Esophageal Motility DisordersWord文档下载推荐.docx
- 文档编号:5830712
- 上传时间:2023-05-05
- 格式:DOCX
- 页数:36
- 大小:69.88KB
Esophageal Motility DisordersWord文档下载推荐.docx
《Esophageal Motility DisordersWord文档下载推荐.docx》由会员分享,可在线阅读,更多相关《Esophageal Motility DisordersWord文档下载推荐.docx(36页珍藏版)》请在冰点文库上搜索。
Theesophagusfunctionssolelytodeliverfoodfromthemouthtothestomachwheretheprocessofdigestioncanbegin.Efficienttransportbytheesophagusrequiresacoordinated,sequentialmotilitypatternthatpropelsfoodfromaboveandclearsacidandbilerefluxfrombelow.Disruptionofthishighlyintegratedmuscularmotionlimitsdeliveryoffoodandfluid,aswellascausesabothersomesenseofdysphagiaandchestpain.Disordersofesophagealmotilityarereferredtoasprimaryorsecondaryesophagealmotilitydisordersandcategorizedaccordingtotheirabnormalmanometricpatterns.
Anatomy
Thetubularesophagusisamuscularorgan,approximately25cminlength,andhasspecializedsphinctersatproximalanddistalends.Theupperesophagealsphincter(UES)iscomprisedofseveralstriatedmuscles,creatingatonicallyclosedvalveandpreventingairfromenteringintothegastrointestinaltract.Theloweresophagealsphincter(LES)iscomposedentirelyofsmoothmuscleandmaintainsasteadybaselinetonetopreventgastricrefluxintotheesophagus.
Thebodyoftheesophagusissimilarlycomposedof2muscletypes.Theproximalesophagusispredominantlystriatedmuscle,whilethedistalesophagusandtheremainderoftheGItractcontainsmoothmuscle.Themidesophaguscontainsagradedtransitionofstriatedandsmoothmuscletypes.Themuscleisorientedin2perpendicularopposinglayers:
aninnercircularlayerandanouterlongitudinallayer,knowncollectivelyasthemuscularispropria.Thelongitudinalmuscleisresponsibleforshorteningtheesophagus,whilethecircularmuscleformslumen-occludingringcontractions.
Esophagealperistalsis
Thecoordinationofthesesimultaneouslycontractingmusclelayersproducesthemotilitypatternknownasperistalsis.Peristalsisisasequential,coordinatedcontractionwavethattravelstheentirelengthoftheesophagus,propellingintraluminalcontentsdistallytothestomach.TheLESrelaxesduringswallowsandstaysopeneduntiltheperistalticwavetravelsthroughtheLES,thencontractsandredevelopsrestingbasaltone.Lowperistalticamplitudesnormallyoccuratthetransitionzonebetweenthestriatedandsmoothmuscleportions;
however,theperistalsisisuninterrupted.
Primaryperistalsisistheperistalticwavetriggeredbytheswallowingcenter.Theperistalticcontractionwavetravelsataspeedof2cm/sandcorrelateswithmanometry-recordedcontractions.Therelationshipofcontractionandfoodbolusismorecomplexbecauseofintraboluspressuresfromabove(contractionfromabove)andtheresistancefrombelow(outflowresistance).
Thesecondaryperistalticwaveisinducedbyesophagealdistensionfromtheretainedbolus,refluxedmaterial,orswallowedair.Theprimaryroleistocleartheesophagusofretainedfoodoranygastroesophagealrefluxate.
Tertiarycontractionsaresimultaneous,isolated,dysfunctionalcontractions.Thesecontractionsarenonperistaltic,havenoknownphysiologicrole,andareobservedwithincreasedfrequencyinelderlypeople.Radiographicdescriptionofthisphenomenonhasbeencalledpresbyesophagus.
Esophagealmotilitydisorders
Esophagealmotilitydisordersarenotuncommoningastroenterology.Thespectrumofthesedisordersrangesfromthewell-definedprimaryesophagealmotilitydisorders(PEMDs)toverynonspecificdisordersthatmayplayamoreindirectroleinrefluxdiseaseandotherwisebeasymptomatic.Esophagealmotilitydisordersmayoccurasmanifestationsofsystemicdiseases,referredtoassecondarymotilitydisorders.
Esophagealmotilitydisordersarelesscommonthanmechanicalandinflammatorydiseasesaffectingtheesophagus,suchasrefluxesophagitis,pepticstrictures,andmucosalrings.Theclinicalpresentationofamotilitydisorderisvaried,but,classically,dysphagiaandchestpainarereported.In80%ofpatients,thecauseofapatient'
sdysphagiacanbesuggestedfromthehistory,includingdysmotilityoftheesophagus.Beforeentertainingadiagnosisofamotilitydisorder,firstandforemost,thephysicianmustevaluateforamechanicalobstructinglesion.
Esophagealmotilitydisordersdiscussedinthisarticleincludethefollowing:
∙Achalasia
∙Spasticesophagealmotilitydisorders,includingdiffuseesophagealspasm(DES),nutcrackeresophagus,andhypertensiveLES
∙Nonspecificesophagealmotilitydisorder(inefficientesophagealmotilitydisorder)
∙Secondaryesophagealmotilitydisordersrelatedtoscleroderma,diabetesmellitus,alcoholconsumption,psychiatricdisorders,andpresbyesophagus
Pathophysiology:
Thepathophysiologyoftheprimaryesophagealmotilitydisordersispoorlydefined,withtheexceptionofachalasia.Theunderlyingcauseofalltheprimarymotilitydisordersremainselusive.Thesecondarymotilitydisorders,suchassclerodermaesophagusoresophagealmotilitydisorderofdiabetes,arebetterunderstoodfromthestandpointofthepreexistingunderlyingdisorders.
Achalasia
Achalasiaisthebestdefinedprimarymotilitydisorderandtheonlyonewithanestablishedpathology.Thepredominantneuropathologicprocessofachalasiainvolvesthelossofganglioncellsfromthewalloftheesophagus,startingattheLESanddevelopingproximally.Thedegreeofganglioncelllossparallelsthediseasedurationsuchthat,at10years,ganglioncellsarelikelycompletelyabsent.AttheLES,thelossofinhibitorynervesisdemonstratedbylossofnitricoxidesynthaseandvasoactiveintestinalpeptide(VIP)immunohistochemistrystaining.Variableamountsofinflammatorycellshavebeendescribedwithinthemyentericplexusalongwiththedisappearingnerves.Intheperistalticesophagealbody,achalasiaischaracterizedbyalossofintrinsicacetylcholine-containingnerves.Extrinsicnervesmayalsobeaffected,characterizedbyWalleriandegenerationoftheaxoplasmandmyelinsheathswithinthevagusnerveanddorsalmotornucleus.Anatomically,thecircularmusclelayerattheLESisthickened,but,microscopically,individualmusclecellsaregrosslynormal.
Thephysiologicprocessofachalasiaiscorrelatedmostdirectlytothelossoftheinhibitorynervesatthesphincter,resultinginfailureoftheLEStocompletelyrelaxandcausingrelativeobstruction.ManometrymayrevealelevatedLESpressuregreaterthan40mmHginmorethan60%ofpatients;
however,hypertensiveLESisnotuniversalorrequiredforthemanometricdiagnosis.Thelossofnervesalongtheesophagealbodycausesaperistalsis,leadingtostasisofingestedfoodandsubsequentdilationoftheesophagus.Nonperistalticisolatedcontractionsorlow-amplitudesimultaneouscontractionsoftheesophagealbodymaybeobserved.Ifhigh-amplitude(>
60mmHg)simultaneouscontractionsoccur,theentityiscategorizedasvigorousachalasia,whichmayrepresentanearlystageofclassicachalasia.Physiologiccharacteristicsofachalasiaareadditionallyusefulinassistingwithestablishingthediagnosisthroughchemicalchallengetesting.
Withthepartialganglioncelllossinpatientswithachalasia,edrophonium(acetylcholineesteraseinhibitor)increasesLESpressurewhileatropine(muscarinicantagonist)decreasesLESpressure.Thischaracteristiclikelyexplainswhythebotulinumtoxin(acetylcholinereleaseinhibitor)mayhavetherapeuticbenefitinpatientswithachalasia.
Spasticmotilitydisordersoftheesophagealbody
Nodocumentedabnormalitiesexistregardingthedistributionofmyentericneuronsinpatientsdiagnosedwithspasticmotilitydisordersoftheesophagealbody,butdiffusefragmentationofvagalfilaments,increasedendoneuralcollagen,andmitochondrialfragmentationaredescribed.Thereappearstobeafunctionalimbalancebetweenexcitatoryandinhibitorypostganglionicpathways,disruptingthecoordinatedcomponentsofperistalsis.InDES,muscularhypertrophyorhyperplasiahasbeendescribedinthedistaltwothirdsoftheesophagus.Musclewallthickeninghasbeendescribedinpatientswhoareasymptomaticand,conversely,hasbeenabsentinsomepatientswithtypicalsymptomsandmanometricfindings.Thiscontroversialfindingcausesdifficultyinattributingsymptomsormanometricabnormalitiestomusclestructurechanges.Inaddition,anxietystatesmayalsoplayaroleinsomepatients.
Sclerodermaesophagus
Inscleroderma,theprimarydefectinthissystemicprocessisrelatedtosmoothmuscleatrophyandfibrosis.Esophagealdysmotilitydevelopsasthesmoothmuscleoftheesophagusisreplacedbyscartissue,graduallyleadingtoprogressivelossofperistalsisandaweakeningofLES.Motilityispreservedattheproximalstriatedmuscleportionoftheesophagus.
Frequency:
∙IntheUS:
Esophagealmotilitydisorders,excludingachalasia,lackpopulation-basedstudies.The2best-characterizedmotilitydisorders,achalasiaandDES,representonlyasmallpercentageofdiagnosedmotilitydisorders.Theincidenceofachalasiais1-3caseper100,000populationperyear.Aswithanyotherchronicillness,prevalenceexceedsincidencesignificantly.Familialclusteringisobserved,butageneticrelationshipisnotestablished.Nutcrackeresophagusisthemostcommonmotilitydisorder(>
40%ofallmotilitydisordersdiagnosed),butitisthemostcontroversialinsignificance.
∙Internationally:
InEurope,theincidenceofachalasiaissimilartothatoftheUnitedStates.
Mortality/Morbidity:
∙Achalasiaisassociatedwithsignificantandprogressivesymptomaticdiscomfort.Whenadvanced,thisconditioncanleadtosuchseveredysphagiathatmalnutrition,weightloss,anddehydrationcandevelop.Increasedincidenceofbothesophagealsquamouscellandadenocarcinomaisobservedin
- 配套讲稿:
如PPT文件的首页显示word图标,表示该PPT已包含配套word讲稿。双击word图标可打开word文档。
- 特殊限制:
部分文档作品中含有的国旗、国徽等图片,仅作为作品整体效果示例展示,禁止商用。设计者仅对作品中独创性部分享有著作权。
- 关 键 词:
- Esophageal Motility Disorders