W5 - Craniofacial Malformations & Cleft Management - Abdalla Flashcards
What are the 3 stages that can impact embryonic craniofacial development?
Neural crest problems
Lack of fusion
Suture problems
Examples of neural crest problems (3)
Fetal Alcohol syndrome
Hemifacial microsomia
Treacher collins syndrome
What is FAS? Features (4)
Fetal alcohol syndrome
-
Caused by maternal alcohol use (teratogen) during pregnancy
- Microcephaly
- Smooth philtrum
- Thin upper lip
- Micrognathia
How does alcohol use affect developing child in early pregnancy vs late pregnancy?
Early - Craniofacial malformation
Late - Affected cognitive & behavioural development
Head / Oral manifestations of FAS (4)
Midface deficiency
Mandibular retrognathia
Cleft lip / palate
Enamel hypoplasia
FAS IS A SPECTRUM - may or may not have all these
Physical features of Treacher Collins Syndrome (5)
Microtia or anotia
Deafness
Zygomatic deficiency
Mandibular hypoplasia
Cleft palate plus facial clefting
Cause of treacher collins syndrome
Autosomal dominant condition
Mutation affects neural crest cells resulting in lack of mesenchymal cells
- causes a lack of tissues on the lateral parts of the face
What is hemifacial microsomia?
Most common craniofacial anomaly after cleft lip
- Defect of 1st and 2nd brachial arch
- Not much known of etiology → congenital but not inherited
- Can occur bilaterally in 10-15% of cases
What important dentistry-related structures arise from the first and second brachial arches?
First brachial arch
- Maxilla & mandible
- MoM
Second brachial arch
- Muscles of facial expression
What are the 5 things that can be affected by hemifacial microsomia
OMENS
Orbit
Mandible
Ears
Nerves
Soft tissues
What is craniosynososis?
Early closure of skull sutures
- Can be syndromic or nonsyndromic
Features of non syndromic craniosynostosis (3)
- Very rare
- Head shape altered
- Can cause increased intracranial pressure
Features of syndromic craniosynostosis (syndromes? features?)
Crouzons and Aperts most common
Very very rare
- Cranial vault deformities
- Midface deficiency
- Cleftr palate
- Hand and foot syndactyly
How do syndromic craniosynostoses affect cranial / facial development? (5)
Raised intracranial pressure can cause problems with neural development and vision
Vault expansion required in early childhood (first few months)
Eye exposure can cause corneal abrasions and scarring → may lead to blindness
Compromised airways
Feeding problems
What is distraction osteogenesis?
Extending the fracture site to encourage new bone growth in the formed gap
- Allows new growth without need for graft
- 1mm per day bone growth (14mm over 2 weeks)
Can be used for synchondroses where sutures have closed too early → need craniofacial growth
Sequence vs Syndrome
Syndrome - pattern of anomalies that occur together in a predictable fashion due to a single aetiology
Sequence - group of anomalies that generally stem from a single major anomaly that alters the development of surrounding structures
What is pierre robin sequence and what causes it
Micrognathia caused by posture in utero
- Elevation of tongue obstructs the upper airway and causes cleft lip and palate
- in other words, tongue cannot descend and thus palatal shelves cannot connect in fuse → Cleft palate
During which weeks in utero is the face formed
4th to 10th weeks
- This is the time span when facial deformities and clefts will develop
What 5 facial swellings make up the face in utero development
unpaired frontonasal process
pair of maxillary swellings
pair of mandibular swellings
When does the median nasal process and maxillary process fuse to form the primary palate? What happens if they dont fuse?
Around week 6 - median nasal process and maxillary process fuse forming lip and primary palate
Failure to fuse median nasal process and maxillary process leads to cleft lip
Do cleft lip and palate happen together? What causes them embryologically?
Not necessarily - different process, different times
Cleft lip - medial nasal processes and maxillary process dont fuse (pic in first slide) ALSO, if structure does not fuse with premaxilla aka primary palate (cleft lip includes clefting all the way to alveolus up until incisal foramen)
Cleft palate - maxillary processes which have turned into the palatal shelves must grow and fuse with nasal septum and primary palate. If not → cleft palate (second slide pic)
How does the secondary palate form?
Occurs during 6th week of embryogenesis
Secondary palate forms as bilateral outgrowths from maxillary processes (now palatal shelves), which grow vertically down the side of the tongue
Palatal shelves elevate to a horizontal position above the tongue (AND TONGUE DESCENDS), make contact, and commence fusion starting from the front to the back
Fusion of the shelves ultimately divides the oronasal space into separate oral and nasal cavities
How does the cleft lip present?
Includes lip and alveolus to incisive foramen
Bilateral or unilateral
How does the cleft lip present?
Includes lip and alveolus
Bilateral or unilateral
How does the cleft palate present (2)
NOT unilateral/bilateral → only one split
ALVEOLUS NOT INVOLVED IN CLEFT PALATE
Cleft lip and palate aetiology?
Genetic → but not standard mendellian heridity
Environmental → Retinoids, smoking, alcohol, drugs
Most likely a combination
- some people may be more genetically predisposed → requires less environmental factors to develop cleft
What drugs may induce cleft lip and palate
Phenytoin - anticonvulsants
Trimethoprim - antibiotics
What drug has a preventive effect on oral clefts?
Folic acid / Folate
Chance of live birth developing cleft
1:700 → 0.14%
How can CLP be diagnosed and when
Ultrasound
- Week 20
- 3D ultrasound much more effective than 2D
CLP Tx at 0-1 years old
0-1 years → acrylic plates for nasoalveolar molding and to stop tongue from resting in cleft
→ Cleft lip and palate can begin to repair itself
CLP tx at 7-9 years
Ortho treatment to prep for alveolar bone graft
- may need mx expansion
CLP tx when 18+
Orthognathic surgery
Rhinoplasty
- will likely have a class 3 skeletal discrepancy
- This is due to prev tx → scar tissue affecting mx development (55min)
Why do CLP patients develop class 3 when older?
Tx when young from closing the cleft causes scar tissue formation on lip and palatal structure
→ restricts maxillary growth (midface deficiency)
3 classifications of embryonic craniofacial development
Neural crest problems
Lack of fusion (ex. CLP)
Suture problems
What type of surgery is required for syndromic craniosynostosis
Craniofacial surgery / lefort 3
Distraction osteogenesis (more modern)
