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Fila M, Przyslo L, Derwich M, Pawlowska E, Blasiak J. Potential of focal cortical dysplasia in migraine pathogenesis. Cereb Cortex 2024; 34:bhae158. [PMID: 38615241 DOI: 10.1093/cercor/bhae158] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/14/2024] [Revised: 03/21/2024] [Accepted: 03/23/2024] [Indexed: 04/15/2024] Open
Abstract
Focal cortical dysplasias are abnormalities of the cerebral cortex associated with an elevated risk of neurological disturbances. Cortical spreading depolarization/depression is a correlate of migraine aura/headache and a trigger of migraine pain mechanisms. However, cortical spreading depolarization/depression is associated with cortical structural changes, which can be classified as transient focal cortical dysplasias. Migraine is reported to be associated with changes in various brain structures, including malformations and lesions in the cortex. Such malformations may be related to focal cortical dysplasias, which may play a role in migraine pathogenesis. Results obtained so far suggest that focal cortical dysplasias may belong to the causes and consequences of migraine. Certain focal cortical dysplasias may lower the threshold of cortical excitability and facilitate the action of migraine triggers. Migraine prevalence in epileptic patients is higher than in the general population, and focal cortical dysplasias are an established element of epilepsy pathogenesis. In this narrative/hypothesis review, we present mainly information on cortical structural changes in migraine, but studies on structural alterations in deep white matter and other brain regions are also presented. We develop the hypothesis that focal cortical dysplasias may be causally associated with migraine and link pathogeneses of migraine and epilepsy.
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Affiliation(s)
- Michal Fila
- Department of Developmental Neurology and Epileptology, Polish Mother's Memorial Hospital Research Institute, Rzgowska 281/289, 93-338 Lodz, Łódzkie, Poland
| | - Lukasz Przyslo
- Department of Developmental Neurology and Epileptology, Polish Mother's Memorial Hospital Research Institute, Rzgowska 281/289, 93-338 Lodz, Łódzkie, Poland
| | - Marcin Derwich
- Department of Developmental Dentistry, Medical University of Lodz, Pomorska 251, 90-647 Lodz, Łódzkie, Poland
| | - Ezbieta Pawlowska
- Department of Developmental Dentistry, Medical University of Lodz, Pomorska 251, 90-647 Lodz, Łódzkie, Poland
| | - Janusz Blasiak
- Faculty of Medicine, Collegium Medicum, Mazovian Academy in Plock, Plac Generała Dabrowskiego 2, 09-420 Plock, Mazowieckie, Poland
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2
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Supernumerary neurons within the cerebral cortical subplate in autism spectrum disorders. Brain Res 2021; 1760:147350. [PMID: 33607045 DOI: 10.1016/j.brainres.2021.147350] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/15/2020] [Revised: 02/01/2021] [Accepted: 02/02/2021] [Indexed: 12/11/2022]
Abstract
Autism spectrum disorders (ASDs) involve alterations to cortical connectivity that manifest as reduced coordinated activity between cortical regions. The neurons of the cortical subplate are a major contributor to establishing thalamocortical, corticothalamic and corticocortical long-range connections and only a subset of this cell population survives into adulthood. Previous reports of an indistinct gray-white matter boundary in subjects with ASD suggest that the adjacent subplate may also show organizational abnormalities. Frozen human postmortem tissue samples from the parietal lobe (BA7) were used to evaluate white-matter neuron densities adjacent to layer VI with an antibody to NeuN. In addition, fixed postmortem tissue samples from frontal (BA9), parietal (BA7) and temporal lobe (BA21) locations, were stained with a Golgi-Kopsch procedure, and used to examine the morphology of these neuronal profiles. Relative to control cases, ASD subjects showed a large average density increase of NeuN-positive profiles of 44.7 percent. The morphologies of these neurons were consistent with subplate cells of the fusiform, polymorphic and pyramidal cell types. Lower ratios of fusiform to other cell types are found early in development and although adult ASD subjects showed consistently lower ratios, these differences were not significant. The increased number of retained subplate profiles, along with cell type ratios redolent of earlier developmental stages, suggests either an abnormal initial population or a partial failure of the apoptosis seen in neurotypical development. These results indicate abnormalities within a neuron population that plays multiple roles in the developing and mature cerebral cortex, including the establishment of long-range cortical connections.
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3
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Pogledic I, Schwartz E, Mitter C, Baltzer P, Milos RI, Gruber GM, Brugger PC, Hainfellner J, Bettelheim D, Langs G, Kasprian G, Prayer D. The Subplate Layers: The Superficial and Deep Subplate Can be Discriminated on 3 Tesla Human Fetal Postmortem MRI. Cereb Cortex 2020; 30:5038-5048. [PMID: 32377685 DOI: 10.1093/cercor/bhaa099] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/28/2019] [Revised: 03/24/2020] [Accepted: 03/24/2020] [Indexed: 01/19/2023] Open
Abstract
The subplate (SP) is a transient structure of the human fetal brain that becomes the most prominent layer of the developing pallium during the late second trimester. It is important in the formation of thalamocortical and cortico-cortical connections. The SP is vulnerable in perinatal brain injury and may play a role in complex neurodevelopmental disorders, such as schizophrenia and autism. Nine postmortem fetal human brains (19-24 GW) were imaged on a 3 Tesla MR scanner and the T2-w images in the frontal and temporal lobes were compared, in each case, with the histological slices of the same brain. The brains were confirmed to be without any brain pathology. The purpose of this study was to demonstrate that the superficial SP (sSP) and deep SP (dSP) can be discriminated on postmortem MR images. More specifically, we aimed to clarify that the observable, thin, hyperintense layer below the cortical plate in the upper SP portion on T2-weighted MR images has an anatomical correspondence to the histologically established sSP. Therefore, the distinction between the sSP and dSP layers, using clinically available MR imaging methodology, is possible in postmortem MRI and can help in the imaging interpretation of the fetal cerebral layers.
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Affiliation(s)
- Ivana Pogledic
- Division of Neuroradiology and Musculoskeletal Radiology, Department of Biomedical Imaging and Image-Guided Therapy, Medical University of Vienna, 1090 Vienna, Austria
| | - Ernst Schwartz
- Computational Imaging Research Lab, Department of Biomedical Imaging and Image-Guided Therapy, Medical University of Vienna, 1090 Vienna, Austria
| | - Christian Mitter
- Division of Neuroradiology and Musculoskeletal Radiology, Department of Biomedical Imaging and Image-Guided Therapy, Medical University of Vienna, 1090 Vienna, Austria
| | - Pascal Baltzer
- Division of Molecular and Gender Imaging, Department of Biomedical Imaging and Image-Guided Therapy, Medical University of Vienna, 1090 Vienna, Austria
| | - Ruxandra-Iulia Milos
- Division of Molecular and Gender Imaging, Department of Biomedical Imaging and Image-Guided Therapy, Medical University of Vienna, 1090 Vienna, Austria
| | - Gerlinde Maria Gruber
- Department of Anatomy and Biomechanics, Karl Landsteiner University of Health Sciences, 3500 Krems, Austria
| | - Peter C Brugger
- Division of Anatomy, Center for Anatomy and Cell Biology, Medical University of Vienna, 1090 Vienna, Austria
| | | | - Dieter Bettelheim
- Division of Obstetrics and Feto-Maternal Medicine, Department of Obstetrics and Gynecology, Medical University of Vienna, 1090 Vienna, Austria
| | - Georg Langs
- Computational Imaging Research Lab, Department of Biomedical Imaging and Image-Guided Therapy, Medical University of Vienna, 1090 Vienna, Austria
| | - Gregor Kasprian
- Division of Neuroradiology and Musculoskeletal Radiology, Department of Biomedical Imaging and Image-Guided Therapy, Medical University of Vienna, 1090 Vienna, Austria
| | - Daniela Prayer
- Division of Neuroradiology and Musculoskeletal Radiology, Department of Biomedical Imaging and Image-Guided Therapy, Medical University of Vienna, 1090 Vienna, Austria
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Wang Y, Zhou Y, Wang H, Cui J, Nguchu BA, Zhang X, Qiu B, Wang X, Zhu M. Voxel-based automated detection of focal cortical dysplasia lesions using diffusion tensor imaging and T2-weighted MRI data. Epilepsy Behav 2018; 84:127-134. [PMID: 29793134 DOI: 10.1016/j.yebeh.2018.04.005] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 02/05/2018] [Revised: 03/31/2018] [Accepted: 04/13/2018] [Indexed: 12/16/2022]
Abstract
The aim of this study was to automatically detect focal cortical dysplasia (FCD) lesions in patients with extratemporal lobe epilepsy by relying on diffusion tensor imaging (DTI) and T2-weighted magnetic resonance imaging (MRI) data. We implemented an automated classifier using voxel-based multimodal features to identify gray and white matter abnormalities of FCD in patient cohorts. In addition to the commonly used T2-weighted image intensity feature, DTI-based features were also utilized. A Gaussian processes for machine learning (GPML) classifier was tested on 12 patients with FCD (8 with histologically confirmed FCD) scanned at 1.5 T and cross-validated using a leave-one-out strategy. Moreover, we compared the multimodal GPML paradigm's performance with that of single modal GPML and classical support vector machine (SVM). Our results demonstrated that the GPML performance on DTI-based features (mean AUC = 0.63) matches with the GPML performance on T2-weighted image intensity feature (mean AUC = 0.64). More promisingly, GPML yielded significantly improved performance (mean AUC = 0.76) when applying DTI-based features to multimodal paradigm. Based on the results, it can also be clearly stated that the proposed GPML strategy performed better and is robust to unbalanced dataset contrary to SVM that performed poorly (AUC = 0.69). Therefore, the GPML paradigm using multimodal MRI data containing DTI modality has promising result towards detection of the FCD lesions and provides an effective direction for future researches.
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Affiliation(s)
- Yanming Wang
- Centers for Biomedical Engineering, University of Science and Technology of China, Hefei, China
| | - Yawen Zhou
- Centers for Biomedical Engineering, University of Science and Technology of China, Hefei, China
| | - Huijuan Wang
- Centers for Biomedical Engineering, University of Science and Technology of China, Hefei, China
| | - Jin Cui
- Centers for Biomedical Engineering, University of Science and Technology of China, Hefei, China
| | | | - Xufei Zhang
- Department of Radiology, Sanbo Brain Hospital, Capital Medical University, Beijing, China
| | - Bensheng Qiu
- Centers for Biomedical Engineering, University of Science and Technology of China, Hefei, China
| | - Xiaoxiao Wang
- Centers for Biomedical Engineering, University of Science and Technology of China, Hefei, China.
| | - Mingwang Zhu
- Department of Radiology, Sanbo Brain Hospital, Capital Medical University, Beijing, China.
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5
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Avansini SH, Torres FR, Vieira AS, Dogini DB, Rogerio F, Coan AC, Morita ME, Guerreiro MM, Yasuda CL, Secolin R, Carvalho BS, Borges MG, Almeida VS, Araújo PAOR, Queiroz L, Cendes F, Lopes-Cendes I. Dysregulation of NEUROG2 plays a key role in focal cortical dysplasia. Ann Neurol 2018; 83:623-635. [PMID: 29461643 PMCID: PMC5901021 DOI: 10.1002/ana.25187] [Citation(s) in RCA: 19] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/22/2016] [Revised: 02/16/2018] [Accepted: 02/16/2018] [Indexed: 12/31/2022]
Abstract
OBJECTIVE Focal cortical dysplasias (FCDs) are an important cause of drug-resistant epilepsy. In this work, we aimed to investigate whether abnormal gene regulation, mediated by microRNA, could be involved in FCD type II. METHODS We used total RNA from the brain tissue of 16 patients with FCD type II and 28 controls. MicroRNA expression was initially assessed by microarray. Quantitative polymerase chain reaction, in situ hybridization, luciferase reporter assays, and deep sequencing for genes in the mTOR pathway were performed to validate and further explore our initial study. RESULTS hsa-let-7f (p = 0.039), hsa-miR-31 (p = 0.0078), and hsa-miR34a (p = 0.021) were downregulated in FCD type II, whereas a transcription factor involved in neuronal and glial fate specification, NEUROG2 (p < 0.05), was upregulated. We also found that the RND2 gene, a NEUROG2-target, is upregulated (p < 0.001). In vitro experiments showed that hsa-miR-34a downregulates NEUROG2 by binding to its 5'-untranslated region. Moreover, we observed strong nuclear expression of NEUROG2 in balloon cells and dysmorphic neurons and found that 28.5% of our patients presented brain somatic mutations in genes of the mTOR pathway. INTERPRETATION Our findings suggest a new molecular mechanism, in which NEUROG2 has a pivotal and central role in the pathogenesis of FCD type II. In this way, we found that the downregulation of hsa-miR-34a leads to upregulation of NEUROG2, and consequently to overexpression of the RND2 gene. These findings indicate that a faulty coupling in neuronal differentiation and migration mechanisms may explain the presence of aberrant cells and complete dyslamination in FCD type II. Ann Neurol 2018;83:623-635.
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Affiliation(s)
- Simoni H Avansini
- Department of Medical Genetics, University of Campinas and Brazilian Institute of Neuroscience and Neurotechnology, Campinas, Brazil
| | - Fábio R Torres
- Department of Medical Genetics, University of Campinas and Brazilian Institute of Neuroscience and Neurotechnology, Campinas, Brazil
| | - André S Vieira
- Department of Medical Genetics, University of Campinas and Brazilian Institute of Neuroscience and Neurotechnology, Campinas, Brazil
| | - Danyella B Dogini
- Department of Medical Genetics, University of Campinas and Brazilian Institute of Neuroscience and Neurotechnology, Campinas, Brazil
| | - Fabio Rogerio
- Department of Anatomical Pathology, University of Campinas and Brazilian Institute of Neuroscience and Neurotechnology, Campinas, Brazil
| | - Ana C Coan
- Department of Neurology, University of Campinas and Brazilian Institute of Neuroscience and Neurotechnology, Campinas, Brazil
| | - Marcia E Morita
- Department of Neurology, University of Campinas and Brazilian Institute of Neuroscience and Neurotechnology, Campinas, Brazil
| | - Marilisa M Guerreiro
- Department of Neurology, University of Campinas and Brazilian Institute of Neuroscience and Neurotechnology, Campinas, Brazil
| | - Clarissa L Yasuda
- Department of Neurology, University of Campinas and Brazilian Institute of Neuroscience and Neurotechnology, Campinas, Brazil
| | - Rodrigo Secolin
- Department of Medical Genetics, University of Campinas and Brazilian Institute of Neuroscience and Neurotechnology, Campinas, Brazil
| | - Benilton S Carvalho
- Department of Medical Genetics, University of Campinas and Brazilian Institute of Neuroscience and Neurotechnology, Campinas, Brazil
| | - Murilo G Borges
- Department of Medical Genetics, University of Campinas and Brazilian Institute of Neuroscience and Neurotechnology, Campinas, Brazil
| | - Vanessa S Almeida
- Department of Medical Genetics, University of Campinas and Brazilian Institute of Neuroscience and Neurotechnology, Campinas, Brazil
| | - Patrícia A O R Araújo
- Department of Medical Genetics, University of Campinas and Brazilian Institute of Neuroscience and Neurotechnology, Campinas, Brazil
| | - Luciano Queiroz
- Department of Anatomical Pathology, University of Campinas and Brazilian Institute of Neuroscience and Neurotechnology, Campinas, Brazil
| | - Fernando Cendes
- Department of Neurology, University of Campinas and Brazilian Institute of Neuroscience and Neurotechnology, Campinas, Brazil
| | - Iscia Lopes-Cendes
- Department of Medical Genetics, University of Campinas and Brazilian Institute of Neuroscience and Neurotechnology, Campinas, Brazil
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6
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Andrews DS, Avino TA, Gudbrandsen M, Daly E, Marquand A, Murphy CM, Lai MC, Lombardo MV, Ruigrok ANV, Williams SC, Bullmore ET, The Mrc Aims Consortium, Suckling J, Baron-Cohen S, Craig MC, Murphy DGM, Ecker C. In Vivo Evidence of Reduced Integrity of the Gray-White Matter Boundary in Autism Spectrum Disorder. Cereb Cortex 2018; 27:877-887. [PMID: 28057721 PMCID: PMC6093436 DOI: 10.1093/cercor/bhw404] [Citation(s) in RCA: 27] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/12/2016] [Accepted: 12/20/2016] [Indexed: 11/16/2022] Open
Abstract
Atypical cortical organization and reduced integrity of the gray–white matter boundary have been reported by postmortem studies in individuals with autism spectrum disorder (ASD). However, there are no in vivo studies that examine these particular features of cortical organization in ASD. Hence, we used structural magnetic resonance imaging to examine differences in tissue contrast between gray and white matter in 98 adults with ASD and 98 typically developing controls, to test the hypothesis that individuals with ASD have significantly reduced tissue contrast. More specifically, we examined contrast as a percentage between gray and white matter tissue signal intensities (GWPC) sampled at the gray–white matter boundary, and across different cortical layers. We found that individuals with ASD had significantly reduced GWPC in several clusters throughout the cortex (cluster, P < 0.05). As expected, these reductions were greatest when tissue intensities were sampled close to gray–white matter interface, which indicates a less distinct gray–white matter boundary in ASD. Our in vivo findings of reduced GWPC in ASD are therefore consistent with prior postmortem findings of a less well-defined gray–white matter boundary in ASD. Taken together, these results indicate that GWPC might be utilized as an in vivo proxy measure of atypical cortical microstructural organization in future studies.
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Affiliation(s)
- Derek Sayre Andrews
- Department of Forensic and Neurodevelopmental Sciences, Sackler Institute for Translational Neurodevelopment, Institute of Psychiatry, Psychology and Neuroscience, King's College London, London SE5 8AF, UK
| | - Thomas A Avino
- Department of Psychiatry and Behavioral Sciences, M.I.N.D. Institute, University of California Davis, Sacramento, CA, USA
| | - Maria Gudbrandsen
- Department of Forensic and Neurodevelopmental Sciences, Sackler Institute for Translational Neurodevelopment, Institute of Psychiatry, Psychology and Neuroscience, King's College London, London SE5 8AF, UK
| | - Eileen Daly
- Department of Forensic and Neurodevelopmental Sciences, Sackler Institute for Translational Neurodevelopment, Institute of Psychiatry, Psychology and Neuroscience, King's College London, London SE5 8AF, UK
| | - Andre Marquand
- Donders Institute for Brain, Cognition and Behaviour, Radboud University, Nijmegen, The Netherlands.,Centre for Neuroimaging Sciences, Institute of Psychiatry, Psychology and Neuroscience, King's College, London, UK
| | - Clodagh M Murphy
- Department of Forensic and Neurodevelopmental Sciences, Sackler Institute for Translational Neurodevelopment, Institute of Psychiatry, Psychology and Neuroscience, King's College London, London SE5 8AF, UK.,National Autism Unit, Bethlem Royal Hospital, South London and Maudsley NHS Foundation Trust, London, UK
| | - Meng-Chuan Lai
- Autism Research Centre, Department of Psychiatry, University of Cambridge, Cambridge, UK.,Child and Youth Mental Health Collaborative at the Centre for Addiction and Mental Health and The Hospital for Sick Children, Department of Psychiatry, University of Toronto, Toronto, Canada.,Department of Psychiatry, National Taiwan University Hospital and College of Medicine, Taipei, Taiwan
| | - Michael V Lombardo
- Autism Research Centre, Department of Psychiatry, University of Cambridge, Cambridge, UK.,Department of Psychology & Center for Applied Neuroscience, University of Cyprus, Nicosia, Cyprus
| | - Amber N V Ruigrok
- Autism Research Centre, Department of Psychiatry, University of Cambridge, Cambridge, UK
| | - Steven C Williams
- Centre for Neuroimaging Sciences, Institute of Psychiatry, Psychology and Neuroscience, King's College, London, UK
| | - Edward T Bullmore
- Brain Mapping Unit, Department of Psychiatry, University of Cambridge, Cambridge, UK
| | - The Mrc Aims Consortium
- The Medical Research Council Autism Imaging Multicentre Study Consortium (MRC AIMS Consortium) is a UK collaboration between the Institute of Psychiatry, Psychology and Neuroscience at King's College, London, the Autism Research Centre, University of Cambridge, and the Autism Research Group, University of Oxford. The Consortium members in alphabetical order are as follows: Anthony J. Bailey (Oxford), Simon Baron-Cohen (Cambridge), Patrick F. Bolton (IoP), Edward T. Bullmore (Cambridge), Sarah Carrington (Oxford), Marco Catani (IoPPN), Bhismadev Chakrabarti (Cambridge), Michael C. Craig (IoPPN), Eileen M. Daly (IoPPN), Sean C.L. Deoni (IoPPN), Christine Ecker (IoPPN), Francesca Happé (IoPPN), Julian Henty (Cambridge), Peter Jezzard (Oxford), Patrick Johnston (IoPPN), Derek K. Jones (IoPPN), Meng-Chuan Lai (Cambridge), Michael V. Lombardo (Cambridge), Anya Madden (IoPPN), Diane Mullins (IoPPN), Clodagh M. Murphy (IoPPN), Declan G.M. Murphy (IoPPN), Greg Pasco (Cambridge), Amber N.V. Ruigrok (Cambridge), Susan A. Sadek (Cambridge), Debbie Spain (IoPPN), Rose Stewart (Oxford), John Suckling (Cambridge), Sally J. Wheelwright (Cambridge), Steven C. Williams (IoPPN), and C. Ellie Wilson (IoPPN)
| | - John Suckling
- Department of Child and Adolescent Psychiatry, Psychosomatics and Psychotherapy, Universitätsklinikum Frankfurt am Main, Goethe-University Frankfurt am Main, Frankfurt, Germany
| | - Simon Baron-Cohen
- Autism Research Centre, Department of Psychiatry, University of Cambridge, Cambridge, UK
| | - Michael C Craig
- Department of Forensic and Neurodevelopmental Sciences, Sackler Institute for Translational Neurodevelopment, Institute of Psychiatry, Psychology and Neuroscience, King's College London, London SE5 8AF, UK.,National Autism Unit, Bethlem Royal Hospital, South London and Maudsley NHS Foundation Trust, London, UK
| | - Declan G M Murphy
- Department of Forensic and Neurodevelopmental Sciences, Sackler Institute for Translational Neurodevelopment, Institute of Psychiatry, Psychology and Neuroscience, King's College London, London SE5 8AF, UK.,National Autism Unit, Bethlem Royal Hospital, South London and Maudsley NHS Foundation Trust, London, UK
| | - Christine Ecker
- Department of Forensic and Neurodevelopmental Sciences, Sackler Institute for Translational Neurodevelopment, Institute of Psychiatry, Psychology and Neuroscience, King's College London, London SE5 8AF, UK.,Department of Child and Adolescent Psychiatry, Psychosomatics and Psychotherapy, Universitätsklinikum Frankfurt am Main, Goethe-University Frankfurt am Main, Frankfurt, Germany
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7
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Mizutani KI. Physiological significance of multipolar cells generated from neural stem cells and progenitors for the establishment of neocortical cytoarchitecture. Genes Cells 2017; 23:6-15. [PMID: 29193520 DOI: 10.1111/gtc.12546] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/11/2017] [Accepted: 10/29/2017] [Indexed: 11/28/2022]
Abstract
Neurogenesis encompasses an entire set of events that leads to the generation of newborn neurons from neural stem cells and more committed progenitor cells, including cell division, the production of migratory precursors and their progeny, differentiation and integration into circuits. In particular, the precise control of neuronal migration and morphological changes is essential for the development of the neocortex. Postmitotic cells within the intermediate zone have been found to transiently assume a characteristic "multipolar" morphology, after which a multipolar-to-bipolar transition occurs before the cells enter the cortical plate; however, the importance of this multipolar phase in the establishment of mature cortical cytoarchitecture and the precise genetic control of this phase remains largely unknown. Thus, this review article focuses on the multipolar phase in the developing neocortex. It begins by summarizing the molecular mechanism that underlies multipolar migration for the regulation of each step in multipolar phase in intermediate zone. The physiological significance of this multipolar phase in the establishment of mature cortical lamination and neurodevelopmental disorders associated with migration defects is then described.
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Affiliation(s)
- Ken-Ichi Mizutani
- Laboratory of Stem Cell Biology, Graduate School of Pharmaceutical Sciences, Kobe Gakuin University, Kobe, Japan
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8
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Abstract
Epilepsy is one of the most common neurologic disorders, affecting about 50 million people worldwide. The disease is characterized by recurrent seizures, which are due to aberrant neuronal networks resulting in synchronous discharges. The term epilepsy encompasses a large spectrum of syndromes and diseases with different etiopathogenesis. The recent development of imaging and epilepsy surgery techniques is now enabling the identification of structural abnormalities that are part of the epileptic network, and the removal of these lesions may result in control of seizures. Access of this clinically well-characterized neurosurgical material has provided neuropathologists with the opportunity to study a variety of structural brain abnormalities associated with epilepsy, by combining traditional routine histopathologic methods with molecular genetics and functional analysis of the resected tissue. This approach has contributed greatly to a better diagnosis and classification of these structural lesions, and has provided important new insights into their pathogenesis and epileptogenesis. The present chapter provides a detailed description of the large spectrum of histopathologic findings encountered in epilepsy surgery patients, addressing in particular the nonneoplastic pathologies, including hippocampal sclerosis, malformations of cortical development, Sturge-Weber syndrome, and Rasmussen encephalitis, and reviews current knowledge regarding the underlying molecular pathomechanisms and cellular mechanisms mediating hyperexcitability.
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Affiliation(s)
- Eleonora Aronica
- Department of Neuropathology, Academic Medical Center and Swammerdam Institute for Life Sciences, Center for Neuroscience, University of Amsterdam, Amsterdam, the Netherlands; Stichting Epilepsie Instellingen Nederland, the Netherlands.
| | - Angelika Mühlebner
- Department of Neuropathology, Academic Medical Center and Swammerdam Institute for Life Sciences, Center for Neuroscience, University of Amsterdam, Amsterdam, the Netherlands
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9
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Siedlecka M, Grajkowska W, Galus R, Dembowska-Bagińska B, Jóźwiak J. Focal cortical dysplasia: Molecular disturbances and clinicopathological classification (Review). Int J Mol Med 2016; 38:1327-1337. [DOI: 10.3892/ijmm.2016.2760] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/29/2016] [Accepted: 06/23/2016] [Indexed: 11/05/2022] Open
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10
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Mühlebner A, Iyer AM, van Scheppingen J, Anink JJ, Jansen FE, Veersema TJ, Braun KP, Spliet WGM, van Hecke W, Söylemezoğlu F, Feucht M, Krsek P, Zamecnik J, Bien CG, Polster T, Coras R, Blümcke I, Aronica E. Specific pattern of maturation and differentiation in the formation of cortical tubers in tuberous sclerosis omplex (TSC): evidence from layer-specific marker expression. J Neurodev Disord 2016; 8:9. [PMID: 27042238 PMCID: PMC4818922 DOI: 10.1186/s11689-016-9142-0] [Citation(s) in RCA: 21] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 11/23/2015] [Accepted: 03/08/2016] [Indexed: 03/12/2023] Open
Abstract
BACKGROUND Tuberous sclerosis complex (TSC) is a multisystem disorder that results from mutations in the TSC1 or TSC2 genes, leading to constitutive activation of the mammalian target of rapamycin (mTOR) signaling pathway. Cortical tubers represent typical lesions of the central nervous system (CNS) in TSC. The pattern of cortical layering disruption observed in brain tissue of TSC patients is not yet fully understood, and little is known about the origin and phenotype of individual abnormal cell types recognized in tubers. METHODS In the present study, we aimed to characterize dysmorphic neurons (DNs) and giant cells (GCs) of cortical tubers using neocortical layer-specific markers (NeuN, SMI32, Tbr1, Satb2, Cux2, ER81, and RORβ) and to compare the features with the histo-morphologically similar focal cortical dysplasia (FCD) type IIb. We studied a cohort of nine surgically resected cortical tubers, five FCD type IIb, and four control samples using immunohistochemistry and in situ hybridization. RESULTS Cortical tuber displayed a prominent cell loss in all cortical layers. Moreover, we observed altered proportions of layer-specific markers within the dysplastic region. DNs, in both tubers and FCD type IIb, were found positive for different cortical layer markers, regardless of their laminar location, and their immunophenotype resembles that of cortical projection neurons. CONCLUSIONS These findings demonstrate that, similar to FCD type IIb, cortical layering is markedly disturbed in cortical tubers of TSC patients. Distribution of these disturbances is comparable in all tubers and suggests a dysmaturation affecting early and late migratory patterns, with a more severe impairment of the late stage of maturation.
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Affiliation(s)
- Angelika Mühlebner
- Department of (Neuro) Pathology, Academic Medical Center, Amsterdam, The Netherlands ; Department of Pediatrics, Medical University Vienna, Vienna, Austria
| | - Anand M Iyer
- Department of (Neuro) Pathology, Academic Medical Center, Amsterdam, The Netherlands
| | | | - Jasper J Anink
- Department of (Neuro) Pathology, Academic Medical Center, Amsterdam, The Netherlands
| | - Floor E Jansen
- Department of Pediatric Neurology, Brain Center Rudolf Magnus, University Medical Center Utrecht, Utrecht, The Netherlands
| | - Tim J Veersema
- Department of Pediatric Neurology, Brain Center Rudolf Magnus, University Medical Center Utrecht, Utrecht, The Netherlands
| | - Kees P Braun
- Department of Pediatric Neurology, Brain Center Rudolf Magnus, University Medical Center Utrecht, Utrecht, The Netherlands
| | - Wim G M Spliet
- Department of Pathology, University Medical Center Utrecht, Utrecht, The Netherlands
| | - Wim van Hecke
- Department of Pathology, University Medical Center Utrecht, Utrecht, The Netherlands
| | - Figen Söylemezoğlu
- Department of Pathology, Faculty of Medicine, Hacettepe University, Ankara, Turkey
| | - Martha Feucht
- Department of Pediatrics, Medical University Vienna, Vienna, Austria
| | - Pavel Krsek
- Department of Neurology, Charles University, 2nd Faculty of Medicine, Motol University Hospital, Prague, Czech Republic
| | - Josef Zamecnik
- Department of Pathology and Molecular Medicine, Charles University, 2nd Faculty of Medicine, Motol University Hospital, Prague, Czech Republic
| | | | - Tilman Polster
- Epilepsy Centre Bethel, Krankenhaus Mara, Bielefeld, Germany
| | - Roland Coras
- Department of Neuropathology, University Hospital Erlangen, Erlangen, Germany
| | - Ingmar Blümcke
- Department of Neuropathology, University Hospital Erlangen, Erlangen, Germany
| | - Eleonora Aronica
- Department of (Neuro) Pathology, Academic Medical Center, Amsterdam, The Netherlands ; Swammerdam Institute for Life Sciences, Center for Neuroscience, University of Amsterdam, Amsterdam, The Netherlands ; Stichting Epilepsie Instellingen Nederland (SEIN), Heemstede, The Netherlands
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Caciagli L, Bernhardt BC, Hong SJ, Bernasconi A, Bernasconi N. Functional network alterations and their structural substrate in drug-resistant epilepsy. Front Neurosci 2014; 8:411. [PMID: 25565942 PMCID: PMC4263093 DOI: 10.3389/fnins.2014.00411] [Citation(s) in RCA: 52] [Impact Index Per Article: 5.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/03/2014] [Accepted: 11/24/2014] [Indexed: 12/24/2022] Open
Abstract
The advent of MRI has revolutionized the evaluation and management of drug-resistant epilepsy by allowing the detection of the lesion associated with the region that gives rise to seizures. Recent evidence indicates marked chronic alterations in the functional organization of lesional tissue and large-scale cortico-subcortical networks. In this review, we focus on recent methodological developments in functional MRI (fMRI) analysis techniques and their application to the two most common drug-resistant focal epilepsies, i.e., temporal lobe epilepsy related to mesial temporal sclerosis and extra-temporal lobe epilepsy related to focal cortical dysplasia. We put particular emphasis on methodological developments in the analysis of task-free or “resting-state” fMRI to probe the integrity of intrinsic networks on a regional, inter-regional, and connectome-wide level. In temporal lobe epilepsy, these techniques have revealed disrupted connectivity of the ipsilateral mesiotemporal lobe, together with contralateral compensatory reorganization and striking reconfigurations of large-scale networks. In cortical dysplasia, initial observations indicate functional alterations in lesional, peri-lesional, and remote neocortical regions. While future research is needed to critically evaluate the reliability, sensitivity, and specificity, fMRI mapping promises to lend distinct biomarkers for diagnosis, presurgical planning, and outcome prediction.
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Affiliation(s)
- Lorenzo Caciagli
- Neuroimaging of Epilepsy Laboratory, McConnell Brain Imaging Center, Montreal Neurological Institute and Hospital, McGill University Montreal, QC, Canada
| | - Boris C Bernhardt
- Neuroimaging of Epilepsy Laboratory, McConnell Brain Imaging Center, Montreal Neurological Institute and Hospital, McGill University Montreal, QC, Canada
| | - Seok-Jun Hong
- Neuroimaging of Epilepsy Laboratory, McConnell Brain Imaging Center, Montreal Neurological Institute and Hospital, McGill University Montreal, QC, Canada
| | - Andrea Bernasconi
- Neuroimaging of Epilepsy Laboratory, McConnell Brain Imaging Center, Montreal Neurological Institute and Hospital, McGill University Montreal, QC, Canada
| | - Neda Bernasconi
- Neuroimaging of Epilepsy Laboratory, McConnell Brain Imaging Center, Montreal Neurological Institute and Hospital, McGill University Montreal, QC, Canada
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Abdijadid S, Mathern GW, Levine MS, Cepeda C. Basic mechanisms of epileptogenesis in pediatric cortical dysplasia. CNS Neurosci Ther 2014; 21:92-103. [PMID: 25404064 DOI: 10.1111/cns.12345] [Citation(s) in RCA: 59] [Impact Index Per Article: 5.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/18/2014] [Revised: 09/29/2014] [Accepted: 10/03/2014] [Indexed: 12/25/2022] Open
Abstract
Cortical dysplasia (CD) is a neurodevelopmental disorder due to aberrant cell proliferation and differentiation. Advances in neuroimaging have proven effective in early identification of the more severe lesions and timely surgical removal to treat epilepsy. However, the exact mechanisms of epileptogenesis are not well understood. This review examines possible mechanisms based on anatomical and electrophysiological studies. CD can be classified as CD type I consisting of architectural abnormalities, CD type II with the presence of dysmorphic cytomegalic neurons and balloon cells, and CD type III which occurs in association with other pathologies. Use of freshly resected brain tissue has allowed a better understanding of basic mechanisms of epileptogenesis and has delineated the role of abnormal cells and synaptic activity. In CD type II, it was demonstrated that balloon cells do not initiate epileptic activity, whereas dysmorphic cytomegalic and immature neurons play an important role in generation and propagation of epileptic discharges. An unexpected finding in pediatric CD was that GABA synaptic activity is not reduced, and in fact, it may facilitate the occurrence of epileptic activity. This could be because neuronal circuits display morphological and functional signs of dysmaturity. In consequence, drugs that increase GABA function may prove ineffective in pediatric CD. In contrast, drugs that counteract depolarizing actions of GABA or drugs that inhibit the mammalian target of rapamycin (mTOR) pathway could be more effective.
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Affiliation(s)
- Sara Abdijadid
- Intellectual and Developmental Disabilities Research Center, Semel Institute for Neuroscience and Human Behavior, University of California Los Angeles, Los Angeles, CA, USA
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Santos MV, de Oliveira RS, Machado HR. Approach to cortical dysplasia associated with glial and glioneuronal tumors (FCD type IIIb). Childs Nerv Syst 2014; 30:1869-74. [PMID: 25296548 DOI: 10.1007/s00381-014-2519-z] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 07/27/2014] [Accepted: 07/28/2014] [Indexed: 11/28/2022]
Abstract
INTRODUCTION Brain tumors are a frequent cause of epilepsy in the pediatric population. The last International League Against Epilepsy (ILAE) classification of focal cortical dysplasias (FCDs) includes a subgroup consisting of tumors with surrounding dysplastic abnormalities (FCD type IIIb). Although its pathogenesis is still unclear, it has several clinical and therapeutic (surgical) implications. BACKGROUND A number of benign tumors (such as dysembryoplastic neuroepithelial tumors and gangliogliomas) frequently present with medically refractory epilepsy associated with cortical dysplasia. In such cases, planning of surgical resection needs to take into consideration not only the tumor but also the whole area of epileptogenicity. The use of intraoperative electrocorticography recordings is reported to result in better postoperative outcomes, since they help delineate the abnormal cerebral cortex that needs to be resected to provide seizure freedom to patients. Clinical, radiological, and pathological features are also discussed herein.
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Affiliation(s)
- Marcelo Volpon Santos
- Division of Pediatric Neurosurgery, Department of Surgery and Anatomy, Ribeirão Preto Medical School, University of São Paulo, Campus Universitário, Ribeirão Preto, São Paulo, 14049-900, Brazil
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Bayesian Network and Mechanistic Hierarchical Structure Modeling of Increased likelihood of Developing Intractable Childhood Epilepsy from the Combined Effect of mtDNA Variants, Oxidative Damage, and Copy Number. J Mol Neurosci 2014; 54:752-66. [DOI: 10.1007/s12031-014-0364-x] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/03/2014] [Accepted: 06/24/2014] [Indexed: 10/25/2022]
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Liu JYW, Ellis M, Brooke-Ball H, de Tisi J, Eriksson SH, Brandner S, Sisodiya SM, Thom M. High-throughput, automated quantification of white matter neurons in mild malformation of cortical development in epilepsy. Acta Neuropathol Commun 2014; 2:72. [PMID: 24927775 PMCID: PMC4229809 DOI: 10.1186/2051-5960-2-72] [Citation(s) in RCA: 23] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/11/2014] [Accepted: 06/09/2014] [Indexed: 12/30/2022] Open
Abstract
INTRODUCTION In epilepsy, the diagnosis of mild Malformation of Cortical Development type II (mMCD II) predominantly relies on the histopathological assessment of heterotopic neurons in the white matter. The exact diagnostic criteria for mMCD II are still ill-defined, mainly because findings from previous studies were contradictory due to small sample size, and the use of different stains and quantitative systems. Advance in technology leading to the development of whole slide imaging with high-throughput, automated quantitative analysis (WSA) may overcome these differences, and may provide objective, rapid, and reliable quantitation of white matter neurons in epilepsy. This study quantified the density of NeuN immunopositive neurons in the white matter of up to 142 epilepsy and control cases using WSA. Quantitative data from WSA was compared to two other systems, semi-automated quantitation, and the widely accepted method of stereology, to assess the reliability and quality of results from WSA. RESULTS All quantitative systems showed a higher density of white matter neurons in epilepsy cases compared to controls (P = 0.002). We found that, in particular, WSA with user-defined region of interest (manual) was superior in terms of larger sampled size, ease of use, time consumption, and accuracy in region selection and cell recognition compared to other methods. Using results from WSA manual, we proposed a threshold value for the classification of mMCD II, where 78% of patients now classified with mMCD II were seizure-free at the second post-operatively follow up. CONCLUSION This study confirms the potential role of WSA in future quantitative diagnostic histology, especially for the histopathological diagnosis of mMCD.
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Utreras E, Hamada R, Prochazkova M, Terse A, Takahashi S, Ohshima T, Kulkarni AB. Suppression of neuroinflammation in forebrain-specific Cdk5 conditional knockout mice by PPARγ agonist improves neuronal loss and early lethality. J Neuroinflammation 2014; 11:28. [PMID: 24495352 PMCID: PMC3931315 DOI: 10.1186/1742-2094-11-28] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/17/2013] [Accepted: 01/21/2014] [Indexed: 01/04/2023] Open
Abstract
Background Cyclin-dependent kinase 5 (Cdk5) is essential for brain development and function, and its deregulated expression is implicated in some of neurodegenerative diseases. We reported earlier that the forebrain-specific Cdk5 conditional knockout (cKO) mice displayed an early lethality associated with neuroinflammation, increased expression of the neuronal tissue-type plasminogen activator (tPA), and neuronal migration defects. Methods In order to suppress neuroinflammation in the cKO mice, we first treated these mice with pioglitazone, a PPARγ agonist, and analyzed its effects on neuronal loss and longevity. In a second approach, to delineate the precise role of tPA in neuroinflammation in these mice, we generated Cdk5 cKO; tPA double knockout (dKO) mice. Results We found that pioglitazone treatment significantly reduced astrogliosis, microgliosis, neuronal loss and behavioral deficit in Cdk5 cKO mice. Interestingly, the dKO mice displayed a partial reversal in astrogliosis, but they still died at early age, suggesting that the increased expression of tPA in the cKO mice does not contribute significantly to the pathological process leading to neuroinflammation, neuronal loss and early lethality. Conclusion The suppression of neuroinflammation in Cdk5 cKO mice ameliorates gliosis and neuronal loss, thus suggesting the potential beneficial effects of the PPARγ agonist pioglitazone for the treatment for neurodegenerative diseases.
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Affiliation(s)
| | | | | | | | | | - Toshio Ohshima
- Functional Genomics Section, Laboratory of Cell and Developmental Biology, National Institute of Dental and Craniofacial Research, National Institutes of Health, Bethesda, MD, USA.
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Fauser S, Häussler U, Donkels C, Huber S, Nakagawa J, Prinz M, Schulze-Bonhage A, Zentner J, Haas CA. Disorganization of neocortical lamination in focal cortical dysplasia is brain-region dependent: evidence from layer-specific marker expression. Acta Neuropathol Commun 2013; 1:47. [PMID: 24252438 PMCID: PMC3893528 DOI: 10.1186/2051-5960-1-47] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/10/2013] [Accepted: 08/05/2013] [Indexed: 01/25/2023] Open
Abstract
Background Focal cortical dysplasias (FCD) are local disturbances of neocortical architecture and a common cause of pharmaco-resistant focal epilepsy. Little is known about the pathomechanisms leading to architectural abnormalities associated with FCD. Results In the present study we compared 52 FCD cases originating from the frontal or temporal lobe with or without Ammon’s horn sclerosis (AHS) with regard to structural and molecular differences. We applied layer-specific (ER81, RORß, SMI32, TLE4) and interneuron (calbindin, parvalbumin) markers by means of immunohistochemistry, in situ hybridization (ISH), and real time RT-PCR and correlated our findings with clinical parameters. We found that: (1) Structural abnormalities were most prominent in layers III-VI including changed morphology of individual neurons or dispersion, blurring and thinning of layers. These alterations were most pronounced in isolated frontal FCD, whereas the most homogeneous group was FCD IIIa. (2) Numbers of calbindin- and parvalbumin-positive interneurons varied considerably within the different FCD groups, but were not generally reduced. A significant decrease was only found for calbindin-positive interneurons in frontal FCD, and for parvalbumin-positive interneurons in FCD IIIa. (3) Interestingly, FCD IIIa presented with significant changes in the numbers of calbindin- or TLE4-positive neurons when compared to isolated FCD or controls. (4) Correlations between clinical and cellular parameters strongly depended on FCD localisation and age of the patients. Conclusions In summary, our data suggest that late cortical development is disturbed in FCD, yet most likely by different causes depending on brain region, FCD type and FCD severity.
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Finardi A, Colciaghi F, Castana L, Locatelli D, Marras CE, Nobili P, Fratelli M, Bramerio MA, Lorusso G, Battaglia GS. Long-duration epilepsy affects cell morphology and glutamatergic synapses in type IIB focal cortical dysplasia. Acta Neuropathol 2013; 126:219-35. [PMID: 23793416 DOI: 10.1007/s00401-013-1143-4] [Citation(s) in RCA: 22] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/18/2013] [Revised: 05/30/2013] [Accepted: 06/11/2013] [Indexed: 11/24/2022]
Abstract
To investigate hypothesized effects of severe epilepsy on malformed cortex, we analyzed surgical samples from eight patients with type IIB focal cortical dysplasia (FCD) in comparison with samples from nine non-dysplastic controls. We investigated, using stereological quantification methods, where appropriate, dysplastic neurons, neuronal density, balloon cells, glia, glutamatergic synaptic input, and the expression of N-methyl-D-aspartate (NMDA) receptor subunits and associated membrane-associated guanylate kinase (MAGUK). In all FCD patients, the dysplastic areas giving rise to epileptic discharges were characterized by larger dysmorphic neurons, reduced neuronal density, and increased glutamatergic inputs, compared to adjacent areas with normal cytology. The duration of epilepsy was found to correlate directly (a) with dysmorphic neuron size, (b) reduced neuronal cell density, and (c) extent of reactive gliosis in epileptogenic/dysplastic areas. Consistent with increased glutamatergic input, western blot revealed that NMDA regulatory subunits and related MAGUK proteins were up-regulated in epileptogenic/dysplastic areas of all FCD patients examined. Taken together, these results support the hypothesis that epilepsy itself alters morphology-and probably also function-in the malformed epileptic brain. They also suggest that glutamate/NMDA/MAGUK dysregulation might be the intracellular trigger that modifies brain morphology and induces cell death.
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Affiliation(s)
- Adele Finardi
- Experimental Neurophysiology and Epileptology Department, Molecular Neuroanatomy and Pathogenesis Unit, Neurological Institute C. Besta, Via Temolo 4, 20126, Milan, Italy
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Shepherd C, Liu J, Goc J, Martinian L, Jacques TS, Sisodiya SM, Thom M. A quantitative study of white matter hypomyelination and oligodendroglial maturation in focal cortical dysplasia type II. Epilepsia 2013; 54:898-908. [PMID: 23551043 PMCID: PMC4165267 DOI: 10.1111/epi.12143] [Citation(s) in RCA: 44] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 02/05/2013] [Indexed: 12/21/2022]
Abstract
PURPOSE A diagnostic feature of focal cortical dysplasia (FCD) type II on magnetic resonance imaging (MRI) is increased subcortical white matter (WM) signal on T2 sequences corresponding to hypomyelination, the cause of which is unknown. We aimed to quantify WM pathology in FCD type II and any deficiency in the numbers and differentiation of oligodendroglial (OL) cell types within the dysplasia. METHODS In 19 cases we defined four regions of interests (ROIs): ROI1 = abnormal WM beneath dysplasia, ROI2 =dysplastic cortex, ROI3 = normal WM, and ROI4 = normal cortex. We quantified axonal and myelin density using immunohistochemistry for neurofilament, myelin basic protein and quantified mature OL with NogoA, cyclic nucleotide 3-phosphodiesterase (CNPase) and OL precursor cell (OPC) densities with platelet derived growth factor receptor (PDGFR)α, β and NG-2 in each region. KEY FINDINGS We observed a significant reduction in myelin and axons in the WM beneath dysplasia relative to normal WM and there was a correlation between relative reduction of myelin and neurofilament in each case. OL and OPC were present in the WM beneath dysplasia and although present in lower numbers with most markers, were not significantly different from normal WM. Neurofilament and myelin labeling highlighted disorganized orientation of fibers in dysplastic cortex but there were no significant quantitative differences compared to normal cortex. Clinical correlations showed an association between the severity of reduction of myelin and axons in the WM of FCD and duration of epilepsy. SIGNIFICANCE These findings indicate a reduction of myelinated axons in the WM of FCD type II rather than dysmyelination as the primary pathologic process underlying WM abnormalities, possibly influenced by duration of seizures. The range of OPC to OL present in FCD type II does not implicate a primary failure of cell recruitment and differentiation of these cell types in this pathology.
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Affiliation(s)
- Caterina Shepherd
- Department of Clinical and Experimental Epilepsy, UCL, Institute of Neurology and National Hospital for Neurology and Neurosurgery, London, United Kingdom
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Development and dysgenesis of the cerebral cortex: malformations of cortical development. Neuroimaging Clin N Am 2012; 21:483-543, vii. [PMID: 21807310 DOI: 10.1016/j.nic.2011.05.014] [Citation(s) in RCA: 43] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
Abstract
The cerebral cortex develops in several stages from a pseudostratified epithelium at 5 weeks to an essentially complete cortex at 47 weeks. Cortical connectivity starts with thalamocortical connections in the 3rd trimester only and continues until well after birth. Vascularity adapts to proliferation and connectivity. Malformations of cortical development are classified into disorders of specification, proliferation/apoptosis, migration, and organization. However, all processes are intermingled, as for example a dysplastic cell may migrate incompletely and not connect appropriately. However, this classification is convenient for didactic purposes as long as the complex interactions between the different processes are kept in mind.
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Mühlebner A, Coras R, Kobow K, Feucht M, Czech T, Stefan H, Weigel D, Buchfelder M, Holthausen H, Pieper T, Kudernatsch M, Blümcke I. Neuropathologic measurements in focal cortical dysplasias: validation of the ILAE 2011 classification system and diagnostic implications for MRI. Acta Neuropathol 2012; 123:259-72. [PMID: 22120580 DOI: 10.1007/s00401-011-0920-1] [Citation(s) in RCA: 91] [Impact Index Per Article: 7.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/24/2011] [Revised: 10/19/2011] [Accepted: 10/26/2011] [Indexed: 01/05/2023]
Abstract
Focal cortical dysplasias (FCD) which represent a composite group of cortical malformations are increasingly recognized as morphological substrate for severe therapy-refractory epilepsy in children and young adults. However, presurgical evaluation remains challenging as not all FCD variants can be reliably detected by high-resolution magnetic resonance imaging (MRI). Here, we studied a cohort of 52 epilepsy patients with neuropathological evidence for FCD using the 2011 classification of the International League against Epilepsy (ILAE) and systematically analysed those histopathologic features applicable also for MRI diagnostics. Histopathologic parameters included quantitative measurements of cellular profiles, cortical thickness, heterotopic neurons in white matter, and myelination that were compared between FCD subtypes and age-/localization-matched controls (n = 36) using multivariate analysis. Dysmorphic neurons in both FCD Type II variants showed significantly increased diameter of their cell bodies and nuclei. Cortical thickness was also increased with a distinct loss of myelin content specifying FCD Type IIb from IIa. The data further suggested that myelination deficits in FCD Type IIb result from compromised oligodendroglial lineage differentiation and we concluded that the "transmantle sign" is a unique finding in FCD Type IIb. In contrast, FCD Type Ia was characterized by a smaller cortical ribbon and higher neuronal densities, but these parameters failed to reach statistical significance (considering age- and location-dependent variability in controls). All FCD variants showed abnormal grey-white matter boundaries with increased numbers of heterotopic neurons. Similar results were obtained also at deep white matter location. Thus, many FCD variants may indeed escape visual MRI inspection, but suspicious areas with increased or decreased cortical thickness as well as grey-white matter blurring may be uncovered using post-processing protocols of neuroimaging data. The systematic analysis of well-specified histopathological features could be helpful to improve sensitivity and specificity in MRI detection during pre-surgical work-up of patients with drug-resistant focal epilepsies.
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Abstract
Focal cortical dysplasias (FCD) are increasingly diagnosed as a cause of symptomatic focal epilepsy in paediatric and adult patients. Nowadays, focal cortical dysplasias are identified as the underlying pathology in up to 25% of patients with focal epilepsies. The histological appearance can vary from mild architectural disturbances to severe malformation containing atypical cellular elements like dysmorphic neurons and Balloon cells. Clinical presentation depends on the age at onset of epilepsy, the location and size of the lesion. In most patients seizures begin in early childhood and the course of epilepsy is often severe and pharmaco-resistant. For the majority of patients, epilepsy surgery is the only treatment option in order to become seizure free.In this review an overview on the literature of the last ten years is provided, focussing on histological appearance and classification, pathogenetic mechanisms and clinical presentation of cortical dysplasias. Recent developments in the presurgical diagnostic and outcome after operative treatment as well as prognostic factors are summarized. Finally, an outlook is given on the development of future novel treatment options that might be minimally invasive and help especially the patient group who is inoperable or has failed epilepsy surgery.
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Affiliation(s)
- S Fauser
- Department of Neurosurgery, University of Freiburg, Freiburg, Germany
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Individual differences in verbal abilities associated with regional blurring of the left gray and white matter boundary. J Neurosci 2011; 31:15257-63. [PMID: 22031871 DOI: 10.1523/jneurosci.3039-11.2011] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/30/2022] Open
Abstract
Blurring of the cortical gray and white matter border on MRI is associated with normal aging, pathological aging, and the presence of focal cortical dysplasia. However, it remains unclear whether normal variations in signal intensity contrast at the gray and white matter junction reflect the functional integrity of subjacent tissue. This study explores the relationship between verbal abilities and gray and white matter contrast (GWC) in healthy human adults. Participants were scanned at 3 T MRI and administered standardized measures of verbal expression and verbal working memory. GWC was estimated by calculating the non-normalized T1 image intensity contrast above and below the cortical gray/white matter interface. Spherical averaging and whole-brain correlational analyses were performed. Sulcal regions exhibited higher contrast compared to gyral regions. We found a strongly lateralized and regionally specific profile with reduced verbal expression abilities associated with blurring in left hemisphere inferior frontal cortex and temporal pole. Reduced verbal working memory was associated with blurring in widespread left frontal and temporal cortices. Such lateralized and focal results provide support for GWC as a measure of regional functional integrity and highlight its potential role in probing the neuroanatomical substrates of cognition in healthy and diseased populations.
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Colciaghi F, Finardi A, Frasca A, Balosso S, Nobili P, Carriero G, Locatelli D, Vezzani A, Battaglia G. Status epilepticus-induced pathologic plasticity in a rat model of focal cortical dysplasia. ACTA ACUST UNITED AC 2011; 134:2828-43. [PMID: 21482549 DOI: 10.1093/brain/awr045] [Citation(s) in RCA: 39] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022]
Abstract
We have generated an experimental 'double-hit' model of chronic epilepsy to recapitulate the co-existence of abnormal cortical structure and frequently recurrent seizures as observed in human focal cortical dysplasia. We induced cortical malformations by exposing rats prenatally to methylazoxymethanol acetate and triggered status epilepticus and recurrent seizures in adult methylazoxymethanol acetate rats with pilocarpine. We studied the course of epilepsy and the long-term morphologic and molecular changes induced by the occurrence of status epilepticus and subsequent chronic epilepsy in the malformed methylazoxymethanol acetate exposed brain. Behavioural and electroencephalographic analyses showed that methylazoxymethanol acetate pilocarpine rats develop more severe epilepsy than naïve rats. Morphologic and molecular analyses demonstrated that status epilepticus and subsequent seizures, but not pilocarpine treatment per se, was capable of affecting both cortical architectural and N-methyl-D-aspartate receptor abnormalities induced by methylazoxymethanol acetate. In particular, cortical thickness was further decreased and N-methyl-D-aspartate regulatory subunits were recruited at the postsynaptic membrane. In addition, methylazoxymethanol acetate pilocarpine rats showed abnormally large cortical pyramidal neurons with neurofilament over-expression. These neurons bear similarities to the hypertrophic/dysmorphic pyramidal neurons observed in acquired human focal cortical dysplasia. These data show that status epilepticus sets in motion a pathological process capable of significantly changing the cellular and molecular features of pre-existing experimental cortical malformations. They suggest that seizure recurrence in human focal cortical dysplasia might be an additional factor in establishing a pathological circuitry that favours chronic neuronal hyperexcitability.
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Affiliation(s)
- Francesca Colciaghi
- Molecular Neuroanatomy and Pathogenesis Unit, Neurological Institute C. Besta, via Temolo 4, 20126 Milano, Italy
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Moroni R, Cipelletti B, Inverardi F, Regondi M, Spreafico R, Frassoni C. Development of cortical malformations in BCNU-treated rat, model of cortical dysplasia. Neuroscience 2011; 175:380-93. [DOI: 10.1016/j.neuroscience.2010.11.061] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/24/2010] [Revised: 11/25/2010] [Accepted: 11/30/2010] [Indexed: 01/30/2023]
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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. [PMID: 21219302 DOI: 10.1111/j.1528] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/01/2023]
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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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: 1156] [Impact Index Per Article: 82.6] [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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Sisodiya SM, Fauser S, Cross JH, Thom M. Focal cortical dysplasia type II: biological features and clinical perspectives. Lancet Neurol 2009; 8:830-43. [DOI: 10.1016/s1474-4422(09)70201-7] [Citation(s) in RCA: 103] [Impact Index Per Article: 6.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/23/2022]
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31
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André VM, Cepeda C, Vinters HV, Huynh M, Mathern GW, Levine MS. Pyramidal cell responses to gamma-aminobutyric acid differ in type I and type II cortical dysplasia. J Neurosci Res 2009; 86:3151-62. [PMID: 18615638 DOI: 10.1002/jnr.21752] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/07/2022]
Abstract
Abnormalities in the gamma-aminobutyric acid (GABA)-ergic system could be responsible for seizures in cortical dysplasia (CD). We examined responses of pyramidal neurons to exogenous application of GABA, as well as alterations of GABAergic interneuron number and size in pediatric epilepsy surgery patients with non-CD, type I CD, and type II CD pathologies. We used the dissociated cell preparation for electrophysiology along with immunohistochemistry to identify number and size of GABAergic cells. Pyramidal neurons from type I CD tissue showed increased EC(50) and faster kinetics compared with cells from non-CD and type II CD tissue. Cytomegalic pyramidal neurons showed increased GABA peak currents and decreased peak current densities, longer kinetics, and decreased sensitivity to zolpidem and zinc compared with normal pyramidal cells from non-CD and type I CD. There were fewer but larger glutamic acid decarboxylase (GAD)-containing cells in type II CD tissue with cytomegalic neurons compared with non-CD, type I CD, and type II CD without cytomegalic neurons. In addition, GABA transporters (VGAT and GAT-1) showed increased staining surrounding cytomegalic neurons in type II CD tissue. These results indicate that there are differences in GABA(A) receptor-mediated pyramidal cell responses in type I and type II CD. Alterations in zolpidem and zinc sensitivities also suggest that cytomegalic neurons have altered GABA(A) receptor subunit composition. These findings support the hypothesis that patients with type I and type II CD will respond differently to GABA-mediated antiepileptic drugs and that cytomegalic neurons have features similar to immature neurons with prolonged GABA(A) receptor open channel times.
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Affiliation(s)
- Véronique M André
- Mental Retardation Research Center, David Geffen School of Medicine, University of California at Los Angeles, Los Angeles, CA 90095, USA.
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Lerner JT, Salamon N, Hauptman JS, Velasco TR, Hemb M, Wu JY, Sankar R, Donald Shields W, Engel J, Fried I, Cepeda C, Andre VM, Levine MS, Miyata H, Yong WH, Vinters HV, Mathern GW. Assessment and surgical outcomes for mild type I and severe type II cortical dysplasia: a critical review and the UCLA experience. Epilepsia 2009; 50:1310-35. [PMID: 19175385 DOI: 10.1111/j.1528-1167.2008.01998.x] [Citation(s) in RCA: 269] [Impact Index Per Article: 17.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/21/2023]
Abstract
Recent findings on the clinical, electroencephalography (EEG), neuroimaging, and surgical outcomes are reviewed comparing patients with Palmini type I (mild) and type II (severe) cortical dysplasia. Resources include peer-reviewed studies on surgically treated patients and a subanalysis of the 2004 International League Against Epilepsy (ILAE) Survey of Pediatric Epilepsy Surgery. These sources were supplemented with data from University of California, Los Angeles (UCLA). Cortical dysplasia is the most frequent histopathologic substrate in children, and the second most common etiology in adult epilepsy surgery patients. Cortical dysplasia patients present with seizures at an earlier age than other surgically treated etiologies, and 33-50% have nonlocalized scalp EEG and normal magnetic resonance imaging (MRI) scans. 2-((18)F)Fluoro-2-deoxy-D-glucose positron emission tomography (FDG-PET) is positive in 75-90% of cases. After complete resection, 80% of patients are seizure free compared with 20% with incomplete resections. Compared with type I, patients with type II cortical dysplasia present at younger ages, have higher seizure frequencies, and are extratemporal. Type I dysplasia is found more often in adult patients in the temporal lobe and is often MRI negative. These findings identify characteristics of patients with mild and severe cortical dysplasia that define surgically treated epilepsy syndromes. The authors discuss future challenges to identifying and treating medically refractory epilepsy patients with cortical dysplasia.
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Affiliation(s)
- Jason T Lerner
- Department of Pediatric Neurology, University of California, Los Angeles, California, USA
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Patz S, Colovic C, Wawro S, Lafenetre P, Leske O, Heumann R, Schönfelder S, Tomaschewski J, Räk A, Wahle P. Interneuronal growth and expression of interneuronal markers in visual cortex of mice with transgenic activation of Ras. Exp Brain Res 2009; 199:265-78. [DOI: 10.1007/s00221-008-1688-y] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/13/2008] [Accepted: 12/09/2008] [Indexed: 11/28/2022]
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Dcx reexpression reduces subcortical band heterotopia and seizure threshold in an animal model of neuronal migration disorder. Nat Med 2008; 15:84-90. [PMID: 19098909 PMCID: PMC2715867 DOI: 10.1038/nm.1897] [Citation(s) in RCA: 123] [Impact Index Per Article: 7.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/15/2008] [Accepted: 11/06/2008] [Indexed: 01/10/2023]
Abstract
Disorders of neuronal migration can lead to malformations of the cerebral neocortex that greatly increase the risk of seizures. It remains untested whether malformations caused by disorders in neuronal migration can be reduced by reactivating cellular migration, and whether such repair can decrease seizure risk. Here we show, in a rat model of subcortical band heterotopia (SBH) generated by in utero RNAi of Dcx, that aberrantly positioned neurons can be stimulated to migrate by re-expressing Dcx after birth. Re-starting migration in this way both reduces neocortical malformations and restores neuronal patterning. We find further that the capacity to reduce SBH has a critical period in early postnatal development. Moreover, intervention after birth reduces convulsant-induced seizure threshold to levels similar to that of malformation-free controls. These results suggest that disorders of neuronal migration may be eventually treatable by re-engaging developmental programs both to reduce the size of cortical malformations and to reduce seizure risk.
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Comparative analysis of the EEG in babies in the first month of life with gestation periods of 30–42 weeks. ACTA ACUST UNITED AC 2008; 38:621-6. [DOI: 10.1007/s11055-008-9018-1] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/16/2006] [Revised: 03/03/2007] [Indexed: 10/21/2022]
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KADAM SHILPAD, DUDEK FEDWARD. Neuropathogical features of a rat model for perinatal hypoxic-ischemic encephalopathy with associated epilepsy. J Comp Neurol 2007; 505:716-37. [PMID: 17948865 PMCID: PMC4607042 DOI: 10.1002/cne.21533] [Citation(s) in RCA: 43] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/15/2022]
Abstract
Hypoxic-ischemic (HI) encephalopathy is an important neurological problem of the perinatal period. Little is known of the long-term progression of HI insults or the maladaptive changes that lead to epilepsy. Using rats with unilateral carotid occlusion followed by hypoxia at postnatal day 7, this study provides an initial analysis of the epilepsy caused by a perinatal HI insult with chronic and continuous behavioral monitoring. The histopathology was investigated at postnatal day 30 and later at > or =6 months of age using cresyl violet, Timm, and rapid Golgi staining and immunocytochemistry. The resultant epilepsy showed an increase in seizure frequency over time, with a preponderance for seizure clusters and behavioral features of an ipsilateral cerebral syndrome. In addition to parasagittal infarcts and porencephalic cysts in severe lesions, columnar neuronal death was found with cytomegaly in isolated groups of dysmorphic cortical neurons. Cortical dysgenesis was seen in the form of deep laminar cell loss, microgyri, white matter hypercellularity, and blurring of the white and gray matter junction. Mossy fiber sprouting was not only detected in the atrophied ipsilateral dorsal hippocampus of HI rats with chronic epilepsy, but was also found in comparable grades in spared ipsi- and contralateral ventral hippocampi. The cortical lesions in this animal model show histological similarities with those found in humans after perinatal HI. The occurrence of cortical abnormalities that are associated with epilepsy in humans correlates with the consequent detection of spontaneous recurrent seizures.
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Affiliation(s)
- SHILPA D. KADAM
- Department of Biomedical Sciences, Neurosciences Division, Colorado State University, Fort Collins, Colorado 80523, and Department of Physiology, University of Utah School of Medicine, Salt Lake City, Utah 84108
| | - F. EDWARD DUDEK
- Department of Biomedical Sciences, Neurosciences Division, Colorado State University, Fort Collins, Colorado 80523, and Department of Physiology, University of Utah School of Medicine, Salt Lake City, Utah 84108
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An investigation of the expression of G1-phase cell cycle proteins in focal cortical dysplasia type IIB. J Neuropathol Exp Neurol 2007; 66:1045-55. [PMID: 17984686 DOI: 10.1097/nen.0b013e3181598d23] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/25/2022] Open
Abstract
Balloon cells (BCs) are the pathologic hallmark of focal cortical dysplasia type IIB, a common cause of pharmacoresistent epilepsy. Expression of markers of cell immaturity and of the proliferation marker minichromosome maintenance protein 2 (mcm2) have been previously shown in BCs, suggesting that these cells might represent a pool of less-differentiated cells licensed for replication. An alternative explanation is that these cells are the remnants of early cortical plate cells that have failed to differentiate or to be eliminated during development and are arrested in the cell cycle, a hypothesis that this study aims to explore. Using immunohistochemical methods and semiquantitative analysis in 19 cases of focal cortical dysplasia (ages 1-81 years), we studied the expression of cell cycle proteins important either in regulating progression through the G1 phase or inducing cell arrest and promoting premature senescence. Only a small fraction of BCs expressed geminin, suggesting that few BCs enter the S phase or complete the cell cycle. Variable expression of nonphosphorylated retinoblastoma protein (Rb), cdk4, and p53 was noted in BCs. Cyclin E, D1, cdk2, phosphorylated Rb (795 and 807/811), and checkpoint 2 expression levels were low in BCs. These findings suggest early rather than late G1 arrest. Cell senescence could be induced by an undefined cerebral insult during development or alternatively represent a physiologic replicative senescence. These findings also suggest that dysregulation of cell cycle pathways may occur in focal cortical dysplasia, which opens further areas for exploration as potential new treatment avenues.
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Cepeda C, André VM, Wu N, Yamazaki I, Uzgil B, Vinters HV, Levine MS, Mathern GW. Immature neurons and GABA networks may contribute to epileptogenesis in pediatric cortical dysplasia. Epilepsia 2007; 48 Suppl 5:79-85. [PMID: 17910585 DOI: 10.1111/j.1528-1167.2007.01293.x] [Citation(s) in RCA: 62] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
Cortical dysplasia (CD), a frequent pathological substrate of pediatric epilepsy surgery patients, has a number of similarities with immature cortex, such as reduced Mg2+ sensitivity of N-methyl-D-aspartate (NMDA) receptors and the persistence of subplate-like neurons and undifferentiated cells. Because gamma-aminobutyric acid (GABA) is the main neurotransmitter in early cortical development, we hypothesized increased GABA receptor-mediated synaptic function in CD tissue. Infrared videomicroscopy and whole-cell patch clamp recordings were used to characterize the morphology and electrophysiological properties of immature and normal-appearing neurons in slices from cortical tissue samples resected for the treatment of pharmacoresistant epilepsy in children (0.2-14 years). In addition, we examined spontaneous and evoked synaptic activity, as well as responses to exogenous GABA application. We demonstrate both the presence of immature pyramidal neurons and networks in young CD tissue and the predominance of GABA synaptic activity. In addition, spontaneous GABA depolarizations frequently induced action potentials, supporting a potential excitatory role of GABA in CD. Evoked synaptic responses mediated by GABA were also prominent, and bath application of 4-aminopyridine induced rhythmic depolarizations that were blocked by bicuculline. Finally, responses to exogenous application of GABA had depolarized reversal potentials in severe compared to mild and non-CD cases. The present data support the hypothesis that CD shares features of immature cortex, with predominant and potentially excitatory GABA(A) receptor-mediated neurotransmission. These results could partially explain the increased excitability of the cortical network in pediatric CD.
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Affiliation(s)
- Carlos Cepeda
- Mental Retardation Research Center, David Geffen School of Medicine, University of California, Los Angeles, California 90024, USA.
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39
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Mathern GW, Andres M, Salamon N, Chandra PS, Andre VM, Cepeda C, Levine MS, Leite JP, Neder L, Vinters HV. A hypothesis regarding the pathogenesis and epileptogenesis of pediatric cortical dysplasia and hemimegalencephaly based on MRI cerebral volumes and NeuN cortical cell densities. Epilepsia 2007; 48 Suppl 5:74-8. [PMID: 17910584 DOI: 10.1111/j.1528-1167.2007.01292.x] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/22/2022]
Abstract
This study compared MRI cerebral volumes and Neuronal-Nuclei (NeuN) cell densities in pediatric epilepsy surgery patients with cortical dysplasia (CD; n = 25) and hemimegalencephaly (HME; n = 14). Our purpose was to deduce possible mechanisms of pathogenesis and epileptogenesis based on an understanding of normal developmental corticoneurogenesis. We used MRI to measured cerebral hemisphere volumes, and NeuN staining to determine grey and white matter cell densities and cell sizes in the molecular layer, grey, and white matter. CD and HME surgical cases were compared with autopsy or non-CD cases (n = 20). Total MRI brain volumes were similar between non-CD, CD, and HME cases. However, in HME patients, the affected cerebral hemisphere was larger and the nonaffected side smaller than non-CD cases. Compared with autopsy cases, NeuN cell densities and cell sizes in CD and HME patients were increased in the molecular layer, upper grey matter, and white matter. In CD and HME cases, total cerebral hemisphere volumes were normal in size and there were more cortical neurons in upper layers than expected. The increase in cortical neuronal densities is consistent with the hypothesis that CD and HME pathogenesis involves increased neurogenesis in the late (not early) phases of cortical formation. In addition, more neurons in the molecular layer and white matter supports the concept that CD and HME pathogenesis also involves incomplete programmed cell death in the remnant cells occupying the preplate and subplate regions. Based on our anatomical and previous electrophysiological findings, we propose that in CD and HME seizure generation is the consequence of incomplete cerebral development with abnormal interactions between immature and mature cells and cellular networks.
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Affiliation(s)
- Gary W Mathern
- Division of Neurosurgery, David Geffen School of Medicine, University of California, Los Angeles, California, USA. 90095-1769
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Boer K, Troost D, Spliet WGM, Redeker S, Crino PB, Aronica E. A neuropathological study of two autopsy cases of syndromic hemimegalencephaly. Neuropathol Appl Neurobiol 2007; 33:455-70. [PMID: 17617874 DOI: 10.1111/j.1365-2990.2006.00818.x] [Citation(s) in RCA: 32] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/17/2023]
Abstract
Hemimegalencephaly (HMEG) is a malformation of cortical development characterized by unilateral enlargement of the cerebral hemisphere, severe architectural and cellular abnormalities and association with intractable epilepsy. HMEG may represent an isolated lesion of the central nervous system, but may also be associated with several neurocutaneous syndromes. In the present study we discuss the neuropathological findings of two autopsy cases of HMEG associated with linear naevus sebaceous syndrome. Both cases showed the presence of linear naevus sebaceous on extensive areas of the face. The neurochemical profile of the glial and neuronal components in the affected hemisphere was determined using immunocytochemical markers and was compared with the unaffected contralateral hemisphere and normal control tissue. The observed cytomegalic neurones expressed receptors for distinct neurotransmitters, neuropeptides and growth factors. Analysis of components of the phosphoinositide 3-kinase pathway revealed expression of phospho-S6 ribosomal protein in cytomegalic neurones. Autopsy findings confirm the complexity of the histologic phenotypic manifestations in HMEG and proved useful in determining the spectrum of cytoarchitectural and neurochemical abnormalities, underlying the molecular pathogenesis and epileptogenesis of this brain malformation.
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Affiliation(s)
- K Boer
- Department of (Neuro) Pathology, Academic Medical Center, University of Amsterdam, Amsterdam, The Netherlands
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41
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André VM, Wu N, Yamazaki I, Nguyen ST, Fisher RS, Vinters HV, Mathern GW, Levine MS, Cepeda C. Cytomegalic interneurons: a new abnormal cell type in severe pediatric cortical dysplasia. J Neuropathol Exp Neurol 2007; 66:491-504. [PMID: 17549009 DOI: 10.1097/01.jnen.0000240473.50661.d8] [Citation(s) in RCA: 66] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/26/2022] Open
Abstract
A defining histopathologic feature of Taylor-type cortical dysplasia (CD) is the presence of cytomegalic neurons and balloon cells. Most cytomegalic neurons appear to be pyramidal-shaped and glutamatergic. The present study demonstrates the presence of cytomegalic GABAergic interneurons in a subset of pediatric patients with severe CD. Cortical tissue samples from children with mild, severe, and non-CD pathologies were examined using morphologic and electrophysiologic techniques. By using in vitro slices, cytomegalic cells with characteristics consistent with interneurons were found in 6 of 10 patients with severe CD. Biocytin labeling demonstrated that cytomegalic interneurons had more dendrites than normal-appearing interneurons. Whole-cell patch clamp recordings showed that cytomegalic interneurons had increased membrane capacitance and time constant compared with normal-appearing interneurons. They also displayed signs of cellular hyperexcitability, evidenced by increased firing rates, decreased action potential inactivation, and the occurrence of spontaneous membrane depolarizations. Single-cell reverse transcription-polymerase chain reaction and immunohistochemistry for GABAergic markers provided further evidence that these cells were probably cytomegalic interneurons. The pathophysiologic significance of GABAergic cytomegalic interneurons in severe CD tissue is unknown, but they could inhibit glutamatergic cytomegalic pyramidal neurons, or contribute to the synchronization of neuronal networks and the propagation of ictal activity in a subset of pediatric patients with severe CD.
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Affiliation(s)
- Véronique M André
- Mental Retardation Research Center, David Geffen School of Medicine, University of California Los Angeles, Los Angeles, California, USA
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42
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Najm IM, Tilelli CQ, Oghlakian R. Pathophysiological mechanisms of focal cortical dysplasia: a critical review of human tissue studies and animal models. Epilepsia 2007; 48 Suppl 2:21-32. [PMID: 17571350 DOI: 10.1111/j.1528-1167.2007.01064.x] [Citation(s) in RCA: 59] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/01/2022]
Abstract
Cortical dysplasia (CD, also known as malformations of cortical development) are the pathological substrates in a large percentage of patients with pharmacoresistant epilepsy who may be amenable to surgical treatment. Therefore, research on the mechanisms of dysplastic lesion formation and epileptogenicity is of paramount importance for the prevention, detection, and treatment of CD-induced epilepsy. The purpose of this review is to discuss and critically evaluate the current state and results of human tissue experimentation (focusing on reported results of studies done on neocortical dysplastic tissue resected from patients with pharmacoresistant epilepsy), and to discuss some of the concerns related to research that uses surgically resected epileptic human tissue. The use of better animal models of CD as a tool toward the better understanding of the mechanisms of pathogenesis, epileptogenesis, and epileptogenicity of dysplastic lesions will be reviewed from the perspective of their usefulness in a model of translational research that should ultimately result in better diagnostic and therapeutic techniques of CD.
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Affiliation(s)
- Imad M Najm
- Cleveland Clinic Epilepsy Center Head, Section of Adult Epilepsy and Clinical Neurophysiology, 9500 Euclid Avenue, S51, Cleveland, OH 44195, USA.
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43
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Daley M, Levitt J, Siddarth P, Mormino E, Hojatkashani C, Gurbani S, Shields WD, Sankar R, Toga A, Caplan R. Frontal and temporal volumes in children with epilepsy. Epilepsy Behav 2007; 10:470-6. [PMID: 17382595 DOI: 10.1016/j.yebeh.2007.02.010] [Citation(s) in RCA: 14] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 09/26/2006] [Revised: 01/14/2007] [Accepted: 02/14/2007] [Indexed: 10/23/2022]
Abstract
This study examined if children with cryptogenic epilepsy and complex partial seizures (CPS) have smaller total brain, frontal, and temporal lobe volumes than normal children and how this is related to seizure, cognitive, psychiatric, and demographic variables. Forty-four children with CPS and 38 normal children, aged 5-16 years, underwent brain MRI scans at 1.5 T. Tissue was segmented, and total brain, frontal lobe, frontal parcellation, and temporal lobe volumes were computed. Other than significantly larger temporal lobe white matter volumes in the CPS group, there were no significant differences in brain volumes between the CPS and normal groups. Earlier onset, longer duration of illness, younger chronological age, and presence of a psychiatric diagnosis were significantly related to smaller frontotemporal volumes in subjects with CPS. Although these findings suggest that CPS might affect development of the temporal and frontal regions, we are unable to rule out the possibility that smaller frontotemporal volumes might predispose children to CPS. These findings highlight the need to control for seizure, cognitive, psychiatric, and demographic variables in studies of frontotemporal volumes in pediatric CPS.
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Affiliation(s)
- Melita Daley
- Department of Psychiatry, David Geffen School of Medicine, University of California at Los Angeles, Los Angeles, CA 90095-1759, USA.
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Munakata M, Watanabe M, Otsuki T, Nakama H, Arima K, Itoh M, Nabekura J, Iinuma K, Tsuchiya S. Altered distribution of KCC2 in cortical dysplasia in patients with intractable epilepsy. Epilepsia 2007; 48:837-44. [PMID: 17284302 DOI: 10.1111/j.1528-1167.2006.00954.x] [Citation(s) in RCA: 48] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
PURPOSE To examine the distribution of KCC2, a neuron-specific K(+)-Cl(-) cotransporter, in human cortical dysplasia (CD). METHODS The immunohistochemical expression of KCC2 was investigated in 18 CD specimens obtained during epilepsy surgery. The histopathologic diagnoses were focal CD (FCD) type I (eight cases), FCD type II (six cases), and hemimegalencephaly (HME; four cases). Tissue sections were immunostained for KCC2 and compared with control sections. RESULTS In the mature nondysplastic cortex, all the layers showed diffuse neuropil staining for KCC2. The somata were stained much less, although subcortical ectopic neurons displayed dense staining in the cytosol (intrasomatic staining). In FCD type I, the cortex showed neuropil staining for KCC2 with less-stained somata. Aberrant giant pyramidal neurons were also less stained at the soma, whereas immature neurons showed intrasomatic staining. Increased numbers of ectopic neurons with intrasomatic staining were noted in the subcortical white matter. In FCD type II, dysmorphic neurons displayed dense intrasomatic staining with reduced staining of the neighboring neuropils. Balloon cells did not stain for KCC2. Dysmorphic neurons in HME also showed intrasomatic staining. CONCLUSIONS Neurons in CD tissues expressed KCC2. However, the subcellular distribution of KCC2 was altered, which might have affected the ionic homeostasis of Cl(-) and K(+) involved in epileptic activity within CD tissues.
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Affiliation(s)
- Mitsutoshi Munakata
- Department of Pediatrics, Tohoku University School of Medicine, Sendai, Japan.
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Huang SY, Wolahan SM, Mathern GW, Chute DJ, Akhtari M, Nguyen ST, Huynh MN, Salamon N, Lin YY. Improving MRI differentiation of gray and white matter in epileptogenic lesions based on nonlinear feedback. Magn Reson Med 2007; 56:776-86. [PMID: 16941616 DOI: 10.1002/mrm.20987] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
Abstract
A new method for enhancing MRI contrast between gray matter (GM) and white matter (WM) in epilepsy surgery patients with symptomatic lesions is presented. This method uses the radiation damping feedback interaction in high-field MRI to amplify contrast due to small differences in resonance frequency in GM and WM corresponding to variations in tissue susceptibility. High-resolution radiation damping-enhanced (RD) images of in vitro brain tissue from five patients were acquired at 14 T and compared with corresponding conventional T(1)-, T(2) (*)-, and proton density (PD)-weighted images. The RD images yielded a six times better contrast-to-noise ratio (CNR = 44.8) on average than the best optimized T(1)-weighted (CNR = 7.92), T(2) (*)-weighted (CNR = 4.20), and PD-weighted images (CNR = 2.52). Regional analysis of the signal as a function of evolution time and initial pulse flip angle, and comparison with numerical simulations confirmed that radiation damping was responsible for the observed signal growth. The time evolution of the signal in different tissue regions was also used to identify subtle changes in tissue composition that were not revealed in conventional MR images. RD contrast is compared with conventional MR methods for separating different tissue types, and its value and limitations are discussed.
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Affiliation(s)
- Susie Y Huang
- Department of Chemistry and Biochemistry, University of California-Los Angeles, California 90095-1569, USA
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Cepeda C, André VM, Levine MS, Salamon N, Miyata H, Vinters HV, Mathern GW. Epileptogenesis in pediatric cortical dysplasia: the dysmature cerebral developmental hypothesis. Epilepsy Behav 2006; 9:219-35. [PMID: 16875879 DOI: 10.1016/j.yebeh.2006.05.012] [Citation(s) in RCA: 141] [Impact Index Per Article: 7.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 03/21/2006] [Revised: 05/22/2006] [Accepted: 05/26/2006] [Indexed: 10/24/2022]
Abstract
Cortical dysplasia (CD) is the most frequent pathology found in pediatric epilepsy surgery patients with a nearly 80% incidence in children younger than 3 years of age. Younger cases are more likely to have multilobar and severe forms of CD compared with older patients with focal and mild CD. Using clinico-pathologic techniques, we have initiated studies that unravel the timing of CD pathogenesis that in turn suggest mechanisms of epileptogenesis. Morphological comparisons provided the first clue when we observed that cytomegalic neurons have similarities with human subplate cells, and balloon cells have features analogous to radial glia. This suggested that failure of prenatal cell degeneration before birth could explain the presence of postnatal dysmorphic cells in CD tissue. Neuronal density and MRI volumes indicate that there were more neurons than expected in CD tissue, and they were probably produced in later neurogenesis cell cycles. Together these findings imply that there is partial failure in later phases of cortical development that might explain the distinctive histopathology of CD. If correct, epileptogenesis should be the consequence of incomplete cellular maturation in CD tissue. In vitro electrophysiological findings are consistent with this notion. They show that balloon cells have glial features, cytomegalic neurons and recently discovered cytomegalic interneurons reveal atypical hyperexcitable intrinsic membrane properties, there are more GABA than glutamate spontaneous synaptic inputs onto neurons, and in a subset of cells NMDA and GABA(A) receptor-mediated responses and subunit expression are similar to those of immature neurons. Our studies support the hypothesis that there are retained prenatal cells and neurons with immature cellular and synaptic properties in pediatric CD tissue. We propose that local interactions of dysmature cells with normal postnatal neurons produce seizures. This hypothesis will drive future studies aimed at elucidating mechanisms of epileptogenesis in pediatric CD tissue.
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Affiliation(s)
- Carlos Cepeda
- Division of Neurosurgery, Department of Neurology, The Brain Research Institute and The Mental Retardation Research Center, David Geffen School of Medicine, University of California, Los Angeles, CA 90095, USA
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Abstract
INTRODUCTION Epilepsy surgery rests heavily upon magnetic resonance imaging (MRI). Technical developments have brought significantly improved efficacy of MR imaging in detecting and assessing surgical epileptogenic lesions, while more clinical experience has brought better definition of the pathological groups. DISCUSSION MRI is fairly efficient in identifying developmental, epilepsy-associated tumors such as ganglioglioma (with its variants gangliocytoma and desmoplastic infantile ganglioglioma), the complex, simple and nonspecific forms of dysembryoplastic neuroepithelial tumor, and the rare pleomorphic xanthoastrocytoma. The efficacy of MR imaging is not as good for the diagnosis of focal cortical dysplasia (FCD), as it does not necessarily correlate with histopathological FCD subtypes and does not show the real extent of the dysplasia which may even be missed in a high percentage of cases. Further developments with better, multichannel coils, higher magnetic fields, specific sequences, and different approaches (such as diffusion tensor imaging) for depicting the structural abnormalities may hopefully improve this efficacy. A general review of the MR features of the diverse pathologies concerned with epilepsy surgery in the pediatric context is provided with illustrative images.
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Affiliation(s)
- Charles Raybaud
- Division of Neuroradiology, Hospital for Sick Children, 555 University Avenue, Toronto, Ontario, M5G 1X8, Canada.
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LoTurco JJ, Bai J. The multipolar stage and disruptions in neuronal migration. Trends Neurosci 2006; 29:407-413. [PMID: 16713637 DOI: 10.1016/j.tins.2006.05.006] [Citation(s) in RCA: 196] [Impact Index Per Article: 10.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/12/2006] [Revised: 03/29/2006] [Accepted: 05/09/2006] [Indexed: 11/16/2022]
Abstract
The genetic basis is now known for several disorders of neuronal migration in the developing cerebral cortex. Identification of the cellular processes mediated by the implicated genes is revealing crucial stages of neuronal migration and has the potential to reveal common cellular causes of neuronal migration disorders. We hypothesize that a newly recognized morphological stage of neuronal migration, the multipolar stage, is vulnerable and is disrupted in several disorders of neocortical development. The multipolar stage occurs as bipolar progenitor cells become radially migrating neurons. Several studies using in utero electroporation and RNAi have revealed that transition out of the multipolar stage depends on the function of filamin A, LIS1 and DCX. Mutations in the genes encoding these proteins in humans cause distinct neuronal migration disorders, including periventricular nodular heterotopia, subcortical band heterotopia and lissencephaly. The multipolar stage therefore seems to be a critical point of migration control and a vulnerable target for disruption of neocortical development. This review is part of the INMED/TINS special issue "Nature and nurture in brain development and neurological disorders", based on presentations at the annual INMED/TINS symposium (http://inmednet.com/).
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Affiliation(s)
- Joseph J LoTurco
- Department of Physiology and Neurobiology, 75 North Eagleville Road U-3156, University of Connecticut, Storrs, CT 06269, USA.
| | - Jilin Bai
- Department of Physiology and Neurobiology, 75 North Eagleville Road U-3156, University of Connecticut, Storrs, CT 06269, USA
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Salamon N, Andres M, Chute DJ, Nguyen ST, Chang JW, Huynh MN, Chandra PS, Andre VM, Cepeda C, Levine MS, Leite JP, Neder L, Vinters HV, Mathern GW. Contralateral hemimicrencephaly and clinical-pathological correlations in children with hemimegalencephaly. ACTA ACUST UNITED AC 2005; 129:352-65. [PMID: 16291806 DOI: 10.1093/brain/awh681] [Citation(s) in RCA: 92] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022]
Abstract
In paediatric epilepsy surgery patients with hemimegalencephaly (HME; n = 23), this study compared clinical, neuroimaging and pathologic features to discern potential mechanisms for suboptimal post-hemispherectomy developmental outcomes and structural pathogenesis. MRI measured affected and non-affected cerebral hemisphere volumes for HME and non-HME cases, including monozygotic twins where one sibling had HME. Staining against neuronal nuclei (NeuN) determined grey and white matter cell densities and sizes in HME and autopsy cases, including the non-affected side of a HME surgical/autopsy case. By MRI, the affected hemisphere was larger and the non-affected side smaller in HME compared with non-HME children. The affected HME side showed enlarged abnormal deep grey and white matter structures and/or T2-weighted hypointensity in the subcortical white matter in 75% of cases, suggestive of excessive pre-natal neurogenesis and heterotopias. Histopathological examination of the affected HME side revealed immature-appearing neurons in 70%, polymicrogyria (PMG) in 61% and balloon cells in 45% of cases. Compared with autopsy cases, in HME children NeuN cell densities on the affected side were increased in the molecular layer and upper cortex (+244 to +18%), decreased in lower cortical layers (-35%) and increased in the white matter (+139 to +149%). Deep grey matter MRI abnormalities and/or T2-weighted white matter hypointensity correlated with the presence of immature-appearing neurons and PMG on histopathology, decreased NeuN cell densities in lower cortical layers and a positive history of infantile spasms. Post-surgery seizure control was associated with decreased NeuN densities in the molecular layer. In young children with HME and epilepsy, these findings indicate that there are bilateral cerebral hemispheric abnormalities and contralateral hemimicrencephaly is a likely explanation for poorer post-surgery seizure control and cognitive outcomes. In addition, our findings support the hypothesis that HME pathogenesis probably involves somatic mutations that affect each developing cerebral hemisphere differently with more neurons than expected on the HME side.
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Affiliation(s)
- Noriko Salamon
- Division of Neurosurgery, David Geffen School of Medicine, University of California, Los Angeles, CA, USA
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Thom M, Martinian L, Sen A, Cross JH, Harding BN, Sisodiya SM. Cortical neuronal densities and lamination in focal cortical dysplasia. Acta Neuropathol 2005; 110:383-92. [PMID: 16151726 DOI: 10.1007/s00401-005-1062-0] [Citation(s) in RCA: 39] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/28/2005] [Revised: 06/22/2005] [Accepted: 06/22/2005] [Indexed: 10/25/2022]
Abstract
Focal cortical dysplasia (FCD) is considered to represent a malformation due to abnormal cortical development (MCD) and is an important cause of focal epilepsy. The histopathological features include abnormal laminar architecture, the presence of hypertrophic and dysmorphic neurones in FCD type IIA and additional balloon cells in FCD type IIB. The events causing these sporadic lesions are unknown, but abnormal progenitor cell proliferation occurring late in corticogenesis has been proposed. FCD-like lesions have, however, also been described following a cerebral injury early in life. We carried out a stereological assessment on 15 cases of FCD on NeuN- and Nissl-stained sections from patients with a wide age range, and identified a significant reduction in the neuronal density in all cases in the region of dysplasia compared to the adjacent unaffected cortex (mean neuronal densities 19.2x10(3)/mm3 in the region of dysplasia; 42.8x10(3)/mm3 in the adjacent cortex). Relative differences in neuronal density and size in FCD cases between the superficial (layer I and II) and deep cortical laminae (layer V and VI) were similar to that observed in other pathologies including mild MCD, temporal neocortex adjacent to hippocampal sclerosis as well as in a non-epilepsy surgical control group. The lower overall neuronal densities observed in FCD may reflect neuropil expansion, a local failure of neuronal migration, proliferation or secondary neuronal loss. The preservation of relative differences in neuronal densities between cortical layers and laminar patterns of neurofilament staining in FCD would support the view that the temporal sequence of lamination is not affected.
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Affiliation(s)
- M Thom
- Division of Neuropathology and Department of Clinical and Experimental Epilepsy, Institute of Neurology, Queen Square, London, WC1N 3BG, UK
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