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Cochlear implants in children: benefits and concerns.

Cochlear implants have been used in investigational studies with profoundly deaf children aged 2 to 18 years. Results with the 3M/House implant indicate that this device is safe and effective. The implant provides auditory detection of much of the acoustic speech signal, significant improvement in auditory discrimination compared with preimplant with hearing aids, and improved speech production skills. A longitudinal control-group study of auditory discrimination and a cross-sectional study of speech using age-matched controls support the interpretation that these improvements are due to the cochlear implant. In addition, 26 of 50 children (52%) tested for open-set word recognition and 17 of 41 (41.5%) tested for open-set sentence comprehension demonstrated such abilities using the cochlear implant. Adverse effects have been minimal. Early results from three children with the Nucleus multichannel cochlear implant clearly indicate the efficacy of that device.

Adolescent↗

Connexin-associated deafness and speech perception outcome of cochlear implantation.

OBJECTIVE: To compare performance after cochlear implantation in children with mutations in connexin (Cx) 26 (GJB2) or Cx30 (GJB6) and children with deafness of unknown etiology. DESIGN: Genetic analysis and speech perception evaluation was performed in the children with and without Cx mutations who had undergone cochlear implantation. Speech perception performance was retrospectively analyzed 6, 12, 24, 36, and 48 months after implantation. Test material was selected according to the child's age and cognitive and language abilities. SETTING: The study took place at speech and hearing and genetic centers of a hospital in the central part of Israel and the genetics departments of 3 additional centrally located hospitals. PATIENTS: A total of 30 children who had undergone cochlear implantation were selected for the study, with control patients matched according to age at implantation, duration of implant use, and mode of communication. There was no evidence for additional disabilities or handicaps in either group. MAIN OUTCOME MEASURES: Speech perception measurements included a questionnaire, as well as closed and open-set tests. RESULTS: Overall, the 2 groups showed significant improvement in speech perception results after implantation. Four years after implantation, both groups achieved mean open-set speech perception scores of approximately 60%, 75%, and 90% for monosyllabic, 2 syllables, and words in sentences tests, respectively. CONCLUSIONS: There were no apparent differences in speech perception performance after implantation between the children with Cx mutations and children with deafness of unknown etiology. These data have important implications as a prognostic indicator when counseling candidates for cochlear implantation.

Child↗

Music perception with cochlear implants: a review.

The acceptance of cochlear implantation as an effective and safe treatment for deafness has increased steadily over the past quarter century. The earliest devices were the first implanted prostheses found to be successful in compensating partially for lost sensory function by direct electrical stimulation of nerves. Initially, the main intention was to provide limited auditory sensations to people with profound or total sensorineural hearing impairment in both ears. Although the first cochlear implants aimed to provide patients with little more than awareness of environmental sounds and some cues to assist visual speech-reading, the technology has advanced rapidly. Currently, most people with modern cochlear implant systems can understand speech using the device alone, at least in favorable listening conditions. In recent years, an increasing research effort has been directed towards implant users' perception of nonspeech sounds, especially music. This paper reviews that research, discusses the published experimental results in terms of both psychophysical observations and device function, and concludes with some practical suggestions about how perception of music might be enhanced for implant recipients in the future. The most significant findings of past research are: (1) On average, implant users perceive rhythm about as well as listeners with normal hearing; (2) Even with technically sophisticated multiple-channel sound processors, recognition of melodies, especially without rhythmic or verbal cues, is poor, with performance at little better than chance levels for many implant users; (3) Perception of timbre, which is usually evaluated by experimental procedures that require subjects to identify musical instrument sounds, is generally unsatisfactory; (4) Implant users tend to rate the quality of musical sounds as less pleasant than listeners with normal hearing; (5) Auditory training programs that have been devised specifically to provide implant users with structured musical listening experience may improve the subjective acceptability of music that is heard through a prosthesis; (6) Pitch perception might be improved by designing innovative sound processors that use both temporal and spatial patterns of electric stimulation more effectively and precisely to overcome the inherent limitations of signal coding in existing implant systems; (7) For the growing population of implant recipients who have usable acoustic hearing, at least for low-frequency sounds, perception of music is likely to be much better with combined acoustic and electric stimulation than is typical for deaf people who rely solely on the hearing provided by their prostheses.

Audiometry↗

Cochlear implant candidacy and surgical considerations.

Numerous changes continue to occur in regard to cochlear implant candidacy. In general, these have been accompanied by concomitant and satisfactory changes in surgical techniques. Together, this has advanced the utility and safety of cochlear implantation. Most devices are now approved for use in patients with severe to profound rather the prior requirement of a bilateral profound loss. In addition, studies have begun utilizing short electrode arrays for shallow insertion in patients with considerable low frequency residual hearing. This technique will allow the recipient to continue to use acoustically amplified hearing for the low frequencies simultaneously with a cochlear implant for the high frequencies. New hardware, such as the behind-the-ear speech processors, require modification of existing implant surgery. Similarly, the new perimodiolar electrodes require special insertion techniques. Bilateral implantation clearly requires modification of the surgical techniques used for unilateral implantation. The surgery remains mostly the same, but takes almost twice as long, and requires some modification since at a certain point, when the first device is in contact with the body, the monopolar cautery may no longer be used. Research has already begun on the development of the totally implantable cochlear implant (TICI). This will clearly require a modification of the surgical technique currently used for the present semi-implantable devices. In addition to surgically burying the components of the present cochlear implant, we will also have to develop techniques for implanting a rechargeable power supply and a microphone for the TICI. The latter will be a challenge, since it must be placed where it is capable of great sensitivity, yet not exposed to interference or the risk of extrusion. The advances in design of, and indications for, cochlear implants have been matched by improvements in surgical techniques and decrease in complications. The resulting improvements in safety and efficacy have further encouraged the use of these devices. We anticipate further changes in the foreseeable future, for which there will likely be surgical problems to solve.

Age Factors↗

Acoustic characteristics of the speech of young cochlear implant users: a comparison with normal-hearing age-mates.

OBJECTIVE: The primary objective of this study was to compare select acoustic characteristics of the speech of deaf children who use cochlear implants (young cochlear implant users) with those of children with normal hearing. A secondary objective of this study was to examine the effect, if any, of the deaf child's education (oral versus total communication) on the similarity of these acoustic characteristics to those of normal-hearing age-mates. DESIGN: Speech was recorded from 181 young cochlear implant users and from 24 children with normal hearing. All speech was produced by imitation, and consisted of complete sentences. Acoustic measures included voice onset time (/t/, /d/), second formant frequency (/i/, /[U0254]/), spectral moments (mean, skew and kurtosis of /s/ and /[U0283]/), a nasal manner metric, and durations (of vowels, words, and sentences). RESULTS AND DISCUSSION: A large percentage (46 to 97%) of the young cochlear implant users produced acoustic characteristics with values within the range found for children with normal hearing. Exceptions were sentence duration and vowel duration in sentence-initial words, for which only 23 and 25%, respectively, of the COCHLEAR IMPLANT users had values within the normal range. Additionally, for most of the acoustic measures, significantly more COCHLEAR IMPLANT users from oral than from total communication settings had values within the normal range. CONCLUSIONS: Compared with deaf children with hearing aids (from previous studies by others), deaf children who use cochlear implants have improved speech production skills, as reflected in the acoustic measures of this study. Placement in an oral communication educational setting is also associated with more speech production improvement than placement in a total communication setting.

Child↗

Surgical techniques for cochlear implantation in the very young child.

Early cochlear implantation to treat prelingually deafened children has been shown to improve speech perception and overall performance. The current age limit for implantation is 24 months in accordance with US Food and Drug Administration guidelines, but it is believed that earlier implantation is possible and may result in better performance. Implantation in children younger than 36 months, however, is complicated by the altered anatomy of the temporal bone in this young age group. We have developed specific modifications in the cochlear implantation technique for this young age group. This technique was used in implantation for 17 children younger than 36 months. The ages ranged from 16 to 36 months and averaged 30 months. All patients except one had complete electrode insertion without complication. The technique of cochlear implantation must be modified not only for differences in anatomy in these young children but also for the expected continued growth of the temporal bone and related structures. Cochlear implantation can be safely performed on children as young as 16 months.

Age Factors↗

Cochlear implantation in children with large vestibular aqueduct syndrome.

OBJECTIVE: This study describes the effectiveness of a multielectrode cochlear implant prosthesis (Cochlear; Cochlear Pty., Lane Cove, Australia) for providing hearing to children with deafness caused by large vestibular aqueduct syndrome (LVAS). STUDY DESIGN: The study design was a retrospective study. SETTING: All the children attended The Children's Cochlear Implant Center (NSW), which is a specialist center that provides audiologic testing, speech therapy, habilitation, and medical assistance for children with cochlear implants. PATIENTS: Ten children were studied who had profound hearing loss and radiologic evidence of a vestibular aqueduct larger than 2 mm in width in its intraosseous portion. INTERVENTION: The children received a multielectrode (Cochlear) cochlear implant prosthesis, and the associated programming of the device and habitation were performed postoperatively. No significant problems were encountered at any of the surgeries, although there was an initial gush of perilymph when the otic capsule was opened in 7 ears. MAIN OUTCOME MEASURES: Postoperative audiologic performance at six monthly intervals and school performance were assessed. RESULTS: The postoperative auditory performance was improved in all children. At 6 months, their average BKB score had increased from 31% to 79%; average word score, from 8% to 43%; and average phoneme score, from 38% to 70%. The older children were able to continue their education in their usual setting with less reliance on hearing support staff. CONCLUSION: Children with a deteriorating hearing loss caused by LVAS can derive considerable benefit from a cochlear implant.

Child↗

Good speech recognition and quality-of-life scores after cochlear implantation in patients with DFNA9.

OBJECTIVE: To compare audiometric and quality-of-life results in DFNA 9 patients who received a cochlear implant with cochlear implant patients with adult-onset progressive sensorineural hearing loss. STUDY DESIGN: Prospective comparative design; results were collected cross-sectionally. SETTING: Tertiary referral center. PATIENTS: Eleven DFNA 9 patients were included in the study as well as a comparative group of 39 post-lingually deafened cochlear implant subjects with adult-onset progressive sensorineural hearing loss. INTERVENTIONS: All patients received a cochlear implant. Subjects were implanted with either the Nucleus 24 M/RCS or Med-el Combi 40+ cochlear implant systems implementing the SPEAK, ACE, or CIS+ coding strategies. MEAN OUTCOME MEASURES: Speech recognition was determined by means of phonetically balanced monosyllabic word lists. The Hearing Handicap Inventory for Adults, the Glasgow Benefit Inventory, and the Scale for the Prediction of Hearing Disability in Sensorineural Hearing Loss were used to quantify the quality of life. RESULTS: The results show that the speech perception and the quality of life of the DFNA 9 patients do not differ significantly from the control group (p=0.179; p=0.56). CONCLUSION: In spite of the fact that DFNA 9 is a disease that is known to involve cochlear dendrites, cochlear implantation is a good option for treatment of deafness in DFNA 9.

Adult↗

Cochlear implantation in Mondini dysplasia.

The use of cochlear implantation to treat patients with inner ear malformations such as Mondini dysplasia has been increasingly successful. Until now, conventional hearing aids in these patients have not performed well. Consequently, the hearing problem for patients with this condition has been somewhat improved with the use of cochlear implants. Various results of cochlear implantation have been reported in these patients so far. This is a report of 5 patients with Mondini malformation who have undergone cochlear implant surgery.

Child, Preschool↗

Comparison of speech perception in pediatric CLARION cochlear implant and hearing aid users.

Multichannel cochlear implants (CIs) allow many profoundly deaf children to achieve high levels of speech perception. In order to develop optimal criteria for implantation, it is crucial to test representative samples (or, if possible, full populations) of CI users and compare their results to those of hearing aid (HA) users of the same age and communication mode (oral or total communication) to determine which subgroups of HA users may obtain more perceptual benefit from a CI than from an HA. Word and phoneme identification skills of deaf children who use either HAs or CIs were evaluated and compared. The CI group included all of the prelingually deaf children in the United States who were implanted with the CLARION Multi-Strategy Cochlear Implant during the clinical trial (as of January 1998). Before implantation, the mean scores on the PB-K test (scored phonemically) were lower for prospective CI users than for HA users. However, by 12 to 18 months postimplantation, the average scores for the CI users were higher than those of HA users with residual hearing in the 101- to 110-dB hearing level (HL) range. The CI scores were similar to those of HA users with residual hearing in the 90- to 100-dB HL range.

Adolescent↗

Electrical Suppression of Tinnitus via Cochlear Implants.

Electrical suppression of tinnitus via a cochlear implant is a secondary benefit for many cochlear implant recipients. In this study, a sample of 78 adult cochlear implant users were surveyed. Data was compiled from 64 completed questionnaires. A high prevalence of preoperative tinnitus was documented in profoundly deaf adult cochlear implant users. Although only a few subjects reported that their tinnitus was totally eliminated after implantation, many users reported improvement or stabilization. Duration of tinnitus appeared to be a significant factor as all subjects who reported a significant improvement had less than a 20-year history of tinnitus.

Journal Article↗

Children with cochlear implants: parental perspective.

OBJECTIVE: Evaluation of the parental perspective regarding cochlear implants and the child's progress after a minimum of 1 year after cochlear implantation. STUDY DESIGN: A closed-set questionnaire was used to assess the parental point of view. The questionnaire that was mailed to families included the following sections: decision to implant, process of implantation, positive effect of the implant, communication, supporting the child, self-reliance, well-being and happiness, social relationships, education, and pre- and postoperative services provided by the implant center. SETTING: The study was conducted at SSK Ankara Hospital, which is a tertiary care center. PATIENTS: Parents of 28 children with congenital deafness or who became deaf before the age of 3 years and received cochlear implantation were included in the study. To obtain reliable information, selected patients had a minimum of 1 year experience after implantation. The subjects were the parents of a group of children including 19 boys and 9 girls with ages ranging from 2 to 13 years (mean, 5.07 years; standard deviation, 2.33 years). The period of cochlear implant usage ranged from 12 to 30 months (mean, 19.5 months; standard deviation, 15.95 months). MAIN OUTCOME MEASURE: Assessment of parental view about cochlear implantation. RESULTS: Of 28 questionnaires sent, 27 were returned. Making decision for cochlear implantation was one of the most stressful steps for the parents. Although speech and language development was the major concern, parents reported outstanding improvement in communication skills, social relationships, and self-confidence for their child. All the families were anxious about a possible device failure, and maintenance of the cochlear implant equipment was another major concern. CONCLUSIONS: During pre- and postimplantation processes, parents provide an important link between the child and professional staff and have a vital role in the child's life and rehabilitation. The parental perspective presented in this study can be useful to the implant centers to revise their practice accordingly and improve the information given to candidate families.

Attitude to Health↗

Cochlear implantation via the round window membrane minimizes trauma to cochlear structures: a histologically controlled insertion study.

OBJECTIVE: To evaluate cochlear implant trauma to intracochlear structures when inserting the electrode via the round window membrane. MATERIAL AND METHODS: Eight fresh human temporal bones were evaluated histologically after insertion using two types of cochlear implant array. Bones underwent a special fixation and embedding procedure that allowed sectioning of undecalcified bone with the electrode in situ. Insertions depths were evaluated radiologically and histologically. RESULTS: All arrays were found in the scala tympani of the cochlea. Basal trauma could be avoided in all but one specimen. The mean depth of insertion was 382.5 degrees. Apically, only one implanted bone showed cochlear trauma exceeding lifting of the basilar membrane. CONCLUSION: Insertions through the round window membrane were shown to be atraumatic, even in basal cochlear regions. This route of insertion might be very effective for combined electric and acoustic stimulation of the auditory system.

Cochlea↗

[Presentation of the prototype of a fully implanted cochlear prosthesis].

Description of the prototype of a fully implanted cochlear implant demonstrating the feasibility of a prosthesis with no external component within the next few years. The battery is reloaded by means of electromagnetic induction, and the sound message is received by a subcutaneous microphone, which already has a satisfactory bandwitch and signal-to-noise ratio. This system can be generally applied to most types of permanent intracorporeal stimulation.

Cochlear Implants↗

Cochlear implantation in a patient with bilateral deep brain stimulators.

OBJECTIVE: We report the case of a patient successfully implanted with a Nucleus Contour cochlear implant after placement of a deep brain stimulator for Parkinson disease. METHODS: The authors conducted a case report and literature review. RESULTS: Successful hookup and mapping of the device was performed 1 month after implantation without evidence of aberrant activity of the deep brain stimulators. CONCLUSIONS: To our knowledge, this is the first reported case of successful implantation of both a cochlear implant and a deep brain stimulator in the same patient. We have outlined one approach to avoiding detrimental interactions between cochlear implant and deep brain stimulator devices.

Cochlear Implantation↗

Sound-direction identification with bilateral cochlear implants.

OBJECTIVE: The purpose of this study was to compare the accuracy of sound-direction identification in the horizontal plane by bilateral cochlear implant users when localization was measured with pink noise and with speech stimuli. DESIGN: Eight adults who were bilateral users of Nucleus 24 Contour devices participated in the study. All had received implants in both ears in a single surgery. Sound-direction identification was measured in a large classroom by using a nine-loudspeaker array. Localization was tested in three listening conditions (bilateral cochlear implants, left cochlear implant, and right cochlear implant), using two different stimuli (a speech stimulus and pink noise bursts) in a repeated-measures design. RESULTS: Sound-direction identification accuracy was significantly better when using two implants than when using a single implant. The mean root-mean-square error was 29 degrees for the bilateral condition, 54 degrees for the left cochlear implant, and 46.5 degrees for the right cochlear implant condition. Unilateral accuracy was similar for right cochlear implant and left cochlear implant performance. Sound-direction identification performance was similar for speech and pink noise stimuli. CONCLUSIONS: The data obtained in this study add to the growing body of evidence that sound-direction identification with bilateral cochlear implants is better than with a single implant. The similarity in localization performance obtained with the speech and pink noise supports the use of either stimulus for measuring sound-direction identification.

Acoustic Stimulation↗

The vestibulo-ocular reflex response to head impulses rarely decreases after cochlear implantation.

OBJECTIVE: Measure vestibular function using the head impulse test and assess the change in function due to unilateral cochlear implantation. BACKGROUND: Cochlear implantation entails risks to vestibular function in the implanted ear. However, the nature and extent of this risk is not known. The head impulse test uses physiologically relevant stimuli that allow detection of subtle changes in vestibular function of individual semicircular canals. SUBJECTS: Sixteen adults (age, 28-65 years) were recruited for prospective study from the Listening Center at Johns Hopkins. Eleven of these subjects were tested 4 to 6 weeks after cochlear implantation. METHODS: Three-dimensional eye movement recordings were made using the scleral search coil technique. Stimuli were rapid, passive, transient, head-on-body rotations (acceleration approximately 3000 degrees /s) in the direction excitatory for each of the six semicircular canals. RESULTS: Of the 16 subjects measured preoperatively, 6 (36%) had low (< 0.74) VOR gains in one or both of the horizontal canals and 8 (50%) had low (< 0.64) vestibulo-ocular reflex (VOR) gains in one or more of the vertical canals. These preoperative gain deficits were bilateral in six subjects. The VOR gain did not significantly change after implantation in 10 out of the 11 subjects tested postoperatively. The remaining subject suffered a partial loss of function in the implanted ear and was the only subject who experienced transient vertigo and oscillopsia after implantation. CONCLUSIONS: Preoperative vestibular deficits were common among this group of candidates for cochlear implantation; however, significant loss of vestibular function due to cochlear implantation was uncommon.

Acceleration↗

Modeling the relationship between psychophysical perception and electrically evoked compound action potential threshold in young cochlear implant recipients: clinical implications for implant fitting.

OBJECTIVE: In cochlear implant recipients, the threshold of the electrically evoked compound action potential (ECAP) has been shown to correlate with the perceptual detection threshold and maximum comfortable loudness levels (respectively, T- and C-levels) used for implant programming. Our general objective was to model the relationship between ECAP threshold and T/C-levels by taking into account their relative changes within each subject. In particular, we were interested in investigating further the validity of ECAP threshold as a predictor of psychophysical levels, depending on intra-cochlear electrode location and time of testing (from 1 to 18 months post-implantation). METHODS: A total of 370 ECAP thresholds, measured in 49 children, using a Nucleus 24 cochlear implant, were compared with the corresponding T- and C-levels obtained at the same visit, for the same electrode. Response profiles for the whole group of patients were modeled across four test electrodes spaced equally along the electrode array from base towards apex. A linear regression model was constructed and the quality of the ECAP threshold-based predictions was assessed by testing for correlation between measured and predicted psychophysics. Comparison was made with a more simplistic model (described here as the 'parallel profiles method') stipulating, within each subject, a 1 microA increase in psychophysical levels for every 1 microA increase in ECAP threshold. RESULTS: Offset between ECAP threshold and psychophysics profiles was found to vary significantly along the electrode array for the T-, but not for the C-level. In contrast with the parallel profiles method, our regression model predicted, within each subject, an average increase of 0.23 microA (95% confidence interval: 0.18-0.28) in T-level for every 1 microA increase in ECAP threshold. This correction improved the quality of T-level prediction when our model was run using measured T-level and ECAP threshold from a reference electrode (r=0.77 vs. r=0.62). The shorter the distance between the electrode for which T-level was predicted and the one used as reference, the stronger the correlation between measured and predicted T-levels. In addition, poorer T-level predictions were obtained at the basal end of the array during the first 3 months post-implantation. In contrast to T-level, individual changes in C-level with ECAP threshold exhibited heterogeneous patterns across subjects so that no common coefficient could account for these changes. However, applying the parallel profiles method led to high-quality C-level prediction. CONCLUSIONS AND SIGNIFICANCE: The results suggest that covariation between ECAP thresholds and psychophysics plays a decisive role in the relationship of ECAP threshold with T-, but not with C-level. Therefore, our regression model and the parallel profiles method should both be used for predicting, respectively, the T- and the C-levels. Although the predictability of our regression model seems to be better for middle and apical electrodes, its utilization should be extended to basal electrodes after 6 months' implant use.

Action Potentials↗