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Severe trismus due to bilateral coronoid process hyperplasia in growth hormone therapy patient: a case report

Sung-Tak Lee, In-Kyo Chung

Department of Oral and Maxillofacial Surgery, School of Dentistry, Pusan National University, Yangsan, Korea

Abstract (J Korean Assoc Oral Maxillofac Surg 2012;38:249-54)

Bilateral coronoid process hyperplasia is a rare condition characterized by an enlarged mandibular coronoid process. The painless progressive reduction of a mouth opening is caused by coronoid process impingement on the posterior aspect of the zygomatic bone. Hyperplasia of the bilateral coronoid process leads to the restriction of a mandibular opening consequent to the impingement of the enlarged coronoid process on the temporal surface of the zygomatic bone or with the medial surface of the zygomatic arch. The process has been diagnosed as developmental hyperplasia. Otherwise, the development of the coronoid process may be associated with growth hormone. This paper describes a case of trismus caused by coronoid hyperplasia in an idiopathic short-stature patient who received growth hormone therapy by somatropin injections.

Key words: Coronoid process hyperplasia, Trismus[paper submitted 2011. 9. 28 / revised 2011. 11. 2 / accepted 2011. 11. 18]

upliftontheupperpartofthezygomaticarchandmandibular

displacementtowardtheaffectedsideduringmouthopening.

Unilateralandbilateralcoronoidprocesshyperplasiamay

occurinallagegroups(average25)butrarelyinpeopleaged

10orunder.Moreover,mostpatientsweremale,butfemale

patientswererare.

As a treatmentmethod, coronoidectomycanachieve

meaningfulenhancementofmouthopening,but thereisa

needtocheckforfibrosiscausedbysurgeryorregrowthof

coronoidprocessforalongtime2.

This case reportdealswith apatientdiagnosedwith

idiopathicshortstature (ISS) in2008by theDepartment

ofPediatricsandadministeredgrowthhormone therapy

andwhose trismus-causedbybilateralcoronoidprocess

hyperplasia-wastreatedwithcoronoidectomy.

II. Case Report

OnApril4,2006,a12-year-oldmalepatientvisitedthe

DepartmentofPediatricDentistryandOrthodontics,Pusan

NationalUniversityHospitalKoreadue to thedelayed

eruptionofpermanentteethandfacialasymmetry.Thepatient

weighed34kg,andhewas135cmtall;hewasrelatively

smallcomparedwithotherchildreninhisage,andmanyof

histeethhadbirthdefects.Thepatienthadreceivedtreatment

I. Introduction

BilateralCoronoidProcessHyperplasiaisararecondition

characterizedbyanenlargedmandibularcoronoidprocess.

Continuouslyproliferatingcoronoidprocesscausestrismus

duetoimpingementonthetemporalsurfaceofthezygomatic

boneorthemedialsurfaceofthezygomaticarch.According

toIsbergetal.1,coronoidprocesshyperplasiais thecause

ofapproximately5%oftrismuspatients.Manyhypotheses

suggeststimulatingendocrine,increasedactivityoftemporal

muscle, injury,andheredityasthepossiblefactorscontri-

butingtocoronoidprocesshyperplasia,butthecausehasyet

tobeidentifiedclearly2.

Themostcommonclinical featureofcoronoidprocess

hyperplasiaispainlessandprogressivetrismus.Unilateral

coronoidprocesshyperplasiaiscommonlycombinedwith

facialasymmetryandsometimescombinedwithmobile

In-Kyo ChungDepartment of Oral and Maxillofacial Surgery, School of Dentistry, Pusan National University, 20, Geumo-ro, Mulgeum-eup, Yangsan 626-787, KoreaTEL: +82-55-360-5100 FAX: +82-55-360-5104E-mail: inkchung@pusan.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.2012.38.4.249

pISSN 2234-7550·eISSN 2234-5930

J Korean Assoc Oral Maxillofac Surg 2012;38:249-54

250

2008.(Fig.1)Moreover,hehadahard-end-feelonbothsides

whenopeninghismouthtotheleftandright.Thepanoramic

radiographic inspectionanddentalcone-beamcomputed

tomography(CT)(Pax-Zenith3D;Vatech,Hwaseong,Korea)

imagesshowedhyperplasiaonbothsidesofthemandibular

coronoidprocess.(Fig.2)Inparticular,thethreedimensional

(3D)imagesobtainedbyreorganizingthedentalcone-beam

CTimageswith3Danalysisprogram(Simplant;Materialise,

Leuven,Belgium)revealed that the leftcoronoidprocess

wasclosetothemedialsurfaceoftheleftzygomaticbone,

and that the inner sideof the left zygomaticbonewas

transformed.(Fig.3)Thepatient’sheightincreasedfrom143

cminJanuary2008whenthegrowthhormonetherapywas

startedto153cmwhenthepatientvisitedusinAugust2008

duetotrismus.Andincomparingpanoramicradiographs,

thepanoramicimagestakeninAugust2008showedamore

noticeablehyperplasiaintheleftcoronoidprocess.(Fig.4)

Thepatientkept receivinggrowthhormone therapyuntil

October2009,andhisheight increased from153cm to

167cminJuly2011.Themaximummouthopeninglevel

decreasedfrom15mminAugust2008to10mminJuly

2011.(Table1)

Therefore,basedonthepatient’smedicalhistory,clinical

examinations,andradiographicinspection,wedetermined

at theDepartmentofPediatricDentistryandOrthodontics

without trismus; inAugust2008whenhewas14,hewas

referredtoDepartmentofOralandMaxillofacialSurgeryby

theDepartmentofOrthodonticsduetofacialasymmetryand

trismus.Clinicalexaminationsrevealedfacialasymmetry,

mouthopening levelof15mm,anddisplacement to the

leftofthemandibleduringmouthopening;thepanoramic

photographsshowedleftcoronoidprocesshyperplasia.The

patientdidnothaveanyparticular injuryor infectionor

familyhistoryofsimilarsymptoms,buthewasdiagnosed

withISSinJanuary2008bytheDepartmentofPediatrics

inourhospitalandadministeredgrowthhormonetherapy

usingEutropin (RecombinantHumanGrowthHormone

[somatropin],LGEutropinInj.;LGLifeSciences,Seoul,

Korea) injection.OurDepartmentplanned toencourage

activemouthopeningmovement,observehisstatusduring

thegrowthperiod,andperformsurgery,butthepatientdid

notvisitagain.Later,thepatientvisitedagaininJuly2011

whenhewas17duetorestrictionofmouthopening.Clinical

examinationsrevealedfacialasymmetry,displacementtothe

leftofthemandibleduringmouthopening,andmaximum

mouthopening levelof10mm,decreasingcompared to

Fig. 1. Preoperative clinical photograph. A. Lateral photo view. B. Frontal photoview. C. Preoperaive maximum mouth opening mesurement was 10 mm.Sung-Tak Lee et al: Severe trismus due to bilateral coronoid process hyperplasia in growth hormone therapy patient: a case report. J Korean Assoc Oral Maxillofac Surg 2012

A

B C

Fig. 2. Preoperative radiologic view show both hyperplasic coronoid preocess. A. Panoramic view. B. Dental conbeam com-puted tomography (CT) view (mandible right). C. Dental conbeam CT view (mandible left).Sung-Tak Lee et al: Severe trismus due to bilateral coronoid process hyperplasia in growth hormone therapy patient: a case report. J Korean Assoc Oral Maxillofac Surg 2012

Severe trismus due to bilateral coronoid process hyperplasia in growth hormone therapy patient: a case report

251

thatthegrowthhormonetherapycausedhyperplasiainthe

bilateralmandibularcoronoidprocessanddiagnosed the

transformationoftheleftcoronoidprocessandimpingement

on the innersideof thezygomaticboneas thecauseof

trismus.Assuch,weplannedtoperformcoronoidectomyon

bothsidesofthemandibleundergeneralanesthesiainAugust

2011.

General anesthesiawasperformedwithnasotracheal

intubationusingfiberopticscopebecause itwashard to

executenasotrachealintubationusingheadscopeduetothe

insufficientmouthopeninglevel.Consideringthediagnostic

process,leftcoronoidectomywascarriedoutfirstduetothe

hard-end-feelingand transformationofcoronoidprocess.

At first, leftcoronoidectomywasperformed through the

mouth;however,dueto insufficientmouthopeninglevel,

thesubmandibularapproachwastaken.After thesurgery,

themaximummouthopening level increasedby37mm.

Afterward, rightcoronoidectomywasdone through the

intraoralapproach.Afterthesurgery,themaximummouth

Fig. 3. Three dimensional simplant image. A. The image show morphological abnomality of left zygomatic bone. B. Left coronoid process extend above the zygomatic bone and impinge on the posterior surface of the zygomatic bone. C. Right coronoid pro-cess have just hyperplastic morphology.Sung-Tak Lee et al: Severe trismus due to bilateral coronoid process hyperplasia in growth hormone therapy patient: a case report. J Korean Assoc Oral Maxillofac Surg 2012

Fig. 4. Serial panoramic view. A. April 2006. B. August 2007. C. August 2008 after growth hormone therapy (January 2008). D. July 2011.Sung-Tak Lee et al: Severe trismus due to bilateral coronoid process hyperplasia in growth hormone therapy patient: a case report. J Korean Assoc Oral Maxillofac Surg 2012

A B C D

Table 1. Trismus according to growth hormone therapy

Date(yy/mm/dd)Growth

hormonetherapyHeight(cm) Mouthopening

2006/42008/1/12008/1/212008/2/182008/4/142008/7/22008/7/302008/8/262008/10/212009/7/312009/10/52011/8/8

××

Eutropin21vialEutropin42vialEutropin75vialEutropin80vialEutropin21vialEutropin42vialEutropin42vialEutropin45vialEutropin45vial

×

135143143144148151152154156160161167

W.N.LW.N.LW.N.LW.N.LW.N.LW.N.LW.N.L15mm

---

10mm

(W.N.L:withinnormallength)Sung-Tak Lee et al: Severe trismus due to bilateral coronoid process hyperplasia in growth hormone therapy patient: a case report. J Korean Assoc Oral Maxillofac Surg 2012

J Korean Assoc Oral Maxillofac Surg 2012;38:249-54

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opening level increasedby53mm.(Fig.5)Extracted left

coronoidprocesshadhyperplasiahorizontally;cartilage

proliferating2mmthickwasnotedat theend.Extracted

rightcoronoidprocesswasnottransformed,butithadoverall

hyperplasia.(Fig.6)

Onemonthafterthesurgerywhenthepatientvisitedagain,

themaximumvoluntarymouthopeninglevelwas40mm

withoutedema,pain,andneuraldamage.(Fig.7)

III. Discussion

Generally,trismusmeansallproblemsinmouthopening.

Thenormalmouthopening level is40-60mm,basedon

Fig. 5. A. Perioperative mouth opening was 10 mm. B. Mouth opening after left coronoidectomy was 40 mm. C. Mouth opening after both coronoidectomy was 53 mm.Sung-Tak Lee et al: Severe trismus due to bilateral coronoid process hyperplasia in growth hormone therapy patient: a case report. J Korean Assoc Oral Maxillofac Surg 2012

Fig. 6. A. Resected Lt. coronoid pro-cess. B. Lt. coronoid cartiladge from coro noid process tip. C. Comparison re sected Lt. coronoid process with re-sected Rt. coronoid process. (Lt.: left, Rt.: right)Sung-Tak Lee et al: Severe trismus due to bilateral coronoid process hyperplasia in growth hormone therapy patient: a case report. J Korean Assoc Oral Maxillofac Surg 2012

Fig. 7. A. One month mouth opening after surgery. B. Post ope-rative panoramic view. Sung-Tak Lee et al: Severe trismus due to bilateral coronoid process hyperplasia in growth hormone therapy patient: a case report. J Korean Assoc Oral Maxillofac Surg 2012

Severe trismus due to bilateral coronoid process hyperplasia in growth hormone therapy patient: a case report

253

growthhormone stimulatesoverall bones andmuscles

particularlythegrowthofcartilagethroughtheinsulin-like

growthfactorI(IGF-I).Pirinenetal.14alsostatedthat the

growthofbasiscraniumandmandibularcartilageisaffected

bybothexcessandinsufficiencyof thegrowthhormone.

Considering these researchstudies, insufficientvertical

growthinthemandibularcondyleandposteriorskullbase

inchargeofcartilagegrowthcausessmallmandibleand

shortposteriorfacialheight,eruptionofdentitionincrease,

lowerfacialheight,andmandiblerotatedclockwise;hence

theuniquecraniofacialshapeofshort-staturepatients.The

patientinthiscasealsohadthefacialshapeofshort-stature

patients.

Agrowthhormoneagent(Somatropin)meansasynthetic

humangrowthhormone.Since1958whenRaben15injected

ahumangrowthhormoneextractedfromthepituitarygland

ofacadaverintoapatientwithgrowthhormonedeficiency

for thefirst timeandreporteditseffects, ithasbeenused

for40years.Thegrowthhormonestimulates thegrowth

ofbonesandmusclesaswellasthecompositionofIGF-I

in liver.Therefore, the injectionofgrowthhormonecan

resolvetheproblemofinsufficienthormoneaswellaslow

sensitivitytogrowthhormone,therebyincreasingthefinal

heightbystimulatinggrowthduringchildhoodandtriggering

thegrowthofspheno-occipitalsynchondrosisinbasiscranii

andmandibularcondyle.Actually,Chungetal.16reported

that2yearsofgrowthhormonetherapyforchildrenwith

shortstatureledtotheincreaseofposteriorfacialheightand

growthofthemandible.

Thoughthereisnoothercasereportontherelationship

between thegrowthof themandibularcoronoidprocess

andgrowthhormoneaswellasconsequentcomplications

suchastrismus,thiscasereportconcludedthatthecoronoid

processoriginatingwithcartilagemayhavehyperplasiaof

themandibularcoronoidprocessduetothegrowthhormone

agentandcontractionof temporalmuscle.Nonetheless,

moreresearchontheevidentreasonisneededtoidentifythe

mechanismofcoronoidprocesshyperplasia.

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