Hemifacial microsomia
Encyclopedia
Hemifacial microsomia is a congenital disorder
that affects the development of the lower half of the face
, most commonly the ear
s, 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 . Hemifacial microsomia shares many similarities with Treacher Collins syndrome
.
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
. This restricts the developmental ability of that area of the face. Currently there are no definitive reasons for the development of the condition.
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.
Patients can also benefit from a Bone Anchored Hearing Aid
(BAHA).
Congenital disorder
A congenital disorder, or congenital disease, is a condition existing at birth and often before birth, or that develops during the first month of life , regardless of causation...
that affects the development of the lower half of the face
Face
The face is a central sense organ complex, for those animals that have one, normally on the ventral surface of the head, and can, depending on the definition in the human case, include the hair, forehead, eyebrow, eyelashes, eyes, nose, ears, cheeks, mouth, lips, philtrum, temple, teeth, skin, and...
, most commonly the ear
Ear
The ear is the organ that detects sound. It not only receives sound, but also aids in balance and body position. The ear is part of the auditory system....
s, the mouth
Mouth
The mouth is the first portion of the alimentary canal that receives food andsaliva. The oral mucosa is the mucous membrane epithelium lining the inside of 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
Vertebrate trachea
In tetrapod anatomy the trachea, or windpipe, is a tube that connects the pharynx or larynx to the lungs, allowing the passage of air. It is lined with pseudostratified ciliated columnar epithelium cells with goblet cells that produce mucus...
and requiring a tracheotomy
Tracheotomy
Among the oldest described surgical procedures, tracheotomy consists of making an incision on the anterior aspect of the neck and opening a direct airway through an incision in the trachea...
. It is the second most common facial birth defect after clefts, with an incidence in the range of 1 in 3500 to 4500 . Hemifacial microsomia shares many similarities with Treacher Collins syndrome
Treacher Collins syndrome
Treacher Collins syndrome , also known as Treacher Collins–Franceschetti syndrome, or mandibulofacial dysostosis is a rare autosomal dominant congenital disorder characterized by craniofacial deformities, such as absent cheekbones. Treacher Collins syndrome is found in about 1 in 10,000 births, ....
.
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 fetalFetus
A fetus is a developing mammal or other viviparous vertebrate after the embryonic stage and before birth.In humans, the fetal stage of prenatal development starts at the beginning of the 11th week in gestational age, which is the 9th week after fertilization.-Etymology and spelling variations:The...
stage of pregnancy
Pregnancy
Pregnancy refers to the fertilization and development of one or more offspring, known as a fetus or embryo, in a woman's uterus. In a pregnancy, there can be multiple gestations, as in the case of twins or triplets...
at approximately 4 weeks of gestation, when some form of vascular problem leads to clotting and a poor supply of blood
Blood
Blood is a specialized bodily fluid in animals that delivers necessary substances such as nutrients and oxygen to the cells and transports metabolic waste products away from those same cells....
to the face. This can be caused by a physical trauma, though there is some evidence of it being hereditary
Heredity
Heredity is the passing of traits to offspring . This is the process by which an offspring cell or organism acquires or becomes predisposed to the characteristics of its parent cell or organism. Through heredity, variations exhibited by individuals can accumulate and cause some species to evolve...
. 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(microtiaMicrotia
Microtia, also called microtia-anotia, is a congenital deformity where the pinna is very small and underdeveloped or absent . It can be unilateral or bilateral . It occurs in 1 out of about 8,000–10,000 births. In unilateral microtia, the right ear is most commonly affected...
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
Gestational age
Gestational age relates to the age of an embryo or fetus . There is some ambiguity in how it is defined:*In embryology, gestational age is the time elapsed since conception. This interval is also termed fertilisation 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.
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.Patients can also benefit from a Bone Anchored Hearing Aid
Bone Anchored Hearing Aid
A Bone-anchored hearing aid is a type of hearing aid based on bone conduction. It is primarily suited to people who have conductive hearing losses, unilateral hearing loss and people with mixed hearing losses who cannot otherwise wear 'in the ear' or 'behind the ear' hearing aids...
(BAHA).
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 FoundationLittle Baby Face FoundationThe Little Baby Face Foundation provides free facial surgery for children born with facial deformities, including microtia, atresia, cleft lip and palate, facial palsy, hemangioma and hemifacial microsomia...
.