Sonotubometry findings in children at high risk from middle ear effusion

The functioning of the eustachian tube has an important role to play in the development of middle ear disease. It would be useful if a clinical test could assist in the identification of eustachian tube dysfunction, particularly if this is shown to be an indicator of persistent middle ear effusion. The aim of this study was to compare the results of sonotubometry using the MMS-10 instrument in children at high risk from middle ear effusion with a group of normal subjects. Forty-one subjects (age range 5-6 years) were allocated to one of two groups (experimental group, 21 subjects; control group 20 subjects) based on a questionnaire designed to identify subjects at high risk from middle ear effusion. The test protocol allowed each subject to swallow three times for each of two pure-tones (7 and 8 kHz) delivered by the nasal probe. Sonotubometry indicated opening of the eustachian tube on swallowing in around 80% of subjects. The incidence of positive findings varied greatly amongst subjects across both groups. In the control group, the mean increase in sound pressure level on swallowing was 11.5 dB (+/- 4.3) and 9.8 dB (+/- 2.5) for 7 and 8 kHz, respectively. The corresponding means for duration were 118 ms (+/- 47.9) and 137 ms (+/- 61.8). Sonotubometry failed to demonstrate a difference between the two groups of subjects. Hence, the clinical application of sonotubometry to identify subjects at high risk from middle ear effusion is not supported.