医学优质ppt课件精选——《Muscular-diseases》.ppt

MusculardiseasesMusculardiseases执教教师：XXXMusculardiseasesMyastheniagravisDefinition:Myastheniagravisiscausedbyadefectofneuromusculartransmissionduetoanantibody-mediatedattackuponnicotinicacetylcholinereceptors(AChR).ClinicalCharacter:FluctuatingweaknessImprovedbyinhibitorsofcholinesteraseEtiologyandPathogenesisRelatedtodestructiveeffectsofautoantibodiestoAChREvidence:1. Experimental immunization of animalswith purified AChR from an electric fish,induces high titers of antibody to thereceptor.2.HumanserumantibodiesthatreactwithhumanAChRwerefoundinMGpatients3.Electrophysiologic features of MG wereproducedbypassivetransferofhumanIgGtomice.4.Plasmapheresisreducedplasmalevelsofanti-AChR and ameliorated myasthenicsymptomsandsigns.Howtheautoimmunedisorderstartsisnotknown.InhumanMG,hyperplasiaofthethymusabout15%ofcasesisathymoma.AChRantibodiesaresynthesizedbyBcellofhyperplasticthymusgland.Whenhumanmyasthenicthymuswastransplantedintomice,theanimalproducedantibodiestoAChRthatboundtotheirownmotorend-plates.A.Primarilyinthethymus.1.70%ofthymusglandfromadultMGpatientsarenotinvoluted.2.Thethymusweighmorethannormal.3.The thymus glands show lymphoidhyperplasia.4.Immunocytochemical:germinalcenterscontainBcells,plasmacells,andTcells.Pathology5.10% of myasthenic thymus glandscontainthymomas.B.Loss of synaptic folds and widenedcleftsC.Somenerveterminalsaresmallerthannormal.D. On residual synaptic folds show Y-shapedantibody-likestructures,IgG.Clinicalfeatures1.Incidence:0.4/100,000.Prevalence:5/100,000.Beforeage40,Male:female3:12.Symptoms:Threeclinicalcharacteristics.1)Thefluctuatingnature:Theweaknessvaries in a single day; day to day; or overlongerperiods.(remissionsorexacerbations).Crisis: When an exacerbation involvesrespiratorymuscles2)Thedistributionofweakness:A.Ocularmusclesareaffectedfirstinabout40%ofthecases(Ptosisanddiplopia).B. Affected facial oropharyngeal muscles(dysarthria, dysphagia and limination offacialmovements).C.Limbandneckweakness.Crisis:occurin:oropharyngealrespiratorymuscleweakness.provokedby:respiratoryinfectionsurgicalproceduresemotionalstresssystemicillness3).Thethirdcharacteristicistheclinical response to cholinergicdrugs.Thisoccurssouniformlythatithasbecomepartofthedefinition.3.Signs:(1)The vital signs and general physicalexamination are normal limits, unless thepatientisincrisis.(2)Weakness of the facial and levatorpalpabraemusclesproducesacharacteristicexpressionlessfaceswithdroopingeyelids.(3).Completeophthalmoplegiainoneorbotheyes(diplopia).Thepupilisneverinvolved.(4). Weakness of oropharyngeal or limbmuscles,andrespiratorymuscle.(5).Sensationisnormalandthereflexesarepreserved.1.Classification:(1)Group1.About14%ofpatientshaveocularmyastheniaonly.(2)GroupIIA.Mildgeneralizedmyastheniawithocularsigns.(3)Group IIB. Moderately severe generalizedmyasthenia, with mild bulbar and ocularinvolvement.(4)Group III. Acute severe myasthenia,withbulbarandrespiratory complications.Tracheostomyisrequired.(5)GroupIV.Lateseveremyasthenia,usuallydevelopingfromothergroupswithin2years.1.Routineexaminationsofblood,urine,andCSFarenormal.2. EMG: 90% patients have progressivedecrementintheamplitudeofmuscleactionpotentialsevokedbyrepetitivenervestimulationat3to5Hz.Laboratorytests3.AchRAntibodiestoarefoundin90%ofpatientsofallages.Thetiterdosenotmatchtheseverityofsymptoms.4.CTscansofthemediastinumdemonstrates thymomas, especially inthoseolderthan40.Diagnosis1.Characteristichistoryandphysicalexamination.2.Jollytest3.Edrophonium(Tension)tests.4.Neostigminetest:0.04mg/kg,IM,reachesitsmaximum activity in 1-2 hours. Theeffectisgoneat3-4hours.5.EMG.6.AntibotiestoAchRtest.7. CT scans of thymus. Hyperplasia orthymoma.Differentialdiagnosis:1.Botulism:presynapticblockerofacetylcholinereleasecausedbycontaminatefoodsprogressivemuscleweaknessBeginning:extraocularpharyngealmusclesTreatment:trivalentantitoxinguanidinehydrochloride2.Lambert-Eatonsyndrome(LEMS):Myasthenia-likesyndromeoccurswithcarcinomaGeneralizedmuscleweaknessThe EMG is helpful in differentiating thesyndromefromtruemyastheniagravis.Treatment with removal of the tumor andguanidinehydrochloride.Treatment1.Anticholinesterasetherapy:Anticholinesterase drug should be given assoonasthediagnosisismade.i.Pyridostigmine60mgqidii.Neostigminebromide15mgqidiii.Ifthepatientshavedifficultyeating,dosescanbetakenabout30minutesbeforeameal.2.Corticosteroidtherapy(1).High-dosecoticosteroidtherapy1). Prednisone,60-100mgdaily. Improvementbeginsatabout12days.2).Dexamethasone,20mgdailyIVfor10days.3).Prednisononmethel,480-1000mgdailyIVfor3-5days.(2).Low-dosecorticosteroidtherapy:prednisone25mg,qod,graduallyincreasingthedosageby12.5mgeveryweekuntilthetotal dosage reaches 100 mg on alternatedays.3.Immunotherapy(1).Azathioprine,50-100mg,twiceaday.(2).Cyclophophamide100mg,twiceaday.3.Thymectomy:About80%ofpatientswithoutthymomabecomeasymptomaticorgotocompleteremissionafterthymectomy.4.Plasmapheresis:Toremovetheharmfulantibody.6.Treatmentofcrisis(1).Myastheniccrisis:needassistedventilationabout10%ofmyas。