Is pre-operative audiometry a reliable predictor of ossicular chain condition?

Objective: Investigation of ossicular chain (OC) status before surgery is important for preoperative patient consultation. This research aimed to investigate the relationship between pre-operative audiometric values and intra-operative OC condition in a relatively large population of chronic otitis media (COM) surgeries.

Methods: In this descriptive-analytic cross-sectional study, we evaluated 694 patients who underwent COM surgeries. We analyzed pre-operative audiometric data and intraoperative findings including ossicular anatomy, ossicular mobility, and the condition of middle ear mucosa.

Results: The optimal cut-off values of pre-operative speech reception threshold (SRT), mean air-conduction (AC), and mean air-bone gap (ABG) for predicting OC discontinuity were 37.5 dB, 37.2 dB, and 28.4 dB, respectively. For the prediction of OC fixation, the optimal cut-off points of SRT, mean AC, and mean ABG were 37.5 dB, 40.3 dB, and 32.8 dB, respectively. The computing of Cohen's d (95 % confidence interval) demonstrated the greater mean ABG in ears with OC discontinuity in comparison with ears with normal ossicles in all types of pathologies. There was a descending trend of Cohen's d from cholesteatoma to tympanosclerosis and then to granulation tissue and hypertrophic mucosa. There was a substantial relation between the type of pathology and OC status (P < 0.001). Ears with tympanosclerosis plaque had the most fixed OC among all types of pathologies (40 ears, 30.8 %), and ears with no pathology had the most normal OC (135 ears, 83.3 %).

Conclusions: The results supported the view that pre-operative hearing is a key determining factor for the prediction of OC status.