1
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Autonomic nerve activity and cardiovascular changes during discrete seizures in rats. Auton Neurosci 2022; 240:102971. [DOI: 10.1016/j.autneu.2022.102971] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/01/2021] [Revised: 02/18/2022] [Accepted: 03/12/2022] [Indexed: 11/22/2022]
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2
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Acute and chronic cardiorespiratory consequences of focal intrahippocampal administration of seizure-inducing agents. Implications for SUDEP. Auton Neurosci 2021; 235:102864. [PMID: 34428716 DOI: 10.1016/j.autneu.2021.102864] [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: 02/19/2021] [Revised: 07/02/2021] [Accepted: 07/26/2021] [Indexed: 11/20/2022]
Abstract
The risk factors for SUDEP are undoubtedly heterogenous but the main factor is the frequency of generalized tonic-clonic seizures with apnoea and/or cardiac abnormalities likely precipitating the lethal event. By its very nature modelling SUDEP experimentally is challenging, yet insights into the nature of the lethal event and precipitating factors are vital in order to understand and prevent fatalities. Acute animal models, which induce status epilepticus (SE), can be used to help understand pathophysiological processes during and following seizures, which sometimes lead to death. The most commonly used method to induce seizures and status epilepticus is systemic administration of an ictogenic agent. Microinjection of such agents into restricted regions within the brain induces a more localised epileptic focus and circumvents the risk of direct actions on cardiorespiratory control centres. Both approaches have revealed substantial cardiovascular and respiratory consequences, including death as a result of apnoea, which may be of central origin, obstructive due to laryngospasm or, at least in genetically modified mice, a result of spreading depolarisation to medullary respiratory control centres. SUDEP is by definition a result of epilepsy, which in turn is diagnosed on the basis of two or more unprovoked seizures. The incidence of tonic-clonic seizures is the main risk factor, raising the possibility that repeated seizures cause cumulative pathological and/or pathophysiological changes that contribute to the risk of SUDEP. Chronic experimental models, which induce repeated seizures that in some cases lead to death, do show progressive development of pathophysiological changes in the myocardium, e.g. prolongation of QT the interval of the ECG or, over longer periods, ventricular hypertrophy. However, the currently available evidence indicates that seizure-related deaths are primarily due to apnoeas, but cardiac factors, particularly cumulative cardiac pathophysiologies due to repeated seizures, are potential contributing factors.
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3
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Stewart M, Silverman JB, Sundaram K, Kollmar R. Causes and Effects Contributing to Sudden Death in Epilepsy and the Rationale for Prevention and Intervention. Front Neurol 2020; 11:765. [PMID: 32849221 PMCID: PMC7411179 DOI: 10.3389/fneur.2020.00765] [Citation(s) in RCA: 11] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/13/2020] [Accepted: 06/22/2020] [Indexed: 12/15/2022] Open
Abstract
Sudden unexpected death in epilepsy (SUDEP) claims the lives of one in every thousand epileptic patients each year. Autonomic, cardiac, and respiratory pieces to a mechanistic puzzle have not yet been completely assembled. We propose a single sequence of causes and effects that unifies disparate and competitive concepts into a single algorithm centered on ictal obstructive apnea. Based on detailed animal studies that are sometimes impossible in humans, and striking parallels with a growing body of clinical examples, this framework (1) accounts for the autonomic, cardiac, and respiratory data to date by showing the causal relationships between specific elements, and (2) highlights specific kinds of data that can be used to precisely classify various patient outcomes. The framework also justifies a “near miss” designation to be applied to any cases with evidence of obstructive apnea even, and perhaps especially, in individuals that do not require resuscitation. Lastly, the rationale for preventative oxygen therapy is demonstrated. With better mechanistic understanding of SUDEP, we suggest changes for detection and classification to increase survival rates and improve risk stratification.
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Affiliation(s)
- Mark Stewart
- Department of Neurology, State University of New York Health Sciences University, Brooklyn, NY, United States.,Department of Physiology & Pharmacology, State University of New York Health Sciences University, Brooklyn, NY, United States
| | - Joshua B Silverman
- Department of Otolaryngology, North Shore Long Island Jewish Medical Center, New Hyde Park, NY, United States
| | - Krishnamurthi Sundaram
- Department of Otolaryngology, State University of New York Health Sciences University, Brooklyn, NY, United States
| | - Richard Kollmar
- Department of Otolaryngology, State University of New York Health Sciences University, Brooklyn, NY, United States.,Department of Cell Biology, State University of New York Health Sciences University, Brooklyn, NY, United States
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Jefferys JGR, Ashby‐Lumsden A, Lovick TA. Cardiac effects of repeated focal seizures in rats induced by intrahippocampal tetanus toxin: Bradyarrhythmias, tachycardias, and prolonged interictal QT interval. Epilepsia 2020; 61:798-809. [DOI: 10.1111/epi.16479] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/07/2019] [Revised: 02/24/2020] [Accepted: 02/24/2020] [Indexed: 11/30/2022]
Affiliation(s)
- John G. R. Jefferys
- Department of Pharmacology Oxford University Oxford UK
- School of Clinical & Experimental Medicine The University of Birmingham Birmingham UK
- School of Biomedical Engineering Purdue University West Lafayette Indiana
- Department of Physiology 2nd Medical School Motol, Charles University Prague Czech Republic
| | - Alexander Ashby‐Lumsden
- Department of Pharmacology Oxford University Oxford UK
- School of Clinical & Experimental Medicine The University of Birmingham Birmingham UK
| | - Thelma A. Lovick
- School of Biomedical Engineering Purdue University West Lafayette Indiana
- School of Physiology, Pharmacology and Neuroscience The University of Bristol Bristol UK
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Jefferys JGR, Arafat MA, Irazoqui PP, Lovick TA. Brainstem activity, apnea, and death during seizures induced by intrahippocampal kainic acid in anaesthetized rats. Epilepsia 2019; 60:2346-2358. [PMID: 31705531 DOI: 10.1111/epi.16374] [Citation(s) in RCA: 20] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/01/2019] [Revised: 09/25/2019] [Accepted: 10/04/2019] [Indexed: 11/30/2022]
Affiliation(s)
- John G. R. Jefferys
- Weldon School of Biomedical Engineering Purdue University West Lafayette IN USA
- Department of Pharmacology Oxford University Oxford UK
| | - Muhammad A. Arafat
- Weldon School of Biomedical Engineering Purdue University West Lafayette IN USA
- Department of Electrical and Computer Engineering Purdue University West Lafayette IN USA
| | - Pedro P. Irazoqui
- Weldon School of Biomedical Engineering Purdue University West Lafayette IN USA
- Department of Electrical and Computer Engineering Purdue University West Lafayette IN USA
| | - Thelma A. Lovick
- Weldon School of Biomedical Engineering Purdue University West Lafayette IN USA
- School of Physiology, Pharmacology and Neuroscience University of Bristol Bristol UK
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Stewart M. An explanation for sudden death in epilepsy (SUDEP). J Physiol Sci 2018; 68:307-320. [PMID: 29542031 PMCID: PMC10717429 DOI: 10.1007/s12576-018-0602-z] [Citation(s) in RCA: 21] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/05/2017] [Accepted: 03/06/2018] [Indexed: 01/02/2023]
Abstract
This review traces the examination of autonomic, cardiovascular, and respiratory derangements associated with seizure activity in the clinical and preclinical literature generally, and in the author's animal model specifically, and concludes with the author's views on the potential mechanisms for sudden death in epilepsy (SUDEP). An animal model that employs kainic acid-induced seizures on a background of urethane anesthesia has permitted unprecedented access to the behavior of autonomic, cardiovascular, and respiratory systems during seizure activity. The result is a detailed description of the major causes of death and how this animal model can be used to develop and test preventative and interventional strategies. A critical translational step was taken when the rat data were shown to directly parallel data from definite SUDEP cases in the clinical literature. The reasons why ventricular fibrillation as a cause of death is so rarely reported and tools for verifying that seizure-associated laryngospasm can induce obstructive apnea as a cause of death are discussed in detail. Many details of the specific kinetics of activation of brainstem neurons serving autonomic and respiratory function remain to be elucidated, but the boundary conditions described in this review provide an excellent framework for more focused studies. A number of studies conducted in animal models of seizure activity and in epilepsy patients have contributed information on the autonomic, cardiovascular, and respiratory consequences of seizure activity spreading through hypothalamus and brainstem to the periphery. The result is detailed information on the systemic impact of seizure spread and the development of an understanding of the essential mechanistic features of sudden unexpected death in epilepsy (SUDEP). This review summarizes translation of data obtained from animal models to biomarkers that are useful in evaluating data from epilepsy patients.
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Affiliation(s)
- Mark Stewart
- Department of Physiology and Pharmacology, State University of New York Downstate Medical Center, 450 Clarkson Avenue, Brooklyn, NY, 11203, USA.
- Department of Neurology, State University of New York Downstate Medical Center, 450 Clarkson Avenue, Brooklyn, NY, 11203, USA.
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7
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Stewart M. Reader response: Wrist sensor reveals sympathetic hyperactivity and hypoventilation before probable SUDEP. Neurology 2018; 90:712-713. [DOI: 10.1212/wnl.0000000000005286] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/15/2022] Open
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8
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Read MI, Millen RN, McCann DM, Harrison JC, Kerr DS, Sammut IA. Improved cardiac outcomes with combined atenolol and diazepam intervention in seizure. Epilepsia 2018. [DOI: 10.1111/epi.14039] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/31/2023]
Affiliation(s)
- Morgayn I. Read
- Department of Pharmacology and Toxicology; University of Otago School of Medical Sciences; Dunedin New Zealand
| | - Rebecca N. Millen
- Department of Pharmacology and Toxicology; University of Otago School of Medical Sciences; Dunedin New Zealand
| | - Dominic M. McCann
- Department of Pharmacology and Toxicology; University of Otago School of Medical Sciences; Dunedin New Zealand
| | - Joanne C. Harrison
- Department of Pharmacology and Toxicology; University of Otago School of Medical Sciences; Dunedin New Zealand
| | - Douglas S. Kerr
- Department of Pharmacology and Toxicology; University of Otago School of Medical Sciences; Dunedin New Zealand
| | - Ivan A. Sammut
- Department of Pharmacology and Toxicology; University of Otago School of Medical Sciences; Dunedin New Zealand
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Rodrigues FL, Fais RS, Pereira MGAG, Garcia-Cairasco N, Tostes RC, Carneiro FS. Erectile Dysfunction in Wistar Audiogenic Rats Is Associated With Increased Cavernosal Contraction and Decreased Neuronal Nitric Oxide Synthase Protein Expression. Urology 2017; 106:237.e1-237.e8. [PMID: 28483592 DOI: 10.1016/j.urology.2017.04.048] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/04/2017] [Revised: 04/18/2017] [Accepted: 04/30/2017] [Indexed: 11/18/2022]
Abstract
OBJECTIVE To test the hypothesis that naive Wistar audiogenic rats (WARs) display erectile dysfunction (ED), which is associated with increased sympathetic-mediated contractile tone and decreased nitric oxide-mediated relaxation responses of the cavernous tissue. METHODS Changes in the ratio of the maximal intracavernosal pressure-mean arterial pressure after the electrical stimulation of the right major pelvic ganglion were determined in vivo. Cavernosal contractility was induced by electrical field stimulation and phenylephrine. In addition, nonadrenergic-noncholinergic (NANC)-induced relaxation was determined. Rho-kinase (ROCK) pathway proteins, neuronal nitric oxide synthase (nNOS) protein expression, and endothelial nitric oxide synthase (eNOS) and extracellular signal-regulated kinase 1/2 activities were determined by Western blot. RESULTS WARs display a significant decrease in maximal intracavernosal pressure-mean arterial pressure responses suggesting ED in this strain. Sympathetic-mediated contractile responses were increased in WARs and contractile responses to phenylephrine were not changed. The increased sympathetic-mediated contractile responses were not associated with changes in the ROCK pathway. On the other hand, NANC-mediated relaxation responses were significantly reduced in WARs. This functional response was accompanied by decreased nNOS and total eNOS protein expressions, augmented phosphorylated eNOS, and decreased extracellular signal-regulated kinase 1/2 phosphorylation levels. CONCLUSION Our data have demonstrated that naive WARs display ED in vivo that is associated with increased sympathetic-mediated contractile responses and decreased NANC-mediated relaxation responses. The increase in contractile responses is independent of the ROCK pathway, and the changes in relaxation responses are associated with a decrease in nNOS protein expression, which may activate compensatory mechanisms in the cavernous tissue.
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Affiliation(s)
- Fernanda Luciano Rodrigues
- Department of Pharmacology, Ribeirao Preto Medical School, University of Sao Paulo, Ribeirao Preto, São Paulo, Brazil
| | - Rafael S Fais
- Department of Pharmacology, Ribeirao Preto Medical School, University of Sao Paulo, Ribeirao Preto, São Paulo, Brazil
| | - Marília G A G Pereira
- Department of Biochemistry, Biomedical Sciences Institute, University of Alfenas, Alfenas, Minas Gerais, Brazil
| | - Norberto Garcia-Cairasco
- Department of Physiology, Ribeirao Preto Medical School, University of Sao Paulo, Ribeirao Preto, São Paulo, Brazil
| | - Rita C Tostes
- Department of Pharmacology, Ribeirao Preto Medical School, University of Sao Paulo, Ribeirao Preto, São Paulo, Brazil
| | - Fernando S Carneiro
- Department of Pharmacology, Ribeirao Preto Medical School, University of Sao Paulo, Ribeirao Preto, São Paulo, Brazil.
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Stewart M, Kollmar R, Nakase K, Silverman J, Sundaram K, Orman R, Lazar J. Obstructive apnea due to laryngospasm links ictal to postictal events in SUDEP cases and offers practical biomarkers for review of past cases and prevention of new ones. Epilepsia 2017; 58:e87-e90. [PMID: 28464295 DOI: 10.1111/epi.13765] [Citation(s) in RCA: 38] [Impact Index Per Article: 5.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 03/25/2017] [Indexed: 11/29/2022]
Abstract
Seizure spread into autonomic and respiratory brainstem regions is thought to play an important role in sudden unexpected death in epilepsy (SUDEP). As the clinical dataset of cases of definite SUDEP available for study grows, evidence points to a sequence of events that includes postictal apnea, bradycardia, and asystole as critical events that can lead to death. One possible link between the precipitating seizure and the critical postictal sequence is seizure-driven laryngospasm sufficient to completely obstruct the airway for an extended period, but ictal laryngospasm is difficult to fully assess. Herein, we demonstrate in a rat model how the electrical artifacts of attempts to inspire during airway obstruction and features of the cardiac rhythm establish this link between ictal and postictal activity and can be used as practical biomarkers of obstructive apnea due to laryngospasm or other causes of airway obstruction.
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Affiliation(s)
- Mark Stewart
- Department of Neurology, SUNY Downstate Medical Center, Brooklyn, New York, U.S.A.,Department of Physiology/Pharmacology, SUNY Downstate Medical Center, Brooklyn, New York, U.S.A
| | - Richard Kollmar
- Department of Cell Biology, SUNY Downstate Medical Center, Brooklyn, New York, U.S.A.,Department of Otolaryngology, SUNY Downstate Medical Center, Brooklyn, New York, U.S.A
| | - Ko Nakase
- Department of Physiology/Pharmacology, SUNY Downstate Medical Center, Brooklyn, New York, U.S.A
| | - Joshua Silverman
- Department of Otolaryngology, SUNY Downstate Medical Center, Brooklyn, New York, U.S.A
| | | | - Rena Orman
- Department of Physiology/Pharmacology, SUNY Downstate Medical Center, Brooklyn, New York, U.S.A
| | - Jason Lazar
- Department of Medicine, SUNY Downstate Medical Center, Brooklyn, New York, U.S.A
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11
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Nakase K, Kollmar R, Lazar J, Arjomandi H, Sundaram K, Silverman J, Orman R, Weedon J, Stefanov D, Savoca E, Tordjman L, Stiles K, Ihsan M, Nunez A, Guzman L, Stewart M. Laryngospasm, central and obstructive apnea during seizures: Defining pathophysiology for sudden death in a rat model. Epilepsy Res 2016; 128:126-139. [PMID: 27835782 DOI: 10.1016/j.eplepsyres.2016.08.004] [Citation(s) in RCA: 48] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/17/2015] [Revised: 06/27/2016] [Accepted: 08/07/2016] [Indexed: 12/21/2022]
Abstract
Seizure spread into the autonomic nervous system can result in life-threatening cardiovascular and respiratory dysfunction. Here we report on a less-studied consequence of such autonomic derangements-the possibility of laryngospasm and upper-airway occlusion. We used parenteral kainic acid to induce recurring seizures in urethane-anesthetized Sprague Dawley rats. EEG recordings and combinations of cardiopulmonary monitoring, including video laryngoscopy, were performed during multi-unit recordings of recurrent laryngeal nerve (RLN) activity or head-out plethysmography with or without endotracheal intubation. Controlled occlusions of a tracheal tube were used to study the kinetics of cardiac and respiratory changes after sudden obstruction. Seizure activity caused significant firing increases in the RLN that were associated with abnormal, high-frequency movements of the vocal folds. Partial airway obstruction from laryngospasm was evident in plethysmograms and was prevented by intubation. Complete glottic closure (confirmed by laryngoscopy) occurred in a subset of non-intubated animals in association with the largest increases in RLN activity, and cessation of airflow was followed in all obstructed animals within tens of seconds by ST-segment elevation, bradycardia, and death. Periods of central apnea occurred in both intubated and non-intubated rats during seizures for periods up to 33s and were associated with modestly increased RLN activity, minimal cardiac derangements, and an open airway on laryngoscopy. In controlled complete airway occlusions, respiratory effort to inspire progressively increased, then ceased, usually in less than 1min. Respiratory arrest was associated with left ventricular dilatation and eventual asystole, an elevation of systemic blood pressure, and complete glottic closure. Severe laryngospasm contributed to the seizure- and hypoxemia-induced conditions that resulted in sudden death in our rat model, and we suggest that this mechanism could contribute to sudden death in epilepsy.
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Affiliation(s)
- K Nakase
- Department of Physiology & Pharmacology, State University of New York, Downstate Medical Center, 450 Clarkson Avenue, Brooklyn, New York, 11203, United States
| | - R Kollmar
- Department of Cell Biology, State University of New York, Downstate Medical Center, 450 Clarkson Avenue, Brooklyn, New York, 11203, United States; Department of Otolaryngology, State University of New York, Downstate Medical Center, 450 Clarkson Avenue, Brooklyn, New York, 11203, United States
| | - J Lazar
- Department of Medicine (Division of Cardiology), State University of New York, Downstate Medical Center, 450 Clarkson Avenue, Brooklyn, New York, 11203, United States
| | - H Arjomandi
- Department of Otolaryngology, State University of New York, Downstate Medical Center, 450 Clarkson Avenue, Brooklyn, New York, 11203, United States
| | - K Sundaram
- Department of Otolaryngology, State University of New York, Downstate Medical Center, 450 Clarkson Avenue, Brooklyn, New York, 11203, United States
| | - J Silverman
- Department of Otolaryngology, State University of New York, Downstate Medical Center, 450 Clarkson Avenue, Brooklyn, New York, 11203, United States
| | - R Orman
- Department of Physiology & Pharmacology, State University of New York, Downstate Medical Center, 450 Clarkson Avenue, Brooklyn, New York, 11203, United States
| | - J Weedon
- Department of Statistical Design & Analysis, State University of New York, Downstate Medical Center, 450 Clarkson Avenue, Brooklyn, New York, 11203, United States
| | - D Stefanov
- Department of Statistical Design & Analysis, State University of New York, Downstate Medical Center, 450 Clarkson Avenue, Brooklyn, New York, 11203, United States
| | - E Savoca
- Department of Cell Biology, State University of New York, Downstate Medical Center, 450 Clarkson Avenue, Brooklyn, New York, 11203, United States; Department of Otolaryngology, State University of New York, Downstate Medical Center, 450 Clarkson Avenue, Brooklyn, New York, 11203, United States
| | - L Tordjman
- Department of Physiology & Pharmacology, State University of New York, Downstate Medical Center, 450 Clarkson Avenue, Brooklyn, New York, 11203, United States
| | - K Stiles
- Department of Cell Biology, State University of New York, Downstate Medical Center, 450 Clarkson Avenue, Brooklyn, New York, 11203, United States
| | - M Ihsan
- Department of Medicine (Division of Cardiology), State University of New York, Downstate Medical Center, 450 Clarkson Avenue, Brooklyn, New York, 11203, United States
| | - A Nunez
- Department of Medicine (Division of Cardiology), State University of New York, Downstate Medical Center, 450 Clarkson Avenue, Brooklyn, New York, 11203, United States
| | - L Guzman
- Research Initiative for Scientific Enhancement (RISE) Program, City University of New York, Medgar Evers College, 1638 Bedford Avenue, Brooklyn, New York, 11225, United States
| | - M Stewart
- Department of Physiology & Pharmacology, State University of New York, Downstate Medical Center, 450 Clarkson Avenue, Brooklyn, New York, 11203, United States; Department of Neurology, State University of New York, Downstate Medical Center, 450 Clarkson Avenue, Brooklyn, New York, 11203, United States.
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12
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Pansani AP, Colugnati DB, Scorza CA, de Almeida ACG, Cavalheiro EA, Scorza FA. Furthering our understanding of SUDEP: the role of animal models. Expert Rev Neurother 2016; 16:561-72. [PMID: 27029803 DOI: 10.1586/14737175.2016.1169925] [Citation(s) in RCA: 22] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/04/2023]
Abstract
Sudden and unexpected death in epilepsy (SUDEP) is the most common type of death among patients with epilepsy. Here, we address the importance of the experimental models in search of the mechanisms underlying SUDEP. Most studies have investigated the cardiovascular responses in animal models of epilepsy. However, there are few proposed SUDEP models in literature. Hypoventilation, apnea, respiratory distress, pulmonary hypertension, autonomic dysregulation and arrhythmia are common findings in epilepsy models. Impairments on adenosinergic and serotonergic systems, brainstem spreading depolarization, seizure-activation of neural substrates related to cardiorespiratory control, altered autonomic control, and mutations on sodium and potassium channels are hypothesis suggested. Overall, current research highlights the evident multifactorial nature of SUDEP, which involves acute and chronic aspects ranging from systemic to molecular alterations. Thus, we are convinced that elucidation and prevention of SUDEP can be achieved only through the interaction between basic and clinical science.
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Affiliation(s)
- Aline P Pansani
- a Laboratório Integrado de Fisiopatologia Cardiovascular e Neurológica. Departamento de Ciências Fisiológicas , Universidade Federal de Goiás , Goiânia , Brasil
| | - Diego B Colugnati
- a Laboratório Integrado de Fisiopatologia Cardiovascular e Neurológica. Departamento de Ciências Fisiológicas , Universidade Federal de Goiás , Goiânia , Brasil
| | - Carla A Scorza
- b Disciplina de Neurociência. Departamento de Neurologia/Neurocirurgia , Escola Paulista de Medicina/Universidade Federal de São Paulo (EPM/UNIFESP) , São Paulo , Brasil
| | - Antonio-Carlos G de Almeida
- c Laboratório de Neurociência Experimental e Computacional. Departamento de Engenharia de Biossistemas , Universidade Federal de São João del-Rei , São João del-Rei , Brasil
| | - Esper A Cavalheiro
- b Disciplina de Neurociência. Departamento de Neurologia/Neurocirurgia , Escola Paulista de Medicina/Universidade Federal de São Paulo (EPM/UNIFESP) , São Paulo , Brasil
| | - Fulvio A Scorza
- b Disciplina de Neurociência. Departamento de Neurologia/Neurocirurgia , Escola Paulista de Medicina/Universidade Federal de São Paulo (EPM/UNIFESP) , São Paulo , Brasil
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13
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Read MI, McCann DM, Millen RN, Harrison JC, Kerr DS, Sammut IA. Progressive development of cardiomyopathy following altered autonomic activity in status epilepticus. Am J Physiol Heart Circ Physiol 2015; 309:H1554-64. [DOI: 10.1152/ajpheart.00256.2015] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 04/07/2015] [Accepted: 08/20/2015] [Indexed: 11/22/2022]
Abstract
Seizures are associated with altered autonomic activity, which has been implicated in the development of cardiac dysfunction and structural damage. This study aimed to investigate the involvement of the autonomic nervous system in seizure-induced cardiomyopathy. Male Sprague-Dawley rats (320–350 g) were implanted with EEG/ECG electrodes to allow simultaneous telemetric recordings during seizures induced by intrahippocampal (2 nmol, 1 μl/min) kainic acid and monitored for 7 days. Seizure activity occurred in conjunction with increased heart rate (20%), blood pressure (25%), and QTc prolongation (15%). This increased sympathetic activity was confirmed by the presence of raised plasma noradrenaline levels at 3 h post-seizure induction. By 48 h post-seizure induction, sympathovagal balance was shifted in favor of sympathetic dominance, as indicated by both heart rate variability (LF/HF ratio of 3.5 ± 1.0) and pharmacological autonomic blockade. Functional cardiac deficits were evident at 7 and 28 days, as demonstrated by echocardiography showing a decreased ejection fraction (14% compared with control, P < 0.05) and dilated cardiomyopathy present at 28 days following seizure induction. Histological changes, including cardiomyocyte vacuolization, cardiac fibrosis, and inflammatory cell infiltration, were evident within 48 h of seizure induction and remained present for up to 28 days. These structural changes most probably contributed to an increased susceptibility to aconitine-induced arrhythmias. This study confirms that prolonged seizure activity results in acute and chronic alterations in cardiovascular control, leading to a deterioration in cardiac structure and function. This study further supports the need for modulation of sympathetic activity as a promising therapeutic approach in seizure-induced cardiomyopathy.
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Affiliation(s)
- Morgayn I. Read
- Department of Pharmacology, University of Otago School of Medical Sciences, Dunedin, New Zealand
| | - Dominic M. McCann
- Department of Pharmacology, University of Otago School of Medical Sciences, Dunedin, New Zealand
| | - Rebecca N. Millen
- Department of Pharmacology, University of Otago School of Medical Sciences, Dunedin, New Zealand
| | - Joanne C. Harrison
- Department of Pharmacology, University of Otago School of Medical Sciences, Dunedin, New Zealand
| | - D. Steven Kerr
- Department of Pharmacology, University of Otago School of Medical Sciences, Dunedin, New Zealand
| | - Ivan A. Sammut
- Department of Pharmacology, University of Otago School of Medical Sciences, Dunedin, New Zealand
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14
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Read MI, Harrison JC, Kerr DS, Sammut IA. Atenolol offers better protection than clonidine against cardiac injury in kainic acid-induced status epilepticus. Br J Pharmacol 2015; 172:4626-38. [PMID: 25765931 DOI: 10.1111/bph.13132] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/10/2014] [Revised: 02/21/2015] [Accepted: 03/06/2015] [Indexed: 12/31/2022] Open
Abstract
BACKGROUND AND PURPOSE Status epilepticus is increasingly associated with cardiac injury in both clinical and animal studies. The current study examined ECG activity for up to 48 h following kainic acid (KA) seizure induction and compared the potential of atenolol and clonidine to attenuate this cardiac pathology. EXPERIMENTAL APPROACH Sprague-Dawley rats (male, 300-350 g) were implanted with ECG and electrocorticogram electrodes to allow simultaneous telemetric recordings of cardiac and cortical responses during and after KA-induced seizures. Animals were randomized into saline controls, and saline vehicle-, clonidine- or atenolol-pretreated KA groups. KEY RESULTS KA administration in the saline-pretreated group produced an immediate bradycardic response (maximal decrease of 28 ± 6%), coinciding with low-level seizure activity. As high-level seizure behaviours and EEG spiking increased, tachycardia also developed, with a maximum heart rate increase of 38 ± 7% coinciding with QTc prolongation and T wave elevation. Both clonidine and atenolol pretreatment attenuated seizure activity and reduced KA-induced changes in heart rate, QTc interval and T wave amplitude observed during both bradycardic and tachycardic phases in saline-pretreated KA animals. Clonidine, however, failed to reduce the power of EEG frequencies. Atenolol and to a lesser extent clonidine attenuated the cardiac hypercontraction band necrosis, inflammatory infiltration, and oedema at 48 h after KA, relative to the saline-KA group. CONCLUSIONS AND IMPLICATIONS Severe seizure activity in this model was clearly associated with altered ECG activity and cardiac pathology. We suggest that modulation of sympathetic activity by atenolol provides a promising cardioprotective approach in status epilepticus.
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Affiliation(s)
- M I Read
- Department of Pharmacology, University of Otago School of Medical Sciences, Dunedin, New Zealand
| | - J C Harrison
- Department of Pharmacology, University of Otago School of Medical Sciences, Dunedin, New Zealand
| | - D S Kerr
- Department of Pharmacology, University of Otago School of Medical Sciences, Dunedin, New Zealand
| | - I A Sammut
- Department of Pharmacology, University of Otago School of Medical Sciences, Dunedin, New Zealand
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Evaluation of Cardiovascular Risk Factors in the Wistar Audiogenic Rat (WAR) Strain. PLoS One 2015; 10:e0129574. [PMID: 26029918 PMCID: PMC4450865 DOI: 10.1371/journal.pone.0129574] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/18/2014] [Accepted: 05/11/2015] [Indexed: 11/24/2022] Open
Abstract
Introduction Risk factors for life-threatening cardiovascular events were evaluated in an experimental model of epilepsy, the Wistar Audiogenic Rat (WAR) strain. Methods We used long-term ECG recordings in conscious, one year old, WAR and Wistar control counterparts to evaluate spontaneous arrhythmias and heart rate variability, a tool to assess autonomic cardiac control. Ventricular function was also evaluated using the pressure-volume conductance system in anesthetized rats. Results Basal RR interval (RRi) was similar between WAR and Wistar rats (188±5 vs 199±6 ms). RRi variability strongly suggests that WAR present an autonomic imbalance with sympathetic overactivity, which is an isolated risk factor for cardiovascular events. Anesthetized WAR showed lower arterial pressure (92±3 vs 115±5 mmHg) and exhibited indices of systolic dysfunction, such as higher ventricle end-diastolic pressure (9.2±0.6 vs 5.6±1 mmHg) and volume (137±9 vs 68±9 μL) as well as lower rate of increase in ventricular pressure (5266±602 vs 7320±538 mmHg.s-1). Indices of diastolic cardiac function, such as lower rate of decrease in ventricular pressure (-5014±780 vs -7766±998 mmHg.s-1) and a higher slope of the linear relationship between end-diastolic pressure and volume (0.078±0.011 vs 0.036±0.011 mmHg.μL), were also found in WAR as compared to Wistar control rats. Moreover, Wistar rats had 3 to 6 ventricular ectopic beats, whereas WAR showed 15 to 30 ectopic beats out of the 20,000 beats analyzed in each rat. Conclusions The autonomic imbalance observed previously at younger age is also present in aged WAR and, additionally, a cardiac dysfunction was also observed in the rats. These findings make this experimental model of epilepsy a valuable tool to study risk factors for cardiovascular events in epilepsy.
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Antagonism of PACAP or microglia function worsens the cardiovascular consequences of kainic-acid-induced seizures in rats. J Neurosci 2015; 35:2191-9. [PMID: 25653374 DOI: 10.1523/jneurosci.4058-14.2015] [Citation(s) in RCA: 25] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/13/2022] Open
Abstract
Seizures are accompanied by cardiovascular changes that are a major cause of sudden unexpected death in epilepsy (SUDEP). Seizures activate inflammatory responses in the cardiovascular nuclei of the medulla oblongata and increase neuronal excitability. Pituitary adenylate cyclase-activating polypeptide (PACAP) is a neuropeptide with autocrine and paracrine neuroprotective properties. Microglia are key players in inflammatory responses in the CNS. We sought to determine whether PACAP and microglia mitigate the adverse effects of seizure on cardiovascular function in a rat model of temporal lobe epilepsy. Kainic acid (KA)-induced seizures increased splanchnic sympathetic nerve activity by 97%, accompanied by increase in heart rate (HR) but not blood pressure (BP). Intrathecal infusion of the PACAP antagonist PACAP(6-38) or the microglia antagonists minocycline and doxycycline augmented sympathetic responses to KA-induced seizures. PACAP(6-38) caused a 161% increase, whereas minocycline and doxycycline caused a 225% and 215% increase, respectively. In intrathecal PACAP-antagonist-treated rats, both BP and HR increased, whereas after treatment with microglial antagonists, only BP was significantly increased compared with control. Our findings support the idea that PACAP and its action on microglia at the level of the spinal cord elicit cardioprotective effects during seizure. However, intrathecal PACAP did not show additive effects, suggesting that the agonist effect was at maximum. The protective effect of microglia may occur by adoption of an M2 phenotype and expression of factors such as TGF-β and IL-10 that promote neuronal quiescence. In summary, therapeutic interventions targeting PACAP and microglia could be a promising strategy for preventing SUDEP.
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Chaitanya G, Santosh NS, Velmurugan J, Arivazhagan A, Bharath RD, Mahadevan A, Nagappa M, Bindu PS, Rao MB, Taly AB, Satishchandra P, Sinha S. Ictal Generalized EEG Attenuation (IGEA) and hypopnea in a child with occipital type 1 cortical dysplasia - Is it a biomarker for SUDEP? Ann Indian Acad Neurol 2015; 18:103-7. [PMID: 25745325 PMCID: PMC4350194 DOI: 10.4103/0972-2327.144279] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/09/2014] [Revised: 05/01/2014] [Accepted: 05/06/2014] [Indexed: 11/23/2022] Open
Abstract
An interesting association of ictal hypopnea and ictal generalized EEG attenuation (IGEA) as possible marker of sudden unexpected death in epilepsy (SUDEP) is reported. We describe a 5-years-old girl with left focal seizures with secondary generalization due to right occipital cortical dysplasia presenting with ictal hypopnea and IGEA. She had repeated episodes of the ictal apnoea in the past requiring ventilator support and intensive care unit (ICU) admission during episodes of status epilepticus. The IGEA lasted for 0.26-4.68 seconds coinciding with the ictal hypopnea during which both clinical seizure and electrical epileptic activity stopped. Review of literature showed correlation between post-ictal apnoea and post ictal generalized EEG suppression and increased risk for SUDEP. The report adds to the growing body of literature on peri-ictal apnea, about its association with IGEA might be considered as a marker for SUDEP. She is seizure free for 4 months following surgery.
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Affiliation(s)
- Ganne Chaitanya
- Department of Clinical Neurosciences, Bangalore, Karnataka, India ; Department of Neurology, National institute of Mental Health and Neurosciences, Bangalore, Karnataka, India
| | - N Subbareddy Santosh
- Department of Neurology, National institute of Mental Health and Neurosciences, Bangalore, Karnataka, India
| | - Jayabal Velmurugan
- Department of Clinical Neurosciences, Bangalore, Karnataka, India ; Department of Neurology, National institute of Mental Health and Neurosciences, Bangalore, Karnataka, India
| | - Arima Arivazhagan
- Department of Neurosurgery, National institute of Mental Health and Neurosciences, Bangalore, Karnataka, India
| | - Rose D Bharath
- Department of Neuroimaging and Interventional Radiology, National institute of Mental Health and Neurosciences, Bangalore, Karnataka, India
| | - Anita Mahadevan
- Department of Neuropathology, National institute of Mental Health and Neurosciences, Bangalore, Karnataka, India
| | - Madhu Nagappa
- Department of Neurology, National institute of Mental Health and Neurosciences, Bangalore, Karnataka, India
| | - Parayil S Bindu
- Department of Neurology, National institute of Mental Health and Neurosciences, Bangalore, Karnataka, India
| | - Malla Bhaskara Rao
- Department of Neurosurgery, National institute of Mental Health and Neurosciences, Bangalore, Karnataka, India
| | - Arun B Taly
- Department of Neurology, National institute of Mental Health and Neurosciences, Bangalore, Karnataka, India
| | | | - Sanjib Sinha
- Department of Neurology, National institute of Mental Health and Neurosciences, Bangalore, Karnataka, India
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18
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Malik GA, Smith PEM. Increasing awareness of sudden unexpected death in epilepsy. Expert Rev Neurother 2014; 13:1371-82. [DOI: 10.1586/14737175.2013.861741] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/22/2022]
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19
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Cardiac electrographic and morphological changes following status epilepticus: Effect of clonidine. Seizure 2014; 23:55-61. [DOI: 10.1016/j.seizure.2013.09.012] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/21/2013] [Revised: 09/17/2013] [Accepted: 09/18/2013] [Indexed: 11/17/2022] Open
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20
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Effects of anesthetic agents on seizure-induction with intra-cortical injection of convulsants. Epilepsy Res 2013; 105:52-61. [DOI: 10.1016/j.eplepsyres.2012.12.009] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/19/2012] [Revised: 12/02/2012] [Accepted: 12/13/2012] [Indexed: 11/21/2022]
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Tolstykh GP, Cavazos JE. Potential mechanisms of sudden unexpected death in epilepsy. Epilepsy Behav 2013; 26:410-4. [PMID: 23305781 DOI: 10.1016/j.yebeh.2012.09.017] [Citation(s) in RCA: 43] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 08/18/2012] [Accepted: 09/06/2012] [Indexed: 01/03/2023]
Abstract
Sudden unexpected death in epilepsy (SUDEP) accounts for 15% of all deaths in people with epilepsy and 50% in refractory epilepsy. The underlying mechanisms are not well understood, but seizure-induced cardiac and respiratory arrests are involved. The cardiovascular and respiratory systems are subject to precise reflex regulation to ensure appropriate oxygen supply under a wide range of circumstances. Barosensory and chemosensory afferents project into the nucleus tractus solitarius (NTS), which relays systemic data to higher brain centers for integration of homeostatic responses in heart rate, peripheral resistance, respiration, and other autonomic reactions. Being the afferent autonomic gatekeeper, NTS plays a critical role in cardiovascular and respiratory regulation. In the course of studying the kainic acid model, we became aware of progressive neuronal loss in the NTS and noted SUDEP-like deaths in rats with frequent convulsions. Increased autonomic susceptibility with inhalation anesthetics was also observed, often seen after impairment of baroreceptor and chemoreceptor reflex loops. Seizure-induced neuron loss in NTS may play a role impairing the integrative functions of NTS resulting in poor homeostatic responses during seizures and leading to SUDEP.
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Affiliation(s)
- Gleb P Tolstykh
- Research Division - ALM VAMC, South Texas Veterans Health Care System, San Antonio, TX 78229, USA
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22
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Naggar I, Uchida S, Kamran H, Lazar J, Stewart M. Autonomic boundary conditions for ventricular fibrillation and their implications for a novel defibrillation technique. J Physiol Sci 2012; 62:479-92. [PMID: 22893479 PMCID: PMC10717413 DOI: 10.1007/s12576-012-0225-8] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/20/2012] [Accepted: 07/23/2012] [Indexed: 10/28/2022]
Abstract
The sympathetic and parasympathetic divisions of the autonomic nervous system modulate cardiac rhythm and the probability of arrhythmia occurrence. Both increased sympathetic drive and hypoxia increase the likelihood for ventricular fibrillation (VF). Vagus nerve stimulation (VNS) can protect from fatal arrhythmias via cholinergic and nitrergic action. We sought to determine boundary conditions for VF and defibrillation by autonomic manipulations accompanied or not by hypoxic changes in urethane-anesthetized rats. VF was induced with (1) vagotomy, (2) systemic high-dose (>15 mg/kg) isoproterenol, and (3) hypoxemia. When VNS (50 Hz) produced cardiac standstill, it converted every VF episode (59/59). A nitric oxide synthase inhibitor did not reduce VNS efficacy (13/14 episodes converted), but addition of atropine reduced VNS efficacy (11/27 episodes converted). VF can be induced by autonomic derangements only under constrained conditions, including sympathetic over-activation, reduced parasympathetic input, and hypoxemia. VNS can provide an alternative method to defibrillate via its cholinergic action.
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Affiliation(s)
- Isaac Naggar
- Department of Physiology and Pharmacology, State University of New York Downstate Medical Center, 450 Clarkson Avenue, Box 31, Brooklyn, NY 11203 USA
- Program in Neural and Behavioral Sciences, State University of New York Downstate Medical Center, 450 Clarkson Avenue, Brooklyn, NY 11203 USA
| | - Sae Uchida
- Department of the Autonomic Nervous System, Tokyo Metropolitan Institute of Gerontology, 35-2 Sakae-cho, Itabashi-ku, Tokyo, 173-0015 Japan
| | - Haroon Kamran
- Division of Cardiovascular Medicine, Department of Medicine, State University of New York Downstate Medical Center, 450 Clarkson Avenue, Brooklyn, NY 11203 USA
| | - Jason Lazar
- Division of Cardiovascular Medicine, Department of Medicine, State University of New York Downstate Medical Center, 450 Clarkson Avenue, Brooklyn, NY 11203 USA
| | - Mark Stewart
- Department of Physiology and Pharmacology, State University of New York Downstate Medical Center, 450 Clarkson Avenue, Box 31, Brooklyn, NY 11203 USA
- Program in Neural and Behavioral Sciences, State University of New York Downstate Medical Center, 450 Clarkson Avenue, Brooklyn, NY 11203 USA
- Department of Neurology, State University of New York Downstate Medical Center, 450 Clarkson Avenue, Brooklyn, NY 11203 USA
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Kheiri F, Bragin A, Engel J, Almajano J, Winden E. Non-linear classification of heart rate parameters as a biomarker for epileptogenesis. Epilepsy Res 2012; 100:59-66. [PMID: 22305585 DOI: 10.1016/j.eplepsyres.2012.01.008] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/08/2011] [Revised: 01/10/2012] [Accepted: 01/15/2012] [Indexed: 10/14/2022]
Abstract
PURPOSE To characterize a biomarker for epileptogenesis based on cardiac interbeat interval characteristics. METHODS Electrocardiograph (ECG) and electroencephalogram (EEG) signals were recorded from freely moving rats (n = 23) before status epilepticus (SE) induced by i.p. pilocarpine (PILO) injection as baseline, and on days 1, 3 and 7 after SE. We assessed several features from cardiac interbeat intervals, including linear, non-linear and frequency parameters of interbeat intervals, and power spectra of interpolated intervals during epileptogenesis. After thresholding, the altered values were applied to a non-linear classifier. The non-linear classifier divided animals into two groups; with and without epilepsy, based on all collected data. RESULTS We found that none of the single altered parameters in cardiac activity emerged as a sole biomarker for epileptogenesis. However, the non-linear classifier distinguished animals that later developed from those and did not develop epilepsy. The non-linear classification was performed on preliminary findings from 23 animals; six did not develop epilepsy and the rest did. The average positive predictive value (precision rate) was 78%. This was calculated based on the average sensitivity and specificity, which were 80.6% and 35.2% respectively, for the 100 classification passes. We also showed that these numbers would have increased as the number of subjects increased. CONCLUSION Changes to the brain caused by status epilepticus that lead to epileptogenesis have systemic effects, and alter cardiac activity. A non-linear classifier performed on several extracted features of cardiac interbeat intervals may be useful as a biomarker to identify animals with low and high probability of developing epilepsy after status epilepticus.
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Affiliation(s)
- Farshad Kheiri
- Department of Neurology, David Geffen School of Medicine at UCLA, Los Angeles, CA, United States.
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Fazan R, de Oliveira M, Oliveira JAC, Salgado HC, Garcia-Cairasco N. Changes in autonomic control of the cardiovascular system in the Wistar audiogenic rat (WAR) strain. Epilepsy Behav 2011; 22:666-70. [PMID: 22015213 DOI: 10.1016/j.yebeh.2011.09.010] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 06/13/2011] [Revised: 08/24/2011] [Accepted: 09/07/2011] [Indexed: 10/16/2022]
Abstract
We evaluated autonomic cardiovascular modulation and baroreflex control of heart rate (HR) in a particular epileptic rat strain, Wistar audiogenic rats (WARs). We studied spontaneous baroreflex sensitivity as well as reflex changes in HR evoked by phenylephrine/nitroprusside-induced changes in arterial pressure (AP). Atropine and propranolol were used to measure cardiac autonomic tone. AP and pulse interval (PI) variability analysis were performed in the time and frequency domains (FFT spectral analysis) to evaluate cardiovascular sympatovagal modulation in WARs. AP and HR were higher in WARs (109±2 mm Hg and 366±9 bpm) than in Wistar control rats (101±2 mm Hg and 326±10 bpm). The power of the low-frequency band of both AP and PI spectra, a marker of sympathetic modulation, was higher in WARs than in Wistar control rats. The high-frequency power of the PI spectra in normalized units, which is linked to cardiac vagal modulation, was lower in WARs. Both WARs and Wistar control rats had similar vagal tone (91±13 bpm vs 94±11 bpm, respectively), but sympathetic tone was higher in WARs (30±4 bpm vs 14±4 bpm). No differences were detected in the gain of evoked (1.32±0.1 ms/mm Hg vs 1.35±0.2 ms/mm Hg) or spontaneous (1.34±0.2 ms/mm Hg vs 2.04±0.2 ms/mm Hg) baroreflex sensitivity. The higher AP and HR and the autonomic imbalance (sympathetic predominance) in WARs might be associated with an increased risk of life-threatening cardiovascular events in this strain.
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Affiliation(s)
- Rubens Fazan
- Department of Physiology, School of Medicine of Ribeirão Preto, University of São Paulo, Ribeirão Preto, SP, Brazil
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Sensory mismatch induces autonomic responses associated with hippocampal theta waves in rats. Behav Brain Res 2011; 220:244-53. [PMID: 21316395 DOI: 10.1016/j.bbr.2011.02.011] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/14/2010] [Revised: 01/30/2011] [Accepted: 02/06/2011] [Indexed: 11/23/2022]
Abstract
Hippocampal (HIP) theta power increases during sensory mismatch, which has been suggested to induce motion sickness with autonomic abnormality (Zou et al., 2009 [29]). To investigate relationships between hippocampal theta rhythm and autonomic functions, theta waves in the HIP and electrocardiograms (ECGs) were recorded during sensory mismatch by backward translocation in awake rats. The rats were placed on a treadmill affixed to a motion stage that was translocated along a figure 8-shaped track. The rats were trained to run forward on the treadmill at the same speed as that of forward translocation of the motion stage (a forward condition) before the experimental (recording) sessions. In the experimental sessions, the rats were initially tested in the forward condition, and then tested in a backward (mismatch) condition, in which the motion stage was turned around by 180° before translocation. That is, the rats were moved backward by translocation of the stage although the rats ran forward on the treadmill. In this condition, proprioceptive information indicated forward movements while vestibular and visual information indicated backward movements. The theta (6-9 Hz) power was significantly increased in the backward condition compared with the forward condition. Spectral analysis of heart rate variability indicated that sympathetic nervous activity increased in the backward condition. These data (theta power and sympathetic nervous activity) were positively correlated. Furthermore, electrical stimulation of the HIP at theta rhythm (8 Hz) increased heart rate. These results suggest that sensory mismatch information activates the HIP to induce autonomic alteration in motion sickness.
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RMSSD, a measure of vagus-mediated heart rate variability, is associated with risk factors for SUDEP: the SUDEP-7 Inventory. Epilepsy Behav 2010; 19:78-81. [PMID: 20667792 PMCID: PMC2943000 DOI: 10.1016/j.yebeh.2010.06.011] [Citation(s) in RCA: 179] [Impact Index Per Article: 12.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 04/27/2010] [Revised: 06/09/2010] [Accepted: 06/10/2010] [Indexed: 11/23/2022]
Abstract
OBJECTIVE The goal of this study was to determine if specific measures of heart rate variability (HRV) are associated with the total score on a new seven-item inventory for sudden unexplained death in epilepsy (SUDEP). METHODS Nineteen subjects with intractable partial seizures, at least three per month, were enrolled in a randomized clinical trial of omega-3 fatty acids in epilepsy. At study entry, subjects underwent a 1-hour ECG recording for the determination of HRV. To estimate the risk of SUDEP, we assembled a seven-item inventory (the SUDEP-7 Inventory) from risk factors prospectively validated by T.S. Walczak, I.E. Leppik, M. D'Amelio M, et al. (Neurology 2001;56:519-25). The SUDEP-7 score was then correlated with measures of HRV using the Pearson correlation and other parametric and nonparametric methods. RESULTS Subjects had highly drug-resistant seizures, with a mean seizure frequency of 22.8 seizures per month. Scores on the SUDEP-7 inventory ranged from 1 to 7 of a maximum possible score of 12. RMSSD, a measure of high-frequency HRV, was inversely correlated with the SUDEP-7 score, r=-0.64, P=0.004. Subjects with higher SUDEP-7 scores had reduced levels of HRV (RMSSD). Other time-dependent measures of HRV (SDNN, SDANN) were not significantly correlated with SUDEP risk scores. CONCLUSIONS RMSSD, a measure of HRV, which reflects the integrity of vagus nerve-mediated autonomic control of the heart, is highly associated with the total score on a new seven-item SUDEP risk inventory. Lower RMSSD values were associated with higher risk scores on the new SUDEP risk inventory. This provides new evidence that HRV (specifically RMSSD) is a marker of SUDEP risk.
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Hotta H, Watanabe N, Orman R, Stewart M. Efferent and afferent vagal actions on cortical blood flow and kainic acid-induced seizure activity in urethane anesthetized rats. Auton Neurosci 2010; 156:144-8. [DOI: 10.1016/j.autneu.2010.04.010] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/16/2010] [Revised: 04/27/2010] [Accepted: 04/28/2010] [Indexed: 10/19/2022]
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Vagus nerve stimulation-induced bradyarrhythmias in rats. Auton Neurosci 2009; 151:98-105. [DOI: 10.1016/j.autneu.2009.07.008] [Citation(s) in RCA: 28] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/17/2009] [Revised: 07/07/2009] [Accepted: 07/10/2009] [Indexed: 11/30/2022]
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