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Fleury MN, Binding LP, Taylor P, Xiao F, Giampiccolo D, Caciagli L, Buck S, Winston GP, Thompson PJ, Baxendale S, Koepp MJ, Duncan JS, Sidhu MK. Predictors of long-term memory and network connectivity 10 years after anterior temporal lobe resection. Epilepsia 2024. [PMID: 38990127 DOI: 10.1111/epi.18058] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/01/2024] [Revised: 06/25/2024] [Accepted: 06/25/2024] [Indexed: 07/12/2024]
Abstract
OBJECTIVE Anterior temporal lobe resection (ATLR) effectively controls seizures in medically refractory temporal lobe epilepsy but risks significant episodic memory decline. Beyond 1 year postoperatively, the influence of preoperative clinical factors on episodic memory and long-term network plasticity remain underexplored. Ten years post-ATLR, we aimed to determine biomarkers of successful memory network reorganization and establish presurgical features' lasting impact on memory function. METHODS Twenty-five ATLR patients (12 left-sided) and 10 healthy controls underwent a memory-encoding functional magnetic resonance imaging paradigm alongside neuropsychometry 10 years postsurgery. Generalized psychophysiological interaction analyses modeled network functional connectivity of words/faces remembered, seeding from the medial temporal lobes (MTLs). Differences in successful memory connectivity were assessed between controls and left/right ATLR. Multivariate regressions and mixed-effect models probed preoperative phenotypes' effects on long-term memory outcomes. RESULTS Ten years post-ATLR, lower baseline functioning (verbal and performance intelligence quotient) and a focal memory impairment preoperatively predicted worse long-term memory outcomes. Poorer verbal memory was significantly associated with longer epilepsy duration and earlier onset age. Relative to controls, successful word and face encoding involved increased functional connectivity from both or remnant MTL seeds and contralesional parahippocampus/hippocampus after left/right ATLR. Irrespective of surgical laterality, successful memory encoding correlated with increased MTL-seeded connectivity to frontal (bilateral insula, right anterior cingulate), right parahippocampal, and bilateral fusiform gyri. Ten years postsurgery, better memory performance was correlated with contralateral frontal plasticity, which was disrupted with longer epilepsy duration. SIGNIFICANCE Our findings underscore the enduring nature of functional network reorganizations to provide long-term cognitive support. Ten years post-ATLR, successful memory formation featured stronger connections near resected areas and contralateral regions. Preoperative network disruption possibly influenced effectiveness of postoperative plasticity. These findings are crucial for enhancing long-term memory prediction and strategies for lasting memory rehabilitation.
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Affiliation(s)
- Marine N Fleury
- Department of Clinical and Experimental Epilepsy, UCL Queen Square Institute of Neurology, London, UK
- MRI Unit, Epilepsy Society, Buckinghamshire, UK
| | - Lawrence P Binding
- Department of Clinical and Experimental Epilepsy, UCL Queen Square Institute of Neurology, London, UK
- MRI Unit, Epilepsy Society, Buckinghamshire, UK
- Department of Computer Science, UCL Centre for Medical Image Computing, London, UK
| | - Peter Taylor
- Department of Clinical and Experimental Epilepsy, UCL Queen Square Institute of Neurology, London, UK
- CNNP Lab, Interdisciplinary Computing and Complex BioSystems Group, School of Computing Science, Newcastle University, Newcastle, UK
| | - Fenglai Xiao
- Department of Clinical and Experimental Epilepsy, UCL Queen Square Institute of Neurology, London, UK
- MRI Unit, Epilepsy Society, Buckinghamshire, UK
| | - Davide Giampiccolo
- Department of Clinical and Experimental Epilepsy, UCL Queen Square Institute of Neurology, London, UK
- Victor Horsley Department of Neurosurgery, National Hospital for Neurology and Neurosurgery, Queen Square, London, UK
- Department of Neurosurgery, Institute of Neurosciences, Cleveland Clinic London, London, UK
| | - Lorenzo Caciagli
- Department of Clinical and Experimental Epilepsy, UCL Queen Square Institute of Neurology, London, UK
- MRI Unit, Epilepsy Society, Buckinghamshire, UK
- Department of Neurology, Inselspital, Sleep-Wake-Epilepsy Center, Bern University Hospital, University of Bern, Bern, Switzerland
| | - Sarah Buck
- Department of Clinical and Experimental Epilepsy, UCL Queen Square Institute of Neurology, London, UK
- MRI Unit, Epilepsy Society, Buckinghamshire, UK
| | - Gavin P Winston
- Department of Clinical and Experimental Epilepsy, UCL Queen Square Institute of Neurology, London, UK
- MRI Unit, Epilepsy Society, Buckinghamshire, UK
- Division of Neurology, Department of Medicine, Queen's University, Kingston, Ontario, Canada
| | - Pamela J Thompson
- Department of Clinical and Experimental Epilepsy, UCL Queen Square Institute of Neurology, London, UK
- Psychology Department, Epilepsy Society, Buckinghamshire, UK
| | - Sallie Baxendale
- Department of Clinical and Experimental Epilepsy, UCL Queen Square Institute of Neurology, London, UK
- Psychology Department, Epilepsy Society, Buckinghamshire, UK
| | - Matthias J Koepp
- Department of Clinical and Experimental Epilepsy, UCL Queen Square Institute of Neurology, London, UK
- MRI Unit, Epilepsy Society, Buckinghamshire, UK
| | - John S Duncan
- Department of Clinical and Experimental Epilepsy, UCL Queen Square Institute of Neurology, London, UK
- MRI Unit, Epilepsy Society, Buckinghamshire, UK
| | - Meneka K Sidhu
- Department of Clinical and Experimental Epilepsy, UCL Queen Square Institute of Neurology, London, UK
- MRI Unit, Epilepsy Society, Buckinghamshire, UK
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González HFJ, Narasimhan S, Goodale SE, Johnson GW, Doss DJ, Paulo DL, Morgan VL, Chang C, Englot DJ. Arousal and salience network connectivity alterations in surgical temporal lobe epilepsy. J Neurosurg 2023; 138:810-820. [PMID: 35901709 PMCID: PMC10127440 DOI: 10.3171/2022.5.jns22837] [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: 04/09/2022] [Accepted: 05/12/2022] [Indexed: 11/06/2022]
Abstract
OBJECTIVE It is poorly understood why patients with mesial temporal lobe epilepsy (TLE) have cognitive deficits and brain network changes that extend beyond the temporal lobe, including altered extratemporal intrinsic connectivity networks (ICNs). However, subcortical arousal structures project broadly to the neocortex, are affected by TLE, and thus may contribute to these widespread network effects. The authors' objective was to examine functional connectivity (FC) patterns between subcortical arousal structures and neocortical ICNs, possible neurocognitive relationships, and FC changes after epilepsy surgery. METHODS The authors obtained resting-state functional magnetic resonance imaging (fMRI) in 50 adults with TLE and 50 controls. They compared nondirected FC (correlation) and directed FC (Granger causality laterality index) within the salience network, default mode network, and central executive network, as well as between subcortical arousal structures; these 3 ICNs were also compared between patients and controls. They also used an fMRI-based vigilance index to relate alertness to arousal center FC. Finally, fMRI was repeated in 29 patients > 12 months after temporal lobe resection. RESULTS Nondirected FC within the salience (p = 0.042) and default mode (p = 0.0008) networks, but not the central executive network (p = 0.79), was decreased in patients in comparison with controls (t-tests, corrected). Nondirected FC between the salience network and subcortical arousal structures (nucleus basalis of Meynert, thalamic centromedian nucleus, and brainstem pedunculopontine nucleus) was reduced in patients in comparison with controls (p = 0.0028-0.015, t-tests, corrected), and some of these connectivity abnormalities were associated with lower processing speed index, verbal comprehension, and full-scale IQ. Interestingly, directed connectivity measures suggested a loss of top-down influence from the salience network to the arousal nuclei in patients. After resection, certain FC patterns between the arousal nuclei and salience network moved toward control values in the patients, suggesting that some postoperative recovery may be possible. Although an fMRI-based vigilance measure suggested that patients exhibited reduced alertness over time, FC abnormalities between the salience network and arousal structures were not influenced by the alertness levels during the scans. CONCLUSIONS FC abnormalities between subcortical arousal structures and ICNs, such as the salience network, may be related to certain neurocognitive deficits in TLE patients. Although TLE patients demonstrated vigilance abnormalities, baseline FC perturbations between the arousal and salience networks are unlikely to be driven solely by alertness level, and some may improve after surgery. Examination of the arousal network and ICN disturbances may improve our understanding of the downstream clinical effects of TLE.
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Affiliation(s)
- Hernán F. J. González
- Department of Biomedical Engineering, Vanderbilt University, Nashville, Tennessee
- Vanderbilt University Institute of Imaging Science, Vanderbilt University Medical Center, Nashville, Tennessee
| | - Saramati Narasimhan
- Department of Neurological Surgery, Vanderbilt University Medical Center, Nashville, Tennessee
- Vanderbilt University Institute of Imaging Science, Vanderbilt University Medical Center, Nashville, Tennessee
| | - Sarah E. Goodale
- Department of Biomedical Engineering, Vanderbilt University, Nashville, Tennessee
- Vanderbilt University Institute of Imaging Science, Vanderbilt University Medical Center, Nashville, Tennessee
| | - Graham W. Johnson
- Department of Biomedical Engineering, Vanderbilt University, Nashville, Tennessee
- Vanderbilt University Institute of Imaging Science, Vanderbilt University Medical Center, Nashville, Tennessee
| | - Derek J. Doss
- Department of Biomedical Engineering, Vanderbilt University, Nashville, Tennessee
- Vanderbilt University Institute of Imaging Science, Vanderbilt University Medical Center, Nashville, Tennessee
| | - Danika L. Paulo
- Department of Neurological Surgery, Vanderbilt University Medical Center, Nashville, Tennessee
| | - Victoria L. Morgan
- Department of Biomedical Engineering, Vanderbilt University, Nashville, Tennessee
- Department of Neurological Surgery, Vanderbilt University Medical Center, Nashville, Tennessee
- Departments of Radiology and Radiological Sciences, Vanderbilt University Medical Center, Nashville, Tennessee
- Vanderbilt University Institute of Imaging Science, Vanderbilt University Medical Center, Nashville, Tennessee
| | - Catie Chang
- Department of Biomedical Engineering, Vanderbilt University, Nashville, Tennessee
- Departments of Electrical Engineering and Computer Science, Vanderbilt University, Nashville, Tennessee
- Vanderbilt University Institute of Imaging Science, Vanderbilt University Medical Center, Nashville, Tennessee
| | - Dario J. Englot
- Department of Biomedical Engineering, Vanderbilt University, Nashville, Tennessee
- Departments of Electrical Engineering and Computer Science, Vanderbilt University, Nashville, Tennessee
- Department of Neurological Surgery, Vanderbilt University Medical Center, Nashville, Tennessee
- Departments of Radiology and Radiological Sciences, Vanderbilt University Medical Center, Nashville, Tennessee
- Vanderbilt University Institute of Imaging Science, Vanderbilt University Medical Center, Nashville, Tennessee
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Altered Resting State Networks Before and After Temporal Lobe Epilepsy Surgery. Brain Topogr 2022; 35:692-701. [PMID: 36074203 DOI: 10.1007/s10548-022-00912-1] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/22/2022] [Accepted: 08/27/2022] [Indexed: 11/02/2022]
Abstract
OBJECTIVES To explore the resting state networks (RSNs) alterations in patients with unilateral mesial temporal lobe epilepsy (mTLE) before and after successful surgery. METHODS Resting-state functional MRI and T1-weighted structural MRI were obtained in 37 mTLE patients who achieved seizure freedom after anterior temporal lobectomy. Patients were scanned before surgery and at two years after surgery. Twenty-eight age- and sex-matched healthy controls were scanned once. Functional connectivity (FC) changes within and between ten common RSNs before and after surgery, and FC changes between hippocampus and RSNs were explored. RESULTS Before surgery, decreased FC was found within visual network and basal ganglia network, while after surgery, FC within basal ganglia network further decreased but FC within sensorimotor network and dorsal attention network increased. Before surgery, between-network FC related to basal ganglia network, visual network and dorsal attention network decreased, while between-network FC related to default mode network increased. After surgery, between-network FC related to visual network and dorsal attention network significantly increased. In addition, before surgery, ipsilateral hippocampus showed decreased FC with visual network, basal ganglia network, sensorimotor network, default mode network and frontoparietal network, while contralateral rostral hippocampus showed increased FC with salience network. After surgery, no obvious FC changes were found between contralateral hippocampus and these RSNs. CONCLUSION MTLE patients showed significant RSNs alterations before and after surgery. Basal ganglia network showed progressive decline in functional connectivity. Successful surgery may lead to RSNs reorganization. These results provide preliminary evidence for postoperative functional remodeling at whole-brain-network level.
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Sinha N, Johnson GW, Davis KA, Englot DJ. Integrating Network Neuroscience Into Epilepsy Care: Progress, Barriers, and Next Steps. Epilepsy Curr 2022; 22:272-278. [PMID: 36285209 PMCID: PMC9549227 DOI: 10.1177/15357597221101271] [Citation(s) in RCA: 17] [Impact Index Per Article: 8.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/17/2022] Open
Abstract
Drug resistant epilepsy is a disorder involving widespread brain network
alterations. Recently, many groups have reported neuroimaging and
electrophysiology network analysis techniques to aid medical
management, support presurgical planning, and understand postsurgical
seizure persistence. While these approaches may supplement standard
tests to improve care, they are not yet used clinically or influencing
medical or surgical decisions. When will this change? Which approaches
have shown the most promise? What are the barriers to translating them
into clinical use? How do we facilitate this transition? In this
review, we will discuss progress, barriers, and next steps regarding
the integration of brain network analysis into the medical and
presurgical pipeline.
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Affiliation(s)
- Nishant Sinha
- Center for Neuroengineering and Therapeutics, University of Pennsylvania, Philadelphia PA, USA
- Department of Neurology, Penn Epilepsy Center, Hospital of the University of Pennsylvania, Philadelphia, PA, USA
| | - Graham W. Johnson
- Department of Biomedical Engineering, Vanderbilt University, Nashville, TN, USA
- Vanderbilt University Institute of Imaging Science at Vanderbilt University Medical Center, Nashville, TN, USA
| | - Kathryn A. Davis
- Center for Neuroengineering and Therapeutics, University of Pennsylvania, Philadelphia PA, USA
- Department of Neurology, Penn Epilepsy Center, Hospital of the University of Pennsylvania, Philadelphia, PA, USA
| | - Dario J. Englot
- Department of Biomedical Engineering, Vanderbilt University, Nashville, TN, USA
- Vanderbilt University Institute of Imaging Science at Vanderbilt University Medical Center, Nashville, TN, USA
- Department of Neurological Surgery, Vanderbilt University Medical Center, Nashville, TN, USA
- Department of Neurology, Vanderbilt University Medical Center, Nashville, TN, USA
- Department of Radiology and Radiological Sciences, Vanderbilt University Medical Center, Nashville, TN, USA
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Luckett PH, Maccotta L, Lee JJ, Park KY, Dosenbach NU, Ances BM, Hogan RE, Shimony JS, Leuthardt EC. Deep learning resting state fMRI lateralization of temporal lobe epilepsy. Epilepsia 2022; 63:1542-1552. [PMID: 35320587 DOI: 10.1111/epi.17233] [Citation(s) in RCA: 11] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/02/2022] [Revised: 03/21/2022] [Accepted: 03/21/2022] [Indexed: 11/29/2022]
Abstract
OBJECTIVE Localization of focal epilepsy is critical for surgical treatment of refractory seizures. There remains a great need for non-invasive techniques to localize seizures for surgical decision-making. We investigate the use of deep learning using resting state functional MRI (RS-fMRI) to identify the hemisphere of seizure onset in temporal lobe epilepsy (TLE) patients. METHODS 2132 healthy controls and 32 pre-operative TLE patients were studied. All participants underwent structural MRI and RS-fMRI. Healthy control data was used to generate training samples for a 3D convolutional neural network (3DCNN). RS-fMRI was synthetically altered in randomly lateralized regions in the healthy control participants. The model was then trained to classify the hemisphere containing synthetic noise. Finally, the model was tested on TLE patients to assess its performance for detecting biological seizure-onset zones, and gradient-weighted class activation mapping (Grad-CAM) identified the strongest predictive regions. RESULTS The 3DCNN classified healthy control hemispheres known to contain synthetic noise with 96% accuracy, and TLE hemispheres clinically identified to be seizure onset zones with 90.6% accuracy. Grad-CAM identified a range of temporal, frontal, parietal, and subcortical regions that were strong anatomical predictors of the seizure onset zone, while the resting state networks which colocalized with Grad-CAM results included default mode, medial temporal, and dorsal attention networks. Lastly, in an analysis of a subset of patients with post-surgical outcomes, the 3DCNN leveraged a more focal set of regions to achieve classification in patients with Engel class > 1 compared to Engel class 1. SIGNIFICANCE Non-invasive techniques capable of localizing the seizure-onset zone could improve pre-surgical planning in patients with intractable epilepsy. We have demonstrated the ability of deep learning to identify the correct hemisphere of the seizure onset zone in TLE patients using RS-fMRI with high accuracy. This approach represents a novel technique of seizure lateralization that could improve preoperative surgical planning.
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Affiliation(s)
- Patrick H Luckett
- Department of Neurological Surgery, Washington University School of Medicine, St. Louis
| | - Luigi Maccotta
- Department of Neurology, Washington University School of Medicine, St. Louis
| | - John J Lee
- Mallinckrodt Institute of Radiology, Washington University School of Medicine, St. Louis
| | - Ki Yun Park
- Department of Neurological Surgery, Washington University School of Medicine, St. Louis
| | - Nico Uf Dosenbach
- Department of Neurology, Washington University School of Medicine, St. Louis
| | - Beau M Ances
- Department of Neurology, Washington University School of Medicine, St. Louis
| | - R Edward Hogan
- Department of Neurology, Washington University School of Medicine, St. Louis
| | - Joshua S Shimony
- Mallinckrodt Institute of Radiology, Washington University School of Medicine, St. Louis
| | - Eric C Leuthardt
- Department of Neurological Surgery, Washington University School of Medicine, St. Louis
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Bandopadhyay R, Singh T, Ghoneim MM, Alshehri S, Angelopoulou E, Paudel YN, Piperi C, Ahmad J, Alhakamy NA, Alfaleh MA, Mishra A. Recent Developments in Diagnosis of Epilepsy: Scope of MicroRNA and Technological Advancements. BIOLOGY 2021; 10:1097. [PMID: 34827090 PMCID: PMC8615191 DOI: 10.3390/biology10111097] [Citation(s) in RCA: 14] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 09/27/2021] [Revised: 10/21/2021] [Accepted: 10/21/2021] [Indexed: 12/18/2022]
Abstract
Epilepsy is one of the most common neurological disorders, characterized by recurrent seizures, resulting from abnormally synchronized episodic neuronal discharges. Around 70 million people worldwide are suffering from epilepsy. The available antiepileptic medications are capable of controlling seizures in around 60-70% of patients, while the rest remain refractory. Poor seizure control is often associated with neuro-psychiatric comorbidities, mainly including memory impairment, depression, psychosis, neurodegeneration, motor impairment, neuroendocrine dysfunction, etc., resulting in poor prognosis. Effective treatment relies on early and correct detection of epileptic foci. Although there are currently a few well-established diagnostic techniques for epilepsy, they lack accuracy and cannot be applied to patients who are unsupportive or harbor metallic implants. Since a single test result from one of these techniques does not provide complete information about the epileptic foci, it is necessary to develop novel diagnostic tools. Herein, we provide a comprehensive overview of the current diagnostic tools of epilepsy, including electroencephalography (EEG) as well as structural and functional neuroimaging. We further discuss recent trends and advances in the diagnosis of epilepsy that will enable more effective diagnosis and clinical management of patients.
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Affiliation(s)
- Ritam Bandopadhyay
- Department of Pharmacology, School of Pharmaceutical Sciences, Lovely Professional University, Phagwara 144411, Punjab, India;
| | - Tanveer Singh
- Department of Neuroscience and Experimental Therapeutics, College of Medicine, Texas A&M University Health Science Center, Bryan, TX 77807, USA;
| | - Mohammed M. Ghoneim
- Department of Pharmacy Practice, College of Pharmacy, AlMaarefa University, Ad Diriyah 13713, Saudi Arabia;
| | - Sultan Alshehri
- Department of Pharmaceutics, College of Pharmacy, King Saud University, Riyadh 11451, Saudi Arabia;
| | - Efthalia Angelopoulou
- Department of Biological Chemistry, Medical School, National and Kapodistrian University of Athens, 11527 Athens, Greece; (E.A.); (C.P.)
| | - Yam Nath Paudel
- Neuropharmacology Research Strength, Jeffrey Cheah School of Medicine and Health Sciences, Monash University Malaysia, Bandar Sunway, Subang Jaya 47500, Selangor, Malaysia;
| | - Christina Piperi
- Department of Biological Chemistry, Medical School, National and Kapodistrian University of Athens, 11527 Athens, Greece; (E.A.); (C.P.)
| | - Javed Ahmad
- Department of Pharmaceutics, College of Pharmacy, Najran University, Najran 11001, Saudi Arabia;
| | - Nabil A. Alhakamy
- Department of Pharmaceutics, Faculty of Pharmacy, King Abdulaziz University, Jeddah 21589, Saudi Arabia; (N.A.A.); (M.A.A.)
| | - Mohamed A. Alfaleh
- Department of Pharmaceutics, Faculty of Pharmacy, King Abdulaziz University, Jeddah 21589, Saudi Arabia; (N.A.A.); (M.A.A.)
- Vaccines and Immunotherapy Unit, King Fahd Medical Research Center, King Abdulaziz University, Jeddah 21589, Saudi Arabia
| | - Awanish Mishra
- Department of Pharmacology, School of Pharmaceutical Sciences, Lovely Professional University, Phagwara 144411, Punjab, India;
- Department of Pharmacology and Toxicology, National Institute of Pharmaceutical Education and Research (NIPER)—Guwahati, Changsari, Guwahati 781101, Assam, India
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de Bézenac CE, Adan G, Weber B, Keller SS. Association of Epilepsy Surgery With Changes in Imaging-Defined Brain Age. Neurology 2021; 97:e554-e563. [PMID: 34261787 PMCID: PMC8424496 DOI: 10.1212/wnl.0000000000012289] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/11/2020] [Accepted: 05/03/2021] [Indexed: 11/15/2022] Open
Abstract
Objective To determine whether surgery in patients with mesial temporal lobe epilepsy (mTLE) is associated with reduced brain-predicted age as a neural marker overall brain health, we compared brain-predicted and chronologic age difference (brain age gap estimation [BrainAGE]) in patients before and after surgery with healthy controls. Methods We acquired 3D T1-weighted MRI scans for 48 patients with mTLE before and after temporal lobe surgery to estimate brain age using a gaussian processes regression model. We examined BrainAGE before and after surgery controlling for brain volume change, comparing patients to 37 age- and sex-matched controls. Results Preoperatively, patients showed an increased BrainAGE of more than 7 years compared to controls. However, surgery was associated with a mean BrainAGE reduction of 5 years irrespective of whether or not surgery resulted in complete seizure freedom. We observed a lateralization effect as patients with left mTLE had BrainAGE values that more closely resembled control group values following surgery. Conclusions Our findings suggest that while morphologic brain alterations linked to accelerated aging have been observed in mTLE, surgery may be associated with changes that reverse such alterations in some patients. This work highlights the advantages of resective surgery on overall brain health in patients with refractory focal epilepsy.
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Affiliation(s)
- Christophe E de Bézenac
- From the Department of Pharmacology and Therapeutics (C.E.d.B., G.A., S.S.K.), Institute of Systems, Molecular and Integrative Biology, University of Liverpool; The Walton Centre NHS Foundation Trust (C.E.d.B., G.A., S.S.K.), Liverpool, UK; and Institute of Experimental Epileptology and Cognition Research (B.W.), University of Bonn, Germany.
| | - Guleed Adan
- From the Department of Pharmacology and Therapeutics (C.E.d.B., G.A., S.S.K.), Institute of Systems, Molecular and Integrative Biology, University of Liverpool; The Walton Centre NHS Foundation Trust (C.E.d.B., G.A., S.S.K.), Liverpool, UK; and Institute of Experimental Epileptology and Cognition Research (B.W.), University of Bonn, Germany
| | - Bernd Weber
- From the Department of Pharmacology and Therapeutics (C.E.d.B., G.A., S.S.K.), Institute of Systems, Molecular and Integrative Biology, University of Liverpool; The Walton Centre NHS Foundation Trust (C.E.d.B., G.A., S.S.K.), Liverpool, UK; and Institute of Experimental Epileptology and Cognition Research (B.W.), University of Bonn, Germany
| | - Simon S Keller
- From the Department of Pharmacology and Therapeutics (C.E.d.B., G.A., S.S.K.), Institute of Systems, Molecular and Integrative Biology, University of Liverpool; The Walton Centre NHS Foundation Trust (C.E.d.B., G.A., S.S.K.), Liverpool, UK; and Institute of Experimental Epileptology and Cognition Research (B.W.), University of Bonn, Germany
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Network differences based on arterial spin labeling related to anti-seizure medication response in focal epilepsy. Neuroradiology 2021; 64:313-321. [PMID: 34251501 DOI: 10.1007/s00234-021-02741-8] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/08/2021] [Accepted: 05/30/2021] [Indexed: 10/20/2022]
Abstract
PURPOSE The aim of this study was to determine whether anti-seizure medication (ASM) response is associated with structural connectivity in diffusion tensor imaging (DTI) or functional co-variance network in arterial spin labeling (ASL) magnetic resonance imaging (MRI) in patients with focal epilepsy. METHODS In this retrospective study conducted at a tertiary hospital, we enrolled 105 patients with focal epilepsy, of which 64 patients were good ASM responders, and 41 patients were poor ASM responders. All patients showed normal MRI findings on visual inspection and underwent DTI and ASL MRI from August 2018 to July 2020, with regular follow-up for at least 12 months after epilepsy diagnosis while taking ASMs. We calculated the structural connectivity based on DTI and functional co-variance network based on ASL MRI by using graph theory and analyzed their differences in relation to the ASM response. RESULTS No differences were observed in structural connectivity between the good and poor ASM responders. However, significant differences were observed in functional co-variance network between the good and poor ASM responders. In comparison with good ASM responders, poor ASM responders showed a significantly greater characteristic path length (2.557 vs. 1.753, p = 0.034) and a lower local efficiency (2.311 vs. 3.927, p = 0.048). CONCLUSION Significant differences were observed in functional co-variance network based on ASL MRI between the good and poor ASM responders. These findings suggest that functional co-variance network could serve as a new biomarker of ASM response in focal epilepsy.
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Li W, Jiang Y, Qin Y, Zhou B, Lei D, Luo C, Zhang H, Gong Q, Zhou D, An D. Dynamic gray matter and intrinsic activity changes after epilepsy surgery. Acta Neurol Scand 2021; 143:261-270. [PMID: 33058145 DOI: 10.1111/ane.13361] [Citation(s) in RCA: 7] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/12/2020] [Revised: 09/20/2020] [Accepted: 10/05/2020] [Indexed: 02/05/2023]
Abstract
OBJECTIVES To explore the dynamic changes of gray matter volume and intrinsic brain activity following anterior temporal lobectomy (ATL) in patients with unilateral mesial temporal lobe epilepsy (mTLE) who achieved seizure-free for 2 years. MATERIALS AND METHODS High-resolution T1-weighted MRI and resting-state functional MRI data were obtained in ten mTLE patients at five serial timepoints: before surgery, 3, 6, 12, and 24 months after surgery. The gray matter volume (GMV) and amplitude of low-frequency fluctuations (ALFF) were compared among the five scans to depict the dynamic changes after ATL. RESULTS After successful ATL, GMV decreased in several ipsilateral brain regions: ipsilateral insula, thalamus, and putamen showed gradual gray matter atrophy from 3 to 24 months, while ipsilateral superior temporal gyrus, middle temporal gyrus, inferior temporal gyrus, middle occipital gyrus, inferior occipital gyrus, caudate nucleus, lingual gyrus, and fusiform gyrus showed significant GMV decrease at 3 months follow-up, without further changes. Ipsilateral insula showed gradual ALFF decrease from 3 to 24 months after surgery. Ipsilateral superior temporal gyrus showed ALFF decrease at 3 months follow-up, without further changes. Ipsilateral thalamus and cerebellar vermis showed obvious ALFF increase after surgery. CONCLUSIONS Surgical resection may lead to a short-term reduction of gray matter volume and intrinsic brain activity in neighboring regions, while the progressive gray matter atrophy may be due to possible intrinsic mechanism of mTLE. Dynamic ALFF changes provide evidence that disrupted focal spontaneous activities were reorganized after successful surgery.
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Affiliation(s)
- Wei Li
- Department of Neurology West China Hospital Sichuan University Chengdu China
| | - Yuchao Jiang
- The Clinical Hospital of Chengdu Brain Science Institute MOE Key Lab for Neuroinformation Center for Information in Medicine School of life Science and technology University of Electronic Science and Technology of China Chengdu China
| | - Yingjie Qin
- Department of Neurology West China Hospital Sichuan University Chengdu China
| | - Baiwan Zhou
- Department of Radiology Huaxi MR Research Center West China Hospital Sichuan University Chengdu China
| | - Du Lei
- Department of Radiology Huaxi MR Research Center West China Hospital Sichuan University Chengdu China
| | - Cheng Luo
- The Clinical Hospital of Chengdu Brain Science Institute MOE Key Lab for Neuroinformation Center for Information in Medicine School of life Science and technology University of Electronic Science and Technology of China Chengdu China
- Research Unit of NeuroInformation Chinese Academy of Medical Sciences Chengdu China
| | - Heng Zhang
- Department of Neurosurgery West China Hospital Sichuan University Chengdu China
| | - Qiyong Gong
- Department of Radiology Huaxi MR Research Center West China Hospital Sichuan University Chengdu China
| | - Dong Zhou
- Department of Neurology West China Hospital Sichuan University Chengdu China
| | - Dongmei An
- Department of Neurology West China Hospital Sichuan University Chengdu China
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Gonen OM, Kwan P, O'Brien TJ, Lui E, Desmond PM. Resting-state functional MRI of the default mode network in epilepsy. Epilepsy Behav 2020; 111:107308. [PMID: 32698105 DOI: 10.1016/j.yebeh.2020.107308] [Citation(s) in RCA: 15] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 04/26/2020] [Revised: 06/28/2020] [Accepted: 06/28/2020] [Indexed: 02/09/2023]
Abstract
The default mode network (DMN) is a major neuronal network that deactivates during goal-directed tasks. Recent advances in neuroimaging have shed light on its structure and function. Alterations in the DMN are increasingly recognized in a range of neurological and psychiatric conditions including epilepsy. This review first describes the current understanding of the DMN in health, normal aging, and disease as it is acquired via resting-state functional magnetic resonance imaging (MRI), before focusing on how it is affected in various types of focal and generalized epilepsy. These findings support the potential use of DMN parameters as future biomarkers in epilepsy research, diagnosis, and management.
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Affiliation(s)
- Ofer M Gonen
- The Royal Melbourne Hospital, VIC, Australia; The University of Melbourne, VIC, Australia; The Alfred Hospital, VIC, Australia.
| | - Patrick Kwan
- The Royal Melbourne Hospital, VIC, Australia; The University of Melbourne, VIC, Australia; The Alfred Hospital, VIC, Australia; Monash University, VIC, Australia
| | - Terence J O'Brien
- The Royal Melbourne Hospital, VIC, Australia; The University of Melbourne, VIC, Australia; The Alfred Hospital, VIC, Australia; Monash University, VIC, Australia
| | - Elaine Lui
- The Royal Melbourne Hospital, VIC, Australia; The University of Melbourne, VIC, Australia
| | - Patricia M Desmond
- The Royal Melbourne Hospital, VIC, Australia; The University of Melbourne, VIC, Australia
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11
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González HFJ, Goodale SE, Jacobs ML, Haas KF, Landman BA, Morgan VL, Englot DJ. Brainstem Functional Connectivity Disturbances in Epilepsy may Recover After Successful Surgery. Neurosurgery 2020; 86:417-428. [PMID: 31093673 DOI: 10.1093/neuros/nyz128] [Citation(s) in RCA: 12] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/23/2018] [Accepted: 12/20/2018] [Indexed: 11/14/2022] Open
Abstract
BACKGROUND Focal seizures in temporal lobe epilepsy (TLE) are associated with widespread brain network perturbations and neurocognitive problems. OBJECTIVE To determine whether brainstem connectivity disturbances improve with successful epilepsy surgery, as recent work has demonstrated decreased brainstem connectivity in TLE that is related to disease severity and neurocognitive profile. METHODS We evaluated 15 adult TLE patients before and after (>1 yr; mean, 3.4 yr) surgery, and 15 matched control subjects using magnetic resonance imaging to measure functional and structural connectivity of ascending reticular activating system (ARAS) structures, including cuneiform/subcuneiform nuclei (CSC), pedunculopontine nucleus (PPN), and ventral tegmental area (VTA). RESULTS TLE patients who achieved long-term postoperative seizure freedom (10 of 15) demonstrated increases in functional connectivity between ARAS structures and fronto-parietal-insular neocortex compared to preoperative baseline (P = .01, Kruskal-Wallis), with postoperative connectivity patterns resembling controls' connectivity. No functional connectivity changes were detected in 5 patients with persistent seizures after surgery (P = .9, Kruskal-Wallis). Among seizure-free postoperative patients, larger increases in CSC, PPN, and VTA functional connectivity were observed in individuals with more frequent seizures before surgery (P < .05 for each, Spearman's rho). Larger postoperative increases in PPN functional connectivity were seen in patients with lower baseline verbal IQ (P = .03, Spearman's rho) or verbal memory (P = .04, Mann-Whitney U). No changes in ARAS structural connectivity were detected after successful surgery. CONCLUSION ARAS functional connectivity disturbances are present in TLE but may recover after successful epilepsy surgery. Larger increases in postoperative connectivity may be seen in individuals with more severe disease at baseline.
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Affiliation(s)
- Hernán F J González
- Department of Biomedical Engineering, Vanderbilt University, Nashville, Tennessee.,Vanderbilt University Institute of Imaging Science, Vanderbilt University Medical center, Nashville, Tennessee
| | - Sarah E Goodale
- Department of Biomedical Engineering, Vanderbilt University, Nashville, Tennessee.,Vanderbilt University Institute of Imaging Science, Vanderbilt University Medical center, Nashville, Tennessee.,Department of Neurological Surgery, Vanderbilt University Medical Center, Nashville, Tennessee
| | - Monica L Jacobs
- Department of Psychiatry and Behavioral Sciences, Vanderbilt University Medical Center, Nashville, Tennessee.,Department of Neurology, Vanderbilt University Medical Center, Nashville, Tennessee
| | - Kevin F Haas
- Department of Neurology, Vanderbilt University Medical Center, Nashville, Tennessee
| | - Bennett A Landman
- Vanderbilt University Institute of Imaging Science, Vanderbilt University Medical center, Nashville, Tennessee.,Department of Electrical Engineering, Vanderbilt University, Nashville, Tennessee.,Department of Computer Science, Vanderbilt University, Nashville, Tennessee.,Department of Radiology and Radiological Sciences, Vanderbilt University Medical Center, Nashville, Tennessee
| | - Victoria L Morgan
- Department of Biomedical Engineering, Vanderbilt University, Nashville, Tennessee.,Vanderbilt University Institute of Imaging Science, Vanderbilt University Medical center, Nashville, Tennessee.,Department of Neurological Surgery, Vanderbilt University Medical Center, Nashville, Tennessee.,Department of Neurology, Vanderbilt University Medical Center, Nashville, Tennessee.,Department of Electrical Engineering, Vanderbilt University, Nashville, Tennessee.,Department of Radiology and Radiological Sciences, Vanderbilt University Medical Center, Nashville, Tennessee
| | - Dario J Englot
- Department of Biomedical Engineering, Vanderbilt University, Nashville, Tennessee.,Vanderbilt University Institute of Imaging Science, Vanderbilt University Medical center, Nashville, Tennessee.,Department of Neurological Surgery, Vanderbilt University Medical Center, Nashville, Tennessee.,Department of Radiology and Radiological Sciences, Vanderbilt University Medical Center, Nashville, Tennessee
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12
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Foesleitner O, Sigl B, Schmidbauer V, Nenning KH, Pataraia E, Bartha-Doering L, Baumgartner C, Pirker S, Moser D, Schwarz M, Hainfellner JA, Czech T, Dorfer C, Langs G, Prayer D, Bonelli S, Kasprian G. Language network reorganization before and after temporal lobe epilepsy surgery. J Neurosurg 2020; 134:1694-1702. [PMID: 32619977 DOI: 10.3171/2020.4.jns193401] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/16/2019] [Accepted: 04/07/2020] [Indexed: 11/06/2022]
Abstract
OBJECTIVE Epilepsy surgery is the recommended treatment option for patients with drug-resistant temporal lobe epilepsy (TLE). This method offers a good chance of seizure freedom but carries a considerable risk of postoperative language impairment. The extremely variable neurocognitive profiles in surgical epilepsy patients cannot be fully explained by extent of resection, fiber integrity, or current task-based functional MRI (fMRI). In this study, the authors aimed to investigate pathology- and surgery-triggered language organization in TLE by using fMRI activation and network analysis as well as considering structural and neuropsychological measures. METHODS Twenty-eight patients with unilateral TLE (16 right, 12 left) underwent T1-weighted imaging, diffusion tensor imaging, and task-based language fMRI pre- and postoperatively (n = 15 anterior temporal lobectomy, n = 11 selective amygdalohippocampectomy, n = 2 focal resection). Twenty-two healthy subjects served as the control cohort. Functional connectivity, activation maps, and laterality indices for language dominance were analyzed from fMRI data. Postoperative fractional anisotropy values of 7 major tracts were calculated. Naming, semantic, and phonematic verbal fluency scores before and after surgery were correlated with imaging parameters. RESULTS fMRI network analysis revealed widespread, bihemispheric alterations in language architecture that were not captured by activation analysis. These network changes were found preoperatively and proceeded after surgery with characteristic patterns in the left and right TLEs. Ipsilesional fronto-temporal connectivity decreased in both left and right TLE. In left TLE specifically, preoperative atypical language dominance predicted better postoperative verbal fluency and naming function. In right TLE, left frontal language dominance correlated with good semantic verbal fluency before and after surgery, and left fronto-temporal language laterality predicted good naming outcome. Ongoing seizures after surgery (Engel classes ID-IV) were associated with naming deterioration irrespective of seizure side. Functional findings were not explained by the extent of resection or integrity of major white matter tracts. CONCLUSIONS Functional connectivity analysis contributes unique insight into bihemispheric remodeling processes of language networks after epilepsy surgery, with characteristic findings in left and right TLE. Presurgical contralateral language recruitment is associated with better postsurgical language outcome in left and right TLE.
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Affiliation(s)
| | - Benjamin Sigl
- Departments of1Biomedical Imaging and Image-guided Therapy
| | | | | | | | | | | | - Susanne Pirker
- 4General Hospital Hietzing with Neurological Center Rosenhuegel, Vienna; and
| | | | | | | | - Thomas Czech
- 6Department of Neurosurgery, Medical University of Vienna, Austria
| | - Christian Dorfer
- 6Department of Neurosurgery, Medical University of Vienna, Austria
| | - Georg Langs
- Departments of1Biomedical Imaging and Image-guided Therapy
| | - Daniela Prayer
- Departments of1Biomedical Imaging and Image-guided Therapy
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13
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Human brain connectivity: Clinical applications for clinical neurophysiology. Clin Neurophysiol 2020; 131:1621-1651. [DOI: 10.1016/j.clinph.2020.03.031] [Citation(s) in RCA: 34] [Impact Index Per Article: 8.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/18/2019] [Revised: 03/13/2020] [Accepted: 03/17/2020] [Indexed: 12/12/2022]
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14
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Englot DJ. Network Changes after Epilepsy Surgery: It's Time to Reconnect. Epilepsy Curr 2019; 20:12-13. [PMID: 31749378 PMCID: PMC7020526 DOI: 10.1177/1535759719885154] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022] Open
Abstract
Network-Targeted Approach and Postoperative Resting-State Functional Magnetic Resonance Imaging Are Associated With Seizure Outcome Boerwinkle VL, Cediel EG, Mirea L, et al. Ann Neurol. 2019;86(3):344-356. Objective: Postoperative resting-state functional magnetic resonance imaging (MRI) in children with intractable epilepsy has not been quantified in relation to seizure outcome. Therefore, its value as a biomarker for epileptogenic pathology is not well understood. Methods: In a sample of children with intractable epilepsy who underwent prospective resting-state seizure onset zone (SOZ)-targeted epilepsy surgery, postoperative resting-state functional MRI (rs-fMRI) was performed 6 to 12 months later. Graded normalization of the postoperative resting-state SOZ was compared to seizure outcomes, patient, surgery, and anatomical MRI characteristics. Results: A total of 64 cases were evaluated. Network-targeted surgery, followed by postoperative rs-fMRI normalization was significantly (P < .001) correlated with seizure reduction, with a Spearman rank correlation coefficient of 0.83. Of 39 cases with postoperative rs-fMRI SOZ normalization, 38 (97%) became completely seizure free. In contrast, of the 25 cases without complete rs-fMRI SOZ normalization, only 3 (5%) became seizure free. The accuracy of rs-fMRI as a biomarker predicting seizure freedom is 94%, with 96% sensitivity and 93% specificity. Interpretation: Among seizure localization techniques in pediatric epilepsy, network-targeted surgery, followed by postoperative rs-fMRI normalization, has high correlation with seizure freedom. This study shows that rs-fMRI SOZ can be used as a biomarker for the epileptogenic zone, and postoperative rs-fMRI normalization is a biomarker for SOZ quiescence.
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15
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Boerwinkle VL, Cediel EG, Mirea L, Williams K, Kerrigan JF, Lam S, Raskin JS, Desai VR, Wilfong AA, Adelson PD, Curry DJ. Network-targeted approach and postoperative resting-state functional magnetic resonance imaging are associated with seizure outcome. Ann Neurol 2019; 86:344-356. [PMID: 31294865 DOI: 10.1002/ana.25547] [Citation(s) in RCA: 41] [Impact Index Per Article: 8.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/15/2019] [Revised: 07/08/2019] [Accepted: 07/09/2019] [Indexed: 12/25/2022]
Abstract
OBJECTIVE Postoperative resting-state functional magnetic resonance imaging (MRI) in children with intractable epilepsy has not been quantified in relation to seizure outcome. Therefore, its value as a biomarker for epileptogenic pathology is not well understood. METHODS In a sample of children with intractable epilepsy who underwent prospective resting-state seizure onset zone (SOZ)-targeted epilepsy surgery, postoperative resting-state functional MRI (rs-fMRI) was performed 6 to 12 months later. Graded normalization of the postoperative resting-state SOZ was compared to seizure outcomes, patient, surgery, and anatomical MRI characteristics. RESULTS A total of 64 cases were evaluated. Network-targeted surgery, followed by postoperative rs-fMRI normalization was significantly (p < 0.001) correlated with seizure reduction, with a Spearman rank correlation coefficient of 0.83. Of 39 cases with postoperative rs-fMRI SOZ normalization, 38 (97%) became completely seizure free. In contrast, of the 25 cases without complete rs-fMRI SOZ normalization, only 3 (5%) became seizure free. The accuracy of rs-fMRI as a biomarker predicting seizure freedom is 94%, with 96% sensitivity and 93% specificity. INTERPRETATION Among seizure localization techniques in pediatric epilepsy, network-targeted surgery, followed by postoperative rs-fMRI normalization, has high correlation with seizure freedom. This study shows that rs-fMRI SOZ can be used as a biomarker of the epileptogenic zone, and postoperative rs-fMRI normalization is a biomarker for SOZ quiescence. ANN NEUROL 2019;86:344-356.
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Affiliation(s)
- Varina L Boerwinkle
- Division of Pediatric Neurology, Barrow Neurological Institute at Phoenix Children's Hospital, Phoenix, AZ
| | - Emilio G Cediel
- Division of Pediatric Neurosurgery, Barrow Neurological Institute at Phoenix Children's Hospital, Phoenix, AZ
| | - Lucia Mirea
- Department of Research, Phoenix Children's Hospital, Phoenix, AZ
| | - Korwyn Williams
- Division of Pediatric Neurology, Barrow Neurological Institute at Phoenix Children's Hospital, Phoenix, AZ
| | - John F Kerrigan
- Division of Pediatric Neurology, Barrow Neurological Institute at Phoenix Children's Hospital, Phoenix, AZ
| | - Sandi Lam
- Section of Pediatric Neurosurgery, Riley Hospital for Children, Department of Neurological Surgery, Indiana University School of Medicine, Indianapolis, IN
| | - Jeffrey S Raskin
- Section of Pediatric Neurosurgery, Riley Hospital for Children, Department of Neurological Surgery, Indiana University School of Medicine, Indianapolis, IN
| | - Virendra R Desai
- Department of Neurosurgery, Houston Methodist Hospital, Houston, TX
| | - Angus A Wilfong
- Division of Pediatric Neurology, Barrow Neurological Institute at Phoenix Children's Hospital, Phoenix, AZ
| | - P David Adelson
- Division of Pediatric Neurology, Barrow Neurological Institute at Phoenix Children's Hospital, Phoenix, AZ.,Division of Pediatric Neurosurgery, Barrow Neurological Institute at Phoenix Children's Hospital, Phoenix, AZ
| | - Daniel J Curry
- Department of Pediatric Neurosurgery, Texas Children's Hospital, Baylor College of Medicine, Houston, TX
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16
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Morgan VL, Rogers BP, González HFJ, Goodale SE, Englot DJ. Characterization of postsurgical functional connectivity changes in temporal lobe epilepsy. J Neurosurg 2019; 133:392-402. [PMID: 31200384 PMCID: PMC6911037 DOI: 10.3171/2019.3.jns19350] [Citation(s) in RCA: 16] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/07/2019] [Accepted: 03/24/2019] [Indexed: 02/02/2023]
Abstract
OBJECTIVE Seizure outcome after mesial temporal lobe epilepsy (mTLE) surgery is complex and diverse, even across patients with homogeneous presurgical clinical profiles. The authors hypothesized that this is due in part to variations in network connectivity across the brain before and after surgery. Although presurgical network connectivity has been previously characterized in these patients, the objective of this study was to characterize presurgical to postsurgical functional network connectivity changes across the brain after mTLE surgery. METHODS Twenty patients with drug-refractory unilateral mTLE (5 left side, 10 female, age 39.3 ± 13.5 years) who underwent either selective amygdalohippocampectomy (n = 13) or temporal lobectomy (n = 7) were included in the study. Presurgical and postsurgical (36.6 ± 14.3 months after surgery) functional connectivity (FC) was measured with 3-T MRI and compared with findings in age-matched healthy controls (n = 44, 21 female, age 39.3 ± 14.3 years). Postsurgical connectivity changes were then related to seizure outcome, type of surgery, and presurgical disease parameters. RESULTS The results demonstrated significant decreases of FC from control group values across the brain after surgery that were not present before surgery, including many contralateral hippocampal connections distal to the surgical site. Postsurgical impairment of contralateral precuneus to ipsilateral occipital connectivity was associated with seizure recurrence. Presurgical impairment of the contralateral precuneus to contralateral temporal lobe connectivity was associated with those who underwent selective amygdalohippocampectomy compared to those who had temporal lobectomy. Finally, changes in thalamic connectivity after surgery were linearly related to duration of epilepsy and frequency of consciousness-impairing seizures prior to surgery. CONCLUSIONS The widespread contralateral hippocampal FC changes after surgery may be a reflection of an ongoing epileptogenic progression that has been altered by the surgery, rather than a direct result of the surgery itself. This network evolution may contribute to long-term seizure outcome. Therefore, the combination of presurgical network mapping with the understanding of the dynamic effects of surgery on the networks may ultimately be used to create predictors of the likelihood of long-term seizure recurrence in individual patients after mTLE surgery.
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Affiliation(s)
- Victoria L. Morgan
- Vanderbilt University Institute of Imaging Science, Department of Radiology and Radiological Sciences, Vanderbilt University Medical Center
- Department of Biomedical Engineering, Vanderbilt University
- Department of Neurological Surgery, Vanderbilt University Medical Center, Nashville, Tennessee
| | - Baxter P. Rogers
- Vanderbilt University Institute of Imaging Science, Department of Radiology and Radiological Sciences, Vanderbilt University Medical Center
| | | | | | - Dario J. Englot
- Vanderbilt University Institute of Imaging Science, Department of Radiology and Radiological Sciences, Vanderbilt University Medical Center
- Department of Biomedical Engineering, Vanderbilt University
- Department of Neurological Surgery, Vanderbilt University Medical Center, Nashville, Tennessee
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