Intraoperative quantification of floating mass transducer coupling quality in active middle ear implants: a...

Area of Science:

• Audiology
• Neuroscience
• Biomedical Engineering

Background:

• The Vibrant Soundbridge (VSB) is an active middle ear implant.
• Assessing the coupling quality of the floating mass transducer (FMT) is crucial for VSB performance.
• Intraoperative auditory brainstem responses (ABRs) offer a potential method for real-time assessment.

Purpose of the Study:

• To evaluate the effectiveness of intraoperative ABRs in quantifying VSB FMT coupling quality.
• To determine if intraoperative VSB-evoked ABR (VSB-ABR) thresholds can predict postoperative coupling status.
• To assess the potential for optimizing audiological results through intraoperative feedback.

Main Methods:

• A multicentric diagnostic study included 23 patients (age >18) with VSB implants and varying coupling modalities.
• Measurements included pre- and postoperative bone conduction thresholds, intraoperative VSB-ABR thresholds, and postoperative vibrogram and VSB-ABR thresholds.
• Coupling quality was calculated by comparing postoperative vibrogram and bone conduction pure tone averages (3PTA).

Main Results:

• Intraoperative VSB-ABR thresholds were obtainable in 22 out of 23 patients.
• One patient with an insufficient coupling of 36.7 dB showed an intraoperative threshold >30 dB nHL.
• Bland-Altman analysis showed limits of agreement exceeding ±10 dB, but within the general precision of ABRs for predicting behavioral thresholds; five outliers were identified.

Conclusions:

• Intraoperative VSB-ABR thresholds show potential for predicting VSB coupling quality.
• This technique can aid in optimizing postoperative audiological outcomes for VSB implant recipients.
• Real-time intraoperative monitoring can identify coupling issues, allowing for adjustments to improve device function.