptic history, and genesis of epileptic discharges

PURPOSE: Periventricular nodular heterotopia (PNH) is among the most common malformations of cortical development, and affected patients are frequently characterized by focal drug-resistant epilepsy. Here we analyzed clinical, MRI, and electrophysiologic findings in 54 PNH patients to reevaluate the classification of PNH, relate the anatomic features to epileptic outcome, and ascertain the contribution of PNH nodules to the onset of epileptic discharges. METHODS: The patients were followed up for a prolonged period at the Epilepsy Center of our Institute. In all cases, we related MRI findings to clinical and epileptic outcome and analyzed interictal and ictal EEG abnormalities. In one patient, EEG and stereo-EEG (SEEG) recordings of seizures were compared. RESULTS: We included cases with periventricular nodules, also extending to white matter and cortex, provided that anatomic continuity was present between nodules and malformed cortex. Based on imaging and clinical data, patients were subdivided into five PNH groups: (a) bilateral and symmetrical; (b) bilateral single-noduled; (c) bilateral and asymmetrical; (d) unilateral; and (e) unilateral with extension to neocortex. The latter three groups were characterized by worse epileptic outcome. No differences in outcome were found between unilateral PNH patients regardless the presence of cortical involvement. Interictal as well as ictal EEG abnormalities were always related to PNH location. CONCLUSIONS: The distinctive clinical features and epileptic outcomes in each group of patients confirm the reliability of the proposed classification. Ictal EEG and SEEG recordings suggest that seizures are generated by abnormal anatomic circuitries including the heterotopic nodules and adjacent cortical areas.     

The magnetic field of epileptic spikes agrees with intracranial localizations in complex partial epilepsy

The magnetoencephalogram (MEG) and electroencephalogram (EEG) were measured during interictal epileptic spikes in nine patients with complex partial seizures. The MEG localization estimates were compared with localizations by intraoperative cortical electrodes, subdural electrodes, stereotaxic depth electrodes, anatomic imaging, postoperative pathologic analysis, and postoperative follow-up. In all patients, MEG localization estimates were in the same lobe as the epileptic focus determined by invasive methods and EEG. In two patients, it was possible to quantify precisely the accuracy of MEG localization by mapping a spike focus that was visually indistinguishable on MEG and cortical recordings. In both patients, MEG localization was approximately 12 mm from the center of the cortical spike focus on intracranial recordings. In eight patients, MEG showed tangential dipolar field patterns on the spontaneous record, but EEG did not. In one patient, a cortical epileptic discharge was detected only on MEG for some discharges and only on EEG for other discharges. The MEG did not detect deep spikes with present levels of environmental noise.     

Reproducibility of EEG‐MEG fusion source analysis of interictal spikes: Relevance in presurgical evaluation of epilepsy

Fusion of electroencephalography (EEG) and magnetoencephalography (MEG) data using maximum entropy on the mean method (MEM‐fusion) takes advantage of the complementarities between EEG and MEG to improve localization accuracy. Simulation studies demonstrated MEM‐fusion to be robust especially in noisy conditions such as single spike source localizations (SSSL). Our objective was to assess the reliability of SSSL using MEM‐fusion on clinical data. We proposed to cluster SSSL results to find the most reliable and consistent source map from the reconstructed sources, the so‐called consensus map. Thirty‐four types of interictal epileptic discharges (IEDs) were analyzed from 26 patients with well‐defined epileptogenic focus. SSSLs were performed on EEG, MEG, and fusion data and consensus maps were estimated using hierarchical clustering. Qualitative (spike‐to‐spike reproducibility rate, SSR) and quantitative (localization error and spatial dispersion) assessments were performed using the epileptogenic focus as clinical reference. Fusion SSSL provided significantly better results than EEG or MEG alone. Fusion found at least one cluster concordant with the clinical reference in all cases. This concordant cluster was always the one involving the highest number of spikes. Fusion yielded highest reproducibility (SSR EEG = 55%, MEG = 71%, fusion = 90%) and lowest localization error. Also, using only few channels from either modality (21EEG + 272MEG or 54EEG + 25MEG) was sufficient to reach accurate fusion. MEM‐fusion with consensus map approach provides an objective way of finding the most reliable and concordant generators of IEDs. We, therefore, suggest the pertinence of SSSL using MEM‐fusion as a valuable clinical tool for presurgical evaluation of epilepsy.