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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↗
PubMedDate not supplied

Initial experience with the cochlear implant in children.

The decision to implant cochlear prostheses in children came after positive findings with deaf adults and the belief that the benefits of receiving sound far outweigh the potential risks involved. As of December 1981, 12 profoundly deaf children have received the single-electrode cochlear implant. Their ages range from 3.5 to 17 years. Test results are consistent with those of adults. Mean thresholds across the frequency range fall between 59-64 dB SPL. With the implant, these children can perform specific timing and intensity differentiations which could not be done with hearing aids. Their voices are quieter and more modulated, and the children are not quite as noisy with objects in the environment (eg, do not slam doors any more). This preliminary data demonstrates that implanting subjects under the age of 18 years is feasible.

Acoustic Stimulation↗
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↗
PubMed1995

[Cochlear implants and total cochlear obstruction].

Total cochlea obstruction is not a contraindication for cochlear implant. We report our experience owing to the single channel cochlear implant Monosonic (9 cases), partial insertion of the electrodes-array (3 cases: 1 Digisonic and 2 minisystem) and, more recently the separate electrodes version of the Digisonic (6 cases). This new device is encouraging because it supplies 2/5 patients with telephone use.

Adolescent↗
PubMed1995

Pediatric cochlear implants. Surgical aspects: the Nottingham pediatric cochlear implant programme.

The implantation of young children is widely accepted as a means of rehabilitating profoundly/totally deaf children. This paper will review the surgical aspects of implanting young children based on the first 50 children implanted in the Nottingham paediatric cochlear implant programme. Having thoroughly counselled the children's parents, the child is operated on under prophylactic antibiotic cover. The incision (extended endaural) is made directly down to bone and a full-thickness flap is elevated. Meticulous attention is paid to haemostasis. The steps involved in posterior tympanotomy, cochleostomy and implant insertion, often in the presence of osteogenesis, will be described. Electrophysiological testing is done systematically peroperatively. Surgical complications were few. There was no cases of facial weakness, haematoma, implant extrusion or infection. One patient, whose implant was laid in an extracochlear gutter, developed pain on electrical stimulation and was explanted. Another patient developed a retraction pocket cholesteatoma. These few complications are far outweighed by the overwhelming benefits accrued from implantation.

Child↗
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↗
PubMed1980

Neurophysiological requirements for implanted cochlear prostheses.

In a few introductory remarks the technological, neurophysiological and clinical assessments of new developments in modern, highly sophisticated hearing aids are reviewed. The necessity of preprocessing auditory information is discussed as well as the problems related to the choice of suitable electrodes, and, in particular, how much auditory information for speech communication, given by the product of number of just noticeable differences in intensity, number of just noticeable differences in frequency, number of channels for conveying neurophysiologically processable signals would be required as a minimum for cochlear implants to enable patients to communicate with one another. Finally, the fact that a number of different sensory modalities converge in to man's cortical association area might possibly be used for some special application of a multimodal input in a completely deaf patient with the aim of enabling him to understand human speech.

Animals↗
PubMed1993

[Auditory achievements of cochlear implantation].

The cochlear implant, which stimulates the auditory nerve electrically, is a rehabilitative solution for the severely deaf who cannot benefit from a hearing aid. The implant enables them to rejoin the world of sound from which they were disconnected. We present the process of auditory diagnosis which determines the patient's suitability for cochlear implantation, the implant's tuning program and the rehabilitation process it entails. Each of the 22 implanted electrodes is checked through a computer program, and the specifications of the electrical stimulation are established to provide the most comfortable hearing level for the implanted device. These stimulation specifications determine the number of active electrodes and the ideal stimulation model. During the 8-week hearing-training program which follows implantation, the patients acquaint themselves with the new world of sound through which they will communicate with their environment. Of the 16 implanted patients 7 heard only via the implant, without the aid of lipreading, a result which is considered excellent. These patients are able to talk on the telephone with the aid of the implant. 1 patient refused to use the implant, while the others have had good to moderate results. Noteworthy is the fact that even those with only moderate results greatly benefit from the implant, and are not willing to function without it for even a single day.

Adolescent↗
PubMed1981

The use of rare-earth magnet couplers in cochlear implants.

The cochlear implant is an electronic auditory prosthesis gaining widespread acceptance as a means of restoring partial hearing to the totally deaf. A number of engineering and biological hurdles remain toward the improvement of existing implantable systems and development of multichannel systems. One hurdle concerns reliable transcutaneous coupling of the external electric signal to the implanted device. To date this has been accomplished by inductive means through coils which were mechanically held in place. The incorporation of small, permanent, rare-earth (SmCo5) magnets with the coil assemblies has eliminated the unreliable mechanical supporting devices. Magnetic attachment was simulated in dogs to examine for biological compatibility. Electron micrographs indicated normal subcellular structures in tissue exposed for 10 weeks. Five patients were implanted with magnet-modified coil assemblies and tested for the proper alignment and support of the external coil assembly, as well as efficiency of inductive coupling. Electromagnetic coupling was not interfered with and mechanical support was adequate. We conclude that rare-earth magnets provide an effective means for supporting and positioning in place medical devices, such as the cochlear implant.

Animals↗
PubMed1993

Effects of noise and noise reduction processing on the operation of the Nucleus-22 cochlear implant processor.

Cochlear implants, like other types of auditory sensory aids, become increasingly ineffective with increasing ambient noise levels. One method of signal processing to reduce additive random wideband noise, the INTEL method, has been used to good effect as an input preprocessor for the Nucleus-22 cochlear implant. The implant's own signal processor estimates and encodes pitch frequency and the frequencies of Formants 1 and 2. The study reported here shows that additive noise results in substantial deviations in formant frequency estimates from those that would be observed in the absence of noise. When noisy speech is preprocessed by the INTEL method to reduce noise intensity, the deviations in the frequency estimates for Formant 2 are substantially reduced.

Acoustic Stimulation↗
PubMed1996

Accuracy of high-resolution computed tomography in cochlear implantation.

Multichannel cochlear implants are a proven method for the auditory rehabilitation of individuals who have severe-to-profound sensorineural hearing loss. These devices typically require insertion into the scala tympani of the cochlea to provide auditory stimulations. A patent scala provides the best chance for an adequate insertion of the electrode array. Preoperative high-resolution computed tomography imaging has traditionally been used to determine the patency of the scala tympani. Its ability to accurately predict the patency of the cochlea has been questioned in several retrospective studies. A prospective study was undertaken in 28 consecutive individuals undergoing cochlear implant surgery to compare the findings on high-resolution computed tomography with the surgical findings in an attempt to determine high-resolution computed tomography's accuracy. Cochlear obstruction caused by ossification was accurately predicted in six of six individuals but overestimated in the round window region in three individuals. High-resolution computed tomography accurately predicted patent cochleas in 19 individuals. No false-negative results were encountered. In this study sensitivity of high-resolution computed tomography was 100%, and specificity was 86%. High-resolution computed tomography appears to be more helpful than previously reported for determining cochlear patency.

Acoustic Stimulation↗
PubMed1982

The cochlear implant.

The cochlear implant offers an alternative to selected profoundly deaf patients in whom conventional treatments or prostheses have been unsuccessful. Substantial benefits have been obtained by patients, with apparently minimal risk. There have been no serious surgical complications and only a few postoperative problems, which were remedied satisfactorily. The device has continued to function in patients over a period of years, and in cases of internal coil failure it has been removed and replaced. Replacement devices seem to function as well as the patient's first device. There has been no evidence of any decrement in performance after years of electrical stimulation or any measurable adverse effects. The cochlear implant is now widely available and should be considered an option to be offered to appropriate patients.

Adolescent↗