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Yin L, Gao DS, Hu JM, Zhong C, Xi W. Long-term development of dynamic changes in neurovascular coupling after acute temporal lobe epilepsy. Brain Res 2022; 1784:147858. [PMID: 35245486 DOI: 10.1016/j.brainres.2022.147858] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/12/2021] [Revised: 02/23/2022] [Accepted: 02/27/2022] [Indexed: 12/25/2022]
Abstract
Epilepsy is an abnormal brain state that may be induced by synchronous neuronal activation and also abnormalities in energy metabolism or the oxygen supply vascular system. Neurovascular coupling (NVC), the relationship between neuron, capillary, and penetrating artery, remains unexplored on a fine-scale with respect to the pathology process after acute temporal lobe epilepsy (TLE). Here we use two-photon microscopy (TPM) to provide high temporal-spatial resolution imaging to identify changes in NVC during spontaneous and electro-stimulated (ES) states in awake mice. Implantation of a long-term craniotomy window allowed TPM recording of the pathological development after the acute Kainic Acid temporal lobe epilepsy model. Our results provide direct evidence that the capillary and penetrating artery are not correlated to rhythmic neuronal activity during acute epilepsy. During the CSD period, NVC shows a strong correlation. We demonstrate that NVC exhibits nonlinear dynamics after status epilepticus. Furthermore, the vascular correlation to neuronal signals in spontaneous and ES states shows dynamic changes which correlate to the evolution after acute TLE. Understanding NVC in all TLE stages, from the acute through the TLE pathological development, may provide new therapeutic pathways.
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Affiliation(s)
- Liu Yin
- Interdisciplinary Institute of Neuroscience and Technology, Department of Anesthesiology, the Second Affiliated Hospital, School of Medicine, Zhejiang University, Kaixuan Road 258th, Hangzhou, 310020, PR China
| | - Dave Schwinn Gao
- Department of Anesthesiology, the Second Affiliated Hospital, School of Medicine, Zhejiang University, Jiefang Road 88th, Hangzhou, 310016, PR China
| | - Jia Ming Hu
- Interdisciplinary Institute of Neuroscience and Technology, Department of Anesthesiology, the Second Affiliated Hospital, School of Medicine, Zhejiang University, Kaixuan Road 258th, Hangzhou, 310020, PR China
| | - Chen Zhong
- Key Laboratory of Neuropharmacology and Translational Medicine of Zhejiang Province, College of Pharmaceutical Science, Zhejiang Chinese Medical University, Hangzhou, China. Institute of Pharmacology and Toxicology, College of Pharmaceutical Sciences, Zhejiang University, Hangzhou, China. Epilepsy Center, Second Affiliated Hospital, School of Medicine, Zhejiang University, Hangzhou, China.
| | - Wang Xi
- Interdisciplinary Institute of Neuroscience and Technology, Department of Anesthesiology, the Second Affiliated Hospital, School of Medicine, Zhejiang University, Kaixuan Road 258th, Hangzhou, 310020, PR China; Key Laboratory of Biomedical Engineering of Ministry of Education, College of Biomedical Engineering and instrument Science, Zhejiang University, Hangzhou 310027, PR China.
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2
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Chen SF, Pan HY, Huang CR, Huang JB, Tan TY, Chen NC, Hsu CY, Chuang YC. Autonomic Dysfunction Contributes to Impairment of Cerebral Autoregulation in Patients with Epilepsy. J Pers Med 2021; 11:jpm11040313. [PMID: 33920691 PMCID: PMC8073240 DOI: 10.3390/jpm11040313] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/22/2021] [Revised: 04/16/2021] [Accepted: 04/16/2021] [Indexed: 12/26/2022] Open
Abstract
Patients with epilepsy frequently experience autonomic dysfunction and impaired cerebral autoregulation. The present study investigates autonomic function and cerebral autoregulation in patients with epilepsy to determine whether these factors contribute to impaired autoregulation. A total of 81 patients with epilepsy and 45 healthy controls were evaluated, assessing their sudomotor, cardiovagal, and adrenergic functions using a battery of autonomic nervous system (ANS) function tests, including the deep breathing, Valsalva maneuver, head-up tilting, and Q-sweat tests. Cerebral autoregulation was measured by transcranial Doppler examination during the breath-holding test, the Valsalva maneuver, and the head-up tilting test. Autonomic functions were impaired during the interictal period in patients with epilepsy compared to healthy controls. The three indices of cerebral autoregulation—the breath-holding index (BHI), an autoregulation index calculated in phase II of the Valsalva maneuver (ASI), and cerebrovascular resistance measured in the second minute during the head-up tilting test (CVR2-min)—all decreased in patients with epilepsy. ANS dysfunction correlated significantly with impairment of cerebral autoregulation (measured by BHI, ASI, and CVR2-min), suggesting that the increased autonomic dysfunction in patients with epilepsy may augment the dysregulation of cerebral blood flow. Long-term epilepsy, a high frequency of seizures, and refractory epilepsy, particularly temporal lobe epilepsy, may contribute to advanced autonomic dysfunction and impaired cerebral autoregulation. These results have implications for therapeutic interventions that aim to correct central autonomic dysfunction and impairment of cerebral autoregulation, particularly in patients at high risk for sudden, unexplained death in epilepsy.
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Affiliation(s)
- Shu-Fang Chen
- Department of Neurology, Kaohsiung Chang Gung Memorial Hospital, Kaohsiung 83301, Taiwan; (S.-F.C.); (H.-Y.P.); (C.-R.H.); (J.-B.H.); (T.-Y.T.); (N.-C.C.)
- College of Medicine, Chang Gung University, Taoyuan 33302, Taiwan
| | - Hsiu-Yung Pan
- Department of Neurology, Kaohsiung Chang Gung Memorial Hospital, Kaohsiung 83301, Taiwan; (S.-F.C.); (H.-Y.P.); (C.-R.H.); (J.-B.H.); (T.-Y.T.); (N.-C.C.)
- Department of Emergency Medicine, Kaohsiung Chang Gung Memorial Hospital, Kaohsiung 83301, Taiwan
| | - Chi-Ren Huang
- Department of Neurology, Kaohsiung Chang Gung Memorial Hospital, Kaohsiung 83301, Taiwan; (S.-F.C.); (H.-Y.P.); (C.-R.H.); (J.-B.H.); (T.-Y.T.); (N.-C.C.)
- College of Medicine, Chang Gung University, Taoyuan 33302, Taiwan
| | - Jyun-Bin Huang
- Department of Neurology, Kaohsiung Chang Gung Memorial Hospital, Kaohsiung 83301, Taiwan; (S.-F.C.); (H.-Y.P.); (C.-R.H.); (J.-B.H.); (T.-Y.T.); (N.-C.C.)
- Department of Emergency Medicine, Kaohsiung Chang Gung Memorial Hospital, Kaohsiung 83301, Taiwan
| | - Teng-Yeow Tan
- Department of Neurology, Kaohsiung Chang Gung Memorial Hospital, Kaohsiung 83301, Taiwan; (S.-F.C.); (H.-Y.P.); (C.-R.H.); (J.-B.H.); (T.-Y.T.); (N.-C.C.)
- College of Medicine, Chang Gung University, Taoyuan 33302, Taiwan
| | - Nai-Ching Chen
- Department of Neurology, Kaohsiung Chang Gung Memorial Hospital, Kaohsiung 83301, Taiwan; (S.-F.C.); (H.-Y.P.); (C.-R.H.); (J.-B.H.); (T.-Y.T.); (N.-C.C.)
- College of Medicine, Chang Gung University, Taoyuan 33302, Taiwan
| | - Chung-Yao Hsu
- Department of Neurology, School of Medicine, College of Medicine, Kaohsiung Medical University Hospital, Kaohsiung Medical University, Kaohsiung 80708, Taiwan;
| | - Yao-Chung Chuang
- Department of Neurology, Kaohsiung Chang Gung Memorial Hospital, Kaohsiung 83301, Taiwan; (S.-F.C.); (H.-Y.P.); (C.-R.H.); (J.-B.H.); (T.-Y.T.); (N.-C.C.)
- College of Medicine, Chang Gung University, Taoyuan 33302, Taiwan
- Department of Neurology, School of Medicine, College of Medicine, Kaohsiung Medical University Hospital, Kaohsiung Medical University, Kaohsiung 80708, Taiwan;
- Institute for Translation Research in Biomedicine, Kaohsiung Chang Gung Memorial Hospital, Kaohsiung 83301, Taiwan
- Department of Biological Science, National Sun Yat-sen University, Kaohsiung 80424, Taiwan
- Correspondence:
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Bortel A, Pilgram R, Yao ZS, Shmuel A. Dexmedetomidine - Commonly Used in Functional Imaging Studies - Increases Susceptibility to Seizures in Rats But Not in Wild Type Mice. Front Neurosci 2020; 14:832. [PMID: 33192234 PMCID: PMC7658317 DOI: 10.3389/fnins.2020.00832] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/13/2019] [Accepted: 07/16/2020] [Indexed: 12/28/2022] Open
Abstract
Functional MRI (fMRI) utilizes changes in metabolic and hemodynamic signals to indirectly infer the underlying local changes in neuronal activity. To investigate the mechanisms of fMRI responses, spontaneous fluctuations, and functional connectivity in the resting-state, it is important to pursue fMRI in animal models. Animal studies commonly use dexmedetomidine sedation. It has been demonstrated that potent sensory stimuli administered under dexmedetomidine are prone to inducing seizures in Sprague-Dawley (SD) rats. Here we combined optical imaging of intrinsic signals and cerebral blood flow with neurophysiological recordings to measure responses in rat area S1FL to electrical forepaw stimulation administered at 8 Hz. We show that the increased susceptibility to seizures starts no later than 1 h and ends no sooner than 3 h after initiating a continuous administration of dexmedetomidine. By administering different combinations of anesthetic and sedative agents, we demonstrate that dexmedetomidine is the sole agent necessary for the increased susceptibility to seizures. The increased susceptibility to seizures prevails under a combination of 0.3–0.5% isoflurane and dexmedetomidine anesthesia. The blood-oxygenation and cerebral blood flow responses to seizures induced by forepaw stimulation have a higher amplitude and a larger spatial extent relative to physiological responses to the same stimuli. The epileptic activity and the associated blood oxygenation and cerebral blood flow responses stretched beyond the stimulation period. We observed seizures in response to forepaw stimulation with 1–2 mA pulses administered at 8 Hz. In contrast, responses to stimuli administered at 4 Hz were seizure-free. We demonstrate that such seizures are generated not only in SD rats but also in Long-Evans rats, but not in C57BL6 mice stimulated with similar potent stimuli under dexmedetomidine sedation. We conclude that high-amplitude hemodynamic functional imaging responses evoked by peripheral stimulation in rats sedated with dexmedetomidine are possibly due to the induction of epileptic activity. Therefore, caution should be practiced in experiments that combine the administration of potent stimuli with dexmedetomidine sedation. We propose stimulation paradigms that elicit seizure-free, well detectable neurophysiological and hemodynamic responses in rats. We further conclude that the increased susceptibility to seizures under dexmedetomidine sedation is species dependent.
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Affiliation(s)
- Aleksandra Bortel
- Montreal Neurological Institute, McConnell Brain Imaging Centre, McGill University, Montreal, QC, Canada.,Department of Neurology and Neurosurgery, McGill University, Montreal, QC, Canada
| | - Roland Pilgram
- Montreal Neurological Institute, McConnell Brain Imaging Centre, McGill University, Montreal, QC, Canada.,Department of Neurology and Neurosurgery, McGill University, Montreal, QC, Canada
| | - Ze Shan Yao
- Montreal Neurological Institute, McConnell Brain Imaging Centre, McGill University, Montreal, QC, Canada.,Department of Biomedical Engineering, McGill University, Montreal, QC, Canada
| | - Amir Shmuel
- Montreal Neurological Institute, McConnell Brain Imaging Centre, McGill University, Montreal, QC, Canada.,Department of Neurology and Neurosurgery, McGill University, Montreal, QC, Canada.,Department of Biomedical Engineering, McGill University, Montreal, QC, Canada
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Bortel A, Yao ZS, Shmuel A. A rat model of somatosensory-evoked reflex seizures induced by peripheral stimulation. Epilepsy Res 2019; 157:106209. [PMID: 31629247 DOI: 10.1016/j.eplepsyres.2019.106209] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/14/2019] [Revised: 08/31/2019] [Accepted: 09/19/2019] [Indexed: 01/14/2023]
Abstract
OBJECTIVE We introduce a novel animal model of somatosensory stimulation-induced reflex seizures which generates focal seizures without causing damage to the brain. METHODS Specifically, we electrically stimulated digits or forepaws of adult rats sedated with dexmedetomidine while imaging cerebral blood volume and recording neurophysiological activity in cortical area S1FL. For the recordings, we either inserted a linear probe into the D3 digit representation or we performed surface electrocorticography (ECoG) recordings. RESULTS Peripheral stimulation of a digit or the forepaw elicited seizures that were followed by a refractory period with decreased neuronal activity, or another seizure or normal response. LFP amplitudes in response to electrical pulses during the seizures (0.28 ± 0.03 mV) were higher than during normal evoked responses (0.25 ± 0.05 mV) and refractory periods (0.2 ± 0.08 mV). Seizures generated during the stimulation period showed prolonged after-discharges that were sustained for 20.9 ± 1.9 s following the cessation of the stimulus. High-frequency oscillations were observed prior to and during the seizures, with amplitudes higher than those associated with normal evoked responses. The seizures were initially focal. Optical imaging of the cerebral blood volume response showed that they propagated from the onset zone to adjacent cortical areas, beyond the S1FL representation of the stimulated digit or forepaw. The spatial extent during seizures was on average 1.74 times larger during the stimulation and 4.1 times following its cessation relative to normal evoked responses. Seizures were recorded not only by probes inserted into cortex but also with ECoG arrays (24.1 ± 5.8 seizures per rat) placed over the dura matter, indicating that the seizures were not induced by damage caused by inserting the probes to the cortex. Stimulation of the forepaw elicited more seizures (18.8 ± 8.5 seizures per rat) than stimulation of a digit (1.7 ± 0.7). Unlike rats sedated with dexmedetomidine, rats anesthetized with urethane showed no seizures, indicating that the seizures may depend on the use of the mild sedative dexmedetomidine. SIGNIFICANCE Our proposed animal model generates seizures induced by electrical sensory stimulation free of artifacts and brain damage. It can be used for studying the mechanisms underlying the generation and propagation of reflex seizures and for evaluating antiepileptic drugs.
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Affiliation(s)
- Aleksandra Bortel
- Montreal Neurological Institute, McConnell Brain Imaging Centre, McGill University, Montreal, QC, H3A 2B4, Canada; Department of Neurology and Neurosurgery, McGill University, Montreal, QC, H3A 2B4, Canada.
| | - Ze Shan Yao
- Montreal Neurological Institute, McConnell Brain Imaging Centre, McGill University, Montreal, QC, H3A 2B4, Canada; Department of Biomedical Engineering, McGill University, Montreal, QC, H3A 2B4, Canada
| | - Amir Shmuel
- Montreal Neurological Institute, McConnell Brain Imaging Centre, McGill University, Montreal, QC, H3A 2B4, Canada; Department of Neurology and Neurosurgery, McGill University, Montreal, QC, H3A 2B4, Canada; Department of Physiology, McGill University, Montreal, QC, H3A 2B4, Canada; Department of Biomedical Engineering, McGill University, Montreal, QC, H3A 2B4, Canada.
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Kovács R, Gerevich Z, Friedman A, Otáhal J, Prager O, Gabriel S, Berndt N. Bioenergetic Mechanisms of Seizure Control. Front Cell Neurosci 2018; 12:335. [PMID: 30349461 PMCID: PMC6187982 DOI: 10.3389/fncel.2018.00335] [Citation(s) in RCA: 20] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/15/2018] [Accepted: 09/12/2018] [Indexed: 12/14/2022] Open
Abstract
Epilepsy is characterized by the regular occurrence of seizures, which follow a stereotypical sequence of alterations in the electroencephalogram. Seizures are typically a self limiting phenomenon, concluding finally in the cessation of hypersynchronous activity and followed by a state of decreased neuronal excitability which might underlie the cognitive and psychological symptoms the patients experience in the wake of seizures. Many efforts have been devoted to understand how seizures spontaneously stop in hope to exploit this knowledge in anticonvulsant or neuroprotective therapies. Besides the alterations in ion-channels, transmitters and neuromodulators, the successive build up of disturbances in energy metabolism have been suggested as a mechanism for seizure termination. Energy metabolism and substrate supply of the brain are tightly regulated by different mechanisms called neurometabolic and neurovascular coupling. Here we summarize the current knowledge whether these mechanisms are sufficient to cover the energy demand of hypersynchronous activity and whether a mismatch between energy need and supply could contribute to seizure control.
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Affiliation(s)
- Richard Kovács
- Charité - Universitätsmedizin Berlin, Corporate Member of Freie Universität Berlin, Humboldt-Universität zu Berlin, and Berlin Institute of Health, Institut für Neurophysiologie, Berlin, Germany
| | - Zoltan Gerevich
- Charité - Universitätsmedizin Berlin, Corporate Member of Freie Universität Berlin, Humboldt-Universität zu Berlin, and Berlin Institute of Health, Institut für Neurophysiologie, Berlin, Germany
| | - Alon Friedman
- Departments of Physiology and Cell Biology, Cognitive and Brain Sciences, The Zlotowski Center for Neuroscience, Ben-Gurion University of the Negev, Beersheba, Israel.,Department of Medical Neuroscience, Faculty of Medicine, Dalhousie University, Halifax, NS, Canada
| | - Jakub Otáhal
- Institute of Physiology, Czech Academy of Sciences, Prague, Czechia
| | - Ofer Prager
- Departments of Physiology and Cell Biology, Cognitive and Brain Sciences, The Zlotowski Center for Neuroscience, Ben-Gurion University of the Negev, Beersheba, Israel
| | - Siegrun Gabriel
- Charité - Universitätsmedizin Berlin, Corporate Member of Freie Universität Berlin, Humboldt-Universität zu Berlin, and Berlin Institute of Health, Institut für Neurophysiologie, Berlin, Germany
| | - Nikolaus Berndt
- Charité - Universitätsmedizin Berlin, Corporate Member of Freie Universität Berlin, Humboldt-Universität zu Berlin, and Berlin Institute of Health, Institut für Biochemie, Berlin, Germany.,Charité - Universitätsmedizin Berlin, Corporate Member of Freie Universität Berlin, Humboldt-Universität zu Berlin, and Berlin Institute of Health, Institute for Computational and Imaging Science in Cardiovascular Medicine, Berlin, Germany
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Harris SS, Boorman LW, Das D, Kennerley AJ, Sharp PS, Martin C, Redgrave P, Schwartz TH, Berwick J. Physiological and Pathological Brain Activation in the Anesthetized Rat Produces Hemodynamic-Dependent Cortical Temperature Increases That Can Confound the BOLD fMRI Signal. Front Neurosci 2018; 12:550. [PMID: 30154690 PMCID: PMC6102348 DOI: 10.3389/fnins.2018.00550] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/07/2017] [Accepted: 07/20/2018] [Indexed: 11/24/2022] Open
Abstract
Anesthetized rodent models are ubiquitous in pre-clinical neuroimaging studies. However, because the associated cerebral morphology and experimental methodology results in a profound negative brain-core temperature differential, cerebral temperature changes during functional activation are likely to be principally driven by local inflow of fresh, core-temperature, blood. This presents a confound to the interpretation of blood-oxygenation level-dependent (BOLD) functional magnetic resonance imaging (fMRI) data acquired from such models, since this signal is also critically temperature-dependent. Nevertheless, previous investigation on the subject is surprisingly sparse. Here, we address this issue through use of a novel multi-modal methodology in the urethane anesthetized rat. We reveal that sensory stimulation, hypercapnia and recurrent acute seizures induce significant increases in cortical temperature that are preferentially correlated to changes in total hemoglobin concentration (Hbt), relative to cerebral blood flow and oxidative metabolism. Furthermore, using a phantom-based evaluation of the effect of such temperature changes on the BOLD fMRI signal, we demonstrate a robust inverse relationship between both variables. These findings suggest that temperature increases, due to functional hyperemia, should be accounted for to ensure accurate interpretation of BOLD fMRI signals in pre-clinical neuroimaging studies.
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Affiliation(s)
- Samuel S Harris
- Neurovascular and Neuroimaging Research Group, Department of Psychology, University of Sheffield, Sheffield, United Kingdom
| | - Luke W Boorman
- Neurovascular and Neuroimaging Research Group, Department of Psychology, University of Sheffield, Sheffield, United Kingdom
| | - Devashish Das
- Neurovascular and Neuroimaging Research Group, Department of Psychology, University of Sheffield, Sheffield, United Kingdom
| | - Aneurin J Kennerley
- Neurovascular and Neuroimaging Research Group, Department of Psychology, University of Sheffield, Sheffield, United Kingdom
| | - Paul S Sharp
- Neurovascular and Neuroimaging Research Group, Department of Psychology, University of Sheffield, Sheffield, United Kingdom
| | - Chris Martin
- Neurovascular and Neuroimaging Research Group, Department of Psychology, University of Sheffield, Sheffield, United Kingdom
| | - Peter Redgrave
- Neurovascular and Neuroimaging Research Group, Department of Psychology, University of Sheffield, Sheffield, United Kingdom
| | - Theodore H Schwartz
- Department of Neurological Surgery, Brain and Mind Research Institute, Weill Cornell Medicine, Cornell University, New York, NY, United States
| | - Jason Berwick
- Neurovascular and Neuroimaging Research Group, Department of Psychology, University of Sheffield, Sheffield, United Kingdom
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Compromised Dynamic Cerebral Autoregulation in Patients with Epilepsy. BIOMED RESEARCH INTERNATIONAL 2018; 2018:6958476. [PMID: 29568762 PMCID: PMC5820585 DOI: 10.1155/2018/6958476] [Citation(s) in RCA: 13] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 11/10/2017] [Revised: 12/18/2017] [Accepted: 12/26/2017] [Indexed: 12/17/2022]
Abstract
Objective The aim of this study is to analyze dynamic cerebral autoregulation (dCA) in patients with epilepsy. Methods One hundred patients with epilepsy and 100 age- and sex-matched healthy controls were recruited. Noninvasive continuous cerebral blood flow velocity of the bilateral middle artery and arterial blood pressure were recorded. Transfer function analyses were used to analyze the autoregulatory parameters (phase difference and gain). Results The overall phase difference of patients with epilepsy was significantly lower than that of the healthy control group (p = 0.046). Furthermore, patients with interictal slow wave had significant lower phase difference than the slow-wave-free patients (p = 0.012). There was no difference in overall phase between focal discharges and multifocal discharges in patients with epilepsy. Simultaneously, there was no difference in mean phase between the affected and unaffected hemispheres in patients with unilateral discharges. In particular, interictal slow wave was an independent factor that influenced phase difference in patients with epilepsy (p = 0.016). Conclusions Our study documented that dCA is impaired in patients with epilepsy, especially in those with interictal slow wave. The impairment of dCA occurs irrespective of the discharge location and type. Interictal slow wave is an independent factor to predict impaired dCA in patients with epilepsy. Clinical Trial Identifier This trial is registered with NCT02775682.
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Harris SS, Boorman LW, Kennerley AJ, Sharp PS, Martin C, Redgrave P, Schwartz TH, Berwick J. Seizure epicenter depth and translaminar field potential synchrony underlie complex variations in tissue oxygenation during ictal initiation. Neuroimage 2017; 171:165-175. [PMID: 29294386 PMCID: PMC5883323 DOI: 10.1016/j.neuroimage.2017.12.088] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/06/2017] [Revised: 12/01/2017] [Accepted: 12/27/2017] [Indexed: 12/21/2022] Open
Abstract
Whether functional hyperemia during epileptic activity is adequate to meet the heightened metabolic demand of such events is controversial. Whereas some studies have demonstrated hyperoxia during ictal onsets, other work has reported transient hypoxic episodes that are spatially dependent on local surface microvasculature. Crucially, how laminar differences in ictal evolution can affect subsequent cerebrovascular responses has not been thus far investigated, and is likely significant in view of possible laminar-dependent neurovascular mechanisms and angioarchitecture. We addressed this open question using a novel multi-modal methodology enabling concurrent measurement of cortical tissue oxygenation, blood flow and hemoglobin concentration, alongside laminar recordings of neural activity, in a urethane anesthetized rat model of recurrent seizures induced by 4-aminopyridine. We reveal there to be a close relationship between seizure epicenter depth, translaminar local field potential (LFP) synchrony and tissue oxygenation during the early stages of recurrent seizures, whereby deep layer seizures are associated with decreased cross laminar synchrony and prolonged periods of hypoxia, and middle layer seizures are accompanied by increased cross-laminar synchrony and hyperoxia. Through comparison with functional activation by somatosensory stimulation and graded hypercapnia, we show that these seizure-related cerebrovascular responses occur in the presence of conserved neural-hemodynamic and blood flow-volume coupling. Our data provide new insights into the laminar dependency of seizure-related neurovascular responses, which may reconcile inconsistent observations of seizure-related hypoxia in the literature, and highlight a potential layer-dependent vulnerability that may contribute to the harmful effects of clinical recurrent seizures. The relevance of our findings to perfusion-related functional neuroimaging techniques in epilepsy are also discussed.
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Affiliation(s)
- Samuel S Harris
- Department of Psychology, Neurovascular and Neuroimaging Research Group, University of Sheffield, Sheffield S10 2TN, UK.
| | - Luke W Boorman
- Department of Psychology, Neurovascular and Neuroimaging Research Group, University of Sheffield, Sheffield S10 2TN, UK
| | - Aneurin J Kennerley
- Department of Psychology, Neurovascular and Neuroimaging Research Group, University of Sheffield, Sheffield S10 2TN, UK
| | - Paul S Sharp
- Department of Psychology, Neurovascular and Neuroimaging Research Group, University of Sheffield, Sheffield S10 2TN, UK
| | - Chris Martin
- Department of Psychology, Neurovascular and Neuroimaging Research Group, University of Sheffield, Sheffield S10 2TN, UK
| | - Peter Redgrave
- Department of Psychology, Neurovascular and Neuroimaging Research Group, University of Sheffield, Sheffield S10 2TN, UK
| | - Theodore H Schwartz
- Department of Neurological Surgery, Brain and Mind Research Institute, Brain and Spine Center, Weill Cornell Medical College, New York Presbyterian Hospital, 525 East 68th Street, Box 99, New York, NY 10021, USA
| | - Jason Berwick
- Department of Psychology, Neurovascular and Neuroimaging Research Group, University of Sheffield, Sheffield S10 2TN, UK
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Filipovic T, Popovic KS, Ihan A, Vodusek DB. Dynamic Susceptibility Contrast Enhanced (DSC) MRI Perfusion and Plasma Cytokine Levels in Patients after Tonic-clonic Seizures. Radiol Oncol 2017; 51:277-285. [PMID: 28959164 PMCID: PMC5611992 DOI: 10.1515/raon-2017-0031] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/17/2017] [Accepted: 06/14/2017] [Indexed: 11/15/2022] Open
Abstract
Background Inflammatory events in brain parenchyma and glial tissue are involved in epileptogenesis. Blood concentration of cytokines is shown to be elevated after tonic-clonic seizures. As a result of inflammation, blood-brain barrier leakage occurs. This can be documented by imaging techniques, such is dynamic susceptibility contrast enhanced (DSC) MRI perfusion. Our aim was to check for postictal brain inflammation by studying DSC MRI perfusion and plasma level of cytokines. We looked for correlations between number and type of introducing seizures, postictal plasma level of cytokines and parameters of DSC MRI perfusion. Furthermore, we looked for correlation of those parameters and course of the disease over one year follow up. Patients and methods We prospectively enrolled 30 patients, 8–24 hours after single or repeated tonic-clonic seizures. Results 25 of them had normal perfusion parameters, while 5 had hyperperfusion. Patients with hyperperfusion were tested again, 3 months later. Two of 5 had hyperperfusion also on control measurements. Number of index seizures negatively correlated with concentration of proinflammatory cytokines IL-10, IFN-ϒ and TNF-α in a whole cohort. In patients with hyperperfusion, there were significantly lower concentrations of antiinflammatory cytokine IL-4 and higher concentrations of proinflammatory TNF-a. Conclusions Long lasting blood- brain barrier disruption may be crucial for epileptogenesis in selected patients.
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Affiliation(s)
- Tatjana Filipovic
- Division of Neurology, University Medical Centre Ljubljana, Ljubljana, Slovenia
| | | | - Alojz Ihan
- Institute of Immunology, Medical School, University of Ljubljana, Ljubljana, Slovenia
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Gottschalk S, Fehm TF, Deán-Ben XL, Tsytsarev V, Razansky D. Correlation between volumetric oxygenation responses and electrophysiology identifies deep thalamocortical activity during epileptic seizures. NEUROPHOTONICS 2017; 4:011007. [PMID: 27725948 PMCID: PMC5050254 DOI: 10.1117/1.nph.4.1.011007] [Citation(s) in RCA: 42] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/06/2016] [Accepted: 09/13/2016] [Indexed: 05/05/2023]
Abstract
Visualization of whole brain activity during epileptic seizures is essential for both fundamental research into the disease mechanisms and the development of efficient treatment strategies. It has been previously discussed that pathological synchronization originating from cortical areas may reinforce backpropagating signaling from the thalamic neurons, leading to massive seizures through enhancement of high frequency neural activity in the thalamocortical loop. However, the study of deep brain neural activity is challenging with the existing functional neuroimaging methods due to lack of adequate spatiotemporal resolution or otherwise insufficient penetration into subcortical areas. To investigate the role of thalamocortical activity during epileptic seizures, we developed a new functional neuroimaging framework based on spatiotemporal correlation of volumetric optoacoustic hemodynamic responses with the concurrent electroencephalogram recordings and anatomical brain landmarks. The method is shown to be capable of accurate three-dimensional mapping of the onset, spread, and termination of the epileptiform events in a 4-aminopyridine acute model of focal epilepsy. Our study is the first to demonstrate entirely noninvasive real-time visualization of synchronized epileptic foci in the whole mouse brain, including the neocortex and subcortical structures, thus opening new vistas in systematic studies toward the understanding of brain signaling and the origins of neurological disorders.
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Affiliation(s)
- Sven Gottschalk
- Institute for Biological and Medical Imaging (IBMI), Helmholtz Center Munich, Ingolstaedter Landstrasse 1, 85764 Neuherberg, Germany
| | - Thomas Felix Fehm
- Institute for Biological and Medical Imaging (IBMI), Helmholtz Center Munich, Ingolstaedter Landstrasse 1, 85764 Neuherberg, Germany
- Technical University of Munich, Faculty of Medicine, Ismaninger Str. 22, 81675 Munich, Germany
| | - Xose Luís Deán-Ben
- Institute for Biological and Medical Imaging (IBMI), Helmholtz Center Munich, Ingolstaedter Landstrasse 1, 85764 Neuherberg, Germany
| | - Vassiliy Tsytsarev
- University of Maryland School of Medicine, Department of Anatomy and Neurobiology, 20 Penn Street, HSF II, Baltimore, Maryland 21201, United States
| | - Daniel Razansky
- Institute for Biological and Medical Imaging (IBMI), Helmholtz Center Munich, Ingolstaedter Landstrasse 1, 85764 Neuherberg, Germany
- Technical University of Munich, Faculty of Medicine, Ismaninger Str. 22, 81675 Munich, Germany
- Address all correspondence to: Daniel Razansky, E-mail:
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11
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Sykes M, Matheson NA, Brownjohn PW, Tang AD, Rodger J, Shemmell JBH, Reynolds JNJ. Differences in Motor Evoked Potentials Induced in Rats by Transcranial Magnetic Stimulation under Two Separate Anesthetics: Implications for Plasticity Studies. Front Neural Circuits 2016; 10:80. [PMID: 27766073 PMCID: PMC5052269 DOI: 10.3389/fncir.2016.00080] [Citation(s) in RCA: 24] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/20/2016] [Accepted: 09/26/2016] [Indexed: 11/25/2022] Open
Abstract
Repetitive transcranial magnetic stimulation (rTMS) is primarily used in humans to change the state of corticospinal excitability. To assess the efficacy of different rTMS stimulation protocols, motor evoked potentials (MEPs) are used as a readout due to their non-invasive nature. Stimulation of the motor cortex produces a response in a targeted muscle, and the amplitude of this twitch provides an indirect measure of the current state of the cortex. When applied to the motor cortex, rTMS can alter MEP amplitude, however, results are variable between participants and across studies. In addition, the mechanisms underlying any change and its locus are poorly understood. In order to better understand these effects, MEPs have been investigated in vivo in animal models, primarily in rats. One major difference in protocols between rats and humans is the use of general anesthesia in animal experiments. Anesthetics are known to affect plasticity-like mechanisms and so may contaminate the effects of an rTMS protocol. In the present study, we explored the effect of anesthetic on MEP amplitude, recorded before and after intermittent theta burst stimulation (iTBS), a patterned rTMS protocol with reported facilitatory effects. MEPs were assessed in the brachioradialis muscle of the upper forelimb under two anesthetics: a xylazine/zoletil combination and urethane. We found MEPs could be induced under both anesthetics, with no differences in the resting motor threshold or the average baseline amplitudes. However, MEPs were highly variable between animals under both anesthetics, with the xylazine/zoletil combination showing higher variability and most prominently a rise in amplitude across the baseline recording period. Interestingly, application of iTBS did not facilitate MEP amplitude under either anesthetic condition. Although it is important to underpin human application of TMS with mechanistic examination of effects in animals, caution must be taken when selecting an anesthetic and in interpreting results during prolonged TMS recording.
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Affiliation(s)
- Matthew Sykes
- Brain Health Research Centre and Brain Research New Zealand Centre of Research ExcellenceDunedin, New Zealand; Department of Anatomy, University of OtagoDunedin, New Zealand; Experimental and Regenerative Neuroscience, School of Animal Biology, University of Western AustraliaPerth, WA, Australia
| | - Natalie A Matheson
- Brain Health Research Centre and Brain Research New Zealand Centre of Research ExcellenceDunedin, New Zealand; Department of Anatomy, University of OtagoDunedin, New Zealand
| | - Philip W Brownjohn
- Brain Health Research Centre and Brain Research New Zealand Centre of Research ExcellenceDunedin, New Zealand; School of Physical Education, Sport and Exercise Sciences, University of OtagoDunedin, New Zealand
| | - Alexander D Tang
- Experimental and Regenerative Neuroscience, School of Animal Biology, University of Western Australia Perth, WA, Australia
| | - Jennifer Rodger
- Experimental and Regenerative Neuroscience, School of Animal Biology, University of Western Australia Perth, WA, Australia
| | - Jonathan B H Shemmell
- Brain Health Research Centre and Brain Research New Zealand Centre of Research ExcellenceDunedin, New Zealand; School of Physical Education, Sport and Exercise Sciences, University of OtagoDunedin, New Zealand
| | - John N J Reynolds
- Brain Health Research Centre and Brain Research New Zealand Centre of Research ExcellenceDunedin, New Zealand; Department of Anatomy, University of OtagoDunedin, New Zealand
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12
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Moon J, Ha Y, Kim M, Sim J, Lee Y, Suh M. Dual Electrochemical Microsensor for Real-Time Simultaneous Monitoring of Nitric Oxide and Potassium Ion Changes in a Rat Brain during Spontaneous Neocortical Epileptic Seizure. Anal Chem 2016; 88:8942-8. [DOI: 10.1021/acs.analchem.6b02396] [Citation(s) in RCA: 16] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/25/2022]
Affiliation(s)
- Jungmi Moon
- Department
of Chemistry and Nano Science, Ewha Womans University, Seoul, 03760, Republic of Korea
| | - Yejin Ha
- Department
of Chemistry and Nano Science, Ewha Womans University, Seoul, 03760, Republic of Korea
| | - Misun Kim
- Department
of Chemistry and Nano Science, Ewha Womans University, Seoul, 03760, Republic of Korea
| | - Jeongeun Sim
- Center
for Neuroscience Imaging Research (CNIR), Institute for Basic Science (IBS), Suwon, 16419, Republic of Korea
| | - Youngmi Lee
- Department
of Chemistry and Nano Science, Ewha Womans University, Seoul, 03760, Republic of Korea
| | - Minah Suh
- Center
for Neuroscience Imaging Research (CNIR), Institute for Basic Science (IBS), Suwon, 16419, Republic of Korea
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13
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Song Y, Torres RA, Garcia S, Frometa Y, Bae J, Deshmukh A, Lin WC, Zheng Y, Riera JJ. Dysfunction of Neurovascular/Metabolic Coupling in Chronic Focal Epilepsy. IEEE Trans Biomed Eng 2016; 63:97-110. [DOI: 10.1109/tbme.2015.2461496] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
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14
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Blood-brain barrier, bulk flow, and interstitial clearance in epilepsy. J Neurosci Methods 2015; 260:118-24. [PMID: 26093166 DOI: 10.1016/j.jneumeth.2015.06.011] [Citation(s) in RCA: 52] [Impact Index Per Article: 5.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/01/2015] [Revised: 06/10/2015] [Accepted: 06/11/2015] [Indexed: 11/21/2022]
Abstract
Understanding the pathophysiology of epilepsy implies elucidating the neurovascular modifications occurring before or at time of seizures. Cerebrovascular dysfunction provokes or sustains seizures and loss of selective blood-brain barrier (BBB) permeability is a modulator of seizure threshold. However, cerebrovascular pathology in epilepsy extends beyond BBB "leakage" to encompass vascular and parenchymal events. Whenever abnormal accumulation of protein is observed surrounding brain blood vessels, BBB disruption (BBBD) was invoked. Recent clinical and laboratory findings challenged an exclusive role of BBBD in perivascular accumulation of serum-derived products. The circulation of interstitial fluid (ISF) and its bulk flow have emerged as candidate mechanisms which play a role in clearance of CNS waste. Although controversy exists, changes of ISF flow may contribute to CNS disorders through a mechanism encompassing incomplete parenchymal clearance and accompanying accumulation of toxic byproducts. We summarize the evidence in favor and against ISF bulk flow and propose a scenario where abnormal ISF in the epileptic brain allows accumulation of brain protein, sustaining pathophysiology and altering the pharmacology of antiepileptic drugs. We also describe the methods routinely used to dissect out the contribution of BBB-dependent, vascular or paracellular mechanisms to altered neuronal excitability.
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