What is hemifacial microsomia?
Hemifacial microsomia (HFM), also called craniofacial microsomia (CFM), is a
birth defect that occurs when a part of the face appears small or
underdeveloped. It primarily affects the:
The severity of the underdevelopment varies greatly. Most people with this
condition have differences in the size and shape of facial structures from one
side of the face to the other. This is called facial asymmetry. Others might be
affected on only one side of the face. According to the National Institutes of Health (NIH), about
two-thirds of people with HFM have different abnormalities on both sides of the
Those with HFM may also have abnormalities in other parts of the body. HFM
is the most common facial birth defect after clefts.
What are the symptoms of hemifacial microsomia?
The primary symptom of hemifacial
microsomia is an abnormal appearance. Some deformities are easily noticeable
and others are less noticeable. The most common deformities include:
- one side of the face being smaller than the
- a small or missing ear
- a small flap of skin over the ear
- an underdeveloped ear canal
- an overly wide mouth
- small bones of the cheek or jaw
- growths around the eye
Other complications from HFM include
spinal malformation, abnormal kidneys, and heart defects. Some children also
have limited muscle movements, difficulty opening the mouth, or poor alignment
of the teeth. Nerve problems or hearing difficulties are also common.
This study investigates the increased risk of social and
emotional difficulties for people with HFM. It shows that, compared to their
peers, they are:
- less socially adept
- less socially accepted by peers
What are the risk factors of hemifacial
HFM occurs in somewhere between 1 in 5,600
and 1 in 26,550 newborns, according to the NIH. This range may be an underestimation because
doctors don’t agree on the criteria for diagnosis, and because mild cases may
Adults with HFM have a 3 percent chance of
passing the condition on to their children, according to FACES: The National Craniofacial Association. Parents who’ve had one child with HFM have a 0 to
1 percent chance of having another child with the condition.
The disorder occurs about 50 percent more
often in males than females.
What causes hemifacial microsomia?
A developing embryo has six pairs of
pharyngeal arches, which develop into the muscles, arteries, nerves, and
cartilage of the face and neck. The first and second arches, called the
branchial and visceral arches, develop into the lower jaw, nerves and muscles
used for chewing and facial expression, and parts of the ear. Hemifacial
microsomia occurs when these first and second pharyngeal arches don’t develop
properly. Why this occurs is unknown.
Research attempts to study a potential
genetic cause of HFM. It looks for a duplication or deletion of genetic
material in people with HFM. There are some instances of multiple family
members with the disorder. According to the NIH, in most cases only one person in a family has the
condition. More research needs to be done on the cause of the disorder.
How is hemifacial microsomia diagnosed?
To diagnose hemifacial microsomia, your
child’s doctor will review their medical history and perform a physical exam.
During the exam the doctor will look closely at their:
To get a better look at the structure
of your child’s face and head, a doctor may consult a geneticist or order
tests, such as:
To see if other parts of your child’s
body are affected by the condition, your doctor may order other tests, such as:
- renal ultrasound for the kidneys
- X-ray of the top of the spine to look for
differences in how the bones fit together
- echocardiogram to look at the heart
Heart deformities are rare in children
with HFM. Kidney issues and cervical spine issues both occur in about 10 to 15
percent of children with HFM, according to the Seattle Children’s
How is hemifacial microsomia treated?
Treatment for hemifacial microsomia
will depend on the severity of the condition and whether the child suffers from
other ailments as a result of the condition. Reconstructive surgery may be
performed, but it might be postponed until the child is older and more fully
formed. Surgery may not be necessary but chosen for cosmetic reasons.
The following are some examples of
treatments that address abnormalities in different areas:
- Ears: Surgery to correct the ears may be done
around ages 6 to 8, when the ears have reached their adult size. A hearing test
may be performed to see if the ear structure is underdeveloped and disrupting
- Face: Grafts of tissue or muscle may be used to
fill out underdeveloped cheekbones, using either the child’s own tissue or
- Cleft lip: Surgery may be performed at 3 to 4
months of age. Cleft palate surgery may have to wait until 1 year of age.
- Feeding and breathing: A small jaw or cleft
palate can cause difficulty eating and breathing for an infant. Surgery may
need to be performed to reposition their tubes or jaw.
What is the outlook for hemifacial microsomia?
Hemifacial microsomia may cause physical complications. Some children with
difficulty eating or breathing must be monitored closely. Others may have minor
troubles throughout life with speaking, hearing, or facial movement, especially
if they don’t seek treatment.
Despite physical and emotional issues associated with the condition, most
people with HFM go on to live healthy and fulfilling lives, regardless of the
severity of their condition and whether or not they need surgery or treatment.