Objective:Tobetterunderstandthecharacteristicsoftheneurogenicmotorevokedpotential(NMEP)beforeandafteracutespinalcordinjury.Methods:WerecordedandcharacterizedthespinalcordNMEPfrom48normalratsandfrom38ratswithspinalcordhemisectionlesion.SpinalcordNMEPswereelicitedbyapplyingarangeofcurrentintensitieswithbipolarmicroelectrodestimulitotheC4cordsegmentandrecordingtheresponsesfromsciaticnerveswithbipolarmicroelectrodesplacedintheneurilemma.Results:Theevokedpotentialsconsistedofthreestableandreproduciblenegativeandthreepositivepeaks.Themean±SDlatenciesofN1were2.89±0.22msontherightsideand2.89±0.24msontheleftside.Themeanconductionvelocitywas47.9m/s.Themean±SDamplitudesofN1were3.61±2.10μVontherightsideand3.83±2.32μVontheleftside.TheamplitudesofN1weresignificantlydifferentamongtheeightstimulusintensitygroups(rightside:F=2.22,df=7201,P=0.03;leftside:f=2.11,df=7206,P=0.04).Theamplitudewaslargestwhenthestimulusintensitywas1.1-2.5mA.ThelatenciesofN1werenotsignificantlydifferentamongtheeightstimulusintensitygroups(rightside:F=0.40,df=7201,P=0.9;leftside:F=1.20,df=7206,P=0.3).TheamplitudesandlatenciesofN2,N3werenotsignificantlydifferentamongtheeightstimulusintensitygroups.Therewerenosignificantchangesinlatencyandamplitudebetweentheleftandtherightsidenerveresponses.Thirty-eightratsundewentT9cordrightsidehemisection.Amongthem,20(53%),30(79%),and32(84%)ratscouldnotberecordedincorrespondingtoN1,N2,andN3,respectively,intheright-sidesciaticnerves;and13(79%),18(47%),and21(55%),incorrespondingtoN1,N2,andN3intheleft-sidesciaticnerves.Thelatencywassignificantlydelayedonthebothrightandleftsides.TheamplitudeN1wassignificantlydepressedonthebothsides,withN3significantlydepressedontherightsideandN2notsignificantlydepressed.Conclusions:TheamplitudeofNissignificantlydiffere
