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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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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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Chu DY, Adluru N, Nair VA, Adluru A, Choi T, Kessler-Jones A, Dabbs K, Hou J, Hermann B, Prabhakaran V, Ahmed R. Application of data harmonization and tract-based spatial statistics reveals white matter structural abnormalities in pediatric patients with focal cortical dysplasia. Epilepsy Behav 2023; 142:109190. [PMID: 37011527 PMCID: PMC10371876 DOI: 10.1016/j.yebeh.2023.109190] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 09/12/2022] [Revised: 03/16/2023] [Accepted: 03/18/2023] [Indexed: 04/05/2023]
Abstract
Our study assessed diffusion tensor imaging (DTI) metrics of fractional anisotropy (FA), mean diffusivity (MD), and radial diffusivity (RD) in pediatric subjects with epilepsy secondary to Focal Cortical Dysplasia (FCD) to improve our understanding of structural network changes associated with FCD related epilepsy. We utilized a data harmonization (DH) approach to minimize confounding effects induced by MRI protocol differences. We also assessed correlations between DTI metrics and neurocognitive measures of the fluid reasoning index (FRI), verbal comprehension index (VCI), and visuospatial index (VSI). Data (n = 51) from 23 FCD patients and 28 typically developing controls (TD) scanned clinically on either 1.5T, 3T, or 3T-wide-bore MRI were retrospectively analyzed. Tract-based spatial statistics (TBSS) with threshold-free cluster enhancement and permutation testing with 100,000 permutations were used for statistical analysis. To account for imaging protocol differences, we employed non-parametric data harmonization prior to permutation testing. Our analysis demonstrates that DH effectively removed MRI protocol-based differences typical in clinical acquisitions while preserving group differences in DTI metrics between FCD and TD subjects. Furthermore, DH strengthened the association between DTI metrics and neurocognitive indices. Fractional anisotropy, MD, and RD metrics showed stronger correlation with FRI and VSI than VCI. Our results demonstrate that DH is an integral step to reduce the confounding effect of MRI protocol differences during the analysis of white matter tracts and highlights biological differences between FCD and healthy control subjects. Characterization of white matter changes associated with FCD-related epilepsy may better inform prognosis and treatment approaches.
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Affiliation(s)
- Daniel Y Chu
- Department of Radiology, School of Medicine and Public Health, University of Wisconsin, Madison, WI, USA; Department of Neurology, School of Medicine and Public Health, University of Wisconsin, Madison, WI, USA
| | - Nagesh Adluru
- Department of Radiology, School of Medicine and Public Health, University of Wisconsin, Madison, WI, USA; Waisman Center, University of Wisconsin, Madison, WI, USA
| | - Veena A Nair
- Department of Radiology, School of Medicine and Public Health, University of Wisconsin, Madison, WI, USA
| | - Anusha Adluru
- Department of Radiology, School of Medicine and Public Health, University of Wisconsin, Madison, WI, USA
| | - Timothy Choi
- Department of Radiology, School of Medicine and Public Health, University of Wisconsin, Madison, WI, USA
| | - Alanna Kessler-Jones
- Department of Neurology, School of Medicine and Public Health, University of Wisconsin, Madison, WI, USA; Waisman Center, University of Wisconsin, Madison, WI, USA
| | - Kevin Dabbs
- Department of Neurology, School of Medicine and Public Health, University of Wisconsin, Madison, WI, USA
| | - Jiancheng Hou
- Department of Radiology, School of Medicine and Public Health, University of Wisconsin, Madison, WI, USA
| | - Bruce Hermann
- Department of Neurology, School of Medicine and Public Health, University of Wisconsin, Madison, WI, USA
| | - Vivek Prabhakaran
- Department of Radiology, School of Medicine and Public Health, University of Wisconsin, Madison, WI, USA; Department of Neurology, School of Medicine and Public Health, University of Wisconsin, Madison, WI, USA; Department of Medical Physics, School of Medicine and Public Health, University of Wisconsin, Madison, WI, USA; Department of Psychiatry, School of Medicine and Public Health, University of Wisconsin, Madison, WI, USA
| | - Raheel Ahmed
- Department of Neurological Surgery, School of Medicine and Public Health, University of Wisconsin, Madison, WI, USA.
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Lee S, Deshpande SS, Merricks EM, Schlafly E, Goodman R, McKhann GM, Eskandar EN, Madsen JR, Cash SS, van Putten MJAM, Schevon CA, van Drongelen W. Spatiotemporal spike-centered averaging reveals symmetry of temporal and spatial components of the spike-LFP relationship during human focal seizures. Commun Biol 2023; 6:317. [PMID: 36966217 PMCID: PMC10039941 DOI: 10.1038/s42003-023-04696-3] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/11/2022] [Accepted: 03/10/2023] [Indexed: 03/27/2023] Open
Abstract
The electrographic manifestation of neural activity can reflect the relationship between the faster action potentials of individual neurons and the slower fluctuations of the local field potential (LFP). This relationship is typically examined in the temporal domain using the spike-triggered average. In this study, we add a spatial component to this relationship. Here we first derive a theoretical model of the spike-LFP relationship across a macroelectrode. This mathematical derivation showed a special symmetry in the spike-LFP relationship wherein a sinc function in the temporal domain predicts a sinc function in the spatial domain. We show that this theoretical result is observed in a real-world system by characterizing the spike-LFP relationship using microelectrode array (MEA) recordings of human focal seizures. To do this, we present a approach, termed the spatiotemporal spike-centered average (st-SCA), that allows for visualization of the spike-LFP relationship in both the temporal and spatial domains. We applied this method to 25 MEA recordings obtained from seven patients with pharmacoresistant focal epilepsy. Of the five patients with MEAs implanted in recruited territory, three exhibited spatiotemporal patterns consistent with a sinc function, and two exhibited spatiotemporal patterns resembling deep wells of excitation. These results suggest that in some cases characterization of the spike-LFP relationship in the temporal domain is sufficient to predict the underlying spatial pattern. Finally, we discuss the biological interpretation of these findings and propose that the sinc function may reflect the role of mid-range excitatory connections during seizure activity.
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Affiliation(s)
- Somin Lee
- Department of Pediatrics, University of Chicago, Chicago, IL, 60637, USA
- Medical Scientist Training Program, University of Chicago, Chicago, IL, 60637, USA
| | - Sarita S Deshpande
- Department of Pediatrics, University of Chicago, Chicago, IL, 60637, USA
- Medical Scientist Training Program, University of Chicago, Chicago, IL, 60637, USA
| | - Edward M Merricks
- Department of Neurology, Columbia University, New York, NY, 10032, USA
| | - Emily Schlafly
- Graduate Program in Neuroscience, Boston University, Boston, MA, 02215, USA
| | - Robert Goodman
- Department of Neurosurgery, Lenox Hill Hospital, New York, NY, 10075, USA
| | - Guy M McKhann
- Department of Neurological Surgery, Columbia University, New York, NY, 10032, USA
| | - Emad N Eskandar
- Department of Neurosurgery, Massachusetts General Hospital and Harvard Medical School, Boston, MA, 02114, USA
- Nayef Al-Rodhan Laboratories for Cellular Neurosurgery and Neurosurgical Technology, Massachusetts General Hospital and Harvard Medical School, Boston, MA, 02114, USA
| | - Joseph R Madsen
- Department of Neurosurgery, Massachusetts General Hospital and Harvard Medical School, Boston, MA, 02114, USA
- Department of Neurosurgery, Brigham and Women's Hospital and Harvard Medical School, Boston, MA, 02115, USA
| | - Sydney S Cash
- Department of Neurology, Massachusetts General Hospital and Harvard Medical School, Boston, MA, 02114, USA
| | - Michel J A M van Putten
- Clinical Neurophysiology Group, MIRA Institute for Biomedical Engineering and Technical Medicine, University of Twente, 7500AE, Enschede, The Netherlands
| | | | - Wim van Drongelen
- Department of Pediatrics, University of Chicago, Chicago, IL, 60637, USA.
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Cohen NT, You X, Krishnamurthy M, Sepeta LN, Zhang A, Oluigbo C, Whitehead MT, Gholipour T, Baldeweg T, Wagstyl K, Adler S, Gaillard WD. Networks Underlie Temporal Onset of Dysplasia-Related Epilepsy: A MELD Study. Ann Neurol 2022; 92:503-511. [PMID: 35726354 PMCID: PMC10410674 DOI: 10.1002/ana.26442] [Citation(s) in RCA: 4] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/10/2022] [Revised: 04/22/2022] [Accepted: 06/10/2022] [Indexed: 11/11/2022]
Abstract
OBJECTIVE The purpose of this study was to evaluate if focal cortical dysplasia (FCD) co-localization to cortical functional networks is associated with the temporal distribution of epilepsy onset in FCD. METHODS International (20 center), retrospective cohort from the Multi-Centre Epilepsy Lesion Detection (MELD) project. Patients included if >3 years old, had 3D pre-operative T1 magnetic resonance imaging (MRI; 1.5 or 3 T) with radiologic or histopathologic FCD after surgery. Images processed using the MELD protocol, masked with 3D regions-of-interest (ROI), and co-registered to fsaverage_sym (symmetric template). FCDs were then co-localized to 1 of 7 distributed functional cortical networks. Negative binomial regression evaluated effect of FCD size, network, histology, and sulcal depth on age of epilepsy onset. From this model, predictive age of epilepsy onset was calculated for each network. RESULTS Three hundred eighty-eight patients had median age seizure onset 5 years (interquartile range [IQR] = 3-11 years), median age at pre-operative scan 18 years (IQR = 11-28 years). FCDs co-localized to the following networks: limbic (90), default mode (87), somatomotor (65), front parietal control (52), ventral attention (32), dorsal attention (31), and visual (31). Larger lesions were associated with younger age of onset (p = 0.01); age of epilepsy onset was associated with dominant network (p = 0.04) but not sulcal depth or histology. Sensorimotor networks had youngest onset; the limbic network had oldest age of onset (p values <0.05). INTERPRETATION FCD co-localization to distributed functional cortical networks is associated with age of epilepsy onset: sensory neural networks (somatomotor and visual) with earlier onset, and limbic latest onset. These variations may reflect developmental differences in synaptic/white matter maturation or network activation and may provide a biological basis for age-dependent epilepsy onset expression. ANN NEUROL 2022;92:503-511.
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Affiliation(s)
- Nathan T Cohen
- Center for Neuroscience Research, Children's National Hospital, The George Washington University School of Medicine, Washington, DC
| | - Xiaozhen You
- Center for Neuroscience Research, Children's National Hospital, The George Washington University School of Medicine, Washington, DC
| | - Manu Krishnamurthy
- Center for Neuroscience Research, Children's National Hospital, The George Washington University School of Medicine, Washington, DC
| | - Leigh N Sepeta
- Center for Neuroscience Research, Children's National Hospital, The George Washington University School of Medicine, Washington, DC
| | - Anqing Zhang
- Center for Neuroscience Research, Children's National Hospital, The George Washington University School of Medicine, Washington, DC
- Division of Biostatistics and Study Methodology, Children's National Research Institute, Washington, DC
| | - Chima Oluigbo
- Center for Neuroscience Research, Children's National Hospital, The George Washington University School of Medicine, Washington, DC
- Department of Neurosurgery, Children's National Hospital, The George Washington University School of Medicine, Washington, DC
| | - Matthew T Whitehead
- Center for Neuroscience Research, Children's National Hospital, The George Washington University School of Medicine, Washington, DC
- Department of Neuroradiology, Children's National Hospital, The George Washington University School of Medicine, Washington, DC
| | - Taha Gholipour
- Center for Neuroscience Research, Children's National Hospital, The George Washington University School of Medicine, Washington, DC
- George Washington University Epilepsy Center, The George Washington University School of Medicine, Washington, DC
| | - Torsten Baldeweg
- Great Ormond Street Institute for Child Health, University College of London, London, UK
| | | | - Sophie Adler
- Great Ormond Street Institute for Child Health, University College of London, London, UK
| | - William D Gaillard
- Center for Neuroscience Research, Children's National Hospital, The George Washington University School of Medicine, Washington, DC
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Jin B, Zhang Z, Wang C, Li H, Zhao X, Wang S, Chen C, He C, Zheng Y, Geng Y, Wang S, Chen G, Aung T. Focal thalamocortical circuit abnormalities in sleep related epilepsy caused by focal cortical dysplasia type II. Seizure 2022; 99:153-158. [DOI: 10.1016/j.seizure.2022.05.019] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/25/2022] [Revised: 05/23/2022] [Accepted: 05/24/2022] [Indexed: 11/26/2022] Open
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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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Lee DA, Lee HJ, Kim HC, Park KM. Alterations of structural connectivity and structural co-variance network in focal cortical dysplasia. BMC Neurol 2021; 21:330. [PMID: 34452597 PMCID: PMC8394627 DOI: 10.1186/s12883-021-02358-7] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/30/2021] [Accepted: 08/17/2021] [Indexed: 12/04/2022] Open
Abstract
Background The aim of this study was to investigate alterations in structural connectivity and structural co-variance network in patients with focal cortical dysplasia (FCD). Methods We enrolled 37 patients with FCD and 35 healthy controls. All subjects underwent brain MRI with the same scanner and with the same protocol, which included diffusion tensor imaging (DTI) and T1-weighted imaging. We analyzed the structural connectivity based on DTI, and structural co-variance network based on the structural volume with T1-weighted imaging. We created a connectivity matrix and obtained network measures from the matrix using the graph theory. We tested the difference in network measure between patients with FCD and healthy controls. Results In the structural connectivity analysis, we found that the local efficiency in patients with FCD was significantly lower than in healthy controls (2.390 vs. 2.578, p = 0.031). Structural co-variance network analysis revealed that the mean clustering coefficient, global efficiency, local efficiency, and transitivity were significantly decreased in patients with FCD compared to those in healthy controls (0.527 vs. 0.635, p = 0.036; 0.545 vs. 0.648, p = 0.026; 2.699 vs. 3.801, p = 0.019; 0.791 vs. 0.954, p = 0.026, respectively). Conclusions We demonstrate that there are significant alterations in structural connectivity, based on DTI, and structural co-variance network, based on the structural volume, in patients with FCD compared to healthy controls. These findings suggest that focal lesions with FCD could affect the whole-brain network and that FCD is a network disease.
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Affiliation(s)
- Dong Ah Lee
- Neurology Department, Haeundae Paik Hospital, Inje University College of Medicine, Haeundae-ro 875, Haeundae-gu, 48108, Busan, Korea
| | - Ho-Joon Lee
- Radiology Department, Haeundae Paik Hospital, Inje University College of Medicine, Busan, Korea
| | - Hyung Chan Kim
- Neurology Department, Haeundae Paik Hospital, Inje University College of Medicine, Haeundae-ro 875, Haeundae-gu, 48108, Busan, Korea
| | - Kang Min Park
- Neurology Department, Haeundae Paik Hospital, Inje University College of Medicine, Haeundae-ro 875, Haeundae-gu, 48108, Busan, Korea.
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Brain functional connectivity patterns in focal cortical dysplasia related epilepsy. Seizure 2021; 87:1-6. [PMID: 33636448 DOI: 10.1016/j.seizure.2021.02.009] [Citation(s) in RCA: 10] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/26/2020] [Revised: 02/05/2021] [Accepted: 02/06/2021] [Indexed: 02/05/2023] Open
Abstract
OBJECTIVE Focal cortical dysplasia (FCD) appears to be strongly associated with intractable epilepsy. Although patients with FCD are candidates for epilepsy surgery, gray matter structural abnormalities can extend beyond the primary lesion, which makes surgery less effective. The objective of this study was to evaluate functional connectivity patterns in epilepsy associated with FCD to explore the underlying pathological mechanism of this disorder. METHODS A total of 34 patients (14 men) with FCD and epilepsy [mean age ± standard deviation (SD), 24.5 ± 9.8 years; range, 8-47 years] and 34 age-matched healthy controls (14 men, 24.6 ± 9.7 years) underwent functional magnetic resonance imaging. Independent component analysis (ICA), seed-based functional connectivity, and graph theory were applied to analyze functional connectivity patterns in the brain. RESULTS Patients showed more connections among dorsal attention network, anterior default mode network, and sensorimotor brain networks than healthy controls based on ICA. Analysis of connectivity between regions of interest (ROIs) showed greater functional connectivity in patients between frontal and temporal regions, but lower connectivity between the cerebellum and frontal regions. The normalized characteristic path length was significantly higher in group of patients, but the two groups showed no significant differences in global or regional efficiency, clustering coefficient or characteristic path length. CONCLUSIONS Analysis of ICA-derived and ROI-based functional connectivity suggests that disrupted interactions and dysconnectivity in large-scale neural networks and frontotemporal-cerebellar regions may contribute to underlying pathological mechanisms in FCD-related epilepsy.
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Subramanian L, Calcagnotto ME, Paredes MF. Cortical Malformations: Lessons in Human Brain Development. Front Cell Neurosci 2020; 13:576. [PMID: 32038172 PMCID: PMC6993122 DOI: 10.3389/fncel.2019.00576] [Citation(s) in RCA: 49] [Impact Index Per Article: 12.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/10/2019] [Accepted: 12/16/2019] [Indexed: 12/11/2022] Open
Abstract
Creating a functional cerebral cortex requires a series of complex and well-coordinated developmental steps. These steps have evolved across species with the emergence of cortical gyrification and coincided with more complex behaviors. The presence of diverse progenitor cells, a protracted timeline for neuronal migration and maturation, and diverse neuronal types are developmental features that have emerged in the gyrated cortex. These factors could explain how the human brain has expanded in size and complexity. However, their complex nature also renders new avenues of vulnerability by providing additional cell types that could contribute to disease and longer time windows that could impact the composition and organization of the cortical circuit. We aim to discuss the unique developmental steps observed in human corticogenesis and propose how disruption of these species-unique processes could lead to malformations of cortical development.
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Affiliation(s)
- Lakshmi Subramanian
- Eli and Edythe Broad Center of Regeneration Medicine and Stem Cell Research, University of California, San Francisco, San Francisco, CA, United States
| | - Maria Elisa Calcagnotto
- Neurophysiology and Neurochemistry of Neuronal Excitability and Synaptic Plasticity Laboratory, Department of Biochemistry, ICBS, Universidade Federal do Rio Grande do Sul, Porto Alegre, Brazil.,Graduate Program in Biological Sciences: Biochemistry, Universidade Federal do Rio Grande do Sul, Porto Alegre, Brazil.,Graduate Program in Neuroscience, Universidade Federal do Rio Grande do Sul, Porto Alegre, Brazil
| | - Mercedes F Paredes
- Eli and Edythe Broad Center of Regeneration Medicine and Stem Cell Research, University of California, San Francisco, San Francisco, CA, United States.,Department of Neurology, University of California, San Francisco, San Francisco, CA, United States.,Neuroscience Graduate Division, University of California, San Francisco, San Francisco, CA, United States
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Zhang Y, Jiang L, Zhang D, Wang L, Fei X, Liu X, Fu X, Niu C, Wang Y, Qian R. Thalamocortical structural connectivity abnormalities in drug-resistant generalized epilepsy: A diffusion tensor imaging study. Brain Res 2020; 1727:146558. [PMID: 31794706 DOI: 10.1016/j.brainres.2019.146558] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/12/2019] [Revised: 10/25/2019] [Accepted: 11/13/2019] [Indexed: 12/14/2022]
Abstract
BACKGROUND AND PURPOSE Epilepsy is one of the most common diseases of the nervous system. Approximately one-third of epilepsy cases are drug-resistant, among which generalized-onset seizures are very common. The present study aimed to analyze abnormalities of the thalamocortical fiber pathways in each hemisphere of the brains of patients with drug-resistant generalized epilepsy. MATERIALS AND METHODS The thalamocortical structural pathways were identified by diffusion tensor imaging (DTI) in 15 patients with drug-resistant generalized epilepsy and 16 gender/age-matched controls. The thalami of both groups were parcellated into subregions according to the local thalamocortical connectivity pattern. DTI measures of thalamocortical connections were compared between the two groups. RESULTS Probabilistic tractography analyses showed that fractional anisotropy of thalamocortical pathways in patients with epilepsy decreased significantly, and the radial diffusivity of the left thalamus pathways with homolateral motor and parietal-occipital cortical regions in the drug-resistant epilepsy group increased significantly. In addition to the right thalamus pathway and prefrontal cortical region, fractional anisotropy of all other pathways was inversely correlated with disease duration. CONCLUSION The results provide evidence indicating widespread bilateral abnormalities in the thalamocortical pathways in epilepsy patients and imply that the degree of abnormality in the pathway increases with the disease duration.
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Affiliation(s)
- Yiming Zhang
- Department of Neurosurgery, The First Affiliated Hospital of USTC, Division of Life Sciences and Medicine, University of Science and Technology of China, Hefei, Anhui 230001, PR China; Anhui Provincial Hospital Affiliated to Anhui Medical University, 81 Meishan Road, Hefei, Anhui Province 230032, PR China
| | - Luwei Jiang
- Department of Neurosurgery, The First Affiliated Hospital of USTC, Division of Life Sciences and Medicine, University of Science and Technology of China, Hefei, Anhui 230001, PR China; Anhui Provincial Hospital Affiliated to Anhui Medical University, 81 Meishan Road, Hefei, Anhui Province 230032, PR China
| | - Dong Zhang
- Department of Neurosurgery, The First Affiliated Hospital of USTC, Division of Life Sciences and Medicine, University of Science and Technology of China, Hefei, Anhui 230001, PR China
| | - Lanlan Wang
- Department of Nerve Electrophysiology, The First Affiliated Hospital of USTC, Division of Life Sciences and Medicine, University of Science and Technology of China, Hefei, Anhui 230001, PR China
| | - Xiaorui Fei
- Department of Neurosurgery, The First Affiliated Hospital of USTC, Division of Life Sciences and Medicine, University of Science and Technology of China, Hefei, Anhui 230001, PR China
| | - Xiang Liu
- Anhui Provincial Institute of Stereotactic Neurosurgery, 9 Lujiang Road, Hefei, Anhui Province 230001, PR China; Department of Nerve Electrophysiology, The First Affiliated Hospital of USTC, Division of Life Sciences and Medicine, University of Science and Technology of China, Hefei, Anhui 230001, PR China
| | - Xianming Fu
- Department of Neurosurgery, The First Affiliated Hospital of USTC, Division of Life Sciences and Medicine, University of Science and Technology of China, Hefei, Anhui 230001, PR China; Anhui Provincial Institute of Stereotactic Neurosurgery, 9 Lujiang Road, Hefei, Anhui Province 230001, PR China
| | - Chaoshi Niu
- Department of Neurosurgery, The First Affiliated Hospital of USTC, Division of Life Sciences and Medicine, University of Science and Technology of China, Hefei, Anhui 230001, PR China; Anhui Provincial Institute of Stereotactic Neurosurgery, 9 Lujiang Road, Hefei, Anhui Province 230001, PR China
| | - Yehan Wang
- Department of Neurosurgery, The First Affiliated Hospital of USTC, Division of Life Sciences and Medicine, University of Science and Technology of China, Hefei, Anhui 230001, PR China; Anhui Provincial Institute of Stereotactic Neurosurgery, 9 Lujiang Road, Hefei, Anhui Province 230001, PR China
| | - Ruobing Qian
- Department of Neurosurgery, The First Affiliated Hospital of USTC, Division of Life Sciences and Medicine, University of Science and Technology of China, Hefei, Anhui 230001, PR China; Anhui Provincial Hospital Affiliated to Anhui Medical University, 81 Meishan Road, Hefei, Anhui Province 230032, PR China; Anhui Provincial Institute of Stereotactic Neurosurgery, 9 Lujiang Road, Hefei, Anhui Province 230001, PR China.
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Martire DJ, Wong S, Mikhail M, Ochi A, Otsubo H, Snead OC, Donner E, Ibrahim GM. Thalamocortical dysrhythmia in intraoperative recordings of focal epilepsy. J Neurophysiol 2019; 121:2020-2027. [DOI: 10.1152/jn.00079.2019] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
Resonant interactions between the thalamus and cortex subserve a critical role for maintenance of consciousness as well as cognitive functions. In states of abnormal thalamic inhibition, thalamocortical dysrhythmia (TCD) has been described. The characteristics of TCD include a slowing of resting oscillations, ectopic high-frequency activity, and increased cross-frequency coupling. Here, we demonstrate the presence of TCD in four patients who underwent resective epilepsy surgery with chronically implanted electrodes under anesthesia, continuously recording activity from brain regions at the periphery of the epileptogenic zone before and after resection. Following resection, we report an acceleration of the large-scale network resting frequency coincident with decreases in cross-frequency phase-amplitude coupling. Interregional functional connectivity in the surrounding cortex was also increased following resection of the epileptogenic focus. These findings provide evidence for the presence of TCD in focal epilepsy and highlight the importance of reciprocal thalamocortical oscillatory interactions in defining novel biomarkers for resective surgeries. NEW & NOTEWORTHY Thalamocortical dysrhythmia (TCD) occurs in the context of thalamic dysfacilitation and is characterized by slowing of resting oscillations, ectopic high-frequency activity, and cross-frequency coupling. We provide evidence for TCD in focal epilepsy by studying electrophysiological changes occurring at the periphery of the resection margin. We report acceleration of resting activity coincident with decreased cross-frequency coupling and increased functional connectivity. The study of TCD in epilepsy has implications as a biomarker and therapeutic target.
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Affiliation(s)
- Daniel J. Martire
- Program in Neuroscience and Mental Health, Hospital for Sick Children Research Institute, Toronto, Ontario, Canada
| | - Simeon Wong
- Program in Neuroscience and Mental Health, Hospital for Sick Children Research Institute, Toronto, Ontario, Canada
- Institute of Biomaterials and Biomedical Engineering, University of Toronto, Toronto, Ontario, Canada
| | - Mirriam Mikhail
- Faculty of Medicine, University of Toronto, Toronto, Ontario, Canada
| | - Ayako Ochi
- Division of Neurology, Hospital for Sick Children, Toronto, Ontario, Canada
| | - Hiroshi Otsubo
- Division of Neurology, Hospital for Sick Children, Toronto, Ontario, Canada
| | - O. Carter Snead
- Division of Neurology, Hospital for Sick Children, Toronto, Ontario, Canada
| | - Elizabeth Donner
- Division of Neurology, Hospital for Sick Children, Toronto, Ontario, Canada
| | - George M. Ibrahim
- Program in Neuroscience and Mental Health, Hospital for Sick Children Research Institute, Toronto, Ontario, Canada
- Institute of Biomaterials and Biomedical Engineering, University of Toronto, Toronto, Ontario, Canada
- Division of Neurosurgery, Hospital for Sick Children, Department of Surgery, University of Toronto, Toronto, Ontario, Canada
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Tavakol S, Royer J, Lowe AJ, Bonilha L, Tracy JI, Jackson GD, Duncan JS, Bernasconi A, Bernasconi N, Bernhardt BC. Neuroimaging and connectomics of drug-resistant epilepsy at multiple scales: From focal lesions to macroscale networks. Epilepsia 2019; 60:593-604. [PMID: 30889276 PMCID: PMC6447443 DOI: 10.1111/epi.14688] [Citation(s) in RCA: 79] [Impact Index Per Article: 15.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/07/2019] [Revised: 02/13/2019] [Accepted: 02/14/2019] [Indexed: 01/03/2023]
Abstract
Epilepsy is among the most common chronic neurologic disorders, with 30%-40% of patients having seizures despite antiepileptic drug treatment. The advent of brain imaging and network analyses has greatly improved the understanding of this condition. In particular, developments in magnetic resonance imaging (MRI) have provided measures for the noninvasive characterization and detection of lesions causing epilepsy. MRI techniques can probe structural and functional connectivity, and network analyses have shaped our understanding of whole-brain anomalies associated with focal epilepsies. This review considers the progress made by neuroimaging and connectomics in the study of drug-resistant epilepsies due to focal substrates, particularly temporal lobe epilepsy related to mesiotemporal sclerosis and extratemporal lobe epilepsies associated with malformations of cortical development. In these disorders, there is evidence of widespread disturbances of structural and functional connectivity that may contribute to the clinical and cognitive prognosis of individual patients. It is hoped that studying the interplay between macroscale network anomalies and lesional profiles will improve our understanding of focal epilepsies and assist treatment choices.
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Affiliation(s)
- Shahin Tavakol
- Multimodal Imaging and Connectome Analysis Lab, McConnell Brain Imaging Centre, Montreal Neurological Institute and Hospital, McGill University, Montreal, Quebec, Canada
| | - Jessica Royer
- Multimodal Imaging and Connectome Analysis Lab, McConnell Brain Imaging Centre, Montreal Neurological Institute and Hospital, McGill University, Montreal, Quebec, Canada
| | - Alexander J Lowe
- Multimodal Imaging and Connectome Analysis Lab, McConnell Brain Imaging Centre, Montreal Neurological Institute and Hospital, McGill University, Montreal, Quebec, Canada
| | - Leonardo Bonilha
- Department of Neurology, Medical University of South Carolina, Charleston, South Carolina
| | - Joseph I Tracy
- Cognitive Neuroscience and Brain Mapping Laboratory, Thomas Jefferson University Hospitals/Sidney Kimmel Medical College, Philadelphia, Pennsylvania
| | - Graeme D Jackson
- Florey Institute of Neuroscience and Mental Health, University of Melbourne, Melbourne, Victoria, Australia
| | | | - Andrea Bernasconi
- Neuroimaging of Epilepsy Laboratory, McConnell Brain Imaging Centre, Montreal Neurological Institute and Hospital, McGill University, Montreal, Quebec, Canada
| | - Neda Bernasconi
- Neuroimaging of Epilepsy Laboratory, McConnell Brain Imaging Centre, Montreal Neurological Institute and Hospital, McGill University, Montreal, Quebec, Canada
| | - Boris C Bernhardt
- Multimodal Imaging and Connectome Analysis Lab, McConnell Brain Imaging Centre, Montreal Neurological Institute and Hospital, McGill University, Montreal, Quebec, Canada
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