Structural and functional asymmetry of medial temporal subregions in unilateral temporal lobe epilepsy: A 7T MRI study

Mesial temporal lobe epilepsy (TLE) is a common neurological disorder affecting the hippocampus and surrounding medial temporal lobe (MTL). Although prior studies have analyzed whole‐brain network distortions in TLE patients, the functional network architecture of the MTL at the subregion level has not been examined. In this study, we utilized high‐resolution 7T T2‐weighted magnetic resonance imaging (MRI) and resting‐state BOLD‐fMRI to characterize volumetric asymmetry and functional network asymmetry of MTL subregions in unilateral medically refractory TLE patients and healthy controls. We subdivided the TLE group into mesial temporal sclerosis patients (TLE‐MTS) and MRI‐negative nonlesional patients (TLE‐NL). Using an automated multi‐atlas segmentation pipeline, we delineated 10 MTL subregions per hemisphere for each subject. We found significantly different patterns of volumetric asymmetry between the two groups, with TLE‐MTS exhibiting volumetric asymmetry corresponding to decreased volumes ipsilaterally in all hippocampal subfields, and TLE‐NL exhibiting no significant volumetric asymmetries other than a mild decrease in whole‐hippocampal volume ipsilaterally. We also found significantly different patterns of functional network asymmetry in the CA1 subfield and whole hippocampus, with TLE‐NL patients exhibiting asymmetry corresponding to increased connectivity ipsilaterally and TLE‐MTS patients exhibiting asymmetry corresponding to decreased connectivity ipsilaterally. Our findings provide initial evidence that functional neuroimaging‐based network properties within the MTL can distinguish between TLE subtypes. High‐resolution MRI has potential to improve localization of underlying brain network disruptions in TLE patients who are candidates for surgical resection.     

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 temporal lobe epilepsy

Although mesial temporal sclerosis (MTS) has long been recognized in association with temporal lobe epilepsy (TLE), there is a growing body of literature suggesting structural abnormalities extending beyond the temporal lobe in patients with TLE. Diffusion tensor imaging (DTI) is a novel imaging technique that provides insight into the structural integrity of cerebral white matter. DTI studies have demonstrated extensive bilateral white matter abnormalities in TLE that extend far beyond the temporal lobe, even in patients with unilateral MTS. The relationship between white matter abnormalities, seizures, and comorbidity in TLE remains unclear.     

Altered white matter integrity in temporal lobe epilepsy: Association with cognitive and clinical profiles

Purpose: Diffusion tensor imaging (DTI) studies have reported substantial white matter abnormalities in patients with temporal lobe epilepsy (TLE). However, limited data exist regarding the extent of white matter tract abnormalities, cognitive effects of these abnormalities, and relationship to clinical factors. The current study examined these issues in subjects with chronic TLE. Methods: DTI data were obtained in 12 TLE subjects and 10 age‐matched healthy controls. Voxel‐wise statistical analysis of fractional anisotropy (FA) was carried out using tract‐based spatial statistics (TBSS). White matter integrity was correlated with cognitive performance and epilepsy‐related clinical parameters. Results: Subjects with TLE, as compared to healthy controls, demonstrated four clusters of reduced FA, in anterior temporal lobe, mesial temporal lobe, and cerebellum ipsilateral, as well as frontoparietal lobe contralateral to the side of seizure onset. Mean FA was positively correlated with delayed memory, in anterior temporal lobe; and immediate memory, in mesial temporal lobe. Lower FA values in the posterior region of corpus callosum were related to earlier age of seizure onset. Conclusion: TLE is associated with widespread disturbances in white matter tracts and these changes have important cognitive and clinical consequences.     

Hippocampal and thalamic diffusion abnormalities in children with temporal lobe epilepsy

PURPOSE: Previous studies using diffusion MRI in patients with temporal lobe epilepsy have shown abnormal water diffusion in the hippocampus. Because thalamus and lentiform nuclei are considered important for the regulation of cortical excitability and seizure propagation, we analyzed diffusion tensor imaging (DTI) abnormalities in these subcortical structures and in hippocampus of children with partial epilepsy with and without secondary generalization. METHODS: Fourteen children with partial epilepsy involving the temporal lobe underwent MRI including a DTI sequence. Fractional anisotropy (FA) and apparent diffusion coefficient (ADC) values were obtained in the hippocampus, thalamus, and lentiform nucleus, and compared with DTI data of 14 control children with no epilepsy, as well as glucose positron emission tomography (PET) findings. RESULTS: Decreased FA (p < 0.001) and increased ADC (p = 0.003) values were found in the hippocampi ipsilateral to the seizure focus. Significant FA decreases (p = 0.002) also were seen in the contralateral hippocampi, despite unilateral seizure onset and excellent surgical outcome in patients who underwent surgery. ADC values showed a trend for increase in the thalami ipsilateral to the epileptic focus in the seven children with secondarily generalized seizures (p = 0.09). No group differences of ADC or FA were found in the lentiform nuclei. The DTI variables did not correlate with regional glucose metabolism in any of the structures analyzed. CONCLUSIONS: Increased ADC values in hippocampus can assist in lateralizing the seizure focus, but decreased FA in the contralateral hippocampus suggests that it too may be dysfunctional despite unilateral seizure onset. Less-robust thalamic abnormalities of water diffusion in patients with secondarily generalized seizures suggest secondary involvement of the thalamus, perhaps due to recruitment of this structure into the epileptic network; however, this must be confirmed in a larger population. DTI appears to be a sensitive method for detection abnormalities in children with partial epilepsy, even in structures without apparent changes on conventional MRI.     

低频振幅算法功能磁共振成像对不同病因内侧颞叶癫癇的研究

目的研究不同病理基础内侧颞叶癫癇患者异常脑功能活动分布模式的差异,探讨异常活动脑区在内侧颞叶癫癇发病过程中的病理生理学机制。方法采用基于低频振幅（ALFF）的静息态f MRI技术,分别对30例单侧海马硬化性内侧颞叶癫癇（m TLE-HS）和30例单侧占位性内侧颞叶癫癇（m TLE-OL）患者进行研究,并与30例性别和年龄相匹配的正常对照者进行比较。经代价函数预处理图像后,REST软件计算全脑低频振幅均值并作归一化处理获得m ALFF值,两样本t检验依次对3组被试m ALFF值进行比较,对比m TLE-HS和m TLE-OL颞叶外脑区m ALFF值变化,并分析m ALFF值改变脑区与癫癇病程之间关联性。结果静息态下,m TLE-HS组和m TLE-OL组患者均呈现颞叶外m ALFF值改变,但异常脑区分布模式不同。与m TLE-HS组相比,m TLE-OL组患者m ALFF值增强区域位于双侧顶下叶、楔前叶、角回、扣带中后回和对侧颞中回;m ALFF值减弱区域为对侧中央后回、双侧枕中回和小脑（均P〈0.05,Alpha Sim校正）,提示m TLE-HS较m TLE-OL脑默认网络受抑制程度更为严重。m TLE-HS患者局部m ALFF值与癫癇病程无明显关联性,而m TLE-OL患者双侧扣带中后回m ALFF值与病程呈正相关（r=0.687,P=0.000）,双侧前扣带回与病程呈负相关（r=-0.621,P=0.000）。结论不同病理基础内侧颞叶癫癇存在不同的异常脑功能活动分布模式,提示二者潜在的病理生理学机制可能不同,验证了m TLE-HS是一种特异性癫癇类型。     

Entorhinal cortex MRI assessment in temporal,extratemporal, and idiopathic generalized epilepsy

PURPOSE: We previously showed a reduction in the volume of the entorhinal cortex (EC) ipsilateral to the seizure focus in patients with intractable temporal lobe epilepsy (TLE). The purpose of this study was to examine the specificity of EC atrophy in epilepsy. METHODS: We performed volumetric measurement of the EC on high-resolution magnetic resonance imaging (MRI) in patients with TLE (n = 70), extratemporal lobe epilepsy (ETE; n = 18), and idiopathic generalized epilepsy (IGE; n = 20). EC volumes of epilepsy patients were compared with those of 48 age- and sex-matched normal controls. Within the TLE group, 63 patients were selected prospectively with hippocampal atrophy ipsilateral to the seizure focus. The remaining seven patients were chosen retrospectively based on normal volumetric MRI of the hippocampus and amygdale, as well as normal histopathologic examination of the resected tissue. RESULTS: Compared with normal controls, EC volume was smaller ipsilateral but not contralateral to the seizure focus in patients with TLE (p < 0.001). No difference in the EC volumes ipsilateral and contralateral to the seizure focus was seen in patients with ETE and IGE compared with normal controls. The individual analysis showed that the EC was atrophic in 73% of TLE patients with hippocampal atrophy. Three of the seven TLE patients with normal volumetric MRI of the hippocampus and amygdala and normal histopathologic examination had EC atrophy ipsilateral to the seizure focus. In no patient with ETE or IGE was the EC found to be atrophic. CONCLUSIONS: EC atrophy ipsilateral to the seizure focus appears to be specific to mesial temporal lobe structural damage associated with TLE.     

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.     

Surgery for temporal lobe epilepsy after cerebral malaria

The most common indication for epilepsy surgery is temporal lobe epilepsy (TLE) which usually is divided into two categories, mesial and lateral TLE. The commonest pathology underlying mesial temporal lobe epilepsy (MTLE) is mesial temporal sclerosis (MTS); we report on a 50-year-old male patient, who contracted cerebral malaria and developed MTLE shortly thereafter. Magnetic resonance imaging (MRI) showed MTS. Surgical treatment was an anteromedial temporal lobe resection with amygdalohippocampectomy. The patient is seizure free, 36 months after surgical treatment. This is the first report describing MTLE-onset subsequent to cerebral malaria and discussing the potential pathophysiological relationship between cerebral malaria and MTS.     

Volumetric evidence of bilateral damage in unilateral mesial temporal lobe epilepsy

PURPOSE: We sought to analyze the contralateral volumes of the temporal pole, posterior segment of the temporal lobe, amygdala, hippocampus, and parahippocampal gyrus in patients with temporal lobe epilepsy (TLE) due to histologically proven mesial temporal lobe sclerosis (MTLS), seizure free for >or=4 years of postsurgical follow-up. METHODS: Forty-six (23 male) TLE patients, operated on between 1996 and 2001, with histopathologic diagnosis of MTLS, and a postsurgical follow-up of >or=4 years, had their temporal lobe structures manually segmented, measured, and compared with those of 23 normal volunteers, paired as groups for sex, age, and handedness. RESULTS: The mean volumes of the contralateral temporal pole, hippocampus, and parahippocampal gyrus in TLE patients were significantly lower than those in controls. CONCLUSIONS: MRI volumetric data show that the damage in TLE due to MTS may be more widespread and bilateral, even in patients with unilateral TLE by clinical and neurophysiological criteria. Our results are relevant to the discussion of epileptogenic mechanisms in TLE.     

High-resolution diffusion tensor imaging of the hippocampus in temporal lobe epilepsy

PURPOSE: To assess the quantitative diffusion characteristics of the hippocampus with high-resolution diffusion tensor imaging (DTI) in temporal lobe epilepsy (TLE). METHODS: Thirteen controls and seven unilateral TLE patients (six with hippocampal sclerosis, one with normal magnetic resonance imaging (MRI)) were scanned with DTI using a zonally magnified oblique multislice echo planar imaging (ZOOM-EPI) acquisition. Fractional anisotropy (FA) and mean diffusivity (MD) were measured in the hippocampi. RESULTS: The mean hippocampal MD ipsilateral to the seizure focus was higher than the contralateral MD in patients (p<0.05) and the mean MD in controls (p<0.001). Hippocampal FA ipsilateral to the seizure focus was lower than the mean FA in controls (p<0.05). MD asymmetry indexes were significantly different between the patient and control groups (p<0.01). All six individual HS patients had ipsilateral hippocampal MD >or=2 standard deviations (S.D.) above the control mean. The patient with normal structural MRI had bilaterally low hippocampal FA and high MD. DISCUSSION: High-resolution DTI identifies lateralizing abnormalities of MD and FA in TLE patients. This quantitative data on hippocampal integrity may assist in evaluating TLE patients with normal MRI, and in longitudinal studies.     

Hippocampal deformation-based shape analysis in epilepsy and unilateral mesial temporal sclerosis

PURPOSE: To assess shape changes in patients with mesial temporal sclerosis (MTS) and temporal lobe epilepsy (TLE), by using deformation-based hippocampal shape analysis. METHODS: We retrospectively reviewed magnetic resonance imaging (MRI) studies in 30 subjects with unilateral MTS (15 right-sided MTS, 15 left-sided MTS) and TLE. We defined the "average" hippocampus in the right- and left-MTS groups by generating a mean transformation for the 15 deformation images in each group. Further to quantify the difference between the hippocampi, we coregistered the mean transformation of the involved hippocampus (with MTS) to the contralateral hippocampus, considering the left- and right-MTS groups independently. We generated a color "flame" scale showing degrees of outward and inward deviation of the coregistered hippocampi. RESULTS: Both the right- and left-MTS groups showed similar shape changes, with maximal inward deformation in the medial and lateral hippocampal head and the hippocampal tail. However, more extensive involvement was seen in the lateral hippocampal body in the right-MTS group as compared with the left. CONCLUSIONS: Deformation-based hippocampal shape analysis shows specific regions of hippocampal surface anatomy that are most affected in MTS. This technique may aid in detection of clinically significant anatomic abnormalities of the hippocampus in patients with epilepsy.     

Rhinal cortex asymmetries in patients with mesial temporal sclerosis.

PURPOSE: The rhinal cortex, comprising the entorhinal (ErC) and perirhinal (PrC) cortices, is one component of the limbic system that may be affected in patients with epilepsy and other temporal lobe pathologies. This study extended quantitative examination of the limbic system through development and validation of volumetric protocols to measure the ErC and PrC. METHODS: Volumes were calculated from MRI studies using ANALYZE 7.5 and based on detailed anatomical definitions developed for the study. Subjects were 61 temporal lobe epilepsy patients with mesial temporal sclerosis (MTS: 33 left, 28 right) and 20 neurologically normal controls. Inter-rater reliabilities for the ErC and PrC volume protocols were found to be high (range 0.86-0.92). RESULTS: Ipsilateral hippocampal volume was reduced in patients with MTS, while contralateral volume did not differ significantly from controls. In the patients, rhinal cortex volumes were reduced as a function of laterality of disease. The pattern of correlations between ErC and PrC differed between disease groups. Hippocampal and rhinal cortex volumes were not significantly correlated. A significant four-way interaction was found between side of MTS, hemisphere, structure and handedness. CONCLUSIONS: This quantitative study demonstrates reliable in vivo evidence of morphometric changes in ErC and PrC in a substantial number of patients with unilateral MTS. The relationship observed between handedness, structure and disease status may suggest a role for cerebral dominance in modulating the expression of MTS.     

Bilateral white matter diffusion changes persist after epilepsy surgery

PURPOSE: Bilateral white matter diffusion tensor imaging (DTI) abnormalities have been reported in patients with temporal lobe epilepsy (TLE) and unilateral mesial temporal sclerosis (MTS), but it is unknown whether these are functional or structural changes. We performed a longitudinal study in patients with unilateral MTS who were seizure-free for 1 year after surgery to determine whether the observed presurgical white matter diffusion abnormalities were reversible. METHODS: Eight TLE patients with unilateral MTS who were seizure-free after anterior temporal resection and 22 healthy subjects were recruited. DTI was performed before surgery and at 1-year follow-up. Tractography and region-of-interest (ROI) analyses were performed in the fornix, cingulum, genu, and splenium of the corpus callosum and external capsules. Diffusion tensor parameters were compared between groups and before and after surgery in the patient group. RESULTS: The fornix, cingulum, and external capsules showed preoperative bilateral abnormal diffusion parameters (i.e., decreased diffusion anisotropy and increased mean and perpendicular diffusivities). The fornix and cingulum ipsilateral to the resected mesial temporal structures showed signs of wallerian degeneration at 1-year follow-up. The contralateral tracts of the fornix, cingulum, and external capsules, as well as the genu of the corpus callosum, failed to show a normalization of their diffusion parameters. CONCLUSIONS: The irreversibility of the white matter DTI abnormalities on seizure freedom suggests underlying structural abnormalities (e.g., axonal/myelin degradation) as opposed to functional changes (e.g., fluid shifts due to seizures) in the white matter.     

Diffusion tensor imaging findings and their correlation with neuropsychological deficits in patients with temporal lobe epilepsy and interictal psychosis

PURPOSE: To examine frontotemporal white-matter integrity in patients with temporal lobe epilepsy (TLE) and interictal psychosis. METHOD: Patients with TLE and interictal psychosis (IP; n = 20) were compared with age-matched TLE patients without psychosis (NIP; n = 20). Patients had either no focal lesions or hippocampal sclerosis on conventional MRI. Complete diffusion tensor imaging (DTI) data were available in 18 IP and 20 NIP patients. A region-of-interest (ROI) approach was used to determine the DTI measures, fractional anisotropy (FA) and mean diffusivity (MD), in the middle frontal and middle temporal gyri. The relation between the DTI measures and neuropsychological tests previously identified as impaired in the IP group was examined. RESULTS: The IP group had significantly lower FA values in both frontal and temporal regions and significantly higher MD in bilateral frontal regions. We found that performance on some neuropsychological tests was significantly related to frontotemporal FA reductions. CONCLUSIONS: Our findings suggest that subtle abnormalities in the frontotemporal white matter of patients with interictal psychosis may be undetectable on conventional MRI. These abnormalities may contribute to the cognitive deficits detected in these patients.     

Glucose and [11C]flumazenil positron emission tomography abnormalities of thalamic nuclei in temporal lobe epilepsy

OBJECTIVES: To analyze interictal patterns of thalamic nuclei glucose metabolism and benzodiazepine receptor binding in patients with medically intractable temporal lobe epilepsy (TLE) using high-resolution 2-deoxy-2-[18F]fluoro-D-glucose (FDG) and [11C]flumazenil (FMZ) PET. BACKGROUND: Structural and glucose metabolic abnormalities of the thalamus are considered important in the pathophysiology of TLE. The differential involvement of various thalamic nuclei in humans is not known. METHODS: Twelve patients with TLE underwent volumetric MRI, FDG and FMZ PET, and prolonged video-EEG monitoring. Normalized values and asymmetries of glucose metabolism and FMZ binding were obtained in three thalamic regions (dorsomedial nucleus [DMN], pulvinar, and lateral thalamus [LAT]) defined on MRI and copied to coregistered, partial-volume-corrected FDG and FMZ PET images. Hippocampal and amygdaloid FMZ binding asymmetries and thalamic volumes also were measured. RESULTS: The DMN showed significantly lower glucose metabolism and FMZ binding on the side of the epileptic focus. The LAT showed bilateral hypermetabolism and increased FMZ binding. There was a significant correlation between the FMZ binding asymmetries of the DMN and amygdala. The PET abnormalities were associated with a significant volume loss of the thalamus ipsilateral to the seizure focus. CONCLUSIONS: Decreased [11C]flumazenil (FMZ) binding and glucose metabolism of the dorsomedial nucleus (DMN) are common and have strong lateralization value for the seizure focus in human temporal lobe epilepsy. Decreased benzodiazepine receptor binding can be due to neuronal loss, as suggested by volume loss, but also may indicate impaired gamma-aminobutyric acid (GABA)ergic transmission in the DMN, which has strong reciprocal connections with other parts of the limbic system. Increased glucose metabolism and FMZ binding in the lateral thalamus could represent an upregulation of GABA-mediated inhibitory circuits.     

Is Interictal Temporal Hypometabolism Related to Mesial Temporal Sclerosis? A Positron Emission Tomography/Magnetic Resonance Imaging Confrontation

Summary: The mechanism of interictal glucose hypometabolism remains unclear, but this abnormality occurs more frequently in temporal lobe epilepsy (TLE) than in other types of partial epilepsy. Therefore temporal hypometabolism has been suggested to reflect mesial temporal sclerosis (MTS). To investigate this, we selected 22 patients with refractory partial epilepsy of mesial temporal lobe origin (MTLE) who had hippocampal atrophy based on magnetic resonance imaging (MRI) volumetric analysis. We then analyzed the metabolic correlates of unilateral hippocampal atrophy. Thirteen temporal regions of interest (ROI) were defined on MRI scans for each individual and then applied to high-resolution FDG-positron emission tomography (PET) images obtained parallel to the long axis of the hippocampus. The most hypometabolic regions were the temporal pole and the hippocampal region. When we analyzed ensembles of temporal regions grouped into related networks, the temporolimbic network, which included the hippocampal region and the temporal pole, was abnormal in 95% of the patients at a 3-SD threshold. PET hypometabolism was highly correlated with the degree of hippocampal atrophy in this network, but not in other parts of the temporal lobe, which were less frequently hypometabolic. These data indicate that hypometabolism is a consequence of MTS in the temporolimbic region but not necessarily in the other parts of the temporal lobe. Our results also suggest that the combination of PET and MRI may facilitate the noninvasive diagnosis of MTLE.     

The nature and extent of cerebellar atrophy in chronic temporal lobe epilepsy

Purpose: Research indicates that patients with chronic temporal lobe epilepsy (TLE) exhibit cerebellar atrophy compared to healthy controls, but the degree to which specific regions of the cerebellum are affected remains unclear. The purpose of this study was to characterize the extent and lateralization of atrophy in individual cerebellar lobes and subregions in unilateral TLE using advanced quantitative magnetic resonance imaging (MRI) techniques. Methods: Study participants were 46 persons with TLE and 31 age‐ and gender‐ matched healthy controls. All participants underwent high‐resolution MRI with manual tracing of the cerebellum yielding gray and white matter volumes of the right and left anterior lobes, superior posterior lobes, inferior posterior lobes, and corpus medullare. The degree to which asymmetric versus generalized abnormalities was evident in unilateral chronic TLE was determined and related to selected clinical seizure features (age of onset, duration of disorder). Key Findings: There were no lateralized abnormalities in cerebellar gray matter or white matter in patients with right or left TLE (all p’s > 0.2). Compared with controls, unilateral TLE was associated with significant bilateral reductions in the superior (p = 0.032) and inferior (p = 0.023) posterior lobes, whereas volume was significantly increased in the anterior lobes (p = 0.002), especially in patients with early onset TLE, and not significantly different in the corpus medullare (p = 0.71). Total superior cerebellar tissue volumes were reduced in association with increasing duration of epilepsy. Significance: Patients with unilateral TLE exhibit a pattern of bilateral cerebellar pathology characterized by atrophy of the superior and inferior posterior lobes, hypertrophy of the anterior lobe, and no effect on the corpus medullare. Cross‐sectional analyses show that specific aspects of cerebellar pathology are associated with neurodevelopmental (anterior lobe) or chronicity‐related (superior posterior lobe) features of the disorder.     

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.     

The significance of corpora amylacea in mesial temporal lobe epilepsy

Temporal lobe epilepsy (TLE) associated with mesial temporal sclerosis (MTS), mesial TLE (MTLE), is the commonest medically refractory adult epilepsy syndrome. Corpora amylacea (CoA) have been shown to be a marker of MTS. We compared 9 patients with MTS who had dense deposition of CoA in their hippocampi with 25 patients with MTS who did not have CoA. The patients with CoA were significantly older and they showed a trend towards having a significantly longer duration of epilepsy. The postoperative seizure outcome at 2 years was not different in the 2 groups. Our results could indicate the progressive nature of the pathology of MTS, probably indicating excitotoxic damage due to recurrent seizures, but they need to be verified by clinicopathological correlation among a larger number of patients with MTLE.