Fully implantable Otologics MET Carina device for the treatment of sensorineural hearing loss. Preliminary surgical and clinical results.

Middle ear implants overcome some of the common problems of conventional hearing aid technology, such as feedback, signal distortion, ear canal occlusion and associated issues. The Otologics MET Carina, Boulder, CO, USA, is a fully implantable hearing prosthesis designed to address the amplification needs of adults (> 18 years of age), with moderate to severe sensorineural hearing loss and normal middle ears, providing a mechanical direct stimulation of middle ear ossicles. Recently, it has been successfully used also in patients with conductive hearing loss. In the present report, personal surgical and clinical experience with the fully implantable Carina is described in 5 adults with moderate to severe sensorineural hearing loss, operated upon between November 2007 and May 2008 in the ENT Unit, University of Pisa. Mean follow-up was 10.2 months of device use (range 7-13). Surgery was performed under general anaesthesia, in approximately 3 hours, with no surgical complications in any of the patients. In these 5 cases, no significant post-operative variation was observed in hearing thresholds, either for air or bone conduction, indicating absence of surgical damage to the cochlea. All patients showed improvements in hearing thresholds, in free field and in speech perception abilities, with the device functioning, moreover, they reported subjective benefits. With regard to post-operative adverse effects, no cases of extrusion of the device, device failure, loss of external communication or increased charging times were observed. Problems of feedback noise occurred, which were resolved with minor fitting adjustments in 4 cases, while a second operation was required to change the microphone position in the other patient. The present results, in agreement with those reported in the literature, confirm that the Otologics MET Carina is viable treatment for moderate to severe sensorineural hearing loss and, in selected cases, may represent an alternative to conventional hearing aids.