What is Pierre Robin Sequence?
Pierre Robin Sequence (PRS) is the name given to a condition, which includes a small jaw and a cleft palate. This condition is named for a French physician who in 1923 published an article describing a child with this specific combination of medical problems. As it turns out, Dr. Robin was not the first to describe PRS; nevertheless, his name remains linked to this condition. It is often stated that there are three separate issues with PRS: a cleft palate, small jaw and glossoptosis (a term that was coined by Dr. Robin, meaning lowering or drooping of the tongue). As it turns out, glossoptosis is not an actual problem with the tongue itself, instead is the result of a normal-sized tongue sitting in a smaller than normal lower jaw. When the lower jaw (also called the mandible) is smaller, the tongue ends up being positioned closer to the back of the throat, causing the “glossoptosis.” The cleft palate in PRS is usually different from a “typical” cleft palate in that it is more U-shaped, than V-shaped in appearance. Pierre Robin sequence has been reported to occur in about one out of every 8,500 births, but some believe that it can happen even more commonly. It can either occur as by itself as an isolated Pierre Robin Sequence, or as part of a syndrome that may have a different name.
What causes PRS?
For many years, doctors thought that PRS might be the result of the way the baby was positioned inside the womb. If a baby were to be positioned in the womb with the neck flexed forward, then the chin would be against the upper chest, preventing it from growing. During this time the tongue would be enlarging normally, and this would cause it to push up against the roof of the mouth, resulting in a cleft palate. While this seemed to make sense, as further progress has been made in understanding human genes, we have come to realize that this simplistic theory is probably not correct. Today, geneticists believe that isolated Pierre Robin Sequence may be partly caused by changes in genes. Most recently, it has been suggested that potential problems with two genes called SOX9 and KCNJ2 mRNA might be possibly be related to PRS. However, changes in genes named: GAD67, PVRL1, COL11A1 and COL11A2,have also been noted in children with PRS. It is not clear if the changes seen in these genes cause Pierre Robin, make it more likely to happen, or just happen to occurring at the same time that something else is causing PRS. However, up to 25% of children with PRS will have a family member with a cleft palate, which is a more common association than might be expected if there was no genetic role for this problem.This condition was referred to as Pierre Robin Syndrome until a number of years ago when many physicians began referring to this condition as Pierre Robin Sequence. The reason for this change is that the term syndrome is used when a number of problems are caused by a single issue, such as a gene mutation, whereas as sequence is a term applied when there are multiple problems that have occurred in which one problem leads to another, and then another, etc. Initially, doctors thought that the cause for PRS was that the baby’s head was flexed in the womb, leading to the small jaw and cleft palate, so it made sense to change the name from syndrome to sequence. Given the rapid developments in our understanding of genetics, someday physicians may well end up calling this condition Pierre Robin Syndrome, once again.
What problems do parents need to consider with Pierre Robin Sequence?
The most common associated problems with isolated PRS include:
The first step in the treatment of a child with suspected PRS is to determine if the child actually does have PRS and if so, is it isolated PRS or is it associated with another syndrome. PRS features can occur as part of many different conditions and syndromes, and it is very important that a genetic evaluation and testing be performed. The most common syndrome associated with PRS is Stickler syndrome. Stickler syndrome is sometimes associated with joint problems, arthritis, and with multiple eye issues (including myopia, retinal degeneration and detachment, early cataract formation, and a higher incidence of glaucoma) and this condition needs to be accurately diagnosed so that affected individuals can be closely followed by an ophthalmologist. Less commonly associated with PRS is Velocardiofacial syndrome (also known as: VCFS, 22q11 deletion, or by the older term, Shprintzen syndrome) and Fetal Alcohol syndrome. A genetics consultation is an important part of the initial treatment of a child born with PRS.
What it the treatment for Pierre Robin Sequence?
Difficulty breathing. The most urgent concern for any infant born with Pierre Robin Sequence is to make sure that the baby is able to breathe and get enough oxygen. Most children are initially monitored in a Neonatal Intensive Care Unit, where their oxygen levels can be continuously monitored. Some children require intubation (placing a breathing tube through the mouth into the windpipe) right at birth, and some may need intubation after a few days of trying to breathe on their own and then just tiring out. For those children who have problems breathing on their own, what is the best treatment? Different treatment options include: re-positioning, nasopharyngeal airways, lip-tongue adhesions, tracheostomies and jaw distraction. The following is a discussion of the various possible treatments for breathing problems.
Feeding issues. Many children with PRS will have disorganized swallowing. If there are any signs for this (noisy breathing, choking, sputtering) I will recommend a swallowing study for my patients. This study is to make sure that the baby is not having any “silent aspiration” (when small amounts of formula quietly go down into the lungs, instead of the stomach) while feeding. Aspiration can lead to respiratory infections, or possibly even lung injury. The most common reason for aspiration is that the nervous system is slow in developing, and as a result, swallowing is not well coordinated. I recommend that if a swallowing study shows signs of aspiration, then the breast milk or formula may need to be thickened. If thickening does not prevent aspiration, then a small feeding tube is passed through the nose into the stomach and all food is given though the tube until the swallowing ability matures, which can take weeks to months, depending on the child. This tube does not seem to bother children, and it is effective at preventing formula, or breast milk, from entering the lungs. For those babies who require a nasal feeding tube, I will retest a baby in 12 weeks to see if the swallowing has matured to the point that the feeding tube can be removed. Rarely, children with significant problems are given a gastrostomy tube, which is a tube that goes through the skin of the abdomen directly into the stomach.
Hearing problems. For any child with a cleft palate, there is an increased chance that tubes will need to be placed into the ears. This is because the inner ear does not drain in a normal fashion when there is a cleft. Fluid can build up behind the eardrum that reduces hearing, and that can lead to an increased risk of ear infections. If this fluid (called serous otitis) stays behind the eardrum for an extended period of time, hearing will be decreased, which can delay the development of normal speech. I recommend that babies with cleft palates have their hearing tested more frequently, and any time a child needs to go to the operating room, for any reason, that he or she be evaluated the day before surgery to see if tubes need to go in the ears at the same time.
Appearance issues. Even though the lower jaw is smaller in PRS, the good news is that it grows at a fairly normal rate. I recommend waiting until growth is nearly complete (about 15-years old for girls, and 16-years old for boys) before considering any surgery. If anything is needed, most teenagers will only require placement of a chin implant in order to normalize appearance, and this is only recommend this if the lower jaw is small enough to bother the child; otherwise, nothing needs to be done. Less commonly, if the teeth are not aligned properly because of significantly reduced growth of the lower jaw, the lower jaw can be cut and moved forward (all done from inside the mouth, so that there are no external scars).
How should parents proceed?
In general, I recommend getting more than one medical opinion (see Choosing a Doctor, http://www.thecraniofacialcenter.com/choose_doctor.html). It can be difficult for many families do get a good second opinion when their baby is in a NICU and is not able to be discharged from the hospital to see another doctor. Try to find out if there are other surgeons in the same town or city, and speak with them to make sure that the best treatment plan is developed for your child.
Jeffrey A. Fearon, MD