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.