Comparison between incus short process and long process coupling of the vibrant soundbridge in human temporal bones.

OBJECTIVE: The Vibrant Soundbridge (VSB) is one of the most widely used implantable hearing devices. It consists of a vibrating floating mass transducer (FMT) that is connected to a middle ear structure. The standard coupling devices for sensorineural hearing loss are short process (SP) or long process (LP) couplers. DESIGN AND STUDY SAMPLE: This study directly compared the electro-mechanical performance of the SP- and LP-coupled FMT of the VSB in the same temporal bone specimen (n = 10). We measured velocity magnitudes and total harmonic distortions (THD) of the stapes (ST) and the round window (RW) using laser Doppler Vibrometry (LDV). RESULTS: Comparison shows a maximally 10 dB higher magnitude for the LP coupler at ST and RW for frequencies below 600 Hz, whereas the SP coupler shows a maximally 20 dB higher magnitude at the ST and RW for frequencies above 600 Hz. THD show similar behaviour with less distortion at 500 Hz for the LP coupler and less distortions for the SP coupler in higher frequencies. CONCLUSIONS: Our experiments showed that the SP coupling may be mechanically favourable, in terms of magnitude and distortion, for the transmission of FMT vibrations at higher frequencies.

Alterations in auditory change detection associated with tinnitus residual inhibition induced by auditory electrical stimulation.

BACKGROUND: Residual inhibition (RI) is a temporary phenomenon that happens following offset of appropriate complete or partial acoustical and electrical masking stimulations in people who experience tinnitus. The biologic mechanisms associated with RI are not yet fully understood. Few studies have been focused on RI. Auditory mismatch negativity (MMN) as a change-detection tool may be an appropriate tool to explore the processing changes because of tinnitus and RI. PURPOSE: The purpose of this study was to investigate alterations in auditory change detection and auditory sensory memory related to RI induced by auditory electrical stimulation (AES) using MMN brain mapping in participants with tinnitus. RESEARCH DESIGN: This investigation was a single-blind randomized controlled clinical trial study. Participants were randomly assigned into two groups: AES and placebo electrical stimulation (PES). STUDY SAMPLE: Twenty-eight participants with chronic subjective tinnitus aged 22- to 45-yr-old participated in the study. INTERVENTION: After randomization, all participants received both AES and PES for 1 min in different sessions. DATA COLLECTION AND ANALYSIS: Brain mapping of multifeature MMN paradigm was recorded from 29 scalp electrodes pre- and post-AES and PES. Following AES, participants were categorized into two groups: RI and nonresidual inhibition (NRI). The grand average MMN waveforms and isopotential topographic maps were obtained in RI, NRI, and PES groups. RESULTS: Three MMN parameters for five deviants of frequency, intensity, duration, location, and silent gap were compared among three groups of RI, NRI, and PES. Statistical analyses revealed significant between-subject effects for AES on MMN amplitude of frequency and duration deviant, MMN area under the curve of frequency, intensity, and duration deviants. CONCLUSIONS: Presence of RI can reestablish change-detection mechanisms in the central auditory pathways. It is suggested that MMN is reliable for assessment of change-detection system in people with tinnitus. It can be a useful technique in monitoring effects of treatments and rehabilitation.

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

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

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

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

Multicenter study with a direct acoustic cochlear implant.

OBJECTIVE: To confirm the clinical efficacy and safety of a direct acoustic cochlear implant. STUDY DESIGN: Prospective multicenter study. SETTING: The study was performed at 3 university hospitals in Europe (Germany, The Netherlands, and Switzerland). PATIENTS: Fifteen patients with severe-to-profound mixed hearing loss because of otosclerosis or previous failed stapes surgery. INTERVENTION: Implantation with a Codacs direct acoustic cochlear implant investigational device (ID) combined with a stapedotomy with a conventional stapes prosthesis MAIN OUTCOME MEASURES: Preoperative and postoperative (3 months after activation of the investigational direct acoustic cochlear implant) audiometric evaluation measuring conventional pure tone and speech audiometry, tympanometry, aided thresholds in sound field and hearing difficulty by the Abbreviated Profile of Hearing Aid Benefit questionnaire. RESULTS: The preoperative and postoperative air and bone conduction thresholds did not change significantly by the implantation with the investigational Direct Acoustic Cochlear Implant. The mean sound field thresholds (0.25-8 kHz) improved significantly by 48 dB. The word recognition scores (WRS) at 50, 65, and 80 dB SPL improved significantly by 30.4%, 75%, and 78.2%, respectively, after implantation with the investigational direct acoustic cochlear implant compared with the preoperative unaided condition. The difficulty in hearing, measured by the Abbreviated Profile of Hearing Aid Benefit, decreased by 27% after implantation with the investigational direct acoustic cochlear implant. CONCLUSION: Patients with moderate-to-severe mixed hearing loss because of otosclerosis can benefit substantially using the Codacs investigational device.

First European multicenter results with a new transcutaneous bone conduction hearing implant system: short-term safety and efficacy.

OBJECTIVE: To investigate safety and efficacy of a new transcutaneous bone conduction hearing implant, over a 3-month follow-up period. STUDY DESIGN: Prospective, single-subject repeated-measures design in which each subject serves as his/her own control. SETTING: Departments of Otolaryngology at 4 hospitals in Germany and Austria. PATIENTS: Subjects were 12 German-speaking adults who suffered from conductive or mixed hearing loss. The upper bone conduction threshold limit was set to 45 dB HL at frequencies between 500 Hz and 4 kHz. INTERVENTION: Implantation of a transcutaneous bone conduction hearing implant. MAIN OUTCOME MEASURES: Subjects' speech perception (word recognition scores and SRT 50%) and audiometric thresholds (air conduction, bone conduction and sound field at frequencies 500 Hz to 8 kHz) were assessed preoperatively, 1 month postoperatively and 3 months postoperatively. The subjects were monitored for adverse events and given a questionnaire to assess their satisfaction levels. RESULTS: Speech perception as measured by word recognition scores and SRT 50% improved on average about 78.8% and 25 dB HL, respectively, 3 months after implantation. Aided thresholds also improved postoperatively at all tested frequencies and continued to improve from 1 to 3 months postoperatively. Air conduction and bone conduction thresholds showed no significant changes, confirming that subjects' residual unaided hearing was not deteriorated by the treatment. Only minor adverse events were reported and resolved by the end of the study. CONCLUSION: The new transcutaneous bone conduction implant was demonstrated to be safe and effective in adults up to 3 months of device use.

New HRCT-based measurement of the human outer ear canal as a basis for acoustical methods.

PURPOSE: As the form and size of the external auditory canal determine its transmitting function and hence the sound pressure in front of the eardrum, it is important to understand its anatomy in order to develop, optimize, and compare acoustical methods. METHOD: High-resolution computed tomography (HRCT) data were measured retrospectively for 100 patients who had received a cochlear implant. In order to visualize the anatomy of the auditory canal, its length, radius, and the angle at which it runs were determined for the patients' right and left ears. The canal's volume was calculated, and a radius function was created. RESULTS: The determined length of the auditory canal averaged 23.6 mm for the right ear and 23.5 mm for the left ear. The calculated auditory canal volume (Vtotal) was 0.7 ml for the right ear and 0.69 ml for the left ear. The auditory canal was found to be significantly longer in men than in women, and the volume greater. CONCLUSION: The values obtained can be employed to develop a method that represents the shape of the auditory canal as accurately as possible to allow the best possible outcomes for hearing aid fitting.

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

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

Power stapes: an alternative method for treating hearing loss in osteogenesis imperfecta?

OBJECTIVE: To present power stapes, stapedotomy, and middle ear implantation with Vibrant SoundBridge (VSB) performed in a one-step surgery as an alternative option for hearing rehabilitation in patients with osteogenesis imperfecta (OI). STUDY DESIGN: Retrospective case series. SETTING: Tertiary referral ear center. PATIENTS: A family with genetically proven OI Type I. INTERVENTIONS: Two patients, mother and son, with severe to profound mixed hearing loss underwent 3 power stapes, 1 unilateral and 1 bilateral sequential. MAIN OUTCOME MEASURES: Thorough audiological diagnostic batteries including aided and unaided pure-tone and free-field audiometry and Freiburg monosyllabic word test were used to assess the preoperative status and the postoperative hearing outcome. High-resolution computed tomography of the temporal bones was performed as well. Surgical procedure and any special considerations were analyzed in detail. RESULTS: The hearing outcome was favorable in all cases, showing in comparison to the preoperative values an average improvement of 36.8 dB. Severe intraoperative bleeding of the middle ear mucosa was the only complication and could be easily controlled by allowing short time intervals. Inner ear trauma did not occur in any case. CONCLUSION: Power stapes represents a safe and promising procedure for treating hearing loss in selected patients with OI. Furthermore, it introduces a new, advantageous VSB application in cases of mixed hearing loss with severe otosclerosis and increased bone-conduction thresholds.

A biomechanical ear model to evaluate middle-ear reconstruction.

In order to evaluate the efficiency of middle-ear prostheses in near-real conditions, an artificial model was developed that approximately simulates the actual geometrical and biomechanical properties of the ear system (excluding the ossicular chain). The sound transmission characteristics of selected commercial middle-ear prostheses and of a synthetic test material were measured using laser Doppler vibrometry (LDV) in this model. The model's realistic properties enabled clinical tympanometry to be used to control the stiffness. In addition the influences of the implant mass on transmission characteristics were investigated. With an averaged displacement between 10 and 100 nm/Pa up to 2000 Hz, the transmission characteristic of the model was comparable with data obtained from the intact middle ear in temporal bone experiments. From the acoustical point of view, no significant material-specific differences could be found. Increasing the mass of the implants to more than 50 mg results in poorer acoustic transmission. In general, changes to the stiffness involving compliance values greater than 3.5 ml and smaller than 0.2 ml led to poorer acoustic transmission.

Normative data of multifrequency tympanometry in rabbits.

In an experimental study, we evaluated acoustic immittance in rabbits in order to use these data as normative values for further experimental investigations. This study is the first experimental evaluation of both conventional 226 Hz and multifrequency tympanometry (MFT) in rabbits. For the investigation, we used 33 female New Zealand rabbits weighing 3.2-4.4 kg and aged six months. Bilateral measurements using conventional 226 Hz and MFT were performed under general anaesthetic. A 226 Hz tympanogram was recorded for all animals by conducting an air pressure sweep from +200 to -400 daPa at a rate of 50 daPa/s. Subsequent tympanograms were recorded over a wide frequency range from 250 to 2000 Hz. The acoustic impedance device used in this study provided reproducible and evaluable tympanograms. The applied tone frequency of 226 Hz proved to be especially suitable for determining compliance. Normative data obtained from our study reveal the resonance frequency to be 1368 +/- 205 standard deviation (SD) for the right side and 1413 +/- 216 SD for the left side. The values for physiological acoustic immittance of the middle ear in the rabbit obtained here can serve as normative data in subsequent experimental animal studies.

Multifrequency tympanometry: experimental application after implantation of ossicular replacement prosthesis in rabbits.

HYPOTHESIS: We used multiple-frequency tympanometry (MFT) to evaluate the influence of a newly developed ossicular replacement prosthesis on transmission characteristics of middle ear. BACKGROUND: Multiple-frequency tympanometry is a technique for evaluating the emittance of the middle ear over a wide frequency range. It has been shown to be sensitive to certain middle ear conditions that are not detected by conventional 226-Hz tympanometry. In the field of experimental evaluation, MFT has been shown in certain animal studies to be useful in monitoring diseases. METHODS: Thirty-six prostheses composed of titanium dioxide ceramic were implanted into the right middle ear of female rabbits. Bilateral measurements using conventional 226-Hz and MFT were performed before implantation and after 28, 84, and 300 days postoperatively. The results of the preoperative examinations yielded reference values for physiological resonance frequency. After dissecting the temporal bone, we opened the middle ear and analyzed both the surrounding tissue and the position of the prosthesis. RESULTS: The constant values for compliance revealed by both preoperative and postoperative measurements indicate good reproducibility of 226-Hz tympanometry. Postoperatively, resonance frequency increased continuously up to the 300th day. The observation supports the assumption that the higher stiffness level of connective tissue influenced resonance frequency. CONCLUSION: The reference values in this study can serve as guidelines for further experimental trials.

Histological evaluation of novel ossicular chain replacement prostheses: an animal study in rabbits.

CONCLUSION: The improved biocompatibility of Bioverit II coated with a nanostructured surface shows promising qualities for use in human reconstructive middle ear surgery. In the case of chitosan-hydroxyapatite composite prostheses, further investigations regarding composition of the material, degree of purity and design are necessary before clinical application. OBJECTIVE: The selection of optimal materials for reconstructive middle ear surgery continues to be a problem. In the present study novel materials were tested as total ossicular replacement prostheses (TORPs) in an animal model. MATERIALS AND METHODS: Bioverit II coated with a nanostructured surface and chitosan-hydroxyapatite composites were placed in the middle ear of 40 rabbits. Uncoated Bioverit II was used as control. After an implantation period of 28, 84 or 300 days petrous bones were extracted, embedded in epoxy resin and examined by light microscopy. RESULTS: Uncoated and coated Bioverit prostheses revealed a mucosal coverage and a little osseogenic response after 28 days. The results of the coated Bioverit prostheses slightly surpassed those of the plain prostheses. Chitosan-hydroxyapatite composite prostheses were mostly found to be dislocated after 28 days. Formations of granulation tissue and fibrotic capsules were observed around these implants. This reaction could be caused by the instability of the composite material or may be due to impurities present in the chitosan.