Hisanaga Hara

Oral air pressure and nasal air flow rate on levator veli palatini muscle activity in patients wearing a speech appliance

This study was designed to determine if levator veli palatini muscle activity can be elicited by simultaneous changes in oral air pressure and nasal air flow when a speech appliance is in place. The speech appliances routinely worn by 15 subjects were each modified experimentally by drilling a hole in the vertical center of the pharyngeal bulb. The air flow rate into the nasal cavity through the opening in the bulb was altered by changing the circular area of the opening in the bulb from the occluded condition (Condition I), to circular area of 12.6 mm2 (4 mm in diameter; Condition II), and then to 38.5 mm2 (7 mm in diameter; Condition III). Electromyographic activity was measured from the levator veli palatini muscle with changes in nasal air flow rate and oral air pressure. Levator veli palatini muscle activity was correlated with changes in nasal air flow and oral air pressure. Increases in levator veli palatini muscle activity were associated with increases in nasal air flow rate compared to oral air pressure changes. The results indicated that aerodynamic variables of nasal air flow and oral air pressure might be involved in the neural control of speech production in individuals wearing a speech appliance, even if the subjects exhibit velopharyngeal incompetence without using a speech appliance. Also, the stimulating effect of bulb reduction therapy on velopharyngeal function might be achieved through the change in aerodynamic variables in association with the bulb reduction.

Effect of Temporary Closure of Oronasal Fistulae on Levator Veli Palatini Muscle Activity

OBJECTIVE The objective of this study was to clarify electromyographically the effects of closing an oronasal fistula on levator muscle activity and oral air pressure in patients with velopharyngeal incompetence and in those with adequate velopharyngeal function. SUBJECTS Five patients with adequate velopharyngeal function and six patients with velopharyngeal incompetence were studied. All subjects had an oronasal fistula at the anterior third portion of the hard palate in spite of primary palatal closure using palatal push-back operation. OUTCOME MEASURES The smoothed electromyographic activity of the levator veli palatini muscle was measured with the fistula closed with a cotton swab dipped in saline and with the fistula left open. RESULTS Under the closed fistula condition, oral air pressure was greater than that observed under the open fistula condition irrespective of velopharyngeal function. Levator veli palatini muscle activity was significantly lower in magnitude under the condition of closure than under the open condition in the patients with adequate velopharyngeal function, whereas in those with velopharyngeal incompetence, it was not significantly changed. CONCLUSIONS The results suggest that velopharyngeal function is affected by temporary closure of an oronasal fistula, and that the magnitude of the effect is greater for subjects with adequate velopharyngeal function than for subjects with velopharyngeal incompetence.

Change in levator veli palatini muscle activity of normal speakers in association with elevation of the velum using an experimental palatal lift prosthesis.

OBJECTIVE The purpose of this study was to examine whether mechanical elevation of the velum can directly affect the levator veli palatini muscle (LVP) activity using normal speakers as subjects. DESIGN Each subject was instructed to produce /mu/, /u/, /pu/, /su/, and /tsu/ in a speech task and to blow with maximum possible effort. Smoothed electromyographic activity of the LVP was recorded with an experimental palatal lift prosthesis (PLP) both in place and removed. PARTICIPANTS Four normal speakers were used as subjects. RESULTS LVP activity for all tasks was significantly smaller (p <.001; Students t test) with the PLP in place than without the PLP for all subjects. An analysis of variance (p <.001) clarified that activity ranges of the LVP were significantly different between the removal and placement conditions for all the subjects. CONCLUSION The result was similar to that previously obtained for patients with velopharyngeal incompetence wearing a PLP. It is possible that the decrease in the LVP activity in association with placement of a PLP is caused by the direct effect of mechanical elevation, which decreases the distance the velopharyngeal mechanisms must travel for complete closure of the velopharynx.