www.bjorl.org
Brazilian
Journal
of
OTORHINOLARYNGOLOGY
ORIGINAL
ARTICLE
The
relationship
of
the
medial
roof
and
the
posterior
wall
of
the
maxillary
sinus
to
the
sphenoid
sinus:
a
radiologic
study
夽
Seung
Ju
Lee
EuljiHospital,EuljiUniversity,CollegeofMedicine,DepartmentofOtorhinolaryngology,HeadandNeckSurgery,Seoul, SouthKorea
Received15March2016;accepted14April2016 Availableonline9May2016
KEYWORDS Computed tomography;
Medialmaxillarysinus roof;
Posteriorwallof maxillarysinus; Sphenoidsinus
Abstract
Introduction:The medialmaxillary sinus roof is a ridge formed by the superior margin of the maxillarysinus antrostomy.The posteriorwallofthemaxillarysinusisalways included inoperativefields.
Objective: Toperformaradiologicstudyassessingtheutilityofthemedialmaxillarysinusroof andtheposteriorwallofthemaxillarysinusasfixedlandmarksforprovidingasaferouteof entryintothesphenoidsinus.
Methods:We reviewed 115 consecutive paranasal sinus Computed Tomographic scans (230 sides)ofKorean adult patients performedfrom January 2014toDecember 2014. Usingthe nasalfloorasareferencepoint,theverticaldistancestothehighestpointofthemedial maxil-larysinusroof,thesphenoidostiumandanteriorsphenoidroofandfloorweremeasured.Then theverticaldistancesfromthehighestpointofthemedialmaxillarysinusrooftothesphenoid ostiumandanteriorsphenoidroofandfloorwerecalculated.Thecoronaldistancefromthe posteriorwallofthemaxillarysinustothesphenoidostiumwasdetermined.
Results:The averageheightofthe highestpointofthemedialmaxillarysinusroofrelative tothenasal floorwas measuredtobe33.83±3.40mm.The averageverticaldistancefrom thehighestpointofthemedialmaxillarysinusrooftothesphenoidostiumandanterior sphe-noidroofandfloorwas1.79±3.09mm,12.02±2.93mm,and6.18±2.88mmrespectively.The averagecoronaldistancefromtheposteriorwallofthemaxillarysinustothesphenoidostium was0.78mm.Thesphenoidostiumwasbehindthecoronalplaneoftheposteriorwallofthe maxillarysinusmostfrequentlyin103sides(44.4%).Itwasinthesamecoronalplanein68sides (29.3%)andinfrontoftheplanein61sides(26.3%).
夽
Pleasecitethisarticleas:LeeSJ.Therelationshipofthemedialroofandtheposteriorwallofthemaxillarysinustothesphenoidsinus: aradiologicstudy.BrazJOtorhinolaryngol.2017;83:375---80.
E-mail:entdoc@eulji.ac.kr
PeerReviewundertheresponsibilityofAssociac¸ãoBrasileiradeOtorrinolaringologiaeCirurgiaCervico-Facial.
http://dx.doi.org/10.1016/j.bjorl.2016.04.007
Conclusions:Themedialmaxillarysinusroofandtheposteriorwallofthemaxillarysinuscan beusedasareliablelandmarktolocalizeandtoenableasafeentryintothesphenoidsinus. © 2016 Associac¸˜ao Brasileira de Otorrinolaringologia e Cirurgia C´ervico-Facial. Published by Elsevier Editora Ltda. This is an open access article under the CC BY license (http:// creativecommons.org/licenses/by/4.0/).
PALAVRAS-CHAVE Tomografia
computadorizada; Tetomedialdoseio maxilar;
Paredeposteriordo seiomaxilar; Seioesfenoide
Relac¸ãodotetomedialeparedeposteriordoseiomaxilarcomooseioesfenoidal:
estudoradiológico
Resumo
Introduc¸ão:O tetomedial do seiomaxilaré uma crista formada pela margem superior da antrostomiadoseiomaxilar.Aparedeposteriordoseiomaxilarésempreincluídaemcampos cirúrgicos.
Objetivo:Realizar estudoradiológicoavaliando autilidadedotetomedialdoseiomaxilare daparedeposteriordoseiomaxilarcomoreferênciasanatômicasfixasparafornecerumavia seguradeabordagemaoseioesfenoidal.
Método: Foramanalisados115examesdetomografiacomputadorizadaconsecutivosdosseios paranasais(230lados)depacientesadultoscoreanosrealizadosdejaneirode2014adezembro de2014.Usandooassoalhonasalcomopontodereferência,asdistânciasverticaisentreoteto medialdoseiomaxilareoóstioesfenoidaleentreotetoeoassoalhoesfenoidalanteriorforam medidas.Emseguida,asdistânciasverticaisdopontomaisaltodotetomedialdoseiomaxilar eoóstioesfenoidaleentreotetoeaoassoalhoesfenoidalanteriorforammedidas.Adistância coronaldaparedeposteriordoseiomaxilaraoóstioesfenoidalfoideterminada.
Resultados: Aalturamédiadopontomaisaltodotetomedialdoseiomaxilaremrelac¸ãoao assoalhonasalfoimedidacomosendo33,83±3,40mm.Adistânciavertical médiadoponto maisaltodotetomedialdoseiomaxilaratéoóstioesfenoidaledotetoaoassoalhoesfenoidal anteriorfoide1,79±3,09mm,de12,02±2,93mme6,18±2,88mm,respectivamente.A dis-tânciacoronalmédiadaparedeposteriordoseiomaxilaraoóstioesfenoidalfoide0,78mm.O óstioesfenoidalestavaportrásdoplanocoronaldaparedeposteriordoseiomaxilarcommais frequênciaem103lados(44,4%).Omesmoseencontravanoplanocoronalem68lados(29,3%) enafrentedoplanoem61lados(26,3%).
Conclusões:Otetomedialdoseiomaxilareaparedeposteriordoseiomaxilarpodemserusados comopontosdereferênciaconfiáveisparalocalizarepossibilitarumaabordagemseguraaoseio esfenoidal.
© 2016 Associac¸˜ao Brasileira de Otorrinolaringologia e Cirurgia C´ervico-Facial. Publicado por Elsevier Editora Ltda. Este ´e um artigo Open Access sob uma licenc¸a CC BY (http:// creativecommons.org/licenses/by/4.0/).
Introduction
ForsafeandeffectiveEndoscopicSinusSurgery(ESS),
pre-operativeevaluationof ComputedTomographic(CT)scans
are required to identify the extent of disease and
criti-calanatomiclandmarks. However,during realoperations,
landmarksonCTscansoftenhavesignificantanatomic
varia-tionsorareobscuredbyblood,polypsorotherinflammatory
orpostsurgicalchanges.Accordingly,othermore
unchang-ing and fixed anatomic landmarks are needed. The ideal
anatomiclandmarksmustbeconsistent,easytofindevenin
thedistortednasalcavities,andprovidethesurgeonwitha
senseofdirectionasoneproceedsposteriorly.
Themedialmaxillarysinusroof(MMSR)isaridgeformed
by the superior margin of the maxillary sinus antrostomy
and representsthe level of the medial orbital floor.1---3 It
isborderedbythe inferioredgeofthe laminapapyracea,
and has been an useful landmark for finding the lamina
papyracea.4 It is easily identifiableduring ESS in spite of
previous surgery or severe inflammatory disease of nasal
cavityandparanasalsinuses.Recently,thisridgehasbeen
regardedasanimportantintraoperativelandmarkin
locat-ingthesphenoidsinus.1---3
Casiano measured the vertical distance from the
pos-terior medialorbital floor tothesphenoidsinus floorand
thesphenoidsinusheightonhumancadaverheads.He
con-cludedthatthesphenoidsinuswillbeenteredconsistently
at thelocationofthe sphenoidostium at thelevelof the
posteriormedialorbitalfloor.1InHarveyetal.’sstudy,the
maxillarysinusroofcouldbeusedasarobustlandmarkto
enableasafeentrytothesphenoidsinuswhennormal
struc-turesarenotavailable.2InLeeetal.’sstudy,theMMSRwasa
reliablepreoperativereferencepointforguidingsafe
surgi-calentryintothesphenoidsinus.3TheconclusionsofHarvey
etal.andLeeetal.werebasedontheCTstudy,butfew
objectivedataareavailableatthismoment.
Theposteriorwallofthemaxillarysinuswhichisalways
Thus,it mayalso serveasareliable landmark inlocating
theanteriorwallofthesphenoidsinus.Inthepreviousstudy
ofCasiano,theposteriorwallofthemaxillarysinusis
sev-eral millimeters in front of the approximate level of the
anteriorsphenoidwallinthe coronalplane.Hesuggested
thattheposteriorwallofthemaxillarysinusasseenthrough
the antrostomy, demarcate the approximatelevel, in the
coronalplane,oftheanteriorwallofthesphenoidsinus.1
But, to the best of our knowledge, there has been no
detailed study concerning the coronal distance from the
posteriorwallofmaxillarysinustothesphenoidostium.
The aim of this study was toperform radiologic study
assessingtheutilityoftheMMSRandtheposteriorwallof
themaxillarysinusasfixedlandmarksfor providingasafe
routeofentryintothesphenoidsinus.
Methods
We retrospectively reviewed 115 consecutive paranasal
sinustriplanarCTscansofKoreanadultpatientsperformed
fromJanuary2014toDecember2014,givingatotalof230
sidesfor analysis.Eachpatient’s informationsuchasage,
gender, and the purpose of the scan has been collected.
These patientsunderwentCTscanningfor theassessment
of various nasal symptoms suchas nasal obstruction,
rhi-norrhea, posterior nasal dripping, anosmia, facial pain,
headache, etc. Patientsrequiring ESS withCT findings of
chronicparanasalsinusitiswereexcluded.Scanswith
hazi-ness of posterior ethmoid or sphenoid sinuses were also
excluded.Scanswereexcludediftherewasalterationofthe
posteriorethmoidorsphenoidsinusskullbase eitherfrom
previoussurgeryorfromothernoninflammatoryconditions.
Inaddition,scanswereexcludediftheostiumofthe
sphe-noidsinus wasnotidentifiedonthe sagittalCTscan. The
study protocol for a retrospective CT review for research
purposes wasexempt fromtheInstitutional Review Board
review.
CTscansofthenasalcavitiesandparanasalsinuseswere
performed withcontiguous axial cutsof 2.5mm thickness
(120kVp,220mAs,FOV180mm×180mm)onGEDiscovery
750HD CT scanners (GE Medical Systems, Milwaukee, WI,
USA).TheCTdatawerethenreconstructedintocoronaland
sagittalimagesof2mmthicknessbyGEworkstationAdw4.5
software(GE,USA).Measurementsweredoneasfollows:
1. MaximumheightoftheMMSRrelativetothenasalfloor
(MS-NF)(Fig.1A).ThehighestMMSR(hMMSR)wasfound
by scrolling through the coronal images. The slice in
whichtheMMSR washighest relativetothenasalfloor
withinanyareaofthemaxillarysinuswasidentified.The
verticaldistancefromthenasalfloortothehMMSRwas
measured.
2. Verticaldistance fromtheinferior marginof the
sphe-noidostiumtothehMMSR(SO-MS).Bonyopeningatthe
sphenoidface wasidentifiedboth onaxialandsagittal
CTimages.The sagittalslice centeredonthesphenoid
ostiumwasusedtomeasuretheverticaldistancefrom
thenasalfloortothesphenoidostium(SO-NF)(Fig.1B).
SO-MSwascalculatedbysubtractingMS-NFfromSO-NF.
A sphenoid ostium inferior to the hMMSR was given a
negativevalue.
3. Vertical distance fromtheanteriorsphenoidsinus roof
tothehMMSR(SR-MS).Thesinusroofwasidentifiedona
samesagittalCTslicecenteredonthesphenoidostium.
The verticaldistance fromthe nasal floorto sphenoid
sinus roofwasmeasured (SR-NF)(Fig.1C).Ifan Onodi
cellwasfound,theverticaldistancewasmeasuredfrom
the nasal floor tothe skull base at the coronal plane
oftheanteriorsphenoidface.SR-MSwascalculatedby
subtractingMS-NFfromSR-NF.
4. Vertical distancefromthehMMSRtotheanterior
sphe-noidsinusfloor(MS-SF).Thesinusfloorwasidentifiedon
asamesagittalCTslicecenteredonthesphenoidostium.
The verticaldistance fromthe nasal floorto sphenoid
sinus floorwas measured (SF-NF) (Fig.1D). MS-SF was
calculatedbysubtractingSF-NFfromMS-NF.
5. Thecoronaldistancefromtheposteriorwallofthe
max-illarysinustothesphenoidostium. Triplanardisplayof
CTdatainaxial,sagittal,andcoronalplaneswas
simul-taneouslyviewedandanalyzed.Thesphenoidostiumin
theaxialplanewasidentified.Themostposteriorpoint
of the posterior wall of the maxillary sinus was
iden-tified by scrolling through the sagittal images. It was
usually located at the medial part of maxillary sinus.
Usingthe PictureArchivingandCommunicationSystem
(PACS)cross-referencingtool,therelationshipbetween
themostposteriorpointoftheposteriorwallofthe
max-illarysinusinthesagittalplaneandthesphenoidostium
intheaxialplanewasdetermined.Thesphenoidostium
wasbehind(Fig.2A)or in frontsof (Fig.2B)the
coro-nal plane of the most posterior point of the posterior
wallofthemaxillarysinus.Oritwasinthesameplane
(Fig.2C).Thedistancebetweenthetwostructureswas
determinedbythenumberoftheintervening2mm-thick
coronalslicesbetweenthem.Asphenoidostiumanterior
tothecoronalplaneof themostposteriorpointofthe
posteriorwallofthemaxillarysinuswasgivenanegative
value.
Measurementsweremadeforboththerightandleftsides
ofeachpatient.Pairedttestswereusedtoindicatewhether
meandifferencesexistedbetweenrightandleftsides.
Sta-tisticalanalysiswasdoneusingSPSSversion15(SPSSInc.,
Chicago,IL).Statisticalsignificancewasdefinedasp<0.05.
Results
Measurementsweretakenfrom115CTscans,givingatotal
of230 sidesfor analysis.The study group consistedof 53
(46.1%)femalesand62(53.9%)males.Themeanpatientage
was40.4years(range,18---81years).T-testdidnot
demon-strateanysignificantdifferencebetweentherightandleft
sidesinanydistancemeasuredinthisstudy(p>0.05).The
mean,standarddeviation andrangeofthe measurements
areseeninTable1.
The average height of the highest MMSR relative to
the nasal floor was measured to be 33.83±3.40mm,
rangingfrom26.37 to43.98mm. Theaveragevertical
dis-tancefromthe sphenoidostium tothe highest MMSR was
1.79±3.09mm,rangingfrom−5.60to10.84mm.The
aver-ageverticaldistancefromtheanteriorsphenoidsinusroof
PE
A
B
D
C
SR
90º
NF NF
90º SF NF 90º SO
NF MS
Figure1 (A)CoronalCTimagedemonstratingtheverticaldistancefromthenasalfloor(NF)tothehighestmedialmaxillarysinus roof(MS)andposteriorethmoidskullbase(PE).(B)SagittalCTimagedemonstratingtheverticaldistancefromthenasalfloor(NF) tothesphenoidostium(SO).(C)SagittalCTimagedemonstratingtheverticaldistancefromthenasalfloor(NF)totheanterior sphenoidsinusroof(SR).(D)SagittalCTimagedemonstratingtheverticaldistancefromthenasalfloor(NF)totheanteriorsphenoid sinusfloor(SF).
Table1 Summaryofverticaldistancesinourstudy.
Measurement Mean(mm)±SD Range(mm)
hMMSR---nasalfloor 33.83±3.40 26.37to43.98
hMMSR---sphenoidostium 1.79±3.09 −5.60to10.84
hMMSR---sphenoidroof 12.02±2.93 4.22to18.29
hMMSR---sphenoidfloor 6.18±2.88 1.06to12.85
hMMSR,highestmedialmaxillarysinusroof;SD,standarddeviation.
4.22to18.29mm. The averagevertical distancefromthe highest MMSR to the anterior sphenoid sinus floor was 6.18±2.88mm,rangingfrom1.06to12.85mm.
Thedistributionofthenumberoftheslicesbetweenthe coronalplane of the posterior wall of themaxillary sinus andthesphenoidostiumisdisplayedinFig.3.Thesphenoid
ostiumwasbehindthe coronalplane oftheposteriorwall
ofthemaxillarysinusmostfrequentlyin103sides(44.4%).
It wasin the same coronal plane in 68 sides(29.3%) and
infrontoftheplane in61sides(26.3%).Onaverage,0.39
coronalslicewaspresentbetweenthetwostructureswith
astandarddeviationof1.42slices.AstheCTslicethickness
inourstudywas2mm, theaveragedistance betweenthe
twostructureswas0.78mm.
Discussion
Inthisstudy,themeanofthemaximumheightoftheMMSR
wasmeasuredtobe33.83mm,verysimilarto33.45mmin
Lee etal.’sstudy and 33.9mm inHarveyetal.’s study.2,3
We think that the highest MMSR can be easily identified
endoscopicallyatthisheightrelativetothenasalfloorafter
maxillaryantrostomyareperformed.
Toenterthe sphenoidsinussafely, itssize,shape,and
relationship to the optic nerve and carotid artery should
bedeterminedby reviewingtriplanarCTscans,
preopera-tively.The sphenoidsinus canbesafely enteredinferiorly
andmedially,abovethearchoftheposteriornasalchoana
andclosetotheposterioraspectoftheseptum.4,5The
supe-riorturbinateservedasakeylandmark.6---8 However,when
thesuperiorturbinateisnotavailable,previouslyresected
orreplacedbypathology,superiordissectionwillpotentially
damage the skull base. This may be especially important
whentheostiumcannotbevisualizedeitherdueto
bleed-ing,polyps,andinflammatorydiseaseoriftechnologiessuch
asimageguidancenavigationarenotavailable.Inthis
situ-ation,otherlandmarksareneeded.
In Casiano’s study with cadaveric model, the medial
orbital floorwasnotedas39%of thesphenoidheight. He
suggestedthatat theleveloftheposterior medialorbital
Figure2 (A)Theleftsphenoidostium(arrowsinbandd)is2slicesbehindthecoronalplaneoftheposteriorwalloftheleft maxillarysinus(a).(B)Therightsphenoidostium(arrowsinbandd)isonesliceinfrontofthecoronalplaneoftheposteriorwallof therightmaxillarysinus(a).(C)Theleftsphenoidostium(b)isinthesamecoronalplaneoftheposteriorwalloftheleftmaxillary sinus(a).
inferiortomiddlethird,whichalsocorrespondstothe
loca-tionofthesphenoidostiuminmostcases.1Recently,ithas
becomepossibletoevaluateCTimagesthree-dimensionally
withtheadvancementof multiplanarreconstruction
tech-nique.SagittalCTimagescanhelpuspromotethesafetyof
ESS.InthefirstradiologicstudybyLeeetal.,relativetothe
maxillarysinusroof,thesphenoidostiumwasidentifiedat
averticalheight2.76mmsuperiortothehighestMMSR.3In
thisthree-dimensionalradiologicstudy,thesphenoidostium
wasidentifiedataverticalheight1.79mmsuperiortothe
highestMMSR,rangingfrom−5.60to10.84mm.Ourresult
is0.97mmshorterthan thatintheprevious report.Thus,
thereisquiteasmalldifferencebetweenourresultandthat
ofthepreviousreport.
The mean vertical distance from the highest MMSR to
the anterior sphenoid roof at the sagittal slice in which
thesphenoidostiumwasidentifiedinourstudy(12.02mm)
wasnearlyidenticaltothatinthepreviousstudy(12mm).3
Harveyet al.measured at the sagittalplane centered on
thesuperiorturbinate,andthedistance was11.77mm on
average.2Theanteriorsphenoidsinusfloorisapproximately
6mminferiortothemaxillarysinusroofinLeeetal.’sstudy
and6.18mminthecurrentstudy.3
Takentogether,thefindingsofourstudycorroborate
ear-lierobservations.To simplifythedatainthisandprevious
studies,theostiumofthesphenoidsinusandthesphenoid
sinusroofareabout2---3mmand11---12mmsuperiortothe
highest MMSR and the sphenoid sinus floor is about 6mm
inferiorto thehighest MMSR. We thinkthat the sphenoid
ostiumcanbefoundeasilyattheheightofthehighestMMSR
andthisrelationshipishelpfulespeciallywhenthesphenoid
sinusisenteredbytransethmoidalapproach.Therefore,the
MMSRcanbeagoodlandmarkforentrytothesphenoidsinus
whileitiskeptinviewonthemonitorscreenandreferred
tothroughoutthesurgery.
Inourmeasurements,theminimumdistancebetweenthe
MMSRandsphenoidsinusroofwas4.22mm.TheMMSRmay
70
60
Number of sides
50
40
30
20
10
0
–4 –3 –2 –1 0 1 2 3 4 1 1
21 38
68
45 47
8 3
Figure3 Thedistributionofthenumber ofthe2mm-thick slicesbetween thecoronalplaneoftheposteriorwallofthe maxillarysinus and the sphenoid ostium. A sphenoid ostium anteriortothecoronalplaneofthemostposteriorpointofthe posteriorwallofthemaxillarysinuswasgivenanegativevalue.
providesareasonablemarginofsafetyfromtheskullbase
andthesphenoidsinuscanbeenteredsafelywithout
dam-age tothe skull base at the height of the highest MMSR.
Lastly,attemptingtoenterthesphenoidtooinferiorly
rel-ativetothe MMSR canbe difficultdue tothickerbone of
sphenoclivaljunction.
Casianoperformeddirectmeasurementsaftersectioning
thecadaverheadssagittallyinthemidlineandendoscopic
measurementsusingstraight andcurvedsuction tip.1 The
anteriorfaceofthesphenoidandtheposteriorwallofthe
maxillarysinuswasfoundtobeapproximately70mmfrom
thebaseofthecolumella.
InallspecimensincludedinCasiano’sstudy,theanterior
face of sphenoid (at the medial orbital floor level) was
approximately2---4mmmoreposterior,inthecoronalplane,
thantheposterior wallofthemaxillarysinus. But,inthis
three-dimensional radiologic study, the average coronal
distance between the two structures was0.78mm, much
shorterthanthepreviousresult.Oneofthereasonsforthis
difference might be the difference in the measurement
method used. Remarkably, though the sphenoid ostium
wasbehind thecoronalplane ofthe posteriorwall ofthe
maxillarysinus mostfrequently(44.4%),ourstudyshowed
that it may be in the same coronal plane or in front of
the coronal plane of the posterior wall of the maxillary
sinus.Tothebestofourknowledge,thisisthefirstreport
measuringthecoronaldistancebetweentheposteriorwall
of themaxillary sinus and thesphenoid ostium. We think
thatthisanatomicrelationshipalongwiththeMMSRwillbe
ofgreatassistancetoESSsurgeons.Theostiumofsphenoid
sinuscanbemucheasilyidentifiedjustabovetheheightof
theMMSRandjustbehindthecoronalplaneoftheposterior
wallofmaxillarysinus.
Abovementioned mean valuesinthis andtheprevious
publicationsarenotabsolute.AsshowninTable1andFig.3,
theverticalandcoronaldistancesofeachpatientcanvary
greatlywithrelativelywiderange.However,thedifferences
inmeasurementswerewithinafewmillimetersonaverage,
suggestingthatthesedifferencesmaynotaffectthe
over-allclinicalusewhenperformingESS.The individualvalues
foreachpatientwhichshowlargevariationaccordingtothe
age,sex,andthedegreeofthemaxillarysinus
pneumatiza-tionshouldbekeptinmindwhileperformingsphenoidotomy
usingtheMMSRandtheposteriorwallofthemaxillarysinus
asfixedanatomicallandmarks.
Conclusions
TheMMSRandtheposteriorwallofthemaxillarysinuscan
beusedasareliablelandmarktolocalizeandtoenablea
safeentryintothesphenoidsinus.
Conflicts
of
interest
Theauthordeclaresnoconflictsofinterest.
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