Fig 1.
Tubomanometry and computed tomography (CT) imaging during Eustachian tube (ET) opening.
(A) Representative Tubomanometry (TMM) tracing from a healthy volunteer demonstrating normal ET function. The examination was performed during swallowing at a nasal pressure of 30 mbar. C1 designates the onset of nasopharyngeal pressure elevation; C2 indicates the peak nasopharyngeal pressure and the beginning of the plateau phase; C3 marks the initiation of pressure descent and the end of the plateau phase; and C4 represents the completion of pressure descent. (B) ET imaging. Oblique-plane CT imaging performed during the Valsalva maneuver allows complete visualization of the radiolucent linear lumen of the ET. (C) CFD computational model. The computational domain includes the ET and middle ear cavity, while the external auditory canal was retained only for visualization. The outlet boundary was defined at the pharyngeal orifice of the ET. The isthmus region was segmented as an independent boundary, allowing parametric adjustment of its diameter to simulate varying degrees of patency: fully patent (100% tubal patency) and area-reduced configurations (10%, 30%, and 50% tubal patency).
Fig 2.
Eustachian tube (ET) patency configurations and pressure measurement results.
(A) Computational meshes for the fully patent ET (left) and the 50% patency configuration (right). All other stenotic models followed the same meshing protocol as the 50% configuration. (B) Pressure curves under varying ET patency conditions. When ET patency was maximally restricted to 10%, middle ear pressure remained elevated after depressurization. Additional middle ear pressure measurements at 20% tubal patency were obtained from specimens showing comparable pressure recovery between partial (50%) and full (100%) patency states, revealing consistent trends across conditions.
Table 1.
Mesh independence validation.
Fig 3.
Pressure contour plots during the pressurization, stabilization, and depressurization phases (100% Eustachian tube [ET] patency).
During the early pressurization phase (A: 0.02 s), continuous air injection drives airflow inward from the nasopharynx through the ET into the tympanic cavity, resulting in a gradual pressure increase within the tympanic cavity, mastoid antrum, and air cells (collectively referred to as the middle ear system). Magnified insets (dashed boxes) highlight the ET isthmus—the narrowest segment of the ET—where a localized low-pressure zone (cool colors) is visible, consistent with the Venturi effect. By the late pressurization phase (B: 0.14 s), airflow propagates further into the mastoid antrum and air cells, reducing the pressure gradient between the ET and middle ear structures, although the low-pressure region within the isthmus (cool colors in the inset) remains evident. In the stabilization phase (C: 0.26 s), pressure equalizes across the entire computational domain—including the ET, tympanic cavity, mastoid antrum, and air cells—with a uniform pressure distribution (depicted by consistent warm-to-green tones) and only minimal regional variation (inset). During the depressurization phase (D: 1.4 s), airflow reverses direction, moving outward from the tympanic cavity, mastoid antrum, and air cells through the ET toward the nasopharynx. The pressure gradually decreases along the ET pathway, eventually approaching atmospheric pressure over time. Color bars represent pressure magnitude (Pa), with warm colors denoting high pressure and cool colors denoting low pressure.
Table 2.
Comparison of pressure in the tympanic cavity among the area-reduced configuration groups during the pressurization, stabilization, and depressurization phases.
Table 3.
Comparison of pressure in the tympanic antrum among the area-reduced configuration groups during the pressurization, stabilization, and depressurization phases.
Table 4.
Comparison of pressure in the air cells among the area-reduced configuration groups during the pressurization, stabilization, and depressurization phases.
Fig 4.
Pressure contour plots of the Eustachian tube (ET)–middle ear system under different ET patency levels during the late pressurization phase (0.2 s).
This figure illustrates the spatial pressure distribution patterns of 10%, 20%, 30%, 50%, and 100% ET patency (from left to right) at the late pressurization phase (0.2 s). The dashed magnified boxes highlight the ET segment, representing the primary pressure transmission pathway, to clearly depict regional pressure variations. 10% patency: The ET and adjacent middle ear regions are dominated by cool colors, indicating pronounced low-pressure zones. 20% and 30% patency: Cool colors progressively transition to warm tones, and pressure gradients decrease as patency increases. 50% and 100% patency: The entire system displays uniform warm colors, reflecting consistent and equilibrated pressure distribution. Color bars represent pressure magnitude (Pa), where warm colors denote high-pressure zones and cool colors denote low-pressure zones.