Updates on Spaceflight-Associated Neuro-Ocular Syndrome: Intracranial Changes

In this review, we discuss current hypotheses on the pathophysiology of spaceflight-induced neuro-ocular syndrome and recent findings regarding microgravity-induced changes in venous, lymphatic, and glymphatic flow. We propose that spaceflight-associated neuro-ocular syndrome (SANS) may not be explained entirely by intracranial pressure changes only and instead is likely multifactorial including cephalad fluid shifts and fluid outflow obstruction as possible inciting mechanism for the characteristic signs and symptoms of this syndrome. In all, we urge a multifactorial view of SANS whereby predisposing, intrinsic, and extrinsic factors must all be considered.