Classification and clinical features of cl and cp

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Cleft Lip (CL) and Cleft Palate (CP) - Classification and Clinical Features

Cleft lip and/or palate (CL/P) is the most common congenital orofacial abnormality, occurring in approximately 1:600 live births. They may occur in isolation or as part of over 300 recognized syndromes.

Incidence Distribution

Type	Frequency
Cleft lip alone	~15%
Cleft lip + palate	~45%
Isolated cleft palate	~40%

Cleft lip ± palate is more common in males
Isolated cleft palate is more common in females

Classification

Anatomical Landmark - The Incisive Foramen

The incisive foramen is the key embryologic reference point dividing the palate into:

Primary palate (anterior to incisive foramen): premaxilla, lip, nasal tip, and columella
Secondary palate (posterior to incisive foramen): hard palate + soft palate, extending to the uvula

Two Major Phenotypic Groups

Group 1 - Cleft Lip with or without Cleft Palate (CL±P) Involves structures anterior to the incisive foramen (primary palate), with or without extension posteriorly.

Group 2 - Isolated Cleft Palate (CP) Involves the secondary palate only; embryologically and epidemiologically distinct from Group 1.

Classification of Cleft Lip

Type	Description
Unilateral	One side only (specify left or right)
Bilateral	Both sides
Complete	Involves entire vertical height of upper lip, often with alveolar cleft
Incomplete	Involves only a portion of the lip height; a variable band of continuity remains across the cleft
Forme fruste / Microform	Minimal cleft - muscular diastasis with intact overlying skin only
Simonart band	A bridge of lip tissue (usually skin, sometimes with muscle) crossing an otherwise complete cleft gap

(Source: Cummings Otolaryngology Head & Neck Surgery)

Classification of Cleft Palate

Type	Description
Cleft uvula	Mildest form - bifid uvula only
Incomplete cleft palate	Soft palate ± part of hard palate; hard palate remains attached to nasal septum/vomer
Complete cleft palate	Full separation; nasal septum/vomer completely separated from palatine processes
Unilateral	Maxillary process on one side fused with nasal septum
Bilateral	No fusion of maxilla to nasal septum on either side
Submucous cleft palate (SMCP)	Least severe; intact mucosa but deficient/misdirected underlying musculature
Primary palate cleft	Anterior to incisive foramen (CL ± alveolus)
Secondary palate cleft	Posterior to incisive foramen (soft and/or hard palate)
Combined	Involves both primary and secondary palate

(Source: Cummings Otolaryngology; Bailey & Love's Surgery)

Classification Diagram (The Developing Human - Moore)

Clinical Features

Cleft Lip

Unilateral Cleft Lip:

Disruption of the nasolabial and bilabial muscle chains (orbicularis oris)
The orbicularis muscle fibres, instead of running transversely, are misdirected and insert into the base of the columella on the cleft side and into the alar base
Nasal deformity: the alar cartilage on the cleft side is displaced downward and outward; the columella is deviated away from the cleft
The nasal tip is asymmetric, with a widened alar base on the cleft side

Bilateral Cleft Lip:

Disruption is greater but often symmetrical
Bilateral flaring of the nose (absence of nasolabial muscle continuity)
Protrusive premaxilla - often projecting significantly forward
Prolabium - a strip of skin in front of the premaxilla devoid of muscle
Cartilaginous and skeletal deformities influence the overlying mucocutaneous tissues

Cleft Palate

Hard palate features:

Failure of fusion of the two palatine shelves
In complete cleft: the median part of the palatal vault is absent; palatal fibromucosa is reduced in size
Communication between oral and nasal cavities

Soft palate features:

In a normal palate, levator veli palatini fibres run transversely with no significant attachment to hard palate
In a cleft palate, muscle fibres are oriented anteroposteriorly, inserting abnormally into the posterior edge of the hard palate
This misdirected musculature critically impairs velopharyngeal closure

Submucous Cleft Palate (SMCP) - Classic Triad:

Bifid uvula
Zona pellucida - a bluish midline streak from deficient muscle under intact mucosa
Notch in the posterior hard palate (palpable rather than visible)

(Note: Diagnosis of SMCP does not require all three features)

Functional Consequences

Problem	Mechanism
Feeding difficulty	Inability to create negative intraoral pressure for suckling
Speech disorders	Velopharyngeal insufficiency; hypernasal speech
Recurrent otitis media / hearing loss	Eustachian tube dysfunction due to levator veli palatini abnormality
Dental abnormalities	Missing, supernumerary, or malformed teeth; malocclusion
Nasal deformity	Alar cartilage displacement, septal deviation
Psychosocial impact	Altered facial appearance and speech

Associated Syndromes

Isolated cleft palate is more commonly syndromic than CL±P. Frequently associated syndromes include:

Stickler syndrome (ophthalmic + musculoskeletal features)
DiGeorge syndrome (cardiac + thymic anomalies; 22q11 deletion)
Down syndrome (Trisomy 21)
Apert syndrome (craniosynostosis + syndactyly)
Treacher Collins syndrome (mandibulofacial dysostosis)
Pierre Robin sequence (micrognathia + glossoptosis + CP)

Over 150 named syndromes are associated with cleft lip and palate. All children born with a cleft should be screened for other congenital abnormalities and offered genetic counselling where syndromic cause is suspected.

Sources: Bailey & Love's Short Practice of Surgery 28e, p. 762-765 | Cummings Otolaryngology Head & Neck Surgery, Ch. 188 | The Developing Human: Clinically Oriented Embryology, p. 537-541

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