Hemifacial microsomia is the second most common congenital facial anomaly after cleft lip and palate. It affects about 1 in 5,600 children. The cause of hemifacial microsomia is not known. Children with hemifacial microsomia have an under-development of one side of the face. The effects can be very variable. Often jaws (mandible and maxilla) on the affected side are underdeveloped. Sometimes a normal jaw joint does not form.
The ear may be small and abnormal (microtia) and sometimes the eye is also reduced in size. Occasionally the facial nerve is underdeveloped which causes abnormalities of movement on the affected side of the face. Soft tissues and muscles may be underdeveloped and there is often a widening of the mouth (macrostomia) on the affected side. Hemifacial microsomia is occasionally associated with other congenital anomalies such as cleft lip and palate, certain heart defects and abnormalities of the kidneys.
Specific treatment for hemifacial microsomia is variable because there are so many differences in its presentation. Children with severe hemifacial microsomia are managed within the Craniofacial Team, where there is expertise to support every aspect of their psychological, social and functional development as well, of course, as correcting their deformity. Severe under-development of the jaw can cause breathing difficulties early in life and so early surgery using distraction osteogenesis (a process by which the jaw is gradually stretched to a more normal size) may be undertaken. As a rule however most surgery is delayed until later in childhood because the effects of early surgery are often undone by the abnormal growth processes associated with hemifacial microsomia.
Frequently Asked Questions
Treatment of the mandibular and maxillary deformities often involves distraction osteogenesis, osteotomies and bone grafting. Careful orthodontic treatment is needed to ensure that a normal bite is achieved. The external ear when affected is often reconstructed at approximately 8-9 years of age. Soft tissue deficiencies can be treated by injecting fat or transferring soft tissues from other parts of the body. Treatment of severe hemifacial microsomia is often not completed until late adolescence. Treatment of the more severe forms of hemifacial microsomia may therefore happen over a period of many years. A typical timeline is given below;
0-2 years (at presentation to the craniofacial team)
A craniofacial assessment is undertaken. This may include;
- CT scan
- Breathing assessment (ENT examination and sleep study)
- Hearing assessment
- Feeding assessment
- Speech and language assessment
- Ophthalmological assessment
- Dental assessment
- Plastic surgery assessment
Treatment at this age is usually limited to treating functional problems. It is usual to repair clefts and macrostomia and remove skin tags. If the airway is a problem, treatment may be required for this. In the severest forms, a tracheostomy may be required. Occasionally, other forms of airway support such as a nasal prong or CPAP are used. Most children with hemifacial microsomia do not require any airway support.
During this time, most children with Hemifacial microsomia require careful monitoring. Intervention is undertaken for functional reasons to support the airway, feeding and speech and language development.
As children reach school age, there are often concerns within the family about how they will cope with their facial difference at school. In the first few years of school it is uncommon for children to experience worry about their facial appearance, although teasing may become a problem around the age of 7. It is often very helpful to see a psychologist specialising in craniofacial conditions at this stage. They will be able to help children with coping strategies and advise families and schools.
There are a number of surgical treatments that can be undertaken at this age to help facial form. These include autologous fat transfer to build up areas of soft tissue underdevelopment and distraction osteogenesis to lengthen the underdeveloped side of the lower jaw.
Functional orthodontic appliances may be fitted by the orthodontist to encourage jaw growth. Ear reconstruction is usually undertaken at approximately 9 years of age.
Many children with hemifacial microsomia require surgery to the upper and lower jaw to correct their facial asymmetry and bite. Generally, this cannot be undertaken until the jaws are nearly fully grown around the age of 16-17. It is reasonably uncommon to have to undertake any treatment for functional problems in this age group.
During this phase of growth, the face gradually changes from a childlike shape into its adult form. Children and adolescents become increasingly aware of their appearance.
Orthodontic treatment generally starts once the adult dentition is sufficiently established. At this stage, there is usually a consultation with all of the professionals in the team, in order to make a final treatment plan. As hemifacial microsomia is such a variable condition, this treatment plan may take many forms. In general, an assessment will involve a 3D CT scan and taking impressions for orthodontic study models and 3D steriophotogrammetry (3D photography).
A typical treatment plan would be;
- Age 12+ Orthodontic treatment to prepare the teeth for orthognathc surgery (surgery to the upper and lower jaw)
- Age 15+ Orthognathic surgery to finally treat facial asymmetry.
- Soft tissue augmentation where needed
- Cheek implants may be used to augment the mid face
- Eyelid surgery where necessary
- Age 17+ post-surgical orthodontics