The Contribution of the Radiologist to Evaluation of Velopharyngeal Insufficiency

Normal speech and voice production depend in large measure upon separation of the oral and nasal cavities by closure of the velopharyngeal port. This is accomplished by elevation of the velum or soft palate and the sphincteric action of the pharyngeal walls. T h e elevation and posterior movement of the soft palate, which occurs as a result of the combined contributions of the levator palatini and the palatopharyngeus muscles, gives the most important contribution to closure and is easily and clearly demonstrated by radiological techniques. Medial movement of the lateral pharyngeal walls against the edges of the velum also assists in closure of the lateral aspects of the velopharyngeal portal. The forward bulging of the posterior pharyngeal wall in normal speech is slight and its contribution to speech is probably insignificant. However, pharyngeal wall motion may become significant in the individual with palate dysfunction. Lateral pharyngeal wall motion can be studied by radiological techniques (Skolnick, 1969) as well as by ultrasound (Kelsey et al., 1972). There must be synchronous motion of both components of the closure mechanism to prevent the nasal emission of sound. Failure of the velopharyngeal portal to close during the utterence of non-nasal sounds is referred to as velopharyngeal insufficiency. Velopharyngeal insufficiency can be caused by a number of factors, including congenital structural abnormalities, such as a cleft or shortened palate, congenital or acquired neuromuscular dysfunction, or traumatically induced clefts. Although data are available on the frequency of maxillofacial clefts, there are no good data available on the frequency of velopharyngeal insufficiency from all causes. Evaluation of the velopharyngeal port for degree and location of incompetence requires visualization and/or physiological monitoring during a wide range of speech tasks. The re are a number of techniques available, which can be divided into invasive or noninvasive categories (Table 1). All invasive techniques, with the possi-