Is there an optimal location for tympanostomy tube placement?

BACKGROUND Tympanostomy tube placement is the most common surgical procedure in children. It is performed on about 1 million children and 1 million adults in the United States annually. In the past decades, tympanostomy tubes have been shown to reduce the incidence of otitis media–related complications. Although it is a welltolerated procedure with a low risk of complications, chronic perforation after tube extrusion has an incidence of 2% with short-term tubes and 16% for long-term tubes. Thus, there is an expected annual incidence that is conservatively >40,000 perforations in children and adults in the United States alone. Most perforations are readily repaired, but anteriorly located perforations may be more challenging to surgically close than posterior holes. Originally, tubes were often placed using spinal needles for the myringotomy and involved working through an otoscope. The anterior-inferior quadrant was frequently recommended to stay maximally far from the posterior-superior quadrant under which the ossicles are located. Most textbooks have recommended placement of tympanostomy tubes into the anterior-inferior quadrant with the hopes of: 1) longer duration in the tympanic membrane (i.e., prolonged function), 2) avoidance of the ossicular chain, 3) prevention of hearing loss that could theoretically result from a perforation being located over the round window, and 4) easier visibility through the tube to view the patency of the lumen and to see the status of the middle ear mucosa. LITERATURE REVIEW Stinson performed experiments placing India ink on tympanic membranes and observed that the epithelium migrated from the anterior-superior quadrant and circulated around the umbo toward the posterior part of the tympanic membrane. It was subsequently theorized that tympanostomy tubes might stay in place longer within the tympanic membrane if inserted into the anterior tympanic membrane, and the anterior-inferior quadrant was most frequently employed. However, this hypothesis, along with Stinson’s observations, were not supported by other researchers. Alberti found that epithelial migration occurred most often in a radial pattern from the malleus to the periphery, with only 20% of cases demonstrating epithelial migration patterns such as those found in the India ink study. O’Donoghue followed actual tympanostomy tube movement within tympanic membranes and found that only 37% of the tympanostomy tubes migrated to any degree, whereas the remainder maintained the same position of insertion. Moreover, Gibb and Mackenzie performed a prospective study on the extrusion rate of 939 tympanostomy tubes and found that 537 were inserted into the anterior-inferior quadrant, 189 into the anterior-superior quadrant, and 213 into the posteriorinferior quadrant. No difference was found in the times to extrusion among these three insertion locations. Thus, the study did not support the hypothesis for anterior-inferior tube insertion. The effect of location of perforation on hearing was evaluated by Mehta et al. in studies of middle ear mechanics in temporal bones. The effect was also noted in patients with 29 perforations of similar size and middle ear volume but at different locations. The temporal bone results suggested that middle ear volume—and not location of perforation—was the primary determinant of whether perforations of similar sizes would be expected to generate different degrees of conductive hearing loss. A smaller volume (middle ear plus mastoid airspace) was predictive of a larger air-bone gap for a perforation of a given diameter. Therefore, patients with contracted mastoids or tympanic membrane atelectasis would be more likely to have conductive hearing loss for a given size perforation compared to a perforation in an otherwise normal middle ear and mastoid. The bench results From the Department of Otolaryngology & Communication Enhancement (I.K., D.P.), Boston Children’s Hospital and Harvard Medical School, Boston, Massachusetts, U.S.A; and the Department of Otorhinolaryngology (I.K.), Tampere University Hospital and the University of Tampere, Tampere, Finland.