Recent Update in the Diagnosis of Eustachian Tube Dysfunction: A Comprehensive Review of the Eustachian Tube Function Test

Eustachian tube dysfunction (ETD) is a prevalent otolaryngologic condition that plays a central role in the pathogenesis of various middle ear diseases; however, there is no universally accepted gold-standard test for its diagnosis. In this narrative review, currently available Eustachian tube (ET) function tests are comprehensively evaluated, encompassing subjective patient-reported outcome measures and objective diagnostic modalities, with an assessment of their diagnostic accuracy, clinical utility, repeatability, and limitations. Patient-reported outcome measures, such as the Eustachian Tube Dysfunction Questionnaire-7, are valuable for symptom quantification, but they correlate poorly with objective ET function, and they cannot reliably differentiate between ETD subtypes. Among the objective tests, sonotubometry, tubomanometry, and the nine-step inflation-deflation test have the highest detected opening rates in healthy ears. Composite scoring systems, such as the Eustachian Tube Score-7, achieve superior diagnostic accuracy by integrating multiple test modalities. Advanced imaging techniques, including sitting computed tomography and dynamic magnetic resonance imaging, provide critical anatomical and functional information, particularly for patulous ETD and surgical planning. No single test provides a complete functional assessment; a combined diagnostic approach integrating validated patient-reported outcomes with objective function tests offers the most accurate characterization of ETD. Standardization of testing protocols, consensus reference standards, and international multicenter validation studies remain urgent priorities.