Investigations of a pressure-sensitive theory of marginal velopharyngeal inadequacy.
This two-part project was designed to test a pressure-sensitive theory of marginal velopharyngeal inadequacy (MPVI). Specifically, are select subgroups of children with MPVI perceived as hypernasal because they fail to achieve consistent closure during vowels and semivowels while demonstrating adequate closure during pressure consonants? In part one, 36 children with cleft palate and other craniofacial anomalies were examined using a clinical assessment protocol that included nasometry and perceived ratings of hypernasal resonance. Children with nasalance percentages above threshold during low-pressure (LP) productions and below threshold for high-pressure (HP) productions were placed in one group (group 1), while children with nasalance percentages below threshold for both LP and HP sentences were placed in another (group 2). Children in the two groups were age- and sex-matched. In part two, endoscopic data were examined for 10 additional children who received nasometry, perceived hypernasal resonance scores, and videoendoscopy on the same day and who received higher mean nasalance measures during production of LP sentences than during production of HP sentences. The results of part one confirmed that children in group 1 were perceived as being significantly more hypernasal than children in group 2 (mean(group 1) = 2.17, mean(group 2) = 1.50; t = 2.75, p =.01). However, results of endoscopic testing failed to demonstrate a consistent observable physiologic pattern of velopharyngeal inadequacy that would confirm the theory that some patients with MVPI are perceived as being hypernasal because of difficulty achieving velopharyngeal closure during vowels and semivowels. CONCLUSIONS; The findings provide partial support for a pressure-sensitive theory of MVPI and demonstrate the value of using both HP and LP sentences to evaluate patients with MVPI.