Assessment of the Velopharyngeal Mechanism at Rest and During Speech in Children With 22q11.2DS: A Cross-Sectional Study

OBJECTIVE

Velopharyngeal dysfunction (VPD) associated with 22q11.2 deletion syndrome (22q11.2DS) has a complex etiology. This study had 3 aims: (1) assess differences in velopharyngeal and levator muscle configuration during rest versus sustained speech production (2) compare differences in velopharyngeal changes between children with and without 22q11.2DS (3) examine the relationship between adenoid thickness, pharyngeal depth, and velopharyngeal changes.

DESIGN

Cross-sectional.

METHODS

A total of 22 participants, 11 with 22q11.2DS and 11 controls with normal speech and velopharyngeal anatomy (ages 4-12 years), underwent nonsedated MRI at rest and during sustained /i/. Differences in velar and levator muscle contraction across the 2 different conditions were analyzed, using matched paired t-tests. Mean differences across participant groups were examined. Correlation analyses were also conducted.

RESULTS

When comparing differences between rest and sustained phoneme production (aim 1), significant (P < .05) differences were noted for all velar and levator muscle variables. For differences in velopharyngeal changes between children with and without 22q11.2DS (aim 2), VP ratio and effective VP ratio were noted to be significantly different. Pharyngeal depth and adenoid thickness were correlated with velar and levator muscle change measures and ratios (aim 3).

CONCLUSION

Results from this study provide quantitative in vivo measurements of the contracted levator muscle and velum in young children with 22q11.2DS. Results demonstrated that VP ratio and EVP ratio are significantly different between children with and without 22q11.2DS and that pharyngeal depth is a strong clinical determinant of VPD in children with 22q11.2DS.

Development of the lamprey velum and implications for the evolution of the vertebrate jaw

BACKGROUND

The vertebrate jaw is thought to have evolved through developmental modification of the mandibular arch. An extant jawless vertebrate, the lamprey, possesses a structure called "velum"-a mandibular arch derivative-in addition to the oral apparatus. This leads us to assess the velum's possible contribution to the evolution of jaws.

RESULTS

The velar muscles develop from progenitor cells distinct from those from which the oral muscles develop. In addition, the oral and velar regions originate from the different sub-population of the trigeminal neural crest cells (NCCs): the former region receives NCCs from the midbrain, whereas the latter region receives NCCs from the anterior hindbrain. The expression of patterning genes (eg, DlxA and MsxA) is activated at a later developmental stage in the velum compared to the oral region, and more importantly, in different cells from those in the oral region.

CONCLUSION

The lamprey mandibular arch consists of two developmental units: the anterior oral unit and the posterior velar unit. Because structural elements of the lamprey velum may be homologous to the jaw, the evolution of vertebrate jaws may have occurred by the velum being released from its functional roles in feeding or respiration in jawless vertebrates.

Application of radial GRAPPA techniques to single- and multislice dynamic speech MRI using a 16-channel neurovascular coil

PURPOSE

To investigate: (1) the feasibility of using through-time radial GeneRalized Autocalibrating Partially Parallel Acquisitions (rGRAPPA) and hybrid radial GRAPPA (h-rGRAPPA) in single- and multislice dynamic speech MRI; (2) whether single-slice dynamic speech MRI at a rate of 15 frames per second (fps) or higher and with adequate image quality can be achieved using these radial GRAPPA techniques.

METHODS

Seven healthy adult volunteers were imaged at 3T using a 16-channel neurovascular coil and 2 spoiled gradient echo sequences (radial trajectory, field of view = 192 × 192 mm² , acquired pixel size = 2.4 × 2.4 mm² ). One sequence imaged a single slice at 16.8 fps, the other imaged 2 interleaved slices at 7.8 fps per slice. Image sets were reconstructed using rGRAPPA and h-rGRAPPA, and their image quality was compared using the root mean square error, structural similarity index, and visual assessments.

RESULTS

Image quality deteriorated when fewer than 170 calibration frames were used in the rGRAPPA reconstruction. rGRAPPA image sets demonstrated: (1) in 97% of cases, a similar image quality to h-rGRAPPA image sets reconstructed using a k-space segment size of 4, (2) in 98% of cases, a better image quality than h-rGRAPPA image sets reconstructed using a k-space segment size of 32.

CONCLUSION

This study confirmed: (1) the feasibility of using rGRAPPA and h-rGRAPPA in single- and multislice dynamic speech MRI, (2) that single-slice speech imaging at a frame rate higher than 15 fps and with adequate image quality can be achieved using these radial GRAPPA techniques.

The ventilation mechanism of the Pacific hagfish Eptatretus stoutii

We made anatomical and physiological observations of the breathing mechanisms in Pacific hagfish Eptatretus stoutii, with measurements of nostril flow and pressure, mouth and pharyngo-cutaneous duct (PCD) pressure and velum and heart impedance and observations of dye flow patterns. Resting animals frequently exhibit spontaneous apnea. During normal breathing, water flow is continuous at a high rate (~125 ml kg^-1 min^-1 at 12°C) powered by a two-phase unidirectional pumping system with a fast suction pump (the velum, ~22 min^-1 ) for inhalation through the single nostril and a much slower force pump (gill pouches and PCD ~4.4 min^-1 ) for exhalation. The mouth joins the pharynx posterior to the velum and plays no role in ventilation at rest or during swimming. Increases in flow up to >400 ml kg^-1 min^-1 can be achieved by increases in both velum frequency and stroke volume and the ventilatory index (product of frequency x nostril pressure amplitude) provides a useful proxy for ventilatory flow rate. Two types of coughing (flow reversals) are described. During spontaneous swimming, ventilatory pressure and flow pulsatility becomes synchronised with rhythmic body undulations.

Does drug-induced sleep endoscopy predict surgical success in transoral robotic multilevel surgery in obstructive sleep apnea?

OBJECTIVES/HYPOTHESIS

The aim of this study was to determine if drug-induced sleep endoscopy (DISE) was predictive of success for patients undergoing transoral robotic surgery (TORS) and multilevel procedures for sleep apnea.

STUDY DESIGN

Retrospective case series of patients who underwent TORS surgery for sleep apnea METHODS: Before and after polysomnograms were analyzed to assess improvement, success, and cure. Improvement was defined as any decrease in apnea-hypopnea index (AHI), success as an AHI <20 with a decrease >50%, and cure as an AHI <5. DISE videos were scored using the NOHL (nose, oropharynx, hypopharynx, larynx) and VOTE (velum, oropharynx, tongue, epiglottis) classification systems.

RESULTS

One hundred one patients were available for analysis. Eighty-seven percent of patients had an improvement in their AHI. Fifty-one percent met criteria for success, whereas 17% were cured. The degree of collapse at individual NOHL and VOTE subsites as well as total additive scores did not predict improvement, success, or cure. Patients with no oropharyngeal lateral collapse in the VOTE classification system were more likely to improve following surgery (P = .001); however, this effect did not hold for success or cure. Multivariate analysis of DISE variables was not predictive of success.

CONCLUSIONS

In obstructive sleep apnea patients, there is a 51% success rate and a 17% cure rate. DISE, as scored by the NOHL and VOTE system, did not readily identify patients who would benefit most from surgery. Patients with lateral oropharyngeal collapse may be poorer candidates. Prospective, larger studies are required to further evaluate the use of DISE in predicting success following TORS.

LEVEL OF EVIDENCE

4 Laryngoscope, 127:971-976, 2017.

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.

Cytodifferentiation of hair cells during the development of a basal chordate

Tunicates are unique animals for studying the origin and evolution of vertebrates because they are considered vertebrates' closest living relatives and share the vertebrate body plan and many specific features. Both possess neural placodes, transient thickenings of the cranial ectoderm that give rise to various types of sensory cells, including axonless secondary mechanoreceptors. In vertebrates, these are represented by the hair cells of the inner ear and the lateral line, which have an apical apparatus typically bearing cilia and stereovilli. In tunicates, they are found in the coronal organ, which is a mechanoreceptor located at the base of the oral siphon along the border of the velum and tentacles and is formed of cells bearing a row of cilia and short microvilli. The coronal organ represents the best candidate homolog for the vertebrate lateral line. To further understand the evolution of secondary sensory cells, we analysed the development and cytodifferentiation of coronal cells in the tunicate ascidian Ciona intestinalis for the first time. Here, coronal sensory cells can be identified as early as larval metamorphosis, before tentacles form, as cells with short cilia and microvilli. Sensory cells gradually differentiate, acquiring hair cell features with microvilli containing actin and myosin VIIa; in the meantime, the associated supporting cells develop. The coronal organ grows throughout the animal's lifespan, accompanying the growth of the tentacle crown. Anti-phospho Histone H3 immunostaining indicates that both hair cells and supporting cells can proliferate. This finding contributes to the understanding of the evolution of secondary sensory cells, suggesting that both ancestral cell types were able to proliferate and that this property was progressively restricted to supporting cells in vertebrates and definitively lost in mammals.

Endoscopic anatomy of the velum interpositum: A sequential descriptive anatomical study

Background:

The velum interpositum and structures lying within and over it undergo morbid anatomical changes with hydrocephalus that have not been mentioned in the literature.

Objectives:

The aim of this article is to describe the diverse endoscopic anatomical findings for this surgically important region.

Materials and Methods:

One thousand five hundred and twenty cranial endoscopic procedures performed from September 1993 till March 2011 have been retrospectively reviewed. Anatomical `situm and covering layers have been reported in 40 cases.

Results:

The changes of the velum interpositum have four patterns. These are 1-Distraction mounting to disruption of layers, 2-Reverse in the normal curvature, 3-Reverse of the triangular shape with change in size, and 4-Cystic dilatation causing hydrocephalus.

Conclusion:

The velum interpositum and roof of the third ventricle are sites of changes associated with hydrocephalus that show specific patterns described in a sequential anatomical study.

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.

Secondary Male Sex Characteristics of Hoplolaimus galeatus

The secondary male sex characteristics of Hoplolaimus galeatus consisted of caudal alae, two independently retractable spicules and a gubernaculum with two bilobed titillae. The spicules were dimorphic, with the outer one possessing a velum. When both spicules were completely extruded, the only open orifice on the ventral surface of the posterior region was formed by the close association of these two appendages. In specimens where the inner spicule was slightly retracted, the velum almost completely surrounded the inner spicule. When the inner spicule was retracted further, the velum appeared to convolute, closing the orifice described above.