A Preliminary Evaluation of Middle Ear Resonance Frequency via Wideband Tympanometry in Patients with Non-Alcoholic Fatty Liver Disease

Background and Objective: Non-alcoholic fatty liver disease (NAFLD) induces systemic low-grade inflammation and lipotoxicity. While its microvascular effects on the inner ear are recognized, its impact on the middle ear remains unexplored. This study aimed to investigate subclinical biomechanical alterations in the middle ear of normal-hearing NAFLD patients using Wideband Tympanometry (WBT). Materials and Methods: This prospective observational study included 28 patients with ultrasonographically confirmed NAFLD and 30 healthy, sex-matched controls. All included participants had normal pure-tone hearing thresholds and Type A tympanograms. WBT was performed to measure Resonance Frequency (RF) and frequency-specific absorbance (226–8000 Hz). A subgroup analysis compared early-stage (Grade 1) and advanced-stage (Grades 2–3) hepatosteatosis. Results: The mean RF was significantly lower in the NAFLD group compared to the controls for both the right (781.6 ± 218.7 vs. 1010.6 ± 529.0 Hz; p = 0.035) and left ears (740.3 ± 212.7 vs. 1221.6 ± 754.2 Hz; p = 0.002). Furthermore, wideband absorbance was significantly elevated at lower frequencies (250 Hz and 500 Hz) in the study group (p < 0.001 for both ears). Middle ear resting pressures were similar between the groups. Subgroup analysis revealed no significant differences in WBT parameters between Grade 1 and advanced stages (p > 0.05). Conclusions: Normal-hearing NAFLD patients exhibit a mass-dominated biomechanical shift in the middle ear, characterized by a decreased RF and increased low-frequency absorbance. These subclinical alterations, observable even in early-stage hepatosteatosis, likely reflect mucosal micro-edema driven by systemic inflammation. WBT serves as a sensitive, non-invasive tool for detecting early metabolic-related otologic changes.