Eustachian tube dysfunction: A diagnostic accuracy study and proposed diagnostic pathway

Abstract

Background and aims: Eustachian tube dysfunction (ETD) is a commonly diagnosed disorder of Eustachian tube opening and closure, which may be associated with severe symptoms and middle ear disease. Currently the diagnosis of obstructive and patulous forms of ETD is primarily based on non-specific symptoms or examination findings, rather than measurement of the underlying function of the Eustachian tube. This has proved problematic when selecting patients for treatment, and when designing trial inclusion criteria and outcomes. This study aims to determine the correlation and diagnostic value of various tests of ET opening and patient reported outcome measures (PROMs), in order to generate a recommended diagnostic pathway for ETD.

Methods: Index tests included two PROMs and 14 tests of ET opening (nine for obstructive, five for patulous ETD). In the absence of an accepted reference standard two methods were adopted to establish index test accuracy: expert panel diagnosis and latent class analysis. Index test results were assessed with Pearson correlation and principle component analysis, and test accuracy was determined. Logistic regression models assessed the predictive value of grouped test results.

Results: The expert panel diagnosis and PROMs results correlated with each other, but not with ET function measured by tests of ET opening. All index tests were found to be feasible in clinic, and acceptable to patients. PROMs had very poor specificity, and no diagnostic value. Combining the results of tests of ET function appeared beneficial. The latent class model suggested tympanometry, sonotubometry and tubomanometry have the best diagnostic performance for obstructive ETD, and these are included in a proposed diagnostic pathway.

Conclusions: ETD should be diagnosed on the basis of clinical assessment and tests of ET opening, as PROMs have no diagnostic value. Currently diagnostic uncertainty exists for some patients who appear to have intermittent ETD clinically, but have negative index test results.

Fig 1. Flow chart demonstrating the data collection process and generation of a reference standard, with subsequent analysis to assess test accuracy.

Fig 2. Flow chart for the expert panel diagnostic process.

Rules were set to assign a diagnosis in the event of disagreement between panels A&B: 1. Diagnoses made via individual agreement were assigned over those with initial disagreement; 2. Diagnoses made at discussion via consensus were assigned over those made by a 2:1 vote; 3. If rule 1 or 2 could not be applied, the diagnosis was recorded as indeterminate.

Fig 3. Proposed diagnostic pathway for ETD.

^{a, b} While clinical assessment of a patient’s history and conventional examination may not be diagnostic of ETD, they are nonetheless an important means to identify suitable patients for investigation. ^c Effort should be made during assessment of the clinical history to identify habitual sniffing, as a negative middle ear pressure in these individuals may not indicate OETD, and further testing should be undertaken. ^d Described diagnostic thresholds are based on the equipment and protocols used in our study, but may require adjustment if alternative methods are used ^e TTAG is recommended if a tympanic membrane perforation is present. ^f A simple provocation test for use in clinic is asking the patient to exercise (jog on the spot or climb a flight of stairs) prior to testing. ^g Consider repeating tests on a separate occasion to improve sensitivity in patients with variable ET function. Patients with baro-challenge induced OETD may present in this group.