Micrognathia and Pierre Robin sequence

What is Micrognathia and Pierre Robin sequence?

Micrognathia is a smaller than normal jaw, often the lower jaw or chin. Micrognathia may be part of a syndrome, which is a condition where more than one body system is involved. A syndrome may be inherited (passed down from the parents) or come about spontaneously.

Pierre Robin (Pee-air; Ro-ban) sequence refers to a combination of small jaw, a normal tongue that is crowded at the back of the throat and difficulty with breathing. Sometimes there is a wide cleft palate (hole in the roof of the mouth). It is not clear why this occurs, but it may happen because of some problem with development early in pregnancy. 

There are several reasons why the jawbone may not develop normally:

  • Positional deformation (the chin is pressed against the chest of the baby) 
  • Intrinsic hypoplasia (restricted growth)
  • Neurologic or neuromuscular problems (reduced movement related to muscle or nerve involvement)
  • Connective tissue disorder (reduced movement related to connective tissue problems of the jaw)

The most important issue is that the airway may be blocked. Sometimes it is difficult to appreciate it in the early days after birth, and the struggle with breathing becomes more apparent a few days or weeks later. These babies often have difficulty gaining weight because they are using so much energy just to breath.

There are mild cases and severe cases. In mild cases, the airway may be improved by placing the baby on his or her stomach, and having gravity move the tongue a little forward. Even a small amount often helps. In more severe cases, a number of tests can be employed to help understand the severity of the problem, and make sure there are no other issues in the airway. Ultimately, some children may require surgery, including tongue-lip adhesion, mandibular distraction or tracheostomy. In every case, the child requires intensive care until the full extent of the problem is understood.

How common is Pierre Robin sequence, and what causes it?

Pierre Robin occurs in about 1 per 8,500 live births. It occurs equally in males and females. We usually can not know the cause of Pierre Robin sequence, but we do know it is not caused by anything the mother did or did not do during pregnancy.

Prenatal diagnosis of Pierre Robin sequence

Doctors may see a small chin on a profile view of the face during a routine ultrasound. If your doctor suspects this, he or she will pay particular attention to the growth of the chin throughout the remainder of the pregnancy. 

When a smaller chin is noted, because of the increased likelihood of other birth defects, your doctor likely will refer you to a maternal-fetal medicine specialist (a doctor who is specially trained to manage high-risk pregnancies). This doctor will perform a more detailed ultrasound to look closely at your baby for other birth defects. Some doctors also may want to do an MRI at some time during the pregnancy to examine your baby’s palate.

How does Pierre Robin sequence affect my pregnancy?

If your doctor suspects a problem with your baby, he or she will likely refer you to a maternal-fetal medicine specialist. The maternal-fetal medicine specialist may recommend additional tests:

Targeted ultrasound: The doctor will perform a targeted ultrasound to evaluate your baby for any other problems, paying special attention to the heart and skeleton. 

Amniocentesis: When micrognathia is suspected before your baby is born, we may recommended evaluation of the chromosomes. This is done with a genetic test called an amniocentesis. The doctor will discuss risks and benefits of this test with you before it is done. 

Fetal echocardiogram: Because of an increased risk of heart disorders seen with micrognathia, your doctor may recommend a fetal echocardiogram. The echocardiogram is an ultrasound that looks at the heart's anatomy, blood flow and circulation. A pediatric cardiologist would perform this test before your baby is born and maybe again after birth to confirm what they suspect initially on prenatal views. 

How does Pierre Robin sequence affect my baby?

A baby who has been diagnosed before birth with micrognathia should be delivered at a tertiary care center because of possible difficulties with breathing at birth. A neonatologist or a pediatric anesthesiologist should be available to assist in the resuscitation efforts in the delivery room. 

Often, positioning and/or a nasal airway are enough to keep your baby's airway open, but a tube may need to be inserted to help your baby breathe. Putting in a tube for a baby with micrognathia can be difficult because of the altered anatomy.

Even more rarely, a tracheostomy tube may need to be placed in the delivery room because the baby’s anatomy does not provide an adequate airway. A tracheostomy is a surgery that creates an airway through the front of the neck.

Delivering your baby 

If there are concerns about your baby’s airway, plans may be made for you to deliver your baby in a Children's Hospital of Wisconsin operating room with a pediatric ear, nose and throat doctor available to help with the airway. The delivery rooms at Froedtert & The Medical College of Wisconsin Froedtert Hospital Campus are located within Children's Hospital, which makes access to the doctors needed to care for your baby very easy. The delivery rooms are just an elevator ride away from the Neonatal Intensive Care Unit, where your baby will be treated.

What are the biggest concerns for my baby after birth?

The two biggest issues for babies with Pierre Robin sequence are breathing and feeding issues. 

Breathing issues: Babies with a small jaw and tongue that are pushed back may have difficulty breathing. If your baby has difficulty breathing, you may meet a team of specialists that includes:

  • An ear, nose and throat doctor
  • A craniofacial/plastic surgeon
  • A pulmonologist (a lung and breathing specialist)

Possible treatment procedures

Your team may recommend different positions to help your baby’s breathing. These positions, such as sleeping on the stomach, will be tried under safe monitoring. Another way to keep the airway open is with a special device placed in your baby's mouth on top of the tongue to hold it in place and keep it from blocking the airway while he or she sleeps

Also, your baby can be evaluated to see if one of three procedures may be needed:

  • Tongue-lip adhesion
  • Mandibular distraction
  • Tracheostomy (if the first two procedures don't work)

Tongue-lip adhesion involves sewing the tongue to the lower jaw to make it more difficult to block the airway, especially the nasal passage.

Mandibular distraction can help the lower jawbone to grow. This is a surgical procedure in which a special appliance is inserted to literally stretch the jawbone over a number of days to weeks. A metal device is placed into the bone and extensions on the outside allow for daily stretching of the bone and soft tissue. The part of the device that extends out to the skin has a piece that may be turned with a key. This will allow the piece of the device in the bone to stretch the bone and tissue in the jaw. By using this device, no bone grafts are needed and doctors may be able to avoid a tracheostomy.

If a distraction device is used, care of the site will be reviewed with you as well as signs and symptoms of complications and device malfunction. The site needs to be kept clean and dry for healing and to prevent infection. 

A tracheostomy is a surgical procedure that places a hollow tube into the windpipe to create an airway. The tube is placed in the lower middle portion of the neck. The baby will breathe through this tube.

After a tracheostomy, babies will have more secretions because of the surgery and the tube that is in the airway. Frequent suctioning may be necessary. 

Oxygen can be provided through the new tracheotomy tube. The air should be humidified to keep the secretions loose. If the mucous is too thick, it can form a plug that may block the tube. This is life threatening. The tube is left in place for five to seven days to allow for healing. Then, the tube will be changed and can be switched to a metal tube with an inner cannula. This inner cannula can be removed and cleaned periodically, which helps keep the tube clear of secretions and maintain the airway. The surgical opening needs to be kept as clean and dry as possible to ensure that the site does not become infected. If the plan is for your baby to go home with a tracheostomy, the home care teaching will begin right away. You also will need to begin to prepare your home with the equipment necessary to care for your baby. Before your baby goes home, you will learn about all equipment, emergency procedures and daily care. 

Concerns about feeding

Feeding is the second major issue with these babies. The cleft palate, in combination with the small tongue, prevents a baby from developing effective suction. This makes it hard for them to take in enough calories to grow. It also means breastfeeding may be unsuccessful. Breast milk or formula can be placed in a bottle to be given to the baby. It is a matter of trial and error to find out which nipple, hole size in the nipple and feeding position works best for your baby. 

When feeding, positioning the baby sitting and tipped slightly forward can help keep the tongue out of the way. However, it is sometimes very difficult to keep the tongue down to get the bottle nipple in the mouth. Sometimes, a feeding tube placed into the stomach is needed to ensure that the baby gets enough food. The placement of this gastrostomy tube is done in surgery. The tube is placed directly into the stomach through a small hole made in the abdomen. 

If a gastrostomy tube is necessary, the surgical site must be kept clean and dry to help healing and to prevent infection. Before we begin feedings through the tube, we give the gastrointestinal tract time to recover from surgery. We will teach you how to care for the tube and insertion site (also called a stoma) and how to feed your baby through this tube before he or she goes home. 

Will I be able to help care for my baby after surgery?

Yes. Please ask your baby's nurse about ways to interact with and care for your baby. 

If you had planned to breastfeed your baby, you can begin to pump breast milk while you are still in the hospital. A lactation consultant can assist in answering your questions. Your milk will be frozen and stored in the Neonatal Intensive Care Unit until your baby is ready for it. The NICU has breast pumps and private rooms available to you when you are visiting. 

When can my baby go home?

Your baby will go home when he or she is able to keep his or her airway open and eat enough to grow and gain weight. It’s hard to predict the length of stay for these babies because of the wide variation in the type of interventions that may be needed. 

Many babies with this condition will go home with a variety of equipment, including an apnea monitor. As the parent, part of the discharge planning involves learning all you need to know to care for your baby at home. 

If your baby needs surgery, he or she will need time to recover and learn to eat enough to grow. Expect a minimum of 1 to 2 weeks for those minimally affected and 4 to 6 weeks for those who require a gastrostomy tube and/or tracheostomy. The length of stay can also be affected by associated anomalies.

What should I expect long-term?

The survival rate of a child born with Pierre Robin sequence that does not have other problems is high. The most likely cause of death for these children is related to a blocked airway and/or aspiration. The mandible usually has grown sufficiently by 6 to 18 months of age, whether distraction is used or not, so that the airway problem is not as critical of an issue. Distraction may be used later in some children to help make up for ongoing slow growth.

The other complications are related to surgery (cleft palate repair, mandibular distraction, gastrostomy or tracheostomy). The incidence of fatal complications related to surgery are extremely rare. Babies with a tracheostomy have a higher death rate than others, but this may be due to other complex health issues. 

Because Pierre Robin sequence is often a cleft-related disorder, these children require cleft palate repair by a craniofacial surgeon around the time of the first birthday. Also, because of the cleft palate, they are much more prone to fluid buildup behind the eardrum, which can affect hearing. This fluid buildup can lead to ear infections. Therefore, these children need long-term follow-up with ear, nose and throat specialists and an audiologist. The audiologist specializes in testing the hearing of infants and children. 

The cleft palate can cause problems with speech. Children with a cleft palate also need follow-up with a speech pathologist and may require speech therapy.

We will refer you to a geneticist, which is a specialist who takes care of children with syndromes and genetic problems. Pierre Robin sequence can be part of a more complex syndrome. If we discover that your baby has a syndrome, there is an increased risk of future children being affected. Some syndromes also need follow-up by other specialists, including an ophthalmologist for vision issues.

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