What is it?
Pierre Robin Sequence (“PRS”) refers to a series of events that occur in utero to create specific signs, symptoms and physical manifestations. Typically, a baby with PRS has a small jaw (micro/retrognathia), a large tongue (macroglossia), and some form of respiratory distress or airway compromise. Often, they will also have a cleft palate. There are several theories as to how this occurs. Ultimately, there is some event during gestation that prevents the lower jaw from growing appropriately. This makes the tongue too large for the mouth and forces the tongue into the palate, which can cause a wide u-shaped cleft. These findings can occur on a spectrum from mild to severe, and their effect on the airway can also vary widely. In the majority of cases, PRS babies are easily stabilized by giving them oxygen and keeping them on their stomach (laying on the back allows the tongue to fall back in the throat and block the airway). If this is the case, they generally do well. As they grow and get stronger over the next few weeks, the airway problems resolve. If there is a cleft palate, it will be repaired at 9-12 months of age in the same manner as for a typical cleft. In general, jaw growth tends to catch up with time, and most children will ultimately not need surgery on the jaws.
If the baby is born with more severe respiratory problems, special airways, intubation, or even tracheostomy may be required. The airway issues may also be intensified when the baby is sleeping, or during feeding. This can make it very hard for them to take in enough calories to gain weight. In general, there is a protocol followed for PRS babies after they are born. They will be placed on anti-reflux medication, and a CT of the head will be obtained to look at the anatomy of the jaws, tongue, and airway. They will be evaluated by an ENT physician who will use a scope (special thin lighted camera), to directly look at the airway. This will identify if problems are related to the jaw and tongue, or other parts of the airway. A sleep study will also be ordered to determine if they have apnea related to tongue obstruction, or neurologic problems. The ultimate goal with all of these interventions is providing a safe stable airway for the child so it can breathe, eat, and grow normally. The secondary goal is avoiding a tracheostomy. There are many factors that come into play, and this is not always possible. For certain PRS babies that are not thriving, there may be a surgical treatment option called “mandibular distraction osteogenesis”. Distraction works by gradually moving the lower jaw forward. This stretches the soft tissues and opens the airway, and makes more room for the tongue so that it is not falling back into the throat during eating and sleeping. We are able to offer a distraction for babies that have a small enough jaw that we can move it forward far enough to open the airway without causing a significantly abnormal bite. The child must also have an otherwise normal sleep study and scope.
What happens during surgery and recovery?
At the time of surgery, a small incision is made underneath the jawline on both sides. This tends to heal very well and is generally not noticeable later in life. Then, the tissue is elevated to expose the lower jaw, and cuts are made in the bone on each side. Metal plates are then screwed into the bone on each side of the cut, and these plates are attached to a long metal tube which will come out of the skin behind your baby’s ears. The incisions are then closed with absorbable sutures. After surgery, your baby will need to remain intubated until the jaw has moved enough for them to breathe easily on their own. This usually takes 3-5 days. During this time, the breathing tube will be in the nose. The distractor sites will be cleaned twice daily with peroxide. Starting the morning after surgery, distraction will begin and will be done by our team. There is a screwdriver that attaches to the end of the metal tube. By turning the screwdriver, the metal plates gradually separate the bones of the lower jaw. This is usually done at a rate of 1 mm twice a day. The process is not painful, and most children will not even wake up while it is done. Because the process is so slow, it allows the bone to start to heal as it moves. We generally “overcorrect” the position of the mandible by about 5 mm because it tends to relapse a little with time and growth.
Once the distraction phase is complete, the bone is allowed to heal for about 6 weeks before the hardware is removed. During this time, you should continue to clean around the distractors with peroxide and can bathe your child normally. Occasionally, a mild skin infection will develop around the hardware. This can usually be treated with antibiotics. We will also periodically obtain x-rays and/or CT scans to check the jaw position. After 6 weeks, we will bring your child back to the operating room to remove the hardware. This is done through the same incisions, and you are usually able to go home the next day. There is a nerve that runs along the lower part of the jaw that controls the movement of the lower lip and chin. It is possible that this nerve may be injured or irritated during either of the surgeries, which would make your child’s smile and cry look asymmetric. It is rare for this to be permanent. The nerve usually recovers but may take several months to do so. Distraction is extremely effective at treating airway problems in the appropriate PRS patient, but it is hard to predict exactly how the jaw will grow with time. Some children will need additional surgeries on the jaws later in life to address their bite.