A Magnetic Resonance Imaging Study Of Progressive Brain Morphologic Damage Of Mesial Temporal Lobe Epilepsy With Hippocampal Sclerosis

Part â… :Causal influence of hippocampal atrophy on progressive brain structural damage in temporal lobe epilepsyObjective:In temporal lobe epilepsy with evidence of hippocampal sclerosis, volumetric gray abnormalities are not restricted to the hippocampus but also are found in the extrahippocampal structures, which constitute the temporal lobe epilepsy network. However, the relationship between the progressive hippocampal and extrahippocampal morphometric damage is still unclear. The purpose of our study is to find the causal relationship of morphometric alterations between hippocampus and other regions in mesial temporal lobe epilepsy (mTLE), i.e., whether the hippocampal atrophy leads to progressive morphmetric alterations in other regions.Materials and methods:A total of 108 mTLE patients with unilateral hippocampal sclerosis were enrolled in this study, and 108 age- and sex-matched healthy controls served as healthy controls (HC). Clinical data of the all patients were collected. All participators underwent the three-dimensional high-resolution T1 structural MRI scan. Voxel-based morphometry (VBM) analysis on T1-weighted images were processed using VBM8. Gray matter volume (GMV) data of patient and HC groups were compared using two-sample t-tests were performed to map the overall GMV alterations in mTLE. Voxel-wise correlation analysis was performed between GMV data and progressive factors of epilepsy duration and estimated number of seizure events. We also categorized the patients into four subgroups from low to high stages of progressive factors. GMV data of each subgroup was compared with those of HC using two-sample t-test. By applying Granger causality analysis to the morphological data sequenced by progressive factors, we constructed causal networks of structural covariance (CaSCN) associated with hippocampus of epileptogenic focus in mTLE.Results:Compared with the HCs, the patients with mTLE showed overall GMV reductions in the mesial and lateral temporal lobes ipsilateral to the epileptogenic side, the bilateral frontal lobes, thalamus and cerebellum. Moreover, increased GMV could be found in the contralateral amygdale and posterior cingulate cortex. With the gradual increase of epilepsy duration and estimated number of lifetime seizures, we found progressive patterns of reduced GMV in mTLE. Compared with the HCs, the patients showed increased connectivity in the ipsilateral mesial temporal regions, and decreased connectivity in the ipsilateral lateral temporal cortex and contralateral hippocampus. We found that the hippocampal atrophy exerted causal effect on structural damages in a network consisting of thalamus-temporal and frontal cortices-cerebellum.Conclusion:With the gradual increase of epilepsy duration and estimated number of lifetime seizures, we found progressive patterns of reduced GMV in mTLE. Based on a novel network-sensitive approach of CaSCN, our work provided new evidence on the network spread mechanism in terms of the causal influence of hippocampal atrophy on progressive brain structural alterations in mTLE.Part â…¡:A structural magnetic resonance imaging study of morphometric changes of temporal lobe epilepsy with different initial precipitating injuriesObjective:The purpose of the study is to investigate the morphometric and laterality alteration of brain gray matter of mesial temporal lobe epilepsies (mTLE) with different initial pathogenic factors, including febrile convulsion (FC), intracranial infection (â…¡) and no pathogenic factors (NO), and further explore the latent pathological physiological mechanisms of mTLE with different initial precipitating injuries.Materials and Methods:A total of 141 mTLE patients with unilateral hippocampal sclerosis were enrolled in this study, and 139 age-and sex-matched healthy controls served as healthy controls (HC). Clinical data of the all patients were collected. We categorized the patients with different pathogenic factors into three groups, including mTLE-FC, mTLE-II and mTLE-NO. All participators underwent the three-dimensional high-resolution T1 structural MRI scan. Voxel-based morphometry (VBM) analysis on high-resolution T1-weighted images were processed using VBM8. Data of mTLE groups and HCs were compared using one-way analysis of variance (ANOVA) were performed to map the overall GMV and lateralization alterations caused by different precipitating injuries.Results:Compared to HC, all groups of mTLE patients showed significant alterations of GMV and lateralization of the whole brain. In different subgroups of mTLE patients, the mTLE-â…¡ group showed the most severe GMV damage. Compared to mTLE-FC group, areas of GMV reduction were mainly located in temporal lobe and insula ipsilateral to the epileptogenic side, bilateral thalamus, frontal lobe and anterior cingulate in mTLE-â…¡ group. Compared to mTLE-NO group, areas of GMV reduction were located in the ipsilateral temporal lobe, thalamus and cerebellum, bilateral frontal lobe and caudate in mTLE-II group. In addition, in mTLE-NO group we found increased GMV in contralateral hippocampus compared with mTLE-FC group. Results of lateralization study showed in mTLE-â…¡ group the ipsilateral hippocampus displayed reduced lateralization of GMV compared with the other two groups. Meanwhile, ipsilateral superior parietal gyrus in mTLE-NO group showed reduced lateralization of GMV compared with the mTLE-FC group.Conclusion:The distribution patterns of GMV and lateralization are differed in mTLE caused by initial precipitating injuries. mTLE with intracranial infection in childhood displayed the most serious structure damage of gray matter, suggested the pathophysiological underlying mechanisms of initial precipitating injuries are different. In addition, we proposed that laterality of GMV might be a more sensitive marker to detect brain structural abnormality.