声导抗基础知识

Soundtravel声音传导2020/11/302Gettingsoundintoadifferentmedium

声音在不同媒介中的传导Mostofthesoundenergyisreflectedwhenconfrontingaanothermedium...大部分声能在临界面处被反射回来…becausedifferentmediaaremoreorlesseasytobringintomotion(impedance)因为不同媒介的声阻抗是不同的2020/11/303Theroleofthemiddleear中耳的作用

2020/11/304TheOssicles听小骨Malleus锤骨Incus砧骨Stapes镫骨Threesmallbonesformingachainbetweenthetympanicmembraneandtheinnerear听骨链位于鼓膜和内耳之间，由3块听小骨组成Airbornesoundwaveenergybecomesmechanicalvibration空气传导的声波能量转换为机械振动Compensatesfortheair-fluidimpedancedifference补偿气液相不同媒介的导抗差2020/11/305TheMiddleearanatomy中耳解剖AirAirAirpressuremustbenearequalonbothsidesoftheeardruminordertooptimisemobilityofthewholesystem应使鼓膜两侧气压接近，从而保证中耳传声系统的最佳活动性TheEustachiantube(ET)ventilatesthemiddleearandallowspressureequalisation咽鼓管是中耳的通气管道，可保证中耳气压平衡TheETopenswhenswallowingoryawning吞咽和打哈欠时咽鼓管开放Innerearfluids内淋巴2020/11/306Gettingsoundintoadifferentmedium

声音在不同媒介中的传导The“stiletto”principle:圆锥效应Forceiscollectedoveralargerareaandfocusedonasmallerarea(B)作用力在锥底收集后聚焦到锥尖2020/11/307Howdowetestthemiddleear?

如何检测中耳功能2020/11/308中耳测试精密的中耳系统高精度的测试高质量控制系统2020/11/309Partoftheprobetoneisreflected,andsomeisadmittedintothemiddleear一部分探测音被反射回来，另一部分则进入中耳Theadmittanceiscontinuouslymeasuredbyamicrophone声导纳通过麦克风持续测量计算出来Admittance-lettingthesoundwavein

声导纳－将声波导入2020/11/3010鼓室图中耳–劲度TPP(=MEP?)AdmittancePressure2020/11/3011Tympanometry鼓室声导抗Admittance-200daPa200daPa0EarcanalpressureAdmittance声导纳-200daPa200daPa0Earcanalpressure外耳道压强1&3:Pressurestiffensthetympanicmembranesotheprobetonebouncesback,andthesoundlevelinthemiddleeardecreases1和3：大压强使鼓膜僵硬从而探测音多被反弹回来，进入中耳的声能减少2:Whenpressureisequalonbothsides,thesoundlevelinthemiddleearisatmaximum2：鼓膜两侧压力相等时传入中耳的声能最大

1232020/11/3012TheTympanogramcurve,ECVandTPP

鼓室导抗图形，等效外耳道容积和峰压点TheTPPapproximatesthemiddleearpressure峰压点近似于鼓膜内侧的中耳压力ECVTotalAdmittanceoftheearcanalandthemiddleear外耳道和中耳的声导纳总值TPPPressuresweepThe226Hzadmittanceoftheairintheearcanalisdirectlyproportionaltothevolumeofthatair.ThatgivesustheEquivalentEarCanalVolume,ECV以226Hz为探测音，测试探头与鼓膜之间的空气导纳值为外耳道容积，即等效外耳道容积2020/11/3013ECVTotalAdmittanceSATPPSATPPTheTympanogramcurveandbaselinecompensation鼓室导抗图形和基线补偿SubtractionoftheECVcontributiongivesusabaselinecompensatedtympanogram去除外耳道容积成分后的鼓室图称为基线补偿鼓室导抗图PeakadmittancebecomesStaticAdmittance,SA该图峰值处的声导纳称为静态声导纳(SA)TheSAistheadmittanceofthemiddleearalone.Nowwecanusethenormativedata!SA等于中耳的声导纳值2020/11/3014-2002000TypeAd:OssiculardiscontinuityoragerelatedhypermobilityAd型：听骨链中断或鼓膜松弛-2002000TypeA:NormalA型：正常-2002000TypeB:“Flat”-EffusionorperforatedeardrumdependingonECVvalueB型：平坦型。鼓室积液或鼓膜穿孔，根据ECV值区分-2002000TypeAs:PossibleeffusionorotosclerosisAs型：鼓室积液可能或耳硬化症-2002000TypeC:AbnormalpressureC型：负压型TheTympanogramcurveclassification,Type鼓室导抗图形分类2020/11/3015SATWSA/2PressureAdmittanceTheTympanogramcurveandTympanometricWidth

鼓室导抗图形与鼓室图宽度（TW）TympanometricWidthquantifythesteepnessofthetympanogramTW决定鼓室导抗图的坡度Normativedataexistfordifferentagegroups不同年龄组标准化值不同TWandSAarethecriteriausedintheASHAtympanometricscreeningprotocol美国社会卫生学会的鼓室声导抗筛查方案把TW和SA作为诊断指标2020/11/3016226Hz:Differentconfigurationsoftympanometricresults

226Hz鼓室声导抗测试结果与疾病的关系Tympanometryisaninvaluablediagnostictoolwhencombinedwithotheraudiologicaltests鼓室声导抗与其它听力学测试结合是不可替代的诊断工具疾病早期中耳积液中耳积液听骨链中断鼓膜病变耳硬化症锤骨固定咽鼓管阻塞鼓膜置管鼓膜穿孔耵聍栓塞、探头叩堵塞2020/11/3017Thetwomiddleearmuscles中耳肌121:Tensormuscle鼓膜张肌2:StapediusMuscle镫骨肌Themusclesarebelievedtostabilisethemechanicalsystemandprotectthecochleafromexcessivelowfrequencyvibration中耳肌可稳定中耳机械系统，并保护耳蜗免受低频强声损伤2020/11/3018TheAcousticReflex声反射Loudsoundsmakethestapediusmusclecontract.Thismakesthemiddleearsystemstiffer...强声刺激可使镫骨肌收缩，从而增加中耳传声系统的劲度…andlesslowfrequencysoundcangetthroughthemiddleear因而进入中耳的低频声波减少2020/11/3019Stapediusmusclecontrolledbyfacialnerve(CNVII)

镫骨肌由第七对颅神经－面神经支配Networkinbrainstemconsistsofipsilateralandcontralateralpaths

脑干层面由同侧和对侧神经通路组成Reflexactivatedonbothears,evenwhenstimulationonlyoccursinoneear

一侧耳受到刺激时，双侧镫骨肌都会收缩Comparisonofipsilateralvs.contralateralacousticreflexeshelpstodeterminesiteoflesion

对比同侧和对侧声反射有助于判断病变部位TheMiddleear-Immittancetests中耳声导纳测试Acousticreflexthreshold声反射阈2020/11/3020声反射AdmittanceTimeDeflection0.02蹬骨肌2020/11/30210.000.0280dBHL0.000.0285dBHL0.000.0295dBHL0.000.0290dBHLDeflectioncriterion声导纳偏移标准Itisusefultostudythegrowthwithintensitytoconfirmareflexthreshold继续增加声强观察偏移变化有助于进一步明确声反射阈?!AcousticReflexThresholds声反射阈Loudstimuliarepresented,whilsttheadmittanceismeasured强声刺激出现时，可测试出声导纳值的变化2020/11/3022声反射测试–高精度的挑战鼓膜处压力为TPP值时中耳蹬骨肌反射状况最佳正确的声反射是刺激音引起导纳在TPP处的变化耳道或中耳压力的改变导致错误的声反射对于鼓膜活动度过大可进行TPP补偿2020/11/3023Threshold+10dB,10secondsstimulustime声反射阈上10dB给声，刺激时程10s0510secondsAdmittancechangeHalf-LifeTime(HLT),thetimeafterstimulusonsetwhentheadmittancedeflectionhasdecreasedby50%.半衰期是指声反射振幅减少50％的时程Ahalf-lifetimevalue<5secondsisindicativeoftumour半衰期小于5秒提示蜗后病变，常见的疾病是听神经瘤Noreflexdecaypresent阴性AdmittancechangeMax50%ofMaxHLT0510secondsReflexdecaypresent!阳性AcousticReflexDecay声反射衰减2020/11/3024Thereflexshouldbeactivatedinbothearsevenifstimulatedinonlyoneear单耳刺激声可激活双耳声反射Theuppernormalintensitylimitforreflexthresholdsinadultsis95-100dBHL正常成人声反射阈上限是95－100dBHLReflexthresholdscannotbedeterminedifthereisaproblemwiththemiddleear

中耳疾病时不能测出声反射阈BroadBandNoiseprovokesareflexatabout10-15dBlowerthanpuretonestimuli宽带噪声声反射阈较纯音刺激声低10－15dBDeterminestypeofhearinglosswhencomparedwiththeaudiogram声反射阈与听力图比较可帮助判断耳聋类型Decayswithneuralfatigue(typically8thnervetumour)

衰减提示听神经疲劳，是听神经肿瘤的典型表现AcousticReflexfeatures声反射特征2020/11/3025DifferentconfigurationsofAcousticReflexresults声反射结果与疾病的关系Usingthiskindoftablemakesreflexinterpretationeasier使用该表格有助于判断声反射的临床意义病变部位/患耳中耳/右中耳/左耳蜗/右耳蜗/左听神经/右听神经/左面神经/右面神经/左脑干/右脑干/左脑干/中线2020/11/3026226Hzprobetone:Normaltympanograminabnormalear!226Hz探测音：异常中耳显示正常鼓室导抗图Tympanometryininfantsyoungerthan4-7months4－7个月以下婴儿的鼓室声导抗226HzprobetoneTheinfantouterandmiddleearsarestilldeveloping,anddonotvibratewithsoundthesamewayadultearsdo.婴儿外耳和中耳正处于发育期，与成人的声波振动方式不同Use1000Hzprobetoneininfants推荐使用1KHz探测音2020/11/3027Tympanometryininfants婴儿鼓室声导抗1000Hztympanometryclearlyindicatesabnormalmiddleearfunction!1kHz鼓室声导抗明确显示中耳功能异常Normal226Hztympanogramsforbothears!226Hz鼓室声导抗显示双耳正常Acousticreflexesconfirmahealth