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Human Cerebral Vascular Autoregulation and Venous Outflow in Response to Microgravity-induced Cephalad Fluid Redistribution (Cephalad_Fluid)
Principal Investigator
Research Area:
Biomedical countermeasures
Species Studied
Scientific Name: Homo sapiens Species: Human


It’s likely that elevated intracranial pressure (ICP) and associated visual disturbances due to microgravity exposure are serious health risks for astronauts. Furthermore, this is an even greater concern for potential longer duration missions such as to the moon or Mars where decreased vision may impact mission performance and may even require early mission termination. Permanent visual losses may result in lifetime disability issues. Almost certainly, during long-term flights, as the hydrostatic pressure gradients due to gravity are abolished with resultant large cephalad fluid shifts, an intracranial adaptive response occurs. Thus direct measurements of cerebral fluid shifts and cerebral hemodynamics as proposed in this study allowed investigators to more fully characterize the intracranial compartment guiding the development of preventive measures, such as specific pharmacological countermeasures, to combat the development and sequelae of increased ICP during future missions.

Idiopathic intracranial hypertension, or pseudotumor cerebri, is a poorly understood clinical condition of unknown etiology. It has a reported incidence of between one and five cases per 100,000 people in the general population, although the true incidence may be larger. There is a strong female predominance. Patients typically present with disabling headaches and vision changes. In more extreme cases, injury to the optic nerve can occur and patients can experience vision loss. Upon testing, these patients have increased intracranial pressure and swelling of the optic nerves. Similar symptoms can occur in astronauts following long-term space flight. This study provided a unique opportunity to investigate the underlying pathophysiology of abnormal intracranial pressure regulation which was applicable to those who suffer from this Earth-based condition. This research also shed light on the pathophysiology of other Earth-based disease processes associated with abnormal cerebral spinal fluid (CSF) flow or venous outflow obstruction such as obstructive hydrocephalus, normal pressure hydrocephalus and multiple sclerosis, and pathologies associated with altered cerebral autoregulation such as traumatic brain injury.

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Cerebrospinal fluid
Intracranial pressure
Magnetic resonance imaging (MRI)
Paranasal sinuses

Data Information
Data Availability
Archive is complete. Data sets are not publicly available but can be requested.
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Jugular venous outflow
Brain ventricular volume
Cerebral perfusion
Cerebral vascular changes
Intracranial volume
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Mission/Study Information
Mission Launch/Start Date Landing/End Date Duration
Ground 05/01/2009 In Progress

Human Research Program (HRP) Human Research Roadmap (HRR) Information
Crew health and performance is critical to successful human exploration beyond low Earth orbit. The Human Research Program (HRP) investigates and mitigates the highest risks to human health and performance, providing essential countermeasures and technologies for human space exploration. Risks include physiological and performance effects from hazards such as radiation, altered gravity, and hostile environments, as well as unique challenges in medical support, human factors, and behavioral health support. The HRP utilizes an Integrated Research Plan (IRP) to identify the approach and research activities planned to address these risks, which are assigned to specific Elements within the program. The Human Research Roadmap is the web-based tool for communicating the IRP content.

The Human Research Roadmap is located at:

+ Click here for information of how this experiment is contributing to the HRP's path for risk reduction.

Additional Information
Managing NASA Center
Johnson Space Center (JSC)
Responsible NASA Representative
Institutional Support
National Aeronautics and Space Administration (NASA)
Alternate Experiment Name
Proposal Date
Proposal Source
2011 Crew Health NNJ11ZSA002NA