www.bjorl.org
Brazilian
Journal
of
OTORHINOLARYNGOLOGY
ORIGINAL
ARTICLE
Simultaneous
idiopathic
bilateral
sudden
hearing
loss
---
characteristics
and
response
to
treatment
夽
Ferit
Akil
a,
Umur
Yollu
b,∗,
Mehmet
Yilmaz
c,
H.
Murat
Yener
c,
Marlen
Mamanov
c,
Ender
Inci
caDiyarbakirSelahaddinEyyubiPublicHospital,OtolaryngologyClinic,Diyarbakir,Turkey bGumushanePublicHospital,OtolaryngologyClinic,Gumushane,Turkey
cIstanbulUniversity,CerrahpasaMedicalSchool,DepartmentofOtolaryngology,Istanbul,Turkey
Received7September2016;accepted18December2016 Availableonline24January2017
KEYWORDS
Suddenhearingloss; Autoimmune diseases; Tinnitus; Treatment; Prognosis Abstract
Introduction:Theaetiologyofsuddenhearinglossispoorlydefined;however,infectious, vas-cularandneoplasticaetiologiesarepresumedtoberesponsible.Inaddition,theaetiologyof bilateralsuddenhearinglossisalsounknown.
Objective: Theobjectiveofthisstudyisidentifythecharacteristicsandtreatmentresponseof simultaneousbilateralsuddenhearingloss.
Methods:This isa case---controlstudy that practisedintertiary careacademic centre.132 patientswithsuddenhearinglosswhoweretreatedwithsystemicsteroidandhyperbaric oxy-gentogetherwereincluded.26patientshadbilateralsuddenhearinglossand106patientshad unilateralsuddenhearingloss.Patientswereevaluatedwithclinical,audiologicaland radio-logicalexaminationsandlaboratorytestsweredone.Findingsandresponsetotreatmentofthe patientswerecompared.
Results:Themeanagesofpatientswithunilateralandbilateralsuddenhearinglosswere42.0 yearsand24.5yearsrespectivelywithastatisticallysignificantdifference(p<0.001).Immune responsemarkersweremoreprevalentinbilateralsuddenhearingloss.Pre-treatment audio-logicthresholdswere69.1dBforunilateralsuddenhearinglossand63.3dBfortheleftearsand 67.6dBfortherightearsforbilateralsuddenhearinglosswithoutsignificantdifference. Post-treatmentaveragehearingthresholdinunilateralsuddenhearinglosswas47.0dBand55.4dB fortheleftearsand59.0fortherightearsinbilateralsuddenhearingloss.Averagehearing improvementinunilateralsuddenhearinglossgroupwassignificant(p<0.001)inspiteofitwas notsignificantinbilateralsuddenhearinglossgroupforbothears.Betweenthegroups;there wasasignificantdifferenceforhearingimprovementfavouringunilateralsuddenhearingloss
夽 Pleasecitethisarticleas:AkilF,YolluU,YilmazM,YenerHM,MamanovM,InciE.Simultaneousidiopathicbilateralsuddenhearingloss ---characteristicsandresponsetotreatment.BrazJOtorhinolaryngol.2018;84:95---101.
∗Correspondingauthor.
E-mail:umuryollu@hotmail.com(U.Yollu).
PeerReviewundertheresponsibilityofAssociac¸ãoBrasileiradeOtorrinolaringologiaeCirurgiaCérvico-Facial.
https://doi.org/10.1016/j.bjorl.2016.12.003
1808-8694/©2017Associac¸˜aoBrasileiradeOtorrinolaringologiaeCirurgiaC´ervico-Facial.PublishedbyElsevierEditoraLtda.Thisisanopen
(p<0.001).Tinnitusscoresdecreasedsignificantlyinbothgroupsofpatients(p<0.001)inspite oftherewasnosignificantdifferencebetweenthegroupsofpatients.
Conclusion:Patientswithbilateralsuddenhearinglossshowedlowerage,worseprognosisand higherrateofpositiveimmuneresponsemarkers.Cardiovascularriskfactorsseemtohavean importantroleintheaetiologyofunilateralcaseswhereasthisimportancewasnotpresentin bilateralones.
© 2017 Associac¸˜ao Brasileira de Otorrinolaringologia e Cirurgia C´ervico-Facial. Published by Elsevier Editora Ltda. This is an open access article under the CC BY license (http:// creativecommons.org/licenses/by/4.0/).
PALAVRAS-CHAVE
Perdaauditivasúbita; Doenc¸asautoimunes; Zumbido;
Tratamento; Prognóstico
Perdaauditivasúbitabilateralidiopáticasimultânea---característicaseresposta aotratamento
Resumo
Introduc¸ão:A etiologia da perda auditiva súbita ainda não está bem definida; contudo, presume-sequeasetiologiasinfecciosas,vasculareseneoplásicassejamasresponsáveis.Além disso,aetiologiadaperdaauditivasúbitabilateraltambémédesconhecida.
Objetivo:Oobjetivodesseestudofoiidentificarascaracterísticasearespostaaotratamento deperdaauditivasúbitabilateralsimultânea.
Método: Esteéumestudodecaso-controlerealizadoemumcentrodeatenc¸ãoterciária.Foram incluídos132pacientescomPerdaAuditivaNeurossensorialSúbita(PANS)queforamtratados comesteroidessistêmicoseoxigêniohiperbárico.26pacientestiveramPANSbilaterale106 pacientestiveramPANSunilateral.Ospacientesforamavaliadoscomexamesclínicos, audiológi-cos,radiológicoseexameslaboratoriais.Osachadosearespostaaotratamentodospacientes foramcomparados.
Resultados: AsidadesmédiasdospacientescomPANSunilateralebilateralforam42,0anose 24,5anos,respectivamente,comdiferenc¸aestatisticamentesignificante(p<0,001).Os mar-cadoresderespostaimuneforammaisprevalentesnaPANSbilateral.Oslimiaresaudiológicos pré-tratamentoforam69,1dBparaPANSunilaterale63,3dBparaaorelhaesquerdae67,6dB paraaorelhadireitaparaPANSbilateral,semdiferenc¸asignificativa.Olimiarmédiodeaudic¸ão pós-tratamentoemPANSunilateralfoide47,0dBe55,4dBparaaorelhaesquerdae59,0para aorelhadireitaemPANSbilateral.AmelhoraauditivamédianogrupocomPANSunilateralfoi significativa(p<0,001),apesardenãosersignificativanogrupocomPANSbilateralparaambas asorelhas.Houvediferenc¸asignificativaentreosgrupos namelhoraauditivafavorecendoa PANSunilateral(p<0,001).Osescoresdezumbidodiminuíramsignificativamenteemambosos gruposdepacientes(p<0,001),apesardenãoterhavidodiferenc¸asignificativaentreosgrupos depacientes.
Conclusão:OspacientescomPANSbilateralerammaisjovens,tinhampiorprognósticoemaior taxademarcadoresderespostaimunológicapositiva.Osfatoresderiscocardiovasculares pare-cemterumpapelimportantenaetiologiadoscasosunilaterais,aopassoqueessaimportância nãoestavapresentenoscasosbilaterais.
© 2017 Associac¸˜ao Brasileira de Otorrinolaringologia e Cirurgia C´ervico-Facial. Publicado por Elsevier Editora Ltda. Este ´e um artigo Open Access sob uma licenc¸a CC BY (http:// creativecommons.org/licenses/by/4.0/).
Introduction
Suddenhearingloss(SHL)isdefinedasasensorineuraltype of hearing loss that develops over a periodof 72h, with 30dB or more of hearingreduction in at least 3 contigu-ousfrequencies.Theseverityofthehearinglossvariesfrom patienttopatient.SHLcanaffectanyagegroup,butusually peaksat60yearsofage,withoutagenderdifference.1Ear
fullnessandtinnitusarecommoncomplaintsintheaffected ear, while varying degrees of vertigo can be detected in 40% of SHL patients.2 The estimated incidence of SHL in
the UnitedStates per year rangesfrom 5to20 cases per 100,000 individuals.3 Most cases of SHL develop
unilater-ally,withbilateralinvolvementcomprisingonly 0.44---4.9% of thepatients,1---5 whichmakes theincidenceof bilateral
SHL extremelylow.5 Although rare,thiscondition is more
dramaticduetothebilaterallossofhearing.
The aetiologyof sudden hearingloss is poorlydefined; however, infectious, vascular and neoplastic aetiologies are presumed to be responsible.2,3 In addition, the
aeti-ology of bilateral SHL is also unknown. The presumed factors,suchasviralinfection,circulatoryinsufficiencyor
labyrinthinemembrane rupture, aresimilarto thecauses of the unilateral form.1---5 Many treatment protocols have
beendescribed,butthereisnoconsensusaboutthe treat-mentmodalityofchoiceinSHL.Themostwidelyaccepted therapyistaperedoralcorticosteroidtherapy.6However,a
bettertreatmentresponsehasbeenreportedinthe litera-turewiththeadditionof hyperbaricoxygen (HBO)tooral steroidtherapy.7 Certainprognosticfactorscanbeusedin
the predictionof the treatment results in unilateral SHL. Overall,theprognosisofSHLisrelatedtoage,theinterval betweenthedevelopmentoftheconditionandtreatment, thepresenceorabsenceofvertigoandtinnitus,thedegree ofhearingloss,andthepatternsoftheaudiogram.8Inthe
casesofbilateralSHL,sincetheincidenceislow,the prog-nosticfactorsarenotasclear.
In this study,we conducteda retrospective analysisof SHLcasesthatpresentedtoourclinic.Thosepatientswith simultaneousbilateralSHLwerecomparedtothepatients withunilaterallosswithrespecttotheetiologicalfactors, demographicsandresponsestotreatment,inordertobetter understandthisrarecondition.
Methods
Between2000and2012,thechartsof857patientsadmitted tothetertiarycareacademiccentrewithcomplaintsofSHL werereviewed.Intotal,132patientstreatedwiththesame protocol(systemicsteroidswithHBOtreatment),andwho metthe followingcriteriawere includedin thisstudy: no historyofpreviouseardiseases,headinjuriesandacoustic trauma.SHLwasdefinedassensorineuralhearinglossofat least30dBin 3contiguous frequencies over aperiodof 3 daysorless.Theage,sex,durationofsymptoms,laterality ofthedisease,presenceofvertigoordizziness,and cardio-vascularrisksofthepatientswerenoted.Diabetesmellitus, hypertensionandvasculitiswereregardedascardiovascular risks.
Twenty-six patients (16 males, 10 females, mean age 24.5±19.8 years old, range 7---57 years) had bilateral SHL, and 106 patients (56 males, 50 females, mean age 42.0±15.0yearsold,range12---58years)hadunilateralSHL. Each patient was evaluated with a detailed medical his-tory,completeheadandneckexamination,laboratorytests, serialpuretoneaudiogram,MRIandCTscan.Bloodsamples werecollectedfromthepatients,acompleteblood count anderythrocytesedimentationrate(ESR)wereconducted, andthealaninetransaminase(ALT),aspartatetransaminase (AST), serumglucose,cholesterol, lipid,urea,creatinine, thyroidhormoneandantinuclearantibody(ANA)levelswere measured.HEARstagingwasusedtoclassifytheaudiogram characteristics.Accordingtothisstagingsystem,whiletype 0isflat,centralorupwardsloping,type1isdownsloping orindicativeoftotalhearingloss.1WeusedtheTurkish
ver-sionofthevalidatedquestionnaireoftheTinnitusHandicap Inventory(THI)togradethetinnitus.9
Each patient was treated with systemic steroids and HBO.Theoralsteroidprotocolforsuddenhearinglossused in our clinic consisted of 1mg/kg prednisolone (Prednol; MustafaNevzat,Istanbul,Turkey),witha10mgtaperevery 3 days. The oral steroid therapy lasted about 3 weeks. In addition, the patients received lansoprazole (Lansor;
Sanovel, Istanbul,Turkey) asa proton pump inhibitor for gastrointestinal protection, and they were instructed to avoidsaltandhighcarbohydratediets.Theprotocolofthe HBOtreatmentwastwosessionsperdayduringthefirst3 days,andonesessionperdayduringthefollowingdays,for atotalof20sessionsat2.5ATAwith120minpersession.
The clinical and audiological findings and responses to treatment were compared between the groups, as well as within the groups of patients (pre-treatment to post-treatment).The one-wayANOVA, Kruskal---Wallis,Chi squared, and Mann---Whitney U tests were used, and the statisticalanalyseswereconductedwithIBMSPSSsoftware version 19 (IBM Corporation, New York, USA). The means andstandarddeviationswerecalculated,andap<0.05was consideredtobesignificant.
Results
The charts of 857 patients with SHL were reviewed, and 132patientswereincludedinthe study.The demographic data,and clinical and audiological findings are presented inTable1.Overall,106(56male,50female)patients pre-sented withunilateral SHL, and26 patients (16 male, 10 female)presentedwithbilateralSHL.Nosignificant differ-ence was observed between the groups of patients with regardtogender.The agesofthe patientswithunilateral SHLranged between12 and58yearsold,witha meanof 42.0±15.0,andtheagesofthepatientswithbilateralSHL rangedbetween7and57years,withameanof24.5±19.8. Therewasasignificantdifferencebetweentheagesofthe groups(p<0.001)(Table1).
The patients withunilateral SHL presented between 0 and30 days,withamean of4.1±5.6, andthe presenta-tionofthepatients withbilateralSHL wasbetween1and 10days, witha meanof 4.5±3.5. There wasno statisti-callysignificantdifferenceinthedurationofthehearingloss betweenthegroups(p=0.68).Twenty-eightofthepatients (26.4%)withunilateralSHLpresentedwithvertigoor dizzi-ness,whileonlytwoofthepatientswithbilateralSHLhad thistypeofsymptom, withoutany statisticalsignificance. In addition, 23 of the patients (21%) with unilateral SHL hadcardiovascularrisks,butnoneofthepatients(0%)with bilateralSHLhadthem.Thedifferencebetweenthegroups wasvery closeto significance (p=0.07).Moreover, in the unilateral SHL group, 32 of the patients (30%) had upper respiratorytractinfectionsbeforetheonsetofSHL,while6 ofthepatientswithbilateralSHLhadpreviousupper respira-torytractinfections(23%),withoutstatisticalsignificance.
None of the patients with unilateral or bilateral SHL demonstratedabnormalitiesintheirMRIorCTscans. How-ever, 28 of the patients (26.4%) with unilateral SHL had abnormallaboratorytestresults:thetotalcholesterol lev-elswereabnormalin14ofthepatients,theESRwashighin 2patients,theANAwashighin1patient,thethyroid func-tiontestsdemonstratedhypofunctionin2patients,andthe serumglucoselevelswerehighin9patients.Inaddition,4 ofthepatients(15%)withbilateralSHLhadabnormal labo-ratoryresults:2patientshadANApositivityand2patients hadanincreasedESRs.
Thepre-treatmentaudiologicalthresholdofthepatients with unilateral SHL was 69.1±31.1dB. In the bilat-eral SHL group, the baseline audiological threshold was
Table1 Demographics,clinicalfindings,tinnitusscoresandaudiologicdataofthepatientswithunilateralandbilateralSHL (p-valuesarestatisticsbetweenthegroups).
UnilateralSHL BilateralSHL p
Numberofpatients 106 26
Gender(F/M) 50/56 10/16 0.76
Av.age(mean±st.d.[range]) 42.0±15.0(12---58) 24.5±19.8(7---57) 0.001 Durationofsymptoms(day[range]) 4.1±5.6(0---30) 4.5±3.5(1---10) 0.68 Baselineaudiogram(Av.puretone---dB) 69.1±31.1 L:63.3±18.6 0.3
R:67.6±20.8 0.8 Post-treatmentaudiogram(Av.puretone---dB) 47.0±32.4 L:55.4±22.7 0.001
R:59.0±21.7 0.001 Hearingimprovement(dB) 22.1 8.2(averageof2ears) 0.001
Audiogramtype Type0:46 Type0:5 0.37
Type1:60 Type1:8
Vertigoordizziness (−):78 (−):24 0.18
(+):28 (+):2
Tinnitus (−):18 (−):4 0.12
(+):88 (+):22
Pre-treatmenttinnitus(Av.ofTHIscore) 2.9±1.4 2.7±1.5 0.87 Post-treatmenttinnitus(Av.ofTHIscore) 1.9±1.2 2.0±0.8 0.12
CTandMRIfinding(abnormal/normal) 0/106 0/26
---Cardiovascularriskfactors(±) 23/83 0/26 0.07
Historyofupperrespiratorytractinfection(±) 32/74 6/20 0.75
USSHL,unilateralsuddensensorineuralhearingloss;BSSHL,bilateralsuddansensorineuralhearingloss.
63.3±18.6dB for the leftears and 67.6±20.8dB for the right ears. However, there was no significant difference betweenthegroupswithregardtothebaselinethresholds (Table1).Fortheaudiogramtypes,46patientshadtype0 and60patientshadtype1intheunilateralSHLgroup.Five ofthepatientshadtype0and8hadtype1inbilateralSHL group, but there was no statistical significance between thegroups(Table1).
Tinnitus was present in 88 (83%) of the patients with unilateral SHL and 22 (84%) of the patients with bilat-eralSHL.Thepre-treatmentaveragetinnitusscoresofthe patientswithunilateralandbilateralSHLwere2.9±1.4and 2.7±1.5,respectively, andthedifferencewasnot signifi-cant.Thepost-treatmentaveragetinnitusscoresdecreased to1.9±1.2intheunilateralSHLgroupand2.0±0.8inthe bilateralSHLgroup,butagain,thedifferencewasnot signif-icant.Thepretopost-treatmentdifferenceintheaverage tinnitus score in those patients with unilateral SHL was
statisticallysignificant(p=0.01).Inaddition,the improve-ment in the average tinnitus score wasalsosignificant in thepatientswithbilateralSHL(p=0.02)(Table2).
The post-treatment average hearing threshold of the patients withunilateral SHL was 47.0±32.5dB. The cor-respondinghearingthresholdsofthebilateralSHLpatients were46.0±22.7dBfortheleftearsand59.0±21.7dBfor therightears.Whiletheaveragehearingimprovementwas 22.1dB in theunilateral SHL group, it was7.8dB for the leftears,8.6dBfortherightearsand8.2dBforthe aver-ageofthetwoearsinthebilateralSHLgroup.Therewasa significantdifferencebetweenthegroupsaccordingtothe averagehearingimprovement(p<0.001)(Table1).
Overall,therewasasignificantimprovementwith treat-mentonthehearingintheunilateralSHLgroup(p<0.001). However,thehearingimprovementsofbothearsinthe bilat-eralSHLgroupwerenotstatisticallysignificant(p=0.56for theleftearsandp=0.09fortherightears)(Table2).
Table2 AudiologicthresholdsandtinnitusscoresofthepatientsinunilateralandbilateralSHL(pvaluesarein-groupstatistics).
Pre-treatment Post-treatment p USSHL
Audiologicthresholds(Av.puretone---dB) 69.1±31.1 47.0±32.4 0.001 Tinnitusscores(Av.ofTHIscore) 2.9±1.4 1.9±1.2 0.01
BSSHL
Audiologicthresholds---left(Av.puretone---dB) 63.3±18.6 55.4±22.7 0.56 Audiologicthresholds---right(Av.puretone---dB) 67.6±20.8 59.0±21.7 0.09 Tinnitusscores(Av.ofTHIscore) 2.7±1.5 2.0±0.8 0.02
Discussion
SHL is a disorder affecting adults that is not uncommon, which causes a severe limitation in the quality of life, and urgent management is necessary to improve hearing recovery.10,11SHLisdefinedasarapidonset(occurringover
a72h period)sensorineuraltypeofhearingimpairmentin oneorbothears.Themostfrequentlyusedaudiological cri-terionisadecreaseinthehearingthresholdofmorethan 30dBin3consecutivefrequencies.11
Mostpatients withSHLpresent witha unilateral disor-der, and bilateral involvement is very rare.4 There have
been some case reports describing SHL in both ears in patientswithbilateraltemporalbonefractures,12temporal
intracerebral haemorrhage,13 meningeal carcinomatosis,14
metastatictumours,15 or druguse.16 Todefine thesudden
hearing loss as idiopathic, no identifiable cause must be found, despite adequate investigation. In our series, the patients wereevaluatedwithadetailedhistory, including druguse,andCTandMRIexaminationstoidentifyan under-lyingcause.NoneofthepatientswithSHLdemonstratedany disordersrelatedtohearingloss.
Inthisstudy,theagesofthepatientswithunilateralSHL were significantly higher than those of the patients with bilateral SHL (42.0±15.0 vs. 24.5±19.8, respectively). Although themean age ofthe patients withbilateral SHL washigherthanthatoftheunilateralgroupinthecommon literature,4,10 itis notpossible tospeculate thatbilateral
SHL is more frequently seen in the younger age group, accordingtoourresults.Attentionshouldbedrawntothis contradiction.
In some studies of SHL, bilateral involvement ranges from 0.44% to 4.9% of the patients.1---5 In their study,
Kiriake et al. reported 7 patients out of 205 cases of SHL.17 Fetterman et al. reported 1.7% bilateral
involve-mentin823patients,whileOh etal.reported4.9%in324 patients.10Inourstudy,weevaluated857patientswithSHL,
anddetectedsimultaneousbilateralearinvolvementin26 patients(3%),which wassimilartothecurrent literature. We included cases that were all given the same treat-ment,andatotalof132patientswereappropriateforthe analysis.
Therehasbeensomespeculationwithregardtothecause of SHL, including viral infection, vascular insufficiency, rupture of the labyrinthine membranes and autoimmune reactions.3,18 As in the unilateral cases, those disorders
thatleadtobilateral SHLarealsothoughttobevascular, metabolic,traumatic,autoimmune,infectious,toxic, neo-plastic or inflammatory.11 There have been some reports
supportingaviralaetiologyinthedevelopmentofbilateral SHL.19Forexample,Fettermanetal.reportedthatthe
inci-dencesofpreviousviralillnesswerehigherinthecasesof bilateralSHL,butwithoutanystatisticalsignificance.4
How-ever,Xenellisetal.detectedahistoryofviraldiseaseinonly 9%oftheirpatientswithbilateralSHL.20 InthestudybyOh
etal.,therewasnodifferencebetweentheunilateraland bilateralSHLcaseswithregardtoahistoryofviraldisease.10
Inthisstudy,32(30%)ofthepatientswithunilateralSHLand 6(23%)ofthepatientswithbilateralSHLhadpreviousviral diseasesbeforetheonsetofhearingloss.Althoughthe inci-dencewashigherintheunilateralgroup,thedifferencewas notsignificant.Wedonotbelievethatviralinfectionisan
effectiveetiologicalagenttoshowadifferencebetweenthe groups.
The vascular insufficiency theory wassupported in the reportbyFettermanetal.4Theyfoundthatthosepatients
withbilateralSHLhada3foldhigherincidenceof cardiovas-culardiseasethanthepatientswithunilateralSHL.Ohetal. detectedasignificantlyhigherincidenceofsystemic cardio-vascular disorders,but concludedthat peripheral circular dysfunctioncouldnotbethemajormechanismforthe devel-opmentofbilateralSHL.10 Conversely,Xenellisetal.could
notfindanycardiovasculardiseases in theirpatients with bilateralSHL,20 whichwassupportedbyourstudy.
Accord-ingtoourresults,cardiovascularriskfactorsseemedtoplay animportantroleinthe aetiologyof theunilateralcases, butthisimportancewasnotpresentin thebilateralones. Ohetal. foundsignificantly increasedlipidlevelsintheir patientswith bilateral SHL,which might constitute a risk factor.10 The mostfrequently encounteredabnormal
labo-ratoryfindinginthisstudywashyperlipidaemia,whichwas onlydetectedinthepatientswithunilateralSHL.Thiscould beanothersupportive resultfor theopinionabout cardio-vascularrisksstatedabove.
Inourstudy,wedetectedanincreasedANAlevelinonly one patient, and an increased ESR in two patients from theunilateralSHLgroup.Two ofthepatientsinthe bilat-eral SHL group presented with ANA positivity, while two otherpatientshadincreasedESRs.Theabnormallaboratory findingswereevaluatedtogether,andalthoughthe differ-encesbetweenthegroups wereinsignificant,thepatients with bilateral SHL had a tendency towards higher levels of immune response markers (3/106 patients in the uni-lateral SHL group and 4/26 patients in the bilateral SHL group).
Overall, SHL treatment remains controversial. While some authors believe that steroid treatment is nobetter thanaplacebo,21 somemeta-analyseshaveshownaslight,
butnotstatisticallysignificant,benefitfrommedical treat-mentover aplacebo.22 Although thedata donotstrongly
support its use, corticosteroid treatment is one option thatdemonstratesefficiency.11 Weroutinelyprescribeoral
steroidstosuppresstheinflammationandpossible autoim-munitywithinthecochlea.The useofHBO isonemethod forthetreatmentofSHL,andtherehavebeensomereports demonstrating the beneficial effects of HBO in SHL by delivering oxygen to the cochlea with increased partial pressure.11 In the recent guidelinespublished by Stachler
etal.,clinicianscanofferHBOtreatmentwithin3months ofthediagnosisofSHL.11Weworkwithahighlyexperienced
HBOtherapycentre,andhaveroutinelyusedHBO therapy combinedwithoralsteroidssincetheyear2000.Webelieve thatincreasingthepartialpressureoftheoxygenincreases the oxygenation of the injured tissues, and improves the healingprocess.
Thereissomeconflictingdataabouttherecovery from bilateral SHL in the current literature. For instance, the study by Xenelis et al. stated that the improvement was higherinthecasesofunilateralSHLthaninbilateralSHL,20
whileFettermanetal.reportedhearingimprovementin67% oftheir patientswithbilateral SHL,which wasnot signif-icantly different from the unilateral cases.4 Our findings
demonstrated that the hearing thresholds of both groups improved with the steroid plus HBO treatments, but the
hearing improvement was more pronounced in unilateral SHLgroup.
Tinnitusis a verycommon co-existing conditionin SHL thatisveryhardtotreat,anditcreatessignificanteconomic and psychological problems.23 Nearly 90% of the patients
withSHLsuffer fromtinnitus,whichisa positive prognos-tic factor for hearing recovery, but a longer duration of tinnitus predicts poor results.24 In previous studies about
bilateralSHL, thepercentageof tinnituswasaround80%, whichwasnotdifferentfromtheresultsfromourstudy.4,20
ThepatientsinthisstudywerealsoevaluatedusingtheTHI, inwhichbothgroups’tinnitusscoresregressedsignificantly, and the final scores after treatment between the groups werenotsignificantlydifferent.Thismayshowtheeffects ofthesteroidHBOcombinationtreatmentontheregression oftinnitus.
Therecoveryfromsuddenhearinglossdependson cer-tainfactors,likeapatient’sage,durationofsymptoms,the severityandpatternofthehearingloss,andthepresence ofvestibularsymptoms.3,10,25Themeanageofthepatients
withbilateralSHLrepresentedabetterprognosticfactorin thisstudy.Onlytwopatients(7.6%)inthebilateralSHLgroup and28patients(26%)intheunilateralSHLgrouphadvertigo ordizziness,but thiswasnotasignificantdifference. The tinnitusscores and audiogram patternsof the twogroups alsoshowednosignificantdifferences.Inlightofthesefacts, wecansaythatagewastheonlyeffectiveprognostic fac-torbetweenthegroups.Inspiteofthis,theprognosiswas worseinthebilateralSHLgroup.
Conclusion
Bilateral SHL exhibits differentclinical features than uni-lateralSHL.Overall,ourstudydemonstratedsomeopposing findingsaboutbilateralSHLwhencomparedtothecurrent literature.Forexample,themeanageofourpatientswas younger, which showed that bilateral SHL was not a dis-easeofolderages.Moreover,thosepatientswithbilateral SHLdemonstratedpoorerprognoses,ahigherincidenceof immuneresponsemarkersandalowerincidenceof cardio-vascularriskfactors.
ThestudiesaboutbilateralSHLinthecurrentliterature areinsufficient whenconsideringthesample sizes. There-fore,webelievethatitisnotpossibletoconcludedefinite results,but bilateral SHLseems tobethe resultofa dif-ferentprocessthan intheunilateral cases,andshouldbe seriouslyconsidered.
Ethical
approval
Allproceduresperformedinstudiesinvolvinghuman partic-ipantswereinaccordancewiththeethicalstandardsofthe institutionaland/ornationalresearch.
Conflicts
of
interest
Theauthorsdeclarenoconflictsofinterest.
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