The value of ictal scalp EEG in focal epilepsies surgery: a retrospective analysis.

OBJECTIVE: To describe the association between preoperative ictal scalp electroencephalogram (EEG) results and surgical outcomes in patients with focal epilepsies. METHODS: The data of consecutive patients with focal epilepsies who received surgical treatments at our center from January 2012 to December 2021 were retrospectively analyzed. RESULTS: Our data showed that 44.2% (322/729) of patients had ictal EEG recorded on video EEG monitoring during preoperative evaluation, of which 60.6% (195/322) had a concordant ictal EEG results. No significant difference of surgery outcomes between patients with and without ictal EEG was discovered. Among MRI-negative patients, those with concordant ictal EEG had a significantly better outcome than those without ictal EEG (75.7% vs. 43.8%, p = 0.024). Further logistic regression analysis showed that concordant ictal EEG was an independent predictor for a favorable outcome (OR = 4.430, 95%CI 1.175-16.694, p = 0.028). Among MRI-positive patients, those with extra-temporal lesions and discordant ictal EEG results had a worse outcome compared to those without an ictal EEG result (44.7% vs. 68.8%, p = 0.005). Further logistic regression analysis showed that discordant ictal EEG was an independent predictor of worse outcome (OR = 0.387, 95%CI 0.186-0.807, p = 0.011) in these patients. Furthermore, our data indicated that the number of seizures was not associated with the concordance rates of the ictal EEG, nor the surgical outcomes. CONCLUSIONS: The value of ictal scalp EEG for epilepsy surgery varies widely among patients. A concordant ictal EEG predicts a good surgical outcome in MRI-negative patients, whereas a discordant ictal EEG predicts a poor postoperative outcome in lesional extratemporal lobe epilepsy.

Associations of glymphatic function with structural network and cognition in self-limited epilepsy with centrotemporal spikes.

PURPOSE: To investigate glymphatic function by Virchow-Robin space (VRS) counts and volume in patients with newly diagnosed self-limited epilepsy with centrotemporal spikes (SeLECTS) and evaluate its relationship with structural connectivity and cognitive impairment. METHODS: Thirty-two children with SeLECTS and thirty-two age- and sex-matched typically developing (TD) children were enrolled in this study. VRS counts and volume were quantified. Structural networks were constructed and the topological metrics were analyzed. Wechsler Intelligence Scale (WISC) was used to assess cognitive function in all participants. Correlation analysis assessed the association between VRS counts and volume, network connectivity, and cognitive impairment. Mediation effects of topological metrics of the structural networks on the relationship between glymphatic function and cognitive impairment were explored. RESULTS: Patients with SeLECTS showed a higher VRS counts, VRS volume, and global shortest path length (Lp); they also showed a lower global efficiency (Eg). VRS counts and volume were significantly correlated with full-scale intelligence quotient (FIQ) (r_VRS counts = -0.520, r_VRS volume = -0.639), performance intelligence quotient (PIQ) (r_VRS counts = -0.693, r_VRS volume = -0.597), verbal intelligence quotient (VIQ) (r_VRS counts = -0.713, r_VRS volume = -0.699), Eg (r_VRS counts = -0.499, r_VRS volume = -0.490), and Lp (r_VRS volume = 0.671) in patients with SeLECTS. Eg mediated 24.59% of the effects for the relationship between VRS volume and FIQ. CONCLUSION: Glymphatic function may be impaired in SeLECTS reflected by VRS counts and volume. Glymphatic dysfunction may result in cognitive impairment by disrupting structural connectivity in SeLECTS.

Incidence, Severity, and Risk Factors of Hemorrhagic Complications of Epilepsy Surgery After 2026 Craniotomies from 2003 to 2019: A Single Center Experience.

BACKGROUND: Surgery is effective in the treatment of epilepsy, particularly focal epilepsy. The aim of this work was to report the incidence and grade of severity of hemorrhagic complications after cranial epilepsy surgery, and investigate the risk factors. METHODS: Patients who underwent epilepsy surgery via craniotomy between October 2003 and April 2019 were retrospectively analyzed. The incidence of hemorrhagic complications occurring in a 3-month period after cranial surgery was recorded. Other outcomes included the grade of hemorrhagic severity and risk factors. RESULTS: During the inclusion period, 2026 surgical procedures were performed. Sixty-six hemorrhagic complications were recorded. The total incidence of hemorrhagic complications after cranial epilepsy surgery was 3.3%. The most common type of hemorrhagic complications was epidural hemorrhage (57.6%), followed by intraparenchymal hemorrhage (33.3%). Forty-five patients (68.2%) had grade I complications, 4 (6.1%) grade II, 16 (24.2%) grade III, and 1 (1.5%) grade IV. The mortality due to hemorrhagic complications was 1.5% (1 of 66) and hemorrhagic mortality among all cranial surgery was 0.05% (1 of 2026). Left craniotomy induced a higher percentage of severe hemorrhage than the right (34.2% vs. 14.3%). Extratemporal lobe epilepsy induced a higher percentage of severe hemorrhage than other epilepsy type (34.2% vs. 14.3%). However, no statistically significant difference was observed between these two factors (P = 0.067). CONCLUSIONS: Hemorrhagic complications were uncommon after open surgery for epilepsy. Most hemorrhagic complications were mild while the severe were rare. Patients with hemorrhagic complications had a good prognosis after effective treatment.

The clinical features of patients with seizure freedom and failure after total corpus callosotomy for childhood-onset refractory epilepsy.

BACKGROUND: Corpus callosotomy is a palliative surgery for medically refractory epilepsy. We aim to analyze the clinical features of patients with seizure freedom and failure after total corpus callosotomy for childhood-onset refractory epilepsy. METHODS: We retrospectively reviewed the clinical courses of patients with childhood-onset refractory epilepsy undergoing total corpus callosotomy between May 2009 and March 2019. Seizure outcome at the last follow-up was the primary outcome. The clinical features of patients with seizure freedom and failure after callosotomy were compared. RESULTS: Eighty patients with childhood-onset refractory epilepsy underwent total corpus callosotomy; 15 (18.8%) obtained freedom from all seizures and 19 (23.8%) had unworthwhile improvement and failure. The mean ages at seizure onset in patients with seizure freedom and failure after callosotomy were 5.7 and 5.9 years; and mean seizure durations were 9.4 and 11.5 years, respectively. Univariate analysis found epilepsy syndrome (p = 0.047), mental retardation (p = 0.007), previous medical history (p = 0.004), ≥10 seizures per day (p = 0.024), theta waves in the background electroencephalogram (p = 0.024), and acute postoperative seizure (p = 0.000) were associated with failure after callosotomy. Seizure freedom after callosotomy was more common among patients with less than 10 seizures per day. CONCLUSIONS: Total corpus callosotomy is an effective palliative procedure for childhood-onset refractory epilepsy, particularly for patients with specific clinical characteristics. Callosotomy has a high seizure-free rate in well-selected patients.

Subdural osteoma in an adolescent patient with epilepsy: an unusual case report and literature review.

OBJECTIVE: Subdural osteoma (SO) is a rarely reported benign tumor, and there is no report of SO manifested with epileptic seizures. We aim to further the understanding of SO-related epilepsy. METHODS: Here, we report a meaningful case of epilepsy secondary to SO. A systematic review of the literature about SO using the electronic database PubMed and Web of science up to December 2022 was conducted. RESULTS: A 15-year-old girl presented with epileptic seizures for 8 years. Magnetic resonance imaging revealed an irregular lesion with heterogeneous signal in the right frontal convexity. Right frontal craniotomy was performed to remove the lesion. The pathological diagnosis was SO. Histological analysis revealed that the mechanosensitive ion channels Piezo 1/2 were upregulated in the brain tissue compressed by the osteoma, compared with the levels in the osteoma-free region. Seizure freedom was obtained during the 6-month follow-up after the surgery. We identified 24 cases of SO in 23 articles. With our case, a total of 25 cases with 32 SOs was included. Of 25 cases, 24 are adults, and 1 is a child. Seizure has been reported only in our case. Frontal osteoma was found in 76% of the patients. Symptoms were cured in 56% of the patients after surgery. CONCLUSION: Surgery is a safe and effective approach to the treatment of symptomatic osteoma. Mechanical compression on cerebral cortex may be a predisposing factor of the epileptogenesis caused by the SO.

Multivariate analysis of seizure outcomes after resective surgery for focal epilepsy: a single-center study on 833 patients.

The predictors of seizure outcomes after resective surgery for focal epilepsy, for an update on the features of good and poor outcomes, are investigated. A retrospective study of patients with focal epilepsy undergoing resective surgery from March 2011 to April 2019 was performed. There were 3 groups according to the seizure outcomes: seizure freedom, seizure improvement, and no improvement. Predictors of seizure outcomes were identified by multivariate logistic regression analysis. Of all 833 patients, 561 (67.3%) patients remained seizure-free at the last follow-up, 203 (24.4%) patients had seizure improvement, and 69 (8.3%) had no improvement. The mean follow-up duration was 5.2 years (range: 2.7 to 9.6). Predictors of better outcomes included epilepsy duration < 5 years, localized discharge, no. of antiepileptic drugs at surgery < 3, and temporal lobe resection. However, predictors of worse outcomes included intracranial hemorrhage in infancy, interictal abnormal discharge, intracranial electrode monitoring, and acute postoperative seizure. Our study suggests that resective surgery for focal epilepsy has satisfactory outcomes. Short epilepsy duration, localized discharge, and temporal lobe resection are positive predictors of seizure freedom. Patients with these predictors are intensively recommended for surgery.

Functional Anterior Temporal Lobectomy for Temporal Lobe Epilepsy: A Novel, Alternative, and Less Invasive Therapy.

BACKGROUND: Anterior temporal lobectomy is the most effective treatment for intractable temporal lobe epilepsy (TLE). However, patients are reluctant to choose this surgery for fear of risks after large frontotemporal craniotomy, and epileptologists likewise have a cautious attitude because of surgical trauma. Functional anterior temporal lobectomy (FATL) is a minimally invasive surgery procedure for addressing the above concerns. OBJECTIVE: To report preliminary data on this procedure and its safety and efficacy for treating TLE. METHODS: This consecutive case series study was conducted between October 2020 and September 2021. Patients with TLE underwent FATL by minicraniotomy with a diameter of 3 cm. Surgery duration, postoperative complications, and seizure control are described herein. Seizure outcomes were classified using Engel classifications. RESULTS: A total of 25 patients undergoing FATL for TLE were enrolled. The median epilepsy duration was 8 years. The median surgery duration was 165 min. The median blood loss was 100 mL. The median postoperative hospital stay was 8 days. No deaths occurred after surgery. Only 1 patient presented with a cerebrospinal fluid disorder that was successfully treated using a ventriculoperitoneal shunt. At the last follow-up, 23 patients (92%) were seizure-free (Engel-Ia), 1 patient remained substantially improved (Engel-II), and 1 patient obtained worthwhile seizure reduction (Engel-III). CONCLUSION: Our pilot study suggests that FATL is a viable surgical therapy for TLE. This method has the advantages of minimal invasiveness and high seizure-free rate. A controlled trial is warranted to verify the efficacy and safety of FATL comparing with anterior temporal lobectomy.

Stimulation induced aura during subdural recording: A useful predictor of postoperative outcome in refractory epilepsy.

INTRODUCTION: Electrical cortical stimulation (ECS) is a routine procedure commonly conducted in intracranial EEG (iEEG) monitoring in refractory epilepsy and associated with postoperative outcome in stereoelectroencephalography (SEEG) exploration. To better understand this effective method, this study aimed to examine the role of ECS in subdural recording. METHODS: The ECS results of 144 consecutive patients who were monitored via subdural electrodes and received epilepsy surgery were retrospectively collected. The occurrence of stimulation induced aura (SIA) and seizure (SIS) and their distributions as well as their associations with postoperative outcomes were analyzed. RESULTS: Among all 144 patients, 47.2% (68/144) achieved Engel class I recovery with a mean follow-up of 6.6±2.2 years (2.0-9.8 years). The percentages of patients who showed SIA and SIS were 16.0% (23/144) and 43.8% (63/144), respectively. Our data indicated that 30.4% (42/138) of SIS occurred in frontal lobe, which was significantly higher than the 7.7% (10/130) occurred in temporal lobe and the 8.5% (11/129) in parieto-occipital region (p<0.001). Meanwhile, no such distribution difference was discovered in SIA (p=0.229). Univariate and multifactorial analyses showed that SIA was the only independent predictor for postoperative outcome and patients with SIA were 4.8 times more likely to achieve seizure-free (95% CI 1.557-14.789, p = 0.006). CONCLUSIONS: Our study demonstrated that SIS sites are more likely to be located in the frontal lobe and SIA independently predicts optimal postoperative outcome in subdural recording.

Disparate properties of afterdischarges elicited by electric cortical stimulation in MRI lesional epilepsy patients with different surgical outcomes.

PURPOSE: The purpose of this study was to demonstrate the prognostic value of afterdischarges(ADs) on surgical outcome by comparing the disparate properties in epilepsy patients with different surgical outcomes METHODS: 27 lesional epilepsy patients were retrospectively analyzed. The brain region covered by subdural electrodes in each patient was dichotomized into the area of the brain lobe(s) where the MRI lesion is located (region ML) and other brain areas (region nML). The occurrence of ADs and ADs evolving into clinical seizure, ADs threshold and ADs duration in region ML and nML were compared between seizure-free (SF) and non-seizure-free (nSF) patients. RESULTS: A total of 2535 contacts were analyzed, and the total occurrence of ADs was 18.6% (471/2535). The overall occurrence of ADs in region ML (24.8%) was significantly higher than that in region nML (10.3%) (P < 0.001). In region ML, compared with SF patients, nSF patients had a lower occurrence of ADs (19.2% vs. 31.2%, P < 0.001), a higher occurrence of ADs evolves into clinical seizure (8.7% vs. 2.4%, P = 0.006), a higher ADs threshold (12.8 ± 4.1 mA vs. 11.0 ± 3.7 mA, P < 0.001) and a shorter ADs duration (15.3 ± 14.2 s vs. 20.6 ± 17.0 s, P < 0.001). However, in region nML, there was no significant difference in properties of ADs between SF and nSF patients. CONCLUSION: Higher occurrence of ADs in region ML might predict a good outcome, whereas higher occurrence of ADs evolving into clinical seizure, higher ADs threshold and shorter ADs duration might predict an unfavorable surgical outcome. ADs might help predict surgical outcomes in epilepsy patients.

Severity Grading, Risk Factors, and Prediction Model of Complications After Epilepsy Surgery: A Large-Scale and Retrospective Study.

Purpose: To report complications after epilepsy surgery, grade the severity of complications, investigate risk factors, and develop a nomogram for risk prediction of complications. Methods: Patients with epilepsy surgery performed by a single surgeon at a single center between October 1, 2003 and April 30, 2019 were retrospectively analyzed. Study outcomes included severity grading of complications occurring during the 3-month period after surgery, risk factors, and a prediction model of these complications. Multivariable logistic regression analysis was used to calculate odds ratio and 95% confidence interval to identify risk factors. Results: In total, 2,026 surgical procedures were eligible. There were 380 patients with mild complications, 23 with moderate complications, and 82 with severe complications. Being male (odds ratio 1.29, 95% confidence interval 1.02-1.64), age at surgery (>40 years: 2.58, 1.55-4.31; ≤ 40: 2.25, 1.39-3.65; ≤ 30: 1.83, 1.18-2.84; ≤ 20: 1.71, 1.11-2.63), intracranial hemorrhage in infancy (2.28, 1.14-4.57), serial number of surgery ( ≤ 1,000: 1.41, 1.01-1.97; ≤ 1,500: 1.63, 1.18-2.25), type of surgical procedure (extratemporal resections: 2.04, 1.55-2.70; extratemporal plus temporal resections: 2.56, 1.80-3.65), surgery duration (>6 h: 1.94, 1.25-3.00; ≤ 6: 1.92, 1.39-2.65), and acute postoperative seizure (1.44, 1.06-1.97) were independent risk factors of complications. A nomogram including age at surgery, type of surgical procedure, and surgery duration was developed to predict the probability of complications. Conclusions: Although epilepsy surgery has a potential adverse effect on the patients, most complications are mild and severe complications are few. Risk factors should be considered during the perioperative period. Patients with the above risk factors should be closely monitored to identify and treat complications timely. The prediction model is very useful for surgeons to improve postoperative management.

Decreased expression of the clock gene Bmal1 is involved in the pathogenesis of temporal lobe epilepsy.

Clock genes not only regulate the circadian rhythm of physiological activities but also participate in the pathogenesis of many diseases. Previous studies have documented the abnormal expression of clock genes in epilepsy. However, the molecular mechanism of brain and muscle Arnt-like protein 1 (Bmal1), one of the core clock genes, in the epileptogenesis and seizures of temporal lobe epilepsy (TLE) remain unclear. We first investigated the levels of Bmal1 and other clock proteins in the hippocampus of subjects with epilepsy to define the function of Bmal1. The levels of Bmal1 were decreased during the latent and chronic phases in the experimental group compared with those in the control group. Knockout of Bmal1 in hippocampal dentate gyrus (DG) neurons of Bmal1flox/flox mice by Synapsin 1 (Syn1) promoter AAV (adeno-associated virus) lowered the threshold of seizures induced by pilocarpine administration. High-throughput sequencing analysis showed that PCDH19 (protocadherin 19), a gene associated with epilepsy, was regulated by Bmal1. PCDH19 expression was also decreased in the hippocampus of epileptic mice. Furthermore, the higher levels of Bmal1 and PCDH19 were detected in patients with no hippocampal sclerosis (no HS) than in patients with HS International League Against Epilepsy (ILAE) type I and III. Altogether, these data suggest that decreased expression of clock gene Bmal1 may participate in epileptogenesis and seizures via PCDH19 in TLE.

Oral and manual automatisms elicited by electrical stimulation of the pars opercularis cortex in a patient with frontal lobe epilepsy.

Oral automatism (OA) and manual automatism (MA) are common signs during initiation of temporal seizures. However, the precise symptomatogenic zones for OA and MA remains largely unclear. In this study, we presented a case of intractable frontal lobe epilepsy (FLE) in which the patient received intracranial EEG monitoring with subdural electrodes. During electrical stimulation of a grid contact located over the right pars opercularis cortex, OA and contralateral MA were observed unexpectedly without afterdischarges (ADs) or with brief ADs detected in the adjacent contacts. This case suggested that the pars opercularis cortex might play an important role in generating OA. In addition, our data implied that the symptomatogenic zone for MA might locate contralaterally to symptomatic hand.

Optimal Surgical Approach for the Dumbbell-Shaped Trigeminal Schwannoma.

ABSTRACT: Dumbbell-shaped trigeminal schwannoma afflicts the middle and posterior cranial fossa. Surgical approach for gross total resection remains highly challenging. The authors present a case of dumbbell-shaped trigeminal schwannoma treated successfully by using frontotemporal intradural approach with the removal of temporal pole. Subtotal resection was achieved as the schwannoma was closely adhered to trigeminal nerve. As a postoperative complication, abducens paralysis recovered significantly within the 3-month follow-up. No severe complication was observed. The authors suggest that frontotemporal intradural approach is optimal surgical approach as it is particularly convenient and safe.

Downregulation of hsa_circ_0001836 Induces Pyroptosis Cell Death in Glioma Cells via Epigenetically Upregulating NLRP1.

BACKGROUND: It has been shown that circular RNAs (circRNAs) play a vital role in the progression of glioma. Recently, hsa_circ_0001836 was found to be upregulated in glioma tissues, but the role of hsa_circ_0001836 in glioma remains unclear. METHODS: EdU staining and flow cytometry assays were used to measure the viability and death of glioma cells. In addition, scanning electron microscopy (SEM) was used to observe the morphology of cells undergoing cell death. RESULTS: Hsa_circ_0001836 expression was upregulated in U251MG and SHG-44 cells. In addition, hsa_circ_0001836 knockdown significantly reduced the viability and proliferation of U251MG and SHG-44 cells. Moreover, hsa_circ_0001836 knockdown markedly induced the pyroptosis of U251MG and SHG-44 cells, evidenced by the increased expressions of NLRP1, cleaved caspase 1 and GSDMD-N. Meanwhile, methylation specific PCR (MSP) results indicated that hsa_circ_0001836 knockdown epigenetically increased NLRP1 expression via mediating DNA demethylation of NLRP1 promoter region. Furthermore, downregulation of hsa_circ_0001836 notably induced pyroptosis and inhibited tumor growth in a mouse xenograft model of glioma. CONCLUSION: Collectively, hsa_circ_0001836 knockdown could induce pyroptosis cell death in glioma cells in vitro and in vivo via epigenetically upregulating NLRP1 expression. These findings suggested that hsa_circ_0001836 may serve as a potential therapeutic target for the treatment of glioma.

Upregulated Nmnat2 causes neuronal death and increases seizure susceptibility in temporal lobe epilepsy.

A significant pathological feature of refractory temporal lobe epilepsy (TLE) is neuronal loss. Oxidative stress caused by repeated seizures is an important mechanism leading to neuronal loss in hippocampus. Nicotinamide-adenine dinucleotide (NAD) a coenzyme that is involved in many biochemical oxidation-reduction reactions. Nicotinamide mononucleotide adenylyltransferase 2 (Nmnat2) catalyzes an essential step in NAD (NADP) biosynthetic pathwayhas and been considered as a neuronal maintenance factor that protect neurons against insults through context-dependent mechanism. However, it is unexpected that Nmnat2 does not play a neuroprotective role in epilepsy. We found that Nmnat2 was increased in mice model of TLE. Gain-of-function approach revealed that overexpression of Nmnat2 in CA1 area enhanced seizure susceptibility and caused neuronal loss in vivo. Moreover, we found that the chaperone function was essential to increased apoptosis through the function mutation of Nmnat2. Finally, Nmnat2 overexpression in vivo reduced in expression of SOD2 and increased FoxO3a. Overall, our study discloses a new biological function of Nmnat2 in epilepsy and provides novel insights into the molecular events underlying epilepsy.

TRAK1-Mediated Abnormality of Mitochondrial Fission Increases Seizure Susceptibility in Temporal Lobe Epilepsy.

Mitochondrial dysfunction is closely related to the occurrence of epilepsy. Homeostasis of mitochondrial fusion and division can alleviate mitochondrial dysfunction. The trafficking kinesin protein 1 (TRAK1) is a key regulator of mitochondrial movement and regulates mitochondrial fusion-fission balance. The pathogenic variants in TRAK1 result in the severe neurodevelopmental disorders. However, the role of TRAK1 in epilepsy remains unclear. In the present study, we report that TRAK1 has a crucial function in regulation of epileptogenesis in temporal lobe epilepsy (TLE). TRAK1 expression is decreased in the patient specimens and animal model of TLE. Knockdown of TRAK1 causes an increase in mitochondrial fission factor (MFF) in vitro and the susceptibility to seizures in vivo. Exogenous overexpression of TRAK1 can rescue the dysfunction caused by TRAK1 knockdown. These findings provide new insights into the fundamental mechanisms of TRAK1 in TLE and have important implications for understanding and treating TLE via targeting mitochondrion.

Glucose Deficiency Elevates Acid-Sensing Ion Channel 2a Expression and Increases Seizure Susceptibility in Temporal Lobe Epilepsy.

Brain hypometabolism is a common epilepsy-related finding in both patients and animal models. Fluorodeoxyglucose positron emission tomography studies have shown that recurrent seizures lead to reduced glucose metabolism in certain brain regions, but no studies have definitively determined whether this induces epileptogenesis. There is evidence that acid-sensing ion channel 2a (ASIC2a) affects epilepsy susceptibility. Transcription factor CP2 (TFCP2) regulates ASIC2a expression. We report that suppressed TFCP2 expression and elevated ASIC2a expression were associated with glucose hypometabolism in the hippocampi of humans with epilepsy and of rat epilepsy model brains. In cultured PC12 cells, we determined that glucose deficiency led to TFCP2 downregulating ASIC2a. Moreover, electrophysiological recordings from cultured rat hippocampal slices showed that ASIC2a overexpression resulted in more action potentials in CA1 pyramidal neurons and increased seizure susceptibility. Our findings suggest that hippocampal glucose hypometabolism elevates ASIC2a expression by suppressing TFCP2 expression, which further enhances the intrinsic excitability of CA1 pyramidal neurons and increases seizure susceptibility in patients with temporal lobe epilepsy.

Occurrence predictors of the temporal interictal epileptic discharges in epilepsy patients with extratemporal lesions: A prospective cohort study.

OBJECTIVE: Electrical kindling models of epilepsy suggest that medial temporal structures are more prone to be irritated. The aim of this study is to investigate the occurrence rate of temporal interictal epileptic discharges (TIEDs) in the epilepsy patients with extratemporal lesions (ETLs), and to determine the predictive factors for TIEDs in this cohort. METHODS: Totally 221 patients were admitted for presurgical evaluation, and focal ETL were found in all of them by MRI examination. The occurrence rates of TIEDs in several groups with different brain lobe locations, durations; of epilepsy, seizure frequencies, and onset ages stages were assessed. We also evaluated the surgical outcome of; resection in this cohort. RESULTS: The total occurrence rate of TIEDs in this cohort was 29.9%. The occurrence rate of TIEDs in the patients with longer durations (>5 or 10 years) was significantly higher than those with shorter duration (<1 year). These; patients with lower seizure frequency (<1 seizure/month) had a significantly decreased incidence of TIEDs; compared with those with higher frequency (>1 seizure/month or week). In the terms of the brain lobe locations; and age at onset, there were no differences between the groups. Furthermore, there were no differences in terms of the surgical outcomes between the patients with TIEDs and other patients in this series. CONCLUSIONS: TIEDs were frequently recorded in these patients with ETLs, and the predictive factors for TIEDs included the epilepsy duration and seizure frequency. SIGNIFICANCE: This study is instrumental for the presurgical EEG interpretationand the counseling of these ETLs patients considered for epilepsy surgery.

Altered Expression Pattern of Acid-Sensing Ion Channel Isoforms in Piriform Cortex After Seizures.

The piriform cortex (PC) is highly susceptible to chemical and electrical seizure induction. Epileptiform activity is associated with an acid shift in extracellular pH, suggesting that acid-sensing ion channels (ASICs) expressed by PC neurons may contribute to this enhanced epileptogenic potential. In epileptic rats and surgical samples from patients with medial temporal lobe epilepsy (TLE), PC layer II ASIC1a-immunopositive neurons appeared swollen with dendritic elongation, and there was loss of ASIC1a-positive neurons in layer III, consistent with enhanced vulnerability to TLE-induced plasticity and cell death. In rats, pilocarpine-induced seizures led to transient downregulation of ASIC1a and concomitant upregulation of ASIC2a in the first few days post-seizure. These changes in expression may be due to seizure-induced oxidative stress as a similar reciprocal change in ASIC1a, and ASIC2a expression was observed in PC12 cells following H2O2 application. The proportion of ASIC1a/ASIC2a heteromers was reduced in the acute phase following status epilepticus (SE) but increased during the latent phase when rats developed spontaneous seizures. Knockdown of ASIC2a by RNAi reduced dendritic length and spine density in primary neurons, suggesting that seizure-induced upregulation of ASIC2a contributes to dendritic lengthening in PC layer II in rats. Administration of the ASIC inhibitor amiloride before pilocarpine reduced the proportion of rats reaching Racine level IV seizures, protected layer II and III neurons, and prolonged survival in the acute phase following SE. Our findings suggest that ASICs may enhance susceptibility to epileptogenesis in the PC. Inhibition of ASICs, particularly ASIC2a, may suppress seizures originating in the PC.

Intermittent hypoxia preconditioning-induced epileptic tolerance by upregulation of monocarboxylate transporter 4 expression in rat hippocampal astrocytes.

Noxious stimuli applied at doses close to but below the threshold of cell injury induce adaptive responses that provide a defense against additional stress. Epileptic preconditioning protects neurons against status epilepticus and ischemia; however, it is not known if the converse is true. During hypoxia/ischemia (H/I), lactate released from astrocytes is taken up by neurons and is stored for energy, a process mediated by monocarboxylate transporter 4 (MCT4) in astroglia. The present study investigated whether H/I preconditioning can provide protection to neurons against epilepsy through upregulation of MCT4 expression in astrocytes in vitro and in vivo. An oxygen/glucose deprivation protocol was used in primary astrocyte cultures, while rats were subjected to an intermittent hypoxia preconditioning (IHP) paradigm followed by lithium-pilocarpine-induced epilepsy as well as lactate transportation inhibitor injection, with a subsequent evaluation of protein expression as well as behavior. H/I induced an upregulation of MCT4 expression, while an IHP time course of 5 days provided the greatest protection against epileptic seizures, which was most apparent by 3 days after IHP. However, lactate transport function disturbances can block the protective effect induced by IHP. These findings provide a potential basis for the clinical treatment of epilepsy.