表现为眼眶（炎性）假瘤的视神经束膜炎http://www.cnophol.com2009-4-1515:51:50中华眼科在线
DISCUSSION
Opticperineuritis（OPN）isalsoknownasperiopticneuritis,anddescribesinflammationofopticnervesheathwithoutinflammationoftheopticnerveitself[4,5].Theinflammationisassumedtoaffecttheopticnervesheathonlywhenthereisevidenceofopticnervedysfunctionwithnormalintracranialpressure[5].Recently,theopticperineuritishasbeenfocusedontheidiopathicinflammatoryresponseofopticnervesheath[4,5].Opticperineuritisoccasionallyoccursasamanifestationofspecificinfectiousorinflammatorydisorder,eg.Wegenergranulomatosis,giantcellarteritisorinitialpresentationofsarcoidosis[6,7].
Opticperineuritisisararepresentationanditisonesubclassificationofidiopathicorbitalinflammationororbitalpseudotumor[1].Otherorbitalstructuresthatmaybeinvolvedarelacrimalgland（dacryoadenitis）,extraocularmuscles（myositis）,sclera（scleritis）ororbitalfat[1].IdiopathicorbitalinflammationinvolvingtheorbitalapexiscalledTolosoHuntsyndrome[1].Ittypicallyproducedpainfulexternalophthalmoplegiaregardlessofcavernoussinusinvolvement[1].Acuteonsetoforbitalpain,limitedocularmotilityandproptosisarecharacteristicpresentationsofidiopathicorbitalinflammationafterexcludingothersecondaryinflammationsorinfections[1].Somepatientsdonotpresentclassicalsignsandsymptomsoforbitalpseudotumor,makingorbitalimagingavitallyimportantinvestigationtoascertainthediagnosis[1].Asinourcase,patientpresentedwithminimalinflammationofconjunctivawithmarkedlyreducedopticnervefunctionandocularmotility.However,therewasnosignofproptosis.So,clinicallyitwasdifficulttodistinguishbetweenopticperineuritisandretrobulbaropticneuritis.MostofclinicalfeaturesofpatientwithOPNarealsolikelytobemisdiagnosedofhavingopticneuritis（ON）[4].However,demographicdataofopticperineuritisshowmostpatientswithOPNarewomenwithbroaderrangeofage（36%aremorethan50yearsold）[4].ThemeanageofOPNpatientsisolderthanpatientswithopticneuritis[4].PatternofvisuallossisalsodifferentinapatientwithOPNcomparedtoON.InOPNpatientvisuallossprogressesoverseveralweeksbeforethecorrectdiagnosisismadeandcommonlyhassparingofcentralvision[4],whileinONpatientthevisuallossprogresseswithinfewdaysandsparingofcentralvisionislesscommon.
InOPN,theinflammationofextraocularmusclecausesmotilitydisturbanceasoccurredinthispatient.OthersignsthatmayhelptodiagnoseOPNaresubtleptosis,chemosisanddiplopia（orbitalinvolvement）[4].IncontrasttoONpatient,abnormaleyemotilityandtheothersignsmentionedarenottypicalfeaturesunlessitisassociatedwithbrainsteminvolvementduetomultifocaldemyelinatingdisease[5].However,somepatientswithOPNalsodonothaveanyproptosisorophthalmoplegiawhichmimicretrobulbaropticneuritis[8,9].
ThediagnosisofOPNistypicallybasedoncombinationofclinicalandradiographicimagingfindingsparticularlymagneticresonanceimaging（MRI）[4].OpticnervebiopsyisnotindicatedinmostcasesofsuspectedOPN[1,4].ThecharacteristicpatterninneuroimagingofOPNtypicallyshowsenhancementofopticnervesheath（“tramtrack”onaxialviewand"doughnut"oncoronalview）asfoundinourpatient[4].Therewaspresenceofstreakyenhancementoforbitalfat[9]anditwasalsofoundinherMRI.InanotherpublishedcasereportofOPN,MRIshowedenhancementofopticnervesubstanceduetoinflammationofintraneuralpialseptaandopticnervesheath[9].ThesechangesinneuroimagingarenotfoundinpatientswithtypicaldemyelinatingON.ThoseradioimagingfindingsarebestobtainedfromMRIscansspecificallytheuseofdedicatedorbitalviewswithfatsuppressionandgadolinium[9].Computedtomographicscanning,however,doesnotusuallygiveadequatespatialresolutiontodistinguishperineuralenhancementfromintraneuralenhancementasfoundindemyelinatingON[4].Furthermore,thehighresolutionCTimagingisassociatedwithradiationexposureandmayputrisktoothermortalityormorbidityduetoiodinatedcontrast[9].
ItisimportanttodifferentiatebetweenOPNandONfortworeasons.Thetreatmentandprognosisaredifferent.PatientwithOPNwillrespondtocorticosteroidsorantiinflammatoryagentsandmayneedtoprolongthetreatmenttopreventrecurrence.Ifnottreated,thepatientwillcontinuetolosevision.IncontrastwithON,thetreatmentismorecontroversial[10].
CorticosteroidshavenotbeenproventoinfluencethevisualoutcomeandmanypatientsdidnotreceivethetreatmentinOPN.Therouteofadministrationanddosagearealsodifferent.InOPN,oralcorticosteroidwiththedosageof80mg/dayisrecommendedbutcontraindicatedinONbecauseitmayincreasetherateofrecurrenceofopticneuritis[11].ThecourseofcorticosteroidtreatmentinONisshorter（twoweeks）butitisnotlongenoughforOPN.
TheprognosisofOPNisgenerallyexcellent[4].ThepatientshavingOPNarenotatriskofdevelopingmultiplesclerosisbutarelikelytohaverecurrentvisuallossinfuture.ComparedtoONpatients,theyareathighriskofdevelopingmultiplesclerosisandneedtocounsel.
Inconclusion,opticperineuritisisararepresentationofidiopathicorbitalinflammationsyndromethatclinicallymaymimicretrobulbaropticneuritis.Earlydiagnosistodifferentiatethetwoclinicalentitieswillresultinbettermanagementandimprovethevisualprognosis.
【参考文献】
1AmericanAcademyofOphthalmology.Basicandclinicalsciencecourse:orbit,eyelids,andlacrimalsystem.Section7.SanFrancisco:AAO;20022003
2NobleSC,ChandlerWF,LloydRV.Intracranialextensionoforbitalpseudotumor:acasereport.Neurosurgery1986;18:798801
3KayeAH,HahnJF,CraciumA,HansonM,BerlinAJ,TubbsRR.Intracranialextensionofinflammatorypseudotumoroftheorbit.Casereport.JNeurosurg1984;60:625629
4PurvinV,KawasakiA,JacobsonDM.Opticperineuritis:clinicalandradiographicfeatures.ArchOphthalmol2001;119:12991306
5MillerNR,NewmanNJ.Theessentials.Walsh&HoytsClinicalNeuroOphthalmology.5thed.LippincottWilliams&Wilkins;1999
6NassaniS,CocitoL,ArcuriT,FavaleE.Orbitalpseudotumorasapresentingsignoftemporalarteritis.ClinExpRheumatol1995;13:367369
7YuWaiManP,CromptonDE,GrahamJY,BlackFM,DayanMR.Opticperineuritisasarareinitialpresentationofsarcoidosis.ClinExp
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