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University of Montana ScholarWorks at University of Montana Theses, Dissertations, Professional Papers Graduate School 1986 Cochlear implants| The audiologist's role Jill E. King The University of Montana Follow this and additional works at: http://scholarworks.umt.edu/etd Recommended Citation King, Jill E., "Cochlear implants| The audiologist's role" (1986). Theses, Dissertations, Professional Papers. Paper 1815. This Professional Paper is brought to you for free and open access by the Graduate School at ScholarWorks at University of Montana. It has been accepted for inclusion in Theses, Dissertations, Professional Papers by an authorized administrator of ScholarWorks at University of Montana. For more information, please contact [email protected]. COPYRIGHT ACT OF 1976 THIS IS AN UNPUBLISHED MANUSCRIPT IN WHICH COPYRIGHT SUB SISTS, ANY FURTHER REPRINTING OF ITS CONTENTS MUST BE APPROVED BY THE AUTHOR. MANSFIELD LIBRARY UNIVERSITY OF MONTANA DATE : 1 988 COCHLEAR IMPLANTS: THE AUDIOLOGIST'S ROLE by Jill E. King B.A., University of Montana, 1984 A Professional Paper Presented in Partial Fu11fi11ment of the Degree of MCSD UNIVERSITY OF MONTANA 1986 Approved by: Chairman, Board of Examiners Dean, Graduate School if Date Q / UMI Number: EP35121 All rights reserved INFORMATION TO ALL USERS The quality of this reproduction is dependent upon the quality of the copy submitted. In the unlikely event that the author did not send a complete manuscript and there are missing pages, these will be noted. Also, if material had to be removed, a note will indicate the deletion. UMI Dissertation Publishing UMI EP35121 Published by ProQuest LLC (2012). Copyright in the Dissertation held by the Author. Microform Edition © ProQuest LLC. All rights reserved. This work is protected against unauthorized copying under Title 17, United States Code uest* ProQuest LLC. 789 East Eisenhower Parkway P.O. Box 1346 Ann Arbor, Ml 48106- 1346 TABLE OF CONTENTS LIST OF FIGURES AND TABLES ii I. 1 1 4 6 6 6 7 7 8 13 15 15 INTRODUCTION Introduct i on Cochlear Implant vs Hearing Aid Implant Components Neural Interface External (Speech) Processor Signal Transfer Hardware Perceptual Mechanism Single vs Mu 1 t i-e 1 ectrode Arrays Digital vs Analog Coding Schemes Intra- vs Extra-coch 1 ear Devices Summary II. THREE COMMON TYPES OF DEVICES 3M/House 3M/V ienna Nuc 1 eus III. IV. V. VI. VII. PATIENT SELECTION - ADULTS General Considerations Age Et l o 1 ogy Hearing Acuity Congenital vs Acquired Loss Additional Factors Medical Assessment Psychological Assessment Audiological Assessment REHABILITATION - ADULTS Summary-Patient Reactions PATIENT SELECTION - CHILDREN Medical Assessment Psychological Assessment Audiological Assessment Speech and Language Assessment Post-Implant Results Summary REHABILITATION - CHILDREN Summary CONCLUSION 17 17 18 19 22 22 22 22 24 25 26 27 30 31 36 44 46 48 48 49 50 50 52 54 55 57 APPENDIX A 64 BIBLIOGRAPHY 65 l LIST OF TABLES. FIGURES AND APPENDIX Figure 1 = Cochlear Implant vs Hearing Aids Page 5 Table 1 = Number of Children Implanted with the 3/M House Device 52 Appendix A = Summary of the 8 Most Common Types of Implant Hardware 64 ii INTRODUCTION A life, hearing impairment regardless of hearing-impaired language affects 1982). in The styles, personal child a natural future experiences when in minimize profoundly deaf Advocates of a an is developing adversely development (Sanders, hearing loss established life preserving Walter, much social and Rehabilitation must as The turn acquired and effects aspects of acquired. in maintaining Jobs, these many difficulties relationships (Sims, cochlear implant is faces with 1982; Alpiner, 1978). to loss cognitive problems retaining the affect manner, which verbal adult may as and Whitehead, be designed possible. A is a medical device that can help some individuals perceive acoustic stimuli. the cochlear technological implant breakthrough increased enrichment of daily believe that the can implant provide an life for hearing impaired persons (Mecklenburg, 1985a). The cochlear to restore individuals implant hearing by a cochlear auditory perception noise, in prothesis of for electrical elements goals of traffic perception direct remaining neuronal is a device that profoundly stimulation the cochlea. include environmental telephones ringing) and ability to detect is designed deaf of the The main obtaining sounds some (e.g., ultimately the and discriminate speech to a greater 1 2 degree than that which is obtained by conventional amp 1i f i cat i on. The basic premise underlying any type of cochlear prothesis was summarized by Keidel (1979, p.163). "Auditory processing is not the exclusive domain of the central auditory system. The nerve signals that leave the cochlea via the cochlear nerve are the end products of a series of complex, interlinked processes that take place partially in the mechanical domain and partially in the sensorineural one. Two main events stand out: 1) There is a systematic space/time distribution of signal components into a number of parallel nerve fibre channels, of which a maximum of about 30,000 are available; and 2) Each component that travels in a single given nerve fibre is encoded in the only form nerve fibres are equipped to handle (i.e., action potentials). In the two underlying processes of conversion, attributes of the original signals are accurately preserved. A reasonable degree of speech intelligibility, the ultimate aim of cochlear protheses, can only be restored if and when the prothesis is capable of handling these two tasks in a fair manner." The makes it stimulate deaf ear complexity unlikely nerve is of coding that fibers achieved. a so in the auditory prothesis normal However, can nerve exactly functioning in implants can the provide some information regarding intensity and duration which should aid in sounds without Seligman, some lipreading and allow recognition of some 1980). frequency stimulation, and/or as place visual cues. (Tong, Attempts have information used of with been as stimulation, mu 11i-e1ectrode devices. made well single Clark, to via electrode as and provide rate of devices, used with 3 Clark, Shepherd, Patrick, Black p.191) stated that any electrical arid T o n g ( 1 9 8 3 , array must meet these certain design requirements: "1) it must be atraumatic in insertion; 2 ) it must be biologically inert (i.e., biocompatible with the tissues); 3) current must be localized (i.e., should not predispose the patient to local infection); 4) only minimal damage should occur with chronic stimulation); 5) it must have mechanical stability (i.e., not prone to break as a result of repeated stress); and 6) fabrication must be practical (i.e., simple and inexpensive)." There implant are currently protheses Appendix A. in The manufacturers of several use. These basic cochlear types are cochlear summarized philosophies implants of of vary in different in terms of: number of electrodes used for stimulation (i.e., single versus mu1ti-e1ectrode (i.e., monopolar: remote ground remaining versus bipolar: spaced current which neurons electrodes systems); stimulation flows between stimulates a and generates current which site of stimulation); versus digital); large wide flows for site of of speech science, electrical of professions otopatho1ogy, an implant a two more including rheology, engineering and of spread; closely localized analog (i.e., (Staller, 1985) system involves a otology, audiology, psychoacoustics, polymer current stimulation intracoch1 ear versus extracoch1 ear). variety population between allows active coding strategies (i.e., and The development an regime and (Radcliffe, e1ectrophysiology, biomechanical 1984). and Other 4 professionals become involved in the rehabilitation and counseling of cochlear pre-operative1y speech/1anguage and implant patients post-operatively pathologists, deaf both (e.g., educators, pyscho1ogi sts). Cochlear Implant Versus Hearing Aids Hearing amplifiers. aids and vibrotactile devices are A hearing aid has the capability of making sound louder and possibly clearer due to an increase in loudness. acoustical attempts A vibrotactile information to increase device through is used tactile auditory to convey stimulation awareness. A in cochlear implant system is also an amplifying device in that the electrical signal his/her most is delivered comfortable to loudness the level, patient at however, the system possesses a speech processor which also selects key acoustical and information (i.e., frequency) (Mecklenburg, to translate to be 1985a). this delivered In intensity, duration, to the addition, the information into implant implant works electrically coded signals that stimulate nerve fibers within the (Staller, 1985). Typical user implant cochlea recipients have coh1 ear pathologies which allows for the stimulation of nerve fibers and makes use functioning auditory system. of the otherwise normal 5 A cochlear the input stage into electrical processed by compression implant is similar to a hearing aid in that acoustical current an by to perceptual characteristics. aid transduces the energy, through the microphone amplifier, circuit two devices is in a energy filter accommodate electrical a stimulating is converted and is then network, and the patient's The difference between the the output stage. implant in signal delivers an Whereas a hearing back to acoustic electrical signal electrode array (Staller, 1985, see Figure 1). Figure 1 Hearing Aid Versus Coch1 ear Implant (Sta11er,1985) Presented at the Denver Ear Institute Cochlear Implant Symposium, Denver, CO. COCHLEAR IMPLANT VS HEARING AID INPUT STAGE ACOUSTIC ENERGY ELECTRICAL ANALOG OUTPUT STAGE modified electrical analog cochlear stimulation electrical distribution acoustic energy cochlear stimulation mechanical distribution 6 Implant Components The goal of any implant system patterns of neural activity that understand (Miller, Most speech implant systems components. Miller can et al. those the brain requires to Tong, be is to elicit and divided Clark, into 1984). four <1984) described major these as including the following. A. Neural Interface: this component generates controlled electrical currents which stimulate auditory nerve fibers. B. processor External is needed (speech) to Processor: transform incoming acoustic speech signal the information speech from into an electrical the form which retains the important speech components but which can also neural be presented at a crude level through the interface of the prothesis. The signal processing strategy utilized depends on which research center is developing and programming the device. which Mu1ti-e1ectrode extracts duration, information and electrode/channel devices and frequency information. duration transmitted to percutaneous plug (i.e., internal utilize the are capable of direct single processing and external electrode(s) strategy intensity, whereas, information The a regarding frequency, intensity to the devices either electrical limited signal through is a connection receiver) or a transcutaneous receiver 7 (i.e., data inductively transmitted to a receiver under the skin via a radio frequency carrier). C. Signal Transfer Hardware: this consists of the internal receiver, external transmitter/connector. microphone, These and components external interact to produce electrical representations of acoustic stimuli and this electrical radio frequency deliver tissue. A transmit this internal The information receiver radio or stimuli carrier across a direct frequency to carrier the may the be skin neural used to to an percutaneous connector. is such designed that correct data obtained from a custom integrated circuit is required before any stimulation occurs. the Implant will be unable response to any external Therefore, to generate stimulation radio frequencies outside in its acceptance band. D. capabilities will Perceptual of integrate define and his/her minimal adult each may auditory have patient to cues. to learn experiences and the (i.e., utilize acoustic ability auditory Mechanism: make The to how perceptual the patient information) will meaningful post 1ingua11y analyze integrate a of deafened new these use set with of past speech processing experiences. The system most fundamental is to generate neural auditory nerve which may function of the implant discharge patterns to the be modulated by external s signals. speech These signals are signal by a derived speech from an processor acoustic and then transferred to an electrode or electrodes at the neural Interface. This results in a perceptual sensation of " s o u n d " ( M i l l e r e t a l ., 1 9 8 4 ) . Single Versus Mu1ti-e1ectrode Arrays There are a variety with a cochlear of electrode arrays utilized prothesis. Information may be transmitted through a single active electrode as a one dimensional active time varying electrodes as a ( M i l l e r e t a l ., 1 9 8 4 ) . extra-coch1 ear or on the pattern or through several mu1ti-dimensiona1 pattern An active electrode can have an placement promontory adjacent to the (Hochmair-Desoyer 1983) or the electrode(s) can be through the round window round and window Hochmair, intracoch1 ear, placed into the sea la tympani (House and Urban, 1973; Mecklenburg, 1985a; Rebscher, Kessler, and Calvert, 1985; Dankowske, 1985; Ferreira, 1985). The two perception, place controversy over mu1ti-e1ectrode regarding pitch theory the systems. delivery electrode(s) which primary within the of the theories and rate pitch, selection of Therefore, frequency cochlea implant regarding often single the pitch cause versus philosophies information differ according manufacturer to to maintains. According to the place pitch theory, the perception of pitch depends on which auditory nerve fibers are firing 9 Impulses. Mu 11i-e1ectrode systems are designed around this theory. of pitch depends impulses. through Rate pitch on Implants one theorists maintain perception how that electrode rapidly deliver are and place are pitch in the normal the designed pitch theory (Kriewel1, 1985). both rate the fibers entire around fire signal the rate The probability is that involved in the perception of auditory system. In simple terms, a single electrode/single channel system consists information to a of a device is coded into an single electrode. stimulation within where all electrical Such acoustical signal applied could involve a system the cochlea or outside the cochlea. There are single electrode, mu1ti-channe1 devices which extract certain attempt to single acoustical deliver electrode this features processed (Hochmair, of speech information 1983). In and to a contrast, a mu1ti-e1ectrode system contains a number of stimulation sites within the cochlea. The coding of acoustic information into electrical stimulation takes advantage of the nerve naturally fibers essence, frequency become in apical energy active in occurring the cochlea electrodes is tonotopic response (Hirshorn, are dominant to organization 1985). stimulated and high The amount of stimulation received basal when of In low electrodes frequency energy. is dependent on the 10 neural population reserve along the cochlea (Meek 1enburg, 1985b). Mu1ti-channe1 processing channel Theoretically, for each mu1ti-channe1 divide the speech allow subjects frequency systems spectrum to employ a customized stimulating electrode. speech in that contiguous bands should discriminate spectral processors components location of basal electrodes. between of the speech higher due to the Therefore, mu1t1-channe1 stimulation as compared with single channel stimulation is believed to more accurately reflect normal auditory nerve excitation patterns (White, Merzenick, and Gardi, 1984).). when However, White two strong or more et electrode Interactions between al.(1984) discovered channels the are and quality of the stimulated, channels Those interactions can then greatly alter sensation that can occur. the loudness evoked during mu1ti-channe1 stimulation. Clark, Black, Dewhurst, Forster, Patrick, and Tong (1977) stated evoke that temporal mu1ti-e1ectrode systems patterns populations of auditory current must flow stimulating different attempted electrodes highly at to using either closely an array 1978). In such cases, so sites active that produces This positioned of to separate localized different sensations (Chouard, by partially nerve fibers. be electrodes in attempt has been bipolar electrodes 11 Interwoven Patrick, with and a common Bailey, electrode array using a cochlea (Berliner and ground electrode 1979) or remote ground Eisenberg, with a (Clark, monopolar external 1985a). to the Danley and Fretz (1982) concluded that common-ground and monopolar electrode arrays however, this the value of provide poorer current is sometimes offset the lower current by localization, an adjustment threshold obtained of by these arrays. Psychophysical (1983) indicated loudness and affected by channel that behavioral threshold changing when stimulated experiments described by Eddington one or responses measures) the more are stimulus than one simultaneously. (i.e., substantially polarity channel Since of are one being interactions generated during simultaneous stimulation can occur, it might be channel useful to avoid separately them in by time stimulating (i.e., temporally interlacing the stimuli across the channels). al. (1984) declined found with Interactions simultaneous interchannel were channel distance decreased with each White et Interactions and bipolar the channel rather than monopolar stimulation. Having a choice of stimulation sites is important for the perception selectivity fibers of (Farrer, of pitch different Mangham, due groups and to of the frequency auditory nerve Kuprenas,1984). The 12 damaged cochlea stimulation Seligman, some at is different 1980). there frequencies For others, frequency discrimination population in electrodes stimulation its response <Tong, Clark, <1980) stated orderly along the will be allow amplitude for at for of on Therefore, individual different from the as clear as dependent cochlea. that length to and progression the response is not the would al . is cochlea. in locations Tong et patients, high-to-low unpredictable neural multiple adjustments electrode of sites. Because of greater number of stimulation sites and thus increased information delivered to the brain, advocates of the mu1ti-channe1/mu1ti-e1ectrode systems suggest that patients do better with speech discrimination even on open-set discrimination tests without lipreading (Mecklenburg, 1985a, Mecklenburg and Brimacombe, 1985b) single Another argument supporting channel systems was mu1ti-channe1 provided by Farrer over et al. <1984, p.75): "In general, the mu1ti-channe1 device allows recognition of more speech elements than the single device through a unique method of extracting and recording the important resonances of the voice and presenting them to the auditory nerve. It offers a choice of stimulation sites in the cochlea as well as several variable dimensions with which to code incoming acoustic signals." Single their device clinical channel/single electrode is trials a and proven one with examinations Implant system has built-in potential advocates argue more and the years of present for upgrading as 13 new devices are developed (Berliner, 1985). The 3M/House single channel/single electrode unit also has the from advantage of having received approval the Food and Drug Administration (FDA) for use with adults and children NUCLEUS (Berliner and mu1ti-e1ectrode Eisenberg, device also 1985b). has FDA The approval for use with adults and they have recently received FDA approval to use their device on children ages 10-18 years. Comparisons systems have superior between shown in of Eddington recognition results for two-syllable words and mu1ti-e1ectrode terms discrimination. single (1983) devices better found for single channel to recognition that open-set, unpracticed were systems than the best speech mu1ti-e1ectrode be and speech lists of mu1ti-channe1 results reported. However, Eddington (1983) also pointed out that because the processing schemes used by single channel are different, drawing any firm the merits of the relative patients conclusions regarding single channel and mu1ti-channe1 stimulation scheme is difficult. Digital Versus Analog Coding Schemes There are two major coding strategies utilized in the different the market: implant speech processors analog versus digital coding. currently on 1A A. signal Ana Ioa: which Acoustic This system is energy comparable filtered to The more analog compensate characteristics. or to is converted representation. the an electrical sound stimulus. into a direct signal for the This signal electrodes utilizes is compressed patients is then CHochmair, electrical and perceptual delivered to one 1983). This type of system may introduce added noise but improves precision of timing and current B. Digital: series of the charge speech level (Miller et al., 1984). Digital balanced signal. coding schemes utilize electrical The pulses to incoming signal is a encode processed and selected electrodes are stimulated corresponding to various formats generate from a a of pulse speech. each time the positive to negative characteristics intensity) signal. by This extraction of the certain has Digital either signal crosses input voltage or pulses key also systems (Mecklenburg, (i.e., features been determines the of referred 1985a, to rate and the speech as feature Mecklenberg and Brimacombe, 1985a). The digital processing scheme has been reported to decrease also transmission limits the noise precision (Miller et al., 1984). of problems but timing and this current scheme level 15 Intra-coch1 ear Versus Extra-coch1 ear Devices Extra-coch1 ear devices, those which are placed on the promontory, the internal device may have the auditory cochlea. delivered to more advantageous than more and, sensitive being safer However, frequency and nerve devices such a intensity fibers within are to believed to the be extra-coch1 ear devices as seal a require electrophysiological electrodes of the Intra-coch1 ear electrodes of structures. limit the amount information tympani advantage less responses thus, current than do intra-coch1 ear thresholds than to evoke round window devices reveal extra-coch1 ear (Simmons,Lusted, Meyers, and Shelton, 1984). devices However, the placement of intra-coch1 ear devices do increase the risk of damaging the scala tympani. Summary The optimum coding scheme remains controversial at this time. strategies Clearly, the are difficult in assessment differences investigators and to the merits to of assess tests used differences populations (Hochmai r-Desoyer, 1984). it that, might amount eventually of stimulation nerve turn out survival, scheme will the be different due by depending chosen the different the complexity Hochmair-Desoyer, and Hochmair, 1985). to between In coding patient future, on of the the (Wallenberg, 16 Children and prelingually deafened adults are not considered good candidates for due to their Their lack to because the necessary adequate lack of experience with acoustic stimuli. of trying experience adequately patients feedback fitting stated current amount of the mu 11i-e1ectrode devices to would adjust would be the unable to processor the to ensure Kriewell (1985) systems utilized when provide used delivered to the currently problems speech 1985). mu1ti-e1ectrode strategies the clinician (Kriewell, information create may limit the cochlea due in to mu1ti-channe1 speech processors. Such strategies focus primarily on processing information speech appropriately process and environmental thus sound result, could be confusing to the patient. might and, not as a THREE COMMON TYPES OF DEVICES 3M/House The 3M/House electrode/single-channel processor, and House, 1985). which electrical current processor. a A which then coil and to a is this to a ground of sound. of a internal Eisenberg, an electret energy into current signal is to a directed e1ectromagnetica 1 1 y transcutaneous flow stimulates auditory neural perception has is then transmitted to an flows single consists acoustic electrical skin a transmitter, transmits modulated induced across the which system converts and is system (Berliner, The transmitter The current external a magnetic microphone to system microphone, receiver, and system receiver. active electrode electrode. The current tissue and produces the (Berliner and Eisenberg, 1985a; Berliner et al., 1985; Berliner, 1985) The electrodes are pure platinum and are used in a monopolar configuration with implanted approximately 6mm the ground electrode in the active electrode into the scala tympani the temporalis muscle and region. The speech processor uses a bandpass filter from 340 to 2700 Hz. to The signal amplitude waveform. from the modulate a The modulator 16k bandpass filter Hz is highly sinusoidal nonlinear is used carrier in terms of stimulation voltage at the electrode of the internal 17 18 receiver in relation to sound pressure level at the microphone <Fretz and Fravel, 1985). 3M/V i enna There are two types of Vienna cochlear protheses: 1) a four-electrode bipolar electrode intra-coch1 ear channels; and implant with a single active use analog an sound implant four an extracoch1 ear electrode. Both systems processing 2) with scheme that has the capability to cover a frequency range from 30 to 10k Hz (Hochmair-Desoyer, 1984). With the extra-coch1 ear device, placed on, biggest not through, the round window. advantages of such a system very little risk of mechanical structures (Hochmair, mu 11i-channe1 in that device various differs rationale frequencies different is that The from frequency The One damage to the 1983). individually. by the electrode the there is inner ear intra-coch1 ear, the 3M/House bands for of is are amplified amplifying amounts stems device different from the fact that high frequency speech signals are relatively weak. Therefore, high amplification to stimulate nerve high adequately frequency frequencies the (Kriewel1, energy require fibers of 1985). is a critical greater the auditory Transmission factor of for speech discrimination as most of the consonant phonemes in the 19 English language consist of high frequency, low energy i nformati on. A microcomputer processor. The input is used signal to to adjust the the stimulator continuous sine wave which varies in frequency increments from 100 to 4k Hz sweep <FSS) is used in patient's feedback to determine for sound constant amplitude and small increment levels equally loud at <Hochmair-Desoyer, <1984) stated that most in small with the frequency During heard a A frequency conjunction processor. be the is CHochmair-Desoyer, Hochmair, Buriank and Stiglbrunner, 1983). stepped speech the response stimulation, in frequency can comfortable 1984). a loudness Hochmair-Desoyer the FSS method has the advantage of being quicker and easier for the patient. NUCLEUS The NUCLEUS mu 11i-e1ectrode/mu1ti-channe 1 utilizes 32 bands of pure which are 10 of stiff support) The active, acoustic current and arranged signal is carrier of 2.5k is platinum which on are a used 25mm converted transmitted electrodes via to a an a carrier. electrical radio Hz to a tuned external <22 of provide silastic into system frequency induction coil. The system utilizes an electromagnetic induction system between the external coil and the internal <Mecklenburg and Brimacombe, 1985a, 1985b). receiver 20 The strategy (Fo), design which first uses allows formant a feature estimates (Fl), extracting of second the the patient (Mecklenburg, results from an estimate of dominant spectral (Mecklenburg, peak is to stimulation at the rate Conversely, a low (Mecklenburg, information of a the led peak and basal is nasality due to by frequency electrode selected will for frequency. stimulate an in the cochlea the addition increased to identify to 280-4k Hz high fundamental Reportedly, to and to be sent the range of frequency frequency 1985b). has and that (F2), represented is more apically placed implant recipient voicing and F2 detected, pitch Electrode selection Therefore, when corresponding electrode which F1 energy within 1985a). energy 1985b). voice formant signal amplitude to determine the signal coding ability of for F1 the the acoustic features of transmission of the low is the pitched F1 component (NUCLEUS Training Manual). One microcomputer of the which variable across the Interface systems allows major stimulating different levels electrodes. provides communication and the speech processor. components There to be A computer the computer is a special erasable between programmable read-only memory chip (EPROM) which allows the speech processor to be "mapped". Mapping Involves identifying the threshold and maximum comfortable level (i.e., dynamic range) for each electrode. This 21 procedure requires approximately three hours to program and all of the electrodes can patient's perceptions change be reprogrammed due to increased as the implant usage and auditory experience (Mecklenburg, 1985a). PATIENT SELECTION-ADULTS General Considerations A. Age: selection, only In the beginning years of those subjects who ranged patient in age from 18 to 65 years were considered as potential candidates (Maddox House and Institute years of Porter, began age 1983)- implanting with NUCLEUS system has just implant approval While, children to there are from the young Food The has the Drug approval received (Mecklenburg, on two mu1ti-channe 1 previously devices Ear as and recently obtained FDA adults other the as 1985). and implant 1980, children approval Administration (Berliner, to In market FDA 1985b). (e.g., Storz and Symbion) which have FDA approval for clinical use, these devices are still under investigation. B. Etiology etiologies cochlear among of adult protheses and meningitis. malformations of factors which hearing loss. single cochlear Other disease, patients who (both systems) include: Menieres Hearing Loss; the cause 1985; Campos, 1985) ear), permanent (Maddox and and a mu1ti-e1ectrode ototoxicity, loss include syndromes (e.g., trauma, profound Porter, common received hearing congenital inner have otosclerosis, causes of various The most and unknown sensorineural 1983; Eisenberg, 23 Information on the etiology of the hearing loss is important for assessing the condition (e.g., ganglion cell population). by Goin, 1985) ganglion concluded cells are discrimination and must the be in Therefore, that certain implantation. implantation is chances greater in used to however, help this assess 3,000 of assessment those cells. speech of the preclude success with pathologies which Promontory population procedure these cochlea. may for neural 10,000 successful region preserve dendrites/ganglion is for etiologies The cochlea approximately approximately apical the Schuknecht (as cited that needed of has testing reserve, questionable success. Some implantation of the are etiologies temporal bone which von malformations (e.g., with as other or severe congenital of membranous labyrinths the bony and syndrome); and in which neurological or physical head acoustic neuromas disease); syndromes retinitis in Recklinghausen's Mondini's processes preclude fractures resulting extensive cochlear damage; bilateral (e.g., may pigmentosa trauma, with certain deafness is disease present disabilities such associated cerebrovascular blindness, accident and degenerative neurological disorders (Maddox and Porter, 1983). unfeasible These or etiologies make the could make rehabilitation implantation process too 24 complex and lengthy. Promontory testing, X-Rays and CT scans may be used to of the seali tympani (e.g., internal C. the and inability to performance and Patients or amplification inner ear structures Patients need to demonstrate receive cues. questionable assess the patency auditory meatus, transtympanic recess). Hearing Acui tv: auditory other polytome limited often with utilize initially receive who benefits demonstrate such effectively from conventional substantial devices after gains a in period of training (Fourcin, Rosen, Moore, Douek, Clarke, Dodson, and Bannister, where 1979). conventional assistance. aid whether these 1976). there amplification will be gives cases little In such cases, the problem of selection of hearing responses However, versus with cochlear patients implant show conventional centers minimal but amplification around definite (Brackmann, The selection of the best device would then be focused on amplification whether are at responses or lower with than conventional those found with implant patients. The use of residual hearing as the main selection criteria may be complicated in cases where benefit from conventional no benefit amplification by is received by the opposite ear. Porter (1983) stated there cochlear is received implant was used have been cases successfully in one ear and Maddox and in which a conjunction 25 with conventional that the ability additional implant to benefits However, they pre-operative1y will be gained stated predict by the what cochlear is difficult, if even possible. D. the amplification. Congenital House Ear Versus Acquired Hearing Loss; Institute (single NUCLEUS (mu1ti-e1ectrode) congenital and acquired have electrode) reported hearing Both and success losses the with (Mecklenburg, 1985a; Berliner, 1985; Eisenberg, Berliner, Theilemeir, Kirk and Tiber, However, a 1983; higher Eisenberg incidence and of House, 1982). failures (i.e., nonusers) exists among patients with congenital losses (Ber1i ner, 1985). Maddox and Porter (1983) post-implant patients who do not not more perform audiological testing, subjectively be poorly on use that their their use of Therefore, patients with an recognize would and it ability auditory assumed with utilize congenital losses auditory experiences have been severely The seemingly predicted persons success with that acoustic important or congenital of losses an their those likely to cues than whose past limited. variables which failure to cues may acquired loss would be more effectively patients has been do objective inferior to patients who successfully utilize implants. those Implant pre-operative however, make meaningful stated indicate implant include: among age of 26 identification; previous experience with amplification; and type of communication used (i.e., oral communication versus manual). versus total Patients with a congenital hearing loss who were identified at an early age, exposed to in an oral or total communication program have been shown to have a higher (Maddox alone and do auditory success Porter, not stimuli, rate with 1983). guarantee and a cochlear However, success trained or prothesis these failure criteria with an imp 1 ant. E. factors Additional may make Several post-imp 1 antation exceedingly complex. solely on manual Factors: additional rehabilitation Patients who are nonoral and rely communication, those who exhibit poor language skills and/or minimal or unintelligible speech skills, likely and to Children involve those be patients additional in geographical cases, have considered and considered such who mu 11 i-handi caps for with the patient cochlear congenital rehabilitation selection. implant. losses needs that less would must Financial considerations must also be assessed. the responsibility rehabilitation staff of each be and In institute's is to determine whether the staff are adequately prepared and trained to deal additional are with these factors (Maddox and Porter, 1983). 27 Medical Assessment A major factor surgeon's beliefs the implantation and rehabilitation in patient patient the patient program selection is the is a good candidate will with reliably full for complete cooperation. a The physician's pre-operative assessment typically includes the following (Goin, 1985): A. Routine Physical Examination B. Transtympanic e1ectrophonic stimulation of the cochlea (i.e., promontory testing) in attempt to demonstrate intact neural function (i.e., ganglion cell population) within the cochlea and along the nerve VIII pathway (House and Edgerton, 1982). C. Polytome x-rays of the inner ear to determine if fibrosis or calcification of the cochlea is present (utilized to evaluate the patency of the coch1ea)D. Evaluation of the middle ear effusion, recurrent otitis round-window obliteration. to rule media, E. Cranioaxia 1 tomography (CT) scan evaluate status of the cochlea and structures. Although promontory standardized estimate electrical nerve critical system. in stimulation survival Mathews and Walder, is testing is the Simmons et 1979). does not However, selection of a out and to further surrounding often utilized, test designed exist this to (Simmons, information cochlear al . (1979) stated a that implant it makes little sense to place a complex mu 11i-e1ectrode system in a cochlea with a sparse nerve population expect to obtain better results than that electrode system. and then from a single 28 Post-operative further x-rays of the active electrode assessment involves obtaining inner ear to check the ground and placement and to determine if the with the electrodes are intact. The physician histopathology well as from from is an the also concerned implanted electrode surgical risks. Berliner Eisenberg, (1985b) discussed the potential may occur as the result of system surgical damage as and that implantation. Mastoid surgery may result in infection, meningitis, or facial paralysis. and enter To transverse the cochlea may the middle ear space provide a potential pathway for the spread of otitis media to the inner ear system. Insertion of to trauma may be electrodes into the cochlea also may of the inner associated ear with structures. mechanical lead Osteogenisis damage or the presence of the electrode in the seala tympani. The scala tympani begins to curve at approximately 10mm at which possibly point pierce the resulting in membrane, Reissner's spiral will a lamina. membranes of rupture membrane, result and fluid in electrode the of and/or The rupture of any of perilymphatic could implanted mechanical subsequently perilymphatic the the significantly toxic to the basilar the osseous diffusion the of fluids. hair/nerve increase ear these structures endolymphatic is inner can cells amount the The and of 29 sensorineural degeneration (Otte, Schuknecht, and Kerr, 1978; Burgio, 1985). The possible long term damage be considered particularly The coch1 ear nuclei after birth. at implanting children. are not completely developed until Therefore, the cochlea when to the coch1ea must if too early the prothesis an age, it is placed could affect maturity of the cochlear nuclei CGoin, 1985). auditory deprivation revealed that an maturation and, because post-nata11y, require of the early of lower this cells and auditory in the cochlear takes is place thought in order to Webster, 1977, 1979). auditory system may to develop actually stimulation. implantation of children may have sound can cause nucleus stimulation the However, mammals development cochlear (Webster enhancement with the auditory completely in the early deprivation of incomplete nucleus studies in An occur Thus, the enhance the maturation of the cochlear nucleus. The possibility of mechanical taken into consideration when rupture must also be implanting the NUCLEUS mu1ti-e1ectrode system which extends approximately 22mm into the cochlea. 1985) stated related to deprivation Brand (as cited in Fretz and Fravel, tissue any of damage mechanical blood supply tends not to damage but and tissue be directly rather fluids to the which 30 subsequently results in deprivation of oxygen and nutr i ents. Current studies have found the following histopathologic results from an implanted temporal (implanted with the 3M/House single electrode bone device) (Burgio, 1985): 1) Typical foreign possible infection) body response 2) No significant tissue growth (e.g., edema, in the middle ear 3) Round window well sealed by fibrous tissue thus providing a natural barrier between the middle and inner ear. 4) New bone growth was localized to the round window and lower basal turn at or near the opening made into the seal a tympani for electrode insertion. The new bone was not along the length of the electrode and did not appear to adversely affect the nerve cell populations. 5) The 15mm electrode, which is inserted 6mm into the seal i tympani, caused mechanical damage to cochlear tissues. As the electrode extended past the first turn of the cochlea, the amount of tissue damage increased as a result of damage to the cochlear duct which in turn results in degeneration of nerve fibers. 6) Large nerve cell survival 7) In 100% of the cases studied, insertions were safe to the basilar membrane and approximately 96% of electrode insertions were safe to the osseous spiral lamina (Radcliffe, 1984). Psychological Any cochlear implant Assessment-Adults candidate, both child, must meet the following psychological adult and criteria: "1) no evidence of severe organic brain damage; 2) no evidence of psychosis; 3) no evidence of mental 31 retardation; 4) no behaviora1/persona 1 ity traits that would make completion of the rehabilitation program unlikely; and 5) no unremitting, unrealistic expectations about the implant on the part of the patient or the family" (Tiber, 1985, p-48). An indepth interview is often included to measure motivation levels. Many patients request information on cochlear implants because of pressure placed on them by their significant others (Campos, 1985). Therefore, these concerning the interviews patient's also provide expectations of information the both its benefits and limitations. also must be acceptance of support, and considered his/her regarding Other factors which include deafness, the implant the the commitment amount to patient's of family post-implant rehabi1i tat i on. Adverse psychological long-term stimulation have not yet been and use reported effects of the cochlear (Miller, 1979). (1979) concluded that any psychological occur are Implant generally has often positive. been shown secondary The to implant Miller changes that do use to enhance of a cochlear communication skills, promote confidence in social settings, promote independence provide positive feelings towards of (Miller, 1979; improved and quality Ber1i ner, 1982) life House and 32 Audiological The deaf audiological adult is tests. unable to adequately (Edgerton, Therefore, assessment difficult suprathresho1d patient Assessment-Adu1ts the to for perform These the with protocols assessment and of a conventional are assess the residual Eisenburg, profoundly typically skills of the Thielemeir, patient's 1983). ability to receive and utilize auditory cues should not consist of conventional measurements alone. Qne critical patient will implant or implant clear a audiometric question likely benefit from a hearing cochlear benefits aid. prothesis from more is whether the from a cochlear Most clinics will in patients who amplification. This is not receive based on the belief that frequency discrimination will be better with an implant appropriately due generated by naturally to the hearing aid unnatural the electrical occuring Mecklenburg, 1985a; Berliner, 1985; audiologist must sensory fit action method current a cochlear of stimulation versus that by the potentials Mecklenburg and than (Luetje, 1981; Brimacombe, 1985b; Hochmair-Desoyer, also aid (e.g., decide whether vibrotactile 1985). another with established for on an implant. cochlear environmental Some implant sound type device) would the added cues and increase performance equal obtained The norms of provide to those have been patient's performance tests and the, 33 Monosyllable-Trochee-Spondee a l ., 1983). Clinicians information to performance with are compare the Implant patients. (MTS) test (Edgerton encouraged the to patient's range obtained use best from et this aided cochlear In general, patients wearing hearing aids who perform at or above the average for cochlear implant users may not be considered good candidates for an any implant. Such further patients may benefits Conversely, patients poorly be can be from a to receive cochlear performing considered unlikely marginally potential implant. or candidates more for cochlear implantation. Audiometric Evaluation Audiometric assessment for adults usually includes the following measures (Edgerton et a l ., 1 9 8 3 ; Luetje, 1981; Mecklenburg, 1985a): UNAIDED EARPHONE A. Pure-tone thresholds B. Pure-tone uncomfortable loudness levels (UCL) C. Speech detection threshold D. Most comfortable level for speech E. Monosyllable-Trochee-Spondee test (MTS) F. Environmental Sounds test G. Test for CHABA-Everyday speechreadi ng speech ability sentences Hirsh, 1955; Sims, 1975) such as (Silverman the and 34 AIDED SOUNDFIELD A. Warbled tone thresholds B. Speech detection thresholds C. Environmental sounds test D. Minimal Auditory Capabilities battery (MAC) The criteria utilized by when assessing aided performance obtaining an earmold prior that maximum benefit the House Ear from Institute includes: to the evaluation the aid may 1) to ensure be obtained; 2) output of the hearing aid is set at 130 dB SPL or less; 3) at least two sensory aids are evaluated (including a vibro-tacti1e aid); and 4) speech and environmental sound stimuli are presented at 70 dB SPL (Eisenberg and Berliner, 1983; Berliner, 1985). The provides Mononsy11ab1e-Trochee-Spondee data on two discrimination and a forced-choice The word format Environmental five-alternative 1983). levels of (MTS) perception: test stress identification while utilizing (Erber Sounds forced-choice and Allencewicz, test test is a 1976). 20-item (Edgerton et al ., Patients are required to circle the sound they hear from the five answer choices on a response sheet. The Minimal Auditory Capabilities (MAC) battery was designed by Owens, Kessler, and Schubert (1982) and is used to obtain interim audiometric indices on the relative benefits of cochlear implants and hearing aids for patients with profound postlingual sensorineural 35 hearing losses. The MAC battery consists auditory tests and one 1ipreading test. are designed prosodic to test features, environmental sounds, the patient's phonemes, sentence 13 These subtests ability noise of to versus recognition, hear voice, and one- and two-syllable word recognition. Usually, implantation the because worse if ear the will be implant selected were to for be unsuccessful, the patient would have his/her better ear left unharmed. If there is not an ear difference, the patient's prefered ear is selected. no preference, a decision and the patient. If the patient has is reached by the physician REHABILITATION-ADULTS Rehabilitation typically after surgery surgical to allow wound. The involve the fitting speech processor) (Mecklenburg, Adjusting the level each for and procedure always amplification the may of take the (i.e., stimulation to several the current discomfort an weeks as the likely to to change The setting flow) 1984). appropriate prothesis. includes (i.e., patient's initial stimulator the rehabilitation equipment preferences are usage of Hochmair-Desoyer , external patient external the two months healing phases of the 1985b; increased complete initial of patient's perceptual with for begins about fitting of some guarantee threshold level that is not exceeded (Hochmair-Desoyer, 1984). The fitting of quite complex. be "mapped" comfortable each The which continued use processor can NUCLEUS mu1ti-channe1 includes loudness electrode. a mu1ti-channe1 finding levels (i.e., This and thus, range tends system must thresholds dynamic to new "maps" have be and range) for increase with to be made as the rehabilitation progresses. The cochlear implant produces electrical signals which the patient may perceive as a crackling, humming, or buzzing noise. the parameters of This signal may have only a few of the sound 36 stimulus the patient may 37 recall only as being characteristic hold true (Campos, for of speech. post 1ingua11y 1981,1985; Maddox and This would deafened adults. Porter, 1983). Therefore, the therapy program must provide the patient with strategies to re-learn how to make meaningful of acoustic stimuli. The patient with an need to be reminded of the impact of use implant will long-term hearing loss as well as the probability of needing to reprogram the auditory processing system, if this is indeed possible (Campos,1985). Most minimum clinics require of 30-40 hours (Mecklenburg, 1985a; 1985). amount The needed for need each instrumentation effective use of of and a and therapy the basic minimal language speechreading postoperative is variableuse 1984; Berliner, rehabilitation Some may of the introduction auditory require extensive therapy training, attend a post-surgical regarding of patients to Hochmair-Desoyer, patient instructions their cues. simply external to Others the may in auditory training, speech therapy, voice environmental monitoring, manipulation (Maddox and Porter, 1983). The philosophies underlying therapy institution cochlear programs, providing implant a the patients. controversy should be implemented. aural As exists vary for each rehabilitation with as many to for therapeutic which method The issues of unisensory versus 38 mu1tisensory; (synthetic) centered top-down approaches; programs; approaches (analytic) must home and be centered unstructured resolved therapeutic approach versus versus versus (Eisenberg, utilized must bottom-up clinic structured 1985). Any recognize the major levels of auditory processing and work toward obtaining skills at each These levels sound, level (Eisenberg, 1985; NUCLEUS manual). include: attention, (same-different); l) detection arousal); 3) 2) (presence of discrimination identification or recognition (repeating, imitating); and 4) comprehension (Erber and Allencwicz, 1982). At the detection most of awareness sound. of both level, After sound, discrimination using basic and training may the patient activities identification linguistic and can focus on demonstrates focusing be on introduced non1inguistic stimuli (Eisenberg, 1985). The initial stimulation training in critical techniques, barriers. and The speechreading in is followed by listening tasks, voice monitoring reduction latter a of is number known performed of different situations, varying from the optimal patient is encouraged to barriers in ways that will to be achieved intensive (Campos, deal communication by practicing communication to the poor. with The communication allow maximum communication 1981). Critical listening 39 tasks for speech suprasegmental cues aspects differentiation progresses to sentences medial in of usually begins the final hierarchy speech. polysyllabic which and involve a with words, stress positions of the many Varied syllable word stimuli phrases varies in (Campos, and and short the initial, 1981; NUCLEUS training manual). A wide patients' variation ability to auditory sensations. able to integrate this information patients may information in a factors which may Some unable this neural understand to integrate and and manner. Other use The age, reserve) been be utilize this various individual's ability (e.g., population stimulated speech. stimulation have paper implant recipients may stimulation influence an earlier cochlear electrically meaningful electrical onset, among implant better make use of in use electrical to be exists to discussed etiology, age of (Hochmair-Desoyer, et.al., 1983). The mu1ti-channe1 single channel sensations system rehabilitation implants will systems available (Mecklenburg, device, each due for program differ to those 1985b). electrode is to balance the the for that for wider incoming used variety of with a mu1ti-channe1 With a mu1ti-channe1 potentially producing different sensations. need from designed capable Therefore, there signal so that of is a the 40 perceived sound transmission is of pleasant the most and the information successful is obtained (NUCLEUS training manual). The goal develop for mu1ti-channe1 two abilities: information; and 2) recognition for information derived training NUCLEUS device formant. the from The two the new of of prosodic pitch speech, is to pattern which requires second formant (NUCLEUS coding strategy information categories are on of the the first divided into levels of performance which require different training activities. may perception also provides These different 1) the perception understanding manual). implant patients utilize features For example, the easier materials of stressing speech information, such using as word the simpler fundamental length male/female speaker discrimination. sessions prosodic frequency differences and The more difficult tasks may include question/statement discrimination. Those materials which use visual (i.e., speechreading) cues are also arranged from easy to most difficult. (e.g., They everyday may include: situations), familiar contextual sentences categories of phrases and words (e.g., farming, school, etc.), voiced versus numbers non-voiced of (CVs words in rehabilitation program format: length word and words), sentences. uses the and segmenting The NUCLEUS following training discrimination; sentence length 41 differences; male/female noise and speaker voice discrimination; identification; vowel closed-set sentences; closed-set words; ( s t r e s s manner accented words i d e n t i f i c a t i o n ) ; (question/statement); vowel discrimination; consonant voicing i n t o n a t i o n identification; clue length; sentence discrimination; consonant identification; consonant place discrimination; open-set sentence recognition; open-set word recognition; speech tracking; telephone identification of simple words/phrases with a speaker; and telephone use with familiar an unfamiliar speaker (NUCLEUS training manual). Most rehabilitation developed by clinics utilize success (Berliner, 1985; method the with involves an tracking open-set speech 1985a; reading of minutes session and their correctly compared of scores intense are identified per minute. for stimulation speechreading and and This appropriately The patient must repeat each sentence or phrase verbatim. ten a materials 1985). an selected story, sentence by sentence. allowed procedure Mecklenburg Hochmair-Desoyer, oral implant Scott (1978) to evaluate Mecklenburg, 1985b; cochlear speech DeFi1ippo and patient's Brimacombe, offering Patients are speechreading recorded as per words The results are then alone, speechreading, and electrical electrical 42 stimulation alone (DeFilippo and Scott, 1978; Berliner, 1985; Mecklenburg, 1985a). DeFi1ippo and Scott's (1978) goal tracking procedure situational is to conversational speechreading procedures procedure differs from procedures in it opposed to procedure develope that where relevant The tracking speechreading connected of speech sentences. a measure of to conventional conventional lists provides skills failed. utilizes unrelated also use for the speech correct as This message reception as opposed to a two choice method. The developers speculated that "tracking with ongoing speech would require a wider range of perceptual and linguistic skills that can be applied, more or less efficiently, dependent on the display characteristics of the aid being used (p. 1186)." After basic rehabilitation goals have been met, open-set speech discrimination and training on the use of the telephone may begin. The more successful implant patient may learn to recognize and discriminate between a dial-tone, a busy signal, and ringing as well as be able speaker on variety of to carry the other effective on a limited end could be common conversation. taught strategies The to utilize such as a the syllabic responses of "no", and "yes-yes" (Mecklenburg, 1985b; NUCLEUS training manual). The environmental training sounds is for critical carried out listening mainly in for the 43 patient's home. to The patient increase an is given home assignments awareness of surrounding sounds and become familiar with the implant system range of operation for a personal and its in terms of to its limitations. This allows insight into the potential problems with the prothesis and allows the patient to monitor his/her own progress with sound detection and recognition. Each patient all their is requested to keep a daily diary of auditory experiences including the number of hours the day and the novel auditory with therapy is sensations terminated, assignments provided in patients usually the experienced. in-clinic therapy, staff determines whether warranted. When are in-clinic given consisting clinical implant implant was used per Following the initial 30-40 hours of the rehabilitation the a of setting. additional therapy series training The of is home materials patient is encouraged to maintain contact with the rehabilitation staff their progress via monthly reports in order that can be monitored and any medical which may asked to arise return can be to the following the initial progress Brimacombe, 1985a) corrected. institution Most every problems patients are 6-12 months rehabilitation for re-evaluation, evaluations, (Ber1iner,1985; or equipment and equipment Campos,1981; adjustments. Mecklenburg and 44 Patient Reactions Adult cochlear implant timing and intensity not significantly normal users may learn to utilize discrimination abilities that different from the abilities hearing subjects (Helmerich and Edgerton, Bilger, 1977; Wallenberg et al., 1985). most post lingual signal's deaf amplitude predictor of implantation and their and electrode frequency pitch Bilger speech information. single Dent electrode to this first formant the reduced limit information limited frequency information may place of position He or to frequency high that information fundamental only. single of energy frequency of a ability the the after pitch lack as key Edgerton that to decreases secondary to the transmission and due <1982) supported devices the and reduces Furthermore, secondary frequencies. stated the Buriank, and Helmerich perhaps frequencies is Hochmair, significantly 1982; discriminate features have of The ability of understanding However, perception, increases, temporal <1977) device discriminate to <Hochmair-Desoyer, Stiglbrunner,1983). <1982) adults are frequency stated that allow for some basic differentiations of speech prosody and manner of articulation but restricts a person's ability for the differentiation of the place of articulation. Although cochlear implant users possess intensity discrimination abilities, most implant patients exhibit 45 an extremely limited electrical (Pfingst, 1984). 25 dB below less at 1984). The dynamic range 250 Hz higher intensity dynamic range and can be as is often little frequencies (Michelson, less than as 1971; 10 dB or Pfingst, Therefore, the patient may be unable to tolerat stimulation i nformati on. at levels needed to transmit the desired PATIENT SELECTION-CHILDREN The House Ear in 1980 as House, an experimental 1982). electrode States Institute began to implant To cochlear Food Drug the ear, causes are children who maternal some of have by rubella, United (FDA) Bacterial and single the younger than 1985). toxemia, just 3M/House is approved device for children ototoxicity, inner the (Eisenberg Administration of age (Berliner et.al., trauma, only implant and experimental date program children as 10 years meningitis, deformities cytomegalovirus, and the deafness been etologies of selected an for of unknown in implantation (Luxford and House, 1985). The child's primary consideration potential for when implantation assessing is the the valid confirmation of audiometric results which demonstrate a profound sensorineural particularly responses true are for hearing loss. young children often whose inconsistent and This is behavioral inaccurate. Auditory brainstem evoked potentials are often utilized with these children to confirm the presence of a profound loss (Berliner, 1985). The assessment gained of from second major children is conventional unaided audiometric consideration how much actual amplification. results 46 are not always during benefit Aided the is and predictive 47 of the aspect success is or failure difficult limitations of the to with assess hearing because protocols, aids. of cognitive This age-related factors, and l a c k o f e x p e r i e n c e w i t h s o u n d ( E d g e r t o n e t a l ., 1 9 8 3 ) . Berliner and following selection be at least criteria (1985b) for Test children. hearing of loss. Auditory implantation average test cochlear of an They the must The aided performance Comprehension Discrimination After Training test for provided two-years of age with a profound bilateral sensorineural the Eisenberg must results implant. If amplification poorer obtained in the ear than from The child must appropriate training. be no hearing-aid progress (i.e., no is or children also have seen awareness to to the using a a history and with the selected equal trial speech development), a cochlear and on auditory conventional sound and implant should then no be considered (Edgerton et.al., 1983). The (Trammel 1, of Test 1985b). developed Auditory 1976) evaluates environmental hierarchy of of sounds and difficulty specifically the for House auditory speech (Berliner The Discrimination by the Comprehension comprehension in a and Institute, to assess the Eisenberg, profoundly was designed deaf children and adults (Berliner and Eisenberg, 1985b). used sequenced After Training (DAT) test, Ear prellngual (TAC) subject's ability The DAT is to utilize 48 auditory cues to make discriminations of speech or some of the nonsegmental aspects of speech. test materials are incorporated as part of the test an attempt to control, or at past auditory The training of experience in least minimize, the effect may play on test results (Thielemeir, Tonodawa, Peterson, and Eisenberg, 1985). Medical Typically, the Assessment same assessment protocol used for adults is also used for children (e.g., polytomes etc. to observe turn of the status the cochlea of the round in search of window and congenital basal anamolies of the inner ear or labyrinthine ossification). Psychological A. Assessment Interviews: A to obtain (Tiber, 1985; Selmi, 1985) variety of information developmental regarding history, method and emotional adjustments, potential also provide used problem by of the what is history, social expectations, These regarding given child's family, parental areas. information understanding the educational communication and interviews are interviews the involved parents' and the potential benefits and limitations of the cochlear implant. Child Implant Specific Behavior tools Rating Questionaire. utilized Scale A and pattern of include the the Cochlear parent-child 49 interaction must emerge which indicates the family will be able to effectively follow through with the post-implant rehabilitation program. B. Intel 1iaence Tests: 1.Stanford-Binet Forms L-M-for children 2-4 years 2.Wechsler Pre-School and Primary Scale of Intel 1iaence-for children 4-6 1/2 years 3.Wechsler Intelligence Scale for ChildrenRev ised-for children 6 1/2-16 1/2 years 4.Wechsler Adult Intelligence Scale-Revisedfor children 16 1/2-18 years C. Neuropsychological Tests: 1.Hal stead-Rei tan Test of Lateral 2.Bender-Gesta1t 3.Wide-Range Achievement Test Dominance Audiologic Assessment The following audiometric results should be obtained when possible (Berliner and Eisenburg, 1985b): A. Tympanometry and otoscopy (rule out middle ear pathology) B. Acoustic reflex at 500, lk, and 2k Hz measured with a maximum stimulation output of 110 dB SPL C. Warbled tone thresholds 250-4000 Hz D. Speech detection thresholds E. Speech uncomfortable loudness levels F. Brainstem appropriate under) Evoked (used for Responses all children (BSER) 6 years when and 50 Warbled tone thresholds and uncomfortable loudness levels (UCL) are obtained of the appropriate to select hearing soundfield evaluation. the gain aids used and SSPL during The SSPL of the hearing aid the is not to exceed 132 dB SPL. Soundfield testing includes: A. Warbled tone thresholds B. Speech detection thresholds C. Speech UCL's D. Speech discrimination: performed with best aided the hearing warble-tone These aid that tests provided thresholds, with each are the ear being tested separately. 1. Discrimination After Training (DAT) 2. Test of Auditory Comprehension (TAC) Finally, provided to speech evaluate and the language child's assessment receptive is language, expressive language, and phonology/articulation. Post-implant Results Most 3M/House children who implant system have had been no implanted measurable 250, 500, lk, 2k, 3k, and 4k Hz. Once these SPL frequencies ranged tested from (Berliner hearing the at The aided soundfield thresholds rarely exceeded 80 dB SPL. thresholds with 59-64 and dB implanted, across Eisenberg, the 1985a; 51 1985b). The goal to obtain for setting the gain of the implant warble-tone thresholds 45-60 dB HL across the frequency (Thielemeir et al., 1985; on the range average of Eisenberg is of 250-4000 Hz and Berliner, 1983). Additional implant in following benefits derived children have been (Berliner, 1985; from reported Tiber, a to cochlear include the 1985; Kirk and Hi 11-Brown, 1985): A. Simple auditory discrimination B. Detection of environmental sounds C. Increased speech production skills 1.increased vocalization 2.improved voice quality (i.e., monitoring of intensity and pitch, and decreased vocal strain) 3.improved speech rhythm (e.g., speech rate, stress, syllabification) 4.improved imitative and spontaneous production of vowels and simple consonants Based on follow-up. a six the month, post-implant data have psychological effects Tiber found (1985) implanted a children's short-attention spans. not indicated (Tiber, 1985). significant level psychological of These any adverse Behaviora11y, reduction in the distractabi1ity and children are also 52 reported on to have certain demonstrated an psychological and WISC-R). However, tests improved (i.e., maturation may performance Bender-Gesta1t have influenced these improved scores. The House Ear Institute have reported that of 205 children implanted, only Eight of these refuse to utilize and/or peer 10 are the 10 do not use the device. teenagers and device pressure the due to (Berliner, they reportedly cosmetic 1985). reasons Table 1 presents a summary of data from the House Ear Institute as of September 3M/House at single the 15, 1985 electrode Denver Ear regarding cochlear children implant Institute's with the (Presented Cochlear Implant Symposium, Denver, Colorado, 1985). TABLE 1: Cochlear Implantation of Children AGE AT TIME OF SURGERY 2-5 YEARS USERS NONUSERS DEVELOPMENTAL FAILURE NONSTIMULABLE IN PROCESS DECEASED (unrelated to the implant) 6-12 YEARS 13-17 YEARS 63 2 83 0 29 8 1 0 3 0 2 1 8 1 2 1 1 0 Summary In proven auditory summary, to be the effective thresholds can 3M/House for be cochlear some implant children, obtained at in levels has that which 53 allow profoundly deaf children to detect speech and environmental sounds as well as to make simple auditory discriminations (Thielemeir et al., 1985). At minimum, profoundly deaf information speech implant as well (Kirk of as the limited speech pitch Hill-Brown, of voice perform timing allow at a auditory patterns and in intensity information 1985). age by a of the Thielemeir auditory performance time and that two-years may This may be due to the provision al., (1985) reported that after implant detect and different regarding and to improve over to level structured situation. of cochlear children conversational discriminations the et appears children who become deaf and utilized an oral communication method tended to also perform better than average with Hi 11-Brown the cochlear (1985) found implant. improved However, speech and production skills in children who were trained in both an a total communication program. Kirk oral or REHABILITATIQN-CHILDREN The initial with children considered phases of focus to be on an the rehabilitation parent counseling integral part of program which the is program. Decisions also must be made regarding internal settings of the implant threshold and patients. signal comfort A on The important ability speech to level, rehabilitation dependent most processor not be is While achieved, language child may also pragmatic variety skills of enable cochlear errors (Howarth of listener and that may deaf in Smith his/her 1985). A training the improve speech 1965; may sounds and the the and, to compensate John, implant Hill-Brown, shown child's intelligible improvement speech patterns the an and have aspects of intonation might (Kirk studies nonsegmental and demonstrate is ability. the obtaining enable the child to detect environmental adult children improve the electrical with for and to on done program is communicate. may as the child's speech goal based foe 1975; stress in turn, segmental Osberger and Levitt, 1979). Following hours), House basic therapy the child returns therapeutic contact the settings. with Ear Institute to his regular The teachers, period (i.e., implant parents, has 54 and initiated academic and staff maintain therapists. a 30-40 School The Contact 55 Program in personnel (1985) order to maintain in the schools of described program: the 1) to provide regarding benefits limitations; personnel in educational available materials school cochlear 3) 2) to that auditory skills in the objectives information with assist to will this school including the realistic provide Selmi of implants to establishing goals; contact implanted children. following professionals and regular school long-term information maximize development on of implanted child as well as guide professionals in choosing and evaluating auditory objectives; and 4) to develop a system whereby the House schools Ear on a Institute regular receives basis information (e.g., from summaries of the the child's progress, child's responses to classroom sounds etc.>. Summary Initial implanted auditory children skills (Selmi, 1985). the ages 13-18 in the results Hill-Brown, are over able time in Currently, only years have production segmental from skills 1985). of program indicate to increase certain a classroom setting those children demonstrated any several following This this is decrements non-segmenta1 implantation probably between and/or (Kirk related reported unwillingness of some of the patients to and the in this 56 age group to fully utilize their devices due to cosmetic reasons and peer pressure. Although early the number Because of most research results seem encouraging, subjects of the actually implanted assessment tools is small. utilized are age-dependent, gathering long-term data is difficult as the implantation concept. already Additional implanted limitations fully of of and is experience is required cochlear defined Professionals children with before implants (Kirk others a and in relatively those the children benefits children can Hill-Brown, working new with and be 1985). implanted children must also consider the fact that cognitive and speech/1anguage skills develop drastically change over time and will in short-time periods as will not other measures (e.g., audiological) regardless of whether the prothesis is on or off. One of the most difficult decisions audiologists are going to face is a recommendation for or against cochlear implant (Campos, 1985; Mecklenburg, a 1985a; Dankowske, 1985). More than a dozen centers through-out the world have involving systems the via developed set of extent electrical cochlear to varied which in implants. for developing variability in the reasons success of for goals. or The have been procedures there is rehabilitation success has and its own data rehabilitation Therefore, auditory center these scientific programs of Each achieving available considerably. the stimulation its own goals for rehabilitation strategies utilized and initiated independent clinical failure has large programs are poorly understood (Pfingst, 1984). There seem to implantation than the inquiries relatives of fewer one might about deaf surprising number never used be of candidates suspect. cochlear implants individuals these who do achieve from some are of in to A have limited Another group dissatisfied hearing degree by 1985). tried one them. 1/2 of made individuals appear ways and consequently rejected inquiries are cochlear least (Campos, a hearing aid or have the At for benefit. aid Many of users deaf individuals living in the deaf community express little interest in cochlear implantation. 57 They also have the 58 right to determine whether or not they wish to become part of the "hearing" world. Unfortunately, the medical, hospital, and product costs are sources. some not always The medical mu1ti-channe1 underwritten and units by various hospitalization may be funding costs underwritten for by a research grant, however, these may involve no more than two volunteers insurance companies experimental expense and as the California position Approval the are cochlear the the barrier to surgical FDA more reimbursement have treatment of adults procedure implants to insurance insurance for both in 1985). remove the coverage of in coverage cochlear may (Staller, 1985; Campos, insurance the acceptable deafness involved be formal (Simmons, helped to and the an are medical appears taken are also Many Association implants complete include rehabilitation many that stance Medical has however, 1985). a reimbursable This deafened from However, not Association for implantation, maintain 1985). Medical post 1ingual1y (Simmons, still American that procedure year thus (Staller, changing major per not 1985). companies are now providing the surgical and rehabilitation costs. There rehabilitation total exists for communication a controversy deaf children versus manual over any type of (i.e., oral versus versus acoupedics). 59 This controversy extends implantation in children. to the issue of benefit an implant Children need ample time to experiment with hearing aids before determining that no cochlear Specific problems arise when trying to assess the success or failure with children. of from conventional they receive amplification. This more difficult to determine for children than it adults. to changes versus directly changes due related to to the cochlear maturation. In cases, each child serves as his/her own control the is for Another problem may be encountered when trying document implant is lack of development normative of data implanted (Berliner and Eisenberg, compare the on profoundly 1985b). performance the of most due to communication deaf children Researchers may also implanted children to profoundly deaf children without an implant who are the same age (Eisenberg et al., 1983). Good cochlear are living in implant candidates are persons who the hearing world motivation to continue to do so. critical factor satisfactorily living in a in adjusted Those their deaf community will have media attention over the past professionals who years. Cochlear However, criticize the and a have are typically not be good al., 1985). increasing strong who deafness candidates (Berliner et gained have This seems to be success. to and and there influx of implants popularity are also cochlear 60 implantation. Despite these criticisms, of the cochlear to stay The implant (Berliner implant has et a l ., 1985; introduced treatment of approach involves profound professionals who potential believe that a Mecklenburg, concept sensorineural must benefits implants are here unique teamwork work for the investigators 1985b). into deafness. the This between a variety of together to maximize the implant patient (Campos, clinical programs 1985). Most of the centers with cochlear system of to the evaluate of devices (Bilger, provide the running speech goal stimulation has deaf been have patients the major initiated psychophysical laboratories evaluations One of have the electrical additional these implants involved in patient without achieved at conducted 1977; least with a the a ability to most of the patients understanding has been poor implanted In fact, extent even under circumstances (BuriOn, 1981; 1981; 1983). Clark et al., advancements and research implantation becomes a to in common a few However, date, speech structured and Schindler, Further needed this very Michelson are is to understand patients under certain restricted conditions. in of 1984). implantation limited two variety Hochmair-Desoyer, cochlear of psychophysical speechreading. to sort characteristics and implanted goals of some technological before treatment of cochlear profound 61 sensorineural are deafness. Such presently being conducted implantation may become professions, particularly Mecklenburg, 1985a; an prepared refer to them to evaluations, services. cochlear potential appropriate be able to it implantation alternative promote likely a perform provide the will frequency which necessary rehabilitative qualifications as candidates, the become of cochlear current trend transpire. summary, the implant sources, is is this a author's great hearing health care profession. meet many Therefore, audiologists must increases, indicates will In audiology of 1985a; necessary implantation part Mecklenburg and Brimacombe, These increasingly integral cochlear 1985; identify and and (Campos, Hochmair-Desoyer, 1985). be advancements and research candidacy treatment positive probability that have, their mental achievement that in the Those who are deaf and criteria for opinion at handicap. health auditory by last, an This helps providing experience the will once again be a part of these persons' lives. To date, the reports from have been optimistic. of success the and/or new auditory the recipients Implant recipients vary in terms failure. Some will perceptions and utilize their device. implant may never rarely, adjust if to ever, On the other extreme, there are recipients wearing their devices most of the time and comprehending open that the obtained do with the not implant than most truly of implants. part, objective implant keep open represent recipients most improved quality of day One must measures cochlear from performance For speech. objective discrimination reports set set subjective indicate far measures hearing in report a much feel more a less part be measured lsloated of much in every The fact seems to be that general, world, better demonstrate. life, qualities that cannot adequately recipients, benefits life based on performance by objective tests. mind speech the The patients in implant from their the everyday env i ronment. As research population of successfully implant development deaf with patient candidacy and individuals cochlear may criteria advances, of not may be implants. have present. to a wider treated The meet future the rigid Prelingually deafened adults have been implanted with single channel devices. Paralinguals, those who have acquired language but have been deaf a implanted. of the majority The FDA NUCLEUS of their has now approved mu 11i-e1ectrode 10-18 years of age- lives, the device have been implantation for children The list should continue to expand with time and experience in the field. The critical. audio1ogist's Without proper role in this rehabilitation, process the is patient 63 may never as, to learn to utilize the device to date, hearing no to implant a system normal is level . rehabilitation required per patient its potential able to The amount varies. restore of Some will require minimal training including simply adjusting and fitting more of external intensive equipment. therapy the suprasegmenta1 Others including the and segmental will require training of both components of speech. The program for rehabilitation differs with each device currently on the market. However. establish a common goal: the patient speech than at a higher level that most shall which programs understand is obtained with hearing aids. The audiologist should maintain knowledge area as more on cochlear closer to anxious patients may implants. the about hearing this Accurate, realistic potential candidates impaired population to all As audio1ogists. seek a world, new advice and last many help information of clients treatment information and hope will serve in this for help returning will be deafness. identify the to a greater degree, a goal hearing common APPENDIX A Sirrmary of the 8 Most Ccxmion Types of Inplant Hardware (Staller 1985; ASHA, 1986) 1 I TYPE O j SYSTEM i NUCLEUS Digital i Feature : Extract COOING STRATEGY Dt.> I in 3M/House 3M/Vienna BIOSTEM STORZ SYMBION Hurtmarr. Analog Filter Bank Analog Filter Bank Analog Digital Filter Analog Filter Bank Analog Filter Bank Analog Filter Bank Digital Feature Extract Monopolar Monopolar Bipol ar Monopolar Monopolar Monopolar STIMULATION REGIME Bipul ar Monopolar NUMBER OF CHANNELS 22 1 1 1 4 4 1 12 ACTIVE ELECTRODES 21 1 1 1 4 4 8 12 IntraCochlear ExtraCochlear IntraCochlear IntraCochlear IntraCochlear ixtraCochlear IntraCochlear Grm 3nni 24nm 22iT5TI Qiffi $6,000$9,500 $4,500 $12,000 $11,000 | . . . SITE OF STIMULATION IntraCocnl ear ! ELECTRODE DEPTH I j 2'jfim ij APPROXIMATE COST ! | $11,000 j 6MTI i1 Ii i | fj-jin 1 i $6,500 -uO,' $9,000 ; REFERENCES ASHA (1986) "Report of the Ad Hoc Committee on Cochlear Implants". ASHA. April, 29-52. Alpiner, J.G., (1978) Handbook of Adult Rehabilitative Audi o 1 oav. (2nd Ed.) Baltimore, MD: William and Wi 1 kens. Berliner, K.I., (1985) "House Ear Institute Pediatric Cochlear Program". 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