The Occult Submucous Cleft Palate

Abstract

Classic submucous cleft palate is identified by the triad of a bifid uvula, a furrow along the midline of the soft palate, and a notch in the posterior margin of the hard palate (Figure 1). These are the obvious overt physical signs of an underlying anatomic abnormality—the insertion of the levator and other palate muscles onto the hard palate instead of forming a sling across the midline. As a result of this muscle malposition, velar function may be abnormal and velopharyngeal incompetence may result. We now recognize that muscle malposition can occur in the absence of the triad of overt signs. This condition is designated " occult " submucous cleft palate. We believe that isolated cleft of the secondary palate, submucous cleft palate, and occult submucous cleft palate are variations in expression of the same embryologic disorder; that there is, in fact, a continuous spectrum of severity of muscle malformation and actual clefting. However, we would exclude cleft palate associated with craniostenosis (Apert7s syndrome), branchial arch syndromes (Treacher—Collins), mandibular micrognathia (Pierre-Robin), and cleft palate with cleft lip from these considerations because they are probably embryologically distinct conditions. (2). Cleft uvula reportedly occurs in 03-10% of the " normal " population without velopharyngeal incompetence and without other physical signs of submucous cleft. (73) Too, it has been shown that the classic submucous cleft palate also occurs in 1-10% of the population without speech dysfunction. (74) We believe that these are also microforms of secondary palate and submucous clefts which have compensated velopharyngeal function. The terms congenital short palate (3) and congenital insufficiency (7, 77) may also be variant presentations of occult submucous cleft palate. 75% of our patients had a short soft palate and, therefore, could be termed congenital short palate. However, all of these were subsequently shown to be submucous clefts. We have reviewed 240 cases of velopharyngeal incompetence without cleft lip or cleft palate (Figure 2) and have identified 41 cases of classic submucous cleft and 23 cases of occult submucous cleft. The other 167 cases of non-cleft velopharyngeal incompetence were due to a variety of other causes but most were probably patients with occult submucous clefts or other microforms that were not diagnosed because of our initial lack of appreciation of this problem. Patients with velopharyngeal incompetence are classified into four categories: