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ID:20015116
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页数:43页
时间:2018-10-09
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1、MyastheniaGravis重症肌无力DepartmentofNeurologyXuanwuHospitalMuscularDisordersDisordersoftheneuromuscularjunctionDisordersofmusclefibersDisordersoftheNeuromuscularJunctionPresynapticmembraneLambert-EatonsyndromeBotulismSynapticcleftOrganophosphateintoxicationPostsynapt
2、icmembraneMyastheniagravisDisordersofMuscleFibers(Myopathies)MusculardystrophiesCongenitalmyopathiesMembranemyopathies(chanelopathies)InflammatorymyopathiesMetabolicmyopathiesI.DefinitionofMyastheniaGravisMGisadisorderoftheneuromusculartransmissionowingtoantibody
3、-mediatedattackonacetylcholinereceptors(AchR)atneuromuscularjunctions.Muscleweaknessoccursinassociationwithcontinuouseffort,andimproveswithrest.Ⅱ.EtiologyandPathogenesisAnautoimmunemechanism,operativeattheneuromuscularjunctionWeaknessandfatigueareduetothefailureof
4、effectiveneuromusculartransmission.Neuromuscularjunctions1.ReducedNumberofReceptorsandtheCompetitiveActivityofAnti-AchRAntibodies85%ofpatientswithgeneralizedMG60%ofthosewithocularMGarepositiveforanti-AChRantibody.MuscleAChR(Adult)AchBindsAChRHowtheantibodiesactatt
5、hereceptorsurfaceoftheendplateandimpairtheneuromusculartransmission?(1)BlockthebindingofAchtotheAchreceptors(2)IncreasethedegradationrateofAchRs.(3)Complementmediateddestructionofpostsynapticfolds2.TheroleofthymusinpathogenesisofMGThethymusisanorganthatproducescel
6、lsinvolvedinimmuneresponses.Approximately15%ofMGpatientshaveatumorofthethymus(thymoma)And60%haveabnormalenlargement(hyperplasia)ofthethymus.BothTandBcellsfromthemyasthenicthymusareparticularlyresponsivetotheAchR,moresothananalogouscellsfromperipheralblood.Moreover
7、,thethymuscontains“myoidcells”(resemblingstriatedmuscle)thatexpresssurfaceAchRs.MaybeaviruswithtropismforthymiccellsthathaveAchRsmightinjuresuchcellsandinduceantibodyformation.Ⅲ.PATHOLOGYOFMG1.THYMUS15%ofMGpatientshavethymoma60%havehyperplasiaofthethymus2.Patholog
8、yofskeletalmuscles:Inabout50%ofpatients,musclescontainlymphorrhages,whicharefocalclustersoflymphocytesnearsmallnecroticfociwithoutperivascularpredilecti
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