Astrid Wolf-Magele

Sheep as a Large Animal Model for Middle and Inner Ear Implantable Hearing Devices: A Feasibility Study in Cadavers

Objective Currently, no large animal model exists for surgical-experimental exploratory analysis of implantable hearing devices. In a histomorphometric study, we sought to investigate whether sheep or pig cochleae are suitable for this purpose and whether device implantation is feasible. Methods Skulls of pig and sheep cadavers were examined using high-resolution 128-slice computed tomography (CT) to study anatomic relationships. A cochlear implant and an active middle ear implant could be successfully implanted into the sheep’s inner and middle ear, respectively. Correct device placement was verified by CT and histology. The cochlear anatomy of the sheep was further studied by micro-CT and histology. Results Our investigations indicate that the sheep is a suitable animal model for implantation of implantable hearing devices. The implantation of the devices was successfully performed by access through a mastoidectomy. The histologic, morphologic, and micro-CT study of the sheep cochlea showed that it is highly similar to the human cochlea. The temporal bone of the pig was not suitable for these microsurgical procedures because the middle and inner ear were not accessible owing to distinct soft and fatty tissue coverage of the mastoid. Conclusion The sheep is an appropriate large animal model for experimental studies with implantable hearing devices, whereas the pig is not.

The Bonebridge Bone Conduction Hearing Implant: indication criteria, surgery and a systematic review of the literature

Hearing aids and implants employing bone conduction (BC) stimulation have a long tradition in the treatment of conductive or mixed hearing loss, with their indications being extended in the 2000s to include single‐sided deafness (SSD). Existing percutaneous bone conduction implants (BCI) provide significant audiological gain but are associated with a high rate of complications. This has led to the development of passive transcutaneous BCIs; however, audiological benefit may be compromised. An active transcutaneous BCI, the Bonebridge, was recently introduced and first implanted in 2011 as part of a clinical trial.

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

Objective Evaluation of safety and efficacy of the Vibrant Soundbridge in the treatment of hearing loss in children and adolescents with primary focus on improvement in speech discrimination. Study Design Prospective, single-subject repeated-measures design in which each subject serves as his/her own control. Setting Tertiary referral center. Patients Nineteen patients aged 5 to 17 years. Intervention Implantation of an active middle ear implant. Main Outcome Measure Improvement in word recognition scores, speech reception thresholds, and signal-to-noise ratios (SNRs) were evaluated, in addition to air and bone conduction. Oldenburger Kids Satztest/Oldenburger Satztest sentences and Göttinger/Freiburger monosyllables at 65-dB hearing level were tested in two age groups. Results Significant speech discrimination improvement was seen in all patients after 6 months. In children 5 to 9 years old, mean monosyllable recognition improved from 28.9% (unaided) to 95.5% (Soundbridge-aided). Aided 50% sentence discrimination at 44.1 dB and SNR of −4.9 dB were measured. In patients 10 to 17 years old, mean word recognition improved from 18.5% to 89.0%, sentence reception threshold improved to 40.2 dB, and SNR to −3.6 dB. Comparison between age groups indicated a slight trend toward quicker adaptation by older subjects. However, after initial adjustment, a higher level of overall benefit was seen at 6 months in younger children. Conclusions Currently, the only middle ear implant approved for pediatric patients, the Vibrant Soundbridge, provides an option in cases of congenital aural atresia or disease-induced defects, when surgical intervention and reconstruction is indicated. The 6-month results in this comparatively large study population validated conclusions found in previous trials.

Towards a Unified Testing Framework for Single-Sided Deafness Studies: A Consensus Paper

Background: While hearing aids for a contralateral routing of signals (CROS-HA) and bone conduction devices have been the traditional treatment for single-sided deafness (SSD) and asymmetric hearing loss (AHL), in recent years, cochlear implants (CIs) have increasingly become a viable treatment choice, particularly in countries where regulatory approval and reimbursement schemes are in place. Part of the reason for this shift is that the CI is the only device capable of restoring bilateral input to the auditory system and hence of possibly reinstating binaural hearing. Although several studies have independently shown that the CI is a safe and effective treatment for SSD and AHL, clinical outcome measures in those studies and across CI centers vary greatly. Only with a consistent use of defined and agreed-upon outcome measures across centers can high-level evidence be generated to assess the safety and efficacy of CIs and alternative treatments in recipients with SSD and AHL. Methods: This paper presents a comparative study design and minimum outcome measures for the assessment of current treatment options in patients with SSD/AHL. The protocol was developed, discussed, and eventually agreed upon by expert panels that convened at the 2015 APSCI conference in Beijing, China, and at the CI 2016 conference in Toronto, Canada. Results: A longitudinal study design comparing CROS-HA, BCD, and CI treatments is proposed. The recommended outcome measures include (1) speech in noise testing, using the same set of 3 spatial configurations to compare binaural benefits such as summation, squelch, and head shadow across devices; (2) localization testing, using stimuli that rove in both level and spectral content; (3) questionnaires to collect quality of life measures and the frequency of device use; and (4) questionnaires for assessing the impact of tinnitus before and after treatment, if applicable. Conclusion: A protocol for the assessment of treatment options and outcomes in recipients with SSD and AHL is presented. The proposed set of minimum outcome measures aims at harmonizing assessment methods across centers and thus at generating a growing body of high-level evidence for those treatment options.

Intraoperative measurement for a new transcutaneous bone conduction hearing implant.

Objective To investigate the possibility of using a modified reverse transfer function (RTF) measurement intraoperatively during surgery of a new transcutaneous bone conduction hearing implant to evaluate the status of the device. Methods Tests were performed on a cadaver skull (preclinically) and two conductive hearing loss patients implanted with a new transcutaneous bone conduction implant. During intraoperative activation, the RTF was measured using a microphone attached perpendicularly and directly to the skin in the middle section of the forehead. Results The RTF could be measured for all frequencies from 500 to 6, 000 Hz. Conclusion The usage of an intraoperative RTF measurement may be a good method to verify the mechanical coupling of the bone conduction floating mass transducer and to test the functional integrity of the implant in an objective way.

Magnetic Resonance Imaging Compatibility of a New Generation of Active Middle Ear Implant: A Clinically Relevant Temporal Bone Laboratory Study.

Objective: Magnetic resonance imaging (MRI) has become an essential tool of modern medical imaging and disease diagnosis. In November 2014, a new MRI-conditional (up to 1.5 T) generation of an active middle ear implant (AMEI) was released to the market. The aim of the study was to test the MRI compatibility of the new implant system in a clinical-anatomical study. Design: Experimental cadaver head model. Setting: Temporal bone laboratory. Participants: AMEIs were implanted in 28 fixed temporal bones at three different floating mass transducer (FMT)-coupling positions (N = 8 short process of the incus, N = 16 long process of the incus, N = 4 round window). Main Outcome Measures: The position of the FMT and the integrity of the ossicular chain was monitored through microscopy, microendoscopy, and computed tomography (CT) scans before and after the MRI (1.5 T) was conducted. Proper function of the implant was tested with reverse transfer function (RTF) measurements. Results: Neither positional nor functional changes after MRI were observed. Conclusion: The new generation of the AMEI is a MRI-compatible system, which features an easier and quicker implant fixation method. The option of MRI in patients with AMEI should be taken into consideration during the preoperative discussion with potential candidates.

Postoperative changes in telemetry measurements after cochlear implantation and its impact on early activation.

Cochlear implantation is a clinically routine treatment for patients with severe sensorineural hearing loss for over 20 years. Up to now, the general recommendation for speech processor activation was 4 weeks after cochlear implantation. The aim of this study was to determine whether activation is possible at <4 weeks postop and to show the postoperative change in telemetry over time.

Improvement of sound source localization abilities in patients bilaterally supplied with active middle ear implants.

Abstract Conclusions: Patients, who are bilaterally supplied with active middle ear implants, perform slightly better in sound localization tasks than when unilaterally aided or unaided. Objectives: To investigate the impact of bilateral use of active middle ear implants on sound source localization in the horizontal plane in patients with a sloping moderate-to-severe hearing loss. Methods: Ten adults supplied with Med-EL Vibrant Soundbridge systems (VSB) in both ears participated in the study. Four listening conditions were tested: unaided, aided with VSB on left or right ear and on both sides. In each condition the subjects had to judge the direction of broadband noises delivered randomly across a semicircular array of 11 loudspeakers arranged in an anechoic chamber. Results: When unaided or bilaterally aided, the subjects localized on average 40% of the stimuli correct; when unilaterally aided (left or right), this rate dropped to 20–30% in either condition. Precision of sound localization was highest when bilaterally aided, i.e. the mean RMS angular error was 10°, and lowest when unilaterally aided, i.e. 15°. This is in line with bilateral hearing aid users, who show similar performance in sound localization tasks.

Vibrant Soundbridge in Children

Objective: The VSB is an AMEI which is approved for children. It is also used for patients with aural atresia or chronic otitis media (COM), with limited hearing rehabilitation solutions. The aim for this study is to investigate the hearing rehabilitation in children using VSB suffering from atresia or COM. Method: Standard audiological tests were performed pre- and postoperatively. CT images were acquired to assess feasibility of the FMT placement in the middle ear and to determine the Jahresdorfer score in patients with atresia. Functional gain and speech improvement are analyzed. Results: Thirteen children (median age 9.1) with congenital aural atresia or COM were implanted with the VSB. The average Jahresdorfer scale was 5.9. There were no pre- or postoperative medical complications observed, and hearing levels were preserved. The surgical technique is safe, due to the unchanged pre- versus postsurgery BC levels. CT images provide crucial information about the accessibility for the attachment of the FMT. Patients with atresia showed a functional gain of 40 dB and an improvement of 60% in speech. Patients with COM showed a functional gain of 38 dB and an improvement of 50% in speech. Conclusion: In these cases, the audiological outcome shows an effective gain in hearing and an improvement in speech. The VSB therefore offers an excellent audiological rehabilitation intact skin solution for children suffering with congential aural atresia or COM.