Factors affecting hearing improvement following successful repair of the tympanic membrane.

BACKGROUND The main aim of tympanic membrane repair is the elimination of chronic or intermittent aural discharge. Hearing improvement may or may not occur following a technically successful operation. METHOD This study entailed a retrospective analysis of prospectively collected data from 203 operations that resulted in an intact tympanic membrane 6 months after surgery. RESULTS Complete hearing data were available for 169 operations on 160 patients. Of these, 53 per cent resulted in closure of the air-bone gap to within 10 dB, and 54 per cent of cases had post-operative hearing thresholds of at least 30 dB. The mean hearing change after surgery was +8.3 dB. Multiple regression analysis indicated that hearing improvement was more likely in large compared with small perforations. Smaller hearing gains occurred in ears with erosion of the stapes arch and/or fixation of the stapes, as well as in those with active discharge at the time of surgery and in revision cases. CONCLUSION Greater hearing improvement can be expected following successful repair of perforations involving more than 50 per cent of the drum area. Poorer results are likely to occur in ears with additional middle-ear pathology and in revision cases.