Validation of hearing results in tympanoplasty: a preliminary report

In the otological literature, the results of middle ear surgery are frequently reported by closure of the air-bone gap and improvement of the air-conduction threshold in dB HL. These parameters are valid as a reflection of the technical success, but do not evaluate the effect of surgery on binaural hearing. In the literature two methods have been proposed for predicting patient benefit in reconstructive middle ear surgery: the Rule of Thumb and the Glasgow Benefit Plot. Both methods are based on the arbitrary cut-off level of 30 dB HL for normal or socially acceptable hearing. However, a reliable preoperative prediction of patient benefit can only be made after validation of the definition of normal or socially acceptable hearing expressed in dB HL by means of a questionnaire measuring the limitations of adequate hearing. A clear relationship is found between the subjective hearing ability and the air-conduction thresholds that supports 30 dB HL as the cut-off level for normal or socially acceptable hearing. Further validation of this cut-off level in a more extensive prospective study is needed to provide a significant prognosis for normal or socially acceptable hearing.