What is hemifacial microsomia?
Hemifacial microsomia is a common congenital facial difference that causes asymmetric development of the face. Hemifacial has been called many terms such as Goldenhar syndrome and oculo-auriculo-vertebral spectrum. They are all the same condition. This condition may affect all structures of the face, but most commonly causes asymmetry of the eyes, jaws, ears, muscles/nerves that allow a patient to smile, and the soft tissues of the face.
What causes hemifacial microsomia?
Researchers do not yet know the cause of hemifacial microsomia for certain. The leading theory is that an abnormality or injury to an artery in the head during development leads to abnormal development of the affected structures. Most cases of hemifacial microsomia are not genetic or inherited. There are other conditions similar to hemifacial microsomia such as Townes-Brocks syndrome and which can be inherited.
What are the symptoms of hemifacial microsomia?
The most obvious symptoms of hemifacial microsomia are the visible deformities and facial asymmetry. The condition may affect both sides of the face and is called bilateral hemifacial microsomia, but typically one side is more severely affected than the other.
The most common abnormality in hemifacial microsomia is asymmetry of the mandible or lower jaw. Asymmetry of the jaw will cause a cant of the teeth that is visible with smiling, pointing of the chin off to one side, and asymmetry in the lower face. Children with significant deformities of the jaw, particularly bilateral cases, may develop obstructive sleep apnea (OSA) or Pierre Robin sequence.
The second most common abnormality in hemifacial microsomia is asymmetric development or absence of the ears. Patients may have one ear that is slightly smaller and/or more prominent than the other ear. More severe cases, a condition called microtia, may have a small skin structure where the ear lobe was supposed to form and no ear canal. The most severe cases have no ear structures present. Patients without an ear canal may or may not have a normal middle ear for hearing, but often have the nerves needed to hear out of the affected ear.
Patients with hearing loss in one ear can hear, but often have difficulty locating sounds. Your child should be taught the importance of looking both ways when crossing the street.
Severe cases of hemifacial microsomia may have asymmetry in the size or position in the eyes. Additionally, some patients are born with a dermoid cyst of the linings of the eye. This is a benign condition, but may result in imbalance of the muscles that move the eye.
Other asymmetries of the face may be caused by the presence of less fat in the tissues of the cheeks and asymmetries of the muscles and nerves that move the face. Your plastic surgeon will assess these conditions and make recommendations. Sometimes the muscles of the palate do not work symmetrically and this can affect speech.
More severe cases of hemifacial microsomia may have abnormalities outside of the head and neck. These most commonly include abnormalities of the bones of the spine, kidneys, and heart.
How are patients with hemifacial microsomia evaluated?
Evaluation and treatment of hemifacial microsomia requires a coordinated team of specialists. This includes a plastic surgeon, a pediatric ENT specialists, a pediatrician, a geneticist, an ophthalmologist, a pediatric dentist, an orthodontist, an audiologist, a speech therapist, and a social worker. All of these specialists will evaluate your child and coordinate a comprehensive plan for their care.
As your child grows or when surgery is being considered, it will be necessary to determine what underlying anatomy is causing their deformity. Your surgeon, dentists, or orthodontist will order appropriate X-rays or a CT scan to obtain the information they need.
Children with microtia will require regular testing by an audiologist to make sure they are hearing appropriately and that equipment such as hearing aids are working well for them.
Children with significant deformities of their jaws, problems hearing, or malfunction of their palate may have difficulties feeding or speaking normally. A thorough evaluation by a speech therapist will help identify these problems and determine what treatments are necessary to improve their function.
How is hemifacial microsomia treated?
Hemifacial microsomia often requires surgical procedures to treat the various components of your child’s facial difference. The technique and time at which it should be performed are determined by the severity of the deformity and your child’s medical condition.
The deformities affecting the jaws cover a broad spectrum. Some patients have minor asymmetry that is not noticeable during every day conversation. Other patients are born without a normal temporomandibular joint (TMJ) and have a small jaw that causes airway obstruction or Pierre Robin sequence. Minor cases may not require surgery.
The best time to treat jaw asymmetry is after your child is done growing later in their teenage years. Orthognathic surgery on the upper and lower jaws allows the surgeon to place the jaws where they should be located without the risk of your child “outgrowing” their correction. Our surgeons use the latest 3-dimensional imaging techniques and computer assisted planning to prepare for this operation.
In children with more significant jaw deformities, waiting until a child is fully grown may not be an option. Children born without a temporomandibular joint (TMJ) need one created. This is typically done between the ages of 8-12 years old. Your surgeon may use the technique of distraction osteogenesis, a rib bone, or a leg bone (fibula) to create a new joint.
Patients will often require orthognathic surgery later when they have finished growing. Patients with Pierre Robin sequence or severe sleep apnea may need jaw surgery performed before they have grown. These operations are typically done with a technique called mandibular distraction when the bone is gradually stretched using either an external or internally buried device. This technique can be performed on newborns or fully grown adults.
Many centers perform mandibular distraction on children 8-12 years old in the hopes of preventing future surgery. Evidence now suggests that patients tend to outgrow these corrections by the time they are teenagers. Early surgery is still an option for patients with sleep apnea or significant stress due to bullying or pear pressure. Your surgeon will discuss this with you and determine what treatment is best for your child.
Ear deformities in hemifacial microsomia are variable. Patients with an ear that is slightly asymmetric or prominent may benefit from an otoplasty procedure to create normal folds and reduce the ear’s prominence when they are old enough to discuss their desire to have surgery. Patients with significant asymmetry or microtia require a new ear to be constructed.
Most patients with microtia can have an ear created for them around 8-10 years of age. By this time, most patients are big enough that there is enough cartilage in the ribs to create an entire ear and the children are mature enough to undergo the process. Most cases of microtia can be reconstructed in 2 operations. Many patients would benefit from a small “touch-up” operation afterward to maximize their result. More severe cases require 3 or 4 operations to complete the construction of a new ear.
The first operation in this process requires the surgeon to carve an ear from rib cartilage and place this where the missing ear should be located. The second operation is performed 6-12 months later and involves elevating the ear so it sticks out from the head. This is done using tissue taken from the scalp (TPF flap) or behind the ear and a skin graft taken from another location.
Most children with microtia will require surgery to help them hear. Head band hearing aids are very useful in small children but eventually most families consider placing a bone anchored hearing aid (BAHA) as a more permanent solution. Some patients are a candidate for creation of a new ear canal, canalplasty. This is procedure performed by an otology specialist and they can help determine if your child is a candidate for this surgery.
If you are considering either of these procedures, discuss them with your plastic surgeon. They are both valuable procedures, but if they are performed before ear reconstruction surgery they may increase the risk of complications or compromise the outcome of ear reconstruction.
Some patient with hemifacial microsomia are born with congenital facial nerve palsy. These patients may have difficulty closing their eye or might have slight asymmetry of their smile. Discuss these conditions with your surgeon. They will tell you if a procedure is appropriate to improve these conditions. Patients with more significant facial nerve palsy may not be able to move their face and smile. Various operations are available to improve this condition.
Most commonly a small muscle (gracilis muscle) is taken from the muscle and transferred to the face. This muscle is connected either to the facial nerve on the other side of the face, or to a nerve used for chewing. The gracilis muscle is connected to the corner of the mouth and allows the patient to move their cheek and create a smile. Alternative procedures include using one of the muscles that moves the lower jaw for a similar effect.
Your surgeon will assess your child thoroughly and help you select the best operation for your child. Surgery for facial reanimation is typically performed when children are 7-8 years or older. Patients must be mature enough to perform the exercises needed in order to “learn” to use their new smile.
Patients with hemifacial microsomia often have asymmetry of the soft tissues of the face. Structural fat grafting allows us to take fat from other areas of the body using techniques similar to liposuction and transfer it to the face. Typically 60-80% of the transferred fat survives, and repeated procedures are needed to achieve our final goal.