A.Ben Abdallah, K.Mrad Dali, M.Omezzine*, I.Chaabani, N.Mama, K.Kadri, H.Moulahi, K.TliliRadiology service, Sahloul Hospital*MaxilloFacial surgery service, Sahloul Hospital

HN14

INTRODUCTION Otomandibular dysplasia is a condition in

which the lower half of one side of the face is underdeveloped and does not grow normally.

It is sometimes also referred to as hemifacial microsomia, first and second brachial arch syndrome, oral-mandibular-auricular syndrome, lateral facial dysplasia,

or otomandibular dysostosis. The syndrome varies in severity, but always

includes the underdevelopment of the ear and the mandible. This is the second most common facial birth defect after clefts

OBJECTIVES

To illustrate the imaging aspects of oto-mandibular dysplasia through a study of 10 cases.

To highlight the contribution of imaging in the preoperative assessment of the lesions of oto-mandibular dysplasia.

PATIENTS AND METHODS Retrospective study about 10 pediatric

cases 7 boys and 3 girls, Aged from 5 months to 10 years old. All patients underwent a computed

tomography scan (CT).

RESULTS CT revealed skeletal anomalies in all cases variable mandibular hypoplasia (n=10) (table1) temporo-mandibular joint anomalies (n=8) zygoma hypoplasia (n=6) pterygoid hypoplasia (n=4) Soft tissue anomalies (table3): muscle

hypoplasia were observed in 7 cases and parotid gland hypoplasia in 3 cases and agenesic in 3 cases

Hypoplasia of the tympanic cavity was present in 7 patients whith ossicular anomaly in 6 cases.

Other craniofacial anomalies was seen (table2).

Mandible anomalies Maxillar anomalies

Ear malformations

Ascending ramus

hypoplasia

Mandibar condyle

TM joint deformity

Reduced hight

External meatal Middle ear cavity ossicles Aberrant course of the facial nerve

atretic hypoplasia hypoplasia absent atretic hypoplasic malformed

3 10 7 8 2 6 4 7 1 1 6 2

Number

Soft tissus anomaliesMastication muscles hyploasia Parotid gland

masseter temporal pterygoid hypoplasia absent present

8 7 7 3 3 4

Number

Others craniofacial anomalies

mastoidhypoplasia

Zygomatic archhypoplasia

Styloid Processhypoplasia

Orbit anomalies

3 6 3 2

Table 1

Table 2

Table 3

Case n°1: A 2 years old boy

(a,b) 3D bone reconstruction reveal mandibular ramus,condyle and coronoid process hypoplasia, zygomatic arch hypoplasia (blue arrow) styloid hypoplasia ( yellow arrow) and reduced high of the maxillar (*)

a b

(c,d) coronal CT scan shows pterygoid process hypoplasia (red arrow), abnormal right TM joint (arrows) with dysplastic condylar process

(e,f) axial CT scan shows hypoplactic middle ear cavity (arrowhead) with atretic ossicles and external meatal atresia (arrow).c d

e

f

Case n°1

a

b

c

dCoronal (a,b) and axial (c,d) CT scan show hypoplasia of muscles of mastication: masseter (arrowhead), temporal (red arrow) and pterygoid (yellow arrow). It shows also agenesis of the parotid gland

Case n°2: 8 year old boy who had malformed left external ear since

birth.

a b c

de f

(a)3D bone reconstruction shows left mandibular and maxillary severe hypoplasia (*)with hypoplastic zygoma arch (arrow).

(b,c) CT scan show an absent condylar process, hypoplastic condyle with abnormal TM joint (arrow) and hypoplastic pterygoid process (arrowhead)

(e,f) axial CT scan reveal soft-tissu anomalies: hypoplastic masseter, temporal and pterygoid muscles (arrows) and hypoplastic parotid gland (*).

(d) axial CT scan reveal external meatal atresia, agenetic middle ear with hypoplastic and unpneumatized mastoid.

Case n°3: A 11 years old boy

(a,b) coronal CT scan and 3D bone reconstruction: hypoplastic mandibular condyle with TM joint dislocation (arrow).

a b

Coronal (c) and axial(e) CT scan: agenesis of external meatal, hypoplastic middle ear cavity, malformated ossicles (arrow) and hypoplastic and unpneumatized mastoid (*).

c d

e

(e)axial CT scan shows minor muscles hypoplasia (arrow) with normal parotid gland.

Case n°4: A 9 years old boy

Axial CT scan (a,b) and 3D bone reconstruction (c,d): mandibular condyle hypoplasia (arrow) with normal ramus. There is an external meatal agenesis and hypoplastis ossicles (arrowheads).

(e,f) axial and coronal CT scan show masseter,pterygoid and temporal muscle hypoplasia (arrows)with hypoplastic parotid gland (*)

Cas n°5: A 6 years old boy

3D bone reconstruction shows a more dramatic appearance of asymmetric hypoplasia of the mandible and hypoplastic zygomatic arch(a,b) CT scan reveals hypoplastic external meatal , middle ear cavity and ossicles (arrows)

a b

c d

(c,d) axial CT scan shows musles of mastication hypoplasia (arrows) agenesis of parotid gland (*)

Case n°6: A 10 years old boy

CT scan and 3D bone reconstruction show a left hemifacial microsoma which associate hypoplastic ramus (c,e) , mandibular condyle (b) with anomaly of TM joint (b) , hypoplastic pterygoid process( a) and zygomatic arch (e).

a bc

d e

Case n°6

( a,b,c,d) axial and coronal CT images reveal agenesis of external meatal (yellow arrow)and middle ear constituents (red arrows) and show an aberrant course of the 3rd portion of facial nerve (arrowhead)

a

b

c

d

e

(e) axial CT image shows masseter muscle hypoplasia with hypoplastic parotid gland

DISCUSSION Hemifacial microsomia is a congenital

malformation in which there is a deficiency in the amount of hard and soft tissue on one side of the face. It is primarily a syndrome of the first branchial arch,

It a syndrome involving underdevelopment of the temporomandibular joint, mandibular ramus, masticatory muscles and the ear

There may be cardiac, vertebral, and central nervous system defects, in addition to craniofacial anomalies.

Otomandibular dysostosis (OMD) is the second most common congenital facial anomaly after cleft lip/palate with a reported incidence of about 1 in 5600 live births.

Males appear to be more frequently affected than females (7 boys for 3 girls in our study).

It is usually unilateral (70%) and always asymetrical if it exhibits bilaterality.

Discussion

The phenotype is highly variable The clinical picture varies from slight

asymetry in the face to sever underdevelopment of one face half with orbital implications, a partially formed ear or even total absence of the ear.

In 48% of the cases, the condition is a part of a larger syndrome such as Goldenhar Syndrome (when epibulbar dermoids and vertebral anomalies are seen along with other findings of HFM)

Discussion

A panoramic radiograph provides an excellent overview of the osseous structures of the mandible and maxillofacial complex.

The relationship of the mandible and maxilla to the cranial base can be established initially with a lateral cephalometric radiograph.

Computed tomography (CT) can provide both a three dimensional rendition of the soft tissue and an image of the under lying bone

Information on comparative muscle development can be assessed through CT or magnetic resonance imaging on a case by case basis.

Discussion

Imaging findings: Craniofacial anomalies

1-Mandible The most obvious skeletal deformity (all our

cases), The ascending ramus can be absent or reduced

in height. It was the most common anomaly in our study,

The chin is deviated towards the affected side The mandibular condyle may be hypoplastic and malformed The TM joint deformity can range from mild

hypoplasia of the codyle with normal joint anatomy to a grossly disorganized joint anatomy and pseudo-articulation of the condyle at the cranial base.

S. Pruzansky’s mandible hypoplasia classification

Craniofacial anomalies

Grade I: minimal hypoplasia of mandibleGrade II: functioning but deformed TM joint with anteriorly and mdially dispalced condyleGrade III: absence of the ramus and glenoid fossa

2-Maxillar Is also reduced in height, present only in 2 cases in our

study Eruption of mandible and maxillary molllars is delayed 3-Ear The meatal atresia and middle ear anomalies are

almost constant findings (from 66 to 99%) (all cases), The external ear malformations vary from complete

aplasia to a crumpled, distorted pinna along with ear tags

Supernumerary ear tags may occur anywhere from the tragus to the angle of the mouth.

Middle ear cavity is small and ossicles may be absent, hypoplastic and/or malformed

The mastoid is always hypoplastic and unpneumatized

Craniofacial anomalies

4-Other craniofacial bones anomalies The zygoma arch may be decreased in

length or absent (60% in our study) The mastoid process can be hypoplastic The styloid process may be short or

absent , present in only 3 patients The orbit may be reduced in dimensions

and frontal bone can be flattered Clinical microphthalmia or anophthalmia

has been reported and the ipsilateral eye may be at a lower level than that on the opposite side.

Craniofacial anomalies

5-Extraskeletal anomalies Hypoplasia of facial muscles, such as the

masseter, temporal, pterygoid, and those of facial expression on the involved side can be observed (80% in our study)

Hypoplasia or aplasia of the parotid gland Narrowing of the palpebral fissure occurs on

the affected side in about 10% of patients A coloboma of the upper eyelid is frequently

encountered Associated cleft lip and/or palate is found in

7% of patients

Craniofacial anomalies

Epibulbar dermoids may be seen in Goldenhar

Syndrome Hypoplasia and / or paresis of palatal muscles

and pharynx, alongwith tongue musculature is also reported

6-Cranial nerve anomalies Sensorineural hearing loss and facial nerve

dysfunction are common Aberrant course of the facial nerve, Total or partial hypoplasy of the nerve. Only 3 patients have aberrant course of the

facial nerve without nerve paralysis.

Craniofacial anomalies

Imaging findings: Extrafacial anomalies

Cranial CT scan can revel hypoplasia of cerebrum and corpus callosum as well as hydrocephalus

Approximately, 50% of patients have congenital heart disease

40% to 60% of HFM patients exhibit occipitalization of the atlas, cuneiform vertebra, cervi cal complete or partial synostosis of 2 or more vertebrae, supernumerary vertebrae, spinal bifida, and anomalous ribs.

No extrafacial anomalies were seen in our study

The wide spectrum of anomalies associated with HFM has made systematic and inclusive classification difficult. Classification of the disease aids in diagnosis, treatment planning, prognostic predications, and data evaluation.

the 2 popular classification systems used for HFM, namely, the skeletal, auricular, and soft tissue (SAT) system, and the orbit, mandible, ear, nerve, and soft tissue (OMENS) system.

Imaging findings: classification

Skeletal categories Auricle categories Soft tissue categories

S1 = Small mandible with normal shape

A0 = Normal T1 = Minimal contour defect with no cranial nerve involvement

S2 = Condyle, ramus, and sigmoid notch identifiable but grossly distorted; mandible strikingly different in size and shape from normal

A1 = Small, malformed auricle retaining characteristic features

T2= Moderate defect

S3 = Mandible severely malformed, ranging from poorly identifiable ramal components to complete agenesis of ramus

A2 = Rudimentary auricle with hook at cranial and corresponding to the helix

T3 = Major defect with obvious facial scoliosis, possible severe hypoplasia of cranial nerves, parotid gland, muscles of mastication; eye involvement; clefts of face or lips

S4 = An S3 mandible plus orbital involvment with gross posterior recession of lateral and inferior orbital rims

A3 = Malformed lobule with rest of pinna absent

S5 = The S4 defects plus orbital dystopia and frequently hypoplasia and asymmetrical neurocranium with a flat temporal fossa

The skeletal, auricle, and soft tissue (SAT) classification system of HFM

Orbit Mandible Ear Facial nerve Soft tissue

O0 = Normal orbital size position

M0 = Normal mandible

E0 = Normal ear N0 = No facial nerve involvement

S0 = No obvious soft tissue or muscle deficiency

O1 = Abnormal orbital size

M1 = Mandible and glenoid fossa are small with a short ramus

E1 = Mild hypoplasia and cupping with all structures present

N1 = Upper facial nerve involvement (temporal and zygomatic branches)

S1 = Minimal subcutaneous/muscle deficiency

M2 = Mandibular ramus is short and abnormally shaped Subdivision A and B are based on relative positions of condyle and TMJ

N2 = Lower facial nerve involvement (buccal, mandibular, and cervical branches)

S2 = Moderate between

the 2 extremes,S1 and

S3

M3 = Complete absenceof ramus, glenoid fossa, and TMJ. Submental vertex views were usedto distinguish mandibular type 2A from type 2B.Type O, an apparentlynormal mandible has not been included in previous classification systems

N3 = All branches of facial nerve affected. Other involved nerves were also analyzed, eg, trigeminal N5 (sensory), hypoglossal N12; remaining cranial nerves are signified by the appropriate number in superscript

S3 = Severe soft tissue deficiency due to subcutaneous and muscularhypoplasmia

The orbit, mandible, ear, facial nerve, and soft tissue (OMENS) classification system of HFM

CONCLUSION The modern imaging opened a possibility of

precise exploration of oto-mandibular dysplasia

The techniques of browsing by CT scan and the software of image processing allow to carry out a true anatomical dissection of the whole of these malformative syndromes

The SAT and OMENS classification systems allows to delineate the condition of OMD to provide a rational basis for treatment choice.