Predicting the Subjective Hearing Outcome in Type I Tympanoplasty Using Belfast 15/30db Rule of Thumb.

Abstract

OBJECTIVE: Both Otologists and patients mutually hope for an improvement in hearing and a functional benet from an ear surgery to correct unilateral conductive hearing loss that has been reported as the closure of air-bone gap or reduction in air conduction thresholds. While these provide a measure of technical success of the operation, they may not always translate into real life benet for the patient. This is because listening is a binaural task and benet to the patient is determined by numerous factors, of paramount importance is hearing in the non-operated ear. With the aim, to estimate patient benet in terms of subjective hearing gain after type I tympanoplasty, we reviewed the Belfast 15/30 dB rule of thumb. METHOD: A 100 cases of chronic otitis media with inactive mucosal disease having conductive hearing loss, who had undergone type I tympanoplasty were included. Hearing was assessed using pure tone audiogram with average of, .5, 1, 2 & 4Hz and a detailed questionnaire regarding the subjective perception of hearing was obtained pre and 6 month post-operatively which was correlated with Belfast 15/30 dB rule of thumb. RESULT: The predictive value as per pure tone audiometry with Belfast 15/30 dB rule of thumb is 89% with a conclusion that the objective hearing improvement (88.1%) does not necessarily transform into patients' perception of hearing improvement (78.4%) CONCLUSION: Hearing is a binaural function and this should always be kept in mind while operating on unilateral/ asymmetric hearing loss patients as mere closure of air-bone gap or reduction in air conduction threshold might not conclude patients' perception of hearing gain. Belfast 15/30 dB rule of thumb has proved to be a valuable tool in predicting the subjective improvement of hearing