Pierre Robin sequence[a] (/pjɛər rɔːˈbæ̃/;[3] abbreviated PRS) is a congenital defect observed in humans which is characterized by facial abnormalities.

[4] PRS is characterized by an unusually small mandible, posterior displacement or retraction of the tongue, and upper airway obstruction.

[citation needed] The physical craniofacial deformities of PRS may be the result of a mechanical problem in which intrauterine growth of certain facial structures is restricted, or mandibular positioning is altered.

[4] One theory for the etiology of PRS is that, early in the first trimester of gestation, some mechanical factor causes the neck to be abnormally flexed such that the tip of the mandible becomes compressed against the sternoclavicular joint.

The concave space formed by the body of the hypoplastic mandible is too small to accommodate the tongue, which continues to grow unimpeded.

Later in gestation (at around 12 to 14 weeks), extension of the neck of the fetus releases the pressure on the mandible, allowing it to grow normally from this point forward.

The DO process starts with a preoperative assessment, during which doctors use three-dimensional imaging to identify the parts of the patient's facial skeleton that need realignment and determine the required magnitude and direction of distraction.

A few days later, the two ends of the bone are very gradually pulled apart through continual adjustments that are made to the device by the parents at home.

The adjustments are made by turning a small screw that protrudes through the skin, usually at a rate of 1 mm per day.

In many centres there is now a cleft lip and palate team comprising these specialties, as well as a coordinator, a speech and language therapist, an orthodontist, sometimes a psychologist or other mental health specialist, an audiologist, and nursing staff.

The glossoptosis and micrognathism generally do not require surgery, as they improve to some extent unaided, though the mandibular arch remains significantly smaller than average.

Because middle ear effusion is found in many patients with PRS, tympanostomy (ventilation) tubes are often a treatment option.

[15] One study with children showed that patients with PRS displayed a moderate and severe hearing loss most frequently.

However, it has been found internationally that children with PRS are often slightly below average size, raising concerns of incomplete development due to chronic hypoxia related to upper airway obstruction as well as lack of nutrition due to early feeding difficulties or the development of an oral aversion.

Infants who are unable to take in enough calories by mouth to ensure growth may need supplementation with a nasogastric tube.

Mandibular distraction can be effective by moving the jaw forward to overcome the upper airway obstruction caused by the posterior positioning of the tongue.

Because the retinal detachment that sometimes accompanies Stickler syndrome is a leading cause of blindness in children, it is very important to recognize this diagnosis.

[18][19] It is thought that Noel Rosa, one of the most famous and influential artists in the history of Brazilian music, had PRS,[20] although others claim that his sunken chin was the result of a forceps accident during childbirth.

Retrieved March 11, 2020, from https://www.researchgate.net/publication/15470673_Hearing_Levels_in_Pierre_Robin_Syndrome Pierre Robin Syndrome - Birth Defect Fact Sheet.