Coordination of velopharyngeal muscle activity during positioning of the soft palate

Exploring Reliable and Identifiable Quantitative Anatomical, Timing, and Displacement Measures in the VFS of Speech

AIM

Videofluroscopy studies of speech are a recognized assessment of velopharyngeal insufficiency (VPI). Yet, this method is subjective and has low inter-rater reliability. Quantitative measures of timing, distance, and area in videofluoroscopic studies of swallowing have been shown to be valid and reliable, but quantitative measures are not routinely used in videofluroscopy studies for VPI. This study explored the use of quantitative measures in patients with VPI in terms of feasibility and reliability.

METHODS

Forty patients of mixed etiology diagnosed with VPI through perceptual speech assessment underwent videofluroscopy. Anatomical landmarks and timing, distance, and area measurements were taken of the velopharyngeal port at rest and during speech tasks using specialized Swallowtail software. 50% of measures were double-blind rated to test inter-rater reliability. Raters reported on the time they took to complete each assessment and the challenges they had. Associations between measures were explored.

RESULTS

Ten timing, line, and area measures were developed based on 3 landmarks. Measures had moderate-substantial inter-rater reliability (intraclass coefficient: 0.69-0.91) except for time to lift (secs), which only achieved fair agreement (intraclass coefficient: 0.56). Measures demonstrated internal consistency ( R >0.60). Raters took, on average, 15 mins per patient and reported some challenges with image resolution, especially in timing measures where structures were blurred by movement.

CONCLUSION

Quantitative measures are reliable and have the potential to add novel information regarding VPI to support multidisciplinary decision-making. Further research with larger patient cohorts is needed to clarify how quantitative measures can support tailored decisions about surgical and therapeutic interventions in order to maximize outcomes for individuals.

The Pediatric Neuroradiologist's Practical Guide to Capture and Evaluate Pre- and Postoperative Velopharyngeal Insufficiency

Up to 30% of children with cleft palate will develop a severe speech disorder known as velopharyngeal insufficiency. Management of velopharyngeal insufficiency typically involves structural and functional assessment of the velum and pharynx by endoscopy and/or videofluoroscopy. These methods cannot provide direct evaluation of underlying velopharyngeal musculature. MR imaging offers an ideal imaging method, providing noninvasive, high-contrast, high-resolution imaging of soft-tissue anatomy. Furthermore, focused-speech MR imaging techniques can evaluate the function of the velum and pharynx during sustained speech production, providing critical physiologic information that supplements anatomic findings. The use of MR imaging for velopharyngeal evaluation is relatively novel, with limited literature describing its use in clinical radiology. Here we provide a practical approach to perform and interpret velopharyngeal MR imaging examinations. This article discusses the velopharyngeal MR imaging protocol, methods for interpreting velopharyngeal anatomy, and examples illustrating its clinical applications. This knowledge will provide radiologists with a new, noninvasive tool to offer to referring specialists.

Vowel height and velum position in German: Insights from a real-time magnetic resonance imaging study

Velum position was analysed as a function of vowel height in German tense and lax vowels preceding a nasal or oral consonant. Findings from previous research suggest an interdependence between vowel height and the degree of velum lowering, with a higher velum during high vowels and a more lowered velum during low vowels. In the current study, data were presented from 33 native speakers of Standard German who were measured via non-invasive high quality real-time magnetic resonance imaging. The focus was on exploring the spatiotemporal extent of velum lowering in tense and lax /a, i, o, ø/, which was done by analysing velum movement trajectories over the course of VN and VC sequences in CVNV and CVCV sequences by means of functional principal component analysis. Analyses focused on the impact of the vowel category and vowel tenseness. Data indicated that not only the position of the velum was affected by these factors but also the timing of velum closure. Moreover, it is argued that the effect of vowel height was to be better interpreted in terms of the physiological constriction location of vowels, i.e., the specific tongue position rather than phonetic vowel height.

An Exploratory Investigation of the Palatoglossus Muscle in Children Using Magnetic Resonance Imaging

PURPOSE

There is currently little evidence reporting the typical morphology of the palatoglossus (PG) muscle. The primary purpose of this exploratory study is to determine whether magnetic resonance imaging (MRI) methods used to quantify the morphology of the levator veli palatini (LVP) muscle can be applied to the PG. The secondary purpose is to provide preliminary data regarding the relationship between the LVP and PG muscles in children.

METHOD

Ten children between ages of 4 and 7 years participated in this study. Each participant was scanned using a nonsedated, child-friendly protocol with a T2-weighted, three-dimensional anatomical scan to obtain images of the oropharyngeal anatomy. Custom, oblique-coronal image planes were created to visualize and measure the LVP and PG muscles in their entirety from origin to insertion. Thermo Scientific Amira Software was used to obtain 2D measurements of PG muscle length, width, velar insertion distance, lingual insertion distance, and several angle measurements.

RESULTS

The PG ranged from 17.95 to 26.96 mm in length across participants. Velar insertion distance ranged from 17.22 to 30.95 mm. Lingual insertion distance ranged from 26.91 to 36.02 mm. Width ranged from 2.32 to 3.08 mm. The angle formed by the PG and LVP muscle planes ranged from 7.3° to 52.7°. The LVP insertion angle ranged from 42.5° to 75.9°. The PG insertion angle ranged from 16.9° to 52.3°.

CONCLUSIONS

MRI was successful in visualizing the PG muscle. The PG was consistent in size and shape within an individual participant but varied across the participant cohort.

Morphometric and Immunohistochemical Characteristics of the Adult Human Soft Palate Muscles

The soft palate is the only structure that reversibly separates the respiratory and gastrointestinal systems. Most species can eat and breathe at the same time. Humans cannot do this and malfunction of the soft palate may allow food to enter the lungs and cause fatal aspiration pneumonia. Speech is the most defining characteristic of humans and the soft palate, along with the larynx and tongue, plays the key roles. In addition, palatal muscles are involved in snoring and obstructive sleep apnea. Considering the significance of the soft palate, its function is insufficiently understood. The objectives of this study were to document morphometric and immunohistochemical characteristics of adult human soft palate muscles, including fiber size, the fiber type, and myosin heavy chain (MyHC) composition for better understanding muscle functions. In this study, 15 soft palates were obtained from human autopsies. The palatal muscles were separated, cryosectioned, and stained using histological and immunohistochemical techniques. The results showed that there was a fast type II predominance in the musculus uvulae and palatopharyngeus and a slow type I predominance in the levator veli palatine. Approximately equal proportions of type I and type II fibers existed in both the palatoglossus and tensor veli palatine. Soft palate muscles also contained hybrid fibers and some specialized myofibers expressing slow-tonic and embryonic MyHC isoforms. These findings would help better understand muscle functions.

Three-Dimensional Anatomy of the Palatopharyngeus and Its Relation to the Levator Veli Palatini Based on Micro-Computed Tomography

BACKGROUND

Although multiple studies have been reported on the palatopharyngeus and levator veli palatini, their subtle anatomy and functions remain unclear. The authors elucidated the relationship between these muscles and their functional implications based on three-dimensional digital techniques.

METHODS

Cadaveric specimens were stained with iodine-potassium iodide and scanned using micro-computed tomography. The muscle fibers were drawn on the exported Imaging and Communications in Medicine images to reconstruct a three-dimensional model and further simplified.

RESULTS

In the soft palate, the palatopharyngeus was divided into three bundles. The largest inferior head was found to attach to the palatine aponeurosis, soft palate, and the hard palate on the oral side, which occupied approximately the anterior 28.4 to 36.2 percent of the soft palate in the midline. The superior head was thin and attached to the palatine aponeurosis and the surrounding mucosa on the nasal side. The posterior head was located posterior to the levator veli palatini with fibers attaching to the levator veli palatini and the median portion of the uvula. The levator veli palatini was clasped by the three heads of the palatopharyngeus. The fasciculi of the palatopharyngeus converged into a bundle of muscles at the pharynx and inserted into the lateral and posterior pharyngeal wall.

CONCLUSIONS

The palatopharyngeus is the largest muscle that connects the soft palate and pharyngeal wall; it closely coordinates with the levator veli palatini to control levator veli palatini overlifting, narrow the velopharyngeal port with the help of the superior constrictor, and elevate the pharynx. The palatopharyngeus and levator veli palatini help each other in velopharyngeal closure through coordination from other muscles.

Contracted Extravelar Segments of the Levator Veli Palatini Muscle: A Magnetic Resonance Imaging Morphometric Study

OBJECTIVES

To provide detailed descriptions of contraction-induced morphometric changes in the extravelar segments of the levator veli palatini (LVP) muscle using 3-dimensional (3-D) magnetic resonance imaging (MRI).

DESIGN

Three-dimensional MRI data were acquired at rest and during "silent /i/" from 4 singers. During silent /i/, participants voluntarily sustained velar elevation while breathing orally for the entire scan time. Focusing on the extravelar segments, LVP length, angle of the muscle origin, and cross-sectional area (CSA), measurements were obtained and compared between tasks.

RESULTS

Three of the 4 participants exhibited the expected patterns of change following concentric contraction of the LVP muscle. Consistent changes from the resting to the contracted state included reductions in LVP length by 13.5% and angle of the muscle origin by 9.8%, as well as increases in CSAs by 22.1%, on average.

CONCLUSIONS

This study presented high-resolution data of the LVP muscle behavior with the first in vivo 3-D measurements of the contracted LVP muscle, which can be useful for the validation of computational models that aim at describing biomechanical properties of the LVP muscle in future research. The active behavior of the extravelar LVP muscle also provides some insight on optimal LVP muscle geometry to consider during cleft palate repair.

Asymmetry and Positioning of the Levator Veli Palatini Muscle in Children With Repaired Cleft Palate

Purpose The purpose of this study is to examine the differences in velopharyngeal dimensions as well as levator veli palatini (levator) muscle morphology, positioning, and symmetry of children with repaired cleft palate with velopharyngeal insufficiency (VPI), children with repaired cleft palate with complete velopharyngeal closure, and children with noncleft anatomy. Method Fifteen children ranging in age from 4 to 8 years were recruited for this study. Ten of the participants had a history of repaired cleft palate, half with documented VPI and the other half with velopharyngeal closure. Five participants with noncleft anatomy were matched for age from a normative database. The magnetic resonance imaging protocol, processing methods, and analysis are consistent with that used in previous literature. Results Regarding velopharyngeal dimensions, median values were statistically significantly different between groups for sagittal angle (p = .031) and effective velopharyngeal ratio (p = .013). With respect to the levator muscle, median values were statistically significant for average extravelar length (p = .018), thickness at midline (p = .021), and thickness between the left and right muscle bundles at the point of insertion into the velum (p = .037). Remaining measures were not statistically significant. Conclusions The levator muscle is significantly different among these three groups with respect to thickness at midline, extravelar length, and symmetry at the point of insertion into the velum. Sagittal angle and effective velopharyngeal ratio are also significantly different. Participants with repaired cleft palate and VPI displayed the greatest degree of asymmetry. Future research should control for surgical procedure type to determine the impact of surgery on the levator muscle and surrounding velopharyngeal anatomy.

Palatal Measurements Pre- and Post-Furlow Cleft Palate Repair: Analysis of Palatal Lengthening and Comparison Within Cleft Types

Objective:

The purpose of this study was to characterize intraoperative palatal lengthening with the modified Furlow cleft palatal repair and to determine whether lengthening correlated with preoperative cleft width, cleft type, or operating surgeon.

Design:

Retrospective study.

Setting:

Academic tertiary care pediatric hospital.

Patients:

One hundred eighty pediatric patients undergoing primary or secondary palatoplasty using the Furlow technique.

Interventions:

Cleft and palatal lengths and widths were measured pre- and post-Furlow cleft palatal repair.

Main Outcome Measures:

Immediate postoperative percentage change in surface palate length, straight palate length, and soft palate length.

Results:

The average cleft widest width and width at the hard–soft palate junction were 10.2 and 9.5 mm, respectively, and varied with Veau cleft type. Following Furlow palatoplasty, lengths of the curved, straight, and soft palate increased by 7.5%, 15.8%, and 30.6%, respectively. Degree of palatal lengthening varied among surgeons and Veau cleft type but was not related to cleft width. Seven (4.0%) patients developed postoperative oronasal fistulas. Patients with a Veau IV cleft and larger cleft widths were at an increased risk for fistula formation.

Conclusions:

This study demonstrates that overall palatal lengthening occurs with the modified Furlow technique. Long-term follow-up studies are needed to determine the clinical relevance of these findings.

Variations in Velopharyngeal Structure in Adults With Repaired Cleft Palate

OBJECTIVE

The purpose of this study was to examine differences in velopharyngeal structures between adults with repaired cleft palate and normal resonance and adults without cleft palate.

DESIGN

Thirty-six English-speaking adults, including 6 adults (2 males and 4 females) with repaired cleft palate (M = 32.5 years of age, SD = 17.4 years) and 30 adults (15 males and 15 females) without cleft palate (M = 23.3 years of age, SD = 4.1 years), participated in the study. Fourteen velopharyngeal measures were obtained on magnetic resonance images and compared between groups (cleft and noncleft).

RESULTS

After adjusting for body size and sex effects, there was a statistically significant difference between groups for 10 out of the 14 velopharyngeal measures. Compared to those without cleft palate, participants with repaired cleft palate had a significantly shorter hard palate height and length, shorter levator muscle length, shorter intravelar segment, more acute levator angles of origin, shorter and thinner velum, and greater pharyngeal depth.

CONCLUSION

Although significant differences were evident in the cleft palate group, individuals displayed normal resonance. These findings suggest that a wide variability in velopharyngeal anatomy can occur in the presence of normal resonance, particularly for those with repaired cleft palate. Future research is needed to understand how anatomic variability impacts function, such as during speech.

Speech and Language Issues in the Cleft Palate Population: The State of the Art

Objective

State-of-the-art activity demands a look back, a look around, and, importantly, a look into the new millennium. The area of speech and language has been an integral part of cleft palate care from the very beginning. This article reviews the development and progression of our knowledge base over the last several decades in the areas of speech; language; anatomy and physiology of the velopharynx; assessment of velopharyngeal function; and treatment, both behavioral and physical, for velopharyngeal problems.

Method

The clear focus is on the cleft palate condition. However, much of what is reviewed applies to persons with other craniofacial disorders and with other underlying causes of velopharyngeal impairment. A major challenge in the next several years is to sort through speech disorders that have a clear anatomic underpinning, and thus are more amenable to physical management, versus those that may be treated successfully using behavioral approaches. Speech professionals must do a better job of finding and applying ways of treating individuals with less severe velopharyngeal impairment, thus avoiding the need for physical management in these persons or ignoring the speech problem altogether.

Conclusion

Early and aggressive management for speech and language disorders should be conducted. For most individuals born with cleft conditions, a realistic goal should be normal speech and language usage by the time the child reaches the school-age years.

Induced Velopharyngeal Fatigue Effects in Speakers with Repaired Palatal Clefts

Objective:

To address whether speakers with cleft palate exhibit velopharyngeal mechanism fatigue and are more susceptible to muscle fatigue than are speakers without cleft palate.

Methods:

Six adults with repaired palatal clefts and mild-moderate hypernasality served as subjects. Velopharyngeal closure force and levator veli palatini muscle activity were recorded. Subjects were asked to repeat /si/ 100 times while an external load consisting of air pressure (0, 5, 15, 25, 35 cm H2O) was applied via a mask to the nasal side of the velopharyngeal mechanism. Fatigue was defined as a reduction in velopharyngeal closure force across the series of /si/ productions, as evidenced by a negatively sloped regression line fit to the closure force data.

Results:

Absolute levels of velopharyngeal closure force were much lower than those observed previously in speakers without palatal clefts. All subjects showed evidence of fatigue. Furthermore, all subjects demonstrated exhaustion, where they were unable to close the velopharyngeal port against the nasal pressure load. This occurred at pressure load levels lower than those successfully completed by speakers without cleft palate.

Conclusions:

In speakers with a repaired palatal cleft, the velopharyngeal closure muscles may not possess the same strength and/or endurance as in normal speakers. Alternatively, muscles may possess adequate strength, but not be positioned optimally within the velopharynx following cleft palate repair or may be forced to move velopharyngeal structures that are stiffer as a result of surgical scarring.

A Comparison of Oral-Nasal Balance Patterns in Speakers who are Categorized as “Almost but Not Quite” and “Sometimes but Not Always”

Objective

The purpose of this study was to determine whether amplitude or temporal patterns of oral-nasal balance differentiate speakers with cleft palate who are classified as belonging to the “almost but not quite” (ABNQ) and “sometimes but not always” (SBNA) subgroups of marginal velopharyngeal inadequacy.

Design

The nasal accelerometric vibrational index (NAVI) was used to measure amplitude and temporal aspects of oral-nasal balance during the productions of oral and nasal syllables, words, and sentences. NAVI measures obtained include mean amplitude, time integral (area under the curve), duration, rise time, and fall time.

Setting

Tertiary care center for patients with cleft palate–craniofacial anomalies.

Participants

Seventeen patients with repaired cleft palate who were assigned by perceptual assessment to the ABNQ subgroup and 17 patients who were assigned to the SBNA subgroup.

Results

No differences were found between the ABNQ and SBNA subgroups with regard to patterns of nasalization. Further analysis as a function of level of production and phonetic context revealed no differences between the subgroups.

Conclusions

Although clinicians may report perceived differences in the resonance patterns of speakers who fall within the category of marginal velopharyngeal inadequacy, further division into the ABNQ and SBNA subgroups has yet to be validated.

Genetics of Cleft Palate and Velopharyngeal Insufficiency

Velopharyngeal insufficiency (VPI) can occur in the setting of an unrepaired or repaired cleft lip and palate. The rate of VPI has been documented as high as 33% in some studies with higher rates of recurrences following surgery associated with genetic syndromes such as 22q11.2 deletions. The primary cause of VPI in these groups is still identified as the anatomic abnormalities of the velum. In this review, the anatomy and physiology of the velum are discussed along with genetic mutations associated with VPI.

Quantitative Endoscopic Phototransducer Investigation of Normal Velopharyngeal Physiology

PURPOSE

The purpose of this research was to learn the extent to which healthy individuals vary in their ability to achieve velopharyngeal closure for speech.

METHOD

Twenty healthy adult volunteers (10 women, 10 men) were tested using an endoscopic phototransducer system that tracks variations in velopharyngeal closure during speech production. Each speaker produced multiple repetitions of three utterances that differed in phonetic content. The data were amplitude normalized and averaged for each speaker.

RESULTS

Average phototransducer measurements were similar across subjects for utterances containing only oral phonemes. Average percentage of velopharyngeal closure varied considerably among subjects when producing utterances containing both oral and nasal phonemes (54%-95%). Average percentage of velopharyngeal closure levels were significantly lower (p < .05) for utterances that included nasal consonants.

CONCLUSIONS

Phototransducer measurements of velopharyngeal closure for speech are sensitive to nasal phoneme content. The findings suggest that motor programming that accomplishes rapid oral-nasal velopharyngeal valving for speech may differ among healthy subjects. However, such variations in motor programming may not perceptually affect typical speakers. If present in individuals with abnormal velopharyngeal mechanisms, these variations may help explain variations among speakers in speech outcomes after physical and behavioral management.

Anthropometric Analysis of the Velopharynx and Related Craniometric Dimensions in Three Adult Populations Using MRI

OBJECTIVE

The purpose of this study is to examine effects of sex, race, and craniometry among three distinct racial groups of adults with normal velopharyngeal anatomy and to determine whether craniofacial structures could be used to predict velopharyngeal structures.

METHODS

A total of 88 adults across three racial groups including white, black, and Asian (Japanese) participated. Magnetic resonance images were obtained using a high-resolution, three-dimensional anatomical scan. Measurements were obtained on the levator veli palatini muscle, velum, and craniofacial structures.

RESULTS

Head circumference was used as a covariate to control the effect of overall cranial size on the analyses. Palate height, linear cranial base, and face height and width vary based on sex, with men demonstrating larger values compared with women. Linear base values, cranial base angle, and face width vary significantly based on race, with Japanese subjects showing the smallest anterior to posterior measures and larger face-width values. Levator muscle measures, excluding angle measures, vary significantly (P < .0001) based on sex. There was no statistically significant difference (P > .05) among racial groups in the levator muscle measures. Velar length and thickness varied significantly based on race and sex.

CONCLUSIONS

This is the first study to examine the interaction of race and sex on levator muscle morphology. In spite of the differences in velar dimensions, no significant differences were found in muscle size, specifically the levator veli palatini, which is contained within the velum.

Speech function of the oropharyngeal isthmus: A modeling study

A finite element method (FEM) based numerical model of upper airway structures (jaw, tongue, maxilla, soft palate) was implemented to observe interactions between the soft palate and tongue, and in particular to distinguish the contributions of individual muscles in producing speech-relevant constrictions of the oropharyngeal isthmus (OPI), or "uvular" region of the oral tract. Simulations revealed a sphincter-like general operation for the OPI, particularly with regard to the function of the palatoglossus muscle. Further, as has been observed with the lips, the OPI can be controlled by multiple distinct muscular mechanisms, each reliably producing a different sized opening and robust to activation noise, suggestive of a modular view of speech motor control. As off-midline structures of the OPI are difficult to observe during speech production, biomechanical simulation offers a promising approach to studying these structures.

Morphology of the levator veli palatini muscle using magnetic resonance imaging

Background : No studies have reported the circumference and diameter of the levator veli palatini muscle at multiple points along its length and from both views (frontal and lateral). The purpose of this study was to provide quantitative data regarding the levator muscle morphology along the length of the muscle using magnetic resonance imaging and advanced three-dimensional computer technology. Methods : Ten Caucasian male subjects participated in the study. Subjects were scanned using a Siemens 3 T Trio. Levator muscle measures were obtained using a two-dimensional image plane. A three-dimensional model was used to measure the circumference and muscle diameter (in two directions) at six points along the length of the levator muscle. Results : Levator muscle length ranged from 41.67 mm to 52.85 mm across all subjects. Mean extravelar muscle length was 30.55 mm (SD, 2.8 mm) and 30.01 mm (SD, 2.9 mm) for right and left muscles. The mean circumference at the origin was 18.90 mm (SD, 2.6 mm). At the second point, the muscle circumference mean increased slightly (mean, 22.40 mm; SD, 4.9 mm). The means for the remainder of the measures (points 3, 4, 5, and 6) were consistent, showing little to no change. Conclusion : Circumference and diameter values were similar to those reported in previous literature. The muscle did diverge at the point where the muscle bundle entered the velum, as it has been previously described. Instead, the muscle diverges near the midline insertion becoming sparser (smaller superior-to-inferior diameter).

Electromyographic activity of the palatinus and palatopharyngeus muscles in exercising horses

REASONS FOR PERFORMING STUDY

Determining the respiratory related activity of the palatinus and palatopharyngeus muscles in exercising horses is relevant because dysfunction of these muscles has been implicated in the pathogenesis of dorsal displacement of the soft palate.

OBJECTIVE

To determine if the palatinus and palatopharyngeus muscles have respiratory activity that increases with intensity in exercising horses.

METHODS

Electromyographic activity was measured in the palatinus and palatopharyngeus muscles using bipolar fine-wire electrodes while the horses completed an incremental exercise treadmill protocol.

RESULTS

Both muscles displayed synchronous expiratory activity that increased significantly (P < 0.05) with exercise intensity. Phasic expiratory activity of the palatinus increased 390 +/- 98%, whereas phasic expiratory activity of the palatopharyngeus increased by 198 +/- 30% as the treadmill speed increased from 6 to 12 m/s.

CONCLUSIONS

The palatinus and palatopharyngeus muscles may be important respiratory muscles, functioning to stabilise the position of the soft palate during intense exercise.

CLINICAL RELEVANCE

The predominant expiratory activity of these muscles may be associated with specific muscle function related to exercise or distinct upper airway phenomena of an obligate nasal breather, such as the horse.

Change in levator veli palatini muscle activity in relation to swallowing volume during the transition from the oral phase to pharyngeal phase

The aim of this study was to examine whether the levator veli palatini (LVP) muscle might be involved in the regulation of velopharyngeal function during the transition between the oral and pharyngeal phases during swallowing, and to examine whether LVP muscle activity could be regulated in relation to the volume of swallowing. Eight normal adults participated in this study. Smoothed EMG signals of the LVP muscle were collected. At the same time, palatoglossus muscle activity was also monitored. Each subject swallowed water at five different volumes: 12.5%, 25%, 50%, 100%, and 150 (or 200) % of the optimum volume for swallowing, which was individually determined for each subject. LVP muscle activity was positively correlated with changes in swallowing volume. The LVP muscle was involved in the regulation of swallowing during the transition from the oral to pharyngeal phases.

Contraction-induced injury to single permeabilized muscle fibers from normal and congenitally-clefted goat palates

OBJECTIVE

Levator veli palatini muscles from normal palates of adult humans and goats are predominantly slow oxidative (type 1) fibers. However, 85% of levator veli palatini fibers from cleft palates of adult goats are physiologically fast (type 2). This fiber composition difference between cleft and normal palates may have implications in palatal function. For limb muscles, type 2 muscle fibers are more susceptible to lengthening contraction-induced injury than are type 1 fibers. We tested the hypothesis that, compared with single permeabilized levator veli palatini muscle fibers from normal palates of adult goats, those from cleft palates are more susceptible to lengthening contraction-induced injury.

INTERVENTIONS

Congenital cleft palates were the result of chemically-induced decreased movement of the fetal head and tongue causing obstruction of palatal closure. Each muscle fiber was maximally activated and lengthened.

OUTCOME MEASURES

Fiber type was determined by contractile properties and gel electrophoresis. Susceptibility to injury was assessed by measuring the decrease in maximum force following the lengthening contraction, expressed as a percentage of the initial force.

RESULTS

Compared with fibers from normal palates that were all type 1 and had force deficits of 23 +/- 1%, fibers from cleft palates were all type 2 and sustained twofold greater deficits, 40 +/- 1% (p = .001).

CONCLUSION

Levator veli palatini muscles from cleft palates of goats contain predominantly type 2 fibers that are highly susceptible to lengthening contraction-induced injury. This finding may have implications regarding palatal function and the incidence of velopharyngeal incompetence.

Patterns of oral-nasal balance in normal speakers with and without cleft palate

OBJECTIVE

The aero-acoustic aspects of nasalization that distinguish speakers with velopharyngeal adequacy from those with velopharyngeal inadequacy are well known. Differences in aerodynamic aspects of nasalization also have been demonstrated in normal speakers with cleft palate and their noncleft counterparts. The purpose of this study was to compare the amplitude and temporal patterns of oral-nasal balance in speakers with cleft palate and normal speech to those with normal speech without cleft palate.

PATIENTS AND METHODS

Using the Nasal Accelerometric Vibrational Index technique, the time course and amplitude of oral-nasal balance were studied in 10 children with cleft palate and velopharyngeal adequacy and 10 noncleft controls. The speech sample included syllable, word, and sentence contexts, most of which were devoid of nasal consonants.

RESULTS

The results indicate few differences between the two groups in contexts devoid of nasal consonants. However, significant differences were evident with regard to temporal aspects of oral-nasal balance in a nasal-oral consonant word context.

CONCLUSIONS

Subtle structural-motor differences that may exist between normal speakers with and without cleft palate may be more evident when the spatiotemporal requirements for velar movement become more complex and result in a greater possible combination of oral-nasal impedance ratios.

Change in Palatoglossus Muscle Activity in Relationto Swallowing Volume During the Transition from the Oral Phaseto the Pharyngeal Phase

The purpose of this study was to examine whether the palatoglossus (PG) muscle is involved in the regulation of function during the transition from the oral to the pharyngeal phase. Seven normal adults participated in the study. Smoothed electromyography (EMG) signals of the PG muscle and levator veli palatini (LVP) muscle were collected. Each subject swallowed water at five different volumes: 12.5%, 25%, 50%, 100%, and 150% (or 200%) of his/her optimum swallowing volume. PG muscle waveform showed two patterns of activity: one of a single peak and the other of two peaks. There was no significant difference (p < 0.01) in the timing of emergence between the single peak and the second peak of the two-peak pattern. There were two patterns of PG muscle activity in response to a change in swallowing volume, i.e., one was a pattern in which the activity was correlated to the change in swallowing volume, the other was a pattern in which the activity was not changed but almost at the maximum activity level, irrespective of swallowing volume. We conclude that the PG muscle could be involved in the regulation of swallowing from the oral to the pharyngeal phase. The activity could be influenced by swallowing volume.

Change in levator veli palatini muscle activity for patients with cleft palate in association with placement of a speech-aid prosthesis

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 no-prosthesis condition.

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.

Investigations of a pressure-sensitive theory of marginal velopharyngeal inadequacy

PURPOSE

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?

METHODS

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.

RESULTS

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.

Effects of vowel height and vocal intensity on anticipatory nasal airflow in individuals with normal speech

The purpose of this study was to determine the effects of vowel height and vocal intensity on the magnitude of anticipatory nasal airflow in normal speakers when producing vowel-nasal-vowel (VNV) sequences. Measurements of nasal and oral airflow were obtained from 15 men and 12 women with normal speech during production of the VNV sequences /ini/ and /ana/ at low, medium, and high intensity levels. Ratios of nasal to oral-plus-nasal airflow were calculated for the initial vowel of both utterances at each of the intensity levels. Analysis of variance (ANOVA) procedures indicated a significant main effect of intensity level and a significant vowel-by-sex interaction effect (p < .05) on the airflow ratios. Overall, the airflow ratio was reduced at high as compared to low intensity levels, regardless of sex of the speaker or vowel type. Female speakers exhibited greater airflow ratios during production of /ini/ than during productions of /ana/. Their airflow ratios were also greater during production of /ini/ than were those of male speakers. The results suggest that vocal intensity may affect velopharyngeal (VP) function in an assimilative nasal phonetic context. The results further suggest that anticipatory nasal airflow may be determined by the configuration of the oral cavity to a greater extent in women than in men. Theoretical and clinical implications are discussed.

Quantitative analysis of the velopharyngeal sphincter function during speech

OBJECTIVE

This study reports a new concept for quantitative analysis of velopharyngeal function using electromagnetic articulography and simultaneous transoral video endoscopy.

PARTICIPANTS

The velopharyngeal closure mechanism was studied in 16 healthy German subjects during production of the vowel-consonant-vowel sequences /afa/ and /apa/.

DESIGN

Velar movements in the sagittal and vertical direction were measured by electromagnetic articulography (EMA) while video endoscopy was used for recording in the sagittal and transverse directions.

MAIN OUTCOME MEASURE

A transverse sagittal quotient (TSQ) was defined after the measurement of sagittal and transverse diameters of the velopharyngeal port (VPP) in the video-endoscopic pictures on the basis of a frame-by-frame analysis.

RESULTS

The sphincter morphology was objectively determined with the TSQ base value. A terminal sphincter deformation (TSD) for closure phases of articulatory movement was revealed by a qualitative shape analysis of the TSQ curves.

CONCLUSIONS

The assessment of the TSQ of velopharyngeal port diameters and the TSD in the terminal closure period lead to a new dynamic interpretation of velopharyngeal closure patterns.

Effects of gravitational load on jaw movements in speech

External loads arising as a result of the orientation of body segments relative to gravity can affect the achievement of movement goals. The degree to which subjects adjust control signals to compensate for these loads is a reflection of the extent to which forces affecting motion are represented neurally. In the present study we assessed whether subjects, when speaking, compensate for loads caused by the orientation of the head relative to gravity. We used a mathematical model of the jaw to predict the effects of control signals that are not adjusted for changes to head orientation. The simulations predicted a systematic change in sagittal plane jaw orientation and horizontal position resulting from changes to the orientation of the head. We conducted an empirical study in which subjects were tested under the same conditions. With one exception, empirical results were consistent with the simulations. In both simulation and empirical studies, the jaw was rotated closer to occlusion and translated in an anterior direction when the head was in the prone orientation. When the head was in the supine orientation, the jaw was rotated away from occlusion. The findings suggest that the nervous system does not completely compensate for changes in head orientation relative to gravity. A second study was conducted to assess possible changes in acoustical patterns attributable to changes in head orientation. The frequencies of the first (F1) and second (F2) formants associated with the steady-state portion of vowels were measured. As in the kinematic study, systematic differences in the values of F1 and F2 were observed with changes in head orientation. Thus the acoustical analysis further supports the conclusion that control signals are not completely adjusted to offset forces arising because of changes in orientation.

A finite element model of the soft palate

OBJECTIVE

As a step toward better understanding of normal and abnormal velar control, a finite element model of the soft palate was developed.

DESIGN

A static two-dimensional midsagittal model of the velum was given physical dimensions to match that of a 10-year-old boy. Biomechanical properties of the tissues were inferred based on previous histologic studies. Velar movements were induced by the influence of three extrinisic velar muscles: the levator veli palatini, the palatoglossus, and the palatopharyngeus, which were simulated as external forces acting on the velar model.

RESULTS AND CONCLUSIONS

Velopharyngeal opened and closed positions were simulated as well as a variety of intermediate steps between the two configurations. Velopharyngeal closure was also simulated in a manner appropriate for both high and low vowels. Future extensions of the model will incorporate the muscles as an intrinsic component of the model and will include a full time-dependent implementation, including inertial effects. Future studies will compare model predictions with experimental data from the laboratory, including both kinematic data and velopharyngeal closure forces.

Velopharyngeal closure force and levator veli palatini activation levels in varying phonetic contexts

The purpose of this study was to measure velopharyngeal closure force in varying phonetic contexts for normal men and women subjects. Levator veli palatini muscle activity was measured as well. Place and manner of articulation, voicing, and the effects of consonant sequencing were studied in different vowel contexts. When the data were grouped by sex of subject, no differences were found in absolute values of velopharyngeal closure force for the men versus women subjects. As expected, nonnasal consonants were produced with greater velopharyngeal closure force than nasal consonants. High vowels were produced with greater closure force than low vowels. Closure force was greater for voiceless than for voiced consonants but only for the men and only within /i/ and /u/ contexts. The lingua-dorsal consonant was associated with greater closure force than the lingua-apical consonant but only for the men and only in the high-back vowel environment. Significant differences in closure force were not found between fricatives or stops. A tendency for greater closure force for the fricative consonant was observed when the fricative followed rather than preceded the nasal consonant. Vowel identity had an effect on closure force during consonant production in the men in that closure force was greater for /s/ and /n/ in high versus low vowel contexts. Men exhibited a larger number of significant differences in closure force than did the women. The results suggest that velopharyngeal closure force is not controlled by a single muscle (the levator veli palatini) but that other muscles and mechanical factors are likely contributors.

Pressure-flow differences in performance during production of the CV syllables /pi/ and /pa/

Inconsistencies in velopharyngeal function were observed to have been reported in pressure-flow reports. This article introduces our findings from a sample of pressure-flow records and discusses possible implications for management. A retrospective review of the pressure-flow records for 51 patients was completed. All patients had been evaluated at the Craniofacial Center, University of Illinois at Chicago. Records were selected based on the following criteria: patients were referred for evaluation of velopharyngeal function and had no secondary surgeries on the velopharyngeal mechanism, no fistulae, no neurologic disorders, and no compensatory articulations. At the time of testing, patients ranged in age from 4 to 38 years with most being under 18 years of age. Velopharyngeal orifice areas were obtained using the pressure-flow technique during repeated CV syllables, including /pi/ and /pa/. Our results show that 8 of 51 patients exhibited a specific type of inconsistent velopharyngeal function (i.e., they exhibited velopharyngeal closing during /pa/ repetitions, but had openings during /pi/ repetitions). The reverse finding was not observed among any of the 51 patients. We concluded that the velopharyngeal incompetence observed during utterances involving /i/ may have been due to the downward pull on the palate of the palatoglossus muscle, which could not be counteracted by the already maximized levator activity in borderline patients.

Effects of gravity on velopharyngeal muscle activity during speech

Assessment of the role of gravitational forces in the motor control of the velopharyngeal mechanism was the focus of this study. Specifically, the effect of gravity on activation levels of the levator veli palatini and palatoglossus muscles was assessed. Nineteen volunteers repeated a CV syllable in upright and supine body positions. Overall, lower peak activation levels of levator veli palatini were observed in the supine body position. The results suggest that less muscle activity was seen in the levator veli palatini in the supine body posture, where gravitational effects worked in the same direction (i.e., toward closure). No statistically significant group effects were seen in muscle activation levels of palatoglossus across the two body postures, although clear gravity effects were observed in some subjects. The implications of these findings from a speech motor control perspective are discussed in relation to normal and disordered velopharyngeal function.

Measurement of velopharyngeal closure force during vowel production

The purposes of this study were to (a) design and test a new velopharyngeal closure force sensing bulb, and (b) use the closure force bulb to gather additional information on the variations in closure force associated with different vowels. The closure force sensing bulb possessed a flat frequency response to 30 Hz. Its output was highly linear relative to applied gram force. Reliable placement of the bulb in human subjects was achieved following prescribed placement criteria. The bulb was sensitive to small variations in velopharyngeal closure force. In agreement with some previous reports, high vowels were associated with greater velopharyngeal closure forces than low vowels. The results of this investigation support the notion that articulatory goals are specified for vowels. This vowel specificity was observed during production in both isolation and in context.