Cochlear Implants: System Design, Integration, and Evaluation

Depts. of Anatomy & Neurobiol., Univ. of California, Irvine, CA
IEEE Reviews in Biomedical Engineering 02/2008; 1(1):115 - 142. DOI: 10.1109/RBME.2008.2008250
Source: IEEE Xplore

ABSTRACT As the most successful neural prosthesis, cochlear implants have provided partial hearing to more than 120000 persons worldwide; half of which being pediatric users who are able to develop nearly normal language. Biomedical engineers have played a central role in the design, integration and evaluation of the cochlear implant system, but the overall success is a result of collaborative work with physiologists, psychologists, physicians, educators, and entrepreneurs. This review presents broad yet in-depth academic and industrial perspectives on the underlying research and ongoing development of cochlear implants. The introduction accounts for major events and advances in cochlear implants, including dynamic interplays among engineers, scientists, physicians, and policy makers. The review takes a system approach to address critical issues in cochlear implant research and development. First, the cochlear implant system design and specifications are laid out. Second, the design goals, principles, and methods of the subsystem components are identified from the external speech processor and radio frequency transmission link to the internal receiver, stimulator and electrode arrays. Third, system integration and functional evaluation are presented with respect to safety, reliability, and challenges facing the present and future cochlear implant designers and users. Finally, issues beyond cochlear implants are discussed to address treatment options for the entire spectrum of hearing impairment as well as to use the cochlear implant as a model to design and evaluate other similar neural prostheses such as vestibular and retinal implants.

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Available from: Haihong Feng, Oct 13, 2014
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    • "As a highly successful neural prostheses, cochlear implant have been used for many years to help patients who suffer from sensorineural hearing loss recover the sense of hearing. The cochlear implant works by directly stimulating the residual auditory nerve fibers inside the cochlea according to their naturally developed tonotopic organization [1], [2]. Despite the significant improvements that have been made in the past decades, the performance of modern cochlear implants is still far behind the healthy cochlea. "
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    • "By the late 1980s, steps 1 and 2 had been achieved and step 3 had been largely achieved (Wilson and Dorman, 2008a; Zeng et al., 2008). Both single-site and multisite systems were being applied clinically. "
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    ABSTRACT: The challenge in getting a decent signal to the brain for users of cochlear implants (CIs) is described. A breakthrough occurred in 1989 that later enabled most users to understand conversational speech with their restored hearing alone. Subsequent developments included stimulation in addition to that provided with a unilateral CI, either with electrical stimulation on both sides or with acoustic stimulation in combination with a unilateral CI, the latter for persons with residual hearing at low frequencies in either or both ears. Both types of adjunctive stimulation produced further improvements in performance for substantial fractions of patients. Today, the CI and related hearing prostheses are the standard of care for profoundly deaf persons and ever-increasing indications are now allowing persons with less severe losses to benefit from these marvelous technologies. The steps in achieving the present levels of performance are traced, and some possibilities for further improvements are mentioned. Copyright © 2014. Published by Elsevier B.V.
    Hearing Research 12/2014; 322. DOI:10.1016/j.heares.2014.11.009 · 2.97 Impact Factor
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    • "at the back of the head (MP2), or both (MP1 + 2) [3], [4]. However , the specific in vivo current pathways have not been studied to date. "
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    ABSTRACT: The current conduction pathways resulting from monopolar stimulation of the cochlear implant were studied by developing a Human Electro-Anatomical Total HEad Reconstruction (HEATHER). HEATHER was created from serially sectioned images of the female Visible Human Project dataset to encompass a total of 12 different tissues, and included computer aided design geometries of the cochlear implant. Since existing methods were unable to generate the required complexity for HEATHER, a new modeling workflow was proposed. The results of the finite element analysis agree with the literature, showing that the injected current exits the cochlea via the modiolus (14%), the basal end of the cochlea (22%), and through the cochlear walls (64%). It was also found that, once leaving the cochlea, the current travels to the implant body via the cranial cavity or scalp. The modeling workflow proved to be robust and flexible, allowing for meshes to be generated with substantial user control. Furthermore, the workflow could easily be employed to create realistic anatomical models of the human head for different bioelectric applications, such as deep brain stimulation, electroencephalography, and other biophysical phenomena.
    IEEE Transactions on Biomedical Engineering 10/2014; 62(2):728-735. DOI:10.1109/TBME.2014.2364297 · 2.35 Impact Factor
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