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Norager NH, Lilja-Cyron A, Riedel CS, Holst AV, Pedersen SH, Juhler M. Intracranial pressure following surgery of an unruptured intracranial aneurysm-a model for normal intracranial pressure in humans. Fluids Barriers CNS 2024; 21:44. [PMID: 38773608 PMCID: PMC11110356 DOI: 10.1186/s12987-024-00549-1] [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: 02/07/2024] [Accepted: 05/07/2024] [Indexed: 05/24/2024] Open
Abstract
OBJECTIVE Optimizing the treatment of several neurosurgical and neurological disorders relies on knowledge of the intracranial pressure (ICP). However, exploration of normal ICP and intracranial pressure pulse wave amplitude (PWA) values in healthy individuals poses ethical challenges, and thus the current documentation remains scarce. This study explores ICP and PWA values for healthy adults without intracranial pathology expected to influence ICP. METHODS Adult patients (age > 18 years) undergoing surgery for an unruptured intracranial aneurysm without any other neurological co-morbidities were included. Patients had a telemetric ICP sensor inserted, and ICP was measured in four different positions: supine, lateral recumbent, standing upright, and 45-degree sitting, at day 1, 14, 30, and 90 following the surgery. RESULTS ICP in each position did not change with time after surgery. Median ICP was 6.7 mmHg and median PWA 2.1 mmHg in the supine position, while in the upright standing position median ICP was - 3.4 mmHg and median PWA was 1.9 mmHg. After standardization of the measurements from the transducer site to the external acoustic meatus, the median ICPmidbrain was 8.3 mmHg in the supine position and 1.2 mmHg in the upright standing position. CONCLUSION Our study provides insights into normal ICP dynamics in healthy adults following a uncomplicated surgery for an unruptured aneurysm. These results suggest a slightly wider normal reference range for invasive intracranial pressure than previously suggested, and present the first normal values for PWA in different positions. Further studies are, however, essential to enhance our understanding of normal ICP. Trial registration The study was preregistered at www. CLINICALTRIALS gov (NCT03594136) (11 July 2018).
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Affiliation(s)
- Nicolas Hernandez Norager
- Clinic of Neurosurgery, Copenhagen University Hospital, Inge Lehmanns Vej 6, 2100, Copenhagen East, Denmark.
| | - Alexander Lilja-Cyron
- Clinic of Neurosurgery, Copenhagen University Hospital, Inge Lehmanns Vej 6, 2100, Copenhagen East, Denmark
| | - Casper Schwartz Riedel
- Clinic of Neurosurgery, Copenhagen University Hospital, Inge Lehmanns Vej 6, 2100, Copenhagen East, Denmark
| | - Anders Vedel Holst
- Clinic of Neurosurgery, Copenhagen University Hospital, Inge Lehmanns Vej 6, 2100, Copenhagen East, Denmark
| | - Sarah Hornshoej Pedersen
- Clinic of Neurosurgery, Copenhagen University Hospital, Inge Lehmanns Vej 6, 2100, Copenhagen East, Denmark
| | - Marianne Juhler
- Clinic of Neurosurgery, Copenhagen University Hospital, Inge Lehmanns Vej 6, 2100, Copenhagen East, Denmark
- Clinic of Neurosurgery, Aarhus University Hospital, Aarhus, Denmark
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Ong J, Waisberg E, Masalkhi M, Suh A, Kamran SA, Paladugu P, Sarker P, Zaman N, Tavakkoli A, Lee AG. "Spaceflight-to-Eye Clinic": Terrestrial advances in ophthalmic healthcare delivery from space-based innovations. LIFE SCIENCES IN SPACE RESEARCH 2024; 41:100-109. [PMID: 38670636 DOI: 10.1016/j.lssr.2024.02.003] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/06/2023] [Accepted: 02/08/2024] [Indexed: 04/28/2024]
Abstract
The phrase "Bench-to-Bedside" is a well-known phrase in medicine, highlighting scientific discoveries that directly translate to impacting patient care. Key examples of translational research include identification of key molecular targets in diseases and development of diagnostic laboratory tests for earlier disease detection. Bridging these scientific advances to the bedside/clinic has played a meaningful impact in numerous patient lives. The spaceflight environment poses a unique opportunity to also make this impact; the nature of harsh extraterrestrial conditions and medically austere and remote environments push for cutting-edge technology innovation. Many of these novel technologies built for the spaceflight environment also have numerous benefits for human health on Earth. In this manuscript, we focus on "Spaceflight-to-Eye Clinic" and discuss technologies built for the spaceflight environment that eventually helped to optimize ophthalmic health on Earth (e.g., LADAR for satellite docking now utilized in eye-tracking technology for LASIK). We also discuss current technology research for spaceflight associated neuro-ocular syndrome (SANS) that may also be applied to terrestrial ophthalmic health. Ultimately, various advances made to enable to the future of space exploration have also advanced the ophthalmic health of individuals on Earth.
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Affiliation(s)
- Joshua Ong
- Department of Ophthalmology and Visual Sciences, Kellogg Eye Center, University of Michigan, Ann Arbor, MI, United States.
| | - Ethan Waisberg
- Department of Ophthalmology, University of Cambridge, Cambridge, United Kingdom
| | - Mouayad Masalkhi
- University College Dublin School of Medicine, Belfield, Dublin, Ireland
| | - Alex Suh
- Tulane University School of Medicine, New Orleans, LA, United States
| | - Sharif Amit Kamran
- Human-Machine Perception Laboratory, Department of Computer Science and Engineering, University of Nevada, Reno, NV, United States
| | - Phani Paladugu
- Brigham and Women's Hospital, Harvard Medical School, Boston, MA, United States; Sidney Kimmel Medical College, Thomas Jefferson University, Philadelphia, PA, United States
| | - Prithul Sarker
- Human-Machine Perception Laboratory, Department of Computer Science and Engineering, University of Nevada, Reno, NV, United States
| | - Nasif Zaman
- Human-Machine Perception Laboratory, Department of Computer Science and Engineering, University of Nevada, Reno, NV, United States
| | - Alireza Tavakkoli
- Human-Machine Perception Laboratory, Department of Computer Science and Engineering, University of Nevada, Reno, NV, United States
| | - Andrew G Lee
- Center for Space Medicine, Baylor College of Medicine, Houston, TX, United States; Department of Ophthalmology, Blanton Eye Institute, Houston Methodist Hospital, Houston, TX, United States; The Houston Methodist Research Institute, Houston Methodist Hospital, Houston, TX, United States; Departments of Ophthalmology, Neurology, and Neurosurgery, Weill Cornell Medicine, New York, NY, United States; Department of Ophthalmology, University of Texas Medical Branch, Galveston, TX, United States; University of Texas MD Anderson Cancer Center, Houston, TX, United States; Texas A&M College of Medicine, TX, United States; Department of Ophthalmology, The University of Iowa Hospitals and Clinics, Iowa City, IA, United States
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Fois M, Diaz-Artiles A, Zaman SY, Ridolfi L, Scarsoglio S. Linking cerebral hemodynamics and ocular microgravity-induced alterations through an in silico-in vivo head-down tilt framework. NPJ Microgravity 2024; 10:22. [PMID: 38413627 PMCID: PMC10899661 DOI: 10.1038/s41526-024-00366-8] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/30/2023] [Accepted: 02/15/2024] [Indexed: 02/29/2024] Open
Abstract
Head-down tilt (HDT) has been widely proposed as a terrestrial analog of microgravity and used also to investigate the occurrence of spaceflight-associated neuro-ocular syndrome (SANS), which is currently considered one of the major health risks for human spaceflight. We propose here an in vivo validated numerical framework to simulate the acute ocular-cerebrovascular response to 6° HDT, to explore the etiology and pathophysiology of SANS. The model links cerebral and ocular posture-induced hemodynamics, simulating the response of the main cerebrovascular mechanisms, as well as the relationship between intracranial and intraocular pressure to HDT. Our results from short-term (10 min) 6° HDT show increased hemodynamic pulsatility in the proximal-to-distal/capillary-venous cerebral direction, a marked decrease (-43%) in ocular translaminar pressure, and an increase (+31%) in ocular perfusion pressure, suggesting a plausible explanation of the underlying mechanisms at the onset of ocular globe deformation and edema formation over longer time scales.
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Affiliation(s)
- Matteo Fois
- Department of Mechanical and Aerospace Engineering, Politecnico di Torino, Corso Duca degli Abruzzi 24, Turin, 10129, Italy.
| | - Ana Diaz-Artiles
- Department of Aerospace Engineering, Texas A&M University, 3141 TAMU, College Station, TX, 77843-3141, USA
- Department of Kinesiology and Sport Management, Texas A&M University, 2929 Research Pkwy, College Station, TX, 77845, USA
| | - Syeda Yasmin Zaman
- Department of Aerospace Engineering, Texas A&M University, 3141 TAMU, College Station, TX, 77843-3141, USA
| | - Luca Ridolfi
- Department of Environmental, Land and Infrastructure Engineering, Politecnico di Torino, Corso Duca degli Abruzzi 24, Turin, 10129, Italy
- PolitoBioMed Lab, Politecnico di Torino, Corso Duca degli Abruzzi 24, Turin, 10129, Italy
| | - Stefania Scarsoglio
- Department of Mechanical and Aerospace Engineering, Politecnico di Torino, Corso Duca degli Abruzzi 24, Turin, 10129, Italy
- PolitoBioMed Lab, Politecnico di Torino, Corso Duca degli Abruzzi 24, Turin, 10129, Italy
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4
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Hearon CM, Peters K, Dias KA, Macnamara JP, Marshall JET, Campain J, Martin D, Marshal‐Goebel K, Levine BD. Assessment of venous pressure by compression sonography of the internal jugular vein during 3 days of bed rest. Exp Physiol 2023; 108:1560-1568. [PMID: 37824038 PMCID: PMC10988448 DOI: 10.1113/ep091372] [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: 06/30/2023] [Accepted: 09/28/2023] [Indexed: 10/13/2023]
Abstract
Compression sonography has been proposed as a method for non-invasive measurement of venous pressures during spaceflight, but initial reports of venous pressure measured by compression ultrasound conflict with prior reports of invasively measured central venous pressure (CVP). The aim of this study is to determine the agreement of compression sonography of the internal jugular vein (IJVP) with invasive measures of CVP over a range of pressures relevant to microgravity exposure. Ten healthy volunteers (18-55 years, five female) completed two 3-day sessions of supine bed rest to simulate microgravity. IJVP and CVP were measured in the seated position, and in the supine position throughout 3 days of bed rest. The range of CVP recorded was in line with previous reports of CVP during changes in posture on Earth and in microgravity. The correlation between IJVP and CVP was poor when measured during spontaneous breathing (r = 0.29; R2 = 0.09; P = 0.0002; standard error of the estimate (SEE) = 3.0 mmHg) or end-expiration CVP (CVPEE ; r = 0.19; R2 = 0.04; P = 0.121; SEE = 3.0 mmHg). There was a modest correlation between the change in CVP and the change in IJVP for both spontaneous ΔCVP (r = 0.49; R2 = 0.24; P < 0.0001) and ΔCVPEE (r = 0.58; R2 = 0.34; P < 0.0001). Bland-Altman analysis of IJVP revealed a large positive bias compared to spontaneous breathing CVP (3.6 mmHg; SD = 4.0; CV = 85%; P < 0.0001) and CVPEE (3.6 mmHg; SD = 4.2; CV = 84%; P < 0.0001). Assessment of absolute IJVP via compression sonography correlated poorly with direct measurements of CVP by invasive catheterization over a range of venous pressures that are physiologically relevant to spaceflight. However, compression sonography showed modest utility for tracking changes in venous pressure over time. NEW FINDINGS: What is the central question of this study? Compression sonography has been proposed as a novel method for non-invasive measurement of venous pressures during spaceflight. However, the accuracy has not yet been confirmed in the range of CVP experienced by astronauts during spaceflight. What is the main finding and its importance? Our data show that compression sonography of the internal jugular vein correlates poorly with direct measurement of central venous pressures in a range that is physiologically relevant to spaceflight. However, compression sonography showed modest utility for tracking changes in venous pressure over time.
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Affiliation(s)
- Christopher M. Hearon
- Institute for Exercise and Environmental MedicineTexas Health Presbyterian Hospital DallasDallasTXUSA
- University of Texas Southwestern Medical CenterDallasTXUSA
| | - Kirsten Peters
- University Medical CenterRadboud UniversityNijmegenthe Netherlands
| | - Katrin A. Dias
- Institute for Exercise and Environmental MedicineTexas Health Presbyterian Hospital DallasDallasTXUSA
- University of Texas Southwestern Medical CenterDallasTXUSA
| | - James P. Macnamara
- Institute for Exercise and Environmental MedicineTexas Health Presbyterian Hospital DallasDallasTXUSA
- University of Texas Southwestern Medical CenterDallasTXUSA
| | - John E. T. Marshall
- Institute for Exercise and Environmental MedicineTexas Health Presbyterian Hospital DallasDallasTXUSA
- University of Texas Southwestern Medical CenterDallasTXUSA
| | - Joseph Campain
- Institute for Exercise and Environmental MedicineTexas Health Presbyterian Hospital DallasDallasTXUSA
- University of Texas Southwestern Medical CenterDallasTXUSA
| | | | | | - Benjamin D. Levine
- Institute for Exercise and Environmental MedicineTexas Health Presbyterian Hospital DallasDallasTXUSA
- University of Texas Southwestern Medical CenterDallasTXUSA
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McGregor HR, Lee JK, Mulder ER, De Dios YE, Beltran NE, Wood SJ, Bloomberg JJ, Mulavara AP, Seidler RD. Artificial gravity during a spaceflight analog alters brain sensory connectivity. Neuroimage 2023; 278:120261. [PMID: 37422277 DOI: 10.1016/j.neuroimage.2023.120261] [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: 11/14/2022] [Revised: 05/06/2023] [Accepted: 06/29/2023] [Indexed: 07/10/2023] Open
Abstract
Spaceflight has numerous untoward effects on human physiology. Various countermeasures are under investigation including artificial gravity (AG). Here, we investigated whether AG alters resting-state brain functional connectivity changes during head-down tilt bed rest (HDBR), a spaceflight analog. Participants underwent 60 days of HDBR. Two groups received daily AG administered either continuously (cAG) or intermittently (iAG). A control group received no AG. We assessed resting-state functional connectivity before, during, and after HDBR. We also measured balance and mobility changes from pre- to post-HDBR. We examined how functional connectivity changes throughout HDBR and whether AG is associated with differential effects. We found differential connectivity changes by group between posterior parietal cortex and multiple somatosensory regions. The control group exhibited increased functional connectivity between these regions throughout HDBR whereas the cAG group showed decreased functional connectivity. This finding suggests that AG alters somatosensory reweighting during HDBR. We also observed brain-behavioral correlations that differed significantly by group. Control group participants who showed increased connectivity between the putamen and somatosensory cortex exhibited greater mobility declines post-HDBR. For the cAG group, increased connectivity between these regions was associated with little to no mobility declines post-HDBR. This suggests that when somatosensory stimulation is provided via AG, functional connectivity increases between the putamen and somatosensory cortex are compensatory in nature, resulting in reduced mobility declines. Given these findings, AG may be an effective countermeasure for the reduced somatosensory stimulation that occurs in both microgravity and HDBR.
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Affiliation(s)
- Heather R McGregor
- Department of Applied Physiology and Kinesiology, University of Florida, Gainesville, FL, United States
| | - Jessica K Lee
- Department of Applied Physiology and Kinesiology, University of Florida, Gainesville, FL, United States; Institute of Aerospace Medicine, German Aerospace Center, Cologne, Germany
| | - Edwin R Mulder
- Institute of Aerospace Medicine, German Aerospace Center, Cologne, Germany
| | | | | | - Scott J Wood
- NASA Johnson Space Center, Houston, TX, United States
| | | | | | - Rachael D Seidler
- Department of Applied Physiology and Kinesiology, University of Florida, Gainesville, FL, United States; Norman Fixel Institute for Neurological Diseases, University of Florida, Gainesville, FL, United States.
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6
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Ong J, Mader TH, Gibson CR, Mason SS, Lee AG. Spaceflight associated neuro-ocular syndrome (SANS): an update on potential microgravity-based pathophysiology and mitigation development. Eye (Lond) 2023; 37:2409-2415. [PMID: 37072472 PMCID: PMC10397180 DOI: 10.1038/s41433-023-02522-y] [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: 09/20/2022] [Revised: 03/21/2023] [Accepted: 04/04/2023] [Indexed: 04/20/2023] Open
Abstract
Long-duration spaceflight is associated with neurologic and ophthalmic clinical and imaging findings in astronauts termed spaceflight associated neuro-ocular syndrome (SANS). These microgravity-induced findings have been well documented by the National Aeronautics and Space Administration (NASA) and are clearly a potential risk for future human space exploration. The underlying pathogenesis of SANS is not well understood, although multiple hypotheses have emerged. Terrestrial analogues and potential countermeasures have also been studied to further understand and potentially mitigate SANS. In this manuscript, we review the current understanding of SANS, discuss the prevailing hypotheses for pathogenesis, and describe current developments in terrestrial analogues and potential countermeasures for SANS.
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Affiliation(s)
- Joshua Ong
- Michigan Medicine, University of Michigan, Ann Arbor, MI, USA
| | | | - C Robert Gibson
- KBR, NASA Johnson Space Center, Houston, TX, USA
- South Shore Eye Center, League City, TX, USA
| | | | - Andrew G Lee
- Department of Ophthalmology, Blanton Eye Institute, Houston Methodist Hospital, Houston, TX, USA.
- Center for Space Medicine, Baylor College of Medicine, Houston, TX, USA.
- The Houston Methodist Research Institute, Houston Methodist Hospital, Houston, TX, USA.
- Departments of Ophthalmology, Neurology, and Neurosurgery, Weill Cornell Medicine, New York, NY, USA.
- Department of Ophthalmology, University of Texas Medical Branch, Galveston, TX, USA.
- University of Texas MD Anderson Cancer Center, Houston, TX, USA.
- Texas A&M College of Medicine, Bryan, TX, USA.
- Department of Ophthalmology, The University of Iowa Hospitals and Clinics, Iowa City, IA, USA.
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7
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Stern C, Yücel YH, Zu Eulenburg P, Pavy-Le Traon A, Petersen LG. Eye-brain axis in microgravity and its implications for Spaceflight Associated Neuro-ocular Syndrome. NPJ Microgravity 2023; 9:56. [PMID: 37474624 PMCID: PMC10359255 DOI: 10.1038/s41526-023-00300-4] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/13/2022] [Accepted: 07/02/2023] [Indexed: 07/22/2023] Open
Abstract
Long-duration human spaceflight can lead to changes in both the eye and the brain, which have been referred to as Spaceflight Associated Neuro-ocular Syndrome (SANS). These changes may manifest as a constellation of symptoms, which can include optic disc edema, optic nerve sheath distension, choroidal folds, globe flattening, hyperopic shift, and cotton wool spots. Although the underpinning mechanisms for SANS are not yet known, contributors may include intracranial interstitial fluid accumulation following microgravity induced headward fluid shift. Development and validation of SANS countermeasures contribute to our understanding of etiology and accelerate new technology including exercise modalities, Lower Body Negative Pressure suits, venous thigh cuffs, and Impedance Threshold Devices. However, significant knowledge gaps remain including biomarkers, a full set of countermeasures and/or treatment regimes, and finally reliable ground based analogs to accelerate the research. This review from the European Space Agency SANS expert group summarizes past research and current knowledge on SANS, potential countermeasures, and key knowledge gaps, to further our understanding, prevention, and treatment of SANS both during human spaceflight and future extraterrestrial surface exploration.
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Affiliation(s)
- Claudia Stern
- Institute of Aerospace Medicine, German Aerospace Center (DLR), Cologne, Germany.
- ISS Operations and Astronauts Group, European Astronaut Centre, European Space Agency (ESA), Cologne, Germany.
| | - Yeni H Yücel
- Keenan Research Centre for Biomedical Science, St. Michael's Hospital, Unity Health Toronto, Toronto, ON, Canada
- Department of Ophthalmology & Vision Sciences, Temerty Faculty of Medicine, University of Toronto, Toronto, ON, Canada
- Department of Laboratory Medicine & Pathobiology, Temerty Faculty of Medicine, University of Toronto, Toronto, ON, Canada
- Department of Physics, Faculty of Science, Toronto Metropolitan University, Toronto, ON, Canada
- Department of Ophthalmology and Visual Sciences, Faculty of Medicine, University of British Columbia, Vancouver, BC, Canada
| | - Peter Zu Eulenburg
- Institute for Neuroradiology & German Center for Vertigo and Balance Disorders, Ludwig-Maximilians-University, Munich, Germany
| | - Anne Pavy-Le Traon
- Department of Neurology, University Hospital of Toulouse, Toulouse, France
- MEDES, Institute for Space Physiology and Medicine, Toulouse, France
- UMR INSERM U1297, Institute of Cardiovascular and Metabolic Diseases (I2MC), Toulouse, France
| | - Lonnie Grove Petersen
- Department of Aeronautics and Astronautics, Massachusetts Institute of Technology, Cambridge, USA
- Department of Biomedical Sciences, University of Copenhagen, Copenhagen, Denmark
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Ong J, Tarver W, Brunstetter T, Mader TH, Gibson CR, Mason SS, Lee A. Spaceflight associated neuro-ocular syndrome: proposed pathogenesis, terrestrial analogues, and emerging countermeasures. Br J Ophthalmol 2023; 107:895-900. [PMID: 36690421 PMCID: PMC10359702 DOI: 10.1136/bjo-2022-322892] [Citation(s) in RCA: 13] [Impact Index Per Article: 13.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/05/2022] [Accepted: 12/11/2022] [Indexed: 01/25/2023]
Abstract
Spaceflight associated neuro-ocular syndrome (SANS) refers to a distinct constellation of ocular, neurological and neuroimaging findings observed in astronauts during and following long duration spaceflight. These ocular findings, to include optic disc oedema, posterior globe flattening, chorioretinal folds and hyperopic shifts, were first described by NASA in 2011. SANS is a potential risk to astronaut health and will likely require mitigation prior to planetary travel with prolonged exposures to microgravity. While the exact pathogenesis of SANS is not completely understood, several hypotheses have been proposed to explain this neuro-ocular phenomenon. In this paper, we briefly discuss the current hypotheses and contributing factors underlying SANS pathophysiology as well as analogues used to study SANS on Earth. We also review emerging potential countermeasures for SANS including lower body negative pressure, nutritional supplementation and translaminar pressure gradient modulation. Ongoing investigation within these fields will likely be instrumental in preparing and protecting astronaut vision for future spaceflight missions including deep space exploration.
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Affiliation(s)
- Joshua Ong
- Michigan Medicine, University of Michigan, Ann Arbor, Michigan, USA
| | | | | | | | - C Robert Gibson
- KBR, NASA Space Medicine Operations Division, Houston, Texas, USA
- South Shore Eye Center, League City, Texas, USA
| | | | - Andrew Lee
- Department of Ophthalmology, Blanton Eye Institute, Houston Methodist Hospital, Houston, Texas, USA
- Center for Space Medicine, Baylor College of Medicine, Houston, Texas, USA
- The Houston Methodist Research Institute, Houston Methodist Hospital, Houston, Texas, USA
- Departments of Ophthalmology, Neurology, and Neurosurgery, Weill Cornell Medicine, New York, New York, USA
- Department of Ophthalmology, University of Texas Medical Branch, Galveston, Texas, USA
- University of Texas MD Anderson Cancer Center, Houston, Texas, USA
- Texas A&M College of Medicine, Bryan, Texas, USA
- Department of Ophthalmology, The University of Iowa Hospitals and Clinics, Iowa City, Iowa, USA
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9
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Cheng Y, Ren T, Wang N. Biomechanical homeostasis in ocular diseases: A mini-review. Front Public Health 2023; 11:1106728. [PMID: 36733902 PMCID: PMC9886686 DOI: 10.3389/fpubh.2023.1106728] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/24/2022] [Accepted: 01/02/2023] [Indexed: 01/18/2023] Open
Abstract
Diabetes mellitus-induced hyperglycemia is responsible for multiple pathological ocular alternations from vasculopathy to biomechanical dyshomeostasis. Biomechanical homeostasis is crucial to maintain the normal physiological condition of the eyes. Biomechanical features vary in eye tissues regarding different anatomical positions, tissue components, and cellular functions. The disturbance in biomechanical homeostasis may result in different ocular diseases. In this review, we provide a preliminary sketch of the latest evidence on the mechano-environment of the eyeball and its possible influencing factors, thereby underscoring the relationship between the dyshomeostasis of ocular biomechanics and common eye diseases (e.g., diabetic retinopathy, keratoconus, glaucoma, spaceflight-associated neuro-ocular syndrome, retinal vein occlusion and myopia, etc.). Together with the reported evidence, we further discuss and postulate the potential role of biomechanical homeostasis in ophthalmic pathology. Some latest strategies to investigate the biomechanical properties in ocular diseases help unveil the pathological changes at multiple scales, offering references for making new diagnostic and treatment strategies targeting mechanobiology.
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Affiliation(s)
- Ying Cheng
- Beijing Ophthalmology and Visual Sciences Key Laboratory, Beijing Tongren Eye Center, Beijing Institute of Ophthalmology, Beijing Tongren Hospital, Capital Medical University, Beijing, China
| | - Tianmin Ren
- Beijing Ophthalmology and Visual Sciences Key Laboratory, Beijing Tongren Eye Center, Beijing Institute of Ophthalmology, Beijing Tongren Hospital, Capital Medical University, Beijing, China
| | - Ningli Wang
- Beijing Ophthalmology and Visual Sciences Key Laboratory, Beijing Tongren Eye Center, Beijing Institute of Ophthalmology, Beijing Tongren Hospital, Capital Medical University, Beijing, China,Collaborative Innovation Center for Brain Disorders, Beijing Institute of Brain Disorders, Capital Medical University, Beijing, China,Beijing Key Laboratory of Fundamental Research on Biomechanics in Clinical Application, Capital Medical University, Beijing, China,*Correspondence: Ningli Wang ✉
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10
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Griffith JL, Cluff K, Downes GM, Eckerman B, Bhandari S, Loflin BE, Becker R, Alruwaili F, Mohammed N. Wearable Sensing System for NonInvasive Monitoring of Intracranial BioFluid Shifts in Aerospace Applications. SENSORS (BASEL, SWITZERLAND) 2023; 23:985. [PMID: 36679781 PMCID: PMC9860908 DOI: 10.3390/s23020985] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 11/08/2022] [Revised: 12/20/2022] [Accepted: 01/11/2023] [Indexed: 06/17/2023]
Abstract
The alteration of the hydrostatic pressure gradient in the human body has been associated with changes in human physiology, including abnormal blood flow, syncope, and visual impairment. The focus of this study was to evaluate changes in the resonant frequency of a wearable electromagnetic resonant skin patch sensor during simulated physiological changes observed in aerospace applications. Simulated microgravity was induced in eight healthy human participants (n = 8), and the implementation of lower body negative pressure (LBNP) countermeasures was induced in four healthy human participants (n = 4). The average shift in resonant frequency was -13.76 ± 6.49 MHz for simulated microgravity with a shift in intracranial pressure (ICP) of 9.53 ± 1.32 mmHg, and a shift of 8.80 ± 5.2097 MHz for LBNP with a shift in ICP of approximately -5.83 ± 2.76 mmHg. The constructed regression model to explain the variance in shifts in ICP using the shifts in resonant frequency (R2 = 0.97) resulted in a root mean square error of 1.24. This work demonstrates a strong correlation between sensor signal response and shifts in ICP. Furthermore, this study establishes a foundation for future work integrating wearable sensors with alert systems and countermeasure recommendations for pilots and astronauts.
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Affiliation(s)
- Jacob L. Griffith
- Department of Biomedical Engineering, Wichita State University, Wichita, KS 67260, USA
- J. Crayton Pruitt Family Department of Biomedical Engineering, University of Florida, Gainesville, FL 32611, USA
| | - Kim Cluff
- Department of Biomedical Engineering, Wichita State University, Wichita, KS 67260, USA
| | - Grant M. Downes
- Department of Biomedical Engineering, Wichita State University, Wichita, KS 67260, USA
- Pharmaceutical Chemistry, University of Kansas, Lawrence, KS 66045, USA
| | - Brandon Eckerman
- Department of Biomedical Engineering, Wichita State University, Wichita, KS 67260, USA
| | - Subash Bhandari
- Department of Biomedical Engineering, Wichita State University, Wichita, KS 67260, USA
- Meinig School of Biomedical Engineering, Cornell University, Ithaca, NY 14850, USA
| | - Benjamin E. Loflin
- Department of Biomedical Engineering, Wichita State University, Wichita, KS 67260, USA
- Department of Orthopaedic Surgery, Indiana University, Indianapolis, IN 46202, USA
| | - Ryan Becker
- Department of Biomedical Engineering, Wichita State University, Wichita, KS 67260, USA
- Department of Biomedical Engineering, Duke University, Durham, NC 27708, USA
| | - Fayez Alruwaili
- Department of Biomedical Engineering, Wichita State University, Wichita, KS 67260, USA
- Department of Biomedical Engineering, Rowan University, Glassboro, NJ 08028, USA
| | - Noor Mohammed
- Department of Biomedical Engineering, Wichita State University, Wichita, KS 67260, USA
- Department of Electrical and Computer Engineering, University of Massachusetts Amherst, Amherst, MA 01003, USA
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11
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Pramanik J, Kumar A, Panchal L, Prajapati B. Countermeasures for Maintaining Cardiovascular Health in Space Missions. Curr Cardiol Rev 2023; 19:57-67. [PMID: 37005513 PMCID: PMC10518885 DOI: 10.2174/1573403x19666230330083225] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 12/01/2022] [Revised: 01/21/2023] [Accepted: 02/06/2023] [Indexed: 04/04/2023] Open
Abstract
During space exploration, the human body is subjected to altered atmospheric environments and gravity, exposure to radiation, sleep disturbance, and mental pressures; all these factors are responsible for cardiovascular diseases. Under microgravity, the physiological changes related to cardiovascular diseases are the cephalic fluid shift, dramatic reduction in central venous pressure, changes in blood rheology and endothelial function, cerebrovascular abnormalities, headaches, optic disc edema, intracranial hypertension, congestion of the jugular vein, facial swelling, and loss of taste. Generally, five countermeasures are used to maintain cardiovascular health (during and after space missions), including shielding, nutritional, medicinal, exercise, and artificial gravity. This article concludes with how to reduce space missions' impact on cardiovascular health with the help of various countermeasures.
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Affiliation(s)
- Jhilam Pramanik
- Department of Food Technology, ITM University, Gwalior, Madhya Pradesh, India
| | - Akash Kumar
- Department of Food Technology, SRM University, Sonipat, Haryana, India
| | - Lakshay Panchal
- Maharishi Markandeshwar Institute of Physiotherapy and Rehabilitation, Maharishi Markandeshwar University, Mullana, Haryana, India
| | - Bhupendra Prajapati
- Shree S.K. Patel College of Pharmaceutical Education and Research, Ganpat University, India
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12
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Seoane-Viaño I, Ong JJ, Basit AW, Goyanes A. To infinity and beyond: Strategies for fabricating medicines in outer space. Int J Pharm X 2022; 4:100121. [PMID: 35782363 PMCID: PMC9240807 DOI: 10.1016/j.ijpx.2022.100121] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/12/2022] [Revised: 06/08/2022] [Accepted: 06/09/2022] [Indexed: 02/06/2023] Open
Abstract
Recent advancements in next generation spacecrafts have reignited public excitement over life beyond Earth. However, to safeguard the health and safety of humans in the hostile environment of space, innovation in pharmaceutical manufacturing and drug delivery deserves urgent attention. In this review/commentary, the current state of medicines provision in space is explored, accompanied by a forward look on the future of pharmaceutical manufacturing in outer space. The hazards associated with spaceflight, and their corresponding medical problems, are first briefly discussed. Subsequently, the infeasibility of present-day medicines provision systems for supporting deep space exploration is examined. The existing knowledge gaps on the altered clinical effects of medicines in space are evaluated, and suggestions are provided on how clinical trials in space might be conducted. An envisioned model of on-site production and delivery of medicines in space is proposed, referencing emerging technologies (e.g. Chemputing, synthetic biology, and 3D printing) being developed on Earth that may be adapted for extra-terrestrial use. This review concludes with a critical analysis on the regulatory considerations necessary to facilitate the adoption of these technologies and proposes a framework by which these may be enforced. In doing so, this commentary aims to instigate discussions on the pharmaceutical needs of deep space exploration, and strategies on how these may be met. Space is a hostile environment that threatens human health and drug stability. Data on the behaviour of medicines in space is critical but lacking. Novel drug manufacturing and delivery strategies are needed to safeguard crewmembers’ safety. Chemputing, synthetic biology, and 3D printing are examples of such emerging technologies. A regulatory framework for space medicines must be implemented to assure quality.
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Affiliation(s)
- Iria Seoane-Viaño
- Department of Pharmaceutics, UCL School of Pharmacy, University College London, 29-39 Brunswick Square, London WC1N 1AX, UK
- Department of Pharmacology, Pharmacy and Pharmaceutical Technology, Paraquasil Group (GI-2109), Faculty of Pharmacy, Health Research Institute of Santiago de Compostela (IDIS), University of Santiago de Compostela (USC), Santiago de Compostela 15782, Spain
| | - Jun Jie Ong
- Department of Pharmaceutics, UCL School of Pharmacy, University College London, 29-39 Brunswick Square, London WC1N 1AX, UK
| | - Abdul W. Basit
- Department of Pharmaceutics, UCL School of Pharmacy, University College London, 29-39 Brunswick Square, London WC1N 1AX, UK
- FabRx Ltd., 3 Romney Road, Ashford, Kent TN24 0RW, UK
- Corresponding authors at: Department of Pharmaceutics, UCL School of Pharmacy, University College London, 29-39 Brunswick Square, London WC1N 1AX, UK.
| | - Alvaro Goyanes
- Department of Pharmaceutics, UCL School of Pharmacy, University College London, 29-39 Brunswick Square, London WC1N 1AX, UK
- FabRx Ltd., 3 Romney Road, Ashford, Kent TN24 0RW, UK
- Departamento de Farmacología, Farmacia y Tecnología Farmacéutica, I+D Farma Group (GI-1645), Facultad de Farmacia, The Institute of Materials (iMATUS) and Health Research Institute of Santiago de Compostela (IDIS), Universidade de Santiago de Compostela (USC), Santiago de Compostela, 15782, Spain
- Corresponding authors at: Department of Pharmaceutics, UCL School of Pharmacy, University College London, 29-39 Brunswick Square, London WC1N 1AX, UK.
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13
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Jasien JV, Laurie SS, Lee SMC, Martin DS, Kemp DT, Ebert DJ, Ploutz-Snyder R, Marshall-Goebel K, Alferova IV, Sargsyan A, Danielson RW, Hargens AR, Dulchavsky SA, Stenger MB, Macias BR. Noninvasive indicators of intracranial pressure before, during, and after long-duration spaceflight. J Appl Physiol (1985) 2022; 133:721-731. [PMID: 35861522 PMCID: PMC9484990 DOI: 10.1152/japplphysiol.00625.2021] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/02/2021] [Revised: 06/27/2022] [Accepted: 07/18/2022] [Indexed: 11/22/2022] Open
Abstract
Weightlessness induces a cephalad shift of blood and cerebrospinal fluid that may increase intracranial pressure (ICP) during spaceflight, whereas lower body negative pressure (LBNP) may provide an opportunity to caudally redistribute fluids and lower ICP. To investigate the effects of spaceflight and LBNP on noninvasive indicators of ICP (nICP), we studied 13 crewmembers before and after spaceflight in seated, supine, and 15° head-down tilt postures, and at ∼45 and ∼150 days of spaceflight with and without 25 mmHg LBNP. We used four techniques to quantify nICP: cerebral and cochlear fluid pressure (CCFP), otoacoustic emissions (OAE), ultrasound measures of optic nerve sheath diameter (ONSD), and ultrasound-based internal jugular vein pressure (IJVp). On flight day 45, two nICP measures were lower than preflight supine posture [CCFP: mean difference -98.5 -nL (CI: -190.8 to -6.1 -nL), P = 0.037]; [OAE: -19.7° (CI: -10.4° to -29.1°), P < 0.001], but not significantly different from preflight seated measures. Conversely, ONSD was not different than any preflight posture, whereas IJVp was significantly greater than preflight seated measures [14.3 mmHg (CI: 10.1 to 18.5 mmHg), P < 0.001], but not significantly different than preflight supine measures. During spaceflight, acute LBNP application did not cause a significant change in nICP indicators. These data suggest that during spaceflight, nICP is not elevated above values observed in the seated posture on Earth. Invasive measures would be needed to provide absolute ICP values and more precise indications of ICP change during various phases of spaceflight.NEW & NOTEWORTHY The current study provides new evidence that intracranial pressure (ICP), as assessed with noninvasive measures, may not be elevated during long-duration spaceflight. In addition, the acute use of lower body negative pressure did not significantly reduce indicators of ICP during weightlessness.
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Affiliation(s)
| | | | | | | | - David T Kemp
- University College London, London, United Kingdom
| | | | | | | | - Irina V Alferova
- Russian Federation State Research Center Institute of Biomedical Problems, Russian Academy of Sciences, Moscow, Russia
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14
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Holmlund P, Støverud KH, Eklund A. Mathematical modelling of the CSF system: effects of microstructures and posture on optic nerve subarachnoid space dynamics. Fluids Barriers CNS 2022; 19:67. [PMID: 36042452 PMCID: PMC9426285 DOI: 10.1186/s12987-022-00366-4] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/12/2022] [Accepted: 08/18/2022] [Indexed: 11/21/2022] Open
Abstract
Background The pressure difference between the eye and brain in upright postures may be affected by compartmentalization of the optic nerve subarachnoid space (ONSAS). Both pressure and deformation will depend on the microstructures of the ONSAS, and most likely also on ocular glymphatic clearance. Studying these factors could yield important knowledge regarding the translaminar pressure difference, which is suspected to play a role in normal-tension glaucoma. Methods A compartment model coupling the ONSAS with the craniospinal CSF system was used to investigate the effects of microstructures on the pressure transfer through the ONSAS during a posture change from supine to upright body postures. ONSAS distensibility was based on MRI measurements. We also included ocular glymphatic flow to investigate how local pressure gradients alter this flow with changes in posture. Results A compartmentalization of the ONSAS occurred in the upright posture, with ONSAS porosity (degree of microstructural content) affecting the ONSAS pressure (varying the supine/baseline porosity from 1.0 to 0.75 yielded pressures between − 5.3 and − 2 mmHg). Restricting the minimum computed porosity (occurring in upright postures) to 0.3 prevented compartmentalization, and the ONSAS pressure could equilibrate with subarachnoid space pressure (− 6.5 mmHg) in \documentclass[12pt]{minimal}
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\begin{document}$$\le$$\end{document}≤ 1 h. The ocular glymphatics analysis predicted that substantial intraocular-CSF flows could occur without substantial changes in the ONSAS pressure. The flow entering the ONSAS in supine position (both from the intraocular system and from the cranial subarachnoid space) exited the ONSAS through the optic nerve sheath, while in upright postures the flow through the ONSAS was redirected towards the cranial subarachnoid space. Conclusions Microstructures affect pressure transmission along the ONSAS, potentially contributing to ONSAS compartmentalization in upright postures. Different pathways for ocular glymphatic flow were predicted for different postures.
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Affiliation(s)
- Petter Holmlund
- Department of Radiation Sciences, Radiation Physics, Biomedical Engineering, Umeå University, 901 87, Umeå, Sweden.
| | - Karen-Helene Støverud
- Department of Radiation Sciences, Radiation Physics, Biomedical Engineering, Umeå University, 901 87, Umeå, Sweden.,Department of Health Research, SINTEF Digital, Trondheim, Norway
| | - Anders Eklund
- Department of Radiation Sciences, Radiation Physics, Biomedical Engineering, Umeå University, 901 87, Umeå, Sweden.,Umeå Center for Functional Brain Imaging, Umeå University, 901 87, Umeå, Sweden
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15
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Zhang X, Zhang S, Wang T. How the mechanical microenvironment of stem cell growth affects their differentiation: a review. Stem Cell Res Ther 2022; 13:415. [PMID: 35964140 PMCID: PMC9375355 DOI: 10.1186/s13287-022-03070-0] [Citation(s) in RCA: 17] [Impact Index Per Article: 8.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/08/2022] [Accepted: 07/20/2022] [Indexed: 12/18/2022] Open
Abstract
Stem cell differentiation is of great interest in medical research; however, specifically and effectively regulating stem cell differentiation is still a challenge. In addition to chemical factors, physical signals are an important component of the stem cell ecotone. The mechanical microenvironment of stem cells has a huge role in stem cell differentiation. Herein, we describe the knowledge accumulated to date on the mechanical environment in which stem cells exist, which consists of various factors, including the extracellular matrix and topology, substrate stiffness, shear stress, hydrostatic pressure, tension, and microgravity. We then detail the currently known signalling pathways that stem cells use to perceive the mechanical environment, including those involving nuclear factor-kB, the nicotinic acetylcholine receptor, the piezoelectric mechanosensitive ion channel, and hypoxia-inducible factor 1α. Using this information in clinical settings to treat diseases is the goal of this research, and we describe the progress that has been made. In this review, we examined the effects of mechanical factors in the stem cell growth microenvironment on stem cell differentiation, how mechanical signals are transmitted to and function within the cell, and the influence of mechanical factors on the use of stem cells in clinical applications.
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Affiliation(s)
- Xiaofang Zhang
- Department of Radiotherapy, Cancer Hospital of China Medical University, Liaoning Cancer Hospital and Institute, Shenyang, China
| | - Sibo Zhang
- China Medical University, Shenyang, China
| | - Tianlu Wang
- Department of Radiotherapy, Cancer Hospital of China Medical University, Liaoning Cancer Hospital and Institute, Shenyang, China.
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16
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Whittle RS, Keller N, Hall EA, Vellore HS, Stapleton LM, Findlay KH, Dunbar BJ, Diaz‐Artiles A. Gravitational Dose‐Response Curves for Acute Cardiovascular Hemodynamics and Autonomic Responses in a Tilt Paradigm. J Am Heart Assoc 2022; 11:e024175. [PMID: 35861832 PMCID: PMC9707822 DOI: 10.1161/jaha.121.024175] [Citation(s) in RCA: 7] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Abstract
Background
The cardiovascular system is strongly dependent on the gravitational environment. Gravitational changes cause mechanical fluid shifts and, in turn, autonomic effectors influence systemic circulation and cardiac control. We implemented a tilt paradigm to (1) investigate the acute hemodynamic response across a range of directions of the gravitational vector, and (2) to generate specific dose‐response relationships of this gravitational dependency.
Methods and Results
Twelve male subjects were tilted from 45° head‐up tilt to 45° head‐down tilt in 15° increments, in both supine and prone postures. We measured the steady‐state hemodynamic response in a range of variables including heart rate, stroke volume, cardiac output, oxygen consumption, total peripheral resistance, blood pressure, and autonomic indices derived from heart rate variability analysis. There is a strong gravitational dependence in almost all variables considered, with the exception of oxygen consumption, whereas systolic blood pressure remained controlled to within ≈3% across the tilt range. Hemodynamic responses are primarily driven by differential loading on the baroreflex receptors, combined with differences in venous return to the heart. Thorax compression in the prone position leads to reduced venous return and increased sympathetic nervous activity, raising heart rate, and systemic vascular resistance while lowering cardiac output and stroke volume.
Conclusions
Gravitational dose‐response curves generated from these data provide a comprehensive baseline from which to assess the efficacy of potential spaceflight countermeasures. Results also assist clinical management of terrestrial surgery in prone posture or head‐down tilt positions.
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Affiliation(s)
- Richard S. Whittle
- Department of Aerospace Engineering Texas A&M University College Station TX
| | - Nathan Keller
- Department of Health and Kinesiology Texas A&M University College Station TX
| | - Eric A. Hall
- Department of Biomedical Engineering Texas A&M University College Station TX
| | | | | | | | - Bonnie J. Dunbar
- Department of Aerospace Engineering Texas A&M University College Station TX
| | - Ana Diaz‐Artiles
- Department of Aerospace Engineering Texas A&M University College Station TX
- Department of Health and Kinesiology Texas A&M University College Station TX
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17
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Kato T, Kurazumi T, Konishi T, Takko C, Ogawa Y, Iwasaki KI. Effects of -10° and -30° head-down tilt on cerebral blood velocity, dynamic cerebral autoregulation and non-invasively estimated intracranial pressure. J Appl Physiol (1985) 2022; 132:938-946. [PMID: 35201934 PMCID: PMC8993530 DOI: 10.1152/japplphysiol.00283.2021] [Citation(s) in RCA: 5] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/03/2022] Open
Abstract
Steady-state cerebral blood flow (CBF) and dynamic cerebral autoregulation are reportedly maintained during −10° head-down tilt (HDT) despite slight increases in intracranial pressure (ICP). However, the higher ICP during −30° HDT may alter steady-state CBF and dynamic cerebral autoregulation. The present study hypothesized that steady-state CBF and dynamic cerebral autoregulation would be altered by higher ICP during −30° HDT than during 0° and −10° HDT. Seventeen healthy participants were positioned horizontal (0°) and in −10° HDT and −30° HDT for 10 min in random order on separate days. The arterial blood pressure waveform was obtained using a finger blood pressure device and the cerebral blood velocity waveform in the middle cerebral artery was obtained using transcranial Doppler sonography (TCD) for the last 6 min in each position. ICP was estimated using noninvasive ICP (nICP) based on TCD. Dynamic cerebral autoregulation was evaluated by spectral and transfer function analysis. Although nICP was significantly higher during −30° HDT (12.4 mmHg) than during −10° HDT (8.9 mmHg), no significant differences in steady-state mean cerebral blood velocity or transfer function gain in any frequency ranges were seen among all angles of HDT. Counter to our hypothesis, the present results suggest that steady-state CBF and dynamic cerebral autoregulation may be preserved during short-term −30° HDT despite the higher ICP compared with that during −10° HDT. NEW & NOTEWORTHY This appears to be the first study to evaluate steady-state cerebral blood flow (CBF), dynamic cerebral autoregulation, and intracranial pressure (ICP) during −30° head-down tilt (HDT) compared with those during −10° HDT using noninvasive measurements. The results suggest that steady-state CBF and dynamic cerebral autoregulation are preserved despite the higher ICP during short-term −30° HDT compared with −10° HDT.
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Affiliation(s)
- Tomokazu Kato
- Department of Social Medicine, Division of Hygiene, Nihon University School of Medicine, Itabashi, Tokyo, Japan
| | - Takuya Kurazumi
- Department of Social Medicine, Division of Hygiene, Nihon University School of Medicine, Itabashi, Tokyo, Japan.,Institute for Exercise and Environmental Medicine, Texas Health Presbyterian Hospital Dallas, Dallas, Texas, United States.,Department of Neurology, University of Texas Southwestern Medical Center, Dallas, Dallas, Texas, United States
| | - Toru Konishi
- Department of Social Medicine, Division of Hygiene, Nihon University School of Medicine, Itabashi, Tokyo, Japan.,Air Staff Office, Japan Air Self-Defense Force, Tokyo, Japan
| | - Chiharu Takko
- Department of Social Medicine, Division of Hygiene, Nihon University School of Medicine, Itabashi, Tokyo, Japan
| | - Yojiro Ogawa
- Department of Social Medicine, Division of Hygiene, Nihon University School of Medicine, Itabashi, Tokyo, Japan
| | - Ken-Ichi Iwasaki
- Department of Social Medicine, Division of Hygiene, Nihon University School of Medicine, Itabashi, Tokyo, Japan
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18
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Liu HY, Zhao CH, Zhang H, Wang W, Liu QJ. Simulation study on the effect of resistance exercise on the hydrodynamic microenvironment of osteocytes in microgravity. Comput Methods Biomech Biomed Engin 2022; 25:1757-1766. [PMID: 35170387 DOI: 10.1080/10255842.2022.2037130] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/03/2022]
Abstract
Osteoporosis occurs in astronauts after long-term space flight owing to the lack of gravity. The mechanical microenvironment of osteocytes in load-bearing bone are changed during resistance exercise, which prevents massive bone loss in the human body. A cylindrical fluid-structure coupling finite element model for osteons with a two-stage pore structure (i.e., Haversian canal, lacunar-canalicular system) was established with the software COMSOL. In the Earth's gravity field and in microgravity, considering the effects of pulsating pressure of arterioles, a comparative study was performed on the changes in hydrodynamic microenvironment of osteocytes during human body high-intensity exercise at different frequencies (defined as causing bone to produce 3000 με) and the body is at rest. Positive and negative liquid pressure (with respect to one atmosphere pressure) alternately acted on osteocytes during human exercising, but only positive pressure acted on osteocytes during human resting. The variation range of liquid pressure acted on osteocytes during human exercising was significantly higher than that during resting. The liquid flow velocity around osteocytes during body exercise was about four orders of magnitude higher than that during resting. In microgravity, moderate physical exercise can obviously improve the hydrodynamic microenvironment of osteocytes in load-bearing bone, which could compensate for the lack of mechanical stimulation to osteocytes caused by the lack of gravity, thereby promoting the normal physiological function of osteocytes. To a certain extent, these results revealed the biomechanical mechanism by which exercise has an effect in fighting osteoporosis in astronauts.
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Affiliation(s)
- Hai-Ying Liu
- Tianjin Key Laboratory for Advanced Mechatronic System Design and Intelligent Control, School of Mechanical Engineering, Tianjin University of Technology, Tianjin, People's Republic of China.,National Demonstration Center for Experimental Mechanical and Electrical Engineering Education (Tianjin University of Technology), Tianjin, People's Republic of China
| | - Chao-Hui Zhao
- Tianjin Key Laboratory for Advanced Mechatronic System Design and Intelligent Control, School of Mechanical Engineering, Tianjin University of Technology, Tianjin, People's Republic of China.,National Demonstration Center for Experimental Mechanical and Electrical Engineering Education (Tianjin University of Technology), Tianjin, People's Republic of China
| | - Hao Zhang
- Tianjin Key Laboratory for Advanced Mechatronic System Design and Intelligent Control, School of Mechanical Engineering, Tianjin University of Technology, Tianjin, People's Republic of China.,National Demonstration Center for Experimental Mechanical and Electrical Engineering Education (Tianjin University of Technology), Tianjin, People's Republic of China
| | - Wei Wang
- Department of Mechanics, School of Mechanical Engineering, Tianjin University, Tianjin, People's Republic of China
| | - Qing-Jian Liu
- Tianjin Key Laboratory for Advanced Mechatronic System Design and Intelligent Control, School of Mechanical Engineering, Tianjin University of Technology, Tianjin, People's Republic of China.,National Demonstration Center for Experimental Mechanical and Electrical Engineering Education (Tianjin University of Technology), Tianjin, People's Republic of China
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19
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Jirak P, Mirna M, Rezar R, Motloch LJ, Lichtenauer M, Jordan J, Binneboessel S, Tank J, Limper U, Jung C. How spaceflight challenges human cardiovascular health. Eur J Prev Cardiol 2022; 29:1399-1411. [PMID: 35148376 DOI: 10.1093/eurjpc/zwac029] [Citation(s) in RCA: 12] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 10/12/2021] [Revised: 01/08/2022] [Accepted: 02/06/2022] [Indexed: 11/14/2022]
Abstract
The harsh environmental conditions in space, particularly weightlessness and radiation exposure, can negatively affect cardiovascular function and structure. In the future, preventive cardiology will be crucial in enabling safe space travel. Indeed, future space missions destined to the Moon and from there to Mars will create new challenges to cardiovascular health while limiting medical management. Moreover, commercial spaceflight evolves rapidly such that older persons with cardiovascular risk factors will be exposed to space conditions. This review provides an overview on studies conducted in space and in terrestrial models, particularly head-down bedrest studies. These studies showed that weightlessness elicits a fluid shift towards the head, which likely predisposes to the spaceflight-associated neuro-ocular syndrome, neck vein thrombosis, and orthostatic intolerance after return to Earth. Moreover, cardiovascular unloading produces cardiopulmonary deconditioning which may be associated with cardiac atrophy. In addition to limiting physical performance, the mechanism further worsens orthostatic tolerance after return to Earth. Finally, space conditions may directly affect vascular health, however, the clinical relevance of these findings in terms of morbidity and mortality is unknown. Targeted preventive measures, which are referred to as countermeasures in aerospace medicine, and technologies to identify vascular risks early on will be required to maintain cardiovascular performance and health during future space missions.
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Affiliation(s)
- Peter Jirak
- Clinic II for Internal Medicine, University Hospital Salzburg, Paracelsus Medical University, 5020 Salzburg, Austria
| | - Moritz Mirna
- Clinic II for Internal Medicine, University Hospital Salzburg, Paracelsus Medical University, 5020 Salzburg, Austria
| | - Richard Rezar
- Clinic II for Internal Medicine, University Hospital Salzburg, Paracelsus Medical University, 5020 Salzburg, Austria
| | - Lukas J Motloch
- Clinic II for Internal Medicine, University Hospital Salzburg, Paracelsus Medical University, 5020 Salzburg, Austria
| | - Michael Lichtenauer
- Clinic II for Internal Medicine, University Hospital Salzburg, Paracelsus Medical University, 5020 Salzburg, Austria
| | - Jens Jordan
- Institute of Aerospace Medicine, German Aerospace Center, Cologne, Germany.,Medical Faculty, University of Cologne, Germany
| | - Stephan Binneboessel
- Division of Cardiology, Pulmonology, and Vascular Medicine, Medical Faculty, University Duesseldorf, Germany
| | - Jens Tank
- Institute of Aerospace Medicine, German Aerospace Center, Cologne, Germany
| | - Ulrich Limper
- Institute of Aerospace Medicine, German Aerospace Center, Cologne, Germany.,Department of Anaesthesiology and Critical Care Medicine, Merheim Medical Center, Witten/Herdecke University, Cologne, Germany
| | - Christian Jung
- Division of Cardiology, Pulmonology, and Vascular Medicine, Medical Faculty, University Duesseldorf, Germany
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20
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Kramer LA, Hasan KM, Gabr RE, Macias BR, Marshall-Goebel K, Laurie SS, Hargens AR. Cerebrovascular Effects of Lower Body Negative Pressure at 3T MRI: Implications for Long-Duration Space Travel. J Magn Reson Imaging 2022; 56:873-881. [PMID: 35119781 DOI: 10.1002/jmri.28102] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/10/2021] [Revised: 01/24/2022] [Accepted: 01/25/2022] [Indexed: 12/16/2022] Open
Abstract
BACKGROUND Optic disc edema develops in most astronauts during long-duration spaceflight. It is hypothesized to result from weightlessness-induced venous congestion of the head and neck and is an unresolved health risk of space travel. PURPOSE Determine if short-term application of lower body negative pressure (LBNP) could reduce internal jugular vein (IJV) expansion associated with the supine posture without negatively impacting cerebral perfusion or causing IJV flow stasis. STUDY TYPE Prospective. SUBJECTS Nine healthy volunteers (six women). FIELD STRENGTH/SEQUENCE 3T/cine two-dimensional phase-contrast gradient echo; pseudo-continuous arterial spin labeling single-shot gradient echo echo-planar. ASSESSMENT The study was performed with two sequential conditions in randomized order: supine posture and supine posture with 25 mmHg LBNP (LBNP25 ). LBNP was achieved by enclosing the lower extremities in a semi-airtight acrylic chamber connected to a vacuum. Heart rate, bulk cerebrovasculature flow, IJV cross-sectional area, fractional IJV outflow relative to arterial inflow, and cerebral perfusion were assessed in each condition. STATISTICAL TESTS Paired t-tests were used to compare measurement means across conditions. Significance was defined as P < 0.05. RESULTS LBNP25 significantly increased heart rate from 64 ± 9 to 71 ± 8 beats per minute and significantly decreased IJV cross-sectional area, IJV outflow fraction, cerebral arterial flow rate, and cerebral arterial stroke volume from 1.28 ± 0.64 to 0.56 ± 0.31 cm2 , 0.75 ± 0.20 to 0.66 ± 0.28, 780 ± 154 to 708 ± 137 mL/min and 12.2 ± 2.8 to 9.7 ± 1.7 mL/cycle, respectively. During LBNP25 , there was no significant change in gray or white matter cerebral perfusion (P = 0.26 and P = 0.24 respectively) and IJV absolute mean peak flow velocity remained ≥4 cm/sec in all subjects. DATA CONCLUSION Short-term application of LBNP25 reduced IJV expansion without decreasing cerebral perfusion or inducing IJV flow stasis. LEVEL OF EVIDENCE 1 TECHNICAL EFFICACY STAGE: 1.
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Affiliation(s)
- Larry A Kramer
- Department of Diagnostic and Interventional Imaging, University of Texas Health Science Center at Houston, McGovern Medical School, Houston, Texas, USA
| | - Khader M Hasan
- Department of Diagnostic and Interventional Imaging, University of Texas Health Science Center at Houston, McGovern Medical School, Houston, Texas, USA
| | - Refaat E Gabr
- Department of Diagnostic and Interventional Imaging, University of Texas Health Science Center at Houston, McGovern Medical School, Houston, Texas, USA
| | - Brandon R Macias
- Cardiovascular and Vision Laboratory, NASA Johnson Space Center, Houston, Texas, USA
| | | | | | - Alan R Hargens
- Department of Orthopedic Surgery, University of California San Diego, La Jolla, California, USA
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21
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Harris KM, Weber T, Greaves D, Green DA, Goswami N, Petersen LG. Going against the flow: are venous thromboembolism and impaired cerebral drainage critical risks for spaceflight? J Appl Physiol (1985) 2022; 132:270-273. [PMID: 34672768 PMCID: PMC8759966 DOI: 10.1152/japplphysiol.00425.2021] [Citation(s) in RCA: 6] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/03/2023] Open
Affiliation(s)
- Katie M. Harris
- 1Faculty of Medicine, Memorial University of Newfoundland, St. John’s, Newfoundland and Labrador, Canada
| | - Tobias Weber
- 2European Astronaut Centre, European Space Agency, Space Medicine Team (HRE-OM), Cologne, Germany,3KBR GmbH, Cologne, Germany
| | - Danielle Greaves
- 4Department of Kinesiology and Health Sciences, Faculty of Health, University of Waterloo, Waterloo, Ontario, Canada
| | - David Andrew Green
- 2European Astronaut Centre, European Space Agency, Space Medicine Team (HRE-OM), Cologne, Germany,3KBR GmbH, Cologne, Germany,5Centre of Human & Applied Physiological Sciences, King’s College London, London, United Kingdom
| | - Nandu Goswami
- 6Division of Physiology, Otto Löwi Research Center for Vascular Biology, Immunity and Inflammation, Medical University of Graz, Graz, Austria
| | - Lonnie G. Petersen
- 7Department of Mechanical and Aerospace Engineering, University of California, San Diego, California,8Department of Radiology, University of California, San Diego, California
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22
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Hearon CM, Dias KA, Babu G, Marshall JET, Leidner J, Peters K, Silva E, MacNamara JP, Campain J, Levine BD. Effect of Nightly Lower Body Negative Pressure on Choroid Engorgement in a Model of Spaceflight-Associated Neuro-ocular Syndrome: A Randomized Crossover Trial. JAMA Ophthalmol 2021; 140:59-65. [PMID: 34882176 DOI: 10.1001/jamaophthalmol.2021.5200] [Citation(s) in RCA: 6] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/29/2022]
Abstract
Importance Astronauts returning from long-duration spaceflight experience ocular remodeling related to cephalad fluid shifts induced by microgravity. It is hypothesized that the absence of diurnal reductions in intracranial pressure in microgravity creates a low but persistent pressure gradient at the posterior aspect of the eye, which results in ocular remodeling and space-associated neuro-ocular syndrome (SANS) over many months. Objective To determine whether partial reintroduction of footward fluid shifts during simulated microgravity via lower body negative pressure (LBNP) during sleep attenuates choroid engorgement, an early marker of ocular remodeling related to SANS. Design, Setting, and Participants Between May 2019 and February 2020, participants with no major cardiovascular, kidney, or ophthalmic disease completed 3 days of supine (0°) bed rest with and 3 days without 8 hours of nightly LBNP in a randomized, crossover design. This single-center investigation took place at the UT Southwestern Medical Center. All analyses were conducted blinded to condition and time point. Interventions Eight hours of nightly LBNP (-20 mm Hg) vs no LBNP. Main Outcomes and Measures The primary outcome was the change in choroid area and volume after 3 days of bed rest measured by optical coherence tomography. Results Of 10 participants, 5 were female, the mean (SD) age was 29 (9) years, and the age range was 18 to 55 years. Central venous pressure increased from the seated to supine position (mean [SD], seated: -2.3 [2.0] vs supine: 6.9 [2.0] mm Hg; P < .001), leading to choroid engorgement over 3 days of bed rest (Δ area: +0.09 mm2 [95% CI, 0.04-0.13]; P = .001; Δ volume: +0.37 mm3 [95% CI, 0.19-0.55]; P = .001). Nightly LBNP caused a sustained reduction in supine central venous pressure (mean [SD], 5.7 [2.2] mm Hg to 1.2 [1.4 mm Hg]; P < .001) and attenuated the increase in choroid area (74%) (Δ: 0.02 mm2 [95% -0.02 to 0.06]; P = .01) and volume (53%) (Δ: 0.17 mm3 [95% CI, 0.01-0.34]; P = .05) compared with control. Conclusions and Relevance Nightly LBNP reinstated a footward fluid shift and mitigated the increase in choroid area and volume. LBNP during sleep may be an effective countermeasure for ocular remodeling and SANS during long-duration space missions.
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Affiliation(s)
- Christopher M Hearon
- Institute for Exercise and Environmental Medicine, Texas Health Presbyterian Hospital Dallas, Dallas.,University of Texas Southwestern Medical Center, Dallas
| | - Katrin A Dias
- Institute for Exercise and Environmental Medicine, Texas Health Presbyterian Hospital Dallas, Dallas.,University of Texas Southwestern Medical Center, Dallas
| | - Gautam Babu
- University of Texas Southwestern Medical Center, Dallas
| | | | - James Leidner
- Internal Medicine, Texas Health Presbyterian Hospital Dallas, Dallas
| | - Kirsten Peters
- University Medical Center, Radboud University, Nijmegen, the Netherlands
| | - Erika Silva
- Institute for Exercise and Environmental Medicine, Texas Health Presbyterian Hospital Dallas, Dallas
| | - James P MacNamara
- Institute for Exercise and Environmental Medicine, Texas Health Presbyterian Hospital Dallas, Dallas.,University of Texas Southwestern Medical Center, Dallas
| | | | - Benjamin D Levine
- Institute for Exercise and Environmental Medicine, Texas Health Presbyterian Hospital Dallas, Dallas.,University of Texas Southwestern Medical Center, Dallas
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23
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Koep JL, Taylor CE, Coombes JS, Bond B, Ainslie PN, Bailey TG. Autonomic control of cerebral blood flow: fundamental comparisons between peripheral and cerebrovascular circulations in humans. J Physiol 2021; 600:15-39. [PMID: 34842285 DOI: 10.1113/jp281058] [Citation(s) in RCA: 17] [Impact Index Per Article: 5.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/28/2021] [Accepted: 11/25/2021] [Indexed: 01/12/2023] Open
Abstract
Understanding the contribution of the autonomic nervous system to cerebral blood flow (CBF) control is challenging, and interpretations are unclear. The identification of calcium channels and adrenoreceptors within cerebral vessels has led to common misconceptions that the function of these receptors and actions mirror those of the peripheral vasculature. This review outlines the fundamental differences and complex actions of cerebral autonomic activation compared with the peripheral circulation. Anatomical differences, including the closed nature of the cerebrovasculature, and differential adrenoreceptor subtypes, density, distribution and sensitivity, provide evidence that measures on peripheral sympathetic nerve activity cannot be extrapolated to the cerebrovasculature. Cerebral sympathetic nerve activity seems to act opposingly to the peripheral circulation, mediated at least in part by changes in intracranial pressure and cerebral blood volume. Additionally, heterogeneity in cerebral adrenoreceptor distribution highlights region-specific autonomic regulation of CBF. Compensatory chemo- and autoregulatory responses throughout the cerebral circulation, and interactions with parasympathetic nerve activity are unique features to the cerebral circulation. This crosstalk between sympathetic and parasympathetic reflexes acts to ensure adequate perfusion of CBF to rising and falling perfusion pressures, optimizing delivery of oxygen and nutrients to the brain, while attempting to maintain blood volume and intracranial pressure. Herein, we highlight the distinct similarities and differences between autonomic control of cerebral and peripheral blood flow, and the regional specificity of sympathetic and parasympathetic regulation within the cerebrovasculature. Future research directions are outlined with the goal to further our understanding of autonomic control of CBF in humans.
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Affiliation(s)
- Jodie L Koep
- Physiology and Ultrasound Laboratory in Science and Exercise, Centre for Research on Exercise, Physical Activity and Health, School of Human Movement and Nutrition Sciences, The University of Queensland, Brisbane, Queensland, Australia.,Children's Health and Exercise Research Centre, Sport and Health Sciences, College of Life and Environmental Sciences, University of Exeter, Exeter, UK
| | - Chloe E Taylor
- School of Health Sciences, Western Sydney University, Sydney, Australia
| | - Jeff S Coombes
- Physiology and Ultrasound Laboratory in Science and Exercise, Centre for Research on Exercise, Physical Activity and Health, School of Human Movement and Nutrition Sciences, The University of Queensland, Brisbane, Queensland, Australia
| | - Bert Bond
- Children's Health and Exercise Research Centre, Sport and Health Sciences, College of Life and Environmental Sciences, University of Exeter, Exeter, UK
| | - 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
| | - Tom G Bailey
- Physiology and Ultrasound Laboratory in Science and Exercise, Centre for Research on Exercise, Physical Activity and Health, School of Human Movement and Nutrition Sciences, The University of Queensland, Brisbane, Queensland, Australia.,School of Nursing, Midwifery and Social Work, The University of Queensland, Brisbane, Queensland, Australia
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24
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Convertino VA, Cardin S, Cap AP, Crowder AT, Stackle ME, Talley MJ, Lurie KG. Saving the brain after mild-to-moderate traumatic injury: A report on new insights of the physiology underlying adequate maintenance of cerebral perfusion. J Trauma Acute Care Surg 2021; 91:S33-S39. [PMID: 34039933 DOI: 10.1097/ta.0000000000003286] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/25/2022]
Abstract
ABSTRACT Traumatic brain injury (TBI) is associated with increased morbidity and mortality in civilian trauma and battlefield settings. It has been classified across a continuum of dysfunctions, with as much as 80% to 90% of cases diagnosed as mild to moderate in combat casualties. In this report, a framework is presented that focuses on the potential benefits for acute noninvasive treatment of reduced cerebral perfusion associated with mild TBI by harnessing the natural transfer of negative intrathoracic pressure during inspiration. This process is known as intrathoracic pressure regulation (IPR) therapy, which can be applied by having a patient breath against a small inspiratory resistance created by an impedance threshold device. Intrathoracic pressure regulation therapy leverages two fundamental principles for improving blood flow to the brain: (1) greater negative intrathoracic pressure enhances venous return, cardiac output, and arterial blood pressure; and (2) lowering of intracranial pressure provides less resistance to cerebral blood flow. These two effects work together to produce a greater pressure gradient that results in an improvement in cerebral perfusion pressure. In this way, IPR therapy has the potential to counter hypotension and hypoxia, potentially significant contributing factors to secondary brain injury, particularly in conditions of multiple injuries that include severe hemorrhage. By implementing IPR therapy in patients with mild-to-moderate TBI, a potential exists to provide early neuroprotection at the point of injury and a bridge to more definitive care, particularly in settings of prolonged delays in evacuation such as those anticipated in future multidomain operations. LEVEL OF EVIDENCE Report.
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Affiliation(s)
- Victor A Convertino
- From the US Army Institute of Surgical Research (V.A.C., A.P.C., A.T.C., M.E.S.); Naval Medical Research Unit-San Antonio (S.C.), Joint Base San Antonio-Fort Sam Houston, Texas; US Army Medical Research and Development Command (M.J.T.), Fort Detrick, Maryland; and Department of Emergency Medicine (K.G.L.), University of Minnesota, Minneapolis, Minnesota
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25
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Arbeille P, Zuj KA, Macias BR, Ebert DJ, Laurie SS, Sargsyan AE, Martin DS, Lee SMC, Dulchavsky SA, Stenger MB, Hargens AR. Lower body negative pressure reduces jugular and portal vein volumes and counteracts the elevation of middle cerebral vein velocity during long-duration spaceflight. J Appl Physiol (1985) 2021; 131:1080-1087. [PMID: 34323592 DOI: 10.1152/japplphysiol.00231.2021] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
Cephalad fluid shifts in space have been hypothesized to cause the spaceflight-associated neuro-ocular syndrome (SANS) by increasing the intracranial-ocular translaminal pressure gradient. Lower body negative pressure (LBNP) can be used to shift upper-body blood and other fluids toward the legs during spaceflight. We hypothesized that microgravity would increase jugular vein volume (JVvol), portal vein cross-sectional area (PV), and intracranial venous blood velocity (MCV) and that LBNP application would return these variables toward preflight levels. Data were collected from 14 subjects (11 males) before and during long-duration International Space Station (ISS) spaceflights. Ultrasound measures of JVvol, PV, and MCV were acquired while seated and supine before flight and early during spaceflight at day 45 (FD45) and late at day 150 (FD150) with and without LBNP. JVvol increased from preflight supine and seated postures (46 ± 48% and 646 ± 595% on FD45 and 43 ± 43% and 702 ± 631% on FD150, P < 0.05), MCV increased from preflight supine (44 ± 31% on FD45 and 115 ± 116% on FD150, P < 0.05), and PV increased from preflight supine and seated (51 ± 56% on FD45 and 100 ± 74% on FD150, P < 0.05). Inflight LBNP of -25 mmHg restored JVvol and MCV to preflight supine level and PV to preflight seated level. Elevated JVvol confirms the sustained neck-head blood engorgement inflight, whereas increased PV area supports the fluid shift at the splanchnic level. Also, MCV increased potentially due to reduced lumen diameter. LBNP, returning variables to preflight levels, may be an effective countermeasure.NEW & NOTEWORTHY Microgravity-induced fluid shifts markedly enlarge jugular and portal veins and increase cerebral vein velocity. These findings demonstrate a marked flow engorgement at neck and splanchnic levels and may suggest compression of the cerebral veins by the brain tissue in space. LBNP (-25 mmHg for 30 min) returns these changes to preflight levels and, thus, reduces the associated flow and tissue disturbances.
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Affiliation(s)
- P Arbeille
- UMPS-CERCOM, University School of Medicine, Tours, France
| | - K A Zuj
- UMPS-CERCOM, University School of Medicine, Tours, France
| | - B R Macias
- NASA Johnson Space Center, Houston, Texas
| | | | | | | | | | | | | | | | - A R Hargens
- Department of Orthopedic Surgery, UCSD Medical Center, San Diego, California
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26
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Sater SH, Sass AM, Seiner A, Natividad GC, Shrestha D, Fu AQ, Oshinski JN, Ethier CR, Martin BA. MRI-based quantification of ophthalmic changes in healthy volunteers during acute 15° head-down tilt as an analogue to microgravity. J R Soc Interface 2021; 18:20200920. [PMID: 33906382 DOI: 10.1098/rsif.2020.0920] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/17/2023] Open
Abstract
Spaceflight is known to cause ophthalmic changes in a condition known as spaceflight-associated neuro-ocular syndrome (SANS). It is hypothesized that SANS is caused by cephalad fluid shifts and potentially mild elevation of intracranial pressure (ICP) in microgravity. Head-down tilt (HDT) studies are a ground-based spaceflight analogue to create cephalad fluid shifts. Here, we developed non-invasive magnetic resonance imaging (MRI)-based techniques to quantify ophthalmic structural changes under acute 15° HDT. We specifically quantified: (i) change in optic nerve sheath (ONS) and optic nerve (ON) cross-sectional area, (ii) change in ON deviation, an indicator of ON tortuosity, (iii) change in vitreous chamber depth, and (iv) an estimated ONS Young's modulus. Under acute HDT, ONS cross-sectional area increased by 4.04 mm2 (95% CI 2.88-5.21 mm2, p < 0. 000), while ON cross-sectional area remained nearly unchanged (95% CI -0.12 to 0.43 mm2, p = 0.271). ON deviation increased under HDT by 0.20 mm (95% CI 0.08-0.33 mm, p = 0.002). Vitreous chamber depth decreased under HDT by -0.11 mm (95% CI -0.21 to -0.03 mm, p = 0.009). ONS Young's modulus was estimated to be 85.0 kPa. We observed a significant effect of sex and BMI on ONS parameters, of interest since they are known risk factors for idiopathic intracranial hypertension. The tools developed herein will be useful for future analyses of ON changes in various conditions.
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Affiliation(s)
- Stuart H Sater
- Alcyone Therapeutics Inc., Lowell, MA 01852, USA.,Department of Chemical and Biological Engineering, University of Idaho, 875 Perimeter Drive, MC1122, Moscow, ID 83844-1122, USA
| | - Austin M Sass
- Department of Chemical and Biological Engineering, University of Idaho, 875 Perimeter Drive, MC1122, Moscow, ID 83844-1122, USA
| | - Akari Seiner
- Department of Chemical and Biological Engineering, University of Idaho, 875 Perimeter Drive, MC1122, Moscow, ID 83844-1122, USA
| | - Gabryel Conley Natividad
- Department of Chemical and Biological Engineering, University of Idaho, 875 Perimeter Drive, MC1122, Moscow, ID 83844-1122, USA
| | - Dev Shrestha
- Department of Chemical and Biological Engineering, University of Idaho, 875 Perimeter Drive, MC1122, Moscow, ID 83844-1122, USA
| | - Audrey Q Fu
- Department of Mathematics and Statistical Science, Institute of Bioinformatics and Evolutionary Studies, Institute for Modeling Collaboration and Innovation, University of Idaho, 875 Perimeter Drive, MC1122, Moscow, ID 83844-1122, USA
| | - John N Oshinski
- Department of Radiology and Imaging Sciences, Emory University, Atlanta, GA, USA.,Wallace H. Coulter Department of Biomedical Engineering, Georgia Institute of Technology and Emory University, Atlanta, GA, USA
| | - C Ross Ethier
- Wallace H. Coulter Department of Biomedical Engineering, Georgia Institute of Technology and Emory University, Atlanta, GA, USA
| | - Bryn A Martin
- Alcyone Therapeutics Inc., Lowell, MA 01852, USA.,Department of Chemical and Biological Engineering, University of Idaho, 875 Perimeter Drive, MC1122, Moscow, ID 83844-1122, USA
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27
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Macaulay TR, Peters BT, Wood SJ, Clément GR, Oddsson L, Bloomberg JJ. Developing Proprioceptive Countermeasures to Mitigate Postural and Locomotor Control Deficits After Long-Duration Spaceflight. Front Syst Neurosci 2021; 15:658985. [PMID: 33986648 PMCID: PMC8111171 DOI: 10.3389/fnsys.2021.658985] [Citation(s) in RCA: 7] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/26/2021] [Accepted: 04/06/2021] [Indexed: 12/16/2022] Open
Abstract
Astronauts experience post-flight disturbances in postural and locomotor control due to sensorimotor adaptations during spaceflight. These alterations may have adverse consequences if a rapid egress is required after landing. Although current exercise protocols can effectively mitigate cardiovascular and muscular deconditioning, the benefits to post-flight sensorimotor dysfunction are limited. Furthermore, some exercise capabilities like treadmill running are currently not feasible on exploration spaceflight vehicles. Thus, new in-flight operational countermeasures are needed to mitigate postural and locomotor control deficits after exploration missions. Data from spaceflight and from analog studies collectively suggest that body unloading decreases the utilization of proprioceptive input, and this adaptation strongly contributes to balance dysfunction after spaceflight. For example, on return to Earth, an astronaut's vestibular input may be compromised by adaptation to microgravity, but their proprioceptive input is compromised by body unloading. Since proprioceptive and tactile input are important for maintaining postural control, keeping these systems tuned to respond to upright balance challenges during flight may improve functional task performance after flight through dynamic reweighting of sensory input. Novel approaches are needed to compensate for the challenges of balance training in microgravity and must be tested in a body unloading environment such as head down bed rest. Here, we review insights from the literature and provide observations from our laboratory that could inform the development of an in-flight proprioceptive countermeasure.
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Affiliation(s)
| | | | - Scott J. Wood
- NASA Johnson Space Center, Houston, TX, United States
| | | | - Lars Oddsson
- RxFunction Inc., Eden Prairie, MN, United States
- Department of Rehabilitation Medicine, University of Minnesota, Minneapolis, MN, United States
- Recaniti School for Community Health Professions, Ben Gurion University of the Negev, Beersheba, Israel
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28
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Marshall-Goebel K, Macias BR, Laurie SS, Lee SMC, Ebert DJ, Kemp DT, Miller A, Greenwald SH, Martin DS, Young M, Hargens AR, Levine BD, Stenger MB. Mechanical countermeasures to headward fluid shifts. J Appl Physiol (1985) 2021; 130:1766-1777. [PMID: 33856253 DOI: 10.1152/japplphysiol.00863.2020] [Citation(s) in RCA: 9] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/13/2022] Open
Abstract
Head-to-foot gravitationally induced hydrostatic pressure gradients in the upright posture on Earth are absent in weightlessness. This results in a relative headward fluid shift in the vascular and cerebrospinal fluid compartments and may underlie multiple physiological consequences of spaceflight, including the spaceflight-associated neuro-ocular syndrome. Here, we tested three mechanical countermeasures [lower body negative pressure (LBNP), venoconstrictive thigh cuffs (VTC), and impedance threshold device (ITD) resistive inspiratory breathing] individually and in combination to reduce a posture-induced headward fluid shift as a ground-based spaceflight analog. Ten healthy subjects (5 male) underwent baseline measures (seated and supine postures) followed by countermeasure exposure in the supine posture. Noninvasive measurements included ultrasound [internal jugular veins (IJV) cross-sectional area, cardiac stroke volume, optic nerve sheath diameter, noninvasive IJV pressure], transient evoked otoacoustic emissions (OAE; intracranial pressure index), intraocular pressure, choroidal thickness from optical coherence tomography imaging, and brachial blood pressure. Compared with the supine posture, IJV area decreased 48% with application of LBNP [mean ratio: 0.52, 95% confidence interval (CI): 0.44-0.60, P < 0.001], 31% with VTC (mean ratio: 0.69, 95% CI: 0.55-0.87, P < 0.001), and 56% with ITD (mean ratio: 0.44, 95% CI: 0.12-1.70, P = 0.46), measured at end-inspiration. LBNP was the only individual countermeasure to decrease the OAE phase angle (Δ -12.9 degrees, 95% CI: -25 to -0.9, P = 0.027), and use of combined countermeasures did not result in greater effects. Thus, LBNP, and to a lesser extent VTC and ITD, represents promising headward fluid shift countermeasures but will require future testing in analog and spaceflight environments.NEW & NOTEWORTHY As a weightlessness-induced headward fluid shift is hypothesized to be a primary factor underlying several physiological consequences of spaceflight, countermeasures aimed at reversing the fluid shift will likely be crucial during exploration-class spaceflight missions. Here, we tested three mechanical countermeasures individually and in various combinations to reduce a posture-induced headward fluid shift as a ground-based spaceflight analog.
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Affiliation(s)
| | | | | | | | | | - David T Kemp
- University College London Ear Institute, London, United Kingdom
| | | | | | | | | | - Alan R Hargens
- Department of Orthopaedic Surgery, UC San Diego Medical Center, University of California, San Diego, California
| | - Benjamin D Levine
- Institute for Exercise and Environmental Medicine, Texas Health Presbyterian Hospital Dallas, UT Southwestern, Dallas, Texas
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29
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Norager NH, Olsen MH, Pedersen SH, Riedel CS, Czosnyka M, Juhler M. Reference values for intracranial pressure and lumbar cerebrospinal fluid pressure: a systematic review. Fluids Barriers CNS 2021; 18:19. [PMID: 33849603 PMCID: PMC8045192 DOI: 10.1186/s12987-021-00253-4] [Citation(s) in RCA: 9] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/04/2021] [Accepted: 03/30/2021] [Indexed: 11/10/2022] Open
Abstract
BACKGROUND Although widely used in the evaluation of the diseased, normal intracranial pressure and lumbar cerebrospinal fluid pressure remain sparsely documented. Intracranial pressure is different from lumbar cerebrospinal fluid pressure. In addition, intracranial pressure differs considerably according to the body position of the patient. Despite this, the current reference values do not distinguish between intracranial and lumbar cerebrospinal fluid pressures, and body position-dependent reference values do not exist. In this study, we aim to establish these reference values. METHOD A systematic search was conducted in MEDLINE, EMBASE, CENTRAL, and Web of Sciences. Methodological quality was assessed using an amended version of the Joanna Briggs Quality Appraisal Checklist. Intracranial pressure and lumbar cerebrospinal fluid pressure were independently evaluated and subdivided into body positions. Quantitative data were presented with mean ± SD, and 90% reference intervals. RESULTS Thirty-six studies were included. Nine studies reported values for intracranial pressure, while 27 reported values for the lumbar cerebrospinal fluid pressure. Reference values for intracranial pressure were - 5.9 to 8.3 mmHg in the upright position and 0.9 to 16.3 mmHg in the supine position. Reference values for lumbar cerebrospinal fluid pressure were 7.2 to 16.8 mmHg and 5.7 to 15.5 mmHg in the lateral recumbent position and supine position, respectively. CONCLUSIONS This systematic review is the first to provide position-dependent reference values for intracranial pressure and lumbar cerebrospinal fluid pressure. Clinically applicable reference values for normal lumbar cerebrospinal fluid pressure were established, and are in accordance with previously used reference values. For intracranial pressure, this study strongly emphasizes the scarcity of normal pressure measures, and highlights the need for further research on the matter.
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Affiliation(s)
| | | | | | - Casper Schwartz Riedel
- Department of Neurosurgery, Rigshospitalet, Copenhagen, Denmark
- Department of Neurophysiology, Rigshospitalet, Glostrup, Denmark
| | - Marek Czosnyka
- Brain Physics Laboratory, Department of Clinical Neurosciences, Addenbrooke's Hospital, University of Cambridge, Cambridge, UK
| | - Marianne Juhler
- Department of Neurosurgery, Rigshospitalet, Copenhagen, Denmark
- Department of Neurosurgery, Aarhus University Hospital, Aarhus, Denmark
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30
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Ong J, Lee AG, Moss HE. Head-Down Tilt Bed Rest Studies as a Terrestrial Analog for Spaceflight Associated Neuro-Ocular Syndrome. Front Neurol 2021; 12:648958. [PMID: 33841315 PMCID: PMC8032981 DOI: 10.3389/fneur.2021.648958] [Citation(s) in RCA: 25] [Impact Index Per Article: 8.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/03/2021] [Accepted: 03/01/2021] [Indexed: 01/16/2023] Open
Abstract
Astronauts who undergo prolonged periods of spaceflight may develop a unique constellation of neuro-ocular findings termed Spaceflight Associated Neuro-Ocular Syndrome (SANS). SANS is a disorder that is unique to spaceflight and has no terrestrial equivalent. The prevalence of SANS increases with increasing spaceflight duration and although there have been residual, structural, ocular changes noted, no irreversible or permanent visual loss has occurred after SANS, with the longest spaceflight to date being 14 months. These microgravity-induced findings are being actively investigated by the United States' National Aeronautics Space Administration (NASA) and SANS is a potential obstacle to future longer duration, manned, deep space flight missions. The pathophysiology of SANS remains incompletely understood but continues to be a subject of intense study by NASA and others. The study of SANS is of course partially limited by the small sample size of humans undergoing spaceflight. Therefore, identifying a terrestrial experimental model of SANS is imperative to facilitate its study and for testing of preventative measures and treatments. Head-down tilt bed rest (HDTBR) on Earth has emerged as one promising possibility. In this paper, we review the HDTBR as an analog for SANS pathogenesis; the clinical and imaging overlap between SANS and HDTBR studies; and potential SANS countermeasures that have been or could be tested with HDTBR.
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Affiliation(s)
- Joshua Ong
- University of Pittsburgh School of Medicine, Pittsburgh, PA, United States
| | - Andrew G Lee
- Department of Ophthalmology, Houston Methodist Hospital, Houston, TX, United States.,Baylor College of Medicine and the Center for Space Medicine, Houston, TX, United States.,The Houston Methodist Research Institute, Houston Methodist Hospital, Houston, TX, United States.,Departments of Ophthalmology, Neurology, and Neurosurgery, Weill Cornell Medicine, New York, NY, United States.,Department of Ophthalmology, University of Texas Medical Branch, Galveston, TX, United States.,University of Texas MD Anderson Cancer Center, Houston, TX, United States.,Texas A and M College of Medicine, Bryan, TX, United States.,Department of Ophthalmology, The University of Iowa Hospitals and Clinics, Iowa City, IA, United States
| | - Heather E Moss
- Departments of Ophthalmology, Stanford University, Palo Alto, CA, United States.,Departments of Neurology & Neurosciences, Stanford University, Palo Alto, CA, United States
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31
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Abstract
PURPOSE OF REVIEW Several decades of long duration space flight missions by the National Aeronautics and Space Administration has revealed an interesting and unique constellation of neuro-ophthalmic findings now called spaceflight associated neuro-ocular syndrome (SANS). The unique space environment of microgravity produces novel physiological changes and derangements that present a challenge to astronauts in current and future long duration space missions. Although the precise mechanism of SANS is not fully understood, in this review, we examine recent developments that may to help explain possible causes and potential countermeasures. RECENT FINDINGS The cause of SANS is still largely unknown. A growing body of evidence implicates multiple factors that contribute to the development of SANS including cephalad fluid shifts, increased intracranial pressure, venous/lymphatic stasis, inflammation, metabolism, axoplasmic stasis and radiation exposure. SUMMARY The pathologic mechanism behind SANS may be multifactorial and may be amenable to different countermeasures for prevention and management of SANS.
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32
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Hupfeld KE, McGregor HR, Reuter-Lorenz PA, Seidler RD. Microgravity effects on the human brain and behavior: Dysfunction and adaptive plasticity. Neurosci Biobehav Rev 2021; 122:176-189. [PMID: 33454290 DOI: 10.1016/j.neubiorev.2020.11.017] [Citation(s) in RCA: 35] [Impact Index Per Article: 11.7] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/23/2020] [Revised: 09/01/2020] [Accepted: 11/11/2020] [Indexed: 10/22/2022]
Abstract
Emerging plans for travel to Mars and other deep space destinations make it critical for us to understand how spaceflight affects the human brain and behavior. Research over the past decade has demonstrated two co-occurring patterns of spaceflight effects on the brain and behavior: dysfunction and adaptive plasticity. Evidence indicates the spaceflight environment induces adverse effects on the brain, including intracranial fluid shifts, gray matter changes, and white matter declines. Past work also suggests that the spaceflight environment induces adaptive neural effects such as sensory reweighting and neural compensation. Here, we introduce a new conceptual framework to synthesize spaceflight effects on the brain, Spaceflight Perturbation Adaptation Coupled with Dysfunction (SPACeD). We review the literature implicating neurobehavioral dysfunction and adaptation in response to spaceflight and microgravity analogues, and we consider pre-, during-, and post-flight factors that may interact with these processes. We draw several instructive parallels with the aging literature which also suggests co-occurring neurobehavioral dysfunction and adaptive processes. We close with recommendations for future spaceflight research, including: 1) increased efforts to distinguish between dysfunctional versus adaptive effects by testing brain-behavioral correlations, and 2) greater focus on tracking recovery time courses.
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Affiliation(s)
- K E Hupfeld
- Department of Applied Physiology and Kinesiology, University of Florida, Gainesville, FL, United States
| | - H R McGregor
- Department of Applied Physiology and Kinesiology, University of Florida, Gainesville, FL, United States
| | - P A Reuter-Lorenz
- Department of Psychology, University of Michigan, Ann Arbor, MI, United States
| | - R D Seidler
- Department of Applied Physiology and Kinesiology, University of Florida, Gainesville, FL, United States; Norman Fixel Institute for Neurological Diseases, University of Florida, Gainesville, FL, United States.
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33
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Effect of gravity on brain structure as indicated on upright computed tomography. Sci Rep 2021; 11:392. [PMID: 33431952 PMCID: PMC7801697 DOI: 10.1038/s41598-020-79695-z] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/08/2020] [Accepted: 12/11/2020] [Indexed: 12/22/2022] Open
Abstract
We aimed to use upright computed tomography (CT) to depict posture-related changes in the brain tissue under normal gravity. Thirty-two asymptomatic volunteers underwent upright CT in the sitting position and conventional CT in the supine position on the same day. We compared the shift of the pineal body, cerebellar tonsil, the length of pituitary stalk, optic nerve sheath area and perimeter (ONSA and ONSP, respectively), and lateral ventricular volume between the supine and sitting positions. We also compared shape changes of the cerebrospinal fluid (CSF) spaces at different sites between both positions. In the sitting position, the pineal body shifted 0.68 ± 0.27 mm in the ventral direction and 0.76 ± 0.24 mm in the caudal direction, the length of pituitary stalk decreased by 1.23 ± 0.71 mm, the cerebellar tonsil descended by 2.10 ± 0.86 mm, the right ONSA decreased by 15.21 ± 6.54%, the left ONSA decreased by 15.30 ± 7.37%, the right ONSP decreased by 8.52 ± 3.91%, the left ONSP decreased by 8.20 ± 4.38%, and the lateral ventricular volume decreased by 5.07 ± 3.24% (all P < 0.001). We also observed changes in the shape of CSF spaces with changes in posture. We concluded that the intracranial structure of healthy subjects and volume of ventricles changed according to posture on Earth.
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Abstract
PURPOSE OF REVIEW During prolonged spaceflight, astronauts often experience ocular changes, due to constant head-ward fluid shifts in space as compared with Earth. This article reviews symptoms, likely causes, and potential solutions, such as lower body negative pressure, to counteract space-associated neuroocular syndrome (SANS). RECENT FINDINGS Low gravity conditions and other aspects of spaceflight affect the eye detrimentally, causing SANS which is characterized by optic disc edema, choroidal thickening, cotton wool spots, and a hyperopic shift. SANS is probably caused by altered hemodynamic flows in the head and neck as well as mildly elevated intracranial and intraocular pressures. Carbon dioxide and other chemicals in space-craft may influence SANS as well. SANS may be counteracted by using lower body negative pressure, thigh cuffs, spacecraft engineering, and/or artificial gravity by a centrifuge. SUMMARY Prolonged space missions are associated with optic disc edema, choroidal thickening, cotton wool spots, and a hyperopic shift. Possible causes and countermeasures are currently being researched to reduce the risk of SANS. Although many countermeasures to SANS are under investigation lower body negative pressure exhibits great promise in counteracting the headward fluid shifts in space. Understanding and prevention of SANS is critical to future space exploration, especially to long-duration missions to the moon and Mars.
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Affiliation(s)
- Emily A Khossravi
- Department of Orthopaedic Surgery, University of California, San Diego, California, USA
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Harris KM, Petersen LG, Weber T. Reviving lower body negative pressure as a countermeasure to prevent pathological vascular and ocular changes in microgravity. NPJ Microgravity 2020; 6:38. [PMID: 33335101 PMCID: PMC7746725 DOI: 10.1038/s41526-020-00127-3] [Citation(s) in RCA: 17] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/16/2020] [Accepted: 10/30/2020] [Indexed: 02/08/2023] Open
Abstract
Mitigation of spaceflight-related pathologies such as spaceflight-associated neuro-ocular syndrome (SANS) and the recently discovered risk of venous thrombosis must happen before deep space exploration can occur. Lower body negative pressure (LBNP) can simulate gravitational stress during spaceflight that is likely to counteract SANS and venous thrombosis, but the ideal dose and method of delivery have yet to be determined. We undertook a review of current LBNP literature and conducted a gap analysis to determine the steps needed to adapt LBNP for in-flight use. We found that to use LBNP in flight, it must be adapted to long time duration/low pressure use that should be compatible with crew activities. A lack of understanding of the etiology of the pathologies that LBNP can counteract hinders the application of LBNP as a countermeasure during spaceflight. Future research should aim at filling the knowledge gaps outlined in this review.
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Affiliation(s)
- Katie M Harris
- Faculty of Medicine, Memorial University of Newfoundland, St. John's, NL, Canada.
| | - Lonnie G Petersen
- Department of Mechanical and Aerospace Engineering, University of California San Diego, San Diego, CA, USA.,Department of Radiology, University of California San Diego, San Diego, CA, USA.,Department of Biomedical Science, University of Copenhagen, Copenhagen, Denmark
| | - Tobias Weber
- Space Medicine Team (HRE-OM), European Astronaut Centre (EAC), European Space Agency (ESA), Köln, Germany.,KBR GmbH, Köln, Germany
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Hansen AB, Lawley JS, Rickards CA, Howden EJ, Sarma S, Cornwell WK, Amin SB, Mugele H, Marume K, Possnig C, Whitworth LA, Williams MA, Levine BD. Reducing intracranial pressure by reducing central venous pressure: assessment of potential countermeasures to spaceflight-associated neuro-ocular syndrome. J Appl Physiol (1985) 2020; 130:283-289. [PMID: 33270516 DOI: 10.1152/japplphysiol.00786.2020] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
Spaceflight-associated neuro-ocular syndrome (SANS) involves unilateral or bilateral optic disc edema, widening of the optic nerve sheath, and posterior globe flattening. Owing to posterior globe flattening, it is hypothesized that microgravity causes a disproportionate change in intracranial pressure (ICP) relative to intraocular pressure. Countermeasures capable of reducing ICP include thigh cuffs and breathing against inspiratory resistance. Owing to the coupling of central venous pressure (CVP) and intracranial pressure, we hypothesized that both ICP and CVP will be reduced during both countermeasures. In four male participants (32 ± 13 yr) who were previously implanted with Ommaya reservoirs for treatment of unrelated clinical conditions, ICP was measured invasively through these ports. Subjects were healthy at the time of testing. CVP was measured invasively by a peripherally inserted central catheter. Participants breathed through an impedance threshold device (ITD, -7 cmH2O) to generate negative intrathoracic pressure for 5 min, and subsequently, wore bilateral thigh cuffs inflated to 30 mmHg for 2 min. Breathing through an ITD reduced both CVP (6 ± 2 vs. 3 ± 1 mmHg; P = 0.02) and ICP (16 ± 3 vs. 12 ± 1 mmHg; P = 0.04) compared to baseline, a result that was not observed during the free breathing condition (CVP, 6 ± 2 vs. 6 ± 2 mmHg, P = 0.87; ICP, 15 ± 3 vs. 15 ± 4 mmHg, P = 0.68). Inflation of the thigh cuffs to 30 mmHg caused no meaningful reduction in CVP in all four individuals (5 ± 4 vs. 5 ± 4 mmHg; P = 0.1), coincident with minimal reduction in ICP (15 ± 3 vs. 14 ± 4 mmHg; P = 0.13). The application of inspiratory resistance breathing resulted in reductions in both ICP and CVP, likely due to intrathoracic unloading.NEW & NOTEWORTHY Spaceflight causes pathological changes in the eye that may be due to the absence of gravitational unloading of intracranial pressure (ICP) under microgravity conditions commonly referred to as spaceflight-associated neuro-ocular syndrome (SANS), whereby countermeasures aimed at lowering ICP are necessary. These data show that impedance threshold breathing acutely reduces ICP via a reduction in central venous pressure (CVP). Whereas, acute thigh cuff inflation, a popular known spaceflight-associated countermeasure, had little effect on ICP and CVP.
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Affiliation(s)
- Alexander B Hansen
- Department of Sport Science, University of Innsbruck, Innsbruck, Austria
| | - Justin S Lawley
- Department of Sport Science, University of Innsbruck, Innsbruck, Austria.,Institute for Exercise and Environmental Medicine, Texas Health Presbyterian Dallas, Dallas, Texas.,University of Texas Southwestern Medical Center, Dallas, Texas
| | - Caroline A Rickards
- Department of Physiology and Anatomy, University of North Texas Health Science Center, Fort Worth, Texas
| | - Erin J Howden
- The Baker Heart and Diabetes Institute, Melbourne, Victoria, Australia
| | - Satyam Sarma
- Institute for Exercise and Environmental Medicine, Texas Health Presbyterian Dallas, Dallas, Texas.,University of Texas Southwestern Medical Center, Dallas, Texas
| | - William K Cornwell
- Division of Cardiology, Department of Internal Medicine, University of Colorado Anschutz Medical Campus, Aurora, Colorado
| | - Sachin B Amin
- Department of Sport Science, University of Innsbruck, Innsbruck, Austria
| | - Hendrik Mugele
- Department of Sport Science, University of Innsbruck, Innsbruck, Austria
| | - Kyohei Marume
- Department of Sport Science, University of Innsbruck, Innsbruck, Austria
| | - Carmen Possnig
- Department of Sport Science, University of Innsbruck, Innsbruck, Austria
| | | | - Michael A Williams
- Departments of Neurology and Neurological Surgery, University of Washington School of Medicine, Seattle, Washington
| | - Benjamin D Levine
- Institute for Exercise and Environmental Medicine, Texas Health Presbyterian Dallas, Dallas, Texas.,University of Texas Southwestern Medical Center, Dallas, Texas
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Norager NH, Olsen MH, Riedel CS, Juhler M. Changes in intracranial pressure and pulse wave amplitude during postural shifts. Acta Neurochir (Wien) 2020; 162:2983-2989. [PMID: 32886224 DOI: 10.1007/s00701-020-04550-z] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/02/2020] [Accepted: 08/24/2020] [Indexed: 11/27/2022]
Abstract
BACKGROUND Monitoring of intracranial pressure (ICP) and ICP pulse wave amplitude (PWA) is an integrated part of neurosurgery. An increase in ICP usually leads to an increase in PWA. These findings have yet to be replicated during the positional shift from supine to upright, where we only know that ICP decreases. Our main aim is to clarify whether the positional shift also results in a change in pulse wave amplitude. METHOD Our database was retrospectively reviewed for subjects having had a standardized investigation of positional ICP. In all subjects, mean ICP and PWA were determined with both an automatic and a manual method and compared using Student's t test. Finally, ICP and PWA were tested for correlation in both in supine and upright position. RESULTS The study included 29 subjects. A significant change in ICP (Δ14.1 mmHg, p < 0.01) and no significant change in PWA (Δ0.4 mmHg, p = 0.06) were found. Furthermore, a linear correlation between ICP and PWA was found in both supine and upright positions (p < 0.01). CONCLUSIONS We found that during the positional shift from supine to upright, ICP is reduced while PWA remains unaffected. This indicates that the pressure-volume curve is shifted downward according to a hydrostatic pressure offset, while the slope of the curve does not change. In addition, the correlation between ICP and PWA in both supine and upright position validates the previous research on the matter.
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Affiliation(s)
| | | | - Casper Schwartz Riedel
- Department of Neurosurgery, Rigshospitalet, Copenhagen, Denmark
- Department of Neurophysiology, Rigshospitalet, Glostrup, Denmark
| | - Marianne Juhler
- Department of Neurosurgery, Rigshospitalet, Copenhagen, Denmark
- Department of Neurosurgery, Aarhus University Hospital, Aarhus, Denmark
- Institute of Clinical Medicine, University of Copenhagen, Copenhagen, Denmark
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38
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Laurie SS, Lee SMC, Macias BR, Patel N, Stern C, Young M, Stenger MB. Optic Disc Edema and Choroidal Engorgement in Astronauts During Spaceflight and Individuals Exposed to Bed Rest. JAMA Ophthalmol 2020; 138:165-172. [PMID: 31876939 DOI: 10.1001/jamaophthalmol.2019.5261] [Citation(s) in RCA: 53] [Impact Index Per Article: 13.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/28/2023]
Abstract
Importance Optic disc edema develops in astronauts during long-duration spaceflight and is a risk for all future astronauts during spaceflight. Having a ground-based analogue of weightlessness that reproduces critical features of spaceflight-associated neuro-ocular syndrome will facilitate understanding, preventing, and/or treating this syndrome. Objective To determine whether the ocular changes in individuals exposed to an analogue of weightlessness are similar to the ocular changes in astronauts exposed to a duration of spaceflight comparable to this analogue of weightlessness. Design, Setting, and Participants This cohort study, conducted from 2012 to 2018, investigated 11 healthy test participants before, during, and after 30 days of strict 6° head-down tilt bed rest as well as 20 astronauts before and during approximately 30 days of spaceflight. Data were collected at NASA Johnson Space Center, the German Aerospace Center, and on board the International Space Station. Statistical analysis was performed from February 13 to April 24, 2019. Main Outcomes and Measures Peripapillary total retinal thickness and peripapillary choroid thickness quantified from optical coherence tomography images. Results Peripapillary total retinal thickness increased to a greater degree among 11 individuals (6 men and 5 women; mean [SD] age, 33.4 [8.0 years]) exposed to bed rest than among 20 astronauts (17 men and 3 women; mean [SD] age, 46.0 [6.0] years), with a mean difference between groups of 37 μm (95% CI, 13-61 μm; P = .005). Conversely, choroid thickness did not increase among the individuals exposed to bed rest but increased among the astronauts, resulting in a mean difference between groups of 27 μm (95% CI, 14-41 μm; P < .001). Conclusions and Relevance These findings suggest that strict head-down tilt bed rest produces a different magnitude of edema than occurs after a similar duration of spaceflight, and no change in choroid thickness. It is possible that a mild, long-term elevation in intracranial pressure experienced by individuals exposed to bed rest is greater than the intracranial pressure experienced by astronauts during spaceflight, which may explain the different severity of optic disc edema between the cohorts. Gravitational gradients that remain present during bed rest may explain the lack of increase in choroid thickness during bed rest, which differs from the lack of gravitational gradients during spaceflight. Despite the possibility that different mechanisms may underlie optic disc edema development in modeled and real spaceflight, use of this terrestrial model of spaceflight-associated neuro-ocular syndrome will be assistive in the development of effective countermeasures that will protect the eyes of astronauts during future space missions.
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Affiliation(s)
| | | | | | - Nimesh Patel
- College of Optometry, University of Houston, Houston, Texas
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Iwasaki KI, Ogawa Y, Kurazumi T, Imaduddin SM, Mukai C, Furukawa S, Yanagida R, Kato T, Konishi T, Shinojima A, Levine BD, Heldt T. Long-duration spaceflight alters estimated intracranial pressure and cerebral blood velocity. J Physiol 2020; 599:1067-1081. [PMID: 33103234 PMCID: PMC7894300 DOI: 10.1113/jp280318] [Citation(s) in RCA: 15] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/11/2020] [Accepted: 10/19/2020] [Indexed: 12/20/2022] Open
Abstract
Key points During long‐duration spaceflights, some astronauts develop structural ocular changes including optic disc oedema that resemble signs of intracranial hypertension. In the present study, intracranial pressure was estimated non‐invasively (nICP) using a model‐based analysis of cerebral blood velocity and arterial blood pressure waveforms in 11 astronauts before and after long‐duration spaceflights. Our results show that group‐averaged estimates of nICP decreased significantly in nine astronauts without optic disc oedema, suggesting that the cephalad fluid shift during long‐duration spaceflight rarely increased postflight intracranial pressure. The results of the two astronauts with optic disc oedema suggest that both increases and decreases in nICP are observed post‐flight in astronauts with ocular alterations, arguing against a primary causal relationship between elevated ICP and spaceflight associated optical changes. Cerebral blood velocity increased independently of nICP and spaceflight‐associated ocular alterations. This increase may be caused by the reduced haemoglobin concentration after long‐duration spaceflight.
Abstract Persistently elevated intracranial pressure (ICP) above upright values is a suspected cause of optic disc oedema in astronauts. However, no systematic studies have evaluated changes in ICP from preflight. Therefore, ICP was estimated non‐invasively before and after spaceflight to test whether ICP would increase after long‐duration spaceflight. Cerebral blood velocity in the middle cerebral artery (MCAv) was obtained by transcranial Doppler sonography and arterial pressure in the radial artery was obtained by tonometry, in the supine and sitting positions before and after 4−12 months of spaceflight in 11 astronauts (10 males and 1 female, 46 ± 7 years old at launch). Non‐invasive ICP (nICP) was computed using a validated model‐based estimation method. Mean MCAv increased significantly after spaceflight (ANOVA, P = 0.007). Haemoglobin decreased significantly after spaceflight (14.6 ± 0.8 to 13.3 ± 0.7 g/dL, P < 0.001). A repeated measures correlation analysis indicated a negative correlation between haemoglobin and mean MCAv (r = −0.589, regression coefficient = −4.68). The nICP did not change significantly after spaceflight in the 11 astronauts. However, nICP decreased significantly by 15% in nine astronauts without optic disc oedema (P < 0.005). Only one astronaut increased nICP to relatively high levels after spaceflight. Contrary to our hypothesis, nICP did not increase after long‐duration spaceflight in the vast majority (>90%) of astronauts, suggesting that the cephalad fluid shift during spaceflight does not systematically or consistently elevate postflight ICP in astronauts. Independently of nICP and ocular alterations, the present results of mean MCAv suggest that long‐duration spaceflight may increase cerebral blood flow, possibly due to reduced haemoglobin concentration. During long‐duration spaceflights, some astronauts develop structural ocular changes including optic disc oedema that resemble signs of intracranial hypertension. In the present study, intracranial pressure was estimated non‐invasively (nICP) using a model‐based analysis of cerebral blood velocity and arterial blood pressure waveforms in 11 astronauts before and after long‐duration spaceflights. Our results show that group‐averaged estimates of nICP decreased significantly in nine astronauts without optic disc oedema, suggesting that the cephalad fluid shift during long‐duration spaceflight rarely increased postflight intracranial pressure. The results of the two astronauts with optic disc oedema suggest that both increases and decreases in nICP are observed post‐flight in astronauts with ocular alterations, arguing against a primary causal relationship between elevated ICP and spaceflight associated optical changes. Cerebral blood velocity increased independently of nICP and spaceflight‐associated ocular alterations. This increase may be caused by the reduced haemoglobin concentration after long‐duration spaceflight.
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Affiliation(s)
- Ken-Ichi Iwasaki
- Department of Social Medicine, Division of Hygiene, Nihon University School of Medicine, Itabashi-ku, Tokyo, Japan
| | - Yojiro Ogawa
- Department of Social Medicine, Division of Hygiene, Nihon University School of Medicine, Itabashi-ku, Tokyo, Japan
| | - Takuya Kurazumi
- Department of Social Medicine, Division of Hygiene, Nihon University School of Medicine, Itabashi-ku, Tokyo, Japan
| | - Syed M Imaduddin
- Department of Electrical Engineering and Computer Science, Institute for Medical Engineering and Science, Massachusetts Institute of Technology, Cambridge, MA, USA
| | - Chiaki Mukai
- Space Biomedical Research Group, Japan Aerospace Exploration Agency, Tsukuba-shi, Ibaraki, Japan.,Tokyo University of Science, Shinjuku-ku, Tokyo, Japan
| | - Satoshi Furukawa
- Space Biomedical Research Group, Japan Aerospace Exploration Agency, Tsukuba-shi, Ibaraki, Japan
| | - Ryo Yanagida
- Department of Social Medicine, Division of Hygiene, Nihon University School of Medicine, Itabashi-ku, Tokyo, Japan
| | - Tomokazu Kato
- Department of Social Medicine, Division of Hygiene, Nihon University School of Medicine, Itabashi-ku, Tokyo, Japan
| | - Toru Konishi
- Department of Social Medicine, Division of Hygiene, Nihon University School of Medicine, Itabashi-ku, Tokyo, Japan.,Aeromedical Laboratory, Japan Air Self-Defense Force, Ministry of Defense, Sayama-shi, Saitama, Japan
| | - Ari Shinojima
- Department of Ophthalmology, Keio University School of Medicine, Shinjuku-ku, Tokyo, Japan
| | - Benjamin D Levine
- The Institute for Exercise and Environmental Medicine (IEEM) at Texas Health Presbyterian Hospital Dallas, Dallas, TX, USA.,Department of Medicine and Cardiology, the University of Texas Southwestern Medical Center, Dallas, TX, USA
| | - Thomas Heldt
- Department of Electrical Engineering and Computer Science, Institute for Medical Engineering and Science, Massachusetts Institute of Technology, Cambridge, MA, USA
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Martin Paez Y, Mudie LI, Subramanian PS. Spaceflight Associated Neuro-Ocular Syndrome (SANS): A Systematic Review and Future Directions. Eye Brain 2020; 12:105-117. [PMID: 33117025 PMCID: PMC7585261 DOI: 10.2147/eb.s234076] [Citation(s) in RCA: 14] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/03/2020] [Accepted: 09/22/2020] [Indexed: 12/24/2022] Open
Abstract
Purpose To present a systematic review of the current body of literature surrounding spaceflight associated neuro-ocular syndrome (SANS) and highlight priorities for future research. Methods Three major biomedical databases were searched with the following terms: ((neuro ocular) OR ((brain) AND (eye))) AND ((spaceflight) OR (astronaut) OR (microgravity)) AND (ENGLISH[Language]). Once duplicates were removed, 283 papers were left. Articles were excluded if they were not written in English or conference abstracts only. We avoided including review papers which did not provide any new information; however, two reviews on the pathophysiology of SANS were included for completeness. No limitations on date of publication were used. All included entries were then summarized for their contribution to knowledge about SANS. Results Four main themes among the publications emerged: papers defining the clinical entity of SANS, its pathophysiology, technology used to study SANS, and publications on possible prevention of SANS. The key clinical features of SANS include optic nerve head elevation, hyperopic shifts, globe flattening, choroidal folds, and increased cerebrospinal fluid (CSF) volume in optic nerve sheaths. Two main hypotheses are proposed for the pathophysiology of SANS. The first being elevated intracranial pressure and the second compartmentalization of CSF to the globe. These hypotheses are not mutually exclusive, and our understanding of the pathophysiology of SANS is still evolving. The use of optical coherence tomography (OCT) has greatly furthered our knowledge about SANS, and with the deployment of OCT to the International Space Station, we now have ability to collect intraflight data. No effective prevention for SANS has been found, although fortunately, even with persistent anatomic and physiologic neuro-ocular changes, any functional impact has been correctable with spectacles. Conclusion This is the first systematic review of SANS. Despite the limitations of studying a syndrome that can only occur in a small, discrete population, we present a thorough overview of the literature surrounding SANS and several key areas important for future research are identified.
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Affiliation(s)
- Yosbelkys Martin Paez
- Sue Anschutz-Rodgers/UCHealth Eye Center and Departments of Ophthalmology, Aurora, CO, 80045, USA.,Neurology, University of Colorado School of Medicine, Aurora, CO 80045, USA
| | - Lucy I Mudie
- Sue Anschutz-Rodgers/UCHealth Eye Center and Departments of Ophthalmology, Aurora, CO, 80045, USA
| | - Prem S Subramanian
- Sue Anschutz-Rodgers/UCHealth Eye Center and Departments of Ophthalmology, Aurora, CO, 80045, USA.,Neurology, University of Colorado School of Medicine, Aurora, CO 80045, USA.,Neurosurgery, University of Colorado School of Medicine, Aurora, CO 80045, USA
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Lawley JS, Babu G, Janssen SLJE, Petersen LG, Hearon CM, Dias KA, Sarma S, Williams MA, Whitworth LA, Levine BD. Daily generation of a footward fluid shift attenuates ocular changes associated with head-down tilt bed rest. J Appl Physiol (1985) 2020; 129:1220-1231. [PMID: 32940563 DOI: 10.1152/japplphysiol.00250.2020] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
Astronauts have presented with a constellation of visual changes referred to as spaceflight-associated neuro-ocular syndrome (SANS). However, neither have early markers of microgravity-induced optic remodeling been fully identified nor have countermeasures been developed. To identify early markers of SANS, we studied 10 subjects with optical coherence tomography and ultrasonography when upright and supine and again after 24 h of 6° head-down tilt (HDT) bed rest. Upon acute transition from the upright to the supine position, choroid area (2.24 ± 0.53 to 2.28 ± 0.52 mm2, P = 0.001) and volume (9.51 ± 2.08 to 9.73 ± 2.08 mm3, P = 0.002) increased. After 24 h of HDT bed rest, subfoveal choroidal thickness (372 ± 93 to 381 ± 95 µm, P = 0.02), choroid area (2.25 ± 0.52 to 2.33 ± 0.54 mm2, P = 0.08), and volume (9.64 ± 2.03 to 9.82 ± 2.08 mm3, P = 0.08) increased relative to the supine position. Subsequently, seven subjects spent 3 days in -6°HDT bed rest to assess whether low-level lower body negative pressure (LBNP) could prevent the observed choroidal engorgement during bed rest. Maintaining the -6° HDT position for 3 days caused choroid area (Δ0.11 mm2, P = 0.05) and volume (Δ0.45 mm3, P = 0.003) to increase. When participants also spent 8 h daily under -20 mmHg LBNP, choroid volume still increased, but substantially (40%) less than in the control trial (Δ0.27 mm3, P = 0.05). Moreover, the increase in choroid area was diminished (Δ0.03 mm2, P = 0.13), indicating that low-level LBNP attenuates the choroid expansion associated with 3 days of -6° HDT bed rest. These data suggest that low-level LBNP may be an effective countermeasure for SANS.NEW & NOTEWORTHY Choroid measurements appear to be sensitive to changes in gravitational gradients, as well as periods of head-down tilt (HDT) bed rest, suggesting that they are potential indicators of early ocular remodeling and could serve to evaluate the efficacy of countermeasures for SANS. Eight hours of lower body negative pressure (LBNP) daily attenuates the choroid expansion associated with 3 days of strict -6° HDT bed rest, indicating that LBNP may be an effective countermeasure for SANS.
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Affiliation(s)
- Justin S Lawley
- Institute for Exercise and Environmental Medicine, Texas Health Presbyterian Dallas, Dallas, Texas.,University of Texas Southwestern Medical Center, Dallas, Texas.,Division of Physiology, Department of Sports Science, University of Innsbruck, Innsbruck, Austria
| | - Gautam Babu
- Institute for Exercise and Environmental Medicine, Texas Health Presbyterian Dallas, Dallas, Texas.,University of Texas Southwestern Medical Center, Dallas, Texas
| | | | - Lonnie G Petersen
- Department of Orthopedic Surgery, University of California San Diego, California
| | - Christopher M Hearon
- Institute for Exercise and Environmental Medicine, Texas Health Presbyterian Dallas, Dallas, Texas.,University of Texas Southwestern Medical Center, Dallas, Texas
| | - Katrin A Dias
- Institute for Exercise and Environmental Medicine, Texas Health Presbyterian Dallas, Dallas, Texas.,University of Texas Southwestern Medical Center, Dallas, Texas
| | - Satyam Sarma
- Institute for Exercise and Environmental Medicine, Texas Health Presbyterian Dallas, Dallas, Texas.,University of Texas Southwestern Medical Center, Dallas, Texas
| | - Michael A Williams
- Department of Neurology, University of Washington School of Medicine, Seattle, Washington.,Department of Neurological Surgery, University of Washington School of Medicine, Seattle, Washington
| | | | - Benjamin D Levine
- Institute for Exercise and Environmental Medicine, Texas Health Presbyterian Dallas, Dallas, Texas.,University of Texas Southwestern Medical Center, Dallas, Texas
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Ogoh S, Washio T, Paton JFR, Fisher JP, Petersen LG. Gravitational effects on intracranial pressure and blood flow regulation in young men: a potential shunting role for the external carotid artery. J Appl Physiol (1985) 2020; 129:901-908. [PMID: 32816640 DOI: 10.1152/japplphysiol.00369.2020] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/11/2022] Open
Abstract
We sought to determine whether gravity-induced changes in intracranial pressure influence cerebral blood flow regulation. Accordingly, nine young healthy men were studied while supine (0°) and during mild changes in hydrostatic pressure induced by head-up tilt at +20° and +10° (HUT+20 and HUT+10) and head-down tilt at -20° and -10° (HDT-20, HDT-10). Blood flows were measured in the internal and external carotid and vertebral arteries (ICA, ECA, and VA). Intraocular pressure (IOP) was measured as an indicator of hydrostatic changes in intracranial pressure. A posture change from HUT+20 to HDT-20 increased IOP by +5.1 ± 1.9 mmHg (P < 0.001) and ECA blood flow (from 61.7 ± 26.1 to 87.6 ± 46.4 mL/min, P = 0.004) but did not affect ICA (P = 0.528) or VA (P = 0.101) blood flow. The increase in ECA flow correlated with the tilt angle and resultant changes in intracranial pressures (by IOP), thus indicating a passive hydrostatic gravitational dependence (r = 0.371, P = 0.012). On the contrary, ICA flow remained constant and thus well protected against moderate orthostatic stress. When ICA flow was corrected for the gravitational changes in intracranial pressures (by IOP), it demonstrated the same magnitude of gravitational dependence as ECA. These findings suggest that passive hydrostatic increases in intracranial pressure outbalance the concurrent increase in arterial feeding pressure to the brain and thus prevent cerebral hyperperfusion during HDT. The mechanism for maintaining constant cerebral flow was by increased ECA flow, thus supporting the role of these vascular beds as a shunting pathway.NEW & NOTEWORTHY We investigated whether gravity-induced changes in intracranial pressure influence cerebral blood flow regulation in young men. We recorded extra- and intracerebral blood flow during changes in posture, and data indicate that the external carotid artery may serve as an overflow pathway to prevent cerebral hyperperfusion during increases in cerebral arterial blood pressure.
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Affiliation(s)
- Shigehiko Ogoh
- Department of Biomedical Engineering, Toyo University, Kawagoe-Shi, Saitama, Japan
| | - Takuro Washio
- Department of Biomedical Engineering, Toyo University, Kawagoe-Shi, Saitama, Japan.,Japan Society for the Promotion of Science, Tokyo, Japan
| | - Julian F R Paton
- Department of Physiology, Faculty of Medical and Health Sciences, University of Auckland, Auckland, New Zealand
| | - James P Fisher
- Department of Physiology, Faculty of Medical and Health Sciences, University of Auckland, Auckland, New Zealand
| | - Lonnie G Petersen
- Department of Biomedical Science, Faculty of Health Science, University of Copenhagen, Copenhagen, Denmark.,Department of Radiology, University of California, San Diego, California.,Department of Mechanical and Aerospace Engineering, University of California, San Diego, California
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43
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Sinking skin flap syndrome visualized by upright computed tomography. Acta Neurochir (Wien) 2020; 162:1825-1828. [PMID: 32572578 DOI: 10.1007/s00701-020-04459-7] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/10/2020] [Accepted: 06/11/2020] [Indexed: 10/24/2022]
Abstract
Sinking skin flap syndrome is a craniectomy complication characterized by new neurological dysfunction that typically worsens in the upright position and improves after cranioplasty. We present a 33-year-old man who experienced hemiparesis in the upright position after craniectomy. Upright computed tomography (CT) before cranioplasty showed a remarkable shift of the brain compared to supine CT. After cranioplasty, both symptoms and brain shift on CT resolved. Upright CT enables detection and objective evaluation of paradoxical herniation and midline shift that is not obvious on supine imaging modalities. Clinicians need to be aware of positional brain shift in postcraniectomy patients.
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Wojcik P, Batliwala S, Rowsey T, Galdamez LA, Lee AG. Spaceflight-Associated Neuro-ocular Syndrome (SANS): a review of proposed mechanisms and analogs. EXPERT REVIEW OF OPHTHALMOLOGY 2020. [DOI: 10.1080/17469899.2020.1787155] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 10/24/2022]
Affiliation(s)
- Peter Wojcik
- Department of Ophthalmology, Blanton Eye Institute, Houston Methodist Hospital, Houston, TX, USA
| | - Shehzad Batliwala
- Department of Ophthalmology, Dean McGee Eye Institute, University of Oklahoma Health Science Center, Oklahoma City, OK, USA
| | - Tyler Rowsey
- College of Medicine, University of Oklahoma Health Science Center, Oklahoma City, OK, USA
| | - Laura A. Galdamez
- Department of Emergency Medicine, Memorial Hermann The Woodlands, Shenandoah, TX, USA
| | - Andrew G. Lee
- Department of Ophthalmology, Blanton Eye Institute, Houston Methodist Hospital, Houston, TX, USA
- Departments of Ophthalmology, Neurology, and Neurosurgery, Weill Cornell Medicine, New York, NY, USA
- Department of Ophthalmology, University of Texas Medical Branch, Galveston, TX, USA
- Department of Ophthalmology, University of Texas MD Anderson Cancer Center, Houston, TX, USA
- Texas A and M College of Medicine, Bryan, TX, USA
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45
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Xing C, Wang X, Gao Y, Zhang J, Liu Y, Guo Y, Wang C, Feng Y, Lei Y, Zhang X, Li J, Hu W, Zhang S, Yuan L, Gao F. Lower body negative pressure protects brain perfusion in aviation gravitational stress induced by push-pull manoeuvre. J Physiol 2020; 598:3173-3186. [PMID: 32415785 DOI: 10.1113/jp279876] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/14/2020] [Accepted: 05/12/2020] [Indexed: 01/12/2023] Open
Abstract
KEY POINTS Rapid alterations of gravitational stress during high-performance aircraft push-pull manoeuvres induce dramatic shifts in volume and pressure within the circulation system, which may result in loss of consciousness due to the rapid and significant reduction in cerebral perfusion. There are still no specific and effective countermeasures so far. We found that lower body negative pressure (LBNP), applied prior to and during -Gz and released at the subsequent transition to +Gz, could effectively counteract gravitational haemodynamic stress induced by a simulated push-pull manoeuvre and improve cerebral diastolic perfusion in human subjects. We developed a LBNP strategy that effectively protects cerebral perfusion at rapid -Gz to +Gz transitions via improving cerebral blood flow and blood pressure during push-pull manoeuvres and highlight the importance of the timing of the intervention. Our findings provide a systemic link of integrated responses between the peripheral and cerebral haemodynamic changes during push-pull manoeuvres. ABSTRACT The acute negative (-Gz) to positive (+Gz) gravity stress during high-performance aircraft push-pull manoeuvres dramatically reduces transient cerebral perfusion, which may lead to loss of vision or even consciousness. The aim of this study was to explore a specific and effective counteractive strategy. Twenty-three healthy young male volunteers (age 21 ± 1 year) were subjected to tilting-simulated push-pull manoeuvres. Lower body negative pressure (LBNP) of -40 mmHg was applied prior to and during -Gz stress (-0.50 or -0.87 Gz) and released at the subsequent transition to +1.00 Gz stress. Beat-to-beat cerebral and systemic haemodynamics were continuously recorded during the simulated push-pull manoeuvre in LBNP bouts and corresponding control bouts. During the rapid gravitational transition from -Gz to +Gz, the mean cerebral blood flow velocity decreased significantly in control bouts, while it increased in LBNP bouts (control vs. LBNP bouts, -6.6 ± 4.6 vs. 5.1 ± 6.8 cm s-1 for -0.50 Gz, and -7.4 ± 4.8 vs. 3.4 ± 4.6 cm s-1 for -0.87 Gz, P < 0.01), which was attributed mainly to the elevation of diastolic flow. The LBNP bouts showed much smaller reduction of mean arterial blood pressure at the brain level than control bouts (control bouts vs. LBNP bouts, -38 ± 12 vs. -23 ± 10 mmHg for -0.50 to +1.00 Gz, and -62 ± 16 vs. -43 ± 11 mmHg for -0.87 to +1.00 Gz, P < 0.01). LBNP applied at -Gz and released at subsequent +Gz had biphasic counteractive effects against the gravitational responses to the push-pull manoeuvre. These data demonstrate that this LBNP strategy could effectively protect cerebral perfusion with dominant improvement of diastolic flow during push-pull manoeuvres.
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Affiliation(s)
- Changyang Xing
- School of Aerospace Medicine, Fourth Military Medical University, Xi'an, 710032, China.,Department of Ultrasound Diagnostics, Tangdu Hospital, Fourth Military Medical University, Xi'an, 710038, China
| | - Xinpei Wang
- School of Aerospace Medicine, Fourth Military Medical University, Xi'an, 710032, China
| | - Yuan Gao
- School of Aerospace Medicine, Fourth Military Medical University, Xi'an, 710032, China
| | - Jiaxin Zhang
- School of Aerospace Medicine, Fourth Military Medical University, Xi'an, 710032, China
| | - Yunnan Liu
- Department of Ultrasound Diagnostics, Tangdu Hospital, Fourth Military Medical University, Xi'an, 710038, China
| | - Yitong Guo
- Department of Ultrasound Diagnostics, Tangdu Hospital, Fourth Military Medical University, Xi'an, 710038, China
| | - Chen Wang
- Department of Ultrasound Diagnostics, Tangdu Hospital, Fourth Military Medical University, Xi'an, 710038, China
| | - Yang Feng
- Department of Ultrasound Diagnostics, Tangdu Hospital, Fourth Military Medical University, Xi'an, 710038, China
| | - Yujia Lei
- Department of Ultrasound Diagnostics, Tangdu Hospital, Fourth Military Medical University, Xi'an, 710038, China
| | - Xing Zhang
- School of Aerospace Medicine, Fourth Military Medical University, Xi'an, 710032, China
| | - Jia Li
- School of Aerospace Medicine, Fourth Military Medical University, Xi'an, 710032, China
| | - Wendong Hu
- School of Aerospace Medicine, Fourth Military Medical University, Xi'an, 710032, China
| | - Shu Zhang
- School of Aerospace Medicine, Fourth Military Medical University, Xi'an, 710032, China
| | - Lijun Yuan
- Department of Ultrasound Diagnostics, Tangdu Hospital, Fourth Military Medical University, Xi'an, 710038, China
| | - Feng Gao
- School of Aerospace Medicine, Fourth Military Medical University, Xi'an, 710032, China
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Abstract
Telemetric intracranial pressure (ICP) monitoring is a new method of measuring ICP which eliminates some of the shortcomings of previous methods. However, there are limited data on specific characteristics, including the advantages and disadvantages of this method. The main aim of this study was to demonstrate the indications, benefits, and complications of telemetric ICP monitoring. PubMed, MEDLINE, EMBASE, and the Cochrane Central Register of Controlled Trials were searched for relevant studies without language or date restriction in May 2019. Human studies in which telemetric ICP monitoring was the main subject of the study were included. Our initial search resulted in 1650 articles from which 50 studies were included. There were no randomized controlled trials. The majority of the studies were case reports or case series (68%). The most common aim of studies was testing of the device (52%), and monitoring the disease progression or recovery (46%). The most common indications for telemetric ICP monitoring in these studies were testing cerebrospinal fluid shunt function (46%), ICP control after the procedure (36%), and diagnosing intracranial hypertension (22%) and hydrocephalus (12%). In total, 1423 brain disease patients had been monitored in studies. The possibility of long-term ICP monitoring as the main benefit was reported in 38 (76%) studies. The associated complication rate was 7.1%. Despite the increasing application of telemetric monitoring devices, studies to evaluate specific characteristics of this method have been infrequent and inadequate. Future research using a higher level of scientific methods is needed to evaluate advantage and disadvantages.
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47
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Spaceflight associated neuro-ocular syndrome (SANS) and the neuro-ophthalmologic effects of microgravity: a review and an update. NPJ Microgravity 2020; 6:7. [PMID: 32047839 PMCID: PMC7005826 DOI: 10.1038/s41526-020-0097-9] [Citation(s) in RCA: 107] [Impact Index Per Article: 26.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/15/2019] [Accepted: 11/11/2019] [Indexed: 11/08/2022] Open
Abstract
Prolonged microgravity exposure during long-duration spaceflight (LDSF) produces unusual physiologic and pathologic neuro-ophthalmic findings in astronauts. These microgravity associated findings collectively define the “Spaceflight Associated Neuro-ocular Syndrome” (SANS). We compare and contrast prior published work on SANS by the National Aeronautics and Space Administration’s (NASA) Space Medicine Operations Division with retrospective and prospective studies from other research groups. In this manuscript, we update and review the clinical manifestations of SANS including: unilateral and bilateral optic disc edema, globe flattening, choroidal and retinal folds, hyperopic refractive error shifts, and focal areas of ischemic retina (i.e., cotton wool spots). We also discuss the knowledge gaps for in-flight and terrestrial human research including potential countermeasures for future study. We recommend that NASA and its research partners continue to study SANS in preparation for future longer duration manned space missions.
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48
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Marshall-Goebel K, Damani R, Bershad EM. In Reply: Brain Physiological Response and Adaptation during Spaceflight. Neurosurgery 2020; 85:E1138-E1139. [PMID: 31541241 DOI: 10.1093/neuros/nyz374] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022] Open
Affiliation(s)
| | - Rahul Damani
- Department of Neurology Baylor College of Medicine Houston, Texas
| | - Eric M Bershad
- Department of Neurology Baylor College of Medicine Houston, Texas.,Center for Space Medicine Baylor College of Medicine Houston, Texas
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49
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Lilja-Cyron A, Andresen M, Kelsen J, Andreasen TH, Petersen LG, Fugleholm K, Juhler M. Intracranial pressure before and after cranioplasty: insights into intracranial physiology. J Neurosurg 2019; 133:1548-1558. [PMID: 31628275 DOI: 10.3171/2019.7.jns191077] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/17/2019] [Accepted: 07/24/2019] [Indexed: 11/06/2022]
Abstract
OBJECTIVE Decompressive craniectomy (DC) is an emergency neurosurgical procedure used in cases of severe intracranial hypertension or impending intracranial herniation. The procedure is often lifesaving, but it exposes the brain to atmospheric pressure in the subsequent rehabilitation period, which changes intracranial physiology and probably leads to complications such as hydrocephalus, hygromas, and "syndrome of the trephined." The objective of the study was to study the effect of cranioplasty on intracranial pressure (ICP), postural ICP changes, and intracranial pulse wave amplitude (PWA). METHODS The authors performed a prospective observational study including patients who underwent DC during a 12-month period. Telemetric ICP sensors were implanted in all patients at the time of DC. ICP was evaluated before and after cranioplasty during weekly measurement sessions including a standardized postural change program. RESULTS Twelve of the 17 patients enrolled in the study had cranioplasty performed and were included in the present investigation. Their mean ICP in the supine position increased from -0.5 ± 4.8 mm Hg the week before cranioplasty to 6.3 ± 2.5 mm Hg the week after cranioplasty (p < 0.0001), whereas the mean ICP in the sitting position was unchanged (-1.2 ± 4.8 vs -1.1 ± 3.6 mm Hg, p = 0.90). The difference in ICP between the supine and sitting positions was minimal before cranioplasty (1.1 ± 1.8 mm Hg) and increased to 7.4 ± 3.6 mm Hg in the week following cranioplasty (p < 0.0001). During the succeeding 2 weeks of the follow-up period, the mean ICP in the supine and sitting positions decreased in parallel to, respectively, 4.6 ± 3.0 mm Hg (p = 0.0003) and -3.9 ± 2.7 mm Hg (p = 0.040), meaning that the postural ICP difference remained constant at around 8 mm Hg. The mean intracranial PWA increased from 0.7 ± 0.7 mm Hg to 2.9 ± 0.8 mm Hg after cranioplasty (p < 0.0001) and remained around 3 mm Hg throughout the following weeks. CONCLUSIONS Cranioplasty restores normal intracranial physiology regarding postural ICP changes and intracranial PWA. These findings complement those of previous investigations on cerebral blood flow and cerebral metabolism in patients after decompressive craniectomy.
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Affiliation(s)
| | | | - Jesper Kelsen
- 2Orthopaedic Surgery (Spine Section), Rigshospitalet; and
| | | | - Lonnie Grove Petersen
- 3Department of Biomedical Sciences, Faculty of Health Services, University of Copenhagen, Copenhagen, Denmark
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50
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Martinez-Tejada I, Arum A, Wilhjelm JE, Juhler M, Andresen M. B waves: a systematic review of terminology, characteristics, and analysis methods. Fluids Barriers CNS 2019; 16:33. [PMID: 31610775 PMCID: PMC6792201 DOI: 10.1186/s12987-019-0153-6] [Citation(s) in RCA: 12] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/12/2019] [Accepted: 09/15/2019] [Indexed: 11/18/2022] Open
Abstract
Background Although B waves were introduced as a concept in the analysis of intracranial pressure (ICP) recordings nearly 60 years ago, there is still a lack consensus on precise definitions, terminology, amplitude, frequency or origin. Several competing terms exist, addressing either their probable physiological origin or their physical characteristics. To better understand B wave characteristics and ease their detection, a literature review was carried out. Methods A systematic review protocol including search strategy and eligibility criteria was prepared in advance. A literature search was carried out using PubMed/MEDLINE, with the following search terms: B waves + review filter, slow waves + review filter, ICP B waves, slow ICP waves, slow vasogenic waves, Lundberg B waves, MOCAIP. Results In total, 19 different terms were found, B waves being the most common. These terminologies appear to be interchangeable and seem to be used indiscriminately, with some papers using more than five different terms. Definitions and etiologies are still unclear, which makes systematic and standardized detection difficult. Conclusions Two future lines of action are available for automating macro-pattern identification in ICP signals: achieving strict agreement on morphological characteristics of “traditional” B waveforms, or starting a new with a fresh computerized approach for recognition of new clinically relevant patterns.
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Affiliation(s)
- Isabel Martinez-Tejada
- Clinic of Neurosurgery, Copenhagen University Hospital, Rigshospitalet, Copenhagen, Denmark. .,Department of Health Technology, Technical University of Denmark, Kongens Lyngby, Denmark.
| | - Alexander Arum
- Clinic of Neurosurgery, Copenhagen University Hospital, Rigshospitalet, Copenhagen, Denmark
| | - Jens E Wilhjelm
- Department of Health Technology, Technical University of Denmark, Kongens Lyngby, Denmark
| | - Marianne Juhler
- Clinic of Neurosurgery, Copenhagen University Hospital, Rigshospitalet, Copenhagen, Denmark
| | - Morten Andresen
- Clinic of Neurosurgery, Copenhagen University Hospital, Rigshospitalet, Copenhagen, Denmark
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