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Postural Effects on Intracranial Pressure as Assessed NoninvasivelyThis study was designed to investigate effects of whole body tilting on intracranial compliance and pressure in six healthy volunteers by using a noninvasive ultrasonic device. Subjects were randomly tilted up or down sequentially at 60 degree, 30 degree head-up, supine, and 15 degree head-down position for one minute at each angle. We measured arterial blood pressure with a finger pressure cuff and changes in intracranial distance with an ultrasonic device. The device measures skull movement on the order of micro-meter. Our ultrasound technique demonstrates that skull movement is highly correlated (r$(circumflex){2}$=0.77) with intracranial pressure variations due to cerebral arterial pulsation. The amplitudes of arterial pressure (r$(circumflex){2}$=0.99 and those of intracranial distance changes (r$(circumflex){2}$=0.87) associated with one cardiac cycle were inversely correlated with the angle of tilt. The ratio of pulsation amplitudes for intracranial distance over arterial pressure also showed a significant increase as the angle of tilt was lowered (p=0.003). Thus, postural changes alter intracranial compliance in healthy volunteers and intracranial volume-buffering capacity is reduced in head-down position.
Document ID
Document Type
Preprint (Draft being sent to journal)
Ueno, Toshiaki (NASA Ames Research Center Moffett Field, CA United States)
Hargens, Alan R. (NASA Ames Research Center Moffett Field, CA United States)
Ballard, R. E.
Shuer, L. M.
Cantrell, J. H.
Yost, W. T.
Holton, Emily M.
Date Acquired
August 20, 2013
Publication Date
January 1, 1997
Subject Category
Aerospace Medicine
Meeting Information
Experimental Biology 1998(San Francisco, CA)
Funding Number(s)
PROJECT: RTOP 199-80-02-05
Distribution Limits
Work of the US Gov. Public Use Permitted.