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Distortion Product Otoacoustic Emissions and Intracranial Pressure During CSF Infusion Testing
Michael A Williams1, Jan Malm, Anders Eklund
1Departments of Neurology and Neurological Surgery, University of Washington School of Medicine, Seattle, WA, USA.
Aerospace Medicine and Human Performance
|September 24, 2016
Summary
Distortion product otoacoustic emissions (DPOAEs) show significant changes with elevated intracranial pressure (ICP). This suggests DPOAEs may offer a noninvasive method for monitoring ICP, crucial for astronaut health in spaceflight.
Area of Science:
- Otoacoustic emissions research
- Space medicine
- Neurology
Background:
- Astronauts on long space missions face risks of Visual Impairment/Intracranial Pressure syndrome.
- A noninvasive method to monitor intracranial pressure (ICP) is needed for these astronauts.
- Distortion product otoacoustic emissions (DPOAEs) were investigated as a potential noninvasive ICP monitoring tool.
Purpose of the Study:
- To assess the validity of DPOAEs for detecting changes in ICP.
- To determine if DPOAE measurements correlate with ICP levels.
Main Methods:
- Eight patients undergoing cerebrospinal fluid (CSF) infusion testing for hydrocephalus participated.
- DPOAE measurements were taken at baseline and six controlled ICP levels.
- ICP levels were increased incrementally in random order.
Main Results:
- Significant increases in DPOAE angle were observed when ICP rose by ≥ 12 mmHg above baseline.
- Significant decreases in DPOAE magnitude were noted under the same conditions, though less robustly.
- These changes were most prominent for f2 frequencies between 800 and 1700 Hz.
Conclusions:
- Changes in DPOAE angle and magnitude are physiologically linked to ICP variations.
- DPOAE measurements show potential for detecting pathological ICP elevation.
- Further research is needed to establish baseline DPOAE values in various body positions for spaceflight application.
