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Neocortical epilepsy

Anna Serafini, Naoum Issa, Sandra Rose, Shasha Wu, Peter Warnke, James X Tao
Electrophysiological studies have suggested that temporal intermittent rhythmic delta activity (TIRDA) has a localizing value similar to interictal spikes in patients with temporal lobe epilepsy, and is associated with a favorable outcome after temporal lobectomyHowever, it remains controversial whether TIRDA is an EEG marker for mesial or lateral temporal epileptogenesis. We simultaneously recorded scalp EEG and stereoencephalography (SEEG) in a patient with mesial temporal lobe epilepsy (mTLE) during epilepsy pre-surgical evaluation...
June 13, 2016: Journal of Clinical Neurophysiology: Official Publication of the American Electroencephalographic Society
F Vallone, E Vannini, A Cintio, M Caleo, A Di Garbo
Epilepsy is characterized by substantial network rearrangements leading to spontaneous seizures and little is known on how an epileptogenic focus impacts on neural activity in the contralateral hemisphere. Here, we used a model of unilateral epilepsy induced by injection of the synaptic blocker tetanus neurotoxin (TeNT) in the mouse primary visual cortex (V1). Local field potential (LFP) signals were simultaneously recorded from both hemispheres of each mouse in acute phase (peak of toxin action) and chronic condition (completion of TeNT effects)...
September 2016: Physical Review. E
Marcus C Ng, Ronan Kilbride, Mirela Simon, Emad Eskandar, Andrew J Cole
Background. The optimal surgery in lesional neocortical temporal lobe epilepsy is unknown. Hippocampal electrocorticography maximizes seizure freedom by identifying normal-appearing epileptogenic tissue for resection and minimizes neuropsychological deficit by limiting resection to demonstrably epileptogenic tissue. We examined whether standardized hippocampal electrocorticography (hippocampography) guides resection for more consistent hippocampectomy than unguided resection in conventional electrocorticography focused on the lesion...
2016: Epilepsy Research and Treatment
David N Vaughan, Genevieve Rayner, Chris Tailby, Graeme D Jackson
OBJECTIVE: To define the functional network changes that characterize MRI-negative temporal lobe epilepsy (TLE) and TLE with hippocampal sclerosis (HS-TLE). METHODS: We studied 36 patients with medically refractory unilateral TLE, having either a normal clinical MRI (n = 18) or unilateral hippocampal sclerosis (n = 18). Patients were compared to healthy controls of equivalent age and sex (n = 27). Functional connectivity in 10 minutes of task-free functional MRI was assessed using a voxel-resolution graph theoretic analysis, using the metrics of degree, clustering coefficient, eigenvector, and betweenness centrality...
September 30, 2016: Neurology
Grant Gillary, Ernst Niebur
The standard architecture of neocortex is a network with excitation and inhibition in closely maintained balance. These networks respond fast and with high precision to their inputs and they allow selective amplification of patterned signals. The stability of such networks is known to depend on balancing the strengths of positive and negative feedback. We here show that a second condition is required for stability which depends on the relative strengths and time courses of fast (AMPA) and slow (NMDA) currents in the excitatory projections...
September 2016: PLoS Computational Biology
Eun-Ik Son, Ji-Eun Kim
It is well known that there is high quality evidence of epilepsy surgery as an effective and safe option for patients with drug refractory epilepsy by advanced imaging technology and computerized electrophysiological facilities during recent three decades. However, it still remains debate regarding necessities of epilepsy surgery in terms of less satisfactory surgical outcome, especially in non-lesional neocortical epilepsies. This review is for the role of epileptic neurosurgeon rather than the role of epilepsy surgery, namely, the necessity of neurosurgeon's positive participation starting from the first visit of epilepsy patients followed by pertaining process by stages and its degree of contribution...
June 2016: Biomedical Journal
Dario J Englot, Peter E Konrad, Victoria L Morgan
Epilepsy is among the most common brain network disorders, and it is associated with substantial morbidity and increased mortality. Although focal epilepsy was traditionally considered a regional brain disorder, growing evidence has demonstrated widespread network alterations in this disorder that extend beyond the epileptogenic zone from which seizures originate. The goal of this review is to summarize recent investigations examining functional and structural connectivity alterations in focal epilepsy, including neuroimaging and electrophysiologic studies utilizing model-based or data-driven analytic methods...
October 2016: Epilepsia
David O Kamson, Vinod K Pilli, Eishi Asano, Jeong-Won Jeong, Sandeep Sood, Csaba Juhász, Harry T Chugani
PURPOSE: We evaluated if cortical thickness measures were associated with surgical outcome in patients with non-lesional neocortical epilepsy. METHODS: Twenty-one young patients (age: 2.4-19.7years) with epilepsy of neocortical origin and normal MRI underwent two-stage epilepsy surgery with subdural EEG monitoring. Cortical thickness was measured on presurgical volumetric MRI using the FreeSurfer software. The prognostic value of hemispheric and lobar/regional cortical thickness measures for 1-year and 2-year post-surgical seizure outcome has been analyzed...
September 15, 2016: Journal of the Neurological Sciences
Aylin Y Reid, Anatol Bragin, Christopher C Giza, Richard J Staba, Jerome Engel
OBJECTIVE: Posttraumatic epilepsy (PTE) accounts for 20% of acquired epilepsies. Experimental models are important for studying epileptogenesis. We previously reported that repetitive high-frequency oscillations with spikes (rHFOSs) occur early after lateral fluid percussion injury (FPI) and may be a biomarker for PTE. The objective of this study was to use multiple electrodes in rat hippocampal and neocortical regions to describe the long-term electroencephalographic and behavioral evolution of rHFOSs and epileptic seizures after traumatic brain injury (TBI)...
October 2016: Epilepsia
E C Y Ho, Wilson Truccolo
How focal seizures initiate and evolve in human neocortex remains a fundamental problem in neuroscience. Here, we use biophysical neuronal network models of neocortical patches to study how the interaction between inhibition and extracellular potassium ([K (+)] o ) dynamics may contribute to different types of focal seizures. Three main types of propagated focal seizures observed in recent intracortical microelectrode recordings in humans were modelled: seizures characterized by sustained (∼30-60 Hz) gamma local field potential (LFP) oscillations; seizures where the onset in the propagated site consisted of LFP spikes that later evolved into rhythmic (∼2-3 Hz) spike-wave complexes (SWCs); and seizures where a brief stage of low-amplitude fast-oscillation (∼10-20 Hz) LFPs preceded the SWC activity...
October 2016: Journal of Computational Neuroscience
Linda V Blomster, Dorte Strøbaek, Charlotte Hougaard, Jessica Klein, Lars H Pinborg, Jens D Mikkelsen, Palle Christophersen
The KCa 3.1 channel (KCNN4) is an important modulator of microglia responses in rodents, but no information exists on functional expression on microglia from human adults. We isolated and cultured microglia (max 1% astrocytes, no neurons or oligodendrocytes) from neocortex surgically removed from epilepsy patients and employed electrophysiological whole-cell measurements and selective pharmacological tools to elucidate functional expression of KCa 3.1. The channel expression was demonstrated as a significant increase in the voltage-independent current by NS309, a KCa 3...
July 29, 2016: Glia
Lihua Wang, Suzie Dufour, Taufik A Valiante, Peter L Carlen
Seizure activity leads to increases in extracellular potassium concentration ([K[Formula: see text]]o), which can result in changes in neuronal passive and active membrane properties as well as in population activities. In this study, we examined how extracellular potassium modulates seizure activities using an acute 4-AP induced seizure model in the neocortex, both in vivo and in vitro. Moderately elevated [K[Formula: see text]]o up to 9[Formula: see text]mM prolonged seizure durations and shortened interictal intervals as well as depolarized the neuronal resting membrane potential (RMP)...
December 2016: International Journal of Neural Systems
Cenglin Xu, Shuang Wang, Yi Wang, Kang Lin, Gang Pan, Zhenghao Xu, Jorge Gonzalez-Martinez, Feng Gao, Xiaohua Wu, Shihong Zhang, Juan C Bulacio, Imad M Najm, Jianhong Luo, Weiwei Hu, Zhaohui Wu, Norman K So, Zhong Chen
High-frequency oscillations (HFOs) are promising biomarkers for epileptic foci; however, their characteristic changes during the preictal period remain unclear. Here, the preictal HFOs were recorded and detected by an automated HFOs detection method in the mouse pilocarpine model as well as in patients with mesial temporal lobe epilepsy (mTLE) and neocortical epilepsy. A total of sixteen low-voltage fast (LVF) and fifty-three hypersynchronous-onset (HYP) seizures were recorded in ten mice. The rate of ripples (80-250Hz) decreased during 1min before the onset of LVF and HYP seizures, which was primarily due to the reduction of type II (independent of epileptiform discharges) rather than type I ripples (superimposed on epileptiform activities)...
July 22, 2016: Experimental Neurology
Zsófia Richter, József Janszky, György Sétáló, Réka Horváth, Zsolt Horváth, Tamás Dóczi, László Seress, Hajnalka Ábrahám
The aim of the present work was to characterize neurons in the archi- and neocortical white matter, and to investigate their distribution in mesial temporal sclerosis. Immunohistochemistry and quantification of neurons were performed on surgically resected tissue sections of patients with therapy-resistant temporal lobe epilepsy. Temporal lobe tissues of patients with tumor but without epilepsy and that from autopsy were used as controls. Neurons were identified with immunohistochemistry using antibodies against NeuN, calcium-binding proteins, transcription factor Tbr1 and neurofilaments...
October 1, 2016: Neuroscience
Stanislas Lagarde, Francesca Bonini, Aileen McGonigal, Patrick Chauvel, Martine Gavaret, Didier Scavarda, Romain Carron, Jean Régis, Sandrine Aubert, Nathalie Villeneuve, Bernard Giusiano, Dominique Figarella-Branger, Agnès Trebuchon, Fabrice Bartolomei
OBJECTIVES: The study of intracerebral electroencephalography (EEG) seizure-onset patterns is crucial to accurately define the epileptogenic zone and guide successful surgical resection. It also raises important pathophysiologic issues concerning mechanisms of seizure generation. Until now, several seizure-onset patterns have been described using distinct recording methods (subdural, depth electrode), mostly in temporal lobe epilepsies or with heterogeneous neocortical lesions. METHODS: We analyzed data from a cohort of 53 consecutive patients explored by stereoelectroencephalography (SEEG) and with pathologically confirmed malformation of cortical development (MCD; including focal cortical dysplasia [FCD] and neurodevelopmental tumors [NDTs])...
September 2016: Epilepsia
David C Spencer, Felice T Sun, Sarah N Brown, Barbara C Jobst, Nathan B Fountain, Victoria S S Wong, Emily A Mirro, Mark Quigg
OBJECTIVE: Previous studies reporting circadian patterns of epileptiform activity and seizures are limited by (1) short-term recording in an epilepsy monitoring unit (EMU) with altered antiepileptic drugs (AEDs) and sleep, or (2) subjective seizure diary reports. We studied circadian patterns using long-term ambulatory intracranial recordings captured by the NeuroPace RNS System. METHODS: Retrospective study of RNS System trial participants with stable detection parameters over a continuous 84-day period...
September 2016: Epilepsia
Min Liu, Boris C Bernhardt, Seok-Jun Hong, Benoit Caldairou, Andrea Bernasconi, Neda Bernasconi
Drug-resistant temporal lobe epilepsy is increasingly recognized as a system-level disorder affecting the structure and function of large-scale grey matter networks. While diffusion magnetic resonance imaging studies have demonstrated deep fibre tract alterations, the superficial white matter immediately below the cortex has so far been neglected despite its proximity to neocortical regions and key role in maintaining cortico-cortical connectivity. Using multi-modal 3 T magnetic resonance imaging, we mapped the topography of superficial white matter diffusion alterations in 61 consecutive temporal lobe epilepsy patients relative to 38 healthy controls and studied the relationship to large-scale structural as well as functional networks...
September 2016: Brain: a Journal of Neurology
Xingjie Ping, Xiaoming Jin
Posttraumatic epilepsy (PTE) usually develops in a small percentage of patients of traumatic brain injury after a varying latent period. Modeling this chronic neurological condition in rodents is time consuming and inefficient, which constitutes a significant obstacle in studying its mechanism and discovering novel therapeutics for its prevention and treatment. Partially isolated neocortex, or undercut, is known to induce cortical hyperexcitability and epileptiform activity in vitro, and has been used extensively for studying the neurophysiological mechanism of posttraumatic epileptogenesis...
2016: PloS One
Georgia Ramantani, Louis Maillard, Laurent Koessler
Ever since the implementation of invasive EEG recordings in the clinical setting, it has been perceived that a considerable proportion of epileptic discharges present at a cortical level are missed by routine scalp EEG recordings. Several in vitro, in vivo, and simulation studies have been performed in the past decades aiming to clarify the interrelations of cortical sources with their scalp and invasive EEG correlates. The amplitude ratio of cortical potentials to their scalp EEG correlates, the extent of the cortical area involved in the discharge, as well as the localization of the cortical source and its geometry have been each independently linked to the recording of the cortical discharge with scalp electrodes...
October 2016: Seizure: the Journal of the British Epilepsy Association
Yoko Iijima, Katharina Behr, Takatoshi Iijima, Barbara Biemans, Josef Bischofberger, Peter Scheiffele
Autism spectrum disorders (ASDs) are a heterogeneous group of neurodevelopmental disorders characterized by impairments in social interactions and stereotyped behaviors. Valproic acid (VPA) is frequently used to treat epilepsy and bipolar disorders. When taken during pregnancy, VPA increases the risk of the unborn child to develop an ASD. In rodents, in utero VPA exposure can precipitate behavioral phenotypes related to ASD in the offspring. Therefore, such rodent models may allow for identification of synaptic pathophysiology underlying ASD risk...
2016: Scientific Reports
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