InstructionmanualfortheILAE2017operationalclassicationofseizuretypesR - PDF document

InstructionmanualfortheILAE2017operationalclassiÞcationofseizuretypesRobertS.Fisher,J.HelenCross,CarolDÕSouza,JacquelineA.French,SherylR.Haut,NorimichiHigurashi,EdouardHirsch,FloorE.Jansen, Dr.RobertS.FisherpastpresidentofAESandeditorofandepilepsy.com,ledtheSeizureClassificationTask UMMARY AcceptedDecember21,2016;EarlyViewpublicationMarch8,2017.StanfordDepartmentofNeurology&NeurologicalSciences,Stanford,California,U.S.A.;UCL-InstituteofChildHealth,GreatOrmondStreetHospitalforChildren,London,UnitedKingdom;BombayEpilepsySociety,Mumbai,India;DepartmentofNeurology,NYULangoneSchoolofMedicine,NewYork,NewYork,U.S.A.;MontefioreMedicalCenter,AlbertEinsteinCollegeofMedicine,Bronx,NewYork,NewYork,DepartmentofPediatrics,JikeiUniversitySchoolofMedicine,Tokyo,Japan;UniteFrancisRohmer,Strasbourg,France; ILAECOMMISSIONREPORT KeyPointsTheILAEprovidedarevisedbasicandexpandedsei-zuretypeclassification,withinitialdivisionintofocalversusgeneralizedonsetorunknownonsetseizuresFocalseizuresareoptionallysubdividedintofocalawareandfocalimpairedawarenessseizures.SpecificmotorandnonmotorclassifiersmaybeaddedGeneralized-onsetseizurescanbemotor:tonicnic,clonic,tonic,myoclonic,myoclonicnic,myoclonicatonic,atonic,andepilepticspasmsGeneralized-onsetseizurescanalsobenonmotor(ab-sence):typicalabsence,atypicalabsence,myoclonicabsence,orabsencewitheyelidmyocloniaAdditionaldescriptorsandfreetextareencouragedtocharacterizetheseizures.MappingofoldtonewtermscanfacilitateadoptionofthenewterminologyTheInternationalLeagueAgainstEpilepsy(ILAE)hasreleaseda2017versionofseizure-typeclassification(ac-companyingmanuscript).Revisionoftheclassificationthathasbeenusedinmodifiedformsince1981wasmotivatedbyseveralfactors.Someseizuretypes,forexampletonicseizuresorepilepticspasms,canhaveeitherafocalorgen-eralizedonset.Lackofknowledgeabouttheonsetmakesaseizureunclassifiable.Sometermsusedtoclassifyseizureslackcommunityacceptanceorpublicunderstanding,includingdyscognitive,partial,simplepar-tial,complexpartial.Determiningwhetherapersonhasimpairedconsciousnessduringaseizurecanbeconfus-ingfornonclinicians.Someimportantseizuretypesarenotincludedinthe1981classification.Thenewclassificationaddressestheserelevantissues.Materialthatfollowsexplainshowtoapplythe2017seizure-typeclassification.Classificationofaseizurebeginswithhistoricalelicita-tionorobservationofcertainsymptomsandsigns(some-timesreferredtoasthesemiologyofseizures)thatareknowntobeassociatedwithcommonseizures.Thekeysymptomsandsignscannotbematchedinone-to-onerela-tionshipswithseizuretypesbecausesomesymptomsappearinmorethanoneseizuretype.Behaviorarrest,forexample,occursinbothfocalimpairedawarenessseizuresandabsenceseizures.Tonicclonicactivitycanbepresentfromonsetinageneralizedseizureoremergeinthecourseofafocal-onsetseizure.Conversely,aseizuretypeoftenassoci-ateswithmultiplesymptoms.Namingaseizuretypeantomatismseizurewouldnotallowthedistinctionbetweenafocalseizurewithimpairedawarenessandanabsencesei-zure.Becausethesetwoseizuretypesaretreateddifferentlyandhavedifferentprognoses,maintenanceofdistinctsei-zuretypesisuseful,eventhoughsomeinterpretationbeyonddirectobservationmaybeneededtoclassifythesei-zures.Distinctionofseizuretypesusuallycanbemadebyrecognizingacharacteristicsequenceofsymptomsandotherclinicalobservations.Typicalabsenceseizures,forinstance,showmorerapidrecoveryoffunctionthandofocalimpairedawarenessseizures.Insomeinstances,ancil-laryinformationfromelectroencephalography(EEG),imaging,orlaboratorystudiesisneededtoproperlyclassifyaseizure.Forthesecases,classificationofseizuretypebeginstomergeimperceptiblywithdiagnosisofepilepsysyndromes.Becausewelackafundamentalpathophysio-logicunderstandingofdifferingseizurepresentations,groupingofsymptomsandsignsintoseizuretypesreflectsanoperationalopinionaboutwhichgroupingsaresuffi-cientlydistinctandcommonastomeritaspecificname.Thisclassificationisderivedforpracticalclinicaluse,butitalsocanbeusedbyresearchersandothergroupswithspeci-ficpurposes.ResultsTheILAE2017seizureclassificationpresentsbasicandexpandedversions,dependingonthedesireddegreeofdetail.Thebasicversion

isthesameastheexpandedver-sion,butwithcollapseofthesubcategories.BasicclassificationFigure1showsthebasicclassification.Seizuresarefirstcategorizedbytypeofonset.Focal-onsetseizuresaredefinedasoriginatingwithinnetworkslimitedtoonehemisphere.Theymaybediscretelylocalizedormorewidelydistributed.Focalseizuresmayoriginateinsubcorti-calstructures.Generalizedfromonsetseizuresaredefinedoriginatingatsomepointwithin,andrapidlyengaging,bilaterallydistributednetworks.Aseizureofunknownonsetmaystillevidencecertaindefiningmotor(e.g.,tonicclonic)ornonmotor(e.g.,behaviorarrest)characteristics.Withfurtherinformationorfutureobservedseizures,areclassificationofunknown-onsetseizuresintofocalorgen-eralized-onsetcategoriesmaybecomepossible.Therefore,unknown-onsetisnotacharacteristicoftheseizure,butaconvenientplaceholderforourignorance.Whenaseizuretypebeginswiththewordsgeneralized,sence,thenthewordmaybepresumed.Furtherclassificationisoptional.Thenextleveloffocalseizureclassificationisbylevelofawareness.Awarenessisoperationallydefinedasknowledgeofselfandenviron-ment.Assayofawarenessisapragmaticsurrogatemarkerusedtodeterminewhetherlevelofconsciousnessisimpaired.Duringafocalawareseizure,consciousnesswillbeintact.Awarenessspecificallyreferstoawarenessduringaseizure,andnottoawarenessofwhetheraseizurehasEpilepsia,58(4):531–542,2017doi:10.1111/epi.13671 R.S.Fisheretal. occurred.Ifawarenessoftheeventisimpairedforanypor-oftheseizure,thentheseizureisclassifiedasafocalseizurewithimpairedawareness.Asapracticalmatter,afocalawareseizureimpliestheabilityofthepersonhavingtheseizuretolaterverifyretainedawareness.Occasionalseizuresmayproducetransientepilepticamnesiaretainedawareness,butclassificationofsuchseizureswouldrequireexceptionallycleardocumentationbyobser-vers.Somemightusetheshorthandfocalunaware.doingso,itiscrucialtonotethatawarenessmaybeimpairedwithoutbeingfullyabsent.Wordorderisnotimportant,sofocalawareseizuremeansthesamethingasfocalseizurewithretainedawareness.Responsivenessisaseparateclinicalattributethatcanbeeitherintactorimpairedforseizureswithorwithoutretainedawareness.Althoughresponsivenessisanimpor-tantdescriptiveaspectofseizures,itisnotusedintheILAE2017classificationtodesignatespecificseizuretypes.Thebasicclassificationfurtherallowsclassificationintomotoronsetornonmotor-onset(forexample,sensory)symptoms.Furtherspecificationinvokestheexpandedclassification,discussedbelow.Theseizuretypefocaltobilateraltonicisinaspecialcategorybecauseofitscommonoccurrenceandimportance,eventhoughitisreflectiveofapropagationpat-ternofseizureactivityratherthanauniqueseizuretype.Thephrasefocaltobilateraltonicclonicreplacestheoldertermsecondarilygeneralizedtonicclonic.Inthenewclassification,isusedforpropagationpat-ternsofseizuresandgeneralizedforseizuresofgeneral-izedonset.Generalized-onsetseizuresaredividedintomotorandnonmotor(absence)seizures.Levelofawarenessisnotusedasaclassifierforgeneralizedseizures,sincethelargemajority(althoughnotall)ofgeneralizedseizuresareasso-ciatedwithimpairedawareness.Bydefinitionofthegener-alizedbranchoftheclassification,motoractivityshouldbebilateralfromtheonset,butinthebasicclassification,thetypeofmotoractivityneednotbespecified.Incaseswherebilateralonsetofmotoractivityisasymmetrical,itmaybedifficultinpracticetodeterminewhetheraseizurehasfocalorgeneralizedonset.Absenceseizures(theprefixgeneralizedonsetmaybeassumed)presentwithasuddencessationofactivityandawareness.Absenceseizurestendtooccurinyoungeragegroups,havemoresuddenstartandtermination,andtheyusuallydisplaylesscomplexautomatismsthandofocalsei-zureswithimpairedawareness,butthedistinctionsarenotabsolute.EEGinformationmayberequiredforaccurateclassification.Focalepileptiformactivitymaybeseenwithfocalseizuresandbilaterallysynchronousspike-waveswithabsenceseizures.Seizuresofunknownonsetcanbecategorizedasmotor,includingtonicclonic,nonmotor,orunclassified.Thetermunclassifiedcomprisesbothseizureswithpatternsthatdonotfitintotheothercategoriesorseizurespresentinginsuf-ficientinformationtoallowcategorization.ExpandedclassificationTheexpandedclassification(Fig.2)providesanot

herlevelofseizurenames,builtontheframeworkofthebasicclassification.Theverticalorganizationofthefocal-onsetcategoryisnothierarchical,sincenamingthelevelofawarenessisoptional.Afocalseizurecanbeclassifiedasfocalaware(correspondingtothe1981termsimplepartial)orfocalimpairedawareness(correspondingtothe1981termcomplexpartialseizure).Focalawareorimpairedawarenessseizurescanoptionallybeclassifiedbyaddingoneofthemotoronsetornonmotor-onsettermsbelow,reflectingtheearliestprominentsignorsymptomotherthanawareness.Alternatively,afocalseizurenamecanomitmentionofawarenessasbeinginapplicableorunknownandclassifythefocalseizuredirectlybytheearli-estmotorornonmotorcharacteristic. Figure1.ThebasicILAE2017operationalclassiÞcationofseizuretypes.DeÞnitions,otherseizuretypes,anddescriptorsarelistedintheaccom-panyingpaperandglossaryofterms.Duetoinadequateinformationorinabilitytoplaceinothercategories. ,58(4):531–542,2017doi:10.1111/epi.13671 ILAE2017SeizureClassiÞcationManual Forfocal-onsetseizures,theclinicianshouldassaylevelofawarenessasdescribedforthebasicclassification.Askthepatientwhetherawarenessforeventsoccurringduringtheseizureswasretainedorimpaired,evenwhenthepersonseizingwasunresponsiveorunabletounderstandlanguage.Ifsomeonewalkedintotheroomduringaseizure,wouldthatpersonspresencelaterberecalled?Questioningwit-nessesmayclarifythenatureofbehaviorduringtheseizure.Itisimportanttoattempttodistinguishtheictalversusthepostictalstate,sinceawarenessreturnsduringthelatter.Ifthestateofawarenessisuncertain,as,forexample,isusu-allythecaseforatonicorepilepticspasmseizures,thesei-zureisclassifiedasfocalbutawarenesswouldnotbespecified.Descriptionoflevelofawarenessisoptionalandappliedonlywhenknown.Afocalawareseizure,withorwithoutfurthercharacterization,correspondstotheoldtermsimplepartialseizureandafocalimpairedawarenessseizurecorrespondstotheoldtermcomplexpartialsei-zure.Subsequenttermsinthefocalcolumnoftheexpandedclassificationcanfurtherspecifythetypeoffocalawareandfocalimpairedawarenessseizures.Alternatively,thedegreeofawarenesscanbeleftunspecifiedandaseizureclassifiedasafocalseizurewithoneofthemotoronsetornonmotor-onsetcharacteristicslistedinFigure2.Focalmotoronsetbehaviorsincludetheseactivities:ato-nic(focallossoftone),tonic(sustainedfocalstiffening),clonic(focalrhythmicjerking),myoclonic(irregular,brieffocaljerking),orepilepticspasms(focalflexionorextensionofarmsandflexionoftrunk).Thedistinctionbetweenclonicandmyoclonicissomewhatarbitrary,butclonicimpliessus-tained,regularlyspacedstereotypicaljerks,whereas,myo-clonusislessregularandinbrieferruns.Otherlessobviouslyfocalmotorbehaviorsincludehyperkinetic(pedaling,thrashing)activityandautomatisms.An Figure2.TheexpandedILAE2017operationalclassiÞcationofseizuretypes.ThefollowingclariÞcationsshouldguidethechoiceofseizuretype.Forfocalseizures,speciÞcationoflevelofawarenessisoptional.Retainedawarenessmeansthepersonisawareofselfandenvironmentduringtheseizure,evenifimmobile.Afocalawareseizurecorrespondstothepriortermsimplepartialseizure.Afocalimpairedaware-nessseizurecorrespondstothepriortermcomplexpartialseizure,andimpairedawarenessduringanypartoftheseizurerendersitafocalimpairedawarenessseizure.Focalawareorimpairedawarenessseizuresoptionallymayfurtherbecharacterizedbyoneofthemotor-onsetornonmotor-onsetsymptomsbelow,reßectingtheÞrstprominentsignorsymptomintheseizure.Seizuresshouldbeclas-siÞedbytheearliestprominentfeature,exceptthatafocalbehaviorarrestseizureisoneforwhichcessationofactivityisthedominantfeaturethroughouttheseizure.Inaddition,afocalseizurenamecanomitmentionofawarenesswhenawarenessisnotapplicableorunknown,andtherebyclassifytheseizuredirectlybymotor-onsetornonmotor-onsetcharacteristics.AtonicseizuresandepilepticspasmswouldusuallynothavespeciÞedawareness.Cognitiveseizuresimplyimpairedlanguageorothercognitivedomainsorpositivefeaturessuchasdavu,hallucinations,illusions,orperceptualdistortions.Emotionalseizuresinvolveanxiety,fear,joy,otheremotions,orappearanceofaffectwithoutsubjectiveemotions.AnabsenceisatypicalbecauseofslowonsetorterminationorsigniÞcantchangesintonesupportedbyat

ypical,slow,generalizedspikeandwaveontheEEG.AseizuremaybeunclassiÞedduetoinadequateinformationorinabilitytoplacethetypeinothercategories.DeÞnitions,otherseizuretypes,anddescriptorsarelistedintheaccompanyingpaperandglossaryofterms.DegreeofawarenessusuallyisnotspeciÞed.Duetoinadequateinformationorinabilitytoplaceinothercategories. Epilepsia,58(4):531–542,2017doi:10.1111/epi.13671 R.S.Fisheretal. automatismisamoreorlesscoordinated,purposeless,repet-itivemotoractivity.Observersshouldbeaskedwhetherthesubjectdemonstratedrepetitivepurposelessfragmentsofbehaviorsthatmightappearnormalinothercircumstances.Someautomatismsoverlapothermotorbehaviors,forinstance,pedalingorhyperkineticactivity,therebyrenderingclassificationambiguous.The2017ILAEclassificationarbi-trarilygroupspedalingactivitywithhyperkineticseizures,ratherthanwithautomatismseizures.Automatismsmaybeseeninfocalseizuresandinabsenceseizures.Afocalmotorseizurewithbehaviorarrestinvolvescessa-tionofmovementandunresponsiveness.Becausebriefbehavioralarrestatthestartofmanyseizuresiscommonanddifficulttoidentify,afocalbehavioralarrestseizureshouldcomprisebehavioralarrestasthepredominantaspectoftheseizure.Focalautonomicseizurespresentwithgastrointestinalsensations,asenseofheatorcold,flushing,piloerection(goosebumps),palpitations,sexualarousal,res-piratorychanges,orotherautonomiceffects.Focalcogni-tiveseizurescanbeidentifiedwhenthepatientreportsorexhibitsdeficitsinlanguage,thinkingorassociatedhighercorticalfunctionsduringseizuresandwhenthesesymptomsoutweighothermanifestationsoftheseizure.Davu,jamaisvu,hallucinations,illusions,andforcedthinkingareexamplesofinducedabnormalcognitivephenomena.Amorecorrect,althoughlesseuphonious,termwouldbecalimpairedcognitionseizure,butimpairedcognitionmaybeassumed,sinceseizuresneverimprovecognitivefunc-tion.Focalemotionalseizurespresentwithemotionalchanges,includingfear,anxiety,agitation,anger,paranoia,pleasure,joy,ecstasy,laughing(gelastic),orcrying(dacrys-tic).Someofthesephenomenaaresubjectiveandmustberecalledandreportedbythepatientorcaregiver.Emotionalsymptomscompriseasubjectivecomponent,whereas,affectivesignsmayormaynotbeaccompaniedbysubjec-tiveemotionality.Impairmentofawarenessforeventsdur-ingtheseizuredoesnotclassifytheseizureasafocalcognitiveseizure,becauseimpairmentofawarenesscanapplytoanyfocalseizure.Afocalsensoryseizurecanpro-ducesomatosensory,olfactory,visual,auditory,gustatory,coldsense,orvestibularsensations.Theclinicianmustdecidewhetheraneventisaunifiedsingleseizure,withevolvingmanifestationsastheseizurepropagates,oralternatively,twoseparateseizures.Suchadistinctioncansometimesbedifficult.Asmooth,continu-ousevolutionsofsigns,symptoms,andEEGpatterns(whereavailable)favorstheeventbeingasingleseizure.Repetitionofastereotypedsequenceofsigns,symptoms,andEEGchangesatdifferenttimessupportsaunitarysei-zuretype.Unitaryfocalseizuresarenamedfortheinitialmanifestationandpresenceorabsenceofalteredconscious-nessatanypointduringtheseizure.Incontrast,discontinu-ous,interruptedornonstereotypedeventspointtoclassificationofmorethanoneseizuretype.Consideraneventstartingwithdavu,repetitivepurposelesslip-smacking,lossofawareness,forcedversiontotheright,andright-armstiffening.Thissteadyevolutionimpliesaunitaryseizure,whichwouldbeclassifiedasafocalimpairedawarenesscognitiveseizure.Itwouldbeusefultoappend(asoptionaldescription,notaseizuretype)informa-tionabouttheprogressiontoautomatismsandtonicversion.Inanotherscenario,theclinicianmightencounteraseizurewithfearandlossofawareness.Thepatientrecoversand30minlaterhasaneventwithtinglingintherightarmdur-ingclearawareness.Suchasequencereflectstwoseparateseizures,thefirstbeingafocalimpairedawarenessemo-tionalseizureandthesecondafocalawaresensoryseizure.Otherfocalseizuretypesaresometimesencountered,forexample,focaltonicclonicseizures,butnotsufficientlyoftentobenamedasaspecificseizuretype.Ratherthanincludethetermotherineachcategory,adecisionwasmadetoreverttononspecificuseofthelargercategory,suchasmotoronsetornonmotor-onsetwhenthenextlevelofdetailisunclearortheseizureisnotlistedasaspecificseizuretype.The

classificationofgeneralized-onsetseizuresissimilartothatofthe1981classification,withadditionofafewnewtypes.Awarenessusuallyisimpairedwithgeneralizedonsetseizures,solevelofawarenessisnotusedasaclassifierfortheseseizures.Themainsubdivisionisintomotorandnon-motor(absence)seizuretypes.Thetermsmotor(absence)arepresentinordertoallowcharacteriza-tionofgeneralized-onsetmotorornonmotorseizuresaboutwhichnothingelsecanbesaid,butmotornonmotor(absence)maybeomittediftheseizurenameisunambigu-ous,forexample,generalizedtonicseizure.Thewordgeneralizedcanbeomittedforseizuressuchasabsencethatpresentonlywithgeneralizedonset.Tonicclonicremainsthetermreplacingthegrandmalseizuretype,althoughpopularusageoftheoldFrenchphrasewillundoubtedlypersist.Becausethereisanewseizuretypecharacterizedbymyoclonicmovementsprecedingtonic(stiffening)andclonic(sustainedrhythmicjerking)move-ments,itisimportanttodocumenttheearlymovementsofatonicclonicseizureasbeingtonic.Theclonicphaseofatonicclonicseizuretypicallyshowsregularlydecreasingfre-quencyofjerksoverthecourseoftheevent.Duringatonicclonicseizure,awarenessislostbeforeorcontempora-neouslywiththestiffeningandjerkingmovements.Sometonicclonicseizuresmayinvokeanonspecificfeelingofanimpendingseizureorabriefperiodofheadorlimbversion,neitherofwhichinvalidatesageneralizedonset,sincebio-logicprocessesneverexhibitperfectsynchrony.Theclini-cianhastojudgewhetheratrulyfocalonsetispresent.Generalizedclonicseizuresbegin,progress,andendwithsustainedrhythmicjerkingoflimbsonbothsidesofthebodyandoftenhead,neck,face,andtrunk.Generalizedclo-nicseizuresaremuchlesscommonthanaretonicseizures,usuallyoccurininfants,andshouldbedistin-guishedfromjitterinessorshudderingattacks.,58(4):531–542,2017doi:10.1111/epi.13671 ILAE2017SeizureClassiÞcationManual Generalizedtonicseizuresmanifestasbilaterallimbstiff-eningorelevation,oftenwithneckstiffening.Theclassifi-cationpresumesthatthetonicactivityisnotfollowedbyclonicmovements.Thetonicactivitycanbeasustainedabnormalposture,eitherinextensionorflexion,sometimesaccompaniedbytremoroftheextremities.Tonicactivitycanbedifficulttodistinguishfromdystonicactivity,definedassustainedcontractionsofbothagonistandantag-onistmusclesproducingathetoidortwistingmovements,whichwhenprolonged,mayproduceabnormalpostures.Generalizedmyoclonicseizurescanoccurinisolationorinconjunctionwithtonicoratonicactivity.Myoclonusdif-fersfromclonusbybeingbrieferandnotregularlyrepeti-tive.Myoclonusasasymptomhaspossibleepilepticandnonepilepticetiologies.Generalizedmyoclonicclonicseizuresbeginwithafewmyoclonicjerksfollowedbytonicclonicactivity.Theseseizuresarecommonlyseeninpatientswithjuvenilemyoclonicepilepsyandoccasionallywithothergeneral-izedepilepsies.Itisarguablewhethertheinitialjerksaremyoclonicorclonic,buttheyarerarelysufficientlysus-tainedtobeconsideredclonic.Amyoclonicatonicseizureinvolvesbriefjerkingoflimbsortrunk,followedbyalimpdrop.Theseseizures,pre-viouslycalledmyoclonicastaticseizures,aremostcom-monlyseeninDoosesyndrome,butcanalsobeencounteredinLennox-Gastautandothersyndromes.Atonicmeanswithouttone.Whenlegtoneislostduringageneralizedatonicseizure,thepatientfallsonthebuttocksorsometimesforwardontothekneesandface.Recoveryisusuallywithinseconds.Incontrast,tonicortonicclonicseizuresmoretypicallypropelthepatientintoabackwardEpilepticspasmspreviouslywerereferredtoasinfantilespasms,andtheterminfantilespasmsremainssuitableforepilepticspasmsoccurringatinfantileage.Anepilepticspasmpresentsasasuddenflexion,extension,ormixedextensionflexionofpredominantlyproximalandtruncalmuscles.Theycommonlyoccurinclustersandmostoftenduringinfancy.Generalizednonmotorseizuretypescompriseseveralvarietiesofabsenceseizures.TheTaskForceretainedthedistinctionbetweentypicalandatypicalabsence,becausethetwotypesofseizuresusuallyareassociatedwithdiffer-entEEGfindings,epilepsysyndromes,therapies,andprog-noses.Accordingtothe1981classification,whichwasbasedonanalysisofnumerousvideo-EEGrecordings,absenceseizuresareconsideredatypicalwhentheyareassociatedwithchangesintonethataremorepronouncedthanintypicalabsenceortheonsetorcessationisnotabrupt.A

nEEGmayberequiredtosecurethedistinctionbetweentypicalandatypicalabsenceseizures.Amyoclonicabsenceseizurereferstoanabsencesei-zurewithrhythmicthree-per-secondmyoclonicmove-ments,causingratchetingabductionoftheupperlimbsleadingtoprogressivearmelevation,andassociatedwiththree-per-secondgeneralizedspike-wavedischarges.Dura-tionistypically1060s.Impairmentofconsciousnessmaynotbeobvious.Myoclonicabsenceseizuresoccurinavari-etyofgeneticconditionsandalsowithoutknownassocia-Eyelidmyocloniaaremyoclonicjerksoftheeyelidsandupwarddeviationoftheeyes,oftenprecipitatedbyclosingtheeyesorbylight.Eyelidmyocloniacanbeassociatedwithabsences,butalsocanbemotorseizureswithoutacor-respondingabsence,makingthemdifficulttocategorize.The2017classificationgroupsthemwithnonmotor(ab-sence)seizures,whichmayseemcounterintuitive,butthemyocloniainthisinstanceismeanttolinkwithabsence,ratherthanwithnonmotor.Absenceseizureswitheyelidmyoclonia,seizures,orEEGparoxysmsinducedbyeyeclo-sureandphotosensitivityconstitutesthetriadofJeavonssyndrome.Seizuresofunknownonsetcanbemotorornonmotor.Themostimportantuseofthisclassificationisfortonicclonicseizuresforwhichthebeginningwasobscured.Fur-therinformationmightallowreclassificationasafocalorgeneralized-onsetseizure.Epilepticspasmsandbehaviorarrestareotherpossibleseizuretypesofunknownonset.Epilepticspasmsmayrequiredetailedvideo-EEGmonitor-ingtoclarifythenatureofonset,butdoingsoisimportantbecauseafocalonsetmaycorrespondtoatreatablefocalpathology.Anunknown-onsetbehaviorarrestseizurecouldrepresentafocalimpairedawarenessbehaviorarrestsei-oranabsenceseizure.Aseizuremightbeunclassifiedduetoinadequateinformationorinabilitytoplacethesei-zureinothercategories.Ifaneventisnotclearlyaseizure,thenitshouldnotbecalledanunclassifiedseizure;rather,thisclassificationisreservedforunusualeventslikelytobeseizures,butnototherwisecharacterized.Everyseizureclassificationinvolvessomedegreeofuncertainty.TheTaskForceadoptedthegeneralguidelineofan80%levelofcertaintythatonsetwasfocalorgeneral-ized;otherwise,theseizureshouldbelistedasofunknownonset.The80%levelwaschosenarbitrarilytomatchthecommonlyapplied80%false-negativecutoffforstatisticalanalysis.CommondescriptorsFocalseizuresprovokeavarietyofpotentialsensationsandbehaviorstoodiversetobeincorporatedintoaclassifi-cation.Tofacilitateacommonterminologyaboutseizures,theTaskForcelistedsomecommondescriptorsofbehav-iorsduringfocalseizures(Table1),butthesearenotintrin-sictotheclassification.Inotherwords,thecommondescriptorscanbeaddedtotheseizureclassificationtoclar-ifythemanifestationsofindividualseizures,butthedescrip-torsdonotdefineuniqueseizuretypesinthisclassification.Descriptorsarethereforeatalowerlevelthanaresigns,suchastonic,thatdefineaseizuretype.LateralityisaEpilepsia,58(4):531–542,2017doi:10.1111/epi.13671 R.S.Fisheretal. specialtypeofdescriptor,butanimportantoneinclinicalpractice.TheTaskForceacknowledgedtheimportanceofadetailedindividualfree-textdescriptionofaseizure,inadditiontotheclassification.GlossaryTable2providesaglossaryoftermsusedinthisandtheaccompanyingpaper.Thedefinitionsarenotuniversal,butarefocusedontheaspectsoflanguagepertinenttoseizures.Forinstance,sensoryisdefinedintermsofsensoryseizures,notallsensation.Whereverpossible,prioraccepteddefini-tionsfromtheILAEglossaryof2001weremaintained,inordertosupportcontinuityofusage,butthisglossaryupdatessometerminology.Referencecanbemadetoearlierliteraturefordefinitionsofoldterms.Termsnolongerrec-ommendedforuseareomitted.MappingoldtonewtermsTable3providesmappingofoldofficialandpopulartermstothe2017seizuretypeclassification.AbbreviationsTable4providessuggestedabbreviationsforthemainseizuretypes.SummaryofrulesforclassifyingseizuresOnset:Decidewhetherseizureonsetisfocalorgen-eralized,usingan80%confidencelevel.Otherwise,onsetisunknown.Awareness:Forfocalseizures,decidewhethertoclassifybydegreeofawarenessortoomitawarenessasaclassifier.Focalawareseizurescorrespondtotheoldsimplepartialseizuresandfocalimpairedawarenessseizurestotheoldcomplexpartialsei-Impairedawarenessatanypoint:Afocalseizureisfocalimpairedawarenessseizureifawarenessi

simpairedatanypointduringtheseizure.Onsetpredominates:Classifyafocalseizurebyitsfirstprominentsignorsymptom.Donotcounttran-sientbehaviorarrest.Behaviorarrest:Afocalbehaviorarrestseizureshowsarrestofbehaviorastheprominentfeatureoftheentireseizure.Motor/nonmotor:Afocalawareorimpairedaware-nessseizuremaybefurthersubclassifiedbymotorornonmotorcharacteristics.Alternatively,afocalsei-zurecanbecharacterizedbymotorornonmotorcharacteristics,withoutspecifyinglevelofaware-ness.Example,afocaltonicseizureOptionalterms:Termssuchasmotorornonmotormaybeomittedwhentheseizuretypeisotherwiseunambiguous.Additionaldescriptors:Afterclassifyingseizuretypebasedoninitialmanifestations,itisencour-agedtoadddescriptionsofothersignsandsymp-toms,suggesteddescriptorsorfreetext.Thesedonotaltertheseizuretype.Example:focalemotionalseizurewithtonicrightarmactivityandhyperven-tilation.Bilateralversusgeneralized:Usethetermbilateralfortonicclonicseizuresthatpropagatetobothhemi-spheresandgeneralizedforseizuresthatappar-entlyoriginatesimultaneouslyinbothhemispheres.Atypicalabsence:Absenceisatypicalifithasslowonsetoroffset,markedchangesintone,orEEGspike-wavesat3persecond.Clonicversusmyoclonic:Clonicreferstosustainedrhythmicjerkingandmyoclonictoregularunsus-tainedjerking.Eyelidmyoclonia:Absencewitheyelidmyocloniareferstoforcedupwardjerkingoftheeyelidsduringanabsenceseizure. Table1.Commondescriptorsofbehaviorsduringandafterseizures(alphabetically)CognitiveAutomatismsAcalculiaAggressionAphasiaEye-blinkingAttentionimpairmentHead-noddingavuorjamaisvuManualDissociationOral-facialDysphasiaPedalingHallucinationsPelvicthrustingIllusionsPerseverationMemoryimpairmentRunning(cursive)NeglectSexualForcedthinkingUndressingResponsivenessimpairmentVocalization/speechEmotionaloraffectiveMotorAgitationDysarthriaAngerDystonicAnxietyFencerÕsposture(Þgure-of-4)Crying(dacrystic)IncoordinationFearJacksonianLaughing(gelastic)ParalysisParanoiaParesisPleasureVersiveAutonomicSensoryAsystoleAuditoryBradycardiaGustatoryErectionHot-coldsensationsFlushingOlfactoryGastrointestinalSomatosensoryHyper/hypoventilationVestibularNauseaorvomitingVisualPalpitationsLateralityPiloerectionLeftRespiratorychangesRightTachycardiaBilateral,58(4):531–542,2017doi:10.1111/epi.13671 ILAE2017SeizureClassiÞcationManual Table2.GlossaryoftermsWordDeÞnitionSourceAbsence,typicalAsuddenonset,interruptionofongoingactivities,ablankstare,possiblyabriefupwarddeviationoftheeyes.Usuallythepatientwillbeunresponsivewhenspokento.Durationisafewsecondstohalfaminutewithveryrapidrecovery.Althoughnotalwaysavailable,anEEGwouldshowgeneralizedepileptiformdischargesduringtheevent.AnabsenceseizureisbydeÞnitionaseizureofgeneralizedonset.Thewordisnotsynonymouswithablankstare,whichalsocanbeencounteredwithfocalonsetseizuresAdaptedfromRef.12Absence,atypicalAnabsenceseizurewithchangesintonethataremorepronouncedthanintypicalabsenceortheonsetand/orcessationisnotabrupt,oftenassociatedwithslow,irregular,generalizedspike-waveactivityAdaptedfromRef.1ArrestSeebehaviorarrestAtonicSuddenlossordiminutionofmuscletonewithoutapparentprecedingmyoclonicortoniceventlasting2s,involvinghead,trunk,jaw,orlimbmusculatureAutomatismAmoreorlesscoordinatedmotoractivityusuallyoccurringwhencognitionisimpairedandforwhichthesubjectisusually(butnotalways)amnesicafterward.ThisoftenresemblesavoluntarymovementandmayconsistofaninappropriatecontinuationofpreictalmotorAutonomicseizureAdistinctalterationofautonomicnervoussystemfunctioninvolvingcardiovascular,pupillary,gastrointestinal,sudomotor,vasomotor,andthermoregulatoryfunctionsAdaptedfromRef.12AuraAsubjectiveictalphenomenonthat,inagivenpatient,mayprecedeanobservableseizure(popularusage)AwarenessKnowledgeofselforenvironmentNewBilateralBothleftandrightsides,althoughmanifestationsofbilateralseizuresmaybesymmetricorasymmetricClonicJerking,eithersymmetricorasymmetric,thatisregularlyrepetitiveandinvolvesthesamemusclegroupsAdaptedfromRef.12CognitivePertainingtothinkingandhighercorticalfunctions,suchaslanguage,spatialperception,memory,andpraxis.TheprevioustermforsimilarusageasaseizuretypewaspsychicConsciousnessA

stateofmindwithbothsubjectiveandobjectiveaspects,comprisingasenseofselfasauniqueentity,awareness,responsiveness,andmemoryDacrysticBurstsofcrying,whichmayormaynotbeassociatedwithsadness12DystonicSustainedcontractionsofbothagonistandantagonistmusclesproducingathetoidortwistingmovements,whichmayproduceabnormalposturesAdaptedfromRef.12EmotionalseizuresSeizurespresentingwithanemotionortheappearanceofhavinganemotionasanearlyprominentfeature,suchasfear,spontaneousjoyoreuphoria,laughing(gelastic),orcrying(dacrystic)EpilepticspasmsAsuddenßexion,extension,ormixedextensionßexionofpredominantlyproximalandtruncalmusclesthatisusuallymoresustainedthanamyoclonicmovementbutnotassustainedasatonicseizure.Limitedformsmayoccur:Grimacing,headnodding,orsubtleeyemovements.Epilepticspasmsfrequentlyoccurinclusters.Infantilespasmsarethebestknownform,butspasmscanoccuratallagesAdaptedfromRef.12EpilepsyAdiseaseofthebraindeÞnedbyanyofthefollowingconditions:(1)Atleasttwounprovoked(orreßex)seizuresoccurring24hapart;(2)oneunprovoked(orreßex)seizureandaprobabilityoffurtherseizuressimilartothegeneralrecurrencerisk(atleast60%)aftertwounprovokedseizures,occurringoverthenext10years;(3)diagnosisofanepilepsysyndrome.Epilepsyisconsideredtoberesolvedforindividualswhohadanage-dependentepilepsysyndromebutarenowpasttheapplicableageorthosewhohaveremainedseizurefreeforthelast10years,withnoantiseizuremedicinesforthelast5yearsEyelidmyocloniaJerkingoftheeyelidsatfrequenciesofatleast3persecond,commonlywithupwardeyedeviation,usuallylasting10s,oftenprecipitatedbyeyeclosure.TheremayormaynotbeassociatedbrieflossofawarenessFencerÕspostureseizureAfocalmotorseizuretypewithextensionofonearmandßexionatthecontralateralelbowandwrist,givinganimitationofswordplaywithafoil.ThishasalsobeencalledasupplementarymotorareaseizureFigure-of-4seizureUpperlimbswithextensionofthearm(usuallycontralateraltotheepileptogeniczone)withelbowßexionoftheotherarm,formingaÞgure-of-4FocalOriginatingwithinnetworkslimitedtoonehemisphere.Theymaybediscretelylocalizedormorewidelydistributed.FocalseizuresmayoriginateinsubcorticalstructuresFocalonsetbilateraltonicclonicseizureAseizuretypewithfocalonset,withawarenessorimpairedawareness,eithermotorornon-motor,progressingtobilateraltonicclonicactivity.ThepriortermwasseizurewithpartialonsetwithsecondarygeneralizationEpilepsia,58(4):531–542,2017doi:10.1111/epi.13671 R.S.Fisheretal. Examplesclonic:Awomanawakenstofindherhusbandhavingaseizureinbed.Theonsetisnotwitnessed,butsheisabletodescribebilateralstiffeningfollowedbybilateralshaking.EEGandmagneticresonanceimaging(MRI)findingsarenormal.Thisseizureisclassifiedasunknownonsettonicclonic.Thereisnosupplementaryinformationtodetermineiftheonsetwasfocalorgener-alized.Intheoldclassification,thisseizurewouldhavebeenunclassifiablewithnofurtherqualifiers.Focalonsetbilateraltonicclonic:Inanalternatesce-narioofcase1,theEEGshowsaclearrightparietalslow-wavefocus.TheMRIshowsarightparietalregionofcorticaldysplasia.Inthiscircumstance,theseizurecanbeclassifiedasfocaltobilateraltonicclonicdespitetheabsenceofanobservedonset,becauseafocaletiologyhasbeenidentified,andtheoverwhelminglike-lihoodisthattheseizurehadafocalonset.Theoldclas-sificationwouldhaveclassifiedthisseizureaspartialonset,secondarilygeneralized.Absence:AchildisdiagnosedwithLennox-Gastautsyndromeofunknownetiology.EEGshowsrunsofslowspike-waves.Seizuretypesincludeabsence,tonic,andfocalmotorseizures.Theabsenceseizuresarepro-longed,haveindistinctonsetandcessation,andsome-timesresultinfalls.Inthiscase,theabsenceseizuresare Table2.Continued.WordDeÞnitionSourceGelasticBurstsoflaughterorgiggling,usuallywithoutanappropriateaffectivetone12GeneralizedOriginatingatsomepointwithin,andrapidlyengaging,bilaterallydistributednetworks5GeneralizedtonicclonicBilateralsymmetricorsometimesasymmetrictoniccontractionandthenbilateralcloniccontractionofsomaticmuscles,usuallyassociatedwithautonomicphenomenaandlossofawareness.TheseseizuresengagenetworksinbothhemispheresatthestartoftheseizureAdaptedfromRefs5,12HallucinationAcreationofcompositeperceptionswithoutcorrespondingexternalstim

uliinvolvingvisual,auditory,somatosensory,olfactory,and/orgustatoryphenomena.Example:ÒHearingÓandÒseeingÓpeopletalkingBehaviorarrestArrest(pause)ofactivities,freezing,immobilization,asinbehaviorarrestseizureNewImmobilitySeeactivityarrestImpairedawarenessSeeawareness.Impairedorlostawarenessisafeatureoffocalimpairedawarenessseizures,previouslycalledcomplexpartialseizuresImpairmentofconsciousnessSeeimpairedawarenessNewJacksonianseizureTraditionaltermindicatingspreadofclonicmovementsthroughcontiguousbodypartsunilaterallyMotorInvolvesmusculatureinanyform.Themotoreventcouldconsistofanincrease(positive)ordecrease(negative)inmusclecontractiontoproduceamovementMyoclonicSudden,brief(100msec)involuntarysingleormultiplecontraction(s)ofmuscles(s)ormusclegroupsofvariabletopography(axial,proximallimb,distal).MyoclonusislessregularlyrepetitiveandlesssustainedthanisclonusAdaptedfromRef.12MyoclonicatonicAgeneralizedseizuretypewithamyoclonicjerkleadingtoanatonicmotorcomponent.ThistypewaspreviouslycalledmyoclonicMyoclonicclonicOneorafewjerksoflimbsbilaterally,followedbyatonicclonicseizure.Theinitialjerkscanbeconsideredtobeeitherabriefperiodofclonusormyoclonus.SeizureswiththischaracteristicarecommoninjuvenilemyoclonicepilepsyDerivedfromRef.1NonmotorFocalorgeneralizedseizuretypesinwhichmotoractivityisnotprominentNewPropagationSpreadofseizureactivityfromoneplaceinthebraintoanother,orengagingofadditionalbrainnetworksResponsivenessAbilitytoappropriatelyreactbymovementorspeechwhenpresentedwithastimulusNewSeizureAtransientoccurrenceofsignsand/orsymptomsduetoabnormalexcessiveorsynchronousneuronalactivityinthebrainSensoryseizureAperceptualexperiencenotcausedbyappropriatestimuliintheexternalworld12SpasmSeeepilepticspasmTonicAsustainedincreaseinmusclecontractionlastingafewsecondstominutes12clonicAsequenceconsistingofatonicfollowedbyaclonicphase12UnawareThetermunawarecanbeusedasshorthandforimpairedawarenessNewUnclassiÞedReferringtoaseizuretypethatcannotbedescribedbytheILAE2017classiÞcationeitherbecauseofinadequateinformationorunusualclinicalfeatures.IftheseizureisunclassiÞedbecausethetypeofonsetisunknown,alimitedclassiÞcationmaystillderivefromobservedUnresponsiveNotabletoreactappropriatelybymovementorspeechwhenpresentedwithstimulationNewVersiveAsustained,forcedconjugateocular,cephalic,and/ortruncalrotationorlateraldeviationfromthemidlineNew,anewdeÞnition,createdinthisarticle.,58(4):531–542,2017doi:10.1111/epi.13671 ILAE2017SeizureClassiÞcationManual classifiedasatypicalabsenceduetotheircharacteris-tics,theEEGpattern,andunderlyingsyndrome.Theabsenceseizureswouldhavehadthesameclassificationintheoldsystem.Tonic:Achildhasbriefseizureswithstiffeningoftherightarmandleg,duringwhichresponsivenessandawarenessareretained.Thisseizureisafocalawaretonicseizure(thewordsmotoronsetcanbeassumed).Intheoldsystem,theseizurewouldhavebeencalled,withaperhapsincorrectassumptionofgeneral-izedonset.Focalimpairedawareness:A25-year-oldwomandescribesseizuresbeginningwith30sofanintensefeelingthatfamiliarmusicisplaying.Shecanhearotherpeopletalking,butafterwardsrealizesthatshecouldnotdeterminewhattheyweresaying.Afteranepi-sode,sheismildlyconfused,andhastoreorienther-Theseizurewouldbeclassifiedasfocalimpairedawareness.Eventhoughthepatientisabletointeractwithherenvironment,shecannotinterpretherenviron-ment,andismildlyconfused.Priorclassificationwouldhavebeencomplexpartialseizure.Autonomic:A22-year-oldmanhasseizuresduringwhichheremainsfullyaware,withthehaironmyarmsstandingonedgeandafeelingofbeingflushed.Theseareclassifiedasfocalawarenonmotorautonomicsei-,ormoresuccinctly,focalawareautonomicsei-.Theoldclassificationwouldhavecalledthemsimplepartialautonomicseizures.Focalclonic:A1-month-oldboyhasrhythmicaljerkingoftheleftarmthatdoesnotremitwhenrepositioningthearm.CorrespondingEEGshowsrightfrontalictalrhythms.Theseseizuresarefocalmotoronsetclonicsei-,ormoreparsimoniously,focalclonicseizuresBecausethelevelofawarenesscannotbeascertained,awarenessisnotinvolvedinclassifyingthisseizure.Theoldclassificationwouldnothavehadanameforthissei-zure.Sequentialseizuremanifestations:A

seizurebeginswithtinglingintherightarmofa75-year-oldman.The Table3.MappingofoldtonewseizureclassifyingtermsOldtermforseizureNewtermforseizure[choice](optional)Absence(Generalized)absenceAbsence,atypical(Generalized)absence,atypicalAbsence,typical(Generalized)absence,typicalAkineticFocalbehaviorarrest,generalizedabsenceAstatic[Focal/generalized]atonicatonicgeneralized]atonicAuraFocalawareClonic[Focal/generalized]clonicComplexpartialFocalimpairedawarenessConvulsion[Focal/generalized]motor[tonicclonic,tonic,clonic],focaltobilateraltonicDacrysticFocal[awareorimpairedawareness]emotional(dacrystic)DialepticFocalimpairedawarenessDropattack[Focal/generalized]atonic,[focal/generalized]tonicFencerÕsposture(asymmetrictonic)Focal[awareorimpairedawareness]motortonicFigure-of-4Focal[awareorimpairedawareness]motortonicFreezeFocal[awareorimpairedawareness]behaviorarrestFrontallobeGelasticFocal[awareorimpairedawareness]emotional(gelastic)GrandmalGeneralizedtonicclonic,focaltobilateraltonicclonic,unknown-onsettonicGustatoryFocal[awareorimpairedawareness]sensory(gustatory)Infantilespasms[Focal/generalized/unknown]onsetepilepticspasmsJacksonianFocalawaremotor(Jacksonian)LimbicFocalimpairedawarenessMajormotorGeneralizedtonicclonic,focal-onsetbilateralMinormotorFocalmotor,generalizedmyoclonicMyoclonic[generalized]myoclonicNeocorticalFocalawareorfocalimpairedawarenessOccipitallobeParietallobePartialFocalPetitmalAbsencePsychomotorFocalimpairedawarenessRolandicFocalawaremotor,focaltobilateralSalaam[Focal/generalized/unknownonset]epilepticspasmsSecondarilygeneralizedFocaltobilateraltonicSimplepartialFocalawareSupplementarymotorFocalmotortonicSylvianFocalmotorTemporallobeFocalaware/impairedawarenessTonic[generalized]tonicclonic[Generalized/unknown]onsettonicclonic,focaltobilateraltonicUncinateFocal[awareimpairedawareness]sensoryNotethatthereisnotaone-to-onecorrespondence,reßectingreorganiza-tionaswellasrenaming.Themostimportanttermsaresetinbold.AnatomicclassiÞcationmaystillbeusefulforsomepurposes,forexample,inevaluationforepilepsysurgery. Table4.AbbreviationsforthemostimportantseizureSeizuretypeAbbreviationsFocalawareseizureFASFocalimpairedawarenessseizureFIASFocalmotorseizureFMSFocalnonmotorseizureFNMSFocalepilepticspasmFESFocaltobilateraltonicclonicseizureFBTCSGeneralizedtonicclonicseizureGTCSGeneralizedabsenceseizureGASGeneralizedmotorseizureGMSGeneralizedepilepticspasmGESUnknownonsettonicclonicseizureUTCSEpilepsia,58(4):531–542,2017doi:10.1111/epi.13671 R.S.Fisheretal. patientsaysthatitthenprogressestorhythmicjerkingoftherightarmlastingabout30s.Heretainsawarenessandmemoryfortheevent.Thisseizureisafocal(non-motor-onset)sensoryseizure.Additionaldescriptionwouldbeuseful,namelyfocalsensoryseizuresomatosensoryfeaturesprogressingtorightarmclonicactivityIfthesensoryandmotoreventsweretobedis-continuousortheclinicianhadreasontoconsidertheeventtobetwoseparate(bifocalormultifocal)seizures,theneachcomponentwouldbeclassifiedasaseparateseizure.Theoldclassificationwouldhavecalledthisasimplepartialsensorimotorseizure.Anadvantageofthe2017classificationisspecificationofthesensoryonset,whichmayhaveclinicalimportance.Myoclonicatonic:A4-year-oldboywithDoosesyn-dromehasseizureswithafewarmjerksandthenarapiddropwithlossoftone.Thesearenowclassifiedasatonicseizures.PriorunofficialusagewouldhavecalledthesemyoclonicastaticseizuresMyoclonicclonicseizures:A13-year-oldwithjuvenilemyoclonicepilepsyhasseizuresbeginningwithafewjerks,followedbystiffeningofalllimbsandthenrhythmicjerkingofalllimbs.Thesewouldbeclassifiedclonicseizures.Nocorrespondingsingleseizuretypeexistedintheoldclassification,buttheymighthavebeencalledmyoclonicorclonicsei-zuresfollowedbytonicclonicseizures.Focalepilepticspasms:A14-month-oldgirlhassuddenextensionofbotharmsandflexionofthetrunkforabout2s.Theseseizuresrepeatinclusters.EEGshowshyp-sarrhythmiawithbilateralspikes,mostprominentovertheleftparietalregion.MRIshowsaleftparietaldyspla-sia.Resectionofthedysplasiaterminatedtheseizures.Becauseoftheancillaryinformation,theseizuretypewouldbeconsideredtobefocalepilepticspasmsmotoronsetcanbea

ssumed).Thepreviousclas-sificationwouldhavecalledtheminfantilespasms,withinformationonfocalitynotincluded.Thetermcanstillbeusedwhenspasmsoccurininfancy.Unclassified:A75-year-oldmanknowntohaveepi-lepsyreportsaninternalsenseofbodytremblingandasenseofconfusion.Nootherinformationisavailable.EEGandMRIarenormal.ThiseventisThiscompaniontothepaperpresentingtherationaleandstructureoftheILAE2017seizureclassificationprovidesaninstructionalmanualforuseoftheclassification.Noamountofexplanationcan,however,eliminatetheinherentambiguitiesofaclassificationinrealclinicaluse.Forinstance,generalizedonsettonicclonicseizuresmaybeslightlyasymmetricalwithinitialheadversion.Howfocalmustanasymmetrybetoimplyafocalonset?Theanswerliesinindividualjudgmentforeachseizure.Howuncertainmustaclinicianbeaboutthenatureoftheonsettoclassifyaseizureasbeingofunknownonset?TheTaskForcesetaguidelineofconfidencetocallaseizurefocalorgen-eralized,butthisbrightlinewillundoubtedlyblurinprac-Ambiguitiesarisewhenaseizurepresentsmultiplesignsandsymptomsearlyintheevent,forexample,tonicarmstiffeningandautomatisms.Theclassifiershouldchoosetheearliestprominentsymptom,butdifferentobserversmightproducedifferentseizurenamesdependingontheinterpretationofreportedorobservedsymptomsandsigns.Theseambiguitiescanbepartiallyamelioratedbyknowingthetypicalpatternsofcommonseizures.Abehaviorarrest,followedbyeye-blinkingandhead-noddingfor5s,andthenimmediaterecovery,islikelytobeatypicalabsencesei-zure,eventhougheachindividualsymptomcanoccurinmultipleseizuretypes.Appendingoptionaldescriptorsaftertheseizuretypemaybettercommunicatethenatureofasei-zure,forexample,addingwithlaughingtoaimpairedawarenessemotionalseizure.Severalmotorsignsnowappearinconjunctionwitheitherfocalorgeneralized-onsetseizuretypes,butitcannotbeassumedthatthepathophysiologyisthesameforbothcategories.Afocaltonicseizuremayhaveadifferentmech-anismthanthatofageneralizedtonicseizure,andeachsei-zuretypemayevidencedifferentprognoses,responsestotreatments,demographics,andassociationswithepilepsysyndromes.Evenwithinthefocalcategory,focaltonicactivityaspartofafocalimpairedawarenessseizure(recallthecommonoccurrenceoftwistingmovementsduringcom-plexpartialseizures)maybeadifferententityfromfocaltonicseizuresinachildwithLennox-Gastautsyndrome.Identifyingthesenewseizuretypesshouldfacilitatelearn-ingmoreaboutthemandthesyndromeswithwhichtheyareassociated.Alearningandadoptioncurvewilldevelopforthoseintheepilepsycommunitywhousethe2017classification.Overtime,consensuswillemergeregardingwhichseizuretypesarebestrepresentativeofvariousimportantgroupsofsymptomsandsigns.Pastexperienceforecastsgradualadoptionofthenewclassification,withtransientuseoftermsfrommultiplepriorgenerationsofclassifications.Real-worlduseofthe2017classificationwilllikelymoti-vaterevisions.ThedesiredoutcomefortheILAE2017clas-sificationisgreatereaseofcommunicationaboutseizuretypesamongclinicians,thenonmedicalcommunity,andresearchers.Futureempiricalclassificationswillbedevel-opeduntilknowledgeissufficienttoconstructaclassifica-tionbasedonthefundamentalreasonsthattherearedifferentseizuretypes.AcknowledgmentsFundingforthisstudywasprovidedbytheInternationalLeagueAgainstEpilepsy.Theleadauthor(RSF)wassupportedbytheMaslahSaulMD,58(4):531–542,2017doi:10.1111/epi.13671 ILAE2017SeizureClassiÞcationManual Chair,theJames&CarrieAndersonFundforEpilepsy,theSusanHorngrenFund,andtheSteveChenResearchFund.Dr.MosheissupportedbyCharlesFrostChairinNeurosurgeryandNeurology,grantsfromtheNationalInstitutesofHealth(NIH)NS43209,CURE,theU.S.DepartmentofDefense,theHefferFamilyandtheSegalFamilyFoundationsandtheAbbeGoldstein/JoshuaLurieandLaurieMarsh/DanLevitzfamilies.Dr.ewassupportedbygrant1U54NS100064.DisclosureofConflictofThefollowingdisclosuresarerelevanttoclassification:Dr.FisherhasstockoptionsfromAvailsPharmaceuticals,CerebralTherapeutics,Zeto,SmartMonitor,andresearchgrantsfromMedtronicandtheNationalScienceFoundation(NSF).J.A.FrenchdisclosessupportviaTheEpilepsyStudyConsortium,whichpaysDrFrenchsuniversityemployerforherconsultanttimerelatedtoAcorda,Alexza,Anavex,BioPharmSolutions,Concer

t,Eisai,GeorgiaRegentsUniversity,GWPharma,Marathon,Mari-nus,Neurelis,Novartis,Pfizer,Pfizer-Neusentis,Pronutria,Roivant,Sage,SciFluor,SKLifeSciences,Takeda,Turing,UCBInc.,Ultragenyx,UpsherSmith,XenonPharmaceuticals,andZynerba,andgrantsandresearchfromAcorda,Alexza,LCGH,EisaiMedicalResearch,Lundbeck,Pfizer,SKLifeSciences,UCB,Upsher-Smith,Vertex,grantsfromNationalInstituteofNeurologicalDisordersandStroke(NINDS),EpilepsyTherapyProject,EpilepsyResearchFoundation,EpilepsyStudyConsortium.SheisontheeditorialboardsofLancetNeurologyNeurologyToday,and,andwasanAssociateEditorof,forwhichshereceivedafee.SherylHautisaconsultantforAcordaandNeurelis.EdouardHirschhasreceivedhonorariaforlecturesand/oradvicefromNovartis,Eisai,andUCB.Dr.MoshereceivesfromElsevieranannualcompensationforhisworkasAssociateEditorinNeurobiologyofDiseaseandroyaltiesfromtwobooksheco-edited.HereceivedaconsultantsfeefromEisai,andUCB.JukkaPeltolahasparticipatedinclinicaltrialsforEisai,UCB,andBial;receivedresearchgrantsfromEisai,Medtronic,UCB,andCyberon-ics;receivedspeakerhonorariafromCyberonics,Eisai,Medtronic,OrionPharma,andUCB;receivedsupportfortraveltocongressesfromCyberon-ics,Eisai,Medtronic,andUCB;andparticipatedinadvisoryboardsforCyberonics,Eisai,Medtronic,UCB,andPfizer.DrSchefferservesontheeditorialboardsofNeurologyEpilepticDisorders;mayaccruefuturerevenueonpendingpatentWO61/010176(filed:2008):TherapeuticCom-pound;andhasreceivedspeakerhonoraria/consultantfeesfromGlaxoSmithKline,AthenaDiagnostics,UCB,Eisai,andTransgenomics.Dr.YacubianlecturedforAbbott,NovartisandUCB.DrZuberiisEditor-in-ChiefoftheEuropeanJournalofPaediatricNeurologyforwhichhereceivesanannualhonorariumfromElsevierLtd.HehasreceivedresearchfundingfromDravetSyndromeUK,EpilepsyResearchUK,UCBPharma,andGlasgowChildrensHospitalCharity.Theremainingauthorslistednodisclosuresrelevanttotheclassificationofseizuretypes.CarolDErnestSomerville,andE.M.Yacubianhavenothingtodisclose.AndreasSchulze-BonhagehasreceivedhonorariaforlecturesandadvicefromCyberonics,Desitin,Eisai,Precisis,andUCB.M.SperlingcontractswithThomasJeffersonUniversitytoEisai,UCBPharma,Sunovion,SKLifeSciences,Marinus,Lundbeck,Medtronics,Visualase,Accorda,Upsher-Smith,BrainSentinel,andGlaxo;researchsupportfromDefenseAdvancedResearchProjectsAgency(DARPA)andNIHthroughThomasJeffersonUniversity;consulting:contractwithThomasJeffersonUniversitytoMedtronics.WeconfirmthatwehavereadtheJournalspositiononissuesinvolvedinethicalpublicationandaffirmthatthisreportisconsistentwiththoseguidelines.1.Proposalforrevisedclinicalandelectroencephalographicclassifica-tionofepilepticseizures.FromtheCommissiononClassificationandTerminologyoftheInternationalLeagueAgainstEpilepsy.Epilepsia1981;22:4892.AcharyaJN,WyllieE,LudersHO,etal.Seizuresymptomatologyininfantswithlocalization-relatedepilepsy.3.FisherRS,AcevedoC,ArzimanoglouA,etal.Apracticalclinicaldef-initionofepilepsy.4.FisherRS,BoasWV,BlumeW,etal.Epilepticseizuresandepilepsy:definitionsproposedbytheInternationalLeagueagainstEpilepsy(ILAE)andtheInternationalBureauforEpilepsy(IBE).2005;46:4705.BergAT,MillichapJJ.The2010revisedclassificationofseizuresandepilepsy.Continuum(MinneapMinn)2013;19:5716.FelicianO,TramoniE,BartolomeiF.Transientepilepticamnesia:updateonaslowlyemergingepilepticsyndrome.RevNeurol(Paris)2015;171:2897.LuatAF,KamatD,SivaswamyL.Paroxysmalnonepilepticeventsininfancy,childhood,andadolescence.PediatrAnn8.WolfP,YacubianEM,AvanziniG,etal.Juvenilemyoclonicepilepsy:asystemdisorderofthebrain.EpilepsyRes9.KelleySA,KossoffEH.Doosesyndrome(myoclonic-astaticepilepsy):40yearsofprogress.DevMedChildNeurol10.EliaM,GuerriniR,MusumeciSA,etal.Myoclonicabsence-likesei-zuresandchromosomeabnormalitysyndromes.1998;39:66011.StrianoS,CapovillaG,SofiaV,etal.Eyelidmyocloniawithabsences(Jeavonssyndrome):awell-definedidiopathicgeneralizedepilepsysyndromeoraspectrumofphotosensitiveconditions?Epilepsia2009;50(Suppl.5):1512.BlumeWT,LudersHO,MizrahiE,etal.Glossaryofdescriptiveter-minologyforictalsemiology:reportoftheILAEtaskforceonclassifi-cationandterminology.Epilepsia,58(4):531–542,2017doi:10.1111/epi.13671 R.S.Fis