Health-related quality of life in vibrant soundbridge patients: generic and specific measures, short-term and long-term outcomes.

OBJECTIVE: The goal of the study was to determine the short- and long-term outcome of health-related quality of life (HRQoL) in adults implanted with a Vibrant Soundbridge (VSB). METHODS: Twenty-one adults (8 females, 13 males; mean age at implantation: 57 ±10 years) who received a unilateral VSB for combined or conductive hearing loss, were administered two questionnaires: the Nijmegen Cochlear Implant Questionnaire (NCIQ) as a measure of hearing-specific HRQoL, and the Health Utility Index 3 (HUI 3) as a measure of generic HRQoL. The questionnaires were administered before implantation and three, six, 12 and 24 months after processor activation. RESULTS: The NCIQ total score raised significantly from 62 points before implantation to 76 points at three months after processor activation (p < 0.005). Thereafter, no significant increases occurred anymore. The HUI 3 multi-attribute score (MAUS) increased from 0.59 before implantation to 0.70 at three months and at six months after processor activation and then declined slightly to 0.68 at 24 months after processor activation. Similar values were observed with the HUI 3 single-attribute score (SAUS) of Hearing. The increases of the HUI 3 scores were not statistically significant, but all pre-post-implantation differences were clinically relevant. DISCUSSION: VSB recipients experienced a quick improvement of their HRQoL. After just three months of device use, a significant improvement of hearing-specific HRQoL and a clinically relevant improvement of generic HRQoL were seen. After three months, no essential changes of HRQoL occurred in our sample, suggesting that the achieved level of HRQoL may remain stable in the long term.

A novel coupling quality index to estimate the coupling efficiency in Vibrant Soundbridge.

BACKGROUND: The objective-based methods for intraoperative monitoring have been suggested to assess the coupling and the outcomes of Vibrant Soundbridge (VSB). Although several techniques were proposed, they have not been widely adopted due to their complexity and invasiveness. PURPOSE: This study aimed to investigate the accuracy of a new coupling quality index using an intraoperative ABR threshold via AcoustiAP and its correlation with the perioperative measures. METHODS: This is a prospective study conducted at a tertiary center. The medical records were retrieved for all patients who underwent VSB implantation and had an intraoperative objective assessment for the coupling efficiency. AcoustiAP was used to evaluate the intraoperative ABR thresholds, which were assessed directly after the floating mass transducer (FMT) placement using acoustic CE-Chirp signals. The Vibrogram was used for the postoperative audiological evaluation. A new coupling quality index was calculated based on the intraoperative ABR thresholds. RESULTS: Ten patients were eligible for the present study. The ABR thresholds for good coupling ranged from 35 to 60 dBnHL. The loose coupling thresholds ranged considerably from 40 to 100 dBnHL. Overall, the median intraoperative ABR threshold at good coupling was 42.5 (40-60) dBnHL and 60 (40-100) dBnHL at loose coupling. The analysis showed that there was a significant change in the coupling quality index at the good and loose coupling points (24.3 ± 14 vs 38.8 ± 18.2, respectively, p < 0.001). At a cut-off value of 22.6 dB, the coupling quality index had a sensitivity of 70%  and specificity of 90% for discriminating good and loose coupling. CONCLUSION: This study provides evidence for the utility of intraoperative ABR measurements in predicting the coupling efficiency in patients with VSB. Our results showed that the coupling quality index had an acceptable accuracy in discriminating between good and poor coupling, which can help clinicians optimize the fitting process for individuals and may ultimately lead to improved patient outcomes.

An easy method to determine crucial AMEI performance parameters from clinical routine data in individuals - Part 2: dynamic range.

OBJECTIVE: The dynamic range (DR) available to the patient is a central parameter to determine speech intelligibility in quiet. DESIGN: In this retrospective study, the DR for the Vibrant Soundbridge implanted in individual patients was calculated using in situ thresholds of the patients and technical data of the implant system. The average DR across frequencies (0.5, 1, 2, 4 kHz) was correlated with the patients' assigned word recognition score (WRS) in quiet. STUDY SAMPLE: A data set of 66 cases (4 bilateral and 2 revised cases) from 60 implanted patients between 14.3-81.8 years were analysed. RESULTS: The relationship between DR and WRS was described by a sigmoidal growth function with R2=0.6371 and a maximum WRS (upper asymptote) of 93.5%. Word recognition scores in quiet improved with increasing DR. A significant shift in performance was detected from DR bin 2 (10-20 dB, median WRS 55%) to bin 3 (20-30 dB, median WRS 80%) and from DR bin 4 (30-40 dB, median WRS 82.5%) to bin 5 (40-50 dB, median WRS 90%). CONCLUSION: A minimum DR of 20 dB can yield sufficient speech intelligibility in quiet in implanted patients, however, an optimum DR is suggested to be 40 dB.

Middle Ear Implant Usage Restores Subjective Listening Effort toward Normal in Complex Acoustic Scenes.

INTRODUCTION: The amount of listening effort needed to understand speech in every-day life is an important outcome measure of the effectiveness of a hearing device. The main goal of this study was to assess subjective listening effort in patients implanted with an active middle ear implant Vibrant Soundbridge (VSB) with and without using their speech processor in complex acoustic scenarios. METHODS: Ten VSB users were measured using the adaptive categorical listening effort scaling (ACALES) method in four different acoustic scenarios, realized using a multichannel loudspeaker array. The four acoustic scenarios included both spatially simple and complex speech and noise arrangements that realistically simulated challenging every-day listening situations. Signal-to-noise ratios (SNRs) were adaptively varied during the measurement. Twelve normal-hearing (NH) listeners performed the same experiment as a control group. RESULTS: Listening effort was significantly reduced in all tested acoustic scenarios when participants used their VSB. When using the VSB, SNRs corresponding to mild-to-moderate listening effort were found not to be statistically different from SNRs found in the NH control group. SNRs corresponding to extreme listening effort of VSB users approached NH values, indicating partial restoration of listening effort. DISCUSSION AND CONCLUSIONS: Usage of the middle ear implant VSB was found to restore subjective listening effort to normal at high SNRs completely, and at lower SNRs partially. The remaining gap at low SNRs may be due to lower effectiveness of signal processing at high noise levels or due to the microphone location effect.

Hearing rehabilitation and microbial shift after middle ear surgery with Vibrant Soundbridge in patients with chronic otitis media.

INTRODUCTION: Patients with otitis media (OM) encounter significant functional hearing impairment with conductive, or a combined hearing loss and long-term sequelae involving impaired speech/language development in children, reduced academic achievement and irreversible disorders of middle and inner ear requiring a long time therapy and/or multiple surgeries. In its persistent chronic form, Otitis media (COM) can often only be treated by undergoing ear surgery for hearing restoration. The persistent inflammatory reaction plays a major role, often caused by multi-resistant pathogens in the ear. Herein, we present outcomes of patients implanted with currently the only FDA approved active Middle Ear Implant Vibrant Soundbridge (VSB), suffering from persistent COM. METHODS: The study enrolled 42 patients, treated by performing middle ear (ME) surgery to different extents and implanted with the VSB to various structures in the ME. Included were 17 children and 25 adults that had recurrent and/or persisting OM and significant hearing loss. Preoperative and postoperative patients' audiometric data were evaluated and the benefit with VSB assessed using the Glasgow Benefit Inventory for adults and pediatric cohorts. The microbial spectrum of pathogens was assessed before and after surgery, exploring the colonization of the otopathogens, as well as the intestinal microbiome from individually burdened patients. RESULTS: The mean functional gain is 29.7 dB HL (range from 10 to 56.2 dB HL) with a significant improvement in speech intelligibility in quiet. Following VSB implantation, no significant differences in coupling were observed at low complication rates. Postoperatively patients showed significantly increased benefit with VSB compared to the untreated situation, including less otorrhea, pain, medical visits, and medication intake, with no recurrent OM and significant bacterial shift in otopathogens. The analysis of the intestinal microbiome displayed a high abundance of bacterial strains that might be linked to chronic and persistent inflammation. CONCLUSIONS: Functional ear surgery including rehabilitation with a VSB in patients suffering from COM present to be safe and effective. The successful acceptance accompanied by the improved audiological performance resulted in significant benefit with VSB, with a shift in the ear pathogens and altered microbiome and thus is a great opportunity to be treated.

In-vivo characterisation of an implanted microphone and totally implantable active middle ear implant.

OBJECTIVE: To objectively evaluate acoustic sensitivity of the implanted microphone, and maximum stable gain of a totally implantable active middle ear implant. DESIGN: Prospective, single centre evaluation. STUDY SAMPLE: Fourteen adult patients. RESULTS: Microphone sensitivity is approx. 10 dB lower than an externally worn conventional hearing aid, at frequencies up to 4000 Hz, and substantially lower at higher frequencies. The masking level due to microphone noise, which determines the softest test tones that can be detected, is estimated at <20 to <30 dB HL up to 1000 Hz, and <40 dB HL at higher frequencies. Maximum stable effective gain is the maximum amplification achievable without causing feedback whistling. In sensorineural hearing loss (SNHL) cases, it is 30-40 dB at frequencies up to 2000 Hz, allowing to compensate for even the maximum recommended hearing loss (60-70 dB HL). In both SNHL and mixed hearing loss (MHL) cases, maximum stable effective gain is lower (+20 to -30 dB) around 3000-6000 Hz. CONCLUSIONS: Microphone sensitivity is high enough to achieve aided thresholds of 20-40 dB HL. A strong correlation between actuator coupling efficiency and maximum stable effective gain implies that any effort to improve actuator efficiency should also increase the available gain.

Functional results with active middle ear implant or semi-implantable bone conduction device in patients with comparable hearing loss.

OBJECTIVE: In patients with conductive (CHL) or mixed hearing loss (MHL), hearing rehabilitation with an implantable hearing system, active middle ear implant (AMEI) or a semi-implantable bone-conduction device (SIBCD), is an option when conventional hearing aids are insufficient, or patients are unable to wear them. DESIGN: Retrospective analysis of 20 consecutive patients (24 implants) with a comparison of demographic characteristics and audiometric results (air-bone gap = ABG, effective hearing gain = EHG, functional hearing gain = FHG, Freiburg Monosyllabic Test in quiet, Oldenburg Sentence Test in noise = OLSA). STUDY SAMPLE: Patients, eligible for both devices, who received either AMEI or SIBCD due to CHL or MHL. RESULTS: Analysis showed no significant differences in post-operative functional hearing results between the group of AMEI vs. SIBCD (ABG-reduction: 31.6 ± 12.4 dB HL vs. 28.0 ± 11.8 dB HL; p = 0.702; EHG: -1.6 ± 7.7 dB HL vs. -1.2 ± 4.2 dB HL; p = 0.090; FHG: 33.4 ± 12.6 dB HL vs. 26.1 ± 11.7 dB HL; p = 0.192; Freiburg: 83.0 ± 15.6% vs. 83.6 ± 14.2%; Freiburg-improvement: 57.7 ± 26.8% vs. 68.2 ± 19.7%; p = 0.294; OLSA: -2.7 ± 3.0 SNR vs. -1.4 ± 3.6 SNR; OLSA-improvement: 2.6 ± 2.1 dB vs. 3.7 ± 2.8 dB; p = 0.323). Four patients had the AMEI explanted due to insufficient functioning and later received a SIBCD. CONCLUSIONS: Due to more challenging anatomical conditions, a surgical technique for the AMEI is more complex. However, functional results are comparable to the SIBCD. Therefore, proper patient counselling and cautious choice of the device are mandated before surgery.

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 retrospective European multicenter analysis of the functional outcomes after active middle ear implant surgery using the third generation vibroplasty couplers.

PURPOSE: To evaluate the safety and performance of three novel vibroplasty couplers that allow attachment of the floating mass transducer of a transcutaneous active middle ear implant (AMEI) to the round window (RW) membrane, the long process (LP), or the incus body and the short process (SP) of the incus. METHODS: Retrospective multicenter cohort study of 25 AMEI users with sensorineural or mixed hearing loss that were among the first implanted with an AMEI vibrating ossicular prosthesis in combination with the third generation of vibroplasty couplers between 2014 and 2016. Main Outcome Measures were bone-conduction pure-tone and vibroplasty thresholds, postoperative aided sound field thresholds and postoperative aided word recognition score (WRS). RESULTS: Bone conduction threshold changes of more than 10 dB in 4PTABC were observed in two subjects. A mean improvement of 57.8% in speech recognition was observed with a mean WRS at 65 dB SPL improving from 14.8% (SD 21.9%) preoperatively to a mean aided score of 72.6% (SD 18.6%). Sound field thresholds improved from an average 4PTASF of 64.1 dB HL (SD 9.8 dB HL) to 37.0 dB HL (SD 8.9 dB HL), resulting in a mean functional gain of 27.1 dB. There was no significant difference in WRS or functional gain between the coupler types. CONCLUSION: Initial experience shows that all three third generation vibroplasty couplers represent safe and efficient attachment options for the FMT allowing the surgeon to choose the coupling type based on the present pathology.

Revision of active middle ear implants (AMEI): causes, surgical issues and rehabilitative transition at a single implanting center.

PURPOSE: To report on failures related to active middle ear implants (AMEI) surgery, within a series of subjects treated at a single Implanting Center. METHODS: A retrospective review of 79 cases of implanted AMEI has been performed to report the failure ratio, the causes for the failure and the selected rehabilitative solution. The AMEI included 25 Vibrant Soundbridge® (Medel, Innsbruck, Austria), 20 as round window vibroplasty (RW-VSB) for mixed hearing loss, 5 as incus-vibroplasty for sensorineural hearing loss; 7 MET/Carina® (Cochlear, Melbourne, Australia), 2 MET for mixed and sensorineural hearing loss, 5 Carina for sensorineural hearing loss; 43 Esteem® (EnvoyMedical, St Paul, USA) for sensorineural hearing loss; 3 Maxum® (Ototronics, Texas, USA) for sensorineural hearing loss; 1 Codacs® (Cochlear, Melbourne, Australia) for severe mixed hearing loss. RESULTS: The overall complication rate affected 20% of the implanted devices, individually ranging from 6.9 to 100%. Hardware system failures were recorded in all the AMEI, ranging from 10 to 50%. The alternative auditory rehabilitation included replacement of the same system in 2 cases, use of a conventional hearing aid in 3 cases, Cochlear implantation in 4 cases and implantation in the contralateral ear in 2 cases. CONCLUSION: The present clinical experience showed that, in spite of the successful functional rate displayed by the majority of the AMEI implantees, complications may occur to a certain percentage of cases and should prompt the professionals to select alternative solutions, starting from the (re)adoption of a conventional hearing aid and ending up to Cochlear implantation.

Hearing Aid Treatment for Patients with Mixed Hearing Loss. Part II: Speech Recognition in Comparison to Direct Acoustic Cochlear Stimulation.

BACKGROUND: The conventional therapy for severe mixed hearing loss is middle ear surgery combined with a power hearing aid. However, a substantial group of patients with severe mixed hearing loss cannot be treated adequately with today's state-of-the-art (SOTA) power hearing aids, as predicted by the accompanying part I of this publication, where we compared the available maximum power output (MPO) and gain from technical specifications to requirements for optimum benefit using a common fitting rule. Here, we intended to validate the theoretical assumptions from part I experimentally in a mixed hearing loss cohort fitted with SOTA power hearing aids. Additionally, we compared the results with an implantable hearing device that circumvents the impaired middle ear, directly stimulating the cochlea, as this might be a better option. OBJECTIVES: Speech recognition outcomes obtained from patients with severe mixed hearing loss supplied acutely with a SOTA hearing aid were studied to validate the outcome predictions as described in part I. Further, the results obtained with hearing aids were compared to those in direct acoustic cochlear implant (DACI) users. MATERIALS AND METHODS: Twenty patients (37 ears with mixed hearing loss) were provided and fitted with a SOTA power hearing aid. Before and after an acclimatization period of at least 4 weeks, word recognition scores (WRS) in quiet and in noise were studied, as well as the speech reception threshold in noise (SRT). The outcomes were compared retrospectively to a second group of 45 patients (47 ears) using the DACI device. Based on the severity of the mixed hearing loss and the available gain and MPO of the SOTA hearing aid, the hearing aid and DACI users were subdivided into groups with prediction of sufficient, partially insufficient, or very insufficient hearing aid performance. RESULTS: The patients with predicted adequate SOTA hearing aid performance indeed showed the best WRS in quiet and in noise when compared to patients with predicted inferior outcomes. Insufficient hearing aid performance at one or more frequencies led to a gradual decrease in hearing aid benefit, validating the criteria used here and in the accompanying paper. All DACI patients showed outcomes at the same level as the adequate hearing aid performance group, being significantly better than those of the groups with inadequate hearing aid performance. Whereas WRS in quiet and noise were sensitive to insufficient gain or output, showing significant differences between the SOTA hearing aid and DACI groups, the SRT in noise was less sensitive. CONCLUSIONS: Limitations of outcomes in mixed hearing loss individuals due to insufficient hearing aid performance can be accurately predicted by applying a commonly used fitting rule and the 35-dB dynamic range rule on the hearing aid specifications. Evidently, when outcomes in patients with mixed hearing loss using the most powerful hearing aids are insufficient, bypassing the middle ear with a powerful active middle ear implant or direct acoustic implant can be a promising alternative treatment.

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.

Three-year audiological outcomes of the latest generation middle ear transducer (MET) implant.

PURPOSE: To evaluate the long-term audiological outcomes and safety of the latest generation of middle ear transducer (MET) among a group of Polish patients. METHODS: Ten patients aged 48-72 years with bilateral sensorineural hearing loss (n = 8) and mixed hearing loss (n = 2) were included in this study. Pure tone audiometry, sound thresholds, word recognition scores in quiet and speech reception thresholds in noise were assessed. Medical and technical complication information was gathered. RESULTS: All the patients underwent unilateral implantation with the latest generation Cochlear MET between 2014 and 2016. Mean length of follow-up was 3.7 years. Compared to the unaided condition, the implant provided significant functional gain (mean M = 26.1 dB) at 12 months follow-up. Compared to before surgery, average word recognition in quiet at 65 dB and at 80 dB SPL, as well as speech reception threshold in noise, were significantly better at 12 months. However, postoperative air conduction thresholds 6 months after implantation worsened by 10.3 dB (standard deviation SD = 5.8 dB). Postoperatively, three patients had skin problems around the processor, and one of them completely resigned from using the device 5 months after activation. Technical failures occurred in 4 cases. There were 9 out of 10 patients who still used the MET, but only 5 of them used the processor regularly (every day). CONCLUSION: Despite changes in the transducer implemented by the manufacturer, we observed a significant number of adverse events in users of the latest generation of MET.

Intraoperative determination of coupling efficiency of Carina® middle ear implant by means of auditory evoked potentials.

OBJECTIVE: The Carina® implant system is a fully implantable active middle ear implant, which can be coupled to various structures in the middle ear, depending on the nature of the hearing loss and the middle ear anatomy. Currently, there is only one method for determining the coupling efficiency of the actuator of this implant system, and this is limited to incus coupling. DESIGN: The proposed method is based on the intraoperative recording and evaluation of auditory brainstem responses (ABRs) while directly stimulating the hearing system via the actuator. The acoustic stimulation was achieved using an optimised broadband chirp stimulus (CE-Chirp®). STUDY SAMPLES: This study included 10 subjects having moderate to severe sensorineural or mixed hearing loss. RESULTS: The intraoperative ABR measurements show, that it is possible to derive reliable AEP thresholds via the actuator of the implant. The ABR thresholds correlate well with preoperative BC PTA4 thresholds (r = 0.87) while the postoperative OC-direct thresholds (in situ audiogram via the implant) correlate with r = 0.77. CONCLUSION: The results demonstrated that the direct actuator stimulation allow for reliable intraoperative ABR measurements and that the proposed method can be used to estimate the coupling efficiency of the actuator and facilitate its positioning.

Complications after round window vibroplasty.

PURPOSE: To evaluate the complication rate in adult subjects with open cavities that were implanted with the Vibrant Soundbridge implant, using the round window (RW) vibroplasty procedure. METHODS: From 2009 to 2014, 21 adult subjects with mixed hearing loss, all with sequel from open tympanoplasty surgery, underwent RW vibroplasty (RW-VPL). Surgical complications were recorded and a standard minimal approach was used as a basis for all the cases that needed revision. RESULTS: The mean follow-up was 42 months (range 12-76). Complications occurred in nearly half of the cases and included: cable extrusion (23.8%), hardware failure (14.3%), profound hearing loss (9.5%), and inadequate RW coupling (9.5%). A minimal endaural approach (MEA) was used in the majority of the cases (86.7%), while the extended endaural approach was adopted for those patients requiring explantation with or without replacement (14.3%). CONCLUSIONS: RW-VPL can be considered a possible option for the rehabilitation of auditory impairment derived from an open tympanoplasty procedure due to cholesteatoma. The procedure may lead to minor/major complications that may require a surgical revision. By adopting an MEA, it has been possible to manage all the situations in which functionality of the device is worth being preserved.

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.

Influence of backside loading on the floating mass transducer: An in vitro experimental study.

HYPOTHESIS: The vibration of the floating mass transducer (FMT) of a single active middle-ear implant (AMEI) is distinctly influenced by the properties of the material coupled to its back side. BACKGROUND: In round window vibroplasty, the FMT needs to be padded against the surrounding bone opposite from the round window membrane. This represents one factor influencing its performance as a round window driver. Therefore, we examined the effects of different materials linked to the back side of an FMT on its vibration range. METHODS: The back side of an FMT was glued to a silicone cylinder 1.0 mm in diameter and 1.0 mm - 1.5 mm in length and of 40A, 50A or 70A Shore hardness; to cartilage of equivalent size; or to a round window soft coupler (RWSC), all firmly fixed on a steel plate. The vibrations were determined by a laser Doppler vibrometer (LDV) measuring the velocity of the centre point on the front side of the FMT. RESULTS: The materials on the back side of the FMT significantly influenced the vibration range of the FMT. The RWSC and silicone of 40A Shore hardness allowed for the highest detected velocities, while cartilage led to a distinct reduction similarly to 70A silicone. CONCLUSION: The coupling on the back side of an FMT distinctly affects its vibration range. In this regard, the RWSC and silicone of 40A Shore hardness yield the least impairment of vibration. Thus, the RWSC may be a feasible option in round window vibroplasty when additionally connected to the FMT opposite from the round window membrane.

Mastoidectomy dimensions for direct acoustic cochlear implantation: a human cadaveric temporal bone study.

The objective of the present paper was to acquire information about the mastoidectomy size necessary to obtain an optimal placement of the direct acoustic cochlear implant actuator and fixation system. Ten human cadaveric temporal bones were dissected and implanted with direct acoustic cochlear implant. Mastoidectomy size was determined after implantation in each temporal bone. A bone bed for the receiver/stimulator, mastoidectomy and a large posterior tympanotomy were drilled out. The mastoidectomy was progressively enlarged posteriorly in small steps until the actuator template was judged adequately oriented to enable passage of the rod through the posterior tympanotomy without any contact with the bony walls. The distance between different landmarks in the mastoidectomy was measured. All measured values showed a high degree of consistency, with limited median absolute deviation values. One of the most critical measure, i.e. the distance between the posterior margin of the mastoidectomy to the superior rim of the bony external ear canal wall, ranged from 13 to 16 mm with a median value of 15 mm. Prior knowledge of the ideal size of the mastoidectomy for direct acoustic cochlear implant facilitates the positioning of the fixation system and may save time during implant surgery.

Device optimised chirp stimulus for ABR measurements with an active middle ear implant.

OBJECTIVE: Active middle ear implants are widely used to treat adults and children with sensorineural, conductive, or mixed hearing loss. Currently, there is no adequate method to determine the performance of active middle ear implant systems. DESIGN: The proposed method is based on measuring the auditory brainstem response while stimulating the hearing system via the active middle ear implant (Vibrant SoundbridgeTM, VSB; MEDEL, Austria). The acoustic stimulation was achieved via an optimised chirp stimulus (CE-Chirp), implemented in the Eclipse system (Interacoustics, Denmark). To compensate for the frequency-specific delays in the VSB system, the underlying model function of the CE-Chirp was adjusted accordingly (VSB-CE-Chirp). Study samples: The study includes 12 subjects having mild to profound sensorineural, conductive or mixed hearing loss. RESULTS: The use of an optimised VSB-CE-Chirp instead of the CE-Chirp increases significantly the ABR wave V amplitudes (1.63 times) and so also increases their identifiability (by 15.2%). On average, wave V could be identified at a 7.5 dB lower stimulation level. CONCLUSION: The constructed VSB-CE-Chirp stimulus, after it had been transmitted through the VSB system, follows well the shape of the original CE-Chirp. Preliminary measurements in VSB patients demonstrated a significantly improved ABR amplitude with the VSB-CE-Chirp.

Acoustic stimulation of the human round window by laser-induced nonlinear optoacoustics.

The feasibility of low frequency pure tone generation in the inner ear by laser-induced nonlinear optoacoustic effect at the round window was demonstrated in three human cadaveric temporal bones (TB) using an integral pulse density modulation (IPDM). Nanosecond laser pulses with a wavelength in the near-infrared (NIR) region were delivered to the round window niche by an optical fiber with two spherical lenses glued to the end and a viscous gel at the site of the laser focus. Using IPDM, acoustic tones with frequencies between 20 Hz and 1 kHz were generated in the inner ear. The sound pressures in scala tympani and vestibuli were recorded and the intracochlear pressure difference (ICPD) was used to calculate the equivalent sound pressure level (eq. dB SPL) as an equivalent for perceived loudness. The results demonstrate that the optoacoustic effect produced sound pressure levels ranging from 140 eq. dB SPL at low frequencies ≤ 200 Hz to 90 eq. dB SPL at 1 kHz. Therefore, the produced sound pressure level is potentially sufficient for patients requiring acoustic low frequency stimulation. Hence, the presented method offers a potentially viable solution in the future to provide the acoustic stimulus component in combined electro-acoustic stimulation with a cochlear implant.