Influences of swallowing volume and viscosity on regulation of levator veli palatini muscle activity during swallowing

This study examined the aspect of the regulation of velum movement in the transition from the oral to pharyngeal phases of swallowing in relation to changes in the swallowing volume and viscosity by means of measurment of levator veli palatini muscle activity. The subjects were nine normal adults, ranging in age from 24 to 30 years. The swallowing volume was set at 1/4, 1/2 and 1 volume of the optimum volume of green tea for swallowing determined in each subject, and the viscosity was adjusted to 0, 2·0 and 4·6 Pa·s by mixing with thickener. Nine test foods were prepared in total. The electromyographic activity of the levator veli palatini muscle was monitored using bipolar hooked wire electrodes. The levator veli palatini muscle activity was defined as the integrated electromyographic wave. The mean in swallowing each test food was determined in each subject. The levator veli palatini muscle activity increased with the swallowing volume for all subjects (P < 0·05) and decreased inversely with the viscosity for six subjects (P < 0·05), but no change with the increase in the viscosity was noted for three subjects. This study clarified the aspect of the regulation of velar movement with regard to the involvement of the levator veli palatini muscle in swallowing activity with changes in the swallowing volume and viscosity.

Effect of a speech aid prosthesis on reducing muscle fatigue

It has been reported that the levator veli palatini muscles of speakers with velopharyngeal incompetence tend to demonstrate muscle fatigue during speech. This study examined whether a speech aid prosthesis might reduce levator muscle fatigue in such speakers. Eight individuals with post-surgical cleft palates, and who wore a speech aid prosthesis, were studied. Each person was asked to pronounce the syllable [pu] more than 50 times. Mean power frequency (MPF) of one syllable was obtained from electromyographic data from the levator muscle. The MPF regression line was calculated during the course of syllable repetition. The absolute values of the slopes of the regression lines with the prosthesis were significantly smaller than those without the prosthesis. It was shown that the prosthesis reduced the decrease in MPF during speech. These results suggested that speech aid prostheses reduce levator muscle fatigue during speech in persons with velopharyngeal incompetence.

Velar ascent and morphological factors affecting velopharyngeal function in patients with cleft palate and noncleft controls: a cephalometric study

This study compares velar ascent and morphological factors affecting velopharyngeal function between patients with repaired cleft palate and noncleft controls from early childhood to puberty. Lateral cephalograms obtained at rest and during blowing from 61 patients with repaired unilateral cleft lip and palate (cleft group) and 82 noncleft controls (control group) were divided into four developmental stages according to age and were studied cross-sectionally. Indices of nasopharyngeal area were derived from a coordinate system and landmarks on lateral cephalograms. The cleft group had lesser velar ascent, more posterosuperior position of the posterior maxilla, shorter velar length, and lesser pharyngeal depth than did the control group. There was a strong correlation between the vertical position of the posterior maxilla and the pharyngeal depth in the cleft group. Discriminant analysis revealed that the cleft group could be discriminated from the control group primarily on the basis of pharyngeal depth, velar length, and velar ascent. Our results suggest that the posterosuperior position of the posterior maxilla in patients with repaired cleft palate, resulting in reduced pharyngeal depth, represents an effort to facilitate velopharyngeal closure by means of shorter velar length and lesser velar ascent.

The effect of growth of nasopharyngeal structures in velopharyngeal closure in patients with repaired cleft palate and controls without clefts: a cephalometric study

To clarify the changes with growth of nasopharyngeal structures involved in velopharyngeal closure, a cross-sectional study from early childhood to puberty was carried out in 61 patients with repaired unilateral cleft lip and palate showing complete velopharyngeal closure (cleft group) and 82 controls without clefts (control group). Measurements of the nasopharyngeal area were derived from a coordinate system and landmarks on lateral cephalograms, and results were analysed by multivariate analysis and t test. The adequate ratio (velar length to pharyngeal depth ratio) in the control group was maintained at a stable value, indicating that the ratio around 1.3 would be standard to maintain velopharyngeal closure. The vertical position of posterior maxilla, pharyngeal depth and velar length in the cleft group showed a different pattern of growth from those in the control group. There was, however, characteristic growth in both groups for maintenance of velopharyngeal closure.

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; Student's 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.

Effect of placement of a speech appliance on levator veli palatini muscle activity during speech

OBJECTIVE

The purposes of this electromyographic study were to examine whether levator veli palatini muscle activity during speech can be changed with placement of a speech appliance and to clarify whether or not the change is related to the type of speech appliance used.

DESIGN

Electromyography (EMG) was performed during production of speech samples in two conditions: with placement and with removal of a speech appliance. Speech samples were the vowel /omega/ and consonant-vowel (omega) syllables, including nasal, plosive, fricative, and affricate consonants.

SETTING

Division for Oral-Facial Disorders, Faculty of Dentistry, Osaka University Dental Hospital, Japan.

PARTICIPANTS

Subjects were six patients with repaired cleft palate and velopharyngeal inadequacy (VPI); three routinely wore a palatal lift prosthesis to correct borderline VPI, and the other three wore a speech appliance hybrid that consisted of a pharyngeal bulb and a palatal lift.

INTERVENTIONS

Each patient was asked to produce each speech sample in both conditions of placement and removal of their respective appliances.

MAIN OUTCOME MEASURES

Smoothed EMG signals of the levator veli palatini muscle were recorded with and without the appliance during five repetitions of each speech sample. The average value of peak smoothed levator EMG was compared between placement and removal conditions for all subjects and between the two subject groups in each experimental condition.

RESULTS

With a speech appliance in place, the range of levator activity was distributed in a portion lower than that in the removed condition for subjects in both appliance groups. In addition, the intervals were smaller in the placement condition than in the removed condition.

CONCLUSION

A speech appliance may prevent hypernasality, nasal emission of air, or both associated with VPI because of mechanical obturation of the velopharynx and an alteration in velopharyngeal function.

Nasalance score variation in normal adult Japanese speakers of Mid-West Japanese dialect

OBJECTIVE

The aims of this study were to examine nasalance score variation for normal adult Japanese speakers of Mid-West dialect and the gender difference in average mean nasalance score.

DESIGN

Nasalance scores were obtained using a nasometer model 6200. The sample stimulus "Kitsutsuki passage," constructed of four sentences containing no Japanese nasal sounds, was used three times by each subject.

PARTICIPANTS

One hundred normal adult speakers (50 women and 50 men) of Japanese served as subjects. The subjects ranged in age from 19 to 35 years of age (24.0 +/- 3.2).

MAIN OUTCOME MEASURE

A mean nasalance score as well as an overall average nasalance value across speakers was calculated for each subject. The average mean nasalance scores between men and women were compared.

RESULTS

The average mean nasalance score for the normal Japanese speakers was 9.1% (+/- 3.9). There was no statistically significant sex difference (p < .01). Average mean scores of 9.8% (+/- 3.5) and 8.3% (+/- 4.0) were obtained for the female and male speakers, respectively.

CONCLUSIONS

The results provide important information concerning criteria to evaluate hypernasal speech due to velopharyngeal inadequacy of Japanese speakers with cleft palate using the nasometer.

A cephalometric study of the stability of the base of the pharyngeal flap following a modified 'unified velopharyngoplasty procedure'

A cephalometric study was conducted on 12 patients with repaired cleft palate to evaluate the stability in level and length of the base attachment of the velopharyngeal complex following pharyngeal flap surgery by a modified velopharyngoplasty. Complete velopharyngeal closure and normal articulation with a speech appliance were confirmed in all patients prior to pharyngeal flap surgery, which was performed on patients 10 years of age and above. Cephalometric radiographs were taken immediately, 1 year, 2 years and 3 years postoperatively. Cephalometric analysis revealed that although the level and length of the base of the velopharyngeal complex showed changes during the first postoperative year, they remained stable when compared with the palatal plane during the last two years. This indicated therefore that the base of a velopharyngoplasty should be attached at the same level of the palatal plane, namely the level of velopharyngeal closure, and that the procedure appeared useful in producing a stable velopharyngeal complex.

A cephalometric study of the relationship between the level of velopharyngeal closure and the palatal plane in patients with repaired cleft palate and controls without clefts

To find out whether the palatal plane is a useful indicator for evaluating the level of velopharyngeal closure, we did a cross-sectional study from early childhood to puberty of the vertical relationship between the palatal plane and the level of velarpharyngeal contact during velopharyngeal functioning in 61 patients with repaired cleft palate (unilateral cleft lip and palate = cleft group) and 82 controls without clefts (control group). Measurements on the vertical dimension were derived from a coordinate system and landmarks on lateral cephalograms, and the significance of differences in measurements was analysed using Student's t-test. Changes in the points of velarpharyngeal contact in relation to the palatal plane with growth showed a consistent tendency though differed between the two groups. In the control group, the PPW (point where palatal plane extension intersects the posterior pharyngeal wall) was maintained at a level that did not differ significantly from the level of midpoint of velarpharyngeal contact during phonation of /a/, and was maintained at a level that did not differ significantly from the level of the inferior point of velarpharyngeal contact. In the cleft group, however, it was maintained at a level that was slightly higher than the superior point of velarpharyngeal contact both during phonation of /a/ and during blowing. These results suggest that the palatal plane is useful as an indicator for evaluating the level of velopharyngeal closure.

Effect of placement of a speech appliance on levator veli palatini muscle activity during blowing

OBJECTIVE

We have observed clinically that some speakers wearing a speech appliance for correction of velopharyngeal incompetence can blow with variable intensity without nasal air escape. This clinical finding suggests that tightness of velopharyngeal closure may be regulated in accordance with oral air pressure during blowing. The purposes of this electromyographic study were (1) to examine whether levator vell palatini muscle activity can be changed in relation to oral air pressure during blowing when the speech appliance is removed, (2) to clarify whether or not the change is related to the severity of velopharyngeal incompetence, and (3) to examine whether placement of a speech appliance can alter levator muscle activity into the equivalent of that of normal speakers during blowing.

DESIGN

Eight patients with repaired cleft palate, who routinely wear a palatal lift prosthesis (PLP) or a hybrid speech appliance of a pharyngeal bulb and palatal lift (bulb-PLP), served as subjects. Subjects were classified into one of two groups according to their speech appliance (PLP group and bulb-PLP group). Electromyography of the levator veli palatini muscle was recorded with a speech appliance in place and then with the speech appliance removed as the subject blew through a tube at three different effort levels.

RESULTS

In the removed condition, the change in levator activity in relation to oral air pressure was variable across subjects in the bulb-PLP group, whereas levator activity changed in relation to oral air pressure change for all subjects in the PLP group. However, levator activity changed in relation to oral air pressure with either speech appliance in place for all subjects irrespective of their speech appliance types.

CONCLUSION

The severity of velopharyngeal incompetence might be related in part to change in levator activity in association with oral air pressure. The effect of a speech appliance to correct velopharyngeal incompetence might consist not only of mechanical obturation of the velopharynx but also of alteration of velopharyngeal function to become similar to normal speakers. Moreover, it is likely that the velopharyngeal system could be well regulated so as to exhibit a consistent outcome of velopharyngeal function.

A cephalometric study by multivariate analysis of growth of the bony nasopharynx in patients with clefts and non-cleft controls

To clarify the characteristics of growth of the nasopharynx, comparison of the cephalometric growth of bones surrounding nasopharynx between 61 patients with complete unilateral cleft lip and palate (UCLP group) and 82 non-cleft controls (NCC group) was carried out. All of the subjects were divided into four developmental stages (i.e. stage 1 at 4 years of age, stage 2 at 8 years of age, stage 3 at 12 years of age and stage 4 at 17 years of age). Measurements on the antero-posterior and the vertical dimensions were derived from a coordinate system and points on bones surrounding the nasopharynx on lateral X-ray cephalograms, and results were analyzed by multivariate analysis and t-test. The results showed that (a) the posterior maxillary point (PMP) in the UCLP group was located more postero-superiorly than that in the NCC group, and this was the main factor that allows discrimination between the two groups and (b) the cranial base, posterior maxilla and the cervical vertebrae were found to be in independent in growth, however, the nasopharyngeal triangle connecting three points on these three bones (Ho: cranial base; PMP: posterior maxillary point; At: atlas) showed harmonious growth in both the UCLP and NCC groups.

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.

Comparison of nasopharyngeal growth between patients with clefts and noncleft controls

OBJECTIVE

This study was a comparison of the cephalometric growth characteristics of the nasopharyngeal structures between UCLP and noncleft controls.

METHOD

Eighty patients with complete unilateral cleft lip and palate (UCLP group) and 82 noncleft controls (NCC group) were assigned to four developmental stages (i.e., stage 1, at 4 years; stage 2, at 8 years; stage 3, at 12 years; and stage 4, at 17 years of age). Measurements on the anteroposterior and the vertical dimensions were derived from reference lines and points of nasopharyngeal structures on the lateral cephalograms.

RESULTS

The results showed that there were no growth differences between the two groups at any stages in the regions of cranial base and cervical vertebrae, and that growth of the posterior maxilla in the UCLP group was significantly less at any stage in both A-P and vertical dimensions than in the NCC groups. As well, the nasopharyngeal triangle (Ho-At-PMP) in the groups showed almost parallel increase with stage, though with short vertical dimension in the UCLP group, and the soft palate length in the UCLP group was significantly less at stages 2, 3, and 4 compared to that in the NCC group. The adequate ratio (soft palate length/pharyngeal depth) in the UCLP group tended to decrease and was significantly less at stage 4 compared to that in the NCC group.

CONCLUSIONS

These results indicate that the growth of the cranial base and the upper cervical vertebrae is independent of the effect of clefts or of surgeries on clefts, and that the growth inhibition at the posterior maxilla results in morphologic disharmony of upper nasopharyngeal structures. This could be a potential factor for the reappearance of velopharyngeal incompetence at a later age.

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.

Maxillary growth after two-stage palatal closure in complete (unilateral and bilateral) clefts of the lip and palate from infancy until 10 years of age

The purpose of the study is to clarify the maxillary growth effects following different types of palatal closure in complete clefts of the lip and palate from infancy to 10 years of age. Lip repair, carried out at 5 months in one stage, was accomplished by Tennison's procedure. These patients were then assigned randomly to each of the 4 experimental groups according to the types of clefts and of palatal closure. One group of 14 patients in unilateral cases (Unil-S) and another group of 8 patients in bilateral cases (Bil-S) received mucoperiosteal palatal push-back procedure in a single stage at 20 months. The third group of 16 patients in unilateral cases (Unil-T) and the fourth group of 7 patients in bilateral cases (Bil-T) received the two-stage palatal closure based on Perko technique in which primary veloplasty was accomplished at 20 months and hard palate closure at 5 year 10 months. Non-cleft subjects were served as Controls. A longitudinal maxillary growth was monitored by the measurements of maxillofacial cast models obtained from each of the subjects. The results showed that the growth in depth and height of the maxilla of the Unil-T showed catch-up growth after primary veloplasty and resulted in no significant differences compared to that of the Control in the later phases, however, the Unil-S did not. The maxillary growth inhibition in height was characteristic in both Bil-S and Bil-T after palatal closure. There were no differences between the Bil-S and Bil-T in any dimensions and observation phases. The results indicate that the employment of the two-stage palatal closure is more beneficial for the unilateral cases, however, careful consideration is needed in bilateral cases.