Morphology of the levator veli palatini muscle using magnetic resonance imaging

Examining Craniofacial and Velopharyngeal Structures in Premature Infants: A Window Into the Womb

BACKGROUND

Very little is known about how the velopharynx and levator veli palatini muscle develop in utero. The purpose of this study was to describe craniofacial, velopharyngeal, and levator veli palatini dimensions in a group of infants born prematurely and imaged before 40 weeks gestation.

METHODS

A retrospective, descriptive study design was utilized to examine the MRI scans of 6 infants less than 40 weeks' gestation. Imaging was initially completed for medically necessity and pulled from patients' charts retrospectively for the purpose of this study. Craniofacial, velopharyngeal, and levator veli palatini dimensions were analyzed.

RESULTS

All linear measures were consistently shorter across all variable categories. While effective VP ratio was less favorable for speech in infants under 40 weeks' gestation, angle measures such as LVP angle of origin, NSB angle, SNA angle, and SNB angle were relatively unchanged.

CONCLUSIONS

Linear craniofacial, VP, and LVP variables tend to be smaller in infants under 40 weeks' gestation than those reported within the first 6 months of life while angulation is relatively similar. Future research in this area may be relevant to better diagnosis of craniofacial conditions in utero.

Magnetic Resonance Imaging of the Velopharynx: Clinical Findings in Patients with Velopharyngeal Insufficiency

BACKGROUND

Magnetic resonance imaging (MRI) is the only imaging modality capable of directly visualizing the levator veli palatini (LVP) muscles: the primary muscles responsible for velopharyngeal closure during speech. MRI has been used to describe normal anatomy and physiology of the velopharynx in research studies, but there is limited experience with use of MRI in the clinical evaluation of patients with velopharyngeal insufficiency (VPI).

METHODS

MRI was used to evaluate the velopharyngeal mechanism in patients presenting for VPI management. The MRI followed a fully awake, nonsedated protocol with phonation sequences. Quantitative and qualitative measures of the velopharynx were obtained and compared with age- and sex-matched individuals with normal speech resonance.

RESULTS

MRI was completed successfully in 113 of 118 patients (96%). Compared with controls, patients with VPI after cleft palate repair had a shorter velum (P < 0.001), higher incidence of LVP discontinuity (P < 0.001), and shorter effective velar length (P < 0.001). Among patients with persistent VPI after pharyngeal flap placement, findings included a pharyngeal flap base located inferior to the palatal plane [11 of 15 (73%)], shorter velum (P < 0.001), and higher incidence of LVP discontinuity (P = 0.014). Patients presenting with noncleft VPI had a shorter (P = 0.004) and thinner velum (P < 0.001) and higher incidence of LVP discontinuity (P = 0.014).

CONCLUSIONS

MRI provides direct evidence of LVP muscle anomalies and quantitative evaluation of both velar length and velopharyngeal gap. This information is unavailable with traditional VPI imaging tools, suggesting that MRI may be a useful tool for selecting surgical procedures to address patient-specific anatomic differences.

Protocol for a Prospective Observational Study of Revision Palatoplasty Versus Pharyngoplasty for Treatment of Velopharyngeal Insufficiency Following Cleft Palate Repair

OBJECTIVE

To present the design and methodology for an actively enrolling comparative effectiveness study of revision palatoplasty versus pharyngoplasty for the treatment of velopharyngeal insufficiency (VPI).

DESIGN

Prospective observational multicenter study.

SETTING

Twelve hospitals across the United States and Canada.

PARTICIPANTS

Individuals who are 3-23 years of age with a history of repaired cleft palate and a diagnosis of VPI, with a total enrollment target of 528 participants.

INTERVENTIONS

Revision palatoplasty and pharyngoplasty (either pharyngeal flap or sphincter pharyngoplasty), as selected for each participant by their treatment team.

MAIN OUTCOME MEASURE(S)

The primary outcome is resolution of hypernasality, defined as the absence of consistent hypernasality as determined by blinded perceptual assessment of a standard speech sample recorded twelve months after surgery. The secondary outcome is incidence of new onset obstructive sleep apnea. Statistical analyses will use propensity score matching to control for demographics, medical history, preoperative severity of hypernasality, and preoperative imaging findings.

RESULTS

Study recruitment began February 2021. As of September 2022, 148 participants are enrolled, and 78 have undergone VPI surgery. Enrollment is projected to continue into 2025. Collection of postoperative evaluations should be completed by the end of 2026, with dissemination of results soon thereafter.

CONCLUSIONS

Patients with VPI following cleft palate repair are being actively enrolled at sites across the US and Canada into a prospective observational study evaluating surgical outcomes. This study will be the largest and most comprehensive study of VPI surgery outcomes to date.

Establishing a Clinical Protocol for Velopharyngeal MRI and Interpreting Imaging Findings

Traditional imaging modalities used to assess velopharyngeal insufficiency (VPI) do not allow for direct visualization of underlying velopharyngeal (VP) structures and musculature which could impact surgical planning. This limitation can be overcome via structural magnetic resonance imaging (MRI), the only current imaging tool that provides direct visualization of salient VP structures. MRI has been used extensively in research; however, it has had limited clinical use. Factors that restrict clinical use of VP MRI include limited access to optimized VP MRI protocols and uncertainty regarding how to interpret VP MRI findings. The purpose of this paper is to outline a framework for establishing a novel VP MRI scan protocol and to detail the process of interpreting scans of the velopharynx at rest and during speech tasks. Additionally, this paper includes common scan parameters needed to allow for visualization of velopharynx and techniques for the elicitation of speech during scans.

Simulation of Velopharyngeal Biomechanics Identifies Differences in Sphincter Pharyngoplasty Outcomes: A Matched Case-Control Study

The purpose of this study was to develop a framework for 3D subject-specific computational models capable of simulating velopharyngeal biomechanics for anatomic changes that occur following pharyngoplasty and to gain insight into biomechanical factors that may lead to different speech/surgical outcomes. Patient-specific models for two, matched participants with differing speech/surgical outcomes were developed: one with a successful pharyngoplasty outcome and one with a failed pharyngoplasty outcome. Surgical scenarios were simulated to model pharyngoplasty location, identify LVP muscle biomechanics, and identify an optimal pharyngoplasty location for each participant. These simulations illustrate the potential for optimizing pharyngoplasties based on patient-specific geometry.

Anatomical and Physiological Changes Following Primary Palatoplasty Using "The Buccal Flap Approach"

OBJECTIVE

The purpose of this study was to determine the anatomical differences among selected individuals with a cleft palate repaired using "The Buccal Flap Approach" during primary palatoplasty compared to aged-matched participants without cleft palate.

DESIGN

Observational, prospective.

SETTING

Two regional hospitals.

PARTICIPANTS

A total of 30 adult males consisting of 15 adults born with cleft palate who received the Double Opposing Z-Plasty plus Buccal Flaps (DOZP  +  BF) repair at the time of primary palatoplasty and no history of secondary speech surgery or orthognathic surgery and 15 adults without a history of cleft palate.

INTERVENTIONS

All participants underwent MRI to visualize anatomy.

MAIN OUTCOME MEASURES

Ten velopharyngeal and craniofacial anatomical measures.

RESULTS

No statistically significant differences between groups were observed for velar thickness, velar length, pharyngeal depth, NSBa angle, SNB angle, or levator veli palatini length. Individuals with the DOZP  +  BF presented with a greater effective velar length (p < .001), greater effective VP ratio (p < .001), smaller SNA angle (p < .001), and smaller maximal velar stretch (p < .001) compared to the control participants.

CONCLUSIONS

This study suggests that adult males who received the DOZP  +  BF repair at the time of primary palatoplasty and no history of secondary speech surgery or orthognathic surgery present with a longer effective velar length and larger effective VP ratio in comparison to the non-cleft group. Future research is needed to compare patients with and without favorable outcomes from multiple surgical types to fully understand how surgical techniques alter the anatomy.

Can Velopharyngeal MRI be Used in Individuals with Orthodontic Devices?

OBJECTIVE

To evaluate the influence of common pediatric orthodontic appliances on velopharyngeal (VP) MRI and to compare MR image sequences to determine if sequence parameters impact the visibility of key VP structures commonly assessed in clinical VP MRI.

DESIGN

Participants undergoing orthodontic treatment completed a VP MRI study. Level of distortion caused by orthodontic devices on 8 anatomical sites of interest and using variable MRI sequences was evaluated.

SETTING

Single institution.

PARTICIPANTS

Nineteen participants undergoing orthodontic treatment.

MAIN OUTCOME

Level of distortion caused by metal artifacts and MR sequence used.

RESULTS

The results of this study demonstrate that appliances such as hyrax palatal expanders and braces with stainless steel brackets are acceptable for a VP MRI, while class II corrector springs are not recommended. The HASTE MRI sequence with 2D imaging techniques should be utilized if the child has orthodontic devices, while FSE and 3D imaging techniques are not recommended. The presence of wire spring coils and molar bands are likely to not to interfere with the MRI evaluation.

CONCLUSIONS

Findings from this study suggest that the presence of orthodontic appliances does not hinder visualization of all velopharyngeal structures during an MRI. Therefore, careful consideration must be made prior to disqualifying or recommending patients for VP MRI.

Preliminary Development of an MRI Atlas for Application to Cleft Care: Findings and Future Recommendations

OBJECTIVE

To introduce a highly innovative imaging method to study the complex velopharyngeal (VP) system and introduce the potential future clinical applications of a VP atlas in cleft care.

DESIGN

Four healthy adults participated in a 20-min dynamic magnetic resonance imaging scan that included a high-resolution T2-weighted turbo-spin-echo 3D structural scan and five custom dynamic speech imaging scans. Subjects repeated a variety of phrases when in the scanner as real-time audio was captured.

SETTING

Multisite institution and clinical setting.

PARTICIPANTS

Four adult subjects with normal anatomy were recruited for this study.

MAIN OUTCOME

Establishment of 4-D atlas constructed from dynamic VP MRI data.

RESULTS

Three-dimensional dynamic magnetic resonance imaging was successfully used to obtain high quality dynamic speech scans in an adult population. Scans were able to be re-sliced in various imaging planes. Subject-specific MR data were then reconstructed and time-aligned to create a velopharyngeal atlas representing the averaged physiological movements across the four subjects.

CONCLUSIONS

The current preliminary study examined the feasibility of developing a VP atlas for potential clinical applications in cleft care. Our results indicate excellent potential for the development and use of a VP atlas for assessing VP physiology during speech.

Incorporating Velopharyngeal MRI into the Clinical Decision-Making Process for a Patient Presenting with Velopharyngeal Dysfunction Following a Failed Palatoplasty

This clinical report describes the implementation of magnetic resonance imaging (MRI) to evaluate a patient with long-standing velopharyngeal dysfunction. She was referred to the craniofacial clinic at age 10 with no prior surgical history and subsequently completed a Furlow palatoplasty due to a suspected submucous cleft palate. However, results were unfavorable with minimal improvement in speech or resonance. The clinical presentation, treatment, outcomes, and contributions from MRI for secondary surgical planning are described. Addition of MRI into the clinical workflow provided insights into the anatomy and physiology of the velopharyngeal mechanism that were unable to be obtained from nasendoscopy and speech evaluation alone.

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.

Growth Effects on Velopharyngeal Anatomy Within the First 2 Years of Life

PURPOSE

Limited quantitative data exist regarding growth of the velopharynx within the first 2 years of life. The purpose of this study was to (a) quantify changes in velopharyngeal structures due to growth during the first 2 years of life, (b) examine the impact of sex and race within this age range, and (c) provide normative measures for comparison to individuals with cleft palate.

METHOD/DESCRIPTION

A retrospective chart review was completed of all patients up to 24 months of age that underwent magnetic resonance imaging of the head for medical necessity within the past 18 months using a three-dimensional fluid-attenuated inversion recovery sequence. Measurements of the velopharynx were obtained from 200 scans consistent with previous literature. Participants were divided into five groups based on corrected age for comparison. Variables of interest included adenoid depth, angle of origin, effective velopharyngeal ratio, effective velar length, levator veli palatini length, origin-origin distance, pharyngeal depth, sagittal angle, velopharyngeal ratio, velar insertion distance, velar length, and velar thickness.

RESULTS

Velopharyngeal dimensions were significantly different among corrected age groups after controlling for sex and race. Regarding age, analyses revealed significant differences in all variables of interest except effective velopharyngeal ratio. Regarding sex, significant differences were observed for angle of origin, effective velopharyngeal ratio, effective velar length, levator veli palatini muscle length, and velar insertion distance. Regarding race, a significant difference was only observed for angle of origin.

CONCLUSIONS

Results of this study demonstrate growth of velopharyngeal anatomy in normative infants with race and sex effects apparent in children up to 24 months of age. Variable growth trends were observed among different velopharyngeal measures.

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.

Autologous Fat Grafting in Velopharyngeal Insufficiency Gives Complete and Stable Speech Recovery in Patient Under 7 years

ABSTRACT

The authorspresent a retrospective observational cohort study of 47 French speaking consecutive patients treated with retropharyngeal wall filling with autologous fat graft from 2006 to 2019 in a single tertiary center, to assess with a long-term follow-up, the best tailored treatment to recovery speech for velopharyngeal insufficiency, and to stress the importance of early treatment with minimally invasive procedure with retropharyngeal wall fat grafting. In preoperative setting, a clinical and instrumental evaluation with aerophonoscope is completed by a palatal closure assessment with nasal endoscopy. All patients were classified according with Borel Maisonny score pre- and post-operatively. Sixty three fat injections were performed. In 4 cases a pharyngeal flap was performed after fat graft for an insufficient speech result. The authors had no complications. Patients with less than 7 years of age obtained a complete recovery of their velopharyngeal incompetence (P = 0.03) compared to older patients. In conclusion, the authors can state that this tailored surgical technique needs a multidisciplinary approach. Many variables can affect postoperative results: fat reabsorption, concurrently performed surgery, pattern of pharyngeal closure, hearing impairment. None of these factors affected our result. Early treatment plays a crucial role to achieve better results. Patients with less of 7 years showed a better result in this functional treatment.

A Cadaveric and Magnetic Resonance Imaging Investigation of the Salpingopharyngeus

Purpose The aim of the study was to update our information regarding the salpingopharyngeus (SP) muscle using cadaveric and in vivo magnetic resonance imaging (MRI) data. Primary objectives were to (a) observe the presence/absence of the muscle and (b) quantify and describe its dimensions and course. Method SP specimens from 19 cadavers (10 women, nine men) were analyzed. Following head bisection, measurements of SP, including width of the cartilaginous attachment (CW) and width of the superior muscle base (SMW), were taken before and after removal of the overlying mucosa. In addition, SP was analyzed in 15 healthy subjects (eight men, seven women) using high-resolution three-dimensional MRI data. CW and SMW measures were replicated in the paraxial MRI view. Results The presence of the salpingopharyngeal fold and muscle was confirmed bilaterally in all cadaveric and living subjects. Following mucosa removal, mean cadaveric CW and SMW measurements were 5.6 and 3.8 mm, respectively. Mean in vivo CW and SMW were 6.1 and 3.7 mm, respectively. Results from the hierarchical regression analyses revealed that, in both cadaveric and living groups, SMW is dependent on the relationship between age and body weight, after controlling for sex. Conclusions The salpingopharyngeal fold and SP muscle are always present bilaterally and can be quantified at the superior origin using both cadaveric and in vivo three-dimensional MRI data. Though both the superior origin and inferior course of SP are highly variable, the size of the SP muscle is dependent on characteristics known to affect muscle fibers, such as the relationship between age and body weight. Given the consistent and quantifiable presence of the SP muscle, its potential role in velopharyngeal function for speech and swallowing is reconsidered. Supplemental Material https://doi.org/10.23641/asha.14347859.

A Preliminary Study of Anatomical Changes Following the Use of a Pedicled Buccal Fat Pad Flap During Primary Palatoplasty

OBJECTIVE

The purpose of this study was to examine the surgical impact of the pedicled buccal fat pad (BFP) flap on the levator veli palatini (LVP) muscle and surrounding velopharyngeal (VP) anatomy following primary palatoplasty using magnetic resonance imaging (MRI).

DESIGN

Observational, prospective.

SETTING

MRI studies were completed at 3 different facilities. All participants with BFP flap were operated on by the same surgeon.

PARTICIPANTS

Five pediatric participants with cleft palate with or without cleft lip (CP±L) who underwent primary palatoplasty with BFP flap placement. Comparison groups consisted of 10 participants: 5 with CP±L who did not receive the BFP flap and 5 healthy controls.

INTERVENTIONS

All participants underwent nonsedated MRI 2 to 5 years postoperatively.

MAIN OUTCOMES AND MEASURES

Anatomical measures of the velopharynx and LVP among the 3 participant groups.

RESULTS

Median values were significantly different among groups for velar length (P = .042), effective velar length (P = .048), effective VP ratio (P = .046), LVP length (P = .021), extravelar LVP length (P = .009), and LVP origin-origin distance (P = .030). Post hoc analysis revealed a statistically significant difference between the BFP and traditional repair groups for effective VP ratio (P = .040), extravelar LVP length (P = .033), and LVP length (P = .022).

CONCLUSIONS

This study provides preliminary support that the BFP flap creates a longer velum, with increased distance between the posterior hard palate and the LVP, and a larger effective VP ratio compared to traditional surgical techniques. Future research is needed to determine whether this procedure provides a more favorable mechanism for VP closure.

Magnetic Resonance Imaging of the Oral Cavity and Oropharynx

ABSTRACT

Understanding oral cavity and oropharyngeal anatomy is important to identify various pathologies that may afflict them. This article reviews normal magnetic resonance imaging anatomy of these vital spaces and structures, with special attention to the complex musculature, mucosal surfaces, relevant osseous structures, salivary glands, and nerves. Anatomic awareness of these spaces and critical potential pathways for perineural tumoral spread are important to recognize to improve diagnostic evaluation and treatment.

Evaluation of the Symmetry of the Levator Veli Palatini Muscle and Velopharyngeal Closure Among a Noncleft Adult Population

PURPOSE

The goal of this study is to determine the typical range of asymmetry between the length and thickness of the levator veli palatini muscle and to explore the impact of the observed asymmetry on velopharyngeal closure. A second objective is to report normative length and thickness of the levator veli palatini muscle among adults with typical velopharyngeal anatomy.

METHOD

Magnetic resonance imaging (MRI) data and Amira 5.5 Visualization software were used to evaluate the levator veli palatini muscle among 89 participants with typical velopharyngeal anatomy. Flexible nasopharyngoscopy was used to determine the function of velopharyngeal closure among 39 of the 89 participants with typical velopharyngeal anatomy to examine the functional impact of observed asymmetry.

RESULTS

Matched paired t tests demonstrated a nonsignificant difference between the length and thickness of the right and left levator muscle. The mean difference between the right and left length of the levator muscle was 2.28 mm but ranged from 0.09 mm to 10.37 mm. In all cases where individuals displayed asymmetry in the levator muscle through MRI, there was no observed impact on the symmetry of velopharyngeal closure.

DISCUSSION

This study suggest that differences in the right and left levator veli palatini muscle are not significant among individuals without cleft palate. However, among individual cases where asymmetry was sizeable, there was no direct impact on the closure pattern. This may suggest there are multiple factors that contribute to asymmetrical velopharyngeal closure that are beyond the level of the levator veli palatini muscle.

Identifying Predictors of Levator Veli Palatini Muscle Contraction During Speech Using Dynamic Magnetic Resonance Imaging

Purpose The purpose of this study was to identify predictors of levator veli palatini (LVP) muscle shortening and maximum contraction velocity in adults with normal anatomy. Method Twenty-two Caucasian English-speaking adults with normal speech and resonance were recruited. Participants included 11 men and 11 women (M = 22.8 years, SD = 4.1) with normal anatomy. Static magnetic resonance images were obtained using a three-dimensional static imaging protocol. Midsagittal and oblique coronal planes were established for visualization of the velum and LVP muscle at rest. Dynamic magnetic resonance images were obtained in the oblique coronal plane during production of "ansa." Amira 6.0.1 Visualization and Volume Modeling Software and MATLAB were used to analyze images and calculate LVP shortening and maximum contraction velocity. Results Significant predictors (p < .05) of maximum LVP shortening during velopharyngeal closure included mean extravelar length, LVP origin-to-origin distance, velar thickness, pharyngeal depth, and velopharyngeal ratio. Significant predictors (p < .05) of maximum contraction velocity during velopharyngeal closure included mean extravelar length, intravelar length, LVP origin-to-origin distance, and velar thickness. Conclusions This study identified six velopharyngeal variables that predict LVP muscle function during real-time speech. These predictors should be considered among children and individuals with repaired cleft palate in future studies.

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.

Differences in the Tensor Veli Palatini Muscle and Hearing Status in Children With and Without 22q11.2 Deletion Syndrome

PURPOSE

To investigate the dimensions of the tensor veli palatini (TVP) muscle using high image resolution 3-dimensional magnetic resonance imaging (MRI) of the soft palate among children with normal velopharyngeal and craniofacial anatomy and to compare values to individuals with a diagnosis of 22q11.2 deletion syndrome (22q11DS). We also sought to determine whether there is a relationship between hypoplasia of the TVP and severity of middle ear dysfunction and hearing loss.

METHODS

Three-dimensional MRI were used to collect and analyze data obtained across 53 children between 4 and 12 years of age, including 40 children with normal velopharyngeal and craniofacial anatomy and 13 children with a diagnosis of 22q11.2 DS. Tensor veli palatini muscle length, thickness, and volume as well as bihamular distance were compared among participant groups.

RESULTS

A Welch's t-test revealed that the TVP in participants with 22q11DS is significantly shorter (P = .005, 17.3 vs 19.0 mm), thinner (P < .001, 1.1 vs 1.8 mm), and less voluminous (P < .001, 457.5 vs 667.3 mm³) than participants without 22q11DS. Participants with 22q11DS also had a greater (P = .006, 27.7 vs 24.7 mm) bihamular distance than participants without 22q11DS. There was an inverse relationship between TVP abnormalities noted above and the severity of audiologic and otologic histories.

CONCLUSION

The TVP muscle is substantially reduced in volume, length, and thickness in children with 22q11DS. These findings serve as preliminary support for the association of patient hearing and otologic severity and TVP dysmorphology.

A Dynamic Magnetic Resonance Imaging-Based Method to Examine In Vivo Levator Veli Palatini Muscle Function During Speech

Purpose The aim of this study was to develop a method able to quantify levator veli palatini (LVP) muscle shortening and contraction velocities using dynamic magnetic resonance imaging (MRI) throughout speech samples and relate these measurements to velopharyngeal portal dimensions. Method Six healthy adults (3 men and 3 women, M = 24.5 years) produced syllables representing 4 different manners of production during real-time dynamic MRI scans. We acquired an oblique-coronal slice of the velopharyngeal mechanism, which captured the length of the LVP, and manually segmented each frame. LVP shortening and muscle velocities were calculated from the acquired images. Results Using our method, we found that subjects demonstrated greater LVP shortening and higher maximum contraction velocities during fricative and plosive syllable production than during nasal or vowel syllable production. LVP shortening and maximum contraction velocity positively correlated with velopharyngeal port depth. Conclusions In vivo LVP function differs between manners of production, as expected, and an individual's velopharyngeal portal dimensions influence LVP function. These measures, contextualized with the force-length and force-velocity muscle relationships, provide new insight into LVP function. Future studies could use this method to investigate LVP function in healthy speakers and individuals with velopharyngeal dysfunction and how function relates to velopharyngeal anatomy.

Intravelar and Extravelar Portions of Soft Palate Muscles in Velic Constrictions: A Three-Dimensional Modeling Study

Purpose This study predicts and simulates the function and relative contributions of the intravelar and extravelar portions of the levator veli palatini (LVP) and palatoglossus (PG) muscles in velic constrictions. Method A finite element-based model of the 3-dimensional upper airway structures (palate, pharynx, tongue, jaw, maxilla) was implemented, with LVP and PG divided into intravelar and extravelar portions. Simulations were run to investigate the contributions of these muscles in velopharyngeal port (VPP) closure and constriction of the oropharyngeal isthmus (OPI). Results Simulations reveal that the extravelar portion of LVP, though crucial for lifting the palate, is not sufficient to effect VPP closure. Specifically, the characteristic "bulge" appearing in the posterior soft palate during VPP closure ( Pigott, 1969 ; Serrurier & Badin, 2008 ) is found to result from activation of the intravelar portion of LVP. Likewise, the intravelar portion of posterior PG is crucial in bending the "veil" or "traverse" ( Gick, Francis, Klenin, Mizrahi, & Tom, 2013 ) of the velum anteriorly to produce uvular constrictions of the OPI ( Gick et al., 2014 ). Conclusions Simulations support the view that intravelar LVP and PG play significant roles in VPP and OPI constrictions.

Morphology of the Musculus Uvulae In Vivo Using MRI and 3D Modeling Among Adults With Normal Anatomy and Preliminary Comparisons to Cleft Palate Anatomy

PURPOSE

To investigate the musculus uvulae morphology in vivo in adults with normal velopharyngeal anatomy and to examine sex and race effects on the muscle morphology. We also sought to provide a preliminary comparison of musculus uvulae morphology in adults with normal velopharyngeal anatomy to adults with repaired cleft palate.

METHODS

Three-dimensional magnetic resonance imaging data and Amira 5.5 Visualization Modeling software were used to evaluate the musculus uvulae in 70 participants without cleft palate and 6 participants with cleft palate. Muscle length, thickness, width, and volume were compared among participant groups.

RESULTS

Analysis of covariance analysis did not yield statistically significant differences in musculus uvulae length, thickness, width, or volume by race or sex among participants without cleft palate when the effect of body size was accounted for. Two-sample t test revealed that the musculus uvulae in participants with repaired cleft palate is significantly shorter (P = .008, 13.65 mm vs 16.07 mm) and has less volume (P = .002, 51.08 mm³ vs 97.62 mm³) than participants without cleft palate.

CONCLUSION

In adults with normal velopharyngeal anatomy, the musculus uvulae is a cylindrical oblong-shaped muscle lying on the nasal surface of the soft palate, with its greatest bulk located just nasal to the levator veli palatini muscle sling. In participants with repaired cleft palate, the musculus uvulae is substantially reduced in volume. This diminished muscle bulk located just at the point where the palate contacts the posterior pharyngeal wall may contribute to velopharyngeal insufficiency in children with repaired cleft palate.

Anatomical Significance of the Spatial Distribution of the Palatopharyngeus With Regard to Velopharyngeal Closure

OBJECTIVE

Coordination of the various soft palate and pharyngeal muscles should be considered while evaluating velopharyngeal closure. However, it remains unclear whether different muscle bundles have specific functions during velopharyngeal closure. We macroscopically and microscopically examined these muscles in detail and particularly clarified the morphology of the palatopharyngeus (PP) in velopharyngeal closure.

DESIGN

Forty halves of 21 heads from Japanese cadavers (average: 83.9 years) were used for analysis; 37 halves of 19 heads were macroscopically examined and 3 halves of 2 heads were histologically examined.

RESULTS

The PP consisted of muscle bundles originating from the superior and inferior surfaces of the palatine aponeurosis. The most superior part of the superior constrictor (SC) and most lateral part of PP on the palatine aponeurosis initially ran in parallel and subsequently, in superoposterior and inferoposterior directions, respectively. The PP appeared as a single continuous sheet that was radially spread as a whole. Its medial margins, located superior and inferior to the aponeurosis, formed a fold that established the palatopharyngeal arch. The stylopharyngeus (StP) adjoined the base of this arch.

CONCLUSIONS

Since PP consisted of muscle bundles running in various directions, various functions of these bundles should be considered during velopharyngeal closure. The PP can function as a sphincter with SC and as an elevator with StP. In addition, PP forms the medial protrusion in collaboration with StP and SC. Thus, PP plays an important role in velopharyngeal closure with the coordination of various muscles.

Evaluating the Accuracy of Using at Rest Images to Determine the Height of Velopharyngeal Closure

Prior to performing secondary surgeries, lateral cephalograms have been used during phonation to evaluate the point of attempted velopharyngeal contact along the posterior pharyngeal wall relative to the palatal plane and the first cervical vertebra. The ability to quantify the height of velopharyngeal closure is an important aspect of planning corrective surgeries for velopharyngeal dysfunction. However, issues with patient compliance during the imaging process can present difficulties for obtaining adequate preoperative imaging data. The purpose of this study was to assess if the height of velopharyngeal closure can be accurately estimated and quantified from at rest images. Results demonstrate that the height of velopharyngeal closure above C1 can be accurately quantified using at rest images in children with cleft palate. No statistically significant difference was found between the measures obtained at rest or during sustained phonation images (P = 0.573). Thus, quantitative measures from at rest images can aid in the preoperative planning process by providing surgeons with a numeric distance for tissue insertion along the posterior pharyngeal wall above C1. This distance is correlated to the height of velopharyngeal closure and successfully placing tissue at this height is likely tied to improved postoperative speech outcomes.

Structural Changes Following Velopharyngeal Resistance Training (Continuous Positive Airway Pressure Therapy): A Preliminary Report

OBJECTIVE

To evaluate the feasibility/effectiveness of using magnetic resonance imaging (MRI) to document velopharyngeal (VP) structural changes induced by continuous positive airway pressure (CPAP) therapy.

OUTCOME MEASURES

Changes in velar length and thickness, levator veli palatini (LVP) length and thickness, velar volume, and intravelar muscular proportion along the course of CPAP therapy participation (Pre-CPAP, Post-CPAP, and withdrawal).

RESULTS

Velar and LVP lengths remained nearly the same, with the median changes (Δ) less than 0.6%, across repeated conditions. Although varying in magnitudes of change, median velar volume (Δ4%), velar thickness (Δ20%), LVP thickness (Δ17%), and intravelar muscular proportion (Δ10%) illustrated a consistent pattern of increases following the 8-week CPAP therapy. These VP structural measurements slightly decreased but remained above the pretraining condition after 8-week detraining.

CONCLUSIONS

This report successfully demonstrated that MRI is a viable tool to document CPAP therapy-induced VP structural changes while providing preliminary empirical data.

Morphology of the Levator Veli Palatini Muscle in Adults With Repaired Cleft Palate

The purpose of this study was to examine differences in levator veli palatini (levator) morphology between adults with repaired cleft palate and adults with noncleft anatomy. Fifteen adult participants (10 with noncleft anatomy, 5 with repaired cleft palate) underwent 3-dimensional (3D) static magnetic resonance imaging (MRI). Image analyses included measures of total muscle volume and the circumference and diameter at 6 points along the length of the muscle. Differences between groups were analyzed using independent sample Mann-Whitney U tests (α < 0.05). Significant differences between groups were noted for measures of muscle volume, circumference at the origin and midline, anterior-posterior diameter at the origin and midline, and superior-inferior diameter at the point of insertion into the velum and midline. Differences in measures at other points along the levator muscle belly were not statistically significant. Limited sample size and gender differences may have impacted statistical findings. Overall, the levator muscle in adults with repaired cleft palate is significantly different than that of adults with noncleft anatomy. This study demonstrates the successful implementation of a method for 3D analysis of velopharyngeal (VP) musculature with potential clinical utility given continued technological advancements in MRI. Continued evaluation of pre- and postsurgical anatomy and short- and long-term outcomes may contribute to a better understanding of the effects of various types of palatoplasties on levator structure, which is important to VP function for speech.

Differences in the Tensor Veli Palatini Between Adults With and Without Cleft Palate Using High-Resolution 3-Dimensional Magnetic Resonance Imaging

OBJECTIVE

To investigate the dimensions of the tensor veli palatini (TVP) muscle in adults with and without cleft palate.

DESIGN

Prospective study.

PARTICIPANTS

There were a total of 14 adult participants, 8 noncleft and 6 with cleft palate.

METHODS

Analysis and comparison of the TVP muscle and surrounding structures was completed using 3D MRI data and Amira 5.5 Visualization Modeling software. TVP muscle volume, hamular process distance, mucosal thickness, TVP muscle length, and TVP muscle diameter were used for comparison between participant groups based upon previous research methods.

RESULTS

Mann-Whitney U tests revealed a significantly smaller ( U < .001, P = .002) TVP muscle volume in the cleft palate group (median = 536.22 mm³) compared to individuals in the non-cleft palate group (median = 895.19 mm³). The TVP muscle was also significantly shorter ( U = 1.00, P = .003) in the cleft palate group (median = 18.04 mm) versus the non-cleft palate (median = 21.18 mm). No significant differences were noted for the other measured parameters.

CONCLUSION

Significant differences in the TVP muscle volume and length among the noncleft participants found in this study may insights into the reported increased incidence of otitis media with effusion (OME) seen in the cleft population. Results from this study contribute to our understanding of the underlying anatomic differences among individuals with cleft palate.

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.

Clinical Significance of the Levator Veli Palatini Muscle in Velocardiofacial Syndrome Patients

Background:

Anatomical variation and deficits of velocardiofacial syndrome patients are related to unsatisfactory treatment results in surgical correction of speech abnormalities. The main purpose of the article is to investigate the clinical significance of thinned levator veli palatini muscle in VCFS patients.

Methods:

The authors reviewed medical records of all children with velocardiofacial syndrome who received pharyngeal flap surgery between March 2007 and September 2015. Data including thickness of levator veli palatini in magnetic resonance examination; preoperative velopharyngeal gap size from nasoendoscopy; and preoperative and postoperative speech outcomes were collected.

Results:

Total of 36 velocardiofacial syndrome patients with preoperative objective data and postoperative speech outcomes were identified. Preoperative velopharyngeal gap showed significant correlation with thickness of levator veli palatini (correlation coefficient: 0.297/0.397, P = .02/.03) and gap size showed correlation with postoperative speech improvement (0.347/0.413, P = .04/.02). However, muscle thickness showed no correlation with speech outcomes (0.046/0.037, P = .77/.86).

Conclusion:

Thinned levator veli palatini muscle in velocardiofacial syndrome patients are related to widened velopharyngeal gap and production of hypernasal speech, and can give negative impact on postoperative surgical outcome of pharyngeal flap surgery.

Morphological and molecular comparisons between tibialis anterior muscle and levator veli palatini muscle: A preliminary study on their augmentation potential

Tibialis anterior (TA) muscle and other somite-derived limb muscles remain the prototype in skeletal muscle study. The majority of head muscles, however, develop from branchial arches and maintain a number of heterogeneities in comparison with their limb counterparts. Levator veli palatini (LVP) muscle is a deep-located head muscle responsible for breathing, swallowing and speech, and is central to cleft palate surgery, yet lacks morphological and molecular investigation. In the present study, multiscale in vivo analyses were performed to compare TA and LVP muscle in terms of their myofiber composition, in-situ stem cell population and augmentation potential. TA muscle was identified to be primarily composed of type 2B myofibers while LVP muscle primarily consisted of type 2A and 2X myofibers. In addition, LVP muscle maintained a higher percentage of centrally-nucleated myofibers and a greater population of satellite cells. Notably, TA and LVP muscle responded to exogenous Wnt7a stimulus in different ways. Three weeks after Wnt7a administration, TA muscle exhibited an increase in myofiber number and a decrease in myofiber size, while LVP muscle demonstrated no significant changes in myofiber number or myofiber size. These results suggested that LVP muscle exhibits obvious differences in comparison with TA muscle. Therefore, knowledge acquired from TA muscle studies requires further testing before being applied to LVP muscle.

Contributions of the Musculus Uvulae to Velopharyngeal Closure Quantified With a 3-Dimensional Multimuscle Computational Model

The convexity of the dorsal surface of the velum is critical for normal velopharyngeal (VP) function and is largely attributed to the levator veli palatini (LVP) and musculus uvulae (MU). Studies have correlated a concave or flat nasal velar surface to symptoms of VP dysfunction including hypernasality and nasal air emission. In the context of surgical repair of cleft palates, the MU has been given relatively little attention in the literature compared with the larger LVP. A greater understanding of the mechanics of the MU will provide insight into understanding the influence of a dysmorphic MU, as seen in cleft palate, as it relates to VP function. The purpose of this study was to quantify the contributions of the MU to VP closure in a computational model. We created a novel 3-dimensional (3D) finite element model of the VP mechanism from magnetic resonance imaging data collected from an individual with healthy noncleft VP anatomy. The model components included the velum, posterior pharyngeal wall (PPW), LVP, and MU. Simulations were based on the muscle and soft tissue mechanical properties from the literature. We found that, similar to previous hypotheses, the MU acts as (i) a space-occupying structure and (ii) a velar extensor. As a space-occupying structure, the MU helps to nearly triple the midline VP contact length. As a velar extensor, the MU acting alone without the LVP decreases the VP distance 62%. Furthermore, activation of the MU decreases the LVP activation required for closure almost 3-fold, from 20% (without MU) to 8% (with MU). Our study suggests that any possible salvaging and anatomical reconstruction of viable MU tissue in a cleft patient may improve VP closure due to its mechanical function. In the absence or dysfunction of MU tissue, implantation of autologous or engineered tissues at the velar midline, as a possible substitute for the MU, may produce a geometric convexity more favorable to VP closure. In the future, more complex models will provide further insight into optimal surgical reconstruction of the VP musculature in normal and cleft palate populations.

Normative Velopharyngeal Data in Infants: Implications for Treatment of Cleft Palate

Identifying normative data related to velopharyngeal muscles and structures may have clinical significance for infants born with cleft palate, especially as they relate to selection of surgical intervention and postsurgical outcomes. Previous studies suggest that patients whose anatomy postsurgically is dissimilar to that of their normative counterparts are at risk for hypernasal speech. However, studies have not documented what constitutes "normal" anatomy for the clinically relevant population-that is, the infant population. The purpose of this study is to examine a magnetic resonance imaging database (n = 29) related to normative velopharyngeal structures and provide a preliminary comparison to 2 selected patients with repaired cleft palate. Twenty-nine healthy infants between 9 and 23 months of age (mean = 15.2 months) with normal craniofacial and velopharyngeal anatomy were recruited to participate in this study. Normative data were compared to 2 infants with repaired cleft palate between 13 and 15 months of age (mean = 14 months). Quantitative craniometric and velopharyngeal measures from the sagittal and oblique coronal image planes were collected. Variables of interest included: levator muscle, velar, and craniometric measures. Females demonstrated significantly larger intravelar segments compared with males. White infants demonstrated significantly larger levator muscles compared to non-white infants. Infants with repaired cleft palate demonstrated increased overall levator muscle length and levator extravelar length compared with infants with normal velopharyngeal anatomy.Data from the present study provide a normative database for future investigators to utilize as a comparative tool when evaluating infants with normal and abnormal velopharyngeal anatomy.

Age-Related Changes Between the Level of Velopharyngeal Closure and the Cervical Spine

The primary focus of this study was to assess age-related changes in the vertical distance of the estimated level of velopharyngeal closure in relation to a prominent landmark of the cervical spine: the anterior tubercle of cervical vertebra 1 (C1). Midsagittal anatomic magnetic resonance images were examined across 51 participants with normal head and neck anatomy between 4 and 17 years of age. Results indicate that age is a strong predictor (P = 0.002) of the vertical distance between the level of velopharyngeal closure relative to C1. Specifically, as age increases, the vertical distance between the palatal plane and C1 becomes greater resulting in the level of velopharyngeal closure being located higher above C1 (range 4.88-10.55 mm). Results of this study provide insights into the clinical usefulness of using C1 as a surgical landmark for placement of pharyngoplasties in children with repaired cleft palate and persistent hypernasal speech. Clinical implications and future directions are discussed.

Racial Variations in Velopharyngeal and Craniometric Morphology in Children: An Imaging Study

PURPOSE

The purpose of this study is to examine craniometric and velopharyngeal anatomy among young children (4-8 years of age) with normal anatomy across Black and White racial groups.

METHOD

Thirty-two healthy children (16 White and 16 Black) with normal velopharyngeal anatomy participated and successfully completed the magnetic resonance imaging scans. Measurements included 11 craniofacial and 9 velopharyngeal measures.

RESULTS

Two-way analysis of covariance was used to determine the effects of race and sex on velopharyngeal measures and all craniometric measures except head circumference. Head circumference was included as a covariate to control for overall cranial size. Sex did not have a significant effect on any of the craniometric measures. Significant racial differences were demonstrated for face height. A significant race effect was also observed for mean velar length, velar thickness, and velopharyngeal ratio.

CONCLUSION

The present study provides separate craniofacial and velopharyngeal values for young Black and White children. Data from this study can be used to examine morphological variations with respect to race and sex.

A computational model of velopharyngeal closure for simulating cleft palate repair

The levator veli palatini (LVP) muscle has long been recognized as the muscle that contributes most to velopharyngeal (VP) closure and is therefore of principal importance for restoring normal speech in patients with a cleft palate. Different surgical reconstructive procedures can utilize varying degrees of LVP overlap, and this study developed a new finite-element model of VP closure designed to understand the biomechanical effects of LVP overlap. A three-dimensional finite-element model was created from adult anatomical dimensions and parameters taken from the literature. Velopharyngeal function was simulated and compared with experimental measurements of VP closure force from a previous study. Varying degrees of overlap and separation of the LVP were simulated, and the corresponding closure force was calculated. The computational model compares favorably with the experimental measurements of closure force from the literature. Furthermore, the model predicts that there is an optimal level of overlap that maximizes the potential for the LVP to generate closure force. The model predicts that achieving optimal overlap can increase closure force up to roughly 100% when compared with too little or too much overlap. The results of using this new model of VP closure suggest that optimizing LVP overlap may produce improved surgical outcomes due to the intrinsic properties of muscle. Future work will compare these model predictions with clinical observations and provide further insights into optimal cleft palate repair and other craniofacial surgeries.

A Computational Model Quantifies the Effect of Anatomical Variability on Velopharyngeal Function

PURPOSE

This study predicted the effects of velopharyngeal (VP) anatomical parameters on VP function to provide a greater understanding of speech mechanics and aid in the treatment of speech disorders.

METHOD

We created a computational model of the VP mechanism using dimensions obtained from magnetic resonance imaging measurements of 10 healthy adults. The model components included the levator veli palatini (LVP), the velum, and the posterior pharyngeal wall, and the simulations were based on material parameters from the literature. The outcome metrics were the VP closure force and LVP muscle activation required to achieve VP closure.

RESULTS

Our average model compared favorably with experimental data from the literature. Simulations of 1,000 random anatomies reflected the large variability in closure forces observed experimentally. VP distance had the greatest effect on both outcome metrics when considering the observed anatomic variability. Other anatomical parameters were ranked by their predicted influences on the outcome metrics.

CONCLUSIONS

Our results support the implication that interventions for VP dysfunction that decrease anterior to posterior VP portal distance, increase velar length, and/or increase LVP cross-sectional area may be very effective. Future modeling studies will help to further our understanding of speech mechanics and optimize treatment of speech disorders.

Differences in Velopharyngeal Structure during Speech among Asians Revealed by 3-Tesla Magnetic Resonance Imaging Movie Mode

OBJECTIVE

Different bony structures can affect the function of the velopharyngeal muscles. Asian populations differ morphologically, including the morphologies of their bony structures. The purpose of this study was to compare the velopharyngeal structures during speech in two Asian populations: Japanese and Thai.

METHODS

Ten healthy Japanese and Thai females (five each) were evaluated with a 3-Tesla (3 T) magnetic resonance imaging (MRI) scanner while they produced vowel-consonant-vowel syllable (/asa/). A gradient-echo sequence, fast low-angle shot with segmented cine and parallel imaging technique was used to obtain sagittal images of the velopharyngeal structures.

RESULTS

MRI was carried out in real time during speech production, allowing investigations of the time-to-time changes in the velopharyngeal structures. Thai subjects had a significantly longer hard palate and produced shorter consonant than Japanese subjects. The velum of the Thai participants showed significant thickening during consonant production and their retroglossal space was significantly wider at rest, whereas the dimensional change during task performance was similar in the two populations.

CONCLUSIONS

The 3 T MRI movie method can be used to investigate velopharyngeal function and diagnose velopharyngeal insufficiency. The racial differences may include differences in skeletal patterns and soft-tissue morphology that result in functional differences for the affected structures.

Impact of orthodontic appliances on the quality of craniofacial anatomical magnetic resonance imaging and real-time speech imaging

AIMS

The aim of this work was to investigate the effects of commonly used orthodontic appliances on the magnetic resonance (MR) image quality of the craniofacial region, with special interest in the soft palate and velopharyngeal wall using real-time speech imaging sequences and anatomical imaging of the temporomandibular joints (TMJ) and pituitaries.

METHODS

Common orthodontic appliances were studied on 1.5 T scanner using standard spin and gradient echo sequences (based on the American Society for Testing and Materials standard test method) and sequences previously applied for high-resolution anatomical and dynamic real-time imaging during speech. Images were evaluated for the presence and size of artefacts.

RESULTS

Metallic orthodontic appliances had different effects on image quality. The most extensive individual effects were associated with the presence of stainless steel archwire, particularly if combined with stainless steel brackets and stainless steel molar bands. With those appliances, diagnostic quality of magnetic resonance imaging speech and palate images will be most likely severely degraded, or speech imaging and imaging of pituitaries and TMJ will be not possible. All non-metallic, non-metallic with Ni/Cr reinforcement or Ni/Ti alloys appliances were of little concern.

LIMITATIONS

The results in the study are only valid at 1.5 T and for the sequences and devices used and cannot necessarily be extrapolated to all sequences and devices. Furthermore, both geometry and size of some appliances are subject dependent, and consequently, the effects on the image quality can vary between subjects. Therefore, the results presented in this article should be treated as a guide when assessing the risks of image quality degradation rather than an absolute evaluation of possible artefacts.

CONCLUSIONS

Appliances manufactured from stainless steel cause extensive artefacts, which may render image non-diagnostic. The presence and type of orthodontic appliances should be always included in the patient's screening, so the risks of artefacts can be assessed prior to imaging. Although the risks to patients with fixed orthodontic appliances at 1.5 T MR scanners are low, their secure attachment should be confirmed prior to the examination.

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.

Magnetic Resonance Imaging of Velar Muscle Tissue Distribution in Healthy Adults

OBJECTIVES

To examine muscle tissue distribution along the length of the velum in living individuals using magnetic resonance imaging (MRI).

DESIGN

Using the three-dimensional MRI data acquired from 10 normal white adults, two area measures including the muscular area and the total velar area were obtained from 10 oblique slices running perpendicular to velar length. A polynomial regression analysis was performed where the proportion of the muscular to the total velar area was regressed on the slice numbers running along the length of the velum.

RESULTS

The proportion of the muscular to total velar area increased from the anterior section of the velum, reaching a maximum (33.24%) in the midsection, and decreasing in the posterior section of the velum. A third-order (cubic) polynomial function that best illustrated the proportional data (R(2) = .47) was derived.

CONCLUSIONS

The present study demonstrated that MRI is a viable tool to examine the muscle tissue distribution of the velum in living individuals. Although the overall pattern in the muscle tissue distribution of the healthy velum was similar to that reported in previous literature based on cadaver specimens, the participants in the present study appeared to have greater muscular proportion of the velum. The muscular proportion measure derived from the healthy living individuals can be used as an additional parameter accounting for sufficient intravelar muscle mass for future studies.

Sexual dimorphism of the levator veli palatini muscle: an imaging study

Objective : Magnetic resonance imaging studies of the levator veli palatini muscle have used small numbers of subjects and have not consistently controlled for sex, race, or age. The purpose of this study was to conduct a structural assessment using a large homogeneous sample to examine the sex differences in the levator muscle morphology. Methods : Thirty white adult subjects (15 men and 15 women) were imaged using a 3 Tesla MRI system. A high-resolution SPACE (sampling perfection with application-optimized contrasts using different flip-angle evolution) sequence was used to acquire images of the velopharyngeal anatomy. Levator muscle measurements were obtained. Results : Men displayed significantly greater levator extravelar segment length (P = .003), levator intravelar segment muscle length (P < .001), greater distance between levator insertion points (P < .001), and greater angles of origin (P = .008) compared with women. There was no statistically significant variation between men and women in the distance between points of origin at the base of the skull. Conclusions : This study provides normative data to improve understanding of levator dysmorphology such as that in cleft palate muscle anatomy. Results of the study demonstrate significant differences between white men and women across several levator muscle measures. Variations in the relative size of the cranium or height of the individual were not proportionate to the variations observed in the levator muscle.

Speech MRI: morphology and function

Magnetic Resonance Imaging (MRI) plays an increasing role in the study of speech. This article reviews the MRI literature of anatomical imaging, imaging for acoustic modelling and dynamic imaging. It describes existing imaging techniques attempting to meet the challenges of imaging the upper airway during speech and examines the remaining hurdles and future research directions.

Cleft Palate-Craniofacial Journal 50th anniversary editorial board commentary: anatomy, basic sciences, and genetics--then and now

To celebrate the 50th year of the Cleft Palate-Craniofacial Journal we look back to where we started in 1964 and where we are now, and we speculate about directions for the future in a "Then and Now" editorial series. This editorial examines changing trends and perspectives in anatomical, basic science, and genetic studies published in this 50-year interval. In volume 1 there were 45 total papers, seven (16%) of which were peer-reviewed basic science and genetic articles published: four in anatomy, three in craniofacial biology, and none in genetics. In contrast, in volume 50, of 113 articles there were 47 (42%) peer-reviewed basic science and genetic articles published: 30 in anatomy, five in craniofacial biology, and 12 in genetics. Topical analysis of published manuscripts then and now reveal that similar topics in anatomy and craniofacial biology are still being researched today (e.g., phenotypic variability, optimal timing of surgery, presurgical orthopedics, bone grafting); whereas, most of the more recent papers use advanced technology to address old questions. In contrast, genetic publications have clearly increased in frequency during the last 50 years, which parallels advances in the field during this time. However, all of us have noticed that the more "cutting-edge" papers in these areas are not being submitted for publication to the journal, but instead to discipline-specific journals. Concerted efforts are therefore indicated to attract and publish these cutting-edge papers in order to keep the Cleft Palate-Craniofacial Journal in the forefront of orofacial cleft and craniofacial anomaly research and to provide a valuable service to American Cleft Palate-Craniofacial Association members.

Using MRI for assessing velopharyngeal structures and function

OBJECTIVE

Direct visualization of the velopharynx and, in particular, the levator muscle is particularly important in the assessment of velopharyngeal function and normal speech production. The purpose of this study is to demonstrate the development of a static and dynamic magnetic resonance imaging protocol for evaluation of velopharyngeal structures and function.

METHODS

A high-resolution, T2-weighted turbo-spin-echo three-dimensional anatomical scan (sampling perfection with application optimized contrasts using different flip angle evolution) was used to acquire a large field of view covering the velopharyngeal anatomy. Dynamic speech assessment was obtained using a fast-gradient echo, fast low-angle shot, multi-shot spiral technique to acquire 15.8 frames per second (FPS) of the sagittal and oblique coronal image planes.

RESULTS

Using a three-dimensional data set, as opposed to two-dimensional data, the full contour of the levator muscle can be appreciated. Dynamic images were obtained at 15.8 FPS in the sagittal and oblique coronal planes, enabling visualization of the movements of the velum, posterior pharyngeal wall, lateral pharyngeal walls, and levator muscle during speech.

CONCLUSIONS

A three-dimensional magnetic resonance imaging sequence, such as that used in the present study, may provide better analyses and more precise measurements. A dynamic fast low-angle shot sequence allows for visualization of the levator muscle and the velum during speech at a high image rate. This protocol could have a significant impact in improving the process of visualizing pathology and promoting clinical treatment plans for individuals born with cleft lip and palate.

Adaptive averaging applied to dynamic imaging of the soft palate

Achieving sufficient temporal and spatial resolution with adequate signal-to-noise ratio (SNR) in dynamic soft palate imaging is challenging. Triggered acquisitions require repeated reproducible speech samples, and while real-time imaging is more reliable, it may lack SNR. Adaptive averaging was implemented to improve SNR in nongated imaging during repetition of a speech task. Similar images were identified using localized cross-correlation before averaging. Adaptive averaging was applied to the soft palate region of images from six volunteers and one patient acquired with various sequences. In volunteers, soft palate SNR increased by 53 ± 17% with four averages. The additional SNR was used to enable reduced slice thickness in two example subjects. Adaptive averaging was also compared to pseudotriggered images in one example and, in another, it was applied to an unrepeated speech task. In a patient with a repaired cleft palate, the technique was used to demonstrate residual velopharyngeal insufficiency. This initial work demonstrates that increased temporal or spatial resolution may be traded for reduced SNR, which can be recovered using adaptive averaging. This will be a valuable tool in assessing velopharyngeal function, particularly in pediatric patients where cooperation may make gated studies difficult or when their head sizes require increased spatial resolution while maintaining temporal resolution.