BrazJOtorhinolaryngol.2019;85(4):510---519
www.bjorl.org
Brazilian
Journal
of
OTORHINOLARYNGOLOGY
REVIEW
ARTICLE
Influence
of
speech-language
therapy
on
P300
outcome
in
patients
with
language
disorders:
a
meta-analysis
夽
Deise
Renata
Oliveira
da
Silva
a,
Pedro
de
Lemos
Menezes
a,b,
Grazielle
de
Farias
Almeida
c,
Thais
Nobre
Uchoa
Souza
c,d,
Ranilde
Cristiane
Cavalcante
Costa
a,d,
Ana
Claudia
Figueiredo
Frizzo
e,f,
Aline
Tenório
Lins
Carnaúba
g,∗aUniversidadeEstadualdeCiênciasdaSaúdedeAlagoas(UNCISAL),Maceió,AL,Brazil bUniversidadedeSãoPaulo(USP),FísicaAplicadaàMedicina,SãoPaulo,SP,Brazil
cUniversidadeEstadualdeCiênciasdaSaúdedeAlagoas(UNCISAL),Fonoaudiologia,Maceió,AL,Brazil dUniversidadeFederaldeSãoPaulo(UNIFESP),DistúrbiosdaComunicac¸ãoHumana,SãoPaulo,SP,Brazil eUniversidadeEstadualPaulista(UNESP),ProgramadePós-Graduac¸ãoemFonoaudiologia,SãoPaulo,SP,Brazil fUniversidadedeSãoPaulo(USP),Neurologia,SãoPaulo,SP,Brazil
gUniversidadeFederaldeAlagoas(UFAL),RedeNordestedeBiotecnologia(RENORBIO),BiotecnologiaemSaúde,Maceió,AL, Brazil
Received30March2018;accepted2January2019 Availableonline8March2019
KEYWORDS P300evoked potential; Speech-Language therapy; Rehabilitationof speechandlanguage disorders
Abstract
Introduction:The patient’s evolutioninthe audiology andspeech-languageclinic acts asa motivator ofthe therapeutic process, contributing to patient adherence to the treatment and allowing the therapist to review and/or maintain their clinical therapeutic conducts. Electrophysiologicalmeasures,suchastheP300evokedpotential,helpintheevaluation, under-standingand monitoringofhuman communication disorders, thus facilitating theprognosis definitionineachcase.
Objective:Todeterminewhethertheaudiologyandspeech-languagetherapyinfluencesthe variationofP300latencyandamplitudeinpatientswithspeechdisordersundergoingspeech therapy.
Methods:Thisisasystematicreviewwithmeta-analysis,inwhichthefollowingdatabaseswere searched:Pubmed,ScienceDirect,SCOPUS,WebofScience,SciELOandLILACS,inadditionto thegrayliteraturebases:OpenGrey.euandDissOnline.Theinclusioncriteriawererandomized ornon-randomizedclinicaltrials,withoutlanguageordaterestriction,whichevaluatedchildren withlanguagedisordersundergoingspeechtherapy,monitoredbyP300,comparedtochildren withoutintervention.
夽 Pleasecitethisarticleas:SilvaDR,MenezesPL,AlmeidaGF,SouzaTN,CostaRC,FrizzoAC,etal.Influenceofspeech-languagetherapy
onP300outcomeinpatientswithlanguagedisorders:ameta-analysis.BrazJOtorhinolaryngol.2019;85:510---9.
∗Correspondingauthor.
E-mail:grupodepesquisalatec@gmail.com(A.T.Carnaúba).
https://doi.org/10.1016/j.bjorl.2019.01.012
1808-8694/©2019Associac¸˜aoBrasileiradeOtorrinolaringologiaeCirurgiaC´ervico-Facial.PublishedbyElsevierEditoraLtda.Thisisanopen accessarticleundertheCCBYlicense(http://creativecommons.org/licenses/by/4.0/).
Results:The meandifferencebetweenthelatencies inthegroupsubmitted totherapyand thecontrolgroupwas−20.12mswitha95%confidenceintervalof−43.98to3.74ms(p=0.08, I2=25%andpvalue=0.26).Themeandifferencebetweentheamplitudesofthegroupsubmitted
totherapyandthecontrolgroupwas0.73uVwitha95%confidenceintervalof−1.77to3.23uV (p=0.57,I2=0%andpvalue=0.47).
Conclusion: Thepresentmeta-analysisdemonstratesthatspeechtherapydoesnotinfluence thelatencyandamplituderesultsoftheP300evokedpotentialinchildrenundergoingspeech therapyintervention.
© 2019 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
Potencialevocado P300;
Terapiadalinguagem; Reabilitac¸ãodos transtornosda linguagemedafala
InfluênciadaterapiafonoaudiológicanoresultadodoP300empacientesdistúrbiode linguagem:umametanálise
Resumo
Introduc¸ão: A evoluc¸ão do paciente na clínica fonoaudiológica atua como fator motivador do processo terapêutico, contribui para a sua adesão ao tratamento e possibilita ao tera-peutaarevisão e/ouamanutenc¸ãodesuascondutas.Asmedidaseletrofisiológicas,como o potencialevocadoP300,auxiliamnaavaliac¸ão,nacompreensãoenomonitoramentodos dis-túrbiosdacomunicac¸ãohumana,facilitam,dessaforma,adefinic¸ãodoprognósticodecada caso.
Objetivo: Determinarseaterapiafonoaudiológicainfluencianavariac¸ãodalatênciaeda ampli-tudedoP300empacientescomdistúrbiodelinguagemsubmetidosàterapiafonoaudiológica. Método: Revisãosistemáticacommetanálise,naqualforamfeitasbuscasnasseguintesbases de dados: Pubmed,ScienceDirect,Scopus, WebofScience, SciELOeLilacs,alémdasbases de literaturacinzenta: OpenGrey.eueDissOnline.Foramconsiderados critériosde inclusão: ensaiosclínicosaleatóriosounão,semrestric¸ãodeidiomasoudata,quesubmeteramcrianc¸as comdistúrbiodelinguagemàterapiafonoaudiológica,monitoradaspeloP300,comparadasa crianc¸assemintervenc¸ão.
Resultados: A diferenc¸amédia entreaslatências dogruposubmetido àterapia edogrupo controle foi de -20,12mscom intervalode confianc¸a 95% entre -43,98e 3,74ms(p=0,08; I2=25%eovalordep=0,26).A diferenc¸amédiaentreasamplitudesdogruposubmetido à
terapiaedogrupocontrolefoide0,73uVcomintervalodeconfianc¸ade95%entre-1,77e3,23 uV(p=0,57;I2=0%eovalordep=0,47).
Conclusão:Aterapiafonoaudiológicanãoinfluencianosresultadosdelatênciaeamplitudedo potencialevocadoP300emcrianc¸assubmetidasàintervenc¸ãofonoaudiológica.
© 2019 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
Patient evolution at the audiology and speech-language clinicacts asamotivatorofthetherapeutic process, con-tributing to patientadherence totreatment andallowing thetherapiststoreviewand/ormaintaintheirclinical ther-apeuticconducts.1 Electrophysiologicalmeasures, inturn,
help in the evaluation, understanding and monitoring of humancommunicationdisorders,thusfacilitatingthe prog-nosisdefinitionineachcase.2
TheLong-latencyauditoryevokedpotentials(LLAEP)are objectivemeasuresusedintheelectrophysiologicalhearing assessment,correspondingtothethalamusandcortex activ-ityinresponsetotheauditorystimulus.Ithasanexogenous
component,relatedtoauditorysensitivity,andan endoge-nous component, P300, described in the literature as a cognitivepotential.3,4
P300iselicitedbyperformingaspecifictaskthatusually
includes the discrimination between two randomly
pre-sented auditory stimuli (a frequent stimulus and a rare one).Inthis sense,the evaluatedsubjectshouldindicate thestimulusthatis considered rare,thusreflecting infor-mationabout functions such as attention, discrimination, integrationandmemory.4Latencyisdirectlyrelatedtothe
processingofinformationandtheamplitudetothenumber ofinformationthatthestimuluswasabletotransmit.5
The development of language, on the other hand, is
512 SilvaDRetal. the interrelationship of a set of cognitive, linguistic and
socio-pragmatic skills that language becomes effective.6
Therefore,changesin auditoryprocessing,changes inthe
development of language expression and/or reception,
changesinthewrittenlanguagedevelopment,phonological disordersanddisfluenciesmayleadtochangesinthelatency and amplitude of P300. Nevertheless, the rehabilitation of thesedisorders promotes functionaland morphological modificationsinthecentralnervoussystem(CNS)asa con-sequenceofneuroplasticity.7
Considering the high frequency of language changes, especiallyinthepediatricpopulation,performingtheP300 hasgained space in scientific research.8---10 Thus, the
sys-tematicreviewofthiscontentwillprovidebetterplanning in future studies, a synthesis of the knowledge gathered so far, in addition to adding new knowledge, subsidizing clinicalpracticeandrepresentingtheimportanceof speech-languageaudiologistsandotorhinolaryngologists’work.11
Therefore,theaimofthisstudyistodeterminewhether speechtherapyinfluencesthevariationinthelatencyand amplitudeoftheP300auditoryevokedpotentialinpatients withspeechdisordersundergoingspeechtherapy.
Methods
The review is reported according to the items in the
PreferredReportingItemsforSystematicReviewsand Meta-AnalysesStatement(PRISMA).12
Searchstrategies
The strategies aimed at a complete search, including
descriptors(DECsandMESH)andFreeTerms(TL),basedon thefourelementsofPICO(Patient,Intervention, Compari-son,Outcome)presentinthetitle,whichconsistof:(childor childrenorpreschool)and(eventrelatedpotentialorp300 ORevokedpotential)and (languagedisordersor language therapyordevelopmentdisordersorrehabilitationofspeech orspeechtherapy).The completestrategyis foundinthe supplementarymaterial(Appendix1).
The searches were performed between April and May
2017andwerereviewedinSeptember2018.Thefollowing databasesweresearched:Pubmed,ScienceDirect,SCOPUS, WebofScience,SciELOandLILACS,aswellasthegray litera-turedatabases:OpenGrey.eu,DissOnline,withoutlanguage or date restrictions. There was no manual search of the includedarticlestoavoidtheriskofcitationbias.13
Criteriaofeligibility
Inclusioncriteriawere:randomizedornon-randomized clin-ical trials that involved children with language disorders in speechtherapy, monitored by P300,compared to chil-dren without intervention, aswell as the meanvalues of P300latency and amplitude in the first and second eval-uations, associated with a dispersion measure. Exclusion criteriawere studies evaluating children with peripheral, cognitive, psychiatric or neurological auditory disorders. Repeatedarticlesindifferentdatabaseswerealsoexcluded.
Dataextraction
Titlesandabstractsofarticlesobtainedthroughthesearch wereindependentlyassessedbytwoinvestigatorswhowere not blinded to the authors or to the titles of the jour-nals.Divergenceswereresolvedbyconsensus.Incaseswith noconsensus,a third authorwasasked tomake the final decision.Thefulltextsofpotentiallyeligiblearticleswere acquiredandanalyzedinfull.The outcomessought inthe studieswerethemeanvaluesoflatencyandamplitudeof theP300componentspre-andpost-speechtherapy associ-atedwithameasureofdispersion.Thedataofthepublished articleswereanalyzed,andtheauthorswerecontactedfor additionalinformation.Inadditiontotheoutcomedata,the authors’names,article title,yearofpublication,country, agegroups,pathology,intervention,numberofsessionsand studied groups were also extracted. A standard form for datastorage wascreated basedonthemodel adopted by Cochrane.14
Evaluationofstudyquality
Study quality was evaluatedaccording tothe recommen-dationsfoundintheCochraneCollaborationmanual.15 Two
investigatorsindependentlyassessedthequalityofthe stud-iesinthefollowingcategories:generationoftheappropriate sequence; allocation concealment; blinding of the evalu-ators; and handling of missing data for subsequent final judgment.
Dataanalysis
The latency and amplitude variation of the P300 Evoked Potentialforbothgroups(StudyGroupsubmittedtotherapy andControlGroupnotsubmittedtotherapy)wascompared throughameta-analysis.Forthispurpose,arandomeffects
model was used asa measure of the effect of the mean
differencebetween the groups andas a statistical analy-sismethod.An˛valueof0.05wasconsideredstatistically significant. When it was not possible to obtain adequate datafortheanalysis,theCochranerecommendationswere followed.
Thestatisticalheterogeneitybetweenstudieswastested usingtheCochraneQTestandinconsistencywastestedusing theI2test.Ap-value<0.10wasconsideredstatistically
sig-nificant. When necessary,study characteristicsconsidered potentialsourcesofheterogeneitywereincludedina sub-group analysis.Additionally, in case ofheterogeneity, the studies were removed one by one to investigate whether thatparticularstudywasthesourceofheterogeneity.
All analyses were performed using RevMan software
(Computer program,Version 5.3.Copenhagen: The Nordic CochraneCenter,TheCochraneCollaboration,2014).
Results
Includedstudies
Ofthe1008titlesconsideredrelevantbasedonthesearches intheaforementioneddatabases,21textswereselectedfor
of speech-language therapy on P300 outcome in patients with language disorders: a meta-analysis 513
Table1 Characteristicsoftheincludedstudies.
Study Place Agerange
(years) Language pathology Intervention N.ofsessions (timeinmin) Groups Re-evaluation Alvarenga,201330 Brazil 08 ---14 Dyslexia Phonological remediation 24sessions(45min each) GEandGC SGandCG(3 months) Leite,201031 Brazil 8 ---11 Phonological disorder Therapy (cycle model) 12sessions(45min each)
GT,GEandGC TG(therewasno re-evaluation),SG andCG(3months) Leite,201432 Brazil 8 ---11 Phonological disorder Therapy (cycle model) 12sessions(45min each)
GT,GEandGC TG(therewasno re-evaluation),SG andCG(3months)
514 SilvaDRetal. fullreading.Ofthese,18wereexcluded16---33becausethey
didnotmeettheeligibilitycriteria(Appendix2).Therefore, threefulltextswereincludedinthequalitativeand quan-titativeanalysis(Table1).Theflowdiagramillustratingthe searchandselectionprocessisshowninFig.1andthemean latenciesandamplitudesoftheP300ofthearticlesincluded inthemeta-analysisareshowninTable2.
Therewerenosignificantdifferencesbetweentheright andleftearsforallgroupsinallincludedstudies.Moreover, theOddballparadigmandtheInternational10---20systemfor electrodeplacementwereused,inadditiontoasignificance levelof5%.TheotherparametersforP300acquisitioncan befoundinTable3.
InthestudybyAlvarenga,34 whichincluded 20students
withadiagnosisofDevelopmentalDyslexia,10ofthemwere submitted totherapy (GI) and 10 characterized the Con-trolGroup (GII). TwoP300 evaluationswereperformed in thesameintervalfor bothgroups. Aftertheintervention, GIshowedastatisticallysignificantresultfor P300latency (p=0.005).TheauthorsconcludedthatP300isanefficient tooltomonitorthe therapeuticevolutionofchildren with DevelopmentalDyslexia.
The studybyLeite35 evaluated66 children,25ofthem
without phonological disorder (group with typical devel-opment)and41 withphonological disorder (studygroup), which theydivided intotwosubgroups: 22 comprisedthe studysubgroupA,submittedto12speechtherapysessions andre-evaluatedbytheLLAEPaftertheintervention,and
19 comprised the study subgroup B, reassessed 3 months afterthefirstevaluation.Statisticallysignificantdifferences were identifiedbetween the groups withtypical develop-ment and study for P300latencies and amplitudes. When comparingthefirstandthesecondevaluations,significance was observed for the P300 amplitudes in the study sub-groupA(p=0.039).Thelatencyresultswerenotsignificant for the two subgroups. The authors also used a criterion
ofimprovementandnon-improvementbasedonthemean
latencyandamplitudedifferencesoftheLLAEPcomponents ofSubgroupB.Inthisevaluation,theyreportedthatafter thetherapy,improvementwasobservedinallcomponents oftheexamination.Therefore,theyconcludedthatchildren withphonologicaldisordershavealterationsinP300andthat theaudiological/speech-languageinterventionresultsinthe improvementofresultsofalltheLLAEPcomponents.
AnotherstudybyLeite36investigated47children,usinga
similarmethodology.Thechildrenweredividedintogroups withtypicaldevelopmentandstudygroups.Thegroupwith typicaldevelopmentconsistedof24childrenandthestudy groupof23 childrenwithphonological disorders,withthe latterbeingdividedintotwosubgroups:SG1,consistingof 12childrensubmittedto12speechtherapysessionsandwho werere-evaluatedthroughLLAEPaftertheintervention,and SG2,consisting of11 childrenwhowere notsubmittedto speechtherapyandwerere-evaluatedthreemonthsafter the initial evaluation. They obtained a significant result forP300latencyinthegroupsubmittedtospeechtherapy
Articles identified through searches in databases (n = 1008) Screening Included Eligibility Identification
Articles identified through other sources
(n = 0)
Articles after removal of duplicates (n =1000)
Evaluated articles (n =1000)
Excluded articles (n = 979)
Full texts acquired for evaluation
(n = 21)
Excluded full texts (n = 18):
Does not evaluate P300 (n=8); Does not include intervention
(n=3);
Does not have a control group (n=1);
Standardization (n=1); Addressed other subjects
(n=4);
Thesis with published article (n=1)
Studies included in the qualitative synthesis
(n = 3)
Studies included in the qualitative synthesis
(n = 2)
of speech-language therapy on P300 outcome in patients with language disorders: a meta-analysis 515
Table2 MeanslatenciesandamplitudesoftheP300atthefirstandsecondevaluations.
Study Latency(ms) Amplitude(v)
Mean(SD) Mean(SD) GE GC GE GC I II I II I II I II Alvarenga,2013 431.22(29.69) 387.71(31.18) 398.33(48.22) 385.21(46.37) 7.85(2.77) 8.48(2.08) 7.25(4.94) 7.74(3.32) Leite,2010 360.4(48.5) 349.3(48.55) 344.1(51.1) 334.0(42.4) 13.83(5.87) 17.97(12.59) 13.38(5.26) 15.35(6.11) Leite,2014 394.73(54.24) 361.82(37.66) 349.55(60.68) 358.00(59.94) --- --- ---
516 SilvaDRetal. Table3 ParametersofstimulationandacquisitionofP300evokedpotential.
Parameters Alvarenga,2013 Leite,2010 Leite,2014
Stimulation
Stimulator 3Ainsertphone, binaural stimulation Monoaural stimulation Supra-aural (TDH-39) Rate 1s/s 1.1s/s 1.1s/s
Type Speech---/da/
rare;/ba/ frequent
Toneburst Toneburst
Paradigm Oddballfrequent --- 80%,rare--- 20% Oddball1kHz frequent;1.5kHz rare--- 20% Oddball1kHz frequent(80%); 1.5kHzrare--- 20% Duration --- --- Rise/fall:10.00 plateau:30.00
Intensity Fixed80dBNA Fixed75dBNA 75dBnHL
Polarity --- --- Alternating Acquisition Timeofanalysis --- 512ms 300ms Channels --- 2channels ---Electrodes Fz,Cz(active);M1 andM2 (reference)≤5k (individual); ≤2k(between electrodes) Cz(reference), Fpz(ground),M2 andM1(active) 5electrodes ---impedance≤5k Filters 1---30Hz 30.00---1.00Hz 1---30Hz Signal amplification --- --- ---Sampling --- 300 1000
Patientstatus Alert/attentive Attentive Attentive
intervention(p=0.024).Theauthorsdidnotreportthe val-uesforamplitude.
Studyqualityevaluation
The quality analysis of the included studies is shown in
Table4.
All included studies were characterized as
non-randomizedclinical trials.Therefore, itis not possible to judgethem regarding the categories of randomsequence
generation and allocation concealment. Two of them
(Leite,35 2010 and Leite,36 2014) reportedthe blinding of
theevaluatorstoanalyzethelatencies andamplitudes of the P300 Evoked Potential, from the inclusion of evalua-torsblindedtothesubjects’identitiesandtheircategories of participation. Regarding the handling of missing data,
Leite36 2014 reported the abandonment of one member
of the therapy group and absence of two members that
belongedtothe groupwithout intervention inthe second
evaluation. However, he did not report how he treated
these data in the statistical analysis. It should be noted thatregardlessofthefinaljudgmentfoundinthetable,the threestudiesshow,accordingtotheirnature,ahighriskof biasduetonon-randomizationduringtheselectionoftheir researchsubjects.
Dataanalysis
Asthestudiesarenonrandomized,thegroupsshowedgreat divergenceasearlyasinthefirstevaluation.Thus,toavoid thephenomenonofregressiontothemean,thevariations between the final and initial latency and amplitude val-ues wouldbenecessary,aswellasthestandard deviation associatedtothesevariations.
Latency
Threestudies(84individuals)wereevaluated(Fig.2).The mean differencebetween thelatencies of the group
sub-mitted to therapy and the Control Group was −20.12ms
with95%CIof −43.98to3.74ms.Thegeneral effecttest showedap=0.10,revealingthatsuchadifferencewasnot significant.Fortheheterogeneity,I2=27%andthevalueof
p=0.25. To avoid the occurrence of reverse causality, as theexposurechangesasaresultofthedisease,asubgroup analysisofthesamelanguagedisorder(phonological
disor-der) was performed. Thus, the mean difference between
the latencies of the group submitted to therapy and the
Control Group was −16.59ms, with 95% CI of −55.11 to
21.9ms.The testfor theoveralleffectshowedap=0.40, alsorevealingthattherewasnosignificantdifference.For theheterogeneity,I2=50%andthevalueofp=0.16.
Table4 Evaluationofincludedarticles.
Authors Maskingofevaluators Managementofabsentdata Finaljudgment
Alvarenga,2013 Uncertain Low High
Leite,2010 Low Low Low
Leite,2014 low Uncertain High
Study or subgroup
Experimental Control
Weight
Mean Difference Mean Difference
Favours [experimental] Favours [control] IV, Random, 95% CI IV, Random, 95% CI
Total (95% CI)
Heterogeneity. Tau2 = 122.61; Chi2 = 2.74, df = 2 (P = 0.25); I2 = 27%
Test for overall effect: Z = 1.65 (P = 0.10) -100 -50 0 50 100
Mean -43.51 Alvarenga et al., 2013 Leite et al., 2010 Leite et al., 2014 -11.1 -32.91 30.46 48.52 48.14 12 22 10 -13.12 -10.1 8.45 44 11 19 10 47.32 36.7% -30.39 [-63.24, 2.46] -1.00 [-30.40, 28.40] -41.36 [-89.19, 6.47] -20.12 [-43.98, 3.74] 40 42.6% 20.6% 100.0% 47.35 60.31 Mean SD Total SDTotal
Figure2 Meta-analysis:comparisonoflatencies.
Amplitude
Two studies (61subjects) were evaluated(Figs.3 and 4). ThearticlebyLeite36didnotincludethesearchfor
ampli-tudevalues.Themeandifferencebetweentheamplitudes ofthegroupsubmittedtotherapyandtheControlGroupwas 0.73uVwith95%CIof−1.77to3.23uV.Theoveralleffect testshowedap=0.57,showingthatthisdifferencewasnot significant. Fortheheterogeneity,I2=0%andthe valueof
p=0.47.
Discussion
Threearticlesmettheinclusioncriteriaofthepresent meta-analysis,tworelatedtothe PhonologicalDisorder35,36 and
one related to Dyslexia.34 Despite the different language
alterations,sincethephonological disorderaffectsorality anddyslexiaaffectsthereadingsystem,bothinclude phono-logical processingdeficits asabasal alteration.Moreover, thestudiessharesimilaritiesregardingthesubjects’ageand thefactthattheyincludesometypeofintervention.
The present review doesnot aimtofindsimilaror dif-ferentaspectsbetweenthelanguagealterations,nordoes it intend to evaluate the therapeutic procedures used. Ratheritsimplyaimstodeterminewhetherspeechtherapy influencesthe variationof P300latency and amplitudein patientswithspeechdisorderssubmittedtospeechtherapy. Theindividualresultsofthestudiesthatconstitutethis reviewstatethatthestimulationperformedbythe speech-language intervention is able to reorganize the auditory andcognitiveprocessingabilities,thusobservinga reorga-nizationcapacityofthebrainintheprocessingofauditory information,basedonthebrainneuroplasticitycapacity.
They suggest that this effectiveness of the
speech-language intervention occurs regardless of variables
relevant to the pathology and the intervention, as the results were favorable in different language alterations andin differentmethodologies appliedintherapy. There-fore,theeffectivenessofthespeech-languageintervention,
found through the P300 analysis, occurs independently
of the affected language modality and the strategies or
therapeuticresources usedbythespeech-language thera-pist.
The interventioneffectiveness isseen throughchanges intheP300latencyandamplitudeinabroadmanner, with-outquantifyingthe percentageofimprovement according tothetherapy.Therefore,theparametersusedinthetest acquisition,aswellasthemethodologicalcharacteristicsof thestudies,aregivengreaterrelevance.
Regarding the test protocols, all the articles
fol-lowed the recommendations of the International 10/20
System for electrode placement (derivation) and used
the Oddball paradigm. One of the studies34 did not use
the tone burst stimulation for the potential acquisition, using the speech stimulus to obtain specific information regarding auditory discrimination and language process-ing.
Althoughthearticlesthatcomprise thisreview individ-uallyindicate that the P300undergoes changes regarding itsamplitude andlatency parametersasan effectof the speech-language intervention, the results of the meta-analysisdonotshowthesamething.
Regarding the methodological quality, all the studies showedahighrisk ofbias.This statementisbasedmainly on the impossibility of judging by the random sequence generation and allocation concealment criteria, showing animportant selectionbias. Furthermore,inthestudy by Leite36 thestatisticaltreatmentusedinthestudywasnot
reportedduetothe lossof researchsubjects,which con-stitutesan attritionbias.On theother hand, theconcern withtheblindingoftheevaluatorsappeared.It shouldbe rememberedthatthearticlebyLeite35haslowriskofbias
whenconsideringonlyitscategory(non-randomizedclinical trial).
Moreover,oneofthestudieswasexcludedforthe ampli-tude comparison due to lack of data. This result calls attentiontotheneedforbetterplanninginfutureresearch, thus increasing the worth of these investigators’ perfor-mance.
Therefore,thefirstevaluationalreadyshowsa discrep-ancyinthelatencyandamplitudemeanvaluesduetothe severalconfoundingvariablesintheselectionofthegroups.
518 SilvaDRetal.
Study or subgroup
Experimental Mean Difference Mean Difference
IV, Random, 95% CI IV, Random, 95% CI Mean SD Total Mean SD
Control
Weight Total
Favours [experimental] Favours [control]
-100 -50 0 50 100
Heterogeneity. Tau2 = 404.22; Chi2 = 1.99, df = 1 (P = 0.16); I2 = 50% Test for overall effect: Z = 0.84 (P = 0.40)
Total (95% CI) -16.59 [-55.11, 21.93] -1.00 [-30.40, 28.40] -41.36 [-89.19, 6.47] 29 100.0% 32 Leite et al., 2010 -11.1 -32.91 48.52 48.14 22 -10.1 8.45 47.35 60.31 19 10 61.4% 38.6% 10 Leite et al., 2014
Figure3 Meta-analysis:comparisonoflatenciesbetweensubgroupswiththesamelanguagealteration.
Heterogeneity. Tau2 = 0.00; Chi2 = 0.52, df = 1 (P = 0.47); I2 = 0% Test for overall effect: Z = 0.57 (P = 0.57)
Total (95% CI) 32 29 100.0% 0.73 [-1.77, 3.23]
Study or subgroup
Audiology and Speech-Language Therapy Control Mean Difference Mean Difference
Favors Audio and Speech-Language Therapy
Favors Control IV, Random, 95% CI [uV] IV, Random, 95% CI [uV]
Total SD [uV] SD [uV] Mean [uV]
Mean [uV] TotalWeight
-10 -5 0 5 10 Leite et al., 2010 Alvarenga et al., 2013 0.63 4.14 2.43 9.23 10 22 0.49 1.97 4.13 5.69 10 19 70.8% 0.14 [-2.83, 3.11] 2.17 [-2.46, 6.80] 29.2%
Figure4 Meta-analysis:comparisonofamplitudes.
Whendiscussingthisdiscrepancy,itrefers,forinstance,to thelatenciesfoundinthestudybyLeite.36Init,thegroup
selected for speech therapy intervention had in the first evaluationameanvalueof394.73ms,whereastheControl Grouphad349.55ms.
Consideringthesevalues,onecanobservethedistinction betweenthegroups and,therefore, itcannotbeaffirmed that the values found in the second evaluation strongly consist of the therapy effect or only the phenomenon of regressionto the mean.Nonetheless,none of the studies attemptedtominimizethesediscrepancies.
Conversely,toperformthemeta-analysis,theCochrane guidelines were followed14 and the variations of mean
latency andamplitude valueswere calculated, aswell as thestandarddeviationassociatedwiththisvariation.
Incontrast,theliteraturepointstothesuccessof speech-languageintervention in themost diverse disorders.Silva andCapellini,37demonstratedtheefficacyofaphonological
interventionprogramin schoolchildrenat riskfor dyslexia after the application of a specific protocol for assessing cognitive---linguistic abilities pre- and post-therapy. Its
intervention methodology resembles that proposed by
Alvarenga,34whichworkedwithmetaphonologicalskillsand
auditory processing, amongothers. Nevertheless, Rosal,38
verifiedin theirstudythe importanceof thesesameskills forthelearningofwriting.
Despitethephonologicaldisorders,differentapproaches and authors report the good results in the evolution of thispatientprofile.WiethanandMota39gavedifferent
con-tributionsofdifferentapproaches aimedattreatingthese alterations. Gubiani and Keske-Soares40 also verified the
phonologicalsystemevolutioninpatientstreatedwith dif-ferenttherapeuticapproaches.
Thedivergencefoundbetweentheindividualresultsof the studies that constitute this review, which affirm that speechtherapyinfluencesP300alterations,andtheresults ofthismeta-analysis,whichfoundthatspeechtherapydoes not influence the latency and amplitude results of P300, shouldbeinterpretedwithcaution,astheyderivefroma smallnumberofnon-randomizedclinicaltrials.Thelackof theinterventioneffectmay bemuchmorerelatedtothe
lack ofscientificrigor oftheincluded articlesthantothe non-evolutionofthesepatientspost-therapy.
Conclusion
The present meta-analysis demonstrates that
speech-language therapy does not influence the latency and
amplituderesultsoftheP300EvokedPotential inchildren withlanguagedisorderssubmittedtoaudiologyand speech-languageintervention.
Conflicts
of
interest
Theauthorsdeclarenoconflictsofinterest.
Appendix
A.
Supplementary
data
Supplementary data associated with this article can be found,intheonlineversion,atdoi:10.1016/j.bjorl.2019.01.
012.
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