Network alterations in temporal lobe epilepsy during non-rapid eye movement sleep and wakefulness.

OBJECTIVE: Investigate sleep and temporal lobe epilepsy (TLE) effects on brain networks derived from electroencephalography (EEG). METHODS: High-density EEG was recorded during non-rapid eye movement (NREM) sleep stage 2 (N2) and wakefulness in 23 patients and healthy controls (HC). Epochs without epileptic discharges were source-reconstructed in 72 brain regions and connectivity was estimated. We calculated network integration and segregation at global (global efficiency, GE; average clustering coefficient, avgCC) and hemispheric level. These were compared between groups across frequency bands and correlated with the individual proportion of wakefulness- or sleep-related seizures. RESULTS: At the global level, patients had higher delta GE, delta avgCC and theta avgCC than controls, irrespective of the vigilance state. During wakefulness, theta GE of patients was higher than controls and, for patients, theta GE during wakefulness was higher than during N2. Wake-to-sleep differences in TLE were notable only in the ipsilateral hemisphere. Only measures from wakefulness recordings correlated with the proportion of wakefulness- or sleep-related seizures. CONCLUSIONS: TLE network alterations are more prominent during wakefulness and at lower frequencies. Increased integration and segregation suggest a pathological 'small world' configuration with a possible inhibitory role. SIGNIFICANCE: Network alterations in TLE occur and are easier to detect during wakefulness.

Impact of intracranial subclinical seizures on seizure outcomes after SLAH in patients with mesial temporal lobe epilepsy.

OBJECTIVE: To investigate the association between subclinical seizures detected on intracranial electroencephalographic (i-SCSs)recordings and mesial temporal sclerosis (MTS), as well as their impact on surgical outcomes of stereotactic laser amygdalohippocampotomy (SLAH). METHODS: A retrospective review was conducted on 27 patients with drug-resistant mesial temporal lobe epilepsy (MTLE) who underwent SLAH. The number of seizures detected on scalp EEG and iEEG was assessed. Patients were followed for a minimum of 3 years after SLAH. RESULTS: Of the 1715 seizures recorded from mesial temporal regions, 1640 were identified as i-SCSs. Patients with MTS were associated with favorable short- and long-term surgical outcomes. Patients with MTS had a higher number of i-SCSs compared to patients without MTS. The numbers of i-SCSs were higher in patients with Engel I-II outcomes, but no significant statistical difference was found. However, it was observed that patients with MTS who achieved Engel I-II classification had higher numbers of i-SCSs than patients without MTS (P < 0.05). CONCLUSION: Patients with MTS exhibited favorable short-term and long-term surgical outcome after SLAH. A higher number of i-SCSs was significantly associated with MTS in patients with MTLE. The number of i-SCSs tended to be higher in patients with Engel Ⅰ-Ⅱ surgical outcomes. SIGNIFICANCE: The association between i-SCSs, MTS, and surgical outcomes in MTLE patients undergoing SLAH has significant implications for understanding the underlying mechanisms and identifying potential therapeutic targets to enhance surgical outcomes.

Electroencephalographic microstates as a potential neurophysiological marker differentiating bilateral from unilateral temporal lobe epilepsy.

OBJECTIVE: Electroencephalographic (EEG) microstate abnormalities have been documented in different neurological disorders. We aimed to assess whether EEG microstates are altered also in patients with temporal epilepsy (TLE) and whether they show different activations in patients with unilateral TLE (UTLE) and bilateral TLE (BTLE). METHODS: Nineteen patients with UTLE, 12 with BTLE, and 15 healthy controls were enrolled. Resting state high-density electroencephalography (128 channels) was recorded for 15 min with closed eyes. We obtained a set of stable scalp maps representing the EEG activity, named microstates, from which we acquired the following variables: global explained variance (GEV), mean duration (MD), time coverage (TC), and frequency of occurrence (FO). Two-way repeated measures analysis of variance was used to compare groups, and Spearman correlation was performed to study the maps in association with the clinical and neuropsychological data. RESULTS: Patients with BTLE and UTLE showed differences in most of the parameters (GEV, MD, TC, FO) of the four microstate maps (A-D) compared to controls. Patients with BTLE showed a significant increase in all parameters for the microstates in Map-A and a decrease in Map-D compared to UTLE and controls. We observed a correlation between Map-A, disease duration, and spatial short-term memory, whereas microstate Map-D was correlated with the global intelligence score and short-term memory performance. SIGNIFICANCE: A global alteration of the neural dynamics was observed in patients with TLE compared to controls. A different pattern of EEG microstate abnormalities was identified in BTLE compared to UTLE, which might represent a distinctive biomarker.

Leukocyte differential gene expression prognostic value for high versus low seizure frequency in temporal lobe epilepsy.

BACKGROUND: This study was performed to test the hypothesis that systemic leukocyte gene expression has prognostic value differentiating low from high seizure frequency refractory temporal lobe epilepsy (TLE). METHODS: A consecutive series of patients with refractory temporal lobe epilepsy was studied. Based on a median baseline seizure frequency of 2.0 seizures per month, low versus high seizure frequency was defined as ≤ 2 seizures/month and > 2 seizures/month, respectively. Systemic leukocyte gene expression was analyzed for prognostic value for TLE seizure frequency. All differentially expressed genes were analyzed, with Ingenuity® Pathway Analysis (IPA®) and Reactome, to identify leukocyte gene expression and biological pathways with prognostic value for seizure frequency. RESULTS: There were ten males and six females with a mean age of 39.4 years (range: 16 to 62 years, standard error of mean: 3.6 years). There were five patients in the high and eleven patients in the low seizure frequency cohorts, respectively. Based on a threshold of twofold change (p < 0.001, FC > 2.0, FDR < 0.05) and expression within at least two pathways from both Reactome and Ingenuity® Pathway Analysis (IPA®), 13 differentially expressed leukocyte genes were identified which were all over-expressed in the low when compared to the high seizure frequency groups, including NCF2, HMOX1, RHOB, FCGR2A, PRKCD, RAC2, TLR1, CHP1, TNFRSF1A, IFNGR1, LYN, MYD88, and CASP1. Similar analysis identified four differentially expressed genes which were all over-expressed in the high when compared to the low seizure frequency groups, including AK1, F2R, GNB5, and TYMS. CONCLUSIONS: Low and high seizure frequency TLE are predicted by the respective upregulation and downregulation of specific leukocyte genes involved in canonical pathways of neuroinflammation, oxidative stress and lipid peroxidation, GABA (γ-aminobutyric acid) inhibition, and AMPA and NMDA receptor signaling. Furthermore, high seizure frequency-TLE is distinguished prognostically from low seizure frequency-TLE by differentially increased specific leukocyte gene expression involved in GABA inhibition and NMDA receptor signaling. High and low seizure frequency patients appear to represent two mechanistically different forms of temporal lobe epilepsy based on leukocyte gene expression.

Coexistence of temporal lobe epilepsy and idiopathic generalized epilepsy.

OBJECTIVE: We investigated the frequency of coexistence of temporal lobe epilepsy (TLE) and idiopathic generalized epilepsy (IGE) in a retrospective database study. We also explored the underlying pathomechanisms of the coexistence of TLE and IGE based on the available information, using bioinformatics tools. METHODS: The first phase of the investigation was a retrospective study. All patients with an electro-clinical diagnosis of epilepsy were studied at the outpatient epilepsy clinic at Shiraz University of Medical Sciences, Shiraz, Iran, from 2008 until 2023. In the second phase, we searched the following databases for genetic variations (epilepsy-associated genetic polymorphisms) that are associated with TLE or syndromes of IGE: DisGeNET, genome-wide association study (GWAS) Catalog, epilepsy genetic association database (epiGAD), and UniProt. We also did a separate literature search using PubMed. RESULTS: In total, 3760 patients with epilepsy were registered at our clinic; four patients with definitely mixed TLE and IGE were identified; 0.1% of all epilepsies. We could identify that rs1883415 of ALDH5A1, rs137852779 of EFHC1, rs211037 of GABRG2, rs1130183 of KCNJ10, and rs1045642 of ABCB1 genes are shared between TLE and syndromes of IGE. CONCLUSION: While coexistence of TLE and IGE is a rare phenomenon, this could be explained by shared genetic variations.

Dynamic Functional Connectivity Analysis Using Network-Based Brain State Identification, Application on Temporal Lobe Epilepsy.

Epilepsy is a brain network disorder caused by discharges of interconnected groups of neurons and resulting brain dysfunction. The brain network can be characterized by intra- and inter-regional functional connectivity (FC). However, since the BOLD signal is inherently non-stationary, the FC is evidenced to be varying over time. Considering the dynamic characteristics of the functional network, we aimed to obtain dynamic brain states and their properties using network-based analyses for the comparison of healthy control and temporal lobe epilepsy (TLE) groups and also lateralization of TLE patients. We used dwelling time, transition time, and brain network connection in each state as the dynamic features for this purpose. Results showed a significant difference in dwelling time and transition time between the healthy control group and both left TLE and right TLE groups and also a significant difference in brain network connections between the left and right TLE groups.

A simple, automated method of seizure detection in mouse models of temporal lobe epilepsy.

The lack of preventive and disease modifying therapies for temporal lobe epilepsy (TLE) is a major unmet medical need. Search for such therapies utilize mouse models and require detection of seizures in electroencephalography (EEG) recordings. The labor-intensive nature of reviewing EEGs spanning many weeks underscores the need for a method of automated detection. Here we report a simple automated method of detecting seizures in long term EEG recordings from electrodes implanted in the hippocampus in animal models of TLE. We utilize a 2-pronged approach that relies on the increase in power within the gamma band range (20-50hz) during the seizure followed by suppression of activity following the seizure (post-ictal suppression [PIS]). We demonstrate the utility of this method for detecting seizures in hippocampal and amygdala EEG recordings from multiple models of TLE.

The relationship between mood and anxiety and cognitive phenotypes in adults with pharmacoresistant temporal lobe epilepsy.

OBJECTIVE: Patients with temporal lobe epilepsy (TLE) are often at a high risk for cognitive and psychiatric comorbidities. Several cognitive phenotypes have been identified in TLE, but it is unclear how phenotypes relate to psychiatric comorbidities, such as anxiety and depression. This observational study investigated the relationship between cognitive phenotypes and psychiatric symptomatology in TLE. METHODS: A total of 826 adults (age = 40.3, 55% female) with pharmacoresistant TLE completed a neuropsychological evaluation that included at least two measures from five cognitive domains to derive International Classification of Cognitive Disorders in Epilepsy (IC-CoDE) cognitive phenotypes (i.e., intact, single-domain impairment, bi-domain impairment, generalized impairment). Participants also completed screening measures for depression and anxiety. Psychiatric history and medication data were extracted from electronic health records. Multivariable proportional odds logistic regression models examined the relationship between IC-CoDE phenotypes and psychiatric variables after controlling for relevant covariates. RESULTS: Patients with elevated depressive symptoms had a greater odds of demonstrating increasingly worse cognitive phenotypes than patients without significant depressive symptomatology (odds ratio [OR] = 1.123-1.993, all corrected p's < .05). Number of psychotropic (OR = 1.584, p < .05) and anti-seizure medications (OR = 1.507, p < .001), use of anti-seizure medications with mood-worsening effects (OR = 1.748, p = .005), and history of a psychiatric diagnosis (OR = 1.928, p < .05) also increased the odds of a more severe cognitive phenotype, while anxiety symptoms were unrelated. SIGNIFICANCE: This study demonstrates that psychiatric factors are not only associated with function in specific cognitive domains but also with the pattern and extent of deficits across cognitive domains. Results suggest that depressive symptoms and medications are strongly related to cognitive phenotype in adults with TLE and support the inclusion of these factors as diagnostic modifiers for cognitive phenotypes in future work. Longitudinal studies that incorporate neuroimaging findings are warranted to further our understanding of the complex relationships between cognition, mood, and seizures and to determine whether non-pharmacologic treatment of mood symptoms alters cognitive phenotype.

Value of ultralong-term subcutaneous EEG monitoring for treatment decisions in temporal lobe epilepsy: A case report.

Treatment decisions in epilepsy critically depend on information on the course of the disease, its severity and options for specific local interventions. We here report a patient with pharmaco-resistant non-lesional temporal lobe epilepsy with evidence for predominant right temporal epileptogenesis. While seizure frequency had been grossly underestimated for many years, ultralong-term monitoring with a subcutaneous EEG device revealed actual seizure frequency (66 over 11 months vs four patient-documented seizures), providing objective data on treatment efficacy and additional supportive lateralizing information that played a decisive role for the choice of surgical treatment, which had been rejected by the patient prior to this information.

Quantitative electroencephalography performance of different brain lobe epilepsy.

OBJECTIVE: To investigate the quantitative electroencephalography features of different brain lobe epilepsy. METHODS: The electroencephalogram data of adult patients diagnosed with epilepsy in the epilepsy clinic of the Second Affiliated Hospital of Shandong First Medical University from January 1, 2012 to December 31, 2016 were collected, 58 cases in total. They included 28 cases of frontal lobe epilepsy,12 cases of temporal lobe epilepsy, 9 cases of occipital lobe epilepsy, and 9 cases of parietal lobe epilepsy. Quantitative electroencephalography analysis technique was used to obtain the δ, θ, α1, α2, ß1 and ß2 power spectrum value in patients with different brain lobe epilepsy. The δ, θ, α, and ß relative power spectrum value are obtained by calculation. By comparing the quantitative electroencephalography indicators of the affected side and the healthy side, the quantitative electroencephalography characteristics of epilepsy in different lobes were obtained. RESULTS: θ power spectrum can be increased in the discharge lead of temporal lobe epilepsy. δ and θ power spectrum, δ relative power spectrum can be increased in the discharge lead of occipital lobe epilepsy. CONCLUSION: The increase in slow wave power spectrum in QEEG can serve as an auxiliary diagnosis for temporal lobe epilepsy and occipital lobe epilepsy.

Familial Mesial Temporal Lobe Epilepsy: Clinical Spectrum and Genetic Evidence for a Polygenic Architecture.

OBJECTIVE: Familial mesial temporal lobe epilepsy (FMTLE) is an important focal epilepsy syndrome; its molecular genetic basis is unknown. Clinical descriptions of FMTLE vary between a mild syndrome with prominent déjà vu to a more severe phenotype with febrile seizures and hippocampal sclerosis. We aimed to refine the phenotype of FMTLE by analyzing a large cohort of patients and asked whether common risk variants for focal epilepsy and/or febrile seizures, measured by polygenic risk scores (PRS), are enriched in individuals with FMTLE. METHODS: We studied 134 families with ≥ 2 first or second-degree relatives with temporal lobe epilepsy, with clear mesial ictal semiology required in at least one individual. PRS were calculated for 227 FMTLE cases, 124 unaffected relatives, and 16,077 population controls. RESULTS: The age of patients with FMTLE onset ranged from 2.5 to 70 years (median = 18, interquartile range = 13-28 years). The most common focal seizure symptom was déjà vu (62% of cases), followed by epigastric rising sensation (34%), and fear or anxiety (22%). The clinical spectrum included rare cases with drug-resistance and/or hippocampal sclerosis. FMTLE cases had a higher mean focal epilepsy PRS than population controls (odds ratio = 1.24, 95% confidence interval = 1.06, 1.46, p = 0.007); in contrast, no enrichment for the febrile seizure PRS was observed. INTERPRETATION: FMTLE is a generally mild drug-responsive syndrome with déjà vu being the commonest symptom. In contrast to dominant monogenic focal epilepsy syndromes, our molecular data support a polygenic basis for FMTLE. Furthermore, the PRS data suggest that sub-genome-wide significant focal epilepsy genome-wide association study single nucleotide polymorphisms are important risk variants for FMTLE. ANN NEUROL 2023;94:825-835.

Unilateral non-lesional temporal lobe epilepsy presenting as isolated ictal vertigo: a case report.

Temporal lobe epilepsy is the most common focal epilepsy syndrome and has a broad spectrum of presentations. Nevertheless, isolated vestibular symptoms without other symptoms typical of temporal lobe seizures are relatively rare. Here, we report one female patient who suffered from chronic refractory vertigo and had inappropriate pharmacotherapy for several years. Eventually, epileptic vertigo and dizziness (ictal vertigo) were accurately diagnosed by detailed history taking and serial examinations assisted by sphenoid electroencephalography. Awareness of this unique syndrome is important in the diagnosis of patients with epileptic vertigo and dizziness.

Ipsilateral preictal alpha rhythm attenuation (IPARA): An EEG sign of side of seizure onset in temporal lobe epilepsy.

PURPOSE: Identification of the seizure onset zone is critically important for outlining the surgical plan in the treatment of pharmacoresistant focal epilepsy. In patients with temporal lobe epilepsy (TLE), bilateral ictal scalp EEG changes frequently occur and can make lateralization of the seizure onset zone difficult. We investigated the incidence and clinical utility of unilateral preictal alpha rhythm attenuation as a lateralizing sign of seizure onset in TLE. METHODS: Scalp EEG recordings of the seizures acquired during presurgical video-EEG monitoring of 57 consecutive patients with TLE were reviewed retrospectively. Included patients had interictal baseline recordings demonstrating symmetrical posterior alpha rhythm and seizures occurring during wakefulness. RESULTS: We identified a total of 649 seizures in the 57 patients, of which 448 seizures in 53 patients fulfilled the inclusion criteria. Among the 53 included patients, 7 patients (13.2%) exhibited a distinct attenuation of the posterior alpha rhythm prior to the first ictal EEG changes, in 26 of 112 (23.2%) included seizures. Preictal alpha rhythm attenuation in these seizures was ipsilateral to the ultimately determined side of seizure onset (based on video-EEG or intracranial EEG findings) in 22 (84.6%) of these seizures and bilateral in 4 (15.4%), and occurred on average 5.9 ± 2.6 s prior to ictal EEG onsets. CONCLUSION: Our findings suggest that in some patients with TLE lateralized preictal attenuation of the posterior alpha rhythm may be a useful indicator of side of seizure onset, presumably due to early disruption of thalamo-temporo-occipital network function, likely mediated through the thalamus.

Pre-ictal fluctuation of EEG functional connectivity discriminates seizure phenotypes in mesial temporal lobe epilepsy.

OBJECTIVE: We explored whether quantifiable differences between clinical seizures (CSs) and subclinical seizures (SCSs) occur in the pre-ictal state. METHODS: We analyzed pre-ictal stereo-electroencephalography (SEEG) retrospectively across mesial temporal lobe epilepsy patients with recorded CSs and SCSs. Power spectral density and functional connectivity (FC) were quantified within and between the seizure onset zone (SOZ) and the early propagation zone (PZ), respectively. To evaluate the fluctuation of neural connectivity, FC variability was computed. Measures were further verified by a logistic regression model to evaluate their classification potentiality through the area under the receiver-operating-characteristics curve (AUC). RESULTS: Fifty-four pre-ictal SEEG epochs (27 CSs and 27 SCSs) were selected among 14 patients. Within the SOZ, pre-ictal FC variability of CSs was larger than SCSs in 1-45 Hz during 30 seconds before seizure onset. Pre-ictal FC variability between the SOZ and PZ was larger in SCSs than CSs in 55-80 Hz within 1 minute before onset. Using these two variables, the logistic regression model achieved an AUC of 0.79 when classifying CSs and SCSs. CONCLUSIONS: Pre-ictal FC variability within/between epileptic zones, not signal power or FC value, distinguished SCSs from CSs. SIGNIFICANCE: Pre-ictal epileptic network stability possibly marks seizure phenotypes, contributing insights into ictogenesis and potentially helping seizure prediction.

Seizure onset patterns predict outcome after stereo-electroencephalography-guided laser amygdalohippocampotomy.

OBJECTIVE: Stereotactic laser amygdalohippocampotomy (SLAH) is an appealing option for patients with temporal lobe epilepsy, who often require intracranial monitoring to confirm mesial temporal seizure onset. However, given limited spatial sampling, it is possible that stereotactic electroencephalography (stereo-EEG) may miss seizure onset elsewhere. We hypothesized that stereo-EEG seizure onset patterns (SOPs) may differentiate between primary onset and secondary spread and predict postoperative seizure control. In this study, we characterized the 2-year outcomes of patients who underwent single-fiber SLAH after stereo-EEG and evaluated whether stereo-EEG SOPs predict postoperative seizure freedom. METHODS: This retrospective five-center study included patients with or without mesial temporal sclerosis (MTS) who underwent stereo-EEG followed by single-fiber SLAH between August 2014 and January 2022. Patients with causative hippocampal lesions apart from MTS or for whom the SLAH was considered palliative were excluded. An SOP catalogue was developed based on literature review. The dominant pattern for each patient was used for survival analysis. The primary outcome was 2-year Engel I classification or recurrent seizures before then, stratified by SOP category. RESULTS: Fifty-eight patients were included, with a mean follow-up duration of 39 ± 12 months after SLAH. Overall 1-, 2-, and 3-year Engel I seizure freedom probability was 54%, 36%, and 33%, respectively. Patients with SOPs, including low-voltage fast activity or low-frequency repetitive spiking, had a 46% 2-year seizure freedom probability, compared to 0% for patients with alpha or theta frequency repetitive spiking or theta or delta frequency rhythmic slowing (log-rank test, p = .00015). SIGNIFICANCE: Patients who underwent SLAH after stereo-EEG had a low probability of seizure freedom at 2 years, but SOPs successfully predicted seizure recurrence in a subset of patients. This study provides proof of concept that SOPs distinguish between hippocampal seizure onset and spread and supports using SOPs to improve selection of SLAH candidates.

The potential of the Lempel-Ziv complexity of the EEG in diagnosing cognitive impairment in patients with temporal lobe epilepsy.

AIM: To analyze whether the Lempel-Ziv Complexity (LZC) in quantitative electroencephalogram differs between the temporal lobe epilepsy (TLE) patients with or without cognitive impairment (CI) and explore the diagnostic value of LZC for identifying CI in TLE patients. METHODS: Twenty-two clinical features and 20-min EEG recordings were collected from 48 TLE patients with CI and 27 cognitively normal (CON) TLE patients. Seventy-six LZC features were calculated for 19 leads in four frequency bands (alpha, beta, delta, and theta). The clinical and LZC features were compared between the two groups. A support vector machine (SVM) was subsequently constructed using the leave-one-out method of cross-validation for LZC features with statistical differences. RESULTS: Regarding the clinical features, the level of education (p < .001), hippocampal atrophy and sclerosis (p = .029), and depression (p = .037) were statistically different between the two groups. For the LZC features, there were statistically significant differences in the alpha (Fp1, Fz, Cz, Pz, C3, C4, T3, T4, T5, T6, F3, F4, F7, F8, O1, and O2), beta (Fp2), and theta (F7) oscillations. The mean LZC in the alpha band was higher in the TLE-CI group than that in the CON group, and there were no differences in the remaining bands. The SVM model showed 74.51% accuracy, 79.63% sensitivity, 84.30% F1 score, 68.75% specificity, and .85 area under the curve scores. CONCLUSIONS: The LZC in the alpha band might have the potential to be used as a biomarker for the diagnosis of TLE combined with CI. The TLE-CI group, on the other hand, exhibited a higher degree of complexity in alpha oscillations, which were widespread and occurred in all brain regions.

Frontal headache in a patient with right temporal epilepsy: A video-EEG case report of ictal epileptic headache.

BACKGROUND: Ictal epileptic headache (IEH) is caused by a focal epileptic seizure. The diagnosis can be challenging when the headache is isolated without any other symptoms. CASE REPORT: A 16-year-old girl presented with a 5-year history of bilateral frontotemporal headaches with severe intensity lasting for 1-3 min. Past medical, physical, and developmental histories were unremarkable. Head magnetic resonance imaging showed right hippocampal sclerosis. The diagnosis of pure IEH was confirmed by video-electroencephalographic monitoring. The onset and cessation of frontal headache correlated with a right temporal discharge. The patient was diagnosed with right mesial temporal lobe epilepsy. Two years later, her seizures increased despite antiseizure medications. A right anterior temporal lobectomy was performed. The patient remained seizure-free and headache-free for 10 years. CONCLUSION: IEH should be considered in the differential diagnosis of brief and isolated headache, even if the headache is diffuse or contralateral to the epileptogenic focus.

[Analysis of brain volume asymmetry and clinical application in patients with temporal lobe epilepsy with hippocampal sclerosis based on automatic brain segmentation].

Objective: To analyze whole brain structural volume asymmetry in temporal lobe epilepsy with hippocampal sclerosis (TLE-HS) using automated brain segmentation technology, and to investigate the application value of this technology in the diagnosis of TLE-HS and the performance in determining the location the lateralization of epileptogenic focus. Methods: Twenty-eight patients with TLE-HS were enrolled in the First Affiliated Hospital of Zhengzhou University from April 2019 to October 2020, including 13 females and 15 males, aged ranged from 18 to 63 (30±12) years, and these patients were divided two group according to the epilepsy lateralization, left TLE-HS(LTLE-HS) group (n=11), right TLE-HS(RTLE-HS) group (n=17) and 28 normal controls [aged ranged from 18 to 49 (29±10) years]. All of these subjects underwent three-dimensional T1 weighted image (3D T1WI). The differences of brain structure and volumes in LTLE-HS, RTLE-HS and normal controls group were retrospectively analyzed, and Pearson's correlation coefficient was used to evaluate the left and right volume correlations, and effect size was used for evaluating the differences in left and right volume averages. The asymmetry index (AI) of the left and right lateral volumes in each group was also calculated and compared among the three groups. Results: Standard volumes of all structures within the brain were asymmetric in the normal controls, LTLE-HS, and RTLE-HS groups, with smaller volumes of ipsilateral hippocampus than contralateral hippocampus in both the LTLE-HS and RTLE-HS groups(0.20%±0.03% vs 0.24%±0.02%,0.21%±0.03% vs 0.25%±0.02% respectively;both P<0.001), and smaller volumes of gray and white matter of the ipsilateral temporal lobe than contralateral in the LTLE-HS group(4.41%±0.38% vs 5.01%±0.43%,1.83%±0.22 % vs 2.22%±0.14%;both P<0.001). There was a moderate to strong linear correlation (0.553