What is Pierre Robin Syndrome?
Pierre Robin sequence (PRS) is a medical condition identified by a combination of three symptoms: a smaller than usual lower jaw (referred to as micrognathia), an abnormal positioning of the tongue where it falls into the throat (known as glossoptosis), and issues with the upper airway. As a result, the person’s small, underdeveloped lower jaw causes the tongue to move back into the throat which can potentially interfere with their ability to breathe. This condition often goes hand in hand with a cleft palate, which is a split or gap in the roof of the mouth.
These characteristics can occur as part of a specific syndrome or on their own. The condition was first noted in 1891, but it was later officially documented by Pierre Robin via a case study of a baby with these traits in 1923.
What Causes Pierre Robin Syndrome?
Pierre Robin sequence (PRS) usually falls into two categories: isolated PRS and syndromic PRS. Isolated PRS, also known as non-syndromic PRS, is linked to changes (mutations) in certain chromosomes (2, 4, 11, and 17). Some research suggests that mutations in the SOX9 or KCNJ2 genes, found on chromosome 17, might affect the growth of face structures and cartilage, and could lead to PRS.
On the other hand, syndromic PRS is when PRS is part of a broader medical condition. This accounts for about 60% of all the PRS cases. Over 34 different medical conditions have been linked to PRS, with Stickler syndrome being the most common one.
Stickler syndrome is known to be the most common condition associated with PRS. In one study, almost half of the patients with syndromic PRS were diagnosed with Stickler syndrome. This happens due to a mutation in genes that impact the formation of collagen, an important protein for our body’s structure. Signs of Stickler syndrome include a flatter middle of the face, skin folds around the inner corner of the eye, detached retina (in the back of the eye), cataracts, hypermobile joints, hearing loss due to nerve damage, along with typical signs of PRS.
Velocardiofacial syndrome occurs due to deletion in a small piece of chromosome 22 or mutation in TBX1 gene that can cause issues in the heart, parathyroid glands, thymus gland, and facial development. Symptoms may include a long upper lip and philtrum (area between the nose and the upper lip), elongated face, slim fingers and toes, underactive thyroid, immune system issues, hearing loss, a specific kind of heart defect called pulmonary atresia, ventricular septal defects (hole in the wall separating the two lower heart chambers), and underdeveloped pulmonary arteries.
Treacher Collins syndrome is caused by mutations in genes TCOF1, POLR1C, and POLR1D. Signs of Treacher Collins syndrome include underdevelopment of the cheek, upper jaw, lower jaw bones, anomalies in the temporomandibular joint (the joint that connects the jaw to the skull), cleft palate, and irregularities in the outer ears.
Risk Factors and Frequency for Pierre Robin Syndrome
Data on PRS is limited, but what we do have suggests that it impacts about 1 in every 8,500 to 14,000 newborns each year.
Signs and Symptoms of Pierre Robin Syndrome
Micrognathia is a condition diagnosed when the lower jaw or mandible is underdeveloped. This usually involves a shorter length of the mandible and a wider angle. Various methods attempt to define and diagnose micrognathia, but none have effectively helped predict which patients will have breathing difficulties as a result.
Glossoptosis is another condition where the base of the tongue moves towards the throat, or the pharynx. Like micrognathia, the severity of this condition and its consequences, such as respiratory distress, can vary greatly. While there’s no standard method for diagnosing glossoptosis, can sometimes be helpful is endoscopy (looking inside the body with a flexible tube) and CT scans to determine how obstructed the airway is because of the condition.
Airway obstruction is a condition that can present itself in various degrees, from severe cases needing immediate breathing assistance after birth, to mild cases that don’t need any intervention. Signs of airway obstruction can range from:
- Abnormal breathing sounds
- Increased use of respiratory muscles
- Low oxygen levels (desaturations)
- Difficulty feeding or swallowing
- Reflux and aspiration (food or stomach acid entering the airway)
- Over time, reduced weight gain, speech difficulties, and neurological problems may arise, leading to increased lung pressure (pulmonary hypertension) and heart issues (cor pulmonale)
While not always present in patients with PRS, the majority also have a cleft palate. This is an opening in the roof of the mouth where the two sides didn’t join together. These are usually shaped like a “U”, but “V”-shaped cleft palates have been reported as well.
Testing for Pierre Robin Syndrome
During pregnancy, an ultrasound might reveal a small lower jaw, a condition known as micrognathia, which could be a sign of a disorder called Pierre Robin Sequence (PRS). The ultrasound might also show excess amniotic fluid or polyhydramnios, which can occur if the baby’s tongue is falling back into the throat (glossoptosis) enough to cause issues with swallowing.
Recognizing these signs prior to the baby’s birth can allow doctors and the parents to plan for potential issues, treatments, and challenges associated with PRS. The medical team, including specialists in maternal and fetal medicine, newborn medicine, anesthesia, and ear-nose-throat conditions, can be prepared for any necessary immediate intervention after the baby’s delivery. It also provides the parents with an opportunity to consider all available options, including ending the pregnancy. Generally, when these signs are seen in an ultrasound during pregnancy, they suggest a more severe form of PRS.
Amniocentesis – a test where a small amount of amniotic fluid is taken and evaluated – can be recommended for women with these ultrasound findings. This is because PRS often goes hand-in-hand with genetic syndromes. A referral to a genetic counselor can provide further guidance and support.
After the baby is born, doctors will evaluate the baby’s condition in the delivery room to establish if immediate interventions like intubation (inserting a tube into the windpipe to aid breathing) or applying pressure to assist with breathing are required. There isn’t a singular, fool-proof test to identify PRS; it often depends on a combination of observations.
Monitoring oxygen levels can provide insight into potential breathing problems, especially during feeding, sleep, or in different positions. Sleep studies or polysomnography can provide a measure of the severity of any disordered breathing events and can help determine when and if intervention is needed. Scopes (nasoendoscopy or bronchoscopy) can help identify any points of obstruction in the airway.
In newborns, doctors also keep a close eye on feeding habits. By keeping track of growth charts and weight gain, they can determine if the baby is having difficulty feeding and might require additional feeding support, such as with a nasogastric tube (a tube passed through the nose and down into the stomach).
Treatment Options for Pierre Robin Syndrome
Pierre Robin Sequence (PRS) is a condition that some individuals are born with. It affects the size and position of the lower jaw, making it smaller and further back from the upper jaw than usual. This can cause difficulties with feeding and breathing. There are various ‘grades’ of PRS, ranging from very mild to more severe.
In cases of mild PRS, the baby might not need surgery. The child can be positioned carefully to ensure the tongue doesn’t block their airway. This is effective in around 70% of mild PRS cases. Another temporary measure can be a device called a nasopharyngeal stent, which can help keep the airway open. However, parents will need to closely monitor their child for any signs of problems, such as pain or issues with the device.
Additional non-surgical interventions include CPAP (Continuous Positive Airway Pressure) and PEBP (Preepiglottic Baton Plate). Both have shown benefits, but can be difficult to use with infants.
There’s some disagreement in medical studies about whether a baby born with PRS can naturally ‘catch up’ in the growth of the lower jaw after birth. Some studies suggest this is possible, while others suggest the jaw remains smaller than average. However, there’s a general agreement that in syndromic PRS – a more severe form – the lower jaw does not appear to catch up in growth.
In severe cases, and all syndromic PRS, there’s often a need for surgery. Only around 10% of cases of PRS require this treatment. Different surgery options include tongue-lip adhesion, mandibular distraction osteogenesis, or tracheostomy.
Tongue-lip adhesion is a temporary measure where the tongue is attached to the lower lip so that it stays in a forward position to keep the airway open. This is often used while waiting for the lower jaw to grow. Some risks of this procedure include injury, infection and potential breathing issues.
Mandibular distraction osteogenesis is a more long-term solution. This procedure involves breaking the lower jaw and using an external device to slowly stretch it, thereby growing the jawbone. Complications can include infection, damage to the nerve in the jawbone, bite issues, and loss of permanent teeth.
Tracheostomy is a surgery that creates a hole in the windpipe through the front of the neck. It’s more likely to be performed on patients with syndromic PRS and those with airway blockages in multiple areas. Although it’s considered the best treatment for protecting the airway, there are still risks, including infection, possible harm to the esophagus and complications with the tube used.
What else can Pierre Robin Syndrome be?
Pierre Robin sequence can often occur alongside several other medical conditions. Here are some conditions that may be present at the same time:
- Velocardiofacial syndrome
- DiGeorge syndrome
- Stickler syndrome
- Treacher Collins syndrome
- CHARGE syndrome (this includes eye defects, heart defects, blocked nasal passages, growth problems, genital abnormalities, and ear abnormalities)
- Fetal alcohol syndrome
- Paediatric cleft lip and palate
- Childhood sleep apnea
What to expect with Pierre Robin Syndrome
Episodes of obstruction can lead to several health problems, including low levels of oxygen in the blood (hypoxemia), slow or shallow breathing (hypoventilation), undernourishment (malnutrition), choked or stopped breathing (asphyxia), heart disease (cor pulmonale), or even death. People with other abnormalities or who have Pierre Robin sequence (PRS) as part of a syndrome have a higher chance of dying.
In a study reviewing 181 infants’ cases, the overall mortality rate was found to be 16.6%. However, there were no deaths among infants who had only Pierre Robin sequence and no other abnormalities. The risk of death was linked with heart and central nervous system abnormalities or defects in two or more organs.
Possible Complications When Diagnosed with Pierre Robin Syndrome
The complications of Pierre Robin sequence are mainly because of problems with the airway, making it difficult to breathe. Short-term complications from this breathing difficulty can include low oxygen levels in the body, trouble feeding, and risks of inhaling food or liquid into the lungs. Long-term troubles may result from low oxygen levels or trouble feeding. These problems could potentially harm the brain, cause high blood pressure in the lungs, lead to lung-related heart disease, and cause problems with growth and development. There may also be complications associated with the treatments for Pierre Robin sequence, which are discussed separately. Early detection of this condition can help prevent long-term complications from breathing difficulty and low oxygen levels in the body.
List of potential complications:
- Short-term problems due to breathing difficulty:
- Low oxygen levels in the body
- Difficulty in feeding
- Risk of inhaling food or liquid into the lungs
- Long-term problems resulting from low oxygen levels or difficulty in feeding:
- Potential brain damage
- High blood pressure in the lungs
- Lung-related heart disease
- Issues with growth and development
- Complications from Pierre Robin sequence treatments
Preventing Pierre Robin Syndrome
An early pregnancy scan can help parents find out if there are any health concerns with the baby. If so, they have the option to end the pregnancy if they choose to. After the baby’s birth, parents should be taught how to spot weight-gain or breathing problems, which can be signs of health issues. Parents should be properly advised about the possible side-effects and issues that medical procedures can have on the baby.
