Linking cerebral hemodynamics and ocular microgravity-induced alterations through an in silico-in vivo head-down tilt framework
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abstract
AbstractHead-down tilt (HDT) has been widely proposed as terrestrial analogue of microgravity and used also to investigate the occurrence of the spaceflight associated neuro-ocular syndrome (SANS), which is currently considered one of the major health risks for human spaceflight. We propose here a novel, in vivo validated numerical framework to simulate the acute ocular-cerebrovascular response to 6 HDT and to explore the etiology and pathophysiology of SANS. The model links cerebral and ocular posture-induced hemodynamics, simulating the response of the main cerebrovascular mechanisms, as well as the relationship between intracranial and intraocular pressure to HDT. Our results from short-term (10 min) 6 HDT show increased hemodynamic pulsatility in the proximal-to-distal/capillary-venous cerebral direction, a marked decrease (-43%) in ocular translaminar pressure, and an increase (+31%) in ocular perfusion pressure, suggesting a plausible explanation of the underlying mechanisms at the onset of ocular globe deformation and edema formation over longer time scales.
