| Identifier |
space_flight_associated_neuro_ocular_syndrome |
| Title |
Spaceflight-Associated Neuro-Ocular Syndrome |
| Creator |
Andrew G. Lee, MD; Alay Shah |
| Affiliation |
(AGL) Chairman, Department of Ophthalmology, The Methodist Hospital, Houston, Texas; Professor of Ophthalmology, Weill Cornell Medicine, New York City, New York; (AS) Class of 2022, Baylor College of Medicine, Houston, Texas |
| Subject |
Spaceflight; Fluid; IIH, Papilledema |
| Description |
Summary: • Spaceflight-associated neuro-ocular syndrome (SANS) is a constellation of findings that are a result of cephalad and orbital fluid shift in response to loss of normal gravitational forces associated with long spaceflights. This net cephalad flow is responsible for the following findings: o Optic disc edema in one or both eyes: often asymmetric, Frisen grades of 1-3 o Choroidal folds o Hyperopic shift due to globe flattening o Cotton-wool spots (not seen in IIH) o Transient refractive error that goes away after return to Earth • MRI and ultrasounds show fluid in the optic sheath and orbit, causing the above findings. • Head down tilt studies and idiopathic intracranial hypertension are used for comparison but are not perfect analogues. • The cause of SANS is still unknown and further studies are ongoing to understand the influence of the microgravity environment on hemodynamics and CSF fluid dynamics, in preparation for long manned spaceflights. |
| Transcript |
So, we're going to be talking about SANS today. SANS stands for spaceflight-associated neuro-ocular syndrome. It's called that because after long-duration spaceflight on the International Space Station, six months or more on the station, we have seen an associated neuro-ocular syndrome that is unique to spaceflight and the findings that we're seeing are optic disc edema in one or both eyes (but it's often asymmetric), a variable Frisen grades of disc edema (one, two, three) but we really don't see four and five level Frisens. We see choroidal folds and that produces a hyperopic shift because the eye is getting shorter because their retinas getting closer to the front of the eye. So, this is hyperopic refractive shift - just seeing it near. And we have had cotton wool spots. MRIs and ultrasounds of patients with SANS show fluid in the sheath and a cephalad and orbital fluid shift that produces the disc edema and the choroidal folds and the secondary hyperopic shift. Ultrasound also confirmed similar findings. Spinal taps have been done on these patients, which show borderline elevated opening pressures after they return to Earth from the station. So basically, what is happening is there's a cephalad fluid shift. We can see that on MRI as well. The whole brain is shifting upward as well as an orbital fluid shift, fluid in the sheath, flattening of the globe and that's caused by the loss of the 1g terrestrial gravitational field that pulls the eye out. So, everything moves up into the chest and into the head and without the gravitational field that can't get back out. I haven't seen any patients lose any vision permanently, although there is a transient refractive error shift and, after return to Earth, it goes away. There's no good terrestrial analogue for this. We do have head down tilt studies where patients are in the head down position and that can generate the same kind of cephalad fluid shift and there's been OCT changes and other changes that are similar to but not the quite the same as SANS and certainly not of the same severity and the closest analogue that we have on earth to SANS is idiopathic intracranial hypertension which superficially shares some of the features: the optic disc edema, choroidal folds, hyperopic shift, not the cotton wool spots obviously. But as you know, most IIH patients are obese young females and our SANS cohort is mostly male, few females, and definitely not obese patients. So, spaceflight-associated neuro-ocular syndrome; it's a new syndrome characterized by a cephalad orbital fluid shift that superficially looks like some of the features we see in IIH: optic disc edema, choroidal folds, and hyperopic shift. We really still don't know what causes it and we're working on it. Longitudinal studies are ongoing to try and determine if we can see what the causes and how the terrestrial-g environment alters the hemodynamics and the CSF fluid dynamics of astronauts flying, in preparation for exploring the asteroid belt and potentially a manned mission to Mars. |
| Date |
2019-10 |
| Language |
eng |
| Format |
video/mp4 |
| Type |
Image/MovingImage |
| Collection |
Neuro-Ophthalmology Virtual Education Library: Andrew G. Lee Collection: https://novel.utah.edu/Lee/ |
| Publisher |
North American Neuro-Ophthalmology Society |
| Holding Institution |
Spencer S. Eccles Health Sciences Library, University of Utah |
| Rights Management |
Copyright 2019. For further information regarding the rights to this collection, please visit: https://NOVEL.utah.edu/about/copyright |
| ARK |
ark:/87278/s6jq5rjw |
| Setname |
ehsl_novel_lee |
| ID |
1469326 |
| Reference URL |
https://collections.lib.utah.edu/ark:/87278/s6jq5rjw |
