Association of Exercise and Swimming Goggles With Modulation of Cerebro-ocular Hemodynamics and Pressures in a Model of Spaceflight-Associated Neuro-ocular Syndrome

Scott, Jessica; Tucker, Wesley J.; Martin, David S.; Crowell, J. Brent; Goetchius, Elizabeth; Ozgur, Omar; Hamilton, Scott; Otto, Christian; Gonzales, Rebecca; Ritter, Monica; Newby, Nathanial; DeWitt, John K.; Stenger, Michael B.; Ploutz‐Snyder, Robert; Ploutz‐Snyder, Lori L.; Morgan, William H.; Haykowsky, Mark J.

doi:10.1001/jamaophthalmol.2019.0459

Cited by 35 publications

(24 citation statements)

References 47 publications

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“…In healthy subjects, HDT also led to change in pupil reactivity Supports pupil reactivity as a potential clinical sign of SANS Petersen 16 et al 2019 10 healthy volunteers Lower body negative pressure of 20mmHg lowered ICP without changing cerebral perfusion pressure in HDT Suggests lower body negative pressure is a possible countermeasure to raised ICP Petersen 17 et al 2019 8 healthy adult volunteers Lower body negative pressure suits reduced internal jugular vein cross-sectional area without affecting body temperature and mobility Lower body negative pressure suits may provide a countermeasure to cephalad venous blood volume shifts, which in turn may be a countermeasure to SANS Roberts 18 et al 2019 19 astronauts (7 SDSF, 12 LDSF) Astronauts who developed SANS had smaller changes in total ventricular volumes compared to those who did not Suggests the ventricular enlargement associated with SANS may not be a defining characteristic Salerni 19 et al 2019 Mathematical model of fluid flow in the eyes and brain, embedded into a simplified whole-body circulation model The model predicted increased ICP and IOP in microgravity. Ocular blood flow was predicted to decrease in the choroid and ciliary body circulations, whereas retinal circulation was found to be less susceptible to microgravity-induced alterations Supports theory that altered fluid flow in the brain and eye is involved in the pathophysiology of SANS and describes model which may be used to further our understanding of SANS Scott 21 et al 2019 20 health adult male volunteers Exercise in HDT was associated with decreased IOP and larger translaminar pressure gradient; wearing swimming goggles in HDT increased IOP and reduced the translaminar pressure gradient Suggests swimming goggles may be a countermeasure to SANS by reducing the translaminar pressure gradient van Ombergen 15 et al 2019 11 LDSF astronauts and 11 age/gender/education-matched controls Lateral, third and fourth ventricles increased in volume after spaceflight. The ventricular volume decreased after 7 months post missio...…”

Section: Resultsmentioning

confidence: 58%

“…The study did not measure intracranial pressure and further work is pending to expand upon the initial results. Scott et al 21 evaluated commercially-available swimming goggles and the effect of exercise during HDT. They found that goggle wear could modestly increase IOP by 1.9 mmHg and counteract elevated ICP by reducing the predicted translaminar pressure gradient in HDT and LDSF.…”

Section: Resultsmentioning

confidence: 99%

See 1 more Smart Citation

<p>Spaceflight Associated Neuro-Ocular Syndrome (SANS): A Systematic Review and Future Directions</p>

Paez¹,

Mudie²,

Subramanian³

2020

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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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Section: Resultsmentioning

confidence: 58%

Section: Resultsmentioning

confidence: 99%

<p>Spaceflight Associated Neuro-Ocular Syndrome (SANS): A Systematic Review and Future Directions</p>

Paez¹,

Mudie²,

Subramanian³

2020

View full text Add to dashboard Cite

show abstract

“…The search methods resulted in 67 articles. After removal of duplicates, 15 [45,46,50,53,[60][61][62][63][64][65][66][67][68][69] articles were identified in PubMed and 5 [47,51,[70][71][72] new articles in CINAHL. During the initial screening of titles/abstracts, 11 articles were excluded due to HIIE not being the primary experimental protocol performed (n = 6), studies not measuring cerebral arteries (n = 4) and an animal study (n = 1).…”

Section: Resultsmentioning

confidence: 99%

Effects of high intensity interval exercise on cerebrovascular function: A systematic review

et al. 2020

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High intensity interval exercise (HIIE) improves aerobic fitness with decreased exercise time compared to moderate continuous exercise. A gap in knowledge exists regarding the effects of HIIE on cerebrovascular function such as cerebral blood velocity and autoregulation. The objective of this systematic review was to ascertain the effect of HIIE on cerebrovascular function in healthy individuals. We searched PubMed and the Cumulative Index to Nursing and Allied Health Literature databases with apriori key words. We followed the Preferred Reporting Items for Systematic Reviews. Twenty articles were screened and thirteen articles were excluded due to not meeting the apriori inclusion criteria. Seven articles were reviewed via the modified Sackett’s quality evaluation. Outcomes included middle cerebral artery blood velocity (MCAv) (n = 4), dynamic cerebral autoregulation (dCA) (n = 2), cerebral de/oxygenated hemoglobin (n = 2), cerebrovascular reactivity to carbon dioxide (CO 2 ) (n = 2) and cerebrovascular conductance/resistance index (n = 1). Quality review was moderate with 3/7 to 5/7 quality criteria met. HIIE acutely lowered exercise MCAv compared to moderate intensity. HIIE decreased dCA phase following acute and chronic exercise compared to rest. HIIE acutely increased de/oxygenated hemoglobin compared to rest. HIIE acutely decreased cerebrovascular reactivity to higher CO 2 compared to rest and moderate intensity. The acute and chronic effects of HIIE on cerebrovascular function vary depending on the outcomes measured. Therefore, future research is needed to confirm the effects of HIIE on cerebrovascular function in healthy individuals and better understand the effects in individuals with chronic conditions. In order to conduct rigorous systematic reviews in the future, we recommend assessing MCAv, dCA and CO 2 reactivity during and post HIIE.

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“…However, implementation of NASA's integrated resistance and aerobic training (iRAT) protocol during 70-day non-hypercarbic strict 6° HDTBR was not associated with a significant difference in retinal thickening or signs of optic disc edema compared to a control HDTBR group who did not exercise, though IOP was slightly higher (<1 mm Hg) in the exercise group ( 68 ). Interestingly, 15° head down tilt for less than an hour was associated with a decrease in IOP in subjects undergoing either moderate-intensity aerobic, resistance, or high-intensity interval aerobic exercise ( 69 ). These differences highlight how the impacts of countermeasures are affected by the duration and angle of HDTBR.…”

Section: Countermeasure Testing and Monitoring Development In Head-down Tilt Bed Restmentioning

confidence: 99%

Head-Down Tilt Bed Rest Studies as a Terrestrial Analog for Spaceflight Associated Neuro-Ocular Syndrome

2021

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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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Association of Exercise and Swimming Goggles With Modulation of Cerebro-ocular Hemodynamics and Pressures in a Model of Spaceflight-Associated Neuro-ocular Syndrome

Cited by 35 publications

References 47 publications

<p>Spaceflight Associated Neuro-Ocular Syndrome (SANS): A Systematic Review and Future Directions</p>

<p>Spaceflight Associated Neuro-Ocular Syndrome (SANS): A Systematic Review and Future Directions</p>

Effects of high intensity interval exercise on cerebrovascular function: A systematic review

Head-Down Tilt Bed Rest Studies as a Terrestrial Analog for Spaceflight Associated Neuro-Ocular Syndrome

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