Computational analysis of a flapping uvula on aerodynamics and pharyngeal wall collapsibility in sleep apnea.

Studying the airflows and the resultant aerodynamic pressure/force in the pharyngeal airway is critical for understanding the pathophysiology of snoring and sleep apnea. In this work, an experiment-driven computational study was conducted to examine the aerodynamics in human pharyngeal airway. An anatomically accurate pharynx model associated with different uvula kinematics was reconstructed from human magnetic resonance image (MRI) and high-speed photography. An immersed-boundary-method (IBM)-based direct numerical simulation (DNS) flow solver was adopted to simulate the corresponding unsteady flows in all their complexity. Analyses were performed on vortex dynamics and pressure fluctuations in the pharyngeal airway and force oscillations on the pharyngeal wall under the influence of varying airway obstructions, uvula flapping mode, and uvula flapping frequencies. It was found the vortex formation, aerodynamic pressure, and pharyngeal wall force were significantly affected by the width of the pharyngeal airway. By contrast, the influences from the uvula flapping mode were insignificant when other parameters were similar. Fast Fourier transformation (FFT) and continuous wavelet transform (CWT) analysis of the pressure time history revealed the existence of higher order harmonics of base frequency with significant pressure amplitudes and energy intensities. It was also found the airway pressure and pharyngeal wall force oscillate more dramatically at higher uvula flapping frequencies, which tends to promote the collapse of pharyngeal wall and initiates sleep apnea.

Vowel Height Allophony and Dorsal Place Contrasts in Cochabamba Quechua.

This paper reports on the results of two studies investigating the role of allophony in cueing phonemic contrasts. In Cochabamba Quechua, the uvularvelar place distinction is often cued by additional differences in the height of the surrounding vowels. An acoustic study documents the lowering effect of a preceding tautomorphemic or a following heteromorphemic uvular on the high vowels /i u/. A discrimination study finds that vowel height is a significant cue to the velar-uvular place contrast. These findings support a view of contrasts as collections of distinguishing properties, as opposed to oppositions in a single distinctive feature.

Anatomical status of the human musculus uvulae and its functional implications.

In our ongoing series of anatomical studies to determine the three-dimensional architecture of the human velar muscles, we have previously reported on the palatopharyngeus. The present study deals with the musculus uvulae (MU), in which the positional relationships of its origin to the posterior nasal spine and the palatine aponeurosis, as well as the interrelation between its anatomical status and functions, have yet to be clarified. Macroscopic and microscopic examinations were performed on 25 and 2 cadavers, respectively. In the former, bilateral MUs and their adjacent structures were exposed mainly from the nasal aspect. In the latter, the soft palates embedded in paraffin were cut into frontal and sagittal sections and alternately processed with HE and Azan stains. The left and right MUs adjacent to each other were found to run longitudinally along the midline beneath the nasal aspect of velum. It was overlaid by glandular tissue that increased in amount as it coursed distally. After originating from the oral surface of palatine aponeurosis, it ran backward to cross above the sling formed by the levator veli palatini muscles of both sides and reached the tip of uvula with its muscle fibers intermingled with glandular tissue. Past studies have proposed three functions of MU to enhance the efficiency of velopharyngeal closure: space occupier, stiffness modifier, and velar extensor. All of the above-described anatomical characteristics of MU could be explained as being adapted for these functions. This implies that MU is actively responsible for maintaining the velopharyngeal closure efficiency.

Modeling the pharyngeal anatomical effects on breathing resistance and aerodynamically generated sound.

The objective of this study was to systematically assess the effects of pharyngeal anatomical details on breathing resistance and acoustic characteristics by means of computational modeling. A physiologically realistic nose-throat airway was reconstructed from medical images. Individual airway anatomy such as the uvula, pharynx, and larynx was then isolated for examination by gradually simplifying this image-based model geometry. Large eddy simulations with the FW-H acoustics model were used to simulate airflows and acoustic sound generation with constant flow inhalations in rigid-walled airway geometries. Results showed that pharyngeal anatomical details exerted a significant impact on breathing resistance and energy distribution of acoustic sound. The uvula constriction induced considerably increased levels of pressure drop and acoustic power in the pharynx, which could start and worsen snoring symptoms. Each source anatomy was observed to generate a unique spectrum with signature peak frequencies and energy distribution. Moreover, severe pharyngeal airway narrowing led to an upward shift of sound energy in the high-frequency range. Results indicated that computational aeroacoustic modeling appeared to be a practical tool to study breathing-related disorders. Specifically, high-frequency acoustic signals might disclose additional clues to the mechanism of apneic snoring and should be included in future acoustic studies.

Spatiotemporal properties of optic flow and vestibular tuning in the cerebellar nodulus and uvula.

Convergence of visual motion and vestibular information is essential for accurate spatial navigation. Such multisensory integration has been shown in cortex, e.g., the dorsal medial superior temporal (MSTd) and ventral intraparietal (VIP) areas, but not in the parieto-insular vestibular cortex (PIVC). Whether similar convergence occurs subcortically remains unknown. Many Purkinje cells in vermal lobules 10 (nodulus) and 9 (uvula) of the macaque cerebellum are tuned to vestibular translation stimuli, yet little is known about their visual motion responsiveness. Here we show the existence of translational optic flow-tuned Purkinje cells, found exclusively in the anterior part of the nodulus and ventral uvula, near the midline. Vestibular responses of Purkinje cells showed a remarkable similarity to those in MSTd (but not PIVC or VIP) neurons, in terms of both response latency and relative contributions of velocity, acceleration, and position components. In contrast, the spatiotemporal properties of optic flow responses differed from those in MSTd, and matched the vestibular properties of these neurons. Compared with MSTd, optic flow responses of Purkinje cells showed smaller velocity contributions and larger visual motion acceleration responses. The remarkable similarity between the nodulus/uvula and MSTd vestibular translation responsiveness suggests a functional coupling between the two areas for vestibular processing of self-motion information.

The velic traverse: an independent oral articulator?

Two speech functions have traditionally been ascribed to the velum: opening and closing the velopharyngeal port and providing a passive surface against which the tongue can produce oral constrictions. Contrary to this passive oral function, the present x-ray study finds that a substantial portion of the velum moves to constrict the oropharyngeal isthmus for French uvular /ʁ/. This substructure, designated the velic traverse, functions independently of the parts of the velum used for velopharyngeal port closure, thus acting as an oral articulator. An active velic traverse challenges methods for estimating vocal tract shapes based on tongue posture alone.

Bulbar signs in normal population.

BACKGROUND AND OBJECTIVES: There is lack of published data on bulbar signs among the healthy population. This study aims to determine the range of normality of bulbar signs particularly among the elderly. METHODS: Systemic examination of bulbar signs was carried out according to a predetermined protocol on a cohort of young and elderly healthy subjects. RESULTS: A total of 206 subjects were recruited in the study, 104 young adults with mean age of 20 years, and 102 elderly with mean age of 73 years. Uvula deviation was seen in 28 (26.9%) young subjects and 22 (21.6%) elderly. Irregular tongue border was seen in 17 subjects, unilateral in 4 subjects. Fourteen (6.8%) subjects had deviation on tongue protrusion. Occasional tremor of tongue on protrusion is common in both young and old. Persistent (severe) tongue tremor on protrusion was seen in 18.6% of the elderly, and 4.8% of the young. None of the subjects had tremor of tongue at rest. In gag reflex, absence of gagging response was common in elderly, seen in two thirds of the subjects on stimulation of the posterior pharyngeal wall. However, all the subjects had uvular movement. Habituation or suppression of gagging response was seen in close to 90% of young males. CONCLUSION: There is wide range of normality in bulbar signs in normal population, particularly among the elderly.

Swallowing reflex: analysis of the efficiency of different stimuli on healthy young individuals.

BACKGROUND: the absence or delay of the swallowing reflex is considered a significant sign of dysphagia. Therefore, the therapy traditionally applied to these cases consists in increasing the intra-oral input through cold touches (0 or 00 larynx mirror) on the inferior portion of the inferior third of the palatoglossus arch. AIM: to identify in healthy young individuals which oropharyngeal regions are more sensitive and which stimulus is more efficient in triggering the swallowing reflex. METHODS: the swallowing reflex was analyzed based on the following stimuli: spatula, cold 00 larynx mirror, gauze embedded in cold water wrapped onto spatula and frozen moist gauze wrapped onto spatula; touching the palatoglossus arch in both its inferior and superior portions, the palatine tonsils, the base of the tongue and the uvula in 65 healthy young individuals. RESULTS: the swallowing reflex was not triggered in most of the participants when touching different oropharyngeal regions with different stimuli. This result was statistically significant. When present, the most efficient stimuli were cold 00 larynx mirror (28.6%) and frozen moist gauze wrapped onto spatula (27.3%). Concerning the oropharynx, the uvula (29.6%), the palatine tonsils (26.7%), the superior (25%) and inferior (21.2%) palatoglossi arches and the base of tongue (25%) were most sensitive to the applied stimuli. CONCLUSION: when the swallowing reflex was present, the uvula, the palatoglossi arches and the palatine tonsils were the most sensitive regions to trigger this reflex, and the most efficient stimuli to trigger swallowing were the cold 00 larynx mirror and the frozen moist gauze wrapped onto spatula.

Reflexo da deglutição: análise sobre eficiência de diferentes estímulos em jovens sadios / Swallowing reflex: analysis of the efficiency of different stimuli on healthy young individuals

TEMA: a ausência ou atraso do reflexo da deglutição é considerado um sinal significativo de disfagia. Assim, a terapia tradicionalmente empregada nesses casos consiste em aumentar o input intra-oral por meio de toques gelados (espelho laríngeo 0 ou 00) no terço inferior do arco palatoglosso, porção inferior. OBJETIVOS: identificar, em indivíduos jovens e sadios, quais regiões da orofaringe são mais sensíveis para desencadear o reflexo da deglutição e qual estímulo é mais eficiente. MÉTODO: O reflexo da deglutição foi investigado a partir dos estímulos: espátula, espelho laríngeo 00 gelado, espátula envolta em gaze com água gelada e espátula envolta em gaze umedecida congelada, tocando-se o arco palatoglosso em suas porções inferior e superior, as tonsilas palatinas, a base de língua e a úvula em 65 indivíduos jovens e sadios. RESULTADOS: o reflexo da deglutição não foi desencadeado na maioria dos participantes quando tocado com diferentes estímulos e locais da orofaringe, sendo esta estatisticamente significante. Quando presente, os estímulos mais eficientes foram o espelho laríngeo 00 (28,6 por cento) e a espátula envolta com gaze congelada (27,3 por cento). Quanto à região da orofaringe, a úvula (29,6 por cento), as tonsilas palatinas (26,7 por cento), os arcos palatoglossos região superior (25 por cento) e inferior (21,2 por cento) e base de língua (25 por cento) foram sensíveis aos estímulos. CONCLUSÃO: quando presente o reflexo da deglutição, a úvula, os arcos palatoglossos e as tonsilas palatinas foram as regiões mais sensíveis para desencadeá-lo e o estímulo mais eficiente, dentre os selecionados, foram o espelho laríngeo gelado e a espátula envolta em gaze umedecida congelada.

BACKGROUND: the absence or delay of the swallowing reflex is considered a significant sign of dysphagia. Therefore, the therapy traditionally applied to these cases consists in increasing the intra-oral input through cold touches (0 or 00 larynx mirror) on the inferior portion of the inferior third of the palatoglossus arch. AIM: to identify in healthy young individuals which oropharyngeal regions are more sensitive and which stimulus is more efficient in triggering the swallowing reflex. METHODS: the swallowing reflex was analyzed based on the following stimuli: spatula, cold 00 larynx mirror, gauze embedded in cold water wrapped onto spatula and frozen moist gauze wrapped onto spatula; touching the palatoglossus arch in both its inferior and superior portions, the palatine tonsils, the base of the tongue and the uvula in 65 healthy young individuals. RESULTS: the swallowing reflex was not triggered in most of the participants when touching different oropharyngeal regions with different stimuli. This result was statistically significant. When present, the most efficient stimuli were cold 00 larynx mirror (28.6 percent) and frozen moist gauze wrapped onto spatula (27.3 percent). Concerning the oropharynx, the uvula (29.6 percent), the palatine tonsils (26.7 percent), the superior (25 percent) and inferior (21.2 percent) palatoglossi arches and the base of tongue (25 percent) were most sensitive to the applied stimuli. CONCLUSION: when the swallowing reflex was present, the uvula, the palatoglossi arches and the palatine tonsils were the most sensitive regions to trigger this reflex, and the most efficient stimuli to trigger swallowing were the cold 00 larynx mirror and the frozen moist gauze wrapped onto spatula.

Lesions of the cerebellar nodulus and uvula impair downward pursuit.

We studied sinusoidal (SIN) and step-ramp (SR) pursuit in two rhesus monkeys, before and after surgical lesions of the cerebellar nodulus and uvula (Nod/Uv). Eye movements were recorded using the magnetic field scleral search coil method. Pursuit targets were generated by an LCD projector and back-projected onto a tangent screen in an otherwise dark room. After the Nod/Uv lesions, both monkeys showed a reduced eye velocity during downward pursuit (SIN: 42% decrease in M1, 91% decrease in M2; SR: 37% decrease in M1, 85% decrease in M2). For SR, the decrease was seen only for the closed-loop response; initial eye acceleration did not change (P>0.05). Upward pursuit gains increased for SIN (M1: 9%, M2: 11%); they decreased for SR (M1: 27%, M2: 18%), but to a lesser degree than for downward pursuit. Horizontal pursuit was little changed in M1 but was reduced in one direction in M2, the animal with the larger lesion. The deficit in downward tracking was limited to foveal pursuit; ocular following of random-dot stimuli was retained, even when the target subtended only several degrees. Our findings support a critical role for the Nod/Uv in vertical pursuit, particularly for sustained downward pursuit. Finally, in both monkeys, the lesion increased spontaneous upward ocular drift in the dark (mean prelesion, 1.43 degrees/s; postlesion, 5.92 degrees/s), suggesting a role for the Nod/Uv in holding the eyes still and in the genesis of downbeat nystagmus.

A comparison of postoperative recovery from laser-assisted uvulopalatoplasty using different laser systems.

OBJECTIVES: The aim of this study was to compare the effectiveness of 5 power lasers (CO(2), diode, KTP, ErCr:YS66, and ND:YVO4) in laser-assisted uvulopalatoplasty. METHODS: This is a prospective study of 100 patients who were treated for snoring by laser-assisted uvulopalatoplasty with different lasers. RESULTS: The number of days of pain medication use and the time to return to normal diet were used as indicators of recovery from surgery. Median of pain medication use was 9, 7, 7, 5, and 4 days, and the median of the time to return to normal diet was 8, 7, 7, 6, and 4 days in the CO(2), diode, KTP, Nd:YVO4, and ErCrYSGG groups, respectively. CONCLUSIONS: Differences in postoperative recovery were observed. Probands treated with ErCrYSGG laser recovered more quickly than the Nd:YVO4, diode, KTP, and CO(2) groups.

Why do we have a uvula?: literature review and a new theory.

From ancient times up to the present day many different functions and conditions have been attributed to the uvula, many speculative and some with a more scientific basis. The uvula has been shown to have the ability to produce and secrete large quantities of thin saliva. A common complication of surgery involving removal of the uvula is pharyngeal dryness. We have observed that on phonation and swallowing the uvula swings back and forth in the oropharynx. We present a review of the literature on the uvula and propose a theory that the uvula bastes the throat and thereby helps keep it moist and well lubricated.

Role of cerebellar nodulus and uvula on the vestibular quick phase spatial constancy.

We investigated the orientation of quick phases (QPs) of vestibularly-induced eye movements in rabbits in response to "off-vertical" sinusoidal vestibular stimulation. We also examined the possible role of the cerebellar nodulus and ventral uvula in controlling QP spatial orientation and modification. During "off-vertical" vestibular stimulation QPs remained aligned with the earth's horizontal plane, while the slow phases (SPs) were aligned with the plane of vestibular stimulation. This suggests that QPs are coded in gravito-inertial coordinates and SPs in head coordinates. When rabbits were oscillated in the light (20 degrees peak-to-peak; 0.2 Hz) about an "off-vertical" axis for 2 h, the QPs changed their trajectory, abandoning the earth's horizontal plane to approach the plane of the stimulus. By contrast, in the absence of conjunctive optokinetic stimulation, QPs remained fixed in the earth's horizontal plane even after 2 h of "off-vertical" stimulation. The conjunctive combination of optokinetic and vestibular stimulation caused QPs to change their plane of rotation. After lesion of the nodulus-uvula the ability of rabbits to reorient QPs during conjoint vestibular-optokinetic stimulation was maintained. We conclude that the space orientation and adaptation of QPs do not require cerebellar control.

Breathing pauses during sleep: can a non-invasive ENT examination help identify subjects at risk in epidemiological settings?

In patients with obstructive sleep apnoea (OSA) anatomic and functional upper airway abnormalities are frequent and severe. Invasive methods are used to identify and quantitate the obstruction, to precisely locate its site, etc. as part of pre-treatment or of preoperative evaluations.These methods (lateral skull radiographs, computerized tomography, MRI, fibroscopies, etc) are too expensive and too invasive to be utilized in field surveys. To the classical sleep questionnaires and anthropometric measurements, some simple nose-throat examinations, easily accepted by the volunteers in a population study, could add useful information for the identification of the subjects at risk for sleep-disordered breathing. The present paper is a review of these examinations and of their utility.

Palatal snoring identified by acoustic crest factor analysis.

The differentiation of palatal from non-palatal snoring is very important for ENT surgeons trying to determine whether palatal surgery would be curative. At present sleep nasendoscopy is the accepted method. Palatal vibration produces marked modulation of sound loudness at low frequency (below approximately 100 Hz). We calculate a crest factor for the sound waveform (ratio of peak to root mean square (rms) value in any given epoch), as a measure of the degree of modulation. Free-field snore sounds were recorded from 11 supine adult patients under intravenous sedation (midazolam), using a digital tape recorder. Recordings were transferred to a PC (sampling frequency 11 kHz), and analysed using code written by us. Direct visual confirmation of the site of snoring was gained from simultaneous sleep nasendoscopy, taken as the gold standard. In six patients the dominant site was the soft palate. The non-palatal group (five patients) comprised one epiglottic, two hypopharyngeal and two tongue base snorers. The crest factor was found to be significantly higher for palatal snorers (p < 0.01, Student-t or Mann-Whitney tests). Furthermore, palatal could be distinguished from non-palatal snorers on the basis of crest factor alone in all 11 cases, making this a promising non-invasive diagnostic technique.

Predicting midsagittal pharynx shape from tongue position during vowel production.

The shape of the pharynx has a large effect on the acoustics of vowels, but direct measurement of this part of the vocal tract is difficult. The present study examines the efficacy of inferring midsagittal pharynx shape from the position of the tongue, which is much more amenable to measurement. Midsagittal magnetic resonance (MR) images were obtained for multiple repetitions of 11 static English vowels spoken by two subjects (one male and one female). From these, midsagittal widths were measured at approximately 3-mm intervals along the entire vocal tract. A regression analysis was then used to assess whether the pharyngeal widths could be predicted from the locations and width measurements for four positions on the tongue, namely, those likely to be the locations of a receiver coil for an electromagnetometer system. Predictability was quite high throughout the vocal tract (multiple r> 0.9), except for the extreme ends (i.e., larynx and lips) and small decreases for the male subject in the uvula region. The residuals from this analysis showed that the accuracy of predictions was generally quite high, with 89.2% of errors being less than 2 mm. The extremes of the vocal tract, where the resolution of the MRI was poorer, accounted for much of the error. For languages like English, which do not use advanced tongue root (ATR) distinctively, the midsagittal pharynx shape of static vowels can be predicted with high accuracy.

Abolished tilt suppression of the vestibulo-ocular reflex caused by a selective uvulo-nodular lesion.

Within the cerebellum several structures are considered to modulate the function of the vestibulo-ocular reflex (VOR). The nodulus and uvula have been implicated with the low-frequency components of the VOR, which are mediated by the velocity storage system. We report a patient with a selective lesion of the nodulus and ventral uvula. The findings suggest that nodulus and uvula normally exert an inhibitory effect on the velocity storage mechanism.

CT in the evaluation of the upper airway in healthy subjects and in patients with obstructive sleep apnea syndrome.

AIM: To study if the caliber of the upper airway, measured by CT, allows us to distinguish patients with obstructive sleep apnea syndrome (OSAS) from healthy people. PATIENTS AND METHODS: Sixteen OSAS patients (with an apnea-hypopnea index > 10) and 39 healthy volunteers were studied. Polysomnography and CT of the upper airways during awake periods were performed in both groups. We used third-generation equipment (Toshiba model TCT 600QT). The area of the nasopharynx, oropharynx, and hypopharynx (in inspiration and expiration), the uvula diameter, and retropharyngeal tissue were evaluated. The simultaneous identification of the variables that differentiate between control and OSAS groups was determined by a multivariate discriminant model. RESULTS: The retropharyngeal tissue in OSAS men was greater than those of the control men (10.3+/-3.6 mm vs 6.4+/-2.7 mm; p < 0.01). The multivariate analysis was performed on the 29 men (14 OSAS and 15 non-OSAS) who had information compiled in the selected parameters. The retropharyngeal tissue, expiratory hypopharynx, and uvular diameter are used to create a discriminant model (Wilks' lambda=0.556; p < 0.01). Two non-OSAS and five OSAS patients were incorrectly classified by this model as members of the other group (total rate of error, 24.14%). Therefore, the point estimates of specificity and sensitivity are 86.67% and 64.29%, respectively, for this model. The Pearson correlation coefficient between body mass index and retropharyngeal tissue is 0.63 (p < 0.001). CONCLUSIONS: CT could play an important role in studying the upper airway in patients with OSAS. The determination of the retropharyngeal tissue by CT could be a useful procedure to evaluate OSAS.