• Communications for Statistical Applications and Methods
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• v.30 no.6
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• pp.561-575
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• 2023

Brain network analysis has attracted the interest of neuroscience researchers in studying brain diseases. Magnetoencephalography (MEG) is especially proper for analyzing functional connectivity due to high temporal and spatial resolution. The application of graph theory for functional connectivity analysis has been studied widely, but research on network modeling for MEG still needs more. Temporal exponential random graph model (TERGM) considers temporal dependencies of networks. We performed the brain network analysis, including static/temporal network statistics, on two groups of epilepsy patients who removed the left (LT) or right (RT) part of the brain and healthy controls. We investigate network differences using Multiset canonical correlation analysis (MCCA) and TERGM between epilepsy patients and healthy controls (HC). The brain network of healthy controls had fewer temporal changes than patient groups. As a result of TERGM, on the simulation networks, LT and RT had less stable state than HC in the network connectivity structure. HC had a stable state of the brain network.

• Annals of Clinical Neurophysiology
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• v.14 no.2
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• pp.59-63
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• 2012

Epilepsy has continued to provide challenges to epileptologists, as a significant proportion of patients continue to suffer from seizures despite medical and surgical treatments. Deep brain stimulation (DBS) has emerged as a new therapeutic modality that has the potential to improve quality of life and occasionally be curative for patients with medically refractory epilepsy who are not surgical candidates. Several groups have used DBS in drug-resistant epilepsy cases for which resective surgery cannot be applied. The promising subcortical brain structures are anterior and centromedian nucleus of the thalamus, subthalamic nucleus, and other nuclei to treat epilepsy in light of previous clinical and experimental data. Recently two randomized trials of neurostimulation for controlling refractory epilepsy employed the strategies to stimulate electrodes placed on both anterior thalamic nuclei or near seizure foci in response to electroencephalographically detected epileptiform activity. However, the more large-scale, long-term clinical trials which elucidates optimal stimulation parameters, ideal selection criteria for epilepsy DBS should be performed before long. In order to continue to advance the frontier of this field, it is imperative to have a good grasp of the current body of knowledge.

• Journal of Korean Neurosurgical Society
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• v.62 no.3
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• pp.313-320
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• 2019

Brain tumors are the second most common type of structural brain lesion that causes chronic epilepsy. Patients with low-grade brain tumors often experience chronic drug-resistant epilepsy starting in childhood, which led to the concept of long-term epilepsy-associated tumors (LEATs). Dysembryoplastic neuroepithelial tumor and ganglioglioma are representative LEATs and are characterized by young age of onset, frequent temporal lobe location, benign tumor biology, and chronic epilepsy. Although highly relevant in clinical epileptology, the concept of LEATs has been criticized in the neuro-oncology field. Recent genomic and molecular studies have challenged traditional views on LEATs and low-grade gliomas. Molecular studies have revealed that low-grade gliomas can largely be divided into three groups : LEATs, pediatric-type diffuse low-grade glioma (DLGG; astrocytoma and oligodendroglioma), and adult-type DLGG. There is substantial overlap between conventional LEATs and pediatric-type DLGG in regard to clinical features, histology, and molecular characteristics. LEATs and pediatric-type DLGG are characterized by mutations in BRAF, FGFR1, and MYB/MYBL1, which converge on the RAS-RAF-MAPK pathway. Gene (mutation)-centered classification of epilepsy-associated tumors could provide new insight into these heterogeneous and diverse neoplasms and may lead to novel molecular targeted therapies for epilepsy in the near future.

• Clinical and Experimental Pediatrics
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• v.59 no.4
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• pp.155-164
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• 2016

Cognitive impairment associated with childhood-onset epilepsy is an important consequence in the developing brain owing to its negative effects on neurodevelopmental and social outcomes. While the cause of cognitive impairment in epilepsy appears to be multifactorial, epilepsy-related factors such as type of epilepsy and underlying etiology, age at onset, frequency of seizures, duration of epilepsy, and its treatment are considered important. In recent studies, antecedent cognitive impairment before the first recognized seizure and microstructural and functional alteration of the brain at onset of epilepsy suggest the presence of a common neurobiological mechanism between epilepsy and cognitive comorbidity. However, the overall impact of cognitive comorbidity in children with epilepsy and the independent contribution of each of these factors to cognitive impairment have not been clearly delineated. This review article focuses on the significant contributors to cognitive impairment in children with epilepsy.

• Journal of Korean Neurosurgical Society
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• v.62 no.3
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• pp.336-343
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• 2019

Epilepsy surgery revealed dramatically improved seizure outcomes over medical therapy in drug-resistant epilepsy patients. Children with epilepsy, however, have multiple epileptic focuses which require multilobar resection for better seizure outcome. Multilobar resection has not only the several severe surgical complications, such as hydrocephalus and shunt-related craniosynostosis, due to intracranial volume reduction. Isolation method (disconnection surgery) was progressively studied over epileptic focus removal (resective surgery) for seizure control. This concept was first introduced for functional hemispherotomy, and its primary principle is to preserve the vital vascularized brain that is functionally disconnected from the contralateral healthy brain. Currently in most epilepsy centers, the predominant disconnection surgical methods, including functional hemispherotomy, are continually being refined and are showing excellent results. They allow the functional isolation of the hemisphere or multi-lobe, affected by severe epilepsy. This review describes recent findings concerning the indication, surgical technique, seizure outcome and complications in several disconnection surgeries including the functional hemispherotomy for refractory pediatric epilepsy.

• Molecules and Cells
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• v.41 no.10
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• pp.881-888
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• 2018

During the cortical development, cells in the brain acquire somatic mutations that can be implicated in various neurodevelopmental disorders. There is increasing evidence that brain somatic mutations lead to sporadic form of epileptic disorders with previously unknown etiology. In particular, malformation of cortical developments (MCD), ganglioglioma (GG) associated with intractable epilepsy and non-lesional focal epilepsy (NLFE) are known to be attributable to brain somatic mutations in mTOR pathway genes and others. In order to identify such somatic mutations presenting as low-level in epileptic brain tissues, the mutated cells should be enriched and sequenced with high-depth coverage. Nevertheless, there are a lot of technical limitations to accurately detect low-level of somatic mutations. Also, it is important to validate whether identified somatic mutations are truly causative for epileptic seizures or not. Furthermore, it will be necessary to understand the molecular mechanism of how brain somatic mutations disturb neuronal circuitry since epilepsy is a typical example of neural network disorder. In this review, we overview current genetic techniques and experimental tools in neuroscience that can address the existence and significance of brain somatic mutations in epileptic disorders as well as their effect on neuronal circuitry.

• Biomedical Science Letters
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• v.18 no.4
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• pp.428-434
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• 2012

Epilepsy is a chronic neurological disease showing a symptom of repeated seizures without any other physical disorders. Among the diagnostic examination for epilepsy, the electroencephalogram (EEG) has been known as an important test. This study aimed to investigate the EEG with photic stimulation in the pediatric epilepsy patients. They underwent digital sleep and waking EEGs or waking EEGs with photic stimulation. Epilepsy type, seizure history, and season of occurring seizure were analyzed. Epilepsy patients showed more response during the period of photic-on and eye close at the frequency of 10~20 Hz during the EEG activation procedure. Photoparoxysmal response (PPR) was shown in 206 patients out of total 1,551 epilepsy patients. PPR was appeared more frequently during summer and winter seasons, and especially in the patients who had a history of seizure. During the PPR, EEG pattern showed spike (77.18%), theta (9.71%), and spike + theta (13.11%). On the other hand, beta and theta waves were not significantly changed by photic stimulation. However, alpha wave was decreased and delta wave was increased by photic stimulation (P<0.05). These changes may be due to temporarily altered electrophysiological function of the epileptic patient's brain by the photic stimulation. There was no difference in the EEG pattern between the left and right side in the brain. In conclusion, condition of photic-on with closed eyes and frequency of 10~20 Hz during the procedure of EEG activation could be appropriate for obtaining a definite photoparoxysmal response in the electroencephalogram of the pediatric epilepsy patients.

• Clinical and Experimental Pediatrics
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• v.59 no.8
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• pp.341-345
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• 2016

Purpose: Venous angioma (VA) is the most common congenital abnormality of the intracranial vasculature. This study aimed to investigate the relationship between VA and epilepsy and to identify the characteristics of children with VA and epilepsy. Methods: The records of all patients aged less than 18 years who underwent brain magnetic resonance imaging (MRI) at Pusan National University Hospital were retrospectively reviewed. Patients with isolated VA and patients with normal MRI were compared in terms of the prevalence of epilepsy. Results: In total, 2,385 pediatric patients who underwent brain MRI were enrolled. Isolated VA was identified in 26 patients (VA group). Among the patients with normal MRI findings, 225 age- and sexmatched patients to the VA-group were assigned to the control group. Nine patients in the VA group (9 of 26, 34.6%) and 27 patients in the control group (26 of 225, 11.5%; P<0.001) had epilepsy. In the VA group, 20 patients (76.9%) had the VA in the cerebral hemispheres, and 6 patients (23.1%) had the VA in the brainstem and cerebellum. The latter showed a higher prevalence of epilepsy (5 of 6, 83.3%) than the former (4 of 20, 20.0%; P=0.004). Among the nine patients who had epilepsy with VA, patients whose VA involved the brainstem and cerebellum showed a significantly higher frequency of abnormal Electroencephalographic findings than patients whose VA involved the cerebral hemispheres (P=0.016). Conclusion: VA, especially in the brainstem and cerebellum, might be associated with epilepsy.

• Journal of Sensor Science and Technology
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• v.20 no.1
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• pp.19-24
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• 2011

Brain disorders such as epilepsy is a condition that affects an estimated 2.7 million Americans, 50,000,000 worldwide, approximately 200,000 new cases of epilepsy are diagnosed each year. Of the major chronic medical conditions, epilepsy is among the least understood. Scientists are conducting research to determine appropriate treatments, such as the use of drugs, vagus nerve stimulation, brain stimulation, and Peltier chip-based focal cooling. However, brain stimulation and Peltier chip-based stimulation processes cannot effectively stop seizures. This paper presents simulation of a novel heat enchanger network(HEN) technique designed to stop seizures by using a neural cooling probe to stop focal and spontaneous seizures by cooling the brain. The designed probe was composed of a U-shaped tube through which cold fluid flowed in order to reduce the temperature of the brain. The simulation results demonstrated that the neural probe could cool a 7 $mm^2$ area of the brain when the fluid was flowing atb a velocity of 0.55 m/s. It also showed that the neural cooling probe required 23 % less energy to produce cooling when compared to the Peltier chip-based cooling system.

• Sleep Medicine and Psychophysiology
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• v.9 no.1
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• pp.14-17
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• 2002

Epilepsy is a paroxysmal disorder caused by abnormal electrical discharges of the brain. As it is characterized by episodic seizures with intervening normal neurological states, some temporal patterns of seizure attacks can be traced. Sleep and wakefulness patterns are one of several factors influencing seizure occurrence. In this article, physiological and pathological influences of sleep on the seizure phenomenon were reviewed. Understanding this relationship between sleep and epilepsy might lead to better understanding of sleep and epilepsy themselves, thus leading to better diagnosis and treatment of each disease.