First, to assess for the performance of the Carina placed on the round window at various European centers; second, to study the follow-up after 2 years and discuss limitations and technical issues; and finally, to further develop our understanding of the principles of acoustic transfer through the round window. Eleven patients were included in this retrospective study (7 women and 4 men) from 7 European tertiary referral hospitals (4 centers in France, 2 in Belgium, 1 in Spain). The mean age was 50.8 years (35-71 yr). All patients have multiple previous surgeries (>3 surgical procedures) for otosclerosis (3 patients) or chronic otitis media (8 patients), and in all cases, the stapes was not accessible due to obliteration by sclerotic tissue. Preoperative and postoperative air conduction, bone conduction, as well as aided and unaided thresholds and speech scores were measured. No significant differences were observed between preoperative and postoperative air-conduction and bone-conduction pure-tone averages. The average free field functional gain obtained with the implant ranged from 22 to 42 dB at each individual frequency, with a mean of 29 ± 5 dB across all audiometric frequencies. Word recognition scores demonstrated significant differences between unaided and implant-aided conditions. Complications included 2 cases of postoperative infection (including 1 anacusis) that required explantation, and 1 case reduced initial benefit, followed by a nonfunctioning device. In 10 patients, postoperative hearing was unchanged. The 8 other patients are using their implant daily. These results show that this option is valid for patients with a fixed footplate and unsuccessful previous surgeries or patients who cannot benefit from a stapedotomy for anatomic reasons. In some cases, access to the round window membrane could represent a limitation. However, these promising initial results establish the need for further works with regard to 3 issues: 1) clinical data studies are needed, including a greater number of patients to confirm these preliminary results; 2) a long-term follow-up must be performed to detect any possible cochlear adverse effects, in particular, on the basilar membrane; 3) the effect of fascia interposition and tip size has to be evaluated in experimental studies.

Objectives: To assess the importance of 2 variables, transducer tip diameter and resection of the round window (RW) niche, affecting the optimization of the mechanical stimulation of the RW membrane with an active middle ear implant (AMEI). Materials and Methods: Ten temporal bones were prepared with combined atticotomy and facial recess approach to expose the RW. An AMEI stimulated the RW with 2 ball tip diameters (0.5 and 1.0 mm) before and after the resection of the bony rim of the RW niche. The RW drive performance, assessed by stapes velocities using laser Doppler velocimetry, was analyzed in 3 frequency ranges: low (0.25–1 kHz), medium (1–3 kHz) and high (3–8 kHz). Results: Driving the RW produced mean peak stapes velocities (H_EV) of 0.305 and 0.255 mm/s/V at 3.03 kHz, respectively, for the 1- and 0.5-mm tips, with the RW niche intact. Niche drilling increased the H_EV to 0.73 and 0.832 mm/s/V for the 1- and 0.5-mm tips, respectively. The tip diameter produced no difference in output at low and medium frequencies; however, the 0.5-mm tip was 5 and 6 dB better than the 1-mm tip at high frequencies before and after niche drilling, respectively. Drilling the niche significantly improved the output by 4 dB at high frequencies for the 1-mm tip, and by 6 and 10 dB in the medium- and high-frequency ranges for the 0.5-mm tip. Conclusion: The AMEI was able to successfully drive the RW membrane in cadaveric temporal bones using a classical facial recess approach. Stimulation of the RW membrane with an AMEI without drilling the niche is sufficient for successful hearing outputs. However, the resection of the bony rim of the RW niche significantly improved the RW stimulation at medium and higher frequencies. Drilling the niche enhances the exposure of the RW membrane and facilitates positioning the implant tip.

Hypothesis Coupling and placement of actuators onto the ossicular chain have a significant influence on active middle ear implant (AMEI) performance. Background AMEIs have proved to be effective in treating moderate-to-severe sensorineural hearing loss as well as mixed and conductive loss. Here, we assess the effect on performance of an AMEI prosthesis using 5 different methods of coupling to the ossicular chain in 6 temporal bones. Methods The AMEI provided direct vibratory stimuli to the incus using the following methods: 1) tip of the transducer in contact with incus body (baseline condition), 2) tip of the transducer placed in a laser-drilled hole in the incus body, 3) the àWengen clips (straight and articulated) crimped to the transducer and attached to the incus long process, 4) a 0.5-mm diameter cylinder placed in contact with the incus long process, and 5) a bell-shaped prosthesis in contact with the head of the stapes. Performance in each condition was assessed by measuring the resultant stapes velocities (H_EV) from which the maximum equivalent ear canal sound pressure levels (L_Emax) were computed. Results Relative to the baseline condition, which produced L_Emax of 112 to 126 dB SPL for frequencies of 0.25 to 8 kHz, the other coupling methods produced similar or substantially improved (increased L_Emax) performance. Best performance was achieved by providing vibratory stimulation to the head of the stapes directly with the bell-shaped tip where performance improved significantly by 16 to 22 dB. Conclusion Stapes velocities produced by AMEI transducers may be increased depending on the tip used to couple the transducer to the ossicular chain and the placement of the stimulating tip along the incus. Improvement in coupling the transducer to the incus and stapes produced significant improvements in the transfer of vibratory stimuli to the ossicular chain.