Braz. j. . vol.81 número1

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Brazilian

Journal

of

OTORHINOLARYNGOLOGY

www.bjorl.org

ORIGINAL

ARTICLE

Influence

of

sensory

information

on

static

balance

in

older

patients

with

vestibular

disorder

夽

Camila

Macedo

a,∗

,

Juliana

Maria

Gazzola

a

,

Natalia

Aquaroni

Ricci

a

,

Flávia

Doná

b

_,

_Fernando

_Freitas

_Gananc

_¸a

a

a_Department_of_{Otorhinolaryngology}_and_Head_and_Neck_Surgery,_Universidade_Federal_de_São_Paulo_(UNIFESP),

SãoPaulo,SP,Brazil

b_Balance_{Rehabilitation}_and_Social_Inclusion_{Post-Graduation}_Program,_Universidade_Anhanguera_de_São_Paulo,_Brazil

Received14August2012;accepted23August2014 Availableonline21November2014

KEYWORDS

Aged;

Posturalbalance; Rehabilitation; Dizziness;

Vestibulardiseases

Abstract

Introduction:Withaging,thesensorysystemssufferanaccumulationofdegenerative, infec-tiousand/ortraumaticprocessesthatmayhinderthebodybalancemaintenance.

Objective:Toassess the influenceofsensory informationonstatic body balanceofelderly individualswithvestibulardisorders.

Methods:Cross-sectional study ofelderly individualswith vestibular disorders. The Clinical TestofSensoryInteractionandBalanceandposturographyintegratedwithvirtualreality (Bal-anceRehabilitationUnitTM₎_were_used._{Posturography}_parameters_analyzed_included_center_of

pressureandvelocityofbodysway.

Results:123 individuals with mean age of 73.11 were assessed. Worst performance was observed in the Clinical Test of Sensory Interaction and Balance condition of visual dome-unstable surface. Differences between conditions were: firm surface-open eyes/firm surface-closedeyes,unstablesurface-openeyes/unstablesurface-closedeyes(p<0.001),and unstablesurface-closedeyes/unstablesurface-visualdome.Consideringcenterofpressureand velocityofbodysway,significantdifferenceswereobservedbetweenthefollowingconditions: firmsurface-openeyes/firmsurface-closedeyes:firmsurface-saccadicstimulus/firm surface-vertical optokineticstimulus; firmsurface-optokinetic stimuli/firmsurface-visual---vestibular interaction; andfirmsurface-visual---vestibularinteraction/unstablesurface.Worse perform-anceswereobservedinconditionsfirmsurface-closedeyes,firmsurface-verticaloptokinetic stimulus,F-visual---vestibularinteraction,andunstablesurface-closedeyes.Therewasa differ-enceinthecenterofpressurebetweenfirmsurface-closedeyes/firmsurface-saccadicstimulus, with aworse performancein the condition offirm surface-closed eyes, andof velocityof bodysway,betweenfirmsurface-saccadicstimulus/firmsurface-horizontaloptokineticstimulus (p<0.001).

夽 _Please_cite_this_article_as:_Macedo_C,_Gazzola_JM,_Ricci_NA,_Doná_F,_Gananc_¸a_FF._Influence_of_sensory_information_on_static_balance_in olderpatientswithvestibulardisorder.BrazJOtorhinolaryngol.2015;81:50---7.

∗_{Corresponding}_author.

E-mail:[email protected](C.Macedo).

http://dx.doi.org/10.1016/j.bjorl.2014.11.004

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Conclusion: Staticbodybalanceinelderlyindividualswithvestibulardisordersisworsewhen thesensoryconditionsaremorechallenging,i.e.stableandunstablesurfaces,visualstimuli, suchasoptokineticandvisual---vestibularinteraction,andwiththeeyesclosed.

PALAVRAS-CHAVE

Idoso;

Equilíbriopostural; Reabilitac¸ão; Tontura;

Doenc¸asvestibulares

Influênciadasinformac¸õessensoriaisnoequilíbriocorporalestáticodeidosos

vestibulopatas

Resumo

Introduc¸ão: Comoenvelhecimento,osistemasensorialsofreumacúmulodeprocessos degen-erativos, infecciosos e/ou traumáticas que podem dificultar a manutenc¸ão do equilíbrio corporal.

Objetivo: Avaliara influência dasinformac¸ões sensoriais noequilíbrio corporal estáticode idososvestibulopatas.

Método: Estudo transversal, cuja amostra foi constituída por idosos vestibulopatas. Empregaramse oClinical Testof Sensory Interactionand Balance (CTSIB) e a posturografia integrada àrealidadevirtual(BalanceRehabilitationUnit.).Osparâmetrosavaliadosà pos-turografiaforam:áreadocentrodepressão(COP)evelocidadedeoscilac¸ão(VOC).

Resultados: Foram avaliados 123 idosos, com média etária de 73,11 anos. O pior desem-penhoocorreunacondiçãocúpulavisual-superfícieinstável(SI)doCTSIB.Asdiferençasentre as condições foram: superfície firme (SF)-olhos abertos (OA)/SF-olhos fechados (OF) e SI-OA/SI-OF(p<0,001);SI-OF/SI-cúpulavisual.Observou-sediferençadaáreadoCOPedaVOC entreascondições:SF-OA/SF-OF;SF-estímulosacádico/SF-estímulooptocinéticovertical; SF-estímulosoptocinéticos/SF-interaçãovisuo-vestibular(IVV);SF-IVV/SI,compiordesempenho nascondiçõesSF-OF,SF-estímulooptocinéticovertical,SF-IVVeSI-OF.Observou-sediferença doCOPentreascondiçõesSF-OF/SF-estímulosacádico,compiordesempenhonacondição SF-OF,edaVOCentreascondiçõesSF-estímulo sacádicoeSF-estímulooptocinético horizontal (p<0,001).

Conclusão:O equilíbrio corporal estático de idosos vestibulopatas é pior àmedida que as condic¸ões sensoriais sãomais desafiadoras, ouseja, em SIe SE,estímulos visuais como os optocinéticoseinterac¸ãovisuovestibulareOF.

Introduction

Body balance maintenance is influenced by the integra-tionofsensoryinformationfromthevestibular,visual,and somatosensorysystems.Anyconflictbetweenthis informa-tionmaycausechangesinbodybalance.1

With aging, the sensory systems suffer an accumula-tionofdegenerative,infectiousand/ortraumaticprocesses thathindertheiradequatefunctioning.Althoughanisolated change in one system does not result in a major impact onthe developmentof posturalinstability, a combination of suchdeficiencies is akey factor for bodyimbalancein theelderly.2,3_Among _these_systems,_the_vestibular_system

deservesattentionduetothehighprevalenceofvestibular disordersanddizzinesswithadvancingage(11.0---36.0%).4,5

Assessment of thesesystemsby clinical andlaboratory tests can be used to verify the involvement of sensory informationin posturalcontrol.6 _These _tests _simulate _the

demandsinvolvedinbodybalancethroughmanipulationof

sensoryinputs,throughchangesinvisualinput,changesin surface, andreductions in the support base. The Clinical Testof Sensory Interaction andBalance (CTSIB)is a clini-caltest,whosepurposeistoprovideinformationaboutthe individual’scapacitytoadaptandmaintainbodybalancein thepresenceofsensoryconflicts.7

Anotherwaytoassesstheinfluenceofsensory informa-tiononbodybalance isthroughlaboratory tests involving forceplatforms, electromyography,and photo-filming sys-tems. These evaluations primarily measure body sway, shiftingthecenter of gravity andmuscle activation.8 _The

Balance Rehabilitation UnitTM _(BRUTM₎ _is _a _static

posturo-graphydevicethatusesthetechnologyofvirtualrealityto recreateenvironmentsand situations inordertomeasure theposturalresponse oftheindividual inthepresence of differentstimuli.9

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testconditionsallowstheidentificationofkeyinformation for bodybalancein elderlyindividuals withchronic vesti-bulardysfunction,and,thus providesvaluableinformation for planning rehabilitation. This study aimed to evaluate theinfluenceofsensoryinformationonstaticbodybalance in elderly individuals with chronic vestibular dysfunction throughclinicaltesting(CTSIB)andlaboratoryexamination (BRUTM_).

Methods

This was a descriptive, analytical, cross-sectional study, approvedbytheResearchEthicsCommitteeofthe institu-tion,ProtocolNo.0356/2010.

Thesampleconsistedofsubjectsaged65orolder,male orfemale,whocomplainedof dizzinessforat least three monthsandhada diagnosisof chronicvestibular dysfunc-tion.Elderlypatientswhomettheinclusioncriteriaforthe study wereinvited toparticipate andsigned an informed consent.

Elderly individuals unable to understand and follow simpleverbalcommands;thoseunabletoremain indepen-dentlyintheorthostaticposition;thoseusinggait-assistive devices; those with severe visual impairment or not compensatedthroughtheuseofcorrectivelenses; insulin-dependentdiabeticswithorthopedicdisordersthatresulted in limited movement and use of prostheses in the lower limbs;individualswithneurologicaland/orpsychiatric dis-orders;thosewhoreportedalcoholintakewithin24hbefore theassessment;thoseusingmedicationsthataffectthe cen-tralnervousor the vestibularsystem; andthose thathad undergonebodybalancerehabilitationinthelastsixmonths wereexcluded.

Elderly individuals with chronic vestibular dysfunction included in the study underwent evaluation consisting of clinical data, clinical test of sensory interaction through CTSIB,andlaboratorytestingthroughcomputed posturogra-phyintegratedwithvirtualreality(BRUTM_).

Clinicaldatawerecollected:numberofdiseases,number ofmedications,historyoffallsinthelastyear,andtypeof dizziness(rotatoryorvertigo,non-rotatory,andboth).

The CTSIBassesses staticbalance in sixsensory condi-tions:conditionI,firmsurface(FS)andopeneyes;condition II, FS and closed eyes (CE); condition III, FS and visual conflict;conditionIV,unstablesurfaceandopeneyes; condi-tionV,unstablesurfaceandCE;andconditionVI,unstable surfaceandvisualconflict.Astopwatch,foam(medium den-sity),visualdome,andablindfoldwereusedtoimplement theCTSIB.8

The elderly patient was instructed to remain in each sensoryconditionfor30swithoutmakinganystepsto com-pensateforanyinstability;andtonotmovetheupperlimbs, heels, or feet. If thepatient could notmaintain stability withtheaboverestrictions,timewasstoppedandthetest wasconsideredabnormal.Theorderofperformanceof con-ditions wasrandomizedandthe patientwasallowed only oneattempt toperformeach condition.The base of sup-portusedwasbarefoot,withfeettogether,alsocalledthe Rombergposition.8,10 _The_result_of_the_CTSIB_was_analyzed

withrespecttothetimespentinsecondsandthe categoriza-tionas‘‘normal’’or‘‘altered’’foreachsensorycondition.

TheBRUTM_consists_of_a_computer_program_for_the

analy-sisofposturalcontrol;ametalsafetystructure(protection supportwithstrapsandbelt);forceplatform;virtualreality goggles;blindfold;accelerometer;andfoam.9_It_evaluates

the individual’s postural control under ten sensory condi-tions:(1)FSandeyesopen;(2)FSwiththeeyesclosed;(3) foamandeyesclosed;(4)FSandsaccadicstimulation;(5) FSand optokinetic stimulation in the horizontal direction fromlefttoright;(6)FSandoptokineticstimulationinthe horizontal direction fromright toleft;(7) FSand optoki-netic stimulationwithverticaldirectiondownward;(8)FS andoptokineticstimulationwithverticaldirectionupward; (9)FSandoptokineticstimulationwithhorizontaldirection associatedwithslowanduniformheadrotationmovements; (10)FSandoptokinetic stimulationwithvertical direction associated with slow and uniform flexion---extension head movements.9

Sensory conditions 5 and 6, as well as 7 and 8, were grouped. Thus, there was a renaming of the conditions according withthe sensorystimuli and theprogression of difficultyinposturography,asshowninTable1.

Theevaluationofeachconditionwascarriedfor60swith theelderlyindividualinstaticposture,witharmsalongthe side ofthebody. Thesupportbase usedbyposturography wasbarefoot,withadistanceof10◦_from_the_midline_of_the

anteriorportionofeachfootontheplatform,forminga20◦

anglebetweenthetwogreattoes.6 _The_software_uses_the

midpointoftheintermalleolarlineascenterofthestandard borderofthestabilitycircle.

The parameters evaluated were: area of center of pressure (COP) displacement (elliptical area of COP with distributionof95%)andvelocityofbodysway(VBS)(total distance divided by 60s) in seconds for each sensory condition.9_In_case_of_inability_to_maintain_body_balance_in

the standing position for the 60s, the parametersof the interruptedconditionwerenotrecordedbytheprogram.

Statisticalanalysis

Descriptivedataanalysiswasperformedtocharacterizethe sample. ToverifytimedifferencesintheCTSIBconditions ofandbetweenvaluesofposturographyevaluation param-eters,accordingtotheprogressionofsensoryconditionsof these tests, the Wilcoxon test was used for independent samples,inwhichthemeansoftheseconditionswere com-paredtwobytwo.Thesignificancelevelforthestatistical testswas5%(˛=0.05).Statisticalanalyseswereperformed

usingthecomputerprogramSPSS17.0.

Results

Thesampleconsistedof123patientswithchronicvestibular dysfunction,mostlyfemales(n=98;79.7%),withameanage of73.11±5.6years.Theelderlyhadonaverage3.54±1.71 diseases,used3.75±1.98drugs,and48.8%reportedfallsin thepreviousyear.Regardingthetypeofdizziness,39%ofthe samplereportedhavingbothtypesofdizziness,followedby 32.5%withvertigoand28.5%withnon-rotatorydizziness.

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Table1 ConditionsassessedbytheBalanceRehabilitationUnitTM _(BRUTM_),_regrouped_and_renamed_according_to_the_stimuli

involvedandprogression.

Conditions BRUTM _conditions _Conditions _BRUTM_conditions_regrouped_and_renamed_for_the_study

1 Nostimulus,FS,OE 1 Nostimulus,FS,OE

2 Nostimulus,FS,CE 2 Nostimulus,FS,CE

3 Nostimulus,foamsurface,OE 6 Nostimulus,foamsurface,CE

4 Saccadic,FS,OE 3 Saccadic,FS,OE

5 Optokinetic,Bars(tothe right),FS,OE

4horizontal Arithmeticmean

Optokinetic,Bars(totheright),FS,OEandOptokinetic, Bars(totheleft);FS,OE

6 Optokinetic,Bars(totheleft); FS,OE

7 Optokinetic,Bars(downward): FS,CE

4vertical Arithmeticmean

Optokinetic,Bars(downward),FS,OEandOptokinetic, Bars(upward);FS,OE

8 Optokinetic,Bars(upward):FS, OE

9 Vestibular---visualinteraction, Circular,Bars(horizontal direction),FS,OE

5horizontal Vestibular---visualinteraction,Circular,Bars(horizontal direction),FS,OE

10 Vestibular---visualinteraction, Circular,Bars(vertical direction),FS,OE

5vertical Vestibular---visualinteraction,Circular,Bars(vertical direction),FS,OE

FS,firmsurface;OE,openeyes;CE,closedeyes.

numberofabnormalcasesandtheshortestaverageduration oftimespentonthetest(Table2).Fig.1showsa compara-tiverepresentationofthesensoryconditionmeansofCTSIB accordingtothetestprogression.

Regarding theCTSIBprogression, therewasa decrease in time spent in sensory conditions 1---2 (p=0.001), 4---5 (p<0.001), and 5---6 (p=0.002). There was no significant difference from conditions 2 to 3 (p=0.136) and 3 to 4 (p=0.745).

Table3showsdatafromtheCOPareaandtheVBSofthe BRUTM_conditions._The_results_show_that_the_highest_mean_of

theCOPareaandVBSwasfound incondition6.Itwasnot

possibletocollecttheparametersofthreeelderlyin condi-tion6,but intheother conditionsall subjectscompleted thetimerequiredforrecording.

Thecomparativerepresentationoftheprogressionofthe means of COP areaat the sensoryconditions of BRUTM _is

showninFig.2.

WhencomparingtheprogressofthemeansofCOParea intheBRUTM_conditions,_we_observed,_a_significant_increase

fromconditions1to2(p=0.013),3to4vertical(p=0.001), 4to 5horizontal (p<0.001), 4 to5 vertical(p<0.001), 5 horizontalto6 (p<0.001),and5 vertical to6(p<0.001). There was a statistically significant decrease in the area

Table2 FrequenciesandvariabilityofconditionsattheClinical TestofSensoryInteractionandBalance(CTSIB)inelderly individualswithchronicvestibulardisorders.

CTSIBconditions Cases Mean(SD) 95%CI

I N 119(96.7%) 29.44

(3.26)

28.86 ---30.0

A 4(4.3%)

II N 107(87.0%) 28.11

(5.73)

27.09 ---29.13

A 16(13%)

III N 104(84.6%) 27.28

(7.26)

25.99 ---28.58

A 19(15.4%)

IV N 109(88.6%) 27.56

(7.04)

26.30 ---28.82

A 14(11.4%)

V N 91(74.0%) 25.01

(9.42)

23.32 ---26.69

A 32(26.0%)

VI N 82(62.7%) 22.99

(10.11)

21.08 ---24.90

A 41(33.3%)

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Table3 Sway velocityvariability (cm/s)andtheareaofthecenterofpressure(cm2₎_of_the_Balance_{Rehabilitation}_UnitTM

(BRUTM₎_conditions_in_elderly_individuals_with_chronic_vestibular_disorders.

BRUTM_conditions _VBS_(cm/s) _COP_area_(cm2₎

Mean(SD) 95%CI Mean(SD) 95%CI

1FS/OA 1.01(0.40) 0.94---1.08 3.88(3.80) 3.20---4.56

2FS/OF 1.34(0.57) 1.23---1.44 4.90(5.96) 3.83---5.97

3FS/saccadic 1.34(0.50) 1.25---1.43 2.93(2.23) 2.53---3.32

4 Horizontal 1.23(0.44) 3.69(3.53) 3.69(3.53) 3.05---4.32

Vertical 1.31(0.69) 3.96(3.47) 3.96(3.47) 3.24---4.48

5 Horizontal 1.75(0.74) 6.07(4.87) 6.07(4.87) 5.20---6.94

Vertical 1.74(0.62) 6.41(4.10) 6.41(4.10) 4.68---6.15

6 Foam/OF 3.01(1.24) 15.00(12.25) 15.00(12.25) 12.78---17.22

from condition 2 to 3 (p=0.001). From condition 3 to 4 horizontal(p=0.053),therewasatendencytoincrease.

When comparing the COP area with respect to the stimulus direction, no statistical difference wasobserved betweenconditions 4 horizontaland 4 vertical(p=0.479) and5horizontaland5vertical(p=0.112).

30

27.5

22.5

17.5 25

20

15 ₁ ₂ ₃ ₄ ₅ ₆

Seconds

Sensory conditions of CTSIB

Figure1 Sensory conditions oftheClinical TestofSensory InteractionandBalance (CTSIB).Graph representationofthe progressionoftimeofsensoryconditionsoftheCTSIBinelderly individualswithchronicvestibulardysfunction.

1 16

14

12

10

8

6

4

2

0

2 3 4 5 6

Sensory conditions of the BRUTM

Area Horizontal

Vertical

Figure 2 Sensory conditions of the Balance Rehabilitation UnitTM _(BRUTM_)._Graph_{representation}_of_the_progression_of_the

meansofthecenterofpressureareaofthesensoryconditions posturographicassessmentofelderlyindividualswithchronic vestibulardysfunction.

The comparative representation of the progression of means of VBSinthe sensoryBRUTM _conditions_is _shown _in Fig.3.

When comparingtheprogression ofmeans of VBS con-ditions in the BRUTM _conditions, _a _{statistically} _significant

increase wasobservedfromcondition 1to2 (p<0.001),4 to5horizontal(p<0.001),4to5vertical(p<0.001),5 hori-zontalto6(p<0.001),and5verticalto6(p<0.001).There wasastatisticallysignificantdecreasefromcondition3to4 horizontal(p<0.001)and3to4vertical(p=0.007).There wasnostatisticallysignificantdifferenceinconditions2and 3(p=0.453).

WhencomparingVBSwithrespecttothedirectionofthe stimulus, no statistical difference was observed between the4horizontaland4verticalconditions(p=0.225)and5 horizontaland5verticalconditions(p=0.157).

Discussion

The clinicalandlaboratoryassessmentscarriedoutinthis studyidentifiedanimpairmentofsensoryinformationthat affectsposturalcontrolinelderlypatients,astheseresults differfromthoseoftheelderlypopulationingeneral.8

1 2 3 4 5 6

BRUTM sensory conditions

Horizontal

Vertical 3.5

3

2.5

2

1.5

1

0.5

0

V

elocity

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Thecompositionofthesampleinthepresentstudywas representativeoftheelderlypopulationwithvestibular dis-orders, i.e., mostly female and elderly. Women aged 65 years and older have a 1.81% greater chance of repor-tingproblems relatedtodizzinesswhen comparedtomen (95%CI:1.38---2.38).4_Dizziness_constitutes_the_second_most

prevalentsymptomworldwideinindividualsupto65years ofageanditsprevalenceisapproximately80%inthoseaged 75yearsorolder.1

Falls in the elderly are the principal complication of disorders of body balance.11 _There _are _several _factors

associated with falls, but dizziness of vestibular origin is noteworthy,aspopulationstudiesshowthatthechanceof fallingincreasesbythreefold(OR:3.0;95%CI:1.9---5.0)in the presence of this complaint.12 _This _study, _and _others,

showedahigherprevalenceoffallsinelderlypatientswith vestibulardisorders5,6_compared_to_elderly_individuals_from

thesamecommunitywithoutvestibulardisorders.11

Ourstudynotedthepresenceofbothrotatoryand non-rotatorydizzinessinapproximately40.0%ofpatients,which isdifferentfromthestudybyGazzolaetal.11_One_possible

explanationforthisfindingistheconcomitantinvolvement of other systems involved in bodybalance in conjunction withthevestibularsystem,suggestingaprobable multifac-torialsensorydisorder.

WechosetheCTSIBasourmethodofclinicalassessment becauseitiseasytoapply,is lowincostandcanassistin therehabilitationassessment.Theresultsofthisstudyusing the CTSIBshow that the performance of theelderly with vestibulardisordersdeclinesfromconditionItoII,i.e.,when thereislossofvisualinformation.Visionguidesthebody’s positioninrelationtothesurroundingenvironmentandplays akeyroleindelayedstabilizationofposturalcorrectionsand intheplanningofanticipatoryreactions.13

We previously reported a decrease in the time spent in condition II comparedto condition Iin elderly individ-ualsfromthecommunitywitha historyofrecurrentfalls8

althoughwefoundnodifferencebetweentheseconditions forthosewithoutfalls.Inthecaseofelderlypatientswith acompromisedsystem,thevestibularsystemorevena his-toryoffallsdisclosesthedependenceonthevisualsystem forbodystabilization.

TheabsenceofdifferencesbetweenconditionsII,III,and IVindicatesthatwhenonlytwosystemsareactiveandone of them is the vestibular system, which was impaired in ourelderlysubjects,theremainingsystem,beitvisualor proprioceptive,couldnotmeetthenecessarydemandsfor posturalcontrolbyitself.

The changefromtwosystems(condition IV)toasingle system(conditionsVandVI)wasevenmorechallengingfor our elderly subjects withvestibular disorders. In the last twoconditionsoftheCTSIB,thevestibularsystemwasthe only accuratesensory source. Studies have shown thatin conditionsVandVI,performedwitheyesclosed,feetonan unstablesurface,andwithvisualconflict,morethan50%of theelderly withahistory offalls cannot successfullyrely onexclusivelyvestibularinformationandinterruptthetest before30s.14,15

These results were even worse in the elderly patients with vestibular disorders in our study, since our patients hadapreviouslimitationofthevestibularsystem.Thedata revealedtheseconditionstobethemost challengingwith

respecttothetimespentonthetestbytheelderlypatients, showingthevisualdependenceoftheelderlywithchronic vestibulardisordersoncertainsensoryconditionsforstatic bodybalance.ConditionsVandVIhadthehighestnumber ofalteredcases,32(26%)and41(33.3),respectively,and thelowestmeantimespentonthetest, 25.01±9.42and 22.99±10.11s,respectively.

Thus,the CTSIBcanelucidate thedifficulty individuals withvestibulardisordershaveinthemostchallenging condi-tionsandcanhelpdirectrehabilitationthroughstimulation oftheremainingsystems.

Integrated virtual reality (BRUTM₎ _is _a _more

sophisti-cated test that requires adequate equipment and is not alwaysavailableintheclinicalsetting.Thus,computerized posturographycomplements conventionaltests of otoneu-rological assessment, providing quantitative information about the influence of sensory systems on body balance control,inadditiontopromotingdisruptionofvisual infor-mation through virtual reality stimuli to maintain body balance.16

Incondition 1,thebaselinecondition ofposturography evaluation,theCOPareaandthe VBSshowednochanges whencomparedtodatafromhealthyelderly.6_These_results

aresimilartothefindingsofotherauthors17,18_who

demon-strated normal values of COP and VBS for most patients withchronic vestibulardysfunctionin this condition. This isbecausethevisualandsomatosensorycuesfor maintain-ingbodybalanceareabletocompensatefortheinaccurate informationfromthevestibularsystem.

Thus, as in the CTSIB, computerized posturography showedadifferenceintheCOPandVBSinconditions1---2, documentingthe dependence onthe visual system in the presenceofvestibulardysfunctionintheelderly.In condi-tion 2 of the posturography assessment (FS and CE), we observeddifferencesinCOPareabetweenelderlysubjects whowerehealthyandelderlypatientswithvestibular dis-orders whether they maintained stability or fell one or more times. We also observed differences on VBS scores betweenelderlypatientswithvestibulardisorderswhofell andhealthyelderlysubjects,andbetweenelderlypatients withvestibulardisorderswhodidnotfallandthosewhodid fall.Theseresultsindicatethattheuseofvisualinformation isveryimportantforthecontrolofbodybalance,especially intheelderly.6

Buatoisetal.observedsimilarfindingsbetween groups (didnotfall/historyofonefall/historyoftwoormorefalls) of healthy andfunctionally active elderly onthe balance scoreincondition2oftheSensoryOrganizationTest(SOT), fixedsurfaceandCE.19

With the introduction of visuo-vestibular stimuli, we foundthatcondition3(saccadestimulus)addednodifficulty toposturalcontrol,eitherbyVBSorCOParea,incontrast toconditions4and5,whichshowedprogressivedifficulties. Condition3usedsaccadicstimuli,relatedtorapidand smalleyemovements, whichareintended topositionthe imageand movement onto the fovea, and,thus, improve eyesight.16 _In _this_study, _the_optokinetic _stimuli _appeared

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whofellandhealthyelderlysubjects,andbetweenelderly patientswithvestibulardisorderswhodidnotfallandthose elderlypatientswithvestibulardisorderswhodidfall,with thehighervaluesobservedforthosewhofell.

These findingswerealsoidentified,in thesame condi-tion,inastudythatreportedhighervaluesoftheCOParea throughposturographyevaluationinagroupof57subjects olderthan65years(67---82years)withahistoryofinstability andfallsinthe previousyear,when comparedtothe pos-turalresponsesof46healthyvolunteers(aged29---75years) evaluatedasacontrolgroup.20

Conditions 4 horizontal and 4 vertical use optokinetic stimulation,which combines saccadic and smoothpursuit mechanisms,produced byrepeated movementsthrougha stationary visual field to provide clear images for visual stimulation.Theoptokineticstimuliareconsideredintense becausetheperception of neurovegetative symptomscan occur even without movement of the individual.21 _The

optokineticstimulicanbemorechallengingforpatientswith vestibulardysfunction,asshown inthepresent study,and alsoin healthy elderly with a history of falls.20 _However,

the direction of the stimulus does not seem to influence posturalcontrol,sincetherewasnostatisticallysignificant differencebetweenconditions4horizontaland4vertical.

The conditions 5 horizontal and 5 vertical were even morechallenging thancondition4. Theseconditions eval-uatetheperformanceofthe vestibulo-ocularreflex(VOR) associatedwithoptokineticstimulationinthehorizontaland verticaldirections,associatedwithslowanduniform rota-tionor flexion---extension movements of the head. Again, it wasshown that the difficulties imposedby the test do notdependonthestimulusdirection.ThestudybySuarez etal.22_observed_that_elderly_individuals_with_postural

insta-bilityevaluatedbyBRUTM_had_a_significant_increase_in_COP

andVBSinconditionsofvisual---vestibularinteractionwhen comparedtohealthyelderly,probablybecauseelderlywith bodyimbalancehavegreaterdifficultyinstabilizingthe reti-nalimage,whichinfersVORdamage.

AmongalltheBRUTM_conditions,_the_one_that_showed_the

highestdegree of difficultyfor both theVBS andthe COP areawascondition6.Thiscondition,inadditionto suppres-sionofvisualstimuli,includesalterationofsomatosensory information with the use of foam, causing individuals to dependmoreonvestibularfunction,whichexplainsthe dif-ficultyinmaintainingposturalcontrolbytheelderlypatients withvestibulardisorder.Thisresultissimilartothatofthe CTSIB.

Similar tothe present study, other authors23 _observed

highervaluesoftheVBSandCOPareainrelationtotheother conditions. When comparing healthy elderly with young individuals, it has been shown that when proprioception is altered (unstable surface) and vision is removed (eyes closed),elderly subjects showed significantlyhigher sway thanyoungerindividuals.24

Therefore,boththeclinicalandlaboratorytestsshowed thattheconditiononthefoam surfacewitheyesclosedis clearlythemostchallenging,particularlyforelderly individ-ualswith vestibulardysfunction,as thevestibular system cannotalone convey appropriateinformation for postural control.

Therefore,the findings of the present study can assist inthechoiceofconditionstobeprioritizedasascreening

testinelderlypatientswithacomplaintofdizzinessandin thedevelopmentofprotocolsthatmightincludedifferent stimuli(foam, virtual reality,visualocclusion,dome, pro-prioceptiveboards,amongothers)accordingtotheresults ofthesensorytest.

Conclusions

Thepresentstudyshowedadecreaseinstaticbodybalance intheelderlywithchronicvestibulardysfunctionassensory conditions become more challenging, i.e., stable surface and visual stimuli such asoptokinetic and visuovestibular interaction,andunstablesurface.

Conflicts

of

interest

Theauthorsdeclarenoconflictsofinterest.

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