Cleft lip is a variation of a type of clefting congenital deformity caused by abnormal facial development during gestation. It is the non-fusion of the body's natural structures that form before birth. Approximately 1 in 700 children born have a cleft lip or a cleft palate or both. In decades past, the condition was sometimes referred to as harelip, based on the similarity to the cleft in the lip of a hare, but that term is now generally considered to be offensive.

Clefts can also affect other parts of the face, such as the eyes, ears, nose, cheeks, and forehead. In 1976, Paul Tessier described fifteen lines of cleft. Most of these craniofacial clefts are even rarer and are frequently described as Tessier clefts using the numerical locator devised by Tessier.

A cleft lip or palate can be successfully treated with surgery, especially so if conducted soon after birth or in early childhood.

The development of the face is coordinated by complex morphogenetic events and rapid proliferative expansion, and is thus highly susceptible to environmental and genetic factors, rationalising the high incidence of facial malformations. During the first six to eight weeks of pregnancy, the shape of the embryo's head is formed. Five primitive tissue lobes grow:

●one from the top of the head down towards the future upper lip; (Frontonasal Prominence)

●two from the cheeks, which meet the first lobe to form the upper lip; (Maxillar Prominence)

●and just below, two additional lobes grow from each side, which form the chin and lower lip. (Mandibular Prominence)

If these tissues fail to meet, a gap appears where the tissues should have joined (fused). This may happen in any single joining site, or simultaneously in several or all of them. The resulting birth defect reflects the locations and severity of individual fusion failures.

The upper lip is formed earlier than the palate, from the first three lobes named a to c above. Formation of the palate is the last step in joining the five embryonic facial lobes, and involves the back portions of the lobes b and c. These back portions are called palatal shelves, which grow towards each other until they fuse in the middle. This process is very vulnerable to multiple toxic substances, environmental pollutants, and nutritional imbalance. The biologic mechanisms of mutual recognition of the two cabinets, and the way they are glued together, are quite complex and obscure despite intensive scientific research.

Genetic factors contributing to cleft lip and cleft palate formation have been identified for some syndromic cases, but knowledge about genetic factors that contribute to the more common isolated cases of cleft lip/palate is still patchy.

Many clefts run in families, even though in some cases there does not seem to be an identifiable syndrome present, possibly because of the current incomplete genetic understanding of midfacial development.

Many genes are known to play a role in craniofacial development and are being studied through the FaceBase initiative for their part in clefting. These genes are AXIN2, BMP4, FGFR1, FGFR2, FOXE1, IRF6, MAFB (gene), MMP3, MSX1, MSX2 (Msh homeobox 2), MSX3, PAX7, PDGFC, PTCH1, SATB2, SOX9, SUMO1 (Small ubiquitin-related modifier 1), TBX22, TCOF (Treacle protein), TFAP2A, VAX1, TP63, ARHGAP29, NOG, NTN1, WNT genes, and locus 8q24.

Environmental influences may also cause, or interact with genetics to produce, orofacial clefting. In humans, fetal cleft lip and other congenital abnormalities have been linked to maternal hypoxia, as caused by e.g. maternal smoking, maternalalcohol abuse or some forms of maternal hypertension treatment. Other environmental factors that have been studied include: seasonal causes (such as pesticide exposure); maternal diet and vitamin intake; retinoids — which are members of the vitamin A family; anticonvulsant drugs; alcohol; cigarette use; nitrate compounds; organic solvents; parental exposure to lead; and illegal drugs (cocaine, crack cocaine, heroin, etc.).

If the cleft does not affect the palate structure of the mouth it is referred to as cleft lip. Cleft lip is formed in the top of the lip as either a small gap or an indentation in the lip (partial or incomplete cleft) or it continues into the nose (complete cleft). Lip cleft can occur as a one sided (unilateral) or two sided (bilateral). It is due to the failure of fusion of the maxillary and medial nasal processes (formation of the primary palate).

A mild form of a cleft lip is a microform cleft. A microform cleft can appear as small as a little dent in the red part of the lip or look like a scar from the lip up to the nostril. In some cases muscle tissue in the lip underneath the scar is affected and might require reconstructive surgery. It is advised to have newborn infants with a microform cleft checked with a craniofacial team as soon as possible to determine the severity of the cleft.

Most children who have their clefts repaired early enough are able to have a happy youth and social life. Having a cleft palate/lip does not inevitably lead to a psychosocial problem. However, adolescents with cleft palate/lip are at an elevated risk for developing psychosocial problems especially those relating to self-concept, peer relationships and appearance. Adolescents may face psychosocial challenges but can find professional help if problems arise. A cleft lip may impact an individual's self-esteem, social skills and behavior. Self-concept may be adversely affected by the presence of a cleft lip and or cleft palate, particularly among girls.

Research has shown that during the early preschool years (ages 3-5), children with cleft lip and or cleft palate tend to have a self-concept that is similar to their peers without a cleft. However, as they grow older and their social interactions increase, children with clefts tend to report more dissatisfaction with peer relationships and higher levels of social anxiety. Experts conclude that this is probably due to the associated stigma of visible deformities and possible speech impediments. Children who are judged as attractive tend to be perceived as more intelligent, exhibit more positive social behaviors, and are treated more positively than children with cleft lip and or cleft palate. Children with clefts tend to report feelings of anger, sadness, fear, and alienation from their peers, but these children were similar to their peers in regard to “how well they liked themselves.”

A baby being fed using a customized bottle. The upright sitting position allows gravity to help the baby swallow the milk more easily. Cleft may cause problems with feeding, ear disease, speech and socialization. Due to lack of suction, an infant with a cleft may have trouble feeding. An infant with a cleft palate will have greater success feeding in a more upright position. Gravity will help prevent milk from coming through the baby's nose if he/she has cleft palate. Gravity feeding can be accomplished by using specialized equipment, such as the Haberman Feeder, or by using a combination of nipples and bottle inserts like the one shown, is commonly used with other infants. A large hole, crosscut, or slit in the nipple, a protruding nipple and rhythmically squeezing the bottle insert can result in controllable flow to the infant without the stigma caused by specialized equipment.

Individuals with cleft also face many middle ear infections which may eventually lead to hearing loss. The eustachiantubes and external ear canals may be angled or tortuous, leading to food or other contamination of a part of the body that is normally self-cleaning. Hearing is related to learning to speak. Babies with palatal clefts may have compromised hearing and therefore, if the baby cannot hear, it cannot try to mimic the sounds of speech. Thus, even before expressive language acquisition, the baby with the cleft palate is at risk for receptive language acquisition. Because the lips and palate are both used in pronunciation, individuals with cleft usually need the aid of a speech therapist.

Traditionally, the diagnosis is made at the time of birth by physical examination. Recent advances in prenatal diagnosis have allowed obstetricians to diagnose facial clefts in utero.

Cleft lip and palate is very treatable; however, most children with a form of clefting are monitored by a cleft palate team or craniofacial team through young adulthood. Care can be lifelong. Treatment can differ between individual cases depending on the type and severity of the cleft, and a series of treatment are needed.

Primary cleft lip repair

3 months of age is standard

●Reconstruction of phitrum, Cupid's bow, and tubercle

●Functional muscle reconstruction

●Symmetry

●Minimal scarring

●Performed at time of primary lip repair (3 months)

●Release and repositioning of cleft nasal components and alar cartilages successfully integrated into primary lip repair without significant growth impairment

12-24 months of age

May be performed at time of palate repair

●Gingivoperiosteoplasty is the primary closure of alveolar cleft by advancing bilateral mucoperiosteal flaps; it is performed at the time of primary cleft lip repair.

●Presurgical orthopedics are usually needed to narrow cleft and align segments so that primary repair is technically feasible.

●Of patients who underwent nasoalveolar molding and gingivoperiosteoplasty, 60% did not require secondary bone grafting.

Rib grafts is placed under mucosal flaps in upper buccal sulcus.

Multiple studies report associated growth impairment.

Modified techniques that limit dissection and avoid the use of vomerine flaps reportedly have improved dental outcomes without growth impairment.

Early secondary: 2-5 years old

Secondary: 5-16 years old

Late secondary: ＞ 16 years old

Optimal timing depends on the severity of the deformity and its effect on the psychosocial development of the patient. Most commonly performed during:

●Preschool: when developing peer interation

●Adolescence: optimal results after cessation of facial growth

●White roll deformities

●Deficient vermilion (whistle deformity)

●Buccal sulcus deformity

●Short lip

●Long lip (bilateral cleft)

●Tight lip

Risk of growth disturbance with septoplasty

May result in bulbous tip in adolescence because of accumulation of fibrofatty tissue and scar

Definitive osteoplastic rhinoplasty and septoplasty after cessation of facial growth

Treatment of maxillary hypoplasia with Le Fort I advancement during adolescence

alveolar [æl'viələ] adj.齿槽的

craniofacial [,kreiniə'feiʃəl] adj.颅面的

embryonic [,embri'ɔnik] adj.胚胎的

gestation [dʒe'steiʃ(ə)n] n.怀孕；妊娠期

gingivoperiosteoplasty [d'ʒigivəʊpriːəʊstiːəʊplæs] n.牙龈骨膜成形术

harelip [heə'lip] n.兔唇；［口腔］唇裂

morphogenetic [,mɔːfəudʒi'netik] adj.有关形态发生的

mucoperiosteal [muːkəʊpriːəʊs'tel] adj.黏膜骨膜的

nasoalveolar [nə'səʊlviələ] adj.鼻牙槽的

nitrate ['naitreit] n.硝酸盐

obstetricians [,ɒbstə'triʃ(ə)n] n.产科医师

orthognathic [əθəg'næθik] n.正颌学的

orthopedics [,ɔːθə'piːdiks] n.矫形术

retinoids [riti'nɔidz] n.类视黄醇

septoplasty [septəʊp'læsti] n.鼻中隔成形术

tubercle ['tjuːbək(ə)l] n.结节

Cupid's bow 唇弓

frontonasal prominence 额鼻突

maxillar prominence 上颌突

mandibular Prominence 下颌突

mucosal flap 黏膜瓣

prenatal diagnosis 产前诊断