Bilateral Cleft Lip Repair

Introduction
The presence of bilateral cleft lip and palate has the potential to significantly alter facial form and structure. The central third of the face is distorted by the bilateral cleft, and restoring the normal facial form is one of the primary goals for the reconstructive surgeon.

· Craniofacial, Bilateral Cleft Nasal Repair
· Craniofacial, Cleft Palate
· Craniofacial, Cleft Palate Repair
· Craniofacial, Unilateral Cleft Lip Repair
· Craniofacial, Unilateral Cleft Nasal Repair

History of the Procedure

The history of bilateral cleft lip repair has evolved from discarding the premaxilla and prolabium and approximating the lateral lip elements to a definitive lip and primary cleft nasal repair utilizing the underlying musculature. Accompanying the evolution of surgical repair is the increasingly important role of orthodontic support with early presurgical alveolar and nasal molding.1 Repositioning the maxillary and alveolar segments into a more anatomic position allows the surgeon to repair the lip and associated nasal deformity under more optimal conditions. The reader is referred to the references cited for a more detailed historical review of individual repairs and supportive management.
Problem
The cleft affects the obvious facial form as an anatomic deformity and has functional consequences, affecting the child's ability to eat, speak, hear, and breathe. Consequently, rehabilitation of a child born with a facial cleft must involve a multidisciplinary approach and be staged appropriately with the child's development. The need for intervention must be balanced against its subsequent effect on normal growth. In the child born with a bilateral cleft, the surgeon initially is faced with a protrusive premaxilla and the difficulty of achieving adequate columellar length and vertical height to the lip during reconstruction.

Bilateral cleft lip repair. (A) The prolabial width is typically set at 4-5 mm. (B) The prolabial flap is elevated to the base of the columella. The adjacent flaps are turned over to create a labial sulcus. (C) The orbicularis oris muscle, dissected from the overlying skin, is approximated across the midline. (D) The skin is approximated, and the Cupid's bow is created from the lateral vermilion flaps.


Frequency

The overall occurrence of cleft lip with or without cleft palate is approximately 1 in 750-1000 live births, making it the second most common congenital deformity (after club foot). Incidence varies by race, with clefts occurring more commonly in Asians (1 in 500 births), less frequently in Caucasians (1 in 750 births), and even less frequently in African Americans (1 in 2000 births). These racial variations in incidence are not observed with the isolated cleft palate. In terms of gender, the incidence of cleft lip/palate is more common in males, while the incidence of cleft palate alone is more common in females.
The most common presentation is cleft lip and palate (approximately 45%), followed by cleft palate alone (35%) and cleft lip alone (approximately 20%). Unilateral cleft lips are more common than bilateral cleft lips and occur more commonly on the left side (left cleft lip:right cleft lip:bilateral cleft lip - 6:3:1). In a large series reported in the literature, bilateral clefts are observed in approximately 15% of patients with clefts.2,3,4

Bilateral clefts occur in approximately 1 in 5000-6500 births based on the overall occurrence. According to CDC estimates, the overall incidence of orofacial clefts is 1 in 596, with the highest incidences occurring in Native Americans (3.6 in 1000) and the lowest in African Americans.5,6
According to the American Society of Plastic Surgeons (ASPS), 18,859 cleft lip and palate reconstructive procedures were performed in the United States in 2007.7 These statistics include procedures performed by ASPS members as well as other board-certified physicians most likely to perform plastic surgery procedures.

Etiology

Clefting is a multifactorial issue, with both genetic and environmental causes cited. The observation of clustered cases of facial clefts in a particular family indicates a genetic basis. Clefting of the lip and/or palate is associated with more than 150 syndromes. The overall incidence of associated anomalies (eg, cardiac) is approximately 30% (more common with isolated cleft palate).

Environmental causes, such as viral infection (eg, rubella) and teratogens (eg, steroids, anticonvulsants), during the first trimester of pregnancy have been linked to facial clefts. The risk also increases with parental age, especially when older than 30 years, with the father's age appearing to be a more significant factor than the mother's age. Nevertheless, most presentations are of isolated patients within the family without an obvious etiology.

Midfacial development involves several sets of genes, including those involved in cell patterning, proliferation, and signaling. Mutations in any of these genes can change the developmental process and contribute to cleft development. Some of these genes include the DIX gene, sonic hedgehog (SHH) gene, transforming growth factor (TGF) alpha and beta, and interferon regulatory factor (IRF6) gene.

Pathophysiology

While the normal embryologic development of the face is detailed in Head and Neck Embryology, a brief outline relevant to the formation of facial clefts follows.

In short, the branchial arches are responsible for the formation of several areas, including the mouth and lip. Mesenchymal migration and fusion occurs during weeks 4-7 of gestation. The first branchial arch is responsible for the formation of the maxillary and mandibular processes. The maxillary and mandibular prominences form the lateral borders of the primitive mouth or stomodeum.

Mesenchymal migration and fusion of the primitive somite-derived facial elements (central frontonasal, 2 lateral maxillary, mandibular processes), at 4-7 weeks gestation, are necessary for the normal development of embryonic facial structures. When migration and fusion are interrupted for any reason, a facial cleft develops along embryonic fusion lines. The embryonic development of the primary palate (lip and palate anterior to the incisive foramen) differs from the secondary palate (palate posterior to the incisive foramen).

The developing processes of the medial nasal prominence, lateral nasal prominence, and maxillary prominences form the primary palate. Fusion occurs, followed by "streaming" of mesodermal elements derived from the neural crest. In contrast, the secondary palate is formed by the fusion of palatal processes of the maxillary prominence alone. The difference in embryonic development suggests the possibility of differing degrees of susceptibility to genetic and environmental influences and accounts for the observed variation in incidences. In summary, a bilateral cleft lip results from the failure of fusion of the medial nasal prominences with the maxillary prominences bilaterally.

Kernahan developed a classification scheme in which the defect can be classified onto a Y-shaped symbol. In this diagram, the incisive foramen is represented as the focal point. This system has been applied to both cleft lip and palate.

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.


Presentation

As with the unilateral cleft, a wide range of clinical presentations of the bilateral cleft lip and palate is possible, from the simple microform cleft to the complete cleft bilaterally involving the lip, alveolus, palate, and nose. Bilateral cleft lip is typically classified as either complete or incomplete.
In addition, the cleft may present with varying degrees of asymmetric involvement of the lip and palate. Any degree of combination of involvement of the lip, primary palate, and secondary palate can exist. Recognizing these potentially asymmetric variations is essential in planning operative treatment and evaluating postoperative results.
In the complete form of clefts, the premaxilla is unrestrained by the lateral maxillary segments and the vomer grows anterior to the lateral segments. This distorts the alar cartilages away from the nasal tip and stretches the alae across a widening cleft. The columella is significantly deficient, can be virtually nonexistent and without a distinct demarcation from the prolabium, which also is vertically deficient. No prolabial muscle, philtral columns, dimples, or Cupid's bow is present. No nasal floor is present, as the cleft continues through the palatal shelf along either side of the vomer through the soft palate.
Further treatment planning

Orthodontic treatment can be initiated a few weeks following birth, prior to surgical intervention. Other adjunct procedures include lip adhesion, presurgical orthopedics, primary nasal correction, and nasoalveolar molding. These procedures attempt to reduce the deformity. Nasoalveolar molding is the active molding and repositioning of the nasal cartilage and alveolar processes with an appliance. This orthodontic intervention takes advantage of the plasticity of the cartilage.
Presurgical nasal alveolar molding allows repositioning of the maxillary alveolus and surrounding soft tissues in hopes of reducing wound tension and improving results. Definitive repair is delayed until approximately 3 months of age, depending on physician comfort. A multidisciplinary approach should be carried out over a period of several years for patients with unilateral cleft lip. This multidisciplinary treatment team should include specialists in audiology, ENT, and speech therapy, among others.

The key difference between the treatment of unilateral versus bilateral cleft lips centers around the concept of aligning the 3 maxillary segments (the lateral lip segments with the prolabial segments). Presurgical orthopedics may be used to prevent the maxillary segments and premaxilla from collapse.

Presurgical orthopedics can involve the following:
· Finger massage of prolabium
· Pressure tape on prolabium
· Intraoral fixation devices
· Lip adhesion (can be used to achieve symmetry in asymmetric bilateral cleft situations)
· Nasoalveolar molding
The most common appliances used are nasoalveolar molds and intraoral fixation devices. Botulinum toxin is currently being investigated to decrease tension in cleft repair.
In general, bilateral cleft lip repair techniques have been modified from unilateral cleft lip repair techniques. If the repair is staged, the more severe side is repaired first, and the second side is repaired approximately 3-6 months later.
Indications
Patients born with a cleft lip should undergo surgical repair unless otherwise contraindicated. The goal of reconstruction is to establish normal morphologic facial form and function in order to provide the optimal conditions for the development of dentition, mastication, hearing, speech, breathing, and psychosocial status.

Relevant Anatomy

Understanding normal lip and nasal anatomy is essential to recognize the distortion caused by a facial cleft. The elements of the normal lip are the central philtrum, which is demarcated laterally by the philtral columns and inferiorly by the cupid's bow and tubercle. Just above the junction of the vermilion-cutaneous border is a mucocutaneous ridge referred to as the white roll. Within the red vermilion of the lip are 2 distinct areas: the dry vermilion (the more keratinized portion of the lip that is exposed to air) and the wet vermilion (exposed to the moist environment of the labial mucosa).
The primary muscle of the lip is the orbicularis oris. It has 2 well-defined components: the deep (internal) layer and the superficial (external) layer. The deep fibers run circumferentially from commissure (modiolus) to commissure (modiolus) and function as the primary sphincter for oral feeding. The superficial fibers run obliquely, interdigitating with the other muscles of facial expression to terminate in the dermis, and function to provide subtle shades of expression and precise movements of the lip for speech.
The superficial fibers of the orbicularis decussate in the midline and insert into the skin lateral to the opposite philtral groove, forming the philtral columns. The resulting philtral dimple is centrally depressed, as no muscle fibers directly insert into the dermis in the midline. The tubercle of the lip is shaped by the pars marginalis, the portion of the orbicularis along the vermilion forming the tubercle of the lip with eversion of the muscle.
In the upper lip, the levator labii superioris contributes to the form of the lip. Its fibers arise from the medial aspect of the infraorbital rim and sweep down to insert near the vermilion cutaneous junction. The most medial fibers of the levator labii superioris sweep down to insert near the corner of the ipsilateral philtral column and vermilion-cutaneous junction, helping to define the lower philtral column and the peak of the Cupid's bow.
The nasal muscles are equally important. The levator superioris alaeque arises along the frontal process of the maxilla and courses inferiorly to insert on the mucosal surface of the lip and ala. The transverse nasalis arises along the nasal dorsum and sweeps around the ala to insert along the nasal sill from lateral to medial into the incisal crest and anterior nasal spine. These fibers join with the oblique fibers of the orbicularis and the depressor septi (nasalis), which arises from the alveolus between the central and lateral incisors to insert into the skin of the columellar to the nasal tip and the footplates of the medial crura.
A bilateral cleft thus disrupts the normal termination of the muscle fibers that cross the embryologic fault line of the maxillary and nasal processes, resulting in symmetric but abnormal muscular forces between the normal equilibrium that exists with the nasolabial and oral groups of muscles. With an unrestrained premaxilla, the deformity accentuates with differential growth of the various elements. The alar cartilages are splayed apart and rotate caudally, subluxed from the normal position. Consequently, the nasal tip broadens, the columellar is foreshortened, and the alar bases rotate laterally and cephalad.

Workup

Laboratory Studies
· Perform a thorough physical examination, not limited to the head and neck region, to uncover associated anomalies in the infant presenting with a unilateral cleft lip with or without a palatal cleft. Additional workup is determined by physical findings that suggest involvement of other organ systems.
· The child's weight, oral intake, and growth and/or development are of primary concern and must be followed closely.
· Routine laboratory studies typically are not required, other than a hemoglobin study shortly before the planned lip repair.
· Routine imaging is not indicated in a healthy patient with isolated cleft lip.

Treatment

Surgical Therapy

Children born with a facial cleft benefit from a multidisciplinary approach in a team-based setting so that all aspects of their care can be coordinated efficiently.
Beyond lip repair are hearing, speech, dental, and psychosocial integration issues. These should be addressed throughout the child's growth and development from birth through adolescence. These issues are as important as the anatomic reconstruction. Ultimately, the functional outcome of the reconstruction depends on cooperation between the surgeon, orthodontist, and speech pathologist.
Each specialty involved must evaluate the child individually, formulate a treatment plan, and integrate it with those of the other specialties based on the child's needs. The Parameters of Care Guidelines established by the American Cleft Palate Craniofacial Association should be followed.8 However, rather than strictly adhering to one protocol, physicians should assess each child individually and formulate the treatment plan based on the team's experience, its overall philosophy of treatment, and available resources.

Preoperative Details

While the lip repair is the initial focus for many parents, treatment begins by assessing the child's nutritional status and assisting the parents with oral feeding techniques so that appropriate weight gain occurs. Parents who suddenly are faced with caring for a child with a facial cleft can be overwhelmed. The importance of spending sufficient time with them to allay their fears, to discuss staging and timing of reconstruction, to stress the need for involvement of other specialists, and to stress the importance of long-term and consistent follow-up care from birth through adolescence cannot be overemphasized.

No agreement is found in the literature regarding the ideal timing of lip repair. Some have advocated surgery in the early neonatal period, with a theoretical benefit in scar appearance and nasal cartilage adaptability, thus minimizing the nasal deformity. To minimize anesthetic risks, some still adhere to the rule of 10s: perform surgical repair of cleft lip when the child has a hemoglobin level of 10 g, weight of 10 lb, and is aged 10 weeks. In general, most centers prefer to perform the lip reconstruction when the patient is aged 2-4 months; anesthesia risks are lower, the child is better able to withstand the stress of surgery, and lip elements are larger and allow for a meticulous reconstruction.
A presurgical, fabricated, passive, intraoral orthodontic palatal appliance can be used to maintain the arch width to prevent the nearly inevitable collapse that occurs with lip repair. Rarely is there an indication for active expansion of the maxillary segment. This passive plating and gentle traction is an integral component of surgical cleft lip repair. The repair reestablishes the soft tissue and muscular forces on the easily moldable maxillary arch segments. Recently, the palatal appliance has been modified to include a nasal extension to help improve the nasal tip form. The orthodontist takes impressions, and the custom appliance is fitted as soon as possible after birth and well before the lip repair.
The appliance also aids in the child's oral feeding, helping to decrease nasal regurgitation and assisting oral suction. Some centers have chosen either no presurgical orthopedic intervention or an active pin-based appliance (eg, Latham) to align the maxillary arch segments. For bilateral clefts, external pressure is routinely used to help maintain the premaxillary component within the arch alignment. Soft elastic tape (eg, 3M Microfoam tape) across the premaxilla, a head cap with elastic traction, or lip adhesion can be used prior to a definitive lip repair once the arch segments have approximated.

Intraoperative Details

The ideal lip repair results in symmetrically shaped nostrils, nasal sill, and alar bases; adequate columellar length; a well-defined philtral dimple and columns; a natural-appearing cupid's bow with a pout to the vermilion tubercle; and an adequate labial sulcus. In addition, lip scars are used to approximate the natural landmarks. The ideal repair results in functional muscle repair that with animation that mimics a normal lip.

Intraoperative technique.
(A) The anatomic landmarks are tattooed and the planned incisions are marked.
(B) The orbicularis is dissected from the overlying skin and divided into bundles to allow interdigitation with its opposing element. Inferiorly, an element of the muscle is left attached with the triangular vermilion flap used to create a Cupid's bow.
(C) The prolabial flap is developed. The lateral lip elements are discarded and the mucosal flaps are turned over to create a labial sulcus.
(D) The lower lateral cartilages are freed from the overlying nasal skin from the base of the ala and columella. The nasal domes are approximated to each other and the cartilages are suspended from the upper lateral cartilages.
(E) The series of interdigitating bundles of the orbicularis muscle are approximated to each other.
(F) The skin is inset with a series of fine nylon sutures, which are removed 5-7 days postoperatively if a skin adhesive is not used. Xeroform gauze bolsters are placed as a temporary nasal stent.


A number of surgical procedures with many variations for the repair of bilateral cleft lip are well described. Among these are the repairs of Veau, Tennison, Manchester, Millard, and others. The Veau III operation is a straight-line closure without elevation of the prolabial skin and correspondingly without any attempt at restoring the continuity of the orbicularis oris. The central cupid's bow and tubercle is constructed from the vermilion of the lateral lip elements. In contrast, Millard's repair involved complete elevation of the prolabium and reconstitution of the orbicularis across the premaxilla. In addition, Millard banked lateral segments of the prolabium as "forked flaps" that were meant to add columellar height at a later stage. As with Veau, the central vermilion is recreated from the lateral lip elements.
Unlike Veau and Millard, Manchester preferred to maintain the prolabial vermilion to create the cupid's bow and tubercle, but similarly to Veau, Manchester's repair did not involve repairing the orbicularis, as he felt this would create an overly tight lip. In recent years, significant contributions by McComb, Mulliken, Nakajima, and Cutting have integrated the correction of the associated nasal deformity with simultaneous lip repair that appears to achieve adequate primary columellar lengthening and nasal tip projection.9,10,11,12,13,14 More recently, McComb's experience led him to stage the repair.9 The initial stage involves approximating and repositioning the splayed alar cartilages through a V-Y nasal tip "gull-wing" incision that allows redraping the overlying skin with a simultaneous bilateral lip adhesion. A definitive lip repair follows at a second stage.
Mulliken's extensive experience has evolved from a median nasal tip incision for exposure to bilateral rim incisions that allow adequate access to correct the nasal cartilage deformity.15 Nakajima and Cutting have introduced presurgical molding of the nasal tip and columellar with acrylic outriggers attached to a palatal appliance.

· Use general anesthesia with a noncuffed Oral RAE endotracheal tube positioned midline. Typically, the otolaryngologist then examines the ears; if needed, myringotomy and pressure equalizing tubes are placed.
· Prior to infiltration with a local anesthetic (0.5% lidocaine with 1:200,000 epinephrine), tattoo the anatomic landmarks with a methylene blue dye and mark the proposed incisions.
· Two key elements are involved in the preoperative skin marking for the elevation of two crucial flaps (the prolabial flap and lateral lip advancement flaps). Make the prolabial flap in a trapezoid shape, with the peak of the Cupid's bow between 2-2.5 mm on either side of the midline. The flap narrows superiorly to the columella base. On the lateral lip element, the peak of the Cupid's bow is determined where the dry vermilion is maximal in width before it tapers off superiorly. Mark the incision of the lateral lip along the vermilion mucosa cutaneous junction to the ala base. The incision continues vertically intranasally along the mucocutaneous junction. Design the vermilion of the lateral lip flaps to fit into the inferior edge of the prolabial flap and to each other in the midline, forming a tubercle. The white roll should be included with the vermilion flaps.
· Elevate the prolabial flap to the base of the columella. The lateral cutaneous elements are primarily discarded, except at the columella base, where it is tailored to reconstruct the nasal sill (not as banked fork flaps). The mucosa is then turned down to create the labial sulcus.
· Elevate the lateral lip flaps by incising the marking just above the white roll through the full thickness of the lip. Identify the orbicularis oris muscle and separate it from the overlying skin and underlying labial mucosa. The muscle is divided inferiorly to allow it to accompany the vermilion flap. Make an upper buccal incision above the attached gingival to allow medial mobilization of the labial mucosa.
· Free the alar bases from their attachments to the piriform region to allow medial and inferior mobilization of the ala and the corresponding transversus nasi muscles (to prevent alar flare).
· The lower lateral alar cartilages are freed from the overlying nasal skin through an infracartilaginous incision laterally and medially. The domes are approximated to each other with intradomal sutures, and the complex is suspended from the upper lateral cartilages with temporary fixation sutures.
· Reconstructing the lip begins with creating the labial sulcus by approximating the labial mucosa of the lateral lip elements to the turned over prolabial mucosa. To approximate the orbicularis oris muscle, it is divided into bundles and interdigitated with its opposing element with a series of sutures. The alar bases are then set into place (inferior and medial) to the nasal spine. Approximate the prolabial skin flap and lateral lip flaps either with dermal sutures or in combination with an adhesive. The vermilion flaps are tailored to create a central tubercle. Tailor the flaps at the nasal sill and then close the alar and intranasal incisions.
· Place the Xeroform bolsters and nasal stents. Apply a topical antibiotic ointment to the lip.
Postoperative Details
· Oral feedings: For a child who is breastfed, the authors encourage uninterrupted breastfeeding after surgery. Bottle-fed children can resume feedings immediately following surgery with a crosscut nipple. Some centers still advocate having the child use a soft catheter tip syringe for 10 days following surgery, followed by resumption of normal nipple bottle feeding. The authors have found this degree of caution to be unnecessary.
· Activities: The authors instruct the parents to avoid giving the child pacifiers or toys with pointed edges for 2 weeks after surgery. No other restrictions on activity are necessary. Some centers advocate the use of Velcro elbow immobilizers on the patient for 10 days following surgery to minimize the risk of inadvertent injury to the lip repair. These are periodically removed during the day under supervision.
· Lip care: Any exposed suture line, at the base of the nose and lip, should be cleaned using cotton swabs with diluted hydrogen peroxide several times a day, followed by the liberal application of topical antibiotic ointment. The authors then remove any permanent sutures 5-7 days after surgery. If cyanoacrylate adhesive is used, no additional care is required in the immediate postoperative period until the adhesive film comes off. The parents are told to expect noticeable scar contracture, erythema, and firmness for about 4-6 weeks postsurgery and that this gradually begins to improve 3-12 months after the procedure. The authors typically instruct parents to massage the upper lip during this phase and to avoid placing the child in direct sunlight until the scar matures.

Follow-up

Following cleft lip repair, patients are evaluated periodically by the various cleft team members. Oral hygiene and proper dental care need to be emphasized. Psychosocial evaluation and treatment should be made available. Follow-up appointments with speech pathologists should be continued until normal or near normal speech is achieved. Close cooperation among the members of the cleft team is necessary for optimal outcomes.

Complications

Aside from an unsatisfactory appearance of the surgical result, possible complications include dehiscence of the repair, hypertrophic scar formation, or contracture of the lip scars. If dehiscence occurs, re-operation is postponed until the induration has subsided completely. In the intervening period, control of the premaxilla with orthodontic devices to prevent rotation caused by asymmetric forces may be needed. With lip scars that remain red, thick, and contracted, the authors use an occlusive tape dressing and, occasionally, Kenalog-10 (triamcinolone acetonide) injection and/or flurandrenolide tape. For most repairs, the observed contracture is part of normal healing and improves with time. Wait to perform intervention until the lip scar matures (generally 1 y), and the intervention should be guided by the severity of the residual deformity with the goal of minimizing the number of revisions.
A number of secondary deformities of a less than ideal outcome are well characterized. These primarily include the whistle deformity of the lip, a vertically deficient upper lip, a constricted lip, and muscular diastasis. Correction of these residual deformities must be specifically tailored and range from minor revisions to fully re-creating the defect and reconstructing each of the elements of the lip to discarding the prolabial element and replacing it with a lower lip Abbe reconstruction.



Outcome and Prognosis

While maintaining symmetry typically is not the main issue in reconstructing the bilateral cleft lip, the outcome can be less satisfying than with unilateral clefts. Careful preoperative assessment of the cleft lip deformity and attention to appropriate presurgical management and detail in the reconstruction typically results in an acceptable repair that achieves some of the characteristics of the natural lip and nose. Many variables are involved beyond the technical aspects of a particular repair. Ultimately, the outcome depends on the natural course of uncomplicated healing of the initial repair, alignment of the skeletal framework on which the lip rests, and the differential effect of normal growth and development on the operated lip.
While a poor initial result is unlikely to improve with time, an excellent initial result may require some revision because of uncontrolled variables. Moreover, while the lip repair may be acceptable, additional procedures to achieve nasal symmetry are commonly required, despite the initial primary nasal surgery incorporated as an integral part of lip repair. Realistically, one must realize that, despite physicians' best attempts, the stigmata of a bilateral cleft deformity remains in many children.

Future and Controversies

Bilateral cleft lip surgery has evolved from discarding the premaxillary and prolabial elements in a simple approximation of the cleft margins to, currently, a definitive single-stage lip and primary cleft nasal repair that incorporates the underlying musculature. Accompanying the evolution of the surgical repair is the increasingly important involvement of early presurgical alveolar and nasal molding to possibly improve surgical outcome.
The basics of cleft surgery are to achieve a good philtrum size, shape, and positioning of the cartilages, and muscular continuity. Although the basics are the same, the development of presurgical techniques continue to evolve and provide an exciting scaffold to the management of bilateral cleft lip.