The RetroX auditory implant for high-frequency hearing loss

Objective: The objective of this study was to analyze the subjective satisfaction and measure the hearing gain provided by the RetroX (Auric GmbH, Rheine, Germany), an auditory implant of the external ear. Study Design: We conducted a retrospective case review. Setting: We conducted this study at a tertiary referral center at a university hospital. Subjects: We studied 10 adults with high-frequency sensorineural hearing loss (ski-slope audiogram). Intervention: The RetroX consists of an electronic unit sited in the postaural sulcus connected to a titanium tube implanted under the auricle between the sulcus and the entrance of the external auditory canal. Implanting requires only minor surgery under local anesthesia. Main Outcome Measures: Main outcome measures were a satisfaction questionnaire, pure-tone audiometry in quiet, speech audiometry in quiet, speech audiometry in noise, and azimuth audiometry (hearing threshold in function of sound source location within the horizontal plane at ear level). Results: Subjectively, all 10 patients are satisfied or even extremely satisfied with the hearing improvement provided by the RetroX. They wear the implant daily, from morning to evening. We observe a statistically significant improvement of pure-tone thresholds at 1, 2, and 4 kHz. In quiet, the speech reception threshold improves by 9 dB. Speech audiometry in noise shows that intelligibility improves by 26% for a signal-to-noise ratio of -5 dB, by 18% for a signal-to-noise ratio of 0 dB, and by 13% for a signal-to-noise ratio of +5 dB. Localization audiometry indicates that the skull masks sound contralateral to the implanted ear. Of the 10 patients, one had acoustic feedback and one presented with a granulomatous reaction to the foreign body that necessitated removing the implant. Conclusion: The RetroX auditory implant is a semi-implantable hearing aid without occlusion of the external auditory canal. It provides a new therapeutic alternative for managing high-frequency hearing loss.