GE CARESCAPE - AEP practicalities; AEP measurement description; Main peak categories (AEP); Examples of typical AEP patterns

EEGandauditoryevokedpotentials
AEPpracticalities
AEPmeasurementdescription
Evokedpotentials(EP)areresponsesofthecentralnervoussystemtoexternal
stimulation.Commonevokedpotentialsaretheauditoryevokedpotentials(AEP),
somatosensoryevokedpotentials(SSEP),andvisualevokedpotentials(VEP).
Evokedpotentialsaremeasuredbystimulationandestimatingtheresponse.The
evokedpotentialsarelargelyaffectedbythesamethingsastheEEG.Integrityof
neuralpathwaysbringstheinformationtothecortex.Examplesofdecitsinthe
pathwaysareslower,smallerresponses(loweramplitudes,longerlatencies).
Auditoryevokedpotentials(AEP)aretransientresponsestoanauditorystimulus,
whichisusuallygiventhroughheadphones.AEPsreectthefunctionoftheauditory
pathway.Tocreateadistinguishableresponse,alargeamountofresponsesare
averagedandtheresultsaredisplayedasawaveform.
DuringAEPmonitoring,theAEPelectrodesarealsousedforEEGmonitoring.TheAEP
measurementcanbestartedmanually,repeatedautomaticallyaftersetintervals,or
themeasurementcanbecontinuouswithmovingaveraging.
Mainpeakcategories(AEP)
Latenciesandamplitudesofparticularpeaksareimportantinformation.Latencyis
thetimetothepeak,andamplitudeistheheightofthepeak.Typicallyinanesthesia,
forexample,corticallatenciesgrowlongerasanesthesiastartstotakeeffectinthe
brain.Threemaingroupsofpeakscanbedistinguished,andtheycanbecorrelatedto
anatomicalstructures.
●BrainstemAEP(BAEP)
￭withlatenciesshorterthan10ms
￭cochlea,acousticnerve,brainstem
●MiddlelatencyAEP(MLAEP)
￭withlatenciesfrom10msto100ms
￭primaryauditorycortex(temporallobe)
●LonglatencyAEP(LLAEP)
￭withlatenciesfrom100msto1000ms
￭frontalcortex
NOTE
LLAEPdisplayisnotsupportedinthemonitor.
ExamplesoftypicalAEPpatterns
AEP1msto1000mswithanatomicalsitesandlabeling:
2062971-001CARESCAPEModularMonitors391