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At least 19 recordsLinked to original sources

PubMed1991

[General principles of conception of cochlear implants].

Cochlear implants have greatly been developed on last ten years. Their diversity makes their use and choice more complex. The authors expose simply the physiopathology of the implanted auditory system and basic principles of cochlear implants. Cochlear implants are caracterised by the number of channels and electrodes (monochannel, multichannel), the strategy of encoding (analogiq, digital), the transmission of signal (per-cutaneous, electro-magnetic induction), the site of stimulation (extra or intra-cochlear), the signal wave (sinusoid, pulse), the diffusion of current (monopolar, bipolar).

Cochlear Implants↗

PubMed1990

Computed tomography: how accurate a predictor for cochlear implantation?

Cochlear implantation is an accepted medical treatment for profound bilateral postlinguistically acquired hearing loss. Because cochlear implants are still in the process of development, a detailed evaluation of the results of implantation is essential. However, the capability of predetermining the auditory benefit of a cochlear implant is limited and depends upon a number of factors. This report focuses upon the ability of computed tomography (CT) to predict surgical success and audiological results of multichannel cochlear implantation. It also addresses how the disease state might affect the functional benefit of the implant. After undergoing routine clinical and audiological evaluations, 28 cochlear implant candidates underwent CT scans in order to evaluate cochlear patency prior to surgery. Subsequently, 24 patients were implanted with either a single-or 22-channel device. Surgical findings were noted and postoperative audiological assessments of sound detection and speech discrimination were made. The CT risk factors that diminish the likelihood of a successful cochlear implant result are discussed based upon a retrospective comparison of preoperative CT results, surgical findings, and postsurgical audiological evaluations of the 14 patients who received a 22-channel implant. Analysis of the predictive capability of CT will allow clinicians to use that procedure more effectively in the presurgical assessment of cochlear implant candidates.

Adult↗

PubMed1988

Treatment of sensorineural hearing loss by cochlear implantation.

Cochlear implantation, a form of neural prosthesis, is now being employed for some profoundly deaf individuals. The pathophysiology of profound deafness, the strategies inherent in cochlear implantation, the differences between various cochlear implant strategies and designs, medical and otologic evaluation of implant candidates, and the surgical procedure are each discussed. The results in speech recognition and speech reading that have been obtained with four commonly used cochlear implant systems are also presented.

Cochlear Implants↗

PubMed1992

[3D imaging of the labyrinth: application to candidates for cochlear implant].

Cochlear implantation is a treatment for profound bilateral cochlear hearing loss. Two broad varieties of cochlear implants are used: single or multichannel device (22- channel) inserted either into the cochlea (tympanic ramp) or on the promontory on round window Imaging modalities have to predict cochlear patency prior surgery, an essential factor for choosing between intra or extra cochlear implant. Since March 1991, we have investigated 23 implant candidates to evaluate cochlear patency prior surgery, 6 patients underwent surgery: 4 had a multichannel and 2 had a monochannel electrode. Both CT and MRI play a role in pre operative study. CT easily predicts cochlear ossification and labyrinthine malformations MRI (3 D applications) with T 2 Weighted images, one millimeter thick, more clearly depicts labyrinthine liquid and can predict cochlear fibrosis before ossification.

Cochlear Implants↗

PubMed1991

What can we learn about hearing aids from cochlear implants?

Cochlear implants have changed the rehabilitation of profoundly hearing-impaired patients. A wide range of performance is reported for postlingually deaf adult patients using multichannel (Nucleus and Inerad) cochlear implants. For the 63 patients described here, performance ranges from 0 to 62% correct word recognition, from 0 to 98% lipreading enhancement measured as a percentage of the possible enhancement, and from 0 to 98% on understanding words in sentences. Prelingually deaf children also show benefit from their cochlear implants, but they require more time to obtain benefit than postlingually deaf children and adults. Experience with cochlear implants has suggested a few observations that could be useful to hearing aid development, including: (1) field trials are essential; (2) signal processing should preserve and enhance frequency resolution; (3) the fitting process for a sophisticated hearing aid may require several days to adjust properly; (4) fitting algorithms should focus on individuals rather than averages; (5) patients will wear a larger device if their handicap is great enough and if the improvement is sufficient; and (6) patients should and will accept expensive hearing aids.

Adult↗

PubMed1991

Cochlear implant.

Cochlear implantation to restore some of the hearing in the profound or totally cochlear deaf patient has been briefly presented. An approximate two year follow up has not shown any complications. The Nucleus 22 channel cochlear implant, as presently manufactured, is a very useful device to rehabilitate profoundly or totally cochlear deaf patients.

Cochlear Implants↗

PubMed1986

Contraindications to cochlear implantation.

Cochlear implantation is still a controversial surgical procedure because its results in providing hearing for the deaf patient are far from ideal. The possible benefits of implantation should be carefully weighed against the complications that might arise. Many individuals with profound deafness are candidates for this procedure; however, there are some patients who are not. Contraindications to cochlear implantation, absolute and relative, systemic and local, are discussed. The surgeon's decision to withhold surgery is based on these contraindications.

Age Factors↗

PubMedDate not supplied

Observations on an experimental expansile electrode for use in cochlear implantation.

Cochlear implants in children must be designed to allow for a child's growth and maturation. An experimental animal study was performed to document the influence of head growth on a prototype expansile electrode system. Seven kittens were implanted with a stimulated electrode which had been coiled to allow for a two-to-one expansion in length. Head growth was monitored both by direct skull measurements and by serial radiography. The animals were sacrificed when they had reached maturity and the implanted devices were studied. When implanted in subcutaneous tissue, the coils became encased in fibrous tissue, while within air-containing spaces, such as the bulla, they distended freely. This suggested that a route which maximized the amount of air-containing space traversed by an electrode should be the preferred route for a cochlear implant in children.

Animals↗

PubMed1992

Paediatric cochlear implantation.

Cochlear implantation may now be considered as a method of managing children with profound sensory hearing loss who do not benefit from conventional amplification. It involves a team approach with integration of many skilled individuals, as well as the child and his or her parents and family. As William House has said, in 1991, 'The future is not in the adult programme, but in the continued expansion of the children's programme'.

Child↗

PubMed1985

Iowa cochlear implant clinical project: results with two single-channel cochlear implants and one multi-channel cochlear implant.

Cochlear implants have become a realistic alternative for the management of profoundly deaf patients. A variety of implants with differing electrode designs and coding strategies have been developed by nine major implant centers around the world. Each center has their "star" patient, but objective comparisons between these different implant designs are unavailable. In order to determine the performance characteristics of the present generation of cochlear implants, comparison data are vital. We have developed an independent center where uniform objective comparisons of different cochlear implants can be performed longitudinally. This report will present results of nine patients implanted with three different cochlear implant prostheses. Four patients have been implanted with the Los Angeles (House) single-channel implant, three patients have received the Vienna (Hochmair) single-channel intracochlear device, and two patients have been implanted with the Melbourne (Clark) 21-channel unit. All patients have had 11 months or more of experience with their cochlear prostheses. The results of a comprehensive audiologic battery which includes audiovisual and environmental tasks are presented. All implants provide significant improvement in speechreading and sound awareness. The findings to date suggest that there is strong correlation between top-down cognitive processing (as reflected by lip reading skills) and performance with cochlear implants.

Adult↗

PubMed1991

Facial nerve stimulation with cochlear implantation. VA Cooperative Study Group on Cochlear Implantation.

The course of the facial nerve may place it within the current field generated by an activated cochlear implant to produce incidental facial movement. We investigated the presence of facial nerve stimulation associated with cochlear implants in the VA Cooperative Study of Advanced Cochlear implants. Twelve of 82 patients enrolled in this study demonstrated facial nerve stimulation within 2 years of implant activation. Facial nerve stimulation in six patients with multiple channel implants (Nucleus or ineraid devices) either resolved spontaneously (n = 2), or was eliminated by deactivating basal (n = 2) or apical (n = 2) electrodes. Two of six patients with single-channel electrodes (3-M/Vienna devices) demonstrated facial nerve stimulation that resolved spontaneously (n = 2), resolved with lowering current output (n = 2), or was refractory to processor adjustment (n = 2). Intraoperative assessment in one of the refractory cases indicated that facial nerve stimulation resulted from current spread through the modiolus to activate the facial nerve. A variety of factors, including implant design, stimulus parameters, and local tissue impedances, may interact to produce incidental facial stimulation. Low-impedance pathways between the scala tympani and the modiolus may deserve increased recognition as an interactive factor in cochlear implant performance.

Adult↗

PubMed1989

Effects of stimulation by cochlear implant on the cochlear nerve.

Degeneration of the cochlear nerve before and after placement of the cochlear implant might influence the efficacy of the device. We examined histological characteristics, including the caliber of the cochlear nerve fibers of the central segment proximal to the porus acusticus, in three profoundly deaf patients. Two of them used a cochlear implant for many years longer in one ear than in the other, and one used an implant in one ear only. No qualitative or quantitative differences between the two sides were found. However, in all three cases we found that the cochlear nerves on both sides were substantially degenerated. These results indicated no noticeable effects of stimulation by the cochlear implant on the central portion of the cochlear nerve.

Adult↗

PubMed1987

Electrically evoked brainstem responses in cochlear implant recipients.

Electrical stimulation of the auditory nerve in the profoundly deaf population through implanted cochlear prostheses has increased the need for reliable electrophysiologic assessment tools. We have recorded electrically evoked brainstem responses (EABRs) in 21 subjects who have received a 3M/House cochlear implant. Recordings have been made, both intraoperatively and postoperatively, in the laboratory setting. The recording technique, methods of stimulus artifact suppression, and results of our measurements are described. Clinical applications of this technology are suggested.

Adolescent↗

PubMed1989

Place-pitch and vowel-pitch comparisons in cochlear implant patients using the Melbourne-Nucleus cochlear implant.

Results of place-pitch and vowel-pitch comparisons are presented in 21 cochlear implant patients using the Melbourne-Nucleus cochlear implant. Vowel-pitch comparisons were also carried out in 10 normal hearing subjects. A technique for the place-pitch ranking test has been developed. A graphic representation of the results shows the well-ranked electrodes in sequential pitch-order, and reveals any indication of abnormal place-pitch perception. It aids the selection of correctly place-pitch ranked electrodes. The vowel-pitch comparisons showed that both normal hearing subjects and cochlear implant patients are able to rank vowels according to 'vowel-pitch'. In normal hearing subjects, three main types of vowel-pitch processing have been found. Results indicate that an information selection and reduction process occurs at higher levels along the auditory pathway. Cochlear implant patients test results showed the limited contribution of the first and the virtual lack of the second formant's contribution to pitch-ranking the voiced vowels. These results indicate that fundamental frequency converted to pulse rate may not be adequate at certain segments along the cochlear partition. Vowels are not perceived by cochlear implant patients according to their first or second formant frequency converted to place-pitch. There would seem to be a need for alternative speech processing strategies in the Melbourne-Nucleus implant.

Adult↗

PubMed1991

Status of cochlear implantation in children. American Academy of Otolaryngology-Head and Neck Surgery Subcommittee on Cochlear implants.

The cochlear implant is a medical device, part of which is placed surgically, that uses electrical stimulation to provide hearing. For almost a decade, investigational studies have been ongoing to define its safety and efficacy in profoundly deaf children. During this period, more than 500 children aged 2 through 17 years have been implanted with either a single-electrode or multielectrode device. Extensive auditory, speech, educational, and psychologic testing has been performed before and after implantation. Results show that the cochlear implant provides auditory detection over much of the speech signal. Compared with the preimplant period, there is significant improvement in auditory discrimination and speech production skills. Limited open-set word and sentence recognition is possible for at least some children. Complications with the device have been minimal. The cochlear implant can provide sound to deaf children unable to benefit from hearing aids. The complex assessment, rehabilitation, and parent counseling should be performed by centers with the multidisciplinary staffs necessary to provide effective care for patients with this specialized auditory prosthesis.

Adolescent↗

PubMed1989

Loss of residual hearing after cochlear implantation.

Many cochlear implant recipients have some measurable hearing prior to implantation. Animal studies have demonstrated some loss of viable neural elements resulting from both mechanical insertion trauma and long-term electrical stimulation. The effect of implantation of a long intracochlear multichannel electrode array and subsequent electrical stimulation on residual hearing was evaluated. Forty consecutive cochlear implant recipients were assessed by audiometry at the Colorado Ear Clinic between July 1985 and June 1988. Twelve of these patients (30%) had some measurable residual hearing before implantation, although all had profound hearing loss, with no understanding of speech. All patients received a multichannel cochlear implant with all 22 electrodes inserted in each patient by an experienced cochlear implant surgeon. Audiometric testing was repeated between 2 and 24 months after implantation. Pure-tone threshold responses in the implanted ear were significantly reduced postimplant, while pure-tone threshold responses in the nonimplanted ear were stable.

Adult↗

PubMed1991

The Nucleus 22-channel cochlear implant system.

Cochlear implants have become the treatment of choice for profoundly deaf adults and children who obtain little or no benefit from conventional amplification. Sounds are translated into small electric currents that stimulate the auditory nerves in the cochlea and generate hearing sensations. The Nucleus cochlear implant is the result of more than 20 yr of research and development, first at the University of Melbourne, Australia and later by Cochlear Proprietary Limited (Sydney, Australia) in collaboration with the University of Melbourne. Today, the cochlear Mini-22 implant system is approved by the United States Food and Drug Administration (FDA) for use in adults and children, and has been implanted in more than 3000 patients worldwide. Although this chapter describes the cochlear implant system and clinical issues related to its use in children, much of the material has been derived from experience with adults. Furthermore, the Nucleus system is not static. It is being continually improved both in performance and ease of use. The purpose of this chapter is to describe developments leading up to and including the present Nucleus cochlear implant system. Other chapters in this issue present results and procedures relating to pediatric applications of the device.

Adult↗

PubMed1987

Technical development of an implantable cochlear prosthesis in Canada.

A new cochlear implant device is currently being developed by a group of research teams in Canada. This is an update on the progress of this development, including a brief description of the cochlear electrode array, the implantable stimulator, and the software development for the speech processor.

Cochlear Implants↗