www.bjorl.org
Brazilian
Journal
of
OTORHINOLARYNGOLOGY
ORIGINAL
ARTICLE
Laryngeal
and
vocal
alterations
after
thyroidectomy
夽
Renata
Mizusaki
Iyomasa
a,
José
Vicente
Tagliarini
a,
Sérgio
Augusto
Rodrigues
b,
Elaine
Lara
Mendes
Tavares
a,
Regina
Helena
Garcia
Martins
a,∗aUniversidadeEstadualPaulista‘‘JúliodeMesquitaFilho’’(UNESP),DisciplinadeOtorrinolaringologiaeCirurgiadeCabec¸ae Pescoc¸o,Botucatu,SP,Brazil
bUniversidadeEstadualPaulista‘‘JúliodeMesquitaFilho’’(UNESP),InstitutodeBiociências,Botucatu,SP,Brazil
Received19May2017;accepted29August2017 Availableonline21September2017
KEYWORDS Thyroidectomy; Dysphonia; Laryngealparalysis; Hoarseness; Acousticanalysis Abstract
Introduction:Dysphoniaisacommonsymptomafterthyroidectomy.
Objective: Toanalyze the vocal symptoms, auditory-perceptualand acoustic vocal,
video-laryngoscopy, the surgical procedures andhistopathological findings in patients undergoing thyroidectomy.
Methods:Prospectivestudy.Patientssubmittedtothyroidectomywereevaluatedasfollows: anamnesis,laryngoscopy,andacousticvocalassessments.Moments:pre-operative,1stpost(15 days),2ndpost(1month),3rdpost(3months),and4thpost(6months).
Results:Among the 151 patients (130 women; 21 men). Type of surgery:
lobec-tomy+isthmectomyn=40,totalthyroidectomyn=88,thyroidectomy+lymphnodedissection
n=23.Vocalsymptomswerereportedby42patientsinthe1stpost(27.8%)decreasingto7.2% after 6months.In theacousticanalysis,f0 andAPQwere decreasedinwomen. Videolaryn-goscopies showedthat144patients (95.3%)hadnormalexamsinthepreoperativemoment. Vocal fold palsies were diagnosed in 34 paralyzes at the 1st post, 32 recurrent laryngeal nerve(lobectomy+isthmectomyn=6;totalthyroidectomyn=17;thyroidectomy+lymphnode dissectionn=9)and2superiorlaryngealnerve(lobectomy+isthmectomyn=1;Total thyroidec-tomy+lymphnodedissectionn=1).After6months,10patientspersistedwithparalysisofthe recurrentlaryngealnerve(6.6%).Histopathologyandcorrelationwithvocalfoldpalsy:colloid nodulargoiter(n=76;palsyn=13),thyroiditis(n=8;palsyn=0),andcarcinoma(n=67;palsy
n=21).
夽 Please citethisarticle as:Iyomasa RM,Tagliarini JV, Rodrigues SA, TavaresEL, MartinsRH. Laryngealand vocal alterations after
thyroidectomy.BrazJOtorhinolaryngol.2019;85:3---10.
∗Correspondingauthor.
E-mail:rmartins@fmb.unesp.br(R.H.Martins).
PeerReviewundertheresponsibilityofAssociac¸ãoBrasileiradeOtorrinolaringologiaeCirurgiaCérvico-Facial. https://doi.org/10.1016/j.bjorl.2017.08.015
1808-8694/©2017Associac¸˜aoBrasileiradeOtorrinolaringologiaeCirurgiaC´ervico-Facial.PublishedbyElsevierEditoraLtda.Thisisanopen accessarticleundertheCCBYlicense(http://creativecommons.org/licenses/by/4.0/).
Conclusion:Vocalsymptoms,reportedby27.8%ofthepatientsonthe1stpostdecreasedto 7%in6months.Intheacousticanalysis,f0andAPQweredecreased.Transientparalysisofthe vocalfoldssecondarytorecurrentandsuperiorlaryngealnerveinjuryoccurredin,respectively, 21%and1.3%ofthepatients,decreasingto6.6%and0%after6months.
© 2017 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 Tireoidectomia; Disfonia; Paralisialaríngea; Rouquidão; Análiseacústica
Alterac¸õeslaríngeasevocaisapóstireoidectomia
Resumo
Introduc¸ão:Adisfoniaéumsintomacomumapósatireoidectomia.
Objetivo:Analisar os sintomasvocais, auditivo-perceptivos eacústica vocal, videolaringos-copia,procedimentocirúrgicoeachadoshistopatológicosempacientessubmetidosà tireoidec-tomia.
Método: Estudo prospectivo. Pacientes submetidos à tireoidectomia foram avaliados da
seguinte forma: anamnese, laringoscopia e avaliac¸ões vocais acústicas. Momentos: pré-operatório,1a avaliac¸ãopós(15dias),2aavaliac¸ãopós(1mês),3a avaliac¸ãopós(3 meses) e4aavaliac¸ãopós-operatória(6meses).
Resultados: Dos151pacientes,130erammulherese21,homens.Tiposdecirurgia:lobectomia +istmectomian=40,tireoidectomiatotaln=88,tireoidectomia+dissecc¸ãodelinfonodon= 23.Sintomasvocaisforamrelatadospor42pacientesna1aavaliac¸ãopós-operatória(27,8%), reduzidos para 7,2% após 6 meses. Na análise acústica, f0 e APQ estavam diminuídos nas mulheres.Asvideolaringoscopiasmostraramque144pacientes(95,3%)tiveramexamesnormais nomomentopré-operatório.Paralisiadascordasvocaisfoidiagnosticadaem34pacientesna 1aavaliac¸ãopós-operatória,32donervolaríngeorecorrente(lobectomia+istmectomia-n=6; tireoidectomiatotal-n=17;tireoidectomiatotal+dissecc¸ãodelinfonodos-n=9)e2donervo laríngeosuperior(lobectomia+istmectomia-n=1;tireoidectomiatotal+dissecc¸ãode linfono-dos-n=1).Após6meses,10pacientespersistiramcomparalisiadonervolaríngeorecorrente (6,6%).Histopatologiaecorrelac¸ãocomparalisiadascordasvocais:bóciocoloidenodular(n =76;paralisian=13),tireoidite(n=8;paralisian=0)ecarcinoma(n=67;paralisian=21).
Conclusão:Os sintomas vocais, relatados por 27,8% dos pacientes na 1a avaliac¸ão
pós-operatória, diminuírampara 7% em 6 meses. Na análiseacústica, f0 eAPQ diminuíram. A paralisiatransitóriadecordasvocaissecundáriaàlesãodonervolaríngeorecorrenteenervo laríngeosuperiorocorreu,respectivamente,em21%e1,3%dospacientes,reduziu-separa6,6% e0%após6meses.
© 2017 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
Total(TT)orpartialthyroidectomy(PT)mayresultinvocal impairmentduetoextrinsiccompressionoftheglandonthe larynx,endotrachealintubation,dissectionof thecervical muscles,hematomas,anddamagetothelaryngealnerves. Dysphoniamayoccurinupto90%ofpatients,especiallyin theimmediatepostoperativeperiodandpersistforthreeto 6monthsin11---15%ofcases.1Therecurrentlaryngealnerve
(RLN)aswellastheexternalbranchofthesuperiorlaryngeal nerve(SLN)canbetemporarilyorpermanentlyinjured.The estimatedratesofinjurytotheSLNvaryfrom0.3%to13% andtotheRLNfrom5%to10%,beingtemporaryin5%and permanentin0.5---2%.2
DamagetotheRLNisthemaincauseofdysphoniaafter thyroidectomy.3---5Therecurrentlaryngealnervehasseveral
extralaryngealbranchesand directrelation withthe infe-riorthyroid artery,at superficialanddeeplevel,andmay
be injured as the artery is divided. Paralysis of the RLN resultsinimmobilityofthevocalfoldontheaffectedside, causing hoarseness andvocal fatigueasa consequence of glotticinsufficiency.6,7Thesuperiorlaryngealnervemaybe
affected during thyroidectomy when the superior thyroid arteryis dividedor after localcauterization,6 resultingin
alesstensevocalfoldbydecreasedactivityofthe cricothy-roidmuscle(CT).Undertheseconditions,thevocalabilityof arapidchangeinregisterisimpaired,aswellastheemission ofhighpitchsoundsandpitchmaintenance.Howeversome authors point out changes in vocal patternsin 14---30% of patientsafterthyroidectomy,evenwithoutnervedamage.8
The causes include laryngotracheal fixation by adherence to pre-tracheal muscles, injury to the perithyroid neural plexus,traumafromintubation,surgicaltraumaoftheCT orcricothyroidjunction,andchangesinthevascularsupply andvenous andlymphatic drainage ofthelarynx. Mostof theselaryngealalterationsareself-limited.9,10
Inastudythatincluded54patientswhounderwentTT, Stojadinovic et al.10 analyzed the voices of the patients
before and after surgery and identified only one case of SLNinjuryandnocasesofRLNparalysis. However,30%of patientspresented dysphoniainthe1stpostoperativeday and 14% were still symptomatic after 3months. In addi-tion,84%ofpatientshadalterationsinatleastoneacoustic parameterintheimmediatepostoperativeperiod.
Patientswiththyroidcancerhavehigherriskoflaryngeal nerve impairment by tumor infiltration, and may present preoperative vocal symptoms.Rohetal.11 ina study that
included319patientswithpapillarythyroidcarcinoma(256 had total thyroidectomy, 42 lobectomy, and 21 were re-operated for recurrent carcinoma) identified 14 patients withpreoperative vocalfoldparalysisand15with postop-erativeparalysis.Inthelatter,theparalysiswastemporary in4.6%andpermanentin1.3%.Theauthorsemphasizedthat vocalfoldparalysismaygounnoticedbythepatientinupto 50%ofcases,especiallywhenitstartsinaslowandinsidious manner, reinforcing the importance of videolaryngoscopy beforeandaftersurgery.
The objective of this study was to analyze the pres-ence of vocal symptoms, acoustic vocal characteristics, andvideolaryngoscopyfindingsinpatientsundergoing thy-roidectomy, relating them to the type of surgery and histopathology.
Methods
Allpatients seen at aUniversity clinic for thyroid disease submittedtothyroidectomyfrom2012to2015wereinvited toparticipateinthestudy.Thestudywasapprovedbythe InstitutionalCommitteefor Ethicsin HumanResearchand thepatientssignedafree,prior,andinformedconsent.
Exclusion criteria:patients withprevious thyroid, neck surgery or benign laryngeal lesions, previous vocal folds paralysis,neuromusculardisordersthatcompromise laryn-geal structures, subjects with lung diseases or history of prolongedintubation.
Demographic data, voice symptoms, respiratory disor-ders,previousthyroidsurgeries,typeofsurgicalprocedure and histopathology were recorded. The patients were submitted to laryngoscopy using a rigid telescope (70◦, 8mm, brandAsap,Germany)ornasal endoscopes (diame-ter3.5mm,Olympus,Japan)coupledwithimagecapturing conjugated system(multifunctionalvideo system type XE-50,EcoV50WX---TFT/USB---ILOELECTRONICGnbH,Carl ---Zeiss,Germany).
The MDVP system (Multi Dimensional Voice Program ---Multi Speech 3700, model 5105, Kay Elemetrics Corpora-tion, USA) and a headset microphone (Shure, São Paulo, SP, Brazil) connectedto thesoundboard (Behringer Xenyx 502 model,Germany)were usedfor acousticvocal analy-sisduringsustainedemissionofthe/a/vowel,maintaining comfortablepitch.Theinitialandfinaltwosecondsofthe recordingswereremovedsincetheyaresubjecttoemission instabilities.The followingacousticparameterswere ana-lyzed:fundamental frequency (f0),Jitter percentage (%), pitch perturbation quotient (PPQ%), Shimmer percentage (%),amplitude perturbation quotient (APQ, %),noise har-monicratio(NHR),andsoftandphonationindex(SPI).
Momentsstudied
Preoperative(during the week of hospital admission),1st (up to 15 days), 2nd (one month), 3rd (3 months), and 4th(6months)postoperativeevaluations,thelatterbeing reservedonlytopatientswhoremainedwithalterationsin the3rdpostoperativeevaluation.
Statisticalanalysis
Vocalacousticanalysis
Thecomparison betweentimes wasdone usingthe Fried-mantest,complementedbytheDunn’smultiplecomparison test. To compare genders in each moment we used the Mann---Whitneytest,consideringa5%significancelevel.
Videolaryngoscopydiagnoses,vocalsymptoms,and
correlationbetweenvocalfoldsparalysis/paresiswith
surgeryandhistologyresults
Theseparameterswerepresenteddescriptively.
Correlationbetweenhistopathologyandthetypeof
surgicalprocedure
Thechisquaretestwasusedtoevaluatethehomogeneityof thehistopathologyresultsandtypeofsurgery.Inaddition,in ordertoidentifydifferencesbetweentheproportions,the Goodman’stest forcontrastsbetweenandwithin multino-mialpopulationswasused,considering5%significancelevel. Thetest results arepresentedin thetablesby upperand lowercases. Differentcapital letters in the samecolumn indicatestatisticaldifference(p<0.05)betweenthe propor-tionsanalyzedin thecolumn.Differentlowercaseletters in the same line indicate statistical difference (p<0.05) betweentheproportionsanalyzedinthedifferent popula-tions.
Results
Ageandgender
223 patients underwent thyroidectomy during the study period,but only 151 met the inclusion criteria and com-pletedtheevaluations,130womenand21men;meanage 51.4years(12---75years). 45 40 35 30 25 20 15 10 5 0 Vocal symptoms 42(27%) 4(2.6%) 23(15%) 15(10%) 11(7%) pré 10 pós 20 pós 30 pós 40 pós Moments Number of patients
Table1 Median(minimumandmaximum)ofacousticparametersaccordingtomomentsandgender.
Parameters Gender Moments p-Value
Pre 1stpost 2ndpost 3rdpost
F0 F 203.9a (118.28---293.53) 193.3b (76.47---293.53) 191.7b (109.11---293.59) 196.0b (86.19---276.05) <0.00 M 124.5 (85.10---156.61) 116.7 (0.00---158.21) 110.2 (91.02---186.92) 116.3 (89.47---186.92) 0.302 p-Value <0.001 <0.001 <0.001 <0.001 Jitter(%) F 1.03 (0.27---6.54) 1.26 (0.32---18.31) 0.97 (0.25---10.54) 0.94 (0.18---5.22) 0.64 M 1.09 (0.40---2.68) 1.09 (0.27---4.09) 0.71 (0.32---3.29) 1.28 (0.32---6.25) 0.133 p-Value 0.56 0.257 0.144 0.124 PPQ F 0.59 (0.15---3.78) 0.70 (0.19---13.59) 0.53 (0.14---6.57) 0.54 (0.11---2.93) 0.497 M 0.63 (0.23---1.49) 0.63 (0.17---2.60) 0.43 (0.19---2.21) 0.74 (0.16---2.90) 0.133 p-value 0.507 0.341 0.218 0.111 Shimmer(%) F 3.24 (0.92---15.81) 3.34 (1.12---15.70) 3.28 (1.29---14.78) 3.10 (1.04---18.55) 0.211 M 3.65 (1.74---16.43) 4.48 (1.83---11.49) 4.36 (1.42---12.16) 4.36 (2.68---16.32) 0.184 p-Value 0.529 0.081 0.157 0.006 APQ F 2.36ab (0.70---9.57) 2.33a (0.86---12.02) 2.28ab (0.97---11.48) 2.12b (0.76---12.50) 0.039 M 3.04 (0.36---11.44) 3.30 (1.30---8.20) 3.30 (1.29---9.91) 3.07 (1.96---11.03) 0.183 p-Value 0.095 0.019 0.010 <0.001 NHR F 0.14 (0.05---0.32) 0.14 (0.07---0.50) 0.14 (0.07---0.40) 0.14 (0.07---0.48) 0.954 M 0.15 (0.07---0.23) 0.14 (0.08---0.27) 0.14 (0.08---0.25) 0.14 (0.09---0.44) 0.995 p-Value 0.096 0.342 0.440 0.325 SPI F 9.31 (1.16---63.08) 9.17 (1.38---54.75) 8.86 (1.94---56.64) 9.34 (1.94---56.64) 0.313 M 12.02 (5.89---31.71) 14.90 (5.36---42.08) 11.28 (3.06---40.67) 12.44 (0.59---30.62) 0.825 p-Value 0.041 0.021 0.103 0.183
Differentlowercaselettersindicatestatisticaldifference(p<0.05)betweenmoments,separatedbygender.
Table2 Videolaryngoscopyfindingsinthyroidectomypatientsindifferentmoments.
Videolaryngoscopy Moments
Pre n(%) 1stpostn(%) 2ndpostn(%) 3rdpostn(%) 4thpostn(%)
Normal 144(95.3) 100(66.2) 125(82.8) 134(88.7) 141(93.4) RLNparalysis 0(0.0) 32(21.2) 23(15.2) 17(11.3) 10(6.6) SLNparalysis 0(0.0) 2(1.3) 1(0.7) 0(0.0) 0(0.0) Projectiontohypopharynx 7(4.7) 0(0.0) 0(0.0) 0(0.0) 0(0.0) Edema/hematoma 0(0.0) 15(10.0) 2(1.3) 0(0.0) 0(0.0) Granuloma 0(0.0) 2(1.3) 0(0.0) 0(0.0) 0(0.0) Total 151(100.0) 151(100.0) 151(100.0) 151(100.0) 151(100.0)
Figure2 Largegoiterinpatientswithhoarsenessand respi-ratorydistress.
Vocalsymptoms
Therewasapredominanceofthevocalsymptomsinthefirst postoperativeperiod(42patients,27%).Therewasagradual decreaseinsymptomsatsubsequentmoments(Fig.1).
Acousticvocalanalysis
Table1depictstheresultsofacousticvoiceanalysis.The val-uesoff0decreasedconsiderablyinthethreepostoperative moments.Thesechangesaremostevidentinwomen.APQ valuesalsodecreasedinthethreepostoperativemoments inwomen.
Videolaryngoscopy
ThevideolaryngoscopicfindingsaredepictedinTable2.Most ofthepatientshadnormalvideolaryngoscopyinthe preop-erativeperiod.Insevenpatientswithverylargegoiterthe endoscopicexamsidentifiedtheprojectionofthegoiterin thehypopharynx(Figs.2and3).Thesechangesdisappeared aftersurgery.
Vocal folds paresis/paralysis (32 RLN injury and 2 SLN injury) were diagnosed in 34 patients in the 1st post. Of those,only ten (6.6%) remained withparalysis in the 4th postoperative evaluation. In only one case RLN paralysis was bilateral. RLN paralysis occurred on the left side in 12 patients, and on the right in 20 patients. In both SLN paresis/paralysisthe affectedsidewastheright andboth recoveredcompletely.
Hematomas(Fig.4)andpost-intubationgranulomaswere identifiedin15and2patientsinthe1stpostoperative eval-uation,respectively.Howevernoneofthesechangeswere observedafterthe3rdpost.
Histopathologyresultandtypeofsurgical procedure
TheTable3shows thecorrelationbetweenhistopathology andtypeofsurgery.Totalthyroidectomywithandwithout
Figure3 Hypopharyngealprojectionoflargegoiter (ARROW).
Figure4 Laryngealhematoma.
lymphnode dissection wasperformed in 111 patients, 65 withthyroidcancer(58.5%).
Relationshipbetweenthetypeofsurgeryand vocalfoldparalysis/paresisinthe1stpostoperative evaluation
Therelationshipbetweenthetypeofsurgeryandthe occur-renceofparalysis/paresisisdepictedinTable4.Amongthe 34patientswithvocalfoldparalysis,27(79.4%)had under-gonemajorsurgicalprocedures.
Relationshipbetweenhistopathologyandvocal foldparalysis/paresisinthe1stpostoperative evaluation
Therelationshipbetweenthehistopathologydiagnosisand theoccurrenceofparalysis/paresisis depictedinTable5. Among the 34 patients with vocal fold paralysis, 21 had thyroid cancer (61.8%) and 15 (38.2%) had benign
goi-Table3 Correlationbetweenhistopathologyandtypeofsurgeryprocedure.
Typeofsurgeryn(%) Histopathologyn(%) Total
Colloidgoiter Thyroiditis Cancer
Lobectomywithisthmusectomy(LI) 33(82.5) 5(12.5) 2(5.0) 40(100.0)
Totalthyroidectomy(TT) 43(48.9) 3(3.4) 42(47.7) 88(100.0)
Thyroidectomy+lymphnodedissection(TT+LND) 0(0.0) 0(0.0) 23(100.0) 23(100.0)
Total 76(50.3) 8(5.3) 67(44.4) 151(100.0)
Totalthyroidectomy+lymphnodedissectionwasnotconsideredsinceitwaspertinentonlyforcancer.
Table 4 Correlation between the type of surgical procedure and vocal folds paralysis/paresis on the 1st postoperative evaluation.
Patientswithparalysis/paresis Typesofsurgery
LIn(%) TTn(%) TT+LNDn(%) Totaln(%)
RLN 6(17.6) 17(50.0) 9(26.6) 32(94.2)
SLN 1(2.9) 0(0.0) 1(2.9) 2(5.8)
Total 7(20.6) 17(50.0) 10(29.4) 34(100.0)
LI,lobectomy+isthmusectomy;TT,totalthyroidectomy;TT+LND,totalthyroidectomy+lymphnodedissection;RLN,recurrentlaryngeal nerve;SLN,superiorlaryngealnerve.
Table5 Correlationbetweenhistologyandvocalcordsparalysis/paresisinthe1stpost.
Patientswithparesis/paralysis Histology Total
Goiter Thyroiditis Carcinoma
RLN 12(35.3) 0(0.0) 20(58.9) 32(94.2)
SLN 1(2.9) 0(0.0) 1(2.9) 2(5.8)
Total 13(38.2) 0(0.0) 21(61.8) 34(100.0)
RLN,recurrentlaryngealnerve;SLN,superiorlaryngealnerve.
ters, seven of which were giant and extended into the hypopharynx.
Discussion
Inthisstudythesymptomsweremoreprevalentinwomen inaratiocloseto6:1,asdemonstratedbyotherauthors,1,12
andjustifiedby thehigherincidenceof thyroiddiseasein women.
Thedelicateinnervation ofthethyroidglandmaintains anintimaterelationship withthestructuresofthelarynx. Thus,vocalsymptomsarefrequentafterthyroidectomy,and mostofthetimetransient.1Inthisstudy,vocalsymptoms
were reported by 42 patients (28%) in the 1st postop-erative evaluation, decreasing considerably subsequently. Theseresultscanbeattributedtolaryngealdisorders diag-nosedbyvideolaryngoscopyintheimmediatepostoperative period, such as paralysis, hematomas, and granulo-mas, most with remission in subsequent postoperative evaluations.
Someauthorshadreportedhigherincidenceofvoice dis-ordersin thepostoperative period of thyroidectomy than thosepresentedin thecurrent series.Soyluetal.5
evalu-atedthe vocal qualityof 48 thyroidectomy patients(n=8
lobectomy; n=40 total thyroidectomy) in three moments (preoperatively, 2nd postoperatively and after 3months). Theauthorsreportedvocalchangesin37.5%ofpatientsin theearlypostoperativeperiodthatpersistedafter3months in14.6%.F0wastheonlyacousticparameterthatremained alteredafter 3months. Inthe early postoperativeperiod, changesinf0weremoresignificantinpatientssubmittedto totalthyroidectomy.
Page et al.13 conducted a subjective voice analysis in
395 thyroidectomy patients (n=340 multinodular goiter; n=25 Graves’ disease; n=20 thyroid cancer). The voices were classified as: hoarse, low or weak pitch and voice fatigue.Patients whohadinferior laryngeal nerve paraly-siswereexcluded.Theauthorsidentified87patients(21%) withabnormalvoiceatthepreoperativeevaluationsand151 patients (49%)hadvoiceimpairment aftersurgery.Out of the87patientswhohadabnormalvoicesatthepreoperative evaluation,onlyeightpatientskeptanimpairedvoiceafter oneyear.Amongthepossiblecauses,theauthorshighlight the modifications in the resonator channel caused by the cervicalbulkygoiterextendingtotheretropharyngealspace asregisteredbyusduringvideolaryngoscopicexams.Ofthe 151patientswithabnormalpostoperativevoice,46% recov-eredwithinonemonthandafteroneyear, only5patients (3%)stillhadabnormalvoice.
Park et al.14 analyzed the voice of 217 patients who
underwent thyroidectomy in the pre and postoperative moments (2weeks, and 3, 6, and 12months). Significant decreasedpitchwereevidentin93(42.85%)patientsafter surgery, especiallyin thefirst 6monthsafter surgery, and only 18.4% of patients had lower-pitched voices oneyear aftersurgery. The voice changesof patients submittedto totalthyroidectomyweresignificantlyhigherthanthosewho underwentlobectomyat 2week aftersurgery,but didnot differatthe3,6,and12monthfollow-ups.
Among the various causes of post thyroidectomy dys-phonia the most important are endotracheal intubation, manipulation,surgicalstretchingandfixationofthecervical muscles,laryngealnervesandcricothyroidmuscleinjuries. Functional dysphonia can occur even without injuries to the laryngeal nerves. Maeda et al.8 evaluatedthe voices
of110 patientsafterTTwithnonervedamageandfound decreased Maximum PhonationTimeand f0, andincrease in the other acoustic parameters, especially in patients with greater surgical manipulation. Pedro Netto et al.4
evaluated 100 patients after partial (n=42) or total thy-roidectomy(n=58)andfoundvocalchangesin29.7%withno paralysis,representingfunctionaldysphonia.Paralysiswas diagnosedin 10 patients,of which only 5%complainedof dysphonia.
In an interesting systematic review conducted by Lang et al.15 included 896 patients after TT and identified
decreasedf0andincreasedshimmerandNHRinthe immedi-atepostoperativeperiod,especiallyinmen,confirmingthe resultsofmanystudies.
Among theabnormalities detected in the preoperative videolaryngoscopies of this study,we emphasize the pro-jectionof bulkier goitersinto thehypopharyngeal region, compressinglocalstructures(Figs.1and2),seen inseven patients. Page etal.13 point out that the hypopharyngeal
bulging caused by goiter modifies the resonator channel andchangesvocalquality,justifyingpartofthealterations recordedinsubjectivevoiceassessment.
Vocalfoldparalysiswasdiagnosedin34patients inthe 1stpostoperativeevaluation,32(21%)withRLNinjuryand 2 (1.3%) withSLN injury. In the 6month follow upexam, only10 ofthem presentedparalysis/paresis.These values indicate a high rate of nerve function recovery over the months, reducing the chances of permanent paralysis. In additiontothepreviouslymentionedcausesfor vocalfold paralysispostthyroidectomy,wemusthighlightthefactthat thesesurgerieswereperformed ina universityhospital,a place of teaching and trainingof residents,collaborating withthehighest percentages. Accordingtosome authors, RLNinjuriesrangefrom1%to13%.5,6,8,16ForSLN,therange
of valuesismore extensive,between 2%and 30%.3,4,6,10,17
Webelievethattheseresultscanbeattributedto difficul-tiesinthediagnosis ofSLNparalysis,demandingattention andexperienceoftheexaminerduringtheexam,sincethe mobilityofthevocalfoldispreservedandonlyitstension isdecreased.
The reported risk factors of laryngeal nerve damage in thyroidectomy are: goiter grater than 5cm, patients older than 50years,reoperation, malignant disease, type of surgery (partial or total thyroidectomy, with or with-outlymphnode dissection),andsurgeonexperience.7,16,17
Othercausesincludedirectdamage(mechanicalorthermal)
during surgery, perineural vascular injury, and compres-sion by hematoma. Many studies interrupt follow up at threemonths;however,ourresultsandotherauthors’have shownthatvocal symptomsandlaryngealparalysisgreatly reduceaftersixmonths.Itis,therefore,advisabletoextend thefollow-uptimebeforeproposingnewsurgeries.18---21For
ChristouandMathonnet7temporarydysphoniasecondaryto
RLNinjuryoccurin5---18%ofcases,andpermanent dyspho-niainonly1---3.5%. Theseauthorspoint outthatlessthan 0.5%paralyzesarebilateral,alsofoundinourstudy.
In this study, benign thyroid diseases accounted for approximately50%ofallcasesandcancerfor44%,the lat-ter requiring more extended surgical procedures (TT and TT+LND).Thesesurgeriesaccountedfor79%ofvocalfolds paralysis/paresis.Theseratesaresimilartostatistics pre-sentedbyotherauthors.3,4,6,14,16,18
Injuries to the RLN cause symptoms of vocal asthenia and low voice; however, SLN injuries may go unnoticed becausethevoicesymptomsaremorefrequent inwomen and voice professionals. Chun et al.6 evaluated 300
thy-roidectomy patients by videolaryngoscopy, vocal acoustic analysis and auditory-perceptual analysis. They identified 31 patients (10.3%) with postoperative RLN paralysis and 54(18%)withdifficultiesinsustainingthepitch.The voice quality questionnaires were more accurate in identifying abnormalvoices,correspondingto91.6%ofpatientsinthe postoperativeperiod,thisvocalassessmenttoolbeinghighly valuedbytheauthors.
Weemphasizetheimportanceofadoptingsimple meas-ures suchasstandardization of routinevideolaryngoscopy and vocal analysis before and after surgery, since they enableearlydiagnosisofvoicedisordersandmonitoringthe progressoflaryngeallesions,particularlyparalyzes.
Conclusions
Vocal symptoms were reported by 27.8% of our patients in the 1st postoperative evaluation after thyroidectomy, reducingto7%in6months.Intheacousticanalysisf0and APQweredecreased.Temporaryparalysisofthevocalfolds secondarytorecurrentlaryngealnervedamageoccurredin 21%ofthepatients,persistingafter6monthsinonly6.6%of cases.Temporaryparalysisconsequenttosuperiorlaryngeal nervedamageoccurredin1.3%,withcompleterecoveryin allcaseswithin6months.
Conflicts
of
interest
Theauthorsdeclarenoconflictsofinterest.
Acknowledgements
ToFapespforthefinancialsupport.
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