Factors affecting outcomes in children with cochlear implants

Transcription

1 Factrs affecting utcmes in children with cchlear implants XVI Wrld Otrhinlarynglgy Sydney I Australia R.c. DOWELL, P.J. BLAMEY and G.M. CLARK Department fotlarynglgy, The University fmelburne (A US) SUMMARY ~Open-set speech perceptin tests were cmpleted fr a grup f 52 children and adlescents wh were lng-term users f the Nucleus multiple channel cchlear prsthesis. Results shwed mean scres fr the grup f 32.4% fr pen-set BKE sentences and 48.1% fr phnemes in pen-set mnsyllabic wrds. Over % f the grllp perfrmed significantly n these tas1cs. Age at implantatin was identified as a significant factr affecting speech perceptin perfrmance with imprved scres fr children implanted early. This factr was evident in the results at least dwn t the age f thrce years. Duratin.. f prfund hearing lss, prgressive hearing lss, educatinal prgram and preperative residual hearing were als identified as significant factrs that may affect speech perceptin perfrmance INTRODUCTION Multiple channel cchlear prstheses were first implanted in children in Melburne in 1985 (Clark, 1995). Since that time, ver 7000 Nucleus multiple channel cchlear prstheses have been implanted in children thrughut the wrld. In mre recent years, a larger prprtin fyung children have been implanted at mst centres. This trend is due, in part, t the belief that yunger children will have the best chance f develping speech perceptin and speech prductin skills thrugh use f the cchlear implanl There are many arguments supprting this assumptin including ur knwledge f language develpment, physilgical studies f the 'effects f sensry deprivatin n animals, and the effect f age f hearing aid fitting n utcmes fr hearing impaired children. It is certainly f interest, hwever, t establish whether the utcmes fr children with cchlear prstheses are indced enhanced by yunger implantatin, It wuld als be useful t knw exactly hw age f implantatin and ther factrs affect the develpment fspecch perceptin, specch prductin and auditry language. At the Cpyright 1997 by Mnduzzi Editre S.p.A. Blgna (Italy) 297 I

2 XVI W~d f Neck Surge!)" 2-7 March 1997 Univelliity f Melburne, a prgram f regular assessment f spxh perceptin skjlls in implanted children ver the lng term has prvided a large data set which can be used t help answer these questins. This paper will fcus n pen-set speech perceptin results fr implanted children. Many tests f speech perceptin have been used and deve\pc! fr assessing children with <;chlear implants. hwever, it is pen-set tests f wrd and sentence recgnitill that prbably prvide the best measure f the cffectivcness f!he device in real-life situatins. Open-set wrd and sentence tests are!he typ:c21 speech perceptin assessments used in clinical audilgy. Therefre the results f such assessments can readily be cmpared with data fr lher hearing-impaired ppulatins. These tests als prvide a measure f hw much speech can be identified by a subject withut additinal cues such as cntext r lists f alternatives. Clsed-set speech p!lceptin tasks prvide impnant infrmatin abut specific discriminatin abilities :and are invaluable fr research studies. They are als useful fr assessing children wh scre prly n penset tasks. Hwever, scres n these assessments can smctirr:..es be misleading and difficult t relate t cmmunicatin benefit. wrking with thc child. Fr lder childrcn, tape-recrded presentatin was used. Material was presented nly nce and strict precautins were taken t prevent any visual cues being available t the child. Fr lder children. written respnses were madc fr each item and scred after thc sessin. Fr the majrity f children, verbal respnses were videtaped and scred by tw independent listeners at a later time. These scres were averaged t give the [mal scre fr the test. If the independent scres differed by mre than 5%, a third serer was enlisted t view the videtape. Scring difficulties resulted mstly frm ambiguities aris!ng frm speceh prductin errrs: RESULTS Open-set sentence assessments Figure 1 shws results fr 50 f thc 52 children fr the pen-set BKE sentence test using auditin alne. Tw f the yung children in the grup failed t cmplete the task successfully. The mean scre fr this grup was 32.4% with a range frm 0% t 94%. Eighty-six percent f the grup perfrmed significantly n this task. Half f the grup exc('eded a scre f25% and 13 children (26%) scred abve 50%.. SYDNEY'97 XVJ Wrtd Otrhinla<ynglgy Open-set speech perceptin results fr 52 children wh wcre experienced users f the Nucleus cchlear prsthesis will be presented and utalyzed. A number f pssible predictive factrs. including age at implantatin, will be examinee with reference t the speech perceptin results, and the implicatins fr the future f cchlear implantatin in children discussed. MATERIAlS AND MEI'HODS Subjects The subjects in this study were 49 children and adlescents ",-n received a Nucleus multiple chancl cchlear prsthesis in Melburne between 1985 and 1994 and 3 children wh received their implant elsewhere but are nw residclt in Melburne. The subjects were nt selected in any way except that they needed the necessary cgnitive and language skius t cmplete pen-set wrd and sentence testil:.g. In mst cases, this meant that the children were ver six years f age. This grup f 52 children represented 75% f the implanted children and adlescents in Melburne at lst January, The mean age at the time f implantatin fr the grup was 7.7 years with a range frm 1.9 t 19.9 years. Thiny-fur f the children (66%) had a cngenital prfund hearing lss. Twelve children had a prfund hearing lass due t meningitis with nset f thc hearing lss befre the age f three years.. Six children had prgressive hearing lsses with nset f prfund hearing lss after the age f three years. All children had ver twelve mnths experience with use f thc cchlear prsthesis when assessed, with a mean f 3.7 years experience fr the grup. Mst f the children were assessed using the MSP-MULTIPEAK speech prcessr during 1994 and 1995, but eight f the results were btained using the SPECTRA-SPEAK prcessr. Results frm Cwan et al (1995) shwed that a grup f twelvc childr::::::t shwed significant imprvement in speech perceptin whcn changed t the SPECTRA prcessr frm the MSP. These imprvements varied acrss the subjects ",dth a mean imprvement f 8.1% frm 54.5% t 62.6% fr the grup n a cmbined. pen-set scre. Thus, the different prcessrs used in the current study may have sme effect n scres, althugh the results mainly reflect perfrmance using the MSP prcessr. As such, it is reasnable t assume that funher impro\'ements may ccur "..ben all children have changed t the SPEcrRA system. Tbcse results were analysed using multiple linear regressin including the. fllwing predictive variables: age at implantatin; cngenital, meningitis r prgressive hearing lss; duratin f prfund hearing lss; experience with implant use; and pstperative educatinal prgram. These variables were used based n the results f previus studies by Dwell et al (1995). One f the prblems with this type f analysis is that sme f the predictive variables are interrelated. In particular, as mst f the children in the study were cngenitally deaf, their age and duratin f hearing lss were the same. Fr this reasn, age and duratin f prfund hearing lss were included in separate analyses with the ther variables. This analysis shwed that shner duratin f prfund hearing lss (p<o.ool), an ral/aural educatinal setting (P<O.Ol), prgressive hearing lss (p<o.ol) and significant preperative residual hearing (p<o.05) were assciated with better scres fr the BKE Percent crrect subject n. (arbitrary) Mean Test Technique Figure Thc BKB sentence test (Bench and Bamfrd, 1979) and PBK wcr::: test (Haskins, 1949) were presented, using live vice in mst cases, by an a~;lgis, r specch pathlgist Individual results fr 50 children and adlescents implanted with the Nucleus multiple channel cchlear prsthesis n the BKE pen-set sentence test using auditin alne. 299

3 XVI Wrld Olrhinlarynglgy Sydney. Austran. 2-7 MarcIl 1997 pen-set sen\cnce test. Yunger agc at implantatin was als assciated willi bett~r scres, althugh tbe duratin f hearing lss was mre effective in explaining the results fr acquired deafness. There was n significant difference in results fr the meningitis grup cmpared with the cngenital prfund deafness grup. Experience willi the prsthesis did nt shw a significant effect althugh it shuld be pinted ut that all children in the grup had ver 12 mnths implant use and mst had cnsiderably mre_ The fur significant factrs accunted fr apprximately 50% f the. variance in the sentence scres. Open-set wrd nssessments Figure 2 shws results fr the 52 children n the pen-set PBK wrd test alne. The scres are given in terms f percentage f phnemes crrectly This treatment prvides mre infllnatin ahut the children's speech perceptin than a whle wrd scre. Wrd scres wuld typically be significantly lwer than the phneme scres fr a particular test and when scred by phnemes this test has a chance scrc f apprximately 5%_ The mcan scre fr this grup was 41.8% willi a range frm 5% t 93%. Ninety-fur percent f the grup perfrmed' significantly n this task. Half f the grup exceeded a scre f % and 18 children (34%) scred abve 50%. These results wcre submitted t a similar multiple linear' regressin analysis t the sentence scres as detailed abve. This analysis shwed that shrter duratin f prfund hearing lss (p<0.001) and an ral/aural edueatinal setting (p<0.01) were assciated with better phneme scres fr the PBK pen-set wrd tesl Yunger age at implantatin was als assciated willi better scres, althugh the duratin f hearing lss was again mre effective in explaining the results fr acquired deafness. N significant effect was evident fr preperative residual hearing, in cntrast t the results fr sentences, but tbe prgressive hearing lss grup perfnrmed significantly better (p<0.01) than the rest f the grup. There was n significant grup r fr the implant experience variable as was analysis. DISCUSSION These results fr a grup f children using the Nucleus multiple-<:hannel cchlear prsthesis shw that pen-set speecb perceptin is nt nly pssible fr implanted children with prfund deafness but shuld be cnsidered the nrm. Pstlingually deaf adults have shwn gd pen-set results fr sme time. These adults learn t fit a ru:'vel r unusual auditry input 10 their internal mdel f auditry perceptin and language. This ean be smewhat difficult but is facilitated by the wealth f stred experience and, prcessing abilities built up prir t the nset f prfund hearing lsst It is particularly significant t sec children with little r n auditry experience prir t implantatin t understand speech using the implant alne. Many f these children I their auditry prcessing and auditry language abilities exclusively use f the implant and the facl that this can be achieved represents an imprtant step the c1inieal applicatin f ccchlear prstheses. The resullq als shw that nt all children achieve gd pen-set speech perceptin. The mean scres fr sentence perceptin (32.4%) and phnemes in wrds (41.8%) are mderate and the range f perfrmance is large. The regressin analyses described abve prvide sme clues t the reasns fr this variatin. The strng effect f duratin f deafness and age n results is nt surprising. This appears t reflec.t bth the detrimental effect f sensry deprivatin fr thse with an acquired deafness, and enbanced learning ability in yunger children willi cngenital deafness. Thus, a child wh has a cngenital prfund hearing lss r is deafened early in life will have a much beller chance f learning t understand speech if they are implanted as yung as pssible. The results d nt suggest that there is a crucial age, beynd which implantatin is nt useful, but that the chances f develping gd pen-set speecb perceptin decrease with age. T illustrate this pint, it is nted thatthrce children with cngenital deafness, wh were implanted after the age f ten years, scred ver 25% fr the BKB pen-set sentence test. XVI Wrld Otrh!nla~glgy 2-7 Marcil 1997 Percent crrect Mean scre (percent) DPBK{phn) SIIIBKB sent Mean subject n. (arbitrary) Figure 2 lndividual results fr 52 children using the Nucleus multiple channel cchlear prsthesis n the PBK pen-set wrd test using auditin alne. Scres are percentage f 300 phnemes crrecl Figure 3 Ot 3 3 t t 18 Prgressive Age at implantatin (years) Mean pen-set speech perceptin results fr a grup f 52 children implanted with tbe Nucleus multiple channel cchlear prsthesis gruped accrding t age at implantatin and type f hearing lss (see te"t). 301

4 XVI W~d Otrhinlarynglgy The small grup f children with a prgressive hearing lss perflli) significantly beller n wrd and sentence tests than the rest f the grup (see Figure 3). This can be explained quite simply, in that all f these children had relatively gd hearing during the imprtant language develpment phase up t tbree years f age, thus their situatin when implanted was mre like pstlingually deaf adults than the children with a cngenital prfund lss. Figure 3 summari= the effcct f age at implantatin n results fr the wrd and sentence tests. The prgressive hearing "lss grup has been separated ut here t highlight the significant difference fr this grup. The mean scres fr this grup f 72% fr sentences and 62% fr phnemes in wrds cmpare favurably with results fr pstlingually deafened adults using the Nucleus prsthesis. Mean scres fr adults using the MSP-MULTIPEAK prcessr were 59% fr pl;.n-set sentences and 48% fr phnemes in mnsyllables at their six mnths pstperative assessment (Hllw et ai, 1995). It is clear fr the early deafened children thst there is a relative advantage in speech perceptin perfrmance fr thse implanted befre three years f age. It shuld be highlighted again, hwever, that these mcan results can be misleading in that they hide a large amunt f variatin in perfrmance in all grups. It is likely that ther factrs, sme f which have been identified in this study, and thers that may be difficult t quantify, playa rle as imprtant as age fimplantatin in utcmes. The educatinal management f implanted children was significant in the analyses fr bth sentence and wrd tests. In essence, this result is suggesting that children in an ral/aural schl fr hearing-impaired children r in a mainstrcamed setting may be develping speech perceptin skills mre effectively than thse in a "Ttal Cmmunicatin se!!ing where a visual supplement is used fr cmmunicatin. Befre such evidence is used t dismiss the use f manual cmmunicatin methds fr implanted children, we must remember that the cmmunicatin needs f yung children shuld be cnsidered carefully in additin t the develpment f auditfy skills. In individual cases, manual cmmunicatin may prvide the nly useful interactin fr a prfundly hearing-impaired child prir t implantatin and during many mnths r years pstperatively as they leam t use the prsthesis. On the ther hand, tbe available evidence suggests that if a child has a cchlear implant, parents shuld be encuraged t prgress twards an educatinal se!!ing which encurages the use f auditin fr cmmunicatin. perceptin. This effect was evident dwn t the age f threc years. An ral/aural educatinal prgram fllwing implantatin and preperative residual hcaring were als assciated with better scres. With imprved techniques fr the early diagnsis f hearing lss and tec:l1nical imprve~ents in all aspects f cchlear prstheses we can expect mst yung children with implants t develp gd pen-set speech perceptin in Ihe future. REFERENCES BENCH, I. and BAMFORD I. Speech-hearing tests and the spken language f hearing-impaired children. Lndn. Academic Press ClARK, G.M., Cchlear Implants: Histrical Perspectives. In Prfund Deafness and Speech Cmmunicatin &is. G.Plant and K.E. Spens. pp Lndn. Whurr Publishers Ltd COWAN, R.S.C., BROWN, C., WHITFORD L.A., GALVIN K.L, SARANT I.Z., BARKER E.l. et a!. Speech perceptin in children using the advanced SPEAK speech prcessingslrategy. Ann 0101 Rhinal LafYngl 104 (Supplement 166): DOWELL, R.C BLAMEY. P.J., CLARK G.M., Ptential and limitatins f cchlear implants in children. Ann Otl Rhinl LafYngl 104 (Supplement 166): , HOLLOW, R.D., DOWELL R.C., COWAN, R.S.C., et al. Cnlinuing Imprvements in speech prcessing fr adult cchlear implant patients. Ann 0101 Rhinl LafYngl 104 (Supplement 166): , HASKlNS, I., Audtitcc, Kindergarten Phnelically Balanced Wrd Lists (PBK). SI Luis. XVI.Wrld Cngress 01 Otrhinlarynglgy sydney. Australi. Preperative residual hearing was als identified as a significant factr in the analysis f sentence results but nt fr the wrds. It is reasnable t assume that the mre hearing a child has prir t implantatin, the greater chance they have f develping sme auditry language skills. This depends, f curse, 00 hw well this hcarig is utilised with apprpriate amplificatin and early interventin strategies. The auditry language skills f tbe child, hwever minima~ may cnlribute 10 faster r mre effective learning nce they receive a cchlear implant. CONCLUSIONS 302 Results fr children and adlescents wh are lng term users f the Nucleus multiple channel cchlear prsthesis shw that the majrity develp significant pen-sct specch perceptin using the device withut lipreading r ther cues. Mean scres fr BKE I sentences were 32.4% (n-50) and fr phnemes in PBK mnsyllabic wrds, (n=52). Children with prgressive hearing lsses with nset f prfund dearness after the age f three ycars perfrmed significantly beller n Ihese tasks. The age f implantatin fr cngenitally deaf children r duratin f prfund hearing lss fr thse with acquired hearing lss, had a significant effect n perfrmance with yunger age and shrtcr duratin f dearness assciated with be!!cr pen-set speech 303

5 Minerva Access is the Institutinal Repsitry f The University f Melburne Authr/s: Dwell, R. C.; Blamey, P. J.; Clark, Graeme M. Title: Factrs affecting utcmes in children with cchlear implants Date: 1997 Citatin: Dwell, R. C., Blamey, P. J., & Clark, G. M. (1997). Factrs affecting utcmes in children with cchlear implants. In Cchlear Implants: XVI Wrld Othinlarynglgy, Sydney, N.S.W. Persistent Link: File Descriptin: Factrs affecting utcmes in children with cchlear implants Terms and Cnditins: Terms and Cnditins: Cpyright in wrks depsited in Minerva Access is retained by the cpyright wner. The wrk may nt be altered withut permissin frm the cpyright wner. Readers may nly dwnlad, print and save electrnic cpies f whle wrks fr their wn persnal nn-cmmercial use. Any use that exceeds these limits requires permissin frm the cpyright wner. Attributin is essential when quting r paraphrasing frm these wrks.