[Correlation between acoustic immittance and ETS in eustachian tube function test]

Abstract

Objective:To investigate the correlation between acoustic immittance and eustachian tube score（ETS） in eustachian tube function test. Methods:124 ears eustachian tube function with tympanic tension perforation of 107 patients with chronic suppurative otitis media were measured by acoustic immittance positive pressure balance method and ETS. According to the positive pressure balance test results of acoustic immittance, the ear eustachian tube open pressure between 100 and 200 daPa is assigned 2, the ear with open pressure between 200 and 300 daPa is assigned 3, the ear with open pressure betwween 300 and 400 daPa is assigned 4, the ear open pressure is greater than 400 daPa but eustachian tube open after swallowing is assigned 5, and the ear which eustachian tube open pressure is greater than 400 daPa and cannot open after swallowing is assigned 6. Then compare the results. Results:In the acoustic immittance test, there was no ears whose eustachian tube opening pressure less than 100 daPa, 10 ears（8.1%） open pressure between 100 and 200 daPa, 16 ears（12.9%） open pressure between 200 and 300 daPa, 46 ears（37.1%） open pressure between 300 and 400 daPa, 19 ears（15.3%） whose eustachian tube don't open pressure at 400 daPa but open after swallowing, and the cumulative percentage of the above was 73.4%. There were 33 ears（26.6%） whose eustachian tubes not opening after receiving maximum pressure（400 daPa） and repeated swallowing. The score of acoustic immittance eustachian tube function test was significantly correlated with the scores of ETS, eustachian tube manometry（TMM） and subjective part of ETS（P<0.05）. The result of acoustic immittance was moderately negatively correlated with ETS（r=-0.439） and TMM（r=-0.425）, and weakly negatively correlated with subjective part of ETS（r=-0.249）. The scores of 2-5 points （the affected ears with open eustachian tube in all acoustic impedance test methods） were defined as the normal group, and the scores of 6 point were defined as the abnormal group. The results of acoustic immittance between the normal group and the abnormal group showed that there were significant differences with the subjective scores of ETS, TMM and ETS. The consistency compared the results of acoustic immittance eustachian tube test with the results of ETS was poor（kappa value was negative）, and the difference was statistically significant. Conclusion:The open pressure of acoustic immittance positive pressure balance method is a good predictor of the subjective scores of ETS, TMM and ETS. The smaller the open pressure is, the better the subjective scores of ETS, TMM and ETS may be. This two methods results are inconsistent and cannot be replaced. More consideration should be given to the middle ear. The open pressure, equilibrium pressure and the difference between them need to be paid attention to at the same time.

Keywords: acoustic immittance; eustachian tube function; tympanic membrane perforation.