Week 5 Abdalla- Craniofacial malformations & cleft management Flashcards
What are the stages that can impact embryonic craniofacial development?
-
Neural crest problems
- Germ layer foration
- Neural tube formation
- Migration of neural crest cells
-
Lack of fusion
- Organ system formation
- Primary palate
- Secondary Palate
-
Suture problems
- Final differentiation of tissues
What are features of fetal alcohol syndrome?
Caused by maternal alcohol use during pregnancy
- Microcephaly
- Smooth philtrum
- Thin upper lip
- Micrognathia
- Mid face deficiency
- Enamel hypoplasia
- Cleft lip/palate
What is alcohol use in early vs late pregnancy associated with?
- Early: craniofacial malformation
- Late: cognitive and behavioural development
What are features of treacher collins syndrome?
- Microtia or anotia
- Conductive deafness
- Zygoma deficiency
- Md hypoplasia
- Cleft palate plus facial clefting
What is the cause of treacher collins syndrome?
- 3 gene mutations identified (autosomal dominant)
- Mutation effects neural crest cells resulting in overall lack of mesenchymal cells and thus lack of tissues on lateral parts of face
What is hemifacial (craniofacial) microsomia?
- Part of one side of the face is underdeveloped and does not grow normally
- Most common craniofacial anomaly after cleft lip
- Can occur bilaterally (10-15% cases)
- Defect of 1st and 2nd brachial arch
- Congenital but not inherited
What are features of hemifacial (craniofacial) microsomia?
- Mandibular and ear defects
- Facial nerve weakness
- Maxillary hypoplasia
- Significant facial asymmetry
What structures can be affected by hemifacial microsomia?
OMENS
- Orbits
- Mandible
- Ears
- Nerves
- Soft tissues
What is craniosynostosis?
- Early close of skull sutures
- Can be divided into syndromic and non syndromic
What are features of non-syndromic craniosynostosis?
- Head shape altered
- Very rare
- Can cause increased intracranial pressure but rare
What are clinical features of syndromic craniosynostoses?
- Cranial vault deformities
- Mid face deficiencies
- Cleft palate
- Hand and foot syndactyly
- Compromised airways
- Feeding problems
- Raised intracranial pressure → neural development and vision problems
How can syndromic craniosynostoses be managed?
- May need cranial vault expansion
- Craniofacial surgery
- Distraction osteogenesis
What is distraction osteogenesis?
- Extend fracture site to encourage new bone growth by turning screws
- 1mm per day bone growth
- No need for bone graft
What is Pierre Robin Sequence?
- Micrognathia caused by posture in utero
- Elevation of tongue obstructs upper airway and causes cleft lip and palate
What is the diff between syndrome and sequence?
- Syndrome: pattern of anomalies that occur together in predictable fashion due to specific etiology
- Sequence: group of anomalies that stem from single major anomaly that alters development of surrounding structures
How is the face formed?
In 4th-10th week of pregnancy there is fusion of 5 facial swellings
- Unpaired frontonasal process
- Paired maxillary swellings
- Paired mandibular swellings
When/how does primary palate form?
Week 6: medial nasal process and mx process fuse forming lip and primary palate
How does cleft lip and palate occur?
- Cleft lip: failure for medial nasal process and mx process to fuse
- Cleft palate: mx processes which have turned into palatal shelves don’t grow and fuse with nasal septum and primary palate
What does cleft lip involve?
Lip and alveolus
Bilateral or unilateral
What are some environmental teratogens for cleft lip and palate?
- Retinoids
- Smoking
- Alcohol
- Illicit drugs
- Anticonvulsants
- Trimethoprim (AB)
What has protective effect against cleft lip/palate?
Folic acid
What is prevalence of cleft lip and palate?
0.14%
How/when can cleft lip and palate be diagnosed?
Ultrasound at 20 weeks
How is cleft lip and palate treated?
- 0-1 years: acrylic plate to stop tongue going into cleft (helps soft tissues repair)
- 7-9 years: initial ortho tx and then alveolar bone grafting
- 12-13: conventional ortho
- 18: orthognathic surgery (class III skeletal discrepancy)
Why does cleft lip/palate pt have class III skeletal discrepancy and eventually require orthognathic surgery?
Scar tissue from closing cleft lip/palate (around 6 months) restricts growth of maxilla (midface deficiency). Class III assoc with tx rather than the cleft lip/palate.
What syndromes are associated with syndromic craniosynostoses
Crouzens and Aperts most common
What pharyngeal arch do the maxilla and mandible come from?
1st pharyngeal arch
How does the secondary palate form?
- During 6th week, bilateral outgrowths from the maxillary processes grow vertically down the side of the tongue
- Subsequently, the palatal shelves elevate to a horizontal position above the tongue, contact one another and commence fusion
- Fusion of the palatal shelves separates oral and nasal cavities
