1
|
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).
Collapse
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
| |
Collapse
|
2
|
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.
Collapse
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
| |
Collapse
|
3
|
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.
Collapse
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.
| |
Collapse
|
4
|
Wostyn P, Mader TH, Gibson CR, Nedergaard M. Does Long-Duration Exposure to Microgravity Lead to Dysregulation of the Brain and Ocular Glymphatic Systems? Eye Brain 2022; 14:49-58. [PMID: 35546965 PMCID: PMC9081191 DOI: 10.2147/eb.s354710] [Citation(s) in RCA: 7] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/03/2022] [Accepted: 04/27/2022] [Indexed: 02/05/2023] Open
Abstract
Spaceflight-associated neuro-ocular syndrome (SANS) has been well documented in astronauts both during and after long-duration spaceflight and is characterized by the development of optic disc edema, globe flattening, choroidal folds, and hyperopic refractive error shifts. The exact mechanisms underlying these ophthalmic abnormalities remain unclear. New findings regarding spaceflight-associated alterations in cerebrospinal fluid spaces, specifically perivascular spaces, may shed more light on the pathophysiology of SANS. The preliminary results of a recent brain magnetic resonance imaging study show that perivascular spaces enlarge under prolonged microgravity conditions, and that the amount of fluid in perivascular spaces is linked to SANS. The exact pathophysiological mechanisms underlying enlargement of perivascular spaces in space crews are currently unclear. Here, we speculate that the dilation of perivascular spaces observed in long-duration space travelers may result from impaired cerebral venous outflow and compromised cerebrospinal fluid resorption, leading to obstruction of glymphatic perivenous outflow and increased periarterial cerebrospinal fluid inflow, respectively. Further, we provide a possible explanation for how dilated perivascular spaces can be associated with SANS. Given that enlarged perivascular spaces in space crews may be a marker of altered venous hemodynamics and reduced cerebrospinal fluid outflow, at the level of the optic nerve and eye, these disturbances may contribute to SANS. If confirmed by further studies, brain glymphatic dysfunction in space crews could potentially be considered a risk factor for the development of neurodegenerative diseases, such as Alzheimer’s disease. Furthermore, long-duration exposure to microgravity might contribute to SANS through dysregulation of the ocular glymphatic system. If prolonged spaceflight exposure causes disruption of the glymphatic systems, this might affect the ability to conduct future exploration missions, for example, to Mars. The considerations outlined in the present paper further stress the crucial need to develop effective long-term countermeasures to mitigate SANS-related physiologic changes during long-duration spaceflight.
Collapse
Affiliation(s)
- Peter Wostyn
- Department of Psychiatry, PC Sint-Amandus, Beernem, Belgium
- Correspondence: Peter Wostyn, Department of Psychiatry, PC Sint-Amandus, Reigerlostraat 10, Beernem, 8730, Belgium, Tel +32-472713719, Fax +32-50-819720, Email
| | | | - Charles Robert Gibson
- Coastal Eye Associates, Webster, TX, USA
- KBR, NASA Space Medicine Operations Division, Houston, TX, USA
| | - Maiken Nedergaard
- Center for Translational Neuromedicine, Faculty of Health and Medical Sciences, University of Copenhagen, Copenhagen, Denmark
- Center for Translational Neuromedicine, University of Rochester Medical Center, Rochester, NY, USA
| |
Collapse
|
5
|
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.
Collapse
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
| |
Collapse
|
6
|
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.
Collapse
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
| |
Collapse
|
7
|
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.
Collapse
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
| | | |
Collapse
|