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Guo Z, Qu Y, Shen Z, Liu J, Wang Z, Sun Y, Zhang K, Chang J, Si X, Jin H, Sun X, Yang Y. Cerebral autoregulation: A reliable predictor of prognosis in patients receiving intravenous thrombolysis. CNS Neurosci Ther 2024; 30:e14748. [PMID: 38727518 PMCID: PMC11086020 DOI: 10.1111/cns.14748] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/19/2023] [Revised: 03/28/2024] [Accepted: 04/22/2024] [Indexed: 05/12/2024] Open
Abstract
AIMS To investigate the characteristics of dynamic cerebral autoregulation (dCA) after intravenous thrombolysis (IVT) and assess the relationship between dCA and prognosis. METHODS Patients with unilateral acute ischemic stroke receiving IVT were prospectively enrolled; those who did not were selected as controls. All patients underwent dCA measurements, by quantifying the phase difference (PD) and gain, at 1-3 and 7-10 days after stroke onset. Simultaneously, two dCA-based nomogram models were established to verify the predictive value of dCA for patients with mild-to-moderate stroke. RESULTS Finally, 202 patients who received IVT and 238 who did not were included. IVT was positively correlated with higher PD on days 1-3 and 7-10 after stroke onset. PD values in both sides at 1-3 days after stroke onset and in the affected side at 7-10 days after onset were independent predictors of unfavorable outcomes in patients who received IVT. Additionally, in patients with mild-to-moderate stroke who received IVT, the dCA-based nomogram models significantly improved the risk predictive ability for 3-month unfavorable outcomes. CONCLUSION IVT has a positive effect on dCA in patients with acute stroke; furthermore, dCA may be useful to predict the prognosis of patients with IVT.
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Affiliation(s)
- Zhen‐Ni Guo
- Stroke Center, Department of NeurologyThe First Hospital of Jilin UniversityChangchunChina
- Neuroscience Research Center, Department of NeurologyThe First Hospital of Jilin UniversityChangchunChina
| | - Yang Qu
- Stroke Center, Department of NeurologyThe First Hospital of Jilin UniversityChangchunChina
| | - Zi‐Duo Shen
- Stroke Center, Department of NeurologyThe First Hospital of Jilin UniversityChangchunChina
| | - Jia Liu
- Laboratory for Engineering and Scientific Computing, Institute of Advanced Computing and Digital Engineering, Shenzhen Institute of Advanced TechnologyChinese Academy of SciencesShenzhenChina
| | - Zhong‐Xiu Wang
- Stroke Center, Department of NeurologyThe First Hospital of Jilin UniversityChangchunChina
| | - Ying‐Ying Sun
- Stroke Center, Department of NeurologyThe First Hospital of Jilin UniversityChangchunChina
| | - Ke‐Jia Zhang
- Stroke Center, Department of NeurologyThe First Hospital of Jilin UniversityChangchunChina
| | - Junlei Chang
- Center for Protein and Cell‐based Drugs, Institute of Biomedicine and Biotechnology, Shenzhen Institute of Advanced TechnologyChinese Academy of SciencesShenzhenChina
| | - Xiang‐Kun Si
- Stroke Center, Department of NeurologyThe First Hospital of Jilin UniversityChangchunChina
| | - Hang Jin
- Stroke Center, Department of NeurologyThe First Hospital of Jilin UniversityChangchunChina
| | - Xin Sun
- Stroke Center, Department of NeurologyThe First Hospital of Jilin UniversityChangchunChina
| | - Yi Yang
- Stroke Center, Department of NeurologyThe First Hospital of Jilin UniversityChangchunChina
- Neuroscience Research Center, Department of NeurologyThe First Hospital of Jilin UniversityChangchunChina
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Beishon L, Vasilopoulos T, Salinet ASM, Levis B, Barnes S, Hills E, Ramesh P, Gkargkoula P, Minhas JS, Castro P, Brassard P, Goettel N, Gommer ED, Jara JL, Liu J, Mueller M, Nasr N, Payne S, Robertson AD, Simpson D, Robinson TG, Panerai RB, Nogueira RC. Individual Patient Data Meta-Analysis of Dynamic Cerebral Autoregulation and Functional Outcome After Ischemic Stroke. Stroke 2024; 55:1235-1244. [PMID: 38511386 PMCID: PMC7615849 DOI: 10.1161/strokeaha.123.045700] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/19/2023] [Accepted: 02/12/2024] [Indexed: 03/22/2024]
Abstract
BACKGROUND The relationship between dynamic cerebral autoregulation (dCA) and functional outcome after acute ischemic stroke (AIS) is unclear. Previous studies are limited by small sample sizes and heterogeneity. METHODS We performed a 1-stage individual patient data meta-analysis to investigate associations between dCA and functional outcome after AIS. Participating centers were identified through a systematic search of the literature and direct invitation. We included centers with dCA data within 1 year of AIS in adults aged over 18 years, excluding intracerebral or subarachnoid hemorrhage. Data were obtained on phase, gain, coherence, and autoregulation index derived from transfer function analysis at low-frequency and very low-frequency bands. Cerebral blood velocity, arterial pressure, end-tidal carbon dioxide, heart rate, stroke severity and sub-type, and comorbidities were collected where available. Data were grouped into 4 time points after AIS: <24 hours, 24 to 72 hours, 4 to 7 days, and >3 months. The modified Rankin Scale assessed functional outcome at 3 months. Modified Rankin Scale was analyzed as both dichotomized (0 to 2 versus 3 to 6) and ordinal (modified Rankin Scale scores, 0-6) outcomes. Univariable and multivariable analyses were conducted to identify significant relationships between dCA parameters, comorbidities, and outcomes, for each time point using generalized linear (dichotomized outcome), or cumulative link (ordinal outcome) mixed models. The participating center was modeled as a random intercept to generate odds ratios with 95% CIs. RESULTS The sample included 384 individuals (35% women) from 7 centers, aged 66.3±13.7 years, with predominantly nonlacunar stroke (n=348, 69%). In the affected hemisphere, higher phase at very low-frequency predicted better outcome (dichotomized modified Rankin Scale) at <24 (crude odds ratios, 2.17 [95% CI, 1.47-3.19]; P<0.001) hours, 24-72 (crude odds ratios, 1.95 [95% CI, 1.21-3.13]; P=0.006) hours, and phase at low-frequency predicted outcome at 3 (crude odds ratios, 3.03 [95% CI, 1.10-8.33]; P=0.032) months. These results remained after covariate adjustment. CONCLUSIONS Greater transfer function analysis-derived phase was associated with improved functional outcome at 3 months after AIS. dCA parameters in the early phase of AIS may help to predict functional outcome.
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Affiliation(s)
- Lucy Beishon
- University of Leicester, Department of Cardiovascular Sciences, Leicester, UK
- NIHR Leicester Biomedical Research Centre, British Heart Foundation Cardiovascular Research Centre, Glenfield Hospital, Leicester, UK
| | - Terrie Vasilopoulos
- Department of Anesthesiology, University of Florida College of Medicine, Gainesville, FL, USA
| | - Angela SM Salinet
- Neurology Department, Hospital das Clinicas, School of Medicine, University of Sao Paulo, Sao Paulo, Brazil
| | - Brooke Levis
- Lady Davis Institute for Medical Research, Jewish General Hospital, Montreal, Quebec, Canada
- Centre for Prognosis Research, School of Medicine, Keele University, Staffordshire, UK
| | - Samuel Barnes
- University of Leicester, Department of Cardiovascular Sciences, Leicester, UK
- University Hospitals of Leicester NHS Trust, Leicester, UK
| | - Eleanor Hills
- University of Leicester, Department of Cardiovascular Sciences, Leicester, UK
| | - Pranav Ramesh
- University of Leicester, Department of Cardiovascular Sciences, Leicester, UK
| | | | - Jatinder S. Minhas
- University of Leicester, Department of Cardiovascular Sciences, Leicester, UK
- NIHR Leicester Biomedical Research Centre, British Heart Foundation Cardiovascular Research Centre, Glenfield Hospital, Leicester, UK
| | - Pedro Castro
- Department of Neurology, Centro Hospitalar Universitário de São João, Faculty of Medicine, University of Porto
| | - Patrice Brassard
- Département de Kinésiologie, Faculté de médecine, Institut universitaire de cardiologie et de pneumologie de Québec
| | - Nicolai Goettel
- Department of Anesthesiology, Perioperative and Pain Medicine, Brigham and Women’s Hospital, Harvard Medical School, Boston, MA, USA
| | - Erik D. Gommer
- Department of Clinical Neurophysiology, Maastricht University Medical Centre, Maastricht, the Netherlands
| | - Jose Luis Jara
- Departamento de Ingeniería Informática, Universidad de Santiago de Chile
| | - Jia Liu
- Shenzhen Institutes of Advanced Technology at the Chinese Academy of Sciences in Shenzhen, China
| | - Martin Mueller
- Department of Neurology and Neurorehabilitation, Spitalstrasse, CH 6000 Lucerne
| | - Nathalie Nasr
- Department of Neurology, Poitiers University Hospital, Laboratoire de Neurosciences Expérimentales et Cliniques, University of Poitiers, France
| | - Stephen Payne
- Institute of Applied Mechanics, National Taiwan University, Taipei, Taiwan
| | - Andrew D. Robertson
- Schlegel-UW Research Institute for Aging, University of Waterloo, Waterloo, ON, CA
| | - David Simpson
- Faculty of Engineering and Physical Sciences, University of Southampton
| | - Thompson G Robinson
- University of Leicester, Department of Cardiovascular Sciences, Leicester, UK
- NIHR Leicester Biomedical Research Centre, British Heart Foundation Cardiovascular Research Centre, Glenfield Hospital, Leicester, UK
| | - Ronney B. Panerai
- University of Leicester, Department of Cardiovascular Sciences, Leicester, UK
- NIHR Leicester Biomedical Research Centre, British Heart Foundation Cardiovascular Research Centre, Glenfield Hospital, Leicester, UK
| | - Ricardo C. Nogueira
- Neurology Department, Hospital das Clinicas, School of Medicine, University of Sao Paulo, Sao Paulo, Brazil
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3
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Cipolla MJ, Hunt RD, Liebeskind DS, Tremble SM. The impact of collateral therapeutics on stroke hemodynamics in normotensive and hypertensive rats: a step toward translation. Front Neurol 2024; 15:1373445. [PMID: 38585360 PMCID: PMC10996366 DOI: 10.3389/fneur.2024.1373445] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/19/2024] [Accepted: 03/01/2024] [Indexed: 04/09/2024] Open
Abstract
Introduction Stroke interventions that increase collateral flow have the potential to salvage penumbral tissue and increase the number of patients eligible for reperfusion therapy. We compared the efficacy of two different collateral therapeutics during transient middle cerebral artery occlusion (tMCAO) in normotensive and hypertensive rats. Methods The change in collateral and core perfusion was measured using dual laser Doppler in response to either a pressor agent (phenylephrine, 10 mg/kg iv or vehicle) or a collateral vasodilator (TM5441, 5 mg/kg iv or vehicle) given 30 min into tMCAO in male Wistar and spontaneously hypertensive rats (SHRs). Results Pressor therapy increased collateral flow in the Wistar rats but was ineffective in the SHRs. The increase in collateral flow in the Wistar rats was associated with impaired cerebral blood flow autoregulation (CBFAR) that was intact in the SHRs. TM5441 caused a decrease in collateral perfusion in the Wistar rats and a modest increase in the SHRs. The pressor therapy reduced early infarction in both groups but increased edema in the SHRs, whereas TM5441 did not have any beneficial effects in either group. Conclusions Thus, the pressor therapy was superior to a collateral vasodilator in increasing collateral flow and improving outcomes in the Wistar rats, likely due to pial collaterals that were pressure passive; the lack of CBF response in the SHRs to pressor therapy was likely due to intact CBFAR that limited perfusion. While TM5441 modestly increased CBF in the SHRs but not in the Wistar rats, it did not have a beneficial effect on stroke outcomes. These results suggest that collateral therapies may need to be selected for certain comorbidities.
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Affiliation(s)
- Marilyn J. Cipolla
- Department of Neurological Sciences, Larner College of Medicine, University of Vermont, Burlington, VT, United States
- Department of Obstetrics, Gynecology and Reproductive Sciences, Larner College of Medicine, University of Vermont, Burlington, VT, United States
- Department of Pharmacology, Larner College of Medicine, University of Vermont, Burlington, VT, United States
- Department of Electrical and Biomedical Engineering, College of Engineering and Mathematical Sciences, University of Vermont, Burlington, VT, United States
| | - Ryan D. Hunt
- Department of Neurological Sciences, Larner College of Medicine, University of Vermont, Burlington, VT, United States
| | - David S. Liebeskind
- Department of Neurology, University of California Los Angeles, Los Angeles, CA, United States
| | - Sarah M. Tremble
- Department of Neurological Sciences, Larner College of Medicine, University of Vermont, Burlington, VT, United States
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Sheriff FG, Ahmad A, Inam ME, Khatri R, Maud A, Rodriguez GJ. A systematic review on the assessment of cerebral autoregulation in patients with Large Vessel Occlusion. Front Neurol 2023; 14:1287873. [PMID: 38046584 PMCID: PMC10693431 DOI: 10.3389/fneur.2023.1287873] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/02/2023] [Accepted: 11/02/2023] [Indexed: 12/05/2023] Open
Abstract
As the majority of large vessel occlusion (LVO) patients are not treated with revascularization therapies or efficiently revascularized, complementary management strategies are needed. In this article we explore the importance of cerebral autoregulation (CA) assessment in the prediction and/or modification of infarct growth and hemorrhagic transformation. In patients with LVO, these are important factors that affect prognosis. A systematic search of the PubMed, EMBASE databases and a targeted Google search was conducted, resulting in the inclusion of 34 relevant articles. There is an agreement that CA is impaired in patients with LVO; several factors have been identified such as time course, revascularization status, laterality, disease subtype and location, some of which may be potentially modifiable and affect outcomes. The personalized CA assessment of these patients suggests potential for better understanding of the inter-individual variability. Further research is needed for the development of more accurate, noninvasive techniques for continuous monitoring and personalized thresholds for CA.
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Affiliation(s)
- Faheem G. Sheriff
- Department of Neurology, Section of Interventional Neurology, Texas Tech University Health Sciences Center El Paso, El Paso, TX, United States
| | | | - Mehmet E. Inam
- University of Texas Health Science Center at Houston, Houston, TX, United States
| | - Rakesh Khatri
- Department of Neurology, Section of Interventional Neurology, Texas Tech University Health Sciences Center El Paso, El Paso, TX, United States
| | - Alberto Maud
- Department of Neurology, Section of Interventional Neurology, Texas Tech University Health Sciences Center El Paso, El Paso, TX, United States
| | - Gustavo J. Rodriguez
- Department of Neurology, Section of Interventional Neurology, Texas Tech University Health Sciences Center El Paso, El Paso, TX, United States
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Sarwal A, Robba C, Venegas C, Ziai W, Czosnyka M, Sharma D. Are We Ready for Clinical Therapy based on Cerebral Autoregulation? A Pro-con Debate. Neurocrit Care 2023; 39:269-283. [PMID: 37165296 DOI: 10.1007/s12028-023-01741-1] [Citation(s) in RCA: 9] [Impact Index Per Article: 9.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/24/2022] [Accepted: 04/19/2023] [Indexed: 05/12/2023]
Abstract
Cerebral autoregulation (CA) is a physiological mechanism that maintains constant cerebral blood flow regardless of changes in cerebral perfusion pressure and prevents brain damage caused by hypoperfusion or hyperperfusion. In recent decades, researchers have investigated the range of systemic blood pressures and clinical management strategies over which cerebral vasculature modifies intracranial hemodynamics to maintain cerebral perfusion. However, proposed clinical interventions to optimize autoregulation status have not demonstrated clear clinical benefit. As future trials are designed, it is crucial to comprehend the underlying cause of our inability to produce robust clinical evidence supporting the concept of CA-targeted management. This article examines the technological advances in monitoring techniques and the accuracy of continuous assessment of autoregulation techniques used in intraoperative and intensive care settings today. It also examines how increasing knowledge of CA from recent clinical trials contributes to a greater understanding of secondary brain injury in many disease processes, despite the fact that the lack of robust evidence influencing outcomes has prevented the translation of CA-guided algorithms into clinical practice.
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Affiliation(s)
- Aarti Sarwal
- Atrium Wake Forest School of Medicine, Winston-Salem, NC, USA.
| | | | - Carla Venegas
- Mayo Clinic School of Medicine, Jacksonville, FL, USA
| | - Wendy Ziai
- Johns Hopkins University School of Medicine and Johns Hopkins Bayview Medical Center, Baltimore, MD, USA
| | - Marek Czosnyka
- Division of Neurosurgery, Cambridge University Hospital, Cambridge, UK
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Panerai RB, Brassard P, Burma JS, Castro P, Claassen JA, van Lieshout JJ, Liu J, Lucas SJ, Minhas JS, Mitsis GD, Nogueira RC, Ogoh S, Payne SJ, Rickards CA, Robertson AD, Rodrigues GD, Smirl JD, Simpson DM. Transfer function analysis of dynamic cerebral autoregulation: A CARNet white paper 2022 update. J Cereb Blood Flow Metab 2023; 43:3-25. [PMID: 35962478 PMCID: PMC9875346 DOI: 10.1177/0271678x221119760] [Citation(s) in RCA: 42] [Impact Index Per Article: 42.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/28/2023]
Abstract
Cerebral autoregulation (CA) refers to the control of cerebral tissue blood flow (CBF) in response to changes in perfusion pressure. Due to the challenges of measuring intracranial pressure, CA is often described as the relationship between mean arterial pressure (MAP) and CBF. Dynamic CA (dCA) can be assessed using multiple techniques, with transfer function analysis (TFA) being the most common. A 2016 white paper by members of an international Cerebrovascular Research Network (CARNet) that is focused on CA strove to improve TFA standardization by way of introducing data acquisition, analysis, and reporting guidelines. Since then, additional evidence has allowed for the improvement and refinement of the original recommendations, as well as for the inclusion of new guidelines to reflect recent advances in the field. This second edition of the white paper contains more robust, evidence-based recommendations, which have been expanded to address current streams of inquiry, including optimizing MAP variability, acquiring CBF estimates from alternative methods, estimating alternative dCA metrics, and incorporating dCA quantification into clinical trials. Implementation of these new and revised recommendations is important to improve the reliability and reproducibility of dCA studies, and to facilitate inter-institutional collaboration and the comparison of results between studies.
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Affiliation(s)
- Ronney B Panerai
- Department of Cardiovascular Sciences, University of Leicester and NIHR Biomedical Research Centre, Leicester, UK
| | - Patrice Brassard
- Department of Kinesiology, Faculty of Medicine, and Research Center of the Institut universitaire de cardiologie et de pneumologie de Québec, Université Laval, Québec, QC, Canada
| | - Joel S Burma
- Faculty of Kinesiology, University of Calgary, Calgary, AB, Canada
| | - Pedro Castro
- Department of Neurology, Centro Hospitalar Universitário de São João, Faculty of Medicine, University of Porto, Porto, Portugal
| | - Jurgen Ahr Claassen
- Department of Geriatric Medicine and Donders Institute for Brain, Cognition and Behaviour, Radboud University, Nijmegen, The Netherlands
| | - Johannes J van Lieshout
- Department of Internal Medicine, Amsterdam, UMC, The Netherlands and Division of Physiology, Pharmacology and Neuroscience, School of Life Sciences, University of Nottingham Medical School, Queen's Medical Centre, UK
| | - Jia Liu
- Institute of Advanced Computing and Digital Engineering, Shenzhen Institutes of Advanced Technology, Chinese Academy of Sciences, Shenzhen University Town, Shenzhen, China
| | - Samuel Je Lucas
- School of Sport, Exercise and Rehabilitation Sciences and Centre for Human Brain Health, University of Birmingham, Birmingham, UK
| | - Jatinder S Minhas
- Department of Cardiovascular Sciences, University of Leicester and NIHR Biomedical Research Centre, Leicester, UK
| | - Georgios D Mitsis
- Department of Bioengineering, McGill University, Montreal, Québec, QC, Canada
| | - Ricardo C Nogueira
- Neurology Department, School of Medicine, Hospital das Clinicas, University of São Paulo, São Paulo, Brazil
| | - Shigehiko Ogoh
- Department of Biomedical Engineering, Toyo University, Kawagoe-Shi, Saitama, Japan
| | - Stephen J Payne
- Institute of Applied Mechanics, National Taiwan University, Taipei
| | - Caroline A Rickards
- Department of Physiology & Anatomy, University of North Texas Health Science Center, Fort Worth, Texas, USA
| | - Andrew D Robertson
- Department of Kinesiology and Health Sciences, University of Waterloo, Waterloo, ON, Canada
| | - Gabriel D Rodrigues
- Department of Clinical Sciences and Community Health, University of Milan, Milan, Italy
| | - Jonathan D Smirl
- Faculty of Kinesiology, University of Calgary, Calgary, AB, Canada
| | - David M Simpson
- Institute of Sound and Vibration Research, University of Southampton, Southampton, UK
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7
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The utility of therapeutic hypothermia on cerebral autoregulation. JOURNAL OF INTENSIVE MEDICINE 2022; 3:27-37. [PMID: 36789361 PMCID: PMC9924009 DOI: 10.1016/j.jointm.2022.08.004] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Subscribe] [Scholar Register] [Received: 03/17/2022] [Revised: 07/26/2022] [Accepted: 08/10/2022] [Indexed: 11/07/2022]
Abstract
Cerebral autoregulation (CA) dysfunction is a strong predictor of clinical outcome in patients with acute brain injury (ABI). CA dysfunction is a potential pathologic defect that may lead to secondary injury and worse functional outcomes. Early therapeutic hypothermia (TH) in patients with ABI is controversial. Many factors, including patient selection, timing, treatment depth, duration, and rewarming strategy, impact its clinical efficacy. Therefore, optimizing the benefit of TH is an important issue. This paper reviews the state of current research on the impact of TH on CA function, which may provide the basis and direction for CA-oriented target temperature management.
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8
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Brain Bioenergetics in Chronic Hypertension: Risk Factor for Acute Ischemic Stroke. Biochem Pharmacol 2022; 205:115260. [PMID: 36179931 DOI: 10.1016/j.bcp.2022.115260] [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: 07/30/2022] [Revised: 09/13/2022] [Accepted: 09/14/2022] [Indexed: 11/23/2022]
Abstract
Chronic hypertension is one of the key modifiable risk factors for acute ischemic stroke, also contributing to determine greater neurological deficits and worse functional outcome when an acute cerebrovascular event would occur. A tight relationship exists between cerebrovascular autoregulation, neuronal activity and brain bioenergetics. In chronic hypertension, progressive adaptations of these processes occur as an attempt to cope with the demanding necessity of brain functions, creating a new steady-state homeostatic condition. However, these adaptive modifications are insufficient to grant an adequate response to possible pathological perturbations of the established fragile hemodynamic and metabolic homeostasis. In this narrative review, we will discuss the main mechanisms by which alterations in brain bioenergetics and mitochondrial function in chronic hypertension could lead to increased risk of acute ischemic stroke, stressing the interconnections between hemodynamic factors (i.e. cerebral autoregulation and neurovascular coupling) and metabolic processes. Both experimental and clinical pieces of evidence will be discussed. Moreover, the potential role of mitochondrial dysfunction in determining, or at least sustaining, the pathogenesis and progression of chronic neurogenic hypertension will be considered. In the perspective of novel therapeutic strategies aiming at improving brain bioenergetics, we propose some determinant factors to consider in future studies focused on the cause-effect relationships between chronic hypertension and brain bioenergetic abnormalities (and vice versa), so to help translational research in this so-far unfilled gap.
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9
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Al-Kawaz M, Cho SM, Gottesman RF, Suarez JI, Rivera-Lara L. Impact of Cerebral Autoregulation Monitoring in Cerebrovascular Disease: A Systematic Review. Neurocrit Care 2022; 36:1053-1070. [PMID: 35378665 DOI: 10.1007/s12028-022-01484-5] [Citation(s) in RCA: 15] [Impact Index Per Article: 7.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/29/2021] [Accepted: 03/01/2022] [Indexed: 12/16/2022]
Abstract
Cerebral autoregulation (CA) prevents brain injury by maintaining a relatively constant cerebral blood flow despite fluctuations in cerebral perfusion pressure. This process is disrupted consequent to various neurologic pathologic processes, which may result in worsening neurologic outcomes. Herein, we aim to highlight evidence describing CA changes and the impact of CA monitoring in patients with cerebrovascular disease, including ischemic stroke, intracerebral hemorrhage (ICH), and aneurysmal subarachnoid hemorrhage (aSAH). The study was preformed according to the Preferred Reporting Items for Systematic Reviews and Meta-Analysis guidelines. English language publications were identified through a systematic literature conducted in Ovid Medline, PubMed, and Embase databases. The search spanned the dates of each database's inception through January 2021. We selected case-control studies, cohort observational studies, and randomized clinical trials for adult patients (≥ 18 years) who were monitored with continuous metrics using transcranial Doppler, near-infrared spectroscopy, and intracranial pressure monitors. Of 2799 records screened, 48 studies met the inclusion criteria. There were 23 studies on ischemic stroke, 18 studies on aSAH, 5 studies on ICH, and 2 studies on systemic hypertension. CA impairment was reported after ischemic stroke but generally improved after tissue plasminogen activator administration and successful mechanical thrombectomy. Persistent impairment in CA was associated with hemorrhagic transformation, malignant cerebral edema, and need for hemicraniectomy. Studies that investigated large ICHs described bilateral CA impairment up to 12 days from the ictus, especially in the presence of small vessel disease. In aSAH, impairment of CA was associated with angiographic vasospasm, delayed cerebral ischemia, and poor functional outcomes at 6 months. This systematic review highlights the available evidence for CA disruption during cerebrovascular diseases and its possible association with long-term neurological outcome. CA may be disrupted even before acute stroke in patients with untreated chronic hypertension. Monitoring CA may help in establishing individualized management targets in patients with cerebrovascular disease.
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Affiliation(s)
- Mais Al-Kawaz
- Department of Neurosurgery, Icahn School of Medicine at Mount Sinai, New York, NY, USA.
- Department of Neurology, The Johns Hopkins University School of Medicine, Baltimore, MD, USA.
| | - Sung-Min Cho
- Department of Neurology, The Johns Hopkins University School of Medicine, Baltimore, MD, USA
- Department of Anesthesiology and Critical Care Medicine, The Johns Hopkins University School of Medicine, Baltimore, MD, USA
| | - Rebecca F Gottesman
- Stroke Branch, National Institute of Neurological Disorders and Stroke Intramural Program, National Institutes of Health, Bethesda, MD, USA
| | - Jose I Suarez
- Department of Neurology, The Johns Hopkins University School of Medicine, Baltimore, MD, USA
- Department of Anesthesiology and Critical Care Medicine, The Johns Hopkins University School of Medicine, Baltimore, MD, USA
- Department of Neurosurgery, The Johns Hopkins University School of Medicine, Baltimore, MD, USA
| | - Lucia Rivera-Lara
- Division of Stroke and Neurocritical Care, Stanford University, Palo Alto, CA, USA
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10
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Abstract
Despite advances in acute management and prevention of cerebrovascular disease, stroke and vascular cognitive impairment together remain the world's leading cause of death and neurological disability. Hypertension and its consequences are associated with over 50% of ischemic and 70% of hemorrhagic strokes but despite good control of blood pressure (BP), there remains a 10% risk of recurrent cerebrovascular events, and there is no proven strategy to prevent vascular cognitive impairment. Hypertension evolves over the lifespan, from predominant sympathetically driven hypertension with elevated mean BP in early and mid-life to a late-life phenotype of increasing systolic and falling diastolic pressures, associated with increased arterial stiffness and aortic pulsatility. This pattern may partially explain both the increasing incidence of stroke in younger adults as well as late-onset, chronic cerebrovascular injury associated with concurrent systolic hypertension and historic mid-life diastolic hypertension. With increasing arterial stiffness and autonomic dysfunction, BP variability increases, independently predicting the risk of ischemic and intracerebral hemorrhage, and is potentially modifiable beyond control of mean BP. However, the interaction between hypertension and control of cerebral blood flow remains poorly understood. Cerebral small vessel disease is associated with increased pulsatility in large cerebral vessels and reduced reactivity to carbon dioxide, both of which are being targeted in early phase clinical trials. Cerebral arterial pulsatility is mainly dependent upon increased transmission of aortic pulsatility via stiff vessels to the brain, while cerebrovascular reactivity reflects endothelial dysfunction. In contrast, although cerebral autoregulation is critical to adapt cerebral tone to BP fluctuations to maintain cerebral blood flow, its role as a modifiable risk factor for cerebrovascular disease is uncertain. New insights into hypertension-associated cerebrovascular pathophysiology may provide key targets to prevent chronic cerebrovascular disease, acute events, and vascular cognitive impairment.
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Affiliation(s)
- Alastair J S Webb
- Wolfson Centre for Prevention of Stroke and Dementia, University of Oxford, United Kingdom (A.J.S.W.)
| | - David J Werring
- Stroke Research Centre, UCL Queen Square Institute of Neurology, London, United Kingdom (D.J.W.)
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Abstract
PURPOSE OF REVIEW To discuss recent advances in the critical care management of acute ischaemic stroke patients and highlight controversies and consensus. RECENT FINDINGS Intravenous thrombolysis and endovascular thrombectomy are standard of care reperfusion therapies that have revolutionized the management of acute ischaemic stroke and transformed outcomes for patients. They can now be delivered in extended time windows and to those previously ineligible for intervention based on advanced neuroimaging criteria. Secondary systemic insults, such as hypo- and hypertension, hyperthermia or hyperglycaemia, which can extend the area of ischaemia must also be prevented or corrected to minimize infarct progression. Meticulous blood pressure management is of central importance, particularly in patients that have undergone reperfusion therapies. Neurological deterioration can occur because of infarct extension, haemorrhagic transformation or worsening cerebral oedema. Transcranial Doppler ultrasonography allows bedside, noninvasive evaluation of cerebral haemodynamics and is increasingly used in acute stroke triage, management and recovery prediction. The management of acute ischaemic stroke raises several ethical issues, and shared decision making is essential to ensure outcomes that are compatible with an individual patient's expectations. SUMMARY A bundle of medical, endovascular and surgical strategies implemented by a multidisciplinary team working to locally agreed protocols can improve long-term stroke outcomes.
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Nogueira RC, Aries M, Minhas JS, H Petersen N, Xiong L, Kainerstorfer JM, Castro P. Review of studies on dynamic cerebral autoregulation in the acute phase of stroke and the relationship with clinical outcome. J Cereb Blood Flow Metab 2022; 42:430-453. [PMID: 34515547 PMCID: PMC8985432 DOI: 10.1177/0271678x211045222] [Citation(s) in RCA: 24] [Impact Index Per Article: 12.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/11/2023]
Abstract
Acute stroke is associated with high morbidity and mortality. In the last decades, new therapies have been investigated with the aim of improving clinical outcomes in the acute phase post stroke onset. However, despite such advances, a large number of patients do not demonstrate improvement, furthermore, some unfortunately deteriorate. Thus, there is a need for additional treatments targeted to the individual patient. A potential therapeutic target is interventions to optimize cerebral perfusion guided by cerebral hemodynamic parameters such as dynamic cerebral autoregulation (dCA). This narrative led to the development of the INFOMATAS (Identifying New targets FOr Management And Therapy in Acute Stroke) project, designed to foster interventions directed towards understanding and improving hemodynamic aspects of the cerebral circulation in acute cerebrovascular disease states. This comprehensive review aims to summarize relevant studies on assessing dCA in patients suffering acute ischemic stroke, intracerebral haemorrhage, and subarachnoid haemorrhage. The review will provide to the reader the most consistent findings, the inconsistent findings which still need to be explored further and discuss the main limitations of these studies. This will allow for the creation of a research agenda for the use of bedside dCA information for prognostication and targeted perfusion interventions.
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Affiliation(s)
- Ricardo C Nogueira
- Neurology Department, School of Medicine, Hospital das Clinicas, University of São Paulo, São Paulo, Brazil.,Department of Neurology, Hospital Nove de Julho, São Paulo, Brazil
| | - Marcel Aries
- Department of Intensive Care, University of Maastricht, Maastricht University Medical Center+, School for Mental Health and Neuroscience (MHeNS), Maastricht, The Netherlands
| | - Jatinder S Minhas
- Cerebral Haemodynamics in Ageing and Stroke Medicine (CHiASM) Research Group, Department of Cardiovascular Sciences, NIHR Leicester Biomedical Research Centre, Glenfield Hospital, Leicester, UK
| | - Nils H Petersen
- Department of Neurology, Yale University School of Medicine, New Haven, USA
| | - Li Xiong
- Department of Medicine & Therapeutics, The Chinese University of Hong Kong, Hong Kong, China
| | - Jana M Kainerstorfer
- Department of Biomedical Engineering, Carnegie Mellon University, Pittsburgh, USA.,Neuroscience Institute, Carnegie Mellon University, Pittsburgh, USA
| | - Pedro Castro
- Department of Neurology, Faculty of Medicine of University of Porto, Centro Hospitalar Universitário de São João, Porto, Portugal
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Llwyd O, Fan JL, Müller M. Effect of drug interventions on cerebral hemodynamics in ischemic stroke patients. J Cereb Blood Flow Metab 2022; 42:471-485. [PMID: 34738511 PMCID: PMC8985436 DOI: 10.1177/0271678x211058261] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/06/2023]
Abstract
The ischemic penumbra is sensitive to alterations in cerebral perfusion. A myriad of drugs are used in acute ischemic stroke (AIS) management, yet their impact on cerebral hemodynamics is poorly understood. As part of the Cerebral Autoregulation Network led INFOMATAS project (Identifying New Targets for Management and Therapy in Acute Stroke), this paper reviews some of the most common drugs a patient with AIS will come across and their potential influence on cerebral hemodynamics with a particular focus being on cerebral autoregulation (CA). We first discuss how compounds that promote clot lysis and prevent clot formation could potentially impact cerebral hemodynamics, before focusing on how the different classes of antihypertensive drugs can influence cerebral hemodynamics. We discuss the different properties of each drug and their potential impact on cerebral perfusion and CA. With emerging interest in CA status of AIS patients, either during or soon after treatment when timely reperfusion and salvageable tissue is at its most critical, the properties of these pharmacological agents may be relevant for modelling cerebral perfusion accuracy and for setting individualised treatment strategies.
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Affiliation(s)
- Osian Llwyd
- Department of Cardiovascular Sciences, Cerebral Haemodynamics in Ageing and Stroke Medicine Research Group, University of Leicester, Leicester, UK
| | - Jui-Lin Fan
- Manaaki Manawa - The Centre for Heart Research, Department of Physiology, Faculty of Medical & Health Sciences, University of Auckland, Auckland, New Zealand
| | - Martin Müller
- Neurozentrum, Klinik für Neurologie und Neurorehabilitation, Luzerner Kantonsspital, Spitalstrasse, Luzern, Switzerland
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Svedung Wettervik T, Fahlström M, Enblad P, Lewén A. Cerebral Pressure Autoregulation in Brain Injury and Disorders-A Review on Monitoring, Management, and Future Directions. World Neurosurg 2021; 158:118-131. [PMID: 34775084 DOI: 10.1016/j.wneu.2021.11.027] [Citation(s) in RCA: 14] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/17/2021] [Revised: 11/03/2021] [Accepted: 11/05/2021] [Indexed: 12/14/2022]
Abstract
The role of cerebral pressure autoregulation (CPA) in brain injury and disorders has gained increased interest. The CPA is often disturbed as a consequence of acute brain injury, which contributes to further brain damage and worse outcome. Specifically, in severe traumatic brain injury, CPA disturbances predict worse clinical outcome and targeting an autoregulatory-oriented optimal cerebral perfusion pressure threshold may improve brain energy metabolism and clinical outcome. In aneurysmal subarachnoid hemorrhage, cerebral vasospasm in combination with distal autoregulatory disturbances precipitate delayed cerebral ischemia. The role of optimal cerebral perfusion pressure targets is less clear in aneurysmal subarachnoid hemorrhage, but high cerebral perfusion pressure targets are generally favorable in the vasospasm phase. In acute ischemia, autoregulatory disturbances may occur and autoregulatory-oriented blood pressure (optimal mean arterial pressure) management reduces the risk of hemorrhagic transformation, brain edema, and unfavorable outcome. In chronic occlusive disease such as moyamoya, the gradual reduction of the cerebral circulation leads to compensatory distal vasodilation and the residual CPA capacity predicts the risk for cerebral ischemia. In spontaneous intracerebral hemorrhage, the role of autoregulatory disturbances is less clear, but CPA disturbances correlate with worse clinical outcome. Also, in community-acquired bacterial meningitis, CPA dysfunction is frequent and correlates with worse clinical outcome, but autoregulatory management is yet to be evaluated. In this review, we discuss the role of CPA in different types of brain injury and disease, the strengths and limitations of the monitoring methods, the potentials of autoregulatory management, and future directions in the field.
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Affiliation(s)
| | - Markus Fahlström
- Department of Surgical Sciences, Section of Radiology, Uppsala University, Uppsala, Sweden
| | - Per Enblad
- Department of Neuroscience, Section of Neurosurgery, Uppsala University, Uppsala, Sweden
| | - Anders Lewén
- Department of Neuroscience, Section of Neurosurgery, Uppsala University, Uppsala, Sweden
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15
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Bergman L, Cluver C, Carlberg N, Belfort M, Tolcher MC, Panerai RB, van Veen T. Cerebral perfusion pressure and autoregulation in eclampsia-a case control study. Am J Obstet Gynecol 2021; 225:185.e1-185.e9. [PMID: 33744176 DOI: 10.1016/j.ajog.2021.03.017] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/28/2020] [Revised: 01/31/2021] [Accepted: 03/02/2021] [Indexed: 11/28/2022]
Abstract
BACKGROUND Dynamic cerebral autoregulation and cerebral perfusion pressure are altered in pregnancies complicated by preeclampsia compared with normotensive pregnancies, but the connections of dynamic cerebral autoregulation, cerebral perfusion pressure, and cerebral complications in preeclampsia remain unclear. OBJECTIVE This study aimed to assess dynamic cerebral autoregulation and cerebral perfusion pressure after delivery in women with eclampsia, in women with preeclampsia both with and without severe features, and in normotensive women. STUDY DESIGN This was a prospective case control study at a large referral hospital in Cape Town, South Africa. The recruitment of participants was done at diagnosis (cases) or at admission for delivery (controls). Transcranial Doppler examinations with continuous noninvasive blood pressure measurements and end-tidal CO2 monitoring were conducted for cases and controls after delivery. Cerebral perfusion pressure and dynamic cerebral autoregulation index were calculated, and values were compared among groups. RESULTS We included 16 women with eclampsia, 18 women with preeclampsia with severe features, 32 women with preeclampsia without severe features, and 21 normotensive women with uncomplicated pregnancies. Dynamic cerebral autoregulation was depressed in pregnant women with eclampsia; (autoregulation index, 3.9; interquartile range, 3.1-5.2) compared with all other groups (those with preeclampsia with severe features, autoregulation index, 5.6 [interquartile range, 4.4-6.8]; those with preeclampsia without severe features, autoregulation index, 6.8 [interquartile range, 5.1-7.4]; and normotensive controls, autoregulation index, 7.1 [interquartile range, 6.1-7.9]). Pregnant women with eclampsia had increased cerebral perfusion pressure (109.5 mm Hg; interquartile range, 91.2-130.9) compared with those with preeclampsia without severe features and those with normal blood pressure (84 mm Hg [interquartile range, 73.0-122.0] and 80.0 mm Hg [interquartile range, 67.5-92.0], respectively); furthermore, there was no difference in cerebral perfusion pressure between pregnant women with eclampsia and pregnant women with preeclampsia with severe features (109.5 mm Hg [interquartile range, 91.2-130.9] vs 96.5 mm Hg [interquartile range, 75.8-110.5]). CONCLUSION Cerebral perfusion pressure and dynamic cerebral autoregulation are altered in eclampsia and may be important in the pathophysiological pathway and constitute a therapeutic target in the prevention of cerebral complications in preeclampsia.
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Affiliation(s)
- Lina Bergman
- Department of Obstetrics and Gynecology, Stellenbosch University, Cape Town, South Africa; Department of Women's and Children's Health, Uppsala University, Uppsala, Sweden; Department of Obstetrics and Gynecology, Institute of Clinical Sciences, Sahlgrenska Academy, University of Gothenburg, Gothenburg, Sweden.
| | - Catherine Cluver
- Department of Obstetrics and Gynecology, Stellenbosch University, Cape Town, South Africa; Translational Obstetrics Group, Department of Obstetrics and Gynaecology, University of Melbourne, Victoria, Australia; Mercy Perinatal, Mercy Hospital for Women, Heidelberg, Victoria, Australia
| | - Niclas Carlberg
- Department of Anesthesiology, Institute of Clinical Sciences, Sahlgrenska Academy, University of Gothenburg, Gothenburg, Sweden
| | - Michael Belfort
- Department of Obstetrics and Gynecology, Baylor College of Medicine, Houston, TX
| | - Mary C Tolcher
- Department of Obstetrics and Gynecology, Baylor College of Medicine, Houston, TX
| | - Ronney B Panerai
- Department of Cardiovascular Sciences, University of Leicester, Leicester, United Kingdom
| | - Teelkien van Veen
- Department of Obstetrics and Gynecology, University Medical Center Groningen, Groningen, the Netherlands
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Zhong C, Yin C, Niu G, Ning L, Pan J. MicroRNA miR-497 is closely associated with poor prognosis in patients with cerebral ischemic stroke. Bioengineered 2021; 12:2851-2862. [PMID: 34152256 PMCID: PMC8806653 DOI: 10.1080/21655979.2021.1940073] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/19/2022] Open
Abstract
Cerebral ischemic stroke (CIS) is the most common type of stroke, which is highly hazardous. This investigation aims to analyze the correlation of miR-497 with CIS, so as to provide reliable evidence for clinical response to CIS and lay a solid foundation for follow-up research. Eighty-nine CIS patients and 39 concurrent physical examinees selected between June 2017 and October 2018 were enrolled as the research participants. Additionally, SD rats with increased miR-497 expression and normal SD rats were purchased for CIS modeling to observe the clinical implications of miR-497 in CIS, as well as the water content of brain tissue and neuronal apoptosis of rats. miR-497 expression was lower in CIS patients than in physical examinees, and that in patients with complete stroke (CS) was the lowest, which increased after treatment. As determined by the receiver operating characteristic curve (ROC) analysis, miR-497 had an outstanding diagnostic efficacy for CIS and was negatively correlated with the National Institutes of Health Stroke Scale (NIHSS) and MDA concentration, while positively related to SOD concentration. Prognostic follow-up demonstrated that decreased miR-497 expression in patients after treatment predicted an increased risk of prognostic death and recurrence. However, observed in rats, the water content of the brain tissue of rats with increased miR-497 expression was reduced, and the neuronal apoptosis rate of the brain tissue was inhibited. Taken together, with low expression in CIS, miR-497 is strongly related to CIS progression and is a candidate CIS marker.
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Affiliation(s)
- Changyang Zhong
- Department of Neurology, Hangzhou Third People's Hospital, Hangzhou, Zhejiang, China
| | - Congguo Yin
- Department of Neurology, Hangzhou First People's Hospital, Hangzhou, Zhejiang, China
| | - Guozhong Niu
- Department of Neurology, Hangzhou First People's Hospital, Hangzhou, Zhejiang, China
| | - Li Ning
- Nursing Department, Hangzhou First People's Hospital, Hangzhou, Zhejiang, China
| | - Jinbo Pan
- Department of ICU, Hangzhou Third People's Hospital, Hangzhou, Zhejiang, China
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Nogueira RC, Beishon L, Bor-Seng-Shu E, Panerai RB, Robinson TG. Cerebral Autoregulation in Ischemic Stroke: From Pathophysiology to Clinical Concepts. Brain Sci 2021; 11:511. [PMID: 33923721 PMCID: PMC8073938 DOI: 10.3390/brainsci11040511] [Citation(s) in RCA: 15] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/22/2021] [Revised: 04/02/2021] [Accepted: 04/09/2021] [Indexed: 11/17/2022] Open
Abstract
Ischemic stroke (IS) is one of the most impacting diseases in the world. In the last decades, new therapies have been introduced to improve outcomes after IS, most of them aiming for recanalization of the occluded vessel. However, despite this advance, there are still a large number of patients that remain disabled. One interesting possible therapeutic approach would be interventions guided by cerebral hemodynamic parameters such as dynamic cerebral autoregulation (dCA). Supportive hemodynamic therapies aiming to optimize perfusion in the ischemic area could protect the brain and may even extend the therapeutic window for reperfusion therapies. However, the knowledge of how to implement these therapies in the complex pathophysiology of brain ischemia is challenging and still not fully understood. This comprehensive review will focus on the state of the art in this promising area with emphasis on the following aspects: (1) pathophysiology of CA in the ischemic process; (2) methodology used to evaluate CA in IS; (3) CA studies in IS patients; (4) potential non-reperfusion therapies for IS patients based on the CA concept; and (5) the impact of common IS-associated comorbidities and phenotype on CA status. The review also points to the gaps existing in the current research to be further explored in future trials.
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Affiliation(s)
- Ricardo C. Nogueira
- Neurology Department, School of Medicine, Hospital das Clinicas, University of São Paulo, São Paulo 01246-904, Brazil;
- Department of Neurology, Hospital Nove de Julho, São Paulo 01409-002, Brazil
| | - Lucy Beishon
- Cerebral Haemodynamics in Ageing and Stroke Medicine Research Group, Department of Cardiovascular Sciences, University of Leicester, Leicester LE2 7LX, UK; (L.B.); (R.B.P.); (T.G.R.)
| | - Edson Bor-Seng-Shu
- Neurology Department, School of Medicine, Hospital das Clinicas, University of São Paulo, São Paulo 01246-904, Brazil;
| | - Ronney B. Panerai
- Cerebral Haemodynamics in Ageing and Stroke Medicine Research Group, Department of Cardiovascular Sciences, University of Leicester, Leicester LE2 7LX, UK; (L.B.); (R.B.P.); (T.G.R.)
- National Institute for Health Research (NIHR) Leicester Biomedical Research Centre, University of Leicester, Leicester LE5 4PW, UK
| | - Thompson G. Robinson
- Cerebral Haemodynamics in Ageing and Stroke Medicine Research Group, Department of Cardiovascular Sciences, University of Leicester, Leicester LE2 7LX, UK; (L.B.); (R.B.P.); (T.G.R.)
- National Institute for Health Research (NIHR) Leicester Biomedical Research Centre, University of Leicester, Leicester LE5 4PW, UK
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