Width of Patulous Eustachian Tube: Comparison of Assessment by Sonotubometry and Tubo-tympano-aerography.
To assess the accuracy of tubo-tympano-aerodynamic-graphy (TTAG) in the estimation of morphological severity of patulous Eustachian tube (PET), and to compare the results with that of sonotubometry in clinical cases and in model experiments.Retrospective chart review and model experiment.Tertiary referral center.A retrospective survey of medical records in Sen-En Rifu Hospital identified 26 patients (12 men and 14 women subjects aged 14-78 yr, average 49.4 ± 20.9 yr), comprising of 35 ears with PET. A definite diagnosis of PET was made for all patients based on the diagnostic criteria proposed by the Japan Otological Society.Commercial equipment for sonotubometry and TTAG (JK-05A; RION Co., Ltd., Kokubunji, Tokyo, Japan) were used in the following investigations. Model Experiment: The ET model was made using two truncated syringes with silicone barrels and a narrow connecting tube (0.2, 0.4, 0.58, 0.8, 1.00, 2.00, and 3.00 mm). Clinical Investigation: Morphological evaluation of ET patency was performed by a three-dimensional (3-D) CT (3D Accuitomo; Morita MFG. Corp., Kyoto, Japan) and analyzed by software (Integrated Information System i-VIEW; Morita MFG. Corp.).The transmitted sound pressure level gradually increased as the tube caliber was widened up to 3 mm diameter. On the other hand, pressure transmission was suddenly elevated and reached a plateau at 0.58 mm in diameter. The cross-sectional area at the narrowest portion of the ET was significantly correlated with the sound attenuation from nostril to external auditory canal (EAC) (Spearman rank correlation test: r = -0.521, p