AcuteintraoperativebrainherniationduringelectiveneurosurgerypathophysiologyandmanagementconsiderationschangesinthesevariablescouldbeanalysedinrelationtotheapparentlycatastrophicintraoperativeeventI ID: 939714
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58ournalofNeurology,Neurosurgery,andPsychiatry1996;61:584-590Acuteintraoperativebrainherniationduringelectiveneurosurgery:pathophysiologyandmanagementconsiderationsIanRWhittle,RajaramanViswanathanDepartmentofClinicalNeurosciences,WesternGeneralHospital,EdinburghEH42XU,UKIRWhittleRViswanathanCorrespondenceto:MrIRWhittle,DepartmentofClinicalNeurosciences,WesternGeneralHospital,CreweRoad,Edinburgh,EH42X,UK.Received2June1995andinfinalrevisedform29January1996Accepted9February1996AbstractObjectives-Todescribeoperativeproce-dures,pathophysiologicalevents,man-agementstrategies,andclinicaloutcomesafteracuteintraoperativebrainhernia-tionduringelectiveneurosurgery.Methods-Reviewofclinicaldiagnoses,operativeevents,postoperativeCTfind-ings,intracranialpressure,andarterialbloodpressurechangesandoutcomesinaseriesofpatientsinwhomelectiveneuro-surgeryhadtobeabandonedbecauseofseverebrainherniation.Results-Acuteintraoperativebrainher-niationoccurredinsevenpatients.Ineachpatientsubarachnoidorintraven-tricularhaemorrhageprecededthebrainherniation.Thehaemorrhageoccurredafterintraoperativeaneurysmruptureeitherbeforearachnoidaldissection(three)orduringclipplacement(one);afterresectionof70%ofarecurrenthemisphericastroblastoma;afterresec-tionofapinealtumour;andafterastereotacticbiopsyofanAIDSlesion.Inallpatientstheprocedurewasabandonedbecauseoflossofaccesstotheintracra-nialoperatingsite,medicalmeasurestocontrolintracranialpressureundertaken(intravenousthiopentone),anintraven-tricularcatheterorCaminointracranialpressuremonitorinserted,andCTper-formedimmediatelyafterscalpclosure.Thepatientsweretransferredtoaninten-sivecareunitforelectiveventilationandmultimodalityphysiologicalmonitoring.Usingthisstrategyallpatientsrecoveredfromtheacuteictusandnopatienthadintracranialpressure�35mmHg.Althoughonepatientwithananeurysmrebledanddiedthreedayslatertheothersixpatientsdidwellconsideringthedra-maticandapparentlycatastrophicnatureoftheopenbrainherniation.Conclusions-Therearefundamentaldif-ferencesinthepathophysiologicalmecha-nisms,neuroradiologicalfindings,andoutcomesbetweenopenbrainherniationoccurringinpost-traumaticandelectiveneurosurgicalpatients.Thesurprisinglygoodoutcomesinthisseriesmayhaveoccurredbecausetheintraoperativebrainherniationwassecondarytoextra-axialsubarachnoidorintraventricularhaem-orrhageratherthanintraparenchymalhaemorrhageoracutebrainoedema.Expeditiousabandonmentoftheproce-dureandclosureofthecraniummayalsohavecontributedtotheoftenverysatis-factoryclinicaloutcome.(jNeurolNeurosurgPsychiatry1996;61:584-590)Keywords:brainhemiation;intraoperativeaneurysmrupture;subarachnoidhaemorrhage;intraventricularhaemorrhageProfoundintraoperativebrainswellingandherniationthroughanelectivecraniotomywasinmostinstances,beforemodernneuroanaes-thesia,relatedtoeitherhypercarbiaortohighvenouspressures.Nowadayssuchaneventisuncommonandisonlyoccasionallyfoundafterevacuationofapost-traumaticacutesub-duralhaematoma.'Inthissituationthehernia-tionisthoughttoberelatedtocerebralvasodilatationandhydrostaticbrainoedemasecondarytobraindecompression24andtoalterationsinthebiomechanicsofthebrainaftercraniotomy.Lesscommonlyitmayberelatedtothedevelopmentofdistantintracra-nialhaematomata."Becauseprofoundbrainswellingandhernia-tionduringelectiveneurosurgeryisinfre-quentlyreportedwepresentsevenpatients,allunderthecareoftheseniorauthor(IRW),inwhomsuchcomplicationsoccurred.Theaimsaretoclarifythepathophysiologicalmecha-nismsunderlyingsuchbrainswellingandtomakecertainmanagementrecommendations.Pathophysiologicalmechanismsareimpliedfromobservedintraoperativeevents,immedi-atepostoperativeneuroimagingstudies,andrecordingofmultiplesystemicandneurophys-iologicalvariables.Managementstrategieswerebasedontheprinciplesofprovidinganoptimalsystemicandintracranialmilieutominimisesecondarybraininsults
.MethodsThecaserecordsofsevenpatientswhoalldevelopedprofoundbrainherniationduringelectiveneurosurgicalprocedureswerethor-oughlyreviewed.Thiscohortcomprisedabout07%ofallcranialproceduresperformedbytheseniorauthoroverthetimeofthestudy.Theclinicalandsurgicaldetails,preoperativeobservationcharts,intraoperativeanaestheticrecords,andpostoperativeintensivecareunitrecordswereanalysedandallmeasuredphysi-ologicalvariableswereplottedonappropri-atelyscaledgraphssothetimecourseof584 Acuteintraoperativebrainherniationduringelectiveneurosurgery:pathophysiologyandmanagementconsiderationschangesinthesevariablescouldbeanalysedinrelationtotheapparentlycatastrophicintraop-erativeevent.ImmediatepostsurgicalCTradi-ographswerecomparedwithpreoperativestudies.ClinicaldetailsThreepatientshadsubarachnoidhaemorrhagefromanteriorcommunicatingarteryaneurysmruptureandwereWFNSgradeIorIIpreoper-atively(surgerybeingperformedtwo,seven,and11daysafteraneurysmalrupture).OnepatienthadsubarachnoidhaemorrhagefromaposteriorcommunicatinginternalcarotidarteryaneurysmandwasWFNSgradeIpre-operatively(surgeryperformedonday1).OnepatienthadAIDS,toxoplasmaretinitis,andintracerebrallesionsunresponsivetotwoweeksofantitoxoplasmatreatment.Neuro-logicallyhehadprofoundpsychomotorslow-ingbutneitherfeaturesofraisedintracranialpressurenorfocalneurologicaldeficit.Twoothershadintracerebraltumours(patient6apineoblastomaandpatient7arecurrentlefttemporalastroblastoma)withfixedfocalneu-rologicaldeficitsdespitepreoperativesteroidtherapy.Neitherhadimpairmentofconciousstateorpapilloedemadespitehydrocephalus(patient6)andalargemasslesion(patient7).Table1summarisedtheclinicalfeaturesofthesepatients.AnaestheticdetailsInallpatientsendotrachealgeneralanaesthe-siawasadministeredbyanexperiencedcon-sultantneuroanaesthetist.Premedicationwaswith5mgdroperidoland0O6mgatropine.Thiopentoneandalcuroniumwereusedforinductionandanaesthesiawasmaintainedwithphenoperidineandnitrousoxide/oxygenmixture(Fio,03).Neitheranoradrenergicblockingagentsweregivenbeforeorduringintubation,induction,ormaintananceofanaesthesia.Multiplephysiologicalvariablesincludingarterialbloodpressure(radialarteryline),heartrate,centralvenouspressure,oxy-gensaturation(Sao,),andendtidalCO,werecontinuouslymonitoredthroughouttheopera-tion.Allvariableswerestablebeforetheacuteintraoperativebrainswelling.OperativedetailsPatientswerepositionedsupinewiththeheadrotatedtoonesidewiththecontralateralshoulderraisedforaneurysmsurgery.Thepatientundergoingstereotacticbiopsywasinthesupineposition.Thepatientundergoingpinealsurgerywasprone,withheadslightlyextendedandrotatedtotheright.Thepatienthavingreoperationforbraintumourwasinthelateralposition.TheMayfieldpinheadrestwasusedforallpatientsexceptthestereotacticbiopsy.Headuptiltof150wasroutine.Severebrainherniationocurredwithinminutesineverypatient.Inthreepatients(1,2,and4)itocurredafterpterionalcraniotomy(withafreeboneflap)andduralopeningbutbeforeeitherbasalorsylvianfissurearachnoidaldissection.Inthesepatientsitwasassumedtobeduetointroperativeaneurysmalrupturebecauseoftheprofusebasalarterialbleedingthataccom-paniedtheherniation.Ineachpatientthepro-cedurewasabandonedandthescalpwasclosedinasinglelayerovertheherniatingbrain.Inonepatient(4)thefreeboneflapwasleft"floating"subcutaneouslywhereasintheothertwopatientsthiswasphysicallyimpossi-ble.Inanotherpatient(3)ruptureoftheaneurysmocurredatthetimeofclipplace-mentandwasfollowedbybrainswellingandherniation.However,inthispatientdefinitiveaneurysmalclipplacementwaspossiblebyusingtemporaryanteriorcerebralarteryclip-pingbeforeobliterationofthesurgicalfieldbytheswellingbrain.Thewoundwasclosedrapidlyinasinglelayerovertheherniatingbrain.Onepatient(5),withAIDSandmultipleintracerebrallesions,hadanuneventfulbiopsyofaparietallesion.Afterasecondtargetinthefrontalregionwasbiopsiedarteria
lbloodwasnotedtoflowfromthebiopsytrack.Itwasassumedthatasmallcorticalarterioleatthebaseofasulcuswasavulsedandrapidlythere-aftercerebraltissueherniated(liketoothpastecomingoutofatube)throughtheduralopen-ingandburrholesite.Inpatient6briskvenousbleedingoccurredaftera2X5cmpineoblastomahadbeenexcisedandtumourbedhaemostasisobtained.Theonsetofbleed-ingfollowedwithdrawaloftwomicroretrac-torsfromthedeepparafalcineoccipitallobe-tentorialregion.Initiallyitwasconsid-Table1ClinicaldatainsevenpatientswithsevereintraoperativebrainherniaPatientNoAgelSexDiagnosisPreoperativegradeProcedureTimingofhernia152/FLPostCommAWFNSIPterionalAfterduralopening,aneurismcraniotomyprearachnoiddissection265/FAntCommAWFNSIPterionalAfterduralopening,aneurysmcraniotomyprearachnoiddissection339/FAntCommAWFNSIIPterionalDuringclipplacementaneurysmcraniotomy444/MAntCommAWFNSIIPterionalAfterduralopening,aneurysmcraniotomyprearachnoiddissection541/MAIDS,cerebralGCS15,StereotacticAfterbiopsyoffrontaltoxoplasmosispsychomotorslowingbiopsy(second)lesion639/FPineoblastomaGCS15,OccipitalAfterneartotalpoorupgazecraniotomyexcisionoftumour744/MRecurrentGCS15,TemperoparietalAfter70%excisionofastroblastomadysphasiacraniotomytumourL=left;AntComm=anteriorcommunicating;PostComm=posteriorcommunicating;GCS=Glasgowcomascore;WFVNS=WorldFederationofNeurologicalSurgeonsGrading.585 56Whittle,ViswanathanTable2PhysiologicalchangesandoutcomeinpatientswithsevereintraoperativebrainherniaAcutechangesatthetimeofherniationPostoperativefindingsPatientElectiveNoHRBPICPcontrolClosurePupilsCTventilationOutcome16045140/90200/90ThiopentoneSCPERDiffuse11daysExpressiveSAHaphasiamonoparesis29085140/80210/100ThiopentoneSCPERDiffuse24hoursRebleedandEVDSAH;deathIVH310090140/80110/90ThiopentoneBFRPERDiffuse24hoursExcellentSAH;IVH480100110/80130/100ThiopentoneSCPinpointDiffuse72hoursExcellentSAH590115100/70220/150ThiopentoneSCSmallDiffuse24hoursDeathat10daysunreactiveSAH66865110/60-100/60EVDSCPinpointSAHand24hoursGoodIVH790100100/70130/100ThiopentoneBFRPERSAHand24hoursGoodIVHHR=Heartrate;BP=bloodpressure;SC=scalpclosure;BFR=boneflapreplaced;EVD=externalventriculardrain;PER=pupilsequalandreactive;SAH=subarachnoidhaemorrhage;IVH=intraventricularhaemorrhage.Figure1Patternsofchangesinarterialbloodpressure(BP)beforeandafteracuteintraoperativebrainherniationduringelectiveneurosurgery.Thearrowheadsdenoteonsetofswelling.BPrangeis50-200mmHg.Theunitsoftimeintervalsdenotingintraoperativelevelsarefiveminutesandpostoperatively30minutes.ChangesinBPareshownindetailforthefirsthourafteronsetofswelling.Onlypatient5hadanacutehypertensiveepisodedespitereceivingthiopentone.eredthataperigalenicveinhadbeenavulsed.200pVPatiet1However,thevenoushaemorrhagewasrapidly150_fifollowedbymassiveswellingoftheoccipital1500till'IiIIIlobethroughthecraniotomy.Inthispatient200Patient2thebrainswellingwassoseverethattheoccip-150sj;italpolepiarupturedandclotflowedoutof100[gtIII11thebrain.ThescalpwasclosedinasingleI200-Patient3layer.Itwasnotpossibletoevenreplacethe1501Pfreeboneflapina"floating"fashion.In1i50Ipatient7,duringthelaterstagesofexcisionofo200-Patient4averyvascularrecurrentastroblastoma,pro-:15001ll''liiifusebleedingfromneoplasticarteriolesinthea)50periventriculartumourbedresultedinrapidQL200IPatient5andprofoundcerebralherniation.Haemo-°500-lllllllIstasisandfurthertumourresectionwerem200Patient6impossiblebecausetheherniatingperitumor-150ousbraincompletelyclosedaccesstothesurgi-l11I1iiiiIiIIl111lcalfield.Thescalpwasclosedovera200-Pti7"floating"boneflap.Innoneoftheseven0-patientscouldthedurabeclosedandmanual100ff¶f4111Iil1Ifcompressionofthescalpflapwasrequiredto50-10135reducethebrainherniaandenablescalpclo-Time(h)sure.Figure2Patternsofpostoperativemeanintracranialpressure(ICP)inthefirstsixhoursafteracuteintraoperativebrainherniationduringelectiven
eurosurgery;ICPrangein0-50mmHgandtheunitsoftimeintervalsare30minutes.Patients1,3,and4hadCaminoICPmonitorsandpatients2and6anintraventricularcatheter.ExceptforpatientsIand2meanICPremainedwithinnormalrangesintheearlypostoperativeperiod.IEEECa)-1a)0.cJ50-40-30-20-10_O_5040-30-20-10_O_50-40-30-20H10_O_5040-30-20H10_O_50-40-30-20-10H0_I0123Time(h)45Patient1ManagementImmediatelythebrainherniationbecameapparentabolusinjectionofthiopentone,fol-lowedbyintravenousinfusion,wasgiveninPatient2everypatient.Totalthiopentonedoserangewas1-5gover05totwohours.Therewasnoobviousimmediatebenefitintermsofreduc--~=tionofthebrainherniation.HypotensionwasnotinducedinanyofourpatientsnorwasPatient3mannitolused.Afterscalpclosureallthepatientswerereturnedtotheadjacentneuro-radiologysuiteunderthesameanaestheticand--anon-contrastCTwasperformed.ThereafteraCaminointracranialpressuremonitorwasPatient4placedimmediatelyinthreepatients(1,3,and4)andaventricularcatheterinsertedintwopatients(2and6).Allpatientswereelectivelyventilatedandmedicalmeasuresorventriculardrainagewasemployedtomaintainintracra-Patient6nialpressurewithinnormallimits.Mechanicalventilationhadtobecontinuedfor11daysinonepatient(1)becauseofpulmonarycompli-cations;theotherpatientswereextubatedand6returnedtotheneurosurgicalwardwithinthreedays.586 Acuteintraoperativebrainherniationduringelectiveneurosurgery:pathophysiologyandmanagementconsiderations587Figure3Matchedaxialpreoperative(right)andINpostoperative(left)CTof4fourofthesevenpatients(1=A;2B;6=C;7=D).Thecommonfeaturesareextensivebasalsubarachnoidorintraventricularhaemorrhage(C,D)andventriculardilatation.Althoughbothpatient1andpatient2hadpreoperativehydrocephalusbothwereingoodWFNSgrade(A,B).Thepineallesion(C)andastroblastoma(D)areobviousinthepreoperativescans(arrows).A15ULI Whittle,ViswanathanResultsTable2andfigs1and2showtheimmediateeffectsoftheacutebrainhemiationonthephysiologicalvariablesmonitored.Therewasatransientriseinthebloodpressureinfiveofthesevenpatientsandinthesepatientsthebloodpressurereturnedtothepre-eventval-ueswithin15-30minutes(fig1).Alterationsintheheartratewerealsotransientandinvolvedminorfluctuationsinrate.Therewasanequalincidenceofmildtachycardiaandbradycardia.Intracranialpressurefindings(fig2)disclosedamaximalpressureof35mmHginonepatient(2),whereasintheotherstheintracranialpressurewaseithernormaloronlymarginallyraised(range8-30mmHg).Afterremovalofthesurgicaldrapesnoneofthepatientsexhibitedpupillarydilatation.Threepatients(4,5,and6)hadequalbutunreactivepupilsandintheremainderthepupillaryreac-tiontolightwasnormal.Thecommonfindingsonimmediatepost-surgeryCTweresubarachnoidorintraventric-ularhaemorrhagewithsomedegreeofhydrocephalus.Therewasminimalintra-parenchymalhaematoma,midlineshift,orintraparenchymallowdensity(fig3).Diffusebasalsubarachnoidhaemorrhagewasfoundinthreepatients(1,4,and5),whereassubarach-noidhaemorrhageandintraventricularhaem-orrhagewerefoundinfourpatients(2,3,6,and7).Inseveralpatientstherewasasugges-tionofeitherearlyhydrocephalus(temporalhorndilatation)orlongerstandinghydro-cephalus(fig3).Paradoxicallyinpatient7themidlineshiftwaslessthanpreoperatively(fig3).Theoveralloutcomeswereremarkablygoodconsideringthedramaticandapparentlycatastrophicnatureofboththeopenbrainher-niationandthevolumeoftheacutebleeding.Ofthefourpatientswithaneurysms,two(1and2)hadhemiparesespostoperatively;theothertwohadnolateralisingneurologicaldeficit.Onepatient(2)rebledfromheraneurysmanddiedthreedaysaftertheintra-operativeherniation.One(4)underwentlaterdefinitiveaneurysmalclippingandexcisionbeforeretumingtohispreviousemployment.Patient3alsomadeacompleterecoverybeforeretumingtowork.Thefourthpatient(1)requiredduraplastyandcranioplastyatthetimeofherdefinitiveaneurysmsurgeryandismoderatelydisabled.ThepatientwithAIDSrecoveredtohispreoperativeneurologicals
tatebutdied10dayslaterfromhisimmun-odeficiencydisorder.Thewomanwiththepineoblastomahadavisualfielddefectthatresolvedovertwoyears,andwasabletoresumeherpreviousemployment.Thepatientwiththeastroblastoma,whichhadtrans-formedtoaglioblastoma,underwentfurtherexcisionofhistumour,duraplasty,andcranio-plastybutdiedthreemonthslater.DiscussionThemostimportantclinicalfeatureinthesepatientsofelectiveneurosurgerywastherapidityofonsetofthebrainhemiation.Ineverypatienttheintraoperativeeventwassud-den,withthebrainhemiatingwithinminutesofanobservedoroccultdeepintracranialhaemorrhage,andthebrainhavingtobeman-uallyconfinedtoeffectscalpclosure.Bothcerebralvasodilatationandbrainoedemahavebeenproposedaspossiblemechanismsforrapiddevelopmentofbrainswellingaftercran-iocerebraltrauma.34728Cerebralhyperaemiaandbrainoedemaarenotmutuallyexclusiveandvascularengorgementthatissevereandpersistentmayresultinwidespreadoedemaformation.78Inthesecasesofrapidbrainher-niationduringelectiveneurosurgerywepro-posethatcombinationsofacuteintracranialhypertentioncausedbysubarachnoidorintra-ventricularhaemorrhagetogetherwithhyper-aemia,ratherthanbrainoedema,weretheprimarycausesofhemiation.Theproposedcerebralhyperaemiaandacute"pressure"waveintracranialpressurechangesinthesepatientsmayhaveoccurreddirectlyasaresultofeithertheacutesub-arachnoidhaemorrhageorintraventricularhaemorrhagebolusintotheCSFspaceorindirectlybythesubarachnoidhaemorrhageactivatingvariousneurovascularreflexmecha-nisms.91'Thefirsthypothesiswouldinvokethesubarachnoidhaemorrhageorintraventric-ularhaemorrhagebeingenvisagedasabolusinjectionintotheCSF.Thiswouldbeanalagoustoperforminganacuteexperimen-talWITH,thepeakanddurationoftheintracranialpressurewavebeingrelatedtothebloodvolumeinsultintotheCSF,therateofbleeding,andtheunderlyinglumpedcran-iospinalcomplianceatthetimeofthesub-arachnoidorintraventricularhaemorrhage.'2Acuteintracranialpressure"pressurewaves"andincreasesinthecerebralbloodvolumewithorwithoutsignificantchangesinthemeansystemicarterialpressurehavealsobeendescribedinseveralexperimentalparadigmsthatinvolveelectricalstimulationofthemedullaryandpontinenucli.'3'5Itispostu-latedthatexcitationoftheseregions,perhapsduetobrainstemmicrocirculatorydistur-bancescausedbythesubarachnoidhaemor-rhage,resultsinneurogenicvasodilationandhyperaemia.16Thispostulateisconsistentwiththeincreasesincerebralbloodflowof46%recordedafterintraoperativeaneurysmalrup-tureinhumansdespiteadecrease,albeitnon-significant,inmeanarterialpressure.22Therelative"damping"ofanysystemicvascularhypertensionandabsenceofanyconsistentchangeinmeanarterialbloodpressureinthesepatientsmaybepartlyattributabletotheeffectsofgeneralanaesthesia.'317Thegener-alisednatureofthesubarachnoidhaemor-rhageandabsenceofmidlineshift,deepintracerebralhaematoma,andeitherfocalorgeneralisedbrainoedemaonthepostoperativeCT(performedwithin60minutesoftheictus),theshortlivedcourseofraisedintracra-nialpressure,andtheapparentbenefitofbar-biturateslendsupporttothesehypotheses.Thechangesinthebloodpressure,heartrate,andintracranialpressureseeninourpatientsaresimilartothosefoundbyGroteand588 Acuteintraoperativebrainherniationduringelectiveneurosurgery:pathophysiologyandmanagementconsiderationsHassler,"°Nornes,"andVoldbyandEnevoldsen'8inpatientswithsubarachnoidhaemorrhagealthoughthemagnitudeofphys-iologicalalterationsinourserieswaslower.Thisisprobablyrelatedtothefactthatourpatientshadanopencraniotomy,thusdampingthepeaksoftheictalchanges.5Studiesonexperimentalsubarachnoidhaemorrhagehaveshownasimilarcourseofchangesinbloodpressureandintracranialpressure919andapossiblevascularmechanismforthedevelop-mentofswellingandraisedpressurehasbeenshownindogs.'6Theremarkablefeatureofallthesepatientsisthatdespiteanapparentlycatastrophicintraoperativeeventallthepatientsnotonlysurvivedtheacuteictusbut-exce
ptfortheonepatientwhodiedintheperioperativeperiodandpatient7,whohadaglioblas-toma-alsorecoveredtoanindependentstate.Theseoutcomessuggestthatthesurgeonfacedwithintraoperativebrainherniationcomplicatingoccultorovertdeepintracranialhaemorrhageduringelectiveneurosurgeryshouldnotconsidereitherresectionofnormalbraintissueorinductionofsystemichypoten-sion.Thefirstoptionisnotonlycontrarytobasicprinciplesofneurosurgery,butgiventhefulminantnatureoftheherniation,itisunlikelythatanymeaningfulsurgicalresectionwouldhavebeenpossiblewithoutmajorlossofneuralfunction.Althoughbraintissueresectionhasbeenperformedafterruptureofaneurysmsbeforeorduringduralopeningtheresultsaregenerallyverypoor.'0Farraretal,20Gardner,2'andRansohoffandcolleagues22suggestedtheuseofsystemichypotensiontocontrolintraoperativeaneurysmalruptureandreportedreasonablyfavourableresultsdespitetheregionalcerebralbloodflowbeingatthethresholdlevelsatsomesites.However,usingsuchastrategyincreasestheriskofdelayedpostopertiveischaemiaasaneursymalsub-arachnoidhaemorrhageisgenerallyassociatedwithdisorderedcerebrovascularreactivityandmetabolicactivity.22'242528Further,inthefaceofacutebrainswellingandraisedintracranialpressurebothcerebralperfusionpressureandvenousdrainagemayalreadybecompromisedintheherniatingandretractedbraintissue.TsementzisandHitchcock26reportedon"res-cueclipping"usingprofoundhypotension(MABP60mmHg)afteraneurysmalrup-tureduringinductionofanaesthesia.Operativeconditionsinthesepatientswerepoorand50%diedorwereleftvegetative.Mostsurgeonswouldnowadaysgenerallyavoidsuchlevelsofhypotensionduringaneurysmalsurgeryandifruptureoccurredwithanopensurgicalfieldprefertorelyontemporaryclipstoobtainhaemostasis.2027Certainlyinpatient3temporaryocclusionoftheanteriorcerebralarteryretardedtheherni-ationandenableddefinitiveclippnigofananteriorcommunicatingartery.Animportantaspectofmanagementinourpatientsseemedtobeclosureoftheskullandscalpasrapidlyaspossible.Fromtherelativepaucityofintracranialbloodseenonthepost-operativescansitwouldseemthatre-estab-lishinga"closedcranium"situationisessen-tialintamponadingthesourceofbleeding"andminimisingtherisksofsecondaryvenousinfarctionoftheherniatingbrain.Deleteriouseffectsofcontinuousopenventriculardrainageduringsubarachnoidhaemorrhagesuchaslargeintracerebralhaematomasandprolongedpost-SAHintracranialhypertensionhavebeendescribed.'8Furthermorereboundintracranialhypertensionafterbraincompres-sionisnotonlyrelatedtoanabsolutedecreaseinthecerebralperfusionpressurebelow50mmHgbutalsotothedurationofcirculatorycompromise.2'°AlthoughBatjerandSamson'consideredthatwhenfacedwithprofoundbrainswellingafterintraoperativeaneursymalrupture,thepotentialbenefitsofabandoningtheprocedureweredebatable,20theresultsfromthis,albeitsmall,serieswouldsuggestthatitmayrepresentapragmaticapproachwhentheaneurysmhasnotbeenexposed.Thebenefitsofexpeditiousclosureofthecraniumwouldalsoseemsupportedbythesubsequentclinicalcourseofmostpatientsinthisseries.Replacementoftheboneflap,whichwasphysicallyimpossibleinseveralofthesepatients,doesnotseemessentialforthisbene-fit,althoughsuchpatientsmaydevelopapseudomeningoceleandrequirelaterduraplastyandcranioplasty.Multimodalitypostoperativemonitoringisalsousefultomin-imisesecondarybraininsultsandguidewhencraniospinaldynamicsarenormalising.WeareindebtedtothelateProfessorJDMillerforhiscriticalcommentsonthemanuscriptandMsJMasonforhertypingskills.1LobatoRD,SarabiaR,CordobesF,etal.Post-traumaticcerebralhemishericswelling.J7Neurosurg1988;68:417-23.2IshiiR.Regionalcerebralbloodflowinpatientswithrupturedintracranialaneurysms.JNeurosurg1979;50:587-94.3KobrineAI,KempeLG.Studiesinheadinjury-PartI.Anexperimentalmodelofclosedheadinjury.SurgNeurol1973;1:34-7.4LangfittTW,TannanbaumHM,KassellNF.Theetiologyofbrainswellingfollowingexperimentalheadinjury.JfNeurosurg1966;24:47
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