Identifying juvenile myoclonic epilepsy via diffusion tensor imaging using machine learning analysis

The aim of this study was to evaluate the feasibility of using a machine learning approach based on diffusion tensor imaging (DTI) to identify patients with juvenile myoclonic epilepsy. We analyzed the usefulness of combining conventional DTI measures and structural connectomic profiles. This retrospective study was conducted at a tertiary hospital. We enrolled 55 patients with juvenile myoclonic epilepsy. All of the subjects underwent DTI from January 2017 to March 2020. We also enrolled 58 healthy subjects as a normal control group. We extracted conventional DTI measures and structural connectomic DTI profiles. We employed the support vector machines (SVM) algorithm to classify patients with juvenile myoclonic epilepsy and healthy subjects based on the conventional DTI measures and structural connectomic profiles. The SVM classifier based on conventional DTI measures had an accuracy of 68.1% and an area under the curve (AUC) of 0.682. Another SVM classifier based on the structural connectomic profiles demonstrated an accuracy of 72.7% and an AUC of 0.727. The SVM classifier based on combining the conventional DTI measures and structural connectomic profiles had an accuracy of 81.8% and an AUC of 0.818. DTI using machine learning is useful for classifying patients with juvenile myoclonic epilepsy and healthy subjects. Combining both the conventional DTI measures and structural connectomic profiles results in a better classification performance than using conventional DTI measures or the structural connectomic profiles alone to identify juvenile myoclonic epilepsy.     

颞叶内侧结构弥散张量成像及白质纤维束成像在颞叶癫痫诊断中的应用价值

目的 通过磁共振弥散张量成像(DTI)及白质纤维束示踪(DTT)技术定量分析颞叶癫痫患者双侧颞叶内侧结构弥散参数值及局部纤维束变化特点,评价DTI技术对颞叶癫痫的诊断价值.方法 对广州医学院第二附属医院自2010年12月至2011年2月临床诊断为颞叶癫痫的16例患者和20例健康志愿者进行常规MRI及DTI扫描,测量双侧颞叶杏仁体、海马及颞叶皮质的部分各向异性(FA)、相对各向异性(RA)、表观弥散系数(ADC)等数值并进行统计学分析,同时应用DTT技术观察癫痫患者局部纤维束与正常对照者的差异.结果 正常对照者双侧颞叶内侧各结构FA、RA、ADC值比较差异均无统计学意义(P＞0.05).颞叶癫痫患侧、对侧与正常对照者颞叶内侧各结构FA、RA、ADC值比较差异均有统计学意义(P＜0.05),其中ADC值呈颞叶癫痫患侧＞颞叶癫痫对侧＞正常对照者的变化趋势,以海马尾部变化最为显著;而FA、RA值呈颞叶癫痫患侧＜颞叶癫痫对侧＜正常对照者的变化趋势,并且杏仁体、海马体部变化较海马尾部更显著.结论 DTI技术能充分了解癫痫患者颞叶内侧结构的弥散参数值及纤维束变化特点,有助于癫痫病灶定位的准确诊断,同时加深对颞叶内侧结构整体变化的了解亦有助于术前的整体评估及提高手术疗效.     

Abnormalities in diffusion tensor imaging of the uncinate fasciculus relate to reduced memory in temporal lobe epilepsy

Aims: To use Diffusion Tensor Imaging (DTI) to explore structural integrity and connectivity of the uncinate fasciculus (UF) in patients with temporal lobe epilepsy (TLE) and its relationship to memory performance.
Methods: DTI and UF reconstruction were performed in 28 patients with TLE (18 left, 10 right) and 10 normal controls. Differences between left and right UF fractional anisotropy (FA) and apparent diffusion coefficient (ADC) values and correlations between DTI measures and memory scores in the TLE groups were computed.
Results: In controls, FA was higher in the left than right UF (p < 0.01). In left TLE, FA values were lower and ADC values higher than controls in the left UF and ADC values were higher in the right UF (all p < 0.05). In right TLE, ADCs were higher in the left and right UF compared to controls, and FA was reduced in the left UF (all p < 0.05). In left TLE, ADCs in the left UF were negatively correlated with Auditory Immediate (p < 0.05) and Delayed Memory (p < 0.01). Visual Delayed Memory was positively correlated with reduced FA in the ROI of the right UF and increased radial diffusivities (p < 0.05). No significant correlations were found in right TLE. Thus, DTI values correlated with memory scores in the expected direction in patients with left TLE.
Conclusions: Abnormal diffusion measures in the UF ipsilateral to the epileptogenic zone suggest that integrity of the UF is related to memory performance in patients with left TLE. Larger sample sizes are needed to evaluate structure-function correlations further.     

Extratemporal white matter abnormalities in mesial temporal lobe epilepsy demonstrated with diffusion tensor imaging

PURPOSE: Recent studies have demonstrated bilateral white matter abnormalities in temporal lobe epilepsy (TLE) patients with unilateral mesial temporal sclerosis (MTS). The purpose of this project was to determine whether abnormalities of water diffusion are seen in extratemporal white matter of patients with TLE and pathologically confirmed MTS and to determine whether these findings are associated with worse surgical outcome. METHODS: Eleven patients with TLE and unilateral MTS confirmed in surgical specimens and 14 controls were studied by using cerebrospinal fluid-suppressed diffusion tensor imaging (DTI) and T2 relaxometry. RESULTS: Hippocampal T2 signal for patients was significantly elevated both ipsilateral (p<0.001) and contralateral (p=0.006) to MTS. DTI demonstrated reduced fractional anisotropy of the genu of the corpus callosum (p=0.003) and external capsule (p=0.02) and elevated mean diffusivity of the genu (p=0.005), splenium (p=0.03), and external capsule (p<0.001). For both the genu and external capsule, parallel diffusion of patients was not different from that of controls (genu, p=0.81; external capsule, p=0.45), whereas perpendicular diffusion was elevated (genu, p=0.001; external capsule, p<0.001). With mean postsurgical follow-up of 18.5 months, eight of 11 patients were entirely seizure free and the remaining three had all experienced a worthwhile reduction in seizure frequency. CONCLUSIONS: Our findings suggest that although patients with TLE and MTS have extensive bilateral and extratemporal pathology, these findings may not be associated with a worse postsurgical outcome.     

Diffusion tensor imaging in late posttraumatic epilepsy

PURPOSE: The main objective of this study was to use diffusion tensor imaging (DTI) to search and quantify the extent of abnormality beyond the obvious lesions seen on the T2 and fluid-attenuation inversion recovery (FLAIR) magnetic resonance images in patients with chronic traumatic brain injury (TBI) with and without epilepsy. METHODS: DTI was performed on 23 chronic TBI patients (with late posttraumatic epilepsy, n=14; without epilepsy, n=9) and 11 age-matched controls. The ratios of fractional anisotropy (FA) and mean diffusivity (MD) between the regions of interest beyond the T2/FLAIR-visualized abnormality and the corresponding contralateral normal-appearing region were calculated. FA and MD ratios were compared for relative changes in these parameters among the TBI subjects with and without epilepsy and controls. Tissue volumes exhibiting abnormalities on DTI also were measured in these patients. RESULTS: The mean regional FA ratio was significantly lower, whereas the mean regional MD value was higher in patients with TBI compared with controls. The mean regional FA ratio was significantly lower in TBI patients with epilepsy (0.57+/-0.059) than in those without epilepsy (0.68+/-0.039). Although the regional MD ratio was higher in TBI patients with epilepsy (1.15+/-0.140) relative to those without epilepsy (1.09+/-0.141), the difference did not reach statistical significance. The tissue volume with low FA value also was found to be higher in TBI patients with epilepsy than without. CONCLUSIONS: Severity of injury as predicted by the DTI-derived increased volume of microstructure damage is associated with delayed posttraumatic epilepsy in TBI patients. These findings could be valuable in predicting epileptogenesis in patients with chronic TBI.     

Postoperative axonal changes in the contralateral hemisphere in children with medically refractory epilepsy: A longitudinal diffusion tensor imaging connectome analysis

To determine brain plasticity changes due to resective epilepsy surgery in children, we performed a longitudinal connectome analysis on the pattern of axonal connectivity in the contralateral hemisphere. Pre‐ and postoperative diffusion tensor imaging (DTI) data were acquired from 35 children with intractable focal epilepsy. A total of 54 brain regions of interest (ROIs) were generated in the hemisphere contralateral to the resection. Within a 54 × 54 connectivity matrix, a pairwise connectivity score was calculated for each connection between two ROIs, based on the DTI fiber streamline number in each connection. A permuted Spearman's ρ‐rank analysis was used to identify specific inter‐regional connections showing a significant association between the postoperative change of connectivity score and clinical variables. Nineteen connections in the contralateral hemisphere showed postoperative increases in the strength of connectivity. Postoperative increase in connectivity between insular–inferior frontal operculum regions as well as that between superior frontal orbital and mid frontal orbital regions were both significantly associated with a larger surgical resection volume (ρ > +0.40) and a younger patient age (ρ > ?0.34). These increases were more robust in patients with frontal resection and in those achieving seizure freedom. Neuropsychological evaluation on subsets of patients revealed that such increases in connectivity were associated with preserved or improved cognitive functions such as visual memory and planning. Resective epilepsy surgery may lead to increased contralateral axonal connectivity in children with focal epilepsy. Our data lead to a hypothesis that such increased connectivity may be an imaging marker of postoperative brain plasticity to compensate for cognitive function. Hum Brain Mapp 37:3946–3956, 2016. © 2016 Wiley Periodicals, Inc.     

室管膜下型灰质异位脑纤维结构连接的MR弥散张量成像研究

目的观察室管膜下型灰质异位（PNH）所发出白质纤维束的空间分布形式以及与正常脑组织的空间位置关系。方法8例以癫痫症状就诊的PNH患者经3．0T磁共振仪T1及T：加权成像诊断,并采集弥散张量成像数据。采用白质纤维束追踪技术,以异位灰质团块作为种子点,对异位灰质相连的白质纤维束进行描绘,并观察总结其空间分布模式及与其他大脑结构之间的关系。结果异位灰质白质纤维束有以下分布特点：①异位灰质均能发出自身的白质纤维,其中有4例表现为仅与位于同侧大脑半球的长联络纤维连接;3例除联络纤维外,还可见到其白质纤维参与对侧的胼胝体连接;6例可见到连接至皮层的弓状纤维;②结构连接空间模式与灰质异位所处位置有关,位于侧脑室前角旁的异位灰质发出的联络纤维主要分布于前方,位于侧脑室后角旁的异位灰质发出的联络纤维主要分布于后方,靠近胼胝体的异位灰质其自质纤维较易连接到对侧,靠近皮层的异位灰质较易发出弓状纤维与皮层相连。结论异位灰质不是孤立的结构,其可发出或长或短的白质纤维,并较广泛地与正常脑结构保持连接;其纤维连接分布的空间模式与异位灰质所处的位置有关。     

前颞叶切除范围与视野缺损关系的弥散张量成像分析

目的 观察颞叶癫痫患者前颞叶切除术后视野缺损的发生率以及手术切除范围与视野缺损的关系.方法 25例前颞叶切除术的患者于术前及随访时行视野、磁共振(含DTI弥散张量序列)检查,根据视野缺损严重程度的不同将患者分为A、B、C三级.手术后视放射的各向异性分数(FA值)的下降(△FA)代表Meyer袢受损情况.比较不同视野缺损组之间前颞叶切除范围的差异;并对切除范围和△FA进行线性相关分析.结果 前颞叶切除术后22例患者出现象限盲.前颞叶平均切除长度:A组31.1 mm,B组42.5 mm,C组50.4 mm,A＜B＜C组(P＜0.05).手术侧的△FA与切除范围旱线性相关.结论 前颞叶切除术破坏视放射导致视野缺损较常见.有必要术前应用DTI获得患者视放射的信息,进行术前风险评估.

Abstract：

Objective Anterior temporal lobectomy(ATL) for temporal lobe epilepsy (TLE) is the most commonly performed epilepsy surgery procedure.A visual field defect(VFD) due to the injury to the optic radiation may occur after ATL.DTI technique can visualize the optic radiation (OR) noninvasively.This study aimed at evaluating the incidence of VFD after ATL and investigating whether the resection size of lateral ATL correlated with the extent of VFD.We tried to explain the impact of ATL on the OR and to investigate the anterior extending of Meyer loop with DTI technology.Method 25 patients( 14male, 11 female) underwent ATL for treatment of epilepsy.The patients were aged from 13 to 39 years old ( mean age:22.4 yrs).All cases were classified into three groups on the basis of the severity of VFD( A ～ C,with group C the most severe).All patients had preoperative and follow up clinical and MRI( including DTI series) examinations.The clinical and MRI(DTI) outcomes of these patients were retrospectively analyzed.Results At mean follow up period of 31.3 weeks ( range, 17 - 42 weeks), we found 22 patients become quadrantanopia due to the injury to OR after ATL.A significant reduction of fractional anisotropy was demonstrated in the OR on the side of the temporal lobectomy.The severity of VFD decreased according to the reducing of the mean resection size(group A, 31.1 mm;group B 42.5 mm;C, 50.4 mm), P ＜0.05.There was linearship between the resection size and the FA decrease.Conclusions VFD due to the injury to the OR was not uncommon after ATL There was an association between the resection size and severity of VFD.Optic radiation showed a decreased FA value in cases after ATL.There is considerable intersubjective variance about the OR, so it is necessary to get the patient's DTI information about the OR before the operation ,which could help to assess the preoperative risks.     

Group‐specific regional white matter abnormality revealed in diffusion tensor imaging of medial temporal lobe epilepsy without hippocampal sclerosis

Purpose: In comparison to temporal lobe epilepsy (TLE) patients with hippocampal sclerosis (TLE‐HS), TLE patients without HS (TLE‐NH) have a similar clinical course but may result in worse surgical outcome. We investigated whether the clinical features related to the lack of HS in TLE patients (TLE‐NH) can be explained by water diffusion abnormalities throughout diffusion tensor imaging (DTI) by voxel‐based analysis. Methods: Nineteen patients with TLE‐HS (left/right TLE 12:7), 18 patients with TLE‐NH (left/right TLE 10:8), and 20 controls were included in the study. By statistical parametric mapping (SPM2), the diffusion properties specific to disease characteristics (TLE‐HS vs. TLE‐NH) were analyzed. Results: In TLE‐HS, we found the areas of increased mean diffusivity (MD) in their ipsilateral temporal and extratemporal areas including the hippocampus, parahippocampal, and frontoparietal regions. Left TLE‐HS showed a characteristic MD increase in the ipsilateral posterior cingulum, isthmus of corpus callosum, and contralateral occipital and temporal regions, which was not observed in right TLE‐HS group. In left TLE‐NH, two regions of increased MD were observed in the ipsilateral posterior fornix (within fusiform gyrus) and posterior cingulum. Right TLE‐NH did not show any increased MD. Discussion: In left TLE‐NH, we could find the water diffusion change along the posterior cingulum, which was quite different from the extensive abnormality from TLE‐HS. In addition, there was a lesion‐side–specific distribution (left predominant) of pathology in mesial TLE. This provides a possibility that TLE‐NH is a heterogenous or entity different from TLE‐HS.     

弥散张量成像（DTI）在颅脑高级别胶质瘤中的应用初探

目的：初步探讨磁共振弥散张量成像（DTI）在颅脑高级别胶质瘤中的应用价值。方法：收集经手术病理证实高级别胶质瘤13例,均作了常规MRI平扫、增强扫描以及DTI,经计算机后处理获得平均弥散系数图（MD图）及部分各向异性指数图（FA图）,测定肿瘤实质区、囊变坏死区、瘤周水肿区及正常白质区的MD值、FA值,分析比较上述4个区MD值、FA值有无统计学差异。结果：肿瘤实质区、囊变坏死区、瘤周水肿区及正常白质区的MD值分别为0.976±0.171×10^-9mm^2/s、1.92±0.515×10^-9mm^2/s、1.414±0.288×10^-9mm^2/s、0.723±0.0525×10^-9mm^2/s,上述4个区域两两比较均有显著统计学差异（P〈0.01）;肿瘤实质区、囊变坏死区、瘤周水肿区及正常白质区的FA值分别为0.137±0.056、0.0824±0.061、0.148±0.09、0.522±0.073,囊变坏死区、肿瘤实质区、瘤周水肿区与正常白质区比较均有显著统计学差异（P〈0.001）,而囊变坏死区、肿瘤实质区及瘤周水肿区之间均无统计学差异（P〉0.05）。结论：DTIMD值可区分高级别胶质瘤肿瘤实质区、囊变坏死区、瘤周水肿区及正常白质区;FA值可区分肿瘤区与正常白质区,但不易区分肿瘤实质区、囊变坏死区与瘤周水肿区。     

颞叶癫痫患者磁共振弥散张量成像及记忆损害的研究

目的利用磁共振弥散张量成像技术(DTI)研究颞叶癫痫(TLE)患者脑内微观改变及记忆损害的相关脑区。方法对颞叶癫痫患者15例和健康对照者15例,进行DTI检查,利用韦氏记忆量表检测记忆功能。结果 TLE患者部分各向异性弥散(FA)值降低激活区域有颞叶、边缘叶、扣带回和岛叶,升高区有:额叶、顶叶、枕叶,表观系数(ADC)值升高激活区域在颞叶、额叶、枕叶、顶叶;无ADC值降低区域。与健康者相比,颞叶癫痫患者的记忆商数(MQ)(90.73±19.72)显著下降,P<0.01。对照组FA值在左岛叶、颞叶与MQ值正相关;患者组FA值在右额、顶、枕叶、左顶叶与MQ值正相关,在左颞叶与MQ值负相关。对照组ADC与MQ正相关区域在左边缘叶,与MQ成负相关区域在左顶叶、患者组正相关区域在左、右颞叶。结论初步证实TLE患者的脑内结构变化不局限于颞叶,还包括颞叶外网络结构;TLE患者全脑DTI与MQ存在着相关激活脑区,表明记忆功能损害与脑内相关结构改变有关。     

A meta-analysis of white matter changes in temporal lobe epilepsy as studied with diffusion tensor imaging

Purpose: Diffusion tensor imaging (DTI) is used increasingly to study white matter integrity in people with temporal lobe epilepsy (TLE). Most studies report fractional anisotropy (FA) decrease and mean diffusivity (MD) increase in multiple white matter regions. The disturbance of white matter integrity varies across studies and between regions. We aimed to obtain a more consistent estimate of white matter diffusion characteristics and relate these to the distance from the seizure focus. Methods: Studies comparing diffusion characteristics of people with epilepsy with those of healthy controls were systematically reviewed and quantified using random and mixed effects meta analysis. In addition to the overall meta‐analysis, pooled FA and MD differences were determined per hemisphere and white matter category separately. Key Findings: We included 13 cross‐sectional studies. The pooled FA difference for all white matter was ?0.026 (95% confidence interval [CI] ?0.033 to ?0.019) and MD difference was 0.028 × 10^?3 mm²/s (95% CI 0.015–0.04). FA was reduced significantly in people with TLE compared with healthy controls in both ipsilateral (mean difference ?0.03) and contralateral white matter (?0.02). MD was significantly increased ipsilaterally and contralaterally. MD differed significantly between white matter connected to the affected temporal lobe and remote white matter. Significance: The meta‐analysis provides a better estimation of the true diffusion characteristics. White matter structural integrity in TLE is disturbed more severely in the ipsilateral than in the contralateral hemisphere, and tracts closely connected with the affected temporal lobe are most disturbed. The exact underlying mechanisms remain to be elucidated.     

Contralateral MRI abnormalities in candidates for hemispherectomy for refractory epilepsy

Purpose: To assess the impact of contralateral magnetic resonance imaging (MRI) findings on seizure outcome after hemispherectomy for refractory epilepsy. Methods: We retrospectively reviewed 110 children, 0.4–18 (median 5.9) years of age, who underwent hemispherectomy for severe refractory epilepsy at Cleveland Clinic Children’s Hospital. In children with contralateral (as well as ipsilateral) MRI findings appreciated preoperatively, the decision to proceed to surgery was based on other features concordant with the side with the most severe MRI abnormality, including ipsilateral epileptiform discharges, lateralizing seizure semiology, and side of hemiparesis. Results: We retrospectively observed contralateral MRI abnormalities (predominantly small hemisphere, white matter loss or abnormal signal, or sulcation abnormalities) in 81 patients (74%), including 31 of 43 (72%) with malformations of cortical development (MCD), 31 of 42 (73%) with perinatal injury from infarction or hypoxia, and 15 of 25 (60%) with Rasmussen’s encephalitis, Sturge‐Weber syndrome, or posttraumatic encephalomalacia. Among 84 children (76%) with lesions that were congenital or acquired pre‐ or perinatally, 67 (83%) had contralateral MRI abnormalities (p = 0.02). Contralateral findings were subjectively judged to be mild or moderate in 70 (86%). At follow‐up 12–84 (median 24) months after surgery, 79% of patients with contralateral MRI abnormalities were seizure‐free compared to 83% of patients without contralateral MRI findings, with no differences based on etiology group or type or severity of contralateral MRI abnormality. Discussion: MRI abnormalities, usually mild to moderate in severity, were seen in the contralateral hemisphere in the majority of children who underwent hemispherectomy for refractory epilepsy due to various etiologies, especially those that were congenital or early acquired. The contralateral MRI findings, always much less prominent than those in the ipsilateral hemisphere, did not correlate with seizure outcome and may not contraindicate hemispherectomy in otherwise favorable candidates.     

The utility of diffusion tensor imaging tractography for post-operative evaluation of a patient with hemispherotomy performed for intractable epilepsy

Hemispherotomy is an effective treatment for patients with severe epilepsy caused by hemispheric abnormalities such as hemimegalencephaly or other dysplastic malformations. Here, we report a 5-year-old boy who experienced right-side hemiconvulsion due to left hemispheric cortical dysplasia. He presented with mild right hemiparesis that had been present since seizure onset. Ictal electroencephalogram obtained during the hemiconvulsion showed localized epileptic discharges in the left hemisphere. He underwent a left peri-insular hemispherotomy. Three months after surgery, clonic convulsions returned in the left leg and EEG-video monitoring showed localized epileptic discharges in the frontal region. Magnetic resonance images showed that the genu of corpus callosum was unsectioned and diffusion tensor imaging tractography confirmed the presence of callosal fibers in the genu of the corpus callosum. Clonic convulsion disappeared after additional section of the corpus callosum. Further studies are warranted to determine the utility of diffusion tensor imaging tractography on the assessment of subcortical fibers following disconnective epilepsy surgery.     

磁共振弥散张量成像在脑梗死中的应用

目的应用磁共振弥散张量成像(DTI)技术分析缺血性脑梗死不同时期的表观弥散系数(ADC)、各向异性分数(FA)变化,并通过弥散张量纤维束成像(DTT)观察梗死灶与皮质脊髓束(CST)位置关系,以评估预后。方法 45例由于皮质脊髓束受损所致运动功能障碍的不同时期脑梗死患者作为研究组,分为超急性期(<6h)、急性期(6h～3d)、亚急性期(4d～8w)和慢性期(>8w),分析其DTI参数的变化特点,并与正常组进行比较。结果患侧FA值在超急性期无明显变化,在急性期、亚急性期及慢性期逐渐降低,与健侧和对照组比较有显著性差异(P值均<0.05);患侧ADC值在超急性期、急性期明显减低,亚急性期逐渐恢复接近于健侧,慢性期再度增高;DTT成像显示CST受损严重其预后较差。结论不同时期脑梗死病灶其FA、ADC值有一定规律变化,DTT图像可无创性的显示梗死灶与皮质脊髓束的空间位置关系,可作为评估预后的客观依据。     

弥散张量成像在继发全面性发作癫痫患者中的应用研究

目的 评价弥散张量成像(DTI)对于常规MRI未发现病灶的部分性继发全面性发作癫痫患者的病灶检出能力.方法 使用Siemens 3.0T磁共振成像系统对30例成年继发全面性发作癫痫患者和30例正常对照者进行扫描,得到弥散加权成像,采用基于体素的分析方法对癫痫患者和正常对照组的数据进行分析.结果 癫痫组右侧梭状回和楔前叶、右侧额内侧回和钩回、左侧扣带回、左侧颞下回、左侧小脑扁桃体和左侧中央前回的脑区FA值较正常对照组降低,差异有统计学意义(P＜0.001);癫痫组右侧海马旁回、右侧颞下回、右侧胼胝体、右侧额内侧回、右侧额下回、扣带回、右侧前扣带回、右侧舌回、右侧梭状回和枕中回,左侧颞中回、左侧钩回和左侧中央前回的脑区ADC值较正常对照组升高,差异具有统计学意义(P＜0.001);左侧直回的脑区ADC值较正常对照组降低,差异具有统计学意义(P＜0.001).结论 DTI检查可发现常规MRI检查为阴性的部分性继发全面性发作癫痫患者存在的广泛脑白质微结构异常.     

Diffusion tensor analysis of temporal and extra-temporal lobe tracts in temporal lobe epilepsy

OBJECTIVE: To determine whether the major temporal lobe white matter tracts in patients with temporal lobe epilepsy manifest abnormal water diffusion properties. METHODS: Diffusion tensor MRI measurements were obtained from tractography for uncinate, arcuate, inferior longitudinal fasciculi and corticospinal tract in 13 children with left temporal lobe epilepsy and normal conventional MRI, and the data were compared to measurements in 12 age-matched normal volunteers. The relationship between tensor parameters and duration of epilepsy was also determined. RESULTS: All four tracts in the affected left hemisphere showed lower mean anisotropy, planar and linear indices, but higher spherical index in patients versus controls. Diffusion changes in the left uncinate and arcuate fasciculus correlated significantly with duration of epilepsy. Arcuate fasciculus showed a reversal of the normal left-right asymmetry. Various diffusion abnormalities were also seen in the four tracts studied in the right hemisphere. CONCLUSION: Our findings indicate abnormal water diffusion in temporal lobe and extra-temporal lobe tracts with robust changes in the direction perpendicular to the axons. Diffusion abnormalities associated with duration of epilepsy suggest progressive changes in ipsilateral uncinate and arcuate fasciculus due to chronic seizure activity. Finally, our results in arcuate fasciculus are consistent with language reorganization to the contralateral right hemisphere.     

In vivo diffusion tensor imaging and ex vivo histologic characterization of white matter pathology in a post-status epilepticus model of temporal lobe epilepsy

Although epilepsy is historically considered a disease of gray matter, recent diffusion tensor imaging (DTI) studies have shown white matter abnormalities in patients with epilepsy. The histopathologic correlate of these findings, and whether they are a cause or consequence of epilepsy, remains unclear. To characterize these changes and their underlying histopathology, DTI was performed in juvenile rats, 4 and 8 weeks after pilocarpine‐induced status epilepticus (SE). In the medial corpus callosum (CC), mean diffusivity and axial diffusivity (MD and λ₁) as well as a myelin staining were significantly reduced at 4 weeks. Only the λ₁ decrease persisted at 8 weeks. In the fornix fimbriae (FF), λ₁ and myelin staining were decreased at both time points, whereas fractional anisotropy (FA) and MD were significantly reduced at 8 weeks only. We conclude that SE induces both transient and chronic white matter changes in the medial CC and FF that are to some degree related to myelin pathology.     

Revisiting the role of the insula in refractory partial epilepsy

Purpose:   Recent evidence suggesting that some epilepsy surgery failures could be related to unrecognized insular epilepsy have led us to lower our threshold to sample the insula with intracerebral electrodes. In this study, we report our experience resulting from this change in strategy.
Methods:   During the period extending from October 2004 to June 2007, 18 patients had an intracranial study including 10 with insular coverage. The decision to sample the insula with intracerebral electrodes was made in the context of (1) nonlesional parietal lobe-like epilepsy; (2) nonlesional frontal lobe-like epilepsy; (3) nonlesional temporal lobe-like epilepsy; and (4) atypical temporal lobe-like epilepsy.
Results:   Intracerebral recordings confirmed the presence of insular lobe seizures in four patients. Cortical stimulation performed in 9 of 10 patients with insular electrodes elicited, in decreasing order of frequency, somatosensory, viscerosensory, motor, auditory, vestibular, and speech symptoms.
Discussion:   Our results suggest that insular cortex epilepsy may mimic temporal, frontal, and parietal lobe epilepsies and that a nonnegligeable proportion of surgical candidates with drug-resistant epilepsy have an epileptogenic zone that involves the insula.