The aim of this study was the introduction of a specific class of signals, the so-called perfect sequences (PSEQ), in a novel approach for sonotubometry of the Eustachian tube (ET). Sonotubometry using PSEQ stimuli was performed on 20 healthy subjects in order to gauge its potential for clinical applications. In a series of 320 measurements ET opening was probed, which was induced by dry and water swallowing, Toynbee maneuver, and yawning. All sonotubograms were analyzed with respect to their shape, increase of sound intensity, and opening duration. In 298/320 measurements (>93%) the subjects reported subjective ET openings. The evaluation of the recorded sonotubograms showed good detection of ET opening for the inducing maneuvers of swallowing (dry and water swallowing) and the Toynbee maneuver, with 90, 86, and 80% valid sonotubograms, respectively. Yawning led to only 40% valid sonotubograms. In total, 237/320 (~74%) sonotubograms were classified as valid. The evaluation of the sound level increase during ET openings showed that it was significantly higher in measurements with dry and water swallowing, as well as Toynbee maneuvers (mean 17.1, 19.0 and 17.2 dB, respectively), than with yawning (mean 10.17 dB; P < 0.0001). Nasal decongestion was found to have little influence on the results (P > 0.05). Sonotubometry using PSEQ stimuli is a novel sonotubometry methodology that provides valuable information regarding the auditory tube patency. By further technical refinements of the method, a diagnostic tool with high sensitivity and specificity could be developed.
PSEQ allowed the detection of an ET opening in all 40 normal ears (91% of the performed maneuvers) and in 87.5% of the ears with impaired ET function (but only 47% of the maneuvers). The average amplitude of the openings in healthy ears was 16.86 dB, the average duration was 363 ms. In diseased ears these values were significantly lower: 9.73 dB, p < 0.001 and 280 ms, p < 0.05.
PSEQs allow an evaluation of ET function. The chosen manoeuvres trigger in healthy subjects objective ET openings with a high reliability. The application of PSEQs can detect ET activity with a high sensitivity and good specificity. By further technical refinements specificity may also be enhanced in future studies.
Problem Sonotubometry is a non-invasive method for the evaluation of Eustachian Tube (ET) function. Perfect Sequences (PSQE) allow monitoring the ET under physiologic conditions in healthy ears. This study investigates the use of this new approach in pathologic ears. Methods Forty individuals were examined. Group A: n=20 individuals (40 normal ears). Group B: n= 11 patients (16 ears) with acute/subacute ET dysfunction. Group C: n=9 patients with chronic problems requiring tympanoplasty. Sonotubometry was performed before and after operation. As opening maneuvers, yawning, dry swallowing, water swallowing, and Toynbee were employed. Results In group A an ET opening was seen in 77.06% maneuvers and in all patients. The median amplitude (A) of sound increase was 16.64 dB, the duration of the openings (D) was 365 ms. In group B these values were 34.39%, A = 9.27 dB, D=311 ms before and 72.26%, A= 19.51 dB and D=329 ms after operation (myringotomy/tympanostomy). Group C showed openings in 33.83% with A=9.78dB and D=365 ms. There was no significant change after surgery. Conclusion The comparison between normal ears and acute ET dysfunction shows sonotubometrical a return of the normal function after operation within a week in most ears. The results demonstrate that the findings occur not only due to an improved sound transmission through the dry middle ear but from a recovering ET. The results in Group C show that the ET dysfunction is chronic. Significance Sonotubometry with PSQE is feasible for assessment of ET (dys)function under physiological conditions. It has therefore the potential to open new perspectives on ET monitoring. Support Supported by DFG-grant MA 3917/1-1.
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