有了未来长期载人勘探的计划,NASA已经确定了太空宇航员面临的几种高度优先的潜在健康风险。一种这样的风险是神经和眼科发现的集合,称为航天相关的神经眼综合征(SANS)。SANS的发现包括视盘水肿,地球变平,视网膜神经纤维层增厚,脉络膜视网膜褶皱,远视偏移,和棉绒斑点。SANS的原因最初被认为是微重力下的头颅液移位导致颅内压升高,静脉淤滞和脑脊液流出受损,但SANS的确切病因仍不明确。最近的研究已经探索了SANS的多种可能的致病机制,包括遗传和激素因素;微重力下液体向眼眶和大脑的头颅移位;以及脑淋巴系统的破坏。轨道,眼,和头颅成像,在地球和太空中,SANS的诊断和监测都至关重要(例如,眼底摄影,光学相干断层扫描(OCT),磁共振成像(MRI),和眼眶/颅脑超声)。此外,我们重点介绍了近红外光谱和扩散张量成像,两种新的模式在未来的SANS研究中具有潜在的用途。在这份手稿中,我们对这些模式进行了回顾,概述它们在太空和地球上的当前和潜在用途,并回顾SANS的主要影像学发现。
With plans for future long-duration crewed exploration, NASA has identified several high priority potential health risks to
astronauts in space. One such risk is a collection of neurologic and ophthalmic findings termed spaceflight associated neuro-ocular syndrome (SANS). The findings of SANS include optic disc edema, globe flattening, retinal nerve fiber layer thickening, chorioretinal folds, hyperopic shifts, and cotton-wool spots. The cause of SANS was initially thought to be a cephalad fluid shift in microgravity leading to increased intracranial pressure, venous stasis and impaired CSF outflow, but the precise etiology of SANS remains ill defined. Recent studies have explored multiple possible pathogenic mechanisms for SANS including genetic and hormonal factors; a cephalad shift of fluid into the orbit and brain in microgravity; and disruption to the brain glymphatic system. Orbital, ocular, and cranial imaging, both on Earth and in space has been critical in the diagnosis and monitoring of SANS (e.g., fundus photography, optical coherence tomography (OCT), magnetic resonance imaging (MRI), and orbital/cranial ultrasound). In addition, we highlight near-infrared spectroscopy and diffusion tensor imaging, two newer modalities with potential use in future studies of SANS. In this manuscript we provide a review of these modalities, outline their current and potential use in space and on Earth, and review the reported major imaging findings in SANS.