Submucous Cleft Palate

48

Submucous Cleft Palate

Arun K. Gosain, Steven T. Lanier

KEY POINTS

The classic diagnostic triad of overt submucous cleft palate includes a bifid uvula, notched hard palate, and zona pellucida.

The prevalence of submucous cleft palate ranges from 0.02% to 0.08% in the general population, although it is significantly higher in patients who have velopharyngeal inadequacy (VPI).

Occult submucous cleft palate is diagnosed by multiview videofluoroscopy and nasal endoscopy during workup for VPI.

A specific familial cause of submucous cleft has not been identified, although it is commonly associated with other comorbid craniofacial differences, either sporadic or as part of a syndrome such as velocardiofacial (22q11 microdeletion), Klippel-Feil, or Treacher Collins syndromes.

The bony defect in submucous cleft palate is characterized by a deficiency of the horizontal plate of the palatine bone and underdevelopment of the vomer. The muscular deformity consists of abnormal insertion of the levator veli palatini muscles onto the posterior edge of the hard palate rather than forming a midline aponeurotic sling, resulting in a short, ineffective soft palate.

Documented VPI that is refractory to speech therapy remains the most widely accepted indication for surgical intervention.

The Furlow double-opposing Z-plasty and pharyngeal flaps have a higher reported success rate than does palatoplasty alone for treatment of submucous cleft palate associated with VPI.

Ultimately, the technique selected for the correction of velopharyngeal inadequacy must take into account velopharyngeal gap size, palate length, lateral pharyngeal wall motion, and velopharyngeal closure pattern.

This chapter discusses the submucous cleft palate and its pathogenesis, epidemiology, clinical presentation, diagnosis and evaluation, and options for surgical management. The chapter concludes with a detailed discussion of my (A.K.G.) preferred repair, the Furlow palatoplasty, and presents previously unpublished outcomes data for patients with submucous cleft palate who underwent this repair.

BACKGROUND AND HISTORY

A thorough understanding of the pathology associated with submucous cleft palate depends on having a general concept of the embryology of the primary and secondary palate. In the first trimester of development, the primary palate is formed from the median palatine process, derived from the frontonasal prominence; the secondary palate is formed by the two lateral palatine processes, derived from the maxillary prominences.1 Initially, each lateral palatine process grows in a vertical orientation surrounding the tongue. However, in the eighth week the orientation changes from vertical to horizontal. This change occurs simultaneously with prognathic growth of the mandible. As a result of this mandibular growth, the tongue is displaced inferiorly, allowing for horizontal growth of the palatal processes without impedance by the tongue. As the palatal shelves continue to grow toward one another, the very medial edge of all three palatal shelves undergoes a process of programmed cell death, whereas the mucosa on the oral and nasal surfaces remains intact. Once the shelves meet, the process of fusion occurs between the lateral palatine processes and the median palatine process. As this occurs, a down growth from the medial nasal prominences, the nasal septum, fuses with the nasal surface of the now-formed palate. Clefting of the hard palate can result from any disturbance in the growth and elevation of the palatal shelves or in their fusion with the median palatine process anteriorly and the nasal septum superiorly.2

While palatal growth and fusion is occurring, mesenchymal centers form within each of the shelves. These mesenchymal centers will eventually give rise to the hard palate osseous structures of the anterior secondary palate, through differentiation into osteoblasts, as well as the soft palate musculature, through differentiation into myoblasts. A landmark study of human fetuses at different stages of development by Cohen et al3 demonstrated a definite timeline for soft palate mesenchymal maturation and subsequent myogenesis. This study demonstrated that myogenesis primarily occurs during weeks 6 to 9 of development, with final soft palate architecture in place by weeks 16 to 17. Furthermore, the osseous structures of the palate seem to follow a timeline that also closely parallels myogenesis.

Cohen et al also characterize the abnormal myogenesis associated with a cleft of the hard palate. Compared with histologic specimens of human fetuses without cleft palate, those with cleft palate showed delayed development of the soft palate musculature at 10 to 12 weeks and disorganized and sparser muscle fibers near the medial epithelial edge of the cleft in older specimens. Whether aberrant myogenesis results from an intrinsic problem with the precursor mesenchymal centers, is secondary to the formation of the bony cleft, or is caused by a combination of these factors is unclear.3

Submucous cleft palate was first described by Roux4 in 1825 during a consultation on a young girl with unintelligible speech. During the examination, Roux identified a division within the soft palate, along with nonunion of the hard palate osseous structures, under an intact mucosa.5,6 Nearly a century later, in 1910, Kelly7 further described the condition and offered the modern day name of submucous cleft palate. However, it was not until 1954 that a diagnostic triad was described to identify and diagnose the condition. At that time, Calnan8 published the three currently recognized stigmata of the overt submucous cleft palate:

  1. A bifid uvula
  2. Midline palatal muscle diastasis with an intact mucosa (termed zona pellucida)
  3. A notching defect in the posterior hard palate (Fig. 48-1, A)
image

Fig. 48-1 A, Classic overt submucous cleft palate with a bifid uvula and a zona pellucida resulting from diastasis of the levator muscles, with the palate joined in the midline only by a thin overlying mucosa. B, A patient with an occult submucous cleft palate. The possible start of a bifid uvula is visible; however, at rest, the submucous cleft palate is not clearly evident. C, Here the same patient is phonating, revealing retraction of the velum in a vaulted V-shaped pattern. Deepening of the zona pellucida is the result of contraction of the levator muscles, which are abnormally located in the paramedian position and insert on the posterior margin of the hard palate.

Although this diagnostic triad still forms the basis for diagnosis of submucous cleft palate, more recently, submucous cleft palate has been shown to exist as a spectrum of disease ranging from overt submucous cleft to occult submucous clefts.911 In an occult submucous cleft (Fig. 48-1, B and C), the classic findings may not be evident at rest. However, during phonation or active gag, the soft palate elevates in a vaulted V-shaped pattern, exposing the zona pellucida and the abnormally located levator muscles, which are in the paramedian position and insert on the posterior margin of the hard palate. Mori et al12 recently used three-dimensional computed tomography to characterize the bony defect in a population of Japanese patients with submucous cleft palate, identifying three morphologic variants from most to least common: Type I, characterized by an absent posterior nasal spine with minimal depression of the posterior hard palate; Type II, characterized by the classic V-shaped notch in the hard palate; and Type III, characterized by a complete bony defect extending to the incisive foramen. Furthermore, these bony defects can be paired with various degrees of soft palate muscular malformation, ranging from near-complete muscular sling formation to the insertion of the clefted levator onto the posterior palatine shelves.13 Therefore submucous cleft palate may or may not demonstrate the classic physical triad described by Calnan.

Two large epidemiologic studies have examined the prevalence of overt submucous cleft palate. In the larger of these two studies, Weatherley-White et al14 examined 10,836 children and found only 9 (0.08%) to have all three stigmata of overt submucous cleft palate. Furthermore, of these nine children, only one had clinical symptoms of velopharyngeal inadequacy. This relatively high percentage of patients with submucous cleft palate who remain asymptomatic has been confirmed by numerous other studies.7,8,11,1520 The second large study looked for physical examination findings in 6000 school-age children. However, in this study, Garcia-Velasco et al21 required only two physical examination findings, including the three stigmata, to give the diagnosis of submucous cleft palate. The group found only one child (0.02%) who met their criteria for submucous cleft palate.

The prevalence of occult submucous cleft palate is more difficult to estimate, because within a general population, occult submucous cleft palate is only investigated in patients referred for evaluation of velopharyngeal inadequacy. Furthermore, ethical considerations do not allow for nasendoscopic studies or intraoperative exploration as a means of screening for submucous cleft palate. However, in using nasendoscopy to evaluate 25 patients with bifid uvula, Shprintzen et al20 found 92% of patients to have landmarks associated with submucous cleft palate. This study suggests that the incidence of occult submucous cleft palate may be considerably higher than what has previously been thought, considering that bifid uvula has been reported in roughly 1% to 7.5% of the population.14,1823 Nonetheless, the true incidence of occult submucous cleft palate remains unknown.

As shown in these and other studies, the incidence of overt submucous cleft palate (0.02% to 0.08%) is exceedingly rare in the general population; however, when examining populations with velopharyngeal inadequacy, the incidence is markedly increased. In examining 240 patients with velopharyngeal inadequacy, Kaplan11 found 27% to have diagnoses of submucous cleft palate: 17% of the overt type and 10% of the occult type. In a similar study of 131 patients with velopharyngeal inadequacy, Lewin et al10 found 66% of patients demonstrating submucous cleft palates: 44% of the overt type and 22% of the occult type. Therefore clinicians examining patients with known velopharyngeal inadequacy must have a high clinical suspicion for submucous cleft palate.

Although Calnan observed a small proportion of patients with submucous cleft palate to have a family history of clefts, none of the larger studies have reported a specific familial cause of submucous cleft palate.8 However, despite the lack of definite familial cause, submucous cleft palate is commonly associated with other comorbid conditions. In their evaluation of 26 patients with submucous cleft palate who had evidence of velopharyngeal inadequacy, Kaplan11 found only 30% to have isolated defects of the palate. Similarly, Weatherley-White et al14 found only 35% of 62 patients with submucous cleft palate to have the isolated palatal anomaly. Common comorbid conditions include mandibular prognathism or hypognathism, syndactyly, talipes, cleft lip, microtia, neurosensory hearing loss, and mental retardation.24,25 Furthermore, submucous cleft palate is associated with several syndromes, including velocardiofacial (22q11 microdeletion), Klippel-Feil, and Treacher Collins syndromes.14,26 In a large series of Chilean patients with velocardiofacial syndrome, Lay-Son et al27 found that approximately three fourths displayed a palatal abnormality, half of which consisted of submucous cleft palate. Importantly, for patients with velocardiofacial syndrome without congenital heart defects, velopharyngeal inadequacy is often the presenting symptom.27

Multiple theories regarding the pathogenesis of submucous cleft palate have developed since its discovery in the 1800s. When discussing the pathogenesis of submucous cleft palate, a distinction should be made between the bony and muscular abnormalities, though certain authors have proposed a common cause. A failure of mesenchymal proliferation, first described by Veau,28 has traditionally been the most widely accepted theory. Histologic examination of the palatal mucosa in the initial 18 cases described by Calnan showed a lack of muscle union across the cleft and poorly developed muscle fibers in a matrix of fibrous tissue with an underdeveloped vomer attached anteriorly to the bony cleft. As a result of the lack of midline mesenchymal derivatives, Calnan also believed that the failure of palate formation lay somewhere in mesenchymal proliferation. Supporting this theory, Poswillo29 noted a failure of the maxillary ossification centers to extend to the midline in an induced submucous cleft palate rodent population.

More recently, Stal and Hicks13 published a histologic study showing similar pathology to that found by Calnan,8 with biopsies of submucous cleft palates showing myocyte atrophy and fascicular disorganization as well as dense fibrosis. However, in contrast to Veau and Calnan, Stal et al theorize that these changes may result from failure of epithelial and mesenchymal resorption required for midline fusion of subepithelial mesenchymal centers.13 This latter theory is supported by more recent work by Xu et al,30 who have created a transforming growth factor β receptor (Tgfbr2) null mouse model that displays a submucous cleft palate phenotype with failure of palatine bone fusion in the midline and a complete soft palate cleft with insertion of the palatal muscles onto the posterior portion of the palatal bone. They demonstrate that this is a result of a failure of medial edge epithelium disintegration caused by impaired apoptosis and matrix metalloproteinase activity. Furthermore, they found no defect in palatal mesenchymal proliferation in the Tgfbr2 mutant mice. In contrast, Tgfbr3 null mice do exhibit deficient mesenchymal proliferation, resulting in a complete cleft palate phenotype, suggesting the possibility of a separate cause of complete versus submucous cleft palate.

Whether as a result of failure of mesenchymal proliferation or of epithelial resorption, the levator muscles of the soft palate fail to reach the midline for proper insertion. In 1930 Dorrance31 noted an abnormal insertion of the levator muscles in patients with submucous cleft palate. Normally, the levator muscles insert in the palatine aponeurosis at the midline, allowing for elevation of the soft palate during contraction. However, in submucous cleft palate, the levator muscles insert too far anteriorly onto the posterior hard palate (Fig. 48-2). The result is a soft palate that is ineffectively raised and actually shortened during levator contraction. This tethering effect of the abnormal insertion is believed to be one of the most important factors in the symptoms associated with submucous cleft palate. These findings were confirmed by Hoopes and colleagues3234 who, using fluoroscopic studies, demonstrated a short palatal length, diminished velar excursion, and a slowed rate of velar ascent in a population of patients with submucous cleft palate. The group concluded that the further anterior the insertion, the greater the degree of velopharyngeal inadequacy.

In contrast to overt cleft palate, in which bony clefting results from a failure of lateral palatal growth and fusion, the bony defect in submucous cleft palate is characterized by a deficiency of the horizontal plate of the palatine bone, which forms the posterior portion of the hard palate.2 In addition, the vomer is underdeveloped. Recent work by Pauws et al35 suggests that failed mineralization of condensed palatal mesenchyme rather than a failure of mesenchymal proliferation may be responsible for failure of vomer and palatal bone formation. Their group has identified the transcriptional repressor TBX22 as integral to intramembranous ossification of the posterior hard palate and has created a TBX22 knockout mouse with a submucous cleft palate phenotype, including bony underdevelopment of the vomer, palatine bone deficiency, and palatal notching in combination with a properly formed anterior hard palate. These defects were shown to result from failure of osteoblast maturation. Interestingly, in this model, muscular insertion into the palatal aponeurosis remained intact. Thus these mice demonstrate an occult submucous cleft palate in which palatal function remains intact.

image

Fig. 48-2 A, The normal velopharyngeal mechanism in which the levator muscles form a sling within the velum. The palatopharyngeus and superior pharyngeal constrictor muscles contribute to the velopharyngeal mechanism, creating a circumferential valve that is open at rest to allow nasal breathing but is capable of closure during phonation to prevent nasal air escape. B, The velopharyngeal mechanism in a patient with submucous cleft palate and velopharyngeal inadequacy. The levator muscles are abnormally located in a paramedian position and insert on the posterior surface of the hard palate. The posterior nasal spine is absent in the midline of the hard palate. The velopharyngeal mechanism is incapable of achieving complete closure, resulting in nasal air escape during phonation.

Isolated cleft of the secondary palate, submucous cleft palate, and occult submucous cleft palate are traditionally believed to represent a spectrum of defects with the same embryologic basis.11 However, as the previously cited studies indicate, a wide array of genes are involved in normal palatogenesis, and the cause of cleft palate is likely heterogeneous and multifactorial. The model presented by Pauws et al suggests the possibility that rather than being two points along a developmental spectrum, occult and overt submucous cleft palate could potentially result from separate underlying genetic causes. Furthermore, the work of Xu et al suggests distinct etiologic factors for complete and submucous cleft palate. Ongoing research continues to give us a better understanding of the genetic basis of all forms of cleft palate. In the future, such an understanding could allow for screening and early gene therapy to prevent cleft formation.

RECONSTRUCTIVE PRINCIPLES

Repair of submucous cleft palate depends on some of the fundamental principles of plastic surgery. Reconstructive challenges can be divided into wounds, defects, or deformities.36 Wounds involve a disruption of parts, defects involve a loss of parts, and deformities involve a distortion of parts. Submucous cleft palate can be considered to be part defect and part deformity. The defect involves variable deficiency of the secondary hard palate, deficiency of the vomer, and deficiency of the palatine bone; however, improper insertion of the palatal musculature is best considered a deformity, in which the normal anatomic structures are present but do not form in the proper anatomic arrangement. This has important implications for restoration of palatal function.

Early surgical intervention for submucous cleft palate involved excision with primary closure of the submucous cleft palate. However, this fails to account for the palatal musculature that does not lie in the correct transverse orientation. Rather, the levator muscles insert abnormally anterior, and as a result, primary closure does not re-create the correct palatal anatomy. In a report of seven patients undergoing excision of submucous cleft palate with primary closure, Crikelair et al37 found only one patient to have excellent results 5 months postoperatively. These results reflect that primary closure of submucous cleft palate alone does not adequately address the deformity in the palatal musculature. More current approaches to the surgical correction of submucous cleft palate address the anatomic deformity of the levator complex and its functional consequences, leading to improved outcomes.

PATIENT SELECTION AND EVALUATION

Whereas children with overt submucous cleft palate can be diagnosed based on physical examination, those with occult variants will likely only present for evaluation if they experience symptomatic velopharyngeal inadequacy. In these patients, diagnosis cannot be made by physical examination alone and depends on either direct imaging studies or operative exploration.911 The velopharyngeal valve consists of a complex group of structures that function to separate the oral and nasal cavities for normal speech and deglutition. The soft palate, posterior pharyngeal wall, and lateral pharyngeal walls must all work together for proper closure of this valving mechanism. The muscles primarily responsible for proper velopharyngeal valve closure include the levator veli palatini and superior pharyngeal constrictor, with the palatopharyngeus, salpingopharyngeus, and tensor veli palatini muscles making additional contributions.38 Valve dysfunction as a result of compromised motion is referred to as velopharyngeal incompetence, whereas dysfunction caused by tissue deficit is referred to as insufficiency. Any combination of these two is more generically termed velopharyngeal inadequacy, which is commonly abbreviated as VPI.38 However, in the literature the “I” in the abbreviation VPI might apply to incompetence, insufficiency, or inadequacy; in addition, many authors are not aware of the different meanings of these terms, and often apply the term VPI to any of these conditions. The primary clinical manifestations associated with velopharyngeal inadequacy include nasal escape of air, nasal resonance during nonnasal speech, and oronasal reflux of swallowed liquid and solid food.

Depending on the presence of velopharyngeal inadequacy, patients with submucous cleft palate may present at any age or may remain asymptomatic throughout life.7,8,11,1621 Patients who present in infancy will often have difficulties of prolonged feeding times or nasal regurgitation after feeding. Most commonly, patients will present after the development of speech abnormalities.39 Primary speech abnormalities arise from nasal escape during articulation, producing hypernasal resonance and a decreased ability to increase intraoral pressure, resulting in weak pressure consonants.40 Secondary speech abnormalities arise from articulatory errors that develop to compensate for this abnormal nasal escape during speech.39 When patients present with any of the aforementioned complaints, the diagnosis of submucous cleft palate must be considered.

Recurrent otitis media has also been described as a presenting symptom. Although the association of cleft palate and otitis media is well established, that of submucous cleft palate and otitis media is less convincing. In children with overt cleft palate, otitis is believed to arise from Eustachian tube dysfunction, along with a possible impaired tubal dilatory system.41,42 Children with submucous cleft palate, on the other hand, are believed to have an isolated defect within the levator veli palatini, which is not required for Eustachian tube dilation.43 Furthermore, although early studies reported increased incidence of otitis media in patients with submucous cleft,16,18,21,44,45 more recent studies have shown an incidence closer to that of the general population.24,43,46,47

Evaluation of Velopharyngeal Inadequacy

When velopharyngeal inadequacy is suspected, a full workup is indicated, because timing of treatment is important in management and outcome. The single most important test performed is a formal evaluation by a trained speech pathologist.4850 This evaluation is necessary to establish the diagnosis of velopharyngeal inadequacy. Using judgments of sound articulation, oral-nasal resonance balance, presence of audible and visual nasal emission, use of equal-appearing interval and global ratings scales, and evaluation of overall speech intelligibility, speech pathologists are able to give subjective assessment of hypernasality.5161

Although direct oral examination alone is helpful in identifying features of the overt submucous cleft, it does not allow for assessment of palate length, palate height, pharyngeal wall motion, and velopharyngeal valving, all of which are important for diagnosing and characterizing the cause of velopharyngeal inadequacy.57 As a result, in addition to a speech pathology evaluation, other means of direct and indirect testing are necessary for adequate assessment. Indirect methods use both qualitative and quantitative measures of velopharyngeal inadequacy, whereas direct methods allow visualization of the valve mechanism.

Indirect methods of evaluation include the oral-nasal acoustic ratio (TONAR), air pressure-flow measures, sound pressure measures, nasal vibratory measurements, photodetection, and Velotrace measuring palatal motion transduction.6279 Electromyography is another indirect method of evaluation, although it has less clinical value.80,81 Indirect studies allow for objective documentation of velopharyngeal inadequacy and can confirm the speech pathologist’s perceptual findings.

image

Fig. 48-3 A, Lateral view videofluoroscopy of a patient with velopharyngeal inadequacy and submucous cleft palate. A gap between the velum and the posterior pharyngeal wall during phonation (arrows) results in nasal air escape. B, Anteroposterior videofluoroscopy of a patient with velopharyngeal inadequacy and submucous cleft palate. Arrows demonstrate lateral pharyngeal wall motion.

Although indirect methods allow for correlation of objective and perceptual findings, they are less beneficial in treatment planning of velopharyngeal inadequacy. Therefore, direct measures of visualization become essential for management. The most common direct techniques in use today include mutiview videofluoroscopy and nasal endoscopy. Direct visualization can identify the closure pattern and contributions of the velum, the lateral and posterior pharyngeal walls, and Passavant’s ridge.39

Multiview videofluoroscopy originated as a plain roentgenogram projected in a lateral view during isolated sound phonation.82,83 Fluoroscopy has since evolved to allow real time visualization of the velopharyngeal mechanism in multiple views (Fig. 48-3). By using frontal, lateral, basal, and Towne’s projections, the velopharyngeal mechanism can be seen in three dimensions. Videofluoroscopy allows assessment of palatal length, lateral pharyngeal wall motion, velopharyngeal gap size, and defect pattern.40 The basal view is particularly effective for visualization of the lateral pharyngeal walls.83 Towne’s view, on the other hand, is considered effective in individuals with large adenoids.84 Furthermore, sensitivity is significantly increased when Towne’s view is added versus lateral view alone.85 Common findings associated with submucous cleft palate include a shortened soft palate, diminished velar ascent, decreased velar excursion, and palate fatigability.3234

The second major direct study used to evaluate velopharyngeal inadequacy is nasendoscopy.86,87 Previously, a rigid nasendoscope was used to view the nasal surface of the velopharyngeal valve. More recently, the use of an end-viewing flexible fiberoptic endoscope has been advocated by numerous studies. During nasal endoscopy, the patient repeats key phrases that stimulate velopharyngeal closure as the scope views the velopharyngeal mechanism. It is important that the investigator views the lateral pharyngeal walls, the posterior pharyngeal wall, and the nasal surface of the velum.39 The velopharyngeal closure pattern can be identified through endoscopy, which then guides the treatment plan for correction. Furthermore, nasendoscopy has been shown to be important in the diagnosis of occult submucous cleft palate.9,10 In such patients, nasendoscopy reveals a flat or concave nasal surface, with the “seagull sign” demonstrated as a central groove in the nasal surface of the velum that is believed to represent hypoplasia of the musculus uvulae.9,10,88

More recently, a few case reports have described the use of MRI to evaluate levator muscle anatomy and help guide surgical decision-making. Unlike videofluoroscopy and nasendoscopy, MRI allows direct visualization of the underlying soft palate musculature and offers superior soft tissue imaging without ionizing radiation.89 The potential of MRI to evaluate patients with submucous cleft palate raises important considerations regarding the appropriate timing of intervention and will be discussed further in the following section.

MANAGEMENT ALGORITHM

One of the longstanding debates in submucous cleft palate literature deals with the ideal timing for surgical intervention. In the case of overt cleft palate, speech outcomes are greatly improved when the palate is repaired before speech development. Retrospective analyses have demonstrated improved speech outcomes when palatoplasty is performed before 1 year of age, around the time speech begins, with late repairs associated with a higher rate of velopharyngeal inadequacy and articulation errors.39,9092 For patients with overt cleft palate, early surgical intervention is imperative, because velopharyngeal competency cannot be achieved without treatment. On the other hand, only a small percentage of patients with submucous cleft palate develop symptoms of velopharyngeal inadequacy.7,8,11,1621 Therefore surgery performed before speech development (when symptoms appear) is likely to be unnecessary for most of these patients. More important, it would place these patients at unnecessary risk of surgical complications.

Because of the these considerations, documented velopharyngeal inadequacy that is refractory to speech therapy has been and remains the most widely accepted indication for surgical intervention in the treatment of submucous cleft palate. By this guideline, 2½ years is likely the earliest acceptable age for surgical intervention, because it is very difficult, if not impossible, to perform an adequate speech evaluation along with a sufficient trial of speech therapy before this age.40 However, children may not produce an adequate speech sample for evaluation of velopharyngeal inadequacy until up to 5 years of age, which delays surgical intervention until well after they have begun to develop compensatory articulation errors.93 Given data demonstrating a significant improvement in speech outcomes for patients with overt cleft palate repaired before speech development, intervention before speech development would likely lead to improved outcomes for the subgroup of patients with submucous cleft palate who will go on to develop velopharyngeal inadequacy. Therefore a reliable method to identify this subgroup of patients at an early age would enable earlier intervention and may improve outcomes.

Because an intact levator sling has been shown to be essential for velopharyngeal adequacy, early characterization of the severity of the muscular deformity present in a patient with submucous cleft palate may have a predictive value for his or her ultimate development of velopharyngeal inadequacy.94 As noted previously, the necessity of an intact levator sling for velopharyngeal adequacy serves as the justification for surgical correction of complete cleft palate long before formal evaluation of velopharyngeal function is possible. However, in patients with submucous cleft palate, speech development is variable even in the presence of obvious levator muscle dehiscence, and therefore the correlation between muscular anatomy and velopharyngeal competence is less well understood.

MRI may have significant promise in helping to characterize the muscular anatomy in patients with submucous cleft palate before and after surgical intervention. Ha et al95 used MRI to compare the anatomy of the levator veli palatini in patients with cleft palate after repair with that of noncleft controls. Though only a small series, their work validates the use of MRI to quantify static parameters such as muscle length, angle of origin and insertion, and thickness, as well as dynamic parameters such as contractility.

In 2001 Kuehn et al89 described the first use of MRI of the levator complex to diagnose occult submucous cleft palate and aid in the decision for surgical intervention in two 4-year-old patients with speech delay and hypernasality despite trials of speech therapy. In addition to formal speech evaluation, videofluoroscopy, nasendoscopy, and nasometry were attempted in one of the two patients but could not be completed because of patient noncompliance. Preoperative MRI of these two patients clearly demonstrated interruption of the levator complex in the midline with fibrous encasement of the muscle, a hypoplastic musculus uvulae, and attachment of a significant proportion of levator muscle fibers to the posterior hard palate. Based on these data the authors decided to proceed to surgery rather than continued speech therapy, and both patients showed improvement after a Furlow double-opposing Z-plasty. Although the argument could be made that failure of speech therapy alone provided a sufficient indication for surgical intervention in these two patients, the report does demonstrate the use of MRI to diagnose occult submucous cleft palate without operative exploration by demonstrating malformation and aberrant insertion of the levator complex. Furthermore, it allows a correlation of the extent of levator malformation with clinical evaluations of these patients who showed significant VPI and little improvement with speech therapy.

More recently, Perry et al93 reported a case of a 15-month-old with overt submucous cleft palate, mild nasal regurgitation, and a speech and language delay for whom MRI was used to assess the levator muscle complex, ultimately prompting early surgical intervention. Although the patient was too young for a formal speech evaluation, MRI showed a separation of the levator complex at the midline with aberrant insertion into the posterior hard palate. Based on the studies discussed previously, the authors concluded that the observed levator anatomy could not produce palatal movement that would allow normal speech, and thus intervened at 16 months of age with a Furlow double-opposing Z-plasty. After surgery, the patient began speech therapy and showed significant and rapid improvement in language skills. By 10 months after surgery the patient no longer experienced nasal regurgitation and did not demonstrate nasal emission, and objective metrics rated the patient’s expressive and receptive language skills as above average for age.

Randomized, controlled trials are needed to determine whether early intervention based on anatomic data from MRI leads to improved outcomes in the submucous cleft palate population, though these reports show the significant promise of MRI to guide early intervention. Advantages of MRI compared with videofluoroscopy include a lack of radiation exposure, nonreliance on patient compliance to produce a speech sample, visualization of the malformed muscular anatomy, and ability to make an earlier diagnosis.93 Because of these benefits, MRI will likely continue to play an increasingly important role in the treatment algorithm of patients with both occult and overt submucous cleft palate. As this modality becomes more prevalent, its use is only justifiable in children who are old enough to tolerate the test while awake. This is essential both to obtain images during voluntary phonation and to prevent the need for general anesthesia.

Once the diagnosis of velopharyngeal inadequacy has been established and speech therapy has failed, surgical correction of submucous cleft palate is indicated. Surgical procedures have been developed to target the specific deficiencies of the secondary palate. Historically, surgical correction has focused on increasing palatal length, improving soft palate motility, reorienting palatal musculature, and recruiting tissue to act as a physical barrier between the oropharynx and nasopharynx. By increasing palatal length or by releasing and reorienting the levator muscles, velar function can be improved. On the other hand, when recruiting tissue to act as a physical barrier, velopharyngeal closure relies on adequate lateral pharyngeal wall motion. Surgical corrections that have been designed include use of a pharyngeal flap, palatal push-back techniques, intravelar veloplasty, Furlow Z-plasty, and combined surgical techniques.

Pharyngeal Flap

First performed by Schoenborn96 in 1876, the pharyngeal flap has been used to correct velopharyngeal inadequacy for a long time. In this technique, a myomucosal flap from the posterior pharyngeal wall is raised and inset into the nasal surface of the soft palate. The pharyngeal flap provides a physical barrier between the oropharynx and nasopharynx. When this flap is raised, ports are created on either side of the raised tissue. Velopharyngeal competence is restored as the lateral pharyngeal walls close these ports during speech and deglutition. Therefore restoration of velopharyngeal competence relies on tailoring flap width to maintain patency of the nasal airway, while allowing for adequate lateral pharyngeal wall motion to achieve velopharyngeal closure.

Palatoplasty

Palatoplasty techniques include the von Langenbeck palatoplasty, the Veau-Wardill-Kiner V-Y pushback, and the Bardach two-flap palatoplasty.40 All of these techniques involve variations on the raising of paired mucoperiosteal flaps based on the greater palatine vessels. Von Langenbeck first introduced his bipedicled palatoplasty technique in 1861,97 and the palatal pushback was first described in 1925 by Dorrance98 as a modification of the von Langenbeck palatoplasty. In this procedure, bilateral mucoperiosteal flaps are elevated and advanced posteriorly, thereby increasing the overall length of the palate. Modifications to the procedure have since been made; however, the main principle of palatal lengthening remains. The most recent modification of the pushback technique reported by Hwang99 involves raising a posteriorly based, W-shaped flap of hard palate mucoperiosteum, dissection and midline apposition of the levator muscles without violating the nasal mucosa, and a V-Y pushback midline closure.

Intravelar Veloplasty

Restoration of the levator sling was first popularized in the 1960s after anatomic studies of cleft palate.100,101 The procedure of intravelar veloplasty involves releasing the levator muscle from its abnormal insertion on the posterior margin of the hard palate and opposing the levator muscles at the midline to restore the levator sling and thereby restore velar function.

Furlow Z-plasty

In 1978, Furlow102,103 presented a new technique for repairing palatal clefts using opposing mirror-image Z-plasties elevated from the oral and nasal mucosa. By transposing the posteriorly based myomucosal flaps, this Z-plasty reorients the palatal musculature in correct anatomic position, simultaneously increasing palatal length and decreasing pharyngeal width. This repair has become my (A.K.G.) preferred technique and is discussed in detail in the following section.

Combined Techniques

Combined techniques typically use two or more of the following: pharyngeal flap, palatal pushback, and intravelar veloplasty. The rationale for adding a pharyngeal flap to the palatal pushback is to provide mucosal lining for the defect created by the pushback.39 In this setting, the palatal pushback, rather than the pharyngeal flap, provides the dynamic component of velopharyngeal competence.

SURGICAL TECHNIQUE: DOUBLE-OPPOSING Z-PLASTY

The surgical procedure starts with marking of the oral mucosa (Fig. 48-4, A). Dissection must be done carefully to preserve the pedicle supplying the levator veli palatini muscle. By convention, a posteriorly based oral mucosal-muscular (oromuscular) flap is elevated on the left side of the palate and an anteriorly based oral mucosa–only flap is elevated on the right side of the palate. After the oral layer dissection is completed, the nasal layer incision is planned and flaps are dissected as mirror images of the oral mucosal flaps. A posteriorly based right-sided nasal mucosal-muscular (nasomuscular) flap and an anteriorly based left-sided nasal mucosa–only flap are dissected. The oromuscular flap (left) and nasomuscular flap (right) are elevated without violating the base of either muscle flap. The nasomuscular flap is then transposed to the left and posteriorly (Fig. 48-4, B), and the oromuscular flap is transposed to the right and posteriorly (Fig. 48-4, C) to reconstruct the levator sling. Anterior transposition of the nasal and oral mucosa–only flaps completes the double-opposing Z-plasty (Fig. 48-4, D).

May 11, 2019 | Posted by in Oral and Maxillofacial Surgery | Comments Off on Submucous Cleft Palate
Premium Wordpress Themes by UFO Themes