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Smith J, Richerson G, Kouchi H, Duprat F, Mantegazza M, Bezin L, Rheims S. Are we there yet? A critical evaluation of sudden and unexpected death in epilepsy models. Epilepsia 2024; 65:9-25. [PMID: 37914406 DOI: 10.1111/epi.17812] [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: 08/04/2023] [Revised: 10/11/2023] [Accepted: 10/31/2023] [Indexed: 11/03/2023]
Abstract
Although animal models have helped to elaborate meaningful hypotheses about the pathophysiology of sudden and unexpected death in epilepsy (SUDEP), specific prevention strategies are still lacking, potentially reflecting the limitations of these models and the intrinsic difficulties of investigating SUDEP. The interpretation of preclinical data and their translation to diagnostic and therapeutic developments in patients thus require a high level of confidence in their relevance to model the human situation. Preclinical models of SUDEP are heterogeneous and include rodent and nonrodent species. A critical aspect is whether the animals have isolated seizures exclusively induced by a specific trigger, such as models where seizures are elicited by electrical stimulation, pharmacological intervention, or DBA mouse strains, or whether they suffer from epilepsy with spontaneous seizures, with or without spontaneous SUDEP, either of nongenetic epilepsy etiology or from genetically based developmental and epileptic encephalopathies. All these models have advantages and potential disadvantages, but it is important to be aware of these limitations to interpret data appropriately in a translational perspective. The majority of models with spontaneous seizures are of a genetic basis, whereas SUDEP cases with a genetic basis represent only a small proportion of the total number. In almost all models, cardiorespiratory arrest occurs during the course of the seizure, contrary to that in patients observed at the time of death, potentially raising the issue of whether we are studying models of SUDEP or models of periseizure death. However, some of these limitations are impossible to avoid and can in part be dependent on specific features of SUDEP, which may be difficult to model. Several preclinical tools are available to address certain gaps in SUDEP pathophysiology, which can be used to further validate current preclinical models.
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Affiliation(s)
- Jonathon Smith
- Lyon Neuroscience Research Center (CRNL, INSERM U1028/CNRS UMR 5292, Lyon 1 University), Lyon, France
| | - George Richerson
- Department of Neurology, University of Iowa, Iowa City, Iowa, USA
| | - Hayet Kouchi
- Lyon Neuroscience Research Center (CRNL, INSERM U1028/CNRS UMR 5292, Lyon 1 University), Lyon, France
| | - Fabrice Duprat
- University Cote d'Azur, Valbonne-Sophia Antipolis, France
- CNRS UMR 7275, Institute of Molecular and Cellular Pharmacology, Valbonne-Sophia Antipolis, France
- Inserm, Valbonne-Sophia Antipolis, France
| | - Massimo Mantegazza
- University Cote d'Azur, Valbonne-Sophia Antipolis, France
- CNRS UMR 7275, Institute of Molecular and Cellular Pharmacology, Valbonne-Sophia Antipolis, France
- Inserm, Valbonne-Sophia Antipolis, France
| | - Laurent Bezin
- Lyon Neuroscience Research Center (CRNL, INSERM U1028/CNRS UMR 5292, Lyon 1 University), Lyon, France
| | - Sylvain Rheims
- Lyon Neuroscience Research Center (CRNL, INSERM U1028/CNRS UMR 5292, Lyon 1 University), Lyon, France
- Department of Functional Neurology and Epileptology, Hospices Civils de Lyon and Lyon 1 University, Lyon, France
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Myren‐Svelstad S, Jamali A, Ophus SS, D'gama PP, Ostenrath AM, Mutlu AK, Hoffshagen HH, Hotz AL, Neuhauss SCF, Jurisch‐Yaksi N, Yaksi E. Elevated photic response is followed by a rapid decay and depressed state in ictogenic networks. Epilepsia 2022; 63:2543-2560. [PMID: 36222083 PMCID: PMC9804334 DOI: 10.1111/epi.17380] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/04/2022] [Revised: 07/27/2022] [Accepted: 07/27/2022] [Indexed: 01/05/2023]
Abstract
OBJECTIVE The switch between nonseizure and seizure states involves profound alterations in network excitability and synchrony. In this study, we aimed to identify and compare features of neural excitability and dynamics across multiple zebrafish seizure and epilepsy models. METHODS Inspired by video-electroencephalographic recordings in patients, we developed a framework to study spontaneous and photically evoked neural and locomotor activity in zebrafish larvae, by combining high-throughput behavioral tracking and whole-brain in vivo two-photon calcium imaging. RESULTS Our setup allowed us to dissect behavioral and physiological features that are divergent or convergent across multiple models. We observed that spontaneous locomotor and neural activity exhibit great diversity across models. Nonetheless, during photic stimulation, hyperexcitability and rapid response dynamics were well conserved across multiple models, highlighting the reliability of photically evoked activity for high-throughput assays. Intriguingly, in several models, we observed that the initial elevated photic response is often followed by rapid decay of neural activity and a prominent depressed state. Elevated photic response and following depressed state in seizure-prone networks are significantly reduced by the antiseizure medication valproic acid. Finally, rapid decay and depression of neural activity following photic stimulation temporally overlap with slow recruitment of astroglial calcium signals that are enhanced in seizure-prone networks. SIGNIFICANCE We argue that fast decay of neural activity and depressed states following photic response are likely due to homeostatic mechanisms triggered by excessive neural activity. An improved understanding of the interplay between elevated and depressed excitability states might suggest tailored epilepsy therapies.
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Affiliation(s)
- Sverre Myren‐Svelstad
- Kavli Institute for Systems Neuroscience and Centre for Neural Computation, Faculty of Medicine and Health SciencesNorwegian University of Science and TechnologyTrondheimNorway,Department of Neuromedicine and Movement Science, Faculty of Medicine and Health SciencesNorwegian University of Science and TechnologyTrondheimNorway,Department of Neurology and Clinical NeurophysiologySt Olav's University HospitalTrondheimNorway
| | - Ahmed Jamali
- Kavli Institute for Systems Neuroscience and Centre for Neural Computation, Faculty of Medicine and Health SciencesNorwegian University of Science and TechnologyTrondheimNorway,Department of Neuromedicine and Movement Science, Faculty of Medicine and Health SciencesNorwegian University of Science and TechnologyTrondheimNorway,Department of Neurology and Clinical NeurophysiologySt Olav's University HospitalTrondheimNorway
| | - Sunniva S. Ophus
- Kavli Institute for Systems Neuroscience and Centre for Neural Computation, Faculty of Medicine and Health SciencesNorwegian University of Science and TechnologyTrondheimNorway
| | - Percival P. D'gama
- Kavli Institute for Systems Neuroscience and Centre for Neural Computation, Faculty of Medicine and Health SciencesNorwegian University of Science and TechnologyTrondheimNorway,Department of Clinical and Molecular Medicine, Faculty of Medicine and Health SciencesNorwegian University of Science and TechnologyTrondheimNorway
| | - Anna M. Ostenrath
- Kavli Institute for Systems Neuroscience and Centre for Neural Computation, Faculty of Medicine and Health SciencesNorwegian University of Science and TechnologyTrondheimNorway
| | - Aytac Kadir Mutlu
- Kavli Institute for Systems Neuroscience and Centre for Neural Computation, Faculty of Medicine and Health SciencesNorwegian University of Science and TechnologyTrondheimNorway
| | - Helene Homme Hoffshagen
- Kavli Institute for Systems Neuroscience and Centre for Neural Computation, Faculty of Medicine and Health SciencesNorwegian University of Science and TechnologyTrondheimNorway
| | - Adriana L. Hotz
- Department of Molecular Life SciencesUniversity of ZürichZürichSwitzerland
| | | | - Nathalie Jurisch‐Yaksi
- Kavli Institute for Systems Neuroscience and Centre for Neural Computation, Faculty of Medicine and Health SciencesNorwegian University of Science and TechnologyTrondheimNorway,Department of Neurology and Clinical NeurophysiologySt Olav's University HospitalTrondheimNorway,Department of Clinical and Molecular Medicine, Faculty of Medicine and Health SciencesNorwegian University of Science and TechnologyTrondheimNorway
| | - Emre Yaksi
- Kavli Institute for Systems Neuroscience and Centre for Neural Computation, Faculty of Medicine and Health SciencesNorwegian University of Science and TechnologyTrondheimNorway,Koç University Research Center for Translational Medicine, Department of NeurologyKoç University School of MedicineIstanbulTurkey
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Szabo CA, Salinas FS. Neuroimaging in the Epileptic Baboon. Front Vet Sci 2022; 9:908801. [PMID: 35909685 PMCID: PMC9330034 DOI: 10.3389/fvets.2022.908801] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/31/2022] [Accepted: 06/23/2022] [Indexed: 11/13/2022] Open
Abstract
Characterization of baboon model of genetic generalized epilepsy (GGE) is driven both electroclinically and by successful adoption of neuroimaging platforms, such as magnetic resonance imaging (MRI) and positron emission tomography (PET). Based upon its phylogenetic proximity and similar brain anatomy to humans, the epileptic baboon provides an excellent translational model. Its relatively large brain size compared to smaller nonhuman primates or rodents, a gyrencephalic structure compared to lissencephalic organization of rodent brains, and the availability of a large pedigreed colony allows exploration of neuroimaging markers of diseases. Similar to human idiopathic generalized epilepsy (IGE), structural imaging in the baboon is usually normal in individual subjects, but gray matter volume/concentration (GMV/GMC) changes are reported by statistical parametric mapping (SPM) analyses. Functional neuroimaging has been effective for mapping the photoepileptic responses, the epileptic network, altered functional connectivity of physiological networks, and the effects of anti-seizure therapies. This review will provide insights into our current understanding the baboon model of GGE through functional and structural imaging.
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Affiliation(s)
- C. Akos Szabo
- Department of Neurology, University of Texas Health San Antonio, San Antonio, TX, United States
- *Correspondence: C. Akos Szabo
| | - Felipe S. Salinas
- Research Imaging Institute, University of Texas Health San Antonio, San Antonio, TX, United States
- Department of Radiology, University of Texas Health San Antonio, San Antonio, TX, United States
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Fisher RS, Acharya JN, Baumer FM, French JA, Parisi P, Solodar JH, Szaflarski JP, Thio LL, Tolchin B, Wilkins AJ, Kasteleijn-Nolst Trenité D. Visually sensitive seizures: An updated review by the Epilepsy Foundation. Epilepsia 2022; 63:739-768. [PMID: 35132632 DOI: 10.1111/epi.17175] [Citation(s) in RCA: 24] [Impact Index Per Article: 12.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/29/2021] [Revised: 01/10/2022] [Accepted: 01/12/2022] [Indexed: 12/19/2022]
Abstract
Light flashes, patterns, or color changes can provoke seizures in up to 1 in 4000 persons. Prevalence may be higher because of selection bias. The Epilepsy Foundation reviewed light-induced seizures in 2005. Since then, images on social media, virtual reality, three-dimensional (3D) movies, and the Internet have proliferated. Hundreds of studies have explored the mechanisms and presentations of photosensitive seizures, justifying an updated review. This literature summary derives from a nonsystematic literature review via PubMed using the terms "photosensitive" and "epilepsy." The photoparoxysmal response (PPR) is an electroencephalography (EEG) phenomenon, and photosensitive seizures (PS) are seizures provoked by visual stimulation. Photosensitivity is more common in the young and in specific forms of generalized epilepsy. PS can coexist with spontaneous seizures. PS are hereditable and linked to recently identified genes. Brain imaging usually is normal, but special studies imaging white matter tracts demonstrate abnormal connectivity. Occipital cortex and connected regions are hyperexcitable in subjects with light-provoked seizures. Mechanisms remain unclear. Video games, social media clips, occasional movies, and natural stimuli can provoke PS. Virtual reality and 3D images so far appear benign unless they contain specific provocative content, for example, flashes. Images with flashes brighter than 20 candelas/m2 at 3-60 (particularly 15-20) Hz occupying at least 10 to 25% of the visual field are a risk, as are red color flashes or oscillating stripes. Equipment to assay for these characteristics is probably underutilized. Prevention of seizures includes avoiding provocative stimuli, covering one eye, wearing dark glasses, sitting at least two meters from screens, reducing contrast, and taking certain antiseizure drugs. Measurement of PPR suppression in a photosensitivity model can screen putative antiseizure drugs. Some countries regulate media to reduce risk. Visually-induced seizures remain significant public health hazards so they warrant ongoing scientific and regulatory efforts and public education.
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Affiliation(s)
- Robert S Fisher
- Department of Neurology and Neurological Sciences, Stanford University School of Medicine, Stanford, California, USA
| | - Jayant N Acharya
- Department of Neurology, Penn State Health, Hershey, Pennsylvania, USA
| | - Fiona Mitchell Baumer
- Department of Neurology and Neurological Sciences, Stanford University School of Medicine, Stanford, California, USA
| | - Jacqueline A French
- NYU Comprehensive Epilepsy Center, Epilepsy Foundation, New York, New York, USA
| | - Pasquale Parisi
- Department of Neuroscience, Mental Health, and Sensory Organs, Sapienza University, Rome, Italy
| | - Jessica H Solodar
- American Medical Writers Association-New England Chapter, Boston, Massachusetts, USA
| | - Jerzy P Szaflarski
- Department of Neurology, Neurobiology and Neurosurgery, University of Alabama at Birmingham Heersink School of Medicine, Birmingham, Alabama, USA
| | - Liu Lin Thio
- Department of Neurology, Washington University School of Medicine, St. Louis, Missouri, USA
| | - Benjamin Tolchin
- Department of Neurology, Yale School of Medicine, New Haven, Connecticut, USA
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Szabó CÁ, Akopian M, Papanastassiou AM, Salinas FS. Cerebral blood flow differences between high- vs low-frequency VNS therapy in the epileptic baboon. Epilepsy Res 2022; 180:106862. [PMID: 35114431 DOI: 10.1016/j.eplepsyres.2022.106862] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/10/2021] [Revised: 12/24/2021] [Accepted: 01/17/2022] [Indexed: 01/24/2023]
Abstract
PURPOSE Cerebral blood flow (CBF) tracks physiological effects of ictal or interictal epileptic discharges (IEDs) and neurostimulation. This study compared CBF changes between high-frequency (HF; 300 Hz) microburst, and standard, low-frequency (LF; 30 Hz) vagal nerve stimulation (VNS) Therapy in 2 baboons with genetic generalized epilepsy (GGE), including one with photosensitivity. METHODS The baboons were selected based on video recordings and scalp EEG studies. They were both implanted with Sentiva™ 1000 devices capable of stimulating at standard and microburst frequencies. Nine H215O (10-20 mCi) positron emission tomographic (PET) scans were performed each session (two PET sessions acquired for each animal). The baboons were sedated with ketamine, paralyzed, and monitored with scalp EEG. CBF changes were compared between the two modes of stimulation and resting scans in the first study, while in the second, VNS Therapy trials were combined with intermittent light stimulation (ILS) at 25 Hz and compared to CBF changes induced by ILS alone. RESULTS ILS-associated IED rates were slightly reduced by HF- and LF-VNS Therapies in B1, while spontaneous IEDs were completely suppressed by HF-VNS Therapy in B2. Regional CBF changes were consistent between the two modes of therapy in each baboon, in particular with respect to the activation of the superior colliculus and cerebellum. Neither VNS mode suppressed the photoepileptic response in B1. In B2, IED suppression was associated with bilateral deactivations of the frontal and temporal cortices, cingulate and anterior striatum, as well as bilateral cerebellar activations. CONCLUSIONS This pilot study reveals similar activation/deactivation patterns between LF- and HF-VNS Therapies, but the most pronounced CBF differences between the two baboons and the two modes of stimulation may have been driven by the suppression of the epileptic network by HF-VNS Therapy in B2. Some therapeutic targets appear to be subcortical, including the putamen, superior colliculus, brainstem nuclei, as well as the cerebellum, all of which modulate corticothalamic networks, which is particularly reflected by CBF changes associated with HF-VNS Therapy. These findings need to be replicated in larger samples and correlated with long-term clinical outcomes.
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Affiliation(s)
- C Ákos Szabó
- Department of Neurology, University of Texas Health San Antonio, San Antonio, TX, USA.
| | - Margarita Akopian
- Neurodiagnostic Center, University Health System, San Antonio, TX, USA
| | | | - Felipe S Salinas
- Research Imaging Institute, USA; Department of Radiology, University of Texas Health San Antonio, San Antonio, TX, USA
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The baboon in epilepsy research: Revelations and challenges. Epilepsy Behav 2021; 121:108012. [PMID: 34022622 PMCID: PMC8238811 DOI: 10.1016/j.yebeh.2021.108012] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 04/11/2021] [Accepted: 04/17/2021] [Indexed: 11/23/2022]
Abstract
The baboon offers a natural model for genetic generalized epilepsy with photosensitivity. In this review, we will summarize some of the more important clinical, neuroimaging, and elctrophysiological findings form recent work performed at the Southwest National Primate Research Center (SNPRC, Texas Biomedical Research Institute, San Antonio, Texas), which houses the world's largest captive baboon pedigree. Due to the phylogenetic proximity of the baboon to humans, many of the findings are readily translatable, but there may be some important differences, such as the mutlifocality of the ictal and interictal epileptic discharges (IEDs) on intracranial electroencephalography (EEG) and greater parieto-occipital connectivity of baboon brain networks compared to juvenile myoclonic epilepsy in humans. Furthermore, there is still limited knowledge of the natural history of the epilepsy, which could be transformative for research into epileptogenesis in genetic generalized epilepsy (GGE) and sudden unexpected death in epilepsy (SUDEP).
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