Threshold monitoring of intraoperative auditory steady-state responses for ossiculoplasty surgery.

OBJECTIVE

The objective of this study is to establish a reliable intraoperative auditory threshold monitoring system for ossiculoplasty surgery.

DESIGN

The chirp signal of self-designed sound field earphone (SFE) was calibrated physically and psychophysically. The interaural attenuation of the SFE was tested in patients with unilateral complete deafness and contralateral normal hearing (10 patients). Self-designed SFEs were used to measure the chirp-evoked auditory steady-state responses (Chirp-ASSR) threshold of patients (14 cases and 15 ears) with conductive hearing loss after anesthesia but before surgery.

RESULTS

The response threshold of Chirp-ASSR under anesthesia displayed a strong correlation with the hearing threshold for pure tones: the Pearson coefficients at various frequencies (1, 2, and 4 kHz) were 0.56 (p = .03), 0.82 (p < .001), and 0.90 (p < .001), respectively, and the intragroup correlation coefficients were 0.70 (p = 0.02), 0.90 (p < 0.001), and 0.95 (p < 0.001), respectively. The average test time was 7.0 ± 0.7 min.

CONCLUSIONS

By combining Chirp-ASSR with self-designed SFE, we obtained objective multi-frequency intraoperative auditory thresholds that correlate well with the pure tone audiometry threshold. This reliable system can be applied to future intraoperative auditory threshold monitoring for ossiculoplasty surgery.