Middle ear implants for rehabilitation of sensorineural hearing loss: a systematic review of FDA approved devices

Hearing Outcome and Predictors after Implanting Bone Conduction or Middle Ear Implants in Ears with Refractory Otitis Media

Bone conduction implants (BCIs) and middle ear implants (MEIs) are promising options for individuals with persistent chronic inflammation of the middle or outer ear. However, the structure of the middle ear is often altered in patients who undergo mastoidectomy or posterior wall removal for refractory otitis media, leaving uncertainty regarding the efficacy of hearing devices. Only a few studies have examined auditory outcomes based on the etiology of hearing impairment. We investigated hearing outcomes, including speech audiometry, in patients who underwent implantation after surgery for refractory otitis media. Our findings indicated that patients who received BCIs or MEIs achieved favorable hearing outcomes. Furthermore, a correlation was observed between the preoperative bone-conduction threshold at 1 kHz in the better ear and the sound-field threshold at 1 kHz with BCIs, whereas no correlation was observed between the preoperative bone-conduction threshold and the sound-field threshold with MEIs. This study highlights the positive impact of BCIs and MEIs in patients who undergo implantation after surgery for refractory otitis media. Additionally, our study identified parameters that predict postoperative efficacy.

Results and Quality of Life after Implantation of Active Middle Ear Implants

The provision of implantable hearing aids represents an area with high development and innovation potential. On the one hand, this review article provides an overview of current indication criteria for the treatment with active middle ear implants. On the other hand, outcome parameters as well as functional results after implantation of active middle ear implants are demonstrated and discussed. The focus is mainly placed on audiological results as well as the subjective health status. "Patient Reported Outcome Measures" (PROMs) have become an integral part of the evaluation of hearing implant treatment. Due to low evidence level criteria, the study situation regarding audiological as well as subjective outcome parameters is not satisfactory. The lack of an international consensus on accepted outcome parameters makes a meta-analytical analysis of results immensely difficult. In the studies published to date, patients with sensorineural hearing loss and patients with conductive or mixed hearing loss offered better speech recognition after implantation of an active middle ear implant compared to conventional hearing aids. Current analyses show a significant improvement in general as well as hearing-specific quality of life after implantation of an active middle ear implant. To date, no validated, hearing-specific quality-of-life measurement instruments exist for assessing the success of fitting in children. Especially in children with complex malformations of the outer ear and the middle ear, excellent audiological results were shown. However, these results need to be substantiated by quality-of-life measurements in future.

New Considerations for a Totally Implantable Active Middle Ear Implant

Totally implantable active middle ear implants (AMEI) provide full-time hearing amplification to those with moderate to severe sensorineural hearing loss. While technology in conventional hearing aids (CHA) has advanced greatly, limitations remain for people with active lifestyles, limited vision or dexterity, and hearing aid fit issues. Furthermore, direct-drive properties of AMEI are thought to provide those with inefficient middle ear transfer functions a distinct advantage in delivering prescribed sound to the cochlea, ultimately improving speech understanding with less distortion. AMEI safety, stability, and efficacy outcomes are well documented and fitting strategies continue to improve. Recent studies show how simple aided speech testing can help predict whether a patient struggling with CHA may instead benefit from an AMEI. Totally implantable AMEI continue to be a viable option for patients who cannot or will not utilize traditional hearing aids.

Long-Term Safety and Quality of Life after Vibroplasty in Sensorineural Hearing Loss: Short/Long Incus Process Coupler

OBJECTIVE

The study shows the long-term effectiveness, safety, and quality of life after Vibrant Soundbridge (VSB) implantation in sensorineural hearing loss (SNHL) using the short process coupler (SP) or the long process coupler (LP).

METHODS

This retrospective study evaluated 77 VSB cases. Follow-up (F/U) time-dependent objective measurements (audiological outcomes), subjective data collection (quality-of-life questionnaire), and safety measures are presented.

RESULTS

Sixty-two ears were included in the analysis with up to 116 months of postsurgical F/U data (mean 32.15 ± 37.97 months LP and SP coupler). Fifty-three ears (13 bilateral cases) received the LP coupler and 9 subjects the SP coupler. The post-operative bone conduction thresholds remained stable and, in both groups, <10 dB. The benefit in word recognition scores measured at 65 dB SPL and 80 dB SPL showed no significant difference between the couplers (p = 0.559 and p = 0.088, respectively). The functional gain was not significantly different (p > 0.05) with a mean of 20.91 ± 9.77 and 17.19 ± 5.75 for LP and SP coupler, respectively. The utility score deciphered from the Assessment of Quality-of-life Questionnaire-8 dimensions revealed a mean score of 0.75 ± 0.16 which is not significantly different to the age- and sex-matched healthy control group with 0.81 ± 0.02 (p = 0.3547).

CONCLUSION

The Incus Vibroplasty utilizing both couplers is a safe and effective method to treat mild-to-severe SNHL. Both fixation methods of the floating mass transducer exhibit good clinical and audiological outcomes with high patient quality of life. The SP coupling method can be a good alternative when the long process is anatomically inaccessible, or the approach is limited due to anatomical reasons.

[Coupling of active middle ear implants-biomechanical aspects]

Active middle ear implants or implantable hearing aids are used to treat sensorineural or combined hearing loss. Their coupling to the middle ear structures has a large impact on the success of rehabilitation. Practical issues such as the coupling site, influence of middle ear status, and forward and backward excitation of the inner ear are discussed in the context of biomechanics. For this purpose, experimental studies, model simulations, and current literature data are evaluated. The explanations are intended to contribute to a better understanding of certain procedures in hearing rehabilitation with active implants.

Guidelines for Best Practice in the Audiological Management of Adults with Severe and Profound Hearing Loss

Individuals with severe to profound hearing loss are likely to present with complex listening needs that require evidence-based solutions. This document is intended to inform the practice of hearing care professionals who are involved in the audiological management of adults with a severe to profound degree of hearing loss and will highlight the special considerations and practices required to optimize outcomes for these individuals.

Factors associated with benefit of active middle ear implants compared to conventional hearing aids

OBJECTIVE

Identify factors associated with benefit of middle ear implants (MEIs) as compared to conventional hearing aids (HAs).

STUDY DESIGN

Independent review of audiological data from a multicenter prospective U.S. Food and Drug Administration (FDA) clinical trial. Preoperative and postoperative earphone, unaided/aided/implanted pure-tone thresholds, and word recognition scores were evaluated.

RESULTS

Ninety-one subjects were included in this study. Mean word recognition was better with MEIs than with HAs (81.8% ± 12.0% vs. 77.6% ± 14.6%, P = 0.035). Word recognition with MEIs showed a low positive correlation with word recognition measured with earphones (r = 0.25, P = 0.016) and a moderate positive correlation with aided word recognition (r = 0.42, P < 0.001). Earphone word recognition alone was not predictive of MEI benefit over HA benefit (r = 0.09, P = 0.41), unlike differences between scores with earphone and HAs (earphone-aided differences [EAD]) (r = 0.62, P < 0.011). As compared to those with -EADs, subjects with +EADs showed greater improvement in word recognition from unaided to implanted and from HAs to implanted (P < 0.0001). Using the 95% CI for word recognition scores, 16 subjects showed significantly higher scores with the MEI than with HAs. Of those, 14 had +EAD.

CONCLUSION

Word recognition benefit derived from conventional HAs and MEIs from this large, multi-center FDA trial provides further evidence of the importance of aided word recognition in clinical decision making, such as determining candidacy for and success with MEIs.

LEVEL OF EVIDENCE

2b. Laryngoscope, 128:2133-2138, 2018.

Implantable hearing devices

Combined hearing loss is an essential indication for implantable hearing systems. Depending on the bone conduction threshold, various options are available. Patients with mild sensorineural deafness usually benefit from transcutaneous bone conduction implants (BCI), while percutaneous BCI systems are recommended also for moderate hearing loss. For combined hearing losses with moderate and high-grade cochlear hearing loss, active middle ear implants are recommended. For patients with incompatibilities or middle ear surgery, implants are a valuable and proven addition to the therapeutic options.

Cost-Utility of Partially Implantable Active Middle Ear Implants for Sensorineural Hearing Loss: A Decision Analysis

BACKGROUND

Partially implantable active middle ear implants (aMEIs) offer a solution for individuals who have mild to severe sensorineural hearing loss and an outer ear medical condition that precludes the use of hearing aids. When otherwise left untreated, individuals report a lower quality of life, which may further decrease with increasing disability. In the lack of cost-effectiveness studies and long-term data, there is a need for decision modeling.

OBJECTIVE

To explore individual-level variance in resource utilization patterns following aMEI implantation.

METHODS

A Markov model was developed and analyzed as microsimulation to estimate the incremental cost utility ratio (ICUR) of partially implantable aMEIs compared with no (surgical) intervention in individuals with sensorineural hearing loss and an outer ear medical condition in Australia. Cost data were derived mostly from the Medicare Benefit Schedule and effectiveness data from published literature. A third-party payer perspective was adopted, and a 5% discount rate was applied over a 10-year time horizon.

RESULTS

Compared with baseline strategy, aMEIs yielded an incremental cost of Australian dollars (AUD) 13,339.18, incremental quality-adjusted life-year (QALY) of 1.35, and an ICUR of AUD 9,913.72/QALY. Of the respective number of simulated patients who visited each health state, 75.73% never had a minor adverse event, 99.82% did not experience device failure, and 97.75% did not cease to use their aMEIs. Probabilistic sensitivity analyses showed the ICUR to differ by only 0.95%.

CONCLUSIONS

In the Australian setting, partially implantable aMEIs offer a safe and cost-effective solution compared with no intervention and are also well accepted by users.

Evaluating speech perception of the MAXUM middle ear implant versus speech perception under inserts

OBJECTIVES/HYPOTHESIS

To evaluate the speech perception of the Ototronix MAXUM middle ear implant relative to the cochlear potential for speech perception of patients.

STUDY DESIGN

Clinical study chart review.

METHODS

We performed an evaluation of data from a prospective clinical study of 10 MAXUM patients. Primary outcome measures included comparison of word recognition (WR) scores with MAXUM (WR_MAXUM ) versus word recognition under inserts (WR_inserts ), and the functional gain improvement for pure-tone average (PTA) (0.5, 1, and 2 kHz) and high-frequency pure-tone average (2, 3, and 4 kHz).

RESULTS

Ten ears in 10 adult patients (six female; average age 68.7 years) were included. The average speech perception gap (difference between WR_inserts and WR_MAXUM ) with MAXUM was -9.2% (range, -26% to 4%). A negative number indicates that WR_MAXUM was higher than the WR_inserts . The average PTA with MAXUM was 23.1 dB (range, 18.7-30 dB), a 38.0-dB gain over the preoperative unaided condition (range, 20-53.3 dB). The average high-frequency pure-tone average with MAXUM was 34.4 dB (range, 26-43.3 dB), a 42.8-dB gain over the preoperative unaided condition (range, 32.3-58.7 dB).

CONCLUSIONS

These data demonstrate that a significant, very strong correlation was observed between WR_inserts and WR_MAXUM scores (r = 0.86, P = .001), and a patient's WR_inserts score may be used to reasonably predict the word recognition outcomes with MAXUM.

LEVEL OF EVIDENCE

4. Laryngoscope, 128:456-460, 2018.

THE EFFECT OF IMPLANTABLE TRANSDUCERS ON MIDDLE EAR TRANSFER FUNCTION — A COMPARATIVE NUMERICAL ANALYSIS

Several types of middle ear implants (MEIs) have been invented as an alternative to conventional hearing aids for the rehabilitation of sensorineural hearing loss. Temporal bone and clinical studies have shown that the implantation of MEIs’ transducers influences middle ear transfer function. But there is little comparative data available about these influences. We conducted comparative studies on the influences of three principal types of MEI transducers in respect to their attachment points on the ossicular chain. To aid the investigation, a human middle ear finite element model was constructed. The model was built based on a complete set of micro-computerized tomography section images of a human ear by reverse engineering technology. The validity of the developed model was verified by comparing the motions obtained by this model with published experimental measurements on human temporal bones. The results show that the eardrum driving transducer (EDT) and the floating mass transducer (FMT) decrease stapes displacement prominently at high frequencies. The greater these transducers’ mass, the smaller is the displacement of the stapes footplate. In contrast, the incus body driving transducer (IBDT) decreases stapes displacement severely at low frequencies, and its adverse effect on residual hearing increases with increasing stiffness of the IBDT’s driving rod.

Evaluation of Round Window Stimulation Performance in Otosclerosis Using Finite Element Modeling

Round window (RW) stimulation is a new type of middle ear implant's application for treating patients with middle ear disease, such as otosclerosis. However, clinical outcomes show a substantial degree of variability. One source of variability is the variation in the material properties of the ear components caused by the disease. To investigate the influence of the otosclerosis on the performance of the RW stimulation, a human ear finite element model including middle ear and cochlea was established based on a set of microcomputerized tomography section images of a human temporal bone. Three characteristic changes of the otosclerosis in the auditory system were simulated in the FE model: stapedial annular ligament stiffness enlargement, stapedial abnormal bone growth, and partial fixation of the malleus. The FE model was verified by comparing the model-predicted results with published experimental measurements. The equivalent sound pressure (ESP) of RW stimulation was calculated via comparing the differential intracochlear pressure produced by the RW stimulation and the normal eardrum sound stimulation. The results show that the increase of stapedial annular ligament and partial fixation of the malleus decreases RW stimulation's ESP prominently at lower frequencies. In contrast, the stapedial abnormal bone growth deteriorates RW stimulation's ESP severely at higher frequencies.

The ototronix MAXUM middle ear implant for severe high-frequency sensorineural hearing loss: Preliminary results

OBJECTIVES/HYPOTHESIS

To report the preliminary results of the Ototronix MAXUM middle ear implant for treatment of severe high-frequency sensorineural hearing loss.

STUDY DESIGN

Case series with chart review.

METHODS

Six consecutive ears with severe high-frequency sensorineural hearing loss (≥75 dB HL at 2, 3, and 4 kHz) and poor aided word recognition performance (≤60% single words) underwent implantation of the MAXUM system at a single, private otologic referral center. Primary outcome measures included frequency-specific functional gain and word recognition score improvement compared to optimally fitted hearing aids.

RESULTS

Six ears, in four adult patients (two female; median age 67.5 years) were included. The median unaided preoperative high-frequency pure-tone average (HFPTA) (2, 3, and 4 kHz) was 80.0 dB (range, 75.0-85.0 dB), and the median best-aided word recognition score was 48.0% (range, 24%-60%). The median HFPTA functional gain with the MAXUM system was 47.2 dB, a 25.0 dB improvement (range, 16.7-33.3 dB) (P = .03) over optimally fit hearing aids, and the median word recognition score with MAXUM was 81.5%, a 42.0% improvement (range, 20%-48%) (P = .03) with the MAXUM middle ear implant over optimally fitted hearing aids.

CONCLUSIONS

These preliminary data demonstrate that the MAXUM middle ear implant provides superior functional gain and word recognition scores in quiet for patients with severe high-frequency sensorineural hearing loss compared to optimally fitted hearing aids. Future studies with greater patient numbers and patient reported outcome measures are needed to confirm these promising but preliminary results.

LEVEL OF EVIDENCE

4 Laryngoscope, 126:2124-2127, 2016.

Developing an Ear Prosthesis Fabricated in Polyvinylidene Fluoride by a 3D Printer with Sensory Intrinsic Properties of Pressure and Temperature

An ear prosthesis was designed in 3D computer graphics software and fabricated using a 3D printing process of polyvinylidene fluoride (PVDF) for use as a hearing aid. In addition, the prosthesis response to pressure and temperature was observed. Pyroelectric and piezoelectric properties of this ear prosthesis were investigated using an astable multivibrator circuit, as changes in PVDF permittivity were observed according to variations of pressure and temperature. The results show that this prosthesis is reliable for use under different conditions of pressure (0 Pa to 16,350 Pa) and temperature (2 °C to 90 °C). The experimental results show an almost linear and inversely proportional behavior between the stimuli of pressure and temperature with the frequency response. This 3D-printed ear prosthesis is a promising tool and has a great potentiality in the biomedical engineering field because of its ability to generate an electrical potential proportional to pressure and temperature, and it is the first time that such a device has been processed by the additive manufacturing process (3D printing). More work needs to be carried out to improve the performance, such as electrical stimulation of the nervous system, thereby extending the purpose of a prosthesis to the area of sensory perception.

[Differential indication of active middle ear implants]

INTRODUCTION

Hearing aids (HA) provide adequate support for many patients with hearing loss, but not all. Around one third of 10.000 patients provided with hearing aids in the Abbreviated Profile of Hearing Aid Benefit felt no actual benefit when using the hearing aid, although they demonstrated the necessary hearing improvement on speech audiometry. Epidemiological data show bad compliance, especially in older people. Only one in three hearing aid owners wears their device regularly. For this subpopulation of patients active middle ear implants (AMEIs) have been used since 1998. In the present review, the current indications for AMEIs are presented.

MATERIAL AND METHODS

A selective literature search in PubMed, as well as a guideline search at the Arbeitsgemeinschaft der Wissenschaftlichen Fachgesellschaften e. V. (German Association of Scientific Societies), was carried out.

RESULTS

The present review shows that when there is an adequate indication the hearing capacity of patients can be thoroughly rehabilitated and thus their quality of life improved with the help of AMEIs. Although most commercially available systems have a satisfactory risk profile, increased extrusion rates, malfunctioning and facial paresis have been reported in older implant series. The advantages of AMEIs include increased hearing gain, reduced feedback, increased hearing quality, increased speech discrimination in the presence of background noise, and an absence of occlusion.

CONCLUSIONS

The audiological indication for AMEIs in primary care is usually controversial, since the functional hearing gain and increase in speech discrimination may be small compared with modern conventional hearing aids. AMEIs thus play a main role in the secondary care of patients who do not have sufficient benefit or who have side effects after having a conventional hearing aid fitted.