MedialSphenoidWingMeningioma

Approximately~15-20%ofallmeningiomasarisefromthesphenoidwing,withabouthalfofthesearisingfromthemedialportionofthewing.

Medialsphenoidwingmeningiomasareaheterogeneousgroupoftumorsoriginatingfromtheanteriorclinoidandthemedialthirdofthelessersphenoidwing.Thisgroupincludesbothglobularandhyperostoticenplaquetumors(alsocalled“spheno-orbital”meningiomas).Spheno-orbitalmeningiomaswillbediscussedintheLateralSphenoidWingMeningiomachapter.Therearenospecificpathologicorgeneticfeaturesformedialsphenoidwingmeningiomas.Someofthesetumorsarecausedbyionizingradiation.

Surgicalmanagementofmedialsphenoidwingmeningiomasischallengingbecauseofthecloselyassociatedcriticalneurovascularstructuresalongtheparasellarregion.Meningiomascanoriginatefromanypartofthemeningesalongtheclinoidprocessorlessersphenoidwingandgrowmedially,soclinicalpresentationandtechnicaldetailsofsurgicaltreatmentvaryaccordingly.

Sphenoidwingmeningiomascanbedividedintothreemaingroupsbasedonthesiteoftheirorigin:thosearisingfromtheanteriorclinoidandmedialthirdofthesphenoidwing;thosearisingfromthemiddleandlateralsphenoidwing;andenplaquemeningiomasofthesphenoidwing.Inthischapter,Iwilldiscusstechniquesforresectionofglobularmeningiomasoftheanteriorclinoidandmedialportionsofthesphenoidwing.

TheNeurosurgicalAtlas byAaronCohen-Gadol,M.D.

TheSimpsonscaleremainsthemostpracticalmethodtopredicttheriskofmeningiomarecurrencefollowingresection.

Table1:SimpsonScaleforPredictionofMeningiomaRecurrenceafterSurgery

SimpsonGrade

CompletenessofResection 10yrRecurrence

I Completewithassociatedduraandboneremoval

9%

II Completewithcoagulationofduralattachment

19%

III Completewithoutduralcoagulation 29%

IV Subtotalresection 40%

Classification

Anteriorclinoidmeningiomasarefurtherclassifiedintothreefollowingsubgroupsbasedontheirsiteoforiginalongtheanteriorclinoid.Eachgroupoffersauniquesetoftechnicaldifficultyformicrosurgery,butallthreetypicallyinvolveboththeinternalcarotidartery(ICA)andtheopticapparatusandpotentiallytheoculomotornerve.

AstheICAemergesfromthecavernoussinusinferiorandmedialtotheanteriorclinoidprocess,itpassesthroughthesubduralspacebetweentheinnerandouter(orupperandlower)duralringswhere1-2mmofitssegmentlacksarachnoidalcovering.MeningiomasarisingaroundthisshortsegmentareclassifiedasGroup1clinoidalmeningiomas.

Figure1:AlateralviewofthecavernoussinusandclinoidalsegmentsoftherightICA.NotetheshortICAsegmentbetweentheupperandlowerduralringswheregroup1clinoidalmeningiomasarisefrom(imagecourtesyofALRhoton,Jr).

AsGroup1tumorsgrow,theytypicallyengulftheICA,growdistallytowardtheICAbifurcationandencasetheproximalmiddlecerebralartery.Becausetheylackaninterveningarachnoidalplane,theyaredenselyadherenttotheadventitiaoftheICA,renderingdissectiondifficultandresultinginlowerratesofsurgicalcure.Group1tumorsalsotypicallyinvolvetheopticnerveandchiasm,butanarachnoidplaneinveststhetumorinthisregion,facilitatingdissection.Group1tumorsfrequentlyinvadethecavernoussinus.

Group2clinoidalmeningiomasarisefromthesuperiorandlateralaspectsoftheanteriorclinoiddura.ThesetumorsoftenengulftheICAastheygrow,butareinvestedbythearachnoidallayersofthecarotidcistern,creatingaccessibledissectionplanes.Additionally,thesetumorsownarachnoidaldissectionplaneswithintheregionoftheopticnerveandchiasm.Cavernoussinusinvasioniscommon.

Thesetumorsarethereforemoreamenabletoaggressivesaferesectionthangroup1tumors.

Group3clinoidalmeningiomasarisefromtheopticforamenandextendintotheopticcanal.Becauseoftheirsiteoforiginandgrowthpattern,group3tumorsbecomesymptomaticearlierthanGroup1and2tumorsandaresubstantiallysmalleratthetimeoftheirdiagnosis.ThesetumorsareinvestedbyarachnoidmembranesintheareaoftheICA,butbecausetheyoriginateawayfromthechiasmaticcistern,thereistypicallynoobviousarachnoidplanebetweenthetumorandtheopticapparatus.Asaresult,surgicalcureislesscommonandtheriskofpostoperativevisualdeclineismorereal.

Thetumorsarisingfromthemiddleportionofthesphenoidwinggrowverylargebeforetheirclinicalpresentation.Theycausesignificantmasseffectonthetemporallobe,andiftheyhaveenoughmedialextension,theycausevisualdisturbance.Smallerlesionswithoutmedialextensioncanbetreatedlikeconvexitymeningiomasafterresectionofthesphenoidwing.

Diagnosis

Themostcommonclinicalpresentationofclinoidalandmedialsphenoidwingmeningiomasareheadachesandvisualdisturbancesuchasblurredvision,visualfielddeficit,oropticatrophy(resultingfromopticapparatuscompression)ordiplopia(resultingfromoculomotornervedistortion).

Tumorsthatinvadethecavernoussinusorsuperiororbitalfissuremaycauseadditionalcranialneuropathies.Largetumorswithmiddlecranialfossaextensioncompressingthetemporallobeorbrainstemresultinseizuresorhemiparesis,respectively.Suchtumorsmayalsocausecognitiveandmemorydeficits,personalitychanges,and

dysphasia.

Tumor-inducedhyperostosisofthesphenoidwingandlateralorbitmaypresentwithproptosis,diplopia,andorbitalpain.Enplaquemeningiomasofthesphenoidwing,alsocalledspheno-orbitalmeningiomas,presentwithsuchocularmanifestations.Thesetumorscaninvadethelateralwallofthecavernoussinus,superiororbitalfissure,floorofthemiddlecranialfossa,andtheextracranialinfratemporalfossa.

Evaluation

Athoroughhistoryandphysicalexamwithparticularattentiontothesymptomsandsignsmentionedabovearerequired.Thin-cutorhigh-resolutionmagneticresonance(MR)imaging,whileincludingfatsuppressionsequencesthroughtheorbits,canassessorbitalinvolvement.

AngiographicevaluationwithMRangiographyorcomputedtomography(CT)angiographydeterminesthemeningioma’srelationshiptothesurroundingvasculatureandtheirdegreeofencasement.However,thesestudiesarerarelynecessaryastheT2-weightedMRimagesareadequateforidentificationofrelevantvasculature.ThebonewindowsonCTangiographyalsodeterminetheextentoftumor-infiltratedhyperostosis.

CatheterangiographycandemonstratestheutilityofpreoperativeembolizationandestimatestherobustnessofcollateralbloodsupplyviaatemporaryballoonocclusiontestiftheICAisencasedandatahighriskofoperativeinjury.However,IadvocatesubtotalremovalofthisbenigntumorinanattempttopreservetheICA.Withtheavailabilityofradiosurgery,theassociatedischemicrisksofamoreaggressiveresectionarenotwarranted.

Idonotbelieveendovascularembolizationisnecessaryformostmeningiomasastheycanbedevascularizedearlyduringexposurebyaggressiveresectionofthesphenoidwingandanteriorclinoidaswellascauterizationoftheinvolveddura.

Athoroughneuro-opthalmologicandendocrinologicassessmentshouldbeperformedaspartofevaluationforallsymptomaticparasellartumors,includingmeningiomas.

Figure2:Medialsphenoidwingmeningiomascanpresent

differentsetoftechnicalchallengesbasedontheirinvolvementofthemedialneurovascularstructuresandtheencasementofthecarotidartery’sperforatingvessels.Amedialsphenoidwingmeningiomawithminimalmedialextensionisshown(upperimages).TheSylvianmiddlecerebralarterybranchesdrapeoverthesuperiorpoleofthetumor.Amoretruemedialsphenoidwing/clinoidalmeningiomawithsignificantmedialextensionandencasementoftheICAisalsoincluded(lowerimages).

Figure3:Agroup3orright-sidedopticforamenmeningiomaisdemonstrated.Thestrategiclocationofthismassleadstoitsearlydiscoveryduetotheassociatedrelativelyrapidcourseofvisualdeterioration.

IndicationsforProcedure

Surgicalresectionisthemainstayoftreatmentformedialsphenoidwingmeningiomas.Stereotacticradiosurgeryisanoptionforasymptomaticsmalltumorswithoutmasseffect,buttheproximityof

highlyradiosensitiveopticchiasmandnervesoftenprecludesitsuse.Observationisalsoareasonabletreatmentplanforsmallincidentaltumors.

Figure4:Coronalandaxialviewsofamiddle/medialsphenoidwingmeningiomawithitstypicalrelationshiptothesurroundingvascularstructuresisdemonstrated.Moreprominentevidenceofopticapparatuscompressionisusuallypresent.

PreoperativeConsiderations

Computedtomography(CT)measurestheextentofbonyinvasionorhyperostosis.ThisinformationisimportantforintraoperativenavigationtoguidegrosstotalresectionoftheinvolvedboneandachievingSimpsonscale1outcome.ThisCTdataalsodeterminesthepotentialneedtoprepareacustomimplantpreoperativelytoreconstructtheareaofresectedbone.

Preoperativeunderstandingofhowthetumorhasdistortedthenormalvasculatureisbeneficialtoavoidcatastrophicvascularinjury.Furthermore,significantvascularencasementattheskullbase

highlightstheneedforplannedsubtotalresectionassmallcaliberICAperforatingarteriesarehighlyvulnerabletoarterialinjuryanddissectionduringtumorexcision.Magneticresonance(MR)imagesprovidethenecessaryinformation.

Alumbardraincandecompressthebrainearlyandallowforanobstructedextraduralclinoidectomytoreleasetheaffectedopticnervebeforethetumorismanipulated.

OperativeAnatomy

Familiaritywiththeparaclinoidvascularandopticapparatusanatomyinadditiontobonymorphologyisimportant.

Figure5:Osteologyoftheanteriorandmiddlecranialbaseisshown.Notethelessersphenoidwing,anteriorclinoidprocessandsurroundingbonystructures(imagecourtesyofALRhoton,Jr).Extraduralclinoidectomycanexposethebaseofthetumorearlyandfacilitateitsdevascularization.Furthermore,extradural

opticnervedecompressionprotectsthenerveearlybeforeanyintraduraltumormanipulationplacesthenerveatriskoftractioninjury.

Figure6:Differentanatomicalviewsoftheanteriorclinoidprocesses,cavernoussinus,andtheirassociatedneurovascularstructures.Theduraisremovedovertherightanteriorclinoidprocess(imagescourtesyofALRhoton,Jr).Mostmeningiomasentertheopticcanalmedialtothenerve

becauseoftheavailabilityofapotentialspacethere.Theoculomotornerveisatriskofinjuryduringclinoidectomyandtumorresection.Medialsphenoidwingmeningiomasmayinfiltratethecavernoussinus;however,thisportionofthetumorshouldbeleftbehindbecauseoftheriskofoperatingwithinthecavernoussinus.

RESECTIONOFMEDIALSPHENOIDWINGMENINGIOMA

Mostmedialsphenoidwingmeningiomascanberesectedthroughtheextendedpterionalcraniotomy.Ifthelesionharborsasignificantsuprasellarcomponent,theorbitozygomaticcraniotomyaffordsanexcellentexposureofthesuprasellarextentofthetumorwithminimalfrontalloberetraction.Tumorswithintraorbitalextensionalsorequireanorbitozygomatic/orbitalosteotomytoexposetheorbit,removethetumorandcorrecttheproptosis.Iusetheextendedpterionalcraniotomywithextraduralclinoidectomyfor>90%ofmedialsphenoidwingmeningiomas.

Theuseofprophylacticperioperativeantiepilepticmedicationsiscontroversial.Iprefertoadministeraloadingdoseofthismedicationatsurgeryandcontinuethemedicationfor7dayspostoperatively.Intheabsenceofanyseizurewithintheperioperativeperiod,thismedicationistaperedoffaround1weekaftersurgery.Ifthepatientsuffersfromanyseizureactivityduringtheperioperativeperiod,thedosemaybeincreasedandcontinuedfor6monthsto1year.

Sincelargertumorsfilltheopticocarotidcisternsandoftenpreventearlycerebrospinalfluiddrainageforbrainrelaxation,Iimplantalumbardrainafterinductionoftheanesthesiatopromotebrainrelaxation.Thisrelaxationisimportantfor1)makingextraduralclinoidectomypossibledespitethetumoroverlyingthemedialsphenoidwing,2)earlyextra-andintraduralaggressivetumordevascularizationanddisconnectionthroughmobilizationofthe

tumorbaseawayfromtheskullbasebeforeitsdebulking.

Forgianttumorswithsignificantedemaandmasseffect,CSFdrainageshouldbeconductedjudiciouslyandgradually,preferablyafterduralopeningtoavoidtranstentorialherniation.OverdrainageofcerebrospinalfluidattheoutsetofsurgerycanalsopotentiallymakedissectionoftheSylvianfissuremoredifficult.

PleaserefertotheExtraduralClinoidectomychapterforfurtherdetailsregardingtheinitialstepsoftheoperationaftercraniotomy.Hyperostoticclinoidprocesscanbechallengingtosafelyremove,astheboneisveryresistanttodrilling.Theopticnerveshouldbeskeletonizedandcarefullyprotectedduringheavydrillingusingampleamountofirrigationfluid.

Hypertrophiedclinoidprocessescandistortthenormalanatomyoftheopticforamen/canal.IusetheassistanceofintraoperativeCTnavigationtolocalizetheforamen/canal.Oncetheclinoidectomyiscomplete,thetumor’sbasealongtheduraoverthesphenoidwingandclinoidprocessisthoroughlydevascularizedextradurally.

Oncetheabovestepsarecomplete,Iopenthedurainacrescentshapeandexposethemeningiomafollowingananteriorsylvianfissuresplit.

INTRADURALPROCEDURE

SlowegressofCSFviathelumbardrainachievesdesirablebrainrelaxation.

Figure7:Exposureofthetumorthroughaleft-sidedextendedpterionalcraniotomyafterextraduralclinoidectomyisshown.Inthiscase,thelargetumorextendedlaterallythroughtheSylvianfissure.Following~40ccofgradualCSFdrainagethroughthelumbardrain,in10ccaliquots,thetumorismobilizedawayfromthelateralsphenoidwingduraanditsmoremedialduralattachmentscoagulated.Thisimportantmaneuvercompletesacriticalstepintheoperationthatleadstothoroughdevascularizationofthetumorandsignificantlyexpeditesthelaterstepsofdissectionbyminimizingtheneedtofrequentlyinterrupttumordissection/removaltoobtainhemostasis.

Figure8:Icontinuetumordevascularizationalongtheanteriorcranialfossawhilekeepingtheapproximatelocationoftheopticnerveinmindtoavoiditsheatinjury.CSFdrainage,Sylvianfissuresplitandstrategicuseofthehandheldsuctiondeviceobviatetheneedforfixedretractors.

Figure9:Enucleationanddebulkingoffirmtumorsisconductedusinganultrasonicaspirator(leftimage)whilesoftertumorsaredebulkedusingbipolarelectrocautery,suctionapparatusandpituitaryrongeurs.Next,Igentlydrawuponthetumorcapsuletocauseitscollapseintothedebulkedcoreofthetumor(rightimage).Itiscriticaltostayinsidethetumorcapsule.Violationofthecapsuleplacesthevulnerableadherentmedialcerebrovascularstructuresatrisk.Vicinityoftheultrasonicaspiratortothevessels,evenwithoutanimmediatecontact,canleadtoirreparablevascularinjury.Thisdeviceshouldbeusedawayfromthecriticalvascularstructures.

Figure10:Atthisjuncture,aftersometumordebulkingtocreatemoreworkingspace,IfurthersplitthedistalaspectofSylvianfissureandidentifytheM2branchesdrapedoverthesuperior

andposteriorpolesofthetumorcapsule.IalsogentlymobilizethetumorcapsuleposteriorlyalongthesphenoidwinginanattempttofindorestimatethelocationoftheICAattheskullbase.TheselattertwomaneuvershelpmeapproximatetherouteoftheMCAbranches,includingtheM1,alongthemedialtumorcapsule-myblindspot.

Figure11:AllMCAvesselsaresharplydissectedoffofthetumorcapsuleandprotectedwiththeuseofcottonoidsoncemobilized(upperimage).Bluntdissectionshouldbeavoided

whenpossible.Mostimportantly,thefeedingarteriesofthetumorandthevitalenpassagevesselsareclearlyidentifiedbeforetheirfateisdecided.Piecesofpapaverine-soakedGelfoamareusedtoperiodicallybathesmallenpassagevesselsforreliefoftheirvasospasm.HighermagnificationintraoperativeviewdemonstratesdissectionoftheM2branchesawayfromthetumor(T)(lowerimage).

Althoughvascularencasementiscommononimaginginthesetumors,mostoften,thearachnoidalplanebetweenthetumorandtheMCAbranchesremainsintactenoughtodissectthevesselfreefromthetumor.Ifthetumoristooadherentforthismaneuver,asmallsheetoftumormustbeleftonthevesselsfortheirprotectionandpreventionofvasospasm.

Figure12:ItisimportanttocarefullymobilizetheanteriorfrontalpoleofthetumorinordertoidentifytheopticnerveandICAattheleveloftheskullbase(upperimage).Followingthecontour

ofsphenoidwingmedially,onecanlocalizetheapproximatelocationoftheopticcanalandtheICA.Inthelowerintraoperativephoto,thefrontalportionofthetumorsisremovedandthelocationoftheopticnerveandcarotidarteryisappreciatedatthetipofthesuctiondevice.Residualcoagulatedtumorispresentalongthetentorium.

Figure13:GentlemobilizationofthemedialcapsuleandsharpdissectionwilluncovertheopticnerveandproximalICA.Thefalciformligamentisincisedtountethertheopticnerve.TheposteriorcommunicatingarterycanbeseenoriginatingfromtheposteriorwallofICA.Thisarteryisanindicatorforthegenerallocationoftheoculomotornerve.Itthetumorisveryadherenttothenervesorvessels,aggressivemanipulationandbluntdissectionmustbeavoidedandasheetoftumorleftbehind.Despitegentlehandlingofthetumoraroundtheoculomotor

nerveandtentorium,mostpatientswillsufferfromtransientthirdandfourthnervepalsiesaftersurgery.Coagulationofthetentoriumaroundthesenervesshouldbeminimizedasmuchasfeasible.

Figure14:Next,Imobilizetheposteriortumorcapsuleawayfromthetemporallobe.Thebaseofthetumoralongtheanteriormiddlefossaisdisconnected.Iprefertosay“thereitis”andbewrong100times,ratherthansay“thereitwas”andberightonce.Neurovascularstructures(morespecifically,theposteriorcommunicatingartery,anteriorchoroidalarteriesandtheoculomotornerve)aredisplacedandcanbefoundinveryunexpectedlocations.Theyareinharm’swayduringaggressivecoagulationinfaceofbleeding.Themedial

arachnoidmembranesoverthebasalcisternsandbrainstemareleftuntouched.

Figure15:Itisessentialtomaintainthearachnoidplanesalongtheentirecircumferenceofthetumorcapsule.Topreventinfarcts,Ipreserveeveryperforatingarteryandminimizeitsmanipulation.Aftergrosstotaltumorresection,theinfiltratedduraalongthemedialsphenoidwingiscauterized.Theneurovascularanatomyattheendofresectionisdemonstrated.

Theopticcanalisthenexploredwithafineball-tipdissector.Iftumorisidentifiedinthislocation,thefalciformligamentisdividedfurther

andtheopticnerveunroofedtoallowintracanaliculartumorextraction.Aggressiveremovalofattachedtumorfromtheopticnervecandisruptthenerve’sbloodsupplyandworsenvisualdeficits.Ifthetumorisnotreadilyseparablefromthenerve,athinsheetoftumormustbeleftonthenerveandtheopticcanalgenerouslyunroofed.Carefulmicrosurgeryaroundthesensitiveoculomotornerveisnecessarytoavoidpermanentcranialnerveparesis.Thecavernoussinusisnotentered.

Inmeningiomasurgery,thefirstoperationisthebestopportunityforsurgicalcure.Therefore,safeaggressivetumorremovalisanappropriateoperativephilosophy.However,ifthetumorisadherenttotheproximalICAandencasesthisportionoftheartery,athinsheetoftumormustbeleftbehind.DissectionofadherenttumorinthisregioninvariablyleadstoinjurytothesmallperforatorsoriginatingfromthemedialwalloftheICA,includingtheposteriorcommunicatingandanteriorchoroidalarteries.

Unfortunately,Ihavesufferedfromtheagonyofthiscomplication.Oneofmypatientssufferedfromaninfarctintheposteriorlimboftheinternalcapsule,causinghemiplegia,afterremovalofagiantmedialsphenoidwingmeningioma.Ithereforeadviseagainstaggressivemanipulationoftheattachedencasingtumoralongtheskullbase.

Figure16:Theopticnerveisdecompressed,buttheadherentfirm/calcifiedtumorencasingthevasculatureisleftbehindtoavoidinjurytotheperforatingarteries(upperimage).Thelowerintraoperativephotodemonstratestheanteriorchoroidalarteryoroneoftheperforators(arrow)encasedbythetumor.This

pieceofthetumorwasnotmanipulated.

AdditionalConsiderations

Dissectionoffibroustumorscanbechallengingandalternativetechniquesarenecessarytomobilizethetumorfromtheopticnerveandthecarotidartery.

Figure17:Thefibrouscapsuleofthismedialsphenoidwingmeningiomathatwasresistanttomobilizationwasremovedby

dividingthetumorintotwofragmentsparalleltothelongaxisoftheICA.Theproximalcarotidarteryandopticnervewerefirstidentifiedattheskullbase(upperphoto).ThetumorwassubsequentlydividedalongtheaxisoftheICA(lowerphoto).Thisdivisionfacilitatedmobilizationandremovaloftheanteriorandposteriorfragmentsofthetumor.

CaseExample

Thispatientpresentedwithright-sidedvisualdeclineandwasdiagnosedwithalargemedialsphenoidwingmeningioma.

Figure18:TheMRimagesofthefirstrowdemonstratethemassandassociatedorbitalroofhyperostosis.Extraduralclinoidectomydecompressedtheopticnerveearly.ThedistalMCAbranchesweredissectedandprotected(secondrow).Asdissectioncontinuedtowardtheskullbase,thetumorwasdividedalongtheICA;thismaneuverfacilitatedtumormobilization(lastrow,leftimage).Theopticnervewasfounddistalinitsforamenandgenerouslyreleasedviaremovaloftheintracanalicularportionofthetumor(lastrow,rightimage).

RESECTIONOFOPTICFORAMENMENINGIOMA

Removalofopticforamenmeningiomasismorestraightforwardasthesetumorsarediscoveredwhentheyaresmall.Theydonotencasethevasculature.However,theycanadheretotheopticapparatus.

https://www.neurosurgicalatlas.com/uploads/volumes/ATLAS/5-SKULL_BASE_SURGERY/05-Skull_Base_Meningioma/03-Medial_Sphenoid_Wing_Meningioma/_lightbox/CBS_SkullBaseMen_MedSphenWing_19.jpg

Figure19:Arightopticforamen,group3meningioma,isdemonstrated(topimage).Extraduralclinoidectomyunroofstheopticnerve(middlephoto)inpreparationofintraduralopeningofthefalciformligamentanddissectionofthetumorwithintheopticcanal.Theextracanalicularextentofthetumoralongthemedialaspectofthenerveisshownuponduralopeningandelevationofthefrontallobe(lowerimage).

Figure20:AKarlinblade(SymmetricSurgical,Antioch,TN)isusedtocutthefalciformligamentonthesideofthetumortowardthesurgeon(topimage).Theextracanalicularcomponentofthetumorisdissectedawayfromthenerveusingsharptechniquesanddeliveredusingpituitaryrongeurs(bottomphotos).

Figure21:Thesmallperforatingvesselstothechiasmareprotected(topimage)whileanangleddissectormobilizesthemoreintracanalicularportionofthetumoraroundthemedialopticnervewithintheoperativeblindspot(middleimage).Angledstraightdissectorinspectsthedistalpartofthecanaltoensurecompletedecompressionofthecanal;thisfindingisalsoverifiedusingamicrosurgicalmirror(lowerimages).

ClosureandPostoperativeCare

AsmallpieceoftemporalismuscleisusedtoplugtheextraduralspaceatthesiteofclinoidectomytopreventapostoperativeCSFleak.Thelumbardrainisremovedattheendoftheoperation.Postoperativecareissimilartotheoneforpatientswithotherskullbasemeningiomas.

PostoperativevasospasmoftheMCAbranchesisasignificantriskandshouldbetimelyconsideredinthedifferentialdiagnosisofdelayedpostoperativeneurologicdecline.ImagingusingaCTangiogramiswarranted.

PearlsandPitfalls

Athoroughextraduralsphenoidwingresectionand

clinoidectomyleadstoanopportunitytodevascularizethetumoranddecompresstheopticnerveearlyintheprocedure.

Earlytumordevascularizationminimizesbleedingduringthedemandingmicrosurgicalstepsoftheoperationandkeepstheoperativefieldpristine.Avoidanceofbipolarcoagulationaroundthemedialneurovascularstructuresislifesaving.

Thecriticalneurovascularstructuresarealongthemedialcapsuleandthereforewithintheblindspotofthesurgeon.Centraltumordebulkingandcarefulmobilizationofthetumorcapsulearekeymaneuverstoavoidingcomplications.

Allvesselsshouldbetreatedwithutmostrespectandasmallsheetofadherenttumormustbeleftbehind.TheperforatorsalongtheICAattheskullbasearenonforgiving.

DOI:https://doi.org/10.18791/nsatlas.v5.ch05.3

Contributor:AndrewR.Conger,MD,MS

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ChicoineM,JostS.Surgicalmanagementofmeningiomasofthesphenoidwingregion:Operativeapproachestomedialandlateralsphenoidwing,spheno-orbital,andcavernoussinusmeningiomas,inBenhamB.(ed):NeurosurgicalOperativeAtlas:Neuro-oncology,2nded.RollingMeadows,IL:ThiemeMedicalPublishersandtheAmericanAssociationofNeurologicalSurgeons,2007,161-169.

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MeftyO(eds):Al-Mefty’sMeningiomas,2nded,NewYork:ThiemeMedicalPublishers,2011.297-306.

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SimonM,SchrammJ.Lateralandmiddlesphenoidwingmeningiomas,inDeMonteF,McDermottM,Al-MeftyO(eds):Al-Mefty’sMeningiomas,2nded.NewYork:ThiemeMedicalPublishers,2011,297-306.

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