Etiology, Terminology, classification

Question 1

Cleft Lip/Cleft Palate

Answer 1

• Abnormal opening or fissure in an anatomical structure that is normally closed
• Vary in width and length
• Structures are there, they just have not fused together
• Structures may be hypoplastic or underdeveloped

Question 2

Embryological Development

Answer 2

• Happens during first trimester of life • Lip and alveolus 6-7 weeks
• Palate 8-9 weeks
• Completed by 12 weeks gestation

Question 3

Causes of Clefts and Related Craniofacial Anomalies (CFA)

Answer 3

• It is believed that there is no single factor contributing to CFA
• Possible causes fall into 2 categories:
– Endogenous (internal)
• Chromosomal disorders • Genetic disorders
– Exogenous (external) • Environmental
• Mechanical factors

Question 4

Environmental Causes

Answer 4

• Cause congenital malformations
• Factors associated w/ CLP and CFA:
– Cigarette smoking
– Phenytoin (Dilantin)
• Used commonly in management of seizures in epilepsy nerve problems in MS
– Thalidomide
• Used to treat mouth ulcers in HIV patients
• Being investigated for use in treating AIDS, tuberculosis, and other illnesses

Question 5

Clefts and associated abnormalities

Answer 5

• 14-15% have at least one other abnormality, varies based on cleft type
– Lip: 7%
– Lip/palate: 14% – Palate only: 24%
• Parental age and birth order have no direct effect

Question 6

Genetic and Chromosomal Causes

Answer 6

• Possible causes:
– Pre-existing chromosomal defects in parent genes
– Problem may occur when trying to combine them together
– Or may incur alterations in the genes after they are combined
– Babies inherit a gene that makes them more likely to develop a cleft, and then an environmental trigger actually causes the cleft to occur

Question 7

Folic Acid Deficiency

Answer 7

believed to cause neural tube defects, such as spina bifida, and various craniofacial defects

Question 8

Incidence/Prevalence

Answer 8

• CL +/- CP twice as often in males • Also more severe in males
• CP only – twice as often in females • Reason not clear

Question 9

Mechanical Interference

Answer 9

• E.g. in Pierre Robin sequence:
– Head is forced down and mandible retracted
– Tongue is elevated and oral cavity is restricted
– Tongue is blocking the fusion of the secondary palates
– Ends up bell shaped cleft palate

Question 10

Multifactorial Inheritance

Answer 10

• Most clefts are caused by not just one factor
• Interaction of several factors
– Genetic predisposition – Environmental

Question 11

Classification

Answer 11

• May be the lip or the palate or both • May be complete or incomplete
• Lip may be unilateral or bilateral
• Cleft lip (CL)
• Cleft palate (CP)

Question 12

Normal lip anatomy vs. Cleft

Answer 12

– Vermillion zone
– Columella
– Philtral lines/columns
 CL can range from mild to severe
• Can be as mild as a small notch in the vermillion zone
• More severe cleft
• Often affects the shape of nose
• Usually associated with cleft of alveolus

Question 13

Bilateral Cleft Lip

Answer 13

• Separation of tissue that would normally form philtrium
• Tissue that is isolated called prolabium
• When all the way through alveous to incisive foramen separates premaxilla bone

Question 14

Cleft Lip

Answer 14

• Once repaired, difficulty breathing through nose is common – ala is collapsed (nostril/alae)
• May also have developmental defects in nasal cavity ( choanal atresia)
• Can also have scaring
• Nose is 30% smaller than non-cleft

Question 15

Palatal Classifications

Answer 15

• Primary Palate ( cleft lip): lip and alveolar process
– Can be complete or incomplete
– Unilateral or bilateral
• Secondary Palate: hard and soft palate (area posterior to incisive foramen)
– Can be complete or incomplete

Question 16

Cleft Palate (secondary palate)

Answer 16

• Slight as bifed uvula or complete into soft palate and hard palate
• If hard palate, unilateral CP attached to vomer bone
• Can occur with or without a cleft lip
• Isolated CP (can be) associated w/ syndrome

Question 17

Cleft of soft palate

Answer 17

• Muscle insertions are abnormal
• The levator does not insert at midline
• Instead the levator and palatopharyngeous are inserted onto the posterior border of the hard palate (may also be cleft)
• The anterior one-third of the velum contains the muscle fibers of the levator and palatopharyngeous
• Goal of surgery is to correct the orientation
• Great variability in the insertion of muscle and muscle mass
• Even after surgery to repair, 20-30% still have VPI (velopharyngeal incompetence)
– Palate isn’t closing all the way; that’s why it’s so important to follow-up with these patients
– Look for nasal emission and hypernasality

Question 18

Otology Problems

Answer 18

• CP risk for otitis media (ear infections)
• Malfunction of eustachian tubes (tensor palatini)
• Pressure equalizing tubes (P.E. tubes)

Question 19

Submucous Cleft Palate (SMCP)

Answer 19

• Is a congenital defect that affects the underlying structures of palate
• Structures of oral surface are intact
• Involve muscles of velum and bony
• Can have three Characteristics – Zona pellucida
– Bifed uvula
– Notch in posterior border of HP
• May have one or none of the characteristicsstructures

Question 20

Bifed Uvula

Answer 20

• Can be isolated—but frequently assoc with SMCP

* Can appear as one structure with line down the middle or small (hyperplastic and underdeveloped)

Question 21

Zona Pellucida

Answer 21

• Bluish area in middle of velum
• Result thin mucosa (lack of underlining muscle
mass

Question 22

Occult Submucous Cleft

Answer 22

• No abnormality of velum observed when looking in mouth.
• Need videonasoendoscopy or MRI
• The edge of the velum-nasal surface is depressed rather than bulk. Will see a depression.
• Surgeon sees abnormality of muscle when dissecting the velum.

Question 23

Effect of Submucous Cleft

Answer 23

• Depends on type and extent of defect
• May have:
– Feeding problems
– Nasal regurgitation during swallowing
– Increased risk of otitis media (Eustachian tube malfunction)
• But may be asymptomatic from newborn to adulthood
• McWilliams (1991) studied 130 patients with submucous cleft, 44% with no symptoms

Question 24

Other Kinds of Cleft

Answer 24

• Clefts usually follow the embryological fusion lines (e.g medial palatine suture, philtrum), but other locations may be possible
• Usually rare
• Midline/median clefts • Lateral facial clefts
• Facial clefts are usually very severe and likely to be associated with other anomalies