Pierre Robin syndrome is a condition characterized by three components: cleft palate, mandibular micrognathia or retrognathia, and glossoptosis. It is caused by the mechanical theory where cleft palate prevents palatal shelf fusion and mandibular hypoplasia constrains growth, leading to tongue displacement. Achondroplasia is caused by mutations affecting endochondral ossification, leading to disproportionate short stature and limb shortening, large head size, and restricted joint motion. Both conditions are diagnosed based on clinical features and imaging findings, and require multidisciplinary care.

1. dr vaISHNAVI
Department of Oral Pathology
& Microbiology
SRM Dental College,
Ramapuram, Chennai, India
PIERRE ROBIN SYNDROME &
ACHONDROPLASIA

3. PIERRE ROBIN SYNDROME
 Pierre robin sequence/Anomalad
 Pierre robin malformation
 Robin sequence/ complex
It has three essential components
1. Cleft palate
2. Mandibular Micrognathia (smaller-than-normal
mandible) or Retrognathia (retruded mandible)
3. Glossoptosis (lower and posterior displacement of
tongue airway obstruction)

5.  Pierre Robin is a sequence, not a syndrome!
 Sequence = a series of sequential developmental
malformations produced by a single cause
 Syndrome = a group of signs and symptoms that
occur together and that underlie a particular
abnormality or condition

6. ETIOLOGY
PATHOPHYSIOLOGICAL
THEORIES
 Isolated phenomenon
 Associated with syndromes or other anomalies
1. Mechanical theory
2. Neurological maturation theory
3. Rhomboencephalic dysneurulation theory

7. Basics

8. Palate development ; basics

9. Tongue has to descend …..

10. Mechanical theory
 Most accepted
cleft palate
Prevents fusion of palatal shelves
failure of tongue to descend
(tongue remains high in the oral
cavity)
Constraint of mandibular growth in
utero (mandibular hypoplasia 7th to
11th week of gestation)

11. PIERRE ROBIN SEQUENCE

13.  Oligohydramnios could play a role
 Absence of amniotic fluid deformation of chin
subsequent impaction of tongue between the palatal
shelves
 Retruded mandible results in the following:
 Posterior displacement of tongue
 Lack of support of tongue musculature
 Airway obstruction
 Respiratory difficulty  especially when child is in
supine position (from birth) can cause asphyxiation
 Palatal cleft is U – shaped and wider than isolated
cleft palate

14. Other theories:
 Neurological Maturation Theory :
 Delay in neurological maturation  delay in
hypoglossal nerve conduction
 Explains spontaneous correction of mandibular
hypoplasia with age in most cases
 The rhomboencephalic dysneurulation theory :
 Major and regulatory organization of
rhomboencephalus (hindbrain) is related

15. CLINICAL FEATURES:
 1 in 8500
 Palate : U-Shaped/V-Shaped
 Mandible :
 Hypoplasia
 Micrognathia
 Small body
 Obtuse gonial angle
 Posteriorly located condyle
 Resolves and child attains normal profile by 5-6 years
 Tongue:
 Glossoptosis
 Macroglossia, ankyloglossia (rare)
 Severe respiratory distress and feeding difficulty in newborn

16. OTHER ASSOCIATED ANOMALIES
 Otitis media (inflammatory diseases of the middle ear)
 Hearing loss
 Nasal deformities
 Dental and philtral malformation
 Anomalies of musculoskeletal system:
 Syndactyly (some or all of the fingers or toes wholly or partly
united)
 Dysplastic phalanges
 Polydactyly
 Clinodactyly (curvature )
 Hyperextensive joints
 Oligodactyly in hands
 CNS defects:
 language delay
 Epilepsy
 Neurodevelopmental delay
 Hydrocephalus (accumulation of CSF within the brain.)

17. DIAGNOSIS:
 Mainly based on the clinical assessment and radiographic findings of
micrognathia
 Shortly after birth due to characteristic facies :
 Small lower jaw (micrognathia)
 A tongue which tends to ball up at the back of the mouth and fall
back towards the throat (glossoptosis)
 Horseshoe-shaped cleft palate
 Breathing difficulties
 Feeding difficulties
 Genetic testing is important to determine if it is isolated or associated
with another syndrome.

18. Treatment and Prognosis
 Multidisciplinary approach
 Depends on the airway compromise and extent of
feeding difficulty
 Surgical intervention

19. ACHONDROPLASIA

21. ETIOLOGY
 Also known as Chondrodystrophia fetalis
 Non-lethal form of chondrodysplasia
 Transmitted as Autosomal Dominant Trait with
complete penetrance
 De-Novo mutations (80% cases)
 Mutations in gene for FGFR3 results in
decreased endochondral ossification  inhibited
proliferation of chondrocytes in growth plate
cartilage  decreased cartilage matrix production

22. Try to remember:
• The bones of the extremities and those parts of the axial skeleton that bear
weight (e.g., vertebrae) develop by endochondral ossification.
• The flat bones of the skull and face, the mandible, and the clavicle develop
by intamembranous ossification.

23. Endochondral ossification

25. CLINICAL FEATURES
 1 in 15000-40000 births
 Short stature
 Rhizomelic shortening of the arms
and legs
 A disproportionately long trunk
 Trident hands
 Midfacial hypoplasia
 Prominent forehead frontal bossing
 Thoracolumbar protuberance
 True megalencephaly (A growth
development disorder in which the
brain is abnormally large)
 Characteristic limitation of joint
motion

27. CLINICAL FEATURES

28. The body phenotype is shown in individuals of different ages: Left to right –
infancy, early childhood, childhood and adulthood. In all, note the rhizomelic
shortening of the limbs, which are disproportionately short compared with
the trunk. In the infant and young child macrocephaly is evident

29. Oral Manifestations:
 Maxilla is retruded due to restriction of growth of
base of skull
 Relative mandibular prognathism
 Malocclusion
 Might have congenitally missing teeth/ shape
disturbances

31. RADIOGRAPHIC FEATURES:
 Skull, spine and extremeties
 Lateral skull radiograph : midface hypoplasia, enlarged calvaria,
frontal prominence, shortening of base of skull
 Size of foramen magnum is diminished
 Long bones are shorter than normal they have thickening/mild
clubbing at ends
 Epiphyses appear normal, but may close early/late
 Bones at the base of the skull fuse prematurely
 Maxilla – retruded
 Malocclusion between the jaws

32. Intraoral views showing anterior reversed jet, posterior cross bite, Class III
dental malocclusion, crowding at the mandibular anterior region, and dental
caries

33. Histologic features:
 Failure of endochondral ossification:
 Loss of chondrocyte proliferation
 Fibrous tissue is present in the zone of provisional
calcification, but bone trabeculae present are
irregular
 Orderly longitudinal growth of bone is disturbed 
stunted growth
 Intramembranous and periosteal ossifications
undisturbed  so normal clavicles and skull and
width of long bones normal

34. DIAGNOSIS
 Preconception: affected parent/family member ,
genetic counselling
 Prenatal : routine ultrasound, DNA test
 Post natal : clinical findings, skeletal survey,
radiographs

35. Treatment and Prognosis
 No treatment
 May be delay in motor milestones but speech is
normal
 Treatment for Frequent middle ear infections and
Dental crowding
 Life expectancy – as that of a normal person

36. Thank you