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Congenital syngnathia: a case report

Chul-Hwan Kim, Moon-Young Kim

Department of Oral and Maxillofacial Surgery, College of Dentistry, Dankook University, Cheonan, Korea

Abstract (J Korean Assoc Oral Maxillofac Surg 2012;38:171-6)

Congenital syngnathia refers to the fusion of bony tissues, a rare disorder with only 41 cases reported in the international literature from 1936 to 2009. The occurrence of syngnathia without any other associated systemic disease or congenital anomaly is extremely rare. This report presents a case of congenital syngnathia with unilateral maxillomandibular bony adhesion without any other oral or maxillofacial anomaly. No recommended protocol for surgery exists due to the rarity of the disorder. There is a very low survival rate for the few patients who have forgone surgical management. This case describes a 74-year-old female patient who was suffering from limitation of mouth opening and was subsequently diagnosed with congenital syngnathia. The surgical staff performed separation surgery and reconstructed the malformed oral vestibule and cheek using the radial forearm free flap operation.

Key words: Jaw abnormalities, Synostosis, Congenital[paper submitted 2011. 8. 19 / revised 2011. 10. 10 / accepted 2011. 10. 12]

treatmentoutcomehavingnocomplicationand refusion

togetherwithareviewofliterature.

II. Case Report

A74-year-old femalepatientwithchiefcomplaintof

fusionoftheleftjawscametotheDepartmentofOraland

I. Introduction

Congenitalfusionofthejawsisaconditionthatcannot

openthemouthatbirthandthebonyfusioncomposedof

oralmucosaormaxillaandmandible.Casesofcongenital

synechiaewithsoft tissuehavebeengenerallyreportedin

literature,butcongenitalsyngnathiawithhardtissueisrare.

Itwasfirst reported in1936,withonly41casesreported

until20091.Inparticular,congenitalsyngnathiathatisnot

associatedwithsystemicsyndromeormaxillofacialdefect

is rarely found in literature.Sincecongenitalsyngnathia

causes,dyspnea,difficulty inoral feeding,andabnormal

growthof the jawsand face,early surgical treatment is

necessary.However,thatnostandardtreatmentforcongenital

syngnathiaisestablishedbecausetheprevalencerateislow

andfewpatients livewithoutsurgical treatment.For the

patientdiagnosedwithcongenitalsyngnathiaas featured

inthisreport,weperformedseparativesurgeryandradial

forearmfreeflapoperation.Wepresentareportonthegood

Chul-Hwan KimDepartment of Oral and Maxillofacial Surgery, School of Dentistry, Dankook University, 119 Dan-daero, Dongnam-gu, Cheonan 330-714, KoreaTEL: +82-41-550-1996 FAX: +82-41-551-8988E-mail: kimchoms@dankook.ac.kr

This is an open-access article distributed under the terms of the Creative Commons Attribution Non-Commercial License (http://creativecommons.org/licenses/by-nc/3.0/), which permits unrestricted non-commercial use, distribution, and reproduction in any medium, provided the original work is properly cited.

CC

CASE REPORThttp://dx.doi.org/10.5125/jkaoms.2012.38.3.171

pISSN 2234-7550·eISSN 2234-5930

Fig. 1. 74-year-old woman with facial asymmetry due to left mandibular hypoplasia resulting in the fusion of the left maxillo-mandibular alveolar ridge.Chul-Hwan Kim et al: Congenital syngnathia: a case report. J Korean Assoc Oral Maxil-lofac Surg 2012

J Korean Assoc Oral Maxillofac Surg 2012;38:171-6

172

years.Shehasnofamilyhistoryofsuchfusion.Theclinical

findingsrevealedfusioninthegingivaareaequivalenttothe

leftedentulousalveolarridgeofthemaxillaandmandible

andnobuccalvestibuleasaresultofperfectfusioninthe

buccalgingivalarea.(Fig.2)Therewasnotoothintheoral

cavity,andshehadneverexperiencedtoothextraction.There

was facialasymmetrydue to leftmandibulardeficiency

causedbysyngnathia.Themaximummouthopeningshowed

0mmin thesymphysisof the jaws,andanymandibular

movementinalldirectionswasimpossible.Thepanoramic

radiographshowedfusionoftheleftedentulousalveolarridge

(Fig.3),andthefacial3dimensionimageacquiredthrough

acomputedtomographyscanwasusedtoobservethebony

fusionof the leftedentulousalveolarridge.(Fig.4)There

wasneitheradhesionofboth temporomandibular joints

(TMJs)norcoronoidprocesshyperplasia.(Fig.5)Moreover,

the imagefromthebonescan(99mTc-MDP;SymbiaE,

Siemens,Germany)revealeda findingofhotspot in the

MaxillofacialSurgery,DankookUniversityHospitalon9th,

March,2011.(Fig.1)Thepatienthasneitheropenedher

mouthnorchewedsincebirth, takinginliquiddietfor74

Fig. 2. Adhesion of the left commissural and retrocommissural oral cheek to the fused arches on the left side, which continued posteriorly as complete adhesion of the buccal mucosa to the slopes of the upper and lower arches, resulting in the absence of the buccal vestibule.Chul-Hwan Kim et al: Congenital syngnathia: a case report. J Korean Assoc Oral Maxil-lofac Surg 2012

Fig. 3. Panoramic view showing left mandibular ramus hypoplasia resulting in the unilateral bony fusion of the left maxillary-mandibular alveolar ridges.Chul-Hwan Kim et al: Congenital syngnathia: a case report. J Korean Assoc Oral Maxil-lofac Surg 2012

Fig. 5. Computerized 3 dimension recon struction of the skull. A. There was neither temporomandibular joint (TMJ) ankylosis nor coronoid process hyper plasia in the right skull. B. There was no TMJ ankylosis, but coronoid process hyperplasia was noted on the left side.Chul-Hwan Kim et al: Congenital syngnathia: a case report. J Korean Assoc Oral Maxillofac Surg 2012

Fig. 4. A computerized 3 dimension reconstruction of the skull showed the bony fusion of the alveolar crest of the maxilla and mandible.Chul-Hwan Kim et al: Congenital syngnathia: a case report. J Korean Assoc Oral Maxil-lofac Surg 2012

Congenital syngnathia: a case report

173

thesurgery.(Figs.7-9)Before thesurgery,weconducted

theAllen's test forbloodcirculationcompatibility and

microvascularanastomosistoconnecttheradialarteryand

venacomitantsintheradialforearmfreeflaptothebranches

of the facialarteryand internal jugularvein.Asa result

ofcontinuousmouthopeningmovement7daysafter the

surgery,themaximummouthopeningwas45mmfromthe

symphysisofthejaws.Tocontrolthesizeofthetransplanted

flap,flapde-bulkingoperationwasperformedon8th,Julyof

affectedalveolarbone.(Fig.6)

OnMarch16ofthesameyear,sinceitwasimpossibleto

performnormalintubationforgeneralanesthesia,fiber-optic

intubationusingendoscopywasdonetoperformseparative

surgeryandreconstructedtherightbuccalmucosaandoral

vestibule.Suchreconstructivesurgery includedextension

of lipsplit incision,separativesurgeryof themaxillaand

mandibleaftercollar incision,detachmentof theaffected

temporalismuscle,coronoidectomyandradialforearmfree

flapoperation to lead tomouthopeningmovementafter

Fig. 6. The bone scan (99mTc-MDP) revealed a hot spot in the left maxillo-mandibular bony fusion area.Chul-Hwan Kim et al: Congenital syngnathia: a case report. J Korean Assoc Oral Maxil-lofac Surg 2012

Fig. 7. Surgical incision. The incision line was lip-split and extended to apron flap incision.Chul-Hwan Kim et al: Congenital syngnathia: a case report. J Korean Assoc Oral Maxil-lofac Surg 2012

Fig. 8. The maxillo-mandibular fusion area is separated by a saw, and left coronoidectomy was done to favor mouth opening training.Chul-Hwan Kim et al: Congenital syngnathia: a case report. J Korean Assoc Oral Maxil-lofac Surg 2012

Fig. 9. Radial forearm free flap was inserted for the reconstruction of the buccal cheek mucosa.Chul-Hwan Kim et al: Congenital syngnathia: a case report. J Korean Assoc Oral Maxil-lofac Surg 2012

J Korean Assoc Oral Maxillofac Surg 2012;38:171-6

174

calledsynechiae,whereasfusionbyosseoustissueiscalled

syngnathia.Synechiaehasbeen reportedextensively in

literatures,anditstreatmentissimpleratherthancomplicated.

However,syngnathiaisararerdeformitythanfusionbysoft

tissue;unilateralbonyfusioninthejawshasbeenreported

evenmorerarely1.Mostcasesofcongenitalsyngnathiaare

additionallyaccompaniedbycongenitaldefects suchas

cleftlip,cleftpalate,microglossia,micrognathism,andTMJ

disease1.(Table1)Inparticular,cleftpalateismostcommon.

Atleast41casesofcongenitalsyngnathiahadbeenreported

until2009since thefirstcasewasreportedbyBurket2 in

1936,whereasonly18casesofcongenitalsyngnathiawithno

additionalcongenitaldefectorsyndromehadbeenreported

until20091.Somescholarsclassifiedthepatientconditions,

suchastheclassificationofDawsonetal.3,andclassification

ofLasteretal.4asamodifiedclassification.(Tables2,3)The

patientinthiscaseisType1undertheclassificationofDawson

etal.3andType1aundertheclassificationofLasteretal.4.

Theetiologicfactorofcongenitalbonysyngnathiahasyet

thesameyearunderoralintubationandgeneralanesthesia.

(Fig.10)Now,6monthsafter thesurgery, themaximum

openingwas45mmfromthesymphysisofthejaws.

III. Discussion

Thefusiondefectofthemaxilla/mandibleinthejawbones

ororalmucosaisanextremelyraremaxillofacialdeformity.

Suchdeformity iscalledvariousmedical termsincluding

congenitalfusionofthejawsorgums,zygomaticomandibular

fusion, intraoralband, intra-alveolarsynechiae,congenital

bony syngnathia, andmandibulomaxillary synostosis1.

Fusionby thesoft tissuesof themaxillaandmandible is

Table 1. Congenital anomalies associated with syngnathia

CleftlipCleftpalateCleftmandibleObliquefacialcleftMandibularhypoplasiaHemifacialmicrosomiaGlossopalatineankylosisMicroglossiaCongenitalamputationofarmsandlegsColobomaScoliosisHorner’ssyndromeVanderwoudesyndrome

Chul-Hwan Kim et al: Congenital syngnathia: a case report. J Korean Assoc Oral Maxil-lofac Surg 2012

Table 2. Classification of Dawson et al.3

Type1Type2aType2b

SimplesyngnathiaComplexsyngnathiaComplexsyngnathia

NootheranomaliesintheheadandneckSyngnathiacoexistentwithaglossiaSyngnathiacoexistentwithagenesisorhypoplasiaofproximalmandible

Chul-Hwan Kim et al: Congenital syngnathia: a case report. J Korean Assoc Oral Maxillofac Surg 2012

Table 3. Classification of Laster et al.4

Type1a

Type1a

Type2a

Type2b

Simpleanteriorsyngnathia

Complexanteriorsyngnathia

Simplezygomatico-mandibularsyngnathia

Complexzygomatico-mandibularsyngnathia

Bonyfusionofthealveolarridgeonlyandwithoutothercongenitaldeformityintheheadandneck

Bonyfusionof thealveolar ridgesonlyandassociatedwithothercongenitaldeformityintheheadandneck

Bonyfusionofthemandibletothezygomaticcomplexcausingonlymandibularmicrognathia

Bonyfusionofthemandibletothezygomaticcomplexandassociatedwithcleftsortemporomandibularjointankylosis

Chul-Hwan Kim et al: Congenital syngnathia: a case report. J Korean Assoc Oral Maxillofac Surg 2012

Fig. 10. Debulking procedure for the reduction of volume of excessive radial forearm free flap during the second operation. Mouth opening of 45 mm was achieved.Chul-Hwan Kim et al: Congenital syngnathia: a case report. J Korean Assoc Oral Maxil-lofac Surg 2012

Congenital syngnathia: a case report

175

wasdonesimultaneouslywiththeseparationofthemaxilla

and themandible.Profusebleedingoccurredduring the

operationinthebloodvesselsaroundthebaseoftheskull,

andthecausewasthoughttobevenousruptureduetothe

excessiveextensionoftheveinconnectedtothebaseofthe

skullwhen themouthwasopenedafter theseparationof

themandibularbone.Therefore,notifyingthepatientand

caregiverwellaheadofthesurgeryofthepossibilityofblood

transfusionagainstexcessivebleedingduringtheoperationis

recommended,includingperformingmouthopeningcarefully

topreventexcessivebleedingduringtheoperation.Toavoid

recurrencecausedbytherefusionofsofttissue,ankylosisof

theTMJ,andatrophyofmasticatorymuscleafterthesurgery,

mouthopeningtrainingwasdone7daysaftertheoperation.

Choietal.14maintained in their research that,asmouth

openingcanbereducedduetoatrophyof themasticatory

muscleafter the surgerydespiteenoughbuccalmucosa

whenusingradialforearmfreeflap,continuousmonitoring

ofmouthopeningandphysical treatmentarerequired.In

thiscase, thepatientshowedsuccessfulopening4months

after thesurgery;however,sincethesizeoffreeflapwas

somewhatexcessive,secondaryflapreductionoperationwas

performed.

Inconclusion,wecouldsecureenoughmouthopeningfor

thepatientwithcongenitalsyngnathiaanddrawaneffective

resultwithoutanyrefusionafterthesurgery.However,case

reportsonpatientsundergoingtheradialforearmfreeflap

operationarerare,andthereisashortageofdiscussionon

comparativestudyofcasesusingotheroperationsother

thantheradialforearmfreeflapoperation.Therefore,more

researchon the refusionpatternandmaintainingmouth

openingincaseoftheradialforearmfreeflapoperationare

deemednecessary.

IV. Conclusion

Totreatapatientwithcongenitalsyngnathiaeffectively,

it is important tosecure theairwayof thepatient,ensure

propernutrition,andsecureenoughmouthopeningwithno

recurrencepattern.Therefore,itisrecommendedtoprevent

anyrecurrenceaftersurgerybyusingtheproperoperation,

includingmaintainingthemouthopeningtopreventankylosis

oftheTMJthroughcontinuousphysicaltherapy.

Forapatientwithcongenitalsyngnathia,wesuccessfully

performedseparativesurgeryandradialforearmfreeflap

andpresentedareportonthesatisfactoryresultwithoutany

complicationsandrecurrence.

toberevealed,butthefollowingcausesareassumed:long-

termsurvivalofbuccopharyngealmembrane,amnioticband

syndrome, incest,drugsduringpregnancy, abnormality

offetalstapedialartery,earlylossofneuralcrestcell,and

injury5-9.AccordingtoNanda,syngnathiaoccurredwithcleft

palate in therabbit injectedwithvitaminA10.Humphrey

maintained that, since theelevationofpalatal shelves is

delayedduetothereducedswallowingreflexofafetusin

theearlystagesofpregnancy, thecontactofpharyngeal

membraneandglossalmembrane in apalate results in

syngnathiatogetherwithcleftpalate11.Lastermaintainedthat

suchdeformityisrelatedtothetimeandperiodofexternal

damageandthatexternaldamageoccurredafterweek12of

pregnancydoesnotcausecleftpalate,micrognathism,fusion

ofzygomaticboneandupperjawboneorfusionofcortical

bones4.Inthepresentcase,therewasnoankylosisofboth

TMJs,buttheovergrowthofleftcoronoidprocesswasnoted.

Nofusionof the leftcoronoidprocess,zygomaticbone,

andupper jawwasobserved,however.Asaresultof left

mandibulardeficiencyduetosyngnathia,theleftmandibular

branchwas1cmshorter thantherightbranch,andfacial

asymmetrywasobserved.

Theimportantpoint in treatingthisdisease is tosecure

theairwayandfeedingthroughnasogastrictubeinsertionat

birth,andthenremovethefusionareabysurgicalprocedure,

administeringactivephysicaltreatmenttopreventrecurrence

inthefuture.Ifpossible,earlysurgeryisrecommendedto

avoid theankylosisofbothTMJsandpreventsecondary

developmentalmaxillofacialdeformitythatmaybecaused

bysyngnathia.

In literatureon the treatmentofcongenitalsyngnathia,

manyauthorsusedapproachessuchastemporo-preauricular

approach,submentalapproach, intraoralapproach3,12,and

suggested interpositional flapusing temporalismuscleor

buccalmucosa,insertionofanimplantsuchassilasticsheets

betweenseparatedsoft tissues toprevent recurrence3,or

physicaltreatmentusingoralapplianceafterthesurgery12,13.

Fusion reportedly recurred inmost casesdespite such

efforts3,8.Recently,Choietal.14reportedacaseofusingradial

forearmfree flap toprevent refusionandsecureproper

mouthopeningafter surgery in theacquiredsyngnathia.

However, thedecreaseofmouthopeningaftersurgeryled

toTMJsurgeryandlipsurgeryusingtemporalismusclein

thesecondarysurgery14.Inthepresentcase,topreventthe

decreaseofmouthopeningafterthesurgery,detachmentof

theaffected temporalismuscleandcoronoidectomywere

additionallyperformed,andradialforearmfreeflapoperation

J Korean Assoc Oral Maxillofac Surg 2012;38:171-6

176

mandibularbonyfusionwithamandibularcleftandabifidtongue.BrJPlastSurg1997;50:139-41.

8. KamataS,SatohK,UemuraT,OnizukaT.Congenitalbilateralzygomatico-mandibularfusionwithmandibularhypoplasia.BrJPlastSurg1996;49:251-3.

9. GoodacreTE,WallaceAF.Congenitalalveolarfusion.BrJPlastSurg1990;43:203-9.

10. NandaR.Maxillomandibularankylosisandcleftpalate in ratembryos.JDentRes1970;49:1086-90.

11. HumphreyT.Therelationbetweenhumanfetalmouthopeningreflexesandclosureofthepalate.AmJAnat1969;125:317-44.

12. SubramanianB,AgrawalK,PandaK.Congenital fusionofthe jaws:amanagementprotocol. Int JOralMaxillofacSurg2010;39:925-9.

13. AgrawalK,ChandraSS,SreekumarNS.Congenitalbilateralinter-maxillarybonyfusion.AnnPlastSurg1993;30:163-6.

14. Choi JY,MinCG,MyoungH,HwangSJ,KimMJ,Lee JH.Acquiredsyngnathia.BrJOralMaxillofacSurg2004;42:448-50.

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