Etiology, Terminology, classification Flashcards
Cleft Lip/Cleft Palate
- 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
Embryological Development
- Happens during first trimester of life • Lip and alveolus 6-7 weeks
- Palate 8-9 weeks
- Completed by 12 weeks gestation
Causes of Clefts and Related Craniofacial Anomalies (CFA)
• 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
Environmental Causes
• 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
Clefts and associated abnormalities
• 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
Genetic and Chromosomal Causes
• 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
Folic Acid Deficiency
believed to cause neural tube defects, such as spina bifida, and various craniofacial defects
Incidence/Prevalence
- CL +/- CP twice as often in males • Also more severe in males
- CP only – twice as often in females • Reason not clear
Mechanical Interference
• 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
Multifactorial Inheritance
• Most clefts are caused by not just one factor
• Interaction of several factors
– Genetic predisposition – Environmental
Classification
- 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)
Normal lip anatomy vs. Cleft
– 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
Bilateral Cleft Lip
- 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
Cleft Lip
- 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
Palatal Classifications
• 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
Cleft Palate (secondary palate)
- 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
Cleft of soft palate
• 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
Otology Problems
- CP risk for otitis media (ear infections)
- Malfunction of eustachian tubes (tensor palatini)
- Pressure equalizing tubes (P.E. tubes)
Submucous Cleft Palate (SMCP)
• 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
Bifed Uvula
- Can be isolated—but frequently assoc with SMCP
* Can appear as one structure with line down the middle or small (hyperplastic and underdeveloped)
Zona Pellucida
• Bluish area in middle of velum
• Result thin mucosa (lack of underlining muscle
mass
Occult Submucous Cleft
- 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.
Effect of Submucous Cleft
• 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
Other Kinds of Cleft
- 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
