This technique appears to provide a completely new dimension for the audiologic rehabilitation of patients with severe malformation of the middle ear.

Objectives: The safety and performance of the Otologics fully implantable hearing device were assessed in adult patients with mixed conductive and sensorineural hearing loss. Methods: The subcutaneous microphone of this fully implantable device picks up ambient sounds, converts them into an electrical signal, amplifies the signal according to the user’s needs, and sends it to an electromechanical transducer. The transducer tip is customized with a prosthesis in order to be in contact with the round window membrane and is protected by fascia; this translates the electrical signal into a mechanical motion that directly stimulates the round window membrane and enables the user to perceive sound. The implanted battery is recharged daily via an external charger and the user can turn the implant on and off as well as adjust the volume with a hand-held remote control. In this pilot study, 6 patients with mixed conductive and sensorineural hearing loss were implanted with the Otologics fully implantable hearing device. Pre- and postoperative air conduction, bone conduction, as well as aided and unaided thresholds and speech scores were measured. Results: No significant differences between preoperative and postoperative pure-tone averages were noted. Average improvement ranged from 19.16 to 35.8 dB of functional gain across audiometric frequencies with a mean of 26.17 ± 5.15 dB. Long-term average functional gain at 12 months was 20.83 ± 6.22 dB. Word recognition scores demonstrated significant differences between unaided and implant-aided conditions. Conclusions: Preliminary results of this trial of the Otologics fully implantable hearing device provide evidence that this fully implantable device is capable of efficiently transferring the sound to the inner ear via the round window membrane in patients with mixed hearing loss.

In the semi-implantable clinical trials, METF(MET) was -10 to -15 dB for frequencies above 1 kHz, and dropped to -15 to -20 dB for lower frequencies. Fully implantable clinical trial results were 10-20 dB better than the semi-implantable trial results, with less variability at all frequencies. These findings indicate more consistent and better coupling efficiency of the transducer to the ossicles.

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The greatest anatomical vibrations that an implanted microphone must overcome are because of vocalization in the soft tissue inferior to the mastoid and chewing vibrations on the mastoid. A human cadaver is an appropriate model for transducer cranial vibration studies. If the implantable microphone is placed on the cranium near the pinna, it makes little difference with regard to actual location.