Measurement of eustachian tube function using sonotubometry

Evaluation of eustachian tube function using a portable device

The present paper investigates a portable eustachian-tube-function testing device by sonotubometry based on pure-tone sound transmission via the eustachian tube (ET). The measured results obtained by the proposed method were validated through comparison with the existing testing technique based on broadband sound inspection. The measurement results for the ET opening time (T_open) and the sound pressure difference in the ear canal between open and closed ETs (ΔL) obtained using pure-tone sounds with tonal frequency components of 7.0 and 9.5 kHz generally agreed with the results obtained by the existing technique with broadband testing sound.

Eustachian Tube Opening Measurement by Sonotubometry Using Perfect Sequences for Healthy Adults

Objectives

The aim of this study was to establish the rate variation of sonotubometric measurements using a specific broadband class of signals, the so-called perfect sequences (PSEQ) among healthy adults and to identify an optimal and technically simple test to provoke Eustachian tube (ET) openings.

Methods

Sonotubometry was performed on 105 healthy adult subjects. Three different consecutive maneuvers were performed for ET opening: dry swallowing, water swallowing (a small [2 mL] and a large [5 mL] water bolus). Values of the amplitude and duration of each measured ET opening were calculated.

Results

A total of 6,300 measurements were performed. Sonotubometric ET openings were detected for all subjects but not for each measurement. In 6,180 of 6,300 measurements (98.1%), objective ET openings were registered. In 11 of 105 subjects (10.5%) at least one sonotubometric ET opening was not detected. The mean ET opening duration time and the mean sound amplitude similar for all performed test and were 270 (SD, ±96) msec, 13.48 (SD, ±6.57) dB.

Conclusion

Sonotubometry based on PSEQ stimuli is a reliable methodology to assess the ET opening function in healthy subjects. Mean ET opening duration time and the mean sound wave amplitude performed similarly in all analysed tests, hence it might be concluded that dry (saliva) and water swallowing are reliable sonotubometric maneuvers and may be used when examining ET opening function. The size of a sip during water swallowing does not affect the sonotubometry result. All maneuvers can be equally used as the optimal test, and water swallow is most comfortable for the subject.

A method to assess the accuracy of sonotubometry for detecting Eustachian tube openings

Sonotubometry is a simple test for Eustachian tube (ET) opening during a maneuver. Different sonotubometry configurations were suggested to maximize test accuracy, but no method has been described for comparing sonotubometry test results with those for a definitive measure of ET opening. Here, we present such a method and exemplify is use by an accuracy assessment of a simple sonotubometry configuration. A total of 502 data-sequences from 168 test sessions in 103 adult subjects were analyzed. For each session, subjects were seated in a pressure chamber and relative middle ear over- and under-pressures created by changing chamber pressure. At each pressure, the test sequence of bilateral tympanometry, bilateral sonotubometry while the subject swallowed twice, and bilateral tympanometry was done. Tympanometric data were expressed as the fractional gradient equilibrated (FGE) by swallowing and sonotubometric signals were analyzed to record the shape of detected sound signals. Tympanometric and sonotubometric tubal opening assignments were analyzed by cross-correlation. For the data sequences with FGE = 0 (n = 32) evidencing no tubal opening and one (n = 249) evidencing definitive tubal opening, detection of a sonotubometry sound signal during a swallow had a sensitivity and specificity of 74.2 and 65.6 % for identifying ET openings and an accuracy of 73.3 % for assigning ET opening/non-opening by swallowing. Measures of sound signal shape were significantly different between those groups. This protocol allows a sonotubometry accuracy assessment for detecting ET openings. For the test configuration used, accuracy was moderate, but this should improve as more sophisticated sonotubometry test configurations are evaluated.

New insights into mechanism of Eustachian tube ventilation based on cine computed tomography images

There is debate concerning the mechanism of Eustachian tube (ET) ventilation. While a mechanism of complete opening has been advocated previously, sequential contraction of the levator veli palatini and medial pterygoid muscles followed by the tensor veli palatini and lateral pterygoid muscles may produce a transient sequential opening mechanism, allowing an air bolus to traverse the ET. This may explain confusion surrounding sonotubometry reports that not every swallow leads to sound passage in normal subjects. We hypothesize that the ET may not need to open completely when ventilating the middle ear; rather, a discrete air bolus can pass through it. Five normal and five disordered subjects underwent low-radiation dose cine computed tomography (CT) scans of the ET. Sixteen contiguous 2.5 mm slice locations were chosen through a 4 cm area in the nasopharynx that were parallel to and encompassed the entire ET. Twelve images were acquired at each slice over 4.8 s during swallowing and other tasks. Serial images were analyzed. An air bolus was observed passing through the ET in the normal subjects, but not the subject with ET dysfunction. Medial and lateral pterygoid contractions were also observed. A new hypothetical mechanism of transient sequential ET ventilation is presented. This is not a definitive conclusion, as the number of scans taken and maneuvers used was limited. Improved understanding of ET ventilation may facilitate management of middle ear disease as treatment evolves from ventilatory tube placement to ET manipulation.

Results of sonotubometry in testing eustachian tube ventilatory function in children with cleft palate

OBJECTIVES

In previous studies, an updated sonotubometry setup was tested in healthy adults and children to test its validity and reproducibility in the assessment of the ventilatory function of the eustachian tube (ET). The results were promising, but further investigations were needed to confirm the discriminative potential of this sonotubometry setup. Our objective in the present study was to test the discriminative potential of an updated sonotubometry setup in children with cleft palate.

METHODS

The ET ventilatory function was tested in 56 children with cleft palate, ie, children with impaired ET function, and compared to the outcomes in 61 healthy children who served as a control group. All of the children were between 5 and 9 years of age. To test the reproducibility, we performed the sonotubometric testing in 2 sessions of 10 acts of swallowing each. Spearman's coefficient was used to test the correlation between the 2 sets of measurements. The results of measurements in the cleft palate group were compared with those in the otologically healthy control group and analyzed by means of a Mann-Whitney U test.

RESULTS

Opening of the ET was recorded in at least 1 of the 2 measurement sessions in 57% of the children with cleft palate, as compared to 82% in the control group. The mean number of openings was lower in the cleft palate group than in the control group (respectively, 2.3 versus 3.7 out of 10; p < .01). The first and second sessions were highly correlated in both the cleft palate group and the control group, with Spearman's coefficients of, respectively, 0.96 and 0.89.

CONCLUSIONS

The results of this study show that this updated sonotubometry setup has the potential to discriminate between these groups of children with various states of ET ventilatory function. Furthermore, the results of this study once again show that this updated sonotubometry setup is capable of assessing ET ventilatory function in both healthy children and children with cleft palate and that the measurements are highly reproducible. A persistent disadvantage remains that in 18% of the 61 healthy children there was no ET opening that could be registered, which still prohibits a definite assessment at the individual level.

Reproducibility of sonotubometry as Eustachian tube ventilatory function test in healthy children

OBJECTIVES

To devise a simple and reliable diagnostic procedure to test Eustachian tube function routinely in an ENT outpatient setting. One method to measure ET ventilatory function is sonotubometry. The reproducibility of a recently updated sonotubometry set-up was tested in healthy children.

METHODS

The test population comprised 61 school children aged from 6 to 8 years. Only otologically healthy children were included. Health state was established by means of a 12-item questionnaire. To test reproducibility, sonotubometric testing took place in two sessions of 10 acts of swallowing each. Spearman's coefficient was used to test the correlation between the two sets of measurements. All testing took place at a primary school in a nearby village.

RESULTS

Opening of the ET was recorded in at least one of the two measurement sessions in 82% of the children. The first and second sessions were highly correlated, with a Spearman's coefficient of 0.89.

CONCLUSIONS

In otologically healthy children, opening of the ET was recorded frequently using the updated sonotubometry set-up. Measurement results had high reproducibility. Therefore, the test forms a useful method to assess ET ventilatory function in otologically healthy children. The performance of this updated version needs to be established in children with otological diseases.

Sonotubometry: Eustachian Tube Ventilatory Function Test: A State-of-the-Art Review

OBJECTIVE

Disturbance of any of the ET functions may contribute to the development of otitis media. Sonotubometry measures the ventilatory function using sound. The qualities of sonotubometry as a test for eustachian tube ventilatory function have been studied by various investigators. The development of the method is described in the review, and a summary of the study results is provided to make an estimate of the diagnostic potential of this eustachian tube function test.

DATA SOURCES

The English-language literature on the topic was searched systematically by Medline and Pubmed using the following key words: ventilatory function, eustachian tube, sonotubometry, and function test. There were no limits for the year of publication.

STUDY SELECTION

Articles that described the method itself (validity, reproducibility, diagnostic value) were studied in detail.

DATA EXTRACTION

All the articles described in study selection were used for this review.

CONCLUSIONS

The technique of sonotubometry has been improved gradually over the years. The results of sonotubometry are at least as good as those of other function tests. However, because the results still tend to be ambiguous in children and otitis media is most common in this population, the reproducibility and application of sonotubometry must be evaluated further. Sonotubometry has great advantages over other function tests, but it is not used routinely to assess eustachian tube ventilatory function because its value for clinical practice has not yet been adequately demonstrated. The review showed that sonotubometry can be improved further and that efforts to do so seem justified because it forms a particularly promising method to assess eustachian tube function in children with suspected eustachian tube disease.

Funktionsuntersuchungen der Tuba Eustachii

The Eustachian tube regulates the homeostasis of the middle ear. Problems with its function are predominantly found in childhood. As a consequence, otitis and hearing impairment occur. The most important muscle is the tensor tympani muscle. The complexity of the functional anatomy and physiology are reasons why no function test alone is capable of fulfilling all diagnostic needs. The predictive value of the various Eustachian tube function tests for the outcome of a tympanoplasty is not yet clear. An overview of clinically and scientifically relevant tests for the Eustachian tube function is provided.

Therapeutic improvement of Eustachian tube function: a review

An impaired Eustachian tube is assumed to be an important factor in the pathogenesis of different middle ear diseases. Therefore, several investigators have studied different treatment strategies to improve Eustachian tube function. The aim of this review is to provide a comprehensive summary of the results of these studies on improvement of tubal function. The English language literature was searched systematically to identify all articles that described the effect of different interventions on Eustachian tube function. Although the results were not uniform throughout the different studies and despite several restrictions of the reviewed studies, the results of this review indicate that the function may be improved by medical intervention. However, it seems premature to recommend any of the interventions reviewed in this paper to improve function in humans. More studies, preferably randomized, placebo-controlled trials, should be conducted to assess the efficacy of different interventions.

Interpretation of sonotubometry. A critical view of the acoustical measurement of the opening of the eustachian tube

The principle of sonotubometry for recording the opening of the Eustachian tube is based on the assumption that this opening increases the sound transmission from the nasopharynx to the external ear canal. However, the clinical validity of the method remains to be documented. In the present study the results in 37 normal ears were compared with those of 11 ears which showed signs of Eustachian tube dysfunction. In these glue was found in the middle ear at a subsequent myringotomy. In 13 of the subjects a comparison was made of the signals picked up from the ear canal and from the contralateral nostril. It was concluded that the interpretation of the signals from the ear canal is very complicated. They may be due to an opening of the Eustachian tube, but they may also be caused by a change of the acoustic conditions in the nasopharynx during the swallowing procedure. Despite the fact that this test principle in theory is ideal, much research seems to be required before the clinical value of the method can be confirmed.