A Retrospective Multicentre Cohort Review of Patient Characteristics and Surgical Aspects versus the Long-Term Outcomes for Recipients of a Fully Implantable Active Middle Ear Implant

Abstract

Objective: To summarise treatment outcomes compared to surgical and patient variables for a multicentre recipient cohort using a fully implantable active middle ear implant for hearing impairment. To describe the authors' preferred surgical technique to determine microphone placement. Study Design: Multicentre retrospective, observational survey. Setting: Five tertiary referral centres. Patients: Carina recipients (66 ears, 62 subjects) using the current Cochlear® Carina® System or the legacy device, the Otologics® Fully Implantable Middle Ear, with a T2 transducer. Methods: Patient file review and routine clinical review. Patient outcomes assessed were satisfaction, daily use and feedback reports at the first fitting and ≥12 months after implantation. Descriptive and statistical analysis of correlations of variables and their influence on outcomes was performed. Independently reported preferred methods for microphone placement are collectively summarised. Results: The average implant experience was 3.5 years. Satisfaction increased significantly over time (p < 0.05). No correlation with covariates examined was observed. Feedback significantly decreased over time, showing a significant correlation with microphone location, primary motivation, gender, age at implantation, and contralateral hearing aid use (p < 0.05). Patient satisfaction was inversely correlated with reports of system feedback (p < 0.05). The implantable microphone was most commonly on the posterior inferior mastoid line, in 42/66 (65%) cases, correlating with less likelihood for feedback and consistent with author surgical preference. Conclusion: Carina recipients in this study present as satisfied consistent daily users with very few reports of persistent feedback. As microphone location is an influencing factor, a careful surgical consideration of microphone placement is required. The authors prefer a posterior inferior mastoid line position whenever possible.

Stability of the standard incus coupling of the Carina middle ear actuator after 1.5T MRI

“…Experiments were performed by implanting eleven temporal bones with the electromagnetic T2 actuator coupled to the short process of the incus. This surgical position was preferred as it resembles the majority of reported surgical approaches in Carina 1 patients [1,[3][4][5]. Each temporal bone was entered and exited into the MRI suite in a clinically relevant way to simulate how a patient would enter the MRI suite during an examination.…”

“…Depending on a patient's specific needs, the actuator can be coupled to the ossicles, the oval window or the round window to compensate the hearing loss [2]. Coupling the actuator to the body of the incus has been used most in practice as it does not require mounting an additional prosthesis to the actuator tip [1,[3][4][5].…”

“…The loading of the actuator will be tested before and after exposure to a 1.5 T field to assess the coupling efficiency. An actuator will be rigorously coupled to the body of the incus in order to represent the most commonly used configuration [1,[3][4][5]. The coupling stability is observed in the case when a patient traverses the fringe field of a 1.5 T MRI scanner in a clinically relevant manner.…”

Air- and Bone-Conducted Sources of Feedback With an Active Middle Ear Implant

“…Few studies of active middle ear implants contain an in-depth discussion regarding generation of feedback. While excessive acoustic feedback with traditional hearing aids is a problem often cited by patients prior to implantation, only a small number of investigations discuss device feedback as a post-surgical complication for AMEI (Jenkins et al 2007a;Bruschini et al 2010Bruschini et al , 2016Lefebvre et al 2016). Suboptimal device compliance due to feedback has been reported (Jenkins et al 2007a;Lefebvre et al 2016), with report of one severe case necessitating return to the operating room (Bruschini et al 2010).…”

“…Like conventional hearing aids, AMEI are susceptible to leakage of stimulus back to the microphone, resulting in feedback (Pulcherio et al 2014). Several studies have discussed feedback as a complication of this type of device for some patients (Jenkins et al 2007a;Bruschini et al 2009Bruschini et al , 2010Bruschini et al , 2016Zenner & Rodriguez Jorge 2010;Kam et al 2012;Pulcherio et al 2014;Lefebvre et al 2016), though the pathway for feedback is not completely understood. While reverse propagation of an acoustic signal through the ossicular chain and tympanic membrane can create an air-conducted source of feedback, the implanted AMEI microphone position near the mastoid cortex suggests that the bone conduction pathway might also contribute to the generation of audible feedback.…”