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

Abstract

BackgroundEustachian 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.MethodsSixteen 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.ResultsIt 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.ConclusionThe 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.

The characteristic of patulous eustachian tube patients diagnosed by the JOS diagnostic criteria

“…The former two tests are similar in that both tests monitor pressure transmission from the nasopharynx to the middle ear, by imposing pressure change through respiration or sniffing, and evaluate its effect on the middle ear pressure [8]. Sonotubometry evaluates sound transmission from the nasopharynx to the external auditory meatus [10, 19]. Previous study indicate that definite PET can be diagnosed if sound attenuation from the nostril to EAC is less than 100 dB [20].…”

Advances in Eustachian tube function testing

“…ET opening may also be detected using a sound stimulus transmitted from the nose to the ear, via the momentarily patent ET, a test known as sonotubometry. Peaks in the transmitted sound that are synchronous with swallowing are interpreted as ET opening, assessed in terms of amplitude 34 , 35 or shape 36 . Although usually performed at atmospheric pressure, the nasopharyngeal pressure may be varied, 37 or the procedure performed in a pressure chamber 38 .…”

“…Breathing-synchronous TM movement is considered a specific sign of patulous ETD that may be detected by visual monitoring of the TM, 20 or through the use of continuous (also known as long time-base) impedance recording, 47 TTAG, 48 or sonotubometry. For those patients in whom the ET is not permanently patulous, tubomanometry 32 , 49 or sonotubometry 35 , 50 using specific protocols have shown promise in defining the severity of patulous ETD. However, detection of an intermittently patulous ET, or an ET with low acoustic impedance remains difficult, as discussed in the partner review of patulous ETD [ cross reference ].…”