What are the other Names for this condition? (Also known as/Synonyms)

• First and Second Branchial Arch Syndrome
• Lateral Facial Dysplasia
• Oral-Mandibular-Auricular Syndrome

What is Hemifacial Microsomia? (Definition/Background Information)

• Hemifacial Microsomia (HFM) is a condition in which one side of the face is less developed than the other side, leading to asymmetry between the two halves of the face
• Hemifacial Microsomia is part of a group of disorders collectively known as “craniofacial microsomia”. It constitutes the most common facial birth defect after cleft lip and palate
• The exact cause of Hemifacial Microsomia and its contributing risk factors are unknown. However, several theories have been proposed to explain HFM development
• The characteristic feature of Hemifacial Microsomia is facial asymmetry, in combination with physical abnormalities that affect the ear, eye, mouth and jaws, resulting in hearing, vision, and dental issues respectively
• The diagnosis of Hemifacial Microsomia is made by clinical assessment, based on OMENS (orbit of the eye, mandible or jaw bone, ear, nerves, and soft tissue) abnormalities. Imaging techniques may be used to determine skeletal or dental defects in the affected individual
• Surgical correction of skeletal abnormalities is a commonly considered treatment method for HFM. Ear reconstruction may be required, if it is abnormal in shape or is missing
• The life expectancy of individuals with Hemifacial Microsomia is usually normal, unless the symptoms are severe, with the involvement of kidneys, heart and vertebrae

Who gets Hemifacial Microsomia? (Age and Sex Distribution)

• Hemifacial Microsomia is reported to occur at a frequency of approximately 1 in 4000 newborns
• Although reported from many parts of the world, the exact global prevalence is not discernable from current scientific literature
• Both male and female genders are equally affected by HFM

What are the Risk Factors for Hemifacial Microsomia? (Predisposing Factors)

The risk factors for being born with Hemifacial Microsomia are not clearly known. However, the following risk factors have been suggested:

• Use of medications, such as pseudoephedrine, ibuprofen, aspirin, and accutane, during pregnancy
• Multiple pregnancy
• Bleeding in the second trimester of pregnancy
• Mother with diabetes
• Use of assisted reproductive technology to get pregnant
• A family history of HFM
• A family history of Goldenhar-Gorlin syndrome; HFM is a symptom of this syndrome

It is important to note that having a risk factor does not mean that one will get the condition. A risk factor increases one’s chances of getting a condition compared to an individual without the risk factors. Some risk factors are more important than others.

Also, not having a risk factor does not mean that an individual will not get the condition. It is always important to discuss the effect of risk factors with your healthcare provider.

What are the Causes of Hemifacial Microsomia? (Etiology)

The exact cause of Hemifacial Microsomia is not known. Nevertheless, the following have been suggested to explain the cause of HFM:

• An interruption of blood supply to the first and second branchial arches within the first 8 weeks of pregnancy
• Deletion of genetic material from chromosomes
• A mutation in an as yet uncharacterized gene
• A combination of genetic predisposition and environmental risk factors, such as the use of certain medications (aspirin, ibuprofen, etc.) and maternal diabetes

In 1-2% of HFM cases, the condition is inherited in an autosomal dominant manner. In rare instances, HFM may also be inherited as an autosomal recessive disorder.

Autosomal dominant inheritance: In this type of inheritance, a single copy of a defective gene in each cell of an individual is sufficient for the disorder to manifest itself. An affected individual inherits the disorder from an affected parent.

Autosomal recessive inheritance: In this type of inheritance, an individual must have both copies of the causative gene to be defective, for the disorder to manifest itself. The affected individual inherits one copy of the defective gene from each parent, who are carriers of the disorder and are typically unaffected.

What are the Signs and Symptoms of Hemifacial Microsomia?

The symptoms of Hemifacial Microsomia may vary in type and severity among affected individuals. Either one or both sides of the face may be affected. The latter is known as bilateral facial microsomia.

The following are some signs and symptoms of the disorder:

• Facial asymmetry
• Flattened cheekbones and forehead; missing cheekbone
• Weakness of facial muscles, facial numbness that may be partial or complete
• Problems with speech
• Underdeveloped eyes, absence of eye, vision abnormalities
• Incomplete closing of eyelids
• Malformed or absent external ear; underdeveloped or absent inner ear parts
• Hearing difficulties (partial or total loss of hearing)
• Skin tags on the ear
• Underdeveloped jaw; missing jaw on one side of the face
• Up-slanted mouth or jaw
• Cleft lip, cleft palate
• Crowding of teeth, difficulty chewing
• Tracheal malformation leading to breathing difficulties

How is Hemifacial Microsomia Diagnosed?

The diagnosis of Hemifacial Microsomia is undertaken on the basis of the following exams:

• Physical examination and an assessment of the presenting symptoms
• Family history evaluation

Assessment of HFM severity based on OMENS classification, by checking for abnormalities in the following parts:

• Orbit (eye)
• Mandible (jaw)
• Ear
• Nerves
• Soft tissues (skin, muscle, fat, tendons, and ligaments)

Other tests and studies may include:

• X-ray and/or computed tomography (CT) scan to check for skeletal malformations
• Eye examinations to check for visual acuity
• Dental examinations
• Hearing tests

Prenatal ultrasound may be helpful in identifying facial and other abnormalities in the developing fetus.

Many clinical conditions may have similar signs and symptoms. Your healthcare provider may perform additional tests to rule out other clinical conditions to arrive at a definitive diagnosis.

What are the possible Complications of Hemifacial Microsomia?

The following are some complications of Hemifacial Microsomia:

• Inability to chew, owing to dental crowding
• Problems with speech development
• Difficulty with breathing
• Involvement of the vertebra, heart or kidneys: Malformation of these structures and organs may impede their normal function
• Reduced quality of life

How is Hemifacial Microsomia Treated?

The treatment of Hemifacial Microsomia may vary for each affected individual, depending on the type and severity of the abnormality. The following are some treatment modalities:

In newborns:

• Breathing support
• In severe cases of malformation, tracheotomy to ease breathing
• Feeding tube to aid in maintaining proper nutrition
• Eye protection using ointments, when there is incomplete closure of eyes

In children:

• A series of reconstruction surgeries for severe ear abnormalities
• Surgical correction of eyelids; repositioning of lower eyelids
• Surgical correction for cleft lip and palate
• Tissue or fat grafting procedures for correcting flat cheekbones or forehead

Distraction lengthening of mandible: In this procedure, a device is implanted in the center of a deficient section of the jaw. The gap thus created allows new bone to develop. The gap is widened gradually to allow new bone to fill the space, till the proper size is achieved. This allows the teeth to grow normally. 

How can Hemifacial Microsomia be Prevented?

Presently, no guidelines exist for prevention of Hemifacial Microsomia, since the exact cause is unknown.

• Maintenance of proper glycemic index in the mother may help prevent the condition in the offspring
• Avoiding medications that are believed to contribute to the development of HFM in the fetus may be considered. Discussing about the same with the healthcare provider (for alternative medication) may help prevent this condition
• Active research is ongoing to understand Hemifacial Microsomia better

What is the Prognosis of Hemifacial Microsomia? (Outcomes/ Resolutions)

• The prognosis of Hemifacial Microsomia is typically good with normal life expectancy in the affected individuals
• However, involvement of the heart, lungs, and vertebrae, may reduce the quality of life, as well as lower life expectancy

Additional and Relevant Useful Information for Hemifacial Microsomia:

Please visit our Congenital & Genetic Disorders Health Center for more physician-approved health information:

http://www.dovemed.com/diseases-conditions/congenital-genetic-disorders/