Pre-operative Evaluation of Eustachian Tube Function Using a Modified Pressure Equilibration Test is Predictive of Good Postoperative Hearing and Middle Ear Aeration in Type 1 Tympanoplasty Patients

OBJECTIVES: The Eustachian tube (ET) plays an important role in maintaining a normally aerated middle ear. Inflammation in middle ear disease is related to ET dysfunction, and postoperative restoration of middle ear integrity and hearing are closely related to ET function in chronic ear disease patients. After successful tympanoplasty, restoration of a well-aerated middle ear with good ET function can permit better compliance of the tympanic membrane. In this study, we evaluated the predictive validity of preoperative ET function measurements. METHODS: We reviewed 137 patients who underwent type 1 tympanoplasty. All patients had non-cholesteatomatous chronic otitis media and received canal wall-up-type tympanomastoidectomies. Patients were categorized into four groups according to preoperative ET function measurements using a modified pressure inflation-deflation equilibration test. Group I patients had residual pressures less than 10 daPa, and Group IV patients showed no pressure change (poor results). Groups II and III were intermediate. Hearing levels were determined using pure tone averages at four frequencies. Postoperative tympanography was performed to determine middle ear aeration. RESULTS: The preoperative air bone (AB) gap was 29.6±7.0 dB, and the postoperative gap was 16.5±5.7 dB; thus, there was significant overall improvement. In all groups, hearing was significantly better after surgery, but the worst postoperative hearing level was seen in Group IV patients. Type B tympanograms were more frequently recorded in Group IV patients than they were in Group I or II patients. Postoperative AB gaps were 9.2±3.8 dB in patients with type A tympanograms, 13.4±2.1 dB in those with type As, 24.1±2.5 dB in those with type C, and 18.5±2.8 dB in those with type B. CONCLUSION: ET function measured with a modified pressure equilibration test using an inflation-deflation manometric method is a good indicator of an aerated middle ear and is predictive of improved postoperative hearing.