Treatment of Middle Ear Ventilation Disorders: Sheep as Animal Model for Stenting the Human Eustachian Tube – A Cadaver Study

Abstract

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.

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

“…However, Miller et al . reported that the ET curvature of blackface sheep had an angle of 162.4° and decreased from the pharyngeal orifice to the tympanic orifice (Miller et al ., ). The ET of the miniature pig was approximately the same shape as that of the sheep, but it had a completely different course.…”

“…Miller et al . () used a silicone model to evaluate the dimensions of the ET. This method is suitable for studying a cavity or tube, and we used this approach in the present study.…”

“…Pracy reported that the pig ET and middle ear are very similar to those in humans, being approximately the same size and following a more or less identical development course in both species (Pracy et al ., ). Recently, a sheep cadaver model has been used successfully for endoscopic implantation of a stent from the pharyngeal orifice (Miller et al ., ), indicating that large animal models would be more suitable for ET studies than the small animals mentioned above. Whether endoscopy can access the pharyngeal orifice of the pig ET through the nose has not been determined.…”

Reconstruction of biological functions: novel implant concepts for cardiovascular, ophthal-mologic and otolaryngologic applications

“…Here, a permanent stent or temporary scaffold shall be applied for the restoration of the physiological venting function of the Eustashian tube, mediated by anti-inflammatory and antiinfective local drug release [16].…”

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

“…However, the success rate could not be confirmed in a following study [65]. Currently tube stents are developed to improve the tube function with transpharyngeal insertion [77]. In first investigations with sheep, chrome cobalt coronary stents (ProKinetic Energy) (Figure 13 (Fig.…”