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1、 Advancesinneurobiologyoftinnitusandhyreracusis耳鸣和听觉过敏的神经生物学研究进展杨明建2014 12 16 研究背景 Hearingimpairmentisaconsiderablediseaseburden Ithasbeenestimatedthatadult onsethearingimpairmentisthethirdleadingcauseofdisability WHO 2008 Forty twopreviousreportspublishedbetween1973and2010in29countrieshaverevealedi
2、ncreasedhearinglosswithage Developingcountriesreporthigherratesofmoderateandmoderately severehearingimpairmentduetohigherratesofpre andpostnatalchildhoodinfectionssuchasrubella 风疹 measles 麻疹 andmeningit 脑膜炎 andfromtheuseofototoxicdrugs 耳毒性药物 Stevensetal 2013 However inindustrializedcountries noise i
3、nducedhearingloss NIHL 噪声性听力损失 isacommoncauseofhearingimpairments Luetal 2005 withaprevalencethatissecondtopresbycusis 老年性耳聋 Stanburyetal 2008 Hyperacusiandtinnitusarepotentiallydevastatingconditionsthatarestillincurable Epidemiology 流行病学 oftinnitus Tinnitusisadisorderofperceptionofphantomsoundthati
4、salsoknownasringingintheearorhead Tinnitusaffects10 20 ofthegeneralpopulation Galazyuketal 2012 Shargorodskyetal 2010 AccordingtotheAmericanTinnitusAssociation anestimated50millionpeopleintheUnitedStateshavechronictinnitus persistingforlongerthansixmonths Shargorodskyetal 2010 For12millionindividual
5、s itissevereenoughtointerferewithdailyactivities Tinnituscanoccurinchildren ShetyeandKennedy 2010 andprevalenceincreaseswithage Adamsetal 1999 AhmadandSeidman 2004 peakingbetween60and69yearsofage Shargorodskyetal 2010 Morecommoninmenthaninwomen morelikelyinformersmokers andinadultswithhypertension h
6、earingimpairment loudnoiseexposure orgeneralizedanxietydisorder 广泛性焦虑障碍 Shargorodskyetal 2010 Hearinglossandstress emotionalaswellaspsychosocial areimportantriskfactorsfortinnitus Hebertetal 2012 Jastreboff 2007 Langguthetal 2009 althoughtinnituscanoccurindependentlyfrombroadincreaseofhearingthresho
7、lds Gevenetal 2011 Langersetal 2012 Lockwoodetal 2002 耳鸣的分类 耳鸣有间歇性 也有持续性 有单一频率窄带噪音或白噪音等多种表现 耳鸣一般可分为中枢性及周围性两大类 周围性耳鸣根据是否被别人听见分为主观性耳鸣和客观性耳鸣 前者多见 后者少见 耳鸣又可根据其特征分为持续性耳鸣与节律性耳鸣 持续性耳鸣可有单一频率或多频率声调的混合 多为主观性耳鸣 节律性耳鸣多与血管跳动一致 偶尔与呼吸一致 耳鸣的频率较低 如为肌肉收缩引起 则耳鸣的频率较高 节律性耳鸣 多为客观性耳鸣 Epidemiology 流行病学 ofhyperacusis Hypera
8、cusisisadisorderofloudnessperception 响度感知紊乱 inwhichsoundintensitiesthatareconsideredcomfortablebymostpeopleareperceivedunbearablyloud Baguley 2003 Inhyperacusis soundsarenotsimplyabitloud buttrulyunbearable 难以忍受 Hyperacusiscanoccurwithoutalossofhearingthresholds Guetal 2010 Statisticsonhyperacusisar
9、escarce andalthoughitisoftencoincidentwithtinnitus limitedevidencehassupportedtheco occurrenceofthetwoconditions Anderssonetal 2002 Guetal 2010 NelsonandChen 2004 Withanapproximateprevalenceofabout10 15 ofthepopulation Gillesetal 2012 theprevalenceofhyperacusisiscomparabletotinnitus Shargorodskyetal
10、 2010 Fortinnitusandhyperacusis hearingloss however isamajorriskfactor Astheincidenceofhearinglosswillincreasewiththeagingofthepopulation alsotheincidenceoftinnitusandhyperacusismayincrease Aretinnitusandhyperacusisintheearorthebrain 越来越多的证据表明耳鸣和听觉过敏形成的机制中外周听觉器官损伤只是起因 耳鸣和听觉过敏的形成和维持更多的是听觉传导通路上各级中枢的作用
11、 耳蜗损伤等造成的异常神经活动经中枢核团逐级传递并在边缘系统等非听觉系统的参与下最终在听皮层被感知为耳鸣 M Knipper P V Dijk I Nunes etal Advancesintheneurobiologyofhearingdisorders RecentdevelopmentsregardingthebasisoftinnitusandhyperacusisProgressinNeurobiology 111 2013 17 33J J Eggermont L E Roberts Theneuroscienceoftinnitus TRENDSinNeurosciences 2
12、7 2004 676 682 Fig 1 SchematicillustrationoftheadultorganofCorti ThenervefibersofIHCs 内毛细胞 sendinformationtothebrain whereasthenervesofOHCs 外毛细胞 mainlyreceiveinformationfromthebrain IHCsare therefore thetruesensorycellsofhearing OHCsarecharacterizedbytheirelectromotileproperties theyareresponsiblefo
13、rtheamplificationoftheacousticsignal whichinturnactivatesIHCs TheIHCstransmitelectricalsignalsinafrequency specificmannertohigherauditorybrainareas 内耳柯蒂氏器 螺旋器 示意图 1 cochleardamage NIHL 噪声性听力损失 hasbeen inapreviousview typicallydefinedbyapermanentlossofhearingthresholds 听阈永久性损失 Normalthresholdsrelyont
14、heproperfunctionofouterhaircells OHCs DallosandHarris 1978 Perinnerear thereareapproximately11 000OHCs whichare inthehumancochlea typicallyarrangedin3rows Fig 1 OHC OHCfunctionistononlinearlyamplifybasilarmembranevibrationinresponsetosoftsoundsneartheplaceofcharacteristicfrequencywithinthecochlea As
15、hmore 2008 OHCsarethereforecrucialforthehighsensitivityofthehearingorgan itsfrequencyselectivity andunderstandingspeechinnoise Ashmore 2008 Dallos 2008 Aftermildacousticoverexposure hearingfunctioncanrecoverwithin2 3weeks Milleretal 1963 Thiscorrespondstoatemporarythresholdshift 暂时性阈移 duetoreversibl
16、edamagetothemechanosensoryhairbundlesofhaircells Fig 1 stereocilia LibermanandDodds 1984a b Schneideretal 2002 Afterintenseorrepeatedacousticoverstimulation however hearingfunctionstabilizesatanelevatedvalue leadingtopermanentthresholdshift 永久性阈移 thatmostlyoccursduetodestructionofOHCs Spoendlin 1985 Inthedailyclinicalroutine permanenthearinglossistypicallydetectedthroughtheincreaseofhearingthresholdsastestedbytone audiometry 听力测定 Moredetailedclinicaldiagnostictestingmayalsoincludeauditorybrainst
