Neuromyelitis Optica in Portugal (NEMIPORT) - A Multicentre Study

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ContentslistsavailableatScienceDirect

Clinical

Neurology

and

Neurosurgery

j ou rn a l h o m epa g e : w w w . e l s e v i e r . c o m / l o c a t e / c l i n e u r o

Neuromyelitis

optica

in

Portugal

(NEMIPORT)

–

A

multicentre

study

Joana

Domingos

a,∗,1

_,

_Luís

_Isidoro

b,1

_,

_Rita

_Figueiredo

c,1

_,

_Marisa

_Brum

d,1

_,

Carlos

Capela

e,1

_,

_Pedro

_Barros

f,1

_,

_Ernestina

_Santos

a,g

_,

_Maria

_do

_Carmo

_Macário

b

_,

José

Pinto

Marques

d

_,

_Rui

_Pedrosa

e

_,

_José

_Vale

h

_,

_Maria

_José

_Sá

i,j

a_Centro_Hospitalar_do_Porto_–_Hospital_de_Santo_António,_Department_of_Neurology,_Largo_Prof._Abel_Salazar,_4099-001_Porto,_Portugal

b_Centro_Hospitalar_e_{Universitário}_de_Coimbra,_EPE,_Department_of_Neurology,_Avenida_Bissaya_Barreto,_Prac¸_eta_Prof._Mota_Pinto,_3000-075_Coimbra,

Portugal

c_Centro_Hospitalar_de_São_João,_EPE,_Department_of_{Neuroradiology,}_Alameda_Prof._Hernâni_Monteiro,_4200-319_Porto,_Portugal d_Centro_Hospitalar_de_Setúbal,_EPE,_Department_of_Neurology,_Rua_Camilo_Castelo_Branco,_2910-446_Setúbal,_Portugal

e_Centro_Hospitalar_de_Lisboa_Central,_EPE,_Department_of_Neurology,_Alameda_Santo_António_dos_Capuchos,_1169-050_Lisboa,_Portugal f_Centro_Hospitalar_de_Vila_Nova_de_Gaia,_EPE,_Department_of_Neurology,_Rua_Conceic¸_ão_Fernandes,_4434-502_Vila_Nova_de_Gaia,_Portugal g_UMIB,_Instituto_de_Ciências_Biomédicas_Abel_Salazar,_Universidade_do_Porto,_Porto,_Portugal

h_Hospital_Beatriz_Ângelo,_Department_of_Neurology,_Avenida_Carlos_Teixeira,_3,_2674-514_Loures,_Portugal i_Centro_Hospitalar_de_São_João,_Department_of_Neurology,_Alameda_Prof._Hernâni_Monteiro,_4200-319_Porto,_Portugal j_Faculty_of_Health_Sciences,_University_Fernando_Pessoa,_Porto,_Portugal

a

r

t

i

c

l

e

i

n

f

o

Articlehistory:

Received20September2014 Receivedinrevisedform3March2015 Accepted5April2015

Availableonline11April2015 Keywords: NMO Neuromyelitisoptica Aquaporin4 AQP4 Autoimmunedisorders

a

b

s

t

r

a

c

t

Background:NeuromyelitisOptica(NMO)isaninﬂammatorydemyelinatingdiseaseoftheCNS.There havebeenfewepidemiologicstudiesonNMO,noneinPortugal.

Objective:Toanalyzetheclinical,biologicalandMRIcharacteristicsfromacohortofPortuguesepatients whofulﬁlledtheWingerchuk2006NMO/NMOSDcriteria.Toidentifyandcharacterizethosewhohad concomitantautoimmunediseaseorcirculatingautoantibodies.

Methods:Weperformedanobservational,retrospective,multicenterstudyin5HospitalCentersin Portugal.

Results:Sixty-sevenpatientsfulfilledtheinclusioncriteria.TheyweremainlyCaucasian,55female. Medianageatonsetwas32.0yearsandmeanfollow-up7.4±6.0years.Twenty-onepatientswere definiteNMOandopticneuritis(ON)themostfrequentinitialpresentation.Forty-sixwereclassified asNMOspectrumdisorders.ThemainsubtypeswererecurrentONandsinglelongitudinallyextensive transversemyelitis.Twenty-fourpatientshadpositiveAQP4-IgG.Twenty-threehadothercirculating autoantibodies.Fifteenoutof67patientshadconcomitantautoimmunedisease.Therewasasignificant correlationbetweenthepresenceofautoimmunediseaseandthepositivityforAQP4-IgG.Fivepatients died,alldefiniteNMO.

Conclusion:ThisistheﬁrststudyaboutthisrarediseaseinPortugal.Demographicfeaturesweresimilar tootherstudies.Theexistenceofconcomitantautoimmunediseasewassigniﬁcantlyassociatedwith seropositivityforAQP4-IgG.

∗ Correspondingauthor.

E-mailaddresses:joanadomingos@hotmail.com(J.Domingos), luisisidoro@yahoo.com(L.Isidoro),ritaﬁg7@gmail.com(R.Figueiredo), marisatbrum@gmail.com(M.Brum),cmc120@gmail.com(C.Capela), pedrojgbarros@gmail.com(P.Barros),ernestina.santos@gmail.com (E.Santos),carmo.macario@gmail.com(M.d.C.Macário), josefernandopintomarques@gmail.com(J.PintoMarques),

rui.pedrosa@chlc.min-saude.pt(R.Pedrosa),Josevale.neuro@gmail.com(J.Vale), mjsa@med.up.pt(M.J.Sá).

1 _These_authors_have_contributed_equally_to_this_work.

1. Introduction

NMOisarareinﬂammatorydemyelinatingdiseaseofthe cen-tralnervous system(CNS)[1], withanestimatedprevalenceof 0.3–4.4/100.000[2].It ismoreprevalentinfemales(9:1)[1].In thepast10years,differentdiagnosticcriteriaforNMOhavebeen proposed,includingthoseofWingerchuk[1,3]andUnitedStates NationalMultipleSclerosisSociety–NMSS[4].

ThemainclinicalfeaturesofNMOareopticneuritis(ON)and acutetransversemyelitis(TM).LongitudinallyextensiveTM–LETM andTMwithcervicalextensiontothebrainstemareconsidered typicalofNMO.

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BrainMRIﬁndingsattheonsetofNMOaretypicallynormalor shownon-speciﬁcwhite-matterlesionsthatdonot satisfy neu-roimagingcriteriaforMS[5],eventhoughtheymightraisedoubts aboutdifferentialdiagnosis[6].

Laboratory studies in NMO typically comprise a prominent cerebrospinalfluid(CSF)pleocytosis (>50leucocytes/mL) witha highproportion ofneutrophils, althoughthis is onlypresent in aminority ofpatients. Thepresenceof oligoclonalbands(OCB) ofimmunoglobulin G (IgG)restricted totheCSF is detected in only15–30%ofthepatients[1].ThedetectionofAQP4-IgGis con-sideredaserumbiomarker[7,8]contributingtothediagnosisof NMOandtobroadenitsclinicalspectrum.However,theAQP4-IgG seropositiveratedependsontheassaytypeused[8–11].The cell-basedassay,currentlythegoldstandard,has100%specificityand between68%(commercialCBA)and73%(OxfordCBA)sensitivityin contrastwiththecommercialELISAassaythathas97.7%specificity and70%sensitivity[11].

AcommondenominatorofautoimmunityinNMOissuggested byitsassociationwithotherautoimmuneconditions(10–40%of patients)suchasthyroiditis,myastheniagravis,systemiclupus ery-thematosus(SLE)andSjögren’ssyndromeormoreoften(50%)by thepresenceofcirculatingautoantibodiesintheabsenceofclinical symptomsorautoimmunedisease[1,12,13].

RecoveryinNMOisoftenincompleteandmostpatientsfollowa relapsing–remittingcoursewithprogressiveincreaseofdisability. Predictivefactorsforpooroutcomeincludethepresenceofother autoimmunediseases,highfrequencyofrelapsesduringtheﬁrst twoyearsandpoormotorrecoveryfollowingtheindexevent[1].

TherehavebeenfewepidemiologicstudiesonNMOandnonein thePortuguesepopulation.Thisworkaimstocharacterizeagroup ofPortuguesepatientswithdeﬁniteandNMOspectrumdisorders (NMOSD),accordingtotheWingerchuk2006criteria.Additionally, weintendtodetermineiftherearedemographic,clinical, analyt-icalandimaging differencesbetweenpatientswithdeﬁniteand NMOSD.Finally,weaimtoexplorethecharacteristicsofpatients withconcomitantautoimmunedisease.

2. Materialandmethods

WeperformedanobservationalandretrospectivestudyofNMO patientsin5HospitalCentersinPortugal.Fouraretertiaryhospitals andoneisadistricthospital,followingapproximatelytwo-thirds oftheapproximately5000patientswithdemyelinatingdiseases inthecountry[14].DatawascollectedfromMarchtoJune2012. WeinvestigatedpatientswithdeﬁniteNMOorNMOSD, accord-ingtotheWingerchuk2006criteria[1,3].DeﬁniteNMOcriteria: opticneuritisand acutemyelitisand atleasttwo ofthree sup-portivecriteria:1.ContiguousspinalcordMRIlesionextending over 3 vertebral segments; 2. Brain MRI not meeting diagnos-ticcriteriaformultiplesclerosis;3.NMO-IgGseropositivestatus. NMOSD–Limitedformsofneuromyelitisoptica:Idiopathic sin-gleor recurrenteventsof longitudinallyextensivemyelitis (≥3 vertebralsegmentspinal cordlesionseenonMRI);recurrentor simultaneous bilateral optic neuritis; optic neuritis or longitu-dinallyextensivemyelitisassociatedwithsystemicautoimmune disease;optic neuritisor myelitis associated withbrainlesions typical of neuromyelitis optica (hypothalamic, corpus callosal, periventricular,orbrainstem).

Themajoritywerehospitalizedpatientsthatwereposteriorly followed-upingeneralneurologyordemyelinatingdiseases out-patientclinic.Weincludedallpatientsobservedsince1990.

Theinclusioncriteriawereasfollows:patientswhofulﬁll crite-ria for deﬁnite and NMOSD (Wingerchuk 2006); patientswith brain/spinal MRI (report and/or image); determination of the AQP4-IgGmadeinthelaboratoriesoftheMayoClinicorOxford,

according to the visual observation-fluorescence cell-based assay technique. Theexclusion criteria werefindings consistent with otherpathologiesincludinginflammatorydemyelinating(namely MS),infectious,vascular,metabolicdiseasesorCNSmalformation andpatientswithoutMRIimageorreport.

Data was obtained from hospital databases of the different participating centers, through consultation of medical records. Epidemiologicdatawasassessedforeachpatientincluding demo-graphicinformation(age,gender,ethnicity,placeofbirth);clinical (age of onset,initialclinical disabilityaccording toinitialEDSS score,patternofevolution–relapsing–remitting,monophasicor progressive–accordingtothenumberofattacksduringthe follow-upperiod,optico-spinalinterval,timebetweenﬁrstandsecond attack,annualizedrelapse rate–ifapplicable,progression time to EDSS 3, 6, 8, 10 – based on stable disability measurement afterattackrecoveryandstabilization,concomitantautoimmune diseases); laboratory(CSF during theﬁrst attack, seropositivity for AQP4-IgG,presence of OCB restricted to theCSF and other immunologicalstudies);imaging studies(brainand spinalMRI) and treatment (typeof treatment in relapses and global treat-mentreceived).MRIatdiseaseonsetandadditional/subsequent oneswerereviewedandevaluatedbyaneuroradiologist(number, topography,morphologyandpatternsofcontrastenhancementof lesions).LETMlesionswereconsideredwhenextendingfor3or morevertebralsegments.

Allpatientswereaskedtoprovidewritteninformedconsent afterthestudyapprovalbyethicscommittees,boardsofthe par-ticipatingcentersand NationalCommissionfor Data Protection (NCDP).Inthecaseofdeceasedpatients,datawascollectedwith NCDPpermission.

AlldataanalysiswasperformedusingSPSSversion17.0. Demo-graphic and clinical data is presented by descriptive statistics. Means,medians,andrangeswerecalculated,95%conﬁdence inter-vals (CI) were estimated and p values <0.05 were considered signiﬁcant.

3. Results

3.1. Demographicandclinicalfeatures(Table1)

We found67 patients fulﬁlling the inclusion criteria (NMO andNMOSD).Fromthese,55(65.7%)werefemaleandthe major-ity(95.0%) wereCaucasian.Themean ageatdiseaseonset was 36.0±15.0years,withameanfollow-uptimeof7.4±6.0years. Spinal symptoms were the initial presentation in 31 patients (46.3%) and ON in 30 patients (44.8%). Only 3 patients had concomitantmyelitisand ON(4.5%)atpresentation.Inthe def-inite NMO group the majority of patients presented with ON (12 patients, 57.1%)and themedian optico-spinal interval was 38months.

ThemeantimetoanEDSSof3,6and8wasrespectively4.5±4.9 months(in25 patients),9.9±22.5months (in17patients) and 9.3±8.4months(in7patients).

Twenty-oneoutof67(31.3%)patientswereclassifiedas defi-niteNMOand46(68.7%)asNMOSD.LETMandanegativeinitial brainMRI(Barkhofcriteria)[15]werethemainsupportivecriteria (10patients) for definiteNMO.Six patientshad thethree sup-portivecriteriafordefiniteNMO.IntheNMOSDgroup,recurrent ON(13)andisolatedLETM(12)werethemostfrequent presenta-tions.

Fivepatientsdied(threefrompneumonia,onefrompancreatic cancerandonewasNMOrelated–cervicallesioncausing respira-toryinsufﬁciency).

Autoimmunediseases wereobserved in 15 patients(22.4%), themostfrequentwasSLE(5patients),followedbyautoimmune

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Table1

DemographicandclinicalcharacteristicsoftheNMOcohort.

Characteristics Na _%_(n)

Female 67 65.7(55)

Caucasian 67 95(64)

Na _Mean_(SD) _Median_(min;_max)

Ageatdiseaseonset 67 36.0(15.0) 32(3;76)

Ageatdiagnosis 65 40.7(15.0) 39(13;79)

Follow-up(years) 67 7.4(6.0) 4(1;24)

Optic-spinalinterval(months) 23 45.1(48.7) 19(0;168)

S1–S2Interval(months) 46 44.0(63.2) 19(2;276)

Annualizedrelapserate(at24months) 59 0.9(0.7) 0.5(0.5;3.5)

TimetoEDSS3(months) 25 4.5(4.9) 2(0;18)

Na _%_(n)

Deaths 67 7.5(5)

Relapsing–remittingcourse 67 72(48)

Monophasiccourse 67 28(19)

a_Number_of_patients_with_available_and_or_applicable_information.

Table2

BiologicalcharacteristicsoftheNMOcohort.

Na _%_(n) CSF Cellcount/mm3 ₅₃ ≤5 64(34) ]5;50[ 26(14) ≥50 9(5) Oligoclonalbands 46 17(8) Proteins≥45mg/dL 50 42(21) IgGindex>0.73 34 26(9) Blood AQP4-IgG+ 67 36(24) Detectableantibodies 50 34.3(23) Antinuclearantibodies 20(10) Anticardiolipinantibodies 18(9) Anti-SSAantibodies 16(8) Anti-␤2glycoprotein 16(8) Otherantibodies 50(25)

thyroiditis,primaryantiphospholipidsyndrome(3patientseach), myastheniagravis,Sjogren’ssyndrome,primarybiliarycirrhosis(2 patientseach)andscleroderma(1patient).Threepatientshad2 autoimmunepathologiessimultaneously.

3.2. Laboratorialfeatures(Table2)

The CSF analysis revealed that 34 patients had less than 5leucocytes/mm3_._Analysing_the_CSF_pleocytosis_according_to_the

formofpresentationwefoundthatfromthe30patientsthat pre-sentedwithON19(63%)hadnormalCSFcellcount(<5cells/mm3_),

2(6.6%)hadCSFpleocytosisbetween5and50cells/mm3_,₁_(3%)_had

CSFpleocytosis>50cells/mm3_and_in₈_patients_these_data_was_not

available.Fromthe31patientsthatpresentedwithLETM13(42%) hadnormalCSFcellcount,11(35%)hadCSFpleocytosisbetween 5 and 50cells/mm3_,₃ _patients_(9.7%) _had _>50_cells/mm3 _and ₄

patientshadnoavailabledata.Allthepatientsthatpresentedwith ONandhadCSFpleocytosishadmononuclearpredominance.From thepatientsthatpresentedwithLETMandhadCSFpleocytosis10 hadmononuclearpredominance.

Eightoutof46patientshadpositiveOCB.

AQP4-IgGwasfoundin24patients(35.8%).Twenty-threeoutof 50patientshadpositiveautoantibodies.

Table3

ImagingcharacteristicsoftheNMOcohort.

MRIfeatures Na _%_(n)

BrainMRIpattern 66

Normal 42(28)

Non-speciﬁc 39(26)

MS-like 12(8)

NMO-like 6(4)

BrainMRIlesionstopography 66

Supratentorial 47(31)

Infratentorial 21(14)

Periventricular 43(28)

Juxtacortical 12(8)

BrainMRInumberlesions 66

0 42.4(28)

1–24 31.8(21)

>25 25.8(17)

SpinalMRInumberoflesions 59

0 23.7(14) 1 57.6(34) 2 13.6(8) >3 5.1(3) LETM 52.5(31) CervicalLETM 20.3(12) DorsalLETM 32.2(19) Cervico-dorsalLETM 20.3(12)

a_Number_of_patients_with_available_and_or_applicable_information;₁_patient_with

LETMhadonlyspinalMRIperformed;8patientswithoutspinalinvolvementhad onlybrainMRIperformed.

3.3. MRIfeatures(Table3)

Inmostpatients,brainMRIshowednoabnormalities(42.4%) ornonspeciﬁcﬁndings(39.4%).Only4(6.1%)casesshowed NMO-likelesions.LETMwasdetectedin31patients,withdorsalsegment beingthemostofteninvolved(19patients).

3.4. Treatment

Methylprednisolone(MP)wasthemostfrequentlyused treat-mentintheacutephase(83.3%)followedbythecombinationof MPwithintravenousimmunoglobulinorplasmaexchange(7.4% each). For preventivetreatment, prednisolone and azathioprine werethemainlyusedtreatments(25.6%and18.6%,respectively); in7patients(16.3%)theyweregivensimultaneously.

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3.5. Groupcomparisons

3.5.1. DeﬁniteNMOvsNMOSD(Table4)

Comparingthe groupof definite NMOwith theNMOSD we founda relapsing-remitting course in 90.5% and 63.0% respec-tivelyandamonophasicevolutionin9.5%and37.0%,respectively (p=0.02).Ifweselectedonlypatientswithmorethan5yearsof follow-upwereachatotalof33patients,15definiteNMOand18 NMOSD.NoneofthedefiniteNMOpatientswasmonophasic.From the18NMOSD,4(22.2%)weremonophasicand14hadmorethan oneattack.Althoughthepercentageofmonophasicpatientsinthe NMOSDgroupislowerthanwhenallthepatientswereconsidered (37.0%)itisstillsignificantlyhigherthaninthedefiniteNMOgroup. Medianannualizedrelapseratewas1.0inthedefiniteNMO groupand0.5intheNMOSD(p=0.01).Concerningthedeathrate, allpatientsthathaddied(n=5;7.5%)belongedtotheNMOdefinite group(p=0.002).

OCBwerepresentin38.5%ofthedeﬁniteNMOpatientsandin 9.1%oftheNMOSDpatients(p=0.03).

ThespinalMRIshowedlesionsinallpatientswithdeﬁniteNMO andin63.2%oftheNMOSDgroup(p=0.001).

No differences between the two groups were found in the remainingdemographic,clinical,laboratorialandtherapeuticdata. Regardingthepresenceofautoimmunediseasestherewereno statisticallysigniﬁcantdifferences.

3.6. PositiveAQP4-IgGvsnegativeAQP4-IgG

Twenty-threeoutof 24 (95.8%) patientswithAQP4-IgG and 19 out of 41 (46.3%) of those without antibody were female (p=0.0012). FromtheAQP4-IgGpositive group,elevenpatients belongtothedeﬁniteNMOgroup(52.4%) and13(28.3%)tothe NMOSD(p=0.10).

PositiveAQP4-IgGpatientshadameanageatdiagnosisof37.2 years;10patients(41.6%)presentedwithmyelitisand9(37.5%) withON;18patients(75%)followedarelapsing–remittingcourse and6(25%)weremonophasic;2patientsinthisgroupdied(8.3%). TheseropositiveAQP4-IgGpatientshadsigniﬁcantlymore con-comitantautoimmunediseasesthandidpatientswithseronegative AQP4-IgG(41.7%vs9.8%,p<0.004).

Twenty-ﬁvepercentoftheAQP4-IgGseropositivepatientswere monophasicand26.8%fromtheseronegativeweremonophasic andthisdifferencewasnotstatisticallysigniﬁcant(p>0.05).

Nofurthersigniﬁcantdifferenceswerefoundbetweenthose twogroups.

3.7. Patientswithautoimmunediseases

Concomitantautoimmunediseasewaspresentin15outof67 patients,5 belongingtothe deﬁniteNMOgroup and10 tothe NMOSD.

Fourteenoutof15werefemale,Caucasian,withamedianageat diseaseonsetof32years(19;71),andamedianfollow-upof4years (1;13).Eleven had arelapsing–remitting course.Sevenpatients (46.7%)hadmyelitisastheinitialtopography,5ONand1both.One ofthese15patientsdied.Aspreviouslyreported,10outofthe15 patientswithautoimmunediseases(66.7%)hadpositiveAQP4-IgG antibody.

4. Discussion

Thisstudy,theﬁrstdoneinthePortuguesepopulationregarding NMO,comprisesasigniﬁcantnumberofpatientsfromthemost representativenationalcenters.

Althoughthere aremanyepidemiologic studiesfromseveral countries,themethodologiesnamelythepopulationsampling,the

inclusioncriteria,thedeﬁnitionsofNMOandNMOSDandthe vari-ables studiedvary greatly among them. For thesereasons it is difﬁculttomakedirectcomparisons.

Thedemographic characteristicsofourcohort aresimilarto those reported in other studies [16,17] namely regarding the female:maleratio(4.6:1),themedianageatonset(36.0years)and thediseasecourse(relapsing–remittingin71.6%).Interestingly,in ourstudynopatienthad aprogressivecourse.Althoughhigher female:maleratios,higherageat diseaseonsetand higher per-centageofrelapsingremittingcoursehavebeenreported[18–20] namely in cohorts with populations sizes similar to Portugal [18,20].TheCSFresultsaredifferentfromwhatwecanfindinthe literature.Infact,inthemajorityofthepatientstherewasnoCSF pleocytosisand8outof46(17.4%)hadOCB(around12%inother studies)[19–21].Wefoundthata higherpercentageofpatients presentingwithLETMhadCSFpleocytosiswhencomparedtothe patientsthatpresentedwithON.Likeinpreviousreports,brainMRI atdiseaseonsetwasmostlynormalorshowednon-specificbrain lesions[18–20].Withrespecttospinalcordlesions,theresultswere alsoconsistentwiththoseofpriorstudiesshowingLETMin52.5% ofpatients.ThepercentageofAQP4-IgGpositivepatientsislower inourstudy(35.8%;CBAtechnique)thanintheFrench[16](54.0%; indirectimmunofluorescenceassay),theDanish[17](62.0%;CBA technique),theHongKong [18](88.9%,CBA)and theAmerican multicentreone[19](68.3%;indirectimmunofluorescenceassay). However,the total number of patients (namely of theNMOSD group)andthedefinitionofNMOSD(somestudiesincludedinthis grouponlypatientsthatwereAQP4-IgGseropositive)[18–20]must betakenintoaccount.Infact,ifwecompareonlywiththe defi-niteNMOgroupstheresultsareinconsonancebetweenourstudy (52.4%)andtheDanish[17]one(55.6%).AQP4-IgGpositivitywas notassociatedwithaworseoutcome,consideringthenumberof deaths,annualizedrelapserateortimetoreachEDSSof3,6or8.

Inspiteofhavingfoundahigherpercentageofpatientswith concomitantautoimmunedisorders(15patients,22.4%)thanitwas reportedintheFrench[16](10.4%)andHongKong [18](10.6%) studies,mostoftheencountereddisordersweresimilar(mainly SLEandSjogren’ssyndrome)exceptforthetwocasesofmyasthenia gravisdescribedinourcohort[13] andalsointheAustrianone [20].Since66.7%ofpatientswithautoimmunediseaseshadpositive AQP4-IgGantibody,wehypothesizethatitspresencemaybefaced asan“autoimmunemarker”.

Withrespecttotheclinicaldataofthedefinite NMOgroup, weobservedthatthepredominantinitialtopographyintheoptic nerves(57.1%)isinagreementwiththeItalian[21]andthe Ameri-canmulticentregroup[19],butincontrastwithothers[16,17,22]. Aswell,theopticospinalinterval(24months)waslongerthanin theMexican[22](3.5months)andFrench[16](15months) stud-ies.However,theannualizedrelapserate(1.0)inourcohortwas similartothepreviousstudies[16,17,21].Themortalityrateinthis group(23.8%)wassimilarintheAmericanMayoCliniccohort[23] (22.5%),buthigherthanintheItalian[21](13.0%),Mexican[22] (2.9%),French[16](3.2%)andDanish[17](8.3%)cohorts.Itisalso worthofnotethatinthepresentstudythepresenceofAQP4-IgG antibodywasessentialfordefiniteNMOdiagnosisin5cases(23.8%) whereasintheFrenchstudy[16]itwasneededinonly10.0%(12 cases)ofthecasesandintheDanishstudy[17]in36.0%(15cases). Concerning the comparison between definite NMO with NMOSD, thefirstone seemsto have a worseprognosis witha higherannualizedrelapserate(1.0vs0.5)andmortalityrate(all ofthe5deathsoccurringintheformergroup).Also,themajority ofpatientsinthedefiniteNMOgrouphadarelapsing–remitting course,whereasthemonophasiccoursewassignificantlyhigher intheNMOSDpatients.Positiveoligloclonalbandsweremore fre-quentintheNMOdefinitegroup.Yet,thismayduetoarecord bias,sincethisinformationwasavailableonlyinasmallnumberof

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Table4

ComparisonbetweendeﬁniteNMOandNMOSDgroups.

Na _Deﬁnite_NMO_(N₌₂₁₎ _Na _NMOSD_(N₌₄₆₎ _p

Female,n(%) 16 76% 28 61% 0.22

Caucasian,n(%) 18 86% 45 98% 0.09

Ageatonset(years),median(min;max) 21 32(3;60) 46 33.5(13;76) 0.42

Ageatdiagnosis(years),median(min;max) 19 40(17;65) 46 38(13;76) 0.85

Follow-up(years),median(min;max) 21 9(1;21) 46 4(1;24) 0.18

S1–S2interval(months),median(min;max) 20 17.5(20;168) 26 19(2;276) 0.75

Annualizedrelapserate,median(min;max) 20 1.0(0.5;3.5) 39 0.5(0.5;3.0) 0.01

Deaths(n) 21 5 46 0 0.002 Relapsing–remittingcourse,n(%) 21 19(91) 46 29(63) 0.02 Monophasiccourse,n(%) 21 2(9) 46 17(37) CSFpleocytosis 15 38 ≤5 10 67 24 63 0.72 ]5;50[ 4 27 10 26 ≥50 1 7 4 11 Oligoclonalbands,n(%) 13 5(39) 33 3(9) 0.03 Proteins≥45,n(%) 16 8(50) 34 13(38) 0.43 BrainMRI,n(%) 21 45 Normal 6(29) 20(44) 0.19 Non-speciﬁc 10(48) 18(40) MS-like 2(9) 6(13) NMO-like 3(14) 1(2) Lesionstopography,n(%) 21 45 Supratentorial 12(57) 20(44) 0.34 Infratentorial 6(29) 9(20) 0.44 Periventricular 8(40) 17(38) 0.87 Juxtacortical 2(10) 6(13) 1.00 SpinalMRI,n(%) 21 38 Withoutlesions 0 14(37) 0.001 Withlesions 21(100) 24(63)

patients.TherewasnosignificantdifferencebetweendefiniteNMO andNMOSD,regardingthepresenceofAQP4-IgGorother circulat-ingautoantibodies.ComparedwiththeDanishstudy[17],where thespectrumformswerealsoevaluated,wefoundahigher propor-tionofthosedisorders(68.7%vs14.0%).Webelievethatthisfact maybeduetoaselectionbias,overestimatingthosecaseswhere CNSinflammatorydiseasewassuspectedbutdidnotmatchMS criteria,suchasrecurrentopticneuritisoridiopathicLETM.

Taking into account the comparison between AQP4-IgG seropositiveandseronegativepatients,wefoundahigher propor-tionoffemales amongthepositiveones,similarlytowhathave beenpreviouslyreported[24].AnalysingthegroupofAQP4-IgG seropositivepatients,wefoundsimilarclinicalcharacteristicsto whathavebeenreportedintheUKandJapancohorts[25], includ-ingmeanageatonset,percentageoffemalepatients,diseasecourse andformofpresentation.Themortalityratewas8.3%inourcohort, higherthantheJapanesebutlowerthantheUKcohorts[25].Infact, recentstudiescomparingseropositiveandseronegativepatients broughtnewconcepts, includingswitching theNMOdeﬁnition fromaclinicalphenotypetoabiologicalone[24].

Beingretrospective,thisstudyhasinherentlimitations,namely therecordconsulting bias.Thedetermination ofAQP4-IgGwas madeaccordingtothesametechnique.However,sinceitwas per-formedatdifferenttimesofthediseaseevolution,insomecases thetitersmighthavebeeninﬂuencedbytheongoingtreatment. Likewise,MRIavailabledatawasalsoperformedatdifferenttimes andmighthavebeeninﬂuencedbytheongoingtreatmentoreven thediseaseprogression.

Inconclusion,thisstudycorroboratestheclinicalheterogeneity ofNMOinitsbroadsense.Finally,theassociationfoundbetween AQP4-IgGpositivityandconcomitantautoimmunedisease,could betakenintoaccountforfutureresearchstudies.

Conﬂictofinterest

Theauthorsdeclarethatthereisnoconﬂictofinterest.

Acknowledgments

TheauthorsaregratefultoAnaMartinsdaSilvaandManuel Cor-reia(CentroHospitalardoPorto–HospitaldeSantoAntónio,Porto, Portugal),LíviaSousa(CentroHospitalareUniversitáriode Coim-bra)andRuiGuerreiro(CentroHospitalardeSetúbal,Portugal)for theircontributiontothiswork.ThanksarealsoduetotheMayo Clinic Laboratories(USA)and totheOxford Laboratory of Neu-roimmunology(UK) wheretheAQP4-IgGtestswereperformed. Finally,wethankForpoint–InstitutodeFormaçãoeInovaçãona SaúdefromKeypointGroupforstatisticalassistanceandBiogen Idecforthefinancialsupport.

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