NIH Consensus StatementVolume 13, Number 2

May 15–17, 1995

Cochlear Implants inAdults and Children

NATIONAL INSTITUTES OF HEALTHOffice of the Director

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Cochlear Implants in Adults and Children. NIH ConsensStatement 1995 May 15-17; 13(2): 1-30

NIH Consensus StatementVolume 13, Number 2

May 15–17, 1995

Cochlear Implants inAdults and Children

NATIONAL INSTITUTES OF HEALTHOffice of the Director

AbstractObjective. To provide clinicians and other health care

providers with a current consensus on the benefits, limit-ations, and technical and safety issues that need to beconsidered in the use of cochlear implants.

Participants. A non-Federal, nonadvocate, 14-memberconsensus panel representing the fields of otolaryngology,audiology, speech-language pathology, pediatrics, psychol-ogy, and education and including a public representative.In addition, 24 experts in auditory anatomy and physiology,otolaryngology, audiology, aural rehabilitation, education,speech-language pathology, and bioengineering presenteddata to the consensus panel and a conference audienceof 650.

Evidence. The literature was searched through Medlineand an extensive bibliography of references was providedto the panel and the conference audience. Experts pre-pared abstracts with relevant citations from the literature.Scientific evidence was given precedence over clinicalanecdotal experience.

Consensus. The panel, answering predefined consensusquestions, developed its conclusions based on the scientificevidence presented in open forum and the scientific literature.

Consensus Statement. The panel composed a draftstatement that was read in its entirety and circulated to theexperts and the audience for comment. Thereafter, the panelresolved conflicting recommendations and released a revisedstatement at the end of the conference. The panel finalizedthe revisions within a few weeks after the conference.

Conclusions. Cochlear implantation improves communi-cation ability in most adults with severe to profound deafnessand frequently leads to positive psychological and socialbenefits as well. Currently, children at least 2 years old andadults with profound deafness are candidates for implantation.Cochlear implant candidacy should be extended to adultswith severe hearing impairment and open-set sentence dis-crimination that is less than or equal to 30 percent in the bestaided condition. Access to optimal education and (re)habilita-tion services is important for adults and is critical for childrento maximize the benefits available from cochlear implantation.

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IntroductionCochlear implants are now firmly established as effectiveoptions in the habilitation and rehabilitation of individuals withprofound hearing impairment. Worldwide, more than 12,000people have attained some degree of sound perception withcochlear implants, and the multichannel cochlear implant hasbecome a widely accepted auditory prosthesis for both adultsand children. The vast majority of deaf adults with cochlearimplants derive substantial benefit when the implant is usedin conjunction with speechreading. As a result of cochlearimplantation, many of these individuals are able to understandsome speech without speechreading, and some are able tocommunicate by telephone. Benefits have also been observedin children, including those who lost their hearing prelingually;moreover, there is evidence that the benefits derived improvewith continued use. New speech–sound processing tech-niques continue to improve the effectiveness of cochlearimplants, increasing user performance beyond previous levels.

The NIH sponsored a Consensus Development Conference(CDC) on Cochlear Implants in 1988. Since then, implanttechnology has improved substantially. Some questionsunanswered at that conference have been resolved, andnew issues have emerged that must be addressed.

For example, the performance of some severely to profoundlyhearing-impaired adults using hearing aids is poorer than thatof more severely hearing-impaired individuals using cochlearimplants with advanced speech-processing strategies. It ispossible that cochlear implants could benefit some of theseindividuals. Therefore, the criteria for implantation should bere-examined. The ability to predict preoperatively the level ofperformance at which an individual implant recipient willfunction is highly desirable. Currently, the limited predictionof implant efficacy in a specific individual remains a pressingproblem. Agreement does not exist on the definition of asuccessful implant user. What are the appropriate expecta-tions for individuals using cochlear implants? How is benefitdefined and measured? What are the audiological, educa-tional, and psychosocial impacts of this intervention and is itcost-effective? Advancing technology will allow for the modifi-cation of existing devices or the development of new devices.

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Therefore, it is important to know what risks and benefits areassociated with device explantation/reimplantation. Surgicaland other risks and possible long-term effects of cochlearimplants require evaluation.

Implantation of individuals with multiple disabilities, theelderly, and children, particularly children who are preling-ually deaf, engenders special questions. Longitudinal studiesare providing information on the development of auditoryspeech perception and production and language skills indeaf children with a cochlear implant. What educationalsetting is best for the development of speech and languagein these children? Are cochlear implants efficacious inchildren who are prelingually deaf?

To address the issues that have arisen since the 1988 CDCon Cochlear Implants, the National Institute on Deafness andOther Communication Disorders, together with the NIH Officeof Medical Applications of Research, convened a CDC onCochlear Implants in Adults and Children, May 15–17, 1995.The conference was cosponsored by the National Instituteon Aging, the National Institute of Child Health and HumanDevelopment, the National Institute of Neurological Disordersand Stroke, and the Department of Veterans Affairs.

The conference was convened to summarize current knowl-edge about the range of benefits and limitations of cochlearimplantation that have accrued to date. Such knowledge isan important basis for informed choices for individuals andtheir families whose philosophy of communication is dedicatedto spoken discourse. Issues related to the acquisition of signlanguage were not directly addressed by the panel, becausethe focus of the conference was on new information oncochlear implant technology and its use. The panel acknowl-edges the value and contributions of bilingual and biculturalapproaches to deafness.

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This conference brought together specialists in auditoryanatomy and physiology, otolaryngology, audiology, auralrehabilitation, education, speech–language pathology, bio-engineering, and other related disciplines as well as represen-tatives from the public. After 11/2 days of presentations andaudience discussion, an independent, non-Federal consensuspanel weighed the scientific evidence and developed astatement that addressed the following five questions:

● What Factors Affect the Auditory Performance ofCochlear Implant Recipients?

● What Are the Benefits and Limitations of CochlearImplantation?

● What Are the Technical and Safety Considerations ofCochlear Implantation?

● Who Is a Candidate for Cochlear Implantation?

● What Are the Directions for Future Research onCochlear Implantation?

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What Factors Affect the AuditoryPerformance of CochlearImplant Recipients?

Subject FactorsAuditory performance, defined as the ability to detect, dis-criminate, recognize, or identify acoustic signals, includingspeech, is highly variable among individuals using cochlearimplants. Since the 1988 CDC on Cochlear Implants, however,some factors associated with outcome variability are nowbetter understood.

Etiology. Because of a larger subject sample, the effectsof etiology can now be distinguished from other factors suchas the duration of deafness and the age of onset. For example,deafness due to meningitis does not necessarily limit thebenefit of cochlear implantation in the absence of centralnervous system complications, cochlear ossification, orcochlear occlusion. Children with congenital deafness andchildren with prelingually acquired meningitic deafness, forexample, achieve similar auditory performance if the cochlearimplant is received before age 6. In general, etiology doesnot appear to affect auditory performance in either childrenor adults.

Age of Onset of Deafness. The age of onset continuesto have important implications for success with cochlearimplantation, depending on whether the hearing impair-ment occurred before (prelingual), during (perilingual),or after (postlingual) learning speech and language. Atthe last CDC, data on cochlear implantation suggestedthat children or adults with postlingual onset of deafnesshad better auditory performance than children or adultswith prelingual or perilingual onset. Current data aboutauditory performance in children over longer times sup-port this finding. However, the difference between childrenwith postlingual and those with prelingual-perilingual onsetof deafness appears to lessen with time. Large individualdifferences remain within each group, however.

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Age at Implantation. Previous data suggested thatprelingually or perilingually deafened persons who wereimplanted in adolescence or adulthood did not achievethe same level of auditory performance as those implantedduring childhood, although individual differences wererecognized. Current data continue to support the impor-tance of early detection of hearing loss and implantationfor maximal auditory performance. However, it is still unclearwhether implantation at age 2, for example, ultimately resultsin better auditory performance than implantation at age 3.

Duration of Deafness. As deafness endures, even inpostlingually deafened individuals, some auditory andlinguistic skills may decline and some behavioral traits thatwork against successful adaptation to a sensory devicemay develop. Individuals with shorter durations of auditorydeprivation tend to achieve better auditory performance fromany type of sensory aid, including a cochlear implant, thando individuals with longer durations of auditory deprivation.

Residual Hearing. Initially, cochlear implant use wasrestricted to persons with profound hearing loss (pure-tone threshold average (PTA) of greater than 100 dB HLand no open-set speech recognition ability with best-fithearing aids). The average auditory performance of thesecochlear-implant users has been better than the averageauditory performance of hearing-aid users with someresidual hearing, that is, severe hearing loss (PTA > 90 dBHL) and some (<30 percent) open-set speech recognitionability with best-fit hearing aids. Recent data show thatauditory performance in people with residual hearingimproves after cochlear implantation relative to pre-operative auditory performance, although the degree ofimprovement could not be predicted from preoperativehearing sensitivity. Research is now addressing the criticaldistinction between the importance of residual hearingsensitivity compared with overall residual auditorycapacities and functional communicative status.

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Electrophysiological FactorsSome surviving spiral ganglion cells are necessary forauditory performance with a cochlear implant. Degenerativechanges occur in both ganglion cells and central auditoryneurons following sensorineural deafening. Although arelationship between the number of surviving ganglioncells and psychophysical performance has been demon-strated in animals, a direct relationship between ganglioncell survival and level of auditory performance in humanshas not been shown. Animal studies also suggest thatelectrical stimulation increases ganglion cell survival andalso modifies the functional organization of the centralauditory system. The implications of these new findingsfor humans remain to be determined.

Device FactorsThe task of representing speech stimuli as electrical stimuliis central to the design of cochlear implants. Designs varyaccording to (1) the placement, number, and relationshipamong the electrodes; (2) the way in which stimulus informa-tion is conveyed from an external processor to the electrodes;and (3) how the electrical stimuli are derived from the speechinput (and other signals). Changes in cochlear implantdesign/processing strategies and their effects on auditoryperformance are discussed in the section on technical andsafety considerations.

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What Are the Benefits and Limitations ofCochlear Implantation?

Impact on Speech Perception in AdultsCochlear implantation has a profound impact on hearing andspeech perception in postlingually deafened adults. Mostindividuals demonstrate significantly enhanced speechread-ing capabilities, attaining scores of 90–100 percent correcton everyday sentence materials. Speech recognition affordedby the cochlear implant effectively supplements the informa-tion least favorably cued through speechreading. A majorityof those individuals with the latest speech processors fortheir implants will score above 80-percent correct on high-context sentences, even without visual cues. Performanceon single-word testing in these individuals is notably poorer,although these scores have improved significantly with newerspeech-processing strategies. Recognition of environmentalsounds and even appreciation of music have been repeatedlyobserved in adult implant recipients. Noisy environmentsremain a problem for cochlear-implanted adults, significantlydetracting from speech-perception abilities. Prelingually deaf-ened adults generally show little improvement in speech per-ception scores after cochlear implantation, but many of theseindividuals derive satisfaction from hearing environmentalsounds and continue to use their implants.

Speech Perception, Speech Production, and LanguageAcquisition in ChildrenImprovements in the speech perception and speech produc-tion of children following cochlear implantation are oftenreported as primary benefits. Variability across children issubstantial. Factors such as age of onset, age of implantation,the nature and intensity of (re)habilitation, and mode of com-munication contribute to this variability. Using tests commonlyapplied to children and adults with hearing impairments (e.g.,pattern perception, closed-set word identification, open-setperception), perceptual performance increases on averagewith each succeeding year post implantation. Shortly afterimplantation, perform-ance may be broadly comparable to thatof some children with hearing aids and over time may improve

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to match that of children who are highly successful hearing aidusers. Children implanted at younger ages are on averagemore accurate in their production of consonants, vowels,intonation, and rhythm. Speech produced by children with implantsis more accurate than speech produced by children with com-parable hearing losses using vibrotactile devices or hearingaids. One year after implantation, speech intelligibility is twicethat typically reported for children with profound hearingimpairments and continues to improve. Oral–aural commu-nication training appears to result in substantially greaterspeech intelligibility than manually based total communication.

The language outcomes in children with cochlear implantshave received less attention. Reports involving small numbers ofchildren suggest that implantation in conjunction with edu-cation and habilitation leads to advances in oral languageacquisition. Data on cognitive and academic developmentfollowing implantation are not yet available. The nature andpace of language acquisition may be influenced by the ageof onset, age at implantation, nature and intensity of habili-tation, and mode of communication.

One current limitation is that children are typically implantedat no earlier than 2 years of age, which is beyond putativecritical periods of auditory input for the acquisition of orallanguage. Benefits are not realized immediately, but ratherare manifested over time, with some children continuing toshow improvement over several years.

Few studies have used language as an outcome measure.The assessment of speech perception, language production,and language comprehension in young children is particularlychallenging. Furthermore, results in children have been repor-ted for single-channel or feature-based devices only, whichdo not include the effects of the relatively rapid evolution ofalternatives in speech-coding strategies. Oral language develop-ment in deaf children, including those with cochlear implants,remains a slow, training-intensive process, and results typicallyare delayed in comparison with normally hearing peers.

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Psychologic and Social Issues in Adults and ChildrenAlthough psychological evaluation has been a part of thepreimplant evaluation process, comparatively little researchhas been conducted on the long-term psychological andsocial effects of implantation. Still, the psychological andsocial impact for adults is generally positive, and thereappears to be agreement between preimplantation expecta-tions and later benefit. This benefit is expressed as a declinein loneliness, depression, and social isolation and an increasein self-esteem, independence, social integration, and voca-tional prospects.

Many adult implant recipients report being able to functionsocially or vocationally in ways comparable to those withmoderate hearing loss. Furthermore, they describe a newor renewed curiosity about the experience of hearing andthe phenomena of sound. In some cases the experience ofimplantation becomes an integral part of the individual’sidentity, leading these implant users to participate andshare experiences in support and advocacy groups.

Negative psychological and social impact is less frequentlyobserved and is often related to concerns about the mainte-nance and/or malfunction of the implant and external hard-ware. Other social insecurities may result from the difficultyof hearing amidst background noise, and from unreasonableexpectations of aural-only benefit on the part of implant usersor their family and friends.

The assessment of psychological impact in children withimplants lags behind that for the adult population, in partbecause psychological outcome is a factor of audiologicalbenefit, which is realized more slowly in children. Additionally,such assessment must consider the child’s family setting.Because language acquisition is closely associated withidentity, social development, and social integration, theimpact of implantation on a child’s development in theseareas deserves more study to produce useful indicatorsthat can bear upon the parental decisionmaking processes.

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Rehabilitation and Educational IssuesAlthough a cochlear implant can provide dramatic augmentation ofthe auditory information perceived by deaf children and adults,training and educational intervention are fundamental for opti-mal postimplant benefit. Access to postimplant rehabilitationinvolving professionals familiar with cochlear implants must beprovided to ensure successful outcomes for implant recipients.

Rehabilitation efforts must be tailored to meet individualneeds, and protocols should be developed to reflect therapieseffective for various types of individuals receiving implants.Therapeutic intervention with prelingually deaf adults maydiffer significantly in both time and content from that withpostlingually deaf recipients.

Pediatric cochlear implantation requires a multidisciplinaryteam composed of physicians, audiologists, speech–languagepathologists, rehabilitation specialists, and educators familiarwith deafness and cochlear implants. These professionalsmust work together in a long-term relationship to support thechild’s auditory and oral development. Although the effectsof communication mode in implantation habilitation have notbeen sufficiently documented, it is clear that the educationalprograms for children with cochlear implants must includeauditory and speech instruction using the auditory informa-tion offered by the implant.

Cost–UtilityThe cost-benefit or cost-utility of cochlear implantation mustbe calculated separately for adults and children. For adults,the cost of cochlear implantation includes the initial costs ofassessment, the device, implantation, rehabilitation, systemoverhead, and maintenance. The benefit or utility is estimatedas a function of quality of life over time. On this basis, cochlearimplantation whether at age 45 years or 70 years comparesquite favorably to many medical procedures now commonlyin use (e.g., implantable defibrillator insertion).

The cost-utility estimates for children also appear to be quitefavorable, but we are still in the early stages of cochlear implantapplication and cannot yet estimate the cost or potential costsavings that will accrue in the area of (re)habilitation and education.

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What Are the Technical and SafetyConsiderations of Cochlear Implantation?

Cochlear Implant Design IssuesA cochlear implant works by providing direct electrical stimula-tion to the auditory nerve, bypassing the usual transducer cellsthat are absent or nonfunctional in a deaf cochlea. Over thepast 10 years, significant improvements have been made inthe technology used to accomplish auditory stimulation.

The best performance in speech recognition occurs withintracochlear electrodes that are close to the nerve fibersto be stimulated, thus minimizing undesirable side effects.

Early implants used only a single electrode; these single-channel implants rarely provide open-set speech perception.Most recent implants use multielectrode arrays that providea number of independent channels of stimulation. Suchdevices provide more information about the acoustic signaland give better performance on speech recognition. Noagreement exists on the optimum number of channels,although at least 4-6 channels seem to be necessary.

Much of the recent progress in implant performance hasinvolved improvements in the speech processors, whichconvert sound into electrical stimuli. The best performancecomes with speech processors that attempt to preservethe normal frequency code or spectral representation ofthe cochlea. These are distinguished from feature-basedprocessors, which attempt to analyze certain featuresknown to be important to speech perception and presentonly those features through the electrodes. A major problemin multichannel implants is channel interaction, in whichtwo electrodes stimulate overlapping populations of nerves.Channel interaction has now been minimized with speechprocessors that activate the electrodes in a nonsimultaneous or interleaved fashion; this has been shown to improvespeech recognition significantly.

A final design issue is the means by which the stimulusinformation is passed through the skin from the speechprocessor to the electrodes. In a transcutaneous system,

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the skin is intact and the coupling is done electromagnetic-ally to an implanted antenna. In a percutaneous system, theleads are passed directly through the skin. The two systemshave slightly different surgical complications, which arediscussed below. The percutaneous system (1) provides amore flexible connection to the electrodes in case a changein speech processor is desired, (2) is easier to troubleshootin case of electrode problems, and (3) is magnetic resonanceimaging (MRI) compatible. Percutaneous systems are notcommercially available.

Issues Related to Magnetic Resonance ImagingMagnetic Resonance Imaging (MRI) is increasingly the diag-nostic tool of choice for a variety of medical conditions.Implants that use transcutaneous connectors contain animplanted magnet and some ferrous materials that areincompatible with the high magnetic fields of an MRIscanner. Implant manufacturers are redesigning theirdevices to circumvent this problem. Potential MRI risksshould be part of the informed consent procedure for per-sons considering an implant. The external speech pro-cessor cannot be made MRI compatible and should notbe taken into the scanner.

Surgical IssuesCochlear implantation entails risks common to most surgicalprocedures (e.g., general anesthetic exposure), as well asunique risks that are influenced by device design, individualanatomy and pathology, and surgical technique. Comparativedata of major complications incurred in adult implantationshow a halving of the complication rate to approximately 5percent in 1993. The complication rate in pediatric implanta-tion is less than that currently seen in adults. Overall, thecomplication rate compares favorably to the 10 percent rateseen with pacemaker/defibrillator implantation.

Major complications (i.e., those requiring revision surgery)include flap problems, device migration or extrusion, anddevice failure. Facial palsy, although considered a majorcomplication, is distinctly uncommon and rarely permanent.No mortalities have been attributed to cochlear implantation.

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Alterations in surgical technique, especially flap design, haveled to a considerable reduction in the flap complication rate,which is particularly relevant to transcutaneous devices.Alterations in surgical technique, particularly in methodsused to anchor the device, have contributed to a decreasein device migration or extrusion.

All implants are potentially prone to failure—because of eithermanufacturing defects or use-related trauma. Pedestalfracture is a problem unique to the percutaneous device, butoccurs rarely. Manufacturer redesign has produced newerelectrode arrays that are smaller and sturdier than earliermodels. For the most commonly implanted device, 95 per-cent of implants are still functioning after 9 years. Implantswith transcutaneous connectors that do not provide self-testcapability for the implanted portion preclude detecting elec-trode failure, such as open and short circuits. Failure recogni-tion is particularly problematic in young children. The newercochlear implants do, however, include self-test circuitry thatallows objective device monitoring.

Minor complications, that is, those that resolve withoutsurgical intervention, include unwanted facial nerve stimul-ation with electrode activation, which is readily rectified bydevice reprogramming. In percutaneous devices, pedestalinfections are uncommon but can be treated successfullywith antibiotics; on rare occasions explantation may berequired for control.

Reimplantation is necessary in approximately 5 percent ofcases because of improper electrode insertion or migration,device failure, serious flap complication, or loss of manufac-turer support. In general, reimplantation in the same ear isusually possible, and thus far individual auditory perform-ance after reimplantation equals or exceeds that seen withthe original implant.

Long-term complications of implantation relate to flap break-down, electrode migration, and receiver-stimulator migration.The potential consequences of otitis media have been ofconcern, particularly in children. However, as the implantedelectrode becomes ensheathed in a fibrous envelope, itbecomes isolated from the consequences of local infection.

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Who Is a Candidate for aCochlear Implantation?

AdultsCochlear implants are often highly successful in postlinguallydeafened adults with severe to profound hearing loss and nospeech perception benefit from hearing aids. Previously,individuals eceiving marginal benefit from hearing aids werenot considered implant candidates. Ironically, such individualsoften have poorer speech perception with hearing aids thando more severely deafened persons who use implants.Recent data show that most marginally successful hearingaid users will have improved speech perception performancewith a cochlear implant. Therefore, it is reasonable to extendcochlear implants to postlingually deafened adult individualscurrently obtaining marginal benefit from other amplificationsystems. Prelingually deafened adults may also be suitablefor implantation, although these candidates must be coun-seled regarding realistic expectations. Existing data indicatethat these individuals achieve minimal improvement in speechrecognition skills. However, other basic benefits, such asimproved sound awareness, may provide psychologicalsatisfaction and meet safety needs.

Because of the wide variability in speech perception andrecognition in persons with similar hearing impairments, allcandidates require indepth counseling about the surgery,its risks and benefits, rehabilitation, and alternatives tocochlear implantation. To give adequate informed consent,adult candidates should understand that large variability inindividual audiologic performance precludes preoperativeprediction of success. Determining implant candidacy requiresconsideration of both objective audiological variables as wellas the subjective needs and wishes of individual candidates.Specific criteria for potential adult cochlear implant recipientsare provided below.

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Audiologic Criteria. Indications in favor of an implant area severe-to-profound sensorineural hearing loss bilaterallyand open-set sentence recognition scores less than orequal to 30 percent under best aided conditions. Durationof deafness and age of onset have been shown to influenceauditory performance with cochlear implants and shouldbe discussed with potential candidates.

In general, when there is no residual hearing in either ear,the ear with better closed-set performance, more sensitiveelectrical thresholds, shorter period of auditory deprivation,or better radiologic characteristics is implanted. However,when there is residual hearing, the poorer ear should bechosen if there is radiologic evidence of cochlear patency toretain the option for continued hearing aid use and, thus, thepotential advantages of binaural sound localization.

Medical and Surgical Criteria. Traditionally, implantationcandidacy was limited to persons in good health. Althoughthere are specific medical contraindications to surgery andimplantation, such as poor anesthetic risk, severe mentalretardation, severe psychiatric disorders, and organic brainsyndromes, cochlear implantation should be offered to awider population of individuals. Individuals with low visionmay find that implantation promotes independence andother quality-of-life goals. Age, per se, is not a contra-indication to implantation.

The medical history, physical examination, and laboratorytests are important tools in candidacy evaluation. Individualswith active ear pathology require treatment and re-evaluationprior to implantation. The standard radiologic evaluationincludes high-resolution computed tomography (CT) scanningto detect mixed fibrous and bony occlusions and anatomicalabnormalities. MRI provides better resolution of soft tissuestructures and should supplement the CT scan when indi-cated. These imaging techniques should be used to identify

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abnormalities that may compromise or impede implantsurgery or device use.

The results of electrophysiologic tests do not predict implantsuccess. However, in selected individuals, such as those withcochlear obliteration or in decisions regarding ear of implanta-tion, the results of promontory stimulation may be useful.

ChildrenCochlear implants have also been shown to result in success-ful speech perception in children. Currently, the earliest ageof implantation is 24 months, but there are reasons to reas-sess this age limit. A younger age of implantation may limitthe negative consequences of auditory deprivation andmay allow more efficient acquisition of speech and language.Determining whether cochlear implant benefits are greaterin children implanted at age 2–3 compared with those im-planted at age 4–5 might resolve this issue, but sufficientdata are unavailable. Also, it is unclear whether the benefitsof implantation before age 2 would offset potential liabilitiesassociated with the increased difficulty in obtaining reliableand valid characterization of hearing and functional communi-cation status at the younger age. A small number of childrenunder age 2 have received implants, both internationally andin the United States. Cochlear implants principally have beenperformed in this population because of the risk of new boneformation associated with meningitis, which might precludeimplantation at a later date. Speech and language dataobtained on such children will be helpful in determining thepotential benefits of early implantation and therefore mayhelp to guide future policy.

Audiologic Criteria. Children age 2 years or older withprofound (>90 dBHL) sensorineural hearing loss bilaterallyand minimal speech perception under best aided conditionsmay be considered for cochlear implantation. In the youngchild, auditory brainstem response, stapedial reflex testing,and otoacoustic emission testing may be useful when

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combined with auditory behavioral responses to deter-mine hearing status. Prior to implantation, a trial periodwith appropriate amplification combined with intensiveauditory training should be attempted to ensure thatmaximal benefit is achieved. When the validity of behav-ioral test results is compromised by maturational factors,the above criteria should be applied in the most stringentmanner (i.e., worse hearing sensitivity, longer trial periods,etc.). Current research may broaden audiometric criteriafor candidacy to better reflect functional auditory capacity.

Medical and Surgical Criteria. Children should alsoundergo a complete medical evaluation to rule out thepresence of active systemic disease that would contra-indicate implantation. The child must be otologically stableand free of active middle ear disease prior to cochlearimplantation. The radiologic imaging criteria used in adultcandidates are applicable to children.

Psychosocial Criteria. Preoperative assessment shouldentail evaluation of the child in the home, social, andeducational contexts to ensure that implantation is theproper intervention. In some instances psychosocialfactors may be used as exclusionary criteria; however,in all cases psychosocial data should serve as a baselinefor tracking cochlear implant outcomes. Parental expec-tations must be addressed, and commitment to habilitationis essential.

Informed Consent. The parents of a deaf child are respon-sible for deciding whether to elect cochlear implantation.The informed consent process should be used to assistparents in making this decision. Parents must understandthat cochlear implants do not restore normal hearing andthat auditory and speech outcomes are highly variable andunpredictable. They must be informed of the advantages,disadvantages,and risks associated with implantation toestablish realistic expectations. Furthermore, the impor-tance of long-term habilitation with cochlear implants must

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be stressed. As part of the process of informed consent,parents must be told that alternative approaches to habili-tation are available, for example through sign language.All children should be included in the informed consentprocess to the extent of their ability, as their activeparticipation is crucial to (re)habilitative success.

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What Are the Directions for Future Researchon Cochlear Implantation?● Research must attempt to explain the wide variation in

performance across individual cochlear implant users.New tools, such as functional imaging of the brain, mightbe applied to unexplored variables such as the ability ofthe implant to activate the central auditory system. Investi-gations of the role of higher level cognitive processes incochlear implant performance are needed.

● The strides that have been made in improving speechperception of cochlear implant users should continuethrough improvements in electrode design and signalprocessing strategies. Noise-reduction technologies andenhancement of performance using binaural implants arepromising areas.

● Studies of the effects of cochlear stimulation on auditoryneurons have provided clear evidence of plasticity bothin the survival of neural elements and in receptive fieldorganization. Comparisons of neural plasticity in animalexperiments and of adaptation to cochlear implantelectrical stimulation by humans provide a unique oppor-tunity to study the relationships between neural activityand auditory perception.

● Comparative research on language development in childrenwith normal hearing, children with hearing impairment whouse hearing aids, deaf children with cochlear implants,and deaf children using American Sign Language shouldbe conducted. These studies should be longitudinal andreflect current theoretical and empirical advances in neuro-linguistics and psycholinguistics.

● Studies of the relationship between the development ofspeech perception and speech production in cochlearimplant users must continue. Implanted deaf childrenprovide a unique opportunity to examine these develop-mental processes and their relationship to the acquisitionof aural–oral language. Such information is crucial to under-standing and enhancing the performance of implanted pre-lingually deafened children and may help define optimalage for implantation.

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● Adequate tools for the assessment of nonspeech benefitsof implantation should be applied to gain a better under-standing of the full effects of implantation on the quality oflife of implant recipients. This may be particularly useful forimplant recipients who do not realize significant speech-perception benefit. Such data will help in evaluating thecost–utility of cochlear implantation.

● To identify the components of successful (re)habilitationapproaches, model programs that use alternative educa-tional techniques will need to be compared. Likewise,outcome variations between high and routine quality ser-vice programs that use similar techniques will need to bestudied. The identification of those features and servicesthat correlate with outcome success will facilitate theextension of these features and services to all childrenand adults receiving cochlear implants.

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Conclusions● Cochlear implantation improves communication ability

in most adults with severe to profound deafness andfrequently leads to positive psychological and socialbenefits as well. The greatest benefits seen to date haveoccurred in postlingually deafened adults. Cochlearimplantation in prelingually deafened adults providesmore limited improvement in speech perception, butoffers important environmental sound awareness.Cochlear implantation outcomes are more variable inchildren. Nonetheless, gradual, steady improvement inspeech perception, speech production, and languagedoes occur. There is substantial unexplained variabilityin the performance of implant users of all ages, andimplants are not appropriate for all individuals.

● Currently children at least 2 years old and adults withprofound deafness are candidates for implantation.Cochlear implant candidacy should be extended toadults with severe hearing impairment and open-setsentence discrimination that is less than or equal to30 percent in the best aided condition. Although theo-retic reasons exist to lower the age of implantation inchildren, data are too scarce to justify a change incriteria. Additional data may justify a change in ageand audiologic criteria.

● Auditory performance with a cochlear implant variesamong individuals. The data indicate that performanceis better in individuals who (1) have shorter durations ofdeafness, (2) acquired speech and language before theirhearing loss occurred, and (3) if prelingual were implantedbefore age 6. Auditory performance is not affected byetiology of hearing loss.

● Access to optimal educational and (re)habilitation servicesis important for adults and is critical for children to maxi-mize the benefits available from cochlear implantation.

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● The current generation of intracochlear, multichannelimplants with spectrally based speech processors providesa substantial improvement over the previous generation ofdevices, especially when nonsimultaneous electrodeactivation is used.

● The low complication rate and high reliability for cochlearimplants compare favorably with other implanted electronicdevices and continue to improve.

● Most devices are not MRI compatible, and users andphysicians should be acutely aware of this problem.Implant manufacturers should modify future devices to beMRI compatible and to include internal self-test systems.

● Percutaneous connectors offer many research and clinicaladvantages, including MRI compatibility, ease of electrodetesting, and processor upgrading, and they should not beabandoned.

24

ConsensusDevelopment PanelGeorge A. Gates, M.D.Conference and Panel

ChairpersonProfessor of Otolaryngology–

Head and Neck SurgeryDirectorVirginia Merrill Bloedel Hearing

Research CenterUniversity of WashingtonSeattle, Washington

Kathleen Daly, Ph.D.Assistant ProfessorDepartment of OtolaryngologyUniversity of MinnesotaMinneapolis, Minnesota

William J. Dichtel, M.D.Associate Clinical ProfessorDepartment of Otolaryngology–

Head and Neck SurgeryUniversity of VirginiaRoanoke, Virginia

Robert J. Dooling, Ph.D.ProfessorDepartment of PsychologyUniversity of MarylandCollege Park, Maryland

Aina Julianna Gulya, M.D.ProfessorDepartment of Otolaryngology–

Head and Neck SurgeryGeorgetown UniversityWashington, District of Columbia

Joseph W. Hall III, Ph.D.ProfessorDepartment of SurgeryDivision of OtolaryngologyUniversity of North Carolina at

Chapel HillChapel Hill, North Carolina

Susan W. Jerger, Ph.D.Professor and DirectorChildren’s Special Hearing

SectionDepartment of

OtorhinolaryngologyBaylor College of MedicineHouston, Texas

Jacqueline E. Jones, M.D.Assistant ProfessorDepartment of OtolaryngologyCornell University Medical

College/New York HospitalNew York, New York

Margaret H. Mayer, Ed.D.Coordinator for Teacher

Education and ResearchNorthwest School for Hearing-

Impaired ChildrenSeattle, Washington

Michael PierschallaCambridge, Massachusetts

Lainie Friedman Ross, M.D.,M.Phil.

Assistant ProfessorDepartment of Pediatrics

and MacLean Centerfor Clinical Medical Ethics

University of ChicagoChicago, Illinois

Richard G. Schwartz, Ph.D.ProfessorPh.D. Program in Speech and

Hearing SciencesCity University of New YorkNew York, New York

Barbara E. Weinstein, Ph.D.Associate Professor

of AudiologyDirectorAudiology ProgramLehman CollegeCity University of New YorkNew York, New York

25

Eric D. Young, Ph.D.ProfessorDepartment of Biomedical

EngineeringJohns Hopkins UniversityBaltimore, Maryland

SpeakersPaul J. Abbas, Ph.D.“Factors Affecting Auditory

Performance:Electrophysiologic Measures”

ProfessorDepartment of Speech Pathol-

ogy and AudiologyDepartment of Otolaryngology–

Head and Neck SurgeryUniversity of IowaIowa City, Iowa

Peter Blamey, Ph.D.“Factors Affecting Auditory

Performance ofPostlinguistically DeafAdults Using CochlearImplants: Etiology, Age,and Duration of Deafness”

Principal Research FellowDepartment of OtolaryngologyUniversity of MelbourneEast Melbourne, Victoria,

Australia

Derald E. Brackmann, M.D.,F.A.C.S.

“Percutaneous Connectors inCochlear Implantation”

Clinical Professor ofOtolaryngology–Head andNeck Surgery/Neurosurgery

University of Southern CaliforniaSchool of Medicine

PresidentHouse Ear Clinic and InstituteLos Angeles, California

Judith A. Brimacombe, M.A.“Multichannel Cochlear Implants

in Adults With ResidualHearing”

Vice President of Clinical andRegulatory Affairs

Cochlear CorporationEnglewood, Colorado

Patricia M. Chute, Ed.D.“Residual Hearing in Children”DirectorCochlear Implant CenterManhattan Eye, Ear, and

Throat HospitalNew York, New York

Noel L. Cohen, M.D.“Surgical Complications and

Considerations”Professor and ChairmanDepartment of OtolaryngologyNew York University School

of MedicineNew York, New York

Michael F. Dorman, Ph.D.“Speech Perception by Adults”ProfessorDepartment of Speech and

Hearing ScienceArizona State UniversityTempe, ArizonaAdjunct ProfessorDivision of OtolaryngologyUniversity of Utah Health

Sciences CenterSalt Lake City, Utah

Donald K. Eddington, Ph.D.“Introduction and Overview”Cochlear Implant Research

LaboratoryMassachusetts Eye and

Ear InfirmaryBoston, Massachusetts

26

Bruce J. Gantz, M.D., F.A.C.S.“Device Failure”Professor and Interim HeadDepartment of Otolaryngology–

Head and Neck SurgeryUniversity of Iowa College

of MedicineIowa City, Iowa

James W. Heller, P.E.“MRI Considerations”Manager of ResearchCochlear CorporatioEnglewood, Colorado

Darlene R. Ketten, Ph.D.“Radiologic Assessment”Assistant ProfessorDepartment of Otology and

LaryngologyHarvard Medical SchoolResearch DirectorThree-Dimensional Imaging

ServiceMassachusetts Eye and

Ear InfirmaryBoston, Massachusetts

John F. Knutson, Ph.D.“Psychological and Social Issues

in Cochlear Implant Use”ProfessorDepartment of PsychologySpence Laboratories of

PsychologyUniversity of IowaIowa City, Iowa

Patricia A. Leake, Ph.D.“Long-Term Effects of Electrical

Stimulation”Professor in ResidenceDepartment of OtolaryngologyResearch DirectorEpstein Hearing Research

LaboratoryUniversity of California San

FranciscoSan Francisco, California

Hugh J. McDermott, Ph.D.“Speech Processing Using

Selected Spectral Features”Research FellowDepartment of OtolaryngologyUniversity of MelbourneEast Melbourne, Victoria,

Australia

Richard T. Miyamoto, M.D.,F.A.C.S.

“Timing of Implantation inChildren”

Arilla Spence DeVault Professorand Chairman

Department of Otolaryngology–Head and Neck Surgery

Indiana University School ofMedicine

Indianapolis, Indiana

Jean S. Moog, M.S.“Rehabilitation and Educational

Issues in Children”Director of Deaf EducationCentral Institute for the DeafSt. Louis, Missouri

Mary Joe Osberger, Ph.D.“Effect of Age at Onset of

Deafness on CochlearImplant Performance”

“Speech Perception in Children”DirectorPediatric Clinical ResearchAdvanced Bionics CorporationSylmar, California

Robert V. Shannon, Ph.D.“Information Transmission

in Cochlear Implants:Analysis Channels,Number of Electrodes,and Received Channels”

Auditory Implant ResearchHouse Ear InstituteLos Angeles, California

27

Margaret W. Skinner, Ph.D.“Audiologic Criteria for Cochlear

Implantation in Adultsand Children”

Associate ProfessorDirector of AudiologyDirector of Cochlear Implant

ProgramDepartment of Otolaryngology-

Head and Neck SurgeryWashington University School

of MedicineSt. Louis, Missouri

Quentin Summerfield, Ph.D.“Cost-Effectiveness Considera-

tions in Cochlear Implantation”ProfessorMedical Research CouncilInstitute of Hearing ResearchNottingham, United Kingdom

Emily A. Tobey, Ph.D.“Speech Production in Children”Professor and Nelle C. Johnston

Chair in Early ChildhoodCommunication Disorders

Department of CommunicationDisorders

Callier Center for Communica-tion Disorders

University of Texas at DallasDallas, Texas

Susan B. Waltzman, Ph.D.“Comparison of Implant Systems”ProfessorDepartment of OtolaryngologyNew York University School

of MedicineNew York, New York

Blake S. Wilson, B.S.E.E.“Continuous Interleaved Samp-

ling and Related Strategies”DirectorCenter for Auditory Prosthesis

ResearchResearch Triangle InstituteResearch Triangle Park, North

Carolina

Teresa A. Zwolan, Ph.D.“Factors Affecting Auditory

Performance With a CochlearImplant by PrelinguallyDeafened Adults”

Assistant Research ScientistDirector, Cochlear Implant ProgramDepartment of Otolaryngology-

Head and Neck SurgeryAudiology and Electrophysiology

DivisionUniversity of Michigan Medical

CenterAnn Arbor, Michigan

Planning CommitteeAmy M. Donahue, Ph.D.ChairpersonActing Chief, Hearing and

Balance/VestibularSciences Branch

Division of HumanCommunication

National Institute on Deafnessand Other CommunicationDisorders

National Institutes of HealthBethesda, Maryland

Marin P. Allen, Ph.D.ChiefProgram Planning and Health

Reports BranchNational Institute on Deafness

and Other CommunicationDisorders

National Institutes of HealthBethesda, Maryland

Lucille B. Beck, Ph.D.Associate ChiefAudiology and Speech

Pathology ServiceDepartment of Veterans AffairsWashington, District of Columbia

28

Elsa A. BrayProgram AnalystOffice of Medical Applications

of ResearchNational Institutes of HealthBethesda, Maryland

Judith A. Cooper, Ph.D.Deputy DirectorDivision of Human CommunicationNational Institute on Deafness

and Other CommunicationDisorders

National Institutes of HealthRockville, Maryland

John H. Ferguson, M.D.DirectorOffice of Medical Applications

of ResearchNational Institutes of HealthBethesda, Maryland

Marilyn Neder Flack, M.A.Senior Scientific Reviewer/

AudiologistEar, Nose, and Throat DevicesCenter for Devices and

Radiological HealthOffice of Device EvaluationFood and Drug AdministrationRockville, Maryland

George A. Gates, M.D.Conference and Panel

ChairpersonProfessor of Otolaryngology–

Head and Neck SurgeryDirector of Virginia Merrill

Bloedel Hearing ResearchCenter

University of WashingtonSeattle, Washington

William H. HallDirector of CommunicationsOffice of Medical Applications

of ResearchNational Institutes of HealthBethesda, Maryland

F. Terry Hambrecht, M.D.HeadNeural Prosthesis ProgramNational Institute of Neurological

Disorders and StrokeNational Institutes of HealthBethesda, Maryland

Norman Krasnegor, Ph.D.ChiefHuman Learning and Behavior

BranchCenter for Research for Mothers

and ChildrenNational Institute of Child Health

and Human DevelopmentNational Institutes of HealthBethesda, Maryland

Andrew A. Monjan, Ph.D., M.P.H.ChiefNeurobiology of Aging BranchNeuroscience and

Neuropsychology of AgingProgram

National Institute on AgingNational Institutes of HealthBethesda, Maryland

Ralph F. Naunton, M.D.DirectorDivision of Human

CommunicationNational Institute on Deafness

and Other CommunicationDisorders

National Institutes of HealthRockville, Maryland

29

ConferenceSponsorsOffice of Medical Applications

of Research, NIHJohn H. Ferguson, M.D.Director

National Institute on Deafnessand Other CommunicationDisorders

James B. Snow, Jr., M.D.Director

ConferenceCosponsors

National Institute on AgingRichard J. Hodes, M.D.Director

National Institute of Child Healthand Human Development

Duane F. Alexander, M.D.Director

National Institute of NeurologicalDisorders and Stroke

Zach W. Hall, Ph.D.Director

U.S. Department of VeteransAffairs

Jesse BrownSecretary

30

Statement AvailabilityPreparation and distribution of this statement is the responsi-bility of the Office of Medical Applications of Research of theNational Institutes of Health. Free copies of this statement aswell as all other available NIH Consensus Statements and NIHTechnology Assessment Statements may be obtained fromthe following resources:

NIH Consensus Program Information ServiceP.O. Box 2577Kensington, MD 20891Telephone: 1-800-NIH-OMAR (644-6627)Fax: (301) 816-2494

NIH Office of Medical Applications of ResearchFederal Building, Room 6187550 Wisconsin Avenue MSC 9120Bethesda, MD 20892-9120

Full-text versions of statements are also available onlinethrough an electronic bulletin board system and throughthe Internet:

NIH Information Center BBS1-800-NIH-BBS1 (644-2271)

InternetGophergopher://gopher.nih.gov/Health and Clinical Information

World Wide Webhttp://www.nih.gov/health

ftpftp://public.nlm.nih.gov/hstat/nihcdcs

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