Gender and hemispheric differences in temporal lobe epilepsy: A VBM study

Purpose: Gender differences are recognized in the functional and anatomical organization of the human brain. Differences between genders are probably expressed early in life, when differential rates of cerebral maturation occur. Sexual dimorphism has been described in temporal lobe epilepsy with mesial temporal sclerosis (TLE-MTS). Several voxel-based morphometry (VBM) studies have shown that TLE-MTS extends beyond mesial temporal structures, and that there are differences in the extent of anatomical damage between hemispheres, although none have approached gender differences. Our aim was to investigate gender differences and anatomical abnormalities in TLE-MTS.Methods: VBM5 was employed to analyze gender and hemispheric differences in 120 patients with TLE-MTS and 50 controls.Results: VBM abnormalities were more widespread in left-TLE; while in women changes were mostly seen in temporal areas, frontal regions were more affected in men.Conclusions: Our study confirmed that gender and laterality are important factors determining the nature and severity of brain damage in TLE-MTS. Differential rates of maturation between gender and hemispheres may explain the distinct areas of anatomical damage in men and women. (C) 2013 British Epilepsy Association. Published by Elsevier B.V. All rights reserved.Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)Universidade Federal de São Paulo, Unidade Pesquisa & Tratamento Epilepsias UNIPETE, Dept Neurol & Neurosurg, São Paulo, BrazilUniversidade Federal de São Paulo, Dept Psychiat, Lab Interdisciplinar Neurociencias Clin LiNC, São Paulo, BrazilUniversidade Federal de São Paulo, Dept Diagnost Imagem, São Paulo, BrazilUniversidade Federal de São Paulo, Unidade Pesquisa & Tratamento Epilepsias UNIPETE, Dept Neurol & Neurosurg, São Paulo, BrazilUniversidade Federal de São Paulo, Dept Psychiat, Lab Interdisciplinar Neurociencias Clin LiNC, São Paulo, BrazilUniversidade Federal de São Paulo, Dept Diagnost Imagem, São Paulo, BrazilWeb of Scienc

Role of Neuroimaging in the Presurgical Evaluation of Epilepsy

A significant minority of patients with focal epilepsy are candidates for resective epilepsy surgery. Structural and functional neuroimaging plays an important role in the presurgical evaluation of theses patients. The most frequent etiologies of pharmacoresistant epilepsy in the adult population are mesial temporal sclerosis, malformations of cortical development, cavernous angiomas, and low-grade neoplasms. High-resolution multiplanar magnetic resonance imaging (MRI) with sequences providing T1 and T2 contrast is the initial imaging study of choice to detect these epileptogenic lesions. The epilepsy MRI protocol can be individually tailored when considering the patient's clinical and electrophysiological data. Metabolic imaging techniques such as positron emission tomography (PET) and single photon emission tomography (SPECT) visualize metabolic alterations of the brain in the ictal and interictal states. These techniques may have localizing value in patients with a normal MRI scan. Functional MRI is helpful in non-invasively identifying areas of eloquent cortex

Cognitive decline and white matter changes in mesial temporal lobe epilepsy

Noninvasive imaging plays a pivotal role in assessing the brain structural and functional changes in presurgical mesial temporal lobe epilepsy (MTLE) patients. Our goal was to study the relationship between the changes of cerebral white matter (WM) and cognitive functions in MTLE patients.Voxel-based morphometry (VBM) and tract-based spatial statistics (TBSS) MRI were performed on 24 right-handed MTLE patients (12 with left MTLE and 12 with right MTLE) and 12 matching healthy controls. Gray matter (GM), WM, and whole brain (WB) volumes were measured with VBM while fractional anisotropy (FA), mean diffusivity (MD), axial diffusivity (AD), and radial diffusivity (RD) were measured with TBSS. All patients and controls also underwent Montreal Cognitive Assessment (MoCA) before MRI.WM volume and the ratio of WM volume versus WB volume were significantly lower in MTLE patients compared with controls. WM volume in MTLE patients had a positive correlation with MoCA score (r = 0.71, P < .001) and a negative correlation with the duration of epilepsy (r = -0.693, P < .001). Volumetric differences were mainly located in the corpus callosum, uncinate fasciculus, inferior longitudinal fasciculus, and superior longitudinal fasciculus. FA of both left MTLE and right MTLE groups was significantly decreased, while MD, AD, and RD were significantly increased. Most left MTLE patients showed bilateral WM fiber tract changes versus ipsilateral changes for right MTLE patients.Changes in DTI parameters and WM volume were found in MTLE patients and more ipsilateral changes were seen with right-sided MTLE. Cognitive changes of MTLE patients were found to be correlated with the changes in WM structure. These findings not only provide useful information for lateralization of the seizure focus but can also be used to explain functional connectivity disorders which may be an important physiological basis for cognitive changes in patients with MTLE

Mesial temporal sclerosis is linked with more widespread white matter changes in temporal lobe epilepsy

AbstractTemporal lobe epilepsy patients with unilateral mesial temporal sclerosis (TLE+uMTS) have been demonstrated to have extensive white matter abnormalities both ipsilateral and contralateral to the seizure onset zone. However, comparatively less is known about the white matter integrity of TLE patients without MTS (non-lesional TLE, nl-TLE). The purpose of the study was to investigate the diffusion properties of thirteen major white matter tracts in patients with TLE+uMTS and nl-TLE. Diffusion tensor imaging (DTI) was performed on 23 TLE+uMTS (15 left MTS and 8 right MTS), 15nl-TLE and 21 controls. Thirteen tracts were delineated by tractography and their diffusion parameters compared for the two TLE groups relative to controls, with left and right hemispheres combined per tract. A subgroup analysis investigated left and right MTS separately. Compared to controls, reduced anisotropy was detected in ten tracts for TLE+uMTS, but only the parahippocampal cingulum and tapetum for nl-TLE. Right MTS subgroup showed reduced anisotropy in 7 tracts bilaterally (3 limbic, 3 association, 1 projection) and 2 tracts ipsilaterally (1 association, 1 projection) and the body of the corpus callosum whereas the left MTS subgroup showed reduced anisotropy in 4 tracts bilaterally (2 limbic, 1 association, 1 projection) and 2 tracts ipsilaterally (1 limbic, 1 association). Diffusion abnormalities in tracts were observed within and beyond the temporal lobe in TLE+uMTS and were more widespread than in nl-TLE. Patients with right MTS had more extensive, bilateral abnormalities in comparison to left MTS. These findings suggest different dysfunctional networks in TLE patients with and without MTS

Computational brain anatomy in patients with temporal lobe epilepsy

BACKGROUND Temporal lobe epilepsy (TLE) is a frequent type of focal epilepsy that constitutes 30% to 50% of all epileptic syndromes. This medical condition is often associated with hippocampal sclerosis, however it can be due to cortical dysplasia, brain tumour, vascular malformation or without any evidence for pathology (cryptogenic). Even though the main symptoms are the seizures, epilepsy sometimes interferes with cognitive functions such as visual or verbal memory, language or attention. TLE is frequently pharmaco-­‐resistant and only a hippocampal resection helps patients to become seizure-­‐free. Temporal lobe epilepsy is also described as a progressive disorder that causes chronic brain tissue damages. History of febrile seizures and status epilepticus, frequency of seizures and age at onset of seizure, as well as epilepsy duration or years of anti-­‐epileptic drugs use are all factors that impact the gravity of the brain structure's damage. Magnetic resonance imaging (MRI) has undergone a considerable development and, nowadays, has become an essential clinical tool in the diagnosis of TLE. It is currently used to reveal precisely cerebral abnormalities that may induce seizures. PURPOSE The aim of this cross-­‐sectional study is to investigate the pattern of microstructural brain tissue characteristics (grey and white matter volumes) occurring in three clinically distinctive TLE entities: mesial temporal sclerosis (MTS), focal cortical dysplasia (FCD) and cryptogenic epilepsy. By comparing them to each other, we want to acquire in-­‐depth knowledge of their pathological mechanism. We use well-­‐established computational anatomy methodology -­‐ voxel-­‐ based morphometry (VBM) to investigate brain anatomy changes related to the present clinical phenotype. CONTRIBUTION OF THE STUDY In the past few years, there has been a lot of controversy concerning structural MRI findings in TLE. Most of the studies looked for informative brain changes in epilepsy with MTS compared with healthy controls. This study is the first to take into consideration all clinical aspects of TLE together -­‐ mesial temporal sclerosis, focal cortical dysplasia and cryptogenic epilepsy. MATERIAL AND METHODS In-­‐vivo anatomical brain imaging data (MRI at 1.5T) was acquired in patients with clinical diagnosis of temporal lobe epilepsy. TLE patients were divided in three groups according to radiological description of brain MRI findings -­‐ mesial temporal sclerosis [MTS_group], focal cortical dysplasia [Dysplasia_group] and cryptogenic epilepsy [NoMRI_group] and compared with healthy volunteers. VBM technique was used to identify brain tissues alterations (GM and WM). RESULTS We demonstrate that MTS showed similar grey and white matter volumes reduction in the hippocampus, thalamus and cerebellum ipsilateral to the epileptogenic focus when compared with cryptogenic epilepsy patients and healthy controls. The focal cortical dysplasia patients showed grey matter volume loss restricted to the thalamus

Anormalidade de sinal na imagem por RM do pólo temporal na epilepsia do lobo temporal com esclerose hipocampal: um estudo pela seqüência inversão recuperação com supressão da água livre (FLAIR)

OBJECTIVE: To determine the frequency and regional involvement of temporal pole signal abnormality (TPA) in patients with hippocampal sclerosis (HS) using fluid-attenuated inversion-recovery (FLAIR) MR imaging, and to correlate this feature with history. METHOD: Coronal FLAIR images of the temporal pole were assessed in 120 patients with HS and in 30 normal subjects, to evaluate gray-white matter demarcation. RESULTS: Ninety (75%) of 120 patients had associated TPA. The HS side made difference regarding the presence of TPA, with a left side prevalence (p=0.04, chi2 test). The anteromedial zone of temporal pole was affected in 27 (30%) out of 90 patients. In 63 (70%) patients the lateral zone were also affected. Patients with TPA were younger at seizure onset (p=0.018), but without association with duration of epilepsy. CONCLUSION: Our FLAIR study show temporal pole signal abnormality in 3/4 of patients with HS, mainly seen on the anteromedial region, with a larger prevalence when the left hippocampus was involved.OBJETIVO: Determinar a freqüência e o envolvimento regional da anormalidade de sinal do pólo temporal (APT) em pacientes com esclerose hipocampal (EH) utilizando seqüência inversão recuperação com supressão da água (FLAIR) por RM, e correlacioná-la com a história. MÉTODO: Foram analisadas as imagens coronais FLAIR dos pólos temporais de 120 pacientes com EH e de 30 indivíduos normais, para avaliar a demarcação entre substâncias branca e cinzenta. RESULTADOS: Noventa (75%) dos 120 pacientes tinham APT associada. Houve prevalência do lado esquerdo (p=0.04, chi2 teste) na relação entre APT e o lado da EH. A zona ântero-medial estava acometida em 27 (30%) destes pacientes. Em 63 (70%) pacientes também a zona lateral estava acometida. Pacientes com APT apresentaram início da epilepsia quando mais jovens (p=0.018), porém sem associação com a sua duração. CONCLUSÃO: A seqüência FLAIR mostra haver ATP em 3/4 dos pacientes com EH, principalmente na região ântero-medial, com maior prevalência quando o hipocampo esquerdo estava envolvido.Universidade Federal de São Paulo (UNIFESP) Escola Paulista de Medicina Departamento de Diagnóstico por ImagemUNIFESP-EPM Departamento de Diagnóstico por ImagemUNIFESP-EPM Departamento de Neurologia e NeurocirurgiaUNIFESP, EPM, Depto. de Diagnóstico por ImagemUNIFESP, EPM Depto. de Diagnóstico por ImagemUNIFESP, EPM Depto. de Neurologia e NeurocirurgiaSciEL

Recovery of white matter atrophy after epilepsy surgery: structural evidences through voxel-based morphometry

OBJECTIVES: To study pre and postoperative WMA in MTLE patients. METHODS: We performed Voxel-Based Morphometry (VBM) with volume of interest (VOI) in 69 controls (mean age, 34.3±11.1 years) and 67 operated patients (mean age, 34.1±10.4 years) with unilateral MTLE. 34 became seizure-free (SzFree-Group), 23 improved (Engel IB-IIA [Partial recovery-group]) and 10 did not improve (Engel III-IV [Failure-Group]). All had pre and postoperative MRIs (one year minimum). We flipped MRIs of right MTLE patients in order to avoid right-to-left analysis cancelation. VBM was performed on SPM2/MATLAB7.0 with individual masks for surgical lacunae and 1% false-discovery-rate to control for multiple comparisons. We used MARSbar routine to select ROIs and t-test for statistical analyses. RESULTS: Mean postoperative follow-up was 60.2 (±SD 30.7) months. On baseline MRI, SzFree-Group showed White Matter Atrophy (WMA) involving temporal lobes [TL], ipsilateral occipital, parietal and frontal regions, with areas of significant recovery of WMA on postoperative MRI. Partial recovery-Group presented a more restricted pattern of WMA, involving ipsilateral temporal lobe, contralateral superior temporal gyrus and few areas in bilateral cingulated and orbitofrontal areas. In this group we also identified areas with relative increase of WM after surgery. By contrast, Failure-Group showed more widespread bi-hemispheric areas of WMA on baseline MRI without postoperative improvement. CONCLUSIONS: Although we have identified some differences in baseline WMA, we were unable to correlate a more widespread pattern with a worse prognosis, as SzFree-Group, also presented a bilateral distribution of WMA. The recovery of WMA in SzFree-Group and Partial recovery-group is in agreement with previous MRS and PET studies and suggests that a network of neuronal dysfunction in MTLE can be, at least in part, reversible after successful postoperative seizure control.071

Thalamic medial dorsal nucleus atrophy in medial temporal lobe epilepsy: A VBM meta-analysis

Purpose: Medial temporal lobe epilepsy (MTLE) is associated with MTLE network pathology within and beyond the hippocampus. The purpose of this meta-analysis was to identify consistent MTLE structural change to guide subsequent targeted analyses of these areas. Methods: We performed an anatomic likelihood estimation (ALE) meta-analysis of 22 whole-brain voxel-based morphometry experiments from 11 published studies. We grouped these experiments in three ways. We then constructed a meta-analytic connectivity model (MACM) for regions of consistent MTLE structural change as reported by the ALE analysis. Key findings: ALE reported spatially consistent structural change across VBM studies only in the epileptogenic hippocampus and the bilateral thalamus; within the thalamus, the medial dorsal nucleus of the thalamus (MDN thalamus) represented the greatest convergence (Pb0.05 corrected for multiple comparisons). The subsequent MACM for the hippocampus and ipsilateral MDN thalamus demonstrated that the hippocampus and ipsilateral MDN thalamus functionally co-activate and are nodes within the same network, suggesting that MDN thalamic damage could result from MTLE network excitotoxicity. Significance: Notwithstanding our large sample of studies, these findings aremore restrictive thanprevious reports and demonstrate the utility of our inclusion filters and of recently modified meta-analyticmethods in approximating clinical relevance. Thalamic pathology is commonly observed in animal and human studies, suggesting it could be a clinically useful indicator. Thalamus-specific research as a clinical marker awaits further investigation