tudy of cochlear microphonic potentials in auditoryeuropathy�
lka do Amaral Soaresa,b,∗, Pedro de Lemos Menezesb,c,line Tenório Lins Carnaúbaa, Kelly Cristina Lira de Andradea, Otávio Gomes Linsd,e
Universidade Federal de São Paulo (UNIFESP), Ciências Médicas, São Paulo, SP, BrazilUniversidade Estadual de Ciências da Saúde de Alagoas, Maceió, AL, BrazilUniversidade de São Paulo (USP), São Paulo, SP, BrazilUniversidade Federal de São Paulo (UNIFESP), São Paulo, SP, BrazilUniversidade Federal de Pernambuco (UFPE), Recife, PE, Brazil
eceived 20 August 2015; accepted 29 November 2015vailable online 27 April 2016
KEYWORDSCochlearmicrophonic;Cochlear microphonicpotential;Hearing loss
AbstractIntroduction: Auditory Neuropathy/Dyssynchrony is a disorder characterized by the presence ofOtoacoustic Emissions and Cochlear Microphonic Potentials, an absence or severe alteration ofBrainstem Evoked Auditory Potential, auditory thresholds incompatible with speech thresholdsand altered acoustic reflexes. The study of the Cochlear Microphonic Potential appears to bethe most important tool for an accurate diagnosis of this pathology.Objective: Determine the characteristics of the Cochlear Microphonic in Auditory Neurop-athy/Dyssynchrony using an integrative review.Methods: Bibliographic survey of Pubmed and Bireme platforms and MedLine, LILACS and Sci-ELO data banks, with standardized searches up to July 2014, using keywords. Criteria wereestablished for the selection and assessment of the scientific studies surveyed, considering thefollowing aspects: author, year/place, degree of recommendation/level of scientific evidence,objective, sample, age range, mean age, tests, results and conclusion.Results: Of the 1959 articles found, 1914 were excluded for the title, 20 for the abstract, 9 for
the text of the article, 2 for being repeated and 14 were selected for the study.Conclusion: The presence of the Cochlear Microphonic is a determining finding in the differ-ential diagnosis of Auditory Neuropathy/Dyssynchrony. The protocol for the determination ofCochlear Microphonic must include the use of insert earphones, reverse polarity and blocking
� Please cite this article as: Soares IA, Menezes PL, Carnaúba AT, de Andrade KC, Lins OG. Study of cochlear microphonic potentials inuditory neuropathy. Braz J Otorhinolaryngol. 2016;82:722---36.∗ Corresponding author.
The term auditory neuropathy (AN) was first used in 1996to define a group of individuals with auditory symptoms,who had in common normal cochlear function despite havingabnormal cochlear nerve function. Moreover, they experi-enced difficulty in understanding speech especially in noisyenvironments, although in some cases they responded tosound stimuli.1 Today the most common denomination isauditory neuropathy/dyssynchrony (AN/AD).
In general findings reveal the absence or severe abnor-mality of the Auditory Brainstem Response (ABR) withpreservation of the otoacoustic emissions (OAE) and/or theCochlear Microphonic (CM), indicating disordered functionof the auditory nerve with normal function of the cochlear
1---4
hair cells (HC).It is often difficult to determine exactly the onset
of AN/AD, but the disease can occur at all ages.4 Itsprevalence has been estimated at 11% in a group of 109
tdb
earing-impaired children who failed the newborn hearingcreening (NHS) and ABR.5 Another study reports a simi-ar prevalence of 8.44% in 379 children evaluated with ABRlteration.4
The CM is a potential generated from the outer hairells (OHC) and inner hair cells (IHC) of the cochlea andts absence is consistent with alterations in the functionf these cells.2,6 It is an electrical activity that precedeshe synapses of the HC with the auditory nerve and, there-ore, when recorded, it appears before wave I on ABR andaintains its latency even when the stimulus intensity isecreased.5
There are still no available data regarding CM parame-ers in individuals with normal hearing or with hearing loss.owever, recording the CM attracted renewed interest afterhe identification of the AN/AD,1 as the association between
he cochlea and an acoustic stimulation has been used in theifferential diagnosis of AN/AD, once the presence of CM cane used as evidence of OHC integrity.7
The literature recommends that tests of cochlear func-ion, particularly CM, become part of the NHS (Newbornearing Screening) protocol in all children with absent orltered ABR, facilitating the diagnosis of AN/AD.5
The aim of the study is to verify the character-stics of cochlear microphonism in Auditory Neurop-thy/Dyssynchrony through an integrative review.
ethods
he methodological process characterized the present studys an integrative review, to gather data from studies thatelp the understanding of the subject in a systematic andrderly manner, thus helping to acquire further knowledgen Cochlear Microphonic characteristics in Auditory Neurop-thy/Dyssynchrony.
The integrative review was carried out from electronicearches in Pubmed and Bireme platforms and in the fol-owing databases: MedLine, LILACS and SciELO --- Regional.he data search was started and concluded in July 2014.tudies published in English, Spanish or Portuguese wereelected for the analysis. There was no restriction regardinghe year of publication, i.e. studies published up to July 2014ere analyzed, and subsequently, the articles were selectedccording to inclusion and exclusion criteria.
The search strategy was performed by crossing theescriptors (DeCS and MeSH), as well as the free terms,hich are terms not found in MeSH and MeSH, but thatre relevant to the search. The descriptors used to locatehe studies were Cochlear Microphonic and Cochlear Micro-honic Potential and the free terms used were Auditoryeuropathy and Auditory Dyssynchrony.
earch strategy
he search strategy was directed by a specific question:‘What are the characteristics of the Cochlear Microphonicn Auditory Neuropathy/Dyssynchrony?’’. Aiming to iden-ify the relevant articles with the proposed question,
search strategy was developed, using the descriptorsn groups, with at least two keywords. The descriptorssed were: Cochlear Microphonic/Auditory Neurop-thy/Auditory Dyssynchrony/Cochlear Microphonic ANDuditory Neuropathy OR Auditory Dyssynchrony/Cochlearicrophonic Potential/Auditory Neuropathy/Auditoryyssynchrony/Cochlear Microphonic Potential AND Auditoryeuropathy OR Auditory Dyssynchrony.
election criteria
nclusion criteriarticles with the following characteristics were included:riginal article, case report or literature review including asesearch subjects individuals diagnosed with auditory neu-opathy.
xclusion criteriahe articles that did not describe the findings of audiologicalssessment in individuals with AN/AD were excluded fromhis review.
Dt1
Soares IA et al.
tudy identification, selection and inclusion
he study was independently carried out by two researchersnd the points of conflict were discussed at specific meet-ngs. After applying the search strategy containing theefined descriptors, article selection was performed in threetages:
. Identification and reading of titles in different electronicdatabases. Articles that clearly did not meet any of theinclusion criteria of this study were excluded.
. Reading of summaries of the studies selected at the firststage. Similarly, we excluded articles that clearly did notmeet any of the pre-established inclusion criteria.
. All studies that were not excluded in these first twostages were read in full for the selection of those thatwould be included in this review.
All studies used met the inclusion criteria defined inhe beginning of the methodological protocol of this study,iming to answer the question that guided this integrativeeview. The main data of each article were fully collectednd entered into a Microsoft Office Excel 2011 programatabase.
For better presentation of the results, it was decidedo consider the following variables of the selected articles:uthor, year/location, type of study, grade of recommen-ation/level of scientific evidence, objective, sample, ageange, mean age in years, tests performed, results andonclusion.
As for the level of scientific evidence, the classifica-ion used was that of Oxford Center for Evidence-Basededicine.8
esults
ccording to the performed search, 1959 articles were foundn the electronic searches. According to the inclusion andxclusion criteria defined in the method and after elim-nating the repeated references found in more than oneatabase, 14 articles were selected.
In the MedLine database, via PubMed, after employinghe keywords and free terms, 1959 articles were found,f which 1913 were excluded after reading the title, 44bstracts were read and 25 articles were selected for read-ng in full. Of these 25, two were repeated articles and nineere excluded. In the LILACS and MEDLINE databases viaireme, no articles were found for this search. Two articlesere found in the SciELO database; one was excluded after
eading the title and the other was excluded after beingead in full.
The following flow chart (Fig. 1) is a synthesis of therticle selection process for the integrative review.
Table 1 is a synthesis with the characteristics of the stud-es included in the integrative review.
iscussion
ue to the recent increase in the number of studies on AN,his review shows that most studies were published between996 and 2014. All selected articles associated AN with the
Study of
cochlear m
icrophonic potentials
in auditory
neuropathy
725
Table 1 Summary with characteristics of the studies included in the review.
Author Year/place Study type Grade of recom-mendation/levelof scientificevidence
Objective Sample Are range inyears
Mean age inyears
Tests Results Conclusion
Deltenreet al.
1997/Belgium Case study C/4 Describe a newform of hearingdysfunctioncharacterized byabsent ABR, withevidence offunction of theouter hair cellsof the cochlea,the cochlearmicrophonicpotential andpreserved OAE
3 0---4 months Notreported
ABR (clipped),OAE, acousticimmittancetesting
OAE present,absent ABR withthe presence ofCM, residualhearing in onecase inBehavioralAudiometry,normaltympanogramandcontralateralacousticreflexes present
OAE and ABRalone mayindicate anunusualsituation, but theverification onlyoccurs with therecording of CM.Recognition ofthe microphonicpotential isolatedfrom routinerecordingsfacilitated by theuse of reversepolarity can bevaluable for theneuro-physiologicalevaluation ofperipheralhearing and thus,it is highlyrecommended.
Santarelliand Arslan
2002/Italy Case study C/4 Describe thefindings of theECoG in 5patients, oneadult and fourchildren, withabsent ABR andpresence ofDPOAE
Not applicable Pure auditoryneuropathy israre, in manycases, both the8th nerve andcentral auditorypathway or, insome cases, CCcontribute toatypical hearingloss and speechrecognition
The term AN isnot adequate forcases in whichthe pathology ispredominantly inthe brainstemand should bereserved forpatients withevidence that thedisease involvesthe spiralganglion cellsand their axons
Berlin et al. 2003/USA Literaturereview
D5 Study of ANdiagnosis andmanagement
Notapplicable
Notapplicable
Notapplicable
Not applicable Studiesperformed inthe last 20 yearsshow thatalthough theelectroacousticevaluation canprovide gooddiagnosis, theseresponses areproducts of acomplexphysiologicalprocess and arenot necessarilythe trueperceptionindicators
The attempts tocharacterizeseveral aspectsof the AN profilehave shown thatthe resultsdemonstrate acommonphysiologicalpattern due todifferentpathologicalprocesses, ordifferent degreesof involvement
Study of
cochlear m
icrophonic potentials
in auditory
neuropathy
727
Table 1 (Continued)
Author Year/place Study type Grade of recom-mendation/levelof scientificevidence
Objective Sample Are range inyears
Mean age inyears
Tests Results Conclusion
Rance 2005/Australia Literaturereview
D5 Studying themechanisms ofAN, type ofdisorder, clinicalprofile ofpatients andmainly theeffects of theperception ofAN, which arequite differentfrom thoseassociated withSNHL
The results showthat in allpatients,amplitude andCM thresholdare criticallydependent onthe CAPthreshold,showing anassociation ofCM with bothOHC and IHC
The presence ofa CNS disorderseems to improvethe CMamplitude. Insome cases, thedisappearanceover time ofDPOAE suggeststhat changes inthe amplitudeand duration ofCM in patientswith AN, resultfrom acombination ofloss of OHC andalterations in theefferent system
728
Soares IA
et al.
Table 1 (Continued)
Author Year/place Study type Grade of recom-mendation/levelof scientificevidence
Objective Sample Are range inyears
Mean age inyears
Tests Results Conclusion
Santarelliet al.
2006/Italy ObservationalCross-sectional
C4 Evaluate theamplitude of theCM and thehearingthreshold ofnormal ears andears with varyingdegrees ofelevation in therecording of theAction Potentialand comparewith thecorrespondingvalues in a groupof patients withAN
522 7 months to47 years
3.1 years Pure tone andvocalaudiometry,acousticimmittancetesting, OAEand ABR
The CMamplitude wassignificantlyhigher inpatients withCNS diseasethan in thosewith normalhearing. CMresponses weredetected in allauditorypatients withAN, withamplitudes andthresholdssimilar to thosecalculated forindividuals withnormal hearing.The duration ofthe CM wassignificantlyhigher in thegroup with AN
1. CM detectionis not adistinctivecharacteristic ofAN; 2. Patientswith CNS diseaseshowed anincrease inamplitude andduration of CM,possibly due tothe efferentsystemdysfunction;The duration,high frequencyand amplitude ofthe CM weresimilar inpatients withnormal hearingand AN. This mayresult from avariablecombination ofthe type ofefferent systemlesion and loss ofOHC
Anastasioet al.
2008/Brazil Case report D5 Demonstrate theclinicalapplicability ofEcogET in thedifferentialdiagnosis of ANwhen comparedto ABR
1 4 years Notapplicable
OAE, ABR click,ABR 0.5 and1 kHz tone pipsand imagingtest
A 4-year-oldchild, diagnosedwith ANunderwent theEcog-ET with2000 Hz toneburst inrarefaction andcondensationpolarities
Ecog-ET alloweda more detailedanalysis of CMcompared to theABR, thusshowing clinicalapplicability forthe investigationof cochlearfunction in AN
Study of
cochlear m
icrophonic potentials
in auditory
neuropathy
729
Table 1 (Continued)
Author Year/place Study type Grade of recom-mendation/levelof scientificevidence
Objective Sample Are range inyears
Mean age inyears
Tests Results Conclusion
Ahmmedet al.
2008/UnitedKingdom
Case report C4 Study thediagnosticdilemma aboutthe presence ofCM together witha significantincrease in ABRthresholds ininfants who failat NHS
1 6 weeks Notapplicable
TOAE, Ecog,ABR by click,by BC andToneburst (500,1000 and2000 Hz)
SNHL diagnosedthrough clinicaland familyhistory, physicalexamination andimaging teststhat showedenlargedvestibularaqueducts.Presence of CMin the presenceof very highthresholds in theABR click andthe obtaining ofthresholds forand in ABR tonepip 0.5 kHz maynot be adequateto differentiatebetween SNHLand otherconditionsassociated withAN
There is a needto review theNHS/AN protocolused in the UKand a new studyto establishparameters toaid in thedifferentialdiagnosis of CM.A holistic andaudiologicalmedicalapproach isessential tomanage infantswho fail at theNHS
730
Soares IA
et al.
Table 1 (Continued)
Author Year/place Study type Grade of recom-mendation/levelof scientificevidence
Objective Sample Are range inyears
Mean age inyears
Tests Results Conclusion
Riazi andFerraro
2008/USA Case reports C4 To evaluatetechniques thatcan optimize therecording of CMin humans.Through avariety ofstimulusparameters andshieldingconditions aimedat inhibit-ing/reducingartifacts thatcan contaminatethe CM
11 7 childrenand 4 adults
Notreported
TOAE, Ecog,ABR, by clickand toneburst(500, 1000 and2000 Hz)
The resultssuggest that it iseasier toseparate the CMof the artifactfrom thestimulus usingan electrode inthe auditorycanal andtoneburststimuli.Additionally,electromagneticshielding andgrounding of thepower cablesand the acoustictransducer wereeffective inreducing and/oreliminating thestimulus artifact
The results ofthis normativestudy may helpimprove thediagnosis of CMin AN and otherhearing-relateddisorders
Talaat et al. 2009/Egypt PrevalenceStudy
B2B Detect theprevalence of ANin children andyoung individualswith severe toprofound hearingloss
15 patientswere diagnosedaccording to ourdiagnosticcriteria
The prevalenceof AN in the studygroup was 13.4%.We recommendthe CM recordingto be routinelytested during theevaluation of ABRwhenever theresults obtainedare altered
Study of
cochlear m
icrophonic potentials
in auditory
neuropathy
731
Table 1 (Continued)
Author Year/place Study type Grade of recom-mendation/levelof scientificevidence
Objective Sample Are range inyears
Mean age inyears
Tests Results Conclusion
Mo et al. 2010/China ObservationalCross-sectional
C4 Describe theaudiologicalfindings of AN
48 6---58 months Notreported
Behavioralaudiometry,DPOAE, ABR byclick andacousticimmittancetest
There were 40children with abilateral ANprofile and 8unilateral cases;in thecontralateralears of thesecases, therewere 3 ears withABR thresholdsthat were betterthan 30 dB NHL,which indicatesnormal auditoryfunction, and 5with absent orseverely alteredABR. Inaddition, fourchildren werediagnosed withAuditory NerveDisabilities afterfurtherinvestigationthrough innerear magneticresonanceimaging
The audiologicalresults in thisgroup of childrenshow variabilityin relation to theABR thresholdsand the wavemorphology, thebehavioralthresholds andpresence of CMand DPOAE. Thismay reflect theheterogeneousnature of the AN.Additionally,concomitantpathologies ofthe inner ear orfrom the middleear disordersmay disclose AN.Absent orseverely alteredABR togetherwith thepresence of CMare the mostreliable measuresto detect AN
732
Soares IA
et al.
Table 1 (Continued)
Author Year/place Study type Grade of recom-mendation/levelof scientificevidence
Objective Sample Are range inyears
Mean age inyears
Tests Results Conclusion
Shi et al. 2012/China ObservationalCross-sectional
C4 Investigate thecharacteristicsand clinicalsignificance ofCM in thediagnosis of ANin infants andchildren
36 3 months to 9years
3 years Behavioralaudiometry,DPOAE, ABR byclick andacousticimmittancetesting
There was nosignificantdifference inthe length oramplitude of CMbetween thegroup with ANand the groupwith normalhearing. But theamplitudes ofthe CM with ANand absentDPOAE weresignificantlylower than inindividuals withnormal hearing
The CM may bevery important inthe diagnosis ofAN. Themaximumamplitudes of theCM were alwaysfound at around0.6 ms. It is moreuseful for thediagnosis of ANto analyze thepatterns of CMamplitudes andfunctions of OHCand IHC together
Study of
cochlear m
icrophonic potentials
in auditory
neuropathy
733
Table 1 (Continued)
Author Year/place Study type Grade of recom-mendation/levelof scientificevidence
Objective Sample Are range inyears
Mean age inyears
Tests Results Conclusion
Liu et al. 2012/China Retrospectivecross-sectionalcohort
C4 Explore apossiblecorrelationbetweencochlear nerveimpairment andunilateral AN
85 2---23 years Notreported
Pure toneaudiometry,DPOAE, TOAE,ABR by clickand acousticimmittancetesting
Eight cases werediagnosed withunilateral ANcaused bycochlear nerveimpairment. 7had a type ‘‘A’’tympanogramwith normalbilateral OAE;the last one hadunilateral type‘‘B’’,tympanogram,absent OAE andpresent CM,according toalterations inthe middle ear.ABR was absentin all patientsand neuronalresponses fromthe cochleawere notdisclosed whenviewed bymagneticresonanceimaging of theinternalauditory canal
The cochlearnerveimpairment canbe seen by elec-trophysiologicalevidence andmay be animportant causeof unilateral AN.Magneticresonanceimaging of theinternal auditorycanal isrecommendedfor the diagnosisof this disease
734
Soares IA
et al.
Table 1 (Continued)
Author Year/place Study type Grade of recom-mendation/levelof scientificevidence
Objective Sample Are range inyears
Mean age inyears
Tests Results Conclusion
Penido andIssac
2013/Brazil Cohort study C4 Determine theprevalence of ANin individualswith SNHL
2292 0---95 years Notreported
Pure tone andvocalaudiometry;acousticimmittancetesting; OAE;ABR and CM
1.2% had AN. Ofthese, 29.6%had mild SNHL;55.5%moderate; 7.4%severe and 7.5%profound. 14.8%were aged 0---20years; 33.4%were 21---40years; 44.4%were 41---60years and 7.4%were older than60 years
The prevalenceof AN was 1.2% inindividuals withSNHL
Study of cochlear microphonic potentials in auditory neuropathy
Total de artigosencontrados =
1959
Pubmed = 1957 LILACS emedline = 0
SciELO = 2
Excluídos pela leiturado título = 1914
Selecionadospela leitura
do título = 45
Selecionadospela leitura
do resumo = 45
Selecionadospela leitura
do artigo paraa revisão = 14
Excluídos pela leiturado artigo = 9
Artigos repetidos = 2
Excluídos pela leiturado resumo = 20
AtlccTTpoiipt
td
srFacoabcpe
ntsatmspa
ehttwmriw
Awdcwp
rd
Figure 1 Flowchart of articles identified, excluded andincluded in the integrative review.
MC recording through two specific tests, ABR and the Ecog,using invasive or non-invasive methods, in addition to othertests to assess auditory function.
There was greater investment in research in this areain the late 90s, when AN was described.1 Since then, stud-ies have sought to explain the location of the lesion, riskfactors, prevalence and more accurate diagnostic tests inAN.
Regarding location, the literature indicates a broad pos-sibility, as the lesion may occur in several structures or inmore than one at the same time, such as the IHC, auditorynerve fibers, or in their synapses.9 Another study suggeststhat there is an abnormality in the auditory system, locatedin the VIII nerve, ganglion neurons, in the IHC, between theirsynapses or a combination of them.1
Risk factors are usually associated to neonatal problemssuch as prematurity, low birth weight, anoxia, hypoxia,hyperbilirubinemia, need for mechanical ventilation andintracranial hemorrhage,10 as well as genetic and mito-chondrial disorders11 and a family history of hearingdisorders.3,12
According to the studies shown in this review, the preva-lence of AN in children and young individuals with severeto profound hearing loss was 13.4%9 and 1.2% in individualswith SNHL.13 The prevalence has also been described in chil-dren with risk criteria for AN as 1 in 433 (0.23%) and in thegroup of children with permanent hearing deficit, it was 1 in9 (11.01%).5 Another study indicates a prevalence of 8.44%
4
in a group of 379 children with ABR alteration.There is an agreement in the reviewed literature
regarding examination findings in patients with neuropathy,who have present OAE and CM, absent or very altered
dp
c
735
BR and absent acoustical reflexes.9,10,12---23 In audiometry,he described pattern is permanent or fluctuating hearingoss of varying degrees, with flat or ascending audiometriconfigurations,12,17 in addition to difficulties in speech per-eption, especially in the presence of noise.9,10,12,14---17,22,23
he OAE are present, but they may disappear with time.16
he results of objective electrophysiological tests such asresence of TOAE, absent or very altered ABR and presencef CM have emerged as the first diagnostic tool for AN innfants.4,24 Additionally, patients with AN have an alterationn OAE suppression effect caused by the efferent auditoryathways.25 The absence of OAE suppression suggests thathe olivocochlear efferent function is altered.24
Considering the findings of the auditory function tests,he presence of CM becomes the determinant finding in theifferential diagnosis of AN.16
The protocol used to record the CM by ECoG or ABRhould always reverse the stimulus polarities to confirm theecording inversion and, therefore, confirm CM.13,16,17,19,22
urthermore, the use of insert earphones is important tollow the blocking of the plastic tube, indispensable toonfirm the biological response, discarding the presencef electrical signal artifact.13,17,20 Insert earphones shouldlways be used in the ABR to allow stimulus artifacts toe separated from cochlear potentials.2 Another study alsoonfirmed the CM response by closing the stimulus tube torevent the acoustic signal from reaching the ear canal,liminating the artifacts.5
Some studies have reported the use of Ecog as a diag-ostic test for AN. But there are reports suggesting thathe Transtympanic Electrocochleography (EcogT) is the goldtandard tool to evaluate CM,9,16,17 because Ecog allows
more detailed analysis of cochlear function in relationo ABR.9,17 However, promontory recordings are consideredore sensitive than the ear canal and that results in a better
ignal-to-noise ratio, as the CM comes first from the basalortions of the cochlea, with a negligible contribution of thepical regions.7
In one of the reviewed studies, no significant differ-nce was found between the amplitude of the CM in normalearing individuals and those with AN. The maximum ampli-udes of CM for almost all patients were around 0.6 ms afterhe stimulus.13 The literature reports that CM in patientsith AN are especially prominent and persist for severalilliseconds after a transient stimulus.2,24 Another study
eported that the mean amplitudes of the CM was 0.4 msn patients with AN, significantly higher than in individualsith normal hearing.24
The duration of the CM was longer in the group withN than in the group with normal hearing.13,16 In patientsith AN in the ABR, the CM appears wide and can exhibit auration of up to 4---6 ms, and may be mistaken for electri-al activity of the brain stem; however it does not changeith decreasing intensity, but with the reversed stimulusolarity.25
In general, the assessed literature agrees on the location,isk factors and clinical findings of AN and reports that itsifferential diagnosis is confirmed based on the CM recor-ing, because even at an advanced state of AN, CM remains
resent.
This review includes studies that describe the tests mostommonly used to describe the characteristics of Cochlear
7
Mtmhi
C
Bc
C
T
R
1
1
1
1
1
1
1
1
1
1
2
2
2
2
2
36
icrophonism in Auditory Neuropathy/Dyssynchrony. Forhat purpose, several types of studies were selected, whichay seem like a limitation, but on the other hand, they may
ave different perspectives on the subject, always takingnto account the previously defined selection criteria.
onclusion
ased on the studies included in this literature review, weonclude that:
The presence of the CM is a crucial finding in the differen-tial diagnosis of AN.The CM recording protocol must include the use of insertearphones and reverse polarity and the stimulus blockingto prevent electrical artifact interference.The amplitude of CM in AN showed no significant differencewhen compared with the amplitude of CM in individualswith normal hearing.The duration of CM is longer in individuals with AN.
onflicts of interest
he authors declare no conflicts of interest.
eferences
1. Starr A, Picton TW, Sininger Y, Hood LJ, Berlin CI. Auditory neu-ropathy. Brain. 1996;119:741---53.
2. Berlin CI, Bordelon J, St John P, Wilensky D, Hurley A, Kluka E,et al. Reversing click polarity may uncover auditory neuropathyin infants. Ear Hear. 1998;19:37---47.
3. Madden C, Rutter M, Hilbert L, Greinwald JH Jr, Choo DI.Clinical and audiological features in auditory neuropathy. ArchOtolaryngol Neck Surg. 2002;128:1026---30.
4. Foerst A, Beutner D, Lang-Roth R, Huttenbrink KB, Von Wedel H,Walger M. Prevalence of auditory neuropathy/synaptopathy in apopulation of children with profound hearing loss. Int J PediatrOtorhinolaryngol. 2006;70:1415---22.
5. Rance G, Beer D, Cone-Wesson B. Clinical findings for a group ofinfants and young children with auditory neuropathy. Ear Hear.1999;20:238---52.
6. Dallos P, Cheatham MA. Production of cochlear potentials byinner and out hair cells. J Acoust Soc Am. 1976;60:510---2.
7. Withnell RH. Brief report: the cochlear microphonic as an indi-cation of outer hair cell function. Ear Hear. 2001;22:75---7.
8. Oxford Centre for Evidence-based Medicine (CEBM). Centre forEvidence Based Medicine. Levels of Evidence; 2009.
9. Santarelli R, Arslan E. Electrocochleography in auditory neurop-athy. Hear Res. 2002;170:32---47.
2
Soares IA et al.
0. Rapin I, Gravel J. Auditory neuropathy: physiologic and patho-logic evidence calls for more diagnostic specificity. Int J PediatrOtorhinolaryngol. 2003;67:707---28.
1. Ngo RYS, Tan HKK, Balakrishnan A, Lim SB, Lazaroo DT. Audi-tory neuropathy/auditory dys-synchrony detected by universalnewborn hearing screening. Int J Pediatr Otorhinolaryngol.2006;70:1299---306.
2. Rance G. Auditory neuropathy/dys-synchrony and its perceptualconsequences. Trends Amplif. 2005;9:1---43.
3. Shi W, Ji F, Lan L, Liang SC, Ding HN, Wang H, et al. Char-acteristics of cochlear microphonics in infants and youngchildren with auditory neuropathy. Acta Otolaryngol. 2012;132:188---96.
4. Deltenre P, Mansbach AL, Bozet C, Clercx A, Hecox KE. Audi-tory neuropathy: a report on three cases with early onsets andmajor neonatal illnesses. Electroencephalogr Clin Neurophysiol.1997;104:17---22.
5. Berlin CI, Hood L, Morlet T, Rose K, Brashears S. Auditoryneuropathy/dys-synchrony: diagnosis and management. MentRetard Dev Disabil Res Rev. 2003;9:225---31.
6. Santarelli R, Scimemi P, Dal Monte E, Arslan E. Cochlearmicrophonic potential recorded by transtympanic electro-cochleography in normally-hearing and hearing-impaired ears.Acta Otorhinolaryngol Ital. 2006;26:78---95.
7. Anastasio AR, Alvarenga KF, Costa Filho OA. Extratym-panic electrocochleography in the diagnosis of auditoryneuropathy/auditory dyssynchrony. Braz J Otorhinolaryngol.2008;74:132---6.
8. Ahmmed A, Brockbank C, Adshead J. Cochlear microphonicsin sensorineural hearing loss: lesson from newborn hearingscreening. Int J Pediatr Otorhinolaryngol. 2008;72:1281---5.
9. Riazi M, Ferraro JA. Observations on mastoid versus ear canalrecorded cochlear microphonic in newborns and adults. J AmAcad Audiol. 2008;19:46---55.
0. Talaat HS, Kabel AH, Samy H, Elbadry M. Prevalence of audi-tory neuropathy (AN) among infants and young children withsevere to profound hearing loss. Int J Pediatr Otorhinolaryngol.2009;73:937---9.
1. Mo L, Yan F, Liu H, Han D, Zhang L. Audiological results in agroup of children with auditory neuropathy spectrum disorder.ORL J Otorhinolaryngol Relat Spec. 2010;72:75---9.
2. Liu C, Bu X, Wu F, Xing G. Unilateral auditory neuropathy causedby cochlear nerve deficiency. Int J Otolaryngol. 2012:914986.
3. Penido RC, Isaac ML. Prevalence of auditory neuropathy spec-trum disorder in an auditory health care service. Braz JOtorhinolaryngol. 2013;79:429---33.
4. Starr A, Sininger Y, Nguyen T, Michalewski HJ, Oba S, AbdalaC. Cochlear receptor (microphonic and summating potentials,otoacoustic emissions) and auditory pathway (auditory brainstem potentials) activity in auditory neuropathy. Ear Hear.
2001;22:91---9.
5. Spinelli M, Breuel MLF, Silva CMS. Neuropatia auditiva: aspectosclínicos, diagnósticos e terapêuticos. Rev Bras Otorrinolaringol.2001;67:863---7.
