The Eustachian tube (ET) is a unifying passageway between the nose and ear and its function remains incompletely understood. ET dysfunction is the most commonly implicated cause in a number of middle ear pathologies. The dysfunction most commonly relates to obstruction of the ET and may be because of a wide array of causes, more commonly physiological rather than anatomical. Transnasal balloon dilatation of the ET (BET) was first described in the literature 5 years ago by the Bielefeld group in Germany, and shortly thereafter by two other U.S.A.-based groups in Boston and New York.
These three initial studies reviewed the method in cadaver models and all concluded that the procedure was both feasible and safe. A recent systematic review examined the evidence for BET. Although no published randomized controlled trials or case-control studies were identified, existing case series did suggest a benefit with safety and feasibility reaffirmed.
Across the studies analyzed by this systematic review, efficacy of BET was demonstrated in up to 70% of patients. A subsequently published large study of 622 patients demonstrated similar efficacy. Although the literature points to the cartilaginous portion of the ET being the most likely site of pathology, increasing the minimal cross sectional area is the key philosophy of almost all other clinical applications of balloon dilation catheters. Data from threedimensional computer-aided reconstructions of histological slides show that the minimum cross-sectional area lies in the lateral aspect of the cartilaginous ET consistently within 5 mm of the junctional portion. Given the length of the ET and commonly used balloon catheters, it is likely this minimum area is missed in a significant proportion of transnasal balloon dilation, which may afford the transtympanic technique a unique advantage. Transtympanic BET may warrant consideration in patients undergoing simultaneous middle ear surgery, as they often have coincident ET dysfunction.
Additionally, a potential indication for the transtympanic approach may be in patients in whom the transnasal approach has failed. However, these are theoretical indications and direct comparison of the respective indications and merits of the two approaches is beyond the scope of the present study. Two studies to date have specifically looked at transtympanic BET, one in a cadaver model and the other in human subjects. The aim of this work is to evaluate the safety and shortterm efficacy of transtympanic balloon dilatation in the cadaveric model. The study is unique in design using full endoscopic visualization of insertion and dual endoscopic confirmation of correct balloon position. Efficacy will be tested with manometry and blinded radiologist review.