Spaceflight associated neuro-ocular syndrome (SANS): an update on potential microgravity-based pathophysiology and mitigation development

Ong, Joshua; Mader, Thomas H.; Gibson, Charles R.; Mason, Sara S.; Lee, Andrew G.

doi:10.1038/s41433-023-02522-y

Cited by 18 publications

(3 citation statements)

References 58 publications

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“…Nevertheless, it is worth noting that IIH is additionally distinguished by the occurrence of persistent headaches, double vision (diplopia), and pulsating ringing in the ears (pulsatile tinnitus), which are clinical aspects that have not been extensively documented/reported among SANS astronauts. Moreover, the SANS condition is characterized by the presence of asymmetric or unilateral ODE, while IIH typically manifests with bilateral ODE [ 1 , 15 ]. Furthermore, opening pressures on post-flight lumbar punctures in astronauts with SANS revealed only mildly elevated postflight ICP of a significant value observed in terrestrial IIH, although no lumbar punctures have been performed during spaceflight to date.…”

Section: Spaceflight-associated Neuro-ocular Syndrome (Sans)mentioning

confidence: 99%

Artificial Intelligence Frameworks to Detect and Investigate the Pathophysiology of Spaceflight Associated Neuro-Ocular Syndrome (SANS)

Ong,

Waisberg,

Masalkhi

et al. 2023

Brain Sciences

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Spaceflight associated neuro-ocular syndrome (SANS) is a unique phenomenon that has been observed in astronauts who have undergone long-duration spaceflight (LDSF). The syndrome is characterized by distinct imaging and clinical findings including optic disc edema, hyperopic refractive shift, posterior globe flattening, and choroidal folds. SANS serves a large barrier to planetary spaceflight such as a mission to Mars and has been noted by the National Aeronautics and Space Administration (NASA) as a high risk based on its likelihood to occur and its severity to human health and mission performance. While it is a large barrier to future spaceflight, the underlying etiology of SANS is not well understood. Current ophthalmic imaging onboard the International Space Station (ISS) has provided further insights into SANS. However, the spaceflight environment presents with unique challenges and limitations to further understand this microgravity-induced phenomenon. The advent of artificial intelligence (AI) has revolutionized the field of imaging in ophthalmology, particularly in detection and monitoring. In this manuscript, we describe the current hypothesized pathophysiology of SANS and the medical diagnostic limitations during spaceflight to further understand its pathogenesis. We then introduce and describe various AI frameworks that can be applied to ophthalmic imaging onboard the ISS to further understand SANS including supervised/unsupervised learning, generative adversarial networks, and transfer learning. We conclude by describing current research in this area to further understand SANS with the goal of enabling deeper insights into SANS and safer spaceflight for future missions.

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Section: Spaceflight-associated Neuro-ocular Syndrome (Sans)mentioning

confidence: 99%

Artificial Intelligence Frameworks to Detect and Investigate the Pathophysiology of Spaceflight Associated Neuro-Ocular Syndrome (SANS)

Ong,

Waisberg,

Masalkhi

et al. 2023

Brain Sciences

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“…SANS is a unique constellation of neuro-ophthalmic findings observed in astronauts during and after long-duration space missions. SANS was first described by Mader et al in 2011 [1,3], but extensive research since then has been conducted by the National Aeronautics and Space Administration (NASA) on SANS [4,5]. The exact cause of SANS remains illdefined [6]; however, a growing body of evidence suggests multiple potential risk factors.…”

Section: Spaceflight-associated Neuro-ocular Syndromementioning

confidence: 99%

Intraocular Pressure during Spaceflight and Risk of Glaucomatous Damage in Prolonged Microgravity

Masalkhi,

Ong,

Waisberg

et al. 2023

Encyclopedia

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Microgravity introduces diverse pathological and various physiological changes to the human body, including intraocular pressure. Astronauts may develop a constellation of symptoms and signs including optic disc edema, choroidal folds, and a hyperopic shift from the flattening of the globe. These ocular findings have been collectively termed spaceflight-associated neuro-ocular syndrome (SANS). SANS is a condition that is unique to long-duration spaceflight. The precise pathogenesis of SANS remains ill-defined, but several hypotheses have been proposed that may be influenced by intraocular pressure. Countermeasures for SANS research also include techniques that impact intraocular pressure. In this article, we discuss intraocular pressure during spaceflight, the translaminar pressure gradient, SANS and potential SANS countermeasures, and the potential for glaucomatous damage during spaceflight.

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“…4 Fluid shifts towards the cephalic region during microgravity have also been speculated to contribute towards space ight associated neuro-ocular syndrome (SANS). 5 SANS is a distinct, microgravity-induced phenomenon of neuro-ophthalmic ndings observed in astronauts following long-duration space ight including choroidal folds, optic disc edema, posterior globe attening, refractive shift, and cerebral uid shifts noted to be persistent at 6 month postight MRI scans. SANS has been identi ed as a "red" risk based on occurrence probability and its impact on mission performance and human health.…”

Section: Introductionmentioning

confidence: 99%

Assessing non-invasive imaging devices to detect temperature differentiation and lymphatic/venous flow to the head and neck during head down tilt, supine, and sitting positions The NIID Study (non-invasive imaging device)

Melin,

Barnhart,

Aviles

et al. 2023

Preprint

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Under the influence of standard developmental physiology on the Earth’s surface (1 gravity equivalent known as “1G”), 70% of body fluids reside below the level of the heart.Fluid shifts towards the cephalic region during microgravity have also been speculated to contribute towards spaceflight associated neuro-ocular syndrome (SANS).Although a significant barrier to spaceflight, the underlying mechanism of SANS is not well understood, partially due to the spaceflight environment and limited medical capabilities including invasive diagnostic testing. Thus, non-invasive approaches to studying real-time fluid shifts in weightlessness could serve as critical areas of research to further SANS study and effective countermeasure protocol development. For continuous fluid shift monitoring and management, the goal is to establish baseline assessments utilizing real time point of care noninvasive imaging devices (NIID). NIID will first need to be quantified and validated through ground-based analogues, with subsequent acquisition of near continuous imaging from arrival in the weightlessness of LEO and during the time of adaptation, which may be variable among crew members. The purpose of this study was to examine temperature differential alterations, superficial venous flow patterns (head, neck, upper torso), and venous flow patterns along the lymphatic ventromedial bundles of the medial calves and thighs. Imaging was obtained in three different positions using three standards of care medical NIIDs: SnapShotTM by Kent Imaging, Scout by WoundVisionTM and LymphScannerTM by Delfin. 30 volunteers were assessed for temperature and lymphatic/venous flow using three different non-invasive devices that can measure temperature, perfusion, and image the lymphatic and venous structures. The volunteers were assessed in the sitting, supine, and 6-degree head down tilt (HDT) positions, with pre/post assessments for the HDT position. Venous and lymphatic flow patterns may vary upon position changes (sitting vs. supine vs. 6-degree head down tilt), and in response to MLD performance in the treatment group. Fifteen subjects per group (N = 30) completed all visits and were used in the full analysis. The sitting and supine position data did not show statistical significance at any of the time points and with the devices used. The HDT data from SnapShot (looking at perfusion, deoxy and oxyhemoglobin) and Wound Vision Scout (thermal imaging) did not show statistical significance between the control and treatment groups at any time points. No significant difference for any of the within-group comparisons were found with the Lymphscanner. A significant reduction in left temple TDC for the treatment group was found at post-30-minutes (5.77, 95% CI: 1.24, 10.30) and post-180-minutes. A significant reduction in right subclavicular TDC for the treatment group was found at post-180-Minutes (5.09, 95% CI: 0.16, 10.03). A significant increase in the left ventromedial bundle for the treatment group was found at post-90-Minutes (5.72, 95% CI: 0.34, 11.10) and post-120-Minutes (5.85, 95% CI: 0.47, 11.23). A significant increase in the right ventromedial bundle for the treatment group was found at post-90 minutes (5.53, 95% CI: 0.21, 10.84). This is the first HDT spaceflight analogue study, to our knowledge, in which dermal fluid shifts were evaluated using point-of-care noninvasive imaging modalities including Near Infrared Spectroscopy (NIRS), thermography and a subcutaneous edema monitor, with subsequent application of manual lymphatic drainage (MLD) techniques to stimulate dermal lymphatic function as a countermeasure and mitigation therapeutic for intervention in cephalad fluid shifts. Further validating studies are indicated for NIIDs to further quantify fluid shifts in both analogues and weightlessness.

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Spaceflight associated neuro-ocular syndrome (SANS): an update on potential microgravity-based pathophysiology and mitigation development

Cited by 18 publications

References 58 publications

Artificial Intelligence Frameworks to Detect and Investigate the Pathophysiology of Spaceflight Associated Neuro-Ocular Syndrome (SANS)

Artificial Intelligence Frameworks to Detect and Investigate the Pathophysiology of Spaceflight Associated Neuro-Ocular Syndrome (SANS)

Intraocular Pressure during Spaceflight and Risk of Glaucomatous Damage in Prolonged Microgravity

Assessing non-invasive imaging devices to detect temperature differentiation and lymphatic/venous flow to the head and neck during head down tilt, supine, and sitting positions The NIID Study (non-invasive imaging device)

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