Intraoperative Recording of Auditory Brainstem Responses for Monitoring of Floating Mass Transducer Coupling Efficacy During Revision Surgery-Proof of Concept.

OBJECTIVE: The objective of the study was to measure auditory brainstem responses elicited by stimulation via a semi-implantable active middle ear implant with an electromagnetically driven floating mass transducer to quantify the coupling efficacy (=vibroplasty in situ thresholds - bone conduction thresholds) in a patient during a revision surgery.

PATIENTS: One patient, reimplanted with an active middle ear implant in a revision surgery.

INTERVENTION(S): Diagnostic.

MAIN OUTCOME MEASURE(S): Intraoperative auditory brainstem responses evoked by stimulation via an active middle ear implant in a calibrated set-up directly indicating the coupling efficacy magnitude (auditory brainstem response threshold = coupling efficacy), as well as pre- and postoperative bone conduction and vibroplasty in situ thresholds.

RESULTS: The intraoperative auditory brainstem response threshold was detected at 0 dB nHL, i.e., the magnitude of coupling efficacy was determined intraoperatively to be 0 dB. The actual postoperative coupling efficacy (=postoperative vibroplasty in situ - postoperative bone conduction thresholds) was -2.5 dB.

CONCLUSIONS: The coupling efficacy determined intraoperatively was consistent with the postoperative coupling efficacy. The described method seems to be a promising tool to objectively quantify the magnitude of coupling efficacy in active middle ear implant surgeries.