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Mito R, Pedersen M, Pardoe H, Parker D, Smith RE, Cameron J, Scheffer IE, Berkovic SF, Vaughan DN, Jackson GD. Exploring individual fixel-based white matter abnormalities in epilepsy. Brain Commun 2023; 6:fcad352. [PMID: 38187877 PMCID: PMC10768884 DOI: 10.1093/braincomms/fcad352] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/11/2023] [Revised: 11/02/2023] [Accepted: 12/21/2023] [Indexed: 01/09/2024] Open
Abstract
Diffusion MRI has provided insight into the widespread structural connectivity changes that characterize epilepsies. Although syndrome-specific white matter abnormalities have been demonstrated, studies to date have predominantly relied on statistical comparisons between patient and control groups. For diffusion MRI techniques to be of clinical value, they should be able to detect white matter microstructural changes in individual patients. In this study, we apply an individualized approach to a technique known as fixel-based analysis, to examine fibre-tract-specific abnormalities in individuals with epilepsy. We explore the potential clinical value of this individualized fixel-based approach in epilepsy patients with differing syndromic diagnoses. Diffusion MRI data from 90 neurologically healthy control participants and 10 patients with epilepsy (temporal lobe epilepsy, progressive myoclonus epilepsy, and Dravet Syndrome, malformations of cortical development) were included in this study. Measures of fibre density and cross-section were extracted for all participants across brain white matter fixels, and mean values were computed within select tracts-of-interest. Scanner harmonized and normalized data were then used to compute Z-scores for individual patients with epilepsy. White matter abnormalities were observed in distinct patterns in individual patients with epilepsy, both at the tract and fixel level. For patients with specific epilepsy syndromes, the detected white matter abnormalities were in line with expected syndrome-specific clinical phenotypes. In patients with lesional epilepsies (e.g. hippocampal sclerosis, periventricular nodular heterotopia, and bottom-of-sulcus dysplasia), white matter abnormalities were spatially concordant with lesion location. This proof-of-principle study demonstrates the clinical potential of translating advanced diffusion MRI methodology to individual-patient-level use in epilepsy. This technique could be useful both in aiding diagnosis of specific epilepsy syndromes, and in localizing structural abnormalities, and is readily amenable to other neurological disorders. We have included code and data for this study so that individualized white matter changes can be explored robustly in larger cohorts in future work.
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Affiliation(s)
- Remika Mito
- Florey Institute of Neuroscience and Mental Health, Heidelberg, Victoria 3084, Australia
- Florey Department of Neuroscience and Mental Health, University of Melbourne, Melbourne, Victoria 3010, Australia
| | - Mangor Pedersen
- Florey Institute of Neuroscience and Mental Health, Heidelberg, Victoria 3084, Australia
- Department of Psychology and Neuroscience, Auckland University of Technology (AUT), Auckland 1142, New Zealand
| | - Heath Pardoe
- Florey Institute of Neuroscience and Mental Health, Heidelberg, Victoria 3084, Australia
| | - Donna Parker
- Florey Institute of Neuroscience and Mental Health, Heidelberg, Victoria 3084, Australia
| | - Robert E Smith
- Florey Institute of Neuroscience and Mental Health, Heidelberg, Victoria 3084, Australia
- Florey Department of Neuroscience and Mental Health, University of Melbourne, Melbourne, Victoria 3010, Australia
| | - Jillian Cameron
- Epilepsy Research Centre, Department of Medicine, University of Melbourne, Austin Health, Heidelberg, Victoria 3084, Australia
| | - Ingrid E Scheffer
- Epilepsy Research Centre, Department of Medicine, University of Melbourne, Austin Health, Heidelberg, Victoria 3084, Australia
| | - Samuel F Berkovic
- Epilepsy Research Centre, Department of Medicine, University of Melbourne, Austin Health, Heidelberg, Victoria 3084, Australia
| | - David N Vaughan
- Florey Institute of Neuroscience and Mental Health, Heidelberg, Victoria 3084, Australia
- Florey Department of Neuroscience and Mental Health, University of Melbourne, Melbourne, Victoria 3010, Australia
- Department of Neurology, Austin Health, Heidelberg, Victoria 3084, Australia
| | - Graeme D Jackson
- Florey Institute of Neuroscience and Mental Health, Heidelberg, Victoria 3084, Australia
- Florey Department of Neuroscience and Mental Health, University of Melbourne, Melbourne, Victoria 3010, Australia
- Department of Neurology, Austin Health, Heidelberg, Victoria 3084, Australia
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2
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De Benedictis A, Rossi-Espagnet MC, de Palma L, Sarubbo S, Marras CE. Structural networking of the developing brain: from maturation to neurosurgical implications. Front Neuroanat 2023; 17:1242757. [PMID: 38099209 PMCID: PMC10719860 DOI: 10.3389/fnana.2023.1242757] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/19/2023] [Accepted: 11/09/2023] [Indexed: 12/17/2023] Open
Abstract
Modern neuroscience agrees that neurological processing emerges from the multimodal interaction among multiple cortical and subcortical neuronal hubs, connected at short and long distance by white matter, to form a largely integrated and dynamic network, called the brain "connectome." The final architecture of these circuits results from a complex, continuous, and highly protracted development process of several axonal pathways that constitute the anatomical substrate of neuronal interactions. Awareness of the network organization of the central nervous system is crucial not only to understand the basis of children's neurological development, but also it may be of special interest to improve the quality of neurosurgical treatments of many pediatric diseases. Although there are a flourishing number of neuroimaging studies of the connectome, a comprehensive vision linking this research to neurosurgical practice is still lacking in the current pediatric literature. The goal of this review is to contribute to bridging this gap. In the first part, we summarize the main current knowledge concerning brain network maturation and its involvement in different aspects of normal neurocognitive development as well as in the pathophysiology of specific diseases. The final section is devoted to identifying possible implications of this knowledge in the neurosurgical field, especially in epilepsy and tumor surgery, and to discuss promising perspectives for future investigations.
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Affiliation(s)
| | | | - Luca de Palma
- Clinical and Experimental Neurology, Bambino Gesù Children’s Hospital, Rome, Italy
| | - Silvio Sarubbo
- Department of Neurosurgery, Santa Chiara Hospital, Azienda Provinciale per i Servizi Sanitari (APSS), Trento, Italy
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Villaseñor PJ, Cortés-Servín D, Pérez-Moriel A, Aquiles A, Luna-Munguía H, Ramirez-Manzanares A, Coronado-Leija R, Larriva-Sahd J, Concha L. Multi-tensor diffusion abnormalities of gray matter in an animal model of cortical dysplasia. Front Neurol 2023; 14:1124282. [PMID: 37342776 PMCID: PMC10278582 DOI: 10.3389/fneur.2023.1124282] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/15/2022] [Accepted: 04/18/2023] [Indexed: 06/23/2023] Open
Abstract
Focal cortical dysplasias are a type of malformations of cortical development that are a common cause of drug-resistant focal epilepsy. Surgical treatment is a viable option for some of these patients, with their outcome being highly related to complete surgical resection of lesions visible in magnetic resonance imaging (MRI). However, subtle lesions often go undetected on conventional imaging. Several methods to analyze MRI have been proposed, with the common goal of rendering subtle cortical lesions visible. However, most image-processing methods are targeted to detect the macroscopic characteristics of cortical dysplasias, which do not always correspond to the microstructural disarrangement of these cortical malformations. Quantitative analysis of diffusion-weighted MRI (dMRI) enables the inference of tissue characteristics, and novel methods provide valuable microstructural features of complex tissue, including gray matter. We investigated the ability of advanced dMRI descriptors to detect diffusion abnormalities in an animal model of cortical dysplasia. For this purpose, we induced cortical dysplasia in 18 animals that were scanned at 30 postnatal days (along with 19 control animals). We obtained multi-shell dMRI, to which we fitted single and multi-tensor representations. Quantitative dMRI parameters derived from these methods were queried using a curvilinear coordinate system to sample the cortical mantle, providing inter-subject anatomical correspondence. We found region- and layer-specific diffusion abnormalities in experimental animals. Moreover, we were able to distinguish diffusion abnormalities related to altered intra-cortical tangential fibers from those associated with radial cortical fibers. Histological examinations revealed myelo-architectural abnormalities that explain the alterations observed through dMRI. The methods for dMRI acquisition and analysis used here are available in clinical settings and our work shows their clinical relevance to detect subtle cortical dysplasias through analysis of their microstructural properties.
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Affiliation(s)
- Paulina J. Villaseñor
- Instituto de Neurobiología, Universidad Nacional Autónoma de México Campus Juriquilla, Querétaro, Mexico
| | - David Cortés-Servín
- Instituto de Neurobiología, Universidad Nacional Autónoma de México Campus Juriquilla, Querétaro, Mexico
| | | | - Ana Aquiles
- Instituto de Neurobiología, Universidad Nacional Autónoma de México Campus Juriquilla, Querétaro, Mexico
| | - Hiram Luna-Munguía
- Instituto de Neurobiología, Universidad Nacional Autónoma de México Campus Juriquilla, Querétaro, Mexico
| | | | - Ricardo Coronado-Leija
- Bernard and Irene Schwartz Center for Biomedical Imaging, Department of Radiology, New York University School of Medicine, New York, NY, United States
| | - Jorge Larriva-Sahd
- Instituto de Neurobiología, Universidad Nacional Autónoma de México Campus Juriquilla, Querétaro, Mexico
| | - Luis Concha
- Instituto de Neurobiología, Universidad Nacional Autónoma de México Campus Juriquilla, Querétaro, Mexico
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Gennari AG, Cserpan D, Stefanos-Yakoub I, Kottke R, O’Gorman Tuura R, Ramantani G. Diffusion tensor imaging discriminates focal cortical dysplasia from normal brain parenchyma and differentiates between focal cortical dysplasia types. Insights Imaging 2023; 14:36. [PMID: 36826756 PMCID: PMC9958211 DOI: 10.1186/s13244-023-01368-y] [Citation(s) in RCA: 4] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/16/2022] [Accepted: 12/29/2022] [Indexed: 02/25/2023] Open
Abstract
OBJECTIVES Although diffusion tensor imaging (DTI) may facilitate the identification of cytoarchitectural changes associated with focal cortical dysplasia (FCD), the predominant aetiology of paediatric structural epilepsy, its potential has thus far remained unexplored in this population. Here, we investigated whether DTI indices can differentiate FCD from contralateral brain parenchyma (CBP) and whether clinical features affect these indices. METHODS In this single-centre, retrospective study, we considered children and adolescents with FCD-associated epilepsy who underwent brain magnetic resonance (MRI), including DTI. Fractional anisotropy (FA), mean diffusivity (MD), axial diffusivity, and radial diffusivity, were calculated in both FCD and CBP. The DTI indices best discriminating between FCD and CBP were subsequently used to assess the link between DTI and selected clinical and lesion-related parameters. RESULTS We enrolled 32 patients (20 male; median age at MRI 4 years), including 15 with histologically confirmed FCD. FA values were lower (p = 0.03), whereas MD values were higher in FCD than in CBP (p = 0.04). The difference in FA values between FCD and CBP was more pronounced for a positive vs. negative history of status epilepticus (p = 0.004). Among histologically confirmed cases, the difference in FA values between FCD and CBP was more pronounced for type IIb versus type I FCD (p = 0.03). CONCLUSIONS FA and MD discriminate between FCD and CBP, while FA differentiates between FCD types. Status epilepticus increases differences in FA, potentially reflecting changes induced in the brain. Our findings support the potential of DTI to serve as a non-invasive biomarker to characterise FCD in the paediatric population.
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Affiliation(s)
- Antonio Giulio Gennari
- Department of Neuropediatrics, University Children's Hospital Zurich, Steinwiesstrasse 75, 8032, Zurich, Switzerland. .,MR-Research Centre, University Children's Hospital Zurich, Zurich, Switzerland.
| | - Dorottya Cserpan
- grid.412341.10000 0001 0726 4330Department of Neuropediatrics, University Children’s Hospital Zurich, Steinwiesstrasse 75, 8032 Zurich, Switzerland
| | - Ilona Stefanos-Yakoub
- grid.412341.10000 0001 0726 4330Department of Neuropediatrics, University Children’s Hospital Zurich, Steinwiesstrasse 75, 8032 Zurich, Switzerland
| | - Raimund Kottke
- grid.412341.10000 0001 0726 4330Department of Diagnostic Imaging, University Children’s Hospital Zurich, Zurich, Switzerland
| | - Ruth O’Gorman Tuura
- grid.412341.10000 0001 0726 4330MR-Research Centre, University Children’s Hospital Zurich, Zurich, Switzerland ,grid.7400.30000 0004 1937 0650University of Zurich, Zurich, Switzerland ,grid.412341.10000 0001 0726 4330Children’s Research Centre, University Children’s Hospital Zurich, Zurich, Switzerland
| | - Georgia Ramantani
- grid.412341.10000 0001 0726 4330Department of Neuropediatrics, University Children’s Hospital Zurich, Steinwiesstrasse 75, 8032 Zurich, Switzerland ,grid.7400.30000 0004 1937 0650University of Zurich, Zurich, Switzerland ,grid.412341.10000 0001 0726 4330Children’s Research Centre, University Children’s Hospital Zurich, Zurich, Switzerland
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Bartoňová M, Tournier JD, Bartoň M, Říha P, Vojtíšek L, Mareček R, Doležalová I, Rektor I. White matter alterations in MR-negative temporal and frontal lobe epilepsy using fixel-based analysis. Sci Rep 2023; 13:19. [PMID: 36593331 PMCID: PMC9807578 DOI: 10.1038/s41598-022-27233-4] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/05/2022] [Accepted: 12/28/2022] [Indexed: 01/03/2023] Open
Abstract
This study focuses on white matter alterations in pharmacoresistant epilepsy patients with no visible lesions in the temporal and frontal lobes on clinical MRI (i.e. MR-negative) with lesions confirmed by resective surgery. The aim of the study was to extend the knowledge about group-specific neuropathology in MR-negative epilepsy. We used the fixel-based analysis (FBA) that overcomes the limitations of traditional diffusion tensor image analysis, mainly within-voxel averaging of multiple crossing fibres. Group-wise comparisons of fixel parameters between healthy controls (N = 100) and: (1) frontal lobe epilepsy (FLE) patients (N = 9); (2) temporal lobe epilepsy (TLE) patients (N = 13) were performed. A significant decrease of the cross-section area of the fixels in the superior longitudinal fasciculus was observed in the FLE. Results in TLE reflected widespread atrophy of limbic, thalamic, and cortico-striatal connections and tracts directly connected to the temporal lobe (such as the anterior commissure, inferior fronto-occipital fasciculus, uncinate fasciculus, splenium of corpus callosum, and cingulum bundle). Alterations were also observed in extratemporal connections (brainstem connection, commissural fibres, and parts of the superior longitudinal fasciculus). To our knowledge, this is the first study to use an advanced FBA method not only on the datasets of MR-negative TLE patients, but also MR-negative FLE patients, uncovering new common tract-specific alterations on the group level.
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Affiliation(s)
- Michaela Bartoňová
- grid.10267.320000 0001 2194 0956Central European Institute of Technology (CEITEC), Multimodal and Functional Neuroimaging Research Group, Masaryk University, Kamenice 753/5, 625 00 Brno, Czech Republic ,grid.10267.320000 0001 2194 0956Brno Epilepsy Center, First Department of Neurology, St. Anne’s University Hospital, Faculty of Medicine, Masaryk University, Brno, Czech Republic
| | - Jacques-Donald Tournier
- grid.13097.3c0000 0001 2322 6764Centre for Medical Engineering, King’s College London, London, UK ,grid.13097.3c0000 0001 2322 6764Centre for the Developing Brain, King’s College London, London, UK
| | - Marek Bartoň
- grid.10267.320000 0001 2194 0956Central European Institute of Technology (CEITEC), Multimodal and Functional Neuroimaging Research Group, Masaryk University, Kamenice 753/5, 625 00 Brno, Czech Republic
| | - Pavel Říha
- grid.10267.320000 0001 2194 0956Central European Institute of Technology (CEITEC), Multimodal and Functional Neuroimaging Research Group, Masaryk University, Kamenice 753/5, 625 00 Brno, Czech Republic ,grid.10267.320000 0001 2194 0956Brno Epilepsy Center, First Department of Neurology, St. Anne’s University Hospital, Faculty of Medicine, Masaryk University, Brno, Czech Republic
| | - Lubomír Vojtíšek
- grid.10267.320000 0001 2194 0956Central European Institute of Technology (CEITEC), Multimodal and Functional Neuroimaging Research Group, Masaryk University, Kamenice 753/5, 625 00 Brno, Czech Republic
| | - Radek Mareček
- grid.10267.320000 0001 2194 0956Central European Institute of Technology (CEITEC), Multimodal and Functional Neuroimaging Research Group, Masaryk University, Kamenice 753/5, 625 00 Brno, Czech Republic
| | - Irena Doležalová
- grid.10267.320000 0001 2194 0956Brno Epilepsy Center, First Department of Neurology, St. Anne’s University Hospital, Faculty of Medicine, Masaryk University, Brno, Czech Republic
| | - Ivan Rektor
- grid.10267.320000 0001 2194 0956Central European Institute of Technology (CEITEC), Multimodal and Functional Neuroimaging Research Group, Masaryk University, Kamenice 753/5, 625 00 Brno, Czech Republic ,grid.10267.320000 0001 2194 0956Brno Epilepsy Center, First Department of Neurology, St. Anne’s University Hospital, Faculty of Medicine, Masaryk University, Brno, Czech Republic
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Urquia-Osorio H, Pimentel-Silva LR, Rezende TJR, Almendares-Bonilla E, Yasuda CL, Concha L, Cendes F. Superficial and deep white matter diffusion abnormalities in focal epilepsies. Epilepsia 2022; 63:2312-2324. [PMID: 35707885 DOI: 10.1111/epi.17333] [Citation(s) in RCA: 4] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/23/2022] [Revised: 05/11/2022] [Accepted: 06/14/2022] [Indexed: 12/01/2022]
Abstract
OBJECTIVE This study was undertaken to evaluate superficial-white matter (WM) and deep-WM magnetic resonance imaging diffusion tensor imaging (DTI) metrics and identify distinctive patterns of microstructural abnormalities in focal epilepsies of diverse etiology, localization, and response to antiseizure medication (ASM). METHODS We examined DTI data for 113 healthy controls and 113 patients with focal epilepsies: 51 patients with temporal lobe epilepsy (TLE) and hippocampal sclerosis (HS) refractory to ASM, 27 with pharmacoresponsive TLE-HS, 15 with temporal lobe focal cortical dysplasia (FCD), and 20 with frontal lobe FCD. To assess WM microstructure, we used a multicontrast multiatlas parcellation of DTI. We evaluated fractional anisotropy (FA), mean diffusivity (MD), radial diffusivity (RD), and axial diffusivity (AD), and assessed within-group differences ipsilateral and contralateral to the epileptogenic lesion, as well as between-group differences, in regions of interest (ROIs). RESULTS The TLE-HS groups presented more widespread superficial- and deep-WM diffusion abnormalities than both FCD groups. Concerning superficial WM, TLE-HS groups showed multilobar ipsilateral and contralateral abnormalities, with less extensive distribution in pharmacoresponsive patients. Both the refractory TLE-HS and pharmacoresponsive TLE-HS groups also presented pronounced changes in ipsilateral frontotemporal ROIs (decreased FA and increased MD, RD, and AD). Conversely, FCD patients showed diffusion changes almost exclusively adjacent to epileptogenic areas. SIGNIFICANCE Our findings add further evidence of widespread abnormalities in WM diffusion metrics in patients with TLE-HS compared to other focal epilepsies. Notably, superficial-WM microstructural damage in patients with FCD is more restricted around the epileptogenic lesion, whereas TLE-HS groups showed diffuse WM damage with ipsilateral frontotemporal predominance. These findings suggest the potential of superficial-WM analysis for better understanding the biological mechanisms of focal epilepsies, and identifying dysfunctional networks and their relationship with the clinical-pathological phenotype. In addition, lobar superficial-WM abnormalities may aid in the diagnosis of subtle FCDs.
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Affiliation(s)
- Hebel Urquia-Osorio
- Department of Neurology, University of Campinas, São Paulo, Brazil.,Faculty of Medical Science, National Autonomous University of Honduras, Honduras
| | | | | | - Eimy Almendares-Bonilla
- Department of Neurology, University of Campinas, São Paulo, Brazil.,Faculty of Medical Science, National Autonomous University of Honduras, Honduras
| | | | - Luis Concha
- Institute of Neurobiology, National Autonomous University of Mexico, Queretaro, Mexico
| | - Fernando Cendes
- Department of Neurology, University of Campinas, São Paulo, Brazil
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Mito R, Vaughan DN, Semmelroch M, Connelly A, Jackson GD. Bilateral Structural Network Abnormalities in Epilepsy Associated With Bottom-of-Sulcus Dysplasia. Neurology 2022; 98:e152-e163. [PMID: 34675097 PMCID: PMC8762587 DOI: 10.1212/wnl.0000000000013006] [Citation(s) in RCA: 6] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/28/2021] [Accepted: 10/15/2021] [Indexed: 12/02/2022] Open
Abstract
BACKGROUND AND OBJECTIVES To identify white matter fiber tracts that exhibit structural abnormality in patients with bottom-of-sulcus dysplasia (BOSD) and investigate their association with seizure activity. METHODS Whole-brain fixel-based analysis of diffusion MRI data was performed to identify white matter fiber tracts with significant reductions in fiber density and cross-section in patients with BOSD (n = 20) when compared to healthy control participants (n = 40). Results from whole-brain analysis were used to investigate the association of fiber tract abnormality with seizure frequency and epilepsy duration. RESULTS Despite the focal nature of the dysplasia, patients with BOSD showed widespread abnormality in white matter fiber tracts, including the bilateral corticospinal, corticothalamic, and cerebellothalamic tracts, superior longitudinal fasciculi, corpus callosum (body), and the forceps major. This pattern of bilateral connectivity reduction was not related to the laterality of the lesion. Exploratory post hoc analyses showed that high seizure frequency was associated with greater reduction in fiber density at the forceps major, bilateral corticospinal, and cerebellothalamic tracts. DISCUSSION We demonstrate evidence of a bilaterally distributed, specific white matter network that is vulnerable to disruption in BOSD. The degree of tract abnormality is partly related to seizure activity, but additional contributors such as the genetic background and effects of treatment or environment have not been excluded.
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Affiliation(s)
- Remika Mito
- From the Florey Institute of Neuroscience and Mental Health (R.M., D.N.V., M.S., A.C., G.D.J.), Heidelberg; Florey Department of Neuroscience and Mental Health (D.N.V., A.C., G.D.J.), University of Melbourne; and Department of Neurology (D.N.V., G.D.J.), Austin Health, Heidelberg, Australia.
| | - David N Vaughan
- From the Florey Institute of Neuroscience and Mental Health (R.M., D.N.V., M.S., A.C., G.D.J.), Heidelberg; Florey Department of Neuroscience and Mental Health (D.N.V., A.C., G.D.J.), University of Melbourne; and Department of Neurology (D.N.V., G.D.J.), Austin Health, Heidelberg, Australia
| | - Mira Semmelroch
- From the Florey Institute of Neuroscience and Mental Health (R.M., D.N.V., M.S., A.C., G.D.J.), Heidelberg; Florey Department of Neuroscience and Mental Health (D.N.V., A.C., G.D.J.), University of Melbourne; and Department of Neurology (D.N.V., G.D.J.), Austin Health, Heidelberg, Australia
| | - Alan Connelly
- From the Florey Institute of Neuroscience and Mental Health (R.M., D.N.V., M.S., A.C., G.D.J.), Heidelberg; Florey Department of Neuroscience and Mental Health (D.N.V., A.C., G.D.J.), University of Melbourne; and Department of Neurology (D.N.V., G.D.J.), Austin Health, Heidelberg, Australia
| | - Graeme D Jackson
- From the Florey Institute of Neuroscience and Mental Health (R.M., D.N.V., M.S., A.C., G.D.J.), Heidelberg; Florey Department of Neuroscience and Mental Health (D.N.V., A.C., G.D.J.), University of Melbourne; and Department of Neurology (D.N.V., G.D.J.), Austin Health, Heidelberg, Australia
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Lotan E, Tomer O, Tavor I, Blatt I, Goldberg-Stern H, Hoffmann C, Tsarfaty G, Tanne D, Assaf Y. Widespread cortical dyslamination in epilepsy patients with malformations of cortical development. Neuroradiology 2020; 63:225-234. [PMID: 32975591 DOI: 10.1007/s00234-020-02561-2] [Citation(s) in RCA: 9] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/11/2020] [Accepted: 09/16/2020] [Indexed: 01/16/2023]
Abstract
PURPOSE Recent research in epilepsy patients confirms our understanding of epilepsy as a network disorder with widespread cortical compromise. Here, we aimed to investigate the neocortical laminar architecture in patients with focal cortical dysplasia (FCD) and periventricular nodular heterotopia (PNH) using clinically feasible 3 T MRI. METHODS Eighteen epilepsy patients (FCD and PNH groups; n = 9 each) and age-matched healthy controls (n = 9) underwent T1 relaxation 3 T MRI, from which component probability T1 maps were utilized to extract sub-voxel composition of 6 T1 cortical layers. Seventy-eight cortical areas of the automated anatomical labeling atlas were divided into 1000 equal-volume sub-areas for better detection of cortical abnormalities, and logistic regressions were performed to compare FCD/PNH patients with healthy controls with the T1 layers composing each sub-area as regressors. Statistical significance (p < 0.05) was determined by a likelihood-ratio test with correction for false discovery rate using Benjamini-Hochberg method. RESULTS Widespread cortical abnormalities were observed in the patient groups. Out of 1000 sub-areas, 291 and 256 bilateral hemispheric cortical sub-areas were found to predict FCD and PNH, respectively. For each of these sub-areas, we were able to identify the T1 layer, which contributed the most to the prediction. CONCLUSION Our results reveal widespread cortical abnormalities in epilepsy patients with FCD and PNH, which may have a role in epileptogenesis, and likely related to recent studies showing widespread structural (e.g., cortical thinning) and diffusion abnormalities in various human epilepsy populations. Our study provides quantitative information of cortical laminar architecture in epilepsy patients that can be further targeted for study in functional and neuropathological studies.
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Affiliation(s)
- Eyal Lotan
- Department of Diagnostic Imaging, Sheba Medical Center, Tel Hashomer, 52621, Ramat Gan, Israel.
- Sackler Faculty of Medicine, Tel Aviv University, 69978, Tel Aviv, Israel.
- Department of Radiology, NYU Langone Medical Center, 660 1st Ave, New York, NY, 10016, USA.
| | - Omri Tomer
- Sagol School of Neuroscience, Tel Aviv University, 69978, Tel Aviv, Israel
| | - Ido Tavor
- Department of Diagnostic Imaging, Sheba Medical Center, Tel Hashomer, 52621, Ramat Gan, Israel
- Sackler Faculty of Medicine, Tel Aviv University, 69978, Tel Aviv, Israel
| | - Ilan Blatt
- Sackler Faculty of Medicine, Tel Aviv University, 69978, Tel Aviv, Israel
- Department of Neurology, Sheba Medical Center, Tel Hashomer, 52621, Ramat Gan, Israel
| | - Hadassah Goldberg-Stern
- Sackler Faculty of Medicine, Tel Aviv University, 69978, Tel Aviv, Israel
- Department of Neurology, Schneider Children's Medical Center of Israel, 49202, Petah Tikva, Israel
| | - Chen Hoffmann
- Department of Diagnostic Imaging, Sheba Medical Center, Tel Hashomer, 52621, Ramat Gan, Israel
- Sackler Faculty of Medicine, Tel Aviv University, 69978, Tel Aviv, Israel
| | - Galia Tsarfaty
- Department of Diagnostic Imaging, Sheba Medical Center, Tel Hashomer, 52621, Ramat Gan, Israel
- Sackler Faculty of Medicine, Tel Aviv University, 69978, Tel Aviv, Israel
| | - David Tanne
- Sackler Faculty of Medicine, Tel Aviv University, 69978, Tel Aviv, Israel
- Stroke Center, Department of Neurology and Sagol Neuroscience Center, Sheba Medical Center, Tel Hashomer, 52621, Ramat Gan, Israel
| | - Yaniv Assaf
- Sagol School of Neuroscience, Tel Aviv University, 69978, Tel Aviv, Israel
- Department of Neurobiology, The George S. Wise Faculty of Life Sciences, Tel Aviv University, 69978, Tel Aviv, Israel
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9
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Lin H, Leng X, Qin C, Wang W, Zhang C, Qiu S. Altered White Matter Structural Network in Frontal and Temporal Lobe Epilepsy: A Graph-Theoretical Study. Front Neurol 2020; 11:561. [PMID: 32625164 PMCID: PMC7311567 DOI: 10.3389/fneur.2020.00561] [Citation(s) in RCA: 16] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/07/2020] [Accepted: 05/18/2020] [Indexed: 01/28/2023] Open
Abstract
Temporal lobe epilepsy (TLE) and frontal lobe epilepsy (FLE) are the largest subgroup of partial epilepsy, and focal cortical dysplasias (FCDs) are highly epileptogenic brain lesions and are a frequent cause for antiepileptic drug (AED)-resistant focal epilepsies that mostly occur in the temporal and frontal lobes. We performed a graph-theoretical study based on the diffusion tensor imaging (DTI) data of patients with FLE or TLE caused by FCDs or lesions with high suspicion of FCDs and evaluated their cognitive function by the Chinese version of the Montreal Cognitive Assessment-Basic (MoCA-BC). The construction of the white matter structural network and graph-theoretical analysis was performed by Pipeline for Analysing Brain Diffusion Images (PANDA) and Graph-theoretical Network Analysis (GRETNA). We used the nonparametric analysis of covariance to compare the differences in diffusion metrics, network attributes and nodal attributes among FLE, TLE, and healthy control (HC) groups and then performed post hoc pairwise comparisons. Nonparametric Spearman partial correlation analysis was performed to analyse the correlation of network attributes with the age of onset, duration of disease, and MoCA-BC scores in patients with FLE and TLE. The results showed that the white matter structural network in patients with FLE and TLE was impaired in a more extensive set of regions than the FCD location. The similarities in white matter alterations between FLE and TLE suggested that their epileptogenic network might affect the fronto-temporal white matter tracts and thalamo-occipital connections, which might be responsible for the overlapping cognitive deficits in FLE and TLE. The white matter impairments in patients with FLE were more severe than those in patients with TLE, which might be explained by more affected nodes in the areas of DMN in patients with FLE.
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Affiliation(s)
- Huan Lin
- Department of Radiology, Zhujiang Hospital of Southern Medical University, Guangzhou, China
| | - Xi Leng
- Department of Radiology, First Affiliated Hospital of Guangzhou University of Chinese Medicine, Guangzhou, China
| | - Chunhong Qin
- Department of Radiology, First Affiliated Hospital of Guangzhou University of Chinese Medicine, Guangzhou, China
| | - Wensheng Wang
- Department of Radiology, Guangdong 999 Brain Hospital, Guangzhou, China
| | - Chi Zhang
- Department of Radiology, First Affiliated Hospital of Guangzhou University of Chinese Medicine, Guangzhou, China
| | - Shijun Qiu
- Department of Radiology, First Affiliated Hospital of Guangzhou University of Chinese Medicine, Guangzhou, China
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10
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Lorio S, Adler S, Gunny R, D'Arco F, Kaden E, Wagstyl K, Jacques TS, Clark CA, Cross JH, Baldeweg T, Carmichael DW. MRI profiling of focal cortical dysplasia using multi-compartment diffusion models. Epilepsia 2020; 61:433-444. [PMID: 32065673 PMCID: PMC7154549 DOI: 10.1111/epi.16451] [Citation(s) in RCA: 12] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/14/2019] [Revised: 01/26/2020] [Accepted: 01/27/2020] [Indexed: 12/11/2022]
Abstract
Objective Focal cortical dysplasia (FCD) lesion detection and subtyping remain challenging on conventional MRI. New diffusion models such as the spherical mean technique (SMT) and neurite orientation dispersion and density imaging (NODDI) provide measurements that potentially produce more specific maps of abnormal tissue microstructure. This study aims to assess the SMT and NODDI maps for computational and radiological lesion characterization compared to standard fractional anisotropy (FA) and mean diffusivity (MD). Methods SMT, NODDI, FA, and MD maps were calculated for 33 pediatric patients with suspected FCD (18 histologically confirmed). Two neuroradiologists scored lesion visibility on clinical images and diffusion maps. Signal profile changes within lesions and homologous regions were quantified using a surface‐based approach. Diffusion parameter changes at multiple cortical depths were statistically compared between FCD type IIa and type IIb. Results Compared to fluid‐attenuated inversion recovery (FLAIR) or T1‐weighted imaging, lesions conspicuity on NODDI intracellular volume fraction (ICVF) maps was better/equal/worse in 5/14/14 patients, respectively, while on SMT intra‐neurite volume fraction (INVF) in 3/3/27. Compared to FA or MD, lesion conspicuity on the ICVF was better/equal/worse in 27/4/2, while on the INVF in 20/7/6. Quantitative signal profiling demonstrated significant ICVF and INVF reductions in the lesions, whereas SMT microscopic mean, radial, and axial diffusivities were significantly increased. FCD type IIb exhibited greater changes than FCD type IIa. No changes were detected on FA or MD profiles. Significance FCD lesion‐specific signal changes were found in ICVF and INVF but not in FA and MD maps. ICVF and INVF showed greater contrast than FLAIR in some cases and had consistent signal changes specific to FCD, suggesting that they could improve current presurgical pediatric epilepsy imaging protocols and can provide features useful for automated lesion detection.
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Affiliation(s)
- Sara Lorio
- Developmental Neurosciences, Great Ormond Street Institute of Child Health, University College London, London, UK.,School of Biomedical Engineering & Imaging Sciences, St Thomas' Hospital, King's College London, London, UK
| | - Sophie Adler
- Developmental Neurosciences, Great Ormond Street Institute of Child Health, University College London, London, UK
| | | | | | - Enrico Kaden
- Centre for Medical Image Computing, University College London, London, UK
| | - Konrad Wagstyl
- Brain Mapping Unit, Institute of Psychiatry, University of Cambridge, Cambridge, UK
| | - Thomas S Jacques
- Developmental Biology and Cancer Programme, UCL Great Ormond Street Institute of Child Health, University College London, London, UK.,Department of Histopathology, Great Ormond Street Hospital for Children NHS Foundation Trust, London, UK
| | - Chris A Clark
- Developmental Neurosciences, Great Ormond Street Institute of Child Health, University College London, London, UK
| | - Judith Helen Cross
- Developmental Neurosciences, Great Ormond Street Institute of Child Health, University College London, London, UK
| | - Torsten Baldeweg
- Developmental Neurosciences, Great Ormond Street Institute of Child Health, University College London, London, UK
| | - David W Carmichael
- Developmental Neurosciences, Great Ormond Street Institute of Child Health, University College London, London, UK.,School of Biomedical Engineering & Imaging Sciences, St Thomas' Hospital, King's College London, London, UK
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11
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Kreilkamp BAK, Lisanti L, Glenn GR, Wieshmann UC, Das K, Marson AG, Keller SS. Comparison of manual and automated fiber quantification tractography in patients with temporal lobe epilepsy. NEUROIMAGE-CLINICAL 2019; 24:102024. [PMID: 31670154 PMCID: PMC6831895 DOI: 10.1016/j.nicl.2019.102024] [Citation(s) in RCA: 13] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 05/29/2019] [Revised: 09/05/2019] [Accepted: 09/27/2019] [Indexed: 11/25/2022]
Abstract
Tractography approaches showed moderate to good agreement for tract morphology. Along- and whole-tract diffusivity was significantly correlated across approaches. Whole-tract AFQ but not manual tract diffusivity correlated with clinical variables. Absence of excellent agreement between approaches warrants caution.
Objective To investigate the agreement between manually and automatically generated tracts from diffusion tensor imaging (DTI) in patients with temporal lobe epilepsy (TLE). Whole and along-the-tract diffusivity metrics and correlations with patient clinical characteristics were analyzed with respect to tractography approach. Methods We recruited 40 healthy controls and 24 patients with TLE who underwent conventional T1-weighted imaging and 60-direction DTI. An automated (Automated Fiber Quantification, AFQ) and manual (TrackVis) deterministic tractography approach was used to identify the uncinate fasciculus (UF) and parahippocampal white matter bundle (PHWM). Tract diffusion scalar metrics were analyzed with respect to agreement across automated and manual approaches (Dice Coefficient and Spearman correlations), to side of onset of epilepsy and patient clinical characteristics, including duration of epilepsy, age of onset and presence of hippocampal sclerosis. Results Across approaches the analysis of tract morphology similarity revealed Dice coefficients at moderate to good agreement (0.54 - 0.6) and significant correlations between diffusion values (Spearman's Rho=0.4–0.9). However, within bilateral PHWM, AFQ yielded significantly lower FA (left: Z = 4.4, p<0.001; right: Z = 5.1, p<0.001) and higher MD values (left: Z=-4.7, p<0.001; right: Z=-3.7, p<0.001) compared to the manual approach. Whole tract DTI metrics determined using AFQ were significantly correlated with patient characteristics, including age of epilepsy onset in FA (R = 0.6, p = 0.02) and MD of the ipsilateral PHWM (R=-0.6, p = 0.02), while duration of epilepsy corrected for age correlated with MD in ipsilateral PHWM (R = 0.7, p<0.01). Correlations between clinical metrics and diffusion values extracted using the manual whole tract technique did not survive correction for multiple comparisons. Both manual and automated along-the-tract analyses demonstrated significant correlations with patient clinical characteristics such as age of onset and epilepsy duration. The strongest and most widespread localized ipsi- and contralateral diffusivity alterations were observed in patients with left TLE and patients with HS compared to controls, while patients with right TLE and patients without HS did not show these strong effects. Conclusions Manual and AFQ tractography approaches revealed significant correlations in the reconstruction of tract morphology and extracted whole and along-tract diffusivity values. However, as non-identical methods they differed in the respective yield of significant results across clinical correlations and group-wise statistics. Given the absence of excellent agreement between manual and AFQ techniques as demonstrated in the present study, caution should be considered when using AFQ particularly when used without reference to benchmark manual measures.
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Affiliation(s)
- Barbara A K Kreilkamp
- Department of Molecular and Clinical Pharmacology, Institute of Translational Medicine, University of Liverpool, Liverpool, United Kingdom; Department of Neurology, The Walton Centre NHS Foundation Trust, Liverpool, United Kingdom.
| | - Lucy Lisanti
- Department of Molecular and Clinical Pharmacology, Institute of Translational Medicine, University of Liverpool, Liverpool, United Kingdom; Royal Society, London, United Kingdom
| | - G Russell Glenn
- Department of Radiology and Imaging Sciences, Emory University, Atlanta, GA, United States
| | - Udo C Wieshmann
- Department of Neurology, The Walton Centre NHS Foundation Trust, Liverpool, United Kingdom
| | - Kumar Das
- Department of Neuroradiology, The Walton Centre NHS Foundation Trust, Liverpool, United Kingdom
| | - Anthony G Marson
- Department of Molecular and Clinical Pharmacology, Institute of Translational Medicine, University of Liverpool, Liverpool, United Kingdom; Department of Neurology, The Walton Centre NHS Foundation Trust, Liverpool, United Kingdom
| | - Simon S Keller
- Department of Molecular and Clinical Pharmacology, Institute of Translational Medicine, University of Liverpool, Liverpool, United Kingdom; Department of Neurology, The Walton Centre NHS Foundation Trust, Liverpool, United Kingdom
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12
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Gyebnár G, Klimaj Z, Entz L, Fabó D, Rudas G, Barsi P, Kozák LR. Personalized microstructural evaluation using a Mahalanobis-distance based outlier detection strategy on epilepsy patients' DTI data - Theory, simulations and example cases. PLoS One 2019; 14:e0222720. [PMID: 31545838 PMCID: PMC6756533 DOI: 10.1371/journal.pone.0222720] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/21/2019] [Accepted: 09/05/2019] [Indexed: 11/19/2022] Open
Abstract
Quantitative MRI methods have recently gained extensive interest and are seeing substantial developments; however, their application in single patient vs control group comparisons is often limited by inherent statistical difficulties. One such application is detecting malformations of cortical development (MCDs) behind drug resistant epilepsies, a task that, especially when based solely on conventional MR images, may represent a serious challenge. We aimed to develop a novel straightforward voxel-wise evaluation method based on the Mahalanobis-distance, combining quantitative MRI data into a multidimensional parameter space and detecting lesion voxels as outliers. Simulations with standard multivariate Gaussian distribution and resampled DTI-eigenvalue data of 45 healthy control subjects determined the optimal critical value, cluster size threshold, and the expectable lesion detection performance through ROC-analyses. To reduce the effect of false positives emanating from registration artefacts and gyrification differences, an automatic classification method was applied, fine-tuned using a leave-one-out strategy based on diffusion and T1-weighted data of the controls. DWI processing, including thorough corrections and robust tensor fitting was performed with ExploreDTI, spatial coregistration was achieved with the DARTEL tools of SPM12. Additional to simulations, clusters of outlying diffusion profile, concordant with neuroradiological evaluation and independent calculations with the MAP07 toolbox were identified in 12 cases of a 13 patient example population with various types of MCDs. The multidimensional approach proved sufficiently sensitive in pinpointing regions of abnormal tissue microstructure using DTI data both in simulations and in the heterogeneous example population. Inherent limitations posed by registration artefacts, age-related differences, and the different or mixed pathologies limit the generalization of specificity estimation. Nevertheless, the proposed statistical method may aid the everyday examination of individual subjects, ever so more upon extending the framework with quantitative information from other modalities, e.g. susceptibility mapping, relaxometry, or perfusion.
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Affiliation(s)
- Gyula Gyebnár
- Magnetic Resonance Research Centre, Semmelweis University, Budapest, Hungary
| | - Zoltán Klimaj
- Magnetic Resonance Research Centre, Semmelweis University, Budapest, Hungary
| | - László Entz
- National Institute of Clinical Neurosciences, Budapest, Hungary
| | - Dániel Fabó
- National Institute of Clinical Neurosciences, Budapest, Hungary
| | - Gábor Rudas
- Magnetic Resonance Research Centre, Semmelweis University, Budapest, Hungary
| | - Péter Barsi
- Magnetic Resonance Research Centre, Semmelweis University, Budapest, Hungary
| | - Lajos R. Kozák
- Magnetic Resonance Research Centre, Semmelweis University, Budapest, Hungary
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13
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Larivière S, Vos de Wael R, Paquola C, Hong SJ, Mišić B, Bernasconi N, Bernasconi A, Bonilha L, Bernhardt BC. Microstructure-Informed Connectomics: Enriching Large-Scale Descriptions of Healthy and Diseased Brains. Brain Connect 2018; 9:113-127. [PMID: 30079754 DOI: 10.1089/brain.2018.0587] [Citation(s) in RCA: 40] [Impact Index Per Article: 6.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/20/2022] Open
Abstract
Rapid advances in neuroimaging and network science have produced powerful tools and measures to appreciate human brain organization at multiple spatial and temporal scales. It is now possible to obtain increasingly meaningful representations of whole-brain structural and functional brain networks and to formally assess macroscale principles of network topology. In addition to its utility in characterizing healthy brain organization, individual variability, and life span-related changes, there is high promise of network neuroscience for the conceptualization and, ultimately, management of brain disorders. In the current review, we argue for a science of the human brain that, while strongly embracing macroscale connectomics, also recommends awareness of brain properties derived from meso- and microscale resolutions. Such features include MRI markers of tissue microstructure, local functional properties, as well as information from nonimaging domains, including cellular, genetic, or chemical data. Integrating these measures with connectome models promises to better define the individual elements that constitute large-scale networks, and clarify the notion of connection strength among them. By enriching the description of large-scale networks, this approach may improve our understanding of fundamental principles of healthy brain organization. Notably, it may also better define the substrate of prevalent brain disorders, including stroke, autism, as well as drug-resistant epilepsies that are each characterized by intriguing interactions between local anomalies and network-level perturbations.
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Affiliation(s)
- Sara Larivière
- 1 Multimodal Imaging and Connectome Analysis Laboratory, McConnell Brain Imaging Centre, Montreal Neurological Institute and Hospital, McGill University, Montreal, Canada
| | - Reinder Vos de Wael
- 1 Multimodal Imaging and Connectome Analysis Laboratory, McConnell Brain Imaging Centre, Montreal Neurological Institute and Hospital, McGill University, Montreal, Canada
| | - Casey Paquola
- 1 Multimodal Imaging and Connectome Analysis Laboratory, McConnell Brain Imaging Centre, Montreal Neurological Institute and Hospital, McGill University, Montreal, Canada
| | - Seok-Jun Hong
- 1 Multimodal Imaging and Connectome Analysis Laboratory, McConnell Brain Imaging Centre, Montreal Neurological Institute and Hospital, McGill University, Montreal, Canada.,2 NeuroImaging of Epilepsy Laboratory, McConnell Brain Imaging Centre, Montreal Neurological Institute and Hospital, McGill University, Montreal, Canada
| | - Bratislav Mišić
- 3 Network Neuroscience Laboratory, McConnell Brain Imaging Centre, Montreal Neurological Institute and Hospital, McGill University, Montreal, Canada
| | - Neda Bernasconi
- 2 NeuroImaging of Epilepsy Laboratory, McConnell Brain Imaging Centre, Montreal Neurological Institute and Hospital, McGill University, Montreal, Canada
| | - Andrea Bernasconi
- 2 NeuroImaging of Epilepsy Laboratory, McConnell Brain Imaging Centre, Montreal Neurological Institute and Hospital, McGill University, Montreal, Canada
| | - Leonardo Bonilha
- 4 Department of Neurosciences, Medical University of South Carolina, Charleston, South Carolina
| | - Boris C Bernhardt
- 1 Multimodal Imaging and Connectome Analysis Laboratory, McConnell Brain Imaging Centre, Montreal Neurological Institute and Hospital, McGill University, Montreal, Canada
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14
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Rezayev A, Feldman HA, Levman J, Takahashi E. Bilateral thalamocortical abnormalities in focal cortical dysplasia. Brain Res 2018; 1694:38-45. [PMID: 29738718 DOI: 10.1016/j.brainres.2018.05.005] [Citation(s) in RCA: 13] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/04/2017] [Revised: 05/03/2018] [Accepted: 05/04/2018] [Indexed: 11/26/2022]
Abstract
BACKGROUND AND PURPOSE Focal cortical dysplasia (FCD), a congenital malformation of the neocortex and one of the most common causes of medication resistant epilepsy in pediatric populations, can be studied noninvasively by diffusion tensor imaging (DTI). The present study aimed to quantify changes in the thalamus and thalamocortical pathways with respect to fractional anisotropy (FA), apparent diffusion coefficient (ADC), volume, and other common measures. MATERIALS AND METHODS The study quantified data collected from pediatric patients with a prior diagnosis of FCD; 75 patients (35 females, 10.1 ± 6.5 years) for analysis of thalamic volume and 68 patients (32 females, 10.2 ± 6.4 years) for DTI analysis. DTI scans were taken at 3 Tesla MRI scanners (30 diffusion gradient directions; b = 1000 s/mm2 and 5 non diffusion-weighted measurements). DTI tractography was performed using the FACT algorithm with an angle threshold of 45 degrees. Manually delineated ROIs were used to compare the hemisphere containing the dysplasia to the contralateral hemisphere and controls. RESULTS A significant decrease in the volume of the FCD hemisphere thalamus was detected as compared to the contralateral hemisphere. In comparison to controls, there was an observed reduction in tract volume, length, count, FA of thalami, and FA of thalamocortical pathways in FCD patients. FCD patients had higher odds of exhibiting high ADC in both the thalamus and thalamocortical pathways. CONCLUSION The data implied a widespread reduction in structural connectivity of the thalamocortical network. MRI analysis suggests a potential influence of FCD on thalamic volume.
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Affiliation(s)
- Arthur Rezayev
- Department of Biology, Boston University, 5 Cummington Mall, Boston, MA 02215, USA; Division of Newborn Medicine, Department of Medicine, Boston Children's Hospital, Harvard Medical School, 300 Longwood Avenue, Boston, MA 02115, USA
| | - Henry A Feldman
- Clinical Research Center, Boston Children's Hospital, Harvard Medical School, 300 Longwood Ave, Boston, MA 02115, USA
| | - Jacob Levman
- Division of Newborn Medicine, Department of Medicine, Boston Children's Hospital, Harvard Medical School, 300 Longwood Avenue, Boston, MA 02115, USA; Department of Mathematics, Statistics and Computer Science, St. Francis Xavier University, Antigonish, NS B2G 2W5, Canada; Athinoula A. Martinos Center for Biomedical Imaging, Massachusetts General Hospital, Harvard Medical School, Charelestown, MA 02219, USA
| | - Emi Takahashi
- Division of Newborn Medicine, Department of Medicine, Boston Children's Hospital, Harvard Medical School, 300 Longwood Avenue, Boston, MA 02115, USA; Athinoula A. Martinos Center for Biomedical Imaging, Massachusetts General Hospital, Harvard Medical School, Charelestown, MA 02219, USA.
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15
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Deleo F, Thom M, Concha L, Bernasconi A, Bernhardt BC, Bernasconi N. Histological and MRI markers of white matter damage in focal epilepsy. Epilepsy Res 2017; 140:29-38. [PMID: 29227798 DOI: 10.1016/j.eplepsyres.2017.11.010] [Citation(s) in RCA: 40] [Impact Index Per Article: 5.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/29/2017] [Revised: 11/10/2017] [Accepted: 11/20/2017] [Indexed: 12/21/2022]
Abstract
Growing evidence highlights the importance of white matter in the pathogenesis of focal epilepsy. Ex vivo and post-mortem studies show pathological changes in epileptic patients in white matter myelination, axonal integrity, and cellular composition. Diffusion-weighted MRI and its analytical extensions, particularly diffusion tensor imaging (DTI), have been the most widely used technique to image the white matter in vivo for the last two decades, and have shown microstructural alterations in multiple tracts both in the vicinity and at distance from the epileptogenic focus. These techniques have also shown promising ability to predict cognitive status and response to pharmacological or surgical treatments. More recently, the hypothesis that focal epilepsy may be more adequately described as a system-level disorder has motivated a shift towards the study of macroscale brain connectivity. This review will cover emerging findings contributing to our understanding of white matter alterations in focal epilepsy, studied by means of histological and ultrastructural analyses, diffusion MRI, and large-scale network analysis. Focus is put on temporal lobe epilepsy and focal cortical dysplasia. This topic was addressed in a special interest group on neuroimaging at the 70th annual meeting of the American Epilepsy Society, held in Houston December 2-6, 2016.
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Affiliation(s)
- Francesco Deleo
- NeuroImaging of Epilepsy Laboratory, Montreal Neurological Institute, McGill University, Canada
| | - Maria Thom
- Division of Neuropathology and Department of Clinical and Experimental Epilepsy, UCL Institute of Neurology, Queen Square, London WC1N 3BG, UK
| | - Luis Concha
- Instituto de Neurobiología, Universidad Nacional Autónoma de México, Querétaro, Mexico
| | - Andrea Bernasconi
- NeuroImaging of Epilepsy Laboratory, Montreal Neurological Institute, McGill University, Canada
| | - Boris C Bernhardt
- NeuroImaging of Epilepsy Laboratory, Montreal Neurological Institute, McGill University, Canada; Multimodal Imaging and Connectome Analysis Laboratory, Montreal Neurological Institute, McGill University, Canada
| | - Neda Bernasconi
- NeuroImaging of Epilepsy Laboratory, Montreal Neurological Institute, McGill University, Canada.
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16
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Besseling RMH, Jansen JFA, de Louw AJA, Vlooswijk MCG, Hoeberigs MC, Aldenkamp AP, Backes WH, Hofman PAM. Abnormal Profiles of Local Functional Connectivity Proximal to Focal Cortical Dysplasias. PLoS One 2016; 11:e0166022. [PMID: 27861502 PMCID: PMC5115673 DOI: 10.1371/journal.pone.0166022] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/04/2015] [Accepted: 10/21/2016] [Indexed: 11/18/2022] Open
Abstract
Introduction Focal cortical dysplasia (FCD) is a congenital malformation of cortical development that often leads to medically refractory epilepsy. Focal resection can be an effective treatment, but is challenging as the surgically relevant abnormality may exceed the MR-visible lesion. The aim of the current study is to develop methodology to characterize the profile of functional connectivity around FCDs using resting-state functional MRI and in the individual patient. The detection of aberrant connectivity may provide a means to more completely delineate the clinically relevant lesion. Materials and Methods Fifteen FCD patients (age, mean±SD: 31±11 years; 11 males) and 16 matched healthy controls (35±9 years; 7 males) underwent structural and functional imaging at 3 Tesla. The cortical surface was reconstructed from the T1-weighted scan and the registered functional MRI data was spatially normalized to a common anatomical standard space employing the gyral pattern. Seed-based functional connectivity was determined in all subjects for all dysplasia locations. A single patient was excluded based on an aberrant FCD seed time series. Functional connectivity as a function of geodesic distance (along the cortical surface) was compared between the individual patients and the homotopic normative connectivity profiles derived from the controls. Results In 12/14 patients, aberrant profiles of functional connectivity were found, which demonstrated both hyper- and hypoconnectivity as well as combinations. Abnormal functional connectivity was typically found (also) beyond the lesion visible on structural MRI, while functional connectivity profiles not related to a lesion appeared normal in patients. Conclusion This novel functional MRI technique has potential for delineating functionally aberrant from normal cortex beyond the structural lesion in FCD, which remains to be confirmed in future research.
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Affiliation(s)
- René M. H. Besseling
- Epilepsy center Kempenhaeghe, Heeze, the Netherlands
- Research School for Mental Health & Neuroscience, Maastricht University, Maastricht, the Netherlands
- Department of Radiology, Maastricht University Medical Center, Maastricht, the Netherlands
| | - Jacobus F. A. Jansen
- Research School for Mental Health & Neuroscience, Maastricht University, Maastricht, the Netherlands
- Department of Radiology, Maastricht University Medical Center, Maastricht, the Netherlands
| | | | - Mariëlle C. G. Vlooswijk
- Research School for Mental Health & Neuroscience, Maastricht University, Maastricht, the Netherlands
- Department of Neurology, Maastricht University Medical Center, Maastricht, the Netherlands
| | | | - Albert P. Aldenkamp
- Epilepsy center Kempenhaeghe, Heeze, the Netherlands
- Department of Neurology, Maastricht University Medical Center, Maastricht, the Netherlands
| | - Walter H. Backes
- Research School for Mental Health & Neuroscience, Maastricht University, Maastricht, the Netherlands
- Department of Radiology, Maastricht University Medical Center, Maastricht, the Netherlands
| | - Paul A. M. Hofman
- Epilepsy center Kempenhaeghe, Heeze, the Netherlands
- Research School for Mental Health & Neuroscience, Maastricht University, Maastricht, the Netherlands
- Department of Radiology, Maastricht University Medical Center, Maastricht, the Netherlands
- * E-mail:
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Hong SJ, Bernhardt BC, Schrader DS, Bernasconi N, Bernasconi A. Whole-brain MRI phenotyping in dysplasia-related frontal lobe epilepsy. Neurology 2016; 86:643-50. [PMID: 26764030 DOI: 10.1212/wnl.0000000000002374] [Citation(s) in RCA: 65] [Impact Index Per Article: 8.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/10/2015] [Accepted: 08/03/2015] [Indexed: 01/01/2023] Open
Abstract
OBJECTIVE To perform whole-brain morphometry in patients with frontal lobe epilepsy and evaluate the utility of group-level patterns for individualized diagnosis and prognosis. METHODS We compared MRI-based cortical thickness and folding complexity between 2 frontal lobe epilepsy cohorts with histologically verified focal cortical dysplasia (FCD) (13 type I; 28 type II) and 41 closely matched controls. Pattern learning algorithms evaluated the utility of group-level findings to predict histologic FCD subtype, the side of the seizure focus, and postsurgical seizure outcome in single individuals. RESULTS Relative to controls, FCD type I displayed multilobar cortical thinning that was most marked in ipsilateral frontal cortices. Conversely, type II showed thickening in temporal and postcentral cortices. Cortical folding also diverged, with increased complexity in prefrontal cortices in type I and decreases in type II. Group-level findings successfully guided automated FCD subtype classification (type I: 100%; type II: 96%), seizure focus lateralization (type I: 92%; type II: 86%), and outcome prediction (type I: 92%; type II: 82%). CONCLUSION FCD subtypes relate to diverse whole-brain structural phenotypes. While cortical thickening in type II may indicate delayed pruning, a thin cortex in type I likely results from combined effects of seizure excitotoxicity and the primary malformation. Group-level patterns have a high translational value in guiding individualized diagnostics.
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Affiliation(s)
- Seok-Jun Hong
- From the Neuroimaging of Epilepsy Laboratory, Department of Neurology and McConnell Brain Imaging Centre, Montreal Neurological Institute and Hospital, McGill University, Montreal, Canada
| | - Boris C Bernhardt
- From the Neuroimaging of Epilepsy Laboratory, Department of Neurology and McConnell Brain Imaging Centre, Montreal Neurological Institute and Hospital, McGill University, Montreal, Canada
| | - Dewi S Schrader
- From the Neuroimaging of Epilepsy Laboratory, Department of Neurology and McConnell Brain Imaging Centre, Montreal Neurological Institute and Hospital, McGill University, Montreal, Canada
| | - Neda Bernasconi
- From the Neuroimaging of Epilepsy Laboratory, Department of Neurology and McConnell Brain Imaging Centre, Montreal Neurological Institute and Hospital, McGill University, Montreal, Canada
| | - Andrea Bernasconi
- From the Neuroimaging of Epilepsy Laboratory, Department of Neurology and McConnell Brain Imaging Centre, Montreal Neurological Institute and Hospital, McGill University, Montreal, Canada.
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18
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Pre-operative evaluation in pediatric patients with cortical dysplasia. Childs Nerv Syst 2015; 31:2225-33. [PMID: 26280628 DOI: 10.1007/s00381-015-2869-1] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 10/09/2014] [Accepted: 08/03/2015] [Indexed: 01/12/2023]
Abstract
INTRODUCTION Focal cortical dysplasia (FCD) is an important cause of refractory seizures and catastrophic epilepsy in infants and children who had epilepsy surgery. AIMS OF THE REVIEW This manuscript will discuss age-related unique clinical characteristics in evaluation of infants and young children because the understanding of these age-related features is critical in selecting children who can benefit from epilepsy surgery. In addition, we will review the non-invasive tools available for the presurgical evaluation of children with FCD and their individual contribution to the formulation of the presurgical hypothesis.
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Ridley BGY, Rousseau C, Wirsich J, Le Troter A, Soulier E, Confort-Gouny S, Bartolomei F, Ranjeva JP, Achard S, Guye M. Nodal approach reveals differential impact of lateralized focal epilepsies on hub reorganization. Neuroimage 2015; 118:39-48. [PMID: 26070261 DOI: 10.1016/j.neuroimage.2015.05.096] [Citation(s) in RCA: 36] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/24/2014] [Revised: 04/30/2015] [Accepted: 05/21/2015] [Indexed: 02/07/2023] Open
Abstract
The impact of the hemisphere affected by impairment in models of network disease is not fully understood. Among such models, focal epilepsies are characterised by recurrent seizures generated in epileptogenic areas also responsible for wider network dysfunction between seizures. Previous work focusing on functional connectivity within circumscribed networks suggests a divergence of network integrity and compensatory capacity between epilepsies as a function of the laterality of seizure onset. We evaluated the ability of complex network theory to reveal changes in focal epilepsy in global and nodal parameters using graph theoretical analysis of functional connectivity data obtained with resting-state fMRI. Graphs of functional connectivity networks were derived from 19 right and 13 left focal epilepsy patients and 15 controls. Topological metrics (degree, local efficiency, global efficiency and modularity) were computed for a whole-brain, atlas-defined network. We also calculated a hub disruption index for each graph metric, measuring the capacity of the brain network to demonstrate increased connectivity in some nodes for decreased connectivity in others. Our data demonstrate that the patient group as a whole is characterised by network-wide pattern of reorganization, even while global parameters fail to distinguish between groups. Furthermore, multiple metrics indicate that epilepsies with differently lateralized epileptic networks are asymmetric in their burden on functional brain networks; with left epilepsy patients being characterised by reduced efficiency and modularity, while in right epilepsy patients we provide the first evidence that functional brain networks are characterised by enhanced connectivity and efficiency at some nodes whereas reduced in others.
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Affiliation(s)
- Ben Gendon Yeshe Ridley
- Aix-Marseille Université, CNRS, CRMBM UMR 7339, 13005 Marseille, France; APHM, Hôpital de la Timone, Pôle d'Imagerie Médicale, CEMEREM, 13005 Marseille, France.
| | - Celia Rousseau
- Aix-Marseille Université, CNRS, CRMBM UMR 7339, 13005 Marseille, France; APHM, Hôpital de la Timone, Pôle d'Imagerie Médicale, CEMEREM, 13005 Marseille, France.
| | - Jonathan Wirsich
- Aix-Marseille Université, CNRS, CRMBM UMR 7339, 13005 Marseille, France; APHM, Hôpital de la Timone, Pôle d'Imagerie Médicale, CEMEREM, 13005 Marseille, France.
| | - Arnaud Le Troter
- Aix-Marseille Université, CNRS, CRMBM UMR 7339, 13005 Marseille, France; APHM, Hôpital de la Timone, Pôle d'Imagerie Médicale, CEMEREM, 13005 Marseille, France.
| | - Elisabeth Soulier
- Aix-Marseille Université, CNRS, CRMBM UMR 7339, 13005 Marseille, France; APHM, Hôpital de la Timone, Pôle d'Imagerie Médicale, CEMEREM, 13005 Marseille, France.
| | - Sylvianne Confort-Gouny
- Aix-Marseille Université, CNRS, CRMBM UMR 7339, 13005 Marseille, France; APHM, Hôpital de la Timone, Pôle d'Imagerie Médicale, CEMEREM, 13005 Marseille, France.
| | - Fabrice Bartolomei
- APHM, Hôpital de la Timone, Service de Neurophysiologie Clinique, 13005 Marseille, France; Aix-Marseille Université, INSERM, Institut de Neuroscience des Systèmes U1106, 13005 Marseille, France.
| | - Jean-Philippe Ranjeva
- Aix-Marseille Université, CNRS, CRMBM UMR 7339, 13005 Marseille, France; APHM, Hôpital de la Timone, Pôle d'Imagerie Médicale, CEMEREM, 13005 Marseille, France.
| | - Sophie Achard
- Centre National de la Recherche Scientifique, Grenoble Image Parole Signal Automatique, 38402 Grenoble, France.
| | - Maxime Guye
- Aix-Marseille Université, CNRS, CRMBM UMR 7339, 13005 Marseille, France; APHM, Hôpital de la Timone, Pôle d'Imagerie Médicale, CEMEREM, 13005 Marseille, France.
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20
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Roca P, Mellerio C, Chassoux F, Rivière D, Cachia A, Charron S, Lion S, Mangin JF, Devaux B, Meder JF, Oppenheim C. Sulcus-based MR analysis of focal cortical dysplasia located in the central region. PLoS One 2015; 10:e0122252. [PMID: 25822985 PMCID: PMC4378936 DOI: 10.1371/journal.pone.0122252] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/05/2014] [Accepted: 02/10/2015] [Indexed: 11/29/2022] Open
Abstract
Objective Focal cortical dysplasias (FCDs) are mainly located in the frontal region, with a particular tropism for the central sulcus. Up to 30% of lesions are undetected (magnetic resonance [MR]-negative FCD patients) or belatedly diagnosed by visual analysis of MR images. We propose an automated sulcus-based method to analyze abnormal sulcal patterns associated with central FCD, taking into account the normal interindividual sulcal variability. Methods We retrospectively studied 29 right-handed patients with FCD in the central region (including 12 MR negative histologically-confirmed cases) and 29 right-handed controls. The analysis of sulcal abnormalities from T1-weighted MR imaging (MRI) was performed using a graph-based representation of the cortical folds and an automated sulci recognition system, providing a new quantitative criterion to describe sulcal patterns, termed sulcus energy. Results Group analysis showed that the central sulcus in the hemisphere ipsilateral to the FCD exhibited an abnormal sulcal pattern compared with controls (p = 0.032). FCDs were associated with abnormal patterns of the central sulci compared with controls (p = 0.006), a result that remained significant when MR-negative and MR-positive patients were considered separately, while the effects of sex, age and MR-field were not significant. At the individual level, sulcus energy alone failed to detect the FCD lesion. We found, however, a significant association between maximum z-scores and the site of FCD (p = 0.0046) which remained significant in MR-negative (p = 0.024) but not in MR-positive patients (p = 0.058). The maximum z-score pointed to an FCD sulcus in four MR-negative and five MR-positive patients. Conclusions We identified abnormal sulcal patterns in patients with FCD of the central region compared with healthy controls. The abnormal sulcal patterns ipsilateral to the FCD and the link between sulcus energy and the FCD location strengthen the interest of sulcal abnormalities in FCD patients.
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Affiliation(s)
- Pauline Roca
- Department of Neuroimaging, Sainte-Anne Hospital Center, Université Paris Descartes Sorbonne Paris Cité, Center for Psychiatry & Neurosciences, UMR 894 INSERM, Paris, France
- * E-mail:
| | - Charles Mellerio
- Department of Neuroimaging, Sainte-Anne Hospital Center, Université Paris Descartes Sorbonne Paris Cité, Center for Psychiatry & Neurosciences, UMR 894 INSERM, Paris, France
| | - Francine Chassoux
- Department of Neurosurgery, Sainte-Anne Hospital Center, Université Paris Descartes Sorbonne Paris Cité, Paris, France
| | | | - Arnaud Cachia
- Center for Psychiatry & Neurosciences, Sainte-Anne Hospital Center, UMR 894 INSERM/Université Paris Descartes & Laboratory for the Psychology of Child Development and Education, UMR 8240 CNRS/Université Paris Descartes Sorbonne Paris Cité, Paris, France
| | - Sylvain Charron
- Department of Neuroimaging, Sainte-Anne Hospital Center, Université Paris Descartes Sorbonne Paris Cité, Center for Psychiatry & Neurosciences, UMR 894 INSERM, Paris, France
| | - Stéphanie Lion
- Department of Neuroimaging, Sainte-Anne Hospital Center, Université Paris Descartes Sorbonne Paris Cité, Center for Psychiatry & Neurosciences, UMR 894 INSERM, Paris, France
| | | | - Bertrand Devaux
- Department of Neurosurgery, Sainte-Anne Hospital Center, Université Paris Descartes Sorbonne Paris Cité, Paris, France
| | - Jean-François Meder
- Department of Neuroimaging, Sainte-Anne Hospital Center, Université Paris Descartes Sorbonne Paris Cité, Center for Psychiatry & Neurosciences, UMR 894 INSERM, Paris, France
| | - Catherine Oppenheim
- Department of Neuroimaging, Sainte-Anne Hospital Center, Université Paris Descartes Sorbonne Paris Cité, Center for Psychiatry & Neurosciences, UMR 894 INSERM, Paris, France
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21
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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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22
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Chaudhary UJ, Duncan JS. Applications of blood-oxygen-level-dependent functional magnetic resonance imaging and diffusion tensor imaging in epilepsy. Neuroimaging Clin N Am 2014; 24:671-94. [PMID: 25441507 DOI: 10.1016/j.nic.2014.07.001] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/07/2023]
Abstract
The lifetime prevalence of epilepsy ranges from 2.7 to 12.4 per 1000 in Western countries. Around 30% of patients with epilepsy remain refractory to antiepileptic drugs and continue to have seizures. Noninvasive imaging techniques such as functional magnetic resonance imaging (fMRI) and diffusion tensor imaging (DTI) have helped to better understand mechanisms of seizure generation and propagation, and to localize epileptic, eloquent, and cognitive networks. In this review, the clinical applications of fMRI and DTI are discussed, for mapping cognitive and epileptic networks and organization of white matter tracts in individuals with epilepsy.
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Affiliation(s)
- Umair J Chaudhary
- Department of Clinical and Experimental Epilepsy, UCL Institute of Neurology, Queen Square, London WC1N 3BG, UK; MRI Unit, Epilepsy Society, Chesham Lane, Chalfont St Peter, Buckinghamshire SL9 0RJ, UK.
| | - John S Duncan
- Department of Clinical and Experimental Epilepsy, UCL Institute of Neurology, Queen Square, London WC1N 3BG, UK; MRI Unit, Epilepsy Society, Chesham Lane, Chalfont St Peter, Buckinghamshire SL9 0RJ, UK; Queen Square Division, UCLH NHS Foundation Trust, Queen Square, London WC1N 3BG, UK
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23
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Andrade CS, Leite CC, Otaduy MCG, Lyra KP, Valente KDR, Yasuda CL, Beltramini GC, Beaulieu C, Gross DW. Diffusion abnormalities of the corpus callosum in patients with malformations of cortical development and epilepsy. Epilepsy Res 2014; 108:1533-42. [PMID: 25260933 DOI: 10.1016/j.eplepsyres.2014.08.023] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/08/2014] [Revised: 07/25/2014] [Accepted: 08/31/2014] [Indexed: 11/19/2022]
Abstract
PURPOSE Diffusion tensor imaging (DTI) is a magnetic resonance imaging (MRI) technique that can characterize white matter (WM) architecture and microstructure. DTI has demonstrated extensive WM changes in patients with several epileptic syndromes, but few studies have focused on patients with malformations of cortical development (MCD). Our aim was to investigate the quantitative diffusion properties of the corpus callosum (CC), a major commissural bundle critical in inter-hemispheric connectivity, in a large group of patients with MCD. METHODS Thirty-two MCD patients and 32 age and sex-matched control subjects were evaluated with DTI at 3.0 T. We analyzed the three major subdivisions of the CC (genu, body, and splenium) with deterministic tractography to yield fractional anisotropy (FA), mean diffusivity (MD), parallel diffusivity (λ||) and perpendicular diffusivity (λ⊥). We further assessed the CC with region of interest (ROI)-based analyses and evaluated different subgroups of MCD (polymicrogyria/schizencephaly, heterotopia, and cortical dysplasia). Partial correlations between diffusion changes and clinical parameters (epilepsy duration and age at disease onset) were also queried. RESULTS There were significant reductions of FA, accompanied by increases in MD and λ⊥ in all segments of the CC in the patients group with both analytical methods. The absolute differences in FA were greater on ROI-analyses. There were no significant differences between the MCD subgroups, and no correlations between clinical parameters of epilepsy and FA. CONCLUSIONS Our study indicates DTI abnormalities consistent with microstructural changes in the corpus callosum of MCD patients. The findings support the idea that patients with epilepsy secondary to cortical malformations present widespread WM changes that extend beyond the macroscopic MRI-visible lesions.
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Affiliation(s)
- Celi S Andrade
- Department of Radiology, Universidade de São Paulo, São Paulo, Brazil; Division of Neurology, Department of Medicine, University of Alberta, Edmonton, AB, Canada
| | - Claudia C Leite
- Department of Radiology, Universidade de São Paulo, São Paulo, Brazil
| | - Maria C G Otaduy
- Department of Radiology, Universidade de São Paulo, São Paulo, Brazil
| | - Katarina P Lyra
- Department of Radiology, Universidade de São Paulo, São Paulo, Brazil
| | - Kette D R Valente
- Department of Psychiatry, Universidade de São Paulo, São Paulo, Brazil
| | - Clarissa L Yasuda
- Department of Neurology, Universidade de Campinas, São Paulo, Brazil; Division of Neurology, Department of Medicine, University of Alberta, Edmonton, AB, Canada
| | | | - Christian Beaulieu
- Department of Biomedical Engineering, University of Alberta, Edmonton, AB, Canada
| | - Donald W Gross
- Division of Neurology, Department of Medicine, University of Alberta, Edmonton, AB, Canada.
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24
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Besseling RMH, Jansen JFA, Overvliet GM, van der Kruijs SJM, Ebus SCM, de Louw A, Hofman PAM, Vles JSH, Aldenkamp AP, Backes WH. Reduced structural connectivity between sensorimotor and language areas in rolandic epilepsy. PLoS One 2013; 8:e83568. [PMID: 24376719 PMCID: PMC3871667 DOI: 10.1371/journal.pone.0083568] [Citation(s) in RCA: 32] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/16/2013] [Accepted: 11/12/2013] [Indexed: 12/13/2022] Open
Abstract
Introduction Rolandic epilepsy (RE) is a childhood epilepsy with centrotemporal (rolandic) spikes, that is increasingly associated with language impairment. In this study, we tested for a white matter (connectivity) correlate, employing diffusion weighted MRI and language testing. Methods Twenty-three children with RE and 23 matched controls (age: 8–14 years) underwent structural (T1-weighted) and diffusion-weighted MRI (b = 1200 s/mm2, 66 gradient directions) at 3T, as well as neuropsychological language testing. Combining tractography and a cortical segmentation derived from the T1-scan, the rolandic tract were reconstructed (pre- and postcentral gyri), and tract fractional anisotropy (FA) values were compared between patients and controls. Aberrant tracts were tested for correlations with language performance. Results Several reductions of tract FA were found in patients compared to controls, mostly in the left hemisphere; the most significant effects involved the left inferior frontal (p = 0.005) and supramarginal (p = 0.004) gyrus. In the patient group, lower tract FA values were correlated with lower language performance, among others for the connection between the left postcentral and inferior frontal gyrus (p = 0.043, R = 0.43). Conclusion In RE, structural connectivity is reduced for several connections involving the rolandic regions, from which the epileptiform activity originates. Most of these aberrant tracts involve the left (typically language mediating) hemisphere, notably the pars opercularis of the inferior frontal gyrus (Broca’s area) and the supramarginal gyrus (Wernicke’s area). For the former, reduced language performance for lower tract FA was found in the patients. These findings provide a first microstructural white matter correlate for language impairment in RE.
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Affiliation(s)
- René M. H. Besseling
- Epilepsy Center Kempenhaeghe, Heeze, the Netherlands
- Research School for Mental Health and Neuroscience, Maastricht University, Maastricht, the Netherlands
- Department of Radiology, Maastricht University Medical Center, Maastricht, the Netherlands
| | - Jacobus F. A. Jansen
- Research School for Mental Health and Neuroscience, Maastricht University, Maastricht, the Netherlands
- Department of Radiology, Maastricht University Medical Center, Maastricht, the Netherlands
| | - Geke M. Overvliet
- Epilepsy Center Kempenhaeghe, Heeze, the Netherlands
- Department of Neurology, Maastricht University Medical Center, Maastricht, the Netherlands
| | - Sylvie J. M. van der Kruijs
- Epilepsy Center Kempenhaeghe, Heeze, the Netherlands
- Research School for Mental Health and Neuroscience, Maastricht University, Maastricht, the Netherlands
| | | | - Anton de Louw
- Epilepsy Center Kempenhaeghe, Heeze, the Netherlands
- Department of Neurology, Maastricht University Medical Center, Maastricht, the Netherlands
| | - Paul A. M. Hofman
- Epilepsy Center Kempenhaeghe, Heeze, the Netherlands
- Department of Neurology, Maastricht University Medical Center, Maastricht, the Netherlands
| | - Johannes S. H. Vles
- Department of Neurology, Maastricht University Medical Center, Maastricht, the Netherlands
| | - Albert P. Aldenkamp
- Epilepsy Center Kempenhaeghe, Heeze, the Netherlands
- Department of Neurology, Maastricht University Medical Center, Maastricht, the Netherlands
| | - Walter H. Backes
- Research School for Mental Health and Neuroscience, Maastricht University, Maastricht, the Netherlands
- Department of Radiology, Maastricht University Medical Center, Maastricht, the Netherlands
- * E-mail:
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25
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Bilateral white matter abnormality in children with frontal lobe epilepsy. Epilepsy Res 2013; 108:289-94. [PMID: 24380759 DOI: 10.1016/j.eplepsyres.2013.12.001] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/14/2013] [Revised: 04/29/2013] [Accepted: 12/05/2013] [Indexed: 11/22/2022]
Abstract
In frontal lobe epilepsy (FLE), interictal discharges and seizures are more likely to spread to contralateral hemisphere and become secondarily generalized. The aim of this study was to assess white matter (WM) integrity in children with FLE using diffusion tensor imaging (DTI). Children with FLE and normal MRI, and healthy controls with no neurological or psychiatric disorders underwent DTI on 3T MRI. Whole brain fractional anisotropy (FA) and mean diffusivity (MD) maps were compared between right and left FLE with controls. 43 children with FLE, consisting of 28 left and 15 right FLE, and 44 healthy controls were recruited. Patients with left FLE had significant FA reductions in left (p=0.002) and right (p=0.003 and p=0.034) superior longitudinal fasciculi (SLF), genu/body (p=0.0002) and splenium (p=0.011) of corpus callosum. Patients with right FLE had significant FA reductions in left (p=0.016) and right (p=0.033) SLF, genu (p=0.001) and body of corpus callosum (p=0.001 and p=0.008), and significant MD elevation in right thalamus (p=0.032). There was no significant association between FA or MD and clinical seizure parameters. The abnormal WM both ipsilateral and contralateral to seizure focus may be due to seizure activity or abnormal brain development.
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Abstract
The potential utility of diffusion tensor (DT) imaging in clinical practice is broad, and new applications continue to evolve as technology advances. Clinical applications of DT imaging and tractography include tissue characterization, lesion localization, and mapping of white matter tracts. DT imaging metrics are sensitive to microstructural changes associated with central nervous system disease; however, further research is needed to enhance specificity so as to facilitate more widespread clinical application. Preoperative tract mapping, with either directionally encoded color maps or tractography, provides useful information to the neurosurgeon and has been shown to improve clinical outcomes.
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