Maturation of Auditory Brainstem Responses in Babies from Birth to 6 Months of Age

Transcription

1 ORİJİNAL ARAŞTIRMA Maturation of Auditory Brainstem Responses in Babies from Birth to 6 Months of Age Burak ÖZTÜRK, PhD, a G. Aydan GENÇ, PhD a a Department of Ear Nose and Throat and Head and Neck Surgery, Division of Audiology, Hacettepe University Faculty of Medicine, Ankara Ge liş Ta ri hi/re ce i ved: Ka bul Ta ri hi/ac cep ted: Ya zış ma Ad re si/cor res pon den ce: G. Aydan GENÇ, PhD Hacettepe University Faculty of Medicine, Department of Ear Nose and Throat and Head and Neck Surgery, Division of Audiology, Ankara, TÜRKİYE/TURKEY aydangenc@gmail.com ABS TRACT Ob jec ti ve: New born he a ring scre e ning plays an im por tant ro le in ma king a di ag no sis wit hin the first six months of li fe in con ge ni tal he a ring los ses. In this age gro up, the in fant s ma t- u ra ti on is inf lu en ti al in the eva lu a ti on of the Au di tory Bra ins tem Res pon se (ABR) test, which is im por tant in di ag no sis. Be ca u se many ABR cha rac te ris tics vary with age, age-re la ted ma tu ra ti o - nal va lu es must be es tab lis hed for all po pu la ti ons to be eva lu a ted. The pur po se of the pre sent study was to es tab lish age-re la ted ma tu ra ti o nal chan ges for in fants aged 0-6 months. Ma te ri al and Met hods: ABR was me a su red in 180 sub jects from 0 months to 6 months of age. Tran si ent Evo - ked Oto a co us tic Emis si on (TE O A E), Au to ma ted Au di tory Bra ins tem Res pon se (AABR) and di agnos tic ABR tests we re per for med res pec ti vely for each sub ject. Re sults: In our study, ma tu ra ti o nal da ta of ABR ab so lu te la ten ci es and in ter pe ak la ten ci es ob ta i ned at dif fe rent age gro ups and sti mu li in ten sity le vel we re pre sen ted. Ac cor ding to our study re sults, ab so lu te la ten ci es of wa ves I, II I, V, and I-II I, II I-V, I-V in ter pe ak la ten ci es dec re a sed as a func ti on of ad van cing age. Whi le ab so lu te la ten ci es of wa ves I, II I, V sho wed a syste ma tic in cre a se, I-II I, II I-V, I-V in ter pe ak la ten ci es dec re - a sed as sti mu lus in ten sity dec re a sed from 80 db nhl to 20 db nhl. To our re sults, the re we re no sig ni fi cant dif fe ren ces bet we en gen der and ears in terms of wa ve ab so lu te la ten ci es and in ter pe ak la ten ci es. Conc lu si on: Know led ge on the ABR cha rac te ris tics wit hin first six months of li fe will enab le cli ni ci ans to dis cri mi na te nor mal si tu a ti ons from pat ho lo gic ones in di ag no sing he a ring loss for the in fant po pu la ti on. Key Words: Evo ked po ten ti als, au di tory, bra in stem; in fant, new born ÖZET Amaç: Ye ni do ğan işit me ta ra ma sı, do ğum sal işit me ka yıp la rın da ya şa mın ilk al tı ayın da ta - nı koy ma da önem li rol oy nar. Bu yaş gru bun da ta nı da önem li olan işit sel be yin sa pı ce va bı (İBC) tes ti nin de ğer len di ril me sin de be be ğin ma tü ras yo nu et ki li dir. Çün kü pek çok İBC özel li ği yaş la deği şir; ya şa uy gun ma tü ras yon de ğer le ri, de ğer len di ri le cek olan tüm po pu las yon lar için be lir len meli dir. Bu ça lış ma nın ama cı, 0-6 ay lık be bek ler de yaş la uyum lu ma tü ras yo nel de ği şik lik le rin be lir len me si dir. Ge reç ve Yön tem ler: Ça lış ma da, 0-6 ay lık 180 ol gu da İBC öl çül dü. Her ol gu ya sıray la kı sa sü re li uya rıl mış oto a kus tik emis yon (KU O E), oto ma tik işit sel be yin sa pı ce va bı (OİBC) ve ta nı sal İBC test le ri ya pıl dı. Bul gu lar: Ça lış ma mız da, fark lı yaş grup la rın dan el de edi len İBC olu şum sü re le ri nin ma tu ras yo nel ve ri le ri ve dal ga te pe le ri ara sı olu şum sü re le ri ve uya rı şid det dü ze yi sunul du. Bi zim ça lış ma so nuç la rı mı za gö re, iler le yen ya şın bir iş le vi ola rak I, II I, V. dal ga la rın olu şum sü re le ri ve I-II I, II I-V, I-V dal ga te pe le ri ara sı olu şum sü re le ri azal dı. I,II I,V. dal ga la rın olu şum süre le ri sis te ma tik bir ar tış gös te rir ken, I-II I, II I-V, I-V dal ga te pe le ri ara sı olu şum sü re le ri uya rı yoğun lu ğu 80dB nhl den 20 db nhl ye düş tük çe azal dı. Bi zim so nuç la rı mı za gö re, dal ga olu şum sü re le ri ve dal ga te pe le ri ara sı olu şum sü re le ri açı sın dan cin si yet ler ve ku lak lar ara sın da be lir gin fark yok tur. So nuç: Kli nis yen le rin 0-6 ay da ki İBC özel lik le ri ni bil me le ri, bu po pu las yon da işit me kaybı nın ta nı sın da nor mal du rum la rı pa to lo jik du rum lar dan ayır ma yı ko lay laş tı ra cak tır. doi: /medsci Cop yright 2012 by Tür ki ye Kli nik le ri Anah tar Ke li me ler: Uya rıl mış po tan si yel ler, işit sel, be yin sa pı; be bek, ye ni do ğan Turkiye Klinikleri J Med Sci 2012;32(3): Turkiye Klinikleri J Med Sci 2012;32(3) 677

2 Öztürk ve ark. ew born he a ring test is very im por tant in the sen se that it pro vi des for an early di agno sis in ba bi es who suf fer from con ge ni tal he a ring loss and al lows them to de ve lop as clo sely as pos sib le to the ir pe ers. 1,2 The aim of the new born he a ring test is to ma ke a di ag no sis when the in fants are 3 months old. 3 In ad di ti on, di ag nos tic tests are as im por tant as scan tests, be ca u se they al low re c- om men da ti on to be ma de for he a ring aids when the in fants are 6 months old. 4,5 Au di tory bra in stem res pon se (ABR) tests al so ha ve a sig ni fi cant ro le du - ring the new born pe ri od and in the eva lu a ti on of he a ring. The au to ma ted au di tory bra ins tem res - pon se (AABR) is wi dely used as a he a ring scre e ning test du ring the first few months of li fe in newborns. 1,2,6-8 Whi le ba bi es with pos sib le he a ring loss are de ter mi ned du ring the he a ring scan with this test, the di ag nos tic ABR has a cri ti cal ro le in the de fi ni ti ve di ag no sis of ba bi es with pos sib le he a ring loss. 9 Alt ho ugh di ag nos tic ABR is among ob jec ti ve tes ting met hods, it al so car ri es a sub jec ti ve cha racte ris tic, du e to its eva lu a ti on met hod and the ro le of the cli ni ci an in the eva lu a ti on of the re sults. In ABR in ter ven ti ons in in fancy, in ad di ti on to the ex pe ri en ce of the cli ni ci an, the ma tu ra ti on of the in fant is ef fec ti ve on the re sults. 9 Pa ral lell to the in cre a sed num ber of new born he a ring scre e ning, the num ber of ABR tests is al so ri sing in the first six months of li fe. The ma tu ra ti - on le vel of the in fant sho uld be con si de red in the in ter pre ta ti on of the ABR test re sults for tru e outco mes. 10,11 Over lo o king the ma tu ra ti on le vel in the in ter pre ta ti on of re sults may ca u se a baby who has nor mal he a ring to be di ag no sed with he a ring loss. 11 Thus, ma tu ra ti o nal va lu es in this pe ri od are very im por tant. 10,11 Age, even mar ked in ho urs af ter birth, is a very per ti nent va ri ab le af fec ting the ABR. The ABR chan ges with age, par ti cu larly du ring the first 12 to 18 months of li fe, as the cen tral au di tory system con ti nu es to ma tu re. 12,13 The cli ni ci an must al ways ru le out, or at le ast ta ke in to ac co unt, the pos sib le inf lu en ce of sub ject age in re cor ding and analy zing an ABR, be fo re the re sults of tes ting are in ter pre - ted. 14 It is es sen ti al to ha ve a cle ar de fi ni ti on of the nor mal res pon se be fo re ab nor mal res pon ses can be de tec ted in ABR tes ting of in fants, be ca u se, ma tura ti on mar kedly al ters res pon se la tency and inf luen ces wa ve form morp ho logy. To ma ke ad just ments for the se ma tu ra ti o nal ef fects each cli nic con duc t- ing ABR tes ting ro u ti nely de ve lops its own res pon - se la tency norms for dif fe rent con cep tu al ages. 15 The pur po se of this in ves ti ga ti on was to qu antify the cha rac te ris tics of the ABR to click sti mu li of va ri o us in ten sity le vels du ring the first 6 months of age. The cha rac te ris tics of the ABR in ves ti ga ted in this study we re; 1) me an ab so lu te la ten ci es and stan dard de vi a ti ons (SDs) of wa ves I, II I, and V, and 2) me an in ter pe ak la ten ci es and SDs of wa ve I-II I, II I-V and I-V. MA TE RI Al AND MET HoDS Ha cet te pe Uni ver sity Fa culty of Me di ci ne Et hi cal Com mis si on ap pro ved the study pro to co le. (LUT 07/35). Sub jects Kulak-Burun-Boğaz Hastalıkları The study po pu la ti on com pri sed full-term chil dren (ges ta ti o nal age 38 we eks) who un der went newborn he a ring scre e ning. The cri te ri a for be ing as sig - ned to any of the study gro ups we re to ha ve pas sed the Tran si ent Evo ked Au to a co us tic Emis si on (TE- O A E) and AABR tests. The par ti ci pant ba bi es we - re ran domly se lec ted from he a ring scre e ning arc hi ves and we re as sig ned to 6 gro ups. The gro ups we re for med ba sed on age. The fa mi li es of the babi es we re cal led and tho se who ap pro ved the ir baby to jo in the study we re in vi ted. The re por ted ABR da ta we re ob ta i ned from 180 sub jects (90 boys and 90 girls) aged bet we en 2 and 180 days. Each gro up con sis ted of 30 ba bi es. Six gro ups we re for med ac cor ding to the chro - no lo gic age of the sub jects, ran ging from 1-30 days to days (Tab le 1). All sub jects who had risk fac tors for he a ring loss pub lis hed by the Jo int Commit te e on In fant He a ring we re exc lu ded. All subjects who pas sed the TE O A E and AABR scre e ning tests for both ears we re inc lu ded to ta ke the di agnos tic ABR test. 678 Turkiye Klinikleri J Med Sci 2012;32(3)

3 Ear-Nose-Throat Diseases TABLE 1: Chronological and gestational ages of groups. Groups Chronological age (days) Gestational age (weeks) Min-Max Mean Min-Max Mean Group I (1-30 days) , Group II (31-60 days) Group III (61-90 days) Group IV ( days) Group V ( days) Group VI ( days) StImu li The aco us tic sti mu lus in each ca se was an un fil te - red click (0.1 ms du ra ti on) trans du ced with a cli - ni cal in sert earp ho ne and pre sen ted at al ter na ting po la rity. Click sti mu li we re pre sen ted mo na u rally to the right and left ears of each sub ject wit ho ut the use of con tra la te ral mas king. Click re pe ti ti on ra tes emp lo yed we re 11.1 clicks/s. The ab so lu te laten ci es of wa ves I, III and V of the ABR we re re cor - ded at sti mu lus le vels of 80 db nhl, 60 db nhl, 40 db nhl and 20 db nhl, res pec ti vely. Re cor ding tech ni qu e Res pon ses we re re cor ded from scalp elec tro des attac hed to the fo re he ad at the ha ir li ne and the ip sila te ral mas to id pro cess. The con tra la te ral mas to id pro cess ser ved as gro und. In te re lec tro de im pe dan - ces did not ex ce ed 3000 ohms. The on go ing EEG was samp led thro ug ho ut a 15-ms post-sti mu lus peri od, amp li fi ed by a fac tor of 10 5, fil te red bet we en 30 and 3000 Hz, and ave ra ged over at le ast 1500 click pre sen ta ti ons using an In tel li gent He a ring System (IHS). For every con di ti on, at le ast two rep - li ca ting tri als we re run. The in di vi du al wa ve la tenci es ob ta i ned from rep li ca ting tri als of each sub ject we re ave ra ged, yi el ding a sing le ab so lu te la tency for each iden ti fi ab le wa ve at every con di ti on. The ori gi nal no menc la tu re of Je wett and Wil lis ton was used for iden tif ying ABR wa ves I thro ugh V. PRo ce du ReS All tes ting was per for med in a so und-iso la ted ro om whi le the in fants we re in na tu ral sle ep; no se da ti on was re qu i red for any sub ject. For each sub ject TE O - A E, AABR and di ag nos tic ABR we re per for med, res pec ti vely. TE O A E and AABR we re per for med initi ally using MAD SEN Ac cus cre en Pro hand led GN Oto met rics, Den mark com bi ned scre e ning Oto a- cus tic Emis si on (OA E) and ABR system. Di ag nos tic ABR tests we re per for med in sub jects who pas sed the TE O A E and AABR scre e ning tests for both ears. In di ag nos tic ABR for each ear, the ini ti al sti mu lus le vel typi cally was a click at 80 db nhl, which always re sul ted in a cle ar res pon se. Sti mu lus le vel was then dec re a sed by 20-dB steps down to a le vel of 20 db nhl. Me an ab so lu te la ten ci es and SDs for wa - ves I thro ugh V we re de ter mi ned for both ears for each chro no lo gi cal age gro up and at every sti mu lus in ten sity le vel, ex cept for 20 db nhl. Be ca u se of low sti mu lus in ten sity le vel, it was not pos sib le to iden tify wa ves I and III in a lar ge pro por ti on of subjects at 20 db nhl. In ad di ti on, in ter pe ak la ten ci es we re cal cu la ted for each sub ject and then we re ave ra ged ac ross each age gro up. At 20 db nhl, me an ab so lu te la ten ci es of wa ve V we re cal cu la ted only and the re fo re, in ter pe ak la ten ci es co uld not be calcu la ted. Ba sed on the re sult of di ag nos tic ABR tests, da ta from both ears of each sub ject we re used in deve lo ping our age-matc hed norms. Sta tis tical analy SIS The SPSS 11 for win dows soft wa re pac ka ge was used for sta tis ti cal analy ses. The descriptive statistics, independent samples t-test and paired samples t-test were used in the statistical analysis. Ap va lu e of <0.05 was con si de red sig ni fi cant. RE SUlTS Me an ab so lu te la ten ci es and SDs for wa ves I thro - ugh V, at each sti mu lus in ten sity le vel and for each chro no lo gic age gro up, was cal cu la ted from the indi vi du al sub ject da ta. In ad di ti on, in ter pe ak la tenci es we re cal cu la ted for each sub ject and then we re ave ra ged ac ross each age gro up. ab So lu te la ten ci es Öztürk et al. Tab le 2 and Tab le 3 sum ma ri ze me an ab so lu te laten ci es and stan dard de vi a ti ons of wa ve I, II I, and V for right and left ear, res pec ti vely for each age gro up and sti mu lus in ten sity le vel. At 20 db nhl, ab so lu te la tency of wa ve V only was ave ra ged and Turkiye Klinikleri J Med Sci 2012;32(3) 679

4 Öztürk ve ark. re por ted he re for both ears as exp la i ned be fo re (Tab le 2, Tab le 3). The ab so lu te la ten ci es of wa ve I thro ugh V dec re a sed syste ma ti cally with in cre a sing sti mu lus le - vel. The ab so lu te la ten ci es of wa ve I dec re a sed with in cre a sing chro no lo gi cal age up to the days age ca te gory for both ears (p<0.05). Star ting from this age ca te gory, wa ve I la tency did not sig ni ficantly chan ge at any in ten sity le vel for both ears (p>0.05). If wa ve I la tency is con si de red a me a su re of pe rip he ral res pon se ma tu rity, then it ap pe ars that the pe rip he ral res pon se to click sti mu li is matu re early in li fe. The re was a very or derly prog res si on in wa ve III and V la tency as chro no lo gic age in cre a sed. Wa - ve III and V la ten ci es we re shor ter for sub jects 151- Kulak-Burun-Boğaz Hastalıkları 180 days of age com pa red to sub jects in the 1-30 days age ca te gory. The lar gest chan ges oc cu red in the ear li er age gro ups, and the chan ges be ca me prog res si vely smal ler in the sub se qu ent age gro ups. Both wa ves III and V we re cha rac te ri zed by dec - re a ses in ab so lu te la tency, whi le still not re ac hing adult va lu es by 180 days of li fe. As the in fants deve lo ped, wa ve III and V la ten ci es dec re a sed to ward adult va lu es. The me an ab so lu te la ten ci es of wa ve I thro ugh V from Tab le 2 we re plot ted in Fi gu res 1 to 3 as a func ti on of le vel with age for the right ear. The me an ab so lu te la ten ci es of wa ve I thro ugh V from Tab le 2 we re plot ted in Fi gu res 4 to 6 as a func ti on of le vel with age as the pa ra me ter for the left ear. TABLE 2: Mean absolute latencies(m) and standard deviations(sd) of waves for right ear in each group. Group 1 Group 2 Group 3 Group 4 Group 5 Group 6 Wave Intensity level M SD M SD M SD M SD M SD M SD Wave I 80 db nhl db nhl db nhl Wave III 80 db nhl db nhl db nhl Wave V 80 db nhl db nhl db nhl db nhl TABLE 3: Mean absolute latencies(m) and standard deviations(sd) of waves for left ear in each group. Group 1 Group 2 Group 3 Group 4 Group 5 Group 6 Wave Intensity level M SD M SD M SD M SD M SD M SD Wave I 80 db nhl db nhl db nhl Wave III 80 db nhl db nhl db nhl Wave V 80 db nhl db nhl db nhl db nhl Turkiye Klinikleri J Med Sci 2012;32(3)

5 Ear-Nose-Throat Diseases The dif fe ren ce bet we en the right and the left ears for ab so lu te la tency va lu es was not sig ni fi cant in any gro up (p>0.05). In ter Pe ak la tency Tab le 4 and Tab le 5 sum ma ri ze me an in ter pe ak laten ci es and stan dard de vi a ti ons of wa ve I-II I, II I-V, and I-V for the right and left ears, res pec ti vely for each age gro up and sti mu lus in ten sity le vel. At 20 db nhl, in ter pe ak la tency co uld not be cal cu la ted and re por ted for both ears as exp la i ned be fo re (Tab le 4, Tab le 5). The re was a syste ma tic dec re a se in the I-II I, II I- V, and I-V in ter pe ak la ten ci es with in cre a sing chro - Öztürk et al. no lo gi cal age and with dec re a sing sti mu lus in ten sity le vel. As the in ten sity le vel dec re a sed, the ab so lu te la tency of wa ve I in cre a sed mo re com pa red to the ab so lu te la ten ci es of wa ve III and V. The re fo re, I-III and I-V in ter pe ak la ten ci es dec re a sed as the in tensity le vel dec re a sed. In ter pe ak la ten ci es for wa ves I- II I, II I-V, and I-V we re cha rac te ri zed by dec re a ses in la tency, whi le still not re ac hing adult va lu es by 180 days of li fe. As the in fants de ve lo ped, I-II I, II I-V, and I-V in ter pe ak la ten ci es dec re a sed to ward adult va lu es. The me an in ter pe ak la ten ci es from Tab le 4 we re plot ted in Fi gu res 7 to 9 as a func ti on of le vel with age as the pa ra me ter for the right ear. FIGURE 1: Absolute latency of wave I at click levels from 40 db nhl to 80 db nhl for the right ear in each group. FIGURE 2: Absolute latency of wave III at click levels from 40 db nhl to 80 db nhl for the right ear in each group. FIGURE 3: Absolute latency of wave V at click levels from 20 db nhl to 80 db nhl for the right ear in each group. Turkiye Klinikleri J Med Sci 2012;32(3) 681

6 Öztürk ve ark. Kulak-Burun-Boğaz Hastalıkları FIGURE 4: Absolute latency of wave I at click levels from 40 db nhl to 80 db nhl for the left ear in each group. FIGURE 5: Absolute latency of wave III at click levels from 40 db nhl to 80 db nhl for the left ear in each group. FIGURE 6: Absolute latency of wave V at click levels from 20 db nhl to 80 db nhl for the left ear in each group. TABLE 4: Means (M) and standard deviations (SD) of interwave latencies from 80 db nhl to 40 db nhl as a function of age for the right ear. Group 1 Group 2 Group 3 Group 4 Group 5 Group 6 Wave Intensity level M SD M SD M SD M SD M SD M SD I-III interpeak latency 80 db nhl db nhl db nhl III-V interpeak latency 80 db nhl db nhl db nhl I-V interpeak latency 80 db nhl db nhl db nhl The me an in ter pe ak la ten ci es from Tab le 5 we re plot ted in Fi gu res 10 to 12 as a func ti on of le - vel with age as the pa ra me ter for the left ear. The dif fe ren ce in the in ter vi ew la tency va lu - es bet we en the right and the left ears was not signi fi cant for any gro up (p>0.05). 682 Turkiye Klinikleri J Med Sci 2012;32(3)

7 Ear-Nose-Throat Diseases Öztürk et al. TABLE 5: Means (M) and standard deviations (SD) of interwave latencies from 80 db nhl to 40 db nhl as a function of age for the left ear. Group 1 Group 2 Group 3 Group 4 Group 5 Group 6 Wave Intensity level M SD M SD M SD M SD M SD M SD I-III interpeak latency 80 db nhl db nhl db nhl III-V interpeak latency 80 db nhl db nhl db nhl I-V interpeak latency 80 db nhl db nhl db nhl DIS CUS SIoN Au di tory Bra ins tem Res pon se is an im por tant test pro ce du re in terms of not only the as sess ment of he a ring loss but al so for de ter mi ning ne u ro lo gic ma tu ra ti on in in fants. 11,16 Sin ce dif fe ren ces in sti - mu lus con di ti ons and band pass fil ter set tings re sult in dif fe rent ABR wa ve la tency va lu es, 17,18 the conc lu si ons in this re port are uni qu e to the spe ci fic sti - mu li and elec tro en cep ha log ram (EEG) re cor ding pa ra me ters emp lo yed in this in ves ti ga ti on. Alt ho ugh ABR is an ob jec ti ve and re li ab le test, non-pat ho lo gi cal fac tors in tes ted sub jects may inf lu en ce the out co me of the test. Non-pat ho lo gi cal fac tors inc lu de age and gen der, body tem pe ra tu re, sta te of aro u sal, at ten ti on, and the pos sib le ef fects of drugs. 11,19,20 Nu me ro us re ports con fir med the ABR as an in di rect me a su re of the ma tu ra ti on of the au di tory system in de ve lo ping nor mal in fants Un for tuna tely, it is dif fi cult to com pa re re sults ac ross stu - FIGURE 7: Interwave latency of wave I-III at click levels from 80 db nhl to 40 db nhl for the right ear in each group. FIGURE 8: Interwave latency of wave III-V at click levels from 80 db nhl to 40 db nhl for the right ear in each group. Turkiye Klinikleri J Med Sci 2012;32(3) 683

8 Öztürk ve ark. Kulak-Burun-Boğaz Hastalıkları FIGURE 9: Interwave latency of wave I-V at click levels from 80 db nhl to 40 db nhl for the right ear in each group. FIGURE 10: Interwave latency of wave I-III at click levels from 80 db nhl to 40 db nhl for the left ear in each group. FIGURE 11: Interwave latency of wave III-V at click levels from 80 db nhl to 40 db nhl for the left ear in each group. FIGURE 12: Interwave latency of wave I-V at click levels from 80 db nhl to 40 db nhl for the left ear in each group. di es be ca u se of a di ver sity of sti mu lus va ri ab les and sub jects. In con trast to ear li er stu di es, this study inc lu ded a ho mo ge ne o us gro up and in ves ti ga ted multip le sti mu lus in ten sity le vels to de ve lop an age-re la ted ma tu ra ti o nal da ta. The da ta ob ta i ned in this study we re used to qu an tify ABR chan ges oc cur ring wit hin the first 6 months of li fe and to de ve lop age-re la ted norms. Sub ject se lec ti on cri te ri a we re strin gently app li ed to as su re a nor mal full term sub ject po pu la ti on. Mul tip le sti mu lus in ten sity le vels we re emp lo yed to pro vi de ma tu ra ti o nal va lu es in dif fe rent age gro - ups. In this study, chan ges in ABR la ten ci es we re stu di ed for only the first six months of li fe. Jo int 684 Turkiye Klinikleri J Med Sci 2012;32(3)

9 Ear-Nose-Throat Diseases Com mit te e on In fant He a ring sug ges ted that the he a ring of all in fants sho uld be scre e ned using objec ti ve, physi o lo gi cal me a su res to iden tify tho se with con ge ni tal or ne o na tal on set he a ring loss. Audi o lo gi cal eva lu a ti on and me di cal eva lu a ti ons sho - uld be in prog ress be fo re 3 months of age. In fants with con fir med he a ring loss sho uld re ce i ve in terven ti on be fo re 6 months of age from he alt hca re and edu ca ti on pro fes si o nals with ex per ti se in he a - ring loss and de af ness in in fants and yo ung children. 3 It is cle ar that the first 6 months of li fe is cru ci al for di ag no sing he a ring loss and for re ce i ving edu ca ti o nal in ter ven ti on. To di ag no se he a ring loss in this po pu la ti on, age-re la ted ma tu ra ti o nal va lu es are ne e ded to in ter pret ABR re sults ac cu ra tely. The re is con si de rab le va ri a bi lity among in vesti ga ti ons in the ir ca te go ri za ti on of in fant age. For examp le in a study pub lis hed by Fri a and Doy le, 22 the new born gro up inc lu des in fants with con cep ti - o nal ages (ges ta ti o nal age at birth in we eks plus num ber of we ek sin ce birth) ran ging from 32 to 44 we eks. Ol der in fants we re ca te go ri zed by chro nolo gi cal age (we eks af ter birth) wit ho ut con si de ra ti - on of the ges ta ti o nal age (GA) of the in fants. Ja cob son et al. gro u ped new borns by GA only, and inc lu ded 25 sub jects who had at ta i ned an imp la u- sib le GA of mo re than 46 we eks. 24 The pre sent study gro u ped sub jects ac cor ding to the ir chro nolo gi cal ages at which ABR tes ting was imp le men ted and sub jects who se ges ta ti o nal age was 38 we eks we re exc lu ded from the study. So me stu di es re por ting nor ma ti ve va lu es we re ba sed on da ta from re la ti vely small gro ups of subjects. 25 In so me ca ses, the samp le si ze was uns pe cifi ed. Ho we ver, a se ri es of re ports exist that des cri be de ve lop men tal chan ges in ABR la ten ci es thro ugh adult ho od ba sed on lar ge samp le si zes. 21 In the pre - sent study, a lar ge samp le si ze we re used to de ve lop ma tu ra ti o nal va lu e norms and each gro up was equ - ally dis tri bu ted in terms of samp le si ze. In the pre sent study, wa ve I la tency did not chan ge from days to days of li fe. This sug gests that the func ti o nal ma tu rity of the pe rip he ral system is comp le te wit hin the first days fol lo wing full-term birth. The re exists, ho w- e ver, con si de rab le va ri a bi lity among in ves ti ga ti ons Öztürk et al. of the de ve lop men tal co ur se of wa ve I in the infant. So me in ves ti ga tors ha ve re por ted that wa ve I la tency ap pro xi ma tes adult va lu es at full-term birth (40 we eks GA); ot hers ha ve sug ges ted that the latency of wa ve I con ti nu es to dec re a se for 6 to 12 we eks fol lo wing full-term birth; still ot hers ha ve ob ser ved chan ges in wa ve la tency as la te as the se - venth month of li fe Wa ve III and V la ten ci es syste ma ti cally dec - re a se as chro no lo gi cal age in cre a ses. As the in fant de ve lops, wa ve III and wa ve V dec re a se to ward adult va lu es. In this study, wa ve III and V did not re ach adult va lu es up to 6 months of age, which was the up per age li mit of our study and con ti nu - ed the ir ma tu ra ti on. Ho we ver, the ra te of ma tu rati on for wa ves II I and V ex hi bits re mart kab le si mi la rity. The age of ma tu ra ti on ho we ver, dif fers bet we en the stu di es. Fri a and Doy le cal cu la ted the ma tu ra ti on of wa ve III and wa ve V at 107 and 113 we eks of chro no lo gi cal age, res pec ti vely. 22 Ac cor ding to our study re sults, ab so lu te la tenci es of wa ves I, II I, V and I-II I, II I-V, I-V in ter pe - ak la ten ci es dec re a sed with ad van cing age. Whi le ab so lu te la ten ci es of wa ves I, II I, V sho wed a syste - ma tic in cre a se, I-II I, II I-V, I-V in ter pe ak la ten ci es dec re a sed as sti mu lus in ten sity dec re a sed from 80 db nhl to 20 db nhl. The se re sults we re iden ti cal to the re sults of pre vi o us re ports. 28 If a cli ni ci an who works in an Ear, No se and Thro at or pe di at ric cli nic do es not ta ke in to ac co - unt the la tency pro per ti es re la ted to ne u ro lo gic ma tu ra ti on, an in fant who has nor mal he a ring can be mis di ag no sed with he a ring loss. ABR test re sults must be cross chec ked with ma tu ra ti o nal da ta to avo id fal se ne ga ti ve di ag no sis. Ma tu ra ti o nal va lu es de ter mi ned in a cli nic can be used by anot her cli - nic on con di ti on that the sa me pro to col is used. The pre sent in ves ti ga ti on rep re sents in fant ABR cha rac te ris tics using a ca re ful de sign and proto col. In or der to de ri ve com pre hen si ve in for ma ti - on re gar ding ABR de ve lop ment, sti mu lus in ten sity le vels we re ma ni pu la ted wit hin dif fe rent age gro - ups. Thus, ab so lu te la ten ci es and in ter pe ak la ten ci - es over a wi de ran ge of sti mu lus le vels we re re por ted for in fants from birth to 6 months of age. Turkiye Klinikleri J Med Sci 2012;32(3) 685

10 Öztürk ve ark. The da ta re ve al that the ABR ab so lu te and in ter pe - ak la ten ci es of in fants are sig ni fi cantly dif fe rent from tho se of adults, but prog res si vely ap pro xi ma - te the adult func ti on with in cre a sing age. CoNC lu SIoN New born he a ring test is very im por tant in the sen - se that it pro vi des in for ma ti on for an early di ag nosis in ba bi es who suf fer from con ge ni tal he a ring loss and al lows them to de ve lop as clo sely as pos sib le to the ir pe ers. As the new born he a ring scre e n- ing be co mes mo re wi des pre ad, the use of ABR will in cre a se du ring the first six months of li fe. Out co - mes of this study sho wed that func ti o nal ma tu rity of the pe rip he ral system was comp le te wit hin the Kulak-Burun-Boğaz Hastalıkları first days fol lo wing full-term birth. The abso lu te la ten ci es of wa ve I thro ugh V dec re a sed with in cre a sing chro no lo gi cal age and sti mu lus le vels whi le I-II I, II I-V, and I-V in ter pe ak la ten ci es dec - re a sed with in cre a sing chro no lo gi cal age and dec - re a sing sti mu lus le vels. The le vel of ma tu ra ti on sho uld be con si de red in the in ter pre ta ti on of the ABR test re sults for ac cu ra te out co mes. Over lo o - king the ma tu ra ti on le vel when in ter pre ting test re sults, may ca u se a baby who has nor mal he a ring to be di ag no sed with he a ring loss. Ack now led ge ments The aut hors thank to Er dem Ka ra bu lut, PhD for sta tis tical analy sis and to all pa rents for the ir col la bo ra ti on in this study. 1. Ste vens J, Par ker G. Scre e ning and sur ve il lan - ce. In: New ton VE, ed. Pe di at ric Au di o lo gi cal Me - di ci ne. 2 nd ed. Chic hes ter: West Sus sex, Wil ley-black well; p Genç GA, Er türk BB, Bel gin E. [New born he a ring scre e ning: past to pre sent]. Tur kish Pe di at ric Jo - ur nal 2005;48(2): Ame ri can Aca demy of Pe di at rics, Jo int Com mitte e on In fant He a ring. Ye ar 2007 po si ti on sta tement: Prin cip les and gu i de li nes for early he a ring de tec ti on and in ter ven ti on prog rams. Pe di at rics 2007;120(4): McGrath AP, Vohr B, o'ne il CA. New born he a r- ing as sess ment in Med He alth R I 2010;93(5): Whi te KR. New born he a ring scre e ning. In: Ma - dell JR, Fle xer C, eds. Pe di at ric Au di o logy. 1 st ed. New York: Thi e me; p Ahl fors CE, Amin SB, Par ker AE. Un bo und bi li - ru bin pre dicts ab nor mal au to ma ted au di tory bra - ins tem res pon se in a di ver se new born po pu la ti on. J Pe ri na tol 2009;29(4): Tun cer Ü, De mir H, Ay do ğan Bl, Yü ce E, Nar lı N. Un bo und bi li ru bin pre dicts ab nor mal au to ma - ted au di tory bra ins tem res pon se in a di ver se new born po pu la ti on. J Pe ri na tol 2009; 29(4): Whi te KR. Scre e ning prog rams for he a ring loss. In: lu xon l, Fur man JM, Mar ti ni A, Step hens D, eds. Text bo ok of Au di o lo gi cal Me di ci ne, Cli ni cal As pects of He a ring and Ba lan ce. 1 st ed. lon don: Tay lor&fran cis Gro up; p Purdy SC, Kelly AS. Au di tory evo ked res pon se tes ting in in fants and chil dren. In: Ma dell JR, Fle - xer C, eds. Pe di at ric Au di o logy. 1 st ed. New York: Thi e me; p REFERENCES 10. Pratt H. Hu man au di tory elec troph ysi o logy. In: lu - xon l, Fur man JM, Mar ti ni A, Step hens D, eds. Text bo ok of Au di o lo gi cal Me di ci ne, Cli ni cal Aspects of He a ring and Ba lan ce. 1 st ed. lon don: Taylor&Fran cis Gro up; p Hall III JW. ABR Analy sis and In ter pre ta ti on. New Hand bo ok of Au di tory Evo ked Res pon ses. 1 st ed. Bos ton: Allyn and Ba con; p Ho od lj. The nor mal au di tory bra ins tem res pon - se. Cli ni cal App li ca ti ons of ABR. 1 st ed. San-Di e - go-lon don: Sin gu lar Pub lis hing; p Don M, Kwong B. Au di tory bra ins tem res pon se: dif fe ren ti al di ag no sis. In: Katz J, ed. Hand bo ok of Cli ni cal Au di o logy. 5 th ed. Phi la delp hi a: lip pin cott Wil li ams & Wil kins; p Ji ang ZD, Zheng MS, Sun DK, li u XY. Bra ins - tem au di tory evo ked res pon ses from birth to adult ho od: nor ma ti ve da ta of la tency and in terval. He ar Res 1991;54(1): Gor ga MP, Ka mins ki JR, Be a uc ha i ne Kl, Jes te - adt W, Ne ely ST. Au di tory bra ins tem res pon ses from chil dren thre e months to thre e ye ars of age: nor mal pat terns of res pon se. II. J Spe ech He ar Res 1989;32(2): Is sa A, Ross HF. An im pro ved pro ce du re for asses sing ABR la tency in yo ung sub jects ba sed on a new nor ma ti ve da ta set. Int J Pe di atr otor hino lary ngol 1995;32(1): Wil kin son AR, Ji ang ZD. Bra ins tem au di tory evo - ked res pon se in ne o na tal ne u ro logy. Se min Fe - tal Ne o na tal Med 2006;11(6): Stoc kard JE, Stoc kard JJ, West mo re land BF, Cor fits Jl. Bra ins tem au di tory-evo ked res pon - ses. Nor mal va ri a ti on as a func ti on of sti mu lus and sub ject cha rac te ris tics. Arch Ne u rol 1979; 36(13): Hall III JW. Au di tory evo ked res pon se me a su rements prin ci ples. Hand bo ok of Au di tory Evo ked Res pon ses. 1 st ed. Bos ton: Allyn and Ba con; p Hall III JW, Swa ne po el DW. Au di tory bra ins tem res pon se. ob jec ti ve As sess ment of He a ring. 1 st ed. San Di e go: Plu ral Pub lis hing; p Gor ga MP, Re i land JK, Be a uc ha i ne KA, Wort - hing ton DW, Jes te adt W. Au di tory bra ins tem res pon ses from gra du a tes of an in ten si ve ca re nur sery: nor mal pat terns of res pon se. J Spe ech He ar Res 1987;30(3): Fri a TJ, Doy le WJ. Ma tu ra ti on of the au di tory bra in stem res pon se (ABR): ad di ti o nal pers pecti ves. Ear He ar 1984;5(6): Starr A, Am li e RN, Mar tin WH, San ders S. De ve - lop ment of au di tory func ti on in new born in fants re ve a led by au di tory bra ins tem po ten ti als. Pe diat rics 1977;60(6): Ja cob son JT, Mo re ho u se CR, John son MJ. Stra - te gi es for in fant au di tory bra in stem res pon se assess ment. Ear He ar 1982;3(5): He cox K, Ga lam bos R. Bra in stem au di tory evo - ked res pon ses in hu man in fants and adults. Arch oto lary ngol 1974;99(1): El dred ge l, Sa lamy A. Func ti o nal au di tory deve lop ment in pre term and full term in fants. Early Hum Dev 1996; 45(3): Zim mer man MC, Mor gan DE, Dub no JR. Au ditory bra in stem evo ked res pon se cha rac te ris tics in de ve lo ping in fants. Ann otol Rhi nol lary ngol 1987;96(3 Pt 1): Mu si ek FE, John son GD, Gol legly KM, Jo sey AF, Glass cock ME 3rd. The au di tory bra in stem res pon se in te ra u ral la tency dif fe ren ce (IlD) in pa ti ents with bra in stem le si ons. Ear He ar 1989; 10(2): Turkiye Klinikleri J Med Sci 2012;32(3)