Hemifacial microsomia (HFM) is a
congenital disorder
A birth defect, also known as a congenital disorder, is an abnormal condition that is present at birth regardless of its cause. Birth defects may result in disabilities that may be physical, intellectual, or developmental. The disabilities can ...
that affects the development of the lower half of the face, most commonly the ears, the mouth and the
mandible
In anatomy, the mandible, lower jaw or jawbone is the largest, strongest and lowest bone in the human facial skeleton. It forms the lower jaw and holds the lower tooth, teeth in place. The mandible sits beneath the maxilla. It is the only movabl ...
. It usually occurs on one side of the face, but both sides are sometimes affected. If severe, it may result in difficulties in breathing due to obstruction of the
trachea
The trachea, also known as the windpipe, is a Cartilage, cartilaginous tube that connects the larynx to the bronchi of the lungs, allowing the passage of air, and so is present in almost all air-breathing animals with lungs. The trachea extends ...
—sometimes even requiring a
tracheotomy
Tracheotomy (, ), or tracheostomy, is a surgical airway management procedure which consists of making an incision (cut) on the anterior aspect (front) of the neck and opening a direct airway through an incision in the trachea (windpipe). The ...
. With an incidence in the range of 1:3500 to 1:4500, it is the second most common birth defect of the face, after
cleft lip and cleft palate
A cleft lip contains an opening in the upper lip that may extend into the nose. The opening may be on one side, both sides, or in the middle. A cleft palate occurs when the palate (the roof of the mouth) contains an opening into the nose. The te ...
. HFM shares many similarities with
Treacher Collins syndrome
Treacher Collins syndrome (TCS) is a genetic disorder characterized by deformities of the ears, eyes, cheekbones, and chin. The degree to which a person is affected, however, may vary from mild to severe. Complications may include breathing prob ...
.
Presentation
The clinical presentation of HFM is quite variable. The severity may depend on the extent of the area with an insufficient blood supply ''in utero'', and the gestational age of the fetus at which this occurs. In some people, the only physical manifestation may be a small and
underdeveloped external ear. In more severe cases, multiple parts of the face may be affected. Some people with HFM may have
sensorineural hearing loss
Sensorineural hearing loss (SNHL) is a type of hearing loss in which the root cause lies in the inner ear or sensory organ (cochlea and associated structures) or the vestibulocochlear nerve (cranial nerve VIII). SNHL accounts for about 90% of rep ...
and decreased visual acuity or even blindness.
It can be thought of as a particularly severe form of HFM, in which extracranial anomalies are present to some extent. Some of the internal organs (especially the heart, kidneys, and lungs) may be underdeveloped, or in some cases even absent altogether. The affected organs are typically on the same side as the affected facial features, but bilateral involvement occurs in approximately 10% of cases. Deformities of the vertebral column such as scoliosis may also be observed.
While there is no universally accepted grading scale, the OMENS scale (standing for Orbital, Mandible, Ear, Nerves and Soft tissue) was developed to help describe the heterogeneous
phenotype
In genetics, the phenotype () is the set of observable characteristics or traits of an organism. The term covers the organism's morphology or physical form and structure, its developmental processes, its biochemical and physiological proper ...
that makes up this
sequence
In mathematics, a sequence is an enumerated collection of objects in which repetitions are allowed and order matters. Like a set, it contains members (also called ''elements'', or ''terms''). The number of elements (possibly infinite) is calle ...
or
syndrome
A syndrome is a set of medical signs and symptoms which are correlated with each other and often associated with a particular disease or disorder. The word derives from the Greek σύνδρομον, meaning "concurrence". When a syndrome is paired ...
.
Intellectual disability
Intellectual disability (ID), also known as general learning disability in the United Kingdom and formerly mental retardation,Rosa's Law, Pub. L. 111-256124 Stat. 2643(2010). is a generalized neurodevelopmental disorder characterized by signifi ...
is not typically seen in people with HFM. Hemifacial microsomia sometimes results in
temporomandibular joint disorder
Temporomandibular joint dysfunction (TMD, TMJD) is an umbrella term covering pain and dysfunction of the muscles of mastication (the muscles that move the jaw) and the temporomandibular joints (the joints which connect the mandible to the skull ...
s.
Cause
The condition develops in the
fetus
A fetus or foetus (; plural fetuses, feti, foetuses, or foeti) is the unborn offspring that develops from an animal embryo. Following embryonic development the fetal stage of development takes place. In human prenatal development, fetal deve ...
at approximately 4 weeks
gestational age
In obstetrics, gestational age is a measure of the age of a pregnancy which is taken from the beginning of the woman's last menstrual period (LMP), or the corresponding age of the gestation as estimated by a more accurate method if available. Su ...
, when some form of vascular problem such as
blood clotting
Coagulation, also known as clotting, is the process by which blood changes from a liquid to a gel, forming a blood clot. It potentially results in hemostasis, the cessation of blood loss from a damaged vessel, followed by repair. The mechanism o ...
leads to
insufficient blood supply to the face. This can be caused by physical trauma, though there is some evidence of it being
hereditary
Heredity, also called inheritance or biological inheritance, is the passing on of traits from parents to their offspring; either through asexual reproduction or sexual reproduction, the offspring cells or organisms acquire the genetic inform ...
. This restricts the developmental ability of that area of the face. Currently there are no definitive reasons for the development of the condition.
Diagnosis
Classification
Figueroa and Pruzanksky classified HFM patients into three different types:
* Type I : Mild hypoplasia of the ramus, and 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
In anatomy, the temporomandibular joints (TMJ) are the two joints connecting the jawbone to the skull. It is a bilateral synovial articulation between the temporal bone of the skull above and the mandible below; it is from these bones that i ...
.
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, HFM patients can be treated with various treatment options such as functional therapy with an appliance,
distraction osteogenesis
Distraction osteogenesis (DO), also called callus distraction, callotasis and osteodistraction, is a process used in orthopedic surgery, podiatric surgery, and oral and maxillofacial surgery to repair skeletal deformities and in reconstructive s ...
, 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, then surgery is preferred. If patient has mild symptoms, then a functional appliance is generally used.
According to Dr. Harry Pepe, a pediatrician from Hollywood, Fl, the goal of treatment in hemifacial microsomia is to elongate the deficient jaw bone to restore facial symmetry and correct the slanting bite (occlusion).
Patients can also benefit from a
Bone Anchored Hearing Aid
A bone-anchored hearing aid (BAHA) is a type of hearing aid based on bone conduction. It is primarily suited for people who have conductive hearing losses, unilateral hearing loss, single-sided deafness and people with mixed hearing losses who c ...
(BAHA).
Terminology
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
See also
*
Condylar hypoplasia
*
Goldenhar syndrome
Goldenhar syndrome is a rare congenital defect characterized by incomplete development of the ear, nose, soft palate, lip and mandible on usually one side of the body. Common clinical manifestations include limbal dermoids, preauricular skin ta ...
*
Parry–Romberg syndrome
Parry–Romberg syndrome (PRS) is a rare disease characterized by progressive shrinkage and degeneration of the tissues beneath the skin, usually on only one side of the face (hemifacial atrophy) but occasionally extending to other parts of th ...
References
*
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
GeneReviews/NCBI/NIH/UW entry on Craniofacial Microsomia Overview{{Medical resources
, DiseasesDB =
, ICD10 = {{ICD10, Q, 90, , q, 90
, ICD9 = {{ICD9, 758.0
, OMIM = 164210
, OMIM_mult =
, MedlinePlus =
, GeneReviewsName =
, ICDO =
, eMedicineSubj =
, eMedicineTopic =
, MeshID = D006053
Congenital disorders
Rare syndromes