OtosclerosisChunfuDaiOtolaryngologyDepartmentFudanUniversityBackgroundDefinitionprimarymetabolicbonediseaseoftheoticcapsuleandossiclesItcausesfixationoftheossicles(stapes)Itresultsinconductiveormixedhearingloss.Itisgenetically-mediatedviaautosomaldominanttransmissionEpidemiologyRace

incidenceofmicroscopicotosclerosisCaucasian 10%Asian 5%AfricanAmerican 1%NativeAmerican 0%EtiologyManytheorieshavebeenproposedsuchashereditary,54%ofpatientspresentwithfamilyhistoryendocrine,womenwithpregnancyworseherhearingmetabolic,enzymeabnormalwaspathogeninfectious,viruswasidentifiedinthelesionvascular,autoimmune,nonehavebeproven.Hormonalfactorshavebeensuggestedtoplayaroleinotosclerosisbasedontheobservationthatpregnancysometimesacceleratestheprogressionofthedisease.PathophysiologyOtosclerosis(otospongiosis)isanosseousdyscrasia,limitedtothetemporalbone,andcharacterizedbyresorptionandformationofnewboneintheareaoftheossiclesandoticcapsule.PathophysiologyThemostcommonsiteofinvolvementistheanteriorovalwindownearthefistulaantefenestrum.Whenboththeanteriorandposteriorendsofthefootplateareinvolveditistermed“bipolar”involvementorfixation(ifthefootplateisimmobile).Ifonlythefootplateisinvolved,itissometimesreferredtoasa“stapedialotosclerosis”.Whentheentirefootplateandannularligamentareinvolveditisknownasanobliteratedfootplateorobliterativeotosclerosis.Theroundwindowisinvolvedinapproximately30%to50%ofcasesPathophysiologyotosclerosishastwomainforms:anearlyofspongioticphase(otospongiosis)Theearlyphaseischaracterizedbymultipleactivecellgroupsincludingosteocytes,osteoblasts,andhistiocytes.Itdevelopsaspongyappearancebecauseofvasculardilationsecondarytoosteocyteresorptionofbonesurroundingbloodvessels.Thiscanbeseengrosslyasredhuebehindthetympanicmembranetermed“Schwartze'ssign”Pathophysiologyotosclerosishastwomainformsalateorscleroticphasedensescleroticboneformsintheareasofpreviousresorption.Boththescleroticandspongioticaswellasintermediatephasesmaybepresentatthesametime.Otoscleroticfocialwaysbegininendochondralbonebutmayprogresstoinvolveendostealandperiosteallayersandevenenterintothemembranouslabyrinth.PathophysiologyMicroscopically,afocusofactiveotosclerosisrevealsfingerprojectionsofdisorganizedbone,richinosteocytesparticularlyattheleadingedge.Inthecenterofthefocus,multinucleatedosteocytesareoftenpresent.Inthescleroticphase,DiagnosisSlowlyprogressive,bilateral(80%),asymmetric,conductivehearinglossTinnitusisassociatedwith75%patientsTheageofonsetofhearinglossisyoungHistoryofsignificantearinfectionsmakesthediagnosisofotosclerosislesslikely.25%ofpatientspresentwithsomevestibularcomplaintsDiagnosislow-volumespeech.conductivenatureoftheirhearingloss,theyperceivetherevoiceaslouderthanitactuallyis.ParacusisofWillis.ItoccursbecausetheCHLreducesthevolumeofthebackgroundnoise,Two-thirdsofpatientswillreportafamilyhistoryofhearingloss.WomenwithpregnancyworseherhearingPhysicalexaminationTMappearsnormalinthemajorityofpatientsSchwartzesignisobservedin10%ofpatients).Rinnetest:negativeEarlyinthedisease,lowfrequencyCHLwillpredominateresultinginanegativeRinnetestwiththe256-Hzonly.Asprogressionoccurs,the512andthenthe1,024-HzTFwillbecomenegative.Webertest:laterizationtopoorHLSchwabachtest:prolongedboneconductionGelletest:negativetypeAs(s-stiffnesscurve)tympanogramandischaracteristicofadvancedotosclerosisbutmorecommonly,malleusfixation.TestsPuretoneaudiometryEarlystage:adecreaseinairconductioninthelowfrequency,especiallybelow1000Hz.Asthediseaseprogresses,theairlineflattens.becausetheotoscleroticfocushasamassaffectontheentiresystem,carhartnotchisnoted.Furtherprogressionofotosclerosistoinvolvethecochleamayresultinincreasedboneconductionthresholdsinhighfrequency,A-Bgapexistsinlowfrequency.Moreisolatedcochlearotosclerosismaysometimesresultinamixedhearinglosswitha“cookie-bite”patternwithbothairandbonelines.TestsCarhartnotch

Carhartnotchisthehallmarkaudiologicsignofotosclerosis.Itischaracterizedbyadecreasedintheboneconductionthresholdsofapproximately5dBat500Hz,10dBat1000Hz,15dBat2000Hz,and5dBat4000Hz.ImagestudyCTcancharacterizetheextentoftheotoscleroticfocusattheovalwindowCTscancanexcludecapsularinvolvementwhenpatientshavesignificantmixedhearinglossAnenlargedcochlearaqueductmaybeseenwhichpotentialcausesperilymphgusherduringfootplatefenestrationorremoval.Itrevealnormalroundwindowandnormalmastoidpneumatization.DifferentialdiagnosisOssiculardiscontinuityconductivelossof60dbusuallywithoutsensorineuralcomponentflaccidtympanicmembraneonpneumaticotoscopytypeAdtympanogramDifferentialdiagnosisCongenitalstapesfixationFamilyhistorylesslikely(10%)usuallydetectedinthefirstdecadeoflife25%incidenceofothercongenitalanomalies(3%forjuvenileotosclerosis)non-progressiveCHLDifferentialdiagnosisMalleusheadfixationwhencongenital,associatedwithotherstigmata(auralatresia)presenceoftympanosclerosispneumaticotoscopyalmostalwaysassociatedwithtypeAstympanogram(onlyinadvancedotosclerosis)DifferentialdiagnosisPaget’sdisease-diffuseinvolvementofthebonyskeleton-elevatedalkalinephosphatase-CT-diffuse,bilateral,petrousboneinvolvementwithextensive-de-mineralization-Morecommonlycrowdstheossiclesintheepitympanum,partiallyfixingtheossicularchainDifferentialdiagnosisOsteogenesisimperfectapresenceofbluesclerah/oofmultiplebonefracturesCT–morecommoninvolvestheoticcapsuleandtoagreaterextentSurgicalinterventionsThebestsurgicalcandidategoodhealthwithasociallyunacceptableABG,anegativeRinnetest,excellentdiscrimination,thedesireforsurgeryafteranappropriateperiodoftimefordeliberation.Youngerpatientsaremorelikelytodevelopre-ossificationofthestapesfootplateovertheirlifetime.SurgicalinterventionsMostauthorsdiscourageperformingstapessurgeryinpatientswithMeniere'sdisease,especiallywhenitisactive.SurgicalinterventionsStapedotomyLesstraumatotheovalwindowLesspossibilityofdamagingtotheinnerearInaddition,revisionsurgery,ifrequired,iseasierduetopreservedanatomystapedectomyNon-surgicalinterventionsAmplification:hearingaidePatientswhodonotwanttoundergosurgeryforotosclerosispatientswhoarenotfitforsurgery.Non-surgicalinterventionsMedicaltreatment:Usualdoseisabout20-120mgoffluorideadayEfficacyofthetreatmentcanbe