The effect of the "floating mass transducer" in the middle ear on hearing sensitivity.

OBJECTIVE: The Vibrant soundbridge is a semi-implantable hearing device; the transducer is implanted, coupled directly to the incus. The influence of the implant surgery and the presence of the transducer on hearing sensitivity was studied in six implanted subjects. STUDY DESIGN: Longitudinal case reports. SETTING: Tertiary referral center. Subjects. The subjects had bilateral sensorineural hearing loss with an average hearing loss of 40 to 70 dB HL. RESULTS: In five of the six subjects, no long-term effect of the surgery or the presence of the transducer on hearing thresholds was found. In the remaining subject, a deterioration in hearing thresholds was found of 20 dB, with a high and low frequency component. In the 2-kHz region, hearing sensitivity was not deteriorated. In addition, chronic negative middle ear pressure occurred after surgery. CONCLUSION: Hearing thresholds did not change significantly in five of the six patients after placement of the "floating mass transducer." It was speculated that the high frequency component of the hearing deterioration in the remaining patient was caused by cochlear damage caused by the surgery and that the low frequency component was caused by the chronic aeration problems indirectly related to the surgery.