Brazilian
Journal
of
OTORHINOLARYNGOLOGY
www.bjorl.org
REVIEW
ARTICLE
Electrocochleography
for
Ménière’s
disease:
is
it
reliable?
夽
,
夽夽
Pauliana
Lamounier,
Débora
Aparecida
Gobbo,
Thiago
Silva
Almeida
de
Souza,
Carlos
Augusto
Costa
Pires
de
Oliveira,
Fayez
Bahmad
Jr.
∗HealthSciences,UniversidadedeBrasília(UnB),Brasília,DF,Brazil
Received11November2013;accepted25May2014 Availableonline27August2014
KEYWORDS Endolymphatic hydrops; Ménièredisease; Audiometryevoked response
Abstract
Introduction:Endolymphatichydrops,thehistopathologicalsubstrateofMénière’sdisease,is analmostuniversalfindinginpostmortemstudiesofpatientswiththisdisease.Thecauseof hydropsisstillunknown,asisthemechanismbywhichitcausesprogressivedysfunctionofthe sensoryorgansofinnerear.Thefluctuatingcourseofthediseasecomplicatestheinterpretation ofcertaintests,such aselectrocochleography;thus,forsomeauthorsitsdiagnosticvalue is questionable.
Objective: Theaimofthisstudywastoanalyzetheclinicalapplicabilityof electrocochleog-raphyinthediagnosisofhydrops.Itisavaluabletool,butstillgeneratesconflictingopinions amongotolaryngologists.
Methods:Systematicreviewoftheliteratureonelectrocochleographyinpatients diagnosed withendolymphatichydrops.
Results:A total of 34 articles regarding the use of electrocochleography inpatients with hydrops,fromtheyear2000onwards,wereselected.Ofthese,15 wereexcludedfromthe reviewastheywerenotobservationalstudies.Onlyonecross-sectionalstudyaddressingthe clinicaluseofelectrocochleographybyotolaryngologistswasincluded.
Conclusion: Electrocochleographyisavaluabletoolinthediagnosisofhydrops,asitisa non-invasive,easytohandleprocedure,whichoffersnewtechniquestoincreasethesensitivityof thetest,andtherebyassistsotolaryngologistsinthemanagementofMénière’sdisease. © 2014Associac¸ãoBrasileira de Otorrinolaringologiae CirurgiaCérvico-Facial. Publishedby ElsevierEditoraLtda.Allrightsreserved.
夽 Pleasecitethisarticleas:LamounierP,GobboDA,deSouzaTS,deOliveiraCA,BahmadJrF.ElectrocochleographyforMénière’sdisease:
isitreliable?BrazJOtorhinolaryngol.2014;80:527---32.
夽夽
Institution:UniversidadedeBrasília,Brasília,DF,Brazil. ∗Correspondingauthor.
E-mail:fayez@unb.br(F.BahmadJr.). http://dx.doi.org/10.1016/j.bjorl.2014.08.010
PALAVRAS-CHAVE Hidropisia
endolinfática; Doenc¸adeMénière; Audiometriade respostaevocada
Eletrococleografianadoenc¸adeMénière:éconfiável?
Resumo
Introduc¸ão:Ahidropisiaendolinfáticaéosubstratohistopatológicoeachadoquaseuniversal nosestudospost-mortemdepacientescomdoenc¸a deMénière.A causadahidropisiaainda édesconhecida, assimcomo omecanismo peloqualcausadisfunc¸ãoprogressivadosórgãos sensitivosdaorelhainterna.Ocursoflutuantedadoenc¸adificultaainterpretac¸ãodeexames comoaeletrococleografia,queapresenta,paraalgunsautores,valordiagnósticocontroverso.
Objetivos: Oobjetivodesteestudoéanalisaraaplicabilidadeclínicadaeletrococleografiano diagnósticodahidropisiaendolinfática,sendoumaferramentadeusocomumequeaindagera opiniõesconflitantesentreosotorrinolaringologistas.
Método: Revisãosistemáticadaliteraturasobreeletrococleografiaempacientescom diagnós-ticodehidropisiaendolinfática.
Resultados: Foramselecionados34artigossobreousodaeletrococleografiaempacientes por-tadoresdehidropisiaendolinfáticaapartirdoano2000;15artigosforamexcluídosdarevisão pornãosetrataremdeestudosobservacionais,cominclusãodesomenteumestudotransversal quetratasobreousoclínicodaeletrococleografiaentreosotorrinolaringologistas.
Conclusão:A eletrococleografia é uma importanteferramenta nodiagnóstico dahidropisia endolinfática,porsernãoinvasiva,defácilmensurac¸ão,eporoferecernovastécnicascapazes de aumentarasensibilidadedo exame eauxiliaro otorrinolaringologista notratamentoda Doenc¸adeMénière.
©2014Associac¸ãoBrasileira deOtorrinolaringologiaeCirurgiaCérvico-Facial.Publicadopor ElsevierEditoraLtda.Todososdireitosreservados.
Introduction
Endolymphatic hydrops is the histopathological substrate andan almost universal finding in postmortem studies of patientswithMénière’sdisease.Thecauseofhydropsisstill unknown,asisthemechanismbywhichitcausesprogressive dysfunctionofthesensoryorgansoftheinnerear.Various theorieshave beenproposed,andmostofthemarebased onachangeintheproductionorresorptionofendolymph.1,2
Afamilyhistoryispresent inover10%ofpatients,with geneticpredisposition,viralinfections,autoimmunedisease suggesting depositionof circulating immune complexes in theendolymphaticsacanddisordersofwaterhomeostasis whereintheaquaporinsandvasopressin playanimportant role.1,2
Onehypothesis,widelyaccepted,isthatofSchuknecht: hydrops causes rupture of Reissner’s membrane, allowing the potassium-rich endolymphatic fluid to make contact withperilymph,reachingthesurfaceofthehaircellsandof thevestibulocochlearnerve,causinghearinglossandvertigo attacks.2Intheadvancedstagesofendolymphatichydrops,
itiscommontofindpatientswithhearingthresholdsgreater than 50dB. Other theories suggest that even the disten-sionofthebasilarmembranebyendolymphatichydropsmay alreadyleadtodegenerationofhaircellsandconsequently totheirmalfunction,causingadecreaseinAP.1,2
AAO-HNSdiagnosticcriteriafrom1995onlyinclude clini-calandaudiometricparametersinthediagnosisofMénière’s disease.According tothese criteria, patientswith twoor morespontaneousepisodesofvertigo,withdurationequal or greater than 20min, with documented hearing loss on atleastoneoccasionandpresenceoftinnitusoraural full-nessareclinicallyclassifiedashavingMénière’sdisease.This
diagnosisisconsideredlikelywhenadefinedepisodeof ver-tigo occurs in the presence of documented sensorineural hearinglossonatleastoneoccasion,auralfullness,or tinn-itus.Itisconsideredaspossibleinthepresenceofepisodic vertigoofMénière’stypewithoutdocumentedhearingloss or when thereissensorineural, fixed,or fluctuating hear-inglossassociatedtoimbalance,withoutadefinitevertigo episode.3
The fluctuating course of the disease complicates the interpretation of tests such electrocochleography; some authors consider it to provide a controversial diagnostic value.Studies showdisappointing resultsforitssensitivity and specificity;however, severalinstruments can beused toincreasethesensitivityofthistest.Electrocochleography remainsastheonlyobjectivetooltomeasureendolymphatic hydropsinthecochlea.4---8
Electrocochleography registers all three mechanoelec-trical potentials of the cochlea; cochlear microphonics is consideredasthefirststeptowardneuralimpulse, reflect-ing thesum of intracellular potentials generatedinto the hair cells in the most basal portion of cochlea during its depolarization.4,6,9
Cochlearmicrophonicsisproducedbyvaryingthe potas-siumflowinthetectorialplateofhaircells,asaresultof rapidionchangesassociatedwiththeciliarymovement.At high intensities, the basilar membrane vibrates asymmet-ricallyarounditsmidpoint,andtheexcessivedisplacement towardthescalatympaniproducesaconstantdirectcurrent (DC)component,thesummationpotential(SP).4,5,7,9
believethatSPisgeneratedbybothinternalandexternal haircells.Theactionpotentialisthesumofthesynchrony ofcochlearnerve’sindividualneuralPAs.4---6
The aim of this study was to analyze the clinical applicability of electrocochleography in the diagnosis of endolymphatic hydrops, since it represents an usual tool thatstillgeneratesconflictingopinionsamong otolaryngol-ogists.
Methods
This wasa systematicreview ofthe literatureon electro-cochleographyinpatientswithendolymphatichydrops.The PubMed/MEDLINEandBIREMEdatabaseswereconsulted.
The search strategy employedin the literature review was guided by the combination of four descriptors indexed in Descriptors in Health Sciences (DecS) in BrazilianPortuguese:‘‘hidropisiaendolinfática,’’‘‘doenc¸a de Ménière,’’ ‘‘audiometria de resposta evocada,’’ and ‘‘eletrococleografia’’; and in Medical Subject Headings (MeSH) in English: ‘‘endolymphatichydrops;’’ ‘‘Ménière’s disease;’’‘‘audiometry,’’and‘‘evokedresponse.’’
The inclusioncriteriawere:retrospective and prospec-tive studies on humans from the year 2000 on electro-cochleographyinpatientswithadiagnosisofendolymphatic hydrops according to Hearing and Balance Committee of the American Academy of Otolaryngology (1995) criteria, publishedin indexedjournals. The inclusion criteriawere definedbyoneoftheauthors,whiletheotherauthorswere responsiblefortheanalysisofthearticles.
Results
Thirty-four articlesonthe use of electrocochleographyin patients with endolymphatic hydrops were selected from theyear2000onwards;15wereexcludedfromthereview because they were not observational studies, and only one cross-sectional study addressing the clinical use of electrocochleographyamongotolaryngologistswasincluded (Table1).
Discussion
Nguyen et al. evaluatedthe use of electrocochleography among members of the American Society of Otology and Neurotology AmericanSociety and found that, to approx-imately 50% of participants, electrocochleography has no roleintheirclinicalpractice,duetothevariabilityofresults andlackofcorrelationwithpatients’symptoms.8
Between25%and54%ofpatientswithMénière’sdisease produceanelectrocochleographywithnormalresults.7,8In
mostselectedstudies onelectrocochleographyinpatients withMénière’sdisease,thetranstympanicelectrodeisthe mostused,withsensitivityratesrangingfrom67%to85%.9---12
Hallreportedasensitivityof57%andspecificityof94%,5
while Chung et al. reported a sensitivity of 71% and a specificity of 96%.13 Conversely, Devaiah et al. observed
a sensitivity of 60%, which reached 92% when the elec-trocochleography was performed during a symptomatic period.14
Kimetal.examined60patientswithdefiniteand37with probableorpossibleMénière’sdisease.Overall,59.8%had abnormallyhighSP/APratios.Amongpatientswithdefinite Ménière’sdisease,66.7%hadabnormallyhighSP/APratios, whilethosewithprobableorpossibleMD,52.7%producedan abnormalelectrocochleography (p=0.069). These authors concluded that no statistically significant difference was observed in the results of electrocochleography between thedefinite andprobable/possibleMDgroups. Inaddition, approximately30% of people with definite Ménière’s dis-easewouldnotbediagnosedbasedonelectrocochleography results.Duetothelowsensitivity,accordingtoKimetal., electrocochleography should not play a decisive role in determiningthediagnosisofMénière’sdisease.15
Soaresetal.conductedaretrospectivestudy basedon 60electrocochleographystudies.SP/APratio,theamplitude betweenthefirstpositivepeakofthesecondcomponentof APandthe baseline,andtheamplitudebetween the sec-ondpositivepeakof thesecondcomponentof APandthe baseline were analyzed. These authors found that SP/AP ratiowasthemostsensitiveandspecificparameterforthe identificationofpatientswithendolymphatichydrops.16
Comparingresultsfromtranstympanicversus extratym-panic electrocochleography in 20 patients with Ménière’s disease and 20 control patients, Ghosh et al. reported a significant difference in SP/AP ratio between cases and controls. For a value of SP/AP=0.29, these authors found a sensitivity of 100% and specificity of 90% for transtympanicand90%and80%forextratympanic electro-cochleography,respectively,concludingthatextratympanic electrocochleographyisaneffective,easilyimplementedin clinicalpractice,andnon-invasivemethod,whencompared tothetranstympanicmethod.10
Pappas et al., in a retrospective study, evaluated extratympanic electrocochleography in a group of 252 patientsdiagnosedwithMDandacontrolgroupof20healthy patients.The groupwithdefinedMDshowedanincreased SP/APin74%ofcases,thegroupofpossibleMDin64%,and thebilateral MDgroup in 66%. Contralateral ears showed highratiosin42%ofcases;in40%oftheseears,atleastone contralateralsymptomwasfound.Theseauthorsconcluded that extratympanic electrocochleography plays an impor-tantroleincasesofpossibleMD,forwhichaudiologicaldata arescarce.17ThisconclusioniscorroboratedbyChungetal.,
who,inaretrospectiveanalysisof158patients(97women and61men)undergoingextratympanic electrocochleogra-phy,obtainedasensitivityof71%andaspecificityof96%for aSP/AP=0.34,reassertingtheroleofextratympanic elec-trocochleographyinpatientswithless-definedsymptoms.13
The thresholds of SP/AP ratio vary in the literature. Pappas et al. believed that any result above 0.5 with extratympanic electrocochleography with use of clicks with alternating polarity is suggestive of endolymphatic hydrops,17 while Iseli andGibson set avalue of 0.33 with
transtympanicelectrocochleography.18
Table1 Twentyselectedstudiesontheuseofelectrocochleography.
Yearandplaceofthestudy Author Typeofstudy Population
Japan,2010 Yamamotoetal.28 Retrospectiveobservationalstudy 24MDpatients
Belgium,2011 Claesetal.9 Retrospectiveobservationalstudy 109MDpatients
Korea,2012 Seoetal.29 Retrospectiveobservationalstudy 26MDpatients
Spain,2012 Martín-Sanzetal.11 Retrospectiveobservationalstudy 100MDpatients20controls
UnitedStates,2003 Devaiahetal.14 Retrospectiveobservationalstudy 138MDpatients13controls
UnitedStates,2010 Nguyenetal.8 Cross-sectionalstudy 143MDpatients
Japan,2010 Takedaetal.20 Retrospectiveobservationalstudy 632patients
Japan,2007 Babaetal.25 Retrospectiveobservationalstudy 198patients
Brazil,2003 Soaresetal.16 Retrospectiveobservationalstudy 32MDpatients 10controls
India,2002 Ghoshetal.10 Prospectiveobservationalstudy 20MDpatients 20controls
Australia,2000 ConlonandGibson12 Prospectiveobservationalstudy 500MDpatients900controls
UnitedStates,2000 Pappasetal.17 Retrospectiveobservationalstudy 252MDpatients20controls
Korea,2004 Chungetal.13 Retrospectiveobservationalstudy 158MDpatients37controls
Brazil,2011 Lopesetal.24 Retrospectiveobservationalstudy 41MDpatients 14controls
France,2011 Bükietal.22 Retrospectiveobservationalstudy 28MDpatients
Korea,2012 Moonetal.23 Retrospectiveobservationalstudy 90MDpatients
UnitedStates,2005 Kimetal.15 Retrospectiveobservationalstudy 97MDpatients
Australia,2010 IseliandGibson18 Retrospectiveobservationalstudy 40MDears 67controlears
Brazil,2006 Ikinoetal.26 Retrospectiveobservationalstudy 21MDpatients 19controls
Brazil,2002 Ikinoetal.27 Retrospectiveobservationalstudy 22MDpatients
MD,Ménière’sdisease.
Gibsonetal.comparedresultsofelectrocochleography inearsofpatientswithMénière’sdiseaseversushealthyears withsimilarhearinglossandconcludedthattheuseofclicks toassessSP/APdoesnotlenditselftosuchdifferentiation, butthattheuseof toneburststoevaluateSPamplitudeis significantlydifferentinthesepopulations.19
Colon and Gibson demonstrated that the sensitivity of transtympanicelectrocochleographyincreasesby85%when 1kHzoftoneburst wasusedtomeasureSP. Theseauthors reportedthatmostoftheexperts(58.6%)preferclickstimuli versus17.2%usingtoneburstsand24.3%usingbothstimuli.12
Claes et al. conducted a retrospective study of 131 resultsoftranstympanic electrocochleographyusingclicks andtonebursts. These authors found that91% of patients inthedefinite Ménière’s diseasegroup testedpositive for electrocochleographywithtoneburststimulation,andthat 71%ofcontrols(withoutMénière’sdisease)werenegative. Claes et al. combined audiometric and electrocochleo-graphic thresholdsand identified98% of cases of absence ofMénière’sdiseaseand94%ofcasesofdefiniteMénière’s disease.9
Takedaetal.performedaretrospectivestudy withthe use of electrocochleography in 632 patients with symp-tomsextendingover tenyears.Among them,334patients werediagnosedwithMénière’s disease,including95cases ofbilateralinvolvement.Theseauthorsfoundanincreased SP/APratioin56.3%ofpatientswithMD.Theyalsoobserved that ears with longer symptomatology and/or with more severe symptoms presented greater abnormalities in the SP/APratio.TheincidenceofSPincreasewassignificantly higherinpatientswithmorethantwoyearsofdurationof disease,orwithseveralcrisesbyyear.20Geetal.alsoagree
thatpatientswithalongerdiseasedurationpresentSP/AP ratiowithhighervalues.Theyalsoconcludedthatthe hear-inggainafterglyceroltestresultedinnodecreaseinSP/AP
ratio.21 These authorsobservedthatoncePSrises,it
per-sistsforlongperiods,evenincasesofvertigoandofhearing lossremission---datacorroboratedbyKimetal.andPappas etal.15,17
Büki et al., in a retrospective study, analyzed results ofelectrocochleographyaftervertigo controlby intratym-panicinjectionofgentamicinandobservedthattheSP/AP ratio measured by electrocochleography did not exhibit statisticallyincreasesintheabsenceofsymptoms.The ele-vationofSPamplitudeinearswithendolymphatichydrops appearstodependmainlyonthemechanoelectrical trans-duction process into the cochlea, due to the loss of hair cells or to potassium poisoning of the perilymph, instead ofthemechanicalfactorofthedisplacementofthebasilar membrane.22
Moon et al. noted that patients with abnormal SP/AP exhibited significant elevation in their hearing thresholds compared with those who had SP/AP within the normal range, suggesting that MD patients with severe endolymphatic hydrops suffer more severe hear-ing deterioration over time23 --- data corroborated by Ge
etal.23
Lopes assessed the sensitivity and specificity of SP/AP ratioandthegraphicangularmeasurein electrocochleog-raphy studies of 71 ears (41 MD patients and 14 healthy controls). This authorconcludedthat the graphic angular measureis notsensitive andspecific enough forthe diag-nosis ofMD.Theassociation ofSP/AP andgraphicangular measureresultedinimprovedsensitivity,attheexpenseof thespecificityofthetest.24
under the curve (AUC) for both groups were measured. These authors identified an increase in sensitivity for transtympanicelectrocochleographywithclickswith alter-natingpolarity,byanalyzingSP/APAUCinthediagnosisof Ménière’sdisease.Theyfoundthatsevenofeightpatients withpossible Ménière’sdiseaseshowan increaseinSP/AP AUC.14
Baba et al. conducted a retrospective study of 198 patients undergoing transtympanic electrocochleography and compared SP/AP ratio and SP/AP AUC. Regarding SP/AP ratio, they found 57.1% of sensitivity in patients withdefinite MD,39.6%inpatients withprobableMD,and 50% in those cases that turned from probable to defi-nite MD. With respect to SP/AP AUC, they found 43.9%, 27.7%, and 30% respectively, concluding that the analy-sisofSP/APAUCwithtranstympanicelectrocochleography does not necessarily increase the sensitivity in the diag-nosis of endolymphatic hydrops compared with SP/AP amplitude.25
Ikinoetal.usedtranstympanicelectrocochleographyto examine 21 patients with definite Ménière’s disease and 19 normal hearing patients with other cochleovestibular disorders. They compared SP/AP, AP latency difference, and area under curve of SP/AP ratio and calculated the diagnostic sensitivity of theseparameters. The mean SP/AP AUC was 1.89ms in the study group and 1.58ms in the control group. The mean SP/AP was 0.37 in the study group and 0.22 in the control group. The mean product of SP/AP AUC by SP/AP ratio was 75.26ms in the study group and 34.60ms in the control group. The mean AP latency difference was 0.13ms in the study group and 0.07ms in the control group. The differences betweengroupswerestatisticallysignificantforall param-eters evaluated. The sensitivities for SP/AP AUC, SP/AP ratio, andAP latency differencein the study group were 33.3%,52.4%, and23.8%,respectively. Theseauthors con-cluded that the use of the parameters studied did not increase the sensitivity of electrocochleography, regard-less of whether they were used alone or in conjunction withSP/AP. The calculation of SP/AP showedthe highest sensitivity.26
Ikino et al. also analyzed 22 patients (16 females and eightmales)withtranstympanicelectrocochleography, aim-ingtoexaminethelatencyofcondensedandrarefiedclicks andthedifferencesbetweentheselatenciesinpatientswith Ménière’s disease. Those eight cases (36.4%) with SP/AP ratio≥0.33weredefinedasgroup1,whereasthe14cases
(63.6%)withSP/APratio<0.33weredefinedasgroup2.In 36.4%ofpatients,therelationshipbetweenthesummation potentialandtheactionpotentialwasgreaterthan0.33;for thesepatients,thelatencyofcondensedclicks,thelatency forrarefiedclicks,andthedifferencesbetweentheir laten-cies were 1.94ms, 1.84ms, and 0.25ms, respectively. In the other patients, these values were 1.71ms, 1.71ms, and 0.09ms. Ikino et al. concluded that the latency for condensedclicksandthedifferencebetweenlatenciesfor condensedandrarefiedclickswerenotsignificantlyhigher inpatientswithendolymphatichydrops.27
Yamamotoetal.performedanmagneticresonance imag-ing (MRI) study after intratympanic gadolinium injection andobservedthattheSP/APratioobtainedwith extratym-panic electrocochleography with the use of rarefied and
condensedclickswassignificantlyincreasedinpatientswith endolymphatichydrops,exceptinpatientswithearly-stage disease,withinthreemonthsoftheonsetofsymptoms.28
Seoetal.alsodemonstratedendolymphatichydropsin the cochlea (81%) and saccule (69%) using MRI 3T after intratympanicgadoliniumincorrelationwithabnormal elec-trocochleographicthresholds.Theyconsideredasanaltered SP/AP threshold for click stimuli greater than 0.33, and 1000Hztoneburstswereconsidered abnormalifthe abso-lutemagnitudeofPSwere≤3V.29
Studies examined the difference in specificity and sensitivity of transtympanic and extratympanic collec-tionmethods. The present review demonstrated that the transtympanicmethodwouldbemore effective;however, accordingtoPappas,Ghosh,andChung,theextratympanic methodcanalsobeconsideredasaneffective,easyto per-forminclinicalpractice,andnon-invasivemethod.10,13,17It
wasobservedthatelectrocochleographyplaysarole, espe-cially in cases of scarce audiological data and with less definedsymptoms.
Regardingthevariationofstimulitoobtaintheresults, itwasobservedthattheclickisnotusefulfor differentiat-ingbetweenhealthyearsandearswithMénière’sdisease. InthestudiesbyGibson, Colon,andClaes,itwas demon-stratedthat thetoneburst increasesthesensitivity ofthe test.9,12,19As tothestimulipolarity,nostatistically
signifi-cantdifferenceswereobservedinrelationtodifferencesin latencyforcondensateandrarefiedstimuli.
Itcanbeconcludedthatthe SP/APratiowasthemost sensitiveandspecificdiagnosticparameter---data corrobo-ratedbySoares,Baba,andIkino.16,25,26 LopesandDevaiah
reportedanincreaseinsensitivityofthetestfordiagnosis withtheassociationofSP/APratiowiththeareaunderof thecurveof SP/AP.14,24 TheSP/AP thresholds arevariable
intheliterature,withdiagnosisforvaluesgreaterthan0.5, accordingtomostauthorssearched.
Several authors also analyzed the relationship of SP amplitudewithdiseaseduration.Itwasobservedthatears withsymptomsoflongerdurationshowgreater abnormali-tiesintheSP/APratio;andthatonceSPrises,thissituation willpersistforlongperiods.
Conclusion
Electrocochleographyis animportanttoolin thediagnosis ofendolymphatichydrops.Theliteraturereviewidentified thattheextratympanic methodis effective,non-invasive, andeasy to performin clinical practice. New techniques canincrease thesensitivityof thetest,suchastheuseof thetoneburstandtheanalysisoftheareaunderthecurveof SP/APratio,inassociationwithSP/APratiomeasurement.
Electrocochleographystillremainstheonlytestthatcan objectivelymeasureendolymphatichydropsinthecochlea andthatfulfills itsrole,aiding theotolaryngologistinthe treatmentofMénière’sdisease,especiallywhenthe audio-logicaldataarescarceandthesymptomsarelessdefined.
Conflicts
of
interest
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