Pierre Robin Sequence: Etiology, Diagnosis, Treatment

Pierre Robin Sequence (PRS) is a complex clinical condition characterized by a specific triad of findings: glossoptosis, retrognathia, and airway compromise. This article provides a comprehensive overview of its etiology, diagnosis, and treatment, helping students understand this multifaceted entity.

Pierre Robin Sequence is not considered a syndrome, but rather a sequence, meaning various underlying causes can lead to the same set of observable features. It can occur as an isolated entity or be associated with other syndromes, necessitating a multidisciplinary approach for diagnosis and management.

Understanding Pierre Robin Sequence: Etiology and Historical Context

The term “Pierre Robin Sequence” has evolved as scientific understanding advanced. Initially, it was called “Pierre Robin syndrome,” but in 1976, Gorlin, Pinborg, and Cohen clarified it as an “anomalad,” which then shifted to the current “sequence” designation.

The earliest accounts of PRS date back to 1822 by St. Hilaire and Fairbain in 1846. Dr. Pierre Robin, a French stomatologist, popularized the condition, writing 17 articles on “glossoptosis” starting in 1923 and highlighting severe respiratory and feeding complications. He believed severe cases were dire, noting, “I have never seen a child live more than 16–18 months who presented with hypoplasia such as the lower maxilla was pushed more than 1 cm behind the upper.”

What Causes Pierre Robin Sequence?

The exact etiology of PRS is still being researched, but it is understood to be multifactorial. Several theories explain its development:

• Mechanical Theory: Mandibular hypoplasia, occurring between the 7th and 11th weeks of gestation, causes the tongue to sit high in the oral cavity. This interferes with the lateral palatine processes moving from a vertical to a horizontal position, leading to a cleft palate. Intrauterine constriction, from factors like a multigravid pregnancy or oligohydramnios, can induce this.
• Neurological Maturation Theory: A delay in neuromuscular development of the tongue, pharyngeal pillars, and palate may contribute to the condition. Electromyogram studies have shown delays in these areas.
• Rhombencephalic Dysneuralation Theory: This theory suggests a major developmental complication related to the motor and regulatory organization of the rhombencephalus.

Cohen (1978) described mechanisms including malformation, deformation, and connective tissue dysplasia. Intrauterine exposure to teratogens like alcohol, trimethadione, and hydantoin is also implicated. Approximately 80% of patients with PRS are nonsyndromic.

Syndromic Pierre Robin Sequence Associations

Many syndromes are associated with PRS, affecting inheritance patterns and clinical presentation. The most frequently associated is Stickler syndrome, caused by mutations in genes like COL2A1, COL9A1, COL11A1, or COL11A2, impacting collagen. Stickler syndrome is characterized by midline clefting, a flat midface, a hypoplastic mandible, and potential retinal detachments or hearing loss.

Other notable associations include:

• Velocardiofacial syndrome (Shprintzen syndrome): Linked to a deletion in 22q11, presenting with cleft palate, retrognathia, characteristic facial features, cardiac anomalies, and learning disabilities.
• Nager syndrome (acrofacial dysostosis): Features craniofacial similarities to mandibulofacial dysostosis, hypoplasia or agenesis of thumbs/radius, and a cleft palate. Mandibular hypoplasia can be severe with no