“What Causes Cleft Lips and Palates?” is one of the most common questions we hear from parents of children with cleft lips and palates, and why this happened to their child, and whether something could be done differently to prevent clefting in other children. Although it has been extensively studied, we do not know exactly what causes cleft lips and palates.
We do not know exactly what causes cleft lips and palates
Cleft lip and cleft palate, disorders which involve incomplete fusion of the structures of the upper lip and or palate, are among the most common craniofacial anomalies. Recently, these disorders have garnered significant media and public attention. There have been multiple websites and charitable organizations devoted to children with cleft lips and palates, often with striking “before and after” photographs. One may mistakenly believe that they are cosmetic defects that can be completely treated with a simple operation, requiring no further ongoing care. In reality, cleft lip and cleft palate are complex diagnoses than can affect not only appearance, but speech, eating, hearing, and growth of the face. Successful treatment requires a team approach of different but collaborating specialties evaluating and treating the patient throughout his or her childhood.
What causes cleft lips and palates?
When discussing the causes of orofacial clefts (cleft lips and palates), it is useful to separate those clefts associated with a syndrome (syndromic clefts) from those that are not (sporadic clefts). A syndrome is a condition in which multiple symptoms occur together; a syndrome involving a cleft lip or palate would include other signs or symptoms than just the cleft. The majority of cleft lips and palates are sporadic, or not associated with a syndrome. Approximately 12% of cleft lips and over 40% of cleft palates are syndromic. Patients with clefts associated with a syndrome may need medical evaluation and treatment of other symptoms or defects in addition to the cleft. In addition, they may benefit from referral to a geneticist.
The causes of nonsyndromic orofacial clefts are thought to be multifactorial, which means that a combination of genetic and environmental factors contributes to development of the cleft. The majority of cleft patients have no identifiable cause. The strongest risk factor for development of a cleft is family history. Other risk factors include maternal smoking, consumption of large amounts of alcohol during the first trimester of pregnancy, certain medications taken during the first trimester, and maternal diabetes mellitus (but not gestational diabetes). There has been shown to be a decreased risk of cleft lip and palate with the use of prenatal vitamins and folic acid.
What is the risk of a cleft lip or palate in any future children?
The risk of a future child being born with a cleft lip or palate also depends on whether the cleft is associated with a syndrome. Patients with syndromic clefts may have a known risk of clefting for siblings or children. For example, patients with van der Woude syndrome are born with cleft lips and lower lip pits. There is approximately a 50% chance that their children will inherit the condition. For this reason, referral to a geneticist is an important part of the care of children with syndromic clefts.
For patients with sporadic, or nonsyndromic clefts, there is a small risk for recurrence, or for the cleft to occur in future siblings or children. A recent large study in Denmark identified the risk in a future siblings of patients with cleft lip and palate of 3.9%. This risk varied by the type and severity of the cleft.
How do cleft lips and cleft palates develop?
By the time of the first ultrasound in which the fetus’ facial structures can be identified, clefting of the lip or palate will already have occurred. Development of the facial structures and form occurs between the 4th and 8th weeks of gestation. During the 4th week of development, a series of six paired (right and left) swellings form near the cranial, or head, end of the fetus. These are called branchial arches. The branchial arches develop into important structures in the head and neck, as well as the major arteries in the chest. The first branchial arch develops structures called the maxillary and mandibular prominences, which ultimately form the skeleton, skin, muscles, and other structures of the upper (maxilla) and lower (mandible) jaws. In the center of the upper face, a structure called the frontonasal prominence, which is separate from the branchial arches, forms, among other things, the nostrils and the philtrum. The medial maxillary prominences fuse with the frontonasal prominence during this time. Failure of this process results in a cleft lip.
The palate is also formed by fusion of the frontonasal prominence and the maxillary prominences. Although the palate appears to be one complete structure, it actually consists of a primary palate, behind the front teeth, and a secondary palate, which includes the majority of the hard and soft palate. These are separated by a hole in the palatal bone called the incisive foramen. The 2 sides of the secondary palate begin to fuse during the 8th week of development. Failure of fusion results in a cleft palate.
What are the types of cleft lips and palates?
Orofacial clefts, or cleft lips and palates, may occur in a variety of ways with differing severity. There have been a number of classification schemes developed to describe clefts. Patients can be born with isolated cleft lip, isolated cleft palate, or cleft lip and palate. The cleft of the lip or palate can be complete or incomplete. Clefts can occur on one side only (unilateral) or on both sides (bilateral).
Complete cleft lip
Complete cleft lips involve the vermilion (red lip), the skin between the vermilion and the nose, and the floor of the nose. The alveolus (tooth bearing segment of the palate) is typically clefted, as well. In addition to the skin and vermilion, the cleft involves the muscle beneath the skin, called the orbicularis oris. The nose has deformities on the skin and cartilage. Each of these structures must be addressed during a chieloplasty (cleft lip repair).
Incomplete cleft lip
In an incomplete cleft lip, part of the lip or nasal floor is intact. Incomplete clefts may involve only a small part of the lip. In some patients, the majority of the lip is affected by the cleft, while there is a small intact area at the base of the nose. This is called a Simonart band. The least severe form of a cleft lip is called a forme fruste, or microform cleft lip. This may manifest only as a small indentation.
Unilateral versus bilateral cleft lip
Unilateral cleft lips involve only one side of the lip. When both sides are affected, it is termed a bilateral cleft lip. It is possible for both sides to have a complete cleft, or for both sides to be incomplete, or for one side to be complete and the other incomplete.
The alveolus is the tooth-bearing segment of the palate, immediately behind the lip. The anterior (front part) palate is called the primary palate and is related developmentally more to the lip than to the majority of the hard and soft palate. It is therefore possible to have a cleft in the alveolus along with a cleft lip, while the remainder of the palate is intact. Alternatively, the cleft may involve the lip, alveolus, and complete palate. Repair of the alveolus involves bone grafting, and occurs later in childhood than the repair of the lip or palate.
Similar to the lip, clefting of the palate may be complete or incomplete. Complete cleft palates involve the alveolus, the hard palate, and the soft palate or velum. Incomplete cleft palates may involve some or all of the soft palate, with or without part of the hard palate. The palatal cleft may also be either unilateral or bilateral.
Like the lip, the palate involves multiple important structures. The pink lining is called the mucosa; this lines both the lining of the nose (nasal mucosa), and the mouth (oral mucosa). The hard palate has bone sandwiched between the oral and nasal mucosa. The soft palate houses muscles important for speech production. Failure of the palatal muscles to function properly may lead to problems with speech called velopharyngeal insufficiency, or VPI.
How are cleft lips and palates treated?
Successful treatment of cleft lips and palates requires collaboration with several different specialists throughout the patient’s childhood. The Craniofacial Team of Texas is a multidisciplinary team consisting of surgeons, orthodontists, dentists, otolaryngologists, speech therapists, social workers, a craniofacial pediatrician, and nurses expert in the treatment of patients with cleft lips and palates. The team meets regularly to discuss the patients, and patient visits are coordinated so that the patient is seen by each of the relevant specialists during one visit. This allows for seamless care and collaboration.
Treatment of patients with clefts often involves multiple steps, based on the patient’s age and development. Below is a typical timeline, which may vary depending on the characteristics and development of the specific patient.
Age 0-3 months – Cleft Lip and Cleft Palate Treatment
This is the time period prior to repair of the cleft lip. The patient and family will meet the craniofacial team, and be assessed by the team pediatrician and nurses. This allows for help with feeding, and allows the team to ensure that the child is thriving, developing, and gaining weight. If appropriate, this is also the time that the child is treated with taping or nasoalveolar molding (NAM) prior to cleft lip repair.
Age 3-4 months – Cleft Lip and Cleft Palate Treatment
Repair of the cleft lip, or chieloplasty, is generally performed between 3-4 months. At this age, surgery and the necessary anesthesia become safer. Waiting until this time also allows time for NAM, and for the lip and nose structures to develop for a more accurate lip repair.
Age 9-12 months – Cleft Lip and Cleft Palate Treatment
Repair of the palate, or palatoplasty, is generally performed at between 9-12 months of age. Patients with cleft palates are able to eat, drink, and obtain adequate nutrition. The goal of palatoplasty is to allow for the normal production of speech. There is evidence that earlier repair of the palate may risk future growth problems of the upper jaw, or maxilla. In addition, prior to this age, the patient is not yet producing speech. Repair of the palate is timed to minimize the potential growth risks, and to allow for the production of normal speech when the patient is just beginning to develop the ability to produce sounds for which the palate is necessary.
In addition to being important for speech production, the palate contains muscles which help depressurize and clear the ears. These muscles are called the tensor velli palatine. In people with intact palates, these muscles help clear the eustacean tubes (auditory tube), which connects the inner ear canal to the mouth. These are the muscles which help your ears pop when you yawn or are changing altitude in an airplane. In patients with cleft palates, these muscles are unable to depressurize the eustacean tubes, which may lead to fluid buildup and infections. Patients are assessed by otoloaryngologists for fluid buildup prior to palatoplasty. If indicated, ear tubes (tympanostomies) can be placed at the time of palatoplasty to help prevent infections and hearing loss.
Age 1-3 years – Cleft Lip and Cleft Palate Treatment
This is the time in which the child continues to develop speech. Patients are evaluated by speech therapists and the plastic surgeons to determine whether they have velopharyngeal insufficiency. Treatment, if necessary, may include speech therapy or surgery (please see speech and speech surgery pages).
Age 3-7 years – Cleft Lip and Cleft Palate Treatment
During this time, patients typically have annual cleft team visits in which speech is assessed, and well as dental checkups. Depending on the healing from the cleft lip repair, the patient may benefit from small revision operations to the lip or nose.
Age 7-10 years – Cleft Lip and Cleft Palate Treatment
Patients with clefts that include the alveolus, or tooth-bearing area of the palate, typically undergo repair of this defect by alveolar bone grafting at this age. Timing of repair depends on many factors, including the timing of the eruption of permanent teeth in the area of the alveolar cleft. The goals of alveolar bone grafting include repairing the hole between the nose and the mouth (oronasal fistula) which accompanies the alveolar cleft, stabilization of the width of the palate, and providing adequate bone stock to support the erupting permanent teeth. The patient will be treated by the orthodontics team, in the year or more prior to alveolar bone grafting, with braces and palatal expanders to get ready for surgery (please see alveolar bone graft page).
Teenage years – Cleft Lip and Cleft Palate Treatment
For certain aspects of the care of patients with cleft lips and palates, it is important that the patient be near skeletal maturity, or nearly done growing. Patients will continue to be treated by the orthodontics team. Certain patients with clefts develop maxillary hypoplasia, or poor growth of the upper jaw (maxilla) relative to the lower jaw. Some of these patients may be treated by orthodontics alone; however, for some patients, the discrepancy is sufficiently large to warrant jaw surgery, called orthognathic surgery.
Final Stage – Cleft Lip and Cleft Palate Treatment
The final stage in the treatment of many patients with cleft lips and palates is the rhinoplasty, or nose surgery. This surgery is delayed until the patient is finished growing, and has a stable skeletal base to ensure the best result in one operation (please see rhinoplasty page).
Summary of Cleft Lip and Cleft Palate Treatment
Treatment of patients with cleft lips and palates involves multiple specialists, and a continuum of care throughout childhood. The Craniofacial Team of Texas multidisciplinary cleft team provides expert, coordinated care for all aspects of cleft patients and their families.
1) Grosen D, Chevrier C, Skytthe A, et al. A cohort study of recurrence patterns among more than 54,000 relatives of oral cleft cases in Denmark: support for the multifactorial threshold model of inheritance. J Med Genet 2010;47:162-8.
If you would like more information about this craniofacial anomaly, please contact the Craniofacial Team of Texas by calling 512-377-1142 or toll free 877-612-7069 to schedule an appointment or complete an online appointment request.