ClinicalElectromyography

ClinicalElectromyographyNerveConductionStudies01013PrinciplesAnalysisofthecompoundmuscleactionpotential(CMAP),evokedbystimulatinganervewhilerecordingfromamuscle,indirectlyassessestheconductioncharacteristicsofmotorfibers.Analysisofthesensorynerveactionpotential(SNAP)assessesthesensoryfibersbystimulatinganerveandrecordingdirectlyfromacutaneousnerve.Electricalstimulationofnervefibersinitiatesimpulsesthattravelalongmotor,sensory,ormixednervesandevokeacompoundactionpotential.4MotorNerveConductionStudiesSensoryNerveConductionStudies015Amplitude波幅isasemiquantitativemeasureofthenumberofaxonsconductingbetweenthestimulatingandrecordingpoints.alsodependsontherelativeconductionspeedoftheaxons,theintegrityoftheneuromuscularjunctions,andthenumberofmusclefibersthatareabletogenerateactionpotentials.016Axonloss017Latency潜伏期reflectstheconductionrateofthefastest-conductingaxonThenerveisstimulatedattwopoints:adistalpointneartherecordingsiteandamoreproximalpoint;Bothlatenciesdependmostlyonthelengthofthenervesegmentand,toamuchlesserextent,onneuromusculartransmissiontimeandpropagationtimealongthemusclemembrane.018Velocity速度Stim1Stim2记录.019Demyelination0110Duration时程Itisafunctionoftheconductionratesofthevariousaxonsformingtheexaminednerveandthedistancebetweenthestimulationandrecordingelectrodes.0111Focaldesynchronized0112ComputerizedmodelofmotornerveconductionstudyofaperipheralnerveNormalnerveAxonaldegenerationsegmentaldemyelination病理表现Nomal正常Axonloss轴突变性Demyelination髓鞘损伤Conductionblock传导阻滞0114CMAPshowingtherelationshipbetweenfast-conducting(F)andslow-conducting(S)motorfibersWithdistalstimulation,twounitdischargesrepresentingmotorunitpotentialssumtoproduceamuscleactionpotentialtwiceaslargeWithproximalstimulation,motorunitpotentialsoflongdurationstillsuperimposenearlyinphasedespitethesamelatencyshiftoftheslowmotorfiber.Thus,aphysiologicaltemporaldispersionaltersthesizeofthemuscleactionpotentialonlyminimally0115SNAPshowingtherelationshipbetweenfast-conducting(F)andslow-conducting(S)motorfibersWithdistalstimulation,twounitdischargessuminphasetoproduceasensoryactionpotentialtwiceaslargeWithproximalstimulation(bottom),adelayoftheslowfibercausesphasecancellationbetweenthenegativepeakofthefastfiberandpositivepeakoftheslowfiber,resultingina50%reductioninsizeofthesummatedresponse.0116Simultaneousrecordingsof(CMAPs)fromthethenareminenceandSNAPsfromindexfingerafterstimulationofthemediannerveatpalm(P),wrist(W),elbow(E),andaxilla(A).Withprogressivelymoreproximalstimulation,CMAPsremainednearlythesame;forSNAPs,however,bothamplitudeandtheareaunderthewaveformbecamemuchsmaller.17Inchingtechnique(SegmentalStimulationinShortIncrements)节段性刺激技术0118Twelvesitesofstimulationin1-cmincrementsalongthelengthofthemediannerve.The0levelisatthedistalcreaseofthewrist,correspondingtotheoriginofthetransversecarpalligament.InchingtechniqueSNAPsinanormalsubjectrecordedafterstimulationofthemediannerveatmultiplepointsacrossthewrist.Thelatencychangesincreasedlinearly(approximately0.16to0.21msec)asthestimulussitewasmovedproximallyin1-cmincrements.19SNAPinapatientwithbilateralcarpaltunnelsyndromeLoremipsumdoloramet,consecteturadipisicing.Loremipsumdoloramet,consecteturadipisicing.Asharplylocalizedslowingwasfoundfrompoint−2topoint−1inbothhands,withalatencychangemeasuring0.7msecontheleft(A)and1.1msecontheright(B),comparedwiththeothersegmentswithnormallatencychangesofapproximately0.16to0.21ms.SpecializedElectrodiagnostic020221FWaveAsupramaximalstimulusappliedatanypointalongthecourseofamotornerveelicits:CMAP(Mresponse):orthodromicallydepolarizethemusclegenerateaCMAPFwave:antidromicallytowardthespinalcordtotriggeranFwave.0222NormalFwavesrecordedfromthehypothenarmusclesaftersupramaximalstimulationsoftheulnarnerveatthewristTheFwavevariesinlatency,morphology,andamplitudewitheachstimulusbecauseadifferentpopulationofanteriorhorncellsbackfires.Therefore,anadequatestudyrequiresthatabout10Fwavesbeclearlyidentified.Themostsensitivecriterionofabnormalityisaminimumlatencydifferencebetweenthetwosides.0223HReflexTheHreflexisbestelicitedbyalong-durationstimulus,submaximaltoproduceanMresponse,whereastheFwaverequiressupramaximalstimulusintensityIncontrastwiththeFwave,whichcanbeelicitedfromanylimbmuscle,theHreflexfromstimulatingthetibialnervewhilerecordingthesoleusmuscle(S1arcreflex)0224HReflex刺激混合神经干而强度尚不足以刺激运动神经引起M反应时，即刺激了感觉神经，兴奋经后根至脊髓前角细胞，引起兴奋，产生肌肉反应，即H反射.0225HReflexTheHreflexisbestelicitedbyalong-durationstimulus,submaximaltoproduceanMresponse,whereastheFwaverequiressupramaximalstimulusintensityIncontrastwiththeFwave,whichcanbeelicitedfromanylimbmuscle,theHreflexfromstimulatingthetibialnervewhilerecordingthesoleusmuscle(S1arcreflex)0226HReflexHreflexamplitude,Hmax/Mmaxcanbeusedasquantitativeindicatorsofmotorneuronsexcitabilitiesoflowerextremityinspasticpaitent．NeedleElectromyographic030228运动单位是指由一个前角细胞及其轴突所支配的肌纤维，是肌肉收缩的最小功能单位。0229NormalInsertionalandSpontaneousActivityEnd-platenoise(solidarrows)andspikes(dashedarrow)representingnormalinsertionalandspontaneousactivities0