Role of Impedance Audiometry in Evaluation of Eustachian Tube Function and Its Correlation with Tympanoplasty Surgery Outcome: Our Experience

Background: Normal Eustachian tube function is one of the important factor required for successful tympanoplasty outcome. A clinically useful test for assessment of Eustachian tube function is still lacking. Aims And Objectives: To evaluate Eustachian tube function by impedance audiometry and compare the outcome of surgery with respect to graft take up in normal and abnormal Eustachian tube function. Study design Prospective study. Materials and Methods: Study includes 60 patients diagnosed as chronic suppurative otitis media, mucosal type in quiescent or inactive stage. All patients were evaluated with detailed history, ENT examination and radiological investigations. Eustachian tube function was assessed with impedance audiometry. Preoperative Eustachian tube function results were compared with postoperative surgical outcome and results were analyzed. Results: On impedance audiometry 65% patients had normal Eustachian tube function and 35% had impaired function. Overall graft take up rate was 91.66% and failure rate was 8.34%. Tympanoplasty was successful in 94.87% patients with normal Eustachian tube function and in 85.71% with impaired function and difference was not statistically significant (P >0.05). Hearing improvement in terms of air-bone gap closure (AB gap < 20db) was more in patients with normal Eustachian tube function (61.66%). Conclusion: Impedance audiometry is a simple and easy method to assess Eustachian tube function. It not merely assess the anatomical patency but also the physiological function of Eustachian tube. Outcome of Tympanoplasty would be a success in normal Eustachian tube function but impaired tubal function should not be the ground for refusal of surgery.