Rehabilitation of high-frequency hearing loss with the RetroX auditory implant

The RetroX is a new semi-implantable hearing aid which does not occlude the external ear canal. It consists of an electronic unit that plugs into a titanium tube which is implanted under the pinna so as to connect the retroauricular sulcus with the inside lumen of the external ear canal. Implantation requires minor surgery which can be performed under local anesthesia. Moreover, a pre-implant simulator exists and allows patients to try the device before deciding on definite implantation. The RetroX auditory implant is indicated in case of high-frequency sensorineural hearing loss with a steep slope (ski-slope audiogram). We implanted 25 adults suffering from such a hearing loss, and we report their hearing measured after 2.5 to 15 months of use. Four patients developed a persistent granulomatous reaction which disappeared after explantation. Two patients complained of acoustic feedback and needed supplementary fitting. Twenty three of our 25 subjects are satisfied or even extremely satisfied with the hearing improvement provided by the RetroX; they wear the implant daily, from morning until evening. Audiometrically, we observed a statistically significant improvement of the pure-tone thresholds at 1, 2, 4 and 8 kHz. In quiet, the speech reception thresholds decreased by 10 dB SPL and in noise, speech intelligibility increased by 15% for signal-to-noise ratios between -5 dB and +5 dB. Up till now, our patients were implanted monaurally because of financial considerations and our initial inexperience with this new implant. The overall results, however, are promising and nowadays, we advise bilateral implantation for patients who tolerate the first implant. By doing so, we hope to improve hearing in noise and spatial sound perception.