颅内肿瘤手术体位及入路

IntrinsicCerebralTumorOperativeApproachandPatientPositionsThesurgicalapproachandpatientpositioningvariesdependingonthelocationoftheintrinsiccerebraltumorandwillbedescribedseparately.FrontalLobeTumorsFrontallobetumorscanessentiallybedividedintotwodifferentlocations,dependingontheproximityofthelesiontothemidline.Forthoselesionsthatarefoundwithin4cmofthemidline,theheadofthepatientcanessentiallybepositionedstraightuporturnedslightlytothecontralateralsideafterfixationwiththethree-pointMayfieldheadholderdevice.Thisalsoappliestotumorsthataresituateddeeplywithintheanteriorportionofthecingulatedgyrusinfrontoftherolandiccortex.Theincisionextendsfromabovethezygomaticarchtotheanteriorhairlineandmaybeextendeddownontotheforeheadslightlyifthetumorissituatedveryfaranteriorly.Shouldthatbenecessary,thisincisionisclosedwithsubcuticularsuturesandSteri-Strips(3M,St.Paul,MN)inthatportionthatinvolvestheforehead(Fig.1).Fortumorssituatedmorethan4cmfromthemidline,positioningisfacilitatedbyturningtheheadnearly60degreestowardthecontralateralside,witharollplacedundertheipsilateralshoulder(Fig.2).Theincisionisessentiallythesameand,whenthisisdoneonthedominanthemisphereside,thescalpisinfiltratedaroundtheincisionextendingfromthezygomaticarchabovetheearandforwardalongtheforeheadinacircumferentialpattern.Whenthetumoriswithin1to2cmoftherolandiccortex,itwillbenecessarytoeitherexposethemotortracttofacilitatestimulation-inducedmappingortostimulatethemotorcortexwithasubduralstripelectrodeshouldthisareanotbeexposedbecauseofananteriorlyplacedcraniotomy.额叶肿瘤额叶肿瘤依据病变距中线的距离基本上可分为2个不同的位置。对于距中线4cm内的病变，患者的头位可在Mayfield头架固定后垂直或向对侧轻度偏斜摆放。这个头位同样可应用于rolandic皮层(即中央区)前的扣带回前部的深处肿瘤。手术切口自颧弓至前发际，如果肿瘤非常靠前，则切口可向前额轻度延长。如果必要的话，切口术后采用皮内缝合或创可贴(3M,St.Paul,MN)粘合，包括前额部(图1)。对于距中线4cm之外的肿瘤，患者头部向对侧旋转约60°，同侧肩下垫圆枕(图2)。当这是在优势半球端操作时，切口基本上是相同的，头皮切口周围浸润是从颧弓到耳朵上方再到前额部的圆周形式。对于在rolandic皮层1-2cm内的肿瘤，有必要暴露运动束以诱导刺激定位，如果因为先前开颅而未能得到充分暴露，可以用硬膜下电极片刺激运动皮层而获得暴露。

\Milr||FIGURE1.Illustrationshowingthesurgicalpositionandscalpincisionforfrontaltumorswithin4cmofthemidline.\Milr||FIGURE1.Illustrationshowingthesurgicalpositionandscalpincisionforfrontaltumorswithin4cmofthemidline.CingulatetonesCmfrommidlire-FrontdlsinusFIGURE2.Illustrationshowingthesurgicalpositionandscalpincisonforfrontaltumorslateralto4cmofthemidline.TemporalTumorsFortumorsinvolvingtheanteriorhalfofthetemporallobe,theheadisturnednearly90degreescontralateraltothelesion,withtheheadremainingparalleltothefloor.Whenthelesionextendsveryfarmesiallynearthecerebralpeduncleandabovetheuncus,theheadshouldbeflexedtowardthefloorby10degrees.Theincisionextendsfromthezygomaticarchjustabovethepinnaoftheear,andthensuperiorlytowardtheanteriorhairline(Fig.3,AandB).Shouldthetumorbelocatedonthedominanthemisphere,theanestheticscalpblockagainparallelstheincisioninacircumferentialfashion(Fig.4,AC).oWhenthetumorinvolvestheposteriorhalfofthetemporallobe,theheadpositioningremainsthesamebuttheincisionextendsfromthezygomaticarchsuperiorlyandthen

posteriorlytoendwellbehindthepinnaoftheearinahorseshoe-typefashion.Again,shouldtheexposurebeonthedominanthemisphereside,theareaoftheincisioniscircumferentiallyinfiltratedwithlocalanesthetic.颞叶肿瘤对于前半颞叶内的肿瘤，病变侧头需向病变对侧旋转近90度，整个头部保持与地面平行。当病变延伸很远，邻近中线附近的大脑脚及钩回之上，此时头部应向地板弯曲10度。切口从颧弓延伸，沿耳廓上方，超越前发际线（图3,A和B）。如果肿瘤位于优势半球，先行头皮阻滞麻醉，再以圆周形式平行延伸切口。当肿瘤位于颞叶的后半部，头部定位仍然同前，但切口从颧弓上方开始，向后延伸，以马蹄形形式结束于耳廓后方。同时，如果肿瘤位于优势半球侧，切口范围需用药物行局部浸润麻醉。（图4，A-C）FIGURE3.Illustrationsshowingthesurgicalpositionandscalpincisionforanterior(A)andposterior(B)temporallobetumors.$kirtirt/i劭"r&=eipilalfl.Supraarbilatn.Ssnacry引ri口MolarsEnpaccipil^ln.SuprawtolaEn.parietaltumorresection(A),frontotemporoinsulartumors(B),andanteriortemporaltumors(C)underawakemappingconditions.InsularTumorsheadInsular-basedtumorsprovideaspecialchallengetothesurgeon;thus,positioningmustbeadequatetoachievethedesiredgoalsofthesurgicalexposureandresection,dependingonthelocationofthelesionaboveorbelowthesylvianfissure.Forinsulartumorsinwhichthemajorityofthelesionisabovethesylvianfissure,thepatient'isturnedaminimumof60degreescontralateraltothetumor,withtheheadextendednearly15degreessuperiorlyinrelationtothefloor.Thisallowsfortheresectiontoparalleltheinsularvessels,whichareslantedtowardthetemporallobe(Fig.5A).Whenthemajorityoftheinsulartumorislocatedinferiortothesylvianfissure,theheadshouldbeturnednearly90degreescontralaterallyandflexedinferiorlytowardthefloornearly15degrees(Fig.5B).Thisallowsfordirectvisualizationintotheinferioraspectoftheinsulaoncethesuperiormiddletemporalgyrusisresectedorretracted.Thisalsoprovidesaccesstotheinferiorportionoftheuncinatefasciculus,whichisfacilitatedbythehead-downposition.Ifthelesionextendsveryfarposteriorly,atleasttotheendoftheposteriorlimboftheinternalcapsule,theheadshouldnotbeturned90degreesbutshouldremain60degreesfromthestraightuppositiontofacilitateaccesstotheposteriorportionofthelesion.Shouldtheinsulabeapproachedinthedominanthemisphere,theanestheticblockwillagainencompassinacircumferentialfashiontheincision,whichtypicallyextendsfromthezygomaticarchabovethepinnaoftheearandforwardtotheanteriorhairline.shead岛叶肿瘤岛叶肿瘤对于外科医生来说是一个特殊的挑战，正因如此，体位的摆放必须适于获得理想的视野暴露和手术切除，取决于病变在外侧裂上还是外侧裂下。对于大部分病变在外侧裂上的岛叶肿瘤，患者的头位摆放至少应该向肿瘤对侧倾斜60°，向上与地面呈15°。这样切除时就可以平行于岛叶血管进行，岛叶血管倾向颞叶侧(图5A)。对于大部分病变在外侧裂下的岛叶肿瘤，患者头位摆放必须向对侧旋转几乎90°，翻转向下与地面成15°（图5B）。一旦切除或牵拉颞中回的上部后就可以直视岛叶的下部。头低位时同时也为钩束的下部提供了视野暴露。如果病变向后延伸很远，至少到达内囊后肢的末端，头部没有必要倾斜90°，但仍需保留与直立体位时呈60°以适于暴露病变的后部。如果岛叶靠近优势半球，先行头皮阻滞麻醉，再以圆周形式平行延伸切口。经典的是从颧弓延伸于耳廓上方，向前直达前发际线。Anr

FIGURE5.Illustrationsshowingthesurgicalpositionandscalpincisionforinsulartumorsmostlyabove(A)orbelow(B)thesylvianfissure.ParietalandOccipitalTumorsTumorsinvolvingthelateral(i.e.,inferior)halfoftheparietallobecanbeexposedthroughahorseshoe-typeincisionthatessentiallystraddlesthetopoftheearasthebaseoftheincision(Fig.6A).Thisalsoallowsforexposureoftheregionatorabovetheatriumofthelateralventricle.Shouldthetumorinvolvethemesialorsuperiorhalfoftheparietallobe,orbebasedintheposteriorportionofthecingulategyrus,thepatientisplacedinthesupinepositionwiththeheadflexedforward45degrees.Anincisionismadealongthemidlineseveralcentimetersinfrontofthemotorcortex,extendingposteriorlyandthenovertowardthetopoftheearandsubsequentlyreflectedforwardoncetheincisionhasbeenmade.Theboneflaptypicallyencompassestherolandiccortex.However,ifthemotorcortexneedstobestimulatedandtheboneflapisnotplacedoverthisregion,asubduralstripelectrodecanbeinsertedunderneaththeduratofindthemotorcortex.Thetumoristhenapproachedthroughtheparietallobeoncetherolandiccortexisstimulated;thisresultsineventualentryintothecingulatecisternandcingulategyrusshouldthisbenecessary(Fig.6B).Whenthetumorprimarilyinvolvestheoccipitallobe,itisbesttopositionthepatientinthelateraldecubitusposition,withtheheadturnedsothatthenoseisnearlypointingtothefloor.Thispositionstheoccipitallobeinanondependentfashion,withoutanypressureontheabdomen.Thearmisplacedinasli