New developments in bone-conduction hearing implants: a review

The effect of percutaneous and transcutaneous BAHA on hearing and subjective auditory abilities: A comparative study

Hearing loss significantly affects communication, social interactions, and the overall quality of life. The bone-anchored hearing aid (BAHA) is an implantable system that bypasses the outer and middle ear to directly stimulate the cochlea through bone conduction. This study aimed to compare hearing performance and subjective auditory ability improvements between transcutaneous and percutaneous BAHA devices using audiological assessments and Speech, Spatial and Qualities of Hearing Scale. This cross-sectional prospective study included 29 participants aged 14 to 69 years who had used BAHA for at least 6 months. Both Cochlear Baha System's percutaneous (connect) and transcutaneous (attract) implants were evaluated. Audiological assessments involved pure-tone audiometry, speech recognition threshold, and free-field (FF) audiometry, while subjective auditory ability was measured using the Turkish Speech, Spatial and Qualities of Hearing scale (Tr-SSQ). Significant improvements in FF audiometry averages and speech recognition thresholds were observed with BAHA compared to without BAHA (P < .001). Both implant types provided similar FF averages, speech audiometry results, and Tr-SSQ outcomes, with no significant differences between them. Tr-SSQ scores showed substantial satisfaction, indicating significant improvements in speech perception, spatial perception, and hearing quality with BAHA (P < .001). The findings align with previous research, demonstrating that BAHA is a reliable and effective solution for hearing rehabilitation. The study also emphasized the importance of using both audiological test results and daily hearing function scales to comprehensively evaluate the benefits of hearing rehabilitation in real-world environments. In conclusion, BAHA, regardless of the implant type, can provide predictable and lasting improvements in hearing thresholds and daily hearing abilities, making it a valuable option for patients with conductive hearing loss.

Foundational Engineering of Artificial Blood Vessels' Biomechanics: The Impact of Wavy Geometric Designs

The design of wavy structures and their mechanical implications on artificial blood vessels (ABVs) have been insufficiently studied in the existing literature. This research aims to explore the influence of various wavy geometric designs on the mechanical properties of ABVs and to establish a foundational framework for advancing and applying these designs. Computer-aided design (CAD) and finite element method (FEM) simulations, in conjunction with physical sample testing, were utilized. A geometric model incorporating concave and convex curves was developed and analyzed with a symbolic mathematical tool. Subsequently, a total of ten CAD models were subjected to increasing internal pressures using a FEM simulation to evaluate the expansion of internal areas. Additionally, physical experiments were conducted further to investigate the expansion of ABV samples under pressure. The results demonstrated that increased wave numbers significantly enhance the flexibility of ABVs. Samples with 22 waves exhibited a 45% larger area under 24 kPa pressure than those with simple circles. However, the increased number of waves also led to undesirable high-pressure gradients at elevated pressures. Furthermore, a strong correlation was observed between the experimental outcomes and the simulation results, with a notably low error margin, ranging from 19.88% to 3.84%. Incorporating wavy designs into ABVs can effectively increase both vessel flexibility and the internal area under pressure. Finally, it was found that expansion depending on the wave number can be efficiently modeled with a simple linear equation, which could be utilized in future designs.

[Nonsurgical attachment possibilities for bone conduction hearing aids : Comparison of coupling using external pressure versus an adhesive plate]

BACKGROUND

Bone conduction hearing systems are used for patients with conductive or combined hearing loss who cannot be adequately treated with air conduction hearing aids or surgery. These hearing systems can be surgically implanted or reversibly attached using bone conduction eyeglasses or a rigid or soft headband. A nonsurgical and pressure-free alternative is fixation via an adhesive plate.

OBJECTIVE

The aim of this study was to compare the energy transferred from the hearing aid to the mastoid when attached via a new adhesive plate versus via a soft headband. In addition, the comfort and the durability of the adhesive plate was evaluated.

MATERIALS AND METHODS

A total of 30 subjects were tested. The transferred energy was measured by accelerometer, which recorded the sound energy at the maxillary teeth. Wearing comfort, fixation duration (until plate becomes loose), and the skin reaction were examined using a questionnaire after the subjects had worn the adhesive plate with and without hearing aid for a maximum of 7 days. The skin reaction was also assessed clinically.

RESULTS

There was a significant difference in the transferred energy in favor of the soft headband at 0.5, 1, and 2 kHz. On the other hand, there was a high level of satisfaction and acceptance regarding the aesthetics and the wearing time of the adhesive plate, without skin irritations.

CONCLUSION

The difference in the transferred energy up to 2 kHz is probably due to the lack of pressure from the adhesive plate. This could possibly be compensated after appropriate adjustment of the speech processor. Based on the positive properties of the adhesive plate in terms of comfort, it could be used as an alternative to the soft headband.

Active Bone Conduction Implant and Adhesive Bone Conduction Device: A Comparison of Audiological Performance and Subjective Satisfaction

Introduction  Atresia of the external auditory canal affects 1 in every 10 thousand to 20 thousand live births, with a much higher prevalence in Latin America, at 5 to 21 out of every 10 thousand newborns. The treatment involves esthetic and functional aspects. Regarding the functional treatment, there are surgical and nonsurgical alternatives like spectacle frames and rigid and softband systems. Active transcutaneous bone conduction implants (BCIs) achieve good sound transmission and directly stimulate the bone. Objective  To assess the audiological performance and subjective satisfaction of children implanted with an active transcutaneous BCI for more than one year and to compare the outcomes with a nonsurgical adhesive bone conduction device (aBCD) in the same users. Methods  The present is a prospective, multicentric study. The audiological performance was evaluated at 1, 6, and 12 months postactivation, and after a 1-month trial with the nonsurgical device. Results  Ten patients completed all tests. The 4-frequency pure-tone average (4PTA) in the unaided condition was of 65 dB HL, which improved significantly to 20 dB HL after using the BCI for 12 months. The speech recognition in quiet in the unaided condition was of 33% on average, which improved significantly, to 99% with the BCI, and to 91% with the aBCD. Conclusion  The aBCD demonstrated sufficient hearing improvement and subjective satisfaction; thus, it is a good solution for hearing rehabilitation if surgery is not desired or not possible. If surgery is an option, the BCI is the superior device in terms of hearing outcomes, particularly background noise and subjective satisfaction.

Towards sensory substitution and augmentation: Mapping visual distance to audio and tactile frequency

Multimodal perception is the predominant means by which individuals experience and interact with the world. However, sensory dysfunction or loss can significantly impede this process. In such cases, cross-modality research offers valuable insight into how we can compensate for these sensory deficits through sensory substitution. Although sight and hearing are both used to estimate the distance to an object (e.g., by visual size and sound volume) and the perception of distance is an important element in navigation and guidance, it is not widely studied in cross-modal research. We investigate the relationship between audio and vibrotactile frequencies (in the ranges 47-2,764 Hz and 10-99 Hz, respectively) and distances uniformly distributed in the range 1-12 m. In our experiments participants mapped the distance (represented by an image of a model at that distance) to a frequency via adjusting a virtual tuning knob. The results revealed that the majority (more than 76%) of participants demonstrated a strong negative monotonic relationship between frequency and distance, across both vibrotactile (represented by a natural log function) and auditory domains (represented by an exponential function). However, a subgroup of participants showed the opposite positive linear relationship between frequency and distance. The strong cross-modal sensory correlation could contribute to the development of assistive robotic technologies and devices to augment human perception. This work provides the fundamental foundation for future assisted HRI applications where a mapping between distance and frequency is needed, for example for people with vision or hearing loss, drivers with loss of focus or response delay, doctors undertaking teleoperation surgery, and users in augmented reality (AR) or virtual reality (VR) environments.

Development and validation of a surgical planning tool for bone-conduction implants

Background

The BONEBRIDGE® (Med-El GmbH) is a bone-conduction device comprising an external audio processor and an internal Bone Conduction-Floating Mass Transducer (BC-FMT) surgically anchored to the temporal bone. Due to the implant's size, its placement may be challenging in certain anatomies, necessitating thorough surgical planning. Manual planning methods are laborious, time-intensive, and prone to errors. This study aimed to develop and validate an automated algorithm for determining skull thickness, aiding in the surgical planning of the BONEBRIDGE and other devices requiring similar bone thickness estimations.

Materials and methods

Twelve cadaveric temporal bones underwent clinical computed tomography (CT). A custom Python algorithm was developed to automatically segment bone from soft tissue, generate 3D models, and perform ray-tracing to estimate bone thickness. Two thickness colormaps were generated for each sample: the cortical thickness to the first air cell and the total thickness down to the dura. The algorithm was validated against expert manual measurements to achieve consensus interpretation.

Results

The algorithm estimated bone-to-air thicknesses (mean = 4.7 mm, 95% Confidence Interval [CI] of 4.3-5.0 mm) that closely matched the expert measurements (mean = 4.7 mm, CI of 4.4-5.0 mm), with a mean absolute difference (MAD) of 0.3 mm. Similarly, the algorithm's estimations to the dura (6.0 mm, CI of 5.4-6.5 mm) were comparable to the expert markings (5.9 mm, CI of 5.4-6.5 mm), with a MAD of 0.3 mm.

Conclusions

The first automated algorithm to calculate skull thickness to both the air cells and dura in the temporal bone was developed. Colormaps were optimized to aid with the surgical planning of BONEBRIDGE implantation, however the tool can be generalized to aid in the surgical planning of any bone thickness application. The tool was published as a freely available extension to the open-source 3D Slicer software program (www.slicer.org).

Outcomes and device use in children with bone-conduction hearing devices in South Africa

BACKGROUND

 Bone-conduction hearing devices (BCHD) can provide hearing solutions in settings where middle ear pathology is rife.

OBJECTIVES

 Describe functional hearing outcomes and device use of children fitted with BCHD.

METHOD

 Retrospective review of 79 children fitted with BCHD between January 2017 and May 2022. Outcomes included device use and subjective reports measured with the Parents' Evaluation of Aural/Oral Performance of Children (PEACH) and the Teachers' Evaluation of Aural/Oral Performance of Children (TEACH). Analysis of variance established association between mean data logging and type and degree of hearing loss. Thematic analyses were done for qualitative outcomes.

RESULTS

 Average usage was 7.0 h/day (5.4 SD; range 0.1-24). PEACH ratings indicated 93.3% of children wore their BCHD 'always' or 'often', with 80% displaying Typical auditory performance at 1-month follow-up. TEACH ratings indicated 84.2% of children wore their BCHD 'always' or 'often', with 78.9% showing typical auditory behaviour. Increased usage was noted for conductive, mixed, moderate and severe hearing losses. There was a mean delay of 17.2 months (23.4 SD; range 0-90) between age of diagnosis and fitting. Thematic analyses identified two main themes: advantages and barriers to BCDH use.

CONCLUSION

 Average device use fell short of the internationally recommended 10 h/day. Higher BCHD use was associated with higher functional listening performance scores. Long waiting times for medical or surgical intervention for conductive hearing losses can delay BCHD fitting.Contribution: Limited information is available to examine outcomes in children fitted with BCHD.

The Relationship Between Auditory Performances and Satisfaction of Unilateral Bone-Anchored Hearing in Conductive and Mixed Hearing Loss

BACKGROUND

The aim of this study is to investigate the deviced and non-deviced auditory performance results of patients with unilateral bone-anchored hearing aid.

METHODS

Deviced and non-deviced free field hearing thresholds, speech discrimination, and sentence discrimination scores were evaluated. Shortened profile of the benefit from the hearing instrument (Abbreviated Profile of Hearing Aid Benefit) was used.

RESULTS

A total of 17 patients participated in the study. The mean age was 37.9 ± 17.1 years. There was a statistically significant difference between the Abbreviated Profile of Hearing Aid Benefit satisfaction questionnaire and total scores, Background Noise (BN), Reverberation (RV) subscales according to device status (P -lt; .05). No significant difference was found between the Abbreviated Profile of Hearing Aid Benefit total score result of the group divided by the hearing aid threshold (P -gt; .05). No significant difference was found between the Abbreviated Profile of Hearing Aid Benefit total score result of the group divided by the threshold without a hearing aid (P -gt; .05).

CONCLUSION

Bone-implanted hearing aids are effective and reliable amplification methods in patients with conductive and mixed hearing loss. Positive results of patient satisfaction and evaluation inventories were obtained from this study.

Hearing rehabilitation with Baha® transcutaneous and percutaneous systems

PURPOSE

Longitudinally verify the influence of auditory tonal thresholds obtained with transcutaneous and percutaneous bone-anchored hearing aids on speech perception in individuals with external and/or middle ear malformation and chronic otitis media.

METHODS

Observational, retrospective, longitudinal follow-up study of 30 unilateral users of the transcutaneous and percutaneous Baha® system for the collection of secondary data on pure tone thresholds obtained through free field audiometry and sentence recognition threshold in silence and noise in conditions: without the prosthesis; at the time of activation; in the first month of use (post 1); and in the third month (post 2).

RESULTS

There was a significant difference between pure tone thresholds obtained at frequencies of 3 and 4kHz with better results for the percutaneous technique at all evaluation moments. For both systems, better performance was observed in sentence recognition in silence and in noise, with a significant difference in activation (p<0.001), but it remained stable during the other evaluation moments. The percutaneous system showed better benefit in recognizing sentences in noise only on activation (p=0.036), when compared to the transcutaneous system.

CONCLUSION

The percutaneous system provided better audibility for high frequencies; however, such audibility did not influence sentence recognition in the silent situation for both systems. For the noise situation, better responses were observed in the percutaneous system, however, the difference was not maintained over time.

Surgical and audiological outcomes with a new transcutaneous bone conduction device with reduced transducer thickness in children

PURPOSE

Due to smaller bone thickness, young children with conductive or mixed hearing loss or single-sided deafness were previously most commonly treated with a percutaneous osseointegrated bone-anchored hearing aid (BAHA) or an active middle-ear implant. While the BAHA increases the risk of implant infections, skin infection, overgrowth of the screw or involvement of the implant in head trauma, middle-ear implant surgery involves manipulation of the ossicles with possible risk of surgical trauma. These complications can be omitted with transcutaneous bone conduction implant systems like the MED-EL Bonebridge system. The purpose of this study was to analyze whether the second generation of the Bonebridge (BCI 602) that features a decreased implant thickness with a reduced surgical drilling depth can be implanted safely in young children with good postoperative hearing performance.

METHODS

In this study, 14 patients under 12 years were implanted with the second generation of the Bonebridge. Preoperative workup comprised a CT scan, an MRI scan, pure tone audiometry, or alternatively a BERA (bone conduction, air conduction). Since children under 12 years often have a lower bone thickness, the CT was performed to determine the suitability of the temporal bone for optimal implant placement using the Otoplan software.

RESULTS

All patients (including three under the age of five) were successfully implanted and showed a good postoperative hearing performance.

CONCLUSION

With adequate preoperative workup, this device can be safely implanted in children and even children under 5 years of age and allows for an extension of indication criteria toward younger children.

Lumped element models of sound conduction in the human ear: A systematic review

Lumped element models facilitate investigating the fundamental mechanisms of human ear sound conduction. This systematic review aims to guide researchers to the optimal model for the investigated parameters. For this purpose, the literature was reviewed up to 12 July 2023, according to the PRISMA guidelines. Seven models are included via database searching, and another 19 via cross-referencing. The quality of the models is assessed by comparing the predicted middle ear transfer function, the tympanic membrane impedance, the energy reflectance, and the intracochlear pressures (ICPs) (scala vestibuli, scala tympani, and differential) with experimental data. Regarding air conduction (AC), the models characterize the pathway from the outer to the inner ear and accurately predict all six aforementioned parameters. This contrasts with the few existing bone conduction (BC) models that simulate only a part of the ear. In addition, these models excel at predicting one observable parameter, namely, ICP. Thus, a model that simulates BC from the coupling site to the inner ear is still lacking and would increase insights into the human ear sound conduction. Last, this review provides insights and recommendations to determine the appropriate model for AC and BC implants, which is highly relevant for future clinical applications.

A Systematic Review of the Audiological Efficacy of Cartilage Conduction Hearing Aids and the Factors Influencing Their Clinical Application

This systematic review evaluates the efficacy and benefit of cartilage conduction hearing aids (CC-HAs) and that factors that influence purchasing decisions. The hearing thresholds and functional gain following CC-HA wear were synthesised. A one-way analysis of variance compared the differences in the hearing thresholds and functional gain at individual frequencies and in patients with a variety of pathological changes. The synchronised aided hearing threshold and functional gain at 2.0 kHz were significantly better than at 0.5, 1.0, and 4.0 kHz. There was no significant difference in the synchronised unaided hearing thresholds across individual frequencies between 0.5 and 4.0 kHz. The synchronised functional gain in patients with atresia was significantly greater than in patients with aural atresia or stenosis and middle ear pathologies with normal ear canals. The acceptability of CC-HAs in terms of purchase decision is influenced by the condition of the external auditory meatus and severity of hearing loss, with the highest purchase rate seen in patients with aural atresia or stenosis. CC-HAs' fitting procedure advantages and cosmetic considerations make these devices a viable and preferred choice for individuals with microtia and aural atresia. Additional research to evaluate the benefits towards emotional well-being is crucial to gain insights into the psychological impact of CC-HA use.

A pilot study on spatial hearing in children with congenital unilateral aural atresia

Despite normal hearing in one ear, individuals with congenital unilateral aural atresia may perceive difficulties in everyday listening conditions typically containing multiple sound sources. While previous work shows that intervention with bone conduction devices may aid spatial hearing for some children, testing conditions are often arranged to maximize any benefit and are not very similar to daily life. The benefit from amplification on spatial tasks has been found to vary between individuals, for reasons not entirely clear. This study has sought to expand on the limited knowledge on how children with unilateral aural atresia recognize speech masked by competing speech, and how horizontal sound localization accuracy is affected by the degree of unilateral hearing loss and by amplification using unilateral bone conduction devices when fitted before 3 years of age. In a within-subject, repeated measures design, including 11 children (mean age = 7.9 years), bone conduction hearing device (BCD) amplification did not negatively affect horizontal sound localization accuracy. The effect on speech recognition scores showed greater inter-individual variability. No benefit from amplification on a group level was found. There was no association between age at fitting and the benefit of the BCD. For children with poor unaided sound localization accuracy, there was a greater BCD benefit. Unaided localization accuracy increased as a function of decreasing hearing thresholds in the atretic ear. While it is possible that low sound levels in the atretic ear provided access to interaural localization cues for the children with the lowest hearing thresholds, the association has to be further investigated in a larger sample of children.

Exceptional Speech Recognition Outcomes After Cochlear Implantation: Lessons From Two Case Studies

PURPOSE

Individual differences and variability in outcomes following cochlear implantation (CI) in patients with hearing loss remain significant unresolved clinical problems. Case reports of specific individuals allow for detailed examination of the information processing mechanisms underlying variability in outcomes. Two adults who displayed exceptionally good postoperative CI outcomes shortly after activation were administered a novel battery of auditory, speech recognition, and neurocognitive processing tests.

METHOD

A case study of two adult CI recipients with postlingually acquired hearing loss who displayed excellent postoperative speech recognition scores within 3 months of initial activation. Preoperative City University of New York sentence testing and a postoperative battery of sensitive speech recognition tests were combined with auditory and visual neurocognitive information processing tests to uncover their strengths, weaknesses, and milestones.

RESULTS

Preactivation CUNY auditory-only (A) scores were < 5% correct while the auditory + visual (A + V) scores were > 74%. Acoustically with their CIs, both participants' scores on speech recognition, environmental sound identification and speech in noise tests exceeded average CI users scores by 1-2 standard deviations. On nonacoustic visual measures of language and neurocognitive functioning, both participants achieved above average scores compared with normal hearing adults in vocabulary knowledge, rapid phonological coding of visually presented words and nonwords, verbal working memory, and executive functioning.

CONCLUSIONS

Measures of multisensory (A + V) speech recognition and visual neurocognitive functioning were associated with excellent speech recognition outcomes in two postlingual adult CI recipients. These neurocognitive information processing domains may underlie the exceptional speech recognition performance of these two patients and offer new directions for research explaining variability in postimplant outcomes. Results further suggest that current clinical outcome measures should be expanded beyond the conventional speech recognition measures to include more sensitive robust tests of speech recognition as well as neurocognitive measures of working memory, vocabulary, lexical access, and executive functioning.

The Hannover Coupler V2: Audiological outcomes of a round window coupler for the Vibrant Soundbridge

Introduction

The Hannover Coupler version 2 (HC2) was designed to (1) adapt the coupler geometry to the round window (RW) niche (2) to stabilize the floating mass transducer, and (3) to control static coupling forces to the RW. First audiological outcomes with a custom-made HC2 are reported here.

Material and Methods

Ten patients were enrolled in our site-initiated, prospective study. To assess audiological outcomes up to 6 months, preoperative and postoperative hearing thresholds, word recognition score (WRS) at 65 dB SPL and the speech recognition threshold in quiet and noise were performed. The effective gain (EG) and the coupling efficiency were calculated.

Results

One revision surgery had to be performed during the study period and a significant, but clinically not relevant bone conduction thresholds change was observed at 4 and 6 kHz at 6-month follow-up. At 6 months, the median WRS (n = 10) improved significantly from 0% to 80%. The median speech reception threshold in noise improved significantly from 11.6 to -2.4 dB SNR, and in quiet significantly from 79.6 to 44.4 dB SPL. The average EG of -1.3 dB indicated a closure of the air bone gap. The determined average coupling efficiency of 23.3 dB was within the acceptance range suggested by the manufacturer.

Conclusion

For patients with mixed hearing loss and multiple ear surgeries, the HC2 provided good and stable speech recognition results exceeding published results of RW coupling without a coupler or coupling with the RW soft coupler.

Transcutaneous Bone Conduction Implants in Patients With Single-Sided Deafness: Objective and Subjective Evaluation

OBJECTIVES

This study aimed to investigate the audiological outcomes and subjective benefits of transcutaneous bone conduction implants (BCIs) in patients with single-sided deafness (SSD).

METHODS

This retrospective study was conducted on 11 patients with SSD implantations between 2015 and 2018 at a tertiary center. Pure-tone audiometry, speech reception threshold (SRT), and speech-in-noise (SPIN) tests were performed. Preoperative and postoperative performances were compared. Subjective satisfaction level was assessed using validated questionnaires. A PubMed search was conducted to identify the relevant studies published to date.

RESULTS

All patients demonstrated significant audiological improvements compared with their preoperative condition. The mean SRT improved significantly (p = 0.001) from 109 dB to 23 dB after implantation. The mean SPIN score improved significantly after implantation. The questionnaires showed an overall positive benefit of transcutaneous bone conduction devices (BCDs). A literature search revealed 21 articles, of which 14 reported the use of BCIs in patients with SSD. Our results agree with the published evidence showing the overall benefit of BCI in patients with SSD.

CONCLUSIONS

Transcutaneous BCDs could be considered as an alternative treatment option for patients with SSD, it could show good audiological outcomes and high satisfaction levels. Further studies should be conducted on patients with SSD to determine the most appropriate hearing solutions.

The Baha® Attract System Implantations Significantly Improve the Quality of Life of Hearing-Impaired Patients in Long-Term Observations

BACKGROUND

The aim of this study was to assess the impact of the Baha® Attract system implantation on the quality of life of hearing-impaired patients, who were qualified for surgery due to various audiological indications.

METHODS

A total of 96 patients implanted with the Baha® Attract system were asked to fill in the set of questionnaires: the Glasgow Benefit Inventory, the Abbreviated Profile of Hearing-Aid Benefit, and the BAHA Aesthetic, Hygiene, and Use. Totally 79 patients responded and were then analyzed. Patients were divided into 4 groups: A: with bilateral mixed or conductive hearing loss, B: with single-sided deafness, C: with unilateral mixed or conductive hearing loss, and D: others.

RESULTS

There was a significant improvement in quality of life measured by the Glasgow Benefit Inventory in all the analyzed groups, with a mean total score of 29.4 points (P < .001). Similarly, the evaluation by the Abbreviated Profile of Hearing Aid Benefit questionnaire showed a significant improvement in terms of the global score in all the analyzed groups, with a mean gain of 38.6% (P < .001). There were no differences between the groups. More than 90% of patients found the Baha® Attract system easy to place on their heads and maintain good hygiene. Of all the implant users, 81% were satisfied with the final aesthetic effect.

CONCLUSION

The implantation of the Baha® Attract system significantly improves the quality of life of hearing-impaired patients in all subjec- tive scales used. The system is effective for all audiological indications when strictly adhered to. The majority of patients are very satisfied with the aesthetic, hygienic, and utility aspects of the device.

The Impact of Location and Device Coupling on the Performance of the Osia System Actuator

Active transcutaneous bone conduction (BC) devices offer the benefit of improved power output compared to passive transcutaneous devices and remove the risk of skin infections that are more common in traditional percutaneous BC devices. Despite these advantages, more research is needed on implant location, device coupling, and their influence on device performance. This study is aimed at quantifying the extent to which certain parameters affect device output when using the Osia® system actuator. Parameters under study are (1) implant location, (2) comparison with the actuator of a state-of-the-art BC device, (3) bone undergrowth simulation, and (4) skull fixation. Five human cadaveric heads were implanted with the actuator at three different implant locations: (1) recommended, (2) posterior Osia® positions, and (3) standard Baha® position. At each location, the cochlear promontory velocity and the intracochlear pressure difference were measured. A percutaneous bone conduction actuator was used as a reference for the obtained measurements. Stimulation levels corresponded to a hearing level of 60 dB HL for frequencies between 250 and 6000 Hz. In addition, bone cement was used as a simulation for reactive bone growth. Results obtained in four heads indicate an improved power transmission of the transcutaneous actuator when implanted at the recommended position compared to the actuator of the percutaneous device on its respective recommended location when stimulating at an identical force level. A correlation was found between the promontory vibration and the actuator position, indicating that the same level of stimulation leads to higher promontory vibrations when the device is implanted closer to the ear canal. This is mainly reflected at frequencies higher than 1 kHz, where an increase was observed in both measurement modalities. At lower frequencies (<1 kHz), the power transmission is less influenced by the implant position and differences between the acquired responses are limited. In addition, when no rigid coupling to the skull is provided, power transfer losses of up to 30 dB can be expected.

Study of occlusal acoustic parameters in assessing masticatory performance

Background

Previous masticatory studies have focused on a variety of measurements of foods and boluses or kinematic parameters and sound during mastication. To date, the masticatory sound research of has been limited due to the difficulties of sound collection and accurate analysis. Therefore, significant progress in masticatory sound has not been made. Meanwhile, the correlation between acoustic parameters and mastication performance remains unclear. For the purpose of exploring the acoustic parameters in measuring mastication performance, the bone-conduction techniques and sound analysis were used, and a statistical analysis of acoustic and occlusal parameters were conducted.

Methods

The gnathosonic and chewing sounds of fifty-six volunteers with healthy dentate were recorded by a bone-conduction microphone and further analyzed by Praat 5.4.04 when intercuspally occluding natural foods (peanuts) were consumed. The granulometry of the expectorated boluses from the peanuts was characterized by the median particle size of the whole chewing sequence (D50^a) and the median particle size during the fixed chewing strokes (D50^b). The chewing time of the whole chewing sequence (CT^a), the chewing time of the fixed chewing strokes (CT^b), the chewing cycles (CC), and the chewing frequency (CF) were recorded and analyzed by the acoustic software. The acoustic parameters, including gnathosonic pitch, gnathosonic intensity, mastication sound pitch of the whole chewing sequence (MP^a), mastication sound pitch of the fixed chewing strokes (MP^b), mastication sound intensity of the whole chewing sequence (MI^a) and mastication sound intensity of the fixed chewing strokes (MI^b), were analyzed. Independent sample t-test, Spearman and Pearson correlation analyses were used where applicable.

Results

Significant difference in parameters CC, MI^a, CF and D50^a were found by sex (t-test, p < 0.01). The masticatory degree of the test foods was higher in women (CC, 24.25 ± 5.23; CF, 1.70 ± 0.21 s⁻¹; D50^a, 1655.07 ± 346.21 μm) than in men (CC, 18.14 ± 6.38; CF, 1.48 ± 0.18 s⁻¹; D50^a, 2159.21 ± 441.26 μm). In the whole chewing sequence study, a highly negative correlation was found between MI^a and D50^a, and a highly positive correlation was found between MI^a and CF (r =  − 0.94, r = 0.82, respectively, p < 0.01). No significant correlation was found between the remaining acoustic parameters and mastication parameters. In the fixed chewing strokes study, a highly negative correlation was found between MI^b and D50^b (r =  − 0.85, p < 0.01). There was no significant correlation between the rest of the acoustic parameters and the mastication parameters.

Conclusions

Mastication sound intensity may be a valuable indicator for assessing mastication. Acoustic analysis can provide a more convenient and quick method of assessing mastication performance.

Supplementary Information

The online version contains supplementary material available at 10.1186/s12903-021-02018-9.

Measurement and modeling of the mechanical impedance of human mastoid and condyle

Bone conduction devices are used in audiometric tests, hearing rehabilitation, and communication systems. The mechanical impedance of the stimulated skull location affects the performance of the bone conduction devices. In the present study, the mechanical impedances of the mastoid and condyle were measured in 100 Chinese subjects aged from 22 to 67 years. The results show that the mastoid and condyle impedances within the same subject differ significantly and the impedance differences between subjects at the same stimulation position are mainly below the resonance frequency. The mechanical impedance of the mastoid is significantly influenced by age, and not related to gender or body mass index (BMI). While the mechanical impedance of the condyle is significantly affected by BMI, followed by gender, and not related to age. There are some differences in mastoid impedance between the Chinese and Western subjects. An analogy model predicts that the difference in mechanical impedance between the mastoid and condyle leads to a significant difference in the output force of the bone conduction devices. The results can be used to develop improved condyle and mastoid stimulators for the Chinese.

Influence of head orientation and implantation site of a novel transcutaneous bone conduction implant on MRI metal artifact reduction sequence

Purpose

The use of magnetic resonance imaging (MRI) is often limited in patients with auditory implants because of the presence of metallic components and magnets. The aim of this study was to evaluate the clinical usefulness of a customized MRI sequence for metal artifact suppression in patients with BONEBRIDGETM BCI 602 implants (MED-EL, Innsbruck, Austria), the successor of the BCI 601 model.

Methods

Using our in-house developed and customized metal artifact reduction sequence (SEMAC-VAT WARP), MRI artifacts were evaluated qualitatively and quantitatively. MRI sequences were performed with and without artifact reduction on two whole head specimens with and without the BCI 602 implant. In addition, the influence of two different implantation sites (mastoid versus retrosigmoid) and head orientation on artifact presence was investigated.

Results

Artifact volume was reduced by more than the 50%. Results were comparable with those obtained with the BCI 601, showing no significant differences in the dimensions of artifacts caused by the implant.

Conclusion

SEMAC-VAT WARP was once more proved to be efficient at reducing metal artifacts on MR images. The dimensions of artifacts associated with the BCI 602 are not smaller than those caused by the BCI 601.

The outcomes of bilateral bone conduction hearing devices (BCHD) implantation in the treatment of hearing loss: A systematic review

OBJECTIVES

Bone Conduction Hearing Devices (BCHDs) are a means of improving hearing ability in those that do not receive full benefit from conventional hearing aids. In 2016, the NHS started commissioning bilateral BCHDs. This review aims to evaluate the current literature and identify areas for further research.

METHODS

This review was conducted in line with the PRISMA guidelines and registered on the PROSPERO database (registration CRD42020191956). MEDLINE, CINAHL and The Cochrane Library were systematically searched. The full text of relevant titles and abstracts was then reviewed before data extraction was undertaken. Risk of bias was assessed using the ROBINS-1 tool.

RESULTS

Searches identified 125 studies. After removing duplicates, 28 full texts were screened. 14 studies were included in the final review. Amongst the audiological outcomes, greater improvements for bilateral compared to unilateral BCHDs were seen in hearing thresholds, understanding speech in quiet, localization, and restoration of binaural hearing. Thus, supporting the addition of a second implant. For speech in noise however, bilateral BCHDs were less effective when the noise was presented from one side. Increases in measures of Quality of Life, including the Glasgow Benefit Index, were seen across all included studies. No studies included complication rates.

CONCLUSION

Overall, bilateral BCHDs offer benefits to the recipient's audiological capabilities and QoL. However, more research is required on the complications and the cost of bilateral BCHDs. Further to this, future research should aim to use uniform tests to measure outcomes.

Management of patients with unilateral microtia and aural atresia: recent advances and updates

PURPOSE OF REVIEW

The management of patients with unilateral microtia and aural atresia is complex. Recent literature suggests significant strides in hearing habilitation and ear reconstruction.

RECENT FINDINGS

Several options of hearing management are available and are associated with improved outcomes. Timelines for hearing habilitation and ear reconstruction vary by institution. We offer our timeline as a reference. Three dimensional (3D) printed models are increasingly used for training and reconstruction. Bioprinting is on the horizon, though safety and effectiveness studies are pending. Lastly, application of qualitative methods has provided a foundation on which to improve communication between physicians and patients and their families. Better understanding of the patient and family experiences will provide opportunities to target interventions to improve care.

SUMMARY

Current developments include expanding options for hearing management, changing approaches to timing of atresiaplasty, utilization of 3D printed models, and focus on patient and family experience to improve reconstructive outcomes.

Hearing Outcomes with Percutaneous and Transcutaneous BAHA® Technology in Conductive and Mixed Hearing Loss

OBJECTIVES

To evaluate outcomes of BAHA Connect® and BAHA Attract® implantations, and to examine the prognostic utility of a preimplantation Softband®-attached processor trial.

STUDY DESIGN

Retrospective case review.

SETTING

Tertiary referral center.

PATIENTS

Patients who underwent Connect® (19 ears) and Attract® (25 ears) implantation between 2007 and 2017.

INTERVENTION

BAHA® implantation.

MAIN OUTCOME MEASURES

Unaided air conduction (AC), bone conduction (BC), and speech reception thresholds (SRTs), as well as free field (FF) aided with Softband®-attached processor and with implant-attached processor thresholds.

RESULTS

Serviceable implant-attached processor PTA0.5,1,2 kHz (≤35 dB HL) was achieved in 89 and 88% of the Connect® and the Attract® ears, respectively, while at 4 kHz this was achieved in 68 and 32% of the Connect® and the Attract® ears, respectively (p  =  0.032). Significantly more Connect® ears showed alignment between FF aided with implant-attached processors thresholds and BC thresholds. The alignment between the Softband®-attached processors thresholds and implant-attached processors thresholds was similar in the two groups. Both groups exhibited similar positive improvement in the quality of life questionnaires.

CONCLUSIONS

Accessibility to sound with the implant-attached processor is well predicted by the pre-implantation Softband® trial, both in the BAHA Connect® and in the BAHA Attract® ears. Hearing rehabilitation targets at 0.5, 1, and 2 kHz are met by most Connect® and Attract® ears, while at 4 kHz the outcome with Attract® is poorer. This information should be presented to the patient during consultation prior to a decision as to the type of BAHA® device to be implanted.

Sound Localization and Lateralization by Bilateral Bone Conduction Devices, Middle Ear Implants, and Cartilage Conduction Hearing Aids

Sound localization in daily life is one of the important functions of binaural hearing. Bilateral bone conduction devices (BCDs), middle ear implants, and cartilage conduction hearing aids have been often applied for patients with conductive hearing loss (CHL) or mixed hearing loss, for example, resulting from bilateral microtia and aural atresia. In this review, factors affecting the accuracy of sound localization with bilateral BCDs, middle ear implants, and cartilage conduction hearing aids were classified into four categories: (1) types of device, (2) experimental conditions, (3) participants, and (4) pathways from the stimulus sound to both cochleae. Recent studies within the past 10 years on sound localization and lateralization by BCDs, middle ear implants, and cartilage conduction hearing aids were discussed. Most studies showed benefits for sound localization or lateralization with bilateral devices. However, the judgment accuracy was generally lower than that for normal hearing, and the localization errors tended to be larger than for normal hearing. Moreover, it should be noted that the degree of accuracy in sound localization by bilateral BCDs varied considerably among patients. Further research on sound localization is necessary to analyze the complicated mechanism of bone conduction, including suprathreshold air conduction with bilateral devices.

Surgical Solution for the Transformation of the Percutaneous Bone Anchored Hearing Aid to a Transcutaneous System in Complicated Cases

Bone-anchored hearing aids (BAHAs) have been used for multiple types of hearing loss both in pediatric and adult cases. In the last decades, the percutaneous BAHA® Connect System (Cochlear Ltd., Sydney, Australia) was replaced by the fully implanted transcutaneous, magnet-based BAHA® Attract System (Cochlear Ltd., Sydney, Australia). Since the implantable part of the Attract device is fully covered with soft tissue, skin complications that were frequently observed in the percutaneous system, could be eliminated. As an outcome of this important advantage of the Attract System, conversion of the percutaneous into a transcutaneous system should be considered. In the following methodology report, a possible surgical technique is described. The method can easily be adopted to different conditions in which the replacement of the percutaneous device is necessary.

Long-term audiological benefit with an active transcutaneous bone-conduction device: a retrospective cohort analysis

PURPOSE

To evaluate long-term audiological, surgical and safety outcomes of a complex patient cohort treated with an active transcutaneous bone-conduction device (tBCD).

METHODS

This retrospective, monocentric cohort analysis involves 31 adults with conductive (CHL) and mixed hearing loss (MHL). For outcome analysis, study results were divided into short-term follow-up data (< 12 months) and long-term follow-up data (> 12 months).

RESULTS

31 patients with a total person-time of 90.4 years and an average number of 3.2 ± 1.5 preoperatively performed surgeries on the implanted side were investigated. Mean BCD-aided PTA₄ thresholds were significantly lower than unaided PTA_4AC before surgery (64.7 ± 16.1 dB HL; CHL 50.6 ± 10.6 dB HL; MHL 72.8 ± 12.8 dB HL) and did not change between short-term (42.3 ± 13.1 dB HL; CHL 35.8 ± 6.8 dB HL; MHL 45.2 ± 14.3 dB HL) and long-term (43.4 ± 10.0 dB HL; CHL 35.8 ± 4.3 dB HL; MHL 48.1 ± 9.6 dB HL) follow-up periods. Speech intelligibility in the Freiburg monosyllables test at 65 dB improved significantly, from 16.3 ± 21.5% (CHL 26.8 ± 19.0%; MHL 8.7 ± 20.5%) in the unaided condition to 82.7 ± 15.5% (CHL 90.0 ± 12.2%; MHL 79.4 ± 16.3%) in the short-term and 85.5 ± 13.2% (CHL 93.8 ± 7.9%; MHL 79.5 ± 13.3%) BCD-aided in the long-term follow-up periods. Ten minor procedure-related and 6 implant-related (5 minor, 1 major) AEs occurred over the total follow-up period.

CONCLUSION

The device provides satisfactory audiological and speech benefit over long-term follow-up periods, up to 7 years. Explant rates were very low, while the overall rate of manageable AEs was high in this complex patient cohort. The device is considered a safe and effective option in the long-term hearing rehabilitation of patients with CHL and MHL.

Development of a finite element model of a human head including auditory periphery for understanding of bone-conducted hearing

A three-dimensional finite-element (FE) model of a human head including the auditory periphery was developed to obtain a better understanding of bone-conducted (BC) hearing. The model was validated by comparison of cochlear and head responses in both air-conducted (AC) and BC hearing with experimental data. Specifically, the FE model provided the cochlear responses such as basilar membrane velocity and intracochlear pressure corresponding to BC stimulations applied to the mastoid or the conventional bone-anchored-hearing-aid (BAHA) positions. This is a strength of the model because it is difficult to obtain the cochlear responses from experiments corresponding to the BC stimulation applied at a specific position on the head surface. In addition, there have been few studies based on an FE model that can calculate the head and cochlear responses simultaneously from a BC stimulation. Moreover, in this study, the intracochlear sound pressure at multi-positions along the BM length was calculated and used to clarify the effect of stimulating force direction on the cochlear and promontory velocities in BC hearing. Also, the relationship between BC and AC stimulation and the basilar membrane velocity in the FE model was used to calculate the stimulation level at hearing thresholds which has been investigated only by psychoacoustical methods.

Retrosigmoidal placement of an active transcutaneous bone conduction implant: surgical and audiological perspectives in a multicentre study

Introduction

The retrosigmoidal (RS) placement of the Bonebridge system (BB) has been advocated for cases of unfavourable anatomical or clinical conditions which contraindicate transmastoid-presigmoidal positioning. However, these disadvantageous conditions, combined with the considerable dimensions of the implant, may represent a challenge, especially for surgeons with no skull base experience. Moreover, the literature reports only limited experience concerning RS implantation of the BB system.

Methods

A multicentre, retrospective study was conducted to analyse the surgical and functional outcomes of a wide population of patients undergoing RS placement of the BB system by means of a surgical technique specifically developed to overcome the intraoperative issues related to this surgery. Twenty patients with conductive or mixed hearing loss and single sided deafness were submitted to RS implantation of the BB system.

Results

Audiological assessment concerning the measurement of the functional and effective gain by pure-tone audiometry (28 dB HL and -12.25 dB HL, respectively) and speech audiometry (24.7 dB HL and -21 dB HL, respectively) was conducted. A high overall subjective improvement of quality of life was recorded with the Glasgow Benefit Inventory questionnaire. No major complications, such as device extrusions or other conditions requiring revision surgery, were reported during the follow-up period (median: 42 months).

Conclusions

In our study, which has one of the largest cohort of patients reported in the literature, RS placement of the BB system was safe and effective. Our functional results showed comparable hearing outcomes with presigmoidal placement. The effective gain, rarely investigated in this field, may be the object of further research to improve our understanding of bone conduction mechanisms exploited by bone conduction hearing implants.

Clinical Performance Assessment of a New Active Osseointegrated Implant System in Mixed Hearing Loss: Results From a Prospective Clinical Investigation

OBJECTIVE

Evaluation of a new active osseointegrated bone-conduction hearing implant in moderate to severe mixed-hearing loss.

STUDY DESIGN

Prospective observational study of a series of cases.

SETTING

Tertial referral center.

PATIENTS

Twenty patients with moderate mixed-hearing loss were evaluated (10 Cochlear Osia group and 10 Baha 5 Power Connect -control group).

INTERVENTION

Rehabilitative.

MAIN OUTCOME MEASURES

Hearing performance in quiet and in noise and quality-of-life were evaluated.

RESULTS

Improvements in audibility, speech-understanding, speech-recognition, and quality-of-sound in noise and quiet were found for the Osia System compared with preoperative unaided hearing and performance was similar to that obtained with Baha 5 Power Connect.

CONCLUSIONS

The new active transcutaneous bone conduction system provided a tonal improvement in free-field at middle and high frequencies. The performance in speech recognition in quiet and in noise was similar to control group outcomes.

Clinical consensus document for fitting non-surgical transcutaneous bone conduction hearing devices to children

This clinical consensus document addresses the assessment, selection, and fitting considerations for non-surgical bone conduction hearing devices (BCHD) for children under the age of 5 years identified as having unilateral or bilateral, permanent conductive or mixed hearing losses. Children with profound unilateral sensorineural hearing losses are not addressed. The document was developed based on evidence review and consensus by The Paediatric Bone Conduction Working Group, which is composed of audiologists from North America who have experience working with BCHDs in children. The document aims to provide clinical direction for an area of paediatric audiology practice that is under development and is therefore lacking in standard protocols or guidelines. This work may serve as a basis for future research and clinical contributions to support prospective paediatric audiology practices.

Safety of active auditory implants in magnetic resonance imaging

Magnetic resonance imaging (MRI) has become the gold standard for the diagnosis of many pathologies. Using MRI in patients with auditory implants can however raise concerns due to mutual interactions between the implant and imaging device, resulting in potential patient risks. Several implant manufacturers have been working towards more MRI safe devices. Older devices are however often labelled for more stringent conditions, possibly creating confusion with patients and professionals. With this myriad of different devices that are implanted in patients for lifetimes of at least 20 years, it is crucial that both patients and professionals have a clear understanding of the safety of their devices. This work aims at providing an exhaustive overview on the MRI safety of active auditory implants. The available industry standards that are followed by manufacturers are outlined and an overview of the latest scientific developments focusing on the last five years is provided. In addition, based on the analysis of the adverse events reported to the Food and Drug Administration (FDA) and in literature within the past ten years, a systematic review of the most commonly occurring issues for patients with auditory implants in the MRI environment is provided. Results indicate that despite the release of more MRI conditional active hearing implants on the market, adverse events still occur. An extensive overview is provided on the MRI safety of active auditory implants, aiming to increase the understanding of the topic for healthcare professionals and contribute to safer scanning conditions for patients.

Piezoelectric bone conduction hearing implant Osia® - audiological and quality of life benefits

&lt;b&gt;Introduction:&lt;/b&gt; Nowadays, there are many options to treat hearing-impaired patients: tympanoplastic surgery, hearing aids and a wide range of implantable devices.&lt;/br&gt;&lt;/br&gt; &lt;b&gt;Aim:&lt;/b&gt; The aim of this study is to present the mid-term audiological and quality of life benefits after the implantation of Osia®, an active piezoelectric bone conduction hearing implant. &lt;/br&gt;&lt;/br&gt; &lt;b&gt;Material and methods:&lt;/b&gt; The state of the tissues in the implanted area, as well as audiological and quality of life results were analyzed at six, nine and twelve months after implantation in a group of four adult patients with bilateral mixed hearing loss (1 after bilateral canal-wall-down mastoidectomy, 2 with chronic simple otitis media and after myringoplasty in the opposite ear, 1 with bilateral otosclerosis and after stapedotomy in the opposite ear). &lt;/br&gt;&lt;/br&gt; &lt;b&gt;Results:&lt;/b&gt; No postoperative complications were found in any of the cases. One year after surgery the mean audiological gain in FF PTA4 (pure tone average for 0.5, 1, 2, and 4 kHz) was 52.2 ± 3.5 dB in comparison to the unaided situation, the mean speech understanding with Osia® in quiet was 90 ± 8.2% for 50 dB SPL, 98.8 ± 2.5% for 65 dB SPL and 100 ± 0% for 80 dB SPL, and the mean speech understanding with Osia® in noise was 37.5% ± 23.6 for 50 dB SPL, 93.8 ± 4.8% for 65 dB SPL and 98.8 ± 2.5% for 80 dB SPL. There was also an evident improvement in the quality of hearing as well as in the quality of life, measured by APHAB (Abbreviated Profile of Hearing Aid Benefit) and SSQ (Speech, Spatial and Qualities of Hearing Scale). &lt;/br&gt;&lt;/br&gt; &lt;b&gt;Conclusions:&lt;/b&gt; The Osia® is an effective treatment option for patients with bilateral mixed hearing loss. The mid-term audiological and quality of life results are excellent, but further observations including bigger groups of patients and a longer follow- -up are required.

A Novel Dentary Bone Conduction Device Equipped with Laser Communication in DSP

In this study, we designed a dentary bone conduction system that transmits and receives audio by laser. The main objective of this research was to propose a complete hardware design method, including a laser audio transmitter and receiver and digital signal processor (DSP) based digital signal processing system. We also present a digital filter algorithm that can run on a DSP in real time. This experiment used the CMU ARCTIC databases’ human-voice reading audio as the standard audio. We used a piezoelectric sensor to measure the vibration signal of the bone conduction transducer (BCT) and separately calculated the signal-to-noise ratio (SNR) of the digitally filtered audio output and the unfiltered audio output using DSP. The SNR of the former was twice that of the latter, and the BCT output quality significantly improved. From the results, we can conclude that the dentary bone conduction system integrated with a DSP digital filter enhances sound quality.

[Physical audiological principles of implantable hearing systems : About power transmission, coupling and power output]

Implantable hearing systems work because mechanical vibration energy is introduced into the hearing system. The performance of the hearing system is thus essentially determined by physical parameters. Together with the tone and speech audiogram the indications for deciding on a system are based on the efficacy of the respective system and the patient's wishes. Hearing-assisted patients should have a dynamic range of 30-35 dB to adequately understand speech. This should be guaranteed with the respective system also in the medium to long term. In addition, sufficient cochlear reserve performance for implantable hearing systems is critical for success. The expected and achieved audiological success can be the effective gain as a difference of aided hearing threshold to bone conduction threshold and should be preferred to the unreflecting use of gain or functional gain. With good differential diagnostic indications and the inclusion of conventional hearing aids and cochlear implants, optimal hearing solutions can be found for almost all patients.

Audiological benefits and performance improvements of Baha® attract implantation in patients with unilateral hearing loss

OBJECTIVES

To evaluate the overall functional and audiological benefits in unilateral hearing loss, as well as performance improvements with Cochlear™ Baha® Attract System with Baha® 5 sound processor.

METHODS

We performed a prospective study. Fourteen consecutive adult patients with unilateral hearing loss who were audiologically eligible for Baha® Attract were included in this study. All patients were followed-up, and a series of tests were performed in the sound field before surgery, one, two, three, and 6 months after surgery.

RESULTS

Patients were categorized based on their hearing impairment type and severity. Ten patients had conductive hearing loss (CHL), or mixed hearing loss (MHL), and four patients had sensorineural hearing loss (SNHL). The hearing threshold in the sound field aided with Baha® Attract was similar to the preoperative bone conduction hearing threshold of the better ear. The results of the speech audiometry improved post-operatively, but they did not match that of the better ear before surgery. The overall score of the hearing-in-noise test was gradually improved from one month to 6 months after surgery. The results of the sound localization test for SNHL patients were not as good as those for CHL or MHL. All the questionnaires demonstrated additional benefits that implied performance improvements.

CONCLUSIONS

The Baha® Attract provides enough auditory benefits and performance improvements for hearing impaired patients, though there are different benefits according to the type of hearing loss. Clinicians need to counsel the unilateral hearing loss patients for Baha® Attract System carefully, according to their type of hearing loss.

Wavelength-specific optoacoustic-induced vibrations of the guinea pig tympanic membrane

SIGNIFICANCE

Optoacoustic-induced vibrations of the hearing organ can potentially be used for a hearing device. To increase the efficiency of such a hearing device, the conversion of the light energy into vibration energy within each type of irradiated tissue has to be optimized.

AIM

To analyze the wavelength-dependency of optoacoustic-induced vibrations within the tympanic membrane (TM), and to define the most efficient and best-suited optical stimulation parameters for a novel auditory prosthesis.

APPROACH

Single nanosecond laser pulses, continuously tunable in a range of visible to near-infrared, were used to excite the guinea pig TM. The induced vibrations of the hearing organ were recorded at the malleus using a laser Doppler vibrometer.

RESULTS

Our results indicate a strong wavelength-dependency of the vibration's amplitude correlating with the superposition of the absorption spectra of the different specific tissue components.

CONCLUSIONS

We investigated the spectrum of the vibrations of the hearing organ that were induced optoacoustically within a biological membrane embedded in air, in an animal model. First applications for these results can be envisioned for the optical stimulation of the peripheral hearing organ as well as for research purposes.

[Experimental Evaluation of the Adhear, a Novel Transcutaneous Bone Conduction Hearing Aid]

OBJECTIVE

Different bone conduction hearing aids (BCHA) are commercially available. They are attached to the head in different ways. The aim of this work is an experimental evaluation of the performance of a new transcutaneous (surface mounted via adhesive pad) actuator of a BCHA.

MATERIAL AND METHODS

Experiments were conducted on a Thiel embalmed whole head cadaver specimen. The electromagnetic actuators from a commercial BCHA (Adhear) was used to provide stepped sine stimulus in the range of 0.1-10 kHz. The BCHA was coupled to a skin surface adhesion that was placed on the mastoid. The response was monitored as motions of the ipsi- and contralateral promontory, and as motions of the ipsi-, top- and contralateral skull surface. Promontory motion was quantified via a three-dimensional laser Doppler vibrometer (3D LDV) system. Analogously, surface motion was registered by sequentially measuring ~200 points on the skull surface (~ 15-20 mm pitch) via 3D LDV. The data were compared to corresponding measurements obtained with a Baha Power that was coupled to skin on the Mastoid via a 5 Newton steelband.

RESULTS

Ipsilateral and contralateral promontory vibration for stimulation with the Adhear are comparable to stimulation with the Baha Power on the 5 Newton steelband with regard to frequency dependent amplitude and phase, as well as the contribution of the motion components. The surface motion of the skull experiences a similar complex motion for both stimulation modes.

CONCLUSIONS

Although the Adhear is coupled without any pressure to the skin over the mastoid whereas the Baha power is attached with a 5 Newton steelband, the vibration parameters investigated are comparable.

[Implantation of a new active bone conduction hearing device with optimized geometry. German version]

Here, we describe the surgical technique for implanting a new, active, transcutaneous bone conduction hearing aid. The implant technology is based on a system that has been in use reliably since 2012. The geometry of the new implant has been adapted based on experience with previously introduced implants. The surgery was feasible, standardized, and safe. Due to the optimized geometric design that improved the bone fit, it is not necessary to use specialized, detailed preoperative planning, except in challenging anatomical conditions; e.g., in young children, malformations, poor pneumatization, or after a canal wall down mastoidectomy.

Patient-reported long-term benefit with an active transcutaneous bone-conduction device

Purpose

To evaluate the long-term benefits in hearing-related quality of life, patient satisfaction and wearing time of patients rehabilitated with an active transcutaneous bone-conduction device. Adverse events and audiological outcomes are reported as secondary outcomes.

Methods

This retrospective, mono-centric cohort analysis involves 16 adults with conductive or mixed hearing loss with a mean device experience of 51.25 months. Patient-reported outcome measures were assessed using the short version of the Speech, Spatial and Qualities of Hearing Scale (SSQ12-B) and the German version of the Audio Processor Satisfaction Questionnaire (APSQ). Audiological outcomes as well as incidence of adverse events were obtained from patients´ charts.

Results

The hearing-related quality of life improved significantly within all subscales of the SSQ12-B scoring a mean overall of 2.95 points. Patient satisfaction measured with the APSQ scored 8.8 points on average. Wearing times differed considerably and patients with lower levels of education seemed to use their device longer compared to patients with academic education. Eight minor adverse events were documented, all of which resolved during follow-up. The mean gain in word recognition score at the last follow-up measured at 65 dB was 75.9%, while speech reception threshold was lowered by 35.1 dB.

Conclusion

Even after several years, patients report significant benefits in hearing-related quality of life and device satisfaction. In combination with a low rate of minor adverse events and significantly improved audiological outcomes, the device is considered as a comfortable and effective option in hearing rehabilitation.

The Mechanical Impedance of the Human Skull via Direct Bone Conduction Implants

Purpose

The mechanical skull impedance is used in the design of direct bone drive hearing systems. This impedance is also important for the design of skull simulators used in manufacturing, service, and fitting procedures of such devices.

Patients and Methods

The skull impedance was measured in 45 patients (25 female and 20 male) who were using percutaneous bone conduction implants (Ponto system or Baha system). Patients were recruited as a consecutive prospective case series and having an average age of 55.4 years (range 18–80 years). Seven patients were treated in Gothenburg, Sweden, and 38 patients in Edmonton, Canada. An impedance head (B&K 8001), driven by an excitation transducer with emphasized low-frequency response, was used to measure the mechanical point impedance with a swept sine from 100 to 10k Hz.

Results and Discussion

The skull impedance was found to have an anti-resonance of approximately 150 Hz, with a median maximum magnitude of 4500 mechanical ohms. Below this anti-resonance, the mechanical impedance was mainly mass-controlled corresponding to an effective skull mass of 2.5 kg at 100 Hz with substantial damping from neck and shoulder. Above the anti-resonance and up to 4 kHz, the impedance was stiffness-controlled, with a total compliance of approximately 450n m/N with a small amount of damping. At frequencies above 4 kHz, the skull impedance becomes gradually mass-controlled originating from the mass of the osseointegrated implant and adjacent bone. No significant differences related to gender or skull abnormalities were seen, just a slight dependence on age and major ear surgeries. The variability of the mechanical impedance among patients was not found to have any clinical importance.

Conclusion

The mechanical skull impedance of percutaneous implants was found to confirm previous studies and can be used for optimizing the design and test procedures of direct bone drive hearing implants.

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Implantation of a new active bone conduction hearing device with optimized geometry

Here, we describe the surgical technique for implanting a new, active, transcutaneous bone conduction hearing aid. The implant technology is based on a system that has been in use reliably since 2012. The geometry of the new implant has been adapted based on experience with previously introduced implants. The surgery was feasible, standardized, and safe. Due to the optimized geometric design that improved the bone fit, it is not necessary to use specialized, detailed preoperative planning, except in challenging anatomical conditions; e.g., in young children, malformations, poor pneumatization, or after a canal wall down mastoidectomy.

The BONEBRIDGE active transcutaneous bone conduction implant: effects of location, lifts and screws on sound transmission

BACKGROUND

The BONEBRIDGE (MED-EL, Innsbruck, Austria) is a bone-conduction implant used in the treatment of conductive and mixed hearing loss. The BONEBRIDGE consists of an external audio processor and a bone-conduction floating mass transducer that is surgically implanted into the skull in either the transmastoid, retrosigmoid or middle fossa regions. The manufacturer includes self-tapping screws to secure the transducer; however, self-drilling screws have also been used with success. In cases where the skull is not thick enough to house the transducer, lifts are available in a variety of sizes to elevate the transducer away from the skull. The objective of the present study was to investigate the effects of screw type, lift thickness, and implant location on the sound transmission of the BONEBRIDGE.

METHOD

Six cadaveric temporal bones were embalmed and dried for use in this study. In each sample, a hole was drilled in each of the three implant locations to house the implant transducer. At the middle fossa, six pairs of screw holes were pre-drilled; four pairs to be used with self-tapping screws and lifts (1, 2, 3, and 4 mm thick lifts, respectively), one pair with self-tapping screws and no lifts, and one pair with self-drilling screws and no lifts. At the transmastoid and retrosigmoid locations, one pair of screw holes were pre-drilled in each for the use of the self-tapping screws. The vibration of transmitted sound to the cochlea was measured using a laser Doppler vibrometry technique. The measurements were performed on the cochlear promontory at eight discrete frequencies (0.5, 0.75, 1, 1.5, 2, 3, 4 and 6 kHz). Vibration velocity of the cochlear wall was measured in all samples. Measurements were analyzed using a single-factor ANOVA to investigate the effect of each modification.

RESULTS

No significant differences were found related to either screw type, lift thickness, or implant location.

CONCLUSIONS

This is the first known study to evaluate the effect of screw type, lift thickness, and implant location on the sound transmission produced by the BONEBRIDGE bone-conduction implant. Further studies may benefit from analysis using fresh cadaveric samples or in-vivo measurements.

A Retrospective Review of Temporal Bone Computed Tomography to Present Safe Guideline for Bone-Anchored Hearing Aids

OBJECTIVES

Bone-anchored hearing device (BAHD) is contraindicated in patients younger than 5 years because their calvarial bones are not thick enough to be implanted site. However, it has not been studied in the Korean population. This study was not only to establish a safe guideline for depth of implant device in all age groups who undergo BAHD implant surgery, but also to investigate whether implantation of currently used BAHDs could be done safely in Korean children, especially those younger than 5.

METHODS

Two hundred eighty patients, who underwent high-resolution temporal bone computed tomography (TBCT) images between August 2010 and October 2018 were randomly enrolled in all ages. We retrospectively reviewed TBCT imaging to measure skull bone thickness at the recommended BAHD implant site.

RESULTS

The average skull bone thickness was 2.87 mm in patients younger than 5 years and 6.72 mm in patients older than 5 years, respectively, which conforms to the current guideline. The results indicate nearly 50% of calvarial bone thicknesses were less than 3 mm in patients under 5 years old, while 92.78% of the patients older than 5 years of age showed bone thickness greater than 4 mm. Of note, calvarial bone thickness was thicker than 3 mm in all patients who are older than 6 years.

CONCLUSION

This study confirms that the currently approved BAHD implantation guideline is suitable in the Korean population. For safety, we suggest taking TBCTs prior to surgery, especially in pediatric patients. Besides, noninvasive applications are recommended for patients younger than 5.

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

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

Auditory Performance and Subjective Satisfaction with the ADHEAR System

BACKGROUND

The ADHEAR device, a new nonsurgical bone conduction hearing device, has been developed for patients with conductive hearing loss.

OBJECTIVES

This study aims to assess the impact of the ADHEAR device on the audiological performance and satisfaction level in subjects with conductive hearing loss.

METHODS

Twelve patients with conductive hearing loss were included. All patients received the device for 3 months. The audiological outcomes were determined using basic audiological assessments, including pure tone audiometry and sound field measurements of pure tone and speech audiometry with the contralateral ear occluded with a specific earplug. Additionally, the patients were subjectively evaluated using (1) the Speech, Spatial, and Qualities Questionnaire (SSQ), and (2) the custom-made ADHEAR questionnaire.

RESULTS

Analysis of the measured audiological outcomes revealed an average improvement in pure tone thresholds (functional gain) of 23 (± 4.4) dB HL when the ADHEAR system was used compared to the unaided condition in the sound field. Moreover, speech reception thresholds improved by an average of 23 (± 15.3) dB SPL in the aided condition with plugged contralateral ear. Additionally, when using ADHEAR in the sound field, subjects' speech recognition scores improved by 32% (± 17.7) in quiet and 21% (± 15.1) in the presence of interfering noise. The average SSQ questionnaire scores improved from 3.9 at the study initiation to 6.6 after 3 months of device usage. ADHEAR custom questionnaire assessments revealed high satisfaction and acceptance of the device with no pain or skin irritation.

CONCLUSION

During the study period, this new adhesive system yielded improved audiological outcomes with high patient satisfaction and acceptance and no reported skin irritation or pain.

A Comparative Study of a Novel Adhesive Bone Conduction Device and Conventional Treatment Options for Conductive Hearing Loss

Objective:

To compare the audiological performance with the novel adhesive bone conduction hearing device (ADHEAR) to that with a passive bone conduction (BC) implant and to that with a bone conduction device (BCD) on a softband.

Study Design:

Prospective study in an acute setting, single-subject repeated measure in three situations: unaided, with conventional BCDs (passive implant or on softband), and with the ADHEAR.

Setting:

Tertiary referral center.

Patients:

Ten subjects with conductive hearing loss were evaluated with the ADHEAR. Five of these were users of a passive BC implant (Baha Attract with Baha4); five received a BCD (Baha4) on a softband for test purposes.

Intervention:

Use of non-invasive adhesive bone conduction system for the treatment of conductive hearing loss.

Main Outcome Measures:

Air and bone conduction thresholds, sound field thresholds, word recognition scores in quiet, and speech recognition thresholds in quiet and noise were assessed.

Results:

Users of the passive BC implant received comparable hearing benefit with the ADHEAR. The mean aided thresholds in sound field measurements and speech understanding in quiet and noise were similar, when subjects were evaluated either with the ADHEAR or the passive BC implant. The audiological outcomes for the non-implanted group were also comparable between the ADHEAR and the BCD on softband.

Conclusions:

Based on our initial data, the ADHEAR seems to be a suitable alternative for patients who need a hearing solution for conductive hearing loss but for medical reasons cannot or do not want to undergo surgery for a passive BC implant.

Ten years of experience with the Ponto bone-anchored hearing system-A systematic literature review

Background

Bone‐anchored hearing systems (BAHSs) are widely used for hearing rehabilitation and are indicated in cases of conductive and mixed hearing loss and in single‐sided deafness. The Ponto system, that is one available option, has been on the market since 2009.

Objective of review

The aim of this study is to systematically review the literature reporting on the Ponto system, with regard to audiological and surgical outcomes and patient's quality‐of‐life scores.

Type of review

A systematic literature search was performed in the PubMed database 2009‐July 2019.

Search strategy

Search term: ((osseointegrated hearing aid) OR (bone conduction implant) OR (bone anchored hearing) OR BAHA OR BAHS OR BAHI). Pre‐defined inclusion and exclusion criteria were applied.

Evaluation method

English‐language articles reporting original clinical data (audiological, surgical or quality‐of‐life outcomes) on the Ponto system were included.

Articles reporting on Ponto and another BAHS system where the results on Ponto constituted less than 50% of the patient population or including only results on testband or softband devices were excluded.

Results

Audiological outcomes were discussed in 20 publications. Improvement against the unaided thresholds was demonstrated. The functional improvement was on average 33.9 dB. The effective gain or remaining air‐bone gap was on average 6.7 dB. All evaluated data showed aided speech reception thresholds significantly below normal speech level. Twenty‐seven publications reported surgical and follow‐up data for the Ponto system. Implant survival was 97.7%, adverse skin reactions (Holgers ≥ 2) were 5% across visits and 15% across patients. No complications were life‐threatening, causing permanent disability/damage or requiring a hospitalisation. Five studies reported quality of life using the Glasgow benefit inventory, 98% reported an improvement when analysing the score on an individual level.

Conclusions

The outcomes of this systematic review confirm that percutaneous systems provide consistent audiological benefits and improved quality of life for patients. Further, the review demonstrates that the percutaneous systems are safe, with relatively low complication rates. Skin‐related complications are the most common complication type and are experienced by approximately one patient out of seven, or in less than one of 20 follow‐up visits.

Assessment of Cortical Auditory Function Using Electrophysiological and Neuropsychological Measurements in Children with Bone-Anchored Hearing Aids

Children suffering from conductive or mixed hearing loss may benefit from a bone-anchored hearing aid system (BAHA Attract implantable prosthesis). After audiological rehabilitation, different aspects of development are improving. The objective of this case report is to propose a comprehensive framework for monitoring cortical auditory function after implantation of a bone-anchored hearing aid system by using electrophysiological and neuropsychological measurements.

We present the case of a seven-year-old boy with a congenital hearing loss due to a plurimalformative syndrome, including outer and middle ear malformation. After the diagnosis of hearing loss and the audiological rehabilitation with a BAHA Attract implantable prosthesis, the cortical auditory evoked potentials were recorded. We performed a neuropsychological evaluation using the Wechsler Intelligence Scale for Children – Fourth Edition, which was applied according to a standard procedure.

The P1 latency was delayed according to the age (an objective biomarker for quantifying cortical auditory function). The neuropsychological evaluation revealed that the child's working memory and verbal reasoning abilities were in the borderline range comparing with his nonverbal reasoning abilities and processing abilities, which were in the average and below-average range, respectively.

Cortical auditory evoked potentials, along with neuropsychological evaluation, could be an essential tool for monitoring cortical auditory function in children with hearing loss after a bone-anchored hearing aid implantation.