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Ординатура / Хирургия / Библиотека им академика М.И. Перельмана / Книга_186_библиотеки_им_акад_М_И_Перельмана

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☆
Thecranialnervenuclei.
Keepingthesefewpointsinmind,hereareafewbrainstemstrokesyndromesyoushouldknow.These areclinicallyimportant,andcomeupfrequentlyonroundsandeveninreallife—oftennotincomplete formbutcertainlyinarecognizablepresentation.Theitalicizedfontonthenextpagehelpshighlightthe keydistinguishingfeaturesofeachsyndrome.
Box2.8
Jean-DominiqueBaubywastheeditor-in-chiefoftheFrencheditionofEllemagazinein1995 whenhesufferedabrainstemstrokethatlefthimlockedin.TheDivingBellandtheButterfly ishismemoir,publishedseveralyearslaterandwrittenentirely—withthehelpofa transcriberwhorepeatedlyrecitedthealphabet—byblinking,selectingoneletteratatime. ThefilmadaptationpremieredinCannesin2007.
Wallenbergsyndrome
Location:lateralmedulla Vascularsupply:PICA Presentation:
Hoarseness,dysphagia,hiccups(nucleusambiguus:CN10,11) Ipsilateralp ain/temperaturelosstoface(CN5) Contralateralpain/temperaturelosstobody(sp inothalamictract) IpsilateralHornersyndrome(sympathetics) Ataxia(inferiorcerebellarpeduncle) Vertigo(vestibularnuclei)
Dejerinesyndrome
Location:medialmedulla Vascularsupply:vertebralartery,anteriorspinalartery Presentation:
Ipsilateraltongueweak ness(CN12) Contralateralhemiparesis(corticospinalt ract) Contralateralvibration/prop rioceptionlosstobody(dorsalcolumnmediallemniscustract)
MarieFoixsyndrome
Location:lateralpons Vascularsupply:AICA,pontineperforators Presentation:
Ipsilateralp ain/temperaturelosstoface(CN5)
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Ipsilateralfacialdroop(CN7)Ipsilateralhearingloss(CN8) Contralateralpain/temperaturelosstobody(sp inothalamictract) IpsilateralHornersyndrome(sympathetics) Ataxia(middleandinferiorcerebellarp eduncles)
LacunarStrokeSyndromes.Lacunarstrokesaccountforapproximately25%ofallischemicstrokesand aremostoftenduetosmallvesseldiseaseoftheperforatingarteriesoftheMCA,PCA,andbasilarartery (seepage54).Therearefiveclassiclacunarsyndromes.Thefirstthreecharacteristicallyinvolvethe face,arm,andleg;allfiveareusually,butnotalways,devoidofanycorticalsigns.
Pure motor—weakness of the contralateral face, arm, and leg. This is the most common lacunar syndrome,usuallyduetoinfarctsintheinternalcapsuleorbasalganglia. Pure sensory—sensoryloss ofthe contralateral face, arm, andleg; almostalwaysduetothalamic infarcts. Sensorimotor—some combination of the above; most often due to infarcts involving both the thalamusandtheinternalcapsule(termedthalamocapsularinfarcts). Ataxic hemiparesis—characterized by weakness and ataxia of the involved limb(s). Localization varies. Clumsy-handdysarthria—characterizedby dysarthria as wellasby clumsinessand mildweakness ofonehand.Localizationvaries.
CTmissesmostlacunes(particularlythoseinthebrainstem),soMRIisoftennecessaryfordiagnosis.
Box2.9InternuclearOphthalmoplegia(INO)
INO,adisorderofconjugatelateralgazeinwhichoneeyeisunabletofullyadductevenas theotherabductscompletely,iscausedbydamagetothemediallongitudinalfasciculus (MLF;atractoffiberslocatedintheparamedianareaofthemidbrainandpons).Althoughit ismostoftenduetomultiplesclerosisinyoungpatients,brainstemstrokeisthemost commoncauseintheelderly.INOisdescribedingreaterdetailinChapter9(seepage232).
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Aheatmapofthecorticospinalfibers,whichstartoutwidelydispersedinthemotorcortexandthengather together,astheydescendthroughthecoronaradiataintotheinternalcapsuleandbrainstem,intoatightly boundbundle.Theresultisthatcorticaldamagetothesefiberstendstoaffectonlypartofthehemibody (eithertheface,arm,orleg),whereasdeeperdamage—asoccursinlacunarinfarcts—affectstheentire hemibody.(ReprintedfromDalamagkasK,TsintouM,RathiY,etal.Individualvariationsofthehuman corticospinaltractanditshand-relatedmotorfibersusingdiffusionMRItractography.BrainImaging Behav.2020;14(3):696-714.)
Ische micStrokeEtiologies IschemicStrokeSyndromes
Cardioembolism ACA,MCA,PCAstroke Largearteryatherosclerosis Basilararterystroke Smallvesselocclusivedisease Brainstemstroke Strokeofotherdeterminedetiology Lacunarstroke Strokeofundeterminedetiology
Aquicksummaryofwhatyou’velearnedsofaraboutischemicstroke—see,it’snotthatbad!
Management
Notlongago,strokewastreatedasachroniccondition.Managementfocusedsolelyonrehabilitationand secondaryprevention.Then,in1996,tissueplasminogenactivator(tPA)wasapprovedfortheacute treatmentofischemicstroke.BecausetPAmustbegivenquicklytobeeffective,thearrivalofthisdrug resultedvirtuallyovernightinthetransformationofischemicstrokefromachronicconditionintoa neurologicemergency.Withtheadventofendovascularthrombectomyin2015,thetimewindowinwhich wecouldtreatischemicstrokewasexpanded,andtoday,withongoingtrialsutilizingnewimaging techniquesthathelpusidentifysalvageablebraintissue,thatwindowcontinuestogrow.
Acutestrokecaremovesfast.Thereisaclearassociationbetweentimetotreatmentandmeaningful recovery.Thus,whenapatientpresentswithanacuteonsetofafocalneurologicdeficit,inorderto providethebestcarepossible,itbecomesatrueteameffort,ofteninvolvingthepatient’sfamily members,coworkers,andevenbystanders,aswellasemergencymedicalservices,nurses,and physicians.
Whenapatientwithalikelystrokeshowsupatanemergencysetting,therearetwodecisionsthatmust bemadeasquicklyaspossible.
https://t.me/med1917
IsthepatientacandidatefortPA? Isthepatientacandidateforendovascularthrombectomy?
Thesequestionsareindependentofeachother;theanswertooneinnowayaffectstheanswertothe other.3Iftheanswertobothis“no,”theurgencyofthestrokecodeisover.Butlet’swalkthroughwhat happenswhentheanswertobothis“yes.”
IVThrombolyticTherapy.Thrombolyticsbreakupbloodclots.tPA,thefirstandstillmostcommonly usedIVthrombolytic4inacutestrokecare,doesthisbycatalyzingtheconversionofplasminogeninto plasmin,whichinturnlysesthefibrinclot.ItwasFoodandDrugAdministration(FDA)approvedin 1996tobegivenwithina3-hourtimewindow;sincethen,thatwindowhasexpandedto4.5hours5from whatwerefertoas“lastknownwell,”orthetimeatwhichthepatientwaslastdefinitivelyseenathisor herneurologicbaseline.
Box2.10CapsularWarningSyndrome
Motorlacunesoccasionallypresentwithaburstofdramatic,hemiplegicTIAs,inwhichthe motordeficitrepeatedlyappearsandthen—usuallyafter10to15minutesorso—fully resolves.Unfortunately,about50%ofthesepatientsgoontodevelopfixeddeficitswithina dayorso.
Whenastrokecodeisactivated,thelastknownwellisthefirstpieceofinformationyouneedto obtain.Ifthepatientiswithinthetherapeuticwindow,allofyourfollow-upquestionsshouldthenbe gearedtowarddeterminingwhetherornotthepatientiseligiblefortPA.Thelistofrelativeandabsolute contraindicationsfortPAislongandcomplicatedbutcanbesimplifiedbyaskingtwoquestions.
1.  Is the patient likely to bleed? tPA breaks upclots andthuspredisposes tobleeding.There are onlythree objective measures that must alwaysbecheckedpriortotPAadministration: blood pressure,a finger-stickglucose,anda CTofthe head.Severely elevated bloodpressure(systolicbloodpressure[SBP]>185ordiastolicbloodpressure[DBP]>110,accordingtothemostrecentguidelines)is acontraindicationtotPA,butcanoftenberapidlyreducedwithIVantihypertensivetherapy.Glucoselevelsbelow50orabove400are alsocontraindications(hypo-andhyperglycemiaarecommonstrokemimics;seepage75),butagaincanoftenberapidlycorrectedand, if theneurologicdeficits persistdespitecorrection,donotpreclude tPAadministration.Finally,a CToftheheadmustbecompletedto ruleoutintracranialhemorrhage.
2. Significantsurgery,headtrauma, orstrokewithin thepreceding3monthsareallrelativetPA contraindications,determinedonacase­by-case basisbyweighingrisksandbenefits. Thepresence of anintra-axialbrain tumoror active use ofan anticoagulant(including heparin, Lovenox, dabigatran, apixaban, and rivaroxaban) are also contraindications. Warfarin is its own story: if the patient is on warfarin,astatinternationalnormalizedratio(INR)mustbechecked,andifit’sgreaterthan1.7,tPAiscontraindicated.
3. Arethepatient’ssymptomsdisabling?Isolatedsensorysymptoms,forexample,tendtobeconsiderednondisabling,andthus tPA is notrecommended;therisk/benefitratiofavorswithholdingtreatment.Thatsaid,oneperson’sminorneurologicdeficitisanother’sentire world.Mildfingerweakness,for instance,maynot affectthe quality oflife of a90-year-oldpatientwholivesin a nursinghome but couldendthecareerofayoungpianistorsurgeon.Inthecaseofourpatient,Laura,thenumbnessandweaknessinvolvingherleftarm are subtle findings but ultimately deemed disabling given her career as a professional tennis player. These decisions must be individualized,withrisksandbenefitsweighedasappropriate.
Iftherearenocontraindications,tPAisrelativelysafe.Thetwoimmediateconcernsaresymptomatic
intracerebralhemorrhage(ICH)andorolingualangioedema.
SymptomaticICH(seeninapproximately6%ofpatientsintheoriginaltrials;itismorecommonin
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olderpatientswithlargerinfarcts)occursasaconsequenceofreperfusioninjury(i.e.,bleedingandtissue damagecausedbytherapidreturnofbloodflowtoweakenedbloodvesselsfollowingaperiodof ischemia).Ifyourpatient’sexaminationbeginstoworsenafteryou’vestartedtPA,symptomaticICHmust beatthetopofyourdifferential.StopthetPAinfusion,obtainastatCT,andifsignificantbleedingis identified,reversethetPAwitheithercryoprecipitateortranexamicacid.
Orolingualangioedemaismostoftenseeninpatientspreviouslyorcurrentlyonanangiotensin­convertingenzymeinhibitor.Itistypicallyasymmetricandcancausesignificantairwaycompromise.If thesymptomsaresevere,thetPAinfusionmustbestopped,intubationconsidered,andsteroidsandan antihistaminegivenassoonaspossible.
tPAworks(i.e.,itopens,orrecanalizes,theoccludedvessel)between5%and30%ofthetime.Itis moreeffectiveatbreakingupsmallerclotsthanbiggerones;therateofsuccesswithlargevessel occlusions(LVOs)isonlyaround10%.
https://t.me/med1917
https://t.me/med1917
Forevery100patientswhoreceivetissueplasminogenactivator(tPA),aboutone-thirdimprove,mostare unaffected,andafewdoworse.
Box2.11LastKnownWell
Themomentwhenapatientwaslastknownwellmaybeequivalenttothetimeofsymptom onset(e.g.,ifthepatientisabletotellyouthatheorshewasfineat11:45pmandbecame acutelyweakontheleftsideat11:46pm,thenheorshewaslastknownwellat11:45pm), butit’softennotsostraightforward.Aphasicpatients,forinstance,maynotbeabletotell youwhentheirsymptomsbegan,andthusyoumustrelyoncollateralinput,oftenfromfamily membersorhomehealthaides,todeterminelastknownwell.So-called“wake-up”strokes arealsocommon:patientsgotosleep“well”andthenwakeupwithnewneurologicdeficits. Inthesecases,wecan’tknowwhattimethestrokehappenedandthelastknownwellwillbe thetimeatwhichthepatientfellasleep.
EndovascularThrombectomy.Theneedtodevelopeffectiveendovasculartherapywaspromptedbythe tighttimewindowandlonglistofcontraindicationsassociatedwithtPA;althoughgroundbreaking,tPAis ultimatelyabletotreatonlyafractionofpatientswithacuteischemicstroke.
Theroadtothedevelopmentofsafeandeffectivemechanicalthrombectomywasarockyone,with multiplefailedtrialsalongtheway.Butthepivotalmomentcamein2015withthepublicationoftheMR CLEANtrial,arandomizedcontrolledtrialoutoftheNetherlandsthatshowedclearbenefitof mechanicalthrombectomyinpatientswithacuteischemicstrokeandLVOpresentingwithin6hoursof symptomonset.Thistrialpromptedaflurryofotherswhichnotonlyconfirmedpositiveoutcomesbut continuedtoexpandthetimewindow.Today,withthehelpofperfusionimagingtechniquesthatallowus todistinguishdeadfromdyingtissue(seeBox2.12),weroutinelytreatpatientsupto24hoursafter symptomonset,andthatwindowcontinuestogrow.
Box2.12PerfusionImaging
Theideabehindperfusionimaging,whichcanbeeitherCTorMRbased,istodistinguish deadfromdyingbraintissue(referredtoascoreandpenumbra,respectively).Thereare variousparameters,includingcerebralbloodflow(CBF,thetotalbloodvolumemoving throughagivenimagingparameterperunittime),cerebralbloodvolume(CBV,thetotal bloodvolumewithinagivenimagingparameter),andtimetopeak(TTP,alsoknownas meantransittime,anddefinedasthetimefromthestartofcontrastinjectiontomaximal tissueenhancement),thathelpdeterminetheextentofdeadversusdyingtissue.
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Acomputerizedtomography(CT)perfusionscaninapatientwitharightmiddlecerebralartery(MCA) stroke.Thescansare“mismatched”inthattheareaofincreasedtimetopeak(TTP;imageonthe right)hasnocorrelateonthecerebralbloodvolume(CBV;imageontheleft)map.Thispatientwould beacandidateforthrombectomy,becausethereissignificantpenumbraltissuetosave.(Modifiedfrom SaremiF.PerfusionImaginginClinicalPractice.WoltersKluwer;2015.)
Whydoesthisdistinctionmatter?Itturnsoutthattime,usedforsolongasasurrogatefor salvageablebraintissue,isn’talwaysthemostreliableindicator.Therearepatientswho haveacompletedinfarct(i.e.,100%deadtissue)withinanhouroftheirstroke,andothers whohavesignificantsalvageabletissue(i.e.,alargepenumbra)daysaftertheirstroke. Thereisnobenefit—andveryrealpotentialharm—inperformingmechanicalthrombectomy inpatientswithalargecoreinfarct:thereisnotissuetosave,andthedeadtissueisathigh riskofbleedingifperfusionissuddenlyrestored.Butthereverseisalsotrue:thereisoften significantbenefitwithlittlepotentialharminperformingthrombectomyinpatientswitha substantialpenumbra.Perfusionimagingcanthereforebeextraordinarilyusefulinhelpingto selectpatients—particularlythoseattheouterlimitsofthecurrently-acceptedtimewindows —forendovascularintervention.
Sowhatismechanicalthrombectomy?Thetechniquesanddevicescontinuetoevolve,butthegeneral ideaistomechanicallyremovetheclotandtherebyrestorebloodflowtotheaffectedareaofthebrain.
Theclotmustberetrievable,andthereforeonlypatientswithLVOs(i.e.,withaclotintheICA, proximalMCA,ACA,PCA,orbasilarartery)thatarevisualizedonangiographicimagingareeligible. Thereareotherwisenoabsolutecontraindications.Decisionsforeligibilityaredeterminedonacase-by­casebasis,takingintoaccountthepatient’sbaselinefunctionalstatus,symptomseverity,and,incasesthat pushthelimitsofthetimewindow,specificperfusionimagingcharacteristics.
The“numberneededtotreat”foronepatienttoregainfunctionalindependenceisaround3,making mechanicalthrombectomyoneofthemosteffectivequality-of-lifeanddisability-savingproceduresthat wehave.
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Pre-andpostoperativeangiogram.(A)Preoperativeangiogramdemonstratingaleftinternalcarotidartery (ICA)occlusion,and(B)postoperativeangiogram,showingcompletereperfusionoftheICA,anterior cerebralartery(ACA),andmiddlecerebralartery(MCA)branches.(ReprintedfromIkedaH,YamanaN, MurataY,SaikiM.Thrombusremovalbyacute-phaseendovascularreperfusiontherapytotreatcerebral embolismcausedbythrombusinthepulmonaryveinstumpafterleftupperpulmonarylobectomy:case report.NMCCaseRepJ.2014;2(1):26-30.)
Long-TermManagementandSecondaryPreventionofStroke.Antiplatelettherapy(mostoftenwith aspirin,clopidogrel,or,inspecificcases,somecombinationofthetwo)andlipid-loweringtherapy(with statins,i.e.,the3-hydroxy-3-methyl-glutaryl-coenzymeA[HMGCoA]reductaseinhibitors)aremainstays ofsecondarystrokeprevention.Anticoagulationisindicatedwhenatrialfibrillationisfound.
Riskfactorcontrolisessential.Aftertheacuteperiodfollowingstroke,duringwhichwesometimes allow“permissivehypertension”tohelpmaintaintissueperfusion,weaimforstrictbloodpressure control.Managementofdiabetes,weightloss,andsmokingcessationarealsocritical.
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Box2.13StrokeMimics
Therearemanythingsthatcancausetheacuteonsetoffocalneurologicdeficitsbesides stroke.Someofthesedisorders—suchasmigrainewithaura—canoftenbeclinically distinguishedfromstroke,butmanycannot,atleastnotrapidlyandwith100%confidence.If youaren’tsure,andifthepatientiseligiblefortPA,givethetPA.Theriskislow,especiallyin patientswithoutunderlyingbrainpathology.Itisalmostalwaysbettertotreatapatientwitha strokemimicthantomisstheopportunitytotreatanischemicstroke.
Commonstrokemimicsinclude:
Seizure/postictalparalysis(seepage166) Braintumors.Wetendtothinkofbraintumorsaspresentinggradually,withheadache, systemic symptoms such as weight loss and fatigue, and the insidious onset of focal neurologic deficits, which they usually do (see Chapter 16). But it isn’t uncommon for patientstopresentmoreacutely.Whetherthisisbecausethetumorhasbled,hasfinally crossed some symptomatic threshold or because the patient has previously been unawareof the deficit untilheor sheisfinallypromptedtorecognizeit, we often don’t know.  Hypertensive encephalopathy. Sudden rises in blood pressure can cause cerebral edemaduetofailureofcerebralautoregulationresulting inrapidrisesin cerebralblood flow. This condition typically presents with the gradual onset of headache, nausea, vomiting,andconfusion,butcanpresentwithfocalneurologicsymptomsaswell. Migrainewithaura(seepage96)  Stroke recrudescence. Recrudescence refers to the re-emergence or unmasking of priorstroke-relatedneurologicdeficits.Suchsymptomscanlasthourstodaysandare often triggered by infection, hypotension, metabolic derangements, and even severe stress.Deficitsshouldgraduallyimprovewithresolutionoftheprovokingfactor. Hypo-orhyperglycemia. Severeabnormalitiesinthelevelsof bloodglucosecan both trigger stroke recrudescence and cause new focal symptomsall ontheir own, without anyunderlyingbrainpathology.
Somespecificstrokeetiologiesalsorequirespecifictreatments.Infectiveendocarditis,forinstance,is treatedwithlong-termintravenousantibiotics.Symptomaticextracranialcarotidstenosis(i.e.,narrowing ofanextracranialportionofacarotidarterythatisthoughttohavecausedthestroke)canbetreated surgicallyifthepatientiseligibleandthestenosisissevere,witheitherangioplastyandstentingoropen endarterectomy.
IntracerebralHemorrhage(ICH)
Congratulations,you’vemadeittostroketypenumbertwo!Hemorrhageismorestraightforwardthan ischemia(wepromise),bothintermsofetiologyandmanagement.Althoughitremainssignificantlyless commonthanischemicstroke,theincidenceofintracerebralhemorrhage(ICH)isrising,likelyduetothe agingpopulationandtotheincreasinglywidespreaduseofantiplateletandanticoagulantmedications.
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