HEMIFACIAL MICROSOMIA

A Rare Dental Disease

OUTLINE OF THE LECTURE1. Intro.: Assymmetry vs. Symmetry.2. Definition3. Incidence4. Etiology & Genetics5. Diagnosis:

1. Clinical Manifestations2. Nomenclature3. Radiographic Findings

6. Treatment:1. Surgical I: Orthognathic Surgery (Osteotom &

Graft)2. Surgical II: Distraction Osteogenesis.3. Orthodontic.

ASYMMETRY

Patient presenting with left-sided hemimandibular hyperplasia. (b) Note the right-sided chin point deviation which is clearly visible from below

An OPG radiograph of the same patient demonstrating:• increased vertical mandibular growth on the left side• increased alveolar height• a leftsided lateral open bite• displacement of the inferior dental canal on the left.

SYMMETRY Symmetry is defined as correspondence in size,

shape and relative position of parts on opposite sides of a dividing line or median plane.

Asymmetry is described as a lack or absence of symmetry.

When applying this to the human face, it illustrates an imbalance or disproportionality between the right and left sides.

A degree of asymmetry is normal and acceptable in the average face.

It may be caused by a range of factors that affect the underlying skeletal structure or soft tissue drape.

SYMMETRY IS A MYTH Perfectly bilateral face and body symmetry

is largely a theoretical concept that rarely exists in living organisms.

Right-left differences occur everywhere in nature where two bilateral congruent parts present in an entity.

Humans frequently experience functional as well as morphological asymmetries, e.g. right and left handedness. Some of these asymmetries are embryonically or genetically determined and encoded in the central nervous system.

TO WHAT EXTENT? Preferential laterality for some anomalies is striking,

such as cleft lip, which occurs more commonly on the left side.

Left-right tooth crown size asymmetry, evident by measurement but not by visual inspection, is also a normal state in the general population.

Slight facial asymmetry can be found in normal individuals, even in those with aesthetically attractive faces. This minor facial asymmetry is common, usually indiscernible and does not require any treatment.

The point at which ‘normal’ asymmetry becomes ‘abnormal’ cannot be easily defined and is often determined by the clinician’s sense of balance and the patient’s sense of imbalance.

However, the importance of early diagnosis and the detection of progressive causative conditions is essential for the management of facial asymmetry.

DIAGNOSIS:ASSYMMETRY IN THE FACE.

MANDIBULAR ASSYMMETRY

HEMIFACIAL MICROSOMIA

1- DEFINITION Hemifacial microsomia is a

congenital malformation in which there is deficiency in the amount of hard and soft tissues on one side of the face.

It is primarily a syndrome of first and second branchial arches involving underdevelopment of the temporomandibular joint, mandibular ramus, masticatory muscles, ears and occasionally defects in facial nerve and muscles.

1ST & 2ND PHARYNGEAL ARCHES AFFECT: Maxilla Mandible External and middle ear Facial and trigeminal nerves Muscles of mastication And overlying soft tissue.

2- INCIDENCE Hemifacial microsomia (HFM) is:

The most frequently encountered form of isolated facial asymmetry.

The second most common congenital facial anomaly after cleft lip/palate.

Incidence between 1 in 3000 and 1 in 5600 births.

Males appear to be more frequently affected than females. (3 : 2)

The right side is affected more often than the left side.

Although HFM refers to one half of the face, the condition is bilateral in 31% of the cases, with one side being more affected than the other.

In 48% of cases, the condition is part of a larger syndrome such as Goldenhar syndrome.

NOMENCLATURE HFM was first described by German physician Carl

Ferdinand Von Arlt in 1881. 1. Gorlin et al. used the term HFM to describe patients with

unilateral microtia, macrostomia and malformation of mandibular ramus and condyle,

2. whereas Goldenhar syndrome was described as a variant, with vertebral anomalies and epibulbar dermoids. ( العين حبة تغطى (لحمLية

3. The name, craniofacial microsomia, was proposed by Converse et al. when cranial deformities were included.

4. Other synonyms include:1. first arch syndrome, 2. first and second branchial arch syndrome,3. otomandibular dysostosis,4. oculo-auriculovertebral dysplasia and5. lateral facial dysplasia.

IN THE INTERNET WE CAN FIND GUIDES LIKE THIS:

A Parent’s Guide to HFMA Publication of Children’s craniofacial association

IN THIS GUIDE IT WAS WRITTEN: Hemifacial Microsomia is a condition that

simply comes “out of the blue” (فجأة) It doesn’t run in families and is not a result

of disease process. Simply stated, it is a birth defect. (congenital)

Some cases of HFM are severe; therefore the degree of deformity is considerable. Other cases are mild with a wide spectrum of manifestation.

A doctor or medical team makes the clinical diagnosis. No DNA has been Identified in the condition.

3- ETIOLOGY Cause is unknown Stapedial Vessel Rapture affecting 1st &

2nd brachial arches development More recently (2002), a report of a

transgenic mutation of a locus termed Hfm (B1 to B3 on chromosome 10) in a mouse model seems to provide insight into the pathogenesis of HFM

GENETICS: OMIM 164210 OMIM® and Online Mendelian Inheritance in

Man ® are registered trademarks of the Johns Hopkins University. Copyright® 1966-2012 Johns Hopkins University.

OMIM is intended for use primarily by physicians and other professionals concerned with genetic disorders, by genetics researchers, and by advanced students in science and medicine. While the OMIM database is open to the public, users seeking information about a personal medical or genetic condition are urged to consult with a qualified physician for diagnosis and for answers to personal questions.  

GENETICS Hemifacial microsomia is a common

birth defect involving first and second branchial arch derivatives.

The phenotype is highly variable. In addition to craniofacial anomalies, there may be cardiac, vertebral, and central nervous system defects.

Most cases are sporadic (Where There Are No Affected Relatives), but there are rare familial cases that exhibit autosomal dominant inheritance.

مدى عن وتساؤلى Lالعيادة حول Lمناقشاتى أحد فLىأقLسام Lبباقى مقارLنة األسLنان ورLاثة قسم انضباط

التخصصات من الورLاثة تخصص أن اLلرد، كان الشعبة،فLيها للباحثين تتيح التى للحاالت منجم وعيادتها L،النادرة

Lعلى التعرف خالل من وLأبحاثا علمية أوLراقا Lيكتبوا أناألشLعة Lفى المتخصص أن حتى ووLصفها، الحاالت بعض

يجد لن فLهو آخر، لقسم االنتقال رLفض لديهم Lمثلى. الوراثة عيادة حاالت تواLزى حاالت

نLمم Lلمثلى يحققها أLن الله من أLرجو التى واألمنية : عيادة تصبح أن الشعبة هذه مستقبل فLى يفكروLن

عيادات من كثير يقدمها ال التى وLخدماتها بتميزها األسناننستطيع بحاالت تأتى طيبة سمعة ذاLت اLلخاصة األسنان

طب مثل طبى عمل أLى وLهدف فغاية بحثيا، عليها العمليكون Lفكيف للعالج، جيدة طرق عن اLلبحث هو األسLنان

بنسبة ولو مرضى، دوLن من L50ذلك. اLألبحاث% من

4-DIAGNOSIS & CLINICAL

MANIFESTATIONS

1- Extraoral2- Classifications

3- Intraoral

CLINICAL PICTURE Ranging from the mildest form that

included facial asymmetry and ear deformity to the most severe and unusual form with facial nerve paralysis and spine deformity.

DIAGNOSIS:ASSYMMETRY IN THE FACE.

1- EXTRAORAL EXAMINATION: A-SKULL & ORBIT May be associated with

underdevelopment in the skull, or the orbit on the affected side.

There may be a small non-seeing eye or the eye may be entirely absent. (A range of eye problems: from Normal to absent)

Eyelids: dermoids or notches. The Cheek: is flat because the bone

beneath hasn’t grown properly. The Face: is vertically short in this side.

1- EXTRAORAL EXAMINATION: B-MANDIBLE It is involved in a similar way. Underdeveloped Mandible or a portion

of the mandible can be missing (ramus or condyle)

Condylar Hypoplasia or Aplasia.

1- EXTRAORAL EXAMINATION: C-THE EAR External Ear:

May be Normal.May be Underdevelped.May be Absent.

There May be skin tags in front of the ear or in a line between the ear and the corner of the mouth.

Hearing is defective.

1- EXTRAORAL EXAMINATION: D-NERVE INVOLVEMENTE-SOFT TISSUE DEFICIENCY

2- CLASSIFICTIONS1. OMENS Classification:

1. O=Orbital Distortion2. M=Mandibular Hypoplasia3. E=Ear Anomaly4. N=Nerve Involvement5. S=Soft Tissue Deficiency

2. SAT Classification:1. S=Skeletal2. A=Auricular3. T=Soft Tissue

3. Pruzansky & Kaban’s Classifications:Grade I, IIA, IIB, III MandibleMost Useful in Clinical practice

PRUZANSKY’S AND KABAN’S CLASSIFICATIONS

Pruzansky, 1969 described a system that presented a simple workable mandibular classification based on three different types of mandibular deformities.

Grade I mandible: a small mandible with a normal TMJ. It is a normally shaped miniature mandible with a normal glenoid fossa and well-developed muscles of mastication.

Grade II mandible: has a functioning TMJ with a misshapen condyle and a ramus that is short and abnormally shaped. The muscles of mastication are somewhat deficient. I

grade III mandible: the ramus, and glenoid fossa are absent and there is no TMJ – in essence, agenesis of the ramus. There is also significant soft tissue deformities. The mandible may end abruptly in the molar region.

In the Pruzansky system, the distortion of the adjacent facial skeleton is directly related to the degree of mandibular deformity.

In Kaban’s modification of Pruzansky’s grading system, type I and type III are essentially unchanged, but the type II deformity is separated into

IIA and IIB. Kaban type IIA: the TMJ, ramus and glenoid fossa are hypoplastic, malformed and

malpositioned, but the deformed joint is adequately positioned for symmetric opening of the mandible.

In the type IIB: the joint is malpositioned inferiorly and medially and will not function as a TMJ for adequate symmetric opening of the mandible.

In the type IIA, the degree of hypoplasia of the mandibular musculature is closer to normal than in the type IIB.

In the type III deformity of the neuromusculature is very deficient . In the United States the Kaban’s modification of Pruzansky’s system is the system

most widely used in publications.

VARIANT II (CRANIOFACIAL MICROSOMIA) A variant of this disease. In addition to

what seen above: The Forehead: is flattened. The Eye: may be pulled downward(Infra

___)

VARIANT III (GOLDENHAR SYNDROME) Very similar with addition findings: Benign Growths on the eyes (Epibulbar

Dermoids). May also have neck problems: fusions

between the bones of the neck (vertebrae), causes the most common problems.

Goldenhar’s Syndrome is called also: Occulauricular dysplasia (OAV)

3- INTRAORAL EXAMINATION Intraoral manifestations include:

Malocclusion Tooth discrepancies Agenesis of teeth Supernumerary teeth Enamel and dentin malformations Delay in tooth development.

CANTING

5- DIAGNOSTIC AIDS1- Radiography

2- Computed Tomography3- Photography

4- 3D Photography

(a) Patient presenting with right-sided hemifacial microsomia. Lack of mandibular growth on the right side has resulted in chin displacement to the affected side.

(b) A panoramic radiograph illustrating the lack of mandibular growth on the right side.

RADIOGRAPHY: POSTROANTERIOR VIEW

COMPUTED TOMOGRPHY Axial Computerized Tomography

showing hypoplastic left ramus and coronoid process of mandible

Computerized Tomography showing hypoplastic left pterygoid plates

3D RECONSTRUCTION

PHOTOGRAPHY

3D PHOTOGRAPHY

5-TREATMENTI. 1- Surgical: Orthognatic Surg.

II. 2-Surgical: DOIII. 3- Orthodontic

A MULTIDISCIPLINARY PLAN Due to unilateral deficiency of the

mandible and lower face, patients with HFM have specific dental needs that require restorative, orthodontic and surgical correction.

The treatment always requires an interdisciplinary approach including at least maxillofacial surgery and orthodontics.

TREATMENT1: (FIRST SPECIALITY: NEUROSURGERY) This disease is a very complex 3Dimentional

Deformity. The correction is difficult and can rarely be achieved in one stage.

1. If the skull & the skull base are underdeveloped & assymmetrical, then Intracranial surgery may be necessary to enlarge the skull, by putting the skull bones in the correct position. (A Neurosurgeon helps with this procedure)

Usually at this time it is possible to enlarge the orbit & to reconstruct the zygomatic arch, or cheek bones.

The operation can be done with either bone from the skull or elsewhere (Bone graft)

Timing: at an early age (when the patient presents for treatment)

TREATMENT2 (SECOND SPECIALITY: MAXILLOFACIAL/ORTHOGNATHIC SURGERY) Before school Jaw Lengthening can be done: Maxillary Osteotomy and grafting or

Distraction Osteogenesis Mandible may be done in the same time, to

adjust Occlusion. Absence of Condyle is displaced by a rib graft

which has cartilage on its upper surface (to form a joint)

Soft tissue Deficiency can be reconstructed using Skin and fat grafts.Muscle grafts are used in some cases (Free Flap, containing Blood vessels will be attached to Neck vessels)

TREATMENT3 (THIRD SPECIALITY: PLASTIC SURGERY)1. To Revise Scars.2. To Shift the Soft Tissue around to

obtain a better contour or shape.3. Bone Grafting some needed areas.

(from skull or hip)4. Eye Socket Reconstruction and

Artificial Eye Prosthesis.

TREATMENT4 (FOURTH SPECIALITY: ORTHODONTIC TREATMENT) Treatment of problematic Eruption &

Occlusion Treatment of Canting.

PROBLEMS DURING TREATMENT1. Long-term Follow Up.2. Tendency for poor growth on the affected

side.3. Missing Eye.(Occularist)4. Occlusion Problems /Canting.

(Orthodontist)5. Hearing Defects. Abnormalities of the

internal ear, and ear canal can be completely absent.

This leads tovarying degrees of deafness (normal hearing is possible in most cases).(Neuro-otologist)

ABSENCE OF EXTERNAL EAR:

1. Osseointegration using small metal studs into the bone in the ear region. A framework is is then attaced to the studs & a silicone ear (a replica of the normal ear)

[Very Secure- Relistic-With no feeling- can be detached & lost-color may fade- need to be changed with growth of the child]

2. To make an ear from Rib Cartilage (A staged Procedure):

1. Cartilage framework is carved according to the pattern designed from the other ear.

2. Placed under the skin on th side of the head3. After a length of time, the ear is elevated and another skin

graft is placed behind it.[takes several operations wh. Is cosmetically accepted- may not

be accurat – may vary in color- will have no normal sensation, however, it is more convenient than a prosthetic ear]

CHILD INTELLIGENCE Children Often look different, but most

of these children are of normal intelligence and function completely normally

Learning Difficulties: Language problem due to deafness.

It is important for parents to realize that rehabillitation will take a long time, because of complexity of the disease, and because of growth changes between to sides.

TEAMWORK AT CRANIOFACIAL CENTRES This needs a multidesciplinary treatment with

many spechialists to reach better results & fewer complications. (Centres with craniofacial team which are up to date with new research in their specialities & well experienced about these cases are better to treat these children)

Separate Physicians may have unsatisfactory results, which may need more 2 or 3 operations to correct what has been done.

Meeting other families with the same problem in these centres offer an opportrunity of advice and support.

(a) Patient presenting with right-sided hemifacial microsomia. Lack of mandibular growth on the right side has resulted in chin displacement to the affected side.

(b) A panoramic radiograph illustrating the lack of mandibular growth on the right side.

6- ORTODONTIC/ SURGICAL

TREATMENT

1- ORTHODONTIC TREATMENT In designing a course of treatment, the

dental occlusion must be considered in conjunction with the underlying skeletal condition.

Orthodontic therapy begins with removable orthodontic appliance (functional

appliance) and when secondary dentition appears it is possible to continue the treatment using fixed orthodontic appliance to restore proper occlusal plane.

2- MXILLA & MANDIBLE RECONSTRUCTION:

Ramus interpositional bone grafting or end-on bone grafting. In a few cases, ramus lengthening may be completed by a sagittal split.

NEUROMASCULAR ADAPTATION Egil Harvold and his colleagues developed a method

by which changes in form and function are co-ordinated by using a functional appliance resulting in neuromuscular adaptation.

After the bone grafting is completed, as the second of six phases of treatment, a specially designed registration bite-block further facilitates neuromuscular adaptation by controlling mandibular movements (function), but in addition it protects the bone graft from excessive forces thereby aiding in osteogenesis (third phase).

While this form of treatment is not the only one possible, it is the only one that has been tested in the laboratory, proven in patient care, and stood the test of time. (Ousterhout & Vargervik, Aust N Z, 1987)

3- DISTACTION OSTEOGENESIS

SURGICAL APPROACHES The surgical intervention is needed to

lengthen the mandibular ramus and corpus which will reduce facial asymmetry.

two approaches:early surgical intervention(during

growth) late surgical intervention (after the

active growth period) In the early approach, either the

conventional surgical procedure or the distraction technique are possible.

CONVENTIONAL CHOSTOCHONDRAL GRAFT During the conventional surgical

procedure, the deficient ramus of the mandible is partly replaced by an autologous costo-chondral bone graft.

A costo-chondral bone graft is preferred as it still has a growth potential that makes it comparable to the non-affected side.

A costo-chondral graft provides length to the ramus,

as well as a joint; it also acts as a growth centre.

DISTRACTION OSTEOGENESIS AS A FIRST CHOICE In some centres the use of the

distraction technique is the early procedure of choice.

The late procedure consists of either a classical osteotomy (i.e. bimax surgery with canting the maxilla in combination with advancement of the mandible and lengthening the ramus)

or a bimaxillary distraction osteogenesis

 Postero-anterior cephalometric radiographs of one patient pre-distraction (Tpre), at the end of distraction, just before removal of the pins (Td), and 5 years post-distraction (T5). The Occlusal plane is marked by a white dotted line, the Antegonial plane by a grey continuous line. (Maria Costanza Meazzini et al., 2005)

 Panoramic radiographs of one patient pre-distraction (Tpre), at end of distraction, prior to removal of the pins (Td) and at the longest follow-up record, 5 years post-distraction (T5).

Frontal photograph of a patient pre-distraction (Tpre), 1 year post-distraction (T1) and 5 years post-distraction (T5). Note the improvement in the facial contour and lip commissure level after distraction, but the substantial ‘return’ of the phenotype 5 years post-distraction.

Anatomical landmarks and planes on frontal cephalometric tracing. Latero-orbitale (LOr), Infraorbital point (InfOr), Nasal floor point (NF), Occlusal plane point (Oc), Antegonial point (Ag). Horizontal reference line (Lor–Lor), Infraorbital plane (InfOr–InfOr), Nasal Floor (NF–NF), Occlusal Plane (Oc–Oc), Antegonial Plane (Ag–Ag).

DISTRACTION OSTEOGENESIS

DISTRACTION OSTEOGENESIS

DISTRACTION OSTEOGENESIS

MUSCLE ADAPTATION

MUSCLE ELONGATION TRACTION

COORDINATON Successful treatment of hemifacial

microsomia calls for close coordination among the patients’ dental care providers, dental specialists and medical care providers.

From maintenance therapy to intricate orthodontic, pediatric, restorative, prosthetic and surgical procedures, all aspects of clinical care must be maximized to provide these patients with optimal treatment.

REFERENCES1. Manu Dhillon et al., Hemifacial

microsomia: a clinicoradiological report of three cases. Journal of Oral Science, Vol. 52, No. 2, 319-324, 2010.

2. A guide to understanding hemifacial microsomia. A publication of children’s craniofacial Association, Dallas, TX, 2005.

3. Maria Mielnik-Błaszczak & Katarzyna Olszewska. Hemifacial Microsomia – Review of the Literature. Dent. Med. Probl. 2011, 48, 1, 80–85.