Instrumentation Surgical instrumentation has become exponentially more complex in recent decades. I believe simplicity in instrumentation is key to operative efficiency. Figure 1: Cushing’s instrument table in late 1920’s. Please note the use of Bovie electrocautery on the left hand side (Courtesy of Cushing Brain Tumor Registry at Yale University). The surgeon’s operative maneuvers should follow one another seamlessly, similar to movements in a concerto flowing together to form a masterpiece. This virtuosity is founded upon movements that meld together without hesitation. To achieve this level of technical competence and finesse, the surgeon must have a mastery of the desirable macro and micro instruments. This chapter reviews the basics of equipment and instrumentation. The Neurosurgical Atlas by Aaron Cohen-Gadol, M.D.
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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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