Prediction of the bone conduction gain curve after partial posterior stapedectomy: the frequency shift concept.

INTRODUCTION In this article, we present a method able to reasonably predict the bone conduction (BC) gain curve. It provides the advantage of advising patients who will receive little benefit from surgery. MATERIALS AND METHOD A group of 284 cases is studied in an attempt to verify the poststapedectomy predictability of their characteristic gain curve (CGC) to define a pattern, which indicates the outcome of surgery. For that purpose, the postoperative BC curve has been modeled by fitting a linear regression curve (LRC), which I refer to here as "baseline," into the average audiogram of the 284 cases. RESULTS Using the average baseline as the predicted postoperative BC audiogram, in 77% of the cases, the predicted CGC is qualitatively comparable to the measured one. DISCUSSIONS The postoperative baseline can be modeled as a shifting of the average frequency of the preoperative baseline toward higher frequencies. This method is useful to predict the probabilities of having a negative slope in the gain curve after stapes surgery and, therefore, will help in the decision-making process for the indication of surgery and to advise patients on the results they can expect to have. A description of the steps to follow for the application of this method is made available.