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Parrino L, Halasz P, Szucs A, Thomas RJ, Azzi N, Rausa F, Pizzarotti S, Zilioli A, Misirocchi F, Mutti C. Sleep medicine: Practice, challenges and new frontiers. Front Neurol 2022; 13:966659. [PMID: 36313516 PMCID: PMC9616008 DOI: 10.3389/fneur.2022.966659] [Citation(s) in RCA: 8] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/11/2022] [Accepted: 08/29/2022] [Indexed: 11/13/2022] Open
Abstract
Sleep medicine is an ambitious cross-disciplinary challenge, requiring the mutual integration between complementary specialists in order to build a solid framework. Although knowledge in the sleep field is growing impressively thanks to technical and brain imaging support and through detailed clinic-epidemiologic observations, several topics are still dominated by outdated paradigms. In this review we explore the main novelties and gaps in the field of sleep medicine, assess the commonest sleep disturbances, provide advices for routine clinical practice and offer alternative insights and perspectives on the future of sleep research.
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Affiliation(s)
- Liborio Parrino
- Department of General and Specialized Medicine, Sleep Disorders Center, University Hospital of Parma, Parma, Italy
- *Correspondence: Liborio Parrino
| | - Peter Halasz
- Szentagothai János School of Ph.D Studies, Clinical Neurosciences, Semmelweis University, Budapest, Hungary
| | - Anna Szucs
- Department of Behavioral Sciences, National Institute of Clinical Neurosciences, Semmelweis University, Budapest, Hungary
| | - Robert J. Thomas
- Division of Pulmonary, Critical Care and Sleep, Department of Medicine, Beth Israel Deaconess Medical Center and Harvard Medical School, Boston, MA, United States
| | - Nicoletta Azzi
- Department of General and Specialized Medicine, Sleep Disorders Center, University Hospital of Parma, Parma, Italy
| | - Francesco Rausa
- Department of General and Specialized Medicine, Sleep Disorders Center, University Hospital of Parma, Parma, Italy
- Department of Medicine and Surgery, Unit of Neurology, University of Parma, Parma, Italy
| | - Silvia Pizzarotti
- Department of General and Specialized Medicine, Sleep Disorders Center, University Hospital of Parma, Parma, Italy
| | - Alessandro Zilioli
- Department of Medicine and Surgery, Unit of Neurology, University of Parma, Parma, Italy
| | - Francesco Misirocchi
- Department of Medicine and Surgery, Unit of Neurology, University of Parma, Parma, Italy
| | - Carlotta Mutti
- Department of General and Specialized Medicine, Sleep Disorders Center, University Hospital of Parma, Parma, Italy
- Department of Medicine and Surgery, Unit of Neurology, University of Parma, Parma, Italy
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Repeated hippocampal seizures lead to brain-wide reorganization of circuits and seizure propagation pathways. Neuron 2021; 110:221-236.e4. [PMID: 34706219 PMCID: PMC10402913 DOI: 10.1016/j.neuron.2021.10.010] [Citation(s) in RCA: 16] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/18/2020] [Revised: 05/18/2021] [Accepted: 10/05/2021] [Indexed: 11/24/2022]
Abstract
Repeated seizure activity can lead to long-term changes in seizure dynamics and behavior. However, resulting changes in brain-wide dynamics remain poorly understood. This is due partly to technical challenges in precise seizure control and in vivo whole-brain mapping of circuit dynamics. Here, we developed an optogenetic kindling model through repeated stimulation of ventral hippocampal CaMKII neurons in adult rats. We then combined fMRI with electrophysiology to track brain-wide circuit dynamics resulting from non-afterdischarge (AD)-generating stimulations and individual convulsive seizures. Kindling induced widespread increases in non-AD-generating stimulation response and ipsilateral functional connectivity and elevated anxiety. Individual seizures in kindled animals showed more significant increases in brain-wide activity and bilateral functional connectivity. Onset time quantification provided evidence for kindled seizure propagation from the ipsilateral to the contralateral hemisphere. Furthermore, a core of slow-migrating hippocampal activity was identified in both non-kindled and kindled seizures, revealing a novel mechanism of seizure sustainment and propagation.
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Fadaie F, Lee HM, Caldairou B, Gill RS, Sziklas V, Crane J, Bernhardt BC, Hong SJ, Bernasconi A, Bernasconi N. Atypical functional connectome hierarchy impacts cognition in temporal lobe epilepsy. Epilepsia 2021; 62:2589-2603. [PMID: 34490890 DOI: 10.1111/epi.17032] [Citation(s) in RCA: 19] [Impact Index Per Article: 6.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/26/2021] [Revised: 06/24/2021] [Accepted: 07/26/2021] [Indexed: 02/04/2023]
Abstract
OBJECTIVE Drug-resistant temporal lobe epilepsy (TLE) is typically associated with hippocampal pathology. However, widespread network alterations are increasingly recognized and suggested to perturb cognitive function in multiple domains. Here we tested (1) whether TLE shows atypical cortical hierarchical organization, differentiating sensory and higher order systems; and (2) whether atypical hierarchy predicts cognitive impairment. METHODS We studied 72 well-characterized drug-resistant TLE patients and 41 healthy controls, statistically matched for age and sex, using multimodal magnetic resonance imaging analysis and cognitive testing. To model cortical hierarchical organization in vivo, we used a bidirectional stepwise functional connectivity analysis tapping into the differentiation between sensory/unimodal and paralimbic/transmodal cortices. Linear models compared patients to controls. Finally, we assessed associations of functional anomalies to cortical atrophy and microstructural anomalies, as well as clinical and cognitive parameters. RESULTS Compared to controls, TLE presented with bidirectional disruptions of sensory-paralimbic functional organization. Stepwise connectivity remained segregated within paralimbic and salience networks at the top of the hierarchy, and sensorimotor and dorsal attention at the bottom. Whereas paralimbic segregation was associated with atypical cortical myeloarchitecture and hippocampal atrophy, dysconnectivity of sensorimotor cortices reflected diffuse cortical thinning. The degree of abnormal hierarchical organization in sensory-petal streams covaried, with broad cognitive impairments spanning sensorimotor, attention, fluency, and visuoconstructional ability and memory, and was more marked in patients with longer disease duration and Engel I outcome. SIGNIFICANCE Our findings show atypical functional integration between paralimbic/transmodal and sensory/unimodal systems in TLE. Differential associations with paralimbic microstructure and sensorimotor atrophy suggest that system-level imbalance likely reflects complementary structural processes, but ultimately accounts for a broad spectrum of cognitive impairments. Hierarchical contextualization of cognitive deficits promises to open new avenues for personalized counseling in TLE.
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Affiliation(s)
- Fatemeh Fadaie
- Neuroimaging of Epilepsy Laboratory, McConnell Brain Imaging Centre, Montreal Neurological Institute and Hospital, McGill University, Montreal, Quebec, Canada
| | - Hyo M Lee
- Neuroimaging of Epilepsy Laboratory, McConnell Brain Imaging Centre, Montreal Neurological Institute and Hospital, McGill University, Montreal, Quebec, Canada
| | - Benoit Caldairou
- Neuroimaging of Epilepsy Laboratory, McConnell Brain Imaging Centre, Montreal Neurological Institute and Hospital, McGill University, Montreal, Quebec, Canada
| | - Ravnoor S Gill
- Neuroimaging of Epilepsy Laboratory, McConnell Brain Imaging Centre, Montreal Neurological Institute and Hospital, McGill University, Montreal, Quebec, Canada
| | - Viviane Sziklas
- Department of Neurology and Neurosurgery, Montreal Neurological Institute and Hospital, McGill University, Montreal, Quebec, Canada
| | - Joelle Crane
- Department of Neurology and Neurosurgery, Montreal Neurological Institute and Hospital, McGill University, Montreal, Quebec, Canada
| | - Boris C Bernhardt
- Medical Imaging and Connectome Analysis Laboratory, McConnell Brain Imaging Centre, Montreal Neurological Institute and Hospital, McGill University, Montreal, Quebec, Canada
| | - Seok-Jun Hong
- Neuroimaging of Epilepsy Laboratory, McConnell Brain Imaging Centre, Montreal Neurological Institute and Hospital, McGill University, Montreal, Quebec, Canada
| | - 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
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Doerrfuss JI, Kowski AB, Holtkamp M. Etiology-specific response to antiseizure medication in focal epilepsy. Epilepsia 2021; 62:2133-2141. [PMID: 34328218 DOI: 10.1111/epi.17017] [Citation(s) in RCA: 12] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/22/2021] [Revised: 07/13/2021] [Accepted: 07/13/2021] [Indexed: 01/26/2023]
Abstract
OBJECTIVE In focal epilepsy, data on the etiology-specific response to antiseizure medication (ASM) are surprisingly sparse. In this study, we sought to reappraise whether seizure outcome of pharmacological treatment is linked to the underlying etiology. Furthermore, we assessed ASM load with respect to the cause of epilepsy. METHODS Data were retrospectively obtained from the electronic database of the three sites of an academic adult epilepsy outpatient clinic. For each patient, presumed cause of epilepsy was categorized into one of nine etiological groups. Individual drug loads were calculated according to the 2020 World Health Organization Center for Drug Statistics Methodology ATC/DDD Index. Univariate and multivariate analyses were conducted to explore the association between different etiologies and outcome regarding 12-month seizure freedom as well as ASM load. RESULTS A total of 591 patients with focal epilepsy were included in the final analysis. Ischemic stroke was the etiology with the highest rate of 12-month terminal seizure freedom (71.2%, 95% confidence interval [CI] = 57.9-82.2) and, considering all etiological groups, was an independent predictor of seizure freedom (odds ratio = 2.093, 95% CI = 1.039-4.216). The lowest rates of seizure freedom were observed in patients with hippocampal sclerosis (28.2%, 95% CI = 15.0-44.9) and malformation of cortical development (16.7%, 95% CI = 2.1-48.4). In patients with ischemic stroke, median ASM load (1.0, interquartile range [IQR] = .5-1.8) was significantly lower compared to that in patients with hippocampal sclerosis (median = 1.8, IQR = 1.2-3.0, p = .008) and brain tumors (median = 1.7, IQR = .7-3.2, p = .049). SIGNIFICANCE Response to treatment with ASM is highly etiology-specific and best in patients with epilepsy due to ischemic stroke. Interestingly, this most favorable treatment outcome can be achieved by the lowest ASM load considering all etiological groups. In focal epilepsy, etiology should be taken into account when counseling patients about their expected seizure outcome with pharmacological treatment and when tailoring initial ASM doses.
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Affiliation(s)
- Jakob I Doerrfuss
- Department of Neurology with Experimental Neurology, Charité - Universitätsmedizin Berlin, Corporate Member of Freie Universität Berlin, Humboldt-Universität zu Berlin and Berlin Institute of Health, Berlin, Germany
| | - Alexander B Kowski
- Department of Neurology with Experimental Neurology, Charité - Universitätsmedizin Berlin, Corporate Member of Freie Universität Berlin, Humboldt-Universität zu Berlin and Berlin Institute of Health, Berlin, Germany
| | - Martin Holtkamp
- Department of Neurology with Experimental Neurology, Charité - Universitätsmedizin Berlin, Corporate Member of Freie Universität Berlin, Humboldt-Universität zu Berlin and Berlin Institute of Health, Berlin, Germany.,Epilepsy-Center Berlin-Brandenburg, Institute for Diagnostics of Epilepsy, Berlin, Germany
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Winter MJ, Pinion J, Tochwin A, Takesono A, Ball JS, Grabowski P, Metz J, Trznadel M, Tse K, Redfern WS, Hetheridge MJ, Goodfellow M, Randall AD, Tyler CR. Functional brain imaging in larval zebrafish for characterising the effects of seizurogenic compounds acting via a range of pharmacological mechanisms. Br J Pharmacol 2021; 178:2671-2689. [PMID: 33768524 DOI: 10.1111/bph.15458] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/14/2020] [Revised: 02/17/2021] [Accepted: 03/14/2021] [Indexed: 01/18/2023] Open
Abstract
BACKGROUND AND PURPOSE Functional brain imaging using genetically encoded Ca2+ sensors in larval zebrafish is being developed for studying seizures and epilepsy as a more ethical alternative to rodent models. Despite this, few data have been generated on pharmacological mechanisms of action other than GABAA antagonism. Assessing larval responsiveness across multiple mechanisms is vital to test the translational power of this approach, as well as assessing its validity for detecting unwanted drug-induced seizures and testing antiepileptic drug efficacy. EXPERIMENTAL APPROACH Using light-sheet imaging, we systematically analysed the responsiveness of 4 days post fertilisation (dpf; which are not considered protected under European animal experiment legislation) transgenic larval zebrafish to treatment with 57 compounds spanning more than 12 drug classes with a link to seizure generation in mammals, alongside eight compounds with no such link. KEY RESULTS We show 4dpf zebrafish are responsive to a wide range of mechanisms implicated in seizure generation, with cerebellar circuitry activated regardless of the initiating pharmacology. Analysis of functional connectivity revealed compounds targeting cholinergic and monoaminergic reuptake, in particular, showed phenotypic consistency broadly mapping onto what is known about neurotransmitter-specific circuitry in the larval zebrafish brain. Many seizure-associated compounds also exhibited altered whole brain functional connectivity compared with controls. CONCLUSIONS AND IMPLICATIONS This work represents a significant step forward in understanding the translational power of 4dpf larval zebrafish for use in neuropharmacological studies and for studying the events driving transition from small-scale pharmacological activation of local circuits, to the large network-wide abnormal synchronous activity associated with seizures.
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Affiliation(s)
- Matthew J Winter
- Biosciences, College of Life and Environmental Sciences, University of Exeter, Exeter, Devon, UK
| | - Joseph Pinion
- Biosciences, College of Life and Environmental Sciences, University of Exeter, Exeter, Devon, UK
| | - Anna Tochwin
- Biosciences, College of Life and Environmental Sciences, University of Exeter, Exeter, Devon, UK
| | - Aya Takesono
- Biosciences, College of Life and Environmental Sciences, University of Exeter, Exeter, Devon, UK
| | - Jonathan S Ball
- Biosciences, College of Life and Environmental Sciences, University of Exeter, Exeter, Devon, UK
| | - Piotr Grabowski
- Data Science and Artificial Intelligence, Clinical Pharmacology & Safety Sciences, AstraZeneca R&D, Cambridge, UK
| | - Jeremy Metz
- Biosciences, College of Life and Environmental Sciences, University of Exeter, Exeter, Devon, UK
| | - Maciej Trznadel
- Biosciences, College of Life and Environmental Sciences, University of Exeter, Exeter, Devon, UK
| | - Karen Tse
- Safety & Mechanistic Pharmacology, Clinical Pharmacology & Safety Sciences, AstraZeneca R&D, Cambridge, UK
- Sovereign House, GW Pharmaceuticals plc, Cambridge, UK
| | - Will S Redfern
- Safety & Mechanistic Pharmacology, Clinical Pharmacology & Safety Sciences, AstraZeneca R&D, Cambridge, UK
- Simcyp Division, Certara UK Limited, Sheffield, UK
| | - Malcolm J Hetheridge
- Biosciences, College of Life and Environmental Sciences, University of Exeter, Exeter, Devon, UK
| | - Marc Goodfellow
- Department of Mathematics & Living Systems Institute and EPSRC Centre for Predictive Modelling in Healthcare, University of Exeter, Exeter, Devon, UK
| | - Andrew D Randall
- University of Exeter Medical School, University of Exeter, Exeter, Devon, UK
| | - Charles R Tyler
- Biosciences, College of Life and Environmental Sciences, University of Exeter, Exeter, Devon, UK
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Bertoglio D, Amhaoul H, Goossens J, Ali I, Jonckers E, Bijnens T, Siano M, Wyffels L, Verhaeghe J, Van der Linden A, Staelens S, Dedeurwaerdere S. TSPO PET upregulation predicts epileptic phenotype at disease onset independently from chronic TSPO expression in a rat model of temporal lobe epilepsy. Neuroimage Clin 2021; 31:102701. [PMID: 34090124 PMCID: PMC8182303 DOI: 10.1016/j.nicl.2021.102701] [Citation(s) in RCA: 6] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/03/2021] [Revised: 05/10/2021] [Accepted: 05/14/2021] [Indexed: 12/12/2022]
Abstract
Neuroinflammation is a key component of epileptogenesis, the process leading to acquired epilepsy. In recent years, with the development of non-invasive in vivo positron emission tomography (PET) imaging of translocator protein 18 kDa (TSPO), a marker of neuroinflammation, it has become possible to perform longitudinal studies to characterize neuroinflammation at different disease stages in animal models of epileptogenesis. This study aimed to utilize the prognostic capability of TSPO PET imaging at disease onset (2 weeks post-SE) to categorize epileptic rats with distinct seizure burden based on TSPO levels at disease onset and investigate their association to TSPO expression at the chronic epilepsy stage. Controls (n = 14) and kainic acid-induced status epilepticus (KASE) rats (n = 41) were scanned non-invasively with [18F]PBR111 PET imaging measuring TSPO expression. Animals were monitored using video-electroencephalography (vEEG) up to chronic disease (12 weeks post-SE), at which TSPO levels ([3H]PK11195) as well as other post-mortem abnormalities (namely synaptic density ([3H]UCB-J), neuronal loss (NeuN), and neurodegeneration (FjC)) were investigated. By applying multivariate analysis, TSPO PET imaging at disease onset identified three KASE groups with significantly different spontaneous recurrent seizures (SRS) burden (defined as rare SRS, sporadic SRS, and frequent SRS) (p = 0.003). Interestingly, TSPO levels were significantly different when comparing the three KASE groups (p < 0.0001), with the frequent SRS group characterized only by a limited focal TSPO increase at disease onset. On the contrary, TSPO measured during chronic epilepsy was found to be the highest in the frequent SRS group and correlated with seizure burden (r = 0.826, p < 0.0001). Importantly, early and chronic TSPO levels did not correlate (r = -0.05). Finally, significant pathological changes in neuronal loss, synaptic density, and neurodegeneration were found not only when compared to control animals (p < 0.01), but also between the three KASE rat categories in the hippocampus (p < 0.05). Early and chronic TSPO upregulation following epileptogenic insult appear to be driven by two superimposed dynamic processes. The former is associated with epileptogenesis as measured at disease onset, while the latter is related to seizure frequency as quantified during chronic epilepsy.
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Affiliation(s)
- Daniele Bertoglio
- Molecular Imaging Center Antwerp, University of Antwerp, Belgium; Department of Translational Neurosciences, University of Antwerp, Belgium.
| | - Halima Amhaoul
- Department of Translational Neurosciences, University of Antwerp, Belgium
| | - Joery Goossens
- Department of Translational Neurosciences, University of Antwerp, Belgium
| | - Idrish Ali
- Department of Translational Neurosciences, University of Antwerp, Belgium
| | | | - Tom Bijnens
- Department of Translational Neurosciences, University of Antwerp, Belgium
| | - Matteo Siano
- Department of Translational Neurosciences, University of Antwerp, Belgium
| | - Leonie Wyffels
- Molecular Imaging Center Antwerp, University of Antwerp, Belgium; Department of Nuclear Medicine, Antwerp University Hospital, Edegem, Belgium
| | - Jeroen Verhaeghe
- Molecular Imaging Center Antwerp, University of Antwerp, Belgium
| | | | - Steven Staelens
- Department of Translational Neurosciences, University of Antwerp, Belgium
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Karoly PJ, Rao VR, Gregg NM, Worrell GA, Bernard C, Cook MJ, Baud MO. Cycles in epilepsy. Nat Rev Neurol 2021; 17:267-284. [PMID: 33723459 DOI: 10.1038/s41582-021-00464-1] [Citation(s) in RCA: 119] [Impact Index Per Article: 39.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 01/19/2021] [Indexed: 01/31/2023]
Abstract
Epilepsy is among the most dynamic disorders in neurology. A canonical view holds that seizures, the characteristic sign of epilepsy, occur at random, but, for centuries, humans have looked for patterns of temporal organization in seizure occurrence. Observations that seizures are cyclical date back to antiquity, but recent technological advances have, for the first time, enabled cycles of seizure occurrence to be quantitatively characterized with direct brain recordings. Chronic recordings of brain activity in humans and in animals have yielded converging evidence for the existence of cycles of epileptic brain activity that operate over diverse timescales: daily (circadian), multi-day (multidien) and yearly (circannual). Here, we review this evidence, synthesizing data from historical observational studies, modern implanted devices, electronic seizure diaries and laboratory-based animal neurophysiology. We discuss advances in our understanding of the mechanistic underpinnings of these cycles and highlight the knowledge gaps that remain. The potential clinical applications of a knowledge of cycles in epilepsy, including seizure forecasting and chronotherapy, are discussed in the context of the emerging concept of seizure risk. In essence, this Review addresses the broad question of why seizures occur when they occur.
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Affiliation(s)
- Philippa J Karoly
- Graeme Clark Institute, The University of Melbourne, Melbourne, Victoria, Australia.
| | - Vikram R Rao
- Department of Neurology, University of California, San Francisco, CA, USA.,Weill Institute for Neurosciences, University of California, San Francisco, CA, USA
| | - Nicholas M Gregg
- Bioelectronics, Neurophysiology and Engineering Laboratory, Department of Neurology, Mayo Clinic, Rochester, MN, USA
| | - Gregory A Worrell
- Bioelectronics, Neurophysiology and Engineering Laboratory, Department of Neurology, Mayo Clinic, Rochester, MN, USA
| | - Christophe Bernard
- Aix Marseille University, Inserm, Institut de Neurosciences des Systèmes, Marseille, France
| | - Mark J Cook
- Graeme Clark Institute, The University of Melbourne, Melbourne, Victoria, Australia
| | - Maxime O Baud
- Sleep-Wake-Epilepsy Center, Department of Neurology, Inselspital Bern, University Hospital, University of Bern, Bern, Switzerland. .,Center for Experimental Neurology, Department of Neurology, Inselspital Bern, University Hospital, University of Bern, Bern, Switzerland.
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Girardi-Schappo M, Fadaie F, Lee HM, Caldairou B, Sziklas V, Crane J, Bernhardt BC, Bernasconi A, Bernasconi N. Altered communication dynamics reflect cognitive deficits in temporal lobe epilepsy. Epilepsia 2021; 62:1022-1033. [PMID: 33705572 DOI: 10.1111/epi.16864] [Citation(s) in RCA: 20] [Impact Index Per Article: 6.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/22/2020] [Revised: 02/15/2021] [Accepted: 02/15/2021] [Indexed: 12/23/2022]
Abstract
OBJECTIVE Although temporal lobe epilepsy (TLE) is recognized as a system-level disorder, little work has investigated pathoconnectomics from a dynamic perspective. By leveraging computational simulations that quantify patterns of information flow across the connectome, we tested the hypothesis that network communication is abnormal in this condition, studied the interplay between hippocampal- and network-level disease effects, and assessed associations with cognition. METHODS We simulated signal spreading via a linear threshold model that temporally evolves on a structural graph derived from diffusion-weighted magnetic resonance imaging (MRI), comparing a homogeneous group of 31 patients with histologically proven hippocampal sclerosis to 31 age- and sex-matched healthy controls. We evaluated the modulatory effects of structural alterations of the neocortex and hippocampus on network dynamics. Furthermore, multivariate statistics addressed the relationship with cognitive parameters. RESULTS We observed a slowing of in- and out-spreading times across multiple areas bilaterally, indexing delayed information flow, with the strongest effects in ipsilateral frontotemporal regions, thalamus, and hippocampus. Effects were markedly reduced when controlling for hippocampal volume but not cortical thickness, underscoring the central role of the hippocampus in whole-brain disease expression. Multivariate analysis associated slower spreading time in frontoparietal, limbic, default mode, and subcortical networks with impairment across tasks tapping into sensorimotor, executive, memory, and verbal abilities. SIGNIFICANCE Moving beyond descriptions of static topology toward the formulation of brain dynamics, our work provides novel insight into structurally mediated network dysfunction and demonstrates that altered whole-brain communication dynamics contribute to common cognitive difficulties in TLE.
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Affiliation(s)
- Mauricio Girardi-Schappo
- Neuroimaging of Epilepsy Laboratory, McConnell Brain Imaging Center, Montreal Neurological Institute and Hospital, McGill University, Montreal, QC, Canada
| | - Fatemeh Fadaie
- Neuroimaging of Epilepsy Laboratory, McConnell Brain Imaging Center, Montreal Neurological Institute and Hospital, McGill University, Montreal, QC, Canada
| | - Hyo Min Lee
- Neuroimaging of Epilepsy Laboratory, McConnell Brain Imaging Center, Montreal Neurological Institute and Hospital, McGill University, Montreal, QC, Canada
| | - Benoit Caldairou
- Neuroimaging of Epilepsy Laboratory, McConnell Brain Imaging Center, Montreal Neurological Institute and Hospital, McGill University, Montreal, QC, Canada
| | - Viviane Sziklas
- Department of Neurology and Neurosurgery, Montreal Neurological Institute and Hospital, McGill University, Montreal, QC, Canada
| | - Joelle Crane
- Department of Neurology and Neurosurgery, Montreal Neurological Institute and Hospital, McGill University, Montreal, QC, Canada
| | - Boris C Bernhardt
- Multimodal Imaging and Connectome Analysis Lab, McConnell Brain Imaging Center, Montreal Neurological Institute and Hospital, McGill University, Montreal, QC, Canada
| | - Andrea Bernasconi
- Neuroimaging of Epilepsy Laboratory, McConnell Brain Imaging Center, Montreal Neurological Institute and Hospital, McGill University, Montreal, QC, Canada
| | - Neda Bernasconi
- Neuroimaging of Epilepsy Laboratory, McConnell Brain Imaging Center, Montreal Neurological Institute and Hospital, McGill University, Montreal, QC, Canada
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Kreilkamp BAK, McKavanagh A, Alonazi B, Bryant L, Das K, Wieshmann UC, Marson AG, Taylor PN, Keller SS. Altered structural connectome in non-lesional newly diagnosed focal epilepsy: Relation to pharmacoresistance. Neuroimage Clin 2021; 29:102564. [PMID: 33508622 PMCID: PMC7841400 DOI: 10.1016/j.nicl.2021.102564] [Citation(s) in RCA: 11] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/11/2020] [Revised: 01/10/2021] [Accepted: 01/11/2021] [Indexed: 12/19/2022]
Abstract
Despite an expanding literature on brain alterations in patients with longstanding epilepsy, few neuroimaging studies investigate patients with newly diagnosed focal epilepsy (NDfE). Understanding brain network impairments at diagnosis is necessary to elucidate whether or not brain abnormalities are principally due to the chronicity of the disorder and to develop prognostic markers of treatment outcome. Most adults with NDfE do not have MRI-identifiable lesions and the reasons for seizure onset and refractoriness are unknown. We applied structural connectomics to T1-weighted and multi-shell diffusion MRI data with generalized q-sampling image reconstruction using Network Based Statistics (NBS). We scanned 27 patients within an average of 3.7 (SD = 2.9) months of diagnosis and anti-epileptic drug treatment outcomes were collected 24 months after diagnosis. Seven patients were excluded due to lesional NDfE and outcome data was available in 17 patients. Compared to 29 healthy controls, patients with non-lesional NDfE had connectomes with significantly decreased quantitative anisotropy in edges connecting right temporal, frontal and thalamic nodes and increased diffusivity in edges between bilateral temporal, frontal, occipital and parietal nodes. Compared to controls, patients with persistent seizures showed the largest effect size (|d|>=1) for decreased anisotropy in right parietal edges and increased diffusivity in edges between left thalamus and left parietal nodes. Compared to controls, patients who were rendered seizure-free showed the largest effect size for decreased anisotropy in the edge connecting the left thalamus and right temporal nodes and increased diffusivity in edges connecting right frontal nodes. As demonstrated by large effect sizes, connectomes with decreased anisotropy (edge between right frontal and left insular nodes) and increased diffusivity (edge between right thalamus and left parietal nodes) were found in patients with persistent seizures compared to patients who became seizure-free. Patients who had persistent seizures showed larger effect sizes in all network metrics than patients who became seizure-free when compared to each other and compared to controls. Furthermore, patients with focal-to-bilateral tonic-clonic seizures (FBTCS, N = 11) had decreased quantitative anisotropy in a bilateral network involving edges between temporal, parietal and frontal nodes with greater effect sizes than those of patients without FBTCS (N = 9). NBS findings between patients and controls indicated that structural network changes are not necessarily a consequence of longstanding refractory epilepsy and instead are present at the time of diagnosis. Computed effect sizes suggest that there may be structural network MRI-markers of future pharmacoresistance and seizure severity in patients with a new diagnosis of focal epilepsy.
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Affiliation(s)
- Barbara A K Kreilkamp
- Department of Pharmacology & Therapeutics, Institute of Systems, Molecular and Integrative Biology, University of Liverpool, Liverpool, UK; Department of Neuroradiology, The Walton Centre NHS Foundation Trust, Liverpool, UK; Department of Clinical Neurophysiology, University Medicine Göttingen, Göttingen, Germany.
| | - Andrea McKavanagh
- Department of Pharmacology & Therapeutics, Institute of Systems, Molecular and Integrative Biology, University of Liverpool, Liverpool, UK; Department of Neuroradiology, The Walton Centre NHS Foundation Trust, Liverpool, UK
| | - Batil Alonazi
- Department of Radiology and Medical Imaging, Prince Sattam Bin Abdulaziz University, Al Kharj, Saudi Arabia
| | - Lorna Bryant
- Department of Pharmacology & Therapeutics, Institute of Systems, Molecular and Integrative Biology, University of Liverpool, Liverpool, UK; Department of Neuroradiology, The Walton Centre NHS Foundation Trust, Liverpool, UK
| | - Kumar Das
- Department of Neuroradiology, The Walton Centre NHS Foundation Trust, Liverpool, UK
| | - Udo C Wieshmann
- Department of Neuroradiology, The Walton Centre NHS Foundation Trust, Liverpool, UK
| | - Anthony G Marson
- Department of Pharmacology & Therapeutics, Institute of Systems, Molecular and Integrative Biology, University of Liverpool, Liverpool, UK; Department of Neuroradiology, The Walton Centre NHS Foundation Trust, Liverpool, UK
| | - Peter N Taylor
- CNNP Lab, Interdisciplinary Computing and Complex BioSystems Group, School of Computing, Newcastle University, UK; UCL Queen Square Institute of Neurology, Queen Square, London, UK
| | - Simon S Keller
- Department of Pharmacology & Therapeutics, Institute of Systems, Molecular and Integrative Biology, University of Liverpool, Liverpool, UK; Department of Neuroradiology, The Walton Centre NHS Foundation Trust, Liverpool, UK
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Foit NA, Bernasconi A, Ladbon-Bernasconi N. Contributions of Imaging to Neuromodulatory Treatment of Drug-Refractory Epilepsy. Brain Sci 2020; 10:E700. [PMID: 33023078 PMCID: PMC7601437 DOI: 10.3390/brainsci10100700] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/02/2020] [Revised: 09/23/2020] [Accepted: 09/26/2020] [Indexed: 12/17/2022] Open
Abstract
Epilepsy affects about 1% of the world's population, and up to 30% of all patients will ultimately not achieve freedom from seizures with anticonvulsive medication alone. While surgical resection of a magnetic resonance imaging (MRI) -identifiable lesion remains the first-line treatment option for drug-refractory epilepsy, surgery cannot be offered to all. Neuromodulatory therapy targeting "seizures" instead of "epilepsy" has emerged as a valuable treatment option for these patients, including invasive procedures such as deep brain stimulation (DBS), responsive neurostimulation (RNS) and peripheral approaches such as vagus nerve stimulation (VNS). The purpose of this review is to provide in-depth information on current concepts and evidence on network-level aspects of drug-refractory epilepsy. We reviewed the current evidence gained from studies utilizing advanced imaging methodology, with a specific focus on their contributions to neuromodulatory therapy.
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Affiliation(s)
- Niels Alexander Foit
- Neuroimaging of Epilepsy Laboratory, McConnell Brain Imaging Centre, Montreal Neurological Institute and Hospital, McGill University, Montreal, QC H3A2B4, Canada; (A.B.); (N.L.-B.)
- Department of Neurosurgery, Medical Center–University of Freiburg, Faculty of Medicine, D-79106 Freiburg, Germany
| | - Andrea Bernasconi
- Neuroimaging of Epilepsy Laboratory, McConnell Brain Imaging Centre, Montreal Neurological Institute and Hospital, McGill University, Montreal, QC H3A2B4, Canada; (A.B.); (N.L.-B.)
| | - Neda Ladbon-Bernasconi
- Neuroimaging of Epilepsy Laboratory, McConnell Brain Imaging Centre, Montreal Neurological Institute and Hospital, McGill University, Montreal, QC H3A2B4, Canada; (A.B.); (N.L.-B.)
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Foit NA, Bernasconi A, Bernasconi N. Functional Networks in Epilepsy Presurgical Evaluation. Neurosurg Clin N Am 2020; 31:395-405. [PMID: 32475488 DOI: 10.1016/j.nec.2020.03.004] [Citation(s) in RCA: 11] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/24/2022]
Abstract
Continuing advancements in neuroimaging methodology allow for increasingly detailed in vivo characterization of structural and functional brain networks, leading to the recognition of epilepsy as a disorder of large-scale networks. In surgical candidates, analysis of functional networks has proved invaluable for the identification of eloquent brain areas, such as hemispherical language dominance. More recently, connectome-based biomarkers have demonstrated potential to further inform clinical decision making in drug-refractory epilepsy. This article summarizes current evidence on epilepsy as a network disorder, emphasizing potential benefits of network analysis techniques for preoperative assessments and resection planning.
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Affiliation(s)
- Niels Alexander Foit
- Neuroimaging of Epilepsy Laboratory, McConnell Brain Imaging Centre, Montreal Neurological Institute and Hospital, McGill University, 3801 Rue Université, Montreal, Quebec H3A 2B4, Canada
| | - Andrea Bernasconi
- Neuroimaging of Epilepsy Laboratory, McConnell Brain Imaging Centre, Montreal Neurological Institute and Hospital, McGill University, 3801 Rue Université, Montreal, Quebec H3A 2B4, Canada
| | - Neda Bernasconi
- Neuroimaging of Epilepsy Laboratory, McConnell Brain Imaging Centre, Montreal Neurological Institute and Hospital, McGill University, 3801 Rue Université, Montreal, Quebec H3A 2B4, Canada.
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Abstract
Temporal lobe epilepsy (TLE) is the most common type of drug-resistant focal epilepsy. Epilepsy can be conceptualized as a network disorder with the epileptogenic zone a critical node of the network. Temporal lobe networks can be identified on the microscale and macroscale, both during the interictal and ictal periods. This review summarizes the current understanding of TLE networks as studied by neurophysiological and imaging techniques discussing both functional and structural connectivity.
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