磁共振弥散张量成像在内侧颞叶癫痫中的应用进展

内侧颞叶癫痫(mTLE)是最常见的难治性癫痫类型.磁共振弥散张量成像能提供mTLE患者脑组织微观结构变化的定性、定量信息,有助于对颞叶癫痫病理生理机制理解,并可用于颞叶癫痫脑网络结构的研究.本文对磁共振弥散张量成像在mTLE中的应用进展作一综述.     

单侧颞叶内侧癫痫伴海马硬化患者脑内在活动改变

目的 观察颞叶内侧癫痫(mTLE)伴海马硬化患者脑内在活动(IBA)改变。方法 纳入38例单侧mTLE伴海马硬化患者(mTLE组)和53名健康志愿者[健康对照(HC)组],比较组间IBA静态指标,包括低频振幅(ALFF)、比率ALFF(fALFF)、局部一致性(ReHo)、度中心性(DC)、全局信号相关性(GSCorr)和体素镜像同伦连接(VMHC)]及其对应动态指标dALFF、dfALFF、dReHo、dDC、dGSCorr及dVMHC,分析其与癫痫持续时间和认知评估量表的相关性。结果 相比HC组,mTLE组双侧丘脑、内侧颞叶、基底核、脑桥及小脑ALFF、dALFF和fALFF值,右侧扣带回及补充运动区fALFF值,右侧内侧颞叶、梭状回及基底核dfALFF值,脑桥、双侧丘脑、双侧尾状核及左侧内侧颞叶ReHo值均升高;左侧颞叶新皮质和额叶fALFF值和dfALFF值,双侧颞叶新皮质ReHo值和DC值,左侧颞叶新皮质dReHo和GSCorr值,双侧颞叶新皮质、小脑及内侧颞叶VMHC值,双侧枕叶、楔叶及补充运动区dVMHC值均降低。mTLE组形状连线测试A耗时与左侧丘脑ALFF值、左侧海马...     

功能连接密度图观察内侧颞叶癫痫

目的 采用静息态fMRI功能连接密度（FCD）方法观察内侧颞叶癫痫（mTLE）脑功能活动改变的分布模式。方法 分别采集47例mTLE患者与32名正常志愿者（正常对照组）的静息态fMRI数据,通过两样本t检验,观察mTLE患者相对正常对照组的FCD活动改变,并采用基于体素的相关分析观察mTLE患者FCD改变脑区与癫痫病程的关系。结果 与正常对照组相比,mTLE患者发作间期FCD降低区域以双侧内侧颞叶、后扣带回、外侧颞叶和顶叶区为主;FCD增高区域主要分布于双侧感觉运动区（P<0.05,FWR多重校正）。基于体素的相关性分析显示,mTLE病程与双侧内侧颞叶、后扣带回及顶叶区的FCD值呈负相关（P<0.05,FDR多重校正）。结论 mTLE表现为默认网络及感觉运动区的功能连接异常;这些区域功能异常可能与mTLE的病理生理机制有关。     

内侧颞叶癫痫自我参照加工受损的功能磁共振成像

目的 采用功能磁共振成像(fMRI)技术对内侧颞叶癫痫(mTLE)患者的自我参照功能受损状况进行评价。方法 12例伴有海马硬化的mTLE患者及15名健康志愿者纳入本研究。采用内向诱导与外向诱导任务,以内向诱导任务为刺激状态、外向诱导任务为控制状态,收集fMRI数据,观察mTLE患者自我参照加工相关脑区反应的改变。结果 与健康志愿者相比,mTLE患者的内侧前额叶、扣带回前部及后部等与自我参照加工相关的区域活动明显降低(P＜0.01)。结论 mTLE患者以内侧前额叶为主的自我参照加工脑区活动降低,反映其与自我参照加工相关的高级脑认知功能损伤,是mTLE患者异常影像表现的病理生理学基础。     

脑灌注磁共振成像观察内侧颞叶癫痫部分及继发全面发作

目的观察部分及继发全面发作内侧颞叶癫痫(mTLE)患者脑区灌注的差异,分析在继发全面发作中起作用的相关脑区,探讨继发全面发作的mTLE网络的相关脑区。方法选取51例mTLE患者,其中16例部分发作(PS组),35例部分发作继发全面发作(sGS组)。利用3.0T MR脉冲式动脉自旋标记(PASL)序列采集两组患者发作间期脑血流量(CBF)数据。采用体素依赖统计分析(VBA)技术对两组患者脑灌注存在差异的脑区进行评价;并基于此选取患侧颞叶、丘脑及额叶等区域作为ROI,分别评价两组患者各ROI间的CBF的相关性。结果与PS组相比(校正后,P<0.05),sGS组患者表现为发作间期患侧丘脑、基底核及部分默认模式网络区域如双侧楔前叶、前扣带回、后扣带回、内侧前额叶等CBF降低;sGS组患者患侧颞叶与额叶(r=0.50,P<0.05)、丘脑与额叶(r=0.36,P<0.05)的CBF均有明显相关性。结论丘脑在继发全面发作的癫痫活动传播中起重要作用;癫痫活动通过特定网络传播到远处脑区。部分发作继发全面发作mTLE患者相比部分性发作患者部分脑区功能受损更严重。     

联合脑电功能MRI观察颞叶癫痫脑活动局域的一致性改变

目的 探讨颞叶癫痫患者功能MRI(fMRI)局域一致性(ReHo)改变的癫痫电活动基础。方法 对6例单侧颞叶癫痫患者行同步脑电图(EEG)-fMRI。另选取正常对照21名,采集fMRI数据。所有fMRI数据经处理后被分为42小段,分析每小段数据的ReHo值与该段数据时间内间期痫样发放次数的相关性。结果 与正常对照相比,mTLE患者右侧海马区域、右侧颞叶及双侧顶叶ReHo值明显增高。体素依赖分析结果显示,癫痫侧的内侧颞叶、丘脑及脑干等部位ReHo值与间期痫样发放次数呈正相关,其中内侧颞叶处相关性较高(r=0.36, P<0.02)。结论 癫痫电活动发放是ReHo值升高的主要生理基础,为基于ReHo分析的fMRI在癫痫活动检测方面的应用提供了生物学证据。     

间期痫样发放对内侧颞叶癫痫脑网络的影响

目的探讨间期痫样发放对内侧颞叶癫痫患者脑静息态网络的影响,揭示间期癫痫活动发放对全脑功能的损害机制。材料与方法从45例行同步脑电f MRI数据采集单侧颞叶癫痫患者中,挑选35例(左侧颞叶癫痫患者18例、右侧颞叶癫痫患者17例),以同步脑电图监测,每一患者均采集间期痫样发放及无痫样发放状态静息态f MRI数据。采用独立成分分析方法,分别提取患者两种状态的核心网络、背侧注意网络、执行控制网络、默认网络及感觉运动网络等7套内在连接网络。采用配对t检验比较痫样发放及无痫样发放状态m TLE患者脑内在连接网络的差异。结果相比未发放状态,发放状态下颞叶癫痫患者核心网络的前扣带回功能连接增强,听觉网络的脑岛及颞上回功能连接减低。此外,背侧注意网络的顶上小叶在左侧颞叶癫痫患者表现为功能连接增强,而在右侧表现为连接减弱。前默认网络的额中回在右侧表现为功能连接减弱,而后默认网络颞中回及后扣带回在右侧表现为功能连接增强。执行控制网络的中扣带回和视觉网络枕叶皮层在左侧表现为功能连接增强。相关分析结果显示,左侧组视觉网络及右侧组听觉网络内连接强度的变化与发放状态下IEDs发放次数呈正相关。结论内侧颞叶癫痫发作间期痫样发放对脑高级认知网络及感知觉网络均产生了广泛影响,尤其是对参与脑高级认知功能网络的损害,这有助于进一步了解海马硬化这一特异性内侧颞叶癫痫在发作间期脑功能受损机制。     

人颞叶内侧癫痫海马组织星形胶质细胞水通道蛋白4和内向整流性钾离子通道4.1的再分布

目的研究人颞叶内侧癫痫海马组织星形胶质细胞水通道蛋白4(AQP4)和内向整流性钾离子通道4.1(Kir4.1)的分布。方法对10例颞叶内侧癫痫(MTLE)和6例非颞叶内侧癫痫(non-MTLE)手术切除海马组织,应用光镜及透射电镜观察组织学及超微结构,免疫荧光组织化学法观察星形胶质细胞AQP4和Kir4.1的分布。结果 MTLE海马组织星形胶质细胞大量增生伴明显肿胀,神经元显著固缩。non-MTLE海马组织中,AQP4和Kir4.1在星形胶质细胞血管周围足突(pAST-ef)分布多于其他部位,呈现极性分布特点;而在MTLE海马组织中,AQP4和Kir4.1在pAST-ef分布减少,其他部位分布增加,极性分布改变。结论海马组织星形胶质细胞上AQP4和Kir4.1极性分布变化可能与颞叶内侧癫痫发生相关。     

难治性颞叶内侧癫痫手术的术中配合及护理

癫痫是最常见的神经系统疾病之一。它是一种致残率高、临床反复发作、病程漫长的疾病。其中,颞叶癫痫分为颞叶内侧癫痫、病灶性颞叶癫痫和颞叶外侧新皮质癫痫。颞叶内侧癫痫主要起源于内侧结构杏仁核、海马、钩回、海马旁回,占颞叶癫痫90%以上的病例。普遍的临床实践已经证明,难治性颞叶内     

应用FAIR技术评价难治性和非难治性颞叶癫痫灌注异常

目的用FAIR技术评价难治性及非难治性颞叶癫痫患者发作间期rCBF异常的模式是否不同.方法 9例难治性颞叶癫痫、21例非难治性颞叶癫痫患者及13名正常志愿者,测量其双侧大脑半球及双侧内侧颞叶的rCBF,并计算不对称指数(AI).结果难治性及非难治性癫痫患者大脑半球AI值与正常对照组之间有统计学差异(P值分别为0.012和0.029);难治性颞叶癫痫患者内侧颞叶AI值与正常对照组之间无统计学差异(P＝0.102),而非难治性癫痫患者与正常对照组之间有统计学差异(P＝0.049).结论难治性和非难治性颞叶癫痫患者发作间期rCBF异常的模式有所不同,虽然均可出现较广泛的rCBF异常,但难治性癫痫更倾向于出现双侧内侧颞叶低灌注,这可为判断预后提供帮助.     

Cerebral perfusion changes in mesial temporal lobe epilepsy: SPM analysis of ictal and interictal SPECT

We examined cerebral perfusion changes in mesial temporal lobe epilepsy (mTLE) by the statistical parametric mapping of brain single photon emission computed tomography (SPECT) images of 38 mTLE patients and 19 normal controls. Ictal and interictal SPECTs were compared with control SPECTs by independent t test, and ictal and interictal SPECTs by paired t test. We evaluated the number of heterotopic neurons in temporal lobe white matter, white matter changes of the anterior temporal lobe (WCAT) and ictal hyperperfusion of the temporal stem (IHTS). Left mTLE showed interictal hypoperfusion in the ipsilateral hippocampus, bilateral thalami, and paracentral lobules. Right mTLE showed hypoperfusion in bilateral hippocampi, contralateral insula, bilateral thalami, and paracentral lobules. Both mTLEs showed ictal hyperperfusion in bilateral temporal lobes with ipsilateral predominance, and in the anterior frontal white matter bilaterally. By paired t test, ictal hyperperfusion was found in the ipsilateral temporal lobe, temporal stem, hippocampus, thalamus, putamen, insula, and bilateral precentral gyri, whereas ictal hypoperfusion was found in bilateral frontal poles and middle frontal gyri. Fifteen patients showed WCAT and 19 showed IHTS, a weak correlation was observed between WCAT and IHTS (r = 0.377, P = 0.02). WCAT was found to correlate with an early seizure onset age. In 35 patients, heterotopic neurons were found in the white matter of the resected temporal lobe, but the number of heterotopic neurons did not correlate with WCAT or IHTS. In summary, the cerebral perfusion patterns of mTLE suggest interictal hypofunction and ictal activation of the cortico-thalamo-hippocampal-insular network and ictal hypoperfusion of the anterior frontal cortex.     

Voxel-based diffusion tensor imaging in patients with mesial temporal lobe epilepsy and hippocampal sclerosis

BACKGROUND: Mesial temporal lobe epilepsy (mTLE) with hippocampus sclerosis (HS) is an important cause for focal epilepsy. In this study, we explored the integrity of connecting networks using diffusion tensor imaging (DTI) and two whole-brain voxel-based methods: statistical parametric mapping (SPM) and tract-based spatial statistics (TBSS). METHODS: Thirty-three consecutive patients with mTLE and HS undergoing presurgical evaluation were scanned at 3 T, a DTI data set was acquired and parametric maps of fractional anisotropy (FA) and mean diffusivity (MD) were calculated. Twenty-one patients had left hippocampal sclerosis (LHS) and 12 patients had right HS (RHS). These groups were compared to 37 normal control subjects using both SPM5 and TBSS. RESULTS: The ipsilateral temporal lobe showed widespread FA reduction in both groups. The limbic system was clearly abnormal in the LHS group, also involving the arcuate fasciculus. In RHS, changes were more restricted but also showed involvement of the contralateral temporal and inferior frontal lobe. Increased MD was found in the ipsilateral hippocampus by SPM that was only marginally detected by TBSS. In white matter regions, however, TBSS was more sensitive to changes than SPM. CONCLUSION: DTI detects extensive changes in mTLE with HS. The affected networks were principally in the ipsilateral temporal lobe and the limbic system but also the arcuate fasciculus. SPM and TBSS gave complementary information with higher sensitivity to FA changes using TBSS.     

Automated MR image classification in temporal lobe epilepsy

In those with drug refractory focal epilepsy, MR imaging is important for identifying structural causes of seizures that may be amenable to surgical treatment. In up to 25% of potential surgical candidates, however, MRI is reported as unremarkable even when employing epilepsy specific sequences. Automated MRI classification is a desirable tool to augment the interpretation of images, especially when changes are subtle or distributed and may be missed on visual inspection. Support vector machines (SVM) have recently been described to be useful for voxel-based MR image classification. In the present study we sought to evaluate whether this method is feasible in temporal lobe epilepsy, with adequate accuracy.We studied 38 patients with hippocampal sclerosis and unilateral (mesial) temporal lobe epilepsy (mTLE) (20 left) undergoing presurgical evaluation and 22 neurologically normal control subjects. 3D T1-weighted images were acquired at 3T (GE Excite), segmented into tissue classes, normalized and smoothed with SPM8. Diffusion tensor imaging (DTI) and double echo images for T2 relaxometry were also acquired and processed. The SVM analysis was done with the libsvm software package in a leave-one-out cross-validation design and predictive accuracy was measured. Local weighting was applied by SPM F-contrast maps.Best accuracies were achieved using the gray matter based segmentation (90-100%) and mean diffusivity (95-97%). For the three-way classification, accuracies were 88 and 93% respectively. Local weighting generally improved the accuracies except in the FA-based processing for which no effect was noted. Removing the hippocampus from the analysis, on the other hand, reduced the obtainable diagnostic indices but these were still > 90% for DTI-based methods and lateralization based on gray matter maps. These findings show that automated SVM image classification can achieve high diagnostic accuracy in mTLE and that voxel-based MRI can be used at the individual subject level. This could be helpful for screening assessments of MRI scans in patients with epilepsy and when no lesion is detected on visual evaluation.