Rev. Bras. Reumatol. vol.55 número4

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r e v b r a s r e u m a t o l . 2015;55(4):330–333

w w w . r e u m a t o l o g i a . c o m . b r

REVISTA

BRASILEIRA

DE

REUMATOLOGIA

Original

article

Ultrasonography

as

a

tool

in

diagnosis

of

carpal

tunnel

syndrome

夽

Adham

do

Amaral

e

Castro

a,∗

,

Thelma

Larocca

Skare

b

,

Alexandre

Kaue

Sakuma

b

,

Wagner

Haese

Barros

a

a_Department_of_Radiology,_Hospital_{Universitário}_Evangélico_de_Curitiba,_Curitiba,_PR,_Brazil

b_Department_of_{Rheumatology,}_Hospital_{Universitário}_Evangélico_de_Curitiba,_Curitiba,_PR,_Brazil

a

r

t

i

c

l

e

i

n

f

o

Articlehistory:

Received30September2014

Accepted1December2014

Availableonline9March2015

Keywords:

Carpaltunnelsyndrome

Ultrasonography

Handpain

Handparesthesia

a

b

s

t

r

a

c

t

Objective:Weaimedtodeterminethevalueofultrasonography(US)inthediagnosisofcarpal

tunnelsyndrome(CTS).

Methods:Twohundredpatients(400hands)weresubmittedtowristUStomeasuremedian

nervearea(MNA),questioningonparesthesiaandpaininthemediannerveterritory,Tinel

andPhalenmaneuvers.AnMNA>9mm2_was_considered_diagnostic_of_CTS.

Results:MeasurementofMNA byUSwas>9mm2 _in_27%_of_the_hands._A_good

associa-tionwithpain(p<0.0001),paresthesia(p<0.0001),Tineltest(p<0.0001)andPhalentest

(p<0.0001)wasfound.AccordingtotheclinicalcriteriaforclassificationofCTSfrom

Amer-icanAcademyofNeurologytheMNAbyUShad64.8%ofsensibilityand77.0%ofspecificity

inthissample.

Conclusion:MeasurementofMNAbyUSperformswellandcanbeusedasfirstoptionfor

theinvestigationofpatientswithCTS.

Ultrassonografia

no

diagnóstico

da

síndrome

do

túnel

do

carpo

Palavras-chave:

Síndromedotúneldocarpo

Ultrassonografia

Dornamão

Parestesianamão

r

e

s

u

m

o

Objetivo:Determinaraimportânciadaultrassonografia(US)nodiagnósticodasíndromedo

túneldocarpo(STC).

Métodos:Duzentospacientes(400mãos)foramsubmetidosaumaUSdopunhoparamedira

áreadonervomediano(ANM).Foramperguntadosquantoàpresenc¸adeparestesiaedorno

territóriodonervomedianoesubmetidosaostestesdeTinelePhalen.UmaANM>9mm2

foiconsideradadiagnósticadeSTC.

夽

ThisstudywasoriginatedintheRheumatologyandRadiologydepartmentsofHospitalUniversitárioEvangélicodeCuritiba,Curitiba,

PR,Brazil.

∗ _{Corresponding}_author_.

E-mail:adham.castro@gmail.com(A.doAmaraleCastro).

http://dx.doi.org/10.1016/j.rbre.2014.12.002

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rev bras reumatol.2015;55(4):330–333

331

Resultados: OvalordaANMmedidapelaUSfoi>9mm2_em_27%_das_mãos._Foram

encon-tradosumaboaassociac¸ão comador (p<0,0001),parestesia(p<0,0001), testedeTinel

(p<0,0001) e teste de Phalen (p<0,0001). De acordo com os critérios clínicos para a

classificac¸ãodaSTCdaAmericanAcademyofNeurology,aANMmedidapelaUSteve64,8%

desensibilidadee77%deespecificidadenessaamostra.

Conclusão: Amensurac¸ãodaANMpelaUSéadequadaepodeserusadacomoprimeira

opc¸ãoparaainvestigac¸ãodepacientescomSTC.

Introduction

Carpaltunnelsyndrome(CTS)isthemostfrequent

entrap-mentneuropathy,itisduetothecompressionofthemedian

nerveatthe wrist.1 _The_history _and _physical_examination,

includingprovocativesignssuchasTinelandPhalen

maneu-vers,havebeenconsideredhighlysuggestiveofthediagnosis.2

Eletroneuromyography(EMG)studiesareusuallyconsidered

toproveit,3 _but_this _is_a_test_that _is_not_readily_accessible

and notwell toleratedbyall thepatients that precludeits

repetitionforpatient’sfollowup.

Recentlywristultrasonography(US)withmeasurementof

themediannervearea(MNA)hasbeenconsideredan

alter-nativetoEMG.4_An_MNAof₉_mm2_in_the_distal_carpal_tunnel,

atlevelsofpisiformboneisconsidereddiagnosticofCTS.5,6

Accordingtosomeresearchersthisisanexamwithhigh

sen-sitivityandspecificityinCTSdiagnosis4–6_;_others_are_not_so

enthusiastic.Mondellietal.1_found_that_almost_1/4_of_patients

withdiagnosisofmildcasesofCTSdiagnosedclinicallycould

nothavebeendetectedbyUS.Carvalhoet al.,5_in_a_review,

foundthatMNAUSmeasurementhas82to86%ofsensibility

and48to87%ofspecificity.

OneoftheproblemsofstudyingCTSisthelackof

con-sensus to establish the definitive diagnosis.7 _Neurologists

traditionally establish it based more on the outcome of

nerve conduction studies than on the patients’ signs and

symptoms.7_In_contrast,_hand_surgeons_appear_to_give

consid-erablymoreimportancetothepatients’signsandsymptoms.7

Thelackof universallyaccepted classificationcriteria may

beresponsibleforthediversityofresultsseeninthe

litera-ture.

TolookfurtherintotheusefulnessofUStodiagnoseCTS,

wemeasuredtheMNA of200individuals toanalyze ifthis

measurecouldpredictwhichpatienthadornotclinical

symp-tomsofCTS.

Patients

and

methods

Twohundredhospitalworkers(35menand165women)were

invitedtoparticipateinthestudy.Afterapprovaloflocal

Com-mitteeofEthicsinResearchandpatient’ssignatureofconsent

term,all participantsfilled the Katz diagram for pain and

numbnessinthemediannervearea.8_Physical_examination

includedPhalen1_and_Tinel_test.1_Tinel’s_test1_was_performed

by tapping the median nerve at the wrist, and this was

repeatedfourtosixtimes.Thepresenceorabsenceof

radi-atingpainorparaesthesiainthemediannervedistribution

was recorded.Phalen’s test1 _was _executed _by _asking _each

subjecttoholdhandwiththewristincompletepalmar

flex-ionwithelbowextendedandforearmpronated.ThePhalen’s

testwasconsideredpositiveifsymptomswerereproducedin

1min.

TheMNAwasmeasuredbyUSequipment(ToshibaXARIO

XG,Tokyo,Japan),withamultifrequentiallineartransductor

of12MHzatvolardistalsurfaceofthewrist(atthelevelof

pisiformand tuberosity ofscaphoid)byablind technician.

For the examination, patientsshould beseatingin achair

with arms extendedand hands with finger semiextended.

AMNAwithmorethan9mm2_was_considered_diagnostic_of

CTS.5

Data werecollected infrequencyandcontingencytable.

ThesampledistributionwastestedbyKolmogorov–Smirnov

test. Central tendency was expressed in median and

interquartilerange(IQR)asthesampledistributionwas

non-parametric.Associationstudiesweredonebychi-squared(2)

test. Adoptedsignificancewasof5%.Calculationwasdone

withspecificsoftware(GraphPadPrismversion5.0,SanDiego,

USA).

Results

Thestudiedsamplewasformedby35menand165women

withmedianageof40.0years(rangingfrom18.0to74.0years;

IQR of27.0–49.0years). In this sample 39/200(19.5%)were

afrodescendant; 156/200(78%) caucasians,and 5/200 (2.5%)

orientals.Accordingtolaboractivities,142/200(71%)had

man-ualworkand58/200(29%)hadwhitecollarwork.

In the 400 examined hands, paresthesia was found in

108/400 (27.5%), pain in 106/400 (26.5%), positive Tinel test

in99/400(24.7%)andpositivePhalen’stestin97/400(24.2%).

Bothsymptoms(painandparesthesia)werefound

simulta-neouslyin74/400(18.5%)andbothsigns(TinelandPhalen’s)

in60/400(15%).

MNAatUShadamedianvalueof8mm2_(ranging_from₄

to21mm2_;_IQR_of_6.0–10.0_mm2_)._In_108/400_(27%)_hands_the

valueofMNAwas>9mm2_{characterizing}_presence_of_CTS_by

theUS.

Comparingthepresenceofsignsandsymptomsinthose

withMNA>9mm2_with_those_with_≤₉_mm2_by_US,_it_was_found

theresultsshowninTable1.

If the CTS diagnosis were made according to

Ameri-can Academy of Neurology criteria9 _that _considers

clas-sic/probablecasesthosewithparesthesiaorpaininatleast

2ofthefirst3fingers,theMNAbyUShad64.8%ofsensibility

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332

Table1–Presenceofsymptomsandsignsofcarpaltunnelsyndromeaccordingtothevalueofmediannervearea measuredbyultrasound.

MNAwith>9mm2_n₌₁₀₈ _MNA_with_≤₉_mm2_n₌₂₉₂ _p

Paresthesia 61/108(56.4%) 47/292(16.0%) <0.0001

Pain 50/108(46.2%) 56/292(19.1%) <0.0001

Tinel’ssign 56/108(51.8%) 43/292(14.7%) <0.0001

Phalen’ssign 55/108(50.9%) 42/292(14.3%) <0.0001

MNA,mediannervearea.

Discussion

CTSisaverycommonentity.Itaffectsfrom2.7to5.8%of gen-eralpopulation.1–8 _More_than_80%_of_the_patients_are_above

40 years of age and women are affected more commonly

thanmen.5_Bilateral_involvement_appears_in_nearly_half_of_the

casesbut thedominanthandisthefirstandmostseverely

involved.5_This_syndrome_is_considered_mainly_as_a_sensory

disorderbecausethesensoryfibersofthemediannerveare

moreaffectedthanthemotors.10_So,_CTS_patients_complain

ofsymptomssuchasdullpainandtinglingsensationinthe

thumb,index,andmiddlefingerorparaesthesiaandstiffness

ofhandprimarilyatnight.10_Atrophy_in_thenar_muscle,

weak-nessorclumsinessofhand,dryskin,swellingorcolorchange

inthehandalsocanbeseeninsomecases,butusuallythey

arelatefindings11_and_this_stage_should_be_avoided_by_the_early

andcorrecttreatment.

Paresthesiasinthehandsarenonspecificfindingsandmay

havemultiplecauses suchas other neuropathies(diabetic,

alcoholic etc.), other nerve entrapment disorders (cervical

radiculopathy,thoracic outlet syndrome, etc.) and even by

musculoskeletaldisorderssuchasfibromyalgia.12–15_The

clin-icaljudgment that reliessolely on clinical findings can be

misleading.

Tohaveanexactdiagnosisisofvitalimportanceformany

reasons.Oneofthemisthattherateofsuccessinthe

treat-mentisindirectdependenceofdiagnosticcertainty.CTScan

betreatedbothconservativelyandwithmediannerverelease

surgery.16_Surgery_is_often_indicated_in_the_failure_of

conser-vativetreatment.Ameta-analysisbyShietal.16_showed_that

surgerywassuperiortonon-surgicalinterventionregarding

improvementofeletrophysiologicalstudies.

Otherimportantreasonfordiagnosticaccuracyisdirectly

associatedtowork compensation.There isreasonable

evi-dencethatregularandprolongeduseofhand-heldvibratory

toolsincreases the riskofCTS by2 fold.17 _There _is_also _a

substantialbodyofevidencethattaskswithcontinuedand

highlyrepetitiousflexionorextensionofthewristincreases

theriskofCTS,especiallywhenalliedwithaforcefulgrip.17

Sincethisrelationshiphasimportantongoingimplicationsfor

individualworkers,workpracticeandworkers’compensation

systems,diagnosisbasedonlyinpatient’scomplainsmaynot

bewell acceptable. Astudy bySzabo,17 _done _in_California,

estimated that nonmedical costs for CTS, including early

retirementanddisabilityareaboutUS$10,000perhand.The

sameauthor,takingintoaccountmedicalcosts,andindirect

costscoveredbypatientsandfamiliesassessedthat,thetotal

costofaCTSpatientsvariesfromUS$20,000toUS$100,000per

person.

Inthiscontexttheuse ofMNAbyUSemergesasa

use-fultoolevaluation.Ithasagoodcost–benefitratio,itiswell

toleratedbythepatients,itiseasytoperformanditcanalso

diagnoseassociateddisordersandneuralanatomicvariations.

Thislastaspectmaybeofimportanceforsurgicalplanning.

ThepresentstudyshowedthatUSissignificantly

associ-atedwithclinicalsignsandsymptomsofCTS.Italsoshowed

a reasonable sensitivity and specificity so it that can be

performedasafirstlinetest,reducingtheneedof

electroneu-rographicstudies.

ThemeasurementofMNAbyUSisusefulasafirstline

diagnostictoolinpatientswithsuspectedCTS.

Conflicts

of

interests

Theauthorsdeclarenoconflictsofinterest.

Acknowledgments

TotheentirestaffoftheRadiologyandRheumatology

depart-mentsbyenablingthecompletionoftheresearch.

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