Posture systematically alters ear-canal reflectance and DPOAE properties

Picker Engineering Program, Smith College, 51 College Lane, Northampton, MA 01063, USA.
Hearing research (Impact Factor: 2.85). 03/2010; 263(1-2):43-51. DOI: 10.1016/j.heares.2010.03.003
Source: PubMed

ABSTRACT Several studies have demonstrated that the auditory system is sensitive to changes in posture, presumably through changes in intracranial pressure (ICP) that in turn alter the intracochlear pressure, which affects the stiffness of the middle-ear system. This observation has led to efforts to develop an ear-canal based noninvasive diagnostic measure for monitoring ICP, which is currently monitored invasively via access through the skull or spine. Here, we demonstrate the effects of postural changes, and presumably ICP changes, on distortion product otoacoustic emissions (DPOAE) magnitude, DPOAE angle, and power reflectance. Measurements were made on 12 normal-hearing subjects in two postural positions: upright at 90 degrees and tilted at -45 degrees to the horizontal. Measurements on each subject were repeated five times across five separate measurement sessions. All three measures showed significant changes (p<0.001) between upright and tilted for frequencies between 500 and 2000 Hz, and DPOAE angle changes were significant at all measured frequencies (500-4000 Hz). Intra-subject variability, assessed via standard deviations for each subject's multiple measurements, were generally smaller in the upright position relative to the tilted position.

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    High Altitude Medicine & Biology 08/2014; 15(3). DOI:10.1089/ham.2013.1120 · 1.82 Impact Factor
  • Ear and Hearing 07/2013; 34:48s-53s. DOI:10.1097/AUD.0b013e31829c964d · 2.83 Impact Factor
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    ABSTRACT: BACKGROUND: There is an important need to develop a noninvasive method for assessing intracranial pressure (ICP). We report a novel approach for monitoring ICP using cochlear-derived distortion product otoacoustic emissions (DPOAEs), which are affected by ICP. OBJECTIVE: We hypothesized that changes in ICP may be reflected by altered DPOAE responses via an associated change in perilymphatic pressure. METHODS: We measured the ICP and DPOAEs (magnitude and phase angle) during opening and closing in 20 patients undergoing lumbar puncture. RESULTS: We collected data on 18 patients and grouped them based on small (< 4 mm Hg), medium (5-11 mm Hg), or large (>= 15 mm Hg) ICP changes. A permutation test was applied in each group to determine whether changes in DPOAEs differed from zero when ICP changed. We report significant changes in the DPOAE magnitudes and angles, respectively, for the group with the largest ICP changes and no changes for the group with the smallest changes; the group with medium changes had variable DPOAE changes. CONCLUSION: We report, for the first time, systematic changes in DPOAE magnitudes and phase in response to acute ICP changes. Future studies are warranted to further develop this new approach.
    Neurosurgery 05/2014; 75(4). DOI:10.1227/NEU.0000000000000449 · 3.03 Impact Factor


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Jun 6, 2014