[Treatment of chronic tube dysfunction. Use of the tube conductor]

Investigation of Stent Prototypes for the Eustachian Tube in Human Donor Bodies

Chronic otitis media is often connected to Eustachian tube dysfunction. As successful treatment cannot be guaranteed with the currently available options, the aim is to develop a stent for the Eustachian tube (ET). Over the course of this development, different prototypes were generated and tested in ex vivo experiments. Four different prototypes of an ET stent and one commercially available coronary stent were implanted in the ET of seven human donor bodies. The position of the stents was verified by cone beam CT. The implanted ETs were harvested, embedded in resin and ground at 200 µm steps. Resulting images of the single steps were used to generate 3D models. The 3D models were then evaluated regarding position of the stent in the ET, its diameters, amount of squeezing, orientation of the axes and other parameters. Virtual reconstruction of the implanted ET was successful in all cases and revealed one incorrect stent placement. The cross-section increased for all metal stents in direction from the isthmus towards the pharyngeal orifice of the ET. Depending on the individual design of the metal stents (open or closed design), the shape varied also between different positions along a single stent. In contrast, the cross-section area and shape remained constant along the polymeric prototype. With the current investigation, insight into the behavior of different prototypes of ET stents was gained, which can help in defining the specifications for the intended ET stent.

Stenting the Eustachian tube to treat chronic otitis media - a feasibility study in sheep

BACKGROUND

Untreated chronic otitis media severely impairs quality of life in affected individuals. Local destruction of the middle ear and subsequent loss of hearing are common sequelae, and currently available treatments provide limited relief. Therefore, the objectives of this study were to evaluate the feasibility of the insertion of a coronary stent from the nasopharynx into the Eustachian tube in-vivo in sheep and to make an initial assessment of its positional stability, tolerance by the animal, and possible tissue reactions.

METHODS

Bilateral implantation of bare metal cobalt-chrome coronary stents of two sizes was performed endoscopically in three healthy blackface sheep using a nasopharyngeal approach. The postoperative observation period was three months.

RESULTS

Stent implantation into the Eustachian tube was feasible with no intra- or post-operative complications. Health status of the sheep was unaffected. All stents preserved their cylindrical shape. All shorter stents remained in position and ventilated the middle ear even when partially filled with secretion or tissue. One of the long stents became dislocated toward the nasopharynx. Both of the others remained fixed at the isthmus but appeared to be blocked by tissue or secretion. Tissue overgrowth on top of the struts of all stents resulted in closure of the tissue-lumen interface.

CONCLUSION

Stenting of the Eustachian tube was successfully transferred from cadaver studies to an in-vivo application without complications. The stent was well tolerated, the middle ears were ventilated, and clearance of the auditory tube appeared possible. For fixation, it seems to be sufficient to place it only in the cartilaginous part of the Eustachian tube.

[Balloon dilatation of the Eustachian tube during middle ear surgery : Study planning and first experiences during recruitment]

BACKGROUND

Eustachian tube dysfunction is considered a major contributor to chronic middle ear disease. In clinical case series, the results of balloon dilation (balloon Eustachian tuboplasty, BET) as a treatment for Eustachian tube dysfunction have been reported.

OBJECTIVE

This study aims to analyze whether patients undergoing planned surgery for chronic middle ear disease would benefit from additional BET.

METHODS

In a randomized controlled, patient and observer (not surgeon)-blind clinical study, 100 adult patients with planned surgery for chronic middle ear disease will be investigated. Patients will be randomized into two groups, one of which (50%) will receive additional BET of the affected side during the planned surgery. Eustachian tube function will be evaluated using the Valsalva maneuver and tubomanometry according to Estève, as well as on the basis of patient reports. Various scores will be used as outcome measures, including ETS-5 (Eustachian Tube Score 5), the extended version ETS-7, and the ETDQ-7 (Seven-Item Eustachian Tube Dysfunction Questionnaire). Follow-up is at 3, 6, and 12 months.

RESULTS

From June to December 2015, 162 patients underwent microscopic ear surgery. Inclusion criteria were not fulfilled by 90 patients. Of the remaining 72 patients with chronic middle ear disease, 12 patients (17%) have been randomized so far, 28 (39%) did not exhibit Eustachian tube dysfunction, and 32 (44%) patients could not be included for other reasons.

CONCLUSION

The rate of recruitment was lower than expected. Depending on the case number calculations for the patient groups identified in the study for whom BET might be particularly beneficial, multicenter studies in specific disease groups may follow.

Evidence and evidence gaps in the treatment of Eustachian tube dysfunction and otitis media

Evidence-based medicine is an approach to medical treatment intended to optimize patient-oriented decision-making on the basis of empirically proven effectiveness. For this purpose, a classification system has been established to categorize studies - and hence therapy options - in respect of associated evidence according to defined criteria. The Eustachian tube connects the nasopharynx with the middle ear cavity. Its key function is to ensure middle ear ventilation. Compromised ventilation results in inflammatory middle ear disorders. Numerous evidence-based therapy options are available for the treatment of impaired middle ear ventilation and otitis media, the main therapeutic approach being antibiotic treatment. More recent procedures such as balloon dilation of the Eustachian tube have also shown initial success but must undergo further evaluation with regard to evidence. There is, as yet, no evidence for some of the other long-established procedures. Owing to the multitude of variables, the classification of evidence levels for various treatment approaches calls for highly diversified assessment. Numerous evidence-based studies are therefore necessary in order to evaluate the evidence pertaining to existing and future therapy solutions for impaired middle ear ventilation and otitis media. If this need is addressed, a wealth of implications can be expected for therapeutic approaches in the years to come.

Treatment of middle ear ventilation disorders: sheep as animal model for stenting the human Eustachian tube--a cadaver study

Eustachian tube disorders can lead to chronic otitis media with consecutive conductive hearing loss. To improve treatment and to develop new types of implants such as stents, an adequate experimental animal model is required. As the middle ear of sheep is known to be comparable to the human middle ear, the dimensions of the Eustachian tube in two strains of sheep were investigated. The Eustachian tube and middle ear of half heads of heathland and blackface sheep were filled with silicone rubber, blended with barium sulfate to induce X-ray visibility. Images were taken by digital volume tomography. The tubes were segmented, and a three-dimensional model of every Eustachian tube was generated. The lengths, diameters and shapes were determined. Additionally, the feasibility of endoscopic stent implantation and fixation was tested in cadaver experiments. The length of the tube between ostium pharyngeum and the isthmus and the diameters were comparable to published values for the human tube. The tube was easily accessible through the nose, and then stents could be implanted and fixed at the isthmus. The sheep appears to be a promising model for testing new stent treatments for middle ear ventilation disorders.

[Therapy of chronic obstructive eustachian tube dysfunction: evolution of applied therapies]

This paper reviews the past and present developments in the treatment of chronic obstructive eustachian tube dysfunction. Alongside tube catheterization and bougie insertion, modern approaches such as laser eustachian tuboplasty and balloon eustachian tuboplasty (BET) are described. In BET, transnasal endoscopic insertion via the pharyngeal ostium places a balloon catheter in the cartilaginous portion of the eustachian tube. This is then dilated to a pressure of 10 bar for 2 min. Up until January 2013, 351 chronic obstructive eustachian tube dysfunction patients had been treated in our department using BET. The average preoperative eustachian tube score was 2.1 (± 1.8 standard deviation, SD); 12 months postoperatively it was 6.1 (± 2.6 SD). Of these patients, 87% expressed satisfaction with the improvement in chronic obstructive dysfunction. These results demonstrate that BET is a safe and effective treatment for improving eustachian tube function and ear ventilation.