Objectives: 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.
Materials and methods: 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.
Results: 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.
Conclusion: 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.