Wideband tympanometry as a noninvasive marker of intracranial pressure changes: a postural study in healthy adults.

BACKGROUND

Reliable noninvasive assessment of intracranial pressure (ICP) remains an unmet clinical need. Wideband tympanometry (WBT), which reflects middle ear mechanics, may provide indirect information on ICP-related inner ear pressure changes.

OBJECTIVE

To determine whether postural ICP variations induce measurable changes in WBT parameters in healthy adults.

METHODS

In this prospective study, 21 healthy adults (42 ears) underwent repeated WBT measurements in standing, supine, and Trendelenburg (-17°) positions. Five measurements were performed per ear in each position. Parameters analyzed included peak pressure (PP), peak pressure difference (ΔP), resonant frequency (RF), duplication frequency (DF), and absorbance-derived metrics. Statistical comparisons were performed using paired non-parametric tests with Šidák correction for multiple comparisons.

RESULTS

A total of 626 valid recordings were analyzed. PP and ΔP significantly increased in the Trendelenburg position compared with standing (PP: -10.9 ± 8.1 vs. 5.5 ± 24.4 daPa, p < 0.01; ΔP: 90.7 ± 42.0 vs. 105.0 ± 51.5 daPa, p < 0.05). No significant changes were observed for RF, DF, or absorbance-derived parameters. Interaural reproducibility was moderate to high for most variables but low for ΔP.

CONCLUSION

Postural changes associated with presumed ICP elevation induce measurable modifications in WBT signals, particularly PP and ΔP. These findings support WBT as a promising noninvasive approach for detecting ICP variations. Further validation against invasive ICP monitoring is warranted.