Bilateral cochlear implantation.

Binaural hearing has certain benefits while listening in noisy environments. It provides the listeners with access to time, level and spectral differences between sound signals, perceived by the two ears. However, single sided deaf (SSD) or unilateral cochlear implant (CI) users cannot experience these binaural benefits due to the acoustic input coming from a single ear. The translational research on bilateral CIs started in the year 1998, initiated by J. Müller and J. Helms from Würzburg, Germany in association with MED-EL. Since then, several clinical studies were conducted by different research groups from across the world either independently or in collaboration with MED-EL. As a result, the bilateral CI has become the standard of care in many countries along with reimbursement by the health care systems. Recent data shows that children particularly, are given high priority for the bilateral CI implantation, most often performed simultaneously in a single surgery, as the binaural hearing has a positive effect on their language development. This article covers the milestones of translational research from the first concept to the widespread clinical use of bilateral CI.

Special electrodes for demanding cochlear conditions.

Optimal matching of an electrode array to the cochlear anatomy plays a key role in bringing the best benefit of CI technology to the users. Even within the category of normal anatomy cochlea, the size variation is huge justifying MED-EL's FLEX electrode array to be available in five different lengths. Within the malformed inner-ear category the anatomical variation is huge, convincing MED-EL to custom-design the electrode array as per the request from the operating surgeons. Thanks to G. Bredberg, M. Beltrame, L. Sennaroglu, J. Gavilan, S. Plontke, T. Lenarz, J. Müller, and few others for their valuable suggestions on unique electrode designs satisfying various needs. Translational research efforts at MED-EL in cooperation with CI surgeons from across the world led to the implantation of a variety of electrode array designs in patients with special cochlear needs.

CI in single-sided deafness.

The cochlear implant (CI) as a treatment option for single-sided deafness (SSD) started with a clinical study looking in to the influence of cochlear implantation with a MED-EL device on incapacitating unilateral tinnitus in SSD. The study began in 2003 and was conducted by P. Van de Heyning and his team in Antwerp, Belgium. The first CI in SSD without tinnitus in Germany was implanted by J. Mueller and R. Jacob in Koblenz in 2005. Translational research activities took place since then to evaluate the CI as a treatment option for SSD not only in adults but also in children. They assessed the hearing performance of SSD patients implanted with CI, importance of long electrode arrays in SSD patients, degree of acceptance of CI by SSD children, importance of early CI implantation in SSD children in developing language skills, music enjoyment by hearing with two ears and evidence on spiral ganglion cell body distribution. In 2013, MED-EL was the first CI manufacturer to receive the CE mark for the indication of SSD and asymmetric hearing loss (AHL) in adults and children. In 2019, MED-EL was the first CI manufacturer to get its CI device approved for patients over the age of five with SSD and AHL, by the FDA in the USA. This article covers the milestones of translational research from the first concept to the widespread clinical use of CI in SSD.

EAS-Combined electric and acoustic stimulation.

Electric-acoustic stimulation (EAS) is a special treatment modality for those patients who are profoundly deaf in the high-frequency (HF) region and retain usable hearing in the low-frequency (LF) region. Combining the electric stimulation with cochlear implant (CI) in the HF and acoustic amplification of residual hearing using a conventional hearing aid (HA) in the LF region defines EAS. The EAS concept was first proposed by C. von Ilberg from Frankfurt, Germany in the year 1997. In association with MED-EL, all the necessary safety studies were performed in non-human subjects before the first patient received it in 1997. In association with MED-EL, all the necessary safety studies were performed in non-human subjects before the first patient received it in 1999. For the patient to successfully use the EAS concept, the residual hearing needs to be preserved to a high extent and for several years. This requires a highly flexible electrode array in safeguarding the intra-cochlear structures during and after the CI electrode array insertion. Combining the HA unit with the audio processor unit of the CI was necessary for the convenient wearing of the unified audio processor. Fitting of the unified audio processor is another important factor that contributes to the overall success of the EAS treatment. The key translational research efforts at MED-EL were on the development of flexible electrodes, a unified audio processor, innovations in the fitting process, intra-operative monitoring of cochlear health during electrode insertion, pre-operative soft-ware tool to evaluate the cochlear size and electrode selection and some new innovations tried within EAS topic. This article covers the milestones of translational research from the first concept to the widespread clinical use of EAS.

Signal processing & audio processors.

Signal processing algorithms are the hidden components in the audio processor that converts the received acoustic signal into electrical impulses while maintaining as much relevant information as possible. Signal processing algorithms should be smart enough to mimic the functionality of external, middle and the inner-ear to provide the cochlear implant (CI) user with a hearing experience as natural as possible. Modern sound processing strategies are based on the continuous interleaved sampling (CIS) strategy proposed by B. Wilson in 1991, which provided envelope information over several intracochlear electrodes. The CIS strategy brought significant gains in speech perception. Translational research activities of MED-EL resulted in further improvements in speech understanding in noisy environments as well as enjoyment of music by not only coding CIS-based envelope information, but by also representing temporal fine structure information in the stimulation patterns of the apical channels. Further developments include "complete cochlear coverage" made possible by deep insertion of the intracochlear electrode, elaborate front end processing, anatomy based fitting (ABF), triphasic pulse stimulation instrumental in the suppression of facial nerve stimulation, and bimodal delay compensation allowing unilateral CI users to experience hearing with hearing aids on the contralateral ear. The large number of hardware developments might be exemplified by the RONDO, the world's first single unit audio processor in 2013. This article covers the milestones of translational research around the signal processing and audio processor topic that took place in association with MED-EL.

Drug delivery in cochlear implantation.

Intra-cochlear fibrous tissue formation around the electrode following cochlear implantation affects the electrode impedance as well as electrode explantation during reimplantation surgeries. Applying corticosteroids in cochlear implantation is one way of minimizing the intra-cochlear fibrous tissue formation around the electrode. It were J. Kiefer, C. von Ilberg, and W. Gstöttner who proposed the first idea on drug delivery application in cochlear implantation to MED-EL in the year 2000. During the twenty years of translational research efforts at MED-EL in collaboration with several clinics and research institutions from across the world, preclinical safety and efficacy of corticosteroids were performed leading to the final formulation of the electrode design. In parallel to the drug eluting CI electrode development, MED-EL also invested research efforts into developing tools enabling delivery of pharmaceutical agents of surgeon's choice inside the cochlea. The inner ear catheter designed to administer drug substances into the cochlea was CE marked in 2020. A feasibility study in human subjects with MED-EL CI featuring dexamethasone-eluting electrode array started in June 2020. This article covers the milestones of translational research towards the drug delivery in CI application that took place in association with MED-EL.

Pediatric cochlear implantation: A quarter century in review.

Objective: To review the growth of a pediatric cochlear implant (CI) program at one large tertiary care medical center over a 25-year period in order to (1) describe the population of pediatric cochlear implant recipients, (2) document word recognition outcomes, and (3) describe changes in candidacy criteria over time. Design: A retrospective review of population demographics and trends included etiology of hearing loss, device use and type, expansion of inclusion criteria, and word recognition outcomes. Results: Ninety-one percent of the children studied were from North Carolina and reflect the ethnic distribution of the state. The population is heterogeneous for etiology and the presence of syndromes and/or co-morbidities. A trend of lower age of implant and greater residual hearing was documented overtime. As a single metric, monosyllable word recognition for the children assessed is good with the mean CNC test word score of 76.13% (range 0-100, S.D = 19.94). Conclusions: Pediatric cochlear implant candidacy criteria have evolved despite no change in FDA-approved regulations since 2000. There is great diversity among recipients but word recognition outcomes are generally good in this population and have improved over time. Professionals who may refer children for cochlear implantation should be aware of current clinical practices and general outcomes.

¿Qué es un implante coclear? / What is a cochlear implant?

La hipoacusia representa un importante problema de salud. La dificultad de oír y comunicarse es frustrante para las personas provocando aislamiento social, baja autoestima y muchas veces se acompaña de depresión. Según la Organización Mundial de la Salud (OMS), hoy en día se estima que 360 millones de personas en el mundo viven con pérdida auditiva incapacitante. En Argentina nacen aproximadamente 700.000 chicos por año; de estos, entre 1 y 3 de cada mil tienen hipoacusia. La discapacidad auditiva constituye el 18 por ciento de las discapacidades en el país, la cual se reparte en un 86,6 por ciento de dificultad auditiva y un 13,4 por ciento de sordera. El implante coclear es un producto sanitario implantable activo, de alta tecnología y precisión, encaminado a restablecer la audición de aquellas personas que padezcan una sordera causada por la destrucción de las células ciliadas de la cóclea, estimulando directamente las células ganglionares (nervio auditivo) mediante señales eléctricas encargadas de transmitir la información codificada al cerebro. Hay que recordar que, al ser una prótesis, no cura definitivamente la sordera. Hay muy pocas tecnologías sanitarias que se hayan desarrollado tan rápidamente como el Implante Coclear (AU)

Hearing loss is a major health problem. Difficulties in hearing and communicating are frustrating leading to social isolation, low self-esteem and are often associated with depression. According to the World Health Organization (WHO), currently it is estimated that 360 million people in the world live with disabling hearing loss. In Argentina, approximately 700,000 children are born per year; of these, between 1 and 3 each 1,000 have hearing loss. Hearing impairment accounts for 18 percent of disabilities in the country, of which 86.6% consists of hearing loss and 13.4% of deafness. The cochlear implant is a high-technology and high-precision active implantable device aimed at restoring the hearing in individuals who suffer from deafness caused by the destruction of the ciliated cells of the cochlea, directly stimulating the ganglion cells (auditory nerve) through electrical signals that transmit codified information to the brain. It is important to consider that, being a prosthesis, it does not definitively cure deafness. There are very few technological health devices that have been developed as rapidly as the cochlear implant (AU)

[The history of cochlear implantation]. / Istoriya kokhlearnoi implantatsii.

The creation of cochlear implants has become possible owing to the collaboration in the field of neurophysiology, otorhinolaryngology, audiology, engineering, and psychoacoustics. The experiments carried out in the 1930s were not directly associated with the electrical stimulation of the auditory nerve but had a significant influence on the development of cochlear implants. The first attempt at direct electrical stimulation of the auditory nerve was performed in 1957 using a device that consisted of an active electrode and an implantable induction coil. A good discrimination of intensity but poor frequency discrimination of the acoustic stimuli in a deaf patient was achieved. In 1985, the cochlear implants were approved for the treatment of the adult patients and in 1990 for the children at the age under 2 years. Multi-channel cochlear implantation has been carried out in Russia since 1991 although the efforts to introduce singe-channel implantation were made in the 1980s. Nowadays, there are more than 8000 cochlear implant users in the Russian Federation. Cochlear implantation is performed in a number of clinical centres in several regions of the country funded from the federal budget.

The role of the Utah Artificial Ear project in the development of the modern cochlear implant.

The cochlear implant has provided the first substantial restoration of a human sense by a medical intervention. This accomplishment was brought about by the efforts, over a 50+ year period, of many individuals in laboratories around the world. In this paper, we recount the history of one of the early projects - the Utah Artificial Ear project. In 1970 researchers at the University of Utah began work on an auditory prosthesis. A critical early decision was to create a 'transparent' link between external signal processing and the electrodes implanted in the cochlea, i.e., a percutaneous pedestal. The pedestal allowed D. Eddington, then a graduate student, to conduct, in 1975-1978, the first thorough, parametric, psychophysical studies of electrical stimulation of the cochlea in multiple human volunteers. The early work by Eddington and colleagues evolved in 1983 into the 4-channel, Ineraid cochlear implant. Many years later, highly effective, modern signal processing algorithms, e.g., continuous interleaved sampling (CIS), fine structure processing (FSP), and virtual channel processing, were first tested and developed with the aid of Ineraid patients fit with pedestals of the Utah design. Because for many years the Ineraid provided as high a level of speech understanding as that provided by other devices and because the percutaneous pedestal allowed the first testing of many modern signal processing algorithms, the Utah Artificial Ear project may be viewed as one of the most valuable research projects in the history of cochlear implants.