Cleft Lip & Cleft Palate
Cleft lip, cleft palate, and combinations of the two are the most common congenital anomalies of the head and neck. The incidence of facial clefts has been reported to be 1 in every 650–750 live births, making this deformity second only to clubfoot in frequency as a reported birth defect.
The cleft may involve the floor of the nostril and lip on one or both sides and may extend through the alveolus, the hard palate, and the entire soft palate. A useful classification based on embryologic and anatomic aspects divides the structures into the primary and the secondary palate. The dividing point between the primary palate anteriorly and the secondary palate posteriorly is the incisive foramen. Clefts can thus be classified as partial or complete clefts of the primary or secondary palate (or both) in various combinations. The most common clefts are left unilateral complete clefts of the primary and secondary palate and partial midline clefts of the secondary palate, involving the soft palate and part of the hard palate.
Most infants with cleft palate present some feeding difficulties, and breast-feeding may be impossible. As a rule, enlarging the openings in an artificial nipple or using a syringe with a soft rubber feeding tube will solve difficulties in sucking. Feeding in the upright position helps prevent oronasal reflux or aspiration. Severe feeding and breathing problems and recurrent aspiration are seen in Pierre Robin sequence, in which the palatal cleft is associated with a receding lower jaw and posterior and cephalic displacement of the tongue, obstructing the naso-oropharyngeal airway. This is a medical emergency and is a cause of sudden infant death syndrome (SIDS). Nonsurgical treatment includes pulling the tongue forward with an instrument and laying the baby prone with a towel under the chest to let the mandible and tongue drop forward. Insertion of a small (No. 8) nasogastric tube into the pharynx may temporarily prevent respiratory distress and may be used to supplement the baby’s feedings. Placement of an acrylic obturator or appliance has proved quite successful in alleviating the breathing difficulties by bringing the tongue down and permitting a better nasal airway. Several surgical procedures that bring the tongue and mandible forward have been described but should be employed only when conservative measures have been tried without success. Recently, the use of distraction of the mandible has shown some beneficial effects. However, it should be done with great caution in the neonate.
Surgical repair of cleft lip is not considered an emergency. The optimal time for operation can be described as the widely accepted “rule of 10.” This includes body weight of 10 lb (4.5 kg) or more and a hemoglobin of 10 g/dL or more. This is usually at some time after the 10th week of life. In most cases, closure of the lip will mold distortions of the cleft alveolus into a satisfactory contour. In occasional cases in which there is marked distortion of the alveolus, such as in severe bilateral clefts with marked protrusion of the premaxilla, preliminary maxillary orthodontic treatment may be indicated. This may involve the use of carefully crafted appliances or simple constant pressure by use of an elastic band.
General endotracheal anesthesia via an orally placed endotracheal tube is the anesthetic technique of choice. A variety of techniques for repair of unilateral clefts have evolved over many years. Earlier procedures ignored anatomic landmarks and resulted in a characteristic “repaired harelip” look. The Millard rotation advancement operation that is now commonly used for repair employs an incision in the medial side of the cleft to allow the Cupid’s bow of the lip to be rotated down to a normal position. The resulting gap in the medial side of the cleft is filled by advancing a flap from the lateral side. This principle can be varied in placement of the incisions and results in most cases in a symmetric lip with normally placed landmarks. Bilateral clefts, because of greater deficiency of tissue, present more challenging technical problems. Maximum preservation of available tissue is the underlying principle, and most surgeons prefer approximation of the central and lateral lip elements in a straight line closure, rolling up the vermilion border of the lip (Manchester repair).
Secondary revisions are frequently necessary in the older child with a repaired cleft lip. A constant associated deformity in patients with cleft lip is distortion of the soft tissue and cartilage structures of the ala and dome of the nose. These patients often present with deficiency of growth of the structures of the mid face. This has been attributed to intrinsic growth disturbances and to external pressures from the lip and palate repairs. Some correction of these deformities, especially of the nose, can be done at the initial lip operation. More definitive correction is done after the cartilage and bone growth is more complete. These may include scar revisions and rearrangement of the cartilage structure of the nose. Recent approaches involve degloving of the nasal skin envelope with complete exposure of the abnormal cartilage framework. These are then rearranged in proper position with or without additional grafts. Maxillary osteotomies (Le Fort I with advancement) will substantially correct the midfacial depression. A tight upper lip due to severe tissue deficiency can be corrected by a two-stage transfer of a lower lip flap known as an Abbe flap.
In utero repair of cleft lip deformities has recently become a topic of discussion. In utero repair affords the potential to provide a scarless repair and correct the primary deformity. Furthermore, scarless fetal lip and palate repairs may prevent the ripple effect of postnatal scarring with its resultant secondary dentoalveolar and midface growth deformities. While these suggestions make in utero repair attractive, the risk of fetal loss remains high. Preterm labor is a major complication and one that is directly related to the large hysterotomy required for fetal exposure. Due to the great risks associated with it, intrauterine fetal surgery is still largely reserved for severe malformations that cannot be helped significantly by postnatal intervention.
Palatal clefts may involve the alveolus, the bony hard palate, or the soft palate, singly or in any combination. Clefts of the hard palate and alveolus may be either unilateral or bilateral, whereas the soft palate cleft is always midline, extending back through the uvula. The width of the cleft varies greatly, making the amount of tissue available for repair also variable. The bony palate, with its mucoperiosteal lining, forms the roof of the anterior mouth and the floor of the nose. The posteriorly attached soft palate is composed of five paired muscles of speech and swallowing.
Surgical closure of the cleft to allow for normal speech is the treatment of choice. The timetable for closure depends on the size of the cleft and any other associated problems. However, the defect should be closed before the child undertakes serious speech, usually before age 2. Closure at 6 months usually is performed without difficulty and also aids in the child’s feeding. If the soft palate seems to be long enough, simple approximation of the freshened edges of the cleft after freeing of the tissues through lateral relaxing incisions may suffice. If the soft palate is too short, a pushback type of operation is required. In this procedure, the short soft palate is retrodisplaced closer to the posterior pharyngeal wall utilizing the mucoperiosteal flaps based on the posterior palatine artery.
Satisfactory speech following surgical repair of cleft palate is achieved in 70–90% of cases. Significant speech defects usually require secondary operations when the child is older. The most widely used technique is the pharyngeal flap operation, in which the palatopharyngeal space is reduced by attaching a flap of posterior pharyngeal muscle and mucosa to the soft palate. This permits voluntary closure of the velopharyngeal complex and thus avoids hypernasal speech. Various other kinds of pharyngoplasties have been useful in selected cases.
No hay comentarios:
Publicar un comentario