scholarly journals Recent developments in cognitive fMRI for temporal lobe epilepsy

2019 ◽  
Vol 33 (1) ◽  
pp. 30-36 ◽  
Author(s):  
Victor Schmidbauer ◽  
Silvia Bonelli
Keyword(s):  
Temporal Lobe Epilepsy ◽  
Temporal Lobe ◽  
Visual Memory ◽  
Imaging Modality ◽  
Memory Function ◽  
Brain Regions ◽  
Epileptogenic Zone ◽  
Brain Areas ◽  
Recent Developments ◽  
The Brain

AbstractEpilepsy is frequently accompanied by severe cognitive side effects. Temporal lobe epilepsy (TLE), and even successful surgical treatment, may affect cognitive function, in particular language as well as verbal and visual memory function. Epilepsy arising from the temporal lobe can be controlled surgically in up to 70% of patients. The goals of epilepsy surgery are to remove the brain areas generating the seizures without causing or aggravating neuropsychological deficits. This requires accurate localization of the brain areas generating the seizures (“epileptogenic zone”) and the areas responsible for motor and cognitive functions, such as language and memory (“essential brain regions”) during presurgical evaluation. In the past decades, functional magnetic resonance imaging (fMRI) has been increasingly used to noninvasively lateralize and localize not only primary motor and somatosensory areas, but also brain areas that are involved in everyday language and memory processes. The imaging modality also shows potential for predicting the effects of temporal lobe resection on language and memory function. Together with other MRI modalities, cognitive fMRI is a promising tool to improve surgical strategies tailored to individual patients with regard to functional outcome, by virtue of definition of epileptic cerebral areas that need to be resected and eloquent areas that need to be spared.The aim of this review is to provide an overview of recent developments and practical recommendations for the clinical use of cognitive fMRI in TLE.

scholarly journals Seizure Freedom After Epilepsy Surgery and Higher Baseline Cognition May Be Associated With a Negatively Correlated Epilepsy Network in Temporal Lobe Epilepsy

2021 ◽  
Vol 14 ◽  
Author(s):  
Elliot G. Neal ◽  
Mike R. Schoenberg ◽  
Stephanie Maciver ◽  
Yarema B. Bezchlibnyk ◽  
Fernando L. Vale
Keyword(s):  
Temporal Lobe Epilepsy ◽  
Temporal Lobe ◽  
Epilepsy Surgery ◽  
Memory Function ◽  
Brain Regions ◽  
Seizure Freedom ◽  
Epileptogenic Zone ◽  
Temporal Lobes ◽  
Scalp Eeg ◽  
The Brain

Background: Brain regions positively correlated with the epileptogenic zone in patients with temporal lobe epilepsy vary in spread across the brain and in the degree of correlation to the temporal lobes, thalamus, and limbic structures, and these parameters have been associated with pre-operative cognitive impairment and seizure freedom after epilepsy surgery, but negatively correlated regions have not been as well studied. We hypothesize that connectivity within a negatively correlated epilepsy network may predict which patients with temporal lobe epilepsy will respond best to surgery.Methods: Scalp EEG and resting state functional MRI (rsfMRI) were collected from 19 patients with temporal lobe epilepsy and used to estimate the irritative zone. Using patients’ rsfMRI, the negatively correlated epilepsy network was mapped by determining all the brain voxels that were negatively correlated with the voxels in the epileptogenic zone and the spread and average connectivity within the network was determined.Results: Pre-operatively, connectivity within the negatively correlated network was inversely related to the spread (diffuseness) of that network and positively associated with higher baseline verbal and logical memory. Pre-operative connectivity within the negatively correlated network was also significantly higher in patients who would go on to be seizure free.Conclusion: Patients with higher connectivity within brain regions negatively correlated with the epilepsy network had higher baseline memory function, narrower network spread, and were more likely to be seizure free after surgery.

scholarly journals Epileptogenic Zone Location of Temporal Lobe Epilepsy by Cross-Frequency Coupling Analysis

2021 ◽  
Vol 12 ◽  
Author(s):  
Xiaotong Liu ◽  
Fang Han ◽  
Rui Fu ◽  
Qingyun Wang ◽  
Guoming Luan
Keyword(s):  
Temporal Lobe Epilepsy ◽  
Temporal Lobe ◽  
Single Channel ◽  
Brain Networks ◽  
Brain Regions ◽  
Functional Network ◽  
Epileptogenic Zone ◽  
Coupling Analysis ◽  
Frequency Coupling ◽  
Cross Frequency Coupling

Epilepsy is a chronic brain disease with dysfunctional brain networks, and electroencephalography (EEG) is an important tool for epileptogenic zone (EZ) identification, with rich information about frequencies. Different frequency oscillations have different contributions to brain function, and cross-frequency coupling (CFC) has been found to exist within brain regions. Cross-channel and inter-channel analysis should be both focused because they help to analyze how epilepsy networks change and also localize the EZ. In this paper, we analyzed long-term stereo-electroencephalography (SEEG) data from 17 patients with temporal lobe epilepsy. Single-channel and cross-channel CFC features were combined to establish functional brain networks, and the network characteristics under different periods and the localization of EZ were analyzed. It was observed that theta–gamma phase amplitude coupling (PAC) within the electrodes in the seizure region increased during the ictal (p < 0.05). Theta–gamma and delta–gamma PAC of cross-channel were enhanced in the early and mid-late ictal, respectively. It was also found that there was a strong cross-frequency coupling state between channels of EZ in the functional network during the ictal, along with a more regular network than interictal. The accuracy rate of EZ localization was 82.4%. Overall, the combination of single-channel and multi-channel cross-band coupling analysis can help identify seizures and localize EZ for temporal lobe epilepsy. Rhythmic coupling reveals a relationship between the functional network and the seizure status of epilepsy.

Relationship between hippocampal subfields and Verbal and Visual memory function in Mesial Temporal Lobe Epilepsy patients

2021 ◽  
pp. 106700
Author(s):  
Sergio Eiji Ono ◽  
Maria Joana Mäder Joaquim ◽  
Arnolfo de Carvalho Neto ◽  
Luciano de Paola ◽  
Gustavo Rengel dos Santos ◽  
...  
Keyword(s):  
Temporal Lobe Epilepsy ◽  
Temporal Lobe ◽  
Visual Memory ◽  
Memory Function ◽  
Mesial Temporal Lobe Epilepsy ◽  
Hippocampal Subfields ◽  
Mesial Temporal Lobe

Neurophysiological phenotypes of pharmacoresistant temporal lobe epilepsy

2021 ◽  
pp. 9-12
Author(s):  
M. V. Aleksandrov ◽  
Y. V. Marchenko
Keyword(s):  
Surgical Treatment ◽  
Temporal Lobe Epilepsy ◽  
Temporal Lobe ◽  
Epileptic Focus ◽  
Bioelectrical Activity ◽  
Epileptogenic Zone ◽  
Invasive Monitoring ◽  
Ictal Activity ◽  
The Brain

Patients with a drug-resistant form of epilepsy can be treated by neurosurgery through the destruction or separation of the epileptic focus. If the results of clinical, neuro-imaging and neurophysiological methods are discordant, then the localization of the epileptogenic zone is performed based on the results of long-term invasive monitoring of the bioelectrical activity of the cortex and deep structures of the brain. The aim of this work was the retrospective analysis of the results of invasive monitoring of the bioelectrical activity of the brain to clarify the mechanisms of the formation of patterns of interictal and ictal activity in structural epilepsy. The study included 35 patients (18 men, 17 women) with drug-resistant temporal lobe epilepsy, who were treated at the Polenov Neurosurgical Institute. The examination included video-EEG monitoring, long-term invasive monitoring of bioelectrical activity of the cortex, and deep brain structures. The patients were divided into two groups according to the type of surgical treatment: 1) micro-surgical resection of the epileptic focus, including the zone of structural changes (24 patients); 2) stereotactic destruction of the amygdala-hippocampal complex (6 patients). The follow-up of the outcomes of the surgical treatment took place over 2-3 years. Depending on the results of the surgical treatment, the patients were divided into two groups: 1) patients with a favorable outcome (Engel 1–2) — 15 patients and 2) patients with no positive dynamics and a relatively poor outcome (Engel 3–4) — 15 patients. The results obtained showed that the patterns of interictal and ictal activity in their totality determine the neurophysiology, i.e the phenotype of temporal lobe epilepsy, reflecting the interference of pathogenetic and sanogenetic mechanisms. The localization of the epileptogenic zone should be based on the cumulative assessment of interictal and ictal activity. The presence of more than one focus of interictal activity, the secondary spread of epileptiform activity from the primary focus, are prognostically unfavorable factors.

scholarly journals Surgical and postmortem pathology studies: contribution for the investigation of temporal lobe epilepsy

2012 ◽  
Vol 70 (12) ◽  
pp. 945-952 ◽  
Author(s):  
Luís Otávio Sales Ferreira Caboclo ◽  
Rafael Scarpa Neves ◽  
Anaclara Prada Jardim ◽  
Ana Paula Andrade Hamad ◽  
Ricardo Silva Centeno ◽  
...  
Keyword(s):  
Temporal Lobe Epilepsy ◽  
Temporal Lobe ◽  
Response To Treatment ◽  
Mesial Temporal Sclerosis ◽  
Epileptogenic Zone ◽  
Postmortem Studies ◽  
Extensive Information ◽  
Long Term Prognosis ◽  
The Brain

Pathology studies in epilepsy patients bring useful information for comprehending the physiopathology of various forms of epilepsy, as well as aspects related to response to treatment and long-term prognosis. These studies are usually restricted to surgical specimens obtained from patients with refractory focal epilepsies. Therefore, most of them pertain to temporal lobe epilepsy (TLE) with mesial temporal sclerosis (MTS) and malformations of cortical development (MCD), thus providing information of a selected group of patients and restricted regions of the brain. Postmortem whole brain studies are rarely performed in epilepsy patients, however they may provide extensive information on brain pathology, allowing the analysis of areas beyond the putative epileptogenic zone. In this article, we reviewed pathology studies performed in epilepsy patients with emphasis on neuropathological findings in TLE with MTS and MCD. Furthermore, we reviewed data from postmortem studies and discussed the importance of performing these studies in epilepsy populations.

Multiple hippocampal transections for refractory pediatric mesial temporal lobe epilepsy: seizure and neuropsychological outcomes

2020 ◽  
Vol 26 (4) ◽  
pp. 379-388
Author(s):  
Ahmad Marashly ◽  
Jennifer Koop ◽  
Michelle Loman ◽  
Irene Kim ◽  
Mohit Maheshwari ◽  
...  
Keyword(s):  
Temporal Lobe Epilepsy ◽  
Temporal Lobe ◽  
Verbal Memory ◽  
Focal Epilepsy ◽  
Hippocampal Sclerosis ◽  
Neuropsychological Functioning ◽  
Memory Function ◽  
Seizure Outcome ◽  
Epileptogenic Zone ◽  
Seizure Propagation

OBJECTIVETemporal lobe epilepsy (TLE) is the most common focal epilepsy across adult and pediatric age groups. It is also the most amenable to surgery, with excellent long-term seizure outcome. Most TLE cases have an epileptogenic zone in the mesial temporal structures, namely the hippocampus. Resecting the dominant hippocampus has been shown to be associated with significant verbal memory deficits, especially in patients with intact verbal memory scores presurgically. Multiple hippocampal transection (MHT) is a relatively new surgical technique designed to interrupt the longitudinal hippocampal circuitry involved in seizure propagation yet preserve the circular fibers involved in memory function. This technique has been used to treat mesial TLE in both dominant- and nondominant-hemisphere cases, almost exclusively in adults. It has been applied to normal and sclerotic hippocampi.METHODSIn this study, information on 3 pediatric patients who underwent MHT for mesial TLE at Children’s Wisconsin between 2017 and 2018 is included. Clinical, electroencephalographic, and neuropsychological features and outcomes are described in detail.RESULTSMRI revealed a tumor in the amygdala with a normal hippocampus in 1 patient and hippocampal sclerosis in 2 patients. All patients underwent stereoelectroencephalography confirming the involvement of the hippocampus in seizure onset. MHTs were completed under intraoperative monitoring, with amygdala and temporal tip resection in all patients due to early spread to these regions. All patients had excellent seizure outcomes at 1 year, and 2 of the 3 patients remain seizure free at last follow-up (range 20–36 months), all with stable or improved neuropsychological profiles, including verbal memory.CONCLUSIONSMHT is a relatively new surgical procedure designed to preserve essential memory circuitry while disrupting seizure propagation pathways in the hippocampus. A growing body of literature shows good seizure and neuropsychological results, but mainly in adults. This is the first series of MHTs used exclusively in children at one medical center, showcasing excellent seizure control and preservation of neuropsychological functioning. One of the patients is also the first described to have MHT in the setting of an amygdalar tumor abutting the hippocampus, further expanding the pathological setting in which MHT can be used effectively.

scholarly journals Synaptic Reshaping and Neuronal Outcomes in the Temporal Lobe Epilepsy

2021 ◽  
Vol 22 (8) ◽  
pp. 3860
Author(s):  
Elisa Ren ◽  
Giulia Curia
Keyword(s):  
Animal Models ◽  
Temporal Lobe Epilepsy ◽  
Temporal Lobe ◽  
Current Knowledge ◽  
Focal Epilepsy ◽  
Ex Vivo ◽  
Hippocampal Sclerosis ◽  
Control Group ◽  
Epileptogenic Zone ◽  
Epileptiform Discharges

Temporal lobe epilepsy (TLE) is one of the most common types of focal epilepsy, characterized by recurrent spontaneous seizures originating in the temporal lobe(s), with mesial TLE (mTLE) as the worst form of TLE, often associated with hippocampal sclerosis. Abnormal epileptiform discharges are the result, among others, of altered cell-to-cell communication in both chemical and electrical transmissions. Current knowledge about the neurobiology of TLE in human patients emerges from pathological studies of biopsy specimens isolated from the epileptogenic zone or, in a few more recent investigations, from living subjects using positron emission tomography (PET). To overcome limitations related to the use of human tissue, animal models are of great help as they allow the selection of homogeneous samples still presenting a more various scenario of the epileptic syndrome, the presence of a comparable control group, and the availability of a greater amount of tissue for in vitro/ex vivo investigations. This review provides an overview of the structural and functional alterations of synaptic connections in the brain of TLE/mTLE patients and animal models.

scholarly journals Localization of epileptogenic zone in temporal lobe epilepsy by ictal scalp EEG

Seizure ◽  
2002 ◽  
Vol 11 (3) ◽  
pp. 163-168 ◽  
Author(s):  
Yuzo Sakai ◽  
Hiromi Nagano ◽  
Ayumi Sakata ◽  
Sachiko Kinoshita ◽  
Naotaka Hamasaki ◽  
...  
Keyword(s):  
Temporal Lobe Epilepsy ◽  
Temporal Lobe ◽  
Epileptogenic Zone ◽  
Scalp Eeg

scholarly journals Genetic and Neuroimaging Approaches to Understanding Post-Traumatic Stress Disorder

2020 ◽  
Vol 21 (12) ◽  
pp. 4503
Author(s):  
Sabah Nisar ◽  
Ajaz A. Bhat ◽  
Sheema Hashem ◽  
Najeeb Syed ◽  
Santosh K. Yadav ◽  
...  
Keyword(s):  
Post Traumatic Stress Disorder ◽  
Traumatic Stress ◽  
Stress Disorder ◽  
Memory Function ◽  
Deep Understanding ◽  
Brain Regions ◽  
Post Traumatic Stress ◽  
Brain Areas ◽  
Social Burden ◽  
Post Traumatic

Post-traumatic stress disorder (PTSD) is a highly disabling condition, increasingly recognized as both a disorder of mental health and social burden, but also as an anxiety disorder characterized by fear, stress, and negative alterations in mood. PTSD is associated with structural, metabolic, and molecular changes in several brain regions and the neural circuitry. Brain areas implicated in the traumatic stress response include the amygdala, hippocampus, and prefrontal cortex, which play an essential role in memory function. Abnormalities in these brain areas are hypothesized to underlie symptoms of PTSD and other stress-related psychiatric disorders. Conventional methods of studying PTSD have proven to be insufficient for diagnosis, measurement of treatment efficacy, and monitoring disease progression, and currently, there is no diagnostic biomarker available for PTSD. A deep understanding of cutting-edge neuroimaging genetic approaches is necessary for the development of novel therapeutics and biomarkers to better diagnose and treat the disorder. A current goal is to understand the gene pathways that are associated with PTSD, and how those genes act on the fear/stress circuitry to mediate risk vs. resilience for PTSD. This review article explains the rationale and practical utility of neuroimaging genetics in PTSD and how the resulting information can aid the diagnosis and clinical management of patients with PTSD.

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