Background: There is an important need to develop a non-invasive method for assessing intracranial pressure. We report a novel approach for monitoring intracranial pressure using cochlear derived distortion product otoacoustic emissions, which are affected by intracranial pressure.
Objective: We hypothesized that changes of intracranial pressure may be reflected by altered DPOAE responses via an associated change in perilymphatic pressure.
Methods: We measured the intracranial pressure and distortion product otoacoustic emissions (magnitude and phase angle) during opening and closing intracranial pressure measurements in 20 patients undergoing lumbar puncture.
Results: We collected data in 18 subjects and grouped them based on small (<4 mmHg), medium (5 to 11 mmHg), or large (>=15 mmHg) intracranial pressure changes. A permutation test was applied within each group to determine if distortion product otoacoustic emissions changes differed from zero when intracranial pressure changed. We report significant changes in the distortion product otoacoustic emissions magnitudes and angles, respectively, for the group with the largest intracranial pressure changes and no changes for the group with the smallest changes; the group with medium changes had variable distortion product otoacoustic emissions changes.
Conclusion: We report, for the first time, systematic changes in distortion product otoacoustic emissions magnitudes and phase in response to acute intracranial pressure changes. Future studies are warranted to further develop this new approach.
From: Intracranial Pressure Modulates Distortion Product Otoacoustic Emissions: A Proof of Principle Study by Bershad et al.