Levator veli palatini muscle activity in relation to intranasal air pressure variation

Continuous positive airway pressure (CPAP) therapy can be used to reduce hypernasality by elevating the air pressure in the nasal cavities during speech. The purpose of this study was to determine whether increased intranasal air pressure loads the major muscle of velopharyngeal closure, the levator veli palatini. Nine subjects, four with cleft palate and five without cleft palate, were studied. Electromyographic activity was measured from the levator veli palatini muscle with several levels of air pressure delivered to the nasal cavities using a commercially available CPAP instrument. It was found that levator veli palatini activity was significantly greater for the positive air pressure conditions than for the atmospheric pressure conditions for both subject groups. This indicates that the levator veli palatini muscle acts against the resistive load produced by the increased intranasal air pressure. The results support the use of CPAP therapy as a method of resistance exercise for strengthening velopharyngeal closure muscles.