Estimated locations of the narrowest portion of the eustachian tube lumen during closed and open states

Caution in Transnasal Balloon Dilation of the Eustachian Tube: Middle Ear Penetration of Catheter Tip in a Cadaveric Model

OBJECTIVE

To investigate the degree to which transnasal eustachian tube (ET) dilation balloon catheters are able to be passed through the ET in a cadaver model.

PATIENTS AND INTERVENTIONS

A cadaveric study of 8 cadaver heads (16 ears), which underwent transnasal ET insertion with a 3 × 20-mm balloon catheter with transtympanic endoscopic visualization and grading.

RESULTS

Catheter tip incursion into the protympanum or mesotympanum occurred in all ears. Radiological validation was obtained with correlation to published ET length data.

CONCLUSION

Middle ear incursion of balloon catheter tips can be demonstrated in a cadaver model and highlights the ongoing need for both caution in novel surgical techniques and evolution in device design.

Morphological Analysis of the Adult Eustachian Tube: A Fresh-Frozen Human Cadaver Study

OBJECTIVES

To evaluate the dilated Eustachian tube (ET) anatomy configuration using fresh human cadavers.

METHODS

Fourteen ears from human cadavers were used to identify the ET configuration. The cadaver head was cut in the sagittal plane parallel to the nasal septum, dividing it into right and left sides. Silicone was then inserted into the ET through the nasopharyngeal orifice (NO). The volume and length of the impression were measured using 3D computed tomography imaging.

RESULTS

The ET lumen was found to narrow from the NO to the isthmus, and the ET surface was concave anteriorly and convex posteriorly. The lower portion of the ET lumen was the most dilated and displayed a narrow top. The average volume of the ET impression was 1.4 ± 0.5 ml. The total length of the posterior side was 30.5 ± 3.6 mm, and that of the anterior side was 26.3 ± 3.4 mm. The widest ET area of the NO was 10.1 ± 0.9 mm in height and 8.0 ± 1.5 mm in width. The preisthmus was 2.4 ± 0.4 mm in height and 1.3 ± 0.5 mm in width. The height and width were 8.37 and 5.33 mm at the 5 mm point from the NO, and 5.51 and 1.94 mm at the 20 mm point from the NO, respectively.

CONCLUSION

We evaluated the configuration of the cartilaginous ET lumen, which is the main target of balloon dilation, and our findings may give insights into this dilation process and assist with the further development of ET balloons and stents.

Establishment of a Large Animal Model for Eustachian Tube Functional Study in Miniature Pigs

This study was performed to investigate whether miniature pigs are a suitable animal model for studies of the Eustachian tube (ET). Sixteen Chinese experimental miniature pigs were used in this investigation. Ten animals were used for anatomical and morphometric analyses to obtain qualitative and quantitative information regarding the ET. Three animals were used for histological analysis to determine the fine structure of ET cross-sections. Three animals were used to investigate the feasibility of balloon dilation of the Eustachian tube (BDET). The anatomical study indicated that the pharyngeal orifice and tympanic orifice of the miniature pig ET are located at the posterior end of the nasal lateral wall and anterior wall of the middle ear cavity, respectively. The cartilaginous tube was seen to pass through the whole length of the ET, the length of the cartilaginous part of the ET and the diameter of the isthmus were similar between humans and miniature pigs. The inclination of the ET in miniature pigs was larger than that in humans. The gross histology seemed to be slightly different between miniature pig and human, but the fine structures were essentially the same in both species. BDET experiments verified that the miniature pig model is suitable as a model for clinical operations. The miniature pig ET corresponds very well to that of humans. In addition, the miniature pig ET is suitable as a model for clinical operations. Therefore, the miniature pig is a valid animal model for ET study. Anat Rec, 302:1024-1038, 2019. © 2019 Wiley Periodicals, Inc.

Endoscopically Guided Transtympanic Balloon Catheter Dilatation of the Eustachian Tube: A Cadaveric Pilot Study

OBJECTIVE

To assess the feasibility, safety, and efficacy of transtympanic balloon catheter dilatation of the Eustachian tube (ET) in a cadaver model.

PATIENTS AND INTERVENTIONS

A cadaveric study of 10 cadaver heads, which underwent unilateral transtympanic dilatation of the ET with a 3 × 20 mm balloon catheter with full endoscopic guidance and visualization.

RESULTS

Procedural safety was demonstrated, with no damage to any essential structures found. Feasibility of the procedure was demonstrated in all cadavers with 100% success rate, despite a small number of encountered difficulties. Statistically significant efficacy was also demonstrated in both radiologic and manometric data.

CONCLUSION

With full endoscopic visualization, the transtympanic approach to balloon catheter dilatation of the ET seems to be a feasible and safe procedure in the cadaver model.

Transtympanic balloon dilatation of the eustachian tube: systematic review

OBJECTIVE

To investigate the evidence for balloon dilatation of the eustachian tube using a transtympanic approach.

METHODS

A systematic search of several databases was conducted (using the search terms 'dilation' or 'dilatation', and 'balloon' and 'eustachian tube'). Only studies that used a transtympanic approach for the procedure were included. These studies were then assessed for risk of bias.

RESULTS

Three studies were included. Each of these studies was a limited case series, with two performed on human subjects and one on human cadavers. Results of safety and efficacy are conflicting. There is a high risk of bias overall.

CONCLUSION

At present, there is a very narrow evidence base for transtympanic balloon dilatation of the eustachian tube. There are a number of advantages and disadvantages of the technique. Previously identified and theoretical safety concerns will need to be addressed thoroughly in future studies prior to wider clinical use.

The improvement of middle ear ventilation by laser ablation of the epipharyngeal eustachian tube: a prospective study

A long-lasting dysfunction of the eustachian tube seems to be the etiologic origin for development of chronic otitis media (COM) with mesotympanic perforation, otitis media with effusion (OME), and chronic atelectasis of the middle ear. Surgical interventions in the middle ear generally treat the sequelae of the tube dysfunction but not the dysfunction itself. This prospective clinical study investigated how far fiber-guided laser ablation of the posterior half of the epipharyngeal tubal ostium led to better middle ear ventilation in the otologic disease patterns mentioned below. There were 38 adult patients included in the analysis. The patients in one group had a perforated tympanic membrane [COM before primary tympanoplasty (n = 14) or revision tympanoplasty (n = 5)]; the patients in a second group had an intact eardrum [OME resistant to therapy (n = 3), with an atelectasis of the middle ear (n = 2) or problems of pressure equalization with fast changes in ambient pressure (diving, flying) (n = 14)]. Laser ablation of the posterior half of the epipharyngeal tubal ostium was performed, generally with local anesthesia, if tubal function testing was pathologic (Valsalva maneuver, passive tube opening, tympanogram). In patients with COM the procedure was performed 8 weeks before the middle ear surgery. All patients were checked 8 weeks postoperatively and in the course of the following year. The intervention seemed to have had a positive effect on tube function in 68.4% of patients operated on (P = 0.001). In 26 of the 38 patients that had undergone operation, an improvement the results of tubal function tests could be seen in the postoperative follow-up. In the COM group the Valsalva maneuver improved in 14 of 19 patients (73.6%) (P = 0.001), and the passive tube opening improved in nine of 18 patients (50%). In the group with an intact eardrum the Valsalva maneuver improved in 13 of 18 patients (72.2%) (P = 0.001). The resulting condition remained stable after 1 year. None of the patients showed any complications as a result of the therapy. Minimally invasive shaping of the distal eustachian tube under topical anesthesia can be recommended for patients with the above-mentioned diagnoses who have pathologic middle ear ventilation. Especially prior to tympanoplasties, and especially in otologic revision procedures, where middle ear ventilation is a prerequisite for successful otologic surgery, the function of the eustachian tube can be optimized in 70% of the patients, particularly if there are pathological findings (tubal tonsil, narrow orifice of the tubal ostium, adenoids). The placement of permanent ear tubes in adults with recurrent OME can also be avoided by the procedure described. The resultant conditions remained stable for the next year. Patients with tympanic ventilation problems due to rapid pressure changes (flying, diving) can also benefit from this procedure.

Postnatal change on the location of Ostmann's fatty tissue in the region lateral to Eustachian tube

OBJECTIVE

To delineate a possible role of protective function by Ostmann's fatty tissue (OF) in the lateral region to Eustachian tube (ET).

STUDY DESIGN

Morphometric and histopathological examination on human temporal bones.

METHODS

OF in the region lateral to the cartilaginous portion of the ET between the ET lumen and the tensor veli palatini muscle (TVP) was studied histopathologically and morphometrically by analyzing a series of vertically cut histologic sections for the ET structures. Sections were obtained from 25 individuals with age ranging from 33 gestational weeks to 38 years at the time of their death.

RESULTS

In fetus and neonates, the region lateral to ET was filled with mesenchyme. OF appeared first in this region at 2-3 weeks postnatally, and increased in volume with development of the ET. In the cases of older children and adults (Group-B), the ratio of the volume of OF in the region to that of ET lumen (OF/L) was significantly higher in the posterior half than in the anterior half of the cartilaginous portion of ET. However, in the cases of infants and younger children (Group-A), there was no significant difference in the ratio between the two regions. In the posterior half of the cartilaginous portion of ET, OF/L was significantly higher in Group-B than in Group-A, while in the anterior half, there was no significant difference in the ratio between two age groups (Group-A and B).

CONCLUSIONS

In Group-B, the dominant OF in the area of the posterior half of the cartilaginous region, which includes the narrowest portion of ET, may be responsible for restoring the ET lumen back to its closed static condition after active tubal opening by contraction of TVP. This is thought to be important for protection of the middle ear. On the other hand, in Group-A, poor OF near the narrowest portion of ET may cause insufficient restoration of the ET lumen and increased risk of developing otitis media (OM).

Postnatal changes in the connective tissue in the region lateral to the eustachian tube: possible relationship to tube function

In order to delineate the possible role of connective tissue (CT) in the region lateral to the eustachian tube (ET) between the ET lumen and the tensor veli palatini muscle (TVPM), we studied the postnatal changes in the CT in histologic sections of human ET. In fetuses and neonates, the lateral region was filled with mesenchyme. Loose collagenous CT appeared first at 2 weeks of age, and in subjects older than 4 years of age, the collagen formed dense, meshlike structures attaching to both the subepithelial CT layer of the ET and the tendonlike membrane of the TVPM. Along the long axis of the ET, those attachments were distributed mainly in the region at the posterior part of the cartilaginous portion of the ET. Attachments to the subepithelial CT layer of the ET were distributed mainly in the upper half of the region. The dense, meshlike collagenous CT might help the ET to be opened by drawing the lateral wall of the ET lumen through inferolateral movement of the tendonlike membrane of the TVPM when the TVPM contracts. It may work to open mainly the parts that include the narrowest portion of the ET, and also the upper aspect of the ET lumen. Incomplete development of this structure in infants may be one of the factors associated with dysfunction in ET opening.