Do high-frequency air-bone gaps persist after ossiculoplasty?

OBJECTIVES

Conventional reporting of postoperative hearing outcomes utilizes a pure-tone averaged air-bone gap (ABG) that is biased toward low frequencies. Consequently, a high-frequency ABG after otologic surgery may go unnoticed. In this study, we evaluate changes in low- and high-frequency ABG following ossiculoplasty.

STUDY

DESIGN

Retrospective review.

SUBJECTS AND

SETTING

Consecutive series of patients who underwent ossiculoplasty at a single tertiary care center. Patients with pre- and postoperative audiograms were included.

METHODS

Low-frequency ABG was calculated as the mean ABG at 250, 500, and 1000 Hz. High-frequency ABG was calculated at 4 kHz. Pre- and postoperative ABGs were compared.

RESULTS

Thirty-seven consecutive patients were included. Mean age at surgery was 38 years (range, 7-77 years). Reconstruction materials included: cartilage (N = 4), hydroxyapatite cement (N = 5), and partial or total ossicular replacement prostheses (N = 20 and N = 8, respectively). Postoperatively, the mean low-frequency ABG improved by 11.9 ± 15.1 dB (P < .0001) and the mean high-frequency ABG improved by 5.9 ± 16.0 dB (P = .030). Low-frequency ABG closure was significantly larger than high-frequency ABG closure (P = .007). Mean postoperative persistent high-frequency ABG was 22.0 ± 13.8 dB.

CONCLUSION

In this series, ossiculoplasty improved ABG across all frequencies, but greater improvements were observed at low frequencies when compared to high frequency. Current reporting standards may not identify persistent high-frequency ABG. Additional study of the mechanisms of high-frequency sound conduction in reconstructed middle ears is needed to improve high-frequency hearing outcomes in ossiculoplasty.

LEVEL OF EVIDENCE: Level 4.