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Ultrasound measurement of transcranial distance during head-down tiltExposure to microgravity elevates blood pressure and flow in the head, which may increase intracranial volume (ICV) and intracranial pressure (ICP). Rhesus monkeys exposed to simulated microgravity in the form of 6 degree head-down tilt (HDT) experience elevated ICP. With humans, twenty-four hours of 6 degree HDT bed rest increases cerebral blood flow velocity relative to pre-HDT upright posture. Humans exposed to acute 6 degree HDT experiments increased ICP, measured with the tympanic membrane displacement (TMD) technique. Other studies suggest that increased ICP in humans and cats causes measurable cranial bone movement across the sagittal suture. Due to the slightly compliant nature of the cranium, elevation of the ICP will increase ICV and transcranial distance. Currently, several non-invasive approaches to monitor ICP are being investigated. Such techniques include TMD and modal analysis of the skull. TMD may not be reliable over a large range of ICP and neither method is capable of measuring the small changes in pressure. Ultrasound, however, may reliably measure small distance changes that accompany ICP fluctuations. The purpose of our study was to develop and evaluate an ultrasound technique to measure transcranial distance changes during HDT.
Document ID
19960021732
Document Type
Conference Paper
Authors
Torikoshi, S. (NASA Ames Research Center Moffett Field, CA United States)
Wilson, M. H. (NASA Ames Research Center Moffett Field, CA United States)
Ballard, R. E. (NASA Ames Research Center Moffett Field, CA United States)
Watenpaugh, D. E. (NASA Ames Research Center Moffett Field, CA United States)
Murthy, G. (NASA Ames Research Center Moffett Field, CA United States)
Yost, W. T. (NASA Langley Research Center Hampton, VA United States)
Cantrell, J. H. (NASA Langley Research Center Hampton, VA United States)
Chang, D. S. (NASA Ames Research Center Moffett Field, CA United States)
Hargens, A. R. (NASA Ames Research Center Moffett Field, CA United States)
Date Acquired
August 17, 2013
Publication Date
January 1, 1995
Publication Information
Publication: Journal of Gravitational Physiology, Volume 2, No. 1
Subject Category
Aerospace Medicine
Funding Number(s)
PROJECT: RTOP 199-14-12-04
Distribution Limits
Public
Copyright
Work of the US Gov. Public Use Permitted.
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