Functional Assessment Beyond Type A Tympanograms: Pressure-Swallow Testing for Chronic Eustachian Tube Dysfunction in a Taiwanese Cohort

Background: Eustachian tube dysfunction (ETD) is associated with several common otologic conditions but lacks standardized diagnostic thresholds in Taiwan. This study aimed to evaluate the diagnostic performance of the GSI TympStar Pro pressure-swallow test and to identify a ROC-derived maximal peak pressure difference (MPD) cutoff for distinguishing clinically diagnosed obstructive Eustachian tube dysfunction (oETD) from healthy controls. Methods: A total of 152 subjects were enrolled, including 100 healthy controls and 52 patients with clinically diagnosed oETD, confirmed by otolaryngologist assessment and supported by ETDQ-7 symptom scoring. Tympanometry and tympanometry-based Eustachian tube function testing using the GSI TympStar Pro ETF–Intact pressure-swallow module, a modified three-tympanogram pressure-swallow protocol, were performed. Group comparisons were conducted using Mann–Whitney U and Chi-square tests. Diagnostic performance was assessed using receiver operating characteristic (ROC) curve analysis. Results: The median MPD was 11 daPa (IQR 6–17) in the control group, compared to 0 daPa (IQR 0–2) in the ETD group (p < 0.001). ROC analysis demonstrated that a cutoff value of ≤4 daPa yielded a sensitivity of 100.0% and specificity of 91.0% in the per-person analysis, and a sensitivity of 97.5% and specificity of 95.5% in the per-ear analysis. In the Type A-only per-ear analysis, MPD retained discriminatory performance, with an AUC of 0.978 (95% CI, 0.961–0.994). Conclusions: When interpreted in conjunction with ETDQ-7 symptom assessment and routine clinical evaluation, pressure-swallow testing may provide complementary objective information for the functional assessment of patients with suspected obstructive Eustachian tube dysfunction, particularly when resting tympanometry is unremarkable. In this single-center Taiwanese cohort, lower MPD values may serve as an adjunctive indicator of impaired Eustachian tube pressure equalization, and the ROC-derived cutoff of ≤4 daPa showed discriminatory value for differentiating symptomatic obstructive ETD from healthy controls. This cutoff should be interpreted as an exploratory, protocol-specific threshold and requires prospective validation in larger multicenter populations before broader clinical application.