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Bilateral (both sides) hemifacial microsomia in an adolescent

Hemifacial microsomia is a congenital disorder that affects the development of the lower half of the face, most commonly the ears, the mouth and the mandible. It can occur on one side of the face or both. If severe it can lead to difficulties in breathing, obstructing the trachea and requiring a tracheotomy. It is the second most common facial birth defect after clefts, with an incidence in the range of 1 in 3500 to 4500.^[1] Hemifacial microsomia shares many similarities with Treacher Collins syndrome.

Other names

The condition is also known by various other names:

Lateral facial dysplasia
First and second branchial arch syndrome
Oral-mandibular-auricular syndrome
Otomandibular dysostosis
Craniofacial microsomia

Cause

The condition develops during the fetal stage of pregnancy at approximately 4 weeks of gestation, when some form of vascular problem leads to clotting and a poor supply of blood to the face. This can be caused by a physical trauma, though there is some evidence of it being hereditary ^[2]. This restricts the developmental ability of that area of the face. Currently there are no definitive reasons for the development of the condition.

Severity

The clinical presentation of hemifacial microsomia (HFM) can be quite variable. In some children, just the ear is affected (microtia or a small, underdeveloped ear), and in other children, multiple parts of the face and body can be affected. While there is no grading scale that is in use universally, the OMENS scale (standing for Orbital, Mandible, Ear, Nerves and Soft tissue) was developed to help describe the heterogeneous phenotype that makes up this malformation. Children with HFM are at higher risk for hearing loss, and should have their hearing tested. A proportion of children with HFM will have extra-cranial anomalies, including abnormalities of the kidneys and cervical spine, which are important to detect early in childhood. Cognition and development is usually typical in children with HFM.

Some have hypothesized that the severity of hemifacial microsomia depends on the extent of the physical injury (the area with a short supply of blood) and the gestational age of the fetus – the earlier the injury, the greater the chance of wide-scale problems. This has not yet been proven in an animal or human model.

Classification

Pruzanksky classified Hemifacial Microsomia patients into three different types.

Type I : Mild hypoplasia of the ramus , and the the body of the mandible is slightly affected.
Type II : The condyle and ramus are small, the head of the condyle is flattened , the glenoid fossa is absent , the condyle is hinged on a flat, often convex, infratemporal surface , the coronoid may be absent.
Type III: The ramus is reduced to a thin lamina of bone or is completely absent. There is no evidence of a TMJ.

Treatment

Depending upon the treatment required, it is sometimes most appropriate to wait until later in life for a surgical remedy – the childhood growth of the face may highlight or increase the symptoms. When surgery is required, particularly when there is a severe disfiguration of the jaw, it is common to use a rib graft to help correct the shape.

According to literature, Hemifacial Microsomia patients can be treated with various treatment options such functional therapy with an appliance, Distraction osteogenesis, or Costochondral Graft. The treatment is based on the type of severity for these patients. According to Pruzanksky's classification, if the patient has moderate to severe symptoms, than surgery is preferred. If patient has mild symptoms, than a functional appliance is generally used. ^[1]

Patients can also benefit from a Bone Anchored Hearing Aid (BAHA).

References

^ Hansen, PR (1999). "Orthodontic management of the patient undergoing mandibular distraction osteogenesis.". Seminar in Orthodontics. Retrieved 21 September 2015.

^ "Hemifacial Microsomia" at the Tennessee Craniofacial Center. Accessed 20 January 2008.
^ "Hemifacial Microsomia" at the Children's Hospital and Health System of Wisconsin. Accessed 20 January 2008.

External links

Hemifacial Microsomia information from Seattle Children's Craniofacial Center
GeneReviews/NCBI/NIH/UW entry on Craniofacial Microsomia Overview
"Hemifacial Microsomia" at Little Baby Face Foundation.
The story of a Canadian woman with Hemifacial Microsomia

UpToDate Contents

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1. 頭蓋顔面異常を伴う症候群 syndromes with craniofacial abnormalities
2. 耳の先天異常 congenital anomalies of the ear
3. 小児における顔面神経麻痺 facial nerve palsy in children
4. 小児における難聴の病因 etiology of hearing impairment in children
5. 視神経の先天性および後天性異常 congenital anomalies and acquired abnormalities of the optic nerve

English Journal

Sequential treatment for a patient with hemifacial microsomia: 10 year-long term follow up.

Seo JS1, Roh YC1, Song JM1, Song WW1, Seong HS1, Kim SY1, Hwang DS1, Kim UK1.
Maxillofacial plastic and reconstructive surgery.Maxillofac Plast Reconstr Surg.2015 Feb 5;37(1):3. eCollection 2015.
Hemifacial microsomia (HFM) is the most common craniofacial anomaly after cleft lip and cleft palate; this deformity primarily involves the facial skeleton and ear, with either underdevelopment or absence of both components. In patients with HFM, the management of the asymmetries requires a series o
PMID 25664313

Oculo-Auriculo-Vertebral Spectrum: CLINICAL and Molecular Analysis of 51 Patients.

Beleza-Meireles A1, Hart R2, Clayton-Smith J3, Oliveira R4, Reis CF4, Venâncio M4, Ramos F4, Sá J4, Ramos L4, Cunha E5, Pires LM6, Carreira IM6, Scholey R7, Wright R8, Urquhart JE8, Briggs TA7, Kerr B7, Kingston H7, Metcalfe K7, Donnai D7, Newman WG3, Saraiva JM9, Tassabehji M10.
European journal of medical genetics.Eur J Med Genet.2015 Jul 20. pii: S1769-7212(15)30006-9. doi: 10.1016/j.ejmg.2015.07.003. [Epub ahead of print]
INTRODUCTION: Oculo-auriculo-vertebral spectrum (OAVS OMIM164210) is a craniofacial developmental disorder affecting the development of the structures derived from the 1st and the 2nd branchial arches during embryogenesis, with consequential maxillary, mandibular, and ear abnormalities. The phenotyp
PMID 26206081

Cranial Nerve Abnormalities in Oculo-Auriculo-Vertebral Spectrum.

Manara R1, Brotto D2, Ghiselli S2, Mardari R3, Toldo I4, Schifano G2, Cantone E5, Bovo R2, Martini A2.
AJNR. American journal of neuroradiology.AJNR Am J Neuroradiol.2015 Jul;36(7):1375-80. doi: 10.3174/ajnr.A4273. Epub 2015 Mar 26.
BACKGROUND AND PURPOSE: Cranial nerve abnormalities might be observed in hemifacial microsomia and microtia (oculo-auriculo-vertebral spectrum), but the rate, features, and relationship with functional impairment or phenotype severity have not yet been defined. This study aimed at investigating abse
PMID 25814660

Japanese Journal

Hemifacial microsomiaにおける軟部組織の再建 (特集顔面輪郭形成術)

多久嶋亮彦,波利井清紀
形成外科 57(4), 369-375, 2014-04
NAID 40020054777

片側下顎角部へのカスタムメイド人工骨の補填により顔貌の非対称を改善したHemifacial microsomiaの1例:―骨延長後の成長による非対称再燃への対応―

谷口広祐,土生学,鶴島弘基,福田仁一,吉岡泉,冨永和宏
日本顎変形症学会雑誌 24(3), 259-268, 2014
… Hemifacial microsomia (HFM) is a congenital disorder derived from hypoplasia of the first and second branchial arches that occurs at an incidence in the range of 1 in 3,000 to 5,000 births.We reported a case of HFM with difficulty in management. …
NAID 130004691918