Estimating vibration artifacts in preclinical experimental assessment of actuator efficiency in bone-conduction hearing devices.

OBJECTIVES: Test feasibility of a means to distinguish artifact from relevant signal in an experimental method for pre-clinical assessment of bone conduction (BC) stimulation efficiency based on measurement of intracochlear pressure (ICP). METHODS: Experiments were performed on fresh-frozen human temporal bones and cadaver heads. In a first step, fiber optic pressure sensors inserted into the cochlea through cochleostomies were intentionally vibrated to generate relative motion versus the stationary specimen, and the resulting ICP artifact recorded, before and after attaching the sensor fiber to the bone with glue. In a second step, BC stimulation was applied in the conventional location for a commercial bone anchored implant, as well as two alternative locations closer to the otic capsule. Again, ICP was recorded and compared with an estimated artifact, calculated from the previous measurements with intentional vibration of the fiber. RESULTS: Intentional vibration of the sensor fiber creates relative motion between fiber and bone, as intended, and causes an ICP signal. The stimulus does not create substantial promontory vibration, indicating that the measured ICP is all artifact, i.e. would not occur if the sensor were not in place. Fixating the sensor fiber to the bone with glue reduces the ICP artifact by at least 20 dB. BC stimulation also creates relative motion between sensor fiber and bone, as expected, from which an estimated ICP artifact level can be calculated. The ICP signal measured during BC stimulation is well above the estimated artifact, at least in some specimens and at some frequencies, indicating "real" cochlear stimulation, which would result in an auditory percept in a live subject. Stimulation at the alternative locations closer to the otic capsule appear to result in higher ICP (no statistical analysis performed), indicating a trend towards more efficient stimulation than at the conventional location. CONCLUSIONS: Intentional vibration of the fiber optic sensor for measurement of ICP can be used to derive an estimate of the artifact to be expected when measuring ICP during BC stimulation, and to characterize the effectiveness of glues or other means of reducing the artifact caused by relative motion of fiber and bone.

Healthcare consumption among subjects with otitis media undergoing middle ear surgery-analysis of cost drivers.

PURPOSE: To map healthcare utilized by subjects with chronic otitis media, with or without cholesteatoma and perform a cost analysis to determine key drivers of healthcare expenditure. METHODS: A registry study of 656 adult subjects with chronic otitis media that underwent a middle ear surgery between 2014 and 2018. Healthcare contacts related to all publicly funded specialist ENT care, audiological care and primary care for a disease of the ear and mastoid process were extracted. The data are extracted from the Swedish National Patient Registry on subjects that reside in western Sweden. RESULTS: Subjects made 13,782 healthcare contacts at a total cost 61.1 million SEK (6.0 million EUR) between 2014 and 2018. The mean cost per subject was 93,075 SEK (9071 EUR) and ranged between 3971 SEK (387 EUR) and 468,711 SEK (45,683 EUR) per individual. In the most expensive quartile of subjects, mean cost was 192,353 SEK (18,747 EUR) over the 5-year period. These subjects made 3227 ENT contacts (roughly four each year) and 60% of total costs were associated with in-patient ENT care. CONCLUSION: Patients with chronic otitis media are associated with high ENT resource utilization that does not diminish after surgical intervention and the disease places a long-term burden on healthcare systems. Significant costs are attributed to revision surgeries, indicating that these patients could be managed more effectively. In many such cases, reoperation cannot be avoided, especially due to recurrence of cholesteatoma. However, in some patients, when the indication for subsequent surgery is only hearing improvement, alternative options, such as hearing aids or implants, should also be considered. This is especially true in difficult cases, where revision ossiculoplasty is likely.

Direct cost of cochlear implants in Germany - a strategic simulation.

BACKGROUND: Despite the current undersupply of cochlear implants (CIs) with simultaneously increasing indication, CI implantation numbers in Germany still are at a relatively low level. METHODS: As there are hardly any solid forecasts available in the literature, we develop a System Dynamics model that forecasts the number and costs of CI implantations in adults for 40 years from a social health insurance (SHI) perspective. RESULTS: CI demand will grow marginally by demographic changes causing average annual costs of about 538 million €. Medical-technical progress with following relaxed indication criteria and patients' increasing willingness for implantation will increase implantation numbers significantly with average annual costs of 765 million €. CONCLUSION: CI demand by adults will increase in the future, thus will the costs for CI supply. Continuous research and development in CI technology and supply is crucial to ensure long-term financing of the growing CI demand through cost-reducing innovations.

Lifetime cost of unilateral cochlear implants in adults: a Monte Carlo simulation.

BACKROUND/OBJECTIVE: Due to increasing prevalence of hearing loss and relaxation of candidacy criteria of cochlear implant (CI) supply, the number of implantations is likely to further increase. Statutory health insurances are facing ever more urgent financing challenges since CI treatment causes high life-long costs. Additionally, increasing life expectancy and earlier implantation may extend therapy time and cost. With every case being individual, this study aims to calculate the possible lifetime cost of unilateral CI treatment in adults including stochastic uncertainties. METHODS: Taking a statutory health insurance perspective, relevant cost components of CI therapy and their values were identified. The Monte Carlo method was used to simulate lifetime cost considering age at first implantation and distributions of costrelevant variables. A sensitivity analysis was conducted to determine the most crucial variables impacting on lifetime cost. RESULTS: Lifetime cost of CI treatment varies according to age at first implantation, respectively remaining lifetime; the earlier the implantation, the higher the overall cost. According to our simulation, the average lifetime cost for an adult patient first implanted between the age of 20-80 is at 53,030 € (present value). Cost of implantation and periodic speech processor exchanges show the highest impact on the total cost. DISCUSSION: Health care systems could face rising expenses for CI supply by technical development. Innovative life-long CIs could achieve significant savings per case that could finance additional implant cost. Until then, further targeted research will be required. CONCLUSION: CI-related cost for statutory health insurance crucially depends on the patient-side demand for cochlear implants. Therefore, cost forecasts must also consider the development of demand.

Workflow assessment as a preclinical development tool : Surgical process models of three techniques for minimally invasive cochlear implantation.

PURPOSE: Minimally invasive cochlear implant surgery is a challenging procedure due to high demands on accuracy. For clinical success, an according assistance system has to compete against the traditional approach in terms of risk, operating time and cost. It has not yet been determined what kind of system is the most suited. The purpose of this study is a proof of concept of surgical process modeling as a preclinical development tool and the comparison of workflow concepts for this new approach. METHODS: Three preclinical systems (two stereotactic and one robotic) for minimally invasive cochlear implant surgery are compared using the method of surgical process modeling. All three systems were successfully tested with ex vivo human specimen to create minimally invasive surgical access to the cochlea. Those systems where chosen for comparison, because they represent three diverse approaches with different corresponding workflows for the same intervention. The experiments were used to create a process model for each system by recording the interventions. RESULTS: All three conceptual systems developed by our group have shown their eligibility. The recorded process models provide a convenient method for direct comparison. Reduction in the surgical time has a higher impact on the process, than time that is needed for setting up a system beforehand. The stereotactic approaches have little preparation effort and are low cost in terms of hardware compared to the robotic approach, which in return is beneficial in terms of workload reduction for the surgeon. CONCLUSION: Surgical process modeling is suitable for comparison of different assistant systems for minimally invasive cochlear implantation. The benefit of reduced trauma, compared to the traditional mastoidectomy, can now be assessed with consideration of the workflow of each technique. The process models enable an assessment in the regard of surgical time and workload.

Hearing Protection, Restoration, and Regeneration: An Overview of Emerging Therapeutics for Inner Ear and Central Hearing Disorders.

OBJECTIVE: To provide an overview of biotechnology and pharmaceutical companies active in the field of inner ear and central hearing disorders and their therapeutic approaches. METHODS: Scientific and grey literature was searched using broad search terms to identify companies and their hearing-related therapeutic approaches. For each approach its lead indication, product, therapeutic modality, target, mechanism of action and current phase of clinical development was collated. RESULTS: A total of 43 biotechnology and pharmaceutical companies have been identified that are developing therapeutics for inner ear and central hearing disorders. Their therapeutics include drug-, cell- and gene-based approaches to prevent hearing loss or its progression, restore hearing, and regenerate the inner ear. Their therapeutic targets and specific mechanisms of action are wide-ranging, reflecting the complexity of the hearing pathways and the diversity of mechanisms underlying inner ear disorders. While none of the novel products under investigation have yet made it to the clinical market, and a large proportion are still at preclinical phase, many therapeutics have already entered clinical testing with more expected to do so in the next few years. CONCLUSION: A wide range of novel therapeutics targeting different hearing, balance and tinnitus pathways, and patient populations are approaching the clinical domain. It is important that clinicians involved in the care of patients with hearing loss prepare for what may become a radically different approach to the management of hearing disorders, and develop a true understanding of the new therapies' mechanisms of action, applications, and indications.

Feasibility Assessment of Optical Coherence Tomography-Guided Laser Labeling in Middle Cranial Fossa Approach.

INTRODUCTION: Different approaches have been developed to find the position of the internal auditory canal (IAC) in middle cranial fossa approach. A feasibility study was performed to investigate the combination of cone beam computed tomography (CBCT), optical coherence tomography (OCT), and laser ablation to assist a surgeon in a middle cranial fossa approach by outlining the internal auditory canal (IAC). MATERIALS AND METHODS: A combined OCT laser setup was used to outline the position of IAC on the surface of the petrous bone in cadaveric semi-heads. The position of the hidden structures, such as IAC, was determined in MATLAB software using an intraoperative CBCT scan. Four titanium spheres attached to the edge of the craniotomy served as reference markers visible in both CBCT and OCT images in order to transfer the plan to the patient. The integrated erbium-doped yttrium aluminum garnet laser was used to mark the surface of the bone by shallow ablation under OCT-based navigation before the surgeon continued the operation. RESULT: The technical setup was feasible, and the laser marking of the border of the IAC was performed with an overall accuracy of 300 µm. The depth of each ablation phase was 300 µm. The marks indicating a safe path supported the surgeon in the surgery. CONCLUSION: The technique investigated in the present study could decrease the surgical risks for the mentioned structures and improve the pace and precision of operation.

Aplasia of the cochlea: radiologic assessment and options for hearing rehabilitation.

OBJECTIVE: Hearing rehabilitation of patients with severe inner ear malformations remains controversial. Our objective was to describe the radiologic findings of aplasia of the cochlea (AC) and evaluate the existing therapeutic options in such patients. STUDY DESIGN: Retrospective cohort study. SETTING: Tertiary referral center. PATIENTS: Pediatric and adult patients with AC evaluated at our institution from 1995 to 2010. INTERVENTIONS: The precise radiologic findings were identified using high-resolution computed tomography (HRCT) and magnetic resonance imaging (MRI) scans of the inner ear. In cases of auditory implantation on the AC side, the achieved outcome was recorded using categories of auditory performance (CAP). Related surgical aspects were analyzed. RESULTS: Twenty-three patients (28 ears) with AC were found. In 5 patients AC was bilateral. The remaining unilateral cases had contralateral normal ears (2 patients), cochlea hypoplasia (5 patients), common cavity (6 patients), incomplete partition Type I (4 patients), and atresia of the internal auditory canal (1 patient). Four patients (3 bilateral, 1 unilateral ACs) were treated with cochlear implants in ears with AC, and 1 patient underwent auditory brainstem implantation. All implanted patients achieved speech perception with limited vocabulary (CAP scores between 4 and 5). CONCLUSION: AC is defined as the total absence of the cochlea, with a present, although malformed, vestibule. Although a distinct auditory nerve was not seen in these cases of AC, results following cochlear implantation suggest functional cochlear nerve fibers in the remaining dysplastic inner ear structures. In selected cases, cochlear implantation may be a reasonable option for the habilitation of deafness associated with AC.

Cochlear implantation in different health-care systems: disparities between Germany and the United States.

INTRODUCTION: Cochlear implantation is a popular procedure to restore hearing in patients with severe-to-profound hearing loss. Despite the widespread acceptance of the intervention, many variables exist in the evaluation for and implementation of this technology throughout the world. The primary aim of this investigation is to analyze treatment disparities between Germany and the United States in cochlear implantation. MATERIALS AND METHODS: Cochlear implant recipients in 2 representative cochlear implant centers in the United States and Germany were retrospectively analyzed. Differences in preoperative, perioperative, and postoperative treatment paradigms as well as the disparities in the follow-up were recorded. Objective measures included demographic data, length of hospitalization, minor and major complication rates, and speech scores within the first 3 years. Moreover, a cost analysis comparison between both centers was performed. RESULTS: A number of differences in treatment were noted between the two centers. The primary difference was that in Germany the procedure was inpatient with an average 4-day hospital stay, whereas in the United States, it was an outpatient procedure. Despite these differences, only small differences were noted in the category of minor complications, and no differences were seen in the category of major complications between the 2 centers. Comparing the results of monosyllabic speech tests, no major differences could be detected. Cost analysis between the 2 centers demonstrates that, whereas in Germany, all charges are covered by the statutory health insurance, in the United States, the reimbursements are significantly lower than the charges. DISCUSSION: Despite differences in the clinical approach to cochlear implants in Germany versus the United States, no significant differences in outcomes were seen in the 2 groups, and the complication rates were nearly identical. Interestingly, although the procedure in Germany is associated with a 4-day hospital stay, the charges for the entire procedure in Germany are approximately ½ as compared with those in the United States, although the actual reimbursement for this procedure may be lower in the United States than in Germany.

Time of cochlear implant surgery in academic settings.

OBJECTIVE: Establish the time required to perform cochlear implantation (CI) in academic settings. STUDY DESIGN: Historical cohort study. SETTING: German and American academic centers. PATIENTS: A total of 2639 patients underwent CI (1997-2007). We excluded patients receiving an experimental device or technique and those with abnormal cochlear anatomy or incomplete charts, leaving 2253 for analysis. INTERVENTION: Unilateral, bilateral, and revision CI with devices approved in the U.S. and Europe. MAIN OUTCOME MEASURES: Mean surgical time (ST) and total operating room time (TORT). RESULTS: Mixed model analysis was used; estimated marginal means were calculated in minutes after adjusting for random effect of individual surgeon. There were no differences between unilateral (ST = 171, TORT = 245) and revision CI (ST = 160, TORT = 232), but bilateral procedures were longer (ST = 295, TORT = 377, P < 0.001). In unilateral surgeries, Cochlear Limited (CL) devices were implanted faster (ST = 165, TORT = 225) than Advanced Bionics (ABC) (ST = 183, P = 0.001; TORT = 240, P = 0.023) or MedEl (ST = 193, P < 0.001; TORT = 253, P = 0.002) devices. There were no differences for unilateral CI between ABC and MedEl devices. For revision CI, ABC devices (ST = 141, TORT = 219) were implanted faster than CL devices (ST = 181, P = 0.001; TORT = 266, P < 0.001). There were no differences by age group or between Germany and the U.S. ST and TORT were shorter for 575 CIs performed in the final two years of the study (unilateral CI: ST = 145, TORT = 209; bilateral CI: ST = 259, TORT = 330; revision CI: ST = 138, TORT = 205). For unilateral CI, ST and TORT decreased yearly (linear regression, P < 0.001) and inversely correlated with surgeon experience (linear regression, P < 0.01). CONCLUSIONS: We report the time required to perform CI in academic settings-data that are vital for cost-benefit analyses and assessing new CI techniques.

Cost-benefit analysis of pediatric cochlear implantation: German experience.

HYPOTHESIS: To explore, from the payers' perspective, the cost-benefit ratio of pediatric cochlear implantation for congenitally deaf and prelingually deafened children compared with children with hearing aids. The study should verify the hypothesis that educational and associated costs increase with age at implantation and that these can be below costs for children with hearing aids. METHODS: Children who received implants at the Medical University of Hanover at different ages (Group 1, 0-1.9 yr; Group 2, 2-3.9 yr; Group 3, 4-6.9 yr) were compared with deaf children using hearing aids (Group 4). Sick funds were the payers for direct and indirect costs, and public authorities were the payers for educational costs. Educational settings were used to measure for benefits. All costs related to the hearing deficiency were included up to the age of 16 years on the basis of 1999 currency values. A scenario analysis was used to explore the impact of variation of costs and discount rates. RESULTS: Total costs for the three age groups of children with implants were from euro 138,000 (approximately US$113,100) to euro 177,000 (approximately US$152,700), compared with euro 160,000 (approximately US$138,000) for hearing aid users. CONCLUSION: This study supports the view that pediatric cochlear implantation provides positive cost-benefit ratios compared with hearing aid users, depending on the age at implantation. Implantation is strongly recommended from the payers' perspective for children implanted before the age of 2 years.

Auditory brainstem implant part II: subjective assessment of functional outcome.

UNLABELLED: OBJECTIVE The purpose of this study was to present the patients' recommendations and judgments about their hearing and communication abilities with the help of the auditory brainstem implant. STUDY DESIGN: Prospective study. SETTING: Tertiary referral center. PATIENTS AND METHODS: This evaluation was based on the data obtained by the self-administered questionnaires designed for the European Auditory Brainstem Implant Multicenter Clinical Trial. Eleven patients who had used their auditory brainstem implant for a minimum of 6 months to a maximum of 41 months were evaluated with the help of these questionnaires. RESULTS: All the patients had used their implant on a regular daily basis for an average of 13 hours per day. None of them experienced any side effects during the daily use of the device. Nine patients (82%) used their auditory brainstem implant in both quiet and noisy surroundings. The most common cause of disturbance was a noisy surrounding. All the patients were able to distinguish speech from environmental sounds. The role of the auditory brainstem implant in differentiating various environmental sounds was considered to be very useful by 9 patients (82%). As an adjuvant to lip-reading, the auditory brainstem implant was considered most useful for understanding speech in quiet surroundings. DISCUSSION AND CONCLUSION: It was concluded that the auditory brainstem implant is an effective support for receiving and, to some degree, differentiating environmental sounds, and that as an adjuvant to lip-reading, it enhances speech perception, especially in quiet surroundings. A comparison between the results of this study and the results of the audiologic tests presented in Part I of this study (published earlier) revealed that patient satisfaction was not directly correlated with the results of the objective auditory tests. In general, patients' judgments of their individual hearing and communication abilities usually rated higher than could have been predicted by the objective audiometric data.