Adverse events associated with bone-conduction and middle-ear implants: a systematic review.

PURPOSE: To review types and frequencies of adverse events (AE) associated with bone-conduction hearing implants (BCHIs) and active middle-ear implants (aMEIs) as reported in the literature. METHODS: Cochrane, PubMed, and EMBASE libraries were searched for primary articles in English or German language that reported on adverse events following BCHI or aMEI implantation, included at least five patients and were published between 1996 and 2016. Study characteristics, demographics, and counts of adverse events were tabulated and analyzed within the R statistical programming environment. RESULTS: Following assessment of the reporting quality of adverse events, we present a brief guideline that potentially improves AE reporting in this field of research. For the full dataset, we summarize study-level adverse event frequencies in terms of ratio of events to ears (REE) by AE groups and by device. For a subset of studies, we also report cumulative incidence (risk) for minor- and major adverse-events by device and by device groups. CONCLUSIONS: Data analyzed in this review show that: (1) the reporting quality of adverse events associated with BCHI and aMEIs is often very low; (2) adverse events associated with BCHI and aMEIs are qualitatively different and not equally frequent among devices; (3) state-of-the-art implantable BCHIs and aMEIs are a safe treatment option for hearing loss.

Minimal Reporting Standards for Active Middle Ear Hearing Implants.

There is currently no standardized method for reporting audiological, surgical and subjective outcome measures in clinical trials with active middle ear implants (AMEIs). It is often difficult to compare studies due to data incompatibility and to perform meta-analyses across different centres is almost impossible. A committee of ENT and audiological experts from Germany, Austria and Switzerland decided to address this issue by developing new minimal standards for reporting the outcomes of AMEI clinical trials. The consensus presented here aims to provide a recommendation to enable better inter-study comparability.

The Impact of Two-Stage Subtotal Petrosectomy and Round Window Vibroplasty on Bone Conduction Thresholds.

OBJECTIVE: To evaluate possible increases in bone conduction (BC) hearing thresholds in patients undergoing subtotal petrosectomy (SP) with fat obliteration and blind sac closure of the outer ear canal and subsequent round window vibroplasty. PATIENTS AND INTERVENTIONS: Between 1997 and 2013, 43 patients (45 ears) with combined hearing loss and recurrent chronic otitis or status post formation of a radical cavity underwent SP around 6 months prior to implantation of a Vibrant SoundbridgeTM. Pure tone audiograms (0.5, 1, 1.5, 2, 3, 4, and 6 kHz) prior to SP, after SP, prior to implantation, after implantation, and at first fitting around 5 weeks after implantation were collected and statistically analyzed. RESULTS: The comparison between BC thresholds before SP and at first fitting showed an overall decline during the two-step procedure between 2.8 and 6 dB that was significant (p < 0.05, Student t test) at 2, 3, 4, and 6 kHz. CONCLUSION: In some cases, SP is the only way to eradicate chronic otitis and to achieve a suitable environment for the implantation of active middle ear implants. The present data demonstrate a relatively small but significant decline in BC thresholds throughout the whole procedure. Knowledge of its extent is mandatory for a correct indication for later implantation of a Vibrant SoundbridgeTM.

Impact of the surgical wound closure technique on the revision surgery rate after subtotal petrosectomy.

The objective of the study was to examine the impact of the surgical wound closure technique as protection of the obliterated tympanomastoid cavity on the revision surgery rate after subtotal petrosectomy (SP). This is a retrospective case series conducted in a tertiary care referral center. 199 patients (212 ears) with recurrent chronic otitis media underwent SP followed by tympanomastoid obliteration with abdominal fat at a single tertiary referral center between 2005 and 2015. 124 SP were carried out without (group A), 74 with temporalis muscle flap (group B) and 14 with reinforcing material like polydioxanone foil or bovine pericardium or allogenic fascia lata (group C) for wound closure. The evaluated follow-up was either until the scheduled device implantation or 6 months postoperatively. We assessed the rate of postoperative wound healing disorder with revision surgery according to the surgical technique for closure of the obliterated cleft. Revision surgery due to impaired wound healing was necessary in 16 % of the total cases (group A: 18.5 %, group B: 10.8 %, group C: 21.4 %). Further analysis concerning the dehiscent area in both sites (retroauricular and blind sac of the external auditory canal) was conducted and discussed. There was no significant difference observed in the rate of revision surgery between the three groups. The wound healing process after SP is determined by many factors and cannot be significantly influenced solely by reinforcing tissue like the temporalis muscle flap or supporting materials.

Subtotal petrosectomy and Codacs™: new possibilities in ears with chronic infection.

Subtotal petrosectomy combined with obliteration of the tympanomastoid is a standard procedure to treat temporal bones in patients with radical cavity and chronic infections. Currently, patients with profound-to-severe sensorineural hearing loss are often fitted with cochlear implants. In the case of profound mixed hearing loss, active middle ear implants have been used successfully. The new Codacs™ system provides an effective treatment for patients with severe-to-profound mixed hearing loss; however, only aerated middle ears have been treated with this device. The question arises whether the Codacs™ can be implanted in patients with radical cavity or ears with chronic otorrhea. Of the 41 patients who were implanted with the Codacs™ at the department, 4 received the device after subtotal petrosectomy and obliteration with abdominal fat. Clinical and audiological results were assessed. The device was implanted without any complications in the obliterated subtotal petrosectomy. The preliminary results of the first two patients showed stable bone conduction thresholds and indicated improved speech intelligibility in quiet and noise. Implanting the Codacs™ device after subtotal petrosectomy and obliteration with abdominal fat has been proven to be a feasible and suitable procedure for patients with radical cavity or chronic otorrhea. The speech intelligibility outcome directly after activation was comparable to patients with aerated middle ears.

Long-term results of incus vibroplasty in patients with moderate-to-severe sensorineural hearing loss.

OBJECTIVES: The principal aim of this study was to assess the safety and effectiveness of the middle ear implant Vibrant Soundbridge (VSB) in patients with moderate-to-severe sensorineural hearing loss up to a mean (± standard deviation) duration of 11.1 ± 2.1 years (min. = 8.2, max. = 13.9, n = 16) after the intervention. DESIGN: This was a retrospective, single-subject repeated-measurements study over a long-term period. A total of 104 German-speaking adults (for 122 implants) were included in this study (54 male, 50 female). The mean age at implantation was 54.5 years (min. = 19.0, max. = 80.4). Audiological outcome and speech intelligibility were assessed in all VSB patients at different time points in non-overlapping groups. RESULTS: Bone conduction (BC) thresholds were preserved after the implantation and no indication was found of an increase over time of the small air-bone gaps introduced by the implantation. BC and air conduction thresholds worsened similarly in both implanted and non-implanted ears over time. The decrease in audiological benefit provided by the VSB was moderate and the Word Recognition Score in quiet conditions at 65 dB SPL was still largely improved with the VSB in the longest observed group. CONCLUSIONS: These results confirm that the VSB does not affect the integrity of the inner/middle ear and is still beneficial in long-term follow-up.

Retrospective audiological analysis of bone conduction versus round window vibratory stimulation in patients with mixed hearing loss.

OBJECTIVE: To compare audiological outcomes in mild-to-moderate mixed hearing loss patients treated with a bone-anchored hearing aid or an active middle-ear implant. Analysis aimed to refine criteria used in preoperative selection of implant type. DESIGN: Retrospective comparative analysis of audiological data. Follow-up time ranged between 0.55 and 8.8 years. STUDY SAMPLE: For detailed comparative analysis, 12 patients (six in each group) with comparable bone conduction thresholds and similar clinical characteristics were selected. A larger cohort of 48 patient files were used to evaluate overall audiological indication criteria (24 per group). RESULTS: In free-field tone audiometry, Baha patients showed mean aided thresholds between 40-48 dB, whereas hearing thresholds for VSB patients were 25-43 dB. Baha and VSB users had mean WRS of 56% and 82%, respectively, at 65 dB. Better speech understanding in noise was seen with the VSB. CONCLUSION: Analysis of the main cohort (n = 48) showed that treatment with round window vibroplasty leads to better hearing performance than treatment with a bone-anchored hearing device, if the bone conduction pure-tone average (0.5 to 4 kHz) is poorer than 35 dB HL. Audiological analysis in the smaller comparative analysis showed similar findings.

Indications and outcome of subtotal petrosectomy for active middle ear implants.

The aim of this study was to describe the outcome and possible complications of subtotal petrosectomy (SP) for Vibrant Soundbridge (VSB) device surgery in a tertiary referral center. A secondary objective was the evaluation of hearing results in a subgroup of subjects who received the VSB device. Between 2009 and early 2011, 22 adult subjects with chronic otitis media (COM) underwent a SP, blind sac closure of the external auditory canal and abdominal fat obliteration to facilitate the application of an active middle ear implant (AMEI) in a staged procedure. Indications consisted of mixed hearing loss after previous tympanomastoplasty and failure of hearing rehabilitation with a hearing aid or bone conduction device in COM. Pre- and postoperative pure-tone audiograms were analyzed in respect to deterioration of inner ear function, unaided and aided (hearing aid, bone-anchored hearing aid and VSB) speech audiograms were compared to verify improvements in communications skills and functional gains. Incidence and type of complications were reviewed. No significant change was observed regarding mean bone conduction thresholds after the first stage procedure. Some minor wound healing problems were noted. Speech perception using the VSB (n = 16) showed a mean aided speech discrimination at 65-dB SPL of 75 % [standard deviation (SD) 28.7], at 80-dB SPL of 90 % (SD 25.1). Our results suggest that for selected patients with open mastoid cavities and chronic middle ear disease, SP with abdominal fat obliteration is an effective and safe technique to facilitate safe AMEI placement.

Controlling the position and the dislocation of the middle ear transducer with high-resolution computed tomography and digital volume tomography: implications for the transducers' design.

A minimal tip dislocation of the middle ear transducer (MET(®), Otologics Ltd) may result in poor hearing performance. Our objective was to examine if a defined MET dislocation can be diagnosed by high-resolution computed tomography (HRCT) or digital volume tomography (DVT). A human cadaver head was sequentially implanted with different MET tips (incus application) including a ceramic tip (T 1c), a titanium tip (T 1t), a new, thinner titanium tip (T 2), and a spherical titanium tip (Ts). HRCT and DVT studies were performed. Afterward, the tips were pulled back 0.5 mm, so that they were not attached to the incus. HRCT and DVT scans were repeated to identify the dislocation. Using the best plain in HRCT images, the dislocation of the transducer could be measured reliably and reproducibly in half of the cases. In particular, the precise positioning and the dislocation could be identified when T 1t and Ts were implanted, with the Ts showing the best visibility. DVT failed in recognizing the dislocation in all cases. The identification of MET tip's dislocation with HRCT depends on the shape, size, and material of the tip. This knowledge is useful for the design of the implants, as determination of the right position of the middle ear transducer may be proven important for the hearing outcome. In some cases, however, surgical exploration may still be required. Although DVT represents a promising imaging method for the otologists, it can barely help when MET dislocation is suspected.

Ear and further anatomic anomalies in children undergoing stapedotomy.

PURPOSE: Aim of this study was to examine any stapes fixation-related clinical, intraoperative and high-resolution computed tomography (HRCT) findings in children undergoing stapedotomy. PROCEDURES: Detailed diagnostic assessment was performed in 12 children (18 ears) who underwent stapedotomy within the period 2005-2008. RESULTS: Ear malformations such as malleus-incus anomalies, malleus-epitympanum fixation and absence of the stapedius tendon, small external auditory canal and auricle malformations were clinically and/or intraoperatively diagnosed. HRCT identified a petrous high jugular bulb and malformed inner auditory canal in 4 ears; however, it failed to recognize ossicular fixation. Systemic anomalies, namely kyphoscoliosis, esophageal atresia and finger malformations were identified in 2 children. Summing up, additional anatomic anomalies were found in 8 patients (66.7%). CONCLUSIONS: Ear malformations may coexist in children with stapes fixation. Ossicular fixation is not easily recognized with HRCT, and therefore, ossicular mobility should always be tested intraoperatively. In a few cases, pediatric stapes fixation can coexist with systemic dysplasias; in such patients, additional referral to geneticists is recommended.

Impact of occlusive material and cochlea-carotid artery relation on eustachian tube occlusion in subtotal petrosectomy.

OBJECTIVE: To evaluate the success rate of eustachian tube (ET) occlusion in subtotal petrosectomy relative to the occlusive material used and to the varying protympanum anatomy, by means of standardized alignment of the cochlea-carotid artery relation on computed tomography images. PATIENTS AND METHODS: All cases of subtotal petrosectomy carried out by the same surgeon at a tertiary care referral center were retrospectively evaluated. Only cases with available computed tomography prior to second stage cochlear or middle ear implantation were included. The occlusive material was either muscle tissue or oxidized regenerated cellulose in combination with bone wax. On 3D multiplanar image reconstruction, the varying topographic interrelation of the cochlea and the petrous carotid artery was measured and categorized into two groups: detachment or overlapping. RESULTS: In 9 (31%) of the 29 included cases there was insufficient occlusion of the ET. In none of these cases was an infection of the fat filling in the obliterated cavity observed during the implantation procedure on second stage (average 10 months interval). The failure rate of both occlusion materials was almost the same (using muscle tissue, in 4 (33.3%) of 12 or oxidized regenerated cellulose, in 5 (29.4%) of 17 cases). It was also similar for both materials in each of the anatomic variation groups. CONCLUSIONS: An incomplete occlusion of the ET alone does not appear to lead to an infection of the obliterated cavity. Autologous muscle tissue and oxidized regenerated cellulose had similar rates of ET occlusion failure. The topographical variance of the protympanum appears to have no direct influence on the success of the ET occlusion.

Clinical results after stapedotomy: a comparison between the erbium: yttrium-aluminum-garnet laser and the conventional technique.

OBJECTIVE: The objective of this study was to assess whether the use of the erbium: yttrium-aluminum-garnet (Er:YAG) laser has negative effects on inner ear function and to compare the short- and long-term hearing outcome of patients undergoing conventional stapedotomy versus laser stapedotomy. STUDY DESIGN: Retrospective review of prospectively collected audiometric data of patients with otosclerosis operated on by one experienced surgeon. SETTING: Academic tertiary referral center. PATIENTS: A total of 266 stapes surgeries were evaluated for intraoperative findings, of which 209 patients were evaluated for preoperative and postoperative hearing thresholds after a 6- to 452-week (mean, 22 wk) audiological follow-up. INTERVENTION: One hundred fifteen (43%) of the operations were performed conventionally, using manual perforators for stapedotomy (Group A); in 115 (43%) surgeries, the perforators were used in combination with the Er:YAG laser (Group B), and in 36 (14%) operations, the Er:YAG was used exclusively for footplate perforation (Group C). MAIN OUTCOME MEASURES: Pure-tone audiometry was performed before surgery, 2 days postoperatively (bone conduction only) and at 5, 26, and 57 weeks postoperatively. RESULTS: A postoperative temporary threshold shift of the bone conduction could be found in all groups. In Group C, where the laser was used exclusively for footplate perforation, this threshold shift was not only the most significant, but also-in contrast to the other groups-not totally reversible. In all techniques, a satisfactory air-bone gap closure could be achieved. The best long-term results (96% of the patients had

Comparison of Audiological Results Between a Transcutaneous and a Percutaneous Bone Conduction Instrument in Conductive Hearing Loss.

OBJECTIVES: In conductive, mixed hearing losses and single-sided-deafness bone-anchored hearing aids are a well-established treatment. The transcutaneous transmission across the intact skin avoids the percutaneous abutment of a bone-anchored device with the usual risk of infections and requires less care.In this study, the audiological results of the Bonebridge transcutaneous bone conduction implant (MED-EL) are compared to the generally used percutaneous device BP100 (Cochlear Ltd., Sydney, Australia). METHODS: Ten patients implanted with the transcutaneous hearing implant were compared to 10 matched patients implanted with a percutaneous device. Tests included pure-tone AC and BC thresholds and unaided and aided sound field thresholds. Speech intelligibility was determined in quiet using the Freiburg monosyllable test and in noise with the Oldenburg sentence test (OLSA) in sound field with speech from the front (S0). The subjective benefit was assessed with the Abbreviated Profile of Hearing Aid Benefit. RESULTS: In comparison with the unaided condition there was a significant improvement in aided thresholds, word recognition scores (WRS), and speech reception thresholds (SRT) in noise, measured in sound field, for both devices. The comparison of the two devices revealed a minor but not significant difference in functional gain (Bonebridge: PTA = 27.5 dB [mean]; BAHA: PTA = 26.3 dB [mean]). No significant difference between the two devices was found when comparing the improvement in WRSs and SRTs (Bonebridge: improvement WRS = 80% [median], improvement SRT = 6.5 dB SNR [median]; BAHA: improvement WRS = 77.5% [median], BAHA: improvement SRT = 6.9 dB SNR [median]). CONCLUSION: Our data show that the transcutaneous bone conduction hearing implant is an audiologically equivalent alternative to percutaneous bone-anchored devices in conductive hearing loss with a minor sensorineural hearing loss component.

Indication of direct acoustical cochlea stimulation in comparison to cochlear implants.

The new implantable hearing system Codacs™ was designed to close the treatment gap between active middle ear implants and cochlear implants in cases of severe-to-profound mixed hearing loss. The Codacs™ actuator is attached to conventional stapes prosthesis during the implantation and thereby provides acoustical stimulation through a stapedotomy to the cochlea. Cochlear implants (CIs) on the other hand are an established treatment option for profoundly deaf patients including mixed hearing losses that are possible candidates for the Codacs™. In this retrospective study, we compared the clinical outcome of 25 patients with the Codacs™ (≥3 month post-activation) to 54 CI patients (two years post-activation) with comparable pre-operative bone conduction (BC) thresholds that were potential candidates for both categories of devices. The word recognition score (Freiburg monosyllables test) in quiet was significantly (p < 0.05) better in the Codacs™ than in the corresponding CI patients for average pre-operative bone conduction below 60 dB HL and equal in patients with a pre-operative BC PTA between 60 and 70 dB HL. Speech in noise intelligibility (HSM sentences test at +10 dB SNR) was significantly (p < 0.001) better in Codacs™ (80% median) than in CI patients (25% median) in all tested groups. Our results indicate for patients with sufficient cochlear reserve that speech intelligibility in noise with the Codacs™ hearing implant is significantly better than with a CI. Further, results in Codacs™ were better predictable, encouraging the extension of the indication to patients with less cochlear reserve than reported here.

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.

Round window stimulation with the floating mass transducer at constant pretension.

OBJECTIVE: Mechanical stimulation of the round window (RW) of the cochlea is successfully done with the Vibrant Soundbridge (Med-El), but clinical outcomes show a substantial degree of variability. One source of variability is variation in the static force applied by the stimulator to the round window (Maier et al., 2013). In this study we investigated other sources of variability by maintaining a constant pre-load testing the effect of a coupler device and the interposition of soft tissue between the stimulator and the RW. STUDY DESIGN: Experimental. METHODS: The stapes footplate displacement produced by stimulation of the round window was determined in fresh human temporal bones. The response to sound and actuator stimulation was measured with a Laser Doppler Velocimeter at the stapes footplate. The RW was stimulated by a Floating Mass Transducer (FMT) with/without (1) an additional RW coupler (supplied by the manufacturer), and (2) the interposition of TUTOPATCH between the stimulator and the RW, while maintaining a pre-load of ∼1.96 mN. RESULTS: In 8 temporal bones with normal stapes footplate response to sound, we found an average 11.9 dB increase (500 Hz-2 kHz) under controlled conditions by using the coupler together with the interposition. The increase was statistically significant at 500 Hz (p < 0.01). Additionally, the coupler/interposition combination reduced the variability between experiments (FMT alone SD = 10.9 dB; FMT with TUTOPATCH & coupler: SD = 3.4 dB @ 500 Hz) and increased the repeatability. CONCLUSION: At controlled static force an improved output level, inter-subject variability and repeatability were found by using a coupler/TUTOPATCH combination in RW stimulation with the FMT. The high variability found in clinical experience is not solely due to inter-subject variability, but to coupling conditions and can be optimized further.

Do we really need a Coupler for the round window application of an AMEI?

OBJECTIVE: Implanting active middle ear implants (AMEI) at the round window has become a standard procedure to restore hearing for patients with moderate inner ear or mixed hearing loss. The round window (RW)-Coupler was developed as an alternative coupling aid to fit smaller RW diameters and require less drilling in the RW niche. The question arises whether using the RW-Coupler is useful and a safe procedure compared with the nonuse of the RW-Coupler MATERIALS AND METHODS: Forty-nine German-speaking patients were implanted with either a RW-Coupler attached to an AMEI floating mass transducer (FMT) or without coupler. They were evaluated preoperatively and postoperatively for bone and air conduction thresholds with and without the implant, as well as speech perception tests. RESULTS: Bone conduction thresholds remained stable preoperatively and postoperatively. The patient's functional gain was slightly better with the RW-Coupler. Focusing on the average speech perception performances, both groups presented an improvement of speech perception above 80% at 65 dB HL. CONCLUSION: RW-Coupler-Vibroplasty was found to be a safe procedure, which produced good results in this group of patients with mixed hearing loss.

The effect of static force on round window stimulation with the direct acoustic cochlea stimulator.

The Direct Acoustic Cochlea Stimulator Partial Implant (DACS PI, Phonak Acoustic Implants SA, Switzerland) is intended to stimulate the cochlea by a conventional stapedotomy piston that is crimped onto the DACS PI artificial incus. An alternative approach to the round window (RW) is successfully done with other devices, having the advantage of being also independent of the existence of middle ear structure (e.g. ossicles). Here the possibility of stimulating the RW with the DACS actuator is investigated including the impact of static force on sound transmission to the cochlea. The maximum equivalent sound pressure output with RW stimulation was determined experimentally in fresh human temporal bones. Experiments were performed in analogy to the ASTM standard (F2504.24930-1) method for the output determination of implantable middle ear hearing devices (IMEHDs) in human cadaveric temporal bones (TBs). ASTM compliant temporal bones were stimulated with a prosthesis having a spherical tip (∅0.5 mm) attached to the actuator. The stimulation was performed perpendicular to the round window membrane (RWM) at varying position relative to the RW and the resulting static force on the RW membrane was determined. At each position the displacement output of the DACS PI actuator and the stapes footplate (SFP) vibration in response to actuator stimulation was measured with a Laser Doppler Velocimeter (LDV). By comparison of the achieved output at the stapes footplate in response to sound and transducer stimulation the equivalent sound pressure level at the tympanic membrane at 1Vrms input voltage was calculated assuming that the SFP displacement in both conditions is a measure of perceived loudness, as it is done in the ASTM standard. Ten TB preparations within the acceptance range of the ASTM standard were used for analysis. The actuator driven stapes footplate displacement amplitude as well as the resulting equivalent sound pressure level was highly dependent on the static force applied to the RW. The sound transfer efficiency from the RW to the stapes footplate increased monotonically with increasing static load. At a moderate static force load (approx. 3.9 mN) the obtained average sound equivalent sound pressure level was 102-120 eq. dB SPL @ nominally 1Vrms input for frequencies ≤4 kHz. At higher frequencies (6-10 kHz) the achieved output dropped to ∼90 dB SPL. This output was obtained at loading conditions compatible with the actuator safe operating range, although it was possible to increase the output further by increasing the static force load. Our results demonstrate for a first time that static force applied to the RW is crucial for sound transmission efficiency. Further we could show that RW stimulation with the DACS PI actuator is possible having a maximum output that is sufficient to treat moderate and pronounced sensorineural hearing losses (SNHL). This article is part of a Special Issue entitled "MEMRO 2012".

First clinical experiences with a direct acoustic cochlear stimulator in comparison to preoperative fitted conventional hearing aids.

OBJECTIVE: Patients with moderate-to-severe mixed hearing losses (MHLs) are hard to provide sufficient benefit with currently available conventional hearing aids. Here, the long-term safety of a direct acoustic cochlear stimulator (DACS) and the effectiveness compared with conventional "high-performance" hearing aids were investigated. STUDY DESIGN: Prospective, within patient reference, nonrandomized, interventional multicenter clinical study performed at these 3 centers: Medical University Hannover, University of Heidelberg, and Helios Hospital Krefeld. PATIENTS AND INTERVENTION: Ten otosclerosis patients with severe-to-profound MHL were preoperatively fitted with state-of-the-art conventional hearing aids (HA). After 2 months of testing conventional HA, 9 of the patients decided to be implanted with a DACS. MAIN OUTCOME MEASURES: Air conduction (AC) and bone conduction (BC) aided and unaided thresholds, speech discrimination before and after implantation and at 3, 6, and 12 months after activation. The subjective benefit was assessed by the Abbreviated Profile of Hearing Aid Benefit (APHAB). RESULTS: Preoperative hearing thresholds were preserved over the 12 month observation time after activation. Average functional gain (0.5-4 kHz) achieved with conventional HA was 47 dB compared with 56 dB with the DACS. Speech-in-noise tests revealed a lower SNR for DACS (3.1 dB) than for the HA (6.6 dB) and patients were more satisfied with the DACS. CONCLUSION: The DACS significantly improved hearing, speech intelligibility, and satisfaction in patients with a severe-to-profound mixed hearing loss and can be considered a safe and useful alternative to conventional hearing aids.