• Clinical and Experimental Pediatrics
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• v.60 no.1
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• pp.1-9
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• 2017

Malformations of cortical development are rare congenital anomalies of the cerebral cortex, wherein patients present with intractable epilepsy and various degrees of developmental delay. Cases show a spectrum of anomalous cortical formations with diverse anatomic and morphological abnormalities, a variety of genetic causes, and different clinical presentations. Brain magnetic resonance imaging has been of great help in determining the exact morphologies of cortical malformations. The hypothetical mechanisms of malformation include interruptions during the formation of cerebral cortex in the form of viral infection, genetic causes, and vascular events. Recent remarkable developments in genetic analysis methods have improved our understanding of these pathological mechanisms. The present review will discuss normal cortical development, the current proposed malformation classifications, and the diagnostic approach for malformations of cortical development.

• Journal of Korean Neurosurgical Society
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• v.62 no.3
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• pp.265-271
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• 2019

The expansion and folding of the cerebral cortex occur during brain development and are critical factors that influence cognitive ability and sensorimotor skills. The disruption of cortical growth and folding may cause neurological disorders, resulting in severe intellectual disability and intractable epilepsy in humans. Therefore, understanding the mechanism that regulates cortical growth and folding will be crucial in deciphering the key steps of brain development and finding new therapeutic targets for the congenital anomalies of the cerebral cortex. This review will start with a brief introduction describing the anatomy of the brain cortex, followed by a description of our understanding of the proliferation, differentiation, and migration of neural progenitors and important genes and molecules that are involved in these processes. Finally, various types of disorders that develop due to malformation of the cerebral cortex will be discussed.

• Journal of Korean Neurosurgical Society
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• v.62 no.3
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• pp.272-287
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• 2019

The mechanistic target of rapamycin (mTOR) pathway coordinates the metabolic activity of eukaryotic cells through environmental signals, including nutrients, energy, growth factors, and oxygen. In the nervous system, the mTOR pathway regulates fundamental biological processes associated with neural development and neurodegeneration. Intriguingly, genes that constitute the mTOR pathway have been found to be germline and somatic mutation from patients with various epileptic disorders. Hyperactivation of the mTOR pathway due to said mutations has garnered increasing attention as culprits of these conditions : somatic mutations, in particular, in epileptic foci have recently been identified as a major genetic cause of intractable focal epilepsy, such as focal cortical dysplasia. Meanwhile, epilepsy models with aberrant activation of the mTOR pathway have helped elucidate the role of the mTOR pathway in epileptogenesis, and evidence from epilepsy models of human mutations recapitulating the features of epileptic patients has indicated that mTOR inhibitors may be of use in treating epilepsy associated with mutations in mTOR pathway genes. Here, we review recent advances in the molecular and genetic understanding of mTOR signaling in epileptic disorders. In particular, we focus on the development of and limitations to therapies targeting the mTOR pathway to treat epileptic seizures. We also discuss future perspectives on mTOR inhibition therapies and special diagnostic methods for intractable epilepsies caused by brain somatic mutations.

• Clinical and Experimental Pediatrics
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• v.49 no.2
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• pp.187-191
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• 2006

Purpose : Malformation of cortical development(MCD) constitutes an important etiology of intractable epilepsy and is considered an indication for surgical treatments, though their efficacy is limited and variable depending on MCD's location or distribution. Ketogenic diets are widely known to be effective, but as little study has been made concerning their efficacy on epilepsy with MCD, we evaluated the efficacy of ketogenic diets on MCD patients compared with that of epileptic surgery, which is more invasive. Methods : We performed retrospective studies and analyse on 30 patients with MCD diagnosed by brain MRI and treated with ketogenic diets for intractable epilepsy since 1998, checking decreases in their seizure episodes after starting the diets. Results : Cortical dysplasia was observed in 24(80.0 percent) patients as the most common type of MCD. Also, MCD was observed in unilateral hemisphere most commonly, in 23(76.7 percent) patients; it was observed in both hemispheres in 7(23.3 percent) patients. Nine(30.0 percent) out of 30 patients became seizure-free after starting ketogenic diets, and 14(46.7 percent) patients experienced 50 percent seizure reductions as well. Age of starting the diet or the duration of epilepsy period before starting showed no statistical relationship with the efficacy of the diet. Though the younger the patient and the longer the treatment the more effective the diet seemed to be, there was no statistical correlation between them. The location of MCD showed no significance neither. Conclusion : Considering various limits and invasiveness of surgical treatment, a ketogenic diet could be a good tool in treating children with intractable epilepsy with MCD.

• 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.

• Toxicological Research
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• v.17
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• pp.11-16
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• 2001

The development of the central nervous system is a continuous process during the embryonic and fetal periods. For a better understanding of congenital anomalies of central nervous system, three major events of normal development, i.e., neurulation (3 to 4 weeks), brain vesicle formation (4 to 7 weeks) and mantle formation (over 8 weeks) should be kept in mind. The first category of anomalies is neural tube defect. Neural tube defects encompass all the anomalies arise in completion of neurulation. The second category of central nervous system anomalies is disorders of brain vesicle formation. This is anomaly that applies for "the face predicts the brain". Holoprosencephaly covers a spectrum of anomalies of intracranial and midfacial development which result from incomplete development and septation of midline structures within the forebrain or prosencephalon. The last category of central nervous system malformation is disorders involving the process of mantle formation. In the human, neurons are generated in two bursts, the first from 8 to 10 weeks and next from 12 to 14 weeks. By 16 weeks, most of the neurons have been generated and have started their migration into the cortex. Mechanism of migration disorders are multifactorial. Abnormal migration into the cortex, abnormal neurons, faulty neural growth within the cortex, unstable pial-glial border, degeneration of neurons, neural death by exogenous factors are some of the proposed mechanism. Agyria-pachygyria are characterized by a four-layerd cortex. Polymicrogyria is gyri that are too numerous and too small, and is morphologically heterogeneous. Cortical dysplasia is characterized by the presence Q[ abnormal neurons and glia arranged abnormally in focal areas of the cerebral cortex. Neuroglial malformative lesions associated with medically intractable epilepsy are hamartia or hamartoma, focal cortical dysplasia and microdysgenesis.ysgenesis.

• Journal of Genetic Medicine
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• v.16 no.2
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• pp.71-75
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• 2019

Periventricular nodular heterotopia (PNH) is a malformation of cortical development in which normal neurons inappropriately cluster in periventricular areas. Patients with Mowat-Wilson syndrome (MWS) typically present with facial gestalt, complex neurologic problems (e.g., severe developmental delay with marked speech impairment and epilepsy), and multiple anomalies (e.g., Hirschsprung disease, urogenital anomalies, congenital heart defects, eye anomalies, and agenesis of the corpus callosum [CC]). MWS is mostly caused by haploinsufficiency of the gene encoding zinc-finger E-box-binding homeobox 2 (ZEB2) due to premature stops or large deletions. We present a case report of a 9-year-old girl with PNH, drug-responsive epilepsy, severe intellectual disability, and facial dysmorphisms only in whom we performed whole-exome sequencing and found a de novo heterozygous missense mutation (c.3134A>C; p.His1045Pro) of ZEB2 (NM_014795.3; NP_055610.1). This mild case of MWS caused by a rare novel missense mutation of ZEB2 represents the first report of MWS with isolated PNH.

• Journal of Korean Neurosurgical Society
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• v.29 no.8
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• pp.1126-1135
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• 2000

Objectives : The goal of surgical management of cerebral arteriovenous malformation(AVM) is elimination of the lesion without development of new neurological deficits. To improve the management results of cerebral AVMs in the future, this article discusses about surgical complications of the AVM and their management. Material and Methods : During the past 18 years, 116 patients with cerebral AVMs were managed by surgery. Among these cases, 7 cases died, 7 cases developed new neurological deficits, 11 cases residual AVM and 5 cases intracerebral hematoma(ICH) after surgery. The author analyzes the causes of those complications and investigates the methods to minimized those complications based on the review of the literatures. Results : One stage removal of AVM and ICH in the poor neurological state were performed in 5 of 7 death cases. Subtotal removal of ICH followed by delayed AVM surgery after recovery is regard as one method to improve the outcome of patient with large ICH. Postoperative new neurological deficits developed owing to normal perfusion pressure breakthrough(NPPB) in 3, judgement error in 2, preoperative embolization in 1 and cortical injury in 1 case(s). Proper management of NPPB, accurate anatomical knowledge and physiological monitoring during operation, and well trained skill for embolization are regard as methods to minimize those complications. Residual AVMs after surgery were noticed in 11 cases, in which unintended 6 cases due to inaccurate dissection of peripheral margin of AVM, and intended 3 cases due to massive brain swelling during operation, 1 cases due to diffuse type and 1 case due to multiple type of AVM. Accurate dissection of peripheral margin of AVM and mild hypotension during operation may help to avoid this complication. Postoperative hemorrhage occurred in 3 cases due to rupture of the residual AVM and in 2 cases due to oozing from the AVM bed. Complete resection of AVM, complete control of bleeding points at AVM bed and mild hypotension during early postoperative period are the methods to avoid this complication. Conclusion : A precise but flexible therapeutic strategy and refined skill for endovascular, radiosurgical and microsurgical techniques are required to successful treatment of cerebral AVM. Adequate timing of AVM resection, accurate anatomical knowledge, proper management of NPPB and accurate dissection of peripheral margin of AVM are the key points for avoiding complications of the AVM surgery.

• Journal of The Korean Society of Inherited Metabolic disease
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• v.17 no.2
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• pp.48-54
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• 2017

Purpose: Fukuyama congenital muscular dystrophy (FCMD) is a rare, autosomal-recessive disorder characterized by early-onset hypotonia associated with brain malformations in dystroglycanopathy. Although the wide spectrum of congenital muscular dystrophies causes difficulty in diagnosis, correlating the genotype with the clinical phenotype can help diagnose FCMD. Here, we evaluated the correlation of targeted molecular genetic analysis of FKTN gene mutation with the FCMD phenotype. Methods: This study was conducted retrospectively with 9 subjects. Inclusion criteria included clinical symptoms characterized by early-onset hypotonia with magnetic resonance imaging (MRI) featuring brain malformations. FKTN gene-alteration analysis was performed using various FKTN gene-analysis methods, including sequencing. Results: Among the 9 subjects studied, 4 (44.4%) were male and 5 (55.6%) were female. The median age of onset of the first symptom was 3.1 months. The first symptom was a delayed milestone in 6 cases (66.7%). All 9 subjects (100%) presented with early-onset hypotonia and global delayed development. All subjects presented with cortical malformation in their brain MRIs. Of the 9 subjects, 6 subjects had previously undergone muscle biopsy and 4 cases (4/6; 66.7%) showed dystrophic or myopathic features. Pathogenic mutations causing FCMD were identified in 3 cases. Conclusions: In this study, all 3 subjects with FKTN mutations showed important MRI findings (pachygyria and cerebellar dysplasia). These data suggest that patients with characteristic phenotypes who show pachygyria and cerebellar abnormalities in brain MRIs may have a high probability of being diagnosed with FCMD.