Hemifacial Microsomia
Hemifacial microsomia is the second most commen congenital facial anomaly after cleft lip / palate with a reported incidence of about 1 in 5600 live births. The possible cause involves the early developing structures of the head and neck (branchial arches), occuring very early in the pregnancy (about 30-45 days). This is not related to anything the mother did or did not do during pregnancy. It is thought that it results from a hemorrhage from the developing stapedial artery which produces a hematoma in the area of the branchial arches. This may explain the variability in the way it presents. Children may have a mild form that includes mild facial asymmetry and microtia (ear deformity) to a more severe form that includes additional eye, vertebral, cardiac, and renal malformations (also known as Goldenhars syndrome).
Physical Features
The jaw abnormality in children with hemifacial microsomia may range from a small but normally shaped ramus and condyle ( parts of the jaw bone) resulting in a mild asymmetry to complete absence of these structures resulting in a more severe jaw deformity. Dentally, there is shifting of the teeth in the mild case to severe crowding and possible missing or impacted teeth in the more severe cases. The smile is usually slanted with the affected side being higher than the unaffected side. The child's chin may also appear slanted. The soft tissue ( skin and fat) in this area may be deficient also. Small skin tags may be present on the cheek or by the ear. Ear deformities can also vary from mild malformations to complete absence of the ear. Affected children may also have an associated cleft lip/palate or lateral lip cleft (macrostomia).
Evaluation and Treatment
As with other craniofacial deformities , evaluation and treatment requires a multidisciplinary team working closely together with the family to attain the best functional and aesthetic result possible.
Because of the jaw abnormality these infants may be at risk for breathing and feeding problems and need to be evaluated by a specialist if there are any indications of airway compromise or failure to gain weight. Occasionally a tracheostomy and/or gastrostomy are needed to help with breathing and feeding. The techniques found in the Feeding section may be helpful with these infants.
An ophthamologist should be involved in the evaluation and treatment if eye abnormalities are present and close attention to maintaining optimal hearing status is important.
An orthodontist will assess the growth of the facial structures and monitor eruption of the teeth. At appropriate times various orthodontic interventions will be initiated.
Treatment
The timing to correct each component of the deformity may vary depending on the severity of the presenting conditions and the philosophy of the Craniofacial team.
If a cleft lip/palate or macrostomia is present, surgical repair begins at about 3 months of age and skin tags may also be excised.
Correction of the jaw usually comes before ear reconstruction and involves a combination of orthodontic treatment and surgical correction. The mandible (jaw) may be lengthened through distraction osteogenesis or through a combination of surgical cuts in the bone with bone/cartilage grafts . This is usually done when the child is 4-5 years old or sooner if needed to facilitate removal of a tracheostomy.
External ear deformities are addressed between 5-7 years of age.
After skeletal asymmetry is corrected, the soft tissue deficiency is addressed and treatment may be indicated in some cases.
