Pierre Robin Sequence (PRS) describes a set of physical differences present at birth. It involves specific structural abnormalities of the jaw and mouth that can affect a newborn’s breathing and feeding. The condition is considered a “sequence” because one initial developmental issue during pregnancy triggers a chain of other related changes.
Defining Physical Characteristics
Pierre Robin Sequence is characterized by three physical traits. The first is micrognathia, an unusually small or underdeveloped lower jaw. The second is glossoptosis, where the tongue is positioned further back in the mouth, often falling towards the throat. This occurs because the small lower jaw does not provide enough space for the tongue to rest in its usual forward position.
The backward displacement of the tongue can obstruct the upper airway, leading to breathing difficulties. The third feature, present in most cases, is a cleft palate. This is an opening in the roof of the mouth, often U-shaped, that results when the developing tongue interferes with the normal fusion of the palatal shelves during fetal development.
Understanding the Origins
The cause of Pierre Robin Sequence is not fully understood, but it results from a series of events during early fetal development. The initial event is the underdevelopment or arrested growth of the lower jaw, occurring between 7 to 10 weeks of gestation. If the jaw does not grow adequately, the tongue cannot descend properly, remaining pushed up and back in the oral cavity. This abnormal tongue position can then prevent the palate from closing, leading to a cleft palate.
Pierre Robin Sequence can occur in isolation or as part of a broader genetic syndrome. Genetic factors, such as changes near the SOX9 gene, have been linked to isolated PRS. Environmental influences, like uterine crowding during pregnancy, are also potential contributors. While some cases have a known genetic basis, many instances of PRS do not have an identifiable underlying cause.
Approaches to Clinical Care
Diagnosis of Pierre Robin Sequence can occur during pregnancy through ultrasound, which may detect a small jaw. However, it is most often identified shortly after birth when characteristic physical signs and breathing or feeding difficulties become apparent. A physical examination is sufficient for diagnosis, though further imaging like a CT scan might assess facial structure or a sleep study evaluate for obstructive sleep apnea.
Managing PRS focuses on ensuring a clear airway and supporting adequate feeding. For many infants, positioning them on their stomach or side can help prevent the tongue from falling back and obstructing breathing. In some cases, a nasopharyngeal airway, a soft tube inserted through the nose, can keep the airway open. If non-surgical methods are insufficient, more invasive interventions may be necessary.
Surgical options for airway management include tongue-lip adhesion, where the tongue is temporarily attached to the lower lip to keep it forward. Mandibular distraction osteogenesis (MDO) involves surgically cutting the jawbone and gradually lengthening it with a device, creating more space for the tongue. For severe airway compromise, a tracheostomy, which creates a breathing hole in the windpipe, might be considered as a last resort.
Feeding difficulties are also addressed, often with special bottles that aid in suction. For infants who struggle to gain weight or are at risk of aspiration, a nasogastric tube (feeding tube through the nose) or a gastrostomy tube (feeding tube directly into the stomach) may be used. If a cleft palate is present, surgical repair is performed around 10 to 12 months of age, once the infant’s breathing and feeding are stable. Care for individuals with PRS involves a multidisciplinary team, including pediatricians, craniofacial surgeons, ENT specialists, speech pathologists, and feeding therapists.
Life with Pierre Robin Sequence
The long-term outlook for individuals with Pierre Robin Sequence varies depending on the condition’s severity and whether it occurs in isolation or as part of a syndrome. Many children with isolated PRS experience significant improvement as they grow because the lower jaw often undergoes rapid growth during the first year of life. This “catch-up” growth can reduce the severity of airway and feeding issues over time. With appropriate medical and surgical care, the survival rate for babies with PRS is high, with some studies reporting rates as high as 95%.
Despite improvements in jaw size and breathing, individuals with PRS may face ongoing considerations. Speech development can be affected, particularly if a cleft palate was present, requiring speech therapy. Dental issues, such as tooth crowding in the smaller lower jaw, are common and may necessitate orthodontic intervention. Hearing problems, often conductive hearing loss due to fluid buildup in the middle ear, are frequently observed, especially in those with a cleft palate, making regular hearing assessments important. Continued follow-up with a specialized team is important to address these challenges and support optimal development throughout childhood and into adulthood.