Comparison of Dural Venous Sinus Volumes Before and After Flight in Astronauts With and Without Spaceflight-Associated Neuro-Ocular Syndrome.

Importance: Spaceflight-associated neuro-ocular syndrome (SANS) occurs in 40% to 60% of National Aeronautics and Space Administration (NASA) International Space Station (ISS) astronauts who present postflight with ophthalmological findings and elevated intracranial pressure. The etiology of SANS is unknown; it is hypothesized that venous outflow congestion from the head and neck occurs because of microgravity, which is supported by the finding of internal jugular vein stagnant flow and thrombosis in some astronauts, but the impact on intracranial dural venous sinus structures remains unknown.

Objectives: To clarify the potential risk of retrograde extension of clot intracranially among astronauts with internal jugular venous thrombosis by evaluating intracranial venous structures following spaceflight and to assess for any association between intracranial venous congestion and SANS.