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About Pierre Robin Sequence

Pierre Robin Sequence: 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: Difficulty breathing – mostly caused by the tongue falling backwards and blocking the throat. Difficulty eating – mostly related to the airway problems, but can also be the result of a delay in the neuromuscular development of coordinated swallowing. Decreased hearing – with a fluid build up behind the eardrums, or otitis media (which is easily treated, but left alone may lead to hearing loss). Teeth – rarely, there may be missing teeth. 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. Repositioning. In my opinion, too many centers needlessly rush into surgery when most babies could have been managed adequately without operating, even those who have required intubation (putting a breathing tube into the windpipe). Often, surgeons will only recommend to parents cutting the bones of their baby’s lower jaw, and placing distraction devices to lengthen the jawbones. Many parents are told that this is the single best option to prevent a tracheostomy. I would not want this treatment for my own child, and I believe that it is critically important that every effort be made to first try to treat every baby with smaller treatments, whenever possible. Large studies have shown that the majority of children with isolated Pierre Robin Sequence can be treated without any surgery, and exceedingly few ever will need tracheostomies. The first thing to try is to simply position the baby correctly in the “prone position,” which means on the baby’s stomach. This is the opposite of what the American Academy of Pediatrics recommends with their “Back To Sleep” campaign, which is aimed at reducing the incidence of SIDS. Nevertheless, this it is precisely what is necessary for a child born with PRS. It is important that the baby born with a small lower jaw be positioned so that gravity can pull the tongue forward instead of backwards, which is what happens when an infant lies on his or her back. This treatment requires some specialized feeding techniques, and if this positioning works well, the baby will need to go home on a monitor. Nasopharyngeal airway. If simple re-positioning does not work, then the next step is to place a nasopharyngeal airway. This is a tube that goes into the nose, and past the tongue, in order to create an unobstructed breathing pathway. It is very important that this tube be of the correct size, because a tube that is too big may eventually cause scarring inside the nose that can permanently narrow the nasal passage (this is referred to as “stenosis”). Some doctors recommend alternating the tube from side to side, every week or so. This tube has been left in place for up to 6 months, according to some studies. Typically, these tubes are only needed for a month or two because the lower jaw grows fairly quickly in the first year of life. Lip tongue adhesion. The next step to consider, if placing a nasal tube is not a workable option, is a small operation called a lip-tongue adhesion. This procedure temporarily attaches the front tip of the tongue to the inside of the lower lip, in order to keep the tongue from falling back and blocking the airway. It is a completely reversible operation, and typically, the lip and tongue are detached at the same time that the cleft palate is repaired at 9-months of age. This operation does not prevent the baby from taking a bottle (however, there are some general feeding issues associated with PRS that are discussed below). Prior to performing this quick operation, I recommend that an ENT perform an examination in the operating room to make sure that the baby does not have tracheomalacia (a condition in which the cartilage that normally holds the airway open is immature, and is softer than it should be, so that the airway collapses easily). If an infant does have tracheomalacia, the best option may be to proceed with a tracheostomy, because all other treatments will not work well. Fortunately, most infants with PRS do not have tracheomalacia. There are no long-term complications from performing a lip-tongue adhesion. The most common complication reported after this operation is that the repair falls apart. This can be avoided by placing extra supportive stitches at the time of the repair. When should jaw distraction be considered? I do not believe that there is any indication for performing distraction for babies born with PRS. There have been studies published where surgeons have done a number of cases of jaw distraction in infants with PRS, and have concluded that this is the best operation for PRS because it prevents tracheostomies. However, there are a number of things that these studies do not tell us. To begin with, many experienced surgeons argue that overwhelming majority of patients in these studies may have done just fine without this operation (based on other studies showing that treatments like nasal airways and lip-tongue adhesions have excellent results). Perhaps the most significant problem with jaw distraction in infants with PRS, is the significant complication rate with this procedure. Complications include, but are not limited to: needing to replace the device in the operating room once it has been put on because the device fails or pins loosen, permanent scars on the child’s face, possible nerve damage, and injury to permanent teeth. This last complication is pretty much inevitable when any screw or pin is put into an infants jaw. A baby’s small jaw is basically filled up with the two rows of teeth. Anything attached to the jaw can injure these tooth buds, and parents will not notice any problems for 10 to 12 years after the operation when the permanent teeth are supposed to have come in. The routine use of jaw distraction in PRS is not yet 10 years old, so infants treated with distraction are not yet old enough to show these problems. When permanent teeth do not erupt, then dental implants (metal screws are surgically placed into the bone of the jaw, on top of which an artificial tooth is attached) may be required in teenage years, and there is no guarantee that these will last a lifetime of 80 years, or longer. Why accept these problems, when there are so many other good options? Although I recognize that many craniofacial centers recommend jaw distraction in babies with PRS, when I look at the pros and cons, it is simply not an operation that I would select for my own child. 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).

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Monday, July 23, 2012

Bubbles!!!

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