Left Hemisphere Lateralization of Epileptic Focus Can Be More Frequent in Temporal Lobe Epilepsy Surgical Patients with No Consensus Associated with Depression Lateralization.

Temporal lobe epilepsy (TLE) is considered to be the most common form of epilepsy, and it has been seen that most patients are refractory to antiepileptic drugs. A strong association of this ailment has been established with psychiatric comorbidities, primarily mood and anxiety disorders. The side of epileptogenic may contribute to depressive and anxiety symptoms; thus, in this study, we performed a systematic review to evaluate the prevalence of depression in TLE in surgical patients. The literature search was performed using PubMed/Medline, Web of Science, and PsycNet to gather data from inception until January 2019. The search strategy was related to TLE, depressive disorder, and anxiety. After reading full texts, 14 articles meeting the inclusion criteria were screened. The main method utilized for psychiatric diagnosis was Diagnostic and Statistical Manual of Mental Disorders/Structured Clinical Interview for DSM. However, most studies failed to perform the neuropsychological evaluation. For those with lateralization of epilepsy, focus mostly occurred in the left hemisphere. For individual depressive diagnosis, 9 studies were evaluated, and 5 for anxiety. Therefore, from the data analyzed in both situations, no diagnosis was representative in preoperative and postoperative cases. In order to estimate the efficacy of surgery in the psychiatry episodes and its relation to seizure control, the risk of depression and anxiety symptoms in epileptic patients need to be determined before surgical procedures. Rigorous preoperative and postoperative evaluation is essential for psychiatry conditions in patients with refractory epilepsy candidates for surgery.

Intraoperative electrocorticography-guided microsurgical management for patients with onset of supratentorial neoplasms manifesting as epilepsy: a review of 65 cases.

AIM: We reviewed the surgical procedures guided by intraoperative electrocorticography and outcome of 65 patients with onset of supratentorial neoplasms manifesting as epilepsy. METHOD: Clinical data were obtained for 65 patients with supratentorial neoplasms who received surgery, with the aid of intraoperative electrocorticography to screen epileptogenic foci before and after removal of neoplasms, and depth electrodes when needed. According to electrocorticography findings, appropriate surgical procedures were performed to treat the epileptogenic foci. In the control group, 72 patients received simple lesionectomy. Postoperative seizure outcomes were documented and analysed retrospectively. RESULTS: In the case group, 33 patients received lesionectomy only, while the other 32 patients underwent intraoperative electrocorticography-guided tailored epilepsy surgery. In total, 57 patients (87.7%) in the case group and 38 patients (52.8%) in the control group were seizure-free (Engel Class I). Comparing outcomes of patients with temporal lesions between the two groups, 80.0% patients (12/15) in the case group and 20.0% (3/15) in the control group were seizure-free. Furthermore, comparing the seizure outcomes of patients who finally underwent tailored epilepsy surgery and simple lesionectomy (33 after electrocorticography and 72 without electrocorticography), intraoperative electrocorticography-guided tailored epilepsy surgery demonstrated superiority over lesionectomy (Engel Class I; 87.5% vs. 63.8%, respectively). CONCLUSIONS: Electrocorticography plays an important role in the localisation of epileptogenic foci and evaluation of the effects of microsurgical procedures intraoperatively. Isolated lesionectomy is not usually sufficient for better postoperative seizure outcome. In addition, for patients with temporal tumours, especially in the non-dominant hemisphere, a more aggressive strategy, such as an anterior temporal lobectomy, is recommended.

Evaluation of focus laterality in temporal lobe epilepsy: a quantitative study comparing double inversion-recovery MR imaging at 3T with FDG-PET.

PURPOSE: To quantitatively compare the diagnostic capability of double inversion-recovery (DIR) with F-18 fluorodeoxyglucose positron emission tomography (FDG-PET) for detection of seizure focus laterality in temporal lobe epilepsy (TLE). METHODS: This study was approved by the institutional review board, and written informed consent was obtained. Fifteen patients with TLE and 38 healthy volunteers were enrolled. All magnetic resonance (MR) images were acquired using a 3T-MRI system. Voxel-based analysis (VBA) was conducted for FDG-PET images and white matter segments of DIR images (DIR-WM) focused on the whole temporal lobe (TL) and the anterior part of the temporal lobe (ATL). Distribution of hypometabolic areas on FDG-PET and increased signal intensity areas on DIR-WM were evaluated, and their laterality was compared with clinically determined seizure focus laterality. Correct diagnostic rates of laterality were evaluated, and agreement between DIR-WM and FDG-PET was assessed using κ statistics. KEY FINDINGS: Increased signal intensity areas on DIR-WM were located at the vicinity of the hypometabolic areas on FDG-PET, especially in the ATL. Correct diagnostic rates of seizure focus laterality for DIR-WM (0.80 and 0.67 for the TL and the ATL, respectively) were slightly higher than those for FDG-PET (0.67 and 0.60 for the TL and the ATL, respectively). Agreement of laterality between DIR-WM and FDG-PET was substantial for the TL and almost perfect for the ATL (κ = 0.67 and 0.86, respectively). SIGNIFICANCE: High agreement in localization between DIR-WM and FDG-PET and nearly equivalent detectability of them show us an additional role of MRI in TLE.

Interictal localization of the epileptogenic zone: Utilizing the observed resonance behavior in the spectral band of surrounding inhibition.

Introduction: The gold standard for identification of the epileptogenic zone (EZ) continues to be the visual inspection of electrographic changes around seizures' onset by experienced electroencephalography (EEG) readers. Development of an epileptogenic focus localization tool that can delineate the EZ from analysis of interictal (seizure-free) periods is still an open question of great significance for improved diagnosis (e.g., presurgical evaluation) and treatment of epilepsy (e.g., surgical outcome). Methods: We developed an EZ interictal localization algorithm (EZILA) based on novel analysis of intracranial EEG (iEEG) using a univariate periodogram-type power measure, a straight-forward ranking approach, a robust dimensional reduction method and a clustering technique. Ten patients with temporal and extra temporal lobe epilepsies, and matching the inclusion criteria of having iEEG recordings at the epilepsy monitoring unit (EMU) and being Engel Class I ≥12 months post-surgery, were recruited in this study. Results: In a nested k-fold cross validation statistical framework, EZILA assigned the highest score to iEEG channels within the EZ in all patients (10/10) during the first hour of the iEEG recordings and up to their first typical clinical seizure in the EMU (i.e., early interictal period). To further validate EZILA's performance, data from two new (Engel Class I) patients were analyzed in a double-blinded fashion; the EZILA successfully localized iEEG channels within the EZ from interictal iEEG in both patients. Discussion: Out of the sampled brain regions, iEEG channels in the EZ were most frequently and maximally active in seizure-free (interictal) periods across patients in specific narrow gamma frequency band (∼60-80 Hz), which we have termed focal frequency band (FFB). These findings are consistent with the hypothesis that the EZ may interictally be regulated (controlled) by surrounding inhibitory neurons with resonance characteristics within this narrow gamma band.

Intracranial arachnoid cysts and epilepsy in children: Should this be treated surgically? Our 29-year experience and review of the literature.

INTRODUCTION AND OBJECTIVE: Arachnoid cysts (ACs) are relatively frequent lesions related to different neurological symptoms, being mostly incidentally diagnosed. This study aims to clarify whether AC surgery in epileptic patients is useful in their treatment. MATERIAL AND METHODS: The patients registered in the database of the Neuropediatrics Section from May 1990 to August 2019 are analyzed retrospectively. Patients in whom the diagnosis of ACs and epilepsy coincide are studied. The location, size and number of ACs, neurological development, age at diagnosis, follow-up time, the performance of surgery on the cyst, evolution, anatomical relationship between brain electrical activity and location of AC, and type of epilepsy are analyzed. RESULTS: After analyzing the database, we found 1881 patients diagnosed with epilepsy, of which 25 had at least one intracranial AC. In 9 of the patients, cerebral or genetic pathologies were the cause of epilepsy. Of the other 16, only 2 patients showed that the type of epilepsy and the epileptogenic focus coincided with the location of the AC; one of them was surgically treated without success, and the other one remained asymptomatic without receiving medical or surgical treatment. CONCLUSIONS: Although it is necessary to design a prospective study to establish causality, the results of our research and the available literature suggest that there is no causal relationship between the presence of ACs and epilepsy. The study and treatment of these patients should be carried out in a multidisciplinary epilepsy surgery unit, without initially assuming that the AC is the cause of epilepsy.

MEG Node Degree Differences in Patients with Focal Epilepsy vs. Controls-Influence of Experimental Conditions.

Drug-resistant epilepsy can be most limiting for patients, and surgery represents a viable therapy option. With the growing research on the human connectome and the evidence of epilepsy being a network disorder, connectivity analysis may be able to contribute to our understanding of epilepsy and may be potentially developed into clinical applications. In this magnetoencephalographic study, we determined the whole-brain node degree of connectivity levels in patients and controls. Resting-state activity was measured at five frequency bands in 15 healthy controls and 15 patients with focal epilepsy of different etiologies. The whole-brain all-to-all imaginary part of coherence in source space was then calculated. Node degree was determined and parcellated and was used for further statistical evaluation. In comparison to controls, we found a significantly higher overall node degree in patients with lesional and non-lesional epilepsy. Furthermore, we examined the conditions of high/reduced vigilance and open/closed eyes in controls, to analyze whether patient node degree levels can be achieved. We evaluated intraclass-correlation statistics (ICC) to evaluate the reproducibility. Connectivity and specifically node degree analysis could present new tools for one of the most common neurological diseases, with potential applications in epilepsy diagnostics.

Intracranial arachnoid cysts and epilepsy in children: Should this be treated surgically? Our 29-year experience and review of the literature.

INTRODUCTION AND OBJECTIVE: Arachnoid cysts (ACs) are relatively frequent lesions related to different neurological symptoms, being mostly incidentally diagnosed. This study aims to clarify whether AC surgery in epileptic patients is useful in their treatment. MATERIAL AND METHODS: The patients registered in the database of the Neuropediatrics Section from May 1990 to August 2019 are analyzed retrospectively. Patients in whom the diagnosis of ACs and epilepsy coincide are studied. The location, size and number of ACs, neurological development, age at diagnosis, follow-up time, the performance of surgery on the cyst, evolution, anatomical relationship between brain electrical activity and location of AC, and type of epilepsy are analyzed. RESULTS: After analyzing the database, we found 1881 patients diagnosed with epilepsy, of which 25 had at least one intracranial AC. In 9 of the patients, cerebral or genetic pathologies were the cause of epilepsy. Of the other 16, only 2 patients showed that the type of epilepsy and the epileptogenic focus coincided with the location of the AC; one of them was surgically treated without success, and the other one remained asymptomatic without receiving medical or surgical treatment. CONCLUSIONS: Although it is necessary to design a prospective study to establish causality, the results of our research and the available literature suggest that there is no causal relationship between the presence of ACs and epilepsy. The study and treatment of these patients should be carried out in a multidisciplinary epilepsy surgery unit, without initially assuming that the AC is the cause of epilepsy.

Detection of focal electroencephalogram signals using higher-order moments in EMD-TKEO domain.

Detection of epileptogenic focus based on electroencephalogram (EEG) signal screening is an important pre-surgical step to remove affected regions inside the human brain. Considering the fact above, in this work, a novel technique for detection of focal EEG signals is proposed using a combination of empirical mode decomposition (EMD) and Teager-Kaiser energy operator (TKEO). EEG signals belonging to focal (Fo) and non-focal (NFo) groups were at first decomposed into a set of intrinsic mode functions (IMFs) using EMD. Next, TKEO was applied on each IMF and two higher-order statistical moments namely skewness and kurtosis were extracted as features from TKEO of each IMF. The statistical significance of the selected features was evaluated using student's t-test and based on the statistical test, features from first three IMFs which show very high discriminative capability were selected as inputs to a support vector machine classifier for discrimination of Fo and NFo signals. It was observed that the classification accuracy of 92.65% is obtained in classifying EEG signals using a radial basis kernel function, which demonstrates the efficacy of proposed EMD-TKEO based feature extraction method for computer-based treatment of patients suffering from focal seizures.

Translational view: Ablative methods in in vivo epilepsy models.

New treatment approaches in epilepsy - such as novel antiepileptic drugs and neurostimulation - generally at first are assessed in animal models in regard to feasibility, efficacy and safety. The aim of this review was to elucidate and summarize the available literature on in vivo experimental studies on radiofrequency thermoablation and laser interstitial thermal therapy. We have found two in vivo studies on radiofrequency ablation of an acute seizure focus, one assessed the conventional transcranial and the other one a transvenous approach. All other studies focused on technical issues of functional ablation of brain structures assessing parameters such as maximal temperature and duration of thermal ablation as well as electrode devices. As the concept of functional ablation is evident - destruction of the epileptogenic focus as performed in "open" resective surgery - general "proof of concept" experiments do not seem to be necessary.

Experience-based SEEG planning: from retrospective data to automated electrode trajectories suggestions.

StereoElectroEncephaloGraphy (SEEG) is a minimally invasive technique that consists of the insertion of multiple intracranial electrodes to precisely identify the epileptogenic focus. The planning of electrode trajectories is a cumbersome and time-consuming task. Current approaches to support the planning focus on electrode trajectory optimisation based on geometrical constraints but are not helpful to produce an initial electrode set to begin with the planning procedure. In this work, the authors propose a methodology that analyses retrospective planning data and builds a set of average trajectories, representing the practice of a clinical centre, which can be mapped to a new patient to initialise planning procedure. They collected and analysed the data from 75 anonymised patients, obtaining 30 exploratory patterns and 61 mean trajectories in an average brain space. A preliminary validation on a test set showed that they were able to correctly map 90% of those trajectories and, after optimisation, they have comparable or better values than manual trajectories in terms of distance from vessels and insertion angle. Finally, by detecting and analysing similar plans, they were able to identify eight planning strategies, which represent the main tailored sets of trajectories that neurosurgeons used to deal with the different patient cases.

Intracranial arachnoid cysts and epilepsy in children: Should this be treated surgically? Our 29-year experience and review of the literature / Quistes aracnoideos intracraneales y epilepsia en niños: ¿Debemos tratarlos quirúrgicamente? Nuestra experiencia de 29 años y revisión de la literatura

Introduction and objective: Arachnoid cysts (ACs) are relatively frequent lesions related to different neurological symptoms, being mostly incidentally diagnosed. This study aims to clarify whether AC surgery in epileptic patients is useful in their treatment. Material and methods: The patients registered in the database of the Neuropediatrics Section from May 1990 to August 2019 are analyzed retrospectively. Patients in whom the diagnosis of ACs and epilepsy coincide are studied. The location, size and number of ACs, neurological development, age at diagnosis, follow-up time, the performance of surgery on the cyst, evolution, anatomical relationship between brain electrical activity and location of AC, and type of epilepsy are analyzed. Results: After analyzing the database, we found 1881 patients diagnosed with epilepsy, of which 25 had at least one intracranial AC. In 9 of the patients, cerebral or genetic pathologies were the cause of epilepsy. Of the other 16, only 2 patients showed that the type of epilepsy and the epileptogenic focus coincided with the location of the AC; one of them was surgically treated without success, and the other one remained asymptomatic without receiving medical or surgical treatment(AU)

Introducción y objetivo: Los quistes aracnoideos (QAs) son lesiones relativamente comunes relacionados con diferentes síntomas neurológicos, siendo diagnosticados de forma incidental en su mayoría. Este estudio tiene como objetivo aclarar si la cirugía sobre el QA en pacientes epilépticos es útil en su tratamiento. Material y métodos: Se analizan retrospectivamente los pacientes registrados en la base de datos de la Sección de Neuropediatría desde mayo de 1990 a agosto de 2019. Se estudian los pacientes en los que coincide el diagnóstico de QA y epilepsia. Se analiza la localización, tamaño y número de los QA, el desarrollo neurológico, edad al diagnóstico, tiempo de seguimiento, realización de cirugía sobre el QA, evolución, relación anatómica entre la actividad eléctrica cerebral y la localización del QA, así como el tipo de epilepsia. Resultados: Tras el análisis de la base de datos encontramos 1.881 pacientes diagnosticados de epilepsia, entre ellos 25 con al menos un QA intracraneal. En nueve de los pacientes la patología cerebral o genética por sí misma era causa de epilepsia. De los otros 16, únicamente en dos casos se evidenció que el tipo de epilepsia y el foco epileptogénico coincidían con la localización del QA; uno de ellos fue tratado quirúrgicamente sin éxito y el otro permaneció asintomático sin recibir tratamiento médico ni quirúrgico. Conclusiones: Aunque es necesario diseñar un estudio prospectivo para establecer causalidad, los resultados de nuestro trabajo y la literatura disponible sugieren que no hay relación causal entre la presencia de QAs y epilepsia. El estudio y tratamiento de estos pacientes debería ser completado en una unidad multidisciplinar de cirugía de la epilepsia, sin asumir de inicio que el QA es la causa de la epilepsia(AU)

Epileptic focus localization based on resting state interictal MEG recordings is feasible irrespective of the presence or absence of spikes.

OBJECTIVE: To investigate whether epileptogenic focus localization is possible based on resting state connectivity analysis of magnetoencephalographic (MEG) data. METHODS: A multivariate autoregressive (MVAR) model was constructed using the sensor space data and was projected to the source space using lead field and inverse matrix. The generalized partial directed coherence was estimated from the MVAR model in the source space. The dipole with the maximum information inflow was hypothesized to be within the epileptogenic focus. RESULTS: Applying the focus localization algorithm (FLA) to the interictal MEG recordings from five patients with neocortical epilepsy, who underwent presurgical evaluation for the identification of epileptogenic focus, we were able to correctly localize the focus, on the basis of maximum interictal information inflow in the presence or absence of interictal epileptic spikes in the data, with three out of five patients undergoing resective surgery and being seizure free since. CONCLUSION: Our preliminary results suggest that accurate localization of the epileptogenic focus may be accomplished using noninvasive spontaneous "resting-state" recordings of relatively brief duration and without the need to capture definite interictal and/or ictal abnormalities. SIGNIFICANCE: Epileptogenic focus localization is possible through connectivity analysis of resting state MEG data irrespective of the presence/absence of spikes.

Long-term outcome of epilepsy surgery: a retrospective study in a population of 379 cases.

We evaluated the long-term outcome of epilepsy surgery in drug-resistant epilepsy patients, and investigated preoperative factors associated with postoperative long-term surgical outcome. We performed a retrospective study of 379 patients who received epilepsy surgeries from 2000 to 2010. Patients had completed a minimum of 2-year and up to 12-year follow-up. Preoperative evaluations, surgical outcomes and clinical data of patients were collected and analyzed. We found that the epilepsy surgery was effective in drug-resistant patients and the long-term outcome of epilepsy surgery was satisfactory. The bipolar electro-coagulation could improve the surgical outcome when the epileptogenic focus was on the functional cortex. Results of the 2-year follow-up showed that preoperative seizure characteristics including the history of febrile seizure, seizure frequency, and location, quantity and range of seizure foci were significantly associated with the surgical outcome. The surgery procedure including the surgery type and the extent of resection also affected outcome. Abnormal head or hippocampus MRI, inconsistent results of preoperative investigations, seizure types, and pathology type might also be predictors of long-term surgical outcome.

Functional brain connectivity from EEG in epilepsy: seizure prediction and epileptogenic focus localization.

Today, neuroimaging techniques are frequently used to investigate the integration of functionally specialized brain regions in a network. Functional connectivity, which quantifies the statistical dependencies among the dynamics of simultaneously recorded signals, allows to infer the dynamical interactions of segregated brain regions. In this review we discuss how the functional connectivity patterns obtained from intracranial and scalp electroencephalographic (EEG) recordings reveal information about the dynamics of the epileptic brain and can be used to predict upcoming seizures and to localize the seizure onset zone. The added value of extracting information that is not visibly identifiable in the EEG data using functional connectivity analysis is stressed. Despite the fact that many studies have showed promising results, we must conclude that functional connectivity analysis has not made its way into clinical practice yet.