Acoustic Transmission Characteristics of a Eustachian Tube Volitionally Opened in Two Living Subjects

Eustachian Tube Dysfunction Diagnostic Pathway-What Is the Current State of the Art and How Relevant Is Chronic Nasal Disease?

Background: Eustachian tube dysfunction (ETD) presents a complex diagnostic challenge in otolaryngology, compounded by its multifaceted nature and overlapping symptoms with chronic nasal disease. This article examines the intricacies of ETD diagnosis, emphasising the necessity for a consensus on diagnostic procedures. Methods: A review of the literature was performed through the OVID research tool in the Pubmed/Medline databases to identify relevant articles that discuss eustachian tube dysfunction diagnostics as well as its correlation with chronic nasal disease. Results: The literature review harvested 201 articles, and only 51 of them were included in the full text review. A consensus statement was identified on eustachian tube dysfunction, function and diagnostics. It appears that there is significant variability in the diagnostic tools used to identify eustachian tube dysfunction. The main diagnostic approaches used are tympanometry, tubomanometry and sonotubometry, combined with the Patient-Reported Outcome Measure ETDQ-7 questionnaire to support the diagnosis of the condition. Nasal pathology is mostly absent from the retrieved studies, while ear pathology is more commonly mentioned in the current literature. Conclusions: There is no gold standard diagnostic tool to determine the presence of eustachian tube dysfunction. Further discussion, large multicentre studies and focused research are required to achieve a consensus on a diagnostic approach. The authors suggest a diagnostic pathway that combines subjective and objective diagnostic tools to determine the presence of eustachian tube dysfunction. This pathway is simple and can be used in district ENT departments, highlighting the nasal pathology relevance to ETD.

Patulous Eustachian tube (PET), a practical overview

Symptoms of patulous Eustachian tube (ET), particularly autophony, can overlap with other conditions, and can arise from a variety of causes. We review the pathophysiology of "speech hyper-resonance syndromes", and possible mechanisms, including resonances in the tympanic membrane, Eustachian tube and nasopharynx. Treatment can be directed at the eardrum or the ET depending on site of pathology. We review typical presentations, examination findings, and useful clinical tests to distinguish PET from other disorders, and our philosophy of management.

The 678 Hz acoustic immittance probe tone: a more definitive indicator of PET than the traditional 226 Hz method

Background

The accurate diagnosis of Eustachian tube (ET) dysfunction can be very difficult. Our aim is to determine whether a 678 Hz probe tone is a more accurate indicator of Patulous ET (PET) than the 226 Hz probe tone when used in compliance over time (COT) testing.

Methods

Twenty subjects (11 normal ET ears and 7 PET ears) were individually seated in an examination room and connected to a GSI TympStar Middle Ear Analyzer. The order of probe tone frequency (678 or 226 Hz) was randomized. Baseline “testing” COT recordings for each ear undergoing testing were completed. Subjects were instructed to occlude their contralateral nostril and to breathe forcefully in and out through their ipsilateral nostril until the test had run to completion. This process was repeated with the probe tone that had not been previously run. For the control group, each subject had one random ear tested. For the experimental group, only the affected ear(s) was tested. Wilcoxon rank rum tests were performed to determine statistical significance.

Results

The baseline COT measurements for the control group and PET group were similar, 0.86 mL (SD = 0.34) and 0.74 (SD = 0.33) respectively. Comparing the 226 Hz tone between groups revealed that PET patients had a median COT difference 0.19 mL higher than healthy ET patients, and for the 678 Hz tone, PET patients had a median COT difference of 0.57 mL higher than healthy ET patients. Both were deemed to be statistically significant (p = 0.002, p = 0.004 respectively). The was a statistically significant median COT difference between the 678 Hz and 226 Hz of 0.61 mL (p = 0.034) for the PET group, while the same comparison for the control group of 0.05 mL was not significant (p = 0.262), suggesting that the 678 Hz tone yields a larger response for PET than the 226 Hz tone, and no difference for the control group, thus making it less prone to artifact noise interference.

Conclusion

The 678 Hz probe tone is a more reliable indicator of ET patency, and should be preferably used over the 226 Hz tone for future COT testing.

Transmission of a novel sonotubometry acoustic click stimulus in healthy and patulous eustachian tube subjects: a retrospective case -control study

Background

Eustachian tube (ET) dysfunction can be very difficult to diagnose accurately. Our aim is to determine whether a newly developed sonotubometric test using clicks can reliably detect ET opening during swallowing in normal ET subjects, and patulous ET (PET) in subjects with ET dysfunction.

Methods

Sixteen subjects (19 normal ET ears and 6 PET ears) were individually placed in a sound-isolated audiometry booth and subjected to a 1000Hz click train stimulus, played through the nose. PET subjects were identified through the ET clinic at our institution, while healthy subjects were recruited. Transmission through the ET was recorded by a microphone in the ear ipsilateral to the presenting nostril, during no swallow and swallow states, and this was used to compute a power ratio (power in the frequency range of interest to the whole frequency range). The power transmission ratio both before and after the swallow was averaged, and represented the baseline (BaseR). The power transmission ratio during swallow represented the peak (PeakR). The same process was repeated in the absence of a stimulus to account for swallowing noise. Wilcoxon rank rum tests were performed to determine statistical significance.

Results

It was found that for healthy ET patients, the median difference between the PeakR and BaseR was 0.51 (p = 0.004). For the PET patients in this study, the median difference between the PeakR and the BaseR was 3.30 (p = 0.041). Comparing the baseline between groups revealed that PET patients had a median BaseR 1.05 higher than healthy ET patients. PET patients had a median PeakR of 3.84 higher than healthy ET patients. Both were deemed to be statistically significant (p = 0.003, p = 0.003 respectively). A significant difference was found between median PeakR for the stimulus and no-stimulus condition for the healthy ET group (0.59, p < 0.001) and for the PET group (4.39, p = 0.031), indicating that it was unlikely that swallowing noise caused false positive results.

Conclusion

The results of this study suggest that a novel click stimulus is capable of detecting ET opening during swallowing in healthy patients as well as highlighting PET in diseased subjects.