1
|
Liu M, He E, Fu X, Gong S, Han Y, Deng F. Cerebral blood flow self-regulation in depression. J Affect Disord 2022; 302:324-331. [PMID: 35032508 DOI: 10.1016/j.jad.2022.01.057] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 10/29/2021] [Revised: 12/21/2021] [Accepted: 01/11/2022] [Indexed: 11/30/2022]
Abstract
BACKGROUND Depression is a common neuropsychiatric disease with a high prevalence rate. Sleep problems, memory decline, dizziness and headaches are the most common neurological symptoms in depressed patients. Abnormality of cerebral blood flow (CBF) has been observed in depressive patients, but those patients did not have intracranial structural damage. Both of those phenomena might be related to cerebral blood flow self-regulation (CBFSR: cerebral blood flow self-regulation). CBFSR can maintain CBF relatively stable in response to changes in neurological and metabolic factors. Therefore, this review aimed to discuss CBFSR in depression. METHODS We searched for keywords such as "depression", "cerebral blood flow", "cerebral autoregulation", "cerebrovascular reactivity" and the words related to depression. We analyzed whether there is a change in the CBFSR in depression, further explored whether there is a relationship between the pathogenesis of depression and the CBFSR, and discussed the possible mechanism of impaired CBFSR in patients with depression. RESULTS Discovered by the literature review, CBFSR is significantly impaired in depressed patients. The level of circulating markers of endothelial dysfunction, nitric oxide, inflammatory cytokines, glucocorticoid and monoamine neurotransmitters is mostly abnormal in depression, which affected the CBFSR to varying degrees. LIMITATIONS Limitations include the small number of direct studies about depression and CBFSR mechanisms. CONCLUSION CBFSR is impaired in depression. The underlying mechanisms include endothelial dysfunction, overactivation of microglia and changes of cytokines, hyperactivation of the HPA axis, increased oxidative stress, monoamine neurotransmitter disorders, etc. These deepened our understanding of the clinical symptoms of depressed patients.
Collapse
Affiliation(s)
- Min Liu
- Department of Neurology, The First Hospital of Jilin University, No.1, Xinmin Street, Changchun, China
| | - Enling He
- Department of Neurology, The First Hospital of Jilin University, No.1, Xinmin Street, Changchun, China
| | - Xiyao Fu
- Department of Neurology, The First Hospital of Jilin University, No.1, Xinmin Street, Changchun, China
| | - Sizhu Gong
- Department of Neurology, The First Hospital of Jilin University, No.1, Xinmin Street, Changchun, China
| | - Yue Han
- Department of Neurology, The First Hospital of Jilin University, No.1, Xinmin Street, Changchun, China
| | - Fang Deng
- Department of Neurology, The First Hospital of Jilin University, No.1, Xinmin Street, Changchun, China.
| |
Collapse
|
2
|
Claassen JAHR, Thijssen DHJ, Panerai RB, Faraci FM. Regulation of cerebral blood flow in humans: physiology and clinical implications of autoregulation. Physiol Rev 2021; 101:1487-1559. [PMID: 33769101 PMCID: PMC8576366 DOI: 10.1152/physrev.00022.2020] [Citation(s) in RCA: 273] [Impact Index Per Article: 91.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/07/2023] Open
Abstract
Brain function critically depends on a close matching between metabolic demands, appropriate delivery of oxygen and nutrients, and removal of cellular waste. This matching requires continuous regulation of cerebral blood flow (CBF), which can be categorized into four broad topics: 1) autoregulation, which describes the response of the cerebrovasculature to changes in perfusion pressure; 2) vascular reactivity to vasoactive stimuli [including carbon dioxide (CO2)]; 3) neurovascular coupling (NVC), i.e., the CBF response to local changes in neural activity (often standardized cognitive stimuli in humans); and 4) endothelium-dependent responses. This review focuses primarily on autoregulation and its clinical implications. To place autoregulation in a more precise context, and to better understand integrated approaches in the cerebral circulation, we also briefly address reactivity to CO2 and NVC. In addition to our focus on effects of perfusion pressure (or blood pressure), we describe the impact of select stimuli on regulation of CBF (i.e., arterial blood gases, cerebral metabolism, neural mechanisms, and specific vascular cells), the interrelationships between these stimuli, and implications for regulation of CBF at the level of large arteries and the microcirculation. We review clinical implications of autoregulation in aging, hypertension, stroke, mild cognitive impairment, anesthesia, and dementias. Finally, we discuss autoregulation in the context of common daily physiological challenges, including changes in posture (e.g., orthostatic hypotension, syncope) and physical activity.
Collapse
Affiliation(s)
- Jurgen A H R Claassen
- Department of Geriatrics, Radboud University Medical Center, Donders Institute for Brain, Cognition, and Behaviour, Nijmegen, The Netherlands
| | - Dick H J Thijssen
- Department of Physiology, Radboud Institute for Health Sciences, Nijmegen, The Netherlands
- Research Institute for Sport and Exercise Sciences, Liverpool John Moores University, Liverpool, United Kingdom
| | - Ronney B Panerai
- Department of Cardiovascular Sciences, University of Leicester, Leicester, United Kingdom
- >National Institute for Health Research Leicester Biomedical Research Centre, University of Leicester, Leicester, United Kingdom
| | - Frank M Faraci
- Departments of Internal Medicine, Neuroscience, and Pharmacology, Carver College of Medicine, University of Iowa, Iowa City, Iowa
| |
Collapse
|
3
|
Panerai RB, Intharakham K, Haunton V, Minhas JS, Llwyd O, Lam M, Salinet ASM, Nogueira RC, Katsogridakis E, Maggio P, Robinson TG. Chasing the evidence: the influence of data segmentation on estimates of dynamic cerebral autoregulation. Physiol Meas 2020; 41:035006. [PMID: 32150740 DOI: 10.1088/1361-6579/ab7ddf] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
Abstract
OBJECTIVE Transfer function analysis (TFA) of dynamic cerebral autoregulation (dCA) requires smoothing of spectral estimates using segmentation of the data (SD). Systematic studies are required to elucidate the potential influence of SD on dCA parameters. APPROACH Healthy subjects (HS, n = 237) and acute ischaemic stroke patients (AIS, n = 98) were included. Cerebral blood flow velocity (CBFV, transcranial Doppler ultrasound) was recorded supine at rest with continuous arterial blood pressure (BP, Finometer) for a minimum of 5 min. TFA was performed with durations SD = 100, 50 or 25 s and 50% superposition to derive estimates of coherence, gain and phase for the BP-CBFV relationship. The autoregulation index (ARI) was estimated from the CBFV step response. Intrasubject reproducibility was expressed by the intraclass correlation coefficient (ICC). MAIN RESULTS In HS, the ARI, coherence, gain, and phase (low frequency) were influenced by SD, but in AIS, phase (very low frequency) and ARI were not affected. ICC was excellent (>0.75) for all parameters, for both HS and AIS. For SD = 100 s, ARI was different between HS and AIS (mean ± sdev: 5.70 ± 1.61 vs 5.1 ± 2.0; p < 0.01) and the significance of this difference was maintained for SD = 50 s and 25 s. Using SD = 100 s as reference, the rate of misclassification, based on a threshold of ARI ⩽ 4, was 6.3% for SD = 50 s and 8.1% for SD = 25 s in HS, with corresponding values of 11.7% and 8.2% in AIS patients, respectively. SIGNIFICANCE Further studies are warranted with SD values lower than the recommended standard of SD = 100 s, to explore possibilities of improving the reproducibility, sensitivity and prognostic value of TFA parameters used as metrics of dCA.
Collapse
Affiliation(s)
- Ronney B Panerai
- Cerebral Haemodynamics in Ageing and Stroke Medicine (CHiASM) Research Group, Department of Cardiovascular Sciences, University of Leicester, Leicester, United Kingdom. Glenfield Hospital, NIHR Leicester Biomedical Research Centre, British Heart Foundation Cardiovascular Research Centre, Leicester, United Kingdom
| | | | | | | | | | | | | | | | | | | | | |
Collapse
|
4
|
Intharakham K, Beishon L, Panerai RB, Haunton VJ, Robinson TG. Assessment of cerebral autoregulation in stroke: A systematic review and meta-analysis of studies at rest. J Cereb Blood Flow Metab 2019; 39:2105-2116. [PMID: 31433714 PMCID: PMC6827119 DOI: 10.1177/0271678x19871013] [Citation(s) in RCA: 35] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/17/2022]
Abstract
Dynamic cerebral autoregulation (dCA) has been shown to be impaired in cerebrovascular diseases, but there is a lack of consistency across different studies and the different metrics that have been proposed for assessment. We performed a systematic review and meta-analyses involving assessment of dCA in ischemic and hemorrhagic stroke. Thirty-three articles describing assessment of dCA with transfer function analysis (TFA) were included, with meta-analyses performed for derived parameters of gain, phase and autoregulation index (ARI). A total of 1233 patients were pooled from 12 studies on acute ischemic stroke (AIS) and two studies on intracerebral hemorrhage (ICH). In comparison with controls, TFA phase of AIS was significantly reduced (nine studies), in both hemispheres (P < 0.0001). TFA gain provided inconsistent results, with reduced values in relation to controls, for both hemispheres. The ARI (six studies) was reduced compared to controls, in both hemispheres (P < 0.005). In ICH, gain showed higher values compared to controls for the unaffected (P = 0.01), but not for the affected hemisphere. Meta-analyses in AIS have demonstrated that phase and the ARI index can show highly significant differences in comparison with healthy controls, while ICH have been limited by the scarcity of studies and the diversity of units adopted for gain.
Collapse
Affiliation(s)
| | - Lucy Beishon
- Department of Cardiovascular Sciences, University of Leicester, Leicester, UK
| | - Ronney B Panerai
- Department of Cardiovascular Sciences, University of Leicester, Leicester, UK.,NIHR Leicester Biomedical Research Centre, British Heart Foundation Cardiovascular Research Centre, Glenfield Hospital, Leicester, UK
| | - Victoria J Haunton
- Department of Cardiovascular Sciences, University of Leicester, Leicester, UK.,NIHR Leicester Biomedical Research Centre, British Heart Foundation Cardiovascular Research Centre, Glenfield Hospital, Leicester, UK
| | - Thompson G Robinson
- Department of Cardiovascular Sciences, University of Leicester, Leicester, UK.,NIHR Leicester Biomedical Research Centre, British Heart Foundation Cardiovascular Research Centre, Glenfield Hospital, Leicester, UK
| |
Collapse
|
5
|
de Jong DLK, Tarumi T, Liu J, Zhang R, Claassen JAHR. Lack of linear correlation between dynamic and steady-state cerebral autoregulation. J Physiol 2017; 595:5623-5636. [PMID: 28597991 PMCID: PMC5556173 DOI: 10.1113/jp274304] [Citation(s) in RCA: 23] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/14/2017] [Accepted: 06/06/2017] [Indexed: 01/15/2023] Open
Abstract
Key points For correct application and interpretation of cerebral autoregulation (CA) measurements in research and in clinical care, it is essential to understand differences and similarities between dynamic and steady‐state CA. The present study found no correlation between dynamic and steady‐state CA indices in healthy older adults. There was variability between individuals in all (steady‐state and dynamic) autoregulatory indices, ranging from low (almost absent) to highly efficient CA in this healthy population. These findings challenge the assumption that assessment of a single CA parameter or a single set of parameters can be generalized to overall CA functioning. Therefore, depending on specific research purposes, the choice for either steady‐state or dynamic measures or both should be weighed carefully.
Abstract The present study aimed to investigate the relationship between dynamic (dCA) and steady‐state cerebral autoregulation (sCA). In 28 healthy older adults, sCA was quantified by a linear regression slope of proportionate (%) changes in cerebrovascular resistance (CVR) in response to proportionate (%) changes in mean blood pressure (BP) induced by stepwise sodium nitroprusside (SNP) and phenylephrine (PhE) infusion. Cerebral blood flow (CBF) was measured at the internal carotid artery (ICA) and vertebral artery (VA) and CBF velocity at the middle cerebral artery (MCA). With CVR = BP/CBF, Slope‐CVRICA, Slope‐CVRVA and Slope‐CVRiMCA were derived. dCA was assessed (i) in supine rest, analysed with transfer function analysis (gain and phase) and autoregulatory index (ARI) fit from spontaneous oscillations (ARIBaseline), and (ii) with transient changes in BP using a bolus injection of SNP (ARISNP) and PhE (ARIPhE). Comparison of sCA and dCA parameters (using Pearson's r for continuous and Spearman's ρ for ordinal parameters) demonstrated a lack of linear correlations between sCA and dCA measures. However, comparisons of parameters within dCA and within sCA were correlated. For sCA slope‐CVRVA with Slope‐CVRiMCA (r = 0.45, P < 0.03); for dCA ARISNP with ARIPhE (ρ = 0.50, P = 0.03), ARIBaseline (ρ = 0.57, P = 0.03) and PhaseLF (ρ = 0.48, P = 0.03); and for GainVLF with GainLF (r = 0.51, P = 0.01). By contrast to the commonly held assumption based on an earlier study, there were no linear correlations between sCA and dCA. As an additional observation, there was strong inter‐individual variability, both in dCA and sCA, in this healthy group of elderly, in a range from low to high CA efficiency. For correct application and interpretation of cerebral autoregulation (CA) measurements in research and in clinical care, it is essential to understand differences and similarities between dynamic and steady‐state CA. The present study found no correlation between dynamic and steady‐state CA indices in healthy older adults. There was variability between individuals in all (steady‐state and dynamic) autoregulatory indices, ranging from low (almost absent) to highly efficient CA in this healthy population. These findings challenge the assumption that assessment of a single CA parameter or a single set of parameters can be generalized to overall CA functioning. Therefore, depending on specific research purposes, the choice for either steady‐state or dynamic measures or both should be weighed carefully.
Collapse
Affiliation(s)
- Daan L K de Jong
- Donders Institute for Brain, Cognition and Behavior, Radboud Alzheimer Center, and Department of Geriatric Medicine, Radboud University Medical Center, Nijmegen, The Netherlands
| | - Takashi Tarumi
- Institute for Exercise and Environmental Medicine, Texas Health Presbyterian Hospital Dallas, Texas, USA.,Department of Internal Medicine
| | - Jie Liu
- Institute for Exercise and Environmental Medicine, Texas Health Presbyterian Hospital Dallas, Texas, USA.,Department of Internal Medicine
| | - Rong Zhang
- Institute for Exercise and Environmental Medicine, Texas Health Presbyterian Hospital Dallas, Texas, USA.,Department of Internal Medicine.,Department of Neurology and Neurotherapeutics, University of Texas Southwestern Medical Center, Texas, USA
| | - Jurgen A H R Claassen
- Donders Institute for Brain, Cognition and Behavior, Radboud Alzheimer Center, and Department of Geriatric Medicine, Radboud University Medical Center, Nijmegen, The Netherlands
| |
Collapse
|
6
|
Xiong L, Liu X, Shang T, Smielewski P, Donnelly J, Guo ZN, Yang Y, Leung T, Czosnyka M, Zhang R, Liu J, Wong KS. Impaired cerebral autoregulation: measurement and application to stroke. J Neurol Neurosurg Psychiatry 2017; 88:520-531. [PMID: 28536207 DOI: 10.1136/jnnp-2016-314385] [Citation(s) in RCA: 89] [Impact Index Per Article: 12.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 08/31/2016] [Revised: 01/05/2017] [Accepted: 01/09/2017] [Indexed: 11/04/2022]
Abstract
Cerebral autoregulation (CA) is a protective mechanism that maintains cerebral blood flow at a relatively constant level despite fluctuations of cerebral perfusion pressure or arterial blood pressure. It is a universal physiological mechanism that may involve myogenic, neural control as well as metabolic regulations of cerebral vasculature in response to changes in pressure or cerebral blood flow. Traditionally, CA has been represented by a sigmoid curve with a wide plateau between about 50 mm Hg and 170 mm Hg of steady-state changes in mean arterial pressure, defined as static CA. With the advent of transcranial Doppler, measurement of cerebral blood flow in response to transient changes in arterial pressure has been used to assess dynamic CA. However, a gold standard for measuring CA is not currently available. Stroke has been the leading cause of long-term adult disability throughout the world. A better understanding of CA and its response to pathological derangements can help assess the severity of stroke, guide management decisions, assess response to interventions and provide prognostic information. The objective of this review is to provide a comprehensive insight about physiology of autoregulation, measurement methodologies and clinical applications in stroke to help build a consensus for what should be included in an internationally agreed protocol for CA testing and monitoring, and to promote its translation into clinical bedside practice for stroke management.
Collapse
Affiliation(s)
- Li Xiong
- Department of Medicine and Therapeutics, The Chinese University of Hong Kong, Prince of Wales Hospital, Hong Kong, China
| | - Xiuyun Liu
- Department of Clinical Neurosciences, Brain Physics Laboratory, Division of Neurosurgery, University of Cambridge, Cambridge, UK
| | - Ty Shang
- Department of Neurology and Neurotherapeutics, University of Texas Southwestern Medical Center, Dallas, Texas, USA
| | - Peter Smielewski
- Department of Clinical Neurosciences, Brain Physics Laboratory, Division of Neurosurgery, University of Cambridge, Cambridge, UK
| | - Joseph Donnelly
- Department of Clinical Neurosciences, Brain Physics Laboratory, Division of Neurosurgery, University of Cambridge, Cambridge, UK
| | - Zhen-Ni Guo
- Department of Neurology, Neuroscience Center, The First Norman Bethune Hospital of Jilin University, Changchun, China
| | - Yi Yang
- Chinese Academy of Sciences, Shenzhen Institutes of Advanced Technology, Shenzhen, China
| | - Thomas Leung
- Department of Medicine and Therapeutics, The Chinese University of Hong Kong, Prince of Wales Hospital, Hong Kong, China
| | - Marek Czosnyka
- Department of Clinical Neurosciences, Brain Physics Laboratory, Division of Neurosurgery, University of Cambridge, Cambridge, UK
| | - Rong Zhang
- Department of Neurology and Neurotherapeutics, University of Texas Southwestern Medical Center, Dallas, Texas, USA
| | - Jia Liu
- Chinese Academy of Sciences, Shenzhen Institutes of Advanced Technology, Shenzhen, China
| | - Ka Sing Wong
- Department of Medicine and Therapeutics, The Chinese University of Hong Kong, Prince of Wales Hospital, Hong Kong, China
| |
Collapse
|
7
|
Goodson CM, Rosenblatt K, Rivera-Lara L, Nyquist P, Hogue CW. Cerebral Blood Flow Autoregulation in Sepsis for the Intensivist: Why Its Monitoring May Be the Future of Individualized Care. J Intensive Care Med 2016; 33:63-73. [PMID: 27798314 DOI: 10.1177/0885066616673973] [Citation(s) in RCA: 27] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/12/2022]
Abstract
Cerebral blood flow (CBF) autoregulation maintains consistent blood flow across a range of blood pressures (BPs). Sepsis is a common cause of systemic hypotension and cerebral dysfunction. Guidelines for BP management in sepsis are based on historical concepts of CBF autoregulation that have now evolved with the availability of more precise technology for its measurement. In this article, we provide a narrative review of methods of monitoring CBF autoregulation, the cerebral effects of sepsis, and the current knowledge of CBF autoregulation in sepsis. Current guidelines for BP management in sepsis are based on a goal of maintaining mean arterial pressure (MAP) above the lower limit of CBF autoregulation. Bedside tools are now available to monitor CBF autoregulation continuously. These data reveal that individual BP goals determined from CBF autoregulation monitoring are more variable than previously expected. In patients undergoing cardiac surgery with cardiopulmonary bypass, for example, the lower limit of autoregulation varied between a MAP of 40 to 90 mm Hg. Studies of CBF autoregulation in sepsis suggest patients frequently manifest impaired CBF autoregulation, possibly a result of BP below the lower limit of autoregulation, particularly in early sepsis or with sepsis-associated encephalopathy. This suggests that the present consensus guidelines for BP management in sepsis may expose some patients to both cerebral hypoperfusion and cerebral hyperperfusion, potentially resulting in damage to brain parenchyma. The future use of novel techniques to study and clinically monitor CBF autoregulation could provide insight into the cerebral pathophysiology of sepsis and offer more precise treatments that may improve functional and cognitive outcomes for survivors of sepsis.
Collapse
Affiliation(s)
- Carrie M Goodson
- 1 Division of Pulmonary and Critical Care Medicine, Johns Hopkins University School of Medicine, Baltimore, MD, USA
| | - Kathryn Rosenblatt
- 2 Department of Neurology, Johns Hopkins University School of Medicine, Baltimore, MD, USA.,3 Department of Anesthesiology and Critical Care Medicine, Johns Hopkins University School of Medicine, Baltimore, MD, USA
| | - Lucia Rivera-Lara
- 2 Department of Neurology, Johns Hopkins University School of Medicine, Baltimore, MD, USA.,3 Department of Anesthesiology and Critical Care Medicine, Johns Hopkins University School of Medicine, Baltimore, MD, USA
| | - Paul Nyquist
- 2 Department of Neurology, Johns Hopkins University School of Medicine, Baltimore, MD, USA.,3 Department of Anesthesiology and Critical Care Medicine, Johns Hopkins University School of Medicine, Baltimore, MD, USA
| | - Charles W Hogue
- 4 Department of Anesthesiology, Feinberg School of Medicine, Northwestern University, Chicago, IL, USA
| |
Collapse
|
8
|
Marshall RS, Pavol MA, Cheung YK, Strom I, Slane K, Asllani I, Lazar RM. Dissociation among hemodynamic measures in asymptomatic high grade carotid artery stenosis. J Neurol Sci 2016; 367:143-7. [PMID: 27423579 DOI: 10.1016/j.jns.2016.05.011] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/23/2015] [Revised: 05/04/2016] [Accepted: 05/06/2016] [Indexed: 12/18/2022]
Abstract
BACKGROUND Cerebral blood flow (CBF) regulation is a critical element in cerebrovascular pathophysiology, particularly in large vessel disease, but the best method to use for hemodynamic assessment is not clear. We examined 4 different blood-flow related measures in patients with unilateral high-grade carotid artery disease, assessing asymmetry between the occluded vs non-occluded side, and the correlations among the measures. METHODS Thirty-three patients (age 50-93, 19 M) with unilateral 80-100% ICA occlusion but no stroke underwent: 1) mean flow velocity (MFV) in both middle cerebral arteries by transcranial Doppler (TCD), 2) quantitative resting CBF using pseudo-continuous arterial spin labeling (pCASL) MRI, 3) vasomotor reactivity (VMR) in response to 5% CO2 inhalation, and 4) dynamic cerebral autoregulation (DCA) assessing the counter-regulation of blood flow to spontaneous changes in blood pressure using TCD monitoring and finger photoplethysmography. Paired t-tests and Pearson correlations assessed side-to-side differences within each measure, and correlations between measures. RESULTS CBF (p=0.001), MFV (p<0.001), VMR (p=0.008), and DCA (p=0.047) all showed significantly lower values on the occluded side. The 4 measures were independent of each other on correlation analysis, even when controlling for age and anterior circle of Willis collateral (all partial correlations <0.233 and p-values >0.468). CONCLUSIONS These 4 measures showed high sensitivity to the occluded carotid artery, but their dissociation suggests that any given measure only partially characterizes the hemodynamic state. Additional research is needed to explore the multifaceted biology of cerebral blood flow regulation.
Collapse
Affiliation(s)
| | - MaryKay A Pavol
- Columbia University, Department of Neurology, New York, United States
| | - Ying K Cheung
- Department of Biostatistics, Columbia University, New York, United States
| | - Isabelle Strom
- Columbia University, Department of Neurology, New York, United States
| | - Kevin Slane
- Columbia University, Department of Neurology, New York, United States
| | - Iris Asllani
- Rochester Institute of Neurology, Rochester, New York, United States
| | - Ronald M Lazar
- Columbia University, Department of Neurology, New York, United States
| |
Collapse
|
9
|
Smirl JD, Hoffman K, Tzeng YC, Hansen A, Ainslie PN. Methodological comparison of active- and passive-driven oscillations in blood pressure; implications for the assessment of cerebral pressure-flow relationships. J Appl Physiol (1985) 2015; 119:487-501. [PMID: 26183476 DOI: 10.1152/japplphysiol.00264.2015] [Citation(s) in RCA: 93] [Impact Index Per Article: 10.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/27/2015] [Accepted: 07/15/2015] [Indexed: 11/22/2022] Open
Abstract
We examined the between-day reproducibility of active (squat-stand maneuvers)- and passive [oscillatory lower-body negative pressure (OLBNP) maneuvers]-driven oscillations in blood pressure. These relationships were examined in both younger (n = 10; 25 ± 3 yr) and older (n = 9; 66 ± 4 yr) adults. Each testing protocol incorporated rest (5 min), followed by driven maneuvers at 0.05 (5 min) and 0.10 (5 min) Hz to increase blood-pressure variability and improve assessment of the pressure-flow dynamics using linear transfer function analysis. Beat-to-beat blood pressure, middle cerebral artery velocity, and end-tidal partial pressure of CO2 were monitored. The pressure-flow relationship was quantified in the very low (0.02-0.07 Hz) and low (0.07-0.20 Hz) frequencies (LF; spontaneous data) and at 0.05 and 0.10 Hz (driven maneuvers point estimates). Although there were no between-age differences, very few spontaneous and OLBNP transfer function metrics met the criteria for acceptable reproducibility, as reflected in a between-day, within-subject coefficient of variation (CoV) of <20%. Combined CoV data consist of LF coherence (15.1 ± 12.2%), LF gain (15.1 ± 12.2%), and LF normalized gain (18.5 ± 10.9%); OLBNP data consist of 0.05 (12.1 ± 15.%) and 0.10 (4.7 ± 7.8%) Hz coherence. In contrast, the squat-stand maneuvers revealed that all metrics (coherence: 0.6 ± 0.5 and 0.3 ± 0.5%; gain: 17.4 ± 12.3 and 12.7 ± 11.0%; normalized gain: 16.7 ± 10.9 and 15.7 ± 11.0%; and phase: 11.6 ± 10.2 and 17.3 ± 10.8%) at 0.05 and 0.10 Hz, respectively, were considered biologically acceptable for reproducibility. These findings have important implications for the reliable assessment and interpretation of cerebral pressure-flow dynamics in humans.
Collapse
Affiliation(s)
- Jonathan D Smirl
- Centre for Heart, Lung and Vascular Health, School of Health and Exercise Sciences, University of British Columbia, Okanagan Campus, British Columbia, Canada; and
| | - Keegan Hoffman
- Centre for Heart, Lung and Vascular Health, School of Health and Exercise Sciences, University of British Columbia, Okanagan Campus, British Columbia, Canada; and
| | - Yu-Chieh Tzeng
- Cardiovascular Systems Laboratory, Centre for Translational Physiology, University of Otago, Wellington, New Zealand
| | - Alex Hansen
- Centre for Heart, Lung and Vascular Health, School of Health and Exercise Sciences, University of British Columbia, Okanagan Campus, British Columbia, Canada; and
| | - Philip N Ainslie
- Centre for Heart, Lung and Vascular Health, School of Health and Exercise Sciences, University of British Columbia, Okanagan Campus, British Columbia, Canada; and
| |
Collapse
|
10
|
Guo ZN, Shao A, Tong LS, Sun W, Liu J, Yang Y. The Role of Nitric Oxide and Sympathetic Control in Cerebral Autoregulation in the Setting of Subarachnoid Hemorrhage and Traumatic Brain Injury. Mol Neurobiol 2015; 53:3606-3615. [DOI: 10.1007/s12035-015-9308-x] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/16/2015] [Accepted: 06/16/2015] [Indexed: 12/23/2022]
|
11
|
Petersen NH, Ortega-Gutierrez S, Reccius A, Masurkar A, Huang A, Marshall RS. Dynamic cerebral autoregulation is transiently impaired for one week after large-vessel acute ischemic stroke. Cerebrovasc Dis 2015; 39:144-50. [PMID: 25661277 DOI: 10.1159/000368595] [Citation(s) in RCA: 69] [Impact Index Per Article: 7.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/25/2014] [Accepted: 09/23/2014] [Indexed: 11/19/2022] Open
Abstract
BACKGROUND Dynamic cerebral autoregulation (DCA) is the continuous counterregulation of cerebral blood flow to fluctuations in blood pressure. DCA can become impaired after acute stroke, but it remains unclear to what extent and over what interval this occurs. METHODS We included 28 patients (NIHSS = 12 ± 6.5, age = 68.4 ± 17.1, 16F) with acute large-vessel ischemic stroke in the middle cerebral artery territory and 29 healthy controls (mean age 54.9 ± 9, 16F). DCA was assessed by simultaneous measurement of blood pressure together with blood flow velocities using finger plethysmography/arterial catheter and transcranial Doppler over three 10-minute recordings on days 0-2, 3-6 and ≥7 days after stroke. Transfer function analysis was applied to calculate average phase shift (PS) in the low frequency range (0.06-0.12 Hz). Less PS indicated poorer autoregulation. The affected side was compared with the unaffected side and controls. Univariate comparisons of data were performed using t tests at single time points, and generalized estimating equations with an exchangeable correlation matrix to examine the change in PS over time. RESULTS At mean 1.3 ± 0.5 days after stroke the average PS in the affected hemisphere was 29.6 ± 10.5 vs. 42.5 ± 13 degrees in the unaffected hemisphere (p = 0.004). At 4.1 ± 1 days, the PS in affected and unaffected hemisphere was 23.2 ± 19.1 vs. 41.7 ± 18.5 degrees, respectively (p = 0.003). At mean 9.75 ± 2.2 days stroke there was no difference between the affected and the unaffected hemisphere (53.2 ± 28.2 vs. 50.7 ± 29.2 degrees, p = 0.69). Control subjects had an average PS = 47.9 ± 16.8, significantly different from patients' affected hemisphere at the first two measurements (p = 0.001), but not the third (p = 0.37). The PS in controls remained unchanged on repeat testing after an average 19.1 days (48.4 ± 17.1, p = 0.61). Using the last recording as the reference, the average PS in the affected hemisphere was -23.54 (-44.1, -3) degrees lower on recording one (p = 0.025), and -31.6 (-56.1, -7.1) degrees lower on recording two (p < 0.011). Changes in the unaffected hemisphere over time were nonsignificant. DISCUSSION These data suggest that dynamic cerebral autoregulation is impaired in the affected hemisphere throughout the first week after large-vessel ischemic stroke, and then normalizes by week two. These findings may have important implications for acute blood pressure management after stroke.
Collapse
Affiliation(s)
- Nils H Petersen
- Department of Neurology, Columbia University, New York, N.Y., USA
| | | | | | | | | | | |
Collapse
|
12
|
Ševerdija EE, Gommer ED, Weerwind PW, Reulen JPH, Mess WH, Maessen JG. Assessment of dynamic cerebral autoregulation and cerebral carbon dioxide reactivity during normothermic cardiopulmonary bypass. Med Biol Eng Comput 2014; 53:195-203. [PMID: 25412609 DOI: 10.1007/s11517-014-1225-z] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/25/2013] [Accepted: 11/03/2014] [Indexed: 10/24/2022]
Abstract
Despite increased risk of neurological complications after cardiac surgery, monitoring of cerebral hemodynamics during cardiopulmonary bypass (CPB) is still not a common practice. Therefore, a technique to evaluate dynamic cerebral autoregulation and cerebral carbon dioxide reactivity (CO2R) during normothermic nonpulsatile CPB is presented. The technique uses continuous recording of invasive arterial blood pressure, middle cerebral artery blood flow velocity, absolute cerebral tissue oxygenation, in-line arterial carbon dioxide levels, and pump flow measurement in 37 adult male patients undergoing elective CPB. Cerebral autoregulation is estimated by transfer function analysis and the autoregulation index, based on the response to blood pressure variation induced by cyclic 6/min changes of indexed pump flow from 2.0 to 2.4 up to 2.8 L/min/m(2). CO2R was calculated from recordings of both cerebral blood flow velocity and cerebral tissue oxygenation. Cerebral autoregulation and CO2R were estimated at hypocapnia, normocapnia, and hypercapnia. CO2R was preserved during CPB, but significantly lower for hypocapnia compared with hypercapnia (p < 0.01). Conversely, cerebral autoregulation parameters such as gain, phase, and autoregulation index were significantly higher (p < 0.01) during hypocapnia compared with both normocapnia and hypercapnia. Assessing cerebral autoregulation and CO2R during CPB, by cyclic alteration of pump flow, showed an impaired cerebral autoregulation during hypercapnia.
Collapse
Affiliation(s)
- Ervin E Ševerdija
- Department of Cardiothoracic Surgery, Maastricht University Medical Centre, P. Debyelaan 25, PO box 5800, 6202 AZ, Maastricht, The Netherlands,
| | | | | | | | | | | |
Collapse
|
13
|
Salinet ASM, Robinson TG, Panerai RB. Effects of cerebral ischemia on human neurovascular coupling, CO2 reactivity, and dynamic cerebral autoregulation. J Appl Physiol (1985) 2014; 118:170-7. [PMID: 25593216 DOI: 10.1152/japplphysiol.00620.2014] [Citation(s) in RCA: 52] [Impact Index Per Article: 5.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/07/2023] Open
Abstract
Cerebral blood flow (CBF) regulation can be impaired in acute ischemic stroke but the combined effects of dynamic cerebral autoregulation (CA), CO2 cerebrovascular reactivity (CVR), and neurovascular coupling (NVC), obtained from simultaneous measurements, have not been described. CBF velocity in the middle cerebral artery (MCA) (CBFv, transcranial Doppler), blood pressure (BP, Finometer), and end-tidal Pco2 (PetCO2 , infrared capnography) were recorded during a 1-min passive movement of the arm in 27 healthy controls [mean age (SD) 61.4 (6.0) yr] and 27 acute stroke patients [age 63 (11.7) yr]. A multivariate autoregressive-moving average model was used to separate the contributions of BP, arterial Pco2 (PaCO2 ), and the neural activation to the CBFv responses. CBFv step responses for the BP, CO2, and stimulus inputs were also obtained. The contribution of the stimulus to the CBFv response was highly significant for the difference between the affected side [area under the curve (AUC) 104.5 (4.5)%] and controls [AUC 106.9 (4.3)%; P = 0.008]. CBFv step responses to CO2 [affected hemisphere 0.39 (0.7), unaffected 0.55 (0.8), controls 1.39 (0.9)%/mmHg; P = 0.01, affected vs. controls; P = 0.025, unaffected vs. controls] and motor stimulus inputs [affected hemisphere 0.20 (0.1), unaffected 0.22 (0.2), controls 0.37 (0.2) arbitrary units; P = 0.009, affected vs. controls; P = 0.02, unaffected vs. controls] were reduced in the stroke group compared with controls. The CBFv step responses to the BP input at baseline and during the paradigm were not different between groups (P = 0.07), but PetCO2 was lower in the stroke group (P < 0.05). These results provide new insights into the interaction of CA, CVR, and NVC in both health and disease states.
Collapse
Affiliation(s)
- Angela S M Salinet
- Department of Cardiovascular Sciences, University of Leicester, Leicester, United Kingdom; and
| | - Thompson G Robinson
- Department of Cardiovascular Sciences, University of Leicester, Leicester, United Kingdom; and National Institutes for Health Research (NIHR), Biomedical Research Unit in Cardiovascular Sciences, Glenfield Hospital, Leicester, United Kingdom
| | - Ronney B Panerai
- Department of Cardiovascular Sciences, University of Leicester, Leicester, United Kingdom; and National Institutes for Health Research (NIHR), Biomedical Research Unit in Cardiovascular Sciences, Glenfield Hospital, Leicester, United Kingdom
| |
Collapse
|
14
|
Baracchini C. Cerebral ambiguity. Brain Behav 2014; 4:599-601. [PMID: 25328837 PMCID: PMC4188354 DOI: 10.1002/brb3.277] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Download PDF] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/28/2022] Open
Affiliation(s)
- Claudio Baracchini
- Department of Neurological Sciences, University of Padua School of Medicine Via N. Giustiniani 5, Padova, 35128, Italy
| |
Collapse
|
15
|
Transfer function analysis for the assessment of cerebral autoregulation using spontaneous oscillations in blood pressure and cerebral blood flow. Med Eng Phys 2014; 36:563-75. [DOI: 10.1016/j.medengphy.2014.02.001] [Citation(s) in RCA: 46] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/01/2013] [Revised: 01/31/2014] [Accepted: 02/03/2014] [Indexed: 12/21/2022]
|
16
|
Lee CS, Chen CY. Reduction ofN-acetyl Aspartate in Bilateral Cerebral Tissue in Relation to Compromised Cerebrovascular Reserve Capacity as Investigated by Proton MR Spectroscopy and Acetazolamide Test. J CHIN CHEM SOC-TAIP 2013. [DOI: 10.1002/jccs.201000117] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
|
17
|
Horsfield MA, Jara JL, Saeed NP, Panerai RB, Robinson TG. Regional differences in dynamic cerebral autoregulation in the healthy brain assessed by magnetic resonance imaging. PLoS One 2013; 8:e62588. [PMID: 23638121 PMCID: PMC3640083 DOI: 10.1371/journal.pone.0062588] [Citation(s) in RCA: 28] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/29/2012] [Accepted: 03/22/2013] [Indexed: 11/19/2022] Open
Abstract
A novel method is described for mapping dynamic cerebral blood flow autoregulation to assess autoregulatory efficiency throughout the brain, using magnetic resonance imaging (MRI). Global abnormalities in autoregulation occur in clinical conditions, including stroke and head injury, and are of prognostic significance. However, there is limited information about regional variations. A gradient-echo echo-planar pulse sequence was used to scan the brains of healthy subjects at a rate of 1 scan/second during a transient decrease in arterial blood pressure provoked by a sudden release of pressure in bilateral inflated thigh cuffs. The signal decrease and subsequent recovery were analyzed to provide an index of autoregulatory efficiency (MRARI). MRI time-series were successfully acquired and analyzed in eleven subjects. Autoregulatory efficiency was not uniform throughout the brain: white matter exhibited faster recovery than gray (MRARI = 0.702 vs. 0.672, p = 0.009) and the cerebral cortex exhibited faster recovery than the cerebellum (MRARI = 0.669 vs. 0.645, p = 0.016). However, there was no evidence for differences between different cortical regions. Differences in autoregulatory efficiency between white matter, gray matter and the cerebellum may be a result of differences in vessel density and vasodilation. The techniques described may have practical importance in detecting regional changes in autoregulation consequent to disease.
Collapse
Affiliation(s)
- Mark A. Horsfield
- Department of Cardiovascular Sciences, University of Leicester, Leicester, United Kingdom
| | - José L. Jara
- Departamento de Ingeniería Informática, Universidad de Santiago de Chile, Santiago, Chile
| | - Nazia P. Saeed
- Department of Cardiovascular Sciences, University of Leicester, Leicester, United Kingdom
| | - Ronney B. Panerai
- Department of Cardiovascular Sciences, University of Leicester, Leicester, United Kingdom
- NIHR Biomedical Research Unit for Cardiovascular Sciences, The Glenfield Hospital, Leicester, United Kingdom
| | - Thompson G. Robinson
- Department of Cardiovascular Sciences, University of Leicester, Leicester, United Kingdom
- NIHR Biomedical Research Unit for Cardiovascular Sciences, The Glenfield Hospital, Leicester, United Kingdom
- * E-mail:
| |
Collapse
|
18
|
Tzeng YC, Ainslie PN, Cooke WH, Peebles KC, Willie CK, MacRae BA, Smirl JD, Horsman HM, Rickards CA. Assessment of cerebral autoregulation: the quandary of quantification. Am J Physiol Heart Circ Physiol 2012; 303:H658-71. [DOI: 10.1152/ajpheart.00328.2012] [Citation(s) in RCA: 126] [Impact Index Per Article: 10.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
We assessed the convergent validity of commonly applied metrics of cerebral autoregulation (CA) to determine the extent to which the metrics can be used interchangeably. To examine between-subject relationships among low-frequency (LF; 0.07–0.2 Hz) and very-low-frequency (VLF; 0.02–0.07 Hz) transfer function coherence, phase, gain, and normalized gain, we performed retrospective transfer function analysis on spontaneous blood pressure and middle cerebral artery blood velocity recordings from 105 individuals. We characterized the relationships ( n = 29) among spontaneous transfer function metrics and the rate of regulation index and autoregulatory index derived from bilateral thigh-cuff deflation tests. In addition, we analyzed data from subjects ( n = 29) who underwent a repeated squat-to-stand protocol to determine the relationships between transfer function metrics during forced blood pressure fluctuations. Finally, data from subjects ( n = 16) who underwent step changes in end-tidal Pco2 (PetCO2) were analyzed to determine whether transfer function metrics could reliably track the modulation of CA within individuals. CA metrics were generally unrelated or showed only weak to moderate correlations. Changes in PetCO2 were positively related to coherence [LF: β = 0.0065 arbitrary units (AU)/mmHg and VLF: β = 0.011 AU/mmHg, both P < 0.01] and inversely related to phase (LF: β = −0.026 rad/mmHg and VLF: β = −0.018 rad/mmHg, both P < 0.01) and normalized gain (LF: β = −0.042%/mmHg2 and VLF: β = −0.013%/mmHg2, both P < 0.01). However, PetCO2 was positively associated with gain (LF: β = 0.0070 cm·s−1·mmHg−2, P < 0.05; and VLF: β = 0.014 cm·s−1·mmHg−2, P < 0.01). Thus, during changes in PetCO2, LF phase was inversely related to LF gain (β = −0.29 cm·s−1·mmHg−1·rad−1, P < 0.01) but positively related to LF normalized gain (β = 1.3% mmHg−1/rad, P < 0.01). These findings collectively suggest that only select CA metrics can be used interchangeably and that interpretation of these measures should be done cautiously.
Collapse
Affiliation(s)
- Y. C. Tzeng
- Cardiovascular Systems Laboratory, University of Otago, Wellington South, New Zealand
| | - P. N. Ainslie
- School of Health and Exercise Sciences, University of British Columbia (Okanagan Campus), Kelowna, British Columbia, Canada; and
| | - W. H. Cooke
- Department of Health and Kinesiology, The University of Texas, San Antonio, Texas
| | - K. C. Peebles
- Cardiovascular Systems Laboratory, University of Otago, Wellington South, New Zealand
| | - C. K. Willie
- School of Health and Exercise Sciences, University of British Columbia (Okanagan Campus), Kelowna, British Columbia, Canada; and
| | - B. A. MacRae
- Cardiovascular Systems Laboratory, University of Otago, Wellington South, New Zealand
| | - J. D. Smirl
- School of Health and Exercise Sciences, University of British Columbia (Okanagan Campus), Kelowna, British Columbia, Canada; and
| | - H. M. Horsman
- Cardiovascular Systems Laboratory, University of Otago, Wellington South, New Zealand
| | - C. A. Rickards
- Department of Health and Kinesiology, The University of Texas, San Antonio, Texas
| |
Collapse
|
19
|
Archer T, Svensson K, Alricsson M. Physical exercise ameliorates deficits induced by traumatic brain injury. Acta Neurol Scand 2012; 125:293-302. [PMID: 22233115 DOI: 10.1111/j.1600-0404.2011.01638.x] [Citation(s) in RCA: 44] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 12/16/2011] [Indexed: 12/11/2022]
Abstract
The extent and depth of traumatic brain injury (TBI) remains a major determining factor together with the type of structural insult and its location, whether mild, moderate or severe, as well as the distribution and magnitude of inflammation and loss of cerebrovascular integrity, and the eventual efficacy of intervention. The influence of exercise intervention in TBI is multiple, ranging from anti-apoptotic effects to the augmentation of neuroplasticity. Physical exercise diminishes cerebral inflammation by elevating factors and agents involved in immunomodulatory function, and buttresses glial cell, cerebrovascular, and blood-brain barrier intactness. It provides unique non-pharmacologic intervention that incorporate different physical activity regimes, whether dynamic or static, endurance or resistance. Physical training regimes ought necessarily to be adapted to the specific demands of diagnosis, type and degree of injury and prognosis for individuals who have suffered TBI.
Collapse
Affiliation(s)
| | - K. Svensson
- School of Education; Psychology and Sport Science; Linnaeus University; Kalmar; Sweden
| | | |
Collapse
|
20
|
LEN TREVORK, NEARY JPATRICK, ASMUNDSON GORDONJG, GOODMAN DAVIDG, BJORNSON BRUCE, BHAMBHANI YAGESHN. Cerebrovascular Reactivity Impairment after Sport-Induced Concussion. Med Sci Sports Exerc 2011; 43:2241-8. [DOI: 10.1249/mss.0b013e3182249539] [Citation(s) in RCA: 97] [Impact Index Per Article: 7.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
|
21
|
Deegan BM, Sorond FA, Galica A, Lipsitz LA, O'Laighin G, Serrador JM. Elderly women regulate brain blood flow better than men do. Stroke 2011; 42:1988-93. [PMID: 21566238 DOI: 10.1161/strokeaha.110.605618] [Citation(s) in RCA: 63] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Abstract
BACKGROUND AND PURPOSE Orthostatic intolerance and falls differ between sexes and change with age. However, it remains unclear what role cerebral autoregulation may play in this response. This study was designed to determine whether cerebral autoregulation, assessed using transcranial Doppler ultrasound, is more effective in elderly females than in males. METHODS We used transcranial Doppler ultrasound to evaluate cerebral autoregulation in 544 (236 male) subjects older than age 70 years recruited as part of the MOBILIZE Boston study. The MOBILIZE Boston study is a prospective cohort study of a unique set of risk factors for falls in seniors in the Boston area. We assessed CO2 reactivity and transfer function gain, phase, and coherence during 5 minutes of quiet sitting and autoregulatory index during sit-to-stand tests. RESULTS Male subjects had significantly lower CO2 reactivity (males, 1.10 ± 0.03; females, 1.32 ± 0.43 (cm/s)/%CO2; P<0.001) and autoregulatory indices (males, 4.41 ± 2.44; female, 5.32 ± 2.47; P<0.001), higher transfer function gain (males, 1.34 ± 0.49; females, 1.19 ± 0.43; P=0.002), and lower phase (males, 42.7 ± 23.6; females, 49.4 ± 24.9; P=0.002) in the autoregulatory band, implying less effective cerebral autoregulation. However, reduced autoregulation in males was not below the normal range, indicating autoregulation was intact but less effective. CONCLUSIONS Female subjects were better able to maintain cerebral flow velocities during postural changes and demonstrated better cerebral autoregulation. The mechanisms of sex-based differences in autoregulation remain unclear but may partially explain the higher rates of orthostatic hypotension-related hospitalizations in elderly men.
Collapse
Affiliation(s)
- Brian M Deegan
- Electrical & Electronic Engineering, School of Engineering & Informatics, NUI Galway, University Road, Galway, Ireland
| | | | | | | | | | | |
Collapse
|
22
|
Len TK, Neary JP. Cerebrovascular pathophysiology following mild traumatic brain injury. Clin Physiol Funct Imaging 2010; 31:85-93. [PMID: 21078064 DOI: 10.1111/j.1475-097x.2010.00990.x] [Citation(s) in RCA: 74] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/01/2022]
Abstract
Mild traumatic brain injury (mTBI) or sport-induced concussion has recently become a prominent concern not only in the athletic setting (i.e. sports venue) but also in the general population. The majority of research to date has aimed at understanding the neurological and neuropsychological outcomes of injury as well as return-to-play guidelines. Remaining relatively unexamined has been the pathophysiological aspect of mTBI. Recent technological advances including transcranial Doppler ultrasound and near infrared spectroscopy have allowed researchers to examine the systemic effects of mTBI from rest to exercise, and during both asymptomatic and symptomatic conditions. In this review, we focus on the current research available from both human and experimental (animal) studies surrounding the pathophysiology of mTBI. First, the quest for a unified definition of mTBI, its historical development and implications for future research is discussed. Finally, the impact of mTBI on the control and regulation of cerebral blood flow, cerebrovascular reactivity, cerebral oxygenation and neuroautonomic cardiovascular regulation, all of which may be compromised with mTBI, is discussed.
Collapse
Affiliation(s)
- T K Len
- Exercise Physiology Laboratory, Faculty of Kinesiology and Health Studies, University of Regina, Regina, SK, Canada
| | | |
Collapse
|
23
|
Aries MJH, Elting JW, De Keyser J, Kremer BPH, Vroomen PCAJ. Cerebral autoregulation in stroke: a review of transcranial Doppler studies. Stroke 2010; 41:2697-704. [PMID: 20930158 DOI: 10.1161/strokeaha.110.594168] [Citation(s) in RCA: 229] [Impact Index Per Article: 16.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/27/2022]
Abstract
BACKGROUND AND PURPOSE Cerebral autoregulation may become impaired after stroke. To provide a review of the nature and extent of any autoregulation impairment after stroke and its course over time, a technique allowing repeated bedside measurements with good temporal resolution is required. Transcranial Doppler (TCD) in combination with continuous blood pressure measurements allows noninvasive continuous bedside investigation with high temporal resolution of the dynamic and the steady-state components of cerebral autoregulation. Therefore, this review focuses on all TCD studies on cerebral autoregulation in the setting of documented ischemic stroke. METHODS PubMed and EMBASE were searched for studies of stroke, autoregulation, and TCD. Studies were either acute phase (<96 hours after index stroke) or chronic phase (>96 hours after index stroke) autoregulation studies. Quality of studies was studied in a standardized fashion. RESULTS Twenty-three studies met the inclusion criteria. General agreement existed on cerebral autoregulation being impaired, even after minor stroke. Bilateral impairment of autoregulation was documented, particularly after lacunar stroke. Studies showed progressive deterioration of cerebral autoregulation in the first 5 days after stroke and recovery over the next 3 months. Impaired cerebral autoregulation as assessed by TCD was related to neurological deterioration, the necessity for decompressive surgery, and poor outcome. Synthesis of the data of various studies was, however, limited by studies not meeting key methodological criteria for observational studies. CONCLUSIONS TCD in combination with continuous blood pressure measurement offers a method with a high temporal resolution feasible for bedside evaluation of cerebral autoregulation in the stroke unit. TCD studies have shown impairment of cerebral autoregulation in various subtypes of ischemic stroke. To improve the synthesis of data from various research groups, there is urgent need for standardization of methodology of TCD studies in cerebral autoregulation.
Collapse
Affiliation(s)
- Marcel J H Aries
- University Medical Centre Groningen, Department of Neurology, Hanzeplein 1 9700 RB, Groningen, The Netherlands.
| | | | | | | | | |
Collapse
|
24
|
Stevenson SF, Doubal FN, Shuler K, Wardlaw JM. A systematic review of dynamic cerebral and peripheral endothelial function in lacunar stroke versus controls. Stroke 2010; 41:e434-42. [PMID: 20395619 DOI: 10.1161/strokeaha.109.569855] [Citation(s) in RCA: 89] [Impact Index Per Article: 6.4] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/20/2023]
Abstract
BACKGROUND AND PURPOSE The etiology of cerebral small vessel disease is unknown. An association with endothelial dysfunction has been suggested. We systematically assessed all relevant studies of dynamic endothelial function in patients with lacunar stroke as a marker of small vessel disease. METHODS We searched for studies of cerebral or peripheral vascular reactivity in patients with lacunar or cortical (ie, large artery atheromatous) ischemic stroke or nonstroke control subjects. We calculated standardized mean difference (SMD) in vascular reactivity+/-95% CIs between small vessel disease and control groups. RESULTS Sixteen publications (974 patients) were included. In lacunar stroke, cerebrovascular reactivity (n=534) was reduced compared with age-matched normal (SMD -0.94, 95% CI -1.17 to -0.70), but not age+risk factor-matched control subjects (SMD 0.08, 95% CI -0.36 to 0.53) or cortical strokes (SMD -0.29, 95% CI -0.69 to 0.11); forearm flow-mediated dilatation (n=401) was reduced compared with age-matched normal control subjects (SMD -1.04, 95% CI -1.33 to -0.75) and age+risk factor-matched control subjects (SMD -0.94, 95% CI -1.26 to -0.61), but not cortical strokes (SMD -0.23, 95% CI -0.55 to 0.08). CONCLUSIONS Endothelial dysfunction is present in patients with lacunar stroke but may simply reflect exposure to vascular risk factors and having a stroke, because a similar degree of dysfunction is found in cortical (large artery atheromatous) stroke. Current data do not confirm that endothelial dysfunction is specific to small vessel stroke. Future studies should include control subjects with nonlacunar stroke.
Collapse
Affiliation(s)
- Susan F Stevenson
- SINAPSE Collaboration, SFC Brain Imaging Research Centre, Division of Clinical Neurosciences, Western General Hospital, Crewe Road, Edinburgh, EH4 2XU, UK
| | | | | | | |
Collapse
|
25
|
Yonai Y, Boms N, Molnar S, Rosengarten B, Bornstein NM, Csiba L, Olah L. Acetazolamide-induced vasodilation does not inhibit the visually evoked flow response. J Cereb Blood Flow Metab 2010; 30:516-21. [PMID: 19809468 PMCID: PMC2949151 DOI: 10.1038/jcbfm.2009.212] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
Abstract
Different methods are used to assess the vasodilator ability of cerebral blood vessels; however, the exact mechanism of cerebral vasodilation, induced by different stimuli, is not entirely known. Our aim was to investigate whether the potent vasodilator agent, acetazolamide (AZ), inhibits the neurovascular coupling, which also requires vasodilation. Therefore, visually evoked flow parameters were examined by transcranial Doppler in ten healthy subjects before and after AZ administration. Pulsatility index and peak systolic flow velocity changes, evoked by visual stimulus, were recorded in the posterior cerebral arteries before and after intravenous administration of 15 mg/kg AZ. Repeated-measures ANOVA did not show significant group main effect between the visually evoked relative flow velocity time courses before and after AZ provocation (P=0.43). Visual stimulation induced significant increase of relative flow velocity and decrease of pulsatility index not only before but also at the maximal effect of AZ. These results suggest that maximal cerebral vasodilation cannot be determined by the clinically accepted dose of AZ (15 mg/kg) and prove that neurovascular coupling remains preserved despite AZ-induced vasodilation. Our observation indicates independent regulation of vasodilation during neurovascular coupling, allowing the adaptation of cerebral blood flow according to neuronal activity even if other processes require significant vasodilation.
Collapse
Affiliation(s)
- Yaniv Yonai
- Department of Neurology, University of Debrecen, Debrecen H-4032, Hungary
| | | | | | | | | | | | | |
Collapse
|
26
|
Carrera E, Lee LK, Giannopoulos S, Marshall RS. Cerebrovascular reactivity and cerebral autoregulation in normal subjects. J Neurol Sci 2009; 285:191-4. [DOI: 10.1016/j.jns.2009.06.041] [Citation(s) in RCA: 31] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/15/2009] [Revised: 06/22/2009] [Accepted: 06/23/2009] [Indexed: 11/26/2022]
|