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PubMed2004

Effect of magnetic resonance imaging on internal magnet strength in Med-El Combi 40+ cochlear implants.

OBJECTIVE: Magnetic resonance imaging (MRI) has been contraindicated when cochlear implants containing an internal magnet are in place because of concerns regarding torque, force, demagnetization, artifacts, induced voltages, and heating. The objective was to determine the magnetic field strength of Med-El Combi 40+ cochlear implant internal magnets after MRI studies. STUDY DESIGN/METHODS: Two fresh cadavers were used to study demagnetization using a repeated measures design and a magnetometer. Pre- and postMRI measurement of magnetic field strength was completed. Five sets of sagittal T1-weighted, axial T1-weighted, and axial T2-weighted sequences were performed on a cadaver at 0.2 Tesla in the device-up and device-down positions. In the other cadaver, 15 sets of sagittal T1-weighted, axial T1-weighted, and axial T2-weighted sequences were performed on a cadaver at 1.5 Tesla were conducted, 5 each with the head oriented at 80, 90, and 100 degrees rotated around the yaw plane (rotated around the z-axis). Subsequently, three cochlear implant patients completed 0.2 Tesla MRIs. For these patients, subjective and objective assessment of cochlear implant performance was performed. SETTING: Academic medical center. RESULTS: In the cadaver studies, analysis of variance showed no significant difference in the magnetic field strength after the 0.2 or 1.5 Tesla scans. There was no significant difference in the magnetic field strength for the three patients undergoing 0.2 Tesla MRIs and no adverse consequences, including no changes in telemetry, auditory sensations, nonauditory sensations, and sound quality. CONCLUSIONS: No significant demagnetization of the internal magnet occurred during repeated 1.5 Tesla MRI scans with the head orientations used in this study. In the cochlear implant patients, no significant demagnetization of the internal magnet occurred after a 0.2 Tesla MRI.

Artifacts↗

PubMed2003

Update on bilateral cochlear implantation.

PURPOSE OF REVIEW: Providing a unilateral cochlear implant in a patient with a profound bilateral hearing loss has now been a standard clinical practice for more than a decade. Although results are often very good, normal hearing has not been restored. One exciting opportunity to improve hearing in this population is to provide a second implant. However, it is not obvious that bilateral electrical stimulation can be integrated by the central nervous system. This article describes binaural hearing and reviews currently published articles on binaural cochlear implants. RECENT FINDINGS: Controlled laboratory trials have focused on distinguishing different categories of potential binaural advantages. A potential summation effect occurs when the same stimulus is available at two ears. Listening in noise with two ears should be better than listening with one ear when the additional ear is away from the noise. This head shadow benefit results from acoustic effects, not physiologic ones. When the second ear is added near the noise source, a binaural squelch benefit can occur, requiring neural integration from both sides. Finally, two ears may improve sound localization. Binaural implantees generally benefit from head shadow effects. Only some benefit from summation and squelch effects. Most, but not all, show improved horizontal plane localization. SUMMARY: It is now appropriate to begin experimental studies of binaural cochlear implants. Preliminary results show promise to improve head shadow, a physical advantage, and sound localization. Some benefits have been observed for improved summation and squelch. These findings have demonstrated that the brain can integrate electrical stimulation from the two ears. Future studies will be required to maximize this binaural hearing.

Cochlear Implantation↗

PubMed2004

Mandarin tone recognition in cochlear-implant subjects.

This study examined tone recognition in five cochlear-implant subjects who were native speakers of Mandarin and used a Nucleus-22 device. Psychophysical experiments were conduced to measure rate discrimination in individual electrodes from the most apical to the most basal electrodes. The rate range was from 100 to 200 Hz, which corresponded to the range of variation in fundamental frequency for the tonal tokens used in this study. Speech recognition experiments were also conducted to measure tone recognition as function of the number of electrodes from a 1-electrode map to a 20-electrode map. Large individual variability was observed for both rate discrimination and tone recognition result: Average rate discrimination ranged between 0.2 and 1.2 (Weber's fraction) whereas tone recognition ranged between 30% and 70% correct. A highly significant correlation was found between rate discrimination and tone recognition with the 20-electrode map, but a non-significant correlation was observed with the 1-electrode map due to a floor effect in tone recognition. The present result supports the hypothesis that both spectral and temporal cues contribute to tone recognition. In addition, the present result shows that current cochlear-implant subjects produced significantly lower performance than acoustic simulations in normal-hearing subjects, suggesting that neither temporal nor spectral cues have been adequately and appropriately extracted and encoded in current cochlear implants. New designs are discussed to improve tone recognition in cochlear implant subjects.

Adult↗

PubMed1995

Studies of currently used and experimental cochlear implants.

Since 1987 we have inserted multichannel cochlear implants in 60 patients with severe hearing impairment. The surgical procedures were not very difficult, and few postoperative complications were encountered. Postoperative speech recognition by every patients was satisfactory. Nevertheless, some patients complained about their hearing in a noisy environment, or while listening to either TV or music. Consequently, cochlear implants needs further improvement. To improve speech recognition ability, a newly developed experimental system was constructed. Judging from the electrode activation pattern, the new system extracted the features of consonants more successfully than the present system. However, when this new system was installed in cochlear implant patients, no significant improvement in consonant recognition was obtained.

Adult↗

PubMed2006

Adaptation to distorted frequency-to-place maps: implications of simulations in normal listeners for cochlear implants and electroacoustic stimulation.

The ideal cochlear implant electrode array positioning enables stimulation over a range of cochlear positions whose characteristic frequencies cover the frequency range of speech and match the speech processor filter frequencies. However, the electrode positions achieved in practice may not meet this specification. Users of conventional monaural cochlear implants seem able to perceptually adapt to a mismatch of speech processor filters to electrode positions. In electroacoustic stimulation, it is important to consider possible inconsistencies between acoustic and electrical frequency-to-place mapping. Two simulation studies are outlined that address normal listeners' ability to perceive speech presented through distorted frequency maps. The first presented a map that is spectrally warped around a 10-mm medial cochlear area. Listeners were able to adapt to this map after a few hours of training. The second study presented a binaural mapping in which one ear was subject to a 6-mm basalward shift. Here listeners were unable to learn to integrate speech information across the two mismatched ears, rather they seem to learn to ignore the shifted information. Frequency-to-place mapping is likely to be an important factor in the successful use of a combination of electrical and acoustic hearing.

Acoustic Stimulation↗

PubMed1998

Congenitally deaf children following cochlear implantation.

The aim of this study is to determine the auditory performance of congenitally deaf children following cochlear implantation. A prospective study is undertaken of 71 such children who have been implanted in a dedicated paediatric cochlear implant centre and who have been followed up to 3 years following implantation. All children are aged less than 8 years at the time of implantation and all receive a multichannel cochlear implant system. No child meeting these criteria has been excluded from the study. The average age at implantation is 56.5 months (range 27 to 93 months, standard deviation 15.9 months). Auditory performance is assessed by using the Categories of Auditory Perception (CAP) scale which is developed primarily as a clinical tool for evaluating profoundly deaf young children following cochlear implantation. The median score prior to implantation on this scale is Category 0 (no awareness of environmental sound), at the 1 year interval is Category 4 (discrimination some speech sounds without lip-reading), and at the 2 and 3 year interval, the median score on the CAP scale is Category 5 (understanding of common phrases without lip-reading). These results indicate the ability of cochlear implants to provide significant auditory receptive skills to young congenitally deaf children.

Child↗

PubMed1986

Safety and efficacy of the House/3M cochlear implant in profoundly deaf adults.

The House/3M cochlear implant system is no longer considered investigational. Many years of clinical experience led to development of a clinically feasible program for selecting patients, fitting the device, training patients in its use, and evaluating results. Both laboratory and clinical data support the conclusion that this device is safe and provides significant benefits for profoundly deaf adults. The House/3M cochlear implant has had a significant impact in the treatment of the profoundly deaf, even while in the investigational stage. First and foremost, patients who were previously turned away as "untreatable" were provided with a new option. Furthermore, the professionals--otologists and audiologists--had a new set of tools, including assessment and rehabilitation materials, to use in dealing with the profoundly deaf patient. These patients can now be provided more effective care whether they obtain an implant or a hearing aid. Finally, the introduction of this device stimulated the development of better devices, better assessment tools, and other alternatives. The future calls for device improvements, objective methods for selection of candidates, and expansion of the application of electrical stimulation of hearing to children, to patients with more residual hearing, and to those who require a central electroauditory prosthesis for stimulation in the brain stem. Cochlear implants are rapidly becoming a part of clinical otology and audiology. It is important that accurate information be disseminated among these professionals, that professional training programs teach their students about this area, and that other professionals, such as educators of the deaf, speech/language pathologists, and psychologists who deal with the hearing impaired, become knowledgeable in dealing effectively with the implanted child or adult.

Adult↗

PubMed1999

Cochlear implantation in Thailand.

This article evaluates and compares the benefits of a House/3M single channel cochlear implant or a Nucleus 22-channel cochlear implant on speech recognition in Thai-speaking patients. From 1986-1989, four profoundly deaf adults were implanted with the House/3M prosthesis. Since 1994, nine post-lingually deaf adults and three pre-lingually deaf children have been implanted with the Nucleus prosthesis. One case was implanted with the House/3M prosthesis and in the contralateral ear with the Nucleus prosthesis. The post-operative results were determined according to the ability to understand Thai monosyllabic, bisyllabic open-word sets and everyday sentence tests with, and without, lip reading. The scores were then compared in the House/3M users and the Nucleus users and compared between the House/3M cochlear implant and the Nucleus cochlear implant in the same user. The speech recognition scores on monosyllabic and bisyllabic open-word set demonstrated that the Nucleus users perform at a much higher level than the House/3M users. The results of four pre-lingually deaf children will be reported later after a period of auditory and speech rehabilitation.

Adolescent↗

PubMed1997

Performance in quiet and in noise with the Nucleus Spectra 22 and the Clarion CIS/CA cochlear implant devices.

The demographic characteristics and functional results from two cochlear implant adult patient groups are reported. The first group of subjects, implanted with the Nucleus Mini 22 Cochlear Implant System utilized the SPEAK coding strategy available in the SPECTRA 22 speech processor. The second group of subjects, implanted with the Clarion Cochlear Implant System used the CIS coding strategy with the exception of one patient utilizing the CA speech coding strategy. Data are available for 130 Nucleus subjects who were evaluated following 1 month of use of the SPEAK coding strategy. Data for the second group of subjects became available following administration of the Nucleus test battery to 38 Clarion subjects with varying implant experience. The test results presented include one common open set speech perception measure for all patients, the Freiburger monosyllabic word (FMW) tests. Additional subsequent test measures were taken from an adaptive test protocol assessing performance in quiet and quiet and two noise conditions. The results of this study conclude that both subject groups displayed similar distribution of performance scores on Freiburger Monosyllabic Words despite the large difference in group numbers. Both device groups also demonstrated a similar degree of deterioration in performance with increased background noise. This paper describes the results observed for each group.

Adolescent↗

PubMed1998

Stability of the cochlear implant array in children.

OBJECTIVE: To determine cochlear implant electrode stability in the young patient. Electrode migration due to future skull growth was a concern that led to prohibiting implantation in children less than 2 years of age. Recently, the high level of performance achieved by young implantees has led to a re-evaluation of this lower age limit, requiring an assessment of the effects of skull growth over time. STUDY DESIGN: Prospective radiographic analysis of electrode position of cochlear implants in young children. METHODS: Twenty-seven children implanted with the Nucleus (Cochlear Corp., Denver, CO) or Clarion (Advanced Bionics Inc., Sylmar, CA) multi-channel cochlear prostheses were subjects for this study. Follow-up radiographic studies were obtained for a period of 1 month to 5 years after implantation. The age at time of implantation ranged from 14 months to 5 years. An intraoperative modified Stenver's view plain radiograph was obtained as a baseline. After implantation, on a yearly basis transorbital Stenver's and base views were obtained for comparative purposes. Additional radiographs were obtained whenever a change in performance or electrode map caused suspicion for extrusion. Electrode position was determined using a computer graphics enhancement technique whereby image contrast filters enhanced the visibility of the electrode array and surrounding bony structures. RESULTS: An analysis of the data revealed no migration of the electrode array over time. CONCLUSIONS: The confirmation of the stability of the electrode array alleviates the concern of the effects of skull growth on cochlear implantation in young children.

Child, Preschool↗

PubMed1998

The additional hospital costs and outcome of the LAURA Cochlear Implant in the Department of Otorhinolaryngology, Head and Neck Surgery of the University Hospitals, Leuven.

The additional hospital costs and the effects of cochlear implantation are described. From the start in 1994 until 1996 ten patients, 8 adults and 2 children, received a cochlear implant after careful preoperative selection. Only the 8 deaf adults implanted with the LAURA cochlear implant in the department of Otorhinolaryngology, Head and Neck Surgery of the University Hospital Leuven will be included in this retrospective analysis. In this study, the additional hospital costs associated with cochlear implantations are estimated. In estimating the costs, a differentation is made between 'fixed' costs and 'variable' costs. In general the costs of cochlear implantation is high: an average cost of 1,186,741, -Bef per implanted adult and a direct fixed cost of 262,880, -Bef for the computer requisites. To evaluate the effect of cochlear implantation a standard test, the AN-test battery, is used. In general, the cochlear implant enhances the speech perception scores in the postlingually deafened as well as in the prelingually deafened adults. After intensive training, all implanted adults of the University hospital Leuven could recognize the segmental aspects of speech with scores above the level of significance. The cochlear implant has also a positive psychological and social impact.

Adult↗

PubMed2003

Cochlear implantation in a patient with neurofibromatosis type 1 and profound hearing loss: evidence to support a cochlear site of lesion.

OBJECTIVE: To determine the efficacy of cochlear implantation in an individual with neurofibromatosis type 1 and profound hearing loss and to determine, to the extent possible in a living subject, the site of lesion of the hearing loss in an individual with neurofibromatosis type 1. STUDY DESIGN: Postoperative assessment of an adult male with neurofibromatosis type 1. SETTING: The study was completed in the Departments of Otolaryngology and Audiology, University of Massachusetts Medical Center, Massachusetts. PATIENTS: One adult male with neurofibromatosis type 1 and bilateral, chiefly profound, sensorineural hearing loss. INTERVENTIONS: The subject underwent cochlear implantation as treatment of bilateral, chiefly profound sensorineural hearing loss. MAIN OUTCOME MEASURES: Outcome measures include results of electrical auditory brainstem response testing, electrical compound action potential measures, and speech recognition scores. RESULTS: Results of testing revealed expected latencies of waves II, III, and V of the electrical auditory brainstem response, measurable compound action potentials across virtually the entire length of the electrode array, and high levels of open-set, auditory-only speech understanding. CONCLUSIONS: This is the first case report describing the outcome of cochlear implantation in a patient with neurofibromatosis type 1. Composite test results support the absence of VIIIth nerve degeneration or other anomalies, indicating a cochlear site of lesion for the hearing loss in this patient. Based on the results of this investigation, standard cochlear implantation should be considered a viable option and the first line of therapy for the treatment of bilateral, severe to profound sensorineural hearing loss in patients with neurofibromatosis type 1 and normal, VIIIth nerve radiographic findings.

Adult↗

PubMed2002

Temporal processing and speech recognition in cochlear implant users.

Although the speech recognition performance of cochlear implant patients has steadily improved in recent years, considerable variability remains in implant patient outcomes. Here, we report on a correlation between cochlear implant patients' auditory temporal processing and speech recognition abilities. Modulation detection thresholds were measured as a function of stimulation level; phoneme recognition was also assessed. Results showed marked individual differences in the shape and absolute sensitivity of subjects' modulation threshold functions. Statistical analysis revealed a strong correlation between phoneme recognition scores and subjects' mean modulation thresholds, demonstrating the contribution of temporal processing to implant speech perception. In correlating a basic psychophysical measure to speech performance, these results should contribute toward improved speech processor design and rehabilitation tools for cochlear implant patients.

Acoustic Stimulation↗

PubMed1995

First field trials with a portable CIS processor for the Ineraid multichannel cochlear implant.

The continuous interleaved sampling (CIS) strategy is a promising sound processing strategy for multichannel cochlear implants which provides immediate improvements in speech recognition when tested on Ineraid users: patients with only a few hours of experience (in laboratory testing) with the CIS strategy score better than with the Ineraid prosthesis they used since they, were implanted. The goal of this study was to evaluate the benefits that can be gained by the use of the new strategy in every day life. Two patients, implanted with the Ineraid multichannel cochlear implant, were equipped with a portable numerical processor programmed to implement a high rate CIS strategy. Their speech recognition was evaluated periodically with consonant and vowel identification tests for more than 6 months of use. Tests were also made with the Ineraid processor during the same experimental sessions and patients were regularly interviewed about their experience. Performance with the portable CIS processor was superior or equal to that obtained previously in the laboratory with the same strategy. Both patients achieved the best scores in 6 years of cochlear implant use. Qualitative reports from the patients suggest that the CIS strategy can improve "hearing" performance of cochlear implant users in many important situations of every day life. Altogether, these results hold great promises for all users of the Ineraid multichannel cochlear implant.

Adult↗

PubMed2004

Benefits of cochlear implantation in early-deafened adults: the Toronto experience.

OBJECTIVE: To present the results of a survey administered to a group of early-deafened cochlear implants adults and to report the level of perceived benefit. DESIGN: Prospective. SETTING: Large tertiary referral centre. METHOD: A 47-item questionnaire designed to evaluate cochlear implant use and benefit was sent to 42 early-deafened adult cochlear implant users. The questionnaire can be divided into seven subcategories: time of use, associated symptoms, communication, employment status and function, socialization, perceived benefit, and the impact on quality of life. Responses from 30 patients were received. RESULTS: The majority of our patients use their cochlear implant all of their waking hours. The majority of patients continue to depend on lip-reading and hearing as their main mode of communication, although they reported improved lip-reading skills with their cochlear implant. Twenty-three patients (76.7%) were employed. Eleven patients had a change in employment subsequent to cochlear implantation, nine (81.8%) of whom attributed this to their cochlear implant. Our patients als reported greater independence, a greater sense of safety in their environment, and an improved social life. Twenty-nine patients (96.7%) said that they were satisfied with their implant, 28 (93.3%) said that they would go through the same process again, and 27 (90%) said that they would recommend it to a friend in a similar situation. Twenty-nine patients (96.7%) stated that the cochlear implant has had a positive effect on their quality of life. Family and peer support, prior auditory-verbal therapy, and a positive attitude were the most commonly cited factors in successful cochlear implant use. CONCLUSIONS: Early-deafened adult cochlear implant users perceive significant benefit from cochlear implantation. Importantly, family and peer support, prior auditory-verbal therapy, and a positive attitude are considered important factors in maximizing this benefit.

Adult↗

PubMed2006

Educational performance of pediatric cochlear implant recipients in mainstream classes.

OBJECTIVES: The present study documents the school performance of 20 pediatric cochlear implant recipients who attended mainstream classes and compares their educational performance with their normally hearing peers. METHODOLOGY: All 20 school-aged children who underwent cochlear implantation at the Universiti Kebangsaan Malaysia cochlear implant programme participated in this study. Three measures were employed to assess the school performance. First, using the SIFTER teacher-rating scale, the second measure was the child's examination results, and the third was the child's standing compared to his/her peers in language subject, mathematics, and the overall academic performance during the end of semester examinations. RESULTS: The SIFTER rating scale indicated that only 11.8% of the children were identified as not educationally at risk, 17.6% passed four of the SIFTER subtests, whereas the other 71.6% failed in at least two of the subtests on SIFTER. The highest pass rate was obtained in behavior subtest (76.5%), followed by classroom participation (70.6%), attention (58.8%), academic (47.1%), and communication (11.8%). On the educational performance, the cochlear implant recipients performed significantly better in mathematics (mean scores 62.67%; S.D. 22.24) than in language (mean scores 49.96%, S.D. 25.88) (p<0.01). In the overall examination performance, 25.00% had above average performance (>75th percentile), 18.75% had average performance (25-75th percentile), and another 56.25% performed at below average (<25th percentile). CONCLUSION: Children with cochlear implant were rated poorly in the SIFTER communication subtest. It is possible that language deficit presents an educational challenge in these children. The educational performance of children with cochlear implants in mainstream classes varies. Although 43.75% of them thrive well in a full-time mainstream setting, a significant percentage of them (56.25%) performed at below the average level. These findings reemphasize that although a cochlear implant has successfully provided deaf children with a good hearing potential, the majority of its recipients still require additional educational supports in order to function well in the mainstream educational setting.

Child↗

PubMed1986

Cochlear implants. Present and future.

The perfect cochlear implant has eluded the many research teams around the world that are studying it. In the hope that someone may develop one system that is clearly better than the others, I believe that each team should pursue its own ideas and methods. We have at least another 20 years of step-by-small step development if we are to continue to improve the cochlear implant.

Cochlear Implants↗

PubMed2003

Cochlear implants: growing pains.

OBJECTIVES/HYPOTHESIS: The objective was to make familiar the problems faced in the application of cochlear implants to the half-million to a million severe to profoundly deaf individuals who are potential beneficiaries of this technology. STUDY DESIGN: Observations accumulated during 23 years as Medical Director of the Manhattan Eye Ear Throat Hospital Cochlear Implant Center. METHODS: The author reviewed insights gained while directing the Cochlear Implant Center since the early 1980s at Manhattan Eye, Ear and Throat Hospital (New York, NY). RESULTS: The rapid application of cochlear implant technology for patients with severe to profound hearing losses is creating critical problems. It is being hampered by inadequate reimbursement. There is a critical shortage of cochlear implant-trained audiologists, who are an essential keystone in the application of this technology. These audiologists are required to provide lifelong audiological services to patients who have received cochlear implants. At the same time, they must evaluate the exponentially growing number of new candidates. CONCLUSION: The restoration of hearing with cochlear implants provides an enormous educational and societal benefit. However, the existing health care delivery system limits the application of cochlear implant technology. University audiological training programs must expand their curricula to include cochlear implant-related courses. The existing rehabilitation audiologist delivery system could be applied to provide long-term, community-based cochlear implant services.

Audiology↗