Ultrasound imaging to identify occult submucous cleft palate.

INTRODUCTION The classic submucous cleft palate triad was described by Calnan in 1954. The findings include a bifid uvula, a bony notch in the posterior hard palate, and a furrow along the midline of the soft palate. The furrow represents an area of diastasis of the velopharyngeal muscle sling and is often referred to as the zona pellucida. In 1975, Kaplan first reported on the ‘‘occult’’ submucous cleft palate. These patients did not have the overt signs present in the classic triad, yet malposition of the levator veli palatini muscle fibers led to an incomplete velar sling with accompanying abnormal velar function. In Kaplan’s series, confirmatory diagnosis of a submucous cleft palate was not possible until surgical exploration at the time of palate repair. The true incidence of occult submucous cleft palate in the general population is unknown and cannot be determined, as these patients are typically only investigated when evaluating for velopharyngeal insufficiency (VPI). Many children with a submucous cleft palate likely go undetected, either because the cleft is missed on physical examination or the child is asymptomatic and never examined. A delay in diagnosis can have longterm consequences on speech development. Untreated VPI can induce the development of compensatory articulation behaviors that can be difficult to overcome. As Kaplan originally described when reporting on the occult submucous cleft palate, the gold standard for definitive diagnosis is intraoperative exploration to determine the orientation of the soft palate muscle fibers. This was supported by Trier, who emphasized the need to intraoperatively identify the abnormal attachments of the levator veli palatini muscle fibers into the hard palate. Others have used nasoendoscopy as the prime instrument to identify an occult submucous cleft palate. A midline bulge of the posterior soft palate, representing the musculus uvulae, is normally seen on the nasal surface of the velum. Typical findings during nasoendoscopy that suggest an occult submucous cleft palate include flattening in the midline of the posterior edge of the palate at the musculus uvulae or a central groove in the posterior portion of the soft palate in the location of the uvular muscle. Although nasoendoscopy has its advantages, the technology does have limitations. Some children will not tolerate this procedure awake. Also, successful identification of an occult submucous cleft palate by nasoendoscopy presumes that the musculus uvulae is hypoplastic or absent. Abnormally oriented levator veli palatini muscle fibers cannot be visualized via nasoendoscopy. To overcome the limitations of nasoendoscopy, some investigators have turned to magnetic resonance imaging (MRI) as a diagnostic instrument to evaluate velopharyngeal muscle orientation. However, the time and expense necessary to perform MRI cannot be underestimated. We describe a technique using transoral ultrasound imaging to evaluate the muscular anatomy of the velum to identify occult submucous cleft palate.