Bilateral Temporal Lobe Epilepsy Research Articles

Brain Networks for Cortical Atrophy and Responsive Neurostimulation in Temporal Lobe Epilepsy

Drug-resistant temporal lobe epilepsy (TLE) has been associated with hippocampal pathology. Most surgical treatment strategies, including resection and responsive neurostimulation (RNS), focus on this disease epicenter; however, imaging alterations distant from the hippocampus, as well as emerging data from responsive neurostimulation trials, suggest conceptualizing TLE as a network disorder. To assess whether brain networks connected to areas of atrophy in the hippocampus align with the topography of distant neuroimaging alterations and RNS response. This retrospective case-control study was conducted between July 2009 and June 2022. Data collection for this multicenter, population-based study took place across 4 tertiary referral centers in Montréal, Canada; Querétaro, México; Nanjing, China; and Salt Lake City, Utah. Eligible patients were diagnosed with TLE according to International League Against Epilepsy criteria and received either neuroimaging or neuroimaging and RNS to the hippocampus. Patients with encephalitis, traumatic brain injury, or bilateral TLE were excluded. Spatial alignment between brain network topographies. Of the 110 eligible patients, 94 individuals diagnosed with TLE were analyzed (51 [54%] female; mean [SD] age, 31.3 [10.9] years). Hippocampal thickness maps in TLE were compared to 120 healthy control individuals (66 [55%] female; mean [SD] age, 29.8 [9.5] years), and areas of atrophy were identified. Using an atlas of normative connectivity (n = 1000), 2 brain networks were identified that were functionally connected to areas of hippocampal atrophy. The first network was defined by positive correlations to temporolimbic, medial prefrontal, and parietal regions, whereas the second network by negative correlations to frontoparietal regions. White matter changes colocalized to the positive network (t93 = -3.82; P = 2.44 × 10-4). In contrast, cortical atrophy localized to the negative network (t93 = 3.54; P = 6.29 × 10-3). In an additional 38 patients (20 [53%] female; mean [SD] age, 35.8 [11.3] years) treated with RNS, connectivity between the stimulation site and atrophied regions within the negative network was associated with seizure reduction (t212 = -2.74; P = .007). The findings in this study indicate that distributed pathology in TLE may occur in brain networks connected to the hippocampal epicenter. Connectivity to these same networks was associated with improvement following RNS. A network approach to TLE may reveal therapeutic targets outside the traditional target in the hippocampus.

Waveform Window #56: Bilateral Temporal Lobe Epilepsy Misdiagnosed as Nonepileptic Spells

Waveform Window #56: Bilateral Temporal Lobe Epilepsy Misdiagnosed as Nonepileptic Spells

ID: 218087 RNS for Medically Uncontrolled Bilateral Neocortical Temporal Lobe Epilepsy Confers Favorable Long-Term Seizure Control

Patients with refractory neocortical temporal lobe epilepsy are challenging surgical candidates. Preoperative evaluation often fails to accurately localize SOZs, which necessitates the use of intracranial electroencephalography (iEEG). Furthermore, once SOZ can be defined, patients are typically not candidates for resective surgery. We present a retrospective case series of our experience with diagnosis and management of “bilateral neocortical temporal lobe epilepsy” (bnTLE) treated with responsive neurostimulation (RNS).?

Unexpected cardiorespiratory findings postictally and at rest weeks prior to SUDEP.

Mechanisms underlying sudden unexpected death in epilepsy (SUDEP) are unclear, but autonomic disorders are thought to play a critical role. However, those dysfunctions have mainly been reported in the peri-ictal context of generalized tonic-clonic seizures. Here, we explored whether heart rate variability (HRV), heart rate (HR), and breathing rate (BR) changes could be observed perictally during focal seizures with or without impaired awareness as well as interictally to assess the risk of SUDEP. We report the case of a 33-year-old patient with drug-resistant bilateral temporal lobe epilepsy who died at home probably from an unwitnessed nocturnal seizure ("probable SUDEP"). Ictal and interictal HRV as well as postictal cardiorespiratory analyses were conducted to assess autonomic functions and overall SUDEP risk. The SUDEP patient was compared to two living male patients from our local database matched for age, sex, and location of the epileptic focus. Interictal HRV analysis showed that all sleep HRV parameters and most awake HRV parameters of the SUDEP patient were significantly lower than those of our two control subjects with bitemporal lobe epilepsy without SUDEP (p < 0.01). In two focal with impaired awareness seizures (FIAS) of the SUDEP patient, increased postictal mean HR and reduced preictal mean high frequency signals (HF), known markers of increased seizure severity in convulsive seizures, were seen postictally. Furthermore, important autonomic instability and hypersensitivity were seen through fluctuations in LF/HF ratio following two seizures of the SUDEP patient, with a rapid transition between sympathetic and parasympathetic activity. In addition, a combination of severe hypopnea (202 s) and bradycardia (10 s), illustrating autonomic dysfunction, was found after one of the SUDEP patient's FIAS. The unusual cardiorespiratory and HRV patterns found in this case indicated autonomic abnormalities that were possibly predictive of an increased risk of SUDEP. It will be interesting to perform similar analyses in other SUDEP cases to see whether our findings are anecdotal or instead suggestive of reliable biomarkers of high SUDEP risk in focal epilepsy, in particular focal with or without impaired awareness seizures.

Hippocampal volumetry to determine the resection side in patients with intractable non-lesional bilateral temporal lobe epilepsy

Bilateral Temporal lobe epilepsy (BTLE) cases may result in poor surgical outcomes due to the difficulty in determining/localizing the epileptogenic zone. In this study, we investigated whether hippocampal volume (HV) would be useful for the determination of the best resection side in BTLE. Eighteen cases of BTLE determined by a scalp video electroencephalogram (SVEEG) underwent resection via intracranial electroencephalography (IVEEG). Patients with lesions or semiologically determined focus lateralization were excluded. In addition to SVEEG, an epilepsy protocol magnetic resonance imaging (MRI) including hippocampus fluid-attenuated inversion recovery (FLAIR) and HV, 18F-fluorodeoxyglucose positron emission tomography (FDG-PET), single-photon emission computed tomography with 123I-iomazenil (IMZ-SPECT), and magnetoencephalography (MEG) were performed for the preoperative evaluation of the lateralization. The resection side was determined based on the IVEEG results, and the seizure outcome at two years postoperatively was classified as either a well-controlled seizure outcome (Engel class I), or residual (classes II–V). We used a Fisher's exact test to compare the concordance between the determination of the epileptic focus by each modality and the resected side where patients achieved a well-controlled seizure outcome. Seizures were well controlled in 9/18 patients after surgery. Eight out of 11 patients (72.7%), in whom the HV results (strongly atrophic side) and the resection side were matched, had well-controlled seizure outcomes (P = 0.0498). The concordance of other presurgical evaluations with the resection side was not significantly related to a well-controlled seizure outcome. HV may be a useful method to determine the optimal resection side of the epileptic focus/foci in cases of suspected BTLE.

Surgical outcomes in patients with drug-resistant bilateral temporal lobe epilepsy confirmed via magnetic resonance imaging

Introduction. In patients with drug-resistant temporal lobe epilepsy (TLE), surgical treatment is aimed to resect an epileptogenic zone (EZ) followed by seizure control. Despite complicated EZ location, surgical resection should be considered as a treatment of choice in bilateral TLE.&#x0D; Objective: to evaluate surgical outcomes and factors contributing to outcomes in patients with drug-resistant bilateral TLE confirmed via magnetic resonance imaging.&#x0D; Materials and methods. The study included patients with unilateral (n = 50) and bilateral (n = 50) temporal lobe involvement. The results of surgical treatment were evaluated according to the classification of J. Engel (1993).&#x0D; Results. Favorable outcomes of surgical treatment (Engel I and Engel II) in the group with unilateral temporal lobe involvement were found in 98% of patients after 12 months, in 88% after 24 months, and in 100% after 48 and 60 months after surgery. In the group with bilateral temporal lobe involvement outcomes of surgical treatment were favorable in 41% of patients after 12 months, in 50% after 24 months, in 39% after 48 months, and in 50% of patients after 60 months post-surgery.&#x0D; Conclusion. Early onset, burdened perinatal history, and MRI-confirmed left temporal lobe involvement contribute to the poor outcome (Engel III and Engel IV) in the bilateral TLE group. Engel I outcomes were more common in the patients with unilateral TLE while Engel IIIV outcomes were more common in the patients with bilateral TLE.

Outcome in Bilateral Temporal Lobe Epilepsy After Treatment With Vagus Nerve Stimulation

The most common type of therapy-resistant epilepsy is temporal lobe epilepsy (TLE). Unilateral TLE usually has a favourable prognosis with resective surgery. However, surgery is usually not considered in cases of bilateral temporal lobe epilepsy (bi-TLE) which occurs in 10–20% of patients with TLE. Vagus nerve stimulation (VNS) is approved as a palliative therapeutic option. The outcome of treating bi-TLE with VNS is unknown. Our study evaluates the effect of VNS on the reduction of seizure frequency in therapy-resistant epilepsy patients with biTLE.

Bilateral temporal lobe epilepsy: How many seizures are required in chronic ambulatory electrocorticography to estimate the laterality ratio? (S7.010)

Bilateral temporal lobe epilepsy: How many seizures are required in chronic ambulatory electrocorticography to estimate the laterality ratio? (S7.010)

Temporal lobe epilepsy lateralisation and surgical outcome prediction using diffusion imaging

ObjectiveWe sought to augment the presurgical workup of medically refractory temporal lobe epilepsy by creating a supervised machine learning technique that uses diffusion-weighted imaging to classify patient-specific seizure onset laterality...

Low-frequency stimulation of a fiber tract in bilateral temporal lobe epilepsy

ObjectivePharmacoresistant bilateral mesial temporal lobe epilepsy often implies poor resective surgical candidacy. Low-frequency stimulation of a fiber tract connected to bilateral hippocampi, the fornicodorsocommissural tract, has been shown to be safe and efficacious in reducing seizures in a previous short-term study. Here, we report a single-blinded, within-subject control, long-term deep-brain stimulation trial of low-frequency stimulation of the fornicodorsocommissural tract in bilateral mesial temporal lobe epilepsy. Outcomes of interest included safety with respect to verbal memory scores and reduction of seizure frequency. MethodsOur enrollment goal was 16 adult subjects to be randomized to 2-Hz or 5-Hz low-frequency stimulation of the fornicodorsocommissural tract starting at 2 mA. The study design consisted of four two-month blocks of stimulation with a 50%-duty cycle, alternating with two-month blocks of no stimulation. ResultsWe terminated the study after enrollment of five subjects due to slow accrual. Fornicodorsocommissural tract stimulation elicited bilateral hippocampal evoked responses in all subjects. Three subjects underwent implantation of pulse generators and long-term low-frequency stimulation with mean monthly seizures of 3.14 ± 2.67 (median 3.0 [IQR 1–4.0]) during stimulation-off blocks, compared with 0.96 ± 1.23 (median 1.0 [IQR 0–1.0]) during stimulation-on blocks (p = 0.0005) during the blinded phase. Generalized Estimating Equations showed that low-frequency stimulation reduced monthly seizure-frequency by 0.71 per mA (p < 0.001). Verbal memory scores were stable with no psychiatric complications or other adverse events. SignificanceThe results demonstrate feasibility of stimulating both hippocampi using a single deep-brain stimulation electrode in the fornicodorsocommissural tract, efficacy of low-frequency stimulation in reducing seizures, and safety as regards verbal memory.

A simplified depth implantation approach in bitemporal lobe epilepsy

Background: Up to 73.0% of patients with bilateral temporal lobe epilepsy (BTLE) on scalp electroencephalogram (EEG) were found to have unilateral temporal seizure onset via invasive EEG monitoring (iEEG) and 58% of them achieved good surgical outcome. However, iEEG in resource- limited countries is limited by cost. We aimed to present the surgical outcome of a simplified and cost- effective 2-electrode bilateral hippocampal depth implantation strategy in 7 cases with bilateral temporal lobe epilepsy based on scalp EEG and unilateral mesial temporal sclerosis (MTS). Methods: Total 7 cases who underwent epilepsy surgery were reviewed. All patients underwent 2-stage evaluation of video-EEG monitoring followed by intracranial monitoring. A simplified 2-depth electrode implantation strategy was used, targeting the bilateral anterior hippocampus. Results: All 7 patients had interictal bilateral independent temporal epileptiform discharges. Four had bilateral temporal ictal onset on scalp EEG and 3 with ictal onset contralateral to the MTS. With iEEG, 4 patients (57.1%) were confirmed to be unilateral TLE, concordant with the MTS, and 3 patients (42.9%) had true BTLE. All 7 patients underwent anterior temporal lobectomy, ipsilateral to the side of MTS. Four patients (57.1%) achieved Engel I surgical outcome, of which 3/4 (75.0%) were patients with unilateral TLE. For those with true BTLE, 2/3 (66.7%) achieved favourable surgical outcome (Engel I and II). Conclusions: This simplified two-electrode implantation strategy is effective in lateralization of TLE in patients with BTLE and more affordable to those in resource-limited countries.

Bilateral temporal lobe epilepsy: How many seizures are required in chronic ambulatory electrocorticography to estimate the laterality ratio?

This study was undertaken to measure the duration of chronic electrocorticography (ECoG) needed to attain stable estimates of the seizure laterality ratio in patients with drug-resistant bilateral temporal lobe epilepsy (BTLE). We studied 13 patients with drug-resistant BTLE who were implanted for at least 1year with a responsive neurostimulation device (RNS System) that provides chronic ambulatory ECoG. Bootstrap analysis and nonlinear regression were applied to model the relationship between chronic ECoG duration and the probability of capturing at least one seizure. Laterality of electrographic seizures in chronic ECoG was compared with the seizure laterality ratio from Phase 1scalp video-electroencephalographic (vEEG) monitoring. The Kaplan-Meier estimator was used to evaluate time to seizure laterality ratio convergence. Seizure laterality ratios from Phase 1scalp vEEG monitoring correlated poorly with those from RNS chronic ECoG (r=.31, p=.30). Across the 13 patients, average electrographic seizure frequencies ranged from 1.4seizures/month to 5.1seizures/day. A 50% probability of recording at least one electrographic seizure required 9.1days of chronic ECoG, and 90% probability required 44.3days of chronic ECoG. A median recording duration of 150.9days (5months), corresponding to a median of 16seizures, was needed before confidence intervals for the seizure laterality ratio reliably contained the long-term value. The median recording duration before the point estimate of the seizure laterality ratio converged to a stationary value was 236.8days (7.9months). RNS chronic ECoG overcomes temporal sampling limitations intrinsic to inpatient Phase 1 vEEG evaluations. In patients with drug-resistant BTLE, approximately 8months of chronic RNS ECoG are needed to precisely estimate the seizure laterality ratio, with 75% of people with BTLE achieving convergence after 1 year of RNS recording. For individuals who are candidates for unilateral resection based on seizure laterality, optimized recording duration may help avert morbidity associated with delay to definitive treatment.

Hippocampal-ANT connectivity and ANT DBS: Circadian trends and response to stimulation

Abstract Although hippocampal (HC)-anterior nucleus of the thalamus (ANT) interactions are implicated in limbic epilepsy, their dynamics over the circadian cycle and following ANT deep brain stimulation (DBS) remain unclear. We used ultra-long, ambulatory, HC and ANT intracranial electroencephalographic recordings to describe HC-ANT connectivity in a patient with bilateral temporal lobe epilepsy. The patient was implanted with the investigational Medtronic Summit RC+S ™ sensing and stimulating DBS device. Electrodes were implanted into the long axis of the hippocampus and ANT bilaterally. Therapeutic stimulation was delivered to the ANT. HC-ANT coherence was calculated in the Berger bands (4-125 Hz) in 10 second segments from one month of baseline recordings and from a three week period of night-off stimulation that followed a month of continuous low frequency ANT stimulation (2Hz). Only coherence measurements wherein both contacts had spectral peaks in the relevant band, without seizures, spikes, or stimulation, were analyzed. Coherence values over the circadian cycle were compared across hemispheres and between baseline and post-stimulation periods. At baseline, concurrent spectral peaks in HC and ANT occurred across the circadian cycle, primarily in the high beta and low gamma frequency bands bilaterally, with the less epileptogenic, right hemisphere showing significantly greater high beta coherence (Wilcoxon Rank-Sum, n1 = 2638, n2 = 2515, p < 0.0001). Post-stimulation, nighttime left HC-ANT high beta coherence did not change, but the central frequency of coherent high beta peaks did increase significantly (Wilcoxon Rank-Sum, n1 = 368, n2 = 492, p < 0.0001). Our finding that HC-ANT high beta coherence was decreased in the more epileptogenic hemisphere is consistent with reports of functional isolation of epileptogenic zone. The stimulation-associated change in central frequency at which beta peaks occurred, but not in overall magnitude of HC-ANT coherence, suggests that low frequency ANT-DBS influences the spectral composition of HC-ANT connectivity. Keywords: Deep brain stimulation, Connectivity, Epilepsy, Anterior nucleus of the thalamus

Epilepsy Personal Assistant Device-A Mobile Platform for Brain State, Dense Behavioral and Physiology Tracking and Controlling Adaptive Stimulation.

Epilepsy is one of the most common neurological disorders, and it affects almost 1% of the population worldwide. Many people living with epilepsy continue to have seizures despite anti-epileptic medication therapy, surgical treatments, and neuromodulation therapy. The unpredictability of seizures is one of the most disabling aspects of epilepsy. Furthermore, epilepsy is associated with sleep, cognitive, and psychiatric comorbidities, which significantly impact the quality of life. Seizure predictions could potentially be used to adjust neuromodulation therapy to prevent the onset of a seizure and empower patients to avoid sensitive activities during high-risk periods. Long-term objective data is needed to provide a clearer view of brain electrical activity and an objective measure of the efficacy of therapeutic measures for optimal epilepsy care. While neuromodulation devices offer the potential for acquiring long-term data, available devices provide very little information regarding brain activity and therapy effectiveness. Also, seizure diaries kept by patients or caregivers are subjective and have been shown to be unreliable, in particular for patients with memory-impairing seizures. This paper describes the design, architecture, and development of the Mayo Epilepsy Personal Assistant Device (EPAD). The EPAD has bi-directional connectivity to the implanted investigational Medtronic Summit RC+STM device to implement intracranial EEG and physiological monitoring, processing, and control of the overall system and wearable devices streaming physiological time-series signals. In order to mitigate risk and comply with regulatory requirements, we developed a Quality Management System (QMS) to define the development process of the EPAD system, including Risk Analysis, Verification, Validation, and protocol mitigations. Extensive verification and validation testing were performed on thirteen canines and benchtop systems. The system is now under a first-in-human trial as part of the US FDA Investigational Device Exemption given in 2018 to study modulated responsive and predictive stimulation using the Mayo EPAD system and investigational Medtronic Summit RC+STM in ten patients with non-resectable dominant or bilateral mesial temporal lobe epilepsy. The EPAD system coupled with an implanted device capable of EEG telemetry represents a next-generation solution to optimizing neuromodulation therapy.

Responsive Neurostimulation of the Mesial Temporal White Matter in Bilateral Temporal Lobe Epilepsy.

Responsive neuromodulation (RNS) is a treatment option for patients with medically refractory bilateral mesial temporal lobe epilepsy (MTLE). A paucity of data exists on the feasibility and clinical outcome of hippocampal-sparing bilateral RNS depth lead placements within the parahippocampal white matter or temporal stem. To evaluate seizure reduction outcomes with at least a 1-yr follow-up in individuals with bilateral MTLE undergoing hippocampus-sparing implantation of RNS depth leads. A retrospective analysis of prospectively collected data was performed on patients at our institution with bilateral MTLE who were implanted with RNS depth leads along the longitudinal extent of bitemporal parahippocampal white matter or temporal stem. Baseline and postoperative seizure frequency, previous surgical interventions, and postimplantation electrocorticography and stimulation data were analyzed. Ten patients were included in the study (7 male, 3 female). Overall seizure frequency declined by a median 44.25% at 3.13 yr (standard deviation 3.31) postimplantation. Four patients (40%) achieved 50% responder rate at latest follow-up. Two of four patients with focal onset bilateral tonic-clonic seizures became completely seizure-free. Forty percent of patients were previously implanted with a vagus nerve stimulator, and 20% underwent a prior temporal lobectomy. All depth lead placements were confirmed as radiographically located in the parahippocampal white matter or temporal stem without hippocampus violation. There were no cases of lead malposition. Extrahippocampal or temporal stem white matter targeting during RNS surgery for bitemporal MTLE is feasible and allows for electrographic seizure detection. Larger controlled studies with longer follow-up are needed to validate these preliminary findings.

The contribution of sphenoidal electrodes placed under fluoroscopy in lateralization of bilateral refractory temporal lobe epilepsy: a clinical study

Aim: The aim of this study is to investigate the contribution of sphenoidal electrodes placed under fluoroscopic guidance to scalp electrodes, in the lateralization of temporal ictal onsets in bilateral refractory temporal lobe epilepsy. Also we determine the actual locations of sphenoidal electrodes by computerized tomography. Materials and Methods: We performed a prospective study on 10 patients with intractable epilepsy who has underwent sphenoidal electrode placement from 2010 to 2012. Refractory temporal lobe epilepsy patients whose localization and lateralization of epileptic focus couldn’t established with scalp EEG, or patients diagnosed bitemporal epilepsy with bitemporal seizure activity in video-EEG but no seizure onset identified, were evaluated. Sphenoidal electrodes placed double-sided to patients under sedation in the operating room. The control of the sphenoidal electrodes’ last position and several parameters displayed with 3D tomography. Patients monitorized at video-EEG unit. Simultaneously sphenoidal electrodes and scalp electrodes recordings obtained. Sphenoidal electrode lateralization results are compared with MRI, PET, SCALP EEG lateralization. Results: The utility rate of sphenoidal electrode recordings were found to be 28.1%. 2 of 10 cases lateralized were localized, 4 of 8 patients were lateralized by sphenoidal electrodes. Conclusion: Sphenoidal electrodes and scalp electrodes are similar in their ability to detect seizures. The optimal placement of sphenoidal electrodes with our technique provided additional localizing and lateralizing information in this series.

Probing circuit of Papez with stimulation of anterior nucleus of the thalamus and hippocampal evoked potentials

PurposeDespite documented clinical effectiveness, deep brain stimulation (DBS) therapy for drug-resistant epilepsy rarely yields long-term seizure free outcomes. MethodsThis pilot study in five patients investigated circuit of Papez evoked potentials (EPs) using hippocampal sensing during anterior nucleus of the thalamus (ANT) electrical stimulation. We hypothesize that hippocampal EP is a potential biomarker that could be useful for ANT electrode targeting and improving seizure reduction. We obtained bilateral circuit of Papez EPs in five patients with bilateral temporal lobe epilepsy (TLE). The circuit of Papez EPs were measured and assessed by signal amplitude. Volumetric analysis of relevant mesial temporal structures and ANT stimulation analysis was performed on immediate post-implantation images. ResultsThe patient with the most favorable seizure outcome, which meant long-term seizure reduction greater than 50 % compared to baseline, had strong bilateral EPs and normal hippocampal structure. Conversely, those without clinical benefit with ANT DBS had absent or weak bilateral EPs as well as MRI findings consistent with mesial temporal sclerosis (MTS). ConclusionThe data support the hypothesis that hippocampal EPs with ANT stimulation may be used to as a surrogate marker to probe circuit of Papez and predict ANT DBS efficacy.

Hippocampal and Thalamic DBS for Bilateral Temporal Lobe Epilepsy

Hippocampal and Thalamic DBS for Bilateral Temporal Lobe Epilepsy

Ictal High-Frequency Oscillation for Lateralizing Patients With Suspected Bitemporal Epilepsy Using Wavelet Transform and Granger Causality Analysis.

Identifying lateralization of bilateral temporal lobe epilepsy (TLE) is a challenging issue; scalp electroencephalography (EEG) and routine band electrocorticography (ECoG) fail to reveal the epileptogenic focus for further temporal lobectomy treatment. High-frequency oscillations (HFOs) can be utilized as a biomarker for lateralizing the onset zone in suspected bitemporal epilepsy. Except subjective vision detect the HFOs, objective verification should be performed to raise the accuracy. In the present research, we prospectively studied 10 patients with refractory temporal seizures and who underwent ECoG with wide-band frequency amplifiers (2,048 Hz); all patients had a class I outcome after temporal resection. Pre- and ictal HFOs will be analyzed by wavelet transform (WT) and Granger causality (GC) to objectively verify lateralization of the seizure onset zone (SOZ). WT analysis showed ictal HFOs in 10 patients mainly covered from 80 to 115 Hz (average, 92.59 ± 10.23 Hz), and there was distinct bandpass boundary between pre-ictal HFOs and ictal HFOs. GC analysis showed five patients (2, 4, 5, 6, and 7), no matter the pre-ictal or ictal state, had the highest GC degree in SOZ itself. The remaining patients (1, 3, 8, 9, and 10) had the highest GC degree in SOZ with its adjacent regions in the pre-ictal and ictal stages. GC analysis further confirmed the result of the WT and suggested HFOs are initiated and propagated in the local brain region mainly, afterward, transmitting to adjacent brain regions. These results indicated that the combination of WT and GC analyses significantly contributes to accurate lateralization in patients with suspected bitemporal epilepsy.

Autobiographical memory in epileptic patients after temporal lobe resection or bitemporal hippocampal sclerosis.

The human hippocampus is believed to be a crucial node in the neural network supporting autobiographical memory retrieval. Structural mesial temporal damage associated with temporal lobe epilepsy (TLE) provides an opportunity to systematically investigate and better understand the local and distal functional consequences of mesial temporal damage in the engagement of the autobiographical memory network. We examined 19 TLE patients (49.21 ± 11.55years; 12 females) with unilateral mesial TLE (MTLE; 12 with anterior temporal lobe resection: 6 right MTLE, 6 left MTLE) or bilateral mesial TLE (7 BMTLE) and 18 matched healthy subjects. We used functional MRI (fMRI) with an adapted autobiographical memory paradigm and a specific neuropsychological test (Autobiographical Memory Interview, AMI). While engaged in the fMRI autobiographical memory paradigm, all groups activated a large fronto-temporo-parietal network. However, while this network was left lateralized for healthy participants and right MTLE patients, left MTLE and patients with BMTLE also showed strong activation in right temporal and frontal regions. Moreover, BMTLE and left MTLE patients also showed significant mild deficits in episodic autobiographical memory performance measured with the AMI test. The right temporal and extra-temporal fMRI activation, along with the impairment in autobiographical memory retrieval found in left MTLE and BMTLE patients suggest that alternate brain areas-other than the hippocampus-may also support this process, possibly due to neuroplastic effects.