Treatment of the atretic ear with round window vibrant soundbridge implantation in infants and children: electrocochleography and audiologic outcomes

Influence of skin flap thickness on the transmission characteristics of middle ear implant audio processors

OBJECTIVE

To measure signal transmission characteristics for audio processors of an active middle ear implant as a function of skin flap thickness, i.e., distance between audio processor and the implant's receiver coil.

METHODS

Output sound pressure levels for 90 dB input sound pressure level (OSPL90), reference test gains as function of frequency for an input sound pressure level of 60 dB (RTG60), and reference test gains (RTG - high frequency averages) were recorded in a hearing aid test box for Samba 2 Hi, Samba 2 Lo, and AP404 audio processors (MED-EL, Innsbruck, Austria) positioned on an implant-in-the-box and distances of 0-10 mm between audio processors and the receiver coil.

RESULTS

For all audio processors, the OSPL90 and RTG decreased linearly with increasing distance. The effect was dependent on audio processor type and the strongest reduction was observed for Samba 2 Lo. Between distances of 0 mm and 10 mm, the relative change of RTG was - 9,9 dB for Samba 2 Hi, -10,3 dB for AP404, and -27,7 dB for Samba 2 Lo.

CONCLUSIONS

Skin thickness is a clinically significant factor which has to be considered in VSB treatment. In combination with insufficient transducer coupling or in patients with hearing thresholds close to the indication criteria limit, a thick skin flap could lead to loss of transmitted energy resulting in insufficient audiological outcome with the active middle ear implant.

Efficacy of vibrant sound bridge in congenital aural atresia: an updated systematic review

PURPOSE

The indications of Vibrant Soundbridge (VSB) have been expanded to include patients with conductive and mixed hearing loss due to congenital aural atresia (CAA). However, the current evidence supporting the auditory outcomes of VSB is based mainly on case reports and retrospective chart reviews. Therefore, the present systematic review aims to summarize and critically appraise the current evidence regarding the safety and effectiveness of VSB in children and adult patients with CAA.

METHODS

A systematic literature search retrieved studies that evaluated the outcomes of unilateral or bilateral implantation of VSB in patients with CAA. The bibliographic search was conducted in PubMed, Scopus, EBSCO, and Cochrane Central Register of Controlled Trials (CENTRAL) databases from January 2000 to December 2022.

RESULTS

Twenty-seven studies were included in the present systematic review. Overall, the speech perception after VSB was good, with a mean word recognition score (WRS) score ranging from 60 to 96.7%. The mean postoperative speech recognition threshold (SRT) after implantation ranged from 20.8 to 50 dB. The effective gain was reported in 15 studies, ranging from 31.3 to 45.5 dB. In terms of user satisfaction with VSB, the included studies showed significant improvements in the patient-reported outcomes, such as the Speech Spatial and Qualities of Hearing scale and Glasgow Hearing Aid Benefit Profile. The VSB implantation was generally safe with low incidence of postoperative complications.

CONCLUSION

VSB provides significant benefits to individuals with hearing loss owing to CAA, with very good subjective outcomes and a low risk of complications.

Implantable hearing devices in clinical practice. Systematic review and consensus statements

Objective

Implantable hearing devices represent a modern and innovative solution for hearing restoration. Over the years, these high-tech devices have increasingly evolved but their use in clinical practice is not universally agreed in the scientific literature. Congresses, meetings, conferences, and consensus statements to achieve international agreement have been made. This work follows this line and aims to answer unsolved questions regarding examinations, selection criteria and surgery for implantable hearing devices.

Materials and methods

A Consensus Working Group was established by the Italian Society of Otorhinolaryngology. A method group performed a systematic review for each single question to identify the current best evidence on the topic and to guide a multidisciplinary panel in developing the statements.

Results

Twenty-nine consensus statements were approved by the Italian Society of Otorhinolaryngology. These were associated with 4 key area subtopics regarding pre-operative tests, otological, audiological and surgical indications.

Conclusions

This consensus can be considered a further step forward to establish realistic guidelines on the debated topic of implantable hearing devices.

The influence of intraoperative auditory brainstem responses on vibroplasty coupling-quality and analysis of the impact of different fixation steps on the coupling

PURPOSE

The Vibrant Soundbridge (VSB) is an established active-middle-ear-implant for patients with moderate-to-profound hearing-loss. This surgery is referred to as "Vibroplasty". Sufficient transfer of the VSB's floating-mass-transducers (FMT) energy to the inner ear is a crucial factor influencing the coupling-quality (CQ). However, assessing CQ is hamper by two issues: the method of CQ-assessment itself and the method of FMT-fixation during Vibroplasty.

METHODS

This prospective study explored the influence of intraoperative auditory-brainstem-response (+ ABR) measurements and various fixation methods on postoperative CQ after Vibroplasty as compared to matched-patients after Vibroplasty without intraoperative ABR (-ABR). Propensity-score-matching was performed based on preoperative bone-conduction-pure-tone-average-3 (BC-PTA3) at 1-, 2- and 4 kHz. Primary outcome parameters were postoperative CQ-PTA3, intraoperative ABR threshold for various fixation methods and postoperative BC-PTA3.

RESULTS

A total of 28 patients were included, of which 14 were + ABR. Preoperative BC-PTA3, sex, age, and number of previous surgeries did not differ significantly between groups (all p > 0.301). Mean postoperative CQ-PTA3 was significantly better for + ABR (1.8 vs. 12.3 dB-HL; p = 0.006). Mean intraoperative ABR threshold was superior for cartilage-counter-bearing and cartilage-housing compared to additional fixation with injectable-platelet-rich- fibrin (53 vs. 56 & 57 dB-HL, respectively; p = 0.04; η2 = 0.33). Mean postoperative BC-PTA3 did not significantly differ between patients (41.4 vs. 41.8 dB-HL; p = 0.77). A total of 7% of the patients required intraoperative readjustment of the FMT based on unsatisfactory intraoperative ABR threshold.

CONCLUSION

Intraoperative ABR measurement resulted in significantly better postoperative CQ. Cartilage-counter-bearing and cartilage-housing were observed to have superior CQ. A total of 7% of the patients could be spared revision-Vibroplasty due to intraoperative ABR measurement.

Long-term results and quality of life after vibrant soundbridge implantation (VSBs) in children and adults with aural atresia

PURPOSE

The aim of this study was to evaluate the long-term effectiveness and acceptance of the active middle ear implant system Vibrant Soundbridge (VSB®, MED-EL, Austria) in patients with aural atresia or aplasia (children and adults).

METHODS

Data from 51 patients (mean age 13.9 ± 11.3 years), 42 (79.2%) children and adolescents, and 11 (20.8%) adults) who received a VSB implant between 2009 and 2019 at the Department of Otolaryngology at LMU Clinic Großhadern, Munich were included in the study. Pure-tone audiometry, speech recognition in a quiet environment and in a noisy environment were performed preoperatively, during the first fitting of the audio processor, after 1-3 years, after 3-5 years, and after 5 years (if possible). The follow-up period ranged from 11 to 157 months with a mean of 58.6 months (4.8 years). Furthermore, the benefit of the VSB was evaluated by self-assessment questionnaires (Speech, Spatial, and Qualities of Hearing Scale, respectively, for parents).

RESULTS

Significant improvements were observed in hearing and speech comprehension immediately after the initial fitting of the VSB system (mean hearing gain 38.4 ± 9.4 dB HL) and at follow-up intervals (1-3, 3-5 and after 5 years) for children and adults (p < 0.01). The values remained stable over the long-term, indicating a sustained functional gain from the VSB (mean hearing gain 38.9 ± 9.2 dB HL). The results of the self-assessments affirm the positive influence on hearing and speech comprehension with the VSB. With the VSB, there was an improvement of 41.3 ± 13.7% in the Freiburg monosyllable test.

CONCLUSION

These results (a stable hearing gain over the long term, a good tolerance of the implant and an improvement in quality of life) affirm the recommendation for using the active middle ear implant VSB as early as permitted for aural atresia and aplasia patients. This study represents the audiometric results with the (to date) largest collective of aural atresia patients and with a long follow-up period.

Comparison of Transcutaneous and Percutaneous Implantable Hearing Devices for the Management of Congenital Aural Atresia: A Systematic Review and Meta-Analysis

OBJECTIVE

To compare audiometric outcomes, complications, and revisions required for percutaneous (pBCD) versus transcutaneous (tBCD) implantable bone-conduction devices for the treatment of hearing loss associated with congenital aural atresia (CAA).Databases Reviewed.PubMed, Scopus, CINAHL.

METHODS

A systematic review was performed searching for English language articles from inception to December 14, 2022. Studies reporting audiometric outcomes or complications for either pBCDs or tBCDs for the treatment of CAA were selected for inclusion. A meta-analysis of single means and meta-analysis of proportions with comparison (Δ) of weighted proportions was conducted.

RESULTS

A total of 56 articles with 756 patients were selected for inclusion. One hundred ninety patients were implanted with pBCDs, whereas the remaining 566 were implanted with tBCDs. Mean pure-tone audiometry improvement in the pBCD group (39.1 ± 1.1 dB) was significantly higher than in the tBCD group (34.6 ± 1.6 dB; Δ4.5 dB; 95% confidence interval, 4.2-4.7 dB; p < 0.0001). The average improvement in speech reception threshold was 38.6 ± 2.5 dB in the percutaneous group as compared with 32.7 ± 1.6 dB in the transcutaneous group (Δ5.9 dB [5.3-6.5 dB], p < 0.0001). Overall complication rates for patients implanted with pBCDs and tBCDs were 29.0% (15.7-44.4%) and 9.4% (6.5%-13.0%), respectively (Δ19.6% [12.0-27.7%], p < 0.0001).

CONCLUSIONS

Patients with CAA implanted with pBCDs had significantly better audiometric outcomes than those implanted with tBCDs. However, complication rates were significantly higher among the pBCD group.

Comparison of auditory brainstem response and electrocochleography to assess the coupling efficiency of active middle ear implants

Aim

This study aimed to compare the effectiveness of auditory brainstem response (ABR) and extracochlear electrocochleography (ECochG) in objectively evaluating the coupling efficiency of floating mass transducer (FMT) placement during active middle ear implant (AMEI) surgery.

Methods

We enrolled 15 patients (mean age 58.5 ± 19.4 years) with mixed hearing loss who underwent AMEI implantation (seven ossicular chain and eight round window couplings). Before the surgical procedure, an audiogram was performed. We utilized a clinical measurement system to stimulate and record intraoperative ABR and ECochG recordings. The coupling efficiency of the VSB was evaluated through ECochG and ABR threshold measurements. Postoperatively, we conducted an audiogram and a vibrogram.

Results

In all 15 patients, ABR threshold testing successfully determined intraoperative coupling efficiency, while ECochG was successful in only eight patients. In our cohort, ABR measurements were more practical, consistent, and robust than ECochG measurements. Coupling efficiency, calculated as the difference between vibrogram thresholds and postoperative bone conduction thresholds, was found to be more accurately predicted by ABR measurements (p = 0.016, R2 = 0.37) than ECochG measurements (p = 0.761, R2 = 0.02). We also found a non-significant trend toward better results with ossicular chain coupling compared to round window coupling.

Conclusion

Our findings suggest that ABR measurements are more practical, robust, and consistent than ECochG measurements for determining coupling efficiency during FMT placement surgery. The use of ABR measurements can help to identify the optimal FMT placement, especially with round window coupling. Finally, we offer normative data for both techniques, which can aid other clinical centers in using intraoperative monitoring for AMEI placement.

Round-Window Vibroplasty: Systematic Review and Meta-Analysis of Audiological Effectiveness With Different Round-Window Coupling Techniques

OBJECTIVE

Active middle ear implants can be directly coupled to the round-window (RW) membrane via RW Vibroplasty. The objectives of this systematic review were to summarize data on different RW coupling techniques and to investigate their effect on audiological and safety outcomes using meta-analyses.

DATABASES REVIEWED

PubMed (MEDLINE), Cochrane Library, and Embase (DIMDI).

METHODS

All publications reporting on audiological outcomes in human patients after RW Vibroplasty were included. Two independent reviewers carried out screening and data extraction. Meta-analyses and meta-regression were used to evaluate the potential effects of surgical and demographic parameters on primary audiological outcomes. Adverse events were extracted and tabulated for qualitative analysis.

RESULTS

Fourteen different combinations of surgical coupling parameters were identified in 61 included publications. Overall, data from 23 publications could be used for meta-analyses. Significantly better aided sound-field thresholds were reported for RW Vibroplasty performed without a dedicated coupler and using fascia as interponate, compared with RW Vibroplasty with an RW coupler or without an interponate. These effects were not found in other outcomes (i.e., functional gain, word recognition score). Reporting of adverse events was relatively heterogeneous, with 32 explicit mentions of revision surgery after the loss of coupling efficacy.

CONCLUSION

There are numerous publications investigating the effectiveness of coupling active middle ear implants to the RW membrane. However, studies are typically undersampled and of low evidence level. Using meta-analyses, weighted means, and qualitative analyses enabled a summary of the existing literature on audiological and safety outcomes after RW Vibroplasty. Individual selection of the most appropriate coupling modality with standardized intraoperative measurement and careful patient follow-up may be considered key factors for achieving effective RW coupling.

Comparison of Outcomes of Surgery Versus Implantable Device for the Treatment of Hearing Loss Associated With Congenital Aural Atresia: A Systematic Review and Meta-Analysis

OBJECTIVE

To compare audiometric outcomes, complications, and revisions required for implantable bone-conduction devices (BCDs) versus atresia surgery for the treatment of hearing loss associated with congenital aural atresia.

DATABASES REVIEWED

PubMed, Scopus, CINAHL.

METHODS

Databases were searched for English articles from inception to July 1, 2022, for studies reporting audiometric outcomes or complications for either BCDs or atresia surgery for the treatment of congenital aural atresia. Main outcome measures included pure-tone audiometry, air-bone gap, speech reception threshold, associated complications, and rates of revision for each treatment option.

RESULTS

We identified 973 abstracts, of which 89 were selected for data extraction and analysis. A total of 2,611 patients were included, 1,901 in the atresia surgery group and 710 in the BCDs group. A meta-analysis of single means was conducted for age and audiometric outcomes, and a meta-analysis of proportions was conducted for complications and revisions. The average short-term improvement in pure-tone audiometry for the BCDs group was 34.4 ± 1.6 dB compared with 22.4 ± 1.5 dB for the atresia surgery group, representing a significant difference (12.0 dB; 95% confidence interval, 11.9-12.2; p < 0.0001). A smaller proportion of complications were reported in the devices group (16.9%) compared with the atresia surgery group (45.7%). In addition, a smaller proportion of cases in the devices group required some degree of revision (17.8%) compared with the atresia surgery group (23.0%).

CONCLUSIONS

This study demonstrates that implantable BCDs have significantly better audiometric outcomes as well as a lower rate of complications and revisions required compared with atresia surgery.

Round window stimulation with an interface coupler demonstrates proof of concept

HYPOTHESIS

To mechanically stimulate the round window (RW) membrane, an actuator with an interface coupler (IC) has the potential to improve sound transmission to the cochlea as compared to the most used RW stimulation device implanted today. If a proof-of-concept IC prototype shows promise as compared the most common method for RW stimulation, there is potential that future design development of an IC will be worthwhile.

BACKGROUND

A variety of hearing pathologies resulting in mixed and conductive hearing loss can be addressed by mechanically stimulating the RW to transmit sound to the cochlea. The most common method for RW stimulation is with the floating mass transducer (FMT, Med-El). However, the FMT suffers poor sound transmission and unreliable device positioning. The dynamic range and bandwidth of the FMT as a RW stimulator is limited because the entire FMT needs freedom to vibrate. Thus the FMT has difficulty overcoming its own inertia and it cannot be stabilized in a manner that may limit its motion. Here we test an idea of using a generic actuator that vibrates on one side while stationary and held stable on the other (unlike the FMT), and coupling the actuator vibration to the RW membrane with a proof-of-concept IC designed to safely transmit sound to the cochlea. We determine if this proof-of-concept IC can perform as well or better than the FMT in one specimen. If so, further developments of the IC would be worthwhile.

METHODS

RW sound transmission comparison was made between an ideally implanted FMT and a proof-of-concept IC prototype driven by a piezoelectric stack actuator with vibrating tip in a fresh human temporal bone. Velocities of stapes, FMT, and IC actuator were measured with laser Doppler vibrometry to determine bandwidth, linearity, and dynamic range of cochlear sound transmission.

RESULTS

Stimulation with proof-of-concept prototype of the IC provided increased sound transmission, more linear output for larger dynamic range, and wider frequency range as compared to the FMT. This experiment demonstrates the potential of the IC concept to improve performance, and that it merits further development. However, it was challenging to stabilize the coupling between an external actuator and the proof-of-concept IC prototype. Thus, although we were successful in showing that this IC concept has promise, major design improvements and developments are required in the future.

CONCLUSIONS

We demonstrated that the proof-of-concept IC prototype driven with a tip connected to a piezoelectric stack actuator can stimulate the RW membrane with improved acoustic performance as compared to the FMT in one specimen. This study demonstrated proof of concept: that the idea of an IC for sound transmission to the cochlea through the RW has potential, and that it would be worthwhile to pursue the IC idea with further developments. This idea has the potential to provide robust sound transmission to the cochlea via the RW while preventing possible trauma to the cochlea. We also learned that critical design improvements are necessary because coupling the generic external actuator to the IC was challenging. A possible future IC design is to integrate a piezoelectric actuator permanently to the IC, allowing only the soft balloon membrane of the IC to vibrate the RW while the rest of the exterior housing of the combined IC (with actuator) would not vibrate and would be stabilized in a fixed manner.

Clinical feasibility of a novel test setup for objective measurements using the VIBRANT SOUNDBRIDGE

Objectives

The VIBRANT SOUNDBRIDGE is a widely used active middle ear implant to treat hearing loss. The floating mass transducer is surgically coupled to the ossicles, the round or oval window. A reliable method to monitor the coupling efficiency intraoperatively is highly desired. Research groups have developed several methods, but limitations remain. This study aims to evaluate the clinical feasibility of a new research setup for auditory brainstem response measurement to evaluate the coupling efficiency.

Method

In 14 subjects, the new tool was used to record VSB-evoked ABR thresholds during surgery. The intra-op ABR thresholds were compared to pre-op bone conduction (BC) thresholds and post-op vibrogram thresholds to evaluate the feasibility of the method as a tool to monitor coupling efficiency.

Results

The mean pre-op BC threshold average at 1, 2, and 4 kHz (PTA3) was 47 dB HL, the mean intra-op ABR threshold was 54 dB nHL, and the mean post-op vibrogram PTA3 was 60 dB HLeq. ABR was measurable in all subjects using the new tool. Correlation between pre-op BC thresholds and intra-op ABR thresholds was statistically significant; however, one outlier was present.

Conclusion

Intra-op hearing threshold detection through ABR and direct stimulation of the VSB implant was reliable using this new tool. Despite some individual variability, first results correlate well with pre-op BC and post-op vibrogram thresholds.

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.

Active Middle Ear Implant Evoked Auditory Brainstem Response Intensity-Latency Characteristics

Objective

To analyze intensity-latency functions of intraoperative auditory evoked brainstem responses (ABRs) to stimulation by the Vibrant Soundbridge (VSB) active middle ear implant with respect to coupling efficiency, VSB evoked ABR thresholds, and coupling modality [oval window (OW) placement vs. Incus placement and vs. round window (RW) placement].

Study Design

Exploratory study.

Setting

Bi-centric study at tertiary referral centers.

Patients

Twenty-four patients (10 female, 14 male, mean age: 58 years) who received a VSB.

Outcome Measures

Wave-V intensity-latency functions of intraoperative VSB evoked ABRs using a modified audio processor programmed to preoperative bone conduction thresholds for stimulation. Threshold level correction to coupling efficiency and ABR thresholds. Individual plots and exponential function fits.

Results

After ABR threshold level correction, the latency functions could be aligned. A large variance of latencies was observed at individual threshold level. Wave-V latency was longest in the Incus placement subgroup (9.73 ms, SD: 1.04) as compared to OW placement subgroup (9.47 ms, SD: 1.05), with the shortest latency in the RW placement subgroup (8.99 ms, SD: 0.68). For increasing stimulation levels, the variance decreased with intensity-latency function slopes converging toward a steady-state (saturation) latency caused by saturation of audio processor (stimulation) gain. Latency saturation was reached at a stimulation level of 50 dB nHL for the OW placement subgroup, 35 dB nHL for the Incus placement subgroup, and 30 dB nHL for the RW placement subgroup. The latency and saturation results indicated decreased dynamic range for RW placement, i.e., reverse stimulation.

Conclusions

VSB evoked ABR wave-V intensity-latency function slopes were similar to acoustic stimulation at high stimulation levels with a shift toward longer latencies caused by audio processor signal delay. Saturation of latencies occurred for higher stimulation levels due to saturation of audio processor gain. Thus, the analysis of VSB evoked intensity-latency functions appears to allow for the objective assessment of a patient's individual dynamic range. This can further improve diagnostics as well as intraoperative and postoperative quality control.

Analysis of design parameters of round-window stimulating type electromagnetic transducer by a nonlinear lumped parameter model of implanted human ear

Round-window stimulating transducer is a new solution to treat mixed hearing loss. To uncover the factors affecting the round-window stimulation's performance, we investigated the influence of four main design parameters of round-window stimulating type electromagnetic transducer. Firstly, we constructed a human ear nonlinear lumped parameter model and confirmed its validity by comparing the stapes responses predicted by the model with the experimental data. Following this, an electromagnetic transducer's mechanical model, which simulates the floating mass transducer, was built and coupled to the human ear model; thereby, we established a nonlinear lumped parameter model of implanted human ear under round-window stimulation and verified its reliability. Finally, based on this model, the influences of the four main design parameters, i.e., the excitation voltage, the electromechanical coupling coefficient, the support stiffness, and the preload force, were analyzed. The results show that the change of excitation voltage does not alter the system's natural frequency. Chaotic motion occurs when the electromechanical coupling coefficient is small. Meanwhile, the stapes displacement appears to increase firstly and then decrease with the increase of the electromechanical coupling coefficient. The increase of the support stiffness enlarges the resonance frequency of the stapes displacement and reduces the stapes displacement near the resonance frequency, deteriorating the transducer's hearing compensation at low frequency. The preload force can improve the transducer's hearing compensation performance in mid-high frequency region.

[Hearing rehabilitation with the Vibrant Soundbridge in patients with congenital middle ear malformation]

BACKGROUND

Congenital aural atresia, which is usually unilateral, causes hearing loss and aesthetic impairment. Besides tympanoplasty with/without canalplasty and bone conduction devices, active middle ear implants are also available for functional rehabilitation.

OBJECTIVE

This article aims to present a contemporary review on the treatment possibilities for middle ear malformations, with a focus on audiological rehabilitation with the Vibrant Soundbridge.

MATERIALS AND METHODS

A selective literature search for treatment possibilities was performed in PubMed up to October 2020, and personal clinical experiences are reported.

RESULTS

The Vibrant Soundbridge, which is approved for children ≥ 5 years, is suitable for treatment of middle ear malformations with a Jahrsdoerfer score ≥ 5. Although implantation of a Vibrant Soundbridge is surgically more demanding than implantation of a bone conduction device, the method is safe, delivers good auditory results (superior to bone conduction devices in terms of speech understanding and spatial hearing), does not involve intensive postsurgical care, and rarely requires revision surgery. The Vibrant Soundbridge can be coupled to (remnants of) the ossicular chain or the round window.

CONCLUSION

The Vibrant Soundbridge is an appropriate treatment method in patients with middle ear malformations who have suitable anatomical preconditions.

Intraoperative quantification of floating mass transducer coupling quality in active middle ear implants: a multicenter study

Purpose

Evaluating the effectiveness of intraoperative auditory brainstem responses (ABRs) to stimulation by the Vibrant Soundbridge (VSB) active middle ear implant for quantifying the implant’s floating mass transducer (FMT) coupling quality.

Methods

In a diagnostic multicentric study, patients (> 18 years) who received a VSB with different coupling modalities were included. Pre- and postoperative bone conduction thresholds, intraoperative VSB-evoked ABR thresholds (VSB-ABR) using a modified audio processor programmed to preoperative bone conduction thresholds, postoperative vibrogram thresholds, and postoperative VSB-ABR thresholds were measured. Coupling quality was calculated from the difference between the pure tone average at 1000, 2000, and 4000 Hz (3PTA) vibrogram and postoperative 3PTA bone conduction thresholds.

Results

Twenty-three patients (13 males, 10 females, mean age 56.6 (± 12.5) years) were included in the study. Intraoperative VSB-ABR response thresholds could be obtained in all except one patient where the threshold was > 30 dB nHL. Postoperatively, an insufficient coupling of 36.7 dB was confirmed in this patient. In a Bland–Altman analysis of the intraoperative VSB-ABRs and coupling quality, the limits of agreement exceeded ± 10 dB, i.e., the maximum allowed difference considered as not clinically important but the variation was within the general precision of auditory brainstem responses to predict behavioral thresholds. Five outliers were identified. In two patients, the postoperative VSB-ABR thresholds were in agreement with the coupling quality, indicating a change of coupling before the postoperative testing.

Conclusion

The response thresholds recorded in this set-up have the potential to predict the VSB coupling quality and optimize postoperative audiological results.

A Transcutaneous Active Middle Ear Implant (AMEI) in Children and Adolescents: Long-term, Multicenter Results

OBJECTIVE

Evaluation of the long-term safety and performance of an active middle ear implant (AMEI) in the treatment of hearing loss in children and adolescents with a primary focus on improvement in speech discrimination.

STUDY DESIGN

Prospective, multicentric, single-subject repeated-measures design in which each subject serves as his or her own control.

SUBJECTS

Thirty-one pediatric subjects aged 5 to 17 years.

INTERVENTION

Implantation of an active middle ear implant.

METHODS

Improvement in word recognition scores, speech reception thresholds (SRT) in quiet and noise, in addition to air conduction, bone conduction, and sound field thresholds were evaluated in two age groups.

RESULTS

Residual hearing did not change over time and speech intelligibility significantly improved and remained stable after 36 months. Children aged 5 to 9 improved in WRS from 21.92 to 95.38% and in SRT in quiet and in noise respectively from 62.45 dB SPL (sound pressure level) and +1.14 dB SNR to 42.07 dB SPL and -4.45 dB SNR. Adolescents aged 10 to 17 improved in WRS from 12.78 to 84.71% and in SRT in quiet and in noise respectively from 63.96 dB SPL and +3.32 dB SNR to 35.31 dB SPL and -4.55 dB SNR.

CONCLUSIONS

The AMEI, under investigation, is a safe treatment for children and adolescents, and significantly improved audiological performance that remains stable on the long-term scale (up to 36 mo postimplantation). In general, all adult-related issues and questions regarding safety and performance can also be applied to the pediatric population, as no apparent specific issues developed.

Efficacy of Auditory Implants for Patients With Conductive and Mixed Hearing Loss Depends on Implant Center

INTRODUCTION

Although from a technological point of view, progress is impressive, most implantable hearing devices for conductive or mixed hearing loss have a limited capacity. These devices all bypass the impaired middle ear; therefore, the desired amplification (gain) should be based on the cochlear hearing loss (component) only. The aim of the study is to review the literature with regard to accomplished gain with current implantable devices.

METHOD

Thirty-one articles could be included. Aided thresholds were compared with prescribed values, based on cochlear hearing loss (bone-conduction thresholds), according to the well-validated NAL rule.

RESULTS

For the majority of the studies, NAL targets were not met. Variation in accomplished gain between implant teams was unacceptably large, largely independent of the type of device that was used. NAL targets were best met at 2 kHz, with worse results at the other frequencies.

CONCLUSION

Large variations in reported results were found, which primarily depended on implant center. Based on the analyses, a pragmatic fitting procedure is proposed which should minimize the differences between implant centres.

The vibrating ossicular prosthesis in children and adolescents: a retrospective study

PURPOSE

The primary objective of the retrospective study was to collect speech intelligibility data on children and adolescents implanted with the vibrating ossicular prosthesis (VORP) 503.

METHODS

This was a retrospective, multicentre study on 55 children and adolescents from 6 German clinics aged between 5 and 17 years suffering from mixed or conductive hearing loss implanted with a VORP 503. Pre- and postoperative bone-conduction pure tone thresholds were measured at 0.5, 1, 2 and 4 kHz, and word recognition scores in the unaided and VORP 503-aided conditions using monosyllabic speech intelligibility tests measured at 65-dB sound pressure level (SPL) were determined.

RESULTS

Mean pre- and postoperative bone-conduction thresholds remained unchanged, showing the preservation of inner ear hearing. Speech intelligibility assessed in quiet at 65-dB SPL improved on average from 24.5% (SD ± 25.4) unaided to 86.4% (SD ± 13.4) aided. The average improvement of 61.9% (SD ± 25.3) was clinically and statistically significant. A total of three complications were found in the medical records of 55 subjects. The responsible investigators judged these events as procedure related.

CONCLUSION

The treatment of children suffering from conductive or mixed hearing loss with the VORP 503 implant demonstrates excellent aided benefit in terms of speech understanding and only minor complications.

Intraoperative Estimation of the Coupling Efficiency and Clinical Outcomes of the Vibrant Soundbridge Active Middle Ear Implant Using Auditory Brainstem Response Measurements

Purpose This study intraoperatively measured the coupling efficiency of the Vibrant Soundbridge (VSB), with the aim of avoiding revision surgery due to insufficient outcome. This method can also be used to test the integrity of the implant at the end of the implantation surgery and to evaluate aided thresholds. In addition, this method makes it possible to objectively test how well the VSB has been fitted, provide assistance in fitting handicapped patients or children, evaluate hearing degradation, or test for a drop in coupling efficiency before revision surgeries. In order to analyze the feasibility of these new VSB-aided auditory brainstem response (ABR) thresholds, they were compared to behavioral thresholds from the Vibrogram and the preoperative bone conduction thresholds. Method The study included 30 patients with mild-to-severe hearing loss implanted with a VSB (VORP503). Intraoperative ABR thresholds during the VSB implantation were recorded using a VSB-optimized chirp stimulus. The new method is compared to the bone conduction threshold of the study sample and the aided Vibrogram thresholds. Speech intelligibility results up to 24 months after surgery are also presented. Results A reliable correlation between the bone conduction thresholds and the intraoperative ABRs was found and was higher in comparison to the Vibrogram. Furthermore, speech intelligibility outcomes were stable over time. Conclusion ABR measurements can be used intraoperatively to estimate the coupling efficiency of the VSB and test the integrity of the implant at the end of surgery.

The Vibrant Soundbridge: A Global Overview

The Vibrant Soundbridge is a semi-implantable, active middle ear implant that is a safe and effective treatment for patients with sensorineural hearing loss. Since Food and Drug Administration approval for this indication, many international investigators have expanded its use for conductive and mixed hearing losses. This article reviews the author's experience and the international uses of this versatile device.

Round Window Application of an Active Middle Ear Implant: A Comparison With Hearing Aid Usage in Japan

Objective:

To report on the safety and efficacy of an investigational active middle ear implant (AMEI) in Japan, and to compare results to preoperative results with a hearing aid.

Design:

Prospective study conducted in Japan in which 23 Japanese-speaking adults suffering from conductive or mixed hearing loss received a VIBRANT SOUNDBRIDGE with implantation at the round window. Postoperative thresholds, speech perception results (word recognition scores, speech reception thresholds, signal-to-noise ratio [SNR]), and quality of life questionnaires at 20 weeks were compared with preoperative results with all patients receiving the same, best available hearing aid (HA).

Results:

Statistically significant improvements in postoperative AMEI-aided thresholds (1, 2, 4, and 8 kHz) and on the speech reception thresholds and word recognition scores tests, compared with preoperative HA-aided results, were observed. On the SNR, the subjects’ mean values showed statistically significant improvement, with −5.7 dB SNR for the AMEI-aided mean and −2.1 dB SNR for the preoperative HA-assisted mean. The APHAB quality of life questionnaire also showed statistically significant improvement with the AMEI.

Conclusion:

Results with the AMEI applied to the round window exceeded those of the best available hearing aid in speech perception as well as quality of life questionnaires. There were minimal adverse events or changes to patients’ residual hearing.

The Vibrant Soundbridge® middle ear implant: A historical overview

OBJECTIVE

To present a historical overview of the Vibrant Soundbridge^® (VSB) middle ear implant (MEI), since its beginning in the 1990s to date and to describe its course and contemplate what it might become in the future.

HISTORY

MEIs started to take form in researchers' mind in the 1930s with the first experiment of Wilska. In the 1970s, several devices, such as the Goode and Perkins', the Maniglia's, or the Hough and Dormer's were created but remained prototypes. It is only in the 1990s the devices that emerged remained on the market. In 1994, Symphonix, Inc. was created and aimed to manufacture and commercialize its semi-implantable MEI, the VSB. The principle of the VSB lies on a direct drive of the sound to a vibratory structure of the middle ear through an electromagnetic transducer, the floating mass transducer (FMT). The particularity of the system VSB is the simplicity of the transducer which is made of both the magnet and the coil; thus, the FMT, fixed on a vibrating middle ear structure, mimics the natural movement of the ossicular chain by moving in the same direction. The goal of the VSB was to give an alternative to patients with mild-to-severe sensorineural hearing loss who could not wear hearing aids (HAs) or who were unsatisfied conventional HA users. Subsequent to Tjellström's experiment in 1997, implantations started to include etiologies such as otosclerosis, radical mastoidectomy, failed ossiculoplasty/tympanoplasty, and atresia. Nowadays, the VSB, with more than 20 years of experience, is the oldest and most used middle ear implant worldwide. It is well acknowledged that the straightforward design and reliability of the transducer have certainly contributed to the success of the device.

Round window stimulation with the Vibrant Soundbridge: Comparison of direct and indirect coupling

OBJECTIVES/HYPOTHESIS

The purpose of this study was to measure the degree of coupling between the floating mass transducer (FMT) and the round window membrane (RWM) in patients with conductive and mixed hearing loss implanted with the Vibrant Soundbridge (VSB) device. The efficiency of direct and indirect coupling of the FMT to the RWM was compared by measuring differences between the initial prescription targets and the final settings of the VSB audio processor after fine-tuning.

STUDY DESIGN

Retrospective study.

METHODS

Investigation of a group of subjects with either conductive or mixed hearing loss implanted with the VSB, a device that uses a FMT coupled to the RWM. There were two subgroups: subjects in which coupling was direct (no interposed material) or indirect (interposed material). The functional gain, insertion gain, and compression characteristics of the device were measured to assess the efficiency of coupling and to investigate the proximity of the fitting to prescriptive targets.

RESULTS

Coupling for the subgroup with indirect coupling of the RWM was higher (better) than for the subgroup with direct coupling. The gain deviation from prescriptive targets was smaller for the subgroup with indirect coupling.

CONCLUSIONS

The coupling method can have an effect on the coupling efficiency and the final electroacoustic settings of the device. The prescription targets were not accurate for the majority of subjects from either subgroup. Indirect coupling appears to provide more effective stimulation of the cochlea.

LEVEL OF EVIDENCE

4. Laryngoscope, 127:2843-2849, 2017.

Does Coupling and Positioning in Vibroplasty Matter? A Prospective Cohort Study

OBJECTIVE

Vibroplasty has offered a new modality of hearing rehabilitation in patients with mixed, conductive, and sensorineural hearing loss who cannot wear hearing aids. Potentially, the positioning of the floating mass transducer (FMT) in vibroplasty surgery has a critical effect on hearing outputs. In this study, the impact on hearing outputs and coupling efficiency are evaluated by comparing various vibroplasty applications in the middle ear. No other study to date has examined the coupling efficiency of round window (RW) versus an ossicular vibroplasty application.

STUDY DESIGN

Prospective cohort study of patients with underlying ear pathologies who were not able to wear hearing aids.

METHODS

This is an ongoing prospective study of 16 patients. All patients had a standard audiological test battery. Direct drive transfer function analysis results were correlated with bone conduction thresholds to assess the efficiency of the FMT coupling. Speech perception in quiet and quality of life measure questionnaires were used to assess outcomes. Nine patients had round window vibroplasty, six patients had stapes vibroplasty, and one patient had traditional incus vibroplasty.

RESULTS

Patients with a soft tissue coupler between the FMT and the RW had significantly reduced coupling efficiency. Patients who had direct RW contact had significantly improved coupling efficiency. Patients who underwent stapes or incus vibroplasty had the greatest coupling efficiency.

CONCLUSION

This study demonstrates that attachment to the stapes or incus provides the best coupling when compared to round window vibroplasty. When applicable, stapes or incus coupling should be the first choice when implementing vibroplasty.

The Vibrant Soundbridge in Children and Adolescents: Preliminary European Multicenter Results

OBJECTIVE

Evaluation of safety and efficacy of the Vibrant Soundbridge in the treatment of hearing loss in children and adolescents with primary focus on improvement in speech discrimination.

STUDY DESIGN

Prospective, single-subject repeated-measures design in which each subject serves as his/her own control.

SETTING

Tertiary referral center.

PATIENTS

Nineteen patients aged 5 to 17 years.

INTERVENTION

Implantation of an active middle ear implant.

MAIN OUTCOME MEASURE

Improvement in word recognition scores, speech reception thresholds, and signal-to-noise ratios (SNRs) were evaluated, in addition to air and bone conduction. Oldenburger Kids Satztest/Oldenburger Satztest sentences and Göttinger/Freiburger monosyllables at 65-dB hearing level were tested in two age groups.

RESULTS

Significant speech discrimination improvement was seen in all patients after 6 months. In children 5 to 9 years old, mean monosyllable recognition improved from 28.9% (unaided) to 95.5% (Soundbridge-aided). Aided 50% sentence discrimination at 44.1 dB and SNR of -4.9 dB were measured. In patients 10 to 17 years old, mean word recognition improved from 18.5% to 89.0%, sentence reception threshold improved to 40.2 dB, and SNR to -3.6 dB. Comparison between age groups indicated a slight trend toward quicker adaptation by older subjects. However, after initial adjustment, a higher level of overall benefit was seen at 6 months in younger children.

CONCLUSIONS

Currently, the only middle ear implant approved for pediatric patients, the Vibrant Soundbridge, provides an option in cases of congenital aural atresia or disease-induced defects, when surgical intervention and reconstruction is indicated. The 6-month results in this comparatively large study population validated conclusions found in previous trials.

[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.

Comparison of two different titanium couplers for an active middle ear implant

OBJECTIVE

To compare surgical methods, functional gain, and speech discrimination using two different coupling methods for an active middle ear implant. Of several couplers enabling placement of the active element at various locations, two function directly at a cochlear membrane, bypassing a missing or malformed ossicular chain. This study evaluates whether either of these methods is more beneficial.

STUDY DESIGN

Retrospective case review.

SETTING

ENT surgical clinic.

PATIENTS

Forty-seven German-speaking patients with moderate to severe mixed hearing loss.

INTERVENTIONS

Records of patients implanted with either a round window (RW) or oval window (OW) coupler and active implant were examined. Preoperative and postoperative bone and air-conduction thresholds, auditory gain, and speech perception were compared.

MAIN OUTCOME MEASURES

Functional gain, Freiburger monosyllables in quiet.

RESULTS

The range of hearing benefit shown by functional gain in patients implanted with the RW coupler (median) was between 22.5 dB (at 0.25 kHz) and 52.5 dB (2 and 3 kHz). In the OW group, improvement was similar, ranging from 21 dB (at 8 kHz) to 50 dB (1 and 2 kHz). Patients in both groups showed a similar improvement in speech recognition. Median preoperative unaided word recognition was 0% at 60 dB HL for both patient groups, improved postoperatively in both groups to median 85% correct at 65 dB HL and 95% at 80 dB HL.

CONCLUSION

Placement of an active middle ear implant using the RW and the OW coupler was found to be safe, although the surgical methods differ. Safety and efficacy of both couplers present no significant differences.

Consensus statement on round window vibroplasty

OBJECTIVE

This study aimed to review current knowledge regarding implantation of the Vibrant Soundbridge floating mass transducer (FMT) at the round window (round window vibroplasty) as well as to form a consensus on steps for a reliable, stable surgical procedure.

DATA SOURCES

Review of the literature and experimental observations by the authors.

CONCLUSION

Round window (RW) vibroplasty has been established as a reliable procedure that produces good and stable results for patients with conductive or mixed hearing loss. The experience gained over the past few years of the authors' more than 200 implantations has led to consensus on several key points: (1) a wide and bloodless access to the middle ear with facial nerve monitoring, (2) the careful and correct identification and exposure of the round window membrane, (3) a good setup for efficient energy transition of the FMT, namely, perpendicular placement of the FMT with no contact to bone and the placement of cartilage behind the FMT to create a preloaded "spring" function, and (4) 4 points of FMT fixation: a rim of the round window bony overhang left intact both anterior and posterior to the FMT, conductor link stabilization, and cartilage behind the FMT. In addition, the FMT should be covered with soft tissue.

Contemporary hearing rehabilitation options in patients with aural atresia

Congenital aural atresia is the failure of development of the external auditory canal. It usually occurs in conjunction with microtia, which is the malformation of the auricle due to a failure of development of the external ear. Aural atresia, with or without microtia, may significantly affect the hearing and social life of the patients. It is important for every medical practitioner to be aware of the possible treatment options for hearing rehabilitation in this group of patients. In the era of modern technology, new choices, including Bone-Anchored Hearing Aid (BAHA) (Cochlear Ltd. and Oticon Medical), Vibrant Soundbridge (VSB) (MED-EL, Innsbruck, Austria), and Bonebridge system (BB) (MED-EL, Innsbruck, Austria), provide high-end alternatives to traditional Bone Conduction Hearing Aid and Auditory Canal Reconstruction. All these options have advantages and disadvantages, and they are appropriate for different patients and/or at different ages. This paper aims to provide an overview of the management of hearing rehabilitation in congenital aural atresia patients and a discussion of each treatment option.

Vestibulotomy with ossiculoplasty versus round window vibroplasty procedure in children with oval window aplasia

OBJECTIVE

To review the surgical procedures and outcomes in children with bilateral oval window aplasia (OWA).

STUDY DESIGN

Retrospective cohort review.

SETTING

Tertiary referral center.

PATIENTS

Children suffering from OWA between 1990 and 2010.

INTERVENTION

Vestibulotomy with ossiculoplasty (V-OPL) or round window vibroplasty (RWV).

MAIN OUTCOME MEASURES

Findings at radiology and surgery, preoperative and postoperative bone conduction (BC), air conduction (AC), and RWV-air conduction (RWV-AC) thresholds and speech discrimination scores (SDSs).

RESULTS

Among 23 children, 11 underwent V-OPL and 8 RWV. Four children in the V-OPL group had aborted surgery and were excluded from the study. In all the remaining 19 children, the 6-month follow-up time showed postoperative AC and SDS values significantly better than the preoperative thresholds in both groups. At the 36-month long-term follow-up, AC and SDS were stable in the RWV group but showed a significant worsening in the V-OPL children compared with the 6-month follow-up results. Preoperative versus postoperative BC values showed a significant difference between the 2 groups at 36 months; 5 of the V-OPL group underwent revision following the same surgical principles, which did not result in improved outcome.

CONCLUSION

In children with OWA, V-OPL provides modest long-term results and carries higher risks of BC degradation compared to RWV. Both procedures are technically challenging but considering the respective hearing results and morbidity of primary and revision surgery, we have abandoned the V-OPL procedure in favor of RWV. In infants and children younger than 5 years with OWA previously not considered candidates for hearing restoration, we consider RWV as the first-choice surgery. It has shown to provide significantly better hearing outcomes than traditional atresia surgery with minimal complication rate.

Vibroplasty for mixed and conductive hearing loss

OBJECTIVE

To summarize new application methods of an active middle ear implant (Vibrant Soundbridge) in patients with conductive or mixed hearing loss.

DATA SOURCES

Publications listed in the Medline/PubMed database.

STUDY SELECTION

All publications published in English language; search term Vibrant Soundbridge AND floating mass transducer in all fields.

DATA EXTRACTION

Structured analysis of all publications.

DATA SYNTHESIS

Extraction of significant findings and conclusions and audiometric data.

CONCLUSION

Modern application methods of an active middle ear implant (VSB) open new therapeutic options for patients with various outer and middle ear diseases resulting in conductive or mixed hearing loss. Titanium couplers can help to couple the active middle ear implant in a standardized way to remnants of the ossicular chain or to the round window. Thus, the active middle ear implant has been established as an alternative treatment option for patients with mixed and conductive hearing. However, the heterogeneity of the studies published so far complicates the analysis of the audiometric results, and thus, the functional hearing gain after VSB implantation varies a lot.

Vibrant Soundbridge implantation via the third window in two Chinese patients with severe bilateral congenital aural atresia

CONCLUSION

In patients with undeveloped vestibular/oval windows and inaccessible round windows, Vibrant Soundbridge (VSB) implantation performed by placing the transducer into a reconstructed window on the inner tympanum wall demonstrated significant improvement in hearing and verbal communication ability.

OBJECTIVE

To report our surgical experience with new placement of the VSB in pediatric patients with undeveloped vestibular windows, inaccessible round windows, and severe bilateral congenital aural atresia (CAA).

METHODS

In two patients with bilateral CAA selected for middle ear implantation, CT scans revealed severe middle ear malformation including inaccessible round windows, absence of vestibular/oval windows, and abnormal facial nerve anatomy. The transducer of the VSB was implanted into a 'window' drilled at the inner tympanum wall in both patients.

RESULTS

The surgery was successful. Pure-tone air conduction thresholds across the frequencies of 0.25-8 Hz were improved by 35 dB (preoperation, 69.2 dB; postactivation, 34 dB) in patient 1 and 46.6 dB (preoperation, 75.8 dB; postactivation, 24.2 dB) in patient 2. Normal hearing thresholds were achieved in the range of 1-8 kHz in both patients. A sentence recognition rate of up to 100% (65 dB SPL in a quiet room) was attained by both patients after surgery and VSB activation at 3 months postoperatively.

Comparison of forward (ear-canal) and reverse (round-window) sound stimulation of the cochlea

The cochlea is normally driven with "forward" stimulation, in which sound is introduced to the ear canal. Alternatively, the cochlea can be stimulated at the round window (RW) using an actuator. During RW "reverse" stimulation, the acoustic flow starting at the RW does not necessarily take the same path as during forward stimulation. To understand the differences between forward and reverse stimulation, we measured ear-canal pressure, stapes velocity, RW velocity, and intracochlear pressures in scala vestibuli (SV) and scala tympani (ST) of fresh human temporal bones. During forward stimulation, the cochlear drive (differential pressure across the partition) results from the large difference in magnitude between the pressures of SV and ST, which occurs due to the high compliance of the RW. During reverse stimulation, the relatively high impedance of the middle ear causes the pressures of SV and ST to have similar magnitudes, and the differential pressure results primarily from the difference in phase of the pressures. Furthermore, the sound path differs between forward and reverse stimulation, such that motion through a third window is more significant during reverse stimulation. Additionally, we determined that although stapes velocity is a good estimate of cochlear drive during forward stimulation, it is not a good measure during reverse stimulation. This article is part of a special issue entitled "MEMRO 2012".

Application of the Vibrant Soundbridge middle-ear implant for aural atresia in patients with Treacher Collins syndrome

OBJECTIVE

To present results for the auditory rehabilitation of patients with Treacher Collins syndrome with bilateral osseous atresia, using middle-ear implantation with a Vibrant Soundbridge.

METHODS

Three patients underwent vibroplasty for aural atresia with moderate to severe conductive hearing loss. The pre-operative Jahrsdoerfer radiological score was 4 for all patients. Patients underwent active middle-ear implantation of a Vibrant Soundbridge implant (coupling the floating mass transducer to the rudimentary stapes or footplate distally, and positioning it adjacent to the round window membrane proximally), with audiological analysis as follow up.

RESULTS

After implant activation, the mean air conduction threshold ± standard deviation decreased to 22.8 ± 5.5 dB HL, representing a mean functional gain of 44.5 dB. The mean word recognition score (for bisyllabic words at 65 dB SPL) increased from 0 to 97 per cent.

CONCLUSION

Vibrant Soundbridge implantation is an effective hearing rehabilitation procedure in patients with Treacher Collins syndrome with bilateral osseous atresia. This is a versatile implant which can achieve coupling even in cases of severe middle-ear malformation.

Electrocochleography in Round Window Vibrant Soundbridge Implantation

Objective. To determine the role of intraoperative electrocochleography to optimize the fitting of the floating mass transducer of the Vibrant Soundbridge on the round window membrane in patients with conductive and mixed hearing loss.

Study Design. Prospective cohort study.

Setting. Tertiary referral center, Otolaryngology Department, University of Verona, Verona, Italy.

Subjects and Methods. Twenty-six adult patients suffering from chronic otitis media with moderate to severe conductive and mixed hearing loss, all with previous unsuccessful functional surgery, underwent round window vibroplasty. Thirteen subjects had intraoperative compound cochlear action potentials measured to assess vibroplasty coupling during and after surgery. In these patients, surgery was modified according to electrocochleographic feedback. The other 13 had vibroplasty without electrocochleography monitoring.

Results. The average preoperative air conduction and bone conduction thresholds (0.5-4 kHz) were not statistically significantly different between the 2 cohorts ( P > .05). Compound action potential recordings indicated specific surgical modalities to optimize coupling of the floating mass transducer with the round window membrane. The average postoperative Vibrant Soundbridge–aided air conduction threshold improvements (0.5-4 kHz) were 54.6 ± 8.9 and 41.7 ± 11.1 dB HL, respectively, in the monitored and unmonitored cohorts ( P = .0032).

Conclusion. Improved round window vibroplasty outcomes are observed when the surgeon is promptly informed of the compound action potential changes induced by the floating mass transducer round window membrane vibroplasty and alters surgery accordingly. The key point for optimal coupling is a floating mass transducer in full contact with the round window membrane, free to vibrate without any contact with the surrounding bony structures and mobile footplate.