Pierre Robin Syndrome

Synonyms: Pierre Robin syndrome, Pierre Robin anomaly/anomalad, Pierre Robin sequence (PRS), Pierre Robin malformation (PRM) complex, Robin sequence, Robin complex

Related conditions that may display features of the malformation: Stickler syndrome, Velocardiofacial syndrome, Catel-Manzke syndrome, Treacher-Collins syndrome, Nager syndrome, Spondyloepithelial dysplasia congenita, Campomelic dysplasia.

This condition was originally considered to be a single clinical entity but is now thought to represent a particular outcome of an abnormal developmental process, associated with a range of clinical entities, and is more commonly referred to as Pierre Robin sequence. Pierre Robin, a french dental surgeon (1867-1950) is identified with the syndrome/sequence due to his role in the early part of the twentieth century, describing the typical triad of features and his many articles on its management. PRS' typical features are:

• Micrognathia or retrognathia (small or retracted mandible)
• Cleft palate (classically U-shaped, but V-shaped may occur, usually without cleft lip)
• Glossoptosis (inferring a relatively large tongue. In reality, the tongue may be normal size or small so upper airway obstruction may be substituted for this feature)

The aetiology of the sequence is not fully understood and pathogenesis is thought to be multifactorial.¹ Subtypes are recognised: isolated PRS, syndromic PRS (a syndrome + PRS) and unique PRS (unique anomalies + PRS).² About 25% associated with other syndromes, 35% with other abnormalities not syndromally defined, and 40% have isolated malformation.³ Some cases may be due to physical intra-uterine compromise but it has been linked with deletions on chromosome 2 that are known to be associated with palatal abnormalities, and some cases may have a mendelian genetic basis that is, as yet, unclear.⁴ Candidate genes and loci are under investigation.⁵

Incidence

PRS is a rare condition. A Danish retrospective study found an incidence of 1 in 14,000 live births.⁶ American estimates vary from 1 in 2,000 to 1 in 30,000.³

• With the increasing routine use of antenatal ultrasound, diagnosis is frequently before birth - based on identification of micro or retrognathism and glossoptosis.^7,8,9
• The craniofacial abnormalities are usually plainly evident at birth, if not diagnosed previously.
• Neonates with severe micrognathia present as emergencies at birth with significant respiratory obstruction, requiring a nasopharyngeal airway or intubation.
• Unrecognised or untreated airways obstruction may lead to chronic hypoxia and cerebral impairment, failure to thrive and cor pulmonale.
• Feeding difficulties is the most common early problem as the cleft palate prevents enough negative pressure to feed effectively.
• Careful examination for other somatic abnormalities, including examination of the eyes and ears, may indicate the presence of the malformation as one of the related syndromes.

• Fetal alcohol syndrome
• Stickler syndrome: PRS plus severe myopia, retinal detachment and blindness with abnormal epiphyseal development due to Alpha-1 collagen II polypeptide mutation¹⁰
• Velocardiofacial syndrome: 22q deletion with neuropsychiatric impairments and cardiac abnormalities¹¹
• Other rare syndromes that display the malformation

• Pulse oximetry, arterial or capillary blood gases
• Bone radiographs
• Genetic assessment
• Ophthalmological/auditory assessment

Neonatal

Babies presenting at birth with significant respiratory obstruction require urgent attention from someone experienced with the problematic pediatric airway.
Where a cleft palate prevents nursing, deliver formula or breast milk through a bottle with a nipple cut to a large hole to make delivery effortless. Good nursing is critical to teach the proper feeding technique. Positioning (in the prone position) is also vital.
The engagement of a multidisciplinary team (incorporating paediatricians, ENT and plastic surgeons, dentists, orthodontists, nurses, speech therapists, audiologists, and social workers) from birth also ensures the most comprehensive care plan.

Airways

Where positioning therapy fails to control airways, further support may require nasopharanyngeal airways,¹² palatal prostheses, continuous positive airway pressure, endotracheal intubation, mechanical ventilation or tracheostomy. In one series, two-thirds who failed to improve with positional therapy required a surgical airway.²Micrognathia may improve in 'non-syndromal' PRS as catch-up growth occurs, or may require surgery to prevent worsening facial dysmorphism. As the child matures prosthetic devices or surgical intervention may be needed to maintain airway in those for whom conservative measures are insufficient. Surgical approaches include:

• Tracheotomy
• Distraction osteogenesis of the mandible (progressive elongation of mandible, a new and promising technique)¹³
• Tongue-lip adhesion/glossopexy (connecting tongue to lower lip to improve airway, later reversed)¹⁴

Feeding

If feeding is problematic, a feeding tube may be required. Palatal repair usually carried out at 10–18 months.³

A degree of palatal dysfunction is to be expected in the long term. However, overall, the outlook is good but dependent on the presence or absence of other syndromes and their complications. By 3 years old, most children with PRS are taking an oral diet and do not have significant airways obstruction.²