www.bjorl.org
Brazilian
Journal
of
OTORHINOLARYNGOLOGY
ORIGINAL
ARTICLE
LS
CE-Chirp
®
vs.
Click
in
the
neuroaudiological
diagnosis
by
ABR
夽
Michelle
Cargnelutti
a,∗,
Pedro
Luis
Cóser
b,
Eliara
Pinto
Vieira
Biaggio
b,caUniversidadeFederaldeSantaMaria(UFSM),DistúrbiosdaComunicac¸ãoHumana,SantaMaria,RS,Brazil bClinicaCoserdeOtorrino,SantaMaria,RS,Brazil
cUniversidadeFederaldeSantaMaria(UFSM),SantaMaria,RS,Brazil
Received24December2015;accepted6April2016 Availableonline31May2016
KEYWORDS
Hearing;
Electrophysiology;
Auditorybrainstem
response
Abstract
Introduction:The chirpstimuluswas developedseekingtocounterbalance thedelayofthe soundwave onitsjourneythroughthecochlea, allowingthehair cellstodepolarizeatthe same time.Theresultis asimultaneous stimulation providingbetterneuralsynchronyand, consequently,therecordingofresponseswithgreateramplitudes.
Objective: TocomparetheabsolutelatencyofwavesI,IIIandV,theinterpeakintervalsI---III, III---VandI---V,amplitudevaluesofwave VanditsassociationwiththeamplitudeofwaveI, andtheinterauraldifferenceV---Vintheauditorybrainstemresponse(ABR)usingClickandLS CE-Chirp®stimulitodeterminewhethertheresponsesevokedbyLSCE-Chirp®couldbeapplied
toneuroaudiologicaldiagnosis.
Methods:Cross-sectionalstudywith30normal-hearingindividuals.Theparametersusedwere: intensityof85dBnHL,alternatingpolarity;17.1stimuli/sand100---3000Hzfilters.
Results:TheabsolutelatenciesofwavesI,IIIandVobservedwithLSCE-Chirp®andclickdidnot
showsignificantdifferences.SignificantlyhigheramplitudesofwaveVwereobservedwiththe LSCE-Chirp®.TheinterauraldifferencebetweenthewaveVlatenciesbetweenstimulishowed
nosignificantdifference.
Conclusion: TheLSCE-Chirp®stimuluswasshowntobeasefficientastheclicktocaptureABR
athighlevelsofstimulation,withtheadvantageofproducinggreater-amplitudeVwaves. © 2016 Publishedby Elsevier Editora Ltda. onbehalf of Associac¸˜ao Brasileira de Otorrino-laringologiaeCirurgiaC´ervico-Facial.ThisisanopenaccessarticleundertheCCBYlicense (http://creativecommons.org/licenses/by/4.0/).
夽
Pleasecitethisarticleas:CargneluttiM,CóserPL,BiaggioEP.LSCE-Chirp® vs.ClickintheneuroraudiologicaldiagnosisbyABR.BrazJ Otorhinolaryngol.2017;83:313---7.
∗Correspondingauthor.
E-mail:michellecargnelutti@gmail.com(M.Cargnelutti).
PeerReviewundertheresponsibilityofAssociac¸ãoBrasileiradeOtorrinolaringologiaeCirurgiaCérvico-Facial.
http://dx.doi.org/10.1016/j.bjorl.2016.04.018
PALAVRAS-CHAVE
Audic¸ão; Eletrofisiologia;
Potenciaisevocados
auditivos
LSCE-Chirp® vs.CliquenodiagnósticoneuroaudiológicopeloPEATE
Resumo
Introduc¸ão:O chirp foi desenvolvidobuscandocompensar oatraso da ondasonora em seu trajetopela cóclea,possibilitandoqueascélulas ciliadasdespolarizemaomesmotempo.O resultadoéumaestimulac¸ãosimultâneaproporcionandoumamelhorsincronianeurale conse-quentementeoregistroderespostasocorrecommaioresamplitudes.
Objetivo:CompararalatênciaabsolutadasondasI,IIIeV,osintervalosinterpicosI---III,III---Ve I---V,osvaloresdeamplitudedaondaVesuarelac¸ãocomaamplitudedaondaI,eadiferenc¸a interaural V---Vno PotencialEvocadoAuditivode TroncoEncefálico, utilizando osestímulos CliqueeLSCE-Chirp®,afimdedeterminarseasrespostasevocadasporLSCE-Chirp®poderiam
teraplicabilidadenodiagnósticoneuroaudiólogico.
Método: Estudotransversalcom30indivíduosnormo-ouvintes.Osparâmetrosutilizadosforam: intensidadede85dBnNA,polaridadealternada;17,1estímulo/sefiltrosde100---3000Hz.
Resultado:Aslatências absolutasdasondasI,IIIeV observadascomLSCE-Chirp® eclique
nãotiveramdiferenc¸assignificativas.AmplitudessignificativamentemaioresdaondaVforam observadascomoLSCE-Chirp®.A diferenc¸ainteraural entreaslatênciasdaondaV entreos
estímulos,nãomostroudiferenc¸asignificativa.
Conclusão:OestímuloLSCE-Chirp®mostrou-sesertãoeficientequantoocliquenacaptac¸ão
doPotencialEvocadoAuditivodeTroncoEncefálico,emníveiselevadosdeestimulac¸ão,coma vantagemdeproduzirondasVdemaioramplitude.
©2016Publicado porElsevier EditoraLtda.em nome deAssociac¸˜ao Brasileirade Otorrino-laringologia eCirurgiaC´ervico-Facial.Este ´eum artigo OpenAccess sobuma licenc¸aCC BY (http://creativecommons.org/licenses/by/4.0/).
Introduction
Theauditorybrainstemresponse(ABR)examinationrecords
responsesoftheneuralpathway,andisusefulinthe assess-mentof theauditory system integrity.It isclinically used toestimate hearingthresholds of adults and infants1 and
todetect nervous system disorders at the peripheral and
central level.2 It is historically recorded with a transient
clickstimuluswitharapidonsetandshortduration(100s).
The compositionof thisstimulus is broadband,with
max-imum peak power in the regions from 1000 to 4000Hz.3
Considering the cochlear tonotopy when the click
stimu-lusis presentedatthe cochlea,eachregionofthebasilar
membraneisstimulated,oneafteranother,fromthebase
to the apex. Thus, the transient stimulus stimulates the
high-frequencyregionearlier thanthose correspondingto
low frequencies. Because the low-frequency components
providedelayedresponsepeakstobeaddedtotheresponse
tohigh-frequencycomponents,muchinformationislostin
theoverallresponsesum.Therefore,theresultsofthe exci-tationofdifferentnervefibersatdifferenttimesdecreases theneuralsynchrony,whichisnecessarytoevokeahearing potential.4
Fromthis perspective, in orderto compensate for the
sound wave delay on its trajectory through the cochlea,
researchers have designed a stimulus which they named
chirp. This stimulus hasa duration upto10.33ms,which ismuchlongerthan theclick.It wasdesignedsothatlow
frequencies are presented before the high ones, so that
differentregions offrequencies reachtheir specific place
at thebasilar membrane simultaneously.Consequently, in
thisway,thecochlearneuralresponseismoresynchronized
andagreateramplitudeofwaveVisdisplayedattheABR
recording.4---6
Severalchirpmodelshavebeenproposedandtested,4,6---9
andoneoftheresearchers’aimsistofindthemostadequate stimulusforwaveVrecodingoftheABRatlowintensities.
Whenstudying7 severalchirpmodels,chirpresearchers
found that short-duration chirps were more effective at
highintensities andlong-durationchirpsweremore effec-tive at low intensities, and that the stimulus intensity is directlyrelatedtothewaveVamplitude.Giventhesefacts, ClausElberlingandhisgroupofresearchersconcludedthat
the CE-Chirp® model, based only onthe durationof time
required for the soundwave totravelthroughthe
differ-entcochlearfrequencyregions,isinadequatetogeneratea
robustABRresponseinadultswithnormalhearing.
There-fore,theyimprovedthestimulusdesignandcreatedamodel called‘‘directapproach’’.10Thisnewmodeltookinto
con-sideration the sound travel time in the cochlea and also
differentlevelsofintensity.UnliketheCE-Chirp®andothers thatprecededit,thisnewchirphasnofixeddurationatall intensities; itwascreatedwithvariabledurationforeach stimulusintensity,thuscomprisingtwentystimuliof differ-entdurationsthatchangeevery5dB.Thisnewstimuluswas calledlevelspecificCE-Chirp® (LSCE-Chirp®)andhasbeen
tested, purporting toovercomethe limitationsof the
CE-Chirp®,11 whichevokedonlyaverysmallwaveVamplitude
anddidnotallowtheidentificationofwavesIandIIIathigh stimulationintensities.
The few literature articles on this stimulus11,12 only
discussed its advantage in detecting wave V with high
amplitudeevenat high intensityand mentionedthat only
subjects. Therefore, we decided to measure the values of absolute latencies of waves I, III and V, the interpeak intervalsI---III,III---VandI---V,theamplitudevaluesof wave
V and its association with the amplitude of wave I, and
the V---V interaural difference in the auditory brainstem
response (ABR) using Click and LS CE-Chirp® stimuli to
determine whether thisnewstimulus couldbe appliedto
neuroaudiologicaldiagnosisbyABR.
Methods
Thiswasacross-sectionalstudywithadescriptivedesign,
associatedtoawiderprojectapprovedbytheethics
com-mitteeonhumanresearch,accordingtoopinionN.610506,
onApril8,2014,andCAAE14804714.2.0000.5346.Itshould benotedthatitfollowedResolutionN.66/12,whichdeals
with human research. All subjects were informed of the
studyaim,aswellastheproceduresinvolved andall
sub-jectssignedthefreeandinformedconsentform,agreeing
toparticipateinthisstudy.
Inclusion criteria were: individuals with no history of
otologicalor neurologicaldisease andaudiometric thresh-olds≤25dBHLfor the250---8000Hz frequencies.Thestudy included30individuals(18womenand12men)aged12---42 yearswithnormalhearing.
The ABR records with Click and LS CE-Chirp® stimuli
wereperformedusingtheEclipseEP25ABRsystem®
equip-ment, manufacturedby Interacoustics A/S, Denmark.The
parametersusedfortherecordingswere:alternating polar-ity, presentation rate of 17.1stimuli/s; passband filterof 100---3000Hz for the Click and LS CE-Chirp® stimuli,
10-millisecond (ms) window, stimulation using ER-3A insert
earphonesattheintensityof85dBnHL,withnoadditional filteringbeingmadeafterresponseacquisition.
The subjects were placed ona stretcher, so that they
were comfortably lying down. The electrode attachment
siteswerecleanedwithNuprepabrasivepasteandthe elec-trodeswereattachedtotheskin.Thereferenceelectrodes wereplacedontheright(A2)andleft(A1)mastoidsandthe
active (Fz) and ground (Fpz) electrodes on the forehead.
Therecordingonlystartedwithelectrodeimpedancebelow
3k.
TheABRrecordingwasmonaural,startingattherightear withtheClickstimulusand,afterthat, therecordingwas performed in theleftear. Subsequently,theLS CE-Chirp® stimuluswasused,alsostartingwiththerightearandfinally, intheleftear.
The recordingwasinterruptedwithaminimumof1000
stimuliandtheduplicationofeachrecordwascarriedout toensurethereproducibilityandreliabilityofthewaves.
Thepresence/absenceofwavesI,IIIandVwasanalyzed,
comparing theabsolute latency values of waves I, III and
V;amplitude valuesof waveV andwave Iandthe values
ofinterpeaklatencies (IPLs) I---III,III---V,I---Vandthe inter-auraldifference V---V between theLS CE-Chirp® and click stimuli.
Tocomparethelatencyandamplitudevariablesbetween
thestimuli,Student’sttestwasusedforindependent sam-ples.At theanalysisofthevariablesinterauraldifference V---V andV/I ratio,the Mann---WhitneyUtest wasusedto comparetheclickandLSCE-Chirp®stimuli.
Table1 Descriptivestatisticsfortheabsolutelatenciesof wavesI,IIIandVofABRwithClickandLSCE-Chirp®stimuli,
at85dBnHLinnormalhearingadults(n=60).
Variables Stimuli p-Value
Click LSCE-Chirp®
WaveI 1.29(±0.09) 1.29(±0.13) 0.921
WaveIII 3.42(±0.15) 3.42(±0.18) 0.978
WaveV 5.27(±0.18) 5.19(±0.24) 0.885
ABR, auditorybrainstemresponse; dBnHL,decibelfor normal hearinglevel.
Table 2 Descriptive statistics for I---III, III---V and I---V interpeaklatenciesofABRbetweenClickandLSCE-Chirp®
stimuliat85dBnHLinnormalhearingadults(n=60).
Variables Stimuli
Click LSCE-Chirp®
Mean(SD) Mean(SD)
I---III 2.13(±0.14) 2.13(±0.14)
III---V 1.85(±0.18) 1.77(±0.22)
I---V 3.98(±0.21) 3.90(±0.25)
ABR, auditorybrainstemresponse; dBnHL,decibelfor normal hearinglevel;SD,standarddeviation.
Forall analyses, the significance level wasset at 0.05
(5%)andconfidenceintervalswerebuiltwith95%statistical
confidence.
Results
When comparing the results of the absolute latencies of
waves I, III and V and the amplitude of wave V between
therightandleftears,itwasobservedthatthedifferences
betweentheearswerenotsignificantforbothClickandLS
CE-Chirp®stimuli.Thus,thevaluesofbothearswerealways
consideredfordataanalysis,doublingthesamplesize.
Table1 comparesthe absolutelatencies of waves I,III
and V between the stimuli, at an intensity of 85dBHL,
withnostatisticallysignificantdifferenceinthecomparison betweentheClickandLSCE-Chirp® stimuli.
ThemeanvaluesofInterpeaklatenciesI---III,III---VandI---V forthestimuliusedinthisstudyareshowninTable2.
Table3shows thatattheintensity assessed,85dBnHL,
the amplitude of wave V in ABR recordings with the LS
CE-Chirp® stimuluswasgreater thantheamplitude ofthe
Table3 DescriptivestatisticsforwaveVamplitudeatABR withClickandLSCE-Chirp® stimuli,at85dBnHLinnormal
hearingadults.
Stimuli p-Value
Click LSCE-Chirp®
WaveVamplitude 0.50(±0.19) 0.61(±0.23) 0.004
Right ear
Click Click
I I
I
III III
III
III
III
III
LS CE-Chirp LS CE-Chirp
I I
0 2 4 6 8 0 2 4 6 8 10
I
I V
V
I
III
III V
V
V
V V
V
Left ear
Figure1 ExampleofABRrecordingwithClickandLSCE-Chirp® stimuliinonesubject.Observethemuchhigheramplitudeof
waveVinresponsetotheLSCE-Chirp®andsimilarlatenciesinresponsetoClickandLSCE-Chirp®onbothsides.
Table4 DescriptivestatisticsfortheV/IratioofABRwith ClickandLSCE-Chirp®stimuli,at85dBnHLinnormalhearing
adults.
Stimuli p-Value
Click LSCE-Chirp®
V/Iratio 1.63(±1.3) 2.07(±1.3) 0.004
ABR,auditorybrainstemresponse; dBnHL,decibelfor normal hearinglevel.
recordingswiththeclickstimulus,withasignificant differ-ence.
When comparing the amplitude values of V/I ratio
betweenthe stimuli,statistically significant higher values
wereelicitedbytheLSCE-Chirp®stimulus(Table4).
Table5showsthatnostatisticallysignificantdifference
wasobserved when comparingthe interaural latencies of
waveVbetweenthestimuliusedinthisstudy.
Accordingtotheresultsobtainedinthisstudy,itis
sug-gested that the values shown in Table 6 can be used as
maximumvaluesofnormality(meanvalueplus2standard
deviations) for neuroaudiological diagnosis, for both the
clickandtheLSCE-Chirp®stimuli,presentedat85dBnHL.
Table5 DescriptivestatisticsbetweenV---VbetweenClick andLSCE-Chirp®stimuliatABR,at85dBnHLinnormal
hear-ingadults.
Stimuli p-Value
Click LSCE-Chirp®
MeanSD MeanSD
V---V 0.08(±0.09) 0.10(±0.09) 0.273
ABR,auditorybrainstemresponse; dBnHL,decibelfor normal hearinglevel;Sd,standarddeviation.
Table6 Maximumvaluesforabsolutewaveandinterpeak latencies ofABRfor neuroaudiologicaldiagnosis withboth stimuli---ClickandLSCE-Chirp®,at85dBnHL.
Latencies WaveI WaveIII WaveV
1.55ms 3.79ms 5.67ms
Intervals I---V I---III III---V V---V
4.40ms 2.40ms 2.20ms 0.28ms
ABR,auditorybrainstemresponse;dBnHL, decibelfornormal hearinglevel;ms,milliseconds.
Fig.1 shows theABR recordingsregisteredwiththe LS
CE-Chirp® andclickstimuliinoneofthestudysubjects.
Discussion
This study showed that in all ABR recordings the waves
I, III and V were identified both with Click and LS
CE-Chirp® stimuli, at astimulation level of85dBHL.Another
study12 recorded ABR in normal-hearing adults, using the
stimuli: Click, CE-Chirp® and LS CE-Chirp®, and observed
that at 80dBnHL, all peaks of waves I, III and V were
identified when using the Click and LS CE-Chirp® stimuli. WhenusingtheCE-Chirp®stimulusatthisstimulationlevel,
wave I was not observed in any of the records, wave III
appearedin35%andwaveVin90%ofrecordings.Another
investigation13 comparedABR records using click and
CE-Chirp® innormal-hearingadults.Theresearchersanalyzed thepresence/absenceofwavesI,IIIandVat80dBnHLand
concluded that waves I andIII tended todisappear when
However,inastudy recordingABR at80dBnHL,waveV
latencies werelonger for theLS CE-Chirp® stimulus when
comparedtoClick.Accordingtothestudyresearchers,this resultwasdue tothefactthat inthe LS CE-Chirp®,most
frequencycomponents,reachthecochlea1.5mslaterthan
thecorresponding componentsinthe Clickand, thus, the
latency at ABRwiththe LS CE-Chirp® stimulus washigher
whencomparedtoClick.12
However,thecommercialversionofLSCE-Chirp®,when
using the Eclipse EP25 ABR system® equipment
manufac-turedbyInteracoustics, changedthewayLS CE-Chirp®,is presented,usingaspointzeroofthestimulusthelocationof thechirpcorrespondingtothe2500Hzfrequency,insteadof thelocationofthefinalfrequencyof10,000HzoftheLS CE-Chirp® usedinresearch.Thischangeresultedinresponses withlatenciesequaltothoseobtainedwiththeclickinits severalintensities.RegardingtheamplitudeofwaveV,we foundsignificantlyhighervaluesintherecordingswiththe LSCE-Chirp® stimulus.Theseresults areconsistent witha
studythatcomparedtheamplitudebetween LSCE-Chirp®
and Click and concluded that the LS CE-Chirp® stimulus
in ABR recordingsprovides significantly higheramplitudes
when compared to Click, at higher levels of stimulation
(80dBnHL).12
The current study corroboratesseveral studies4,13 that
alsoobservedahigherresponsetowaveVamplitudewhen
usingthechirpstimulusinABRrecordingsinnormal-hearing adults.
ItisworthmentioningthatstudiesusingtheLSCE-Chirp®
stimulus are carried out in individuals with cochlear and
retrocochlearpathologytobetterassesstheircontributions toclinicalpractice.
Conclusion
The LS-CE Chirp® stimulus is as efficient as the click in
obtaining waves I, III and V of the auditory brainstem
response test, at high levelsof stimulation. This stimulus maybeusefulinneuroaudiologicaldiagnosisbecauseunlike CE-Chirp®thatmostofthetimeevokesonlywavesIIIandV, theLS-CEChirp®stimulusevokesthethreewavesneededfor thistypeofdiagnosis,withtheaddedadvantagethatwave
Vhasgreateramplitudethanwhenevokedbytheclick.
Conflicts
of
interest
Theauthorsdeclarenoconflictsofinterest.
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