Change in Levator Veli Palatini Muscle Activity for Patients with Cleft Palate in Association with Placement of a Speech-Aid Prosthesis

Abstract

Objective: The purpose of this study was to examine whether a speech-aid prosthesis normalizes the activity of the levator veli palatini muscle for patients with cleft palate who exhibit velopharyngeal incompetence. Design: Each subject was instructed to produce repetitions of /mu/, /u/, /pu/, /su/, and /tsu/ and to blow with maximum possible effort. Electromyographic (EMG) activity of the levator veli palatini muscle was recorded with and without a hybrid speech-aid prosthesis in place. Participants: The participants were five patients with repaired cleft palate who were routinely wearing a hybrid speech-aid prosthesis. Results: With the prosthesis in place, the mean value of levator activity changed positively in relation to oral air-pressure change during blowing. Differences in levator activity in relation to speech samples were similar to those in normal speakers. With the prosthesis in place, levator activity for speech tasks was less than 50% of the maximum levator activity for all subjects. The findings were similar to those reported previously for normal speakers. Conclusion: Placement of the prosthesis changed EMG activity levels of the levator veli palatini muscle to levels that are similar to normal speakers. It is possible that, with the increase in the differential levator activity between speech and a maximum force task, the velopharyngeal mechanism has a greater reserve capacity to maintain velopharyngeal closure compared with the noprosthesis condition.