Availability of audiological evaluation for the differential diagnosis of clinical otosclerosis.

Objective: The availability of an audiological evaluation for the differential diagnosis of clinical otosclerosis (OS) was examined. Methods: Included were 98 patients (107 ears) with OS and 19 patients (20 ears) with incudostapedial disconnection (ISD) diagnosed by surgery between 2009 and 2017 at Aichi University Hospital. Results of preoperative pure-tone audiometry and impedance audiometry were analyzed. The most reliable index for distinguishing the two diseases was evaluated, and the cut-off value, sensitivity, and specificity were calculated. Results: In the univariate analysis, age, static compliance, reversed ipsilateral acoustic reflex (reversed IAR) at 0.5 kHz and 2 kHz, negative contralateral acoustic reflex (negative CAR), difference between the air-bone gap at 0.25 and 2 kHz (0.25-2 kHzABG) and that at 0.25 and 4 kHz (0.25-4 kHzABG) showed statistical significance between the two diseases, whereas the Carhart notch did not. Multivariate logistic regression analysis by the variable selection method showed that reversed IAR (0.5 kHz), negative CAR, and 0.25-4 kHzABG were statistically significantly better factors for the differential diagnosis of the two diseases. The receiver operating characteristic curve for diagnosing OS using the difference between air-bone gap at 0.25 kHz and 4 kHz showed moderate accuracy. If the cut-off value of 0.25-4 kHzABG was 10 dB, then the sensitivity and specificity were 81.1% and 55.0%, respectively. In other words, if the cut-off value of 0.25-4 kHzABG was less than 10 dB, then the possibility of diagnosing ISD becomes higher, and if greater than 10 dB, then the possibility of diagnosing OS becomes higher. Conclusion: The differences in the air-bone gap at low and high frequency in pure-tone audiometry, static compliance, and acoustic reflex in impedance audiometry are useful for distinguishing OS from ISD. However, combinations of several examinations including computed tomography imaging are needed for the differential diagnosis of other ear diseases and specific preoperative planning. (C) 2020 Oto-Rhino-Laryngological Society of Japan Inc. Published by Elsevier B.V. All rights reserved.