Hemifacial Microsomia

Terminology First and second brachial arch syndrome

First and second branchial arch deformity or syndrome

Oculoauriculovertebral dysplasia

Oculoauriculovertebral spectrum

Otomandibular dysplasia

Otomandibular dysostosis

Lateral facial dysplasia

Unilateral craniofacial microsomia

Unilateral mandibulofacial dysostosis

Introduction Congenital asymmetry of the lower face

Hemifacial macrosomia is the most frequently encountered form of isolated facial

asymmetry.

The findings can be viewed as similar to those of TCS, but mainly these findings are

unilateral, causing gross facial asymmetry.

It could be bilateral in 16%

Affects 1st and 2nd branchial arch structures

Goldenhars (oculoauriculovertebral dysplasia) thought to

be variant of hemifacial microsomia, with eye tumors and fused

spines in addition to the characteristic facial asymmetry thus

collectively called: Oculo-auriculo-vertebral spectrum

(OAVS).

Better description is Craniofacial microsmia because

it accounts for cranium involvement and 30% bilateral (Gill

2015)

Etiology

1. Sporadic:

Tetragon (Thalidomide, retinoic acid)

2. Stapedial artery hematomas at approximately 30–45 days of gestation. At approximate ly

the 32nd day of intrauterine life the normal process of atrophy of the stapedial artery occurs,

allowing the switch of the blood supply to the face from the internal carotid to the external

carotid artery

3. Familial: 2-10% familial/genetic (Gene mapping has indicated a link to a region on

chromosome 10).

Incidence

1; 5,600

M: F 3:2

Bilateral in 10%

R: L 3:2

CLP 15% (CP twice as likely)

Feature

1. Ocular

Anophthalmia or microphthalmia may also occur.

Colobomata or Coloboma of the iris or eyelids

with the absence of the eyelashes is a frequent finding.

Ptosis of the upper eyelid (dropping of the upper

eyelid as a result of levator palpebral muscle function)

with narrowing of the vertical palpebral fissure is often seen.

Deficiencies of the lateral canthi with a decreased horizontal fissure are

common.

2. Ear

Hearing loss may result from underdevelopment of the osseous components of

the auditory system and a diminished or absent external auditory meatus.

Anotia to a mildly dysmorphic ear or unilateral microtia

Pre-auricular skin tags: between tragus and corner of mouth (area of fusion of

Maxillary Mandibular processes). The skin tags of HFM represent epithelial remnants

of the fusion of the maxillary and mandibular processes of the first branchial arch.

3. CN involvement: Facial nerve palsy (25-40%)

1st BA n = trigeminal usually okay

2nd BA n – facial n. lower braches affected

Severity of facial nerve involvement does not relate to degree of skeletal

involvement

4. Facial features:

Facial asymmetry

Dystopia

Orbital hypoplasia

Malar hypoplasia

Maxillary hypoplasia

Mandibular hypoplasia

Agenesis of the ramus

Hypoplastic glenoid fossa

Hypoplastic condyle

Hypoplastic coronoid process

Hypoplastic ramus

Hypoplasia or absence of muscle of mastication. According to the research of

Kane and colleagues, in patients with HFM, the extent of hypoplasia of specific muscles

of mastication frequently predicts the extent of dysplasia of the osseous origin and

insertion of those muscles. If the temporalis muscle is hypoplastic, a deficiency of the

coronoid process will be present. When the masseter muscle is hypoplastic, the gonial

region of the mandible will also be deficient. When the lateral pterygoid muscle is

deficient, the condylar head is deficient or absent. For any degree of muscle

hypoplasia there is a similar degree of skeletal dysmorphology. The opposite is not

true.

Microgenia

Macrosomia due to failed fusion of Mx and Mn process

5. Intraoral features

Delayed teeth eruption,

Hypodontia and Hypoplastic teeth (25%): Dentin is of neural crest origin. It

generally is accepted that normal odontogenesis requires the presence and interact ion

of neural crest ectoderm and mesenchymal cells. Disturbances in the odontogenic

process can produce abnormal or incomplete dental development. Maruko and

colleagues postulated that the increased incidence of hypodontia documented in

patients who have HFM may be attributed to a disturbance in neural crest cell

development.

Cross Bite

Lateral and anterior Open Bite

Midline asymmetry

Occlusal plane canting with ipsilateral shortening (Padwa 1997). The results

of this study indicate that 4 degrees is the threshold for recognition of an occlusal cant

by 90% of people)

CLP or CL 25%

Velopharyngeal insufficiency - ? DiGeorge Syndrome

6. Airway problem

7. Cardiac problem 50%

8. Renal or genitourinary anomalies problems

Differential diagnosis:

VACTERL is an acronym for

Vertebral anomalies, Anal atresia, Cardiac

malformations, Trachea, Esophageal fistula,

Renal Anomalies, and Limb anomalies.

Nager syndrome: downward

palpebral fissures, midface hypoplasia, micrognathia, and upper limb (radial)

deformities. Features are usually bilateral.

TCS: bilateral midface and mandibular hypoplasia, microtia, and coloboma.

Diagnosis

Family history

Clinical examination

OPG

Ceph

AP adiograph

CBCT

CT

MRI

Photo

3D photo

Laser

Genetic analysis

Classification of Hemifacial Microsomia

Mn classification originated from Purzansky 1969 and Kaban 1991, then OMENS added the

Mn to it – Vento & Le Brie 1991

Mandible modification by Kaban (Purzansky 1969, Kaban 1981 & 1991)

I – small condyle, under developed muscle of mastication (MoM)

IIa – hypoplastic condyle, hypoplastic MoM, absent/hypoplastic glenoid fossa

IIb – rudimentary condyle, rudimentary/absent MoM, glenoid fossa absent

III – condyle/glenoid fossa absent, rudimentary/absent MoM

OMENS Classification (Vento & LeBrie 1991)

The mandible is same as Purzansky

O – Orbital asymmetry

M – Mandibular hypoplasia

E – Ear anomalies

N – Nerve involvement

S – Soft tissue involvement

The number are added together Therefore, 15 would be the maximum score

possible

Management:

Initial assessment

New born child:

1. Pediatrician: kidney, heart, Airway – trachy? OSA

2. Ophthalmology: 15% ophthalmic protection due to facial paralysis

3. CP

4. Feeding

5. Audiology: hearing loss 15%

6. Speech

Early intervention (>3 years)

1. Cleft

2. Macrostomia

3. Skin tags

4. Facial n innervation

5. Occluar protection

6. Hearing (BAHA)

Mixed dentition:

Airway: OSA

Ocular protection

Safe and effective first-stage Le Fort I osteotomies carried out during the mixed

dentition are not practical as a result of the location of the developing teeth and the expected

inhibition of any postoperative horizontal maxillary growth.

Hybrid functional appliance alone

Ramus reconstruction alone

Hybrid functional appliance and ramus reconstruction combination

I. One way of treatment distraction osteogenesis (DO) for type I, IIA

For DO to be effective, a functional glenoid fossa and an adequate condyle must be present

(i.e., in the presence of Type I or Type IIA malformation).

It is a method of increasing bone length & originally described by Ilizarov (1988). The

technique involves:

1. Corticotomy – circumferential sectioning of compact bone and maintenance of

medullary complex.

2. Screw device holding bone pins rigidly and then the two pieces are separated in

a controlled and gradual process, which induces bony proliferation between them.

3. Screw turned after 5 days

1mm/day – adults

2mm/day – children

Insufficient speed = bony union

Undue haste = fibrous non-union

Traction forces applied to bone also create tension in the soft tissue, initiating a

sequence of adaptive changes termed distraction histogenesis.

Interestingly, most published reports of first-stage mandibular reconstruction in

patients with HFM do not fully justify it (Meazzini et al 2012). Those authors conducted

a comparison study of long-term follow up until the completion of facial growth of two

homogenous samples of children with HFM. The experimental group was treated with

mandibular DO during the deciduous or early mixed dentition in an attempt to correct

the mandibular deformity. The control group was not subjected to any treatment until

adulthood. The experimental group included children (n = 14) who underwent

mandibular ramus osteotomies with DO (mean age, 5.9 years) with a mean follow up

of 11.2 years. With the use of quantitative measurements on serial panorex radiographs,

the DO group was compared with the control group (n = 8). The study results document

that facial proportions in patients with HFM are maintained throughout growth when

no treatment is undertaken. Unfortunately, after ramus osteotomies with DO, the

mandibular disproportions returned to their original level of asymmetry during growth.

The authors concluded the following: 1) HFM does not progress with regard to the

degree of facial asymmetry or deformity when the patient is left to mature naturally and

2) early intervention with mandibular ramus osteotomies and DO does not effective ly

reduce long-term facial asymmetry in the patient with HFM. In published reports, most

children with HFM were still rated as “unattractive” after surgery and showed no

“improvement in self-esteem.” Children with HFM have an elevated risk for childhood

psychosocial difficulties. The only indication is if there is an airway issues.

II. Second way of treatment for type IIB, III involves an autogenous replacements for

the condyle and a hybrid functional appliance in different phases.

Way for autogenous replacements for the condyle have included:

the metatarsal bones

the proximal head of the fibula

the costochondral junction of the rib (CCJ/rib) (6th or 7th)

the sternoclavicular joint.

a. Very Early intervention at age of 5-6 years

Functional appliance

Then Surgery

Then functional appliance

b. Early intervention at age of 8-9 years

Surgery

Then Functional appliance

Ongoing problems when choosing the costochondral graft option to be carried out during the

mixed dentition for the Type IIB or III malformation include overgrowth, undergrowth,

ankylosis, and resorption of the mandible (third of the ribs not growing, a third growing within

the normal range, the remaining third presenting with overgrowth). The overgrowth concerns

are diminished but not eliminated when the costochondral graft procedure is carried out in a

child who is in the late mixed dentition stage (i.e., 9 to 11 years old) and in whom only a

minimum amount of cartilage (i.e., ≈2 mm) is left at the articulating surface of the graft.

Permanent dentition and late reconstruction after age of 13 years

The rationale for postponing the correction of the dentofacial deformity until the time of “early”

skeletal maturity is the same as that for the correction of the jaw deformity associated with a

repaired cleft palate and most other routine dentofacial deformities. This rationale includes the

consideration of the following:

o avoiding injury to the developing permanent dentition and the inferior alveolar nerves

o avoiding soft-tissue scarring

o avoiding the loss of ramus marrow space that will complicate the success of necessary

redo ramus osteotomies

o minimizing negative psychosocial memories of earlier jaw surgery that may prevent the

patient and family from later pursuing definitive reconstruction and

o avoiding the iatrogenic three-dimensional deformation of the mandible that limits long-

term success.

o In addition, any orthodontics carried out during the mixed dentition will not be reflective

of the permanent dentition; a final course of braces would also be required.

1. Orthodontics

As with other dentofacial deformities, extractions may be required to orthodontically relieve

dental root crowding and to normalize the inclination of the anterior teeth in preparation for the

surgical repositioning of the jaws.

2. Surgery

Type I and IIA mandibular malformations are best reconstructed after all of the

permanent teeth have erupted and orthodontic goals have been reached. Surgical objectives can

be met by making use of sagittal split ramus osteotomies of the mandible in combination with

Le Fort I osteotomy (often in segments) and osseous genioplasty.

For Type IIB mandibular malformations, costochondral graft reconstruction of the

deficient condyle ascending ramus at the time of skeletal maturity remains this surgeon’s

preferred approach in most cases despite its limitations. A sagittal split ramus osteotomy is

completed on the contralateral side to derotate the distal mandible. This is combined with a Le

Fort I osteotomy (often in segments) and an osseous genioplasty.

The Type III glenoid fossa–mandibular malformation requires the surgical construction

of the congenitally glenoid fossa in addition to the mandibular reconstruction that carried out

as previously described for the Type IIB deformity.

The surgical objectives of the Le Fort I osteotomy may include the following:

1. Vertical:

Cant correction of the maxilla

Either extrusion or intrusion of the posterior maxilla on each side, depending on the

extent of counter-clockwise rotation required to achieve adequate horizontal projection of the

mandible and chin (i.e., pitch orientation)

2. Transverse:

Correction of the maxillary dental midline to the facial

Widening of the maxilla

3. AP:

Horizontal advancement to improve midface projection and to open the upper airway

4. Other:

Bone grafting of the zygomatic buttress on the ipsilateral side to improve facial

symmetry

Provision of access for intranasal procedures (e.g., septoplasty, inferior turbinate

reduction, recontouring of the pyriform rims and the nasal floor).

3. External Auditory Canal and Middle-Ear Reconstruction

Generally, attempts to reconstruct the external auditory canal and the bones of the middle ear

for patients with HFM are not carried out as long as adequate hearing is present in the

contralateral ear

A bone-anchored hearing aid (BAHA) consists of a permanent titanium fixture that is

surgically implanted into the skull bone behind the ear and a small detachable sound processor

that clips onto the fixture. BAHAs are suitable for people with conductive or mixed hearing

loss

4. Soft Tissue Free flap:

Antero-lateral groin or rotational from shoulder

Coleman fat transfer (20-50% of cells lost). Adipose tissue is taken from a donor site,

thigh or abdomen (often the belly button), centrifuged intraoperatively and injected

subcutaneously into the area of deficiency. The technique has evolved with improved long term

benefit. It has the advantage of being minimally invasive. As a camouflage procedure it may be

a reasonable alternative for an adolescent until conventional orthognathic treatment can be

offered.

External Ear Reconstruction

5. Genetic analysis

Finally, those patients with known mutations will need counselling from the genetic is ts

as to their future plans.

At Great Ormond Street:

I, IIa

wait until growth complete: ortho at 12 yrs,

16-18 yrs orthognathic

IIb, III

9yrs ramus reconstructions

12 yrs orthodontics

18 years: orthognathic

Goldenhar’s Syndrome (Meenan 2014)

Structures if the 1st and 2nd brachial arches affected 6th week of gestation

Incidence- 1:26000 (Hartsfield 2007)

Etiology

Vascular disturbances in development of NC structures of the 1st and 2nd aortic arches

AD – APC gene mutation (part of Wnt2 pathway – expressed in initiation/ bud

formation phase)

risk prenatal: vasodilative medication, maternal diabetes, twin pregnancies, 2nd trimester

bleeding, artificial reproductive techniques, alcohol

Diagnosis:

Prenatal ultrasound (false –ve in 15%)

Presence of ear tag or (triad micrognathia, glosspotisis, upper air way obstruction)

To differentiate between GHS or Pierre Robin, look for craniofacial and vertebral

abnormalities

Clinical features;

Similar to TCS, But GHS shows

Bilateral in 33%, both sides

maybe affected to varying degrees

vertebral defects 24%

epibulbular dermoids

Microtia/atresia or ear tags

Multiple fibromas/odontomes

Association with colorectal cancer

Craniofacial abnormalities: Facial n palsy (15%) with degree of asymmetry Mx, Mn

zygomatic hypoplasia

TMJ abnormalities

CLP

Teeth: hypodontia, supernumeries, hypoplasia

Oro-maxillo-mandibular and dental intervention

Same as HFM