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

Abstract

Objective 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. Subjects and Methods 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 seconds during swallowing and other tasks. Serial images were analyzed. Results 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. Conclusion 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.

A Conceptual Study on Kaphaja Shiroroga with Special Reference to Sinusitis

“…The intermittent opening of the pharyngeal ostium in the nasopharynx cause peristaltic-like movements, which are probably due to the visco-elastic nature of the tubular structure of the cartilage [3,8]. Yet, the opening of the ostium happens as a result of intervention strategies by the muscles, although we do not know the exact timing of the intervention and the precise actions of the muscles that interact with the tube.…”

“…It consists of a posterolateral osseous portion and one fibro cartilaginous anteromedial portion, with a length of about 3.5 centimetres [1,8]. The three dimensional structure of the internal lumen is covered with epithelial cells coated by a viscous fluid, and periluminous mucous tissue [1].…”

“…Yet, the opening of the ostium happens as a result of intervention strategies by the muscles, although we do not know the exact timing of the intervention and the precise actions of the muscles that interact with the tube. During swallowing or opening the mouth, the ostium of the nasopharyngeal tube opens, balancing the air pressure in the middle ear and clearing it [3,5,8,9].…”

“…Another feature attributed to the two mastication muscles, is to allow the peristaltic movement of the tube, in synergy with the LVPM and TVP (levator veli palantini muscles), during the process of swallowing; the same active movement of the LP and PM, even in the absence of swallowing, allows the tube to open [8]. It is likely, their intervention alters the shape of the tube, which becomes more convex, allowing the muscles that act directly on the tube to provide greater force [8].…”

“…It is likely, their intervention alters the shape of the tube, which becomes more convex, allowing the muscles that act directly on the tube to provide greater force [8]. Another explanation for their usefulness, for the PM in particular, is that they may act as fulcrum, so that the musculature of the tube acts as a more efficient vector [22,23].…”