Cleft lip and
palate
Clefts of the lip, alveolus, hard and soft
palate are the most common congenital abnormalities of the orofacial structures.
They frequently occur as isolated deformities but can be associated with other
medical conditions particularly congenital heart disease. They are also an
associated feature in over 300 recognized syndromes.
All
children born with a cleft lip and palate need thorough paediatric assessment to
exclude other congenital abnormalities. In certain circumstances genetic
counselling must be sought if a syndrome is suspected.
Incidence
The incidence of cleft lip and palate is one
in 600 (1:600) live births, and 1:1000 live births for isolated cleft palate.
The incidence increases in Oriental groups (1:500) and decreases in the black
population (1:2000). The highest incidence reported for cleft lip and palate
occurs in the Native American tribes of Montana, USA (1:276).
Although
cleft lip and palate is an extremely diverse and variable congenital
abnormality, several distinct subgroups exist, namely cleft lip with/without
cleft palate (CL/P), cleft palate alone (CP) and submucous cleft palate
The
typical distribution of cleft types is:
•
cleft lip alone — 15 per cent;
•
cleft lip and palate ------45 per cent;
•
isolated cleft palate — 40 per cent.
Cleft
lip/palate predominates in males whereas cleft palate alone appears more common
in females. In unilateral cleft lip, the deformity affects the left side in 60
per cent of cases.
Aetiology
Contemporary opinion on the aetiology of cleft
lip and palate is that cleft lip and palate (CL/P) and isolated cleft palate
have a genetic predisposition and a contributory environmental component. A
family history of cleft lip and palate in which the first-degree relative is
affected increases the risk to one in 25 live births. Genetic influence is more
significant in cleft lip/palate than cleft palate alone where environmental
factors exert a greater influence.
Environmental
factors implicated in clefting include maternal epilepsy and drugs (e.g.
steroids, diazepam, phenytoin), although the benefit of antenatal folic acid
supplement to prevent cleft lip and palate remains equivocal.
Although
most clefts of the lip and palate occur as an isolated deformity, the Pierre
Robin sequence remains the most common syndrome. This syndrome comprises
isolated cleft palate, retrognathia and a posteriorly displaced tongue (glossoptosis),
which is associated with early respiratory and feeding difficulties.
Isolated
cleft palate is more commonly associated with a syndrome than cleft lip/palate
and cleft lip alone. Over 150 syndromes are associated with cleft lip and
palate, although Stickler (ophthalmic and musculoskeletal abnormalities),
Shprintzen (cardiac anomalies), Down’s, Apert’s and Treacher Collins’ are
most frequently encountered.
Classification
Any classification for such a diverse and
varied condition as cleft lip and palate needs to be simple, concise, flexible,
exact but graphic. It must be suitable for computerisation but descriptive and
morphological. An example of such a classification is the LAHSHAL system which
is able to describe site, size, extent as well as type of cleft (Fig.
37.1).
Complete
clefts of the lip, alveolus, and hard and soft palate are designated capital L,
A, H and 5, respectively, whereas incomplete clefts are recorded in small
letters; microform clefts are documented with asterisks. Hence, LAHSHAL is the
anatomical paraphrase of a complete bilateral cleft lip and palate. Another
example, lahSh, represents an incomplete right unilateral cleft lip and alveolus
with a complete cleft of soft palate extending partly on to the hard palate.