W5 - Craniofacial Malformations & Cleft Management - Abdalla

Question 1

What are the 3 stages that can impact embryonic craniofacial development?

Answer 1

Neural crest problems

Lack of fusion

Suture problems

Question 2

Examples of neural crest problems (3)

Answer 2

Fetal Alcohol syndrome

Hemifacial microsomia

Treacher collins syndrome

Question 3

What is FAS? Features (4)

Answer 3

Fetal alcohol syndrome

• Caused by maternal alcohol use (teratogen) during pregnancy
  
  • Microcephaly
  • Smooth philtrum
  • Thin upper lip
  • Micrognathia

Question 4

How does alcohol use affect developing child in early pregnancy vs late pregnancy?

Answer 4

Early - Craniofacial malformation

Late - Affected cognitive & behavioural development

Question 5

Head / Oral manifestations of FAS (4)

Answer 5

Midface deficiency

Mandibular retrognathia

Cleft lip / palate

Enamel hypoplasia

FAS IS A SPECTRUM - may or may not have all these

Question 6

Physical features of Treacher Collins Syndrome (5)

Answer 6

Microtia or anotia

Deafness

Zygomatic deficiency

Mandibular hypoplasia

Cleft palate plus facial clefting

Question 7

Cause of treacher collins syndrome

Answer 7

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

Question 8

What is hemifacial microsomia?

Answer 8

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

Question 9

What important dentistry-related structures arise from the first and second brachial arches?

Answer 9

First brachial arch

• Maxilla & mandible
• MoM

Second brachial arch

• Muscles of facial expression

Question 10

What are the 5 things that can be affected by hemifacial microsomia

Answer 10

OMENS

Orbit

Mandible

Ears

Nerves

Soft tissues

Question 11

What is craniosynososis?

Answer 11

Early closure of skull sutures

• Can be syndromic or nonsyndromic

Question 12

Features of non syndromic craniosynostosis (3)

Answer 12

• Very rare
• Head shape altered
• Can cause increased intracranial pressure

Question 13

Features of syndromic craniosynostosis (syndromes? features?)

Answer 13

Crouzons and Aperts most common

Very very rare

• Cranial vault deformities
• Midface deficiency
• Cleftr palate
• Hand and foot syndactyly

Question 14

How do syndromic craniosynostoses affect cranial / facial development? (5)

Answer 14

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

Question 15

What is distraction osteogenesis?

Answer 15

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

Question 16

Sequence vs Syndrome

Answer 16

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

Question 17

What is pierre robin sequence and what causes it

Answer 17

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

Question 18

During which weeks in utero is the face formed

Answer 18

4th to 10th weeks

• This is the time span when facial deformities and clefts will develop

Question 19

What 5 facial swellings make up the face in utero development

Answer 19

unpaired frontonasal process

pair of maxillary swellings

pair of mandibular swellings

Question 20

When does the median nasal process and maxillary process fuse to form the primary palate? What happens if they dont fuse?

Answer 20

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

Question 21

Do cleft lip and palate happen together? What causes them embryologically?

Answer 21

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)

Question 22

How does the secondary palate form?

Answer 22

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

Question 23

How does the cleft lip present?

Answer 23

Includes lip and alveolus to incisive foramen

Bilateral or unilateral

Question 23

How does the cleft lip present?

Answer 23

Includes lip and alveolus

Bilateral or unilateral

Question 24

How does the cleft palate present (2)

Answer 24

NOT unilateral/bilateral → only one split

ALVEOLUS NOT INVOLVED IN CLEFT PALATE

Question 25

Cleft lip and palate aetiology?

Answer 25

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

Question 26

What drugs may induce cleft lip and palate

Answer 26

Phenytoin - anticonvulsants

Trimethoprim - antibiotics

Question 27

What drug has a preventive effect on oral clefts?

Answer 27

Folic acid / Folate

Question 28

Chance of live birth developing cleft

Answer 28

1:700 → 0.14%

Question 29

How can CLP be diagnosed and when

Answer 29

Ultrasound

• Week 20
• 3D ultrasound much more effective than 2D

Question 30

CLP Tx at 0-1 years old

Answer 30

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

Question 31

CLP tx at 7-9 years

Answer 31

Ortho treatment to prep for alveolar bone graft

• may need mx expansion

Question 32

CLP tx when 18+

Answer 32

Orthognathic surgery

Rhinoplasty

• will likely have a class 3 skeletal discrepancy
  
  • This is due to prev tx → scar tissue affecting mx development (55min)

Question 33

Why do CLP patients develop class 3 when older?

Answer 33

Tx when young from closing the cleft causes scar tissue formation on lip and palatal structure

→ restricts maxillary growth (midface deficiency)

Question 34

3 classifications of embryonic craniofacial development

Answer 34

Neural crest problems

Lack of fusion (ex. CLP)

Suture problems

Question 35

What type of surgery is required for syndromic craniosynostosis

Answer 35

Craniofacial surgery / lefort 3

Distraction osteogenesis (more modern)