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Chen DY, Di X, Karunakaran KD, Sun H, Pal S, Biswal BB. Delayed cerebrovascular reactivity in individuals with spinal cord injury in the right inferior parietal lobe: a breath-hold functional near-infrared spectroscopy study. MEDRXIV : THE PREPRINT SERVER FOR HEALTH SCIENCES 2024:2024.06.03.24307819. [PMID: 38883754 PMCID: PMC11177928 DOI: 10.1101/2024.06.03.24307819] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/18/2024]
Abstract
Cerebrovascular reactivity (CVR) reflects the ability of blood vessels to dilate or constrict in response to a vasoactive stimulus, and allows researchers to assess the brain's vascular health. Individuals with spinal cord injury (SCI) are at an increased risk for autonomic dysfunction in addition to cognitive impairments, which have been linked to a decline in CVR; however, there is currently a lack of brain-imaging studies that investigate how CVR is altered after SCI. In this study, we used a breath-holding hypercapnic stimulus and functional near-infrared spectroscopy (fNIRS) to investigate CVR alterations in individuals with SCI (n = 20, 14M, 6F, mean age = 46.3 ± 10.2 years) as compared to age- and sex-matched able-bodied (AB) controls (n = 25, 19M, 6F, mean age = 43.2 ± 12.28 years). CVR was evaluated by its amplitude and delay components separately by using principal component analysis and cross-correlation analysis, respectively. We observed significantly delayed CVR in the right inferior parietal lobe in individuals with SCI compared to AB controls (linear mixed-effects model, fixed-effects estimate = 6.565, Satterthwaite's t-test, t = 2.663, p = 0.008), while the amplitude of CVR was not significantly different. The average CVR delay in the SCI group in the right inferior parietal lobe was 14.21 s (sd: 6.60 s), and for the AB group, the average delay in the right inferior parietal lobe was 7.08 s (sd: 7.39 s). CVR delays were also associated with the duration since injury in individuals with SCI, in which a longer duration since injury was associated with a shortened delay in CVR in the right inferior parietal region (Pearson's r-correlation, r = -0.59, p = 0.04). This study shows that fNIRS can be used to quantify changes in CVR in individuals with SCI, and may be further used in rehabilitative settings to monitor the cerebrovascular health of individuals with SCI.
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Affiliation(s)
- Donna Y. Chen
- Department of Biomedical Engineering, New Jersey Institute of Technology, Newark, NJ, US
- Rutgers Biomedical and Health Sciences, Rutgers School of Graduate Studies, Newark, NJ, US
| | - Xin Di
- Department of Biomedical Engineering, New Jersey Institute of Technology, Newark, NJ, US
| | | | - Hai Sun
- Department of Neurosurgery, Rutgers Robert Wood Johnson Medical School, New Brunswick, NJ, US
| | - Saikat Pal
- Department of Biomedical Engineering, New Jersey Institute of Technology, Newark, NJ, US
- Electrical and Computer Engineering Department, New Jersey Institute of Technology, Newark, NJ, US
- Spinal Cord Damage Research Center, James J. Peters Veterans Affairs Medical Center, Bronx, NY, US
| | - Bharat B. Biswal
- Department of Biomedical Engineering, New Jersey Institute of Technology, Newark, NJ, US
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Weber AM, Nightingale TE, Jarrett M, Lee AHX, Campbell OL, Walter M, Lucas SJE, Phillips A, Rauscher A, Krassioukov AV. Cerebrovascular Reactivity Following Spinal Cord Injury. Top Spinal Cord Inj Rehabil 2024; 30:78-95. [PMID: 38799609 PMCID: PMC11123610 DOI: 10.46292/sci23-00068] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 05/29/2024]
Abstract
Background Spinal cord injuries (SCI) often result in cardiovascular issues, increasing the risk of stroke and cognitive deficits. Objectives This study assessed cerebrovascular reactivity (CVR) using functional magnetic resonance imaging (fMRI) during a hypercapnic challenge in SCI participants compared to noninjured controls. Methods Fourteen participants were analyzed (n = 8 with SCI [unless otherwise noted], median age = 44 years; n = 6 controls, median age = 33 years). CVR was calculated through fMRI signal changes. Results The results showed a longer CVR component (tau) in the grey matter of SCI participants (n = 7) compared to controls (median difference = 3.0 s; p < .05). Time since injury (TSI) correlated negatively with steady-state CVR in the grey matter and brainstem of SCI participants (RS = -0.81, p = .014; RS = -0.84, p = .009, respectively). Lower steady-state CVR in the brainstem of the SCI group (n = 7) correlated with lower diastolic blood pressure (RS = 0.76, p = .046). Higher frequency of hypotensive episodes (n = 7) was linked to lower CVR outcomes in the grey matter (RS = -0.86, p = .014) and brainstem (RS = -0.89, p = .007). Conclusion Preliminary findings suggest a difference in the dynamic CVR component, tau, between the SCI and noninjured control groups, potentially explaining the higher cerebrovascular health burden in SCI individuals. Exploratory associations indicate that longer TSI, lower diastolic blood pressure, and more hypotensive episodes may lead to poorer CVR outcomes. However, further research is necessary to establish causality and support these observations.
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Affiliation(s)
- Alexander Mark Weber
- Division of Neurology, Department of Pediatrics, University of British Columbia, Vancouver, BC, Canada
- BC Children's Hospital Research Institute, Vancouver, BC, Canada
- School of Biomedical Engineering, University of British Columbia, British Columbia, Canada
- Department of Neuroscience, University of British Columbia, Vancouver, BC, Canada
| | - Tom E. Nightingale
- School of Sport, Exercise and Rehabilitation Sciences, University of Birmingham, Birmingham, UK
- Centre for Trauma Sciences Research, University of Birmingham, Edgbaston, Birmingham, UK
- International Collaboration on Repair Discoveries (ICORD), University of British Columbia, Vancouver, Canada
| | - Michael Jarrett
- MRI Research Centre, University of British Columbia, Vancouver, Canada
| | - Amanda H. X. Lee
- International Collaboration on Repair Discoveries (ICORD), University of British Columbia, Vancouver, Canada
| | - Olivia Lauren Campbell
- BC Children's Hospital Research Institute, Vancouver, BC, Canada
- School of Biomedical Engineering, University of British Columbia, British Columbia, Canada
| | - Matthias Walter
- International Collaboration on Repair Discoveries (ICORD), University of British Columbia, Vancouver, Canada
- Department of Urology, University Hospital Basel, University of Basel, Basel, Switzerland
| | - Samuel J. E. Lucas
- School of Sport, Exercise and Rehabilitation Sciences, University of Birmingham, Birmingham, UK
- Centre for Human Brain Health, University of Birmingham, UK
| | - Aaron Phillips
- International Collaboration on Repair Discoveries (ICORD), University of British Columbia, Vancouver, Canada
- Department of Physiology and Pharmacology, Cumming School of Medicine, University of Calgary, Calgary, Alberta, Canada
- Department of Clinical Neurosciences, Hotchkiss Brain Institute, Cumming School of Medicine, University of Calgary, Calgary, Alberta, Canada
- Department of Cardiac Sciences, Libin Cardiovascular Institute, Cumming School of Medicine, University of Calgary, Calgary, Alberta, Canada
- RestoreNetwork, Hotchkiss Brain Institute, Libin Cardiovascular Institute, McCaig Institute for Bone and Joint Health, Cumming School of Medicine, University of Calgary, Calgary, Alberta, Canada
| | - Alexander Rauscher
- Division of Neurology, Department of Pediatrics, University of British Columbia, Vancouver, BC, Canada
- BC Children's Hospital Research Institute, Vancouver, BC, Canada
- MRI Research Centre, University of British Columbia, Vancouver, Canada
- Department of Astronomy and Physics, University of British Columbia, Vancouver, BC, Canada
| | - Andrei V. Krassioukov
- International Collaboration on Repair Discoveries (ICORD), University of British Columbia, Vancouver, Canada
- G.F. Strong Rehabilitation Centre, Vancouver, BC, Canada
- Division of Physical Medicine and Rehabilitation, Faculty of Medicine, University of British Columbia, Vancouver, BC, Canada
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3
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Routkevitch D, Soulé Z, Kats N, Baca E, Hersh AM, Kempski-Leadingham KM, Menta AK, Bhimreddy M, Jiang K, Davidar AD, Smit C, Theodore N, Thakor NV, Manbachi A. Non-contrast ultrasound image analysis for spatial and temporal distribution of blood flow after spinal cord injury. Sci Rep 2024; 14:714. [PMID: 38184676 PMCID: PMC10771432 DOI: 10.1038/s41598-024-51281-7] [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: 09/17/2023] [Accepted: 01/03/2024] [Indexed: 01/08/2024] Open
Abstract
Ultrasound technology can provide high-resolution imaging of blood flow following spinal cord injury (SCI). Blood flow imaging may improve critical care management of SCI, yet its duration is limited clinically by the amount of contrast agent injection required for high-resolution, continuous monitoring. In this study, we aim to establish non-contrast ultrasound as a clinically translatable imaging technique for spinal cord blood flow via comparison to contrast-based methods and by measuring the spatial distribution of blood flow after SCI. A rodent model of contusion SCI at the T12 spinal level was carried out using three different impact forces. We compared images of spinal cord blood flow taken using both non-contrast and contrast-enhanced ultrasound. Subsequently, we processed the images as a function of distance from injury, yielding the distribution of blood flow through space after SCI, and found the following. (1) Both non-contrast and contrast-enhanced imaging methods resulted in similar blood flow distributions (Spearman's ρ = 0.55, p < 0.0001). (2) We found an area of decreased flow at the injury epicenter, or umbra (p < 0.0001). Unexpectedly, we found increased flow at the periphery, or penumbra (rostral, p < 0.05; caudal, p < 0.01), following SCI. However, distal flow remained unchanged, in what is presumably unaffected tissue. (3) Finally, tracking blood flow in the injury zones over time revealed interesting dynamic changes. After an initial decrease, blood flow in the penumbra increased during the first 10 min after injury, while blood flow in the umbra and distal tissue remained constant over time. These results demonstrate the viability of non-contrast ultrasound as a clinical monitoring tool. Furthermore, our surprising observations of increased flow in the injury periphery pose interesting new questions about how the spinal cord vasculature reacts to SCI, with potentially increased significance of the penumbra.
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Affiliation(s)
- Denis Routkevitch
- Department of Biomedical Engineering, Johns Hopkins University, Baltimore, MD, USA
- Department of Neurosurgery, School of Medicine, Johns Hopkins University, Baltimore, MD, USA
- HEPIUS Innovation Laboratory, School of Medicine, Johns Hopkins University, Baltimore, MD, USA
| | - Zoe Soulé
- Department of Biomedical Engineering, Johns Hopkins University, Baltimore, MD, USA
| | - Nicholas Kats
- Department of Biomedical Engineering, Johns Hopkins University, Baltimore, MD, USA
| | - Emily Baca
- Department of Biomedical Engineering, Johns Hopkins University, Baltimore, MD, USA
| | - Andrew M Hersh
- Department of Neurosurgery, School of Medicine, Johns Hopkins University, Baltimore, MD, USA
- HEPIUS Innovation Laboratory, School of Medicine, Johns Hopkins University, Baltimore, MD, USA
| | - Kelley M Kempski-Leadingham
- Department of Neurosurgery, School of Medicine, Johns Hopkins University, Baltimore, MD, USA
- HEPIUS Innovation Laboratory, School of Medicine, Johns Hopkins University, Baltimore, MD, USA
| | - Arjun K Menta
- Department of Neurosurgery, School of Medicine, Johns Hopkins University, Baltimore, MD, USA
- HEPIUS Innovation Laboratory, School of Medicine, Johns Hopkins University, Baltimore, MD, USA
| | - Meghana Bhimreddy
- Department of Neurosurgery, School of Medicine, Johns Hopkins University, Baltimore, MD, USA
- HEPIUS Innovation Laboratory, School of Medicine, Johns Hopkins University, Baltimore, MD, USA
| | - Kelly Jiang
- Department of Neurosurgery, School of Medicine, Johns Hopkins University, Baltimore, MD, USA
- HEPIUS Innovation Laboratory, School of Medicine, Johns Hopkins University, Baltimore, MD, USA
| | - A Daniel Davidar
- Department of Neurosurgery, School of Medicine, Johns Hopkins University, Baltimore, MD, USA
- HEPIUS Innovation Laboratory, School of Medicine, Johns Hopkins University, Baltimore, MD, USA
| | - Constantin Smit
- HEPIUS Innovation Laboratory, School of Medicine, Johns Hopkins University, Baltimore, MD, USA
| | - Nicholas Theodore
- Department of Neurosurgery, School of Medicine, Johns Hopkins University, Baltimore, MD, USA
- HEPIUS Innovation Laboratory, School of Medicine, Johns Hopkins University, Baltimore, MD, USA
| | - Nitish V Thakor
- Department of Biomedical Engineering, Johns Hopkins University, Baltimore, MD, USA
- HEPIUS Innovation Laboratory, School of Medicine, Johns Hopkins University, Baltimore, MD, USA
- Department of Electrical and Computer Engineering, Johns Hopkins University, Baltimore, MD, USA
| | - Amir Manbachi
- Department of Biomedical Engineering, Johns Hopkins University, Baltimore, MD, USA.
- Department of Neurosurgery, School of Medicine, Johns Hopkins University, Baltimore, MD, USA.
- HEPIUS Innovation Laboratory, School of Medicine, Johns Hopkins University, Baltimore, MD, USA.
- Department of Electrical and Computer Engineering, Johns Hopkins University, Baltimore, MD, USA.
- Department of Mechanical Engineering, Johns Hopkins University, Baltimore, MD, USA.
- Department of Anesthesiology and Critical Care Medicine, School of Medicine, Johns Hopkins University, Baltimore, MD, USA.
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Brassard P, Roy MA, Burma JS, Labrecque L, Smirl JD. Quantification of dynamic cerebral autoregulation: welcome to the jungle! Clin Auton Res 2023; 33:791-810. [PMID: 37758907 DOI: 10.1007/s10286-023-00986-2] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/01/2023] [Accepted: 09/11/2023] [Indexed: 09/29/2023]
Abstract
PURPOSE Patients with dysautonomia often experience symptoms such as dizziness, syncope, blurred vision and brain fog. Dynamic cerebral autoregulation, or the ability of the cerebrovasculature to react to transient changes in arterial blood pressure, could be associated with these symptoms. METHODS In this narrative review, we go beyond the classical view of cerebral autoregulation to discuss dynamic cerebral autoregulation, focusing on recent advances pitfalls and future directions. RESULTS Following some historical background, this narrative review provides a brief overview of the concept of cerebral autoregulation, with a focus on the quantification of dynamic cerebral autoregulation. We then discuss the main protocols and analytical approaches to assess dynamic cerebral autoregulation, including recent advances and important issues which need to be tackled. CONCLUSION The researcher or clinician new to this field needs an adequate comprehension of the toolbox they have to adequately assess, and interpret, the complex relationship between arterial blood pressure and cerebral blood flow in healthy individuals and clinical populations, including patients with autonomic disorders.
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Affiliation(s)
- Patrice Brassard
- Department of Kinesiology, Faculty of Medicine, Université Laval, Québec, Canada.
- Research center of the Institut Universitaire de Cardiologie et de Pneumologie de Québec, Québec, Canada.
| | - Marc-Antoine Roy
- Department of Kinesiology, Faculty of Medicine, Université Laval, Québec, Canada
- Research center of the Institut Universitaire de Cardiologie et de Pneumologie de Québec, Québec, Canada
| | - Joel S Burma
- Cerebrovascular Concussion Laboratory, Faculty of Kinesiology, University of Calgary, Calgary, AB, Canada
- Sport Injury Prevention Research Centre, Faculty of Kinesiology, University of Calgary, Calgary, AB, Canada
- Integrated Concussion Research Program, University of Calgary, Calgary, AB, Canada
- Alberta Children's Hospital Research Institute, University of Calgary, Calgary, AB, Canada
- Libin Cardiovascular Institute of Alberta, University of Calgary, Calgary, AB, Canada
- Hotchkiss Brain Institute, University of Calgary, Calgary, AB, Canada
- Human Performance Laboratory, Faculty of Kinesiology, University of Calgary, Calgary, AB, Canada
| | - Lawrence Labrecque
- Department of Kinesiology, Faculty of Medicine, Université Laval, Québec, Canada
- Research center of the Institut Universitaire de Cardiologie et de Pneumologie de Québec, Québec, Canada
| | - Jonathan D Smirl
- Cerebrovascular Concussion Laboratory, Faculty of Kinesiology, University of Calgary, Calgary, AB, Canada
- Sport Injury Prevention Research Centre, Faculty of Kinesiology, University of Calgary, Calgary, AB, Canada
- Integrated Concussion Research Program, University of Calgary, Calgary, AB, Canada
- Alberta Children's Hospital Research Institute, University of Calgary, Calgary, AB, Canada
- Libin Cardiovascular Institute of Alberta, University of Calgary, Calgary, AB, Canada
- Hotchkiss Brain Institute, University of Calgary, Calgary, AB, Canada
- Human Performance Laboratory, Faculty of Kinesiology, University of Calgary, Calgary, AB, Canada
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5
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Cerebral Autoregulation during Postural Change in Patients with Cervical Spinal Cord Injury-A Carotid Duplex Ultrasonography Study. Diagnostics (Basel) 2021; 11:diagnostics11081321. [PMID: 34441256 PMCID: PMC8393722 DOI: 10.3390/diagnostics11081321] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/19/2021] [Revised: 07/13/2021] [Accepted: 07/21/2021] [Indexed: 11/17/2022] Open
Abstract
Patients with a spinal cord injury (SCI) frequently experience sudden falls in blood pressure during postural change. Few studies have investigated whether the measurement of blood flow velocity within vessels can reflect brain perfusion during postural change. By performing carotid duplex ultrasonography (CDU), we investigated changes in cerebral blood flow (CBF) during postural changes in patients with a cervical SCI, determined the correlation of CBF change with presyncopal symptoms, and investigated factors affecting cerebral autoregulation. We reviewed the medical records of 100 patients with a cervical SCI who underwent CDU. The differences between the systolic blood pressure, diastolic blood pressure, and CBF volume in the supine posture and after 5 min at 50° tilt were evaluated. Presyncopal symptoms occurred when the blood flow volume of the internal carotid artery decreased by ≥21% after tilt. In the group that had orthostatic hypotension and severe CBF decrease during tilt, the body mass index and physical and functional scores were lower than in other groups, and the proportion of patients with a severe SCI was high. The higher the SCI severity and the lower the functional score, the higher the possibility of cerebral autoregulation failure. CBF should be assessed by conducting CDU in patients with a high-level SCI.
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6
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Shoemaker LN, Wilson LC, Lucas SJE, Machado L, Walker RJ, Cotter JD. Indomethacin markedly blunts cerebral perfusion and reactivity, with little cognitive consequence in healthy young and older adults. J Physiol 2020; 599:1097-1113. [DOI: 10.1113/jp280118] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/07/2020] [Accepted: 11/05/2020] [Indexed: 12/11/2022] Open
Affiliation(s)
- L. N. Shoemaker
- School of Physical Education, Sport and Exercise Sciences University of Otago Dunedin New Zealand
| | - L. C. Wilson
- Department of Medicine Otago Medical School ‐ Dunedin Campus University of Otago Dunedin New Zealand
| | - S. J. E. Lucas
- Department of Physiology University of Otago Dunedin New Zealand
- School of Sport, Exercise and Rehabilitation Sciences College of Life and Environmental Sciences University of Birmingham Birmingham UK
- Centre for Human Brain Health University of Birmingham Birmingham UK
| | - L. Machado
- Department of Psychology University of Otago Dunedin New Zealand
| | - R. J. Walker
- Department of Medicine Otago Medical School ‐ Dunedin Campus University of Otago Dunedin New Zealand
| | - J. D. Cotter
- School of Physical Education, Sport and Exercise Sciences University of Otago Dunedin New Zealand
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7
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Saleem S, Vucina D, Sarafis Z, Lee AHX, Squair JW, Barak OF, Coombs GB, Mijacika T, Krassioukov AV, Ainslie PN, Dujic Z, Tzeng YC, Phillips AA. Wavelet decomposition analysis is a clinically relevant strategy to evaluate cerebrovascular buffering of blood pressure after spinal cord injury. Am J Physiol Heart Circ Physiol 2018; 314:H1108-H1114. [PMID: 29600896 DOI: 10.1152/ajpheart.00152.2017] [Citation(s) in RCA: 21] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/03/2023]
Abstract
The capacity of the cerebrovasculature to buffer changes in blood pressure (BP) is crucial to prevent stroke, the incidence of which is three- to fourfold elevated after spinal cord injury (SCI). Disruption of descending sympathetic pathways within the spinal cord due to cervical SCI may result in impaired cerebrovascular buffering. Only linear analyses of cerebrovascular buffering of BP, such as transfer function, have been used in SCI research. This approach does not account for inherent nonlinearity and nonstationarity components of cerebrovascular regulation, often depends on perturbations of BP to increase the statistical power, and does not account for the influence of arterial CO2 tension. Here, we used a nonlinear and nonstationary analysis approach termed wavelet decomposition analysis (WDA), which recently identified novel sympathetic influences on cerebrovascular buffering of BP occurring in the ultra-low-frequency range (ULF; 0.02-0.03Hz). WDA does not require BP perturbations and can account for influences of CO2 tension. Supine resting beat-by-beat BP (Finometer), middle cerebral artery blood velocity (transcranial Doppler), and end-tidal CO2 tension were recorded in cervical SCI ( n = 14) and uninjured ( n = 16) individuals. WDA revealed that cerebral blood flow more closely follows changes in BP in the ULF range ( P = 0.0021, Cohen's d = 0.89), which may be interpreted as an impairment in cerebrovascular buffering of BP. This persisted after accounting for CO2. Transfer function metrics were not different in the ULF range, but phase was reduced at 0.07-0.2 Hz ( P = 0.03, Cohen's d = 0.31). Sympathetically mediated cerebrovascular buffering of BP is impaired after SCI, and WDA is a powerful strategy for evaluating cerebrovascular buffering in clinical populations.
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Affiliation(s)
- Saqib Saleem
- Department of Electrical Engineering, COMSATS Institute of Information Technology , Sahiwal , Pakistan.,Wellington Medical Technology Group, Centre for Translational Physiology, University of Otago , Wellington , New Zealand
| | - Diana Vucina
- Department of Neurology, Clinical Hospital Center Split , Split , Croatia
| | - Zoe Sarafis
- International Collaboration on Repair Discoveries, Faculty of Medicine, University of British Columbia, Vancouver, British Columbia, Canada
| | - Amanda H X Lee
- International Collaboration on Repair Discoveries, Faculty of Medicine, University of British Columbia, Vancouver, British Columbia, Canada.,Experimental Medicine Program, Faculty of Medicine, University of British Columbia, Vancouver, British Columbia, Canada
| | - Jordan W Squair
- Departments of Physiology and Pharmacology, Cardiac Sciences, and Clinical Neurosciences, Libin Cardiovascular Institute of Alberta, Hotchkiss Brain Institute, University of Calgary, Alberta, Canada.,MD/PhD Training Program, Faculty of Medicine, University of British Columbia, Vancouver, British Columbia, Canada.,International Collaboration on Repair Discoveries, Faculty of Medicine, University of British Columbia, Vancouver, British Columbia, Canada.,Experimental Medicine Program, Faculty of Medicine, University of British Columbia, Vancouver, British Columbia, Canada
| | - Otto F Barak
- Faculty of Medicine, University of Novi Sad, Novi Sad, Serbia.,Faculty of Sport and Physical Education, University of Novi Sad, Novi Sad, Serbia
| | - Geoff B Coombs
- Centre for Heart, Lung and Vascular Health, School of Health and Exercise Sciences, University of British Columbia Okanagan , Kelowna, British Columbia , Canada
| | - Tanja Mijacika
- Department of Integrative Physiology, University of Split School of Medicine , Split , Croatia
| | - Andrei V Krassioukov
- International Collaboration on Repair Discoveries, Faculty of Medicine, University of British Columbia, Vancouver, British Columbia, Canada
| | - Philip N Ainslie
- Centre for Heart, Lung and Vascular Health, School of Health and Exercise Sciences, University of British Columbia Okanagan , Kelowna, British Columbia , Canada
| | - Zeljko Dujic
- Department of Integrative Physiology, University of Split School of Medicine , Split , Croatia
| | - Yu-Chieh Tzeng
- Wellington Medical Technology Group, Centre for Translational Physiology, University of Otago , Wellington , New Zealand
| | - Aaron A Phillips
- Departments of Physiology and Pharmacology, Cardiac Sciences, and Clinical Neurosciences, Libin Cardiovascular Institute of Alberta, Hotchkiss Brain Institute, University of Calgary, Alberta, Canada
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A comparison of static and dynamic cerebral autoregulation during mild whole-body cold stress in individuals with and without cervical spinal cord injury: a pilot study. Spinal Cord 2018; 56:469-477. [PMID: 29330514 DOI: 10.1038/s41393-017-0021-7] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/30/2017] [Revised: 09/14/2017] [Accepted: 09/14/2017] [Indexed: 11/09/2022]
Abstract
STUDY DESIGN Experimental study. OBJECTIVES To characterize static and dynamic cerebral autoregulation (CA) of individuals with cervical spinal cord injury (SCI) compared to able-bodied controls in response to moderate increases in mean arterial pressure (MAP) caused by mild whole-body cold stress. SETTING Japan METHODS: Five men with complete autonomic cervical SCI (sustained > 5 y) and six age-matched able-bodied men participated in hemodynamic, temperature, catecholamine and respiratory measurements for 60 min during three consecutive stages: baseline (10 min; 33 °C water through a thin-tubed whole-body suit), mild cold stress (20 min; 25 °C water), and post-cold recovery (30 min; 33 °C water). Static CA was determined as the ratio between mean changes in middle cerebral artery blood velocity and MAP, dynamic CA as transfer function coherence, gain, and phase between spontaneous changes in MAP to middle cerebral artery blood velocity. RESULTS MAP increased in both groups during cold and post-cold recovery (mean differences: 5-10 mm Hg; main effect of time: p = 0.001). Static CA was not different between the able-bodied vs. the cervical SCI group (mean (95% confidence interval (CI)) of between-group difference: -4 (-11 to 3) and -2 (-5 to 1) cm/s/mm Hg for cold (p = 0.22) and post-cold (p = 0.24), respectively). At baseline, transfer function phase was shorter in the cervical SCI group (mean (95% CI) of between-group difference: 0.6 (0.2 to 1.0) rad; p = 0.006), while between-group differences in changes in phase were not different in response to the cold stress (interaction term: p = 0.06). CONCLUSIONS This pilot study suggests that static CA is similar between individuals with cervical SCI and able-bodied controls in response to moderate increases in MAP, while dynamic CA may be impaired in cervical SCI because of disturbed sympathetic control.
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Affiliation(s)
- J Andrew Taylor
- Physical Medicine and Rehabilitation, Harvard Medical School, Boston, MA 02134, United States; Cardiovascular Research Laboratory, Spaulding Hospital Cambridge, Cambridge, MA 02138, United States.
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10
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Alterations in autonomic cerebrovascular control after spinal cord injury. Auton Neurosci 2017; 209:43-50. [PMID: 28416148 PMCID: PMC6432623 DOI: 10.1016/j.autneu.2017.04.001] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/03/2016] [Revised: 04/02/2017] [Accepted: 04/03/2017] [Indexed: 11/24/2022]
Abstract
Among chronic cardiovascular and metabolic sequelae of spinal cord injury (SCI) is an up-to four-fold increase in the risk of ischemic and hemorrhagic stroke, suggesting that individuals with SCI cannot maintain stable cerebral perfusion. In able-bodied individuals, the cerebral vasculature is able to regulate cerebral perfusion in response to swings in arterial pressure (cerebral autoregulation), blood gases (cerebral vasoreactivity), and neural metabolic demand (neurovascular coupling). This ability depends, at least partly, on intact autonomic function, but high thoracic and cervical spinal cord injuries result in disruption of sympathetic and parasympathetic cerebrovascular control. In addition, alterations in autonomic and/or vascular function secondary to paralysis and physical inactivity can impact cerebrovascular function independent of the disruption of autonomic control due to injury. Thus, it is conceivable that SCI results in cerebrovascular dysfunction that may underlie an elevated risk of stroke in this population, and that rehabilitation strategies targeting this dysfunction may alleviate the long-term risk of adverse cerebrovascular events. However, despite this potential direct link between SCI and the risk of stroke, studies exploring this relationship are surprisingly scarce, and the few available studies provide equivocal results. The focus of this review is to provide an integrated overview of the available data on alterations in cerebral vascular function after SCI in humans, and to provide suggestions for future research.
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11
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Wecht JM, Weir JP, Bauman WA. Inter-day reliability of blood pressure and cerebral blood flow velocities in persons with spinal cord injury and intact controls. J Spinal Cord Med 2017; 40:159-169. [PMID: 26860937 PMCID: PMC5430472 DOI: 10.1080/10790268.2015.1135556] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 10/22/2022] Open
Abstract
BACKGROUND Due to interruption of cardiovascular autonomic control unstable blood pressure (BP) is common in individuals with spinal cord injury (SCI) above the sixth thoracic vertebral level. The impact of unstable BP on cerebral blood flow (CBF) is not well appreciated, but symptoms associated with altered cerebral perfusion are reported, which can negatively impact daily life activities. METHODS We measured seated BP and CBF in participants with SCI and able-bodied (AB) controls on three laboratory visits to determine the inter-day reliability (intraclass correlation coefficient: ICC). BP was assessed at the finger using photoplethysmography and at the brachial artery with manual sphygmomanometry. CBF velocities (CBFv) were assessed at the middle cerebral artery using transcranial Doppler (TCD) ultrasound. RESULTS Data were collected in 15 participants with chronic SCI (C3-T4) and 10 AB controls, the groups did not differ for age, height, weight or BMI; however, brachial BP (P < 0.001), finger BP (P < 0.01) and CBFv (P < 0.05) were significantly lower in the SCI group compared to the controls. The inter-day ICC for brachial BP ranged from 0.51 to 0.79, whereas the ICC for finger BP was not as high (0.17 to 0.47). The inter-day ICC for CBFv ranged from 0.45 to 0.96, indicating fair to substantial reliability. CONCLUSIONS These data indicate good inter-day reliability of brachial BP and TCD recording of CBFv; however, the assessment of finger BP appears to be somewhat less reliable. In addition, these data confirm reduced resting CBFv in association with hypotension in individuals with SCI compared to matched controls with low BP.
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Affiliation(s)
- Jill M. Wecht
- VA RR&D Center for the Medical Consequences of Spinal Cord Injury, James J. Peters VAMC, Bronx, NY, USA,Department of Medicine, The Icahn School of Medicine at Mount Sinai, New York, NY, USA,Department of Rehabilitation Medicine, The Icahn School of Medicine at Mount Sinai, New York, NY, USA,Correspondence to: Jill M. Wecht, Center of Excellence: Medical Consequences of Spinal Cord Injury, James J. Peters VA Medical Center; Room 1E-02, 130 West Kingsbridge Rd., Bronx, NY 10468, USA. E-mail:
| | - Joseph P. Weir
- Department of Health, Sport and Exercise Sciences, The University of Kansas, Lawrence, KS, USA
| | - William A. Bauman
- VA RR&D Center for the Medical Consequences of Spinal Cord Injury, James J. Peters VAMC, Bronx, NY, USA,The Medical Service, James J. Peters VAMC, Bronx, NY, USA,Department of Medicine, The Icahn School of Medicine at Mount Sinai, New York, NY, USA,Department of Rehabilitation Medicine, The Icahn School of Medicine at Mount Sinai, New York, NY, USA
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12
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Wecht JM, Weir JP, Radulovic M, Bauman WA. Effects of midodrine and L-NAME on systemic and cerebral hemodynamics during cognitive activation in spinal cord injury and intact controls. Physiol Rep 2016; 4:4/3/e12683. [PMID: 26869679 PMCID: PMC4758920 DOI: 10.14814/phy2.12683] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/06/2023] Open
Abstract
We previously showed that increases in mean arterial pressure (MAP) following administration of midodrine hydrochloride (MH) and nitro‐L‐arginine methyl ester (L‐NAME) resulted in increased mean cerebral blood flow velocity (MFV) during head‐up tilt in hypotensive individuals with spinal cord injury (SCI) and question if this same association was evident during cognitive activation. Herein, we report MAP and MFV during two serial subtraction tasks (SSt) given before (predrug) and after (postdrug) administration of MH; (10 mg), L‐NAME (1 mg/kg) or no drug (ND) in 15 subjects with SCI compared to nine able‐bodied (AB) controls. Three‐way factorial analysis of variance (ANOVA) models were used to determine significant main and interaction effects for group (SCI, AB), visit (MH, L‐NAME, ND), and time (predrug, postdrug) for MAP and MFV during the two SSt. The three‐way interaction was significant for MAP (F = 4.262; P = 0.020); both MH (30 ± 26 mmHg; P < 0.05) and L‐NAME (27 ± 22 mmHg; P < 0.01) significantly increased MAP in the SCI group, but not in the AB group. There was a significant visit by time interaction for MFV suggesting an increase from predrug to postdrug following L‐NAME (6 ± 8 cm/sec; P < 0.05) and MH (4 ± 7 cm/sec; P < 0.05), regardless of study group, with little change following ND (3 ± 3 cm/sec). The relationship between change in MAP and MFV was significant in the SCI group following administration of MH (r2 = 0.38; P < 0.05) and L‐NAME (r2 = 0.32; P < 0.05). These antihypotensive agents, at the doses tested, raised MAP, which was associated with an increase MFV during cognitive activation in hypotensive subjects with SCI.
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Affiliation(s)
- Jill M Wecht
- VA RR&D National Center for the Medical Consequences of Spinal Cord Injury, James J. Peters VAMC, Bronx, New York The Medical Service, James J. Peters VAMC, Bronx New York Department of Medicine, The Icahn School of Medicine at Mount Sinai, New York, New York Department of Rehabilitation Medicine, The Icahn School of Medicine at Mount Sinai, New York, New York
| | - Joseph P Weir
- Department of Health, Sport and Exercise Sciences, The University of Kansas, Lawrence, Kansas
| | - Miroslav Radulovic
- VA RR&D National Center for the Medical Consequences of Spinal Cord Injury, James J. Peters VAMC, Bronx, New York The Medical Service, James J. Peters VAMC, Bronx New York Department of Medicine, The Icahn School of Medicine at Mount Sinai, New York, New York Department of Rehabilitation Medicine, The Icahn School of Medicine at Mount Sinai, New York, New York
| | - William A Bauman
- VA RR&D National Center for the Medical Consequences of Spinal Cord Injury, James J. Peters VAMC, Bronx, New York The Medical Service, James J. Peters VAMC, Bronx New York Department of Medicine, The Icahn School of Medicine at Mount Sinai, New York, New York Department of Rehabilitation Medicine, The Icahn School of Medicine at Mount Sinai, New York, New York
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13
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Phillips AA, Matin N, Frias B, Zheng MMZ, Jia M, West C, Dorrance AM, Laher I, Krassioukov AV. Rigid and remodelled: cerebrovascular structure and function after experimental high-thoracic spinal cord transection. J Physiol 2016; 594:1677-88. [PMID: 26634420 DOI: 10.1113/jp270925] [Citation(s) in RCA: 27] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/12/2015] [Accepted: 11/18/2015] [Indexed: 12/25/2022] Open
Abstract
High-thoracic or cervical spinal cord injury (SCI) is associated with several critical clinical conditions related to impaired cerebrovascular health, including: 300-400% increased risk of stroke, cognitive decline and diminished cerebral blood flow regulation. The purpose of this study was to examine the influence of high-thoracic (T3 spinal segment) SCI on cerebrovascular structure and function, as well as molecular markers of profibrosis. Seven weeks after complete T3 spinal cord transection (T3-SCI, n = 15) or sham injury (Sham, n = 10), rats were sacrificed for either middle cerebral artery (MCA) structure and function assessments via ex vivo pressure myography, or immunohistochemical analyses. Myogenic tone was unchanged, but over a range of transmural pressures, inward remodelling occurred after T3-SCI with a 40% reduction in distensibility (both P < 0.05), and a 33% reduction in vasoconstrictive reactivity to 5-HT trending toward significance (P = 0.09). After T3-SCI, the MCA had more collagen I (42%), collagen III (24%), transforming growth factor β (47%) and angiotensin II receptor type 2 (132%), 27% less elastin as well as concurrent increased wall thickness and reduced lumen diameter (all P < 0.05). Sympathetic innervation (tyrosine hydroxylase-positive axon density) and endothelium-dependent dilatation (carbachol) of the MCA were not different between groups. This study demonstrates profibrosis and hypertrophic inward remodelling within the largest cerebral artery after high-thoracic SCI, leading to increased stiffness and possibly impaired reactivity. These deleterious adaptations would substantially undermine the capacity for regulation of cerebral blood flow and probably underlie several cerebrovascular clinical conditions in the SCI population.
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Affiliation(s)
- A A Phillips
- International Collaboration on Repair Discoveries, Faculty of Medicine, University of British Columbia, Vancouver, Canada.,Experimental Medicine Program, Faculty of Medicine, University of British Columbia, Vancouver, Canada.,Centre for Heart, Lung, and Vascular Health, Faculty of Health and Social Development, University of British Columbia, Vancouver, Canada
| | - N Matin
- Pharmacology, Michigan State University, East Lansing, MI, USA
| | - B Frias
- International Collaboration on Repair Discoveries, Faculty of Medicine, University of British Columbia, Vancouver, Canada
| | - M M Z Zheng
- International Collaboration on Repair Discoveries, Faculty of Medicine, University of British Columbia, Vancouver, Canada.,Experimental Medicine Program, Faculty of Medicine, University of British Columbia, Vancouver, Canada
| | - M Jia
- International Collaboration on Repair Discoveries, Faculty of Medicine, University of British Columbia, Vancouver, Canada
| | - C West
- International Collaboration on Repair Discoveries, Faculty of Medicine, University of British Columbia, Vancouver, Canada
| | - A M Dorrance
- Pharmacology, Michigan State University, East Lansing, MI, USA
| | - I Laher
- Deptartment of Pharmacology and Therapeutic, Faculty of Medicine, University of British Columbia, Vancouver, Canada
| | - A V Krassioukov
- International Collaboration on Repair Discoveries, Faculty of Medicine, University of British Columbia, Vancouver, Canada.,GF Strong Rehabilitation Center, Vancouver Coastal Health, Vancouver, Canada.,Division of Physical Medicine and Rehabilitation, Department of Medicine, University of British Columbia, Vancouver, Canada
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14
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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]
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15
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Phillips AA, Krassioukov AV, Ainslie PN, Warburton DER. Perturbed and spontaneous regional cerebral blood flow responses to changes in blood pressure after high-level spinal cord injury: the effect of midodrine. J Appl Physiol (1985) 2014; 116:645-53. [PMID: 24436297 DOI: 10.1152/japplphysiol.01090.2013] [Citation(s) in RCA: 48] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/27/2022] Open
Abstract
Individuals with spinal cord injury (SCI) above the T6 spinal segment suffer from orthostatic intolerance. How cerebral blood flow (CBF) responds to orthostatic challenges in SCI is poorly understood. Furthermore, it is unclear how interventions meant to improve orthostatic tolerance in SCI influence CBF. This study aimed to examine 1) the acute regional CBF responses to rapid changes in blood pressure (BP) during orthostatic stress in individuals with SCI and able-bodied (AB) individuals; and 2) the effect of midodrine (alpha1-agonist) on orthostatic tolerance and CBF regulation in SCI. Ten individuals with SCI >T6, and 10 age- and sex-matched AB controls had beat-by-beat BP and middle and posterior cerebral artery blood velocity (MCAv, PCAv, respectively) recorded during a progressive tilt-test to quantify the acute CBF response and orthostatic tolerance. Dynamic MCAv and PCAv to BP relationships were evaluated continuously in the time domain and frequency domain (via transfer function analysis). The SCI group was tested again after administration of 10 mg midodrine to elevate BP. Coherence (i.e., linearity) was elevated in SCI between BP-MCAv and BP-PCAv by 35% and 22%, respectively, compared with AB, whereas SCI BP-PCAv gain (i.e., magnitudinal relationship) was reduced 30% compared with AB (all P < 0.05). The acute (i.e., 0-30 s after tilt) MCAv and PCAv responses were similar between groups. In individuals with SCI, midodrine led to improved PCAv responses 30-60 s following tilt (10 ± 3% vs. 4 ± 2% decline; P < 0.05), and a 59% improvement in orthostatic tolerance (P < 0.01). The vertebrobasilar region may be particularly susceptible to hypoperfusion in SCI, leading to increased orthostatic intolerance.
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Affiliation(s)
- Aaron A Phillips
- Cardiovascular Physiology and Rehabilitation Laboratory, Physical Activity Promotion and Chronic Disease Prevention Unit, University of British Columbia, Vancouver, British Columbia, Canada
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16
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Phillips AA, Ainslie PN, Krassioukov AV, Warburton DER. Regulation of cerebral blood flow after spinal cord injury. J Neurotrauma 2013; 30:1551-63. [PMID: 23758347 DOI: 10.1089/neu.2013.2972] [Citation(s) in RCA: 36] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/06/2023] Open
Abstract
Significant cardiovascular and autonomic dysfunction occurs after era spinal cord injury (SCI). Two major conditions arising from autonomic dysfunction are orthostatic hypotension and autonomic dysreflexia (i.e., severe acute hypertension). Effective regulation of cerebral blood flow (CBF) is essential to offset these drastic changes in cerebral perfusion pressure. In the context of orthostatic hypotension and autonomic dysreflexia, the purpose of this review is to critically examine the mechanisms underlying effective CBF after an SCI and propose future avenues for research. Although only 16 studies have examined CBF control in those with high-level SCI (above the sixth thoracic spinal segment), it appears that CBF regulation is markedly altered in this population. Cerebrovascular function comprises three major mechanisms: (1) cerebral autoregulation, (i.e., ΔCBF/Δ blood pressure); (2) cerebrovascular reactivity to changes in PaCO2 (i.e. ΔCBF/arterial gas concentration); and (3) neurovascular coupling (i.e., ΔCBF/Δ metabolic demand). While static cerebral autoregulation appears to be well maintained in high-level SCI, dynamic cerebral autoregulation, cerebrovascular reactivity, and neurovascular coupling appear to be markedly altered. Several adverse complications after high-level SCI may mediate the changes in CBF regulation including: systemic endothelial dysfunction, sleep apnea, dyslipidemia, decentralization of sympathetic control, and dominant parasympathetic activity. Future studies are needed to describe whether altered CBF responses after SCI aid or impede orthostatic tolerance. Further, simultaneous evaluation of extracranial and intracranial CBF, combined with modern structural and functional imaging, would allow for a more comprehensive evaluation of CBF regulatory processes. We are only beginning to understand the functional effects of dysfunctional CBF regulation on brain function on persons with SCI, which are likely to include increased risk of transient ischemic attacks, stroke, and cognitive dysfunction.
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Affiliation(s)
- Aaron A Phillips
- Cardiovascular Physiology and Rehabilitation Laboratory, University of British Columbia, Vancouver, Canada
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17
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Cerebrovascular autoregulation: lessons learned from spaceflight research. Eur J Appl Physiol 2012; 113:1909-17. [PMID: 23132388 DOI: 10.1007/s00421-012-2539-x] [Citation(s) in RCA: 36] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/10/2012] [Accepted: 10/24/2012] [Indexed: 10/27/2022]
Abstract
This review summarizes our current understanding of cerebral blood flow regulation with exposure to microgravity, outlines potential mechanisms associated with post-flight orthostatic intolerance, and proposes future directions for research and linkages with cerebrovascular disorders found in the general population. It encompasses research from cellular mechanisms (e.g. hind limb suspension: tissue, animal studies) to whole body analysis with respect to understanding human responses using space analogue studies (bed rest, parabolic flight) as well as data collected before, during, and after spaceflight. Recent evidence indicates that cerebrovascular autoregulation may be impaired in some astronauts leading to increased susceptibility to syncope upon return to a gravitational environment. The proposed review not only provides insights into the mechanisms of post-flight orthostatic intolerance, but also increases our understanding of the mechanisms associated with pathophysiological conditions (e.g. unexplained syncope) with clinical applications in relation to postural hypotension or intradialytic hypotension.
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18
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Phillips AA, Krassioukov AV, Ainslie PN, Warburton DE. Baroreflex Function after Spinal Cord Injury. J Neurotrauma 2012; 29:2431-45. [DOI: 10.1089/neu.2012.2507] [Citation(s) in RCA: 40] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/22/2023] Open
Affiliation(s)
- Aaron A. Phillips
- Cardiovascular Physiology and Rehabilitation Laboratory, Physical Activity Promotion and Chronic Disease Prevention Unit, University of British Columbia, British Columbia, Canada
- Experimental Medicine Program, Faculty of Medicine, University of British Columbia, British Columbia, Canada
- International Collaboration of Repair Discoveries, University of British Columbia, British Columbia, Canada
| | - Andrei V. Krassioukov
- Experimental Medicine Program, Faculty of Medicine, University of British Columbia, British Columbia, Canada
- International Collaboration of Repair Discoveries, University of British Columbia, British Columbia, Canada
- Division of Physical Medicine and Rehabilitation, Department of Medicine, University of British Columbia, British Columbia, Canada
| | - Philip N. Ainslie
- School of Health and Exercise Sciences, Faculty of Health and Social Development, University of British Columbia Okanagan, Kelowna, British Columbia, Canada
| | - Darren E.R. Warburton
- Cardiovascular Physiology and Rehabilitation Laboratory, Physical Activity Promotion and Chronic Disease Prevention Unit, University of British Columbia, British Columbia, Canada
- Experimental Medicine Program, Faculty of Medicine, University of British Columbia, British Columbia, Canada
- International Collaboration of Repair Discoveries, University of British Columbia, British Columbia, Canada
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Sahota IS, Ravensbergen HRJC, McGrath MS, Claydon VE. Cerebrovascular responses to orthostatic stress after spinal cord injury. J Neurotrauma 2012; 29:2446-56. [PMID: 22720841 DOI: 10.1089/neu.2012.2379] [Citation(s) in RCA: 40] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/22/2023] Open
Abstract
Orthostatic hypotension (OH) is a debilitating condition affecting individuals with spinal cord injury (SCI) that may be associated with cerebral hypoperfusion. We studied orthostatic cerebral control in individuals with SCI with different levels and severities of injury to spinal cardiovascular autonomic pathways. We measured beat-to-beat cardiovascular and cerebrovascular responses to passive orthostatic stress in 16 controls and 26 subjects with chronic SCI. Cerebrovascular control was assessed from diastolic cerebral blood flow velocity (CBFV(D)), and indices of static and dynamic cerebral autoregulation. Severity of autonomic injury was inferred from spectral analyses of systolic arterial pressure, and supine plasma noradrenaline concentrations. Symptoms of OH were evaluated using questionnaires. CBFV(D) decreased during orthostasis only in individuals with autonomically complete injuries above T6. Orthostatic CBFV(D) was significantly correlated (p<0.05) with the severity of autonomic injury. Individuals with injuries above T6 had impaired dynamic autoregulation (p<0.05) compared to controls, and this was correlated (p<0.05) with the severity of autonomic injury. Individuals with autonomically complete SCI reported increased severity of symptoms relative to controls (p<0.05). Symptom severity was correlated with the efficacy of dynamic autoregulation. During orthostatic stress, SCI individuals have impaired cerebrovascular control that is related to the level and severity of autonomic injury.
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Affiliation(s)
- Inderjeet S Sahota
- Department of Biomedical Physiology and Kinesiology, Simon Fraser University, Burnaby, British Columbia, Canada
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20
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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]
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21
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Willie CK, Colino FL, Bailey DM, Tzeng YC, Binsted G, Jones LW, Haykowsky MJ, Bellapart J, Ogoh S, Smith KJ, Smirl JD, Day TA, Lucas SJ, Eller LK, Ainslie PN. Utility of transcranial Doppler ultrasound for the integrative assessment of cerebrovascular function. J Neurosci Methods 2011; 196:221-37. [PMID: 21276818 DOI: 10.1016/j.jneumeth.2011.01.011] [Citation(s) in RCA: 397] [Impact Index Per Article: 30.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/22/2010] [Revised: 01/05/2011] [Accepted: 01/06/2011] [Indexed: 01/05/2023]
Abstract
There is considerable utility in the use of transcranial Doppler ultrasound (TCD) to assess cerebrovascular function. The brain is unique in its high energy and oxygen demand but limited capacity for energy storage that necessitates an effective means of regional blood delivery. The relative low cost, ease-of-use, non-invasiveness, and excellent temporal resolution of TCD make it an ideal tool for the examination of cerebrovascular function in both research and clinical settings. TCD is an efficient tool to access blood velocities within the cerebral vessels, cerebral autoregulation, cerebrovascular reactivity to CO(2), and neurovascular coupling, in both physiological states and in pathological conditions such as stroke and head trauma. In this review, we provide: (1) an overview of TCD methodology with respect to other techniques; (2) a methodological synopsis of the cerebrovascular exam using TCD; (3) an overview of the physiological mechanisms involved in regulation of the cerebral blood flow; (4) the utility of TCD for assessment of cerebrovascular pathology; and (5) recommendations for the assessment of four critical and complimentary aspects of cerebrovascular function: intra-cranial blood flow velocity, cerebral autoregulation, cerebral reactivity, and neurovascular coupling. The integration of these regulatory mechanisms from an integrated systems perspective is discussed, and future research directions are explored.
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Affiliation(s)
- C K Willie
- Department of Human Kinetics, Faculty of Health and Social Development, University of British Columbia Okanagan, 3333 University Way, Kelowna, BC, Canada V1V 1V7.
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