Gray Matter and White Matter Abnormalities in Temporal Lobe Epilepsy Patients with and without Hippocampal Sclerosis (original) (raw)
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Epilepsy Research, 2012
Summary Purpose: Applying a cross-sectional design, we set out to further characterize the significance of extrahippocampal brain atrophy in a large sample of 'sporadic' mesial temporal lobe epilepsy with hippocampal sclerosis (MTLE + HS). By evaluating the influence of epilepsy chronicity on structural atrophy, this work represents an important step towards the characterization of MRI-based volumetric measurements as genetic endophenotypes for this condition. Methods: Using an automated brain segmentation technique, MRI-based volume measurements of several brain regions were compared between 75 patients with 'sporadic' MTLE + HS and 50 healthy controls. Applying linear regression models, we examined the relationship between structural atrophy and important clinical features of MTLE + HS, including disease duration, lifetime number of partial and generalized seizures, and history of initial precipitating insults (IPIs). Results: Significant volume loss was detected in ipsilateral hippocampus, amygdala, thalamus, and cerebral white matter (WM). In addition, contralateral hippocampal and bilateral cerebellar grey matter (GM) volume loss was observed in left MTLE + HS patients. Hippocampal, amygdalar, and cerebral WM volume loss correlated with duration of epilepsy. This correlation was stronger in patients with prior IPIs history. Further, cerebral WM, cerebellar GM, and contralateral hippocampal volume loss correlated with lifetime number of generalized seizures.
Left Temporal Lobe Epilepsy Patients Without Hippocampal Sclerosis: a DTI and VBM Study
Journal of Systems and Integrative Neuroscience, 2020
Approximately, 30% of temporal-lobe-epilepsy patients have no identified epiloptegenic finding on conventional brain MRI. The underlying pathological mechanism seems to be different when the laterality of seizure onset is considered. Thus, we examined the gray and white matter structural integrity of non-lesional left temporal lobe epilepsy patients. 16 left non-lesional temporal lobe epilepsy patients and 18 healthy controls underwent brain MRI protocol, including the conventional brain imaging epilepsy protocol along with 3D-T1 high resolution and diffusion tensor imaging sequences. The structural integrity was investigated using between-groups whole-brain voxel-based morphometry and reconstructing 20 WM fiber bundles using diffusion tensor imaging tractography. Compared to healthy controls, patients presented gray matter atrophies in temporal, limbic and widespread extra-temporal regions, including occipital, parietal and frontal lobes as well as structures of the cerebellum. Moreover, fractional anisotropy decreases were detected in arcuate, cingulum, fornix, inferior longitudinal fasciculus, inferior fronto-occipital fasciculus and uncinate fasciculus bundles. All affected tracts were ipsilateral to the seizure focus. Reduced axial diffusivity values were also observed for both left arcuate and left cingulate hippocampal part tracts in the patient group. Concluding, the present study revealed temporal, limbic and widespread extra-temporal gray matter atrophies as well as ipsilateral, widespread alterations of temporal and extra-temporal white matter fiber tracts, in non-lesional left temporal lobe epilepsy patients compared to healthy controls, shedding light on a complex network which might be associated with left temporal lobe epilepsy discharges.
Temporal lobe epilepsy with (TLE-mts) and without (TLE-no) mesial temporal sclerosis display different patterns of cortical neuronal loss, suggesting that the distribution of white matter damage may also differ between the sub-groups. The purpose of this study was to examine patterns of white matter damage in TLE-mts and TLE-no and to determine if identified changes are related to neuronal loss at the presumed seizure focus. The 4 T diffusion tensor imaging (DTI) and T1-weighted data were acquired for 22 TLE-mts, 21 TLE-no and 31 healthy controls. Tract-based spatial statistics (TBSS) was used to compare fractional anisotropy (FA) maps and voxel-based morphometry (VBM) was used to identify grey matter (GM) volume atrophy. Correlation analysis was conducted between the FA maps and neuronal loss at the presumed seizure focus. In TLE-mts, reduced FA was identified in the genu, body and splenium of the corpus callosum, bilateral corona radiata, cingulum, external capsule, ipsilateral internal capsule and uncinate fasciculus. In TLE-no, FA decreases were identified in the genu, the body of the corpus callosum and ipsilateral anterior corona radiata. The FA positively correlated with ipsilateral hippocampal volume. Widespread extra-focal GM atrophy was associated with both sub-groups. Despite widespread and extensive GM atrophy displaying different anatomical patterns in both sub-groups, TLE-mts demonstrated more extensive FA abnormalities than TLE-no. The microstructural organization in the corpus callosum was related to hippocampal volume in both patients and healthy subjects demonstrating the association of these distal regions.
Progression of gray matter atrophy in seizure-free patients with temporal lobe epilepsy
Epilepsia, 2016
To investigate the presence and progression of gray matter (GM) reduction in seizure-free patients with temporal lobe epilepsy (TLE). We enrolled 39 consecutive TLE patients, seizure-free for at least 2 years-20 with magnetic resonance imaging (MRI) signs of hippocampal sclerosis (TLE-HS), 19 with normal MRI (TLE-NL), and 74 healthy controls. For longitudinal analysis, we included individuals who had a second MRI with minimum interval of 18 months: 21 patients (10 TLE-HS, 11 TLE-NL) and 11 controls. Three-dimensional (3D) T1 -weighted images acquired in 3 Tesla MRI were analyzed with voxel-based morphometry (VBM). The images of patients with right-sided interictal epileptogenic zone (EZ) were right-left flipped, as well as a comparable proportion of controls. Cross-sectional analysis: The patients' images from each group were compared to controls to investigate differences in GM volumes. Longitudinal analysis: The first and second images were compared in each group to look for d...
Voxel-based morphometry of temporal lobe epilepsy: An introduction and review of the literature
Epilepsia, 2008
We review the applications and results of voxelbased morphometry (VBM) studies that have reported brain changes associated with temporal lobe epilepsy (TLE). A PubMed search yielded 18 applications of VBM to study brain abnormalities in patients with TLE up to May 2007. Across studies, 26 brain regions were found to be significantly reduced in volume relative to healthy controls. There was a strong asymmetrical distribution of temporal lobe abnormalities preferentially observed ipsilateral to the seizure focus, particularly of the hippocampus (82.35% of all studies), parahippocampal gyrus (47.06%), and entorhinal (23.52%) cortex. The contralateral hippocampus was reported as abnormal in 17.65% of studies. There was a much more bilateral distribution of extratempo-ral lobe atrophy, preferentially affecting the thalamus (ipsilateral = 61.11%, contralateral = 50%) and parietal lobe (ipsilateral = 47.06%, contralateral = 52.94%). VBM generally reveals a distribution of brain abnormalities in patients with TLE consistent with the region-of-interest neuroimaging and postmortem literature. It is unlikely that VBM has any clinical utility given the lack of robustness for individual comparisons. However, VBM may help elucidate some unresolved important research questions such as how recurrent temporal lobe seizures affect hippocampal and extrahippocampal morphology using serial imaging acquisitions.
Voxel-Based Morphometry of Temporal Lobe Epileptic Patients
Purpose: In refractory temporal lobe epilepsy (rTLE), gray matter (GM) abnormalities are not confined to the hippocampus but also are found in extrahippocampal structures. Very recently we observed in mild TLE (mTLE) with or without mesiotemporal sclerosis (MTS), GM reductions in regions outside the presumed epileptogenic focus. To date, there are no studies that directly investigate whether whole-brain GM volume differs between rTLE and mTLE. Herein, we used optimized voxel-based morphometry (VBM) to identify GM abnormalities beyond the hippocampus in both rTLE and mTLE with evidence of MTS.
Hippocampal and thalamic atrophy in mild temporal lobe epilepsy: A VBM study
Neurology, 2008
Background: Patients with temporal lobe epilepsy (TLE) often have mild drug-responsive epilepsy which is frequently associated with MRI detectable mesial temporal sclerosis (MTS), indicating that MTS is not necessarily related to seizure severity. To better define the anatomic substrates associated with TLE, we applied voxel-based morphometry (VBM) analysis to patients with mild TLE.