Cleft Palate Repair

Rogers and Georgiade expertly reviewed the evolution of cleft palate surgery. ^{[3, 4]} The first record of a palatal operation dates to 500 AD and was prompted by inflammation of the uvula. In 1552, Houlier proposed suturing palatal clefts and 12 years later Ambroise Pare illustrated obturators for palatal perforations. In 1764, Le Monnier, a French dentist, successfully repaired a cleft velum with a few sutures and hot cautery of the edges. von Graefe, 50 years later, produced inflammation of the velar margins before bringing them together in his palate suture and is credited with performing the first velar repair of a cleft in 1816. JC Warren performed the first velar closure in America in 1824.

In 1828, Dieffenbach enhanced the surgical treatment of cleft palate by introducing hard palatal mucosa elevation to allow the closure of hard palatal cleft. von Langenbeck (1859) proposed the creation of a bipedicle mucoperiosteal flap that can be mobilized medially to close the palatal cleft. The improved vascular supply of the mucoperiosteal flap significantly decreased the incidence of dehiscence. See the image below.

The von Langenbeck repair. Two bipedicle mucoperiosteal flaps are created by incising along the oral side of the cleft edges and along the posterior alveolar ridge from the maxillary tuberosities to the anterior level of the cleft. The flaps are then mobilized medially with preservation of the greater palatine arteries and closed in layers. The hamulus may need to be fractured to ease the closure.

View Media Gallery

With the ability to successfully close the palate, concern about palatal function was raised. It was evident by this time that the short and immobile palate impaired the speech capability of patients with cleft palate. Veau, ^[5] Kilner, ^[6] and Wardill ^[7] described the unipedicled mucoperiosteal flap based posteriorly on the greater palatine artery that pushed the flap posteriorly to lengthen the palate. The scarring of the denuded bone areas anteriorly and laterally was suspected as the cause of facial growth retardation posteriorly.

In 1994, Schweckendiek advocated the use of a 2-stage cleft palate closure. The soft palate was closed early, with closure of the hard palate delayed until several years later. The rationale for the 2-stage procedure was to provide improved velopharyngeal function during the initial speech development and to accomplish the closure of the hard palate after the cleft narrows with facial growth. Anatomic muscle realignment has also been postulated as essential in improving postoperative velopharyngeal function.

A topic for debate has been over the treatment of the alveolar cleft that accompanies the cleft palate. The rationale for its closure includes stabilizing the maxillary arch, providing support for tooth eruption and postsurgical orthodontics, closing oronasal fistulae, and improving the aesthetics of the mid face and nose. The current trend is toward secondary bone grafting at the time of mixed dentitia, with early (primary) grafting potentially proving detrimental to midfacial growth.

Much discussion has centered over the role and timing of presurgical appliances. Both the hard palate and the alveolus can be molded with passive molds and active devices, with the shared ultimate goals of facilitating surgical repair and providing an improved long-term outcome in both facial form and palatal function.

These historic developments in the treatment of the cleft palate underlie the existing controversies still found today.

Classification

Numerous classifications have been suggested over the years. Kernahan's classification system is the most common one used. This "striped Y" classification has been almost universally adopted for its simplicity and usefulness. See the image below.

Millard modification of Kernahan striped-Y classification for cleft lip and palate. The small circle indicates the incisive foramen; the triangles indicate the nasal tip and nasal floor.

View Media Gallery

Embryology

The embryogenesis of the palate can be divided into two separate phases: the formation of the primary palate followed by the formation of the secondary palate. Palatal development begins at approximately day 35 of gestation with the emergence of facial processes. The fusion of the medial nasal process (MNP) with the maxillary process (MxP), followed by the lateral nasal process (LNP) with the MNP, completes the formation of the primary palate. Failure of fusion or breakdown of fusion of the processes results in a cleft of the primary palate. The genesis of the secondary palate begins at the completion of the primary palate formation. The secondary palate arises from the bilateral shelves that develop from the medial aspect of the MxP. The two shelves meet in the midline with the elevation of the shelves. As the shelves move superiorly, the fusion process begins. Interference in the fusion leads to clefting of the secondary palate.

Frequency

The incidence of cleft lip/palate by race is 2.1/1000 in Asians, 1/1000 in whites, and 0.41/1000 in blacks. Isolated cleft palate shows a relatively constant ratio of 0.45-0.5/1000 births. The foremost type of clefting is a bifid uvula, occurring in 2% of the population. The second most frequent type is a left unilateral complete cleft of the palate and prepalatal structures. Midline clefts of the soft palate and parts of the hard palate are also common. Complete clefts of the secondary palate are twice as common in females as in males while the reverse is true of velar clefts. About 7-13% of patients with isolated cleft lip and 11-14% of patients with cleft lip/palate have other anomalies at birth. A comprehensive review of syndromes associated with cleft lip/palate is beyond the objectives of this article. For more information, see Medscape Reference article Reconstructive Surgery for Cleft Palate.

Recurrence risks for clefting deformities do not correspond to any Mendelian pattern of inheritance and it would appear that clefting is inherited heterogeneously. This observation is supported by evidence from studies of twins that indicate the relative roles of genetic and nongenetic influences of cleft development. For isolated cleft palate and combined cleft lip and palate, if the proband has no other affected first- or second-degree relatives, the empiric risk of a sibling being born with a similar malformation is 3-5%. However, if a proband with a combined cleft lip and palate has other affected first-degree relatives, the risk for siblings or subsequent offspring is 10-20%.

In 25% of patients, there is a family history of facial clefting, which does not follow either a normal recessive or dominant pattern. The condition appears to be multifactorial. Some instances of clefting may be because of an overall reduction in the volume of the facial mesenchyme, which leads to clefting by virtue of failure of mesodermal penetration. In some patients, clefting appears to be associated with increased facial width, either alone or in association with encephalocele, idiopathic hypertelorism, or the presence of a teratoma. The characteristic U-shaped cleft of the Pierre Robin anomaly is thought to be dependent upon a persistent high position of the tongue, perhaps associated with a failure or delay of neck extension. This prevents descent of the tongue, which in turn prevents elevation and a medial growth of the palatal shelves.

The production of clefts of the secondary palate in experimental animals has frequently been accomplished by drug administration. Agents commonly used are steroids, anticonvulsants, diazepam, and aminopterin. Phenytoin and diazepam may also be causative factors in clefting in humans. Infections during the first trimester of pregnancy, such as rubella or toxoplasmosis, have been associated with clefting.

An international study (Democratic Republic of the Congo, the Philippines, Vietnam, and Honduras) by Figueiredo et al indicated that parental risk factors for oral clefts include older maternal age, pregestational hypertension, gestational seizures, a lower maternal and paternal education level, and paternal tobacco smoking, as well as a family history of oral clefts. ^[8]

The pathologic sequelae of cleft palate include feeding and nutritional difficulties, recurrent ear infections, hearing loss, abnormal speech development, and facial growth distortion. The communication between the oral and nasal chamber impairs the normal sucking and swallowing mechanism of the cleft infants. Food particles reflux into the nasal chamber.

The abnormal insertion of the tensor veli palati prevents satisfactory emptying of the middle ear. Recurrent ear infections have been implicated in the hearing loss of patients with cleft palate. The hearing loss may worsen the speech pathology in these patients. Evidence that repair of the cleft palate decreases the incidence of middle ear effusions is inconsistent. However, these problems are overshadowed by the magnitude of the speech and facial growth problems.

Speech abnormalities are intrinsic to the anatomic derangement of cleft palate. The facial growth distortion appears to be, to a great extent, secondary to surgical interventions. Along with an intact hard palate, an intact velopharyngeal mechanism is essential in production of high pressure consonants and the oral resonance of vowels. The velopharyngeal mechanism must also remain open to some degree to accomplish nasal resonance of m, n, and ng. With connected spontaneous speech, oral and nasal speech contexts are rapidly coarticulated, resulting in the complex need for millisecond timing of velopharyngeal closure and opening, depending on the speech targets. ^[9]

Experimentation with this velopharyngeal activity begins with babbling and continues through the early language learning years. Without sufficient velopharyngeal function during this early learning period, compensatory strategies may be adopted, with consonants produced in the pharynx to create pressure buildup. These compensatory strategies are difficult to change, and always require speech therapy intervention, often with the need for additional surgical reconstruction.

Multiple studies have demonstrated that the cleft palate maxilla has some intrinsic deficiency of growth potential. This intrinsic growth potential varies from isolated cleft of the palate to complete cleft lip and palate. This growth potential is further impaired by surgical repair. Any surgical intervention performed prior to completion of full facial growth can have significant deleterious effects on maxillary growth. Disagreement exists as to the appropriate timing of surgery to minimize the harmful effects on facial growth and on what type of surgical intervention is most responsible for growth impairment. The formation of scar and scar contracture in the areas of denuded palatal bones are most frequently blamed for restriction of maxillary expansion.

The growth disturbance is exhibited most prominently in the prognathic appearance during the second decade of life despite the normal appearance in early childhood. The discrepant occlusion relationship between the maxilla and the mandible is usually not amenable to nonsurgical correction.

The following 4 points should be emphasized in the presentation of an infant with cleft lip/palate.

Feeding

Although a child with cleft palate may make sucking movements with the mouth, the cleft prevents the child from developing normal suction. However, in general, swallowing mechanisms are normal. Therefore, if milk or formula can be delivered to the back of the child's throat, the infant feeds effectively. Breastfeeding is usually not successful, unless milk production is abundant, but most infants can bottle feed with more specially designed bottles and nipples.

Airway

The infant with Pierre Robin anomaly or other conditions in which the cleft palate is observed in association with a micrognathia or retrognathic mandible may be particularly prone to upper airway obstruction.

Middle ear disease

The disturbance in anatomy associated with cleft palate affects the function of the eustachian tube orifices. Parents and physicians should be aware of the increased possibility of middle ear infection so that the child receives treatment promptly if symptoms arise.

Associated deformities

The surgeon must always keep in mind that in as many as 29% of patients, the child with cleft palate may have other anomalies. These may be more commonly associated with isolated cleft palate than with cleft lip/palate. High among the associated anomalies are those affecting the circulatory and skeletal systems.

Children born with a cleft palate should undergo surgical repair unless otherwise contraindicated. The main goal is to perform a functional repair of the soft palate musculature through the repositioning of the abnormally-oriented and attached muscles. This anatomic repair attempts to facilitate the development of normal speech. While separation of the oral and nasal cavities is advantageous to normalize feeding and decrease regurgitation and nasal irritation, it is not absolutely necessary for feeding.

Palate repair with repositioning of the palatal musculature may be advantageous to eustachian tube function and ultimately to hearing. Because the levator and the tensor veli palatini have their origins along the eustachian tube, repositioning improves function of these muscles, improves ventilation of the middle ear, and decreases serous otitis, which further decreases the incidence of hearing abnormality. Palate repair alone does not usually completely correct this dysfunction and additional therapy frequently includes placement of ear tubes as necessary.

The bony portion of the palate is a symmetric structure with division based on the embryonic origin into the primary and secondary palate. The premaxilla, alveolus, and lip, which are anterior to the incisive foramen, are parts of the primary palate. Structures posterior to it, which include the paired maxilla, palatine bones, and pterygoid plates, are part of the secondary palate. The severity of the clefting of the bony palate varies from simple notching of the hard palate to clefting of the alveolus. See the image below.

Anatomy of the palate.

View Media Gallery

The palatine bone is located posterior to the maxilla and pterygoid lamina. It is composed of horizontal and pyramid processes. The horizontal process contributes to the posterior aspect of the hard palate and becomes the floor of the choana. The pyramidal process extends vertically to contribute to the floor of the orbit.

Even though the bony defect is important in the surgical treatment of cleft palate, the pathology in the muscles and soft tissues has the greatest impact on the functional result. Six muscles have attachment to the palate: levator veli palatini, superior constrictor pharyngeus, uvulus, palatopharyngeus, palatoglossus, and tensor veli palatini. The 3 muscles that appear to have the greatest contribution to the velopharyngeal function are the uvulae, levator veli palatini, and superior constrictor pharyngeus. The uvulae muscle acts by increasing the bulk of the velum during muscular contraction. The levator veli palatini pulls the velum superiorly and posteriorly to appose the velum against the posterior pharyngeal wall. The medial movement of the pharyngeal wall, attributed to superior constrictor pharyngeus, aids in the opposition of the velum against the posterior pharyngeal wall to form the competent sphincter. The palatopharyngeus displace the palate downwards and medially.

The palatoglossus is mainly a palatal depressor that plays a role in the production of phonemes with nasal coupling by allowing controlled airflow into the nasal chamber. The tensor veli palatini does not contribute to the movement of the velum. The tensor veli palatini's tendons hook around the hamulus of the pterygoid plates and the aponeurosis of the muscle inserts along the posterior border of the hard palate. The muscle originates partially on the cartilaginous border of the auditory tubes. The function of the tensor veli palatini, similar to tensor tympani with which it shares similar innervation, is to improve the ventilation and drainage of the auditory tubes.

In cleft palate, the aponeurosis of the tensor veli palatini, instead of attaching along the posterior border of the hard palate, is attached along the bony cleft edges. All the muscles that attach to the palate insert onto the aponeurosis of this muscle. Thus, the overall length of the palate is shortened. The abnormality in the tensor veli palatini increases the incidence of middle ear effusion and middle ear infection.

The muscle sling of the levator veli palatini is also interrupted by cleft palate. The levator does not form the complete sling. The medial portion of each side attaches to the medial edge of the hard palate. Thus, in patients with cleft palate, the effectiveness of the velar pull against the posterior pharyngeal wall is impaired. Of the 6 muscles, the prevailing theory attributes most of the contribution to the velopharyngeal competence to the levator veli palatini.

No absolute contraindications exist for the repair of cleft palate.

Relative contraindications include current illness or other medical condition that can interfere with general anesthesia, possible compromise of the airway in a child with a preexisting airway problem (such as severe micrognathia), severe developmental delay, or a short life expectancy because of other severe illnesses.