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Setkowicz Z, Kiełbinski M, Gzieło K, Węglarz W, Janeczko K. Changes of EEG spectra in rat brains with different patterns of dysplasia in response to pilocarpine-induced seizures. Epilepsy Behav 2020; 111:107288. [PMID: 32702654 DOI: 10.1016/j.yebeh.2020.107288] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 03/04/2020] [Revised: 06/20/2020] [Accepted: 06/24/2020] [Indexed: 12/14/2022]
Abstract
Disorders of neurogenesis at early developmental stages lead to irreversible structural and functional impairments of the brain. As further their consequences, increases in brain excitability and the development of drug-resistant epilepsy can frequently be observed in clinical cases. Mechanisms underlying these phenomena can also be examined on animal models of brain dysplasia. This study was conducted on rats with four degrees of brain dysplasia following exposure to gamma radiation on days 13, 15, 17, or 19 of prenatal development. When reached adulthood, the rats received electroencephalographic (EEG) transmitter implantation. Thereafter, pilocarpine was administered, and significant differences in susceptibility to seizures were detected depending on the degree of brain dysplasia. Before, during, and after the seizures, EEG was recorded in free moving animals. Additionally, the intensity of seizure behavioral symptoms was assessed. Strong and moderate correlations were found between the intensity of seizure behavioral symptoms, the power of particular EEG bands, and volumes of dysplastic brains and their regions. The data drew particular attention to correlations between variations in EEG spectra and changes in the midbrain and pons volumes. The results point to possible significant roles of these regions in the observed changes of susceptibility to seizures. Consequently, the frequently used experimental model was considered here not only as representing cases of cortical dysplasia but also of generalized, diffuse dysplasia of the whole brain.
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Affiliation(s)
- Zuzanna Setkowicz
- Department of Neuroanatomy, Institute of Zoology and Biomedical Research, Jagiellonian University, Krakow, Poland
| | - Michał Kiełbinski
- Department of Neuroanatomy, Institute of Zoology and Biomedical Research, Jagiellonian University, Krakow, Poland
| | - Kinga Gzieło
- Department of Neuroanatomy, Institute of Zoology and Biomedical Research, Jagiellonian University, Krakow, Poland
| | - Władysław Węglarz
- Department of Magnetic Resonance Imaging, Institute of Nuclear Physics, Polish Academy of Sciences, Krakow, Poland
| | - Krzysztof Janeczko
- Department of Neuroanatomy, Institute of Zoology and Biomedical Research, Jagiellonian University, Krakow, Poland.
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Lu IL, Chen C, Tung CY, Chen HH, Pan JP, Chang CH, Cheng JS, Chen YA, Wang CH, Huang CW, Kang YN, Chang HY, Li LL, Chang KP, Shih YH, Lin CH, Kwan SY, Tsai JW. Identification of genes associated with cortical malformation using a transposon-mediated somatic mutagenesis screen in mice. Nat Commun 2018; 9:2498. [PMID: 29950674 PMCID: PMC6021418 DOI: 10.1038/s41467-018-04880-8] [Citation(s) in RCA: 23] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/02/2018] [Accepted: 05/23/2018] [Indexed: 12/12/2022] Open
Abstract
Mutations in genes involved in the production, migration, or differentiation of cortical neurons often lead to malformations of cortical development (MCDs). However, many genetic mutations involved in MCD pathogenesis remain unidentified. Here we developed a genetic screening paradigm based on transposon-mediated somatic mutagenesis by in utero electroporation and the inability of mutant neuronal precursors to migrate to the cortex and identified 33 candidate MCD genes. Consistent with the screen, several genes have already been implicated in neural development and disorders. Functional disruption of the candidate genes by RNAi or CRISPR/Cas9 causes altered neuronal distributions that resemble human cortical dysplasia. To verify potential clinical relevance of these candidate genes, we analyzed somatic mutations in brain tissue from patients with focal cortical dysplasia and found that mutations are enriched in these candidate genes. These results demonstrate that this approach is able to identify potential mouse genes involved in cortical development and MCD pathogenesis. Cortical malformations have a variety of causes. Here the authors use transposon mutagenesis to insert mutations into neural stem cells in the developing mouse cortex to screen for new candidate genes for cortical malformation, and validate some targets in human brain tissue.
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Affiliation(s)
- I-Ling Lu
- Institute of Brain Science, National Yang-Ming University, Taipei, 112, Taiwan
| | - Chien Chen
- Department of Neurology, Neurological Institute, Taipei Veterans General Hospital, Taipei, 112, Taiwan.,National Yang-Ming University School of Medicine, Taipei, 112, Taiwan
| | - Chien-Yi Tung
- VYM Genome Research Center of National Yang-Ming University, Taipei, 112, Taiwan.,Institute of Microbiology and Immunology, National Yang-Ming University, Taipei, 112, Taiwan
| | - Hsin-Hung Chen
- National Yang-Ming University School of Medicine, Taipei, 112, Taiwan.,Department of Neurosurgery, Neurological Institute, Taipei Veterans General Hospital, Taipei, 112, Taiwan
| | - Jia-Ping Pan
- VYM Genome Research Center of National Yang-Ming University, Taipei, 112, Taiwan
| | - Chia-Hsiang Chang
- Institute of Brain Science, National Yang-Ming University, Taipei, 112, Taiwan.,Taiwan International Graduate Program (TIGP) in Molecular Medicine, National Yang-Ming University and Academia Sinica, Taipei, 112, Taiwan
| | - Jia-Shing Cheng
- Institute of Brain Science, National Yang-Ming University, Taipei, 112, Taiwan
| | - Yi-An Chen
- Institute of Brain Science, National Yang-Ming University, Taipei, 112, Taiwan
| | - Chun-Hung Wang
- Institute of Brain Science, National Yang-Ming University, Taipei, 112, Taiwan
| | - Chia-Wei Huang
- Institute of Brain Science, National Yang-Ming University, Taipei, 112, Taiwan
| | - Yi-Ning Kang
- Institute of Brain Science, National Yang-Ming University, Taipei, 112, Taiwan
| | - Hsin-Yun Chang
- Institute of Brain Science, National Yang-Ming University, Taipei, 112, Taiwan
| | - Lei-Li Li
- Institute of Brain Science, National Yang-Ming University, Taipei, 112, Taiwan
| | - Kai-Ping Chang
- National Yang-Ming University School of Medicine, Taipei, 112, Taiwan.,Department of Pediatrics, Taipei Veterans General Hospital, Taipei, 112, Taiwan
| | - Yang-Hsin Shih
- National Yang-Ming University School of Medicine, Taipei, 112, Taiwan.,Department of Neurosurgery, Neurological Institute, Taipei Veterans General Hospital, Taipei, 112, Taiwan
| | - Chi-Hung Lin
- VYM Genome Research Center of National Yang-Ming University, Taipei, 112, Taiwan.,Institute of Microbiology and Immunology, National Yang-Ming University, Taipei, 112, Taiwan.,Institute of Biophotonics, National Yang-Ming University, Taipei, 112, Taiwan
| | - Shang-Yeong Kwan
- Department of Neurology, Neurological Institute, Taipei Veterans General Hospital, Taipei, 112, Taiwan.,National Yang-Ming University School of Medicine, Taipei, 112, Taiwan
| | - Jin-Wu Tsai
- Institute of Brain Science, National Yang-Ming University, Taipei, 112, Taiwan. .,Brain Research Center, National Yang-Ming University, Taipei, 112, Taiwan. .,Biophotonics and Molecular Imaging Research Center, National Yang-Ming University, Taipei, 112, Taiwan.
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3
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Kielbinski M, Setkowicz Z, Gzielo K, Janeczko K. Profiles of gene expression in the hippocampal formation of rats with experimentally-induced brain dysplasia. Dev Neurobiol 2018; 78:718-735. [DOI: 10.1002/dneu.22595] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/15/2017] [Revised: 03/28/2018] [Accepted: 04/06/2018] [Indexed: 12/14/2022]
Affiliation(s)
- Michal Kielbinski
- Department of Neuroanatomy; Institute of Zoology and Biomedical Research, Jagiellonian University, Gronostajowa 9; Krakow 30-387 Poland
| | - Zuzanna Setkowicz
- Department of Neuroanatomy; Institute of Zoology and Biomedical Research, Jagiellonian University, Gronostajowa 9; Krakow 30-387 Poland
| | - Kinga Gzielo
- Department of Neuroanatomy; Institute of Zoology and Biomedical Research, Jagiellonian University, Gronostajowa 9; Krakow 30-387 Poland
| | - Krzysztof Janeczko
- Department of Neuroanatomy; Institute of Zoology and Biomedical Research, Jagiellonian University, Gronostajowa 9; Krakow 30-387 Poland
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Wang DD, Piao YS, Blumcke I, Coras R, Zhou WJ, Gui QP, Liu CC, Hu JX, Cao LZ, Zhang GJ, Lu DH. A distinct clinicopathological variant of focal cortical dysplasia IIId characterized by loss of layer 4 in the occipital lobe in 12 children with remote hypoxic-ischemic injury. Epilepsia 2017; 58:1697-1705. [PMID: 28833053 DOI: 10.1111/epi.13855] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 06/28/2017] [Indexed: 12/18/2022]
Abstract
OBJECTIVE In 2011, the International League Against Epilepsy (ILAE) proposed a consensus classification system of focal cortical dysplasia (FCD) to distinguish clinicopathological subtypes, for example, "isolated" FCD type Ia-c and IIa-b, versus "associated" FCD type IIIa-d. The histopathological differentiation of FCD type I and III variants remains, however, a challenging issue in everyday practice. We present a unique histopathological pattern in patients with difficult-to-diagnose FCD, which highlights this dilemma, but also helps to refine the current ILAE classification scheme of FCD. METHODS We present a retrospective series of 11 male and one female patient with early onset pharmacoresistant epilepsy of the posterior quadrant (mean age at seizure onset = 4.6 years). All surgical specimens were reviewed. Clinical histories were retrieved and extracted from archival patient files. RESULTS Microscopic inspection revealed abnormalities in cortical architecture with complete loss of layer 4 in all surgical samples of the occipital lobe, as confirmed by semiquantitative measurements (p < 0.01). Clinical history reported early transient hypoxic condition in nine patients (75%). Magnetic resonance imaging (MRI) revealed abnormal signals in the occipital lobe in all patients, and signal changes suggestive of subcortical encephalomalacia were found in seven patients. Surgical treatment achieved favorable seizure control (Engel class I and II) in seven patients with an available follow-up period of 6.1 years. SIGNIFICANCE Prominent disorganization of cortical layering and lack of any other microscopically visible principle lesion in the surgical specimen would result in this neuropathological pattern hitherto being classified as FCD ILAE type Ib. However, perinatal hypoxia with distinctive MRI changes suggested primarily a hypoxemic lesion and acquired pathomechanism of neuronal cell loss in the occipital lobe of our patient series. We propose, therefore, classifying this distinctive clinicopathological pattern as a separate variant of FCD ILAE type IIId.
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Affiliation(s)
- Dan-Dan Wang
- Department of Pathology, Xuanwu Hospital, Capital Medical University, Beijing, China
| | - Yue-Shan Piao
- Department of Pathology, Xuanwu Hospital, Capital Medical University, Beijing, China
| | - Ingmar Blumcke
- Neuropathological Institute, University Hospitals Erlangen, Erlangen, Germany
| | - Roland Coras
- Neuropathological Institute, University Hospitals Erlangen, Erlangen, Germany
| | - Wen-Jing Zhou
- Department of Neurosurgery, Tsinghua University Yuquan Hospital, Beijing, China
| | - Qiu-Ping Gui
- Department of Pathology, Chinese People's Liberation Army General Hospital, Beijing, China
| | - Cui-Cui Liu
- Department of Pathology, Xuanwu Hospital, Capital Medical University, Beijing, China
| | - Jing-Xia Hu
- Department of Pathology, Tsinghua University Yuquan Hospital, Beijing, China
| | - Li-Zhen Cao
- Department of Radiology, Xuanwu Hospital, Capital Medical University, Beijing, China
| | - Guo-Jun Zhang
- Department of Functional Neurosurgery, Xuanwu Hospital, Capital Medical University, Beijing, China
| | - De-Hong Lu
- Department of Pathology, Xuanwu Hospital, Capital Medical University, Beijing, China
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Silva J, Sharma S, Cowell JK. Homozygous Deletion of the LGI1 Gene in Mice Leads to Developmental Abnormalities Resulting in Cortical Dysplasia. Brain Pathol 2014; 25:587-97. [PMID: 25346110 DOI: 10.1111/bpa.12225] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/25/2014] [Accepted: 10/21/2014] [Indexed: 01/02/2023] Open
Abstract
LGI1 mutations lead to an autosomal dominant form of epilepsy. Lgi1 mutant null mice develop seizures and show abnormal neuronal excitability. A fine structure analysis of the cortex in these mice demonstrated a subtle cortical dysplasia, preferentially affecting layers II-IV, associated with increased Foxp2 and Cux1-expressing neurons leading to blurring of the cortical layers. The hypercellularity observed in the null cortex resulted from an admixture of highly branched mature pyramidal neurons with short and poorly aligned axons as revealed by Golgi staining and immature small neurons with branched disoriented dendrites with reduced spine density and undersized, morphologically altered and round-headed spines. In vitro, hippocampal neurons revealed poor neurite outgrowth in null mice as well as reduced synapse formation. Electron microscopy demonstrated reduced spine-localized asymmetric (axospinous) synapses with postsynaptic densities and vesicle-loaded synapses in the mutant null cortex. The overall pathology in the null mice suggested cortical dyslamination most likely because of mislocalization of late-born neurons, with an admixture of those carrying suboptimally developed axons and dendrites with reduced functional synapses with normal neurons. Our study suggests that LGI1 has a role in regulating cortical development, which is increasingly becoming recognized as one of the causes of idiopathic epilepsy.
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Affiliation(s)
- Jeane Silva
- Cancer Center, Georgia Regents University, Augusta, GA
| | - Suash Sharma
- Cancer Center, Georgia Regents University, Augusta, GA.,Department of Pathology, Georgia Regents University, Augusta, GA
| | - John K Cowell
- Cancer Center, Georgia Regents University, Augusta, GA.,Department of Pathology, Georgia Regents University, Augusta, GA
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Ma L, Li XW, Zhang SJ, Yang F, Zhu GM, Yuan XB, Jiang W. Interleukin-1 beta guides the migration of cortical neurons. J Neuroinflammation 2014; 11:114. [PMID: 24950657 PMCID: PMC4084576 DOI: 10.1186/1742-2094-11-114] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/22/2014] [Accepted: 06/05/2014] [Indexed: 11/20/2022] Open
Abstract
Background Proinflammatory cytokine interleukin-1beta (IL-1β) is expressed at high levels in the developing brain and declines to low constitutive levels in the adult. However, the pathophysiological function of IL-1β during brain development remains elusive. In this study, we investigated the role of IL-1β in neuronal migration. Methods The Boyden transwell assay was used to examine the effects of IL-1β on the migration of dissociated primary cortical neurons. To determine the role of IL-1β in neuron leading process pathfinding, we employed a growth cone turning assay. In utero electroporation combined with RNAi technology was used to examine the neuronal migration in vivo during brain development in Sprague–Dawley rats. Results IL-1β at concentrations ranging from 0.1 to 10 ng/mL in the lower chamber of a transwell induced a significant increase in the number of migrating neurons in a dose-dependent manner. When IL-1β was simultaneously put in both the upper and lower chambers to eliminate the gradient, no significant differences in cell migration were observed. IL-1 receptor antagonist IL-1RA dose-dependently blocked the attractive effect of IL-1β on neuronal migration. Microscopic gradients of IL-1β were created near the growth cones of isolated neurons by repetitive pulsatile application of picoliters of a IL-1β-containing solution with a micropipette. We found that growth cones exhibited a clear bias toward the source of IL-1β at the end of a one hour period in the IL-1β gradient. No significant difference was observed in the rate of neurite extension between IL-1β and controls. We electroporated specific siRNA constructs against IL-1R1 mRNA into cortical progenitors at embryonic day 16 and examined the position and distribution of transfected cells in the somatosensory cortex at postnatal day 5. We found that neurons transfected with IL-1R1-siRNA displayed a severe retardation in radial migration, with about 83% of total cells unable to arrive at the upper cortical layers. Conclusions Our study suggests an essential contribution of IL-1β to neuronal migration during brain development, which provides a basis to understand the physiological roles of IL-1β in the developing brain and could have significant implications for the prevention of some neurodevelopment disorders due to abnormal neuronal migration.
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Affiliation(s)
| | | | | | | | | | | | - Wen Jiang
- Department of Neurology, Xijing Hospital, Fourth Military Medical University, Xi'an 710032, China.
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Leach JL, Greiner HM, Miles L, Mangano FT. Imaging Spectrum of Cortical Dysplasia in Children. Semin Roentgenol 2014; 49:99-111. [DOI: 10.1053/j.ro.2013.10.007] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
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Andrade CS, Otaduy MCG, Valente KDR, Maia DF, Park EJ, Valério RMF, Tsunemi MH, Leite CC. Phosphorus magnetic resonance spectroscopy in malformations of cortical development. Epilepsia 2011; 52:2276-84. [PMID: 21973076 DOI: 10.1111/j.1528-1167.2011.03281.x] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
PURPOSE The aim of this study was to evaluate phospholipid metabolism in patients with malformations of cortical development (MCDs). METHODS Thirty-seven patients with MCDs and 31 control subjects were studied using three-dimensional phosphorus magnetic resonance spectroscopy ((31)P-MRS) at 3.0 T. The voxels in the lesions and in the frontoparietal cortex of the control subjects were compared (the effective volumes were 12.5 cm(3)). Robust quantification methods were applied to fit the time-domain data to the following resonances: phosphoethanolamine (PE); phosphocholine (PC); inorganic phosphate (Pi); glycerophosphoethanolamine (GPE); glycerophosphocholine (GPC); phosphocreatine (PCr); and α-, β-, and γ-adenosine triphosphate (ATP). We also estimated the total ATP (ATP(t) = α-+β-+γ-ATP), phosphodiesters (PDE = GPC+GPE), phosphomonoesters (PME = PE+PC), and the PME/PDE, PCr/ATP(t) and PCr/Pi ratios. The magnesium (Mg(2+)) levels and pH values were calculated based on PCr, Pi, and β-ATP chemical shifts. KEY FINDINGS Compared to controls and assuming that a p-value < 0.05 indicates statistical significance, the patients with MCDs exhibited significantly lower pH values and higher Mg(2+) levels. In addition, the patients with MCDs had lower GPC and PDE and an increased PME/PDE ratio. SIGNIFICANCE Mg(2+) and pH are important in the regulation of bioenergetics and are involved in many electrical activity pathways in the brain. Our data support the idea that neurometabolic impairments occur during seizure onset and propagation. The GPC, PDE, and PME/PDE abnormalities also demonstrate that there are membrane turnover disturbances in patients with MCDs.
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Affiliation(s)
- Celi S Andrade
- Department of Radiology, Faculdade de Medicina da Universidade de São Paulo, São Paulo, Brazil.
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Andrade CS, Leite CDC. Malformations of cortical development: current concepts and advanced neuroimaging review. ARQUIVOS DE NEURO-PSIQUIATRIA 2011; 69:130-8. [DOI: 10.1590/s0004-282x2011000100024] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/20/2010] [Accepted: 08/12/2010] [Indexed: 11/22/2022]
Abstract
Malformations of cortical development (MCD) result from disruptions in the complex process of the human brain cortex formation and are highly associated to severe epilepsy, neurodevelopmental delay and motor dysfunction. Nowadays, magnetic resonance imaging (MRI) is the cornerstone of the work-up of patients with epilepsy and modern advanced imaging techniques have improved not only our ability to detect and characterize cortical malformations, but also in identifying associated functional abnormalities that are far beyond the structural visualized lesions. Herein, we address the most currently used classifications of MCD and make a concise review of the embryological process of cortical development. Our main goal is to summarize recent advances and new trends in diagnostic imaging techniques concerning MCD. Thereafter, follows a brief discussion of specific disorders and their radiological features.
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Blümcke I, Thom M, Aronica E, Armstrong DD, Vinters HV, Palmini A, Jacques TS, Avanzini G, Barkovich AJ, Battaglia G, Becker A, Cepeda C, Cendes F, Colombo N, Crino P, Cross JH, Delalande O, Dubeau F, Duncan J, Guerrini R, Kahane P, Mathern G, Najm I, Ozkara C, Raybaud C, Represa A, Roper SN, Salamon N, Schulze-Bonhage A, Tassi L, Vezzani A, Spreafico R. The clinicopathologic spectrum of focal cortical dysplasias: a consensus classification proposed by an ad hoc Task Force of the ILAE Diagnostic Methods Commission. Epilepsia 2010; 52:158-74. [PMID: 21219302 DOI: 10.1111/j.1528-1167.2010.02777.x] [Citation(s) in RCA: 1152] [Impact Index Per Article: 82.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/21/2022]
Abstract
PURPOSE Focal cortical dysplasias (FCD) are localized regions of malformed cerebral cortex and are very frequently associated with epilepsy in both children and adults. A broad spectrum of histopathology has been included in the diagnosis of FCD. An ILAE task force proposes an international consensus classification system to better characterize specific clinicopathological FCD entities. METHODS Thirty-two Task Force members have reevaluated available data on electroclinical presentation, imaging, neuropathological examination of surgical specimens as well as postsurgical outcome. KEY FINDINGS The ILAE Task Force proposes a three-tiered classification system. FCD Type I refers to isolated lesions, which present either as radial (FCD Type Ia) or tangential (FCD Type Ib) dyslamination of the neocortex, microscopically identified in one or multiple lobes. FCD Type II is an isolated lesion characterized by cortical dyslamination and dysmorphic neurons without (Type IIa) or with balloon cells (Type IIb). Hence, the major change since a prior classification represents the introduction of FCD Type III, which occurs in combination with hippocampal sclerosis (FCD Type IIIa), or with epilepsy-associated tumors (FCD Type IIIb). FCD Type IIIc is found adjacent to vascular malformations, whereas FCD Type IIId can be diagnosed in association with epileptogenic lesions acquired in early life (i.e., traumatic injury, ischemic injury or encephalitis). SIGNIFICANCE This three-tiered classification system will be an important basis to evaluate imaging, electroclinical features, and postsurgical seizure control as well as to explore underlying molecular pathomechanisms in FCD.
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Affiliation(s)
- Ingmar Blümcke
- Department of Neuropathology, University Hospital Erlangen, Erlangen, Germany.
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Focal Cortical Dysplasias: clinical implication of neuropathological classification systems. Acta Neuropathol 2010; 120:359-67. [PMID: 20607544 DOI: 10.1007/s00401-010-0714-x] [Citation(s) in RCA: 59] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/16/2010] [Revised: 06/22/2010] [Accepted: 06/23/2010] [Indexed: 10/19/2022]
Abstract
Focal Cortical Dysplasias (FCDs) are highly epileptogenic brain lesions and are a frequent cause for drug-resistant focal epilepsies in humans. FCDs present with variable histopathological patterns, including architectural, cytoarchitectural or white matter abnormalities. Pathomechanisms compromising neuroblast proliferation, migration, or differentiation are likely to play a role in the etiology of FCD variants. FCDs were subsumed, therefore, into the broad spectrum of malformations of cortical development. The most frequent subtype comprises FCD Type II, which in general occurs as isolated lesion in extratemporal location and is histopathologically characterized by dysmorphic neurons (Type IIA) and balloon cells (Type IIB). Neuroimaging hallmarks include hyperintense T2-signaling and a "transmantle sign". Electrophysiological recordings show peculiar interictal spike patterns and complete surgical resection results in favorable seizure control. In contrast, FCD Type I can be identified in young children with severe epilepsy and psychomotor retardation. Parietal, temporal, and occipital lobes may be involved in seizure generation, although neuroimaging often reveals normal contrast intensities. Surgical resection strategies ameliorate seizure frequencies in many children, whereas complete seizure relief can be achieved only in rare cases. According to the currently used FCD classification system, the same histopathological FCD Type I variant can be diagnosed as associated lesion in the large cohort of epilepsy patients with hippocampal sclerosis, low-grade glio-neuronal tumors, vascular malformations, or glial scarring. MRI is often not helpful to detect the dysplastic cortical areas. In addition, there is no specific electrophysiological pattern for an associated dysplastic lesion. Surgical resection of the epileptogenic area results, however, in favorable seizure control. These findings argue for a revised neuropathological classification system that distinguishes isolated versus associated FCD variants to obtain a better correlation with electro-clinical findings and prediction of postsurgical seizure control.
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