Instrumentation

Surgicalinstrumentationhasbecomeexponentiallymorecomplexinrecentdecades.Ibelievesimplicityininstrumentationiskeytooperativeefficiency.

Figure1:Cushing’sinstrumenttableinlate1920’s.PleasenotetheuseofBovieelectrocauteryonthelefthandside(CourtesyofCushingBrainTumorRegistryatYaleUniversity).

Thesurgeon’soperativemaneuversshouldfollowoneanotherseamlessly,similartomovementsinaconcertoflowingtogethertoformamasterpiece.Thisvirtuosityisfoundeduponmovementsthatmeldtogetherwithouthesitation.Toachievethisleveloftechnicalcompetenceandfinesse,thesurgeonmusthaveamasteryofthedesirablemacroandmicroinstruments.Thischapterreviewsthebasicsofequipmentandinstrumentation.

TheNeurosurgicalAtlas byAaronCohen-Gadol,M.D.

Everyoperatorshouldbeintimatelyfamiliarwithhisorher“special”setofinstruments.Thissetshouldbeveryabbreviatedandeachinstrumentshouldbeexploitedfornumerousmaneuvers(multifunctional)toadvanceoperativeefficiency.Simplicityisthekeytotechnicaladaptabilityandproficiency.Thesurgeonshouldbethoroughlyfamiliarwiththecapabilitiesandlimitationsofeachinstrument.Thewayaninstrumentisused,andnottheinstrumentitself,mostoftendefinesitssuccessinachievingtheoperativegoalateachsinglestep.

HeadFixation

Becausepatientpositioningisintegraltosuccessfulsurgery,anunderstandingoftheequipmentinvolvedforheadfixationisequallyimportant.Forsurgeriesthatdonotrequirestrictheadimmobilization,suchascranialemergenciesforhematomaevacuation,optionsincludethevariousdonutheadholdersandhorseshoeheadrests.

Proceduresintegratingstereotaxyormicrosurgicaltechniquesdemandstrictheadfixation.ThemostcommonlyusedheadfixationdeviceistheMayfieldskullclamp(IntegraLifeSciences,Plainsboro,NewJersey)thatusesthreepinstofixthecranium.

Figure2:Avarietyofheadfixationdevicesexistandanunderstandingoftheirindicationsisimportant.Thedonutandhorseshoeheadrests(AandB,respectively)arebestwhenfirmstabilizationisnotrequired(thatis,emergentcasesorhematomaevacuation).TheMayfieldskullclamp(C)isthemostcommonlyusedfixationdeviceandcanbecombinedwithstereotaxy.TheSugitaframe(D)isyetanotheroptionforstablecranialfixation.TheSugitausesfourpinsforcranialfixationandhasitsownself-retainingretractorsystem.

AlthoughIrarelyusefixedretractors,theskullclampscanbecoupledtotheBuddeHaloRetractorSystem(IntegraLifeSciences,Plainsboro,NewJersey)thatallowsaplatformfortheattachmentofretractorbladesandcanalsobeusedasanarmrestorhandrestbythesurgeon.

Figure3:TheBuddehalo(leftimage)andSugita(rightimage)retractorsareself-retainingandcanalsoserveasahandrestforthesurgeon.

Formoreinformation,pleaseseethePatientPositioningandSkullClampPlacementchapters.

OperatingRoomMicroscope

Themicroscopeisanintegralpartofmicrosurgery.Withitsillumination,magnification,andstereoscopicimaging,thisdeviceexpandstheoperator’svisionandallowsmicrosurgerywithouttheneedforfixedretractors.

Proficiencywiththemicroscopewilldramaticallyadvanceone’soperativeskill.Withenoughexperience,theoperatorwillrealizethatthemicroscopeisvirtuallyapartofhisorherface.Theflowofmicrosurgeryisverydependentupontheinteractionofthesurgeonwiththemicroscope.Themicroscopeshouldnotbeusedtoconductmacrosurgery.Everystageofsurgeryrequiresadifferentmagnificationlevel.Operatingunderanunnecessarilyhighlevelofmagnificationcandisorientthesurgeonandleadtoprematurefatigue.Similarly,operatingunderalowmagnificationlevelcanleadtoundetectedinjurytothesurroundingvesselsorunintended

residualtumor.

Theuseofamouthswitchdramaticallyimprovesoperativeefficiency.Itobviatestheneedtousemicroscopehandlestokeeptheimageinfocus.

CranialandDuralOpenings

Theinstrumentsforcranialandduralopeningscanandpreferablyshouldbestandardized.Theskinincisionismadewitha10-bladescalpelandbleedingiscontrolledwithbipolarelectrocautery.Raneyscalpclipscanalsobeappliedalongthescalpedgestocontrolbleeding.Fraziersuctionsareusedtocleartheoperativefield.

Thesesuctionscomeindifferentsizesandallowformanipulationofthesuctionlevelbythefingeroftheoperator.Muscleandgaleamaybereflectedofftheskullusingaperiostealelevator.Thescalpcanberetractedusingself-retainingretractorsandfishhooks.IncisionsonaflattersurfaceoftheskullcanberetractedusingWeitlanerretractors.Whenincisionsareonacurve,suchasduringamidlinesuboccipitalcraniotomy,Adsoncerebellarretractorsaremoreuseful.Iprefertousefishhooksformostpterionalandanteriorskullbasecraniotomiesbecausetheirforceofretractionismorecontrolledandthemusclecanbemobilizedeffectivelyalongthetrajectoryofthesubfrontalcorridor.

Figure4:Basicinstrumentsofmychoiceforastandardcraniotomy.

Figure5:Fishhooksareveryusefulduringreflectionofthescalpandtemporalismuscle.Theirforceofretractioncanbedirectedtowardspecificlocationsobstructingtheoperativetrajectory.

Figure6:Burrholesarecommonlymadewithaperforatorclutchdrillbit.Thesedrillbitshaveanautomaticstopmechanismwhentheinnertableispenetratedandaretypically14mmindiameter.

Iprefermakingburrholeswithanacorn-shapedbitbecausetheburrholesizecanbecontrolledmoreeffectively.Theautomaticstopmechanismoftheperforatorisnotalwayssensitiveorreliableenoughtostopontime;thisisespeciallyproblematicduringplacementofburrholesoverthevenoussinuses.Forthisreason,Iroutinelyuseanacornbit.

Figure7:Oncetheburrholesarecreated,theinnertablebonefragmentscanberemovedwithabonecurette,ora#1Penfielddissector.Theduraistypicallythoroughlystrippedfromtheoverlyinginnertableusinga#3Penfield.ThePenfieldinstrumentsareamongthemostusefulinstrumentsforcranialopeningand#1and#3dissectorsarecommonlyused.ThePenfielddissectorsaredemonstratedintheseimages;theirnumberscorrespondtotheirorderfromtoptobottom(upperimageandlefttoright(lowerimage).

Tomakethecraniotomybonycuts,Iuseahigh-speedside-cuttingdrillbitwithafootplatetocompletetheosteotomy.Theduramaybeadhesivetothemiddleoftheboneflapanda#3Penfielddissectorcanbeusedtoseparatethedura.

Figure8:LeksellandKerrisonrongeursmaybeusedforboneresection.Specifically,IremovethelateralsphenoidwingusingLeksellrongeurswhileburrholescanbeexpandedusingKerrisonrongeurs.Duringaretromastoidcraniotomy,thebone

overthevenousduralsinusescanbeshelledoutandsubsequentlyremovedusingKerrisonrongeurs.

Afterelevationoftheboneflap,astraightdrillbitisusedtocreatetheholesfor2or3duraltackingsuturesaroundtheedgesofthecraniotomy.

A15-bladescalpelcanbeusedtomaketheinitialduralopening,andnext,theMetzenbaumscissorsextendtheinitialdurotomy.

MicrosurgicalInstruments

Forbothoncologicalandvascularprocedures,adherencetotheprinciplesofmicrosurgeryisintegraltothesuccessoftheoperation.Theopeningofthearachnoidmembranescanbemadewithanarachnoidknifeandmicroscissors.Theplanessurroundingalesioncanbedissectedusingavarietyofinstruments,includingRhotonmicrodissectors.Sharpdissectionprotectsbluntinjurytothesurroundingnormalcerebrovascularstructures.

Figure9:TheRhotoninstrumentshavedifferentshapesandanglesandthusprovideflexibilitytoworkwithinavarietyofoperativeanglesandsmallspaces.

Figure10:Irrigationclearstheoperativefield,hydratesthetissues,andpreventsheatinjuryfromtheintenselightofthemicroscope.Iusea10-ccsyringeforirrigationduringmicrosurgery.

FormoredetailsaboutinstrumentsforskullbasemicrosurgicalprocedurespleaserefertotheTechnicalNuancesandInstrumentationchapterintheSkullBaseSurgeryvolume.

TumorDebulking/LesionRemoval

Thetextureandsizeofthetumornotonlydefinestheriskofitsresection,butalsotheinstrumentsneededforitsremoval.Besidestumorforceps,pituitaryrongeursplayanimportantroleduringtumordebulkingandmobilization.

Forfibrousskullbasetumorsadjacenttocriticalstructures,Iroutinelyuseanultrasonictissueaspirator.Thisdeviceallowsaggressiveinternaldebulkingofthetumorwhileminimizingpotentialtractioninjuryonthesurroundingcriticalcranialnervesandbrainstem.

Suctiontipsareoftenusedasbothadissectoranddynamicretractor.

Athoroughunderstandingofhowtocontrolsuctionpowerisnecessarytoavoidinjuringsensitivestructures.

Figure11:Moistcottonpattystripscomeindifferentlengthsandwidthsandareusedforbrainprotection,hemostasis,retraction,andmaintainingtumorborders.

CranialClosing

Afterensuringhemostasis,closurebegins.Ifthereisnotenoughnativeduraforawatertightclosure,aduraplastycanbecompletedusingapieceofpericranium.Syntheticdurasubstitutesand/orpericardiumareselectedbasedonthesurgeon’spreference.Ipersonallyavoidtheirusebecauseoftheassociatedriskofasepticinflammationandinfection.

Aplatingsystemisusedtoreattachtheboneflap.Typically,acombinationofburrholecovers,plates,and4-mmscrewsareusedtosecuretheboneflap.Cranioplastymayalsobenecessaryto

reconstructthecraniumandavoidcreatingcosmeticallyundesirableskulldefects.Scalpclosureisusuallydonewithabsorbable3-0vicrylstichesinthegaleaandstaplesornylonsutureintheskin.

PearlsandPitfalls

Understandingandmasteringthecapabilitiesandlimitationsofneurosurgicalinstrumentsiscriticalforconductingsuccessfuloperations.

Developmentofalimitedsetofstandardinstrumentsdramaticallyimprovesthesurgeon’soperativeefficiencyandminimizestheoperatingroomstaff’sconfusion.

DOI:http://dx.doi.org/10.18791/nsatlas.v1.ch06

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