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Project Title:  Human Cerebral Vascular Autoregulation and Venous Outflow in Response to Microgravity-Induced Cephalad Fluid Redistribution Reduce
Fiscal Year: FY 2013 
Division: Human Research 
Research Discipline/Element:
HRP HHC:Human Health Countermeasures
Start Date: 11/15/2012  
End Date: 05/15/2013  
Task Last Updated: 01/02/2013 
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Principal Investigator/Affiliation:   Roberts, Donna  M.D. / Medical University of South Carolina 
Address:  Department of Radiology 
169 Ashley Avenue, POB 250322 
Charleston , SC 29425-8905 
Phone: 843-792-4932  
Congressional District:
Organization Type: UNIVERSITY 
Organization Name: Medical University of South Carolina 
Joint Agency:  
Alperin, Noam  University of Miami, Medical Campus 
Brown, Truman  Medical University of South Carolina 
Helpern, Joseph  Medical University of South Carolina 
Jensen, Jen  Medical University of South Carolina 
Studholme, Colin  University of Washington, Seattle 
Tabesh, Ali  Medical University of South Carolina 
Wagner, Mark  Medical University of South Carolina 
Project Information: Grant/Contract No. NNX13AC32G 
Responsible Center: NASA JSC 
Grant Monitor: Villarreal, Jennifer  
Center Contact: 281-483-7306 
Solicitation / Funding Source: 2011 Crew Health NNJ11ZSA002NA 
Grant/Contract No.: NNX13AC32G 
Project Type: GROUND 
Flight Program:  
TechPort: No 
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Human Research Program Elements: (1) HHC:Human Health Countermeasures
Human Research Program Risks: (1) VIIP:Risk of Spaceflight-Induced Intracranial Hypertension/Vision Alterations (IRP Rev E)
Human Research Program Gaps: (1) VIIP01:We do not know the etiological mechanisms and contributing risk factors for ocular structural and functional changes seen in-flight and postflight (IRP Rev E)
Task Description: According to the NASA Human Research Roadmap (Risk of Microgravity-Induced Visual Impairment/Intracranial Pressure; Gaps VIIP2, VIIP4, VIIP5, VIIP8) and further expounded upon in the Visual Impairment Intracranial Pressure (ICP) Summit Report (May 2011), an essential gap exists in our knowledge of intracranial pressure regulation in spaceflight. This is exemplified by the fact that there are no published studies investigating the structural and functional changes occurring as a result of long-term spaceflight and there is almost no data concerning cerebral autoregulation in astronauts following return from space. Only two published studies exist investigating cerebral autoregulation in astronauts using an indirect method for measuring CBF at the level of the major arteries of the circle of Willis. Thus, although cerebrovascular hemodynamics plays a crucial role in ICP regulation and also in the response to orthostatic stress, we have almost no knowledge of the state of cerebral autoregulatory mechanisms during spaceflight.

The operational relevance of this gap according to the NASA Human Research Roadmap is that elevated ICP and likely associated vision 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 will allow us 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.

In order to fully characterize intracranial adaptation to long-term microgravity, we will use magnetic resonance imaging (MRI) which is the terrestrial gold standard. MRI allows direct visualization and functional characterization of the intracranial contents. Indeed, MR imaging is the clinical standard of care in evaluating patients with idiopathic intracranial hypertension. We will use a suite of advanced MRI sequences to: (1.) characterize weightlessness-induced intracranial compartmental fluid volume changes at the macroscopic (brain, CSF, orbit), microscopic (brain tissue water) and vascular (arterial and venous) levels following adaptation to long-term spaceflight and (2.) assess for potential resultant hemodynamic changes (cerebral perfusion) in the brain. This proposal represents the most relevant and advanced suit of MRI techniques for the characterization of intracranial compartmental fluid and hemodynamic changes induced by long-term microgravity. The specific sequences will be carried out by the recognized experts in each area and in most cases, the developer of the specific technique.

It is imperative to obtain this data in order to have an understanding of what is happening to the brain and orbits while living and working in microgravity. We are only now realizing the consequences of this lack of knowledge. This data will serve as the basis for the development of fundamental theories describing intracranial adaptation to microgravity. It may help establish a risk stratification strategy based on intracranial anatomy, dural venous sinus and jugular vessel outflow, cranial compliance, and cerebral vascular autoregulation. Importantly, it will serve as a basis for interpretation of in-flight data collected via other techniques such as ultrasound, the primary in-flight imaging modality.

Research Impact/Earth Benefits: 0

Task Progress & Bibliography Information FY2013 
Task Progress: NOTE that project continues as "Human Cerebral Vascular Autoregulation and Venous Outflow in Response to Microgravity-Induced Cephalad Fluid Redistribution--NNX13AJ92G" WITH THE SAME PRINCIPAL INVESTIGATOR; PERIOD OF PERFORMANCE IS 5/16/2013-5/15/2019. SEE THAT PROJECT FOR SUBSEQUENT REPORTING. (Ed., 6/14/13)

New project for FY2013 in November 2012.

Bibliography Type: Description: (Last Updated: 08/12/2021) 

Show Cumulative Bibliography Listing
 None in FY 2013