Afferent nerve ending density in the human laryngeal mucosa: potential implications on endoscopic evaluation of laryngeal sensitivity.

Laryngeal sensitivity is crucial for maintaining safe swallowing, thus avoiding silent aspiration. The sensitivity test, carried out by fiberoptic endoscopic examination of swallowing, plays an important role in the assessment of dysphagic patients. The ventricular folds appear to be more sensitive than the epiglottis during the sensitivity test. Therefore, this study aimed to investigate the mechanical sensitivity of the supraglottic larynx. In seven healthy adults undergoing microlaryngoscopy to remove vocal cord polyps, we excised mucosal samples from the epiglottis and ventricular folds. We measured afferent nerve fiber density by immunoelectron microscopy. All of the subjects underwent an endoscopic sensitivity test based on lightly touching the laryngeal surface of the epiglottis and ventricular folds. The discomfort level was self-rated by the subjects on the visual analog scale. Samples were fixed and stored in cryoprotectant solution at 4 °C. Sections were stained with the protein gene product 9.5, a pan-neuronal selective marker. Nerve fiber density was calculated as the number of fibers per millimeter length of section. The mean nerve fiber density was higher in ventricular samples than in epiglottis samples (2.96 ± 2.05 vs 0.83 ± 0.51; two-sided p = 0.018). The mean visual analog scale scores were significantly higher for touching the ventricular folds than for touching the epiglottis (8.28 ± 1.11 vs 4.14 ± 1.21; two-sided p = 0.017). The higher sensitivity of the ventricular region should be considered for further refining clinical endoscopic evaluation of laryngeal sensitivity.

Effortful swallow enhances vertical hyolaryngeal movement and prolongs duration after maximal excursion.

Effortful swallowing (EFS) is a common compensatory swallowing manoeuver for dysphagia patients. We investigated the influence of EFS on temporal and spatial characteristics of the movements of the hyoid bone, larynx and epiglottis in healthy subjects. A total of 41 volunteers swallowed 10 mL of diluted barium solution using two swallowing strategies: usual and effortful swallowing (USS and EFS). The motions of the hyoid bone, larynx and epiglottis were tracked using frame-by-frame kinematic motion analysis of videofluoroscopic images. Maximal velocities and maximal displacements of hyoid and larynx, the maximal angle of the epiglottic tilt, and the durations of hyoid excursion, laryngeal elevation and epiglottic tilt were measured. Compared to USS, EFS was associated with significantly greater vertical displacement of the hyoid (P < 0.001), vertical and horizontal displacement of the larynx (P = 0.003, P = 0.019), and maximal angle of the epiglottic tilt (P = 0.001). In addition, the durations of the vertical and horizontal excursions of the hyoid, vertical excursion of the larynx and the epiglottic tilt were greater in EFS, compared with USS. Effortful swallowing was also associated with significantly greater maximum velocities of the hyoid and larynx during swallowing. In conclusion, the EFS manoeuver facilitates vertical speed and distance of hyolaryngeal excursion and epiglottic tilt and extends the duration of excursion and the epiglottic tilt, especially after reaching maximal excursion in healthy subjects. These results confirm the temporal and kinematic benefits of airway protection induced by the EFS manoeuver.

Pharyngeal diameter in various head and neck positions during exercise in sport horses.

BACKGROUND: In equine athletes, dynamic stenotic disorders of the upper airways are often the cause for abnormal respiratory noises and/or poor performance. There are hypotheses, that head and neck flexion may influence the morphology and function of the upper airway and thus could even induce or deteriorate disorders of the upper respiratory tract. Especially the pharynx, without osseous or cartilaginous support is prone to changes in pressure and airflow during exercise. The objective of this study was to develop a method for measuring the pharyngeal diameter in horses during exercise, in order to analyse whether a change of head-neck position may have an impact on the pharyngeal diameter. RESULTS: Under the assumption that the width of the epiglottis remains constant in healthy horses, the newly developed method for calculating the pharyngeal diameter in horses during exercise is unsusceptible against changes of the viewing-angle and distance between the endoscope and the structures, which are to be assessed. The quotient of the width of the epiglottis and the perpendicular from a fixed point on the dorsal pharynx to the epiglottis could be used to determine the pharyngeal diameter. The percentage change of this quotient (pharynx-epiglottis-ratio; PE-ratio) in the unrestrained head-neck position against the reference position was significantly larger than that of any other combination of the head-neck positions investigated. A relation between the percentage change in PE-ratio and the degree of head and neck flexion could not be confirmed. CONCLUSIONS: It could be shown, that the pharyngeal diameter is reduced through the contact position implemented by the rider in comparison to the unrestrained head and neck position. An alteration of the pharyngeal diameter depending on the degree of head and neck flexion (represented by ground and withers angle) could not be confirmed.

Correlation varies with different time lags between the motions of the hyoid bone, epiglottis, and larynx during swallowing.

Although coordination and timing of swallowing have often been investigated by using discrete timing events such as the onset, peak, and duration of specific motions, the sequence and duration of swallowing events cannot represent the coordination of the swallowing mechanism quantitatively. This study aimed to apply a cross-correlation analysis of the motions of the hyolaryngeal structures during swallowing as an objective method for measuring the coordination and timing of the motions. Forty healthy subjects swallowed 2 and 5 ml of diluted barium solution (35 %) and 5 ml of curd yogurt under videofluoroscopy. Hyolaryngeal motions in videofluoroscopic images were digitized using the motion analysis system. The time series of the horizontal and vertical hyoid motion, the laryngeal elevation, and the angle of the epiglottic tilt were analyzed using cross-correlation at each 1/60-s time lag. The results showed high and consistent cross-correlations between hyolaryngeal motions during swallowing in most of the subjects regardless of age and bolus type. The horizontal hyoid motion and laryngeal elevation were more strongly correlated with the epiglottic tilt than the vertical hyoid motion, which might suggest the mechanism of the epiglottic tilt during swallowing. The bolus volume and viscosity affected the correlation coefficients and time lags between the hyolaryngeal motions, particularly those related to the epiglottic tilt. The results suggest that cross-correlation analysis may be used for measuring the coordination and timing of swallowing. Further studies using cross-correlation analysis of additional physiological factors related to swallowing or pathological conditions are warranted.

Muscular anatomy of the human ventricular folds.

OBJECTIVES: Our purpose in this study was to better understand the muscular anatomy of the ventricular folds in order to help improve biomechanical modeling of phonation and to better understand the role of these muscles during phonatory and nonphonatory tasks. METHODS: Four human larynges were decalcified, sectioned coronally from posterior to anterior by a CryoJane tape transfer system, and stained with Masson's trichrome. The total and relative areas of muscles observed in each section were calculated and used for characterizing the muscle distribution within the ventricular folds. RESULTS: The ventricular folds contained anteriorly coursing thyroarytenoid and ventricularis muscle fibers that were in the lower half of the ventricular fold posteriorly, and some ventricularis muscle was evident in the upper and lateral portions of the fold more anteriorly. Very little muscle tissue was observed in the medial half of the fold, and the anterior half of the ventricular fold was largely devoid of any muscle tissue. All 4 larynges contained muscle bundles that coursed superiorly and medially through the upper half of the fold, toward the lateral margin of the epiglottis. CONCLUSIONS: Although variability of expression was evident, a well-defined thyroarytenoid muscle was readily apparent lateral to the arytenoid cartilage in all specimens.

An investigation of articulatory setting using real-time magnetic resonance imaging.

This paper presents an automatic procedure to analyze articulatory setting in speech production using real-time magnetic resonance imaging of the moving human vocal tract. The procedure extracts frames corresponding to inter-speech pauses, speech-ready intervals and absolute rest intervals from magnetic resonance imaging sequences of read and spontaneous speech elicited from five healthy speakers of American English and uses automatically extracted image features to quantify vocal tract posture during these intervals. Statistical analyses show significant differences between vocal tract postures adopted during inter-speech pauses and those at absolute rest before speech; the latter also exhibits a greater variability in the adopted postures. In addition, the articulatory settings adopted during inter-speech pauses in read and spontaneous speech are distinct. The results suggest that adopted vocal tract postures differ on average during rest positions, ready positions and inter-speech pauses, and might, in that order, involve an increasing degree of active control by the cognitive speech planning mechanism.

Improved vocal tract reconstruction and modeling using an image super-resolution technique.

Magnetic resonance imaging has been widely used in speech production research. Often only one image stack (sagittal, axial, or coronal) is used for vocal tract modeling. As a result, complementary information from other available stacks is not utilized. To overcome this, a recently developed super-resolution technique was applied to integrate three orthogonal low-resolution stacks into one isotropic volume. The results on vowels show that the super-resolution volume produces better vocal tract visualization than any of the low-resolution stacks. Its derived area functions generally produce formant predictions closer to the ground truth, particularly for those formants sensitive to area perturbations at constrictions.

[Numerical simulation on cycle change form of the pressure and wall shear in human upper respiratory tract].

The research on cycle change form of the pressure and the wall shear in human upper respiratory tract can strengthen understanding of the characteristics of the airflow in the place and provide us with a scientific basis for analyzing the diffusion, transition and deposition patterns of aerosol there. In our study, we used large eddy simulation to emulate the pressure and wall shear in human upper respiratory tract in conditions of the low intensive respiratory patterns, and discussed the distributing disciplinarian of the pressure and wall shear in mouth-throat model and trachea-triple bifurcation. The results showed that the pressure gradient variation in human upper respiratory tract was mainly fastened from root of epiglottis to trachea. The minimum pressure at the interim of inspiration was a duplication of the interim of expiration, and located on the posterior wall of the glottis. The pressure gradient variation was evident on trachea and its fork. The wall shear changed with the velocity of the air flow, and its direction changed periodically with breath cycle.

The role of the epiglottis in the swallow process after a partial or total glossectomy due to a neoplasm.

Repeatable epiglottic movement patterns were recorded during a videofluoroscopic swallow evaluation of 95 patients who had undergone a total or partial glossectomy due to a neoplasm. Because no epiglottic function assessment was performed preoperatively, for the purpose of this study it was assumed that epiglottic mobility was "normal" during this time and that all abnormalities found afterward resulted from the growth of the neoplasm and the glossectomy. It was noted that in the early postoperative period, absence of epiglottic movement was accompanied by aspiration and made swallowing incompetent in a majority of cases (9 of 10). A correlation of movement between the epiglottis and the extent of oral tissue excision was found. Epiglottic mobility was evaluated as "normal" in 72% of the patients, i.e., in 67 of 91 (74%) patients after a partial or nearly total glossectomy and in 1 of 4 people who underwent a total glossectomy. In the subgroup (16%) of patients who underwent a total or nearly total glossectomy and then had videofluoroscopic examinations, 60% of the cases had normal epiglottic movements and 40% had an immobile epiglottis. Compensatory mechanisms implemented by the patients on their own initiative, such as additional swallows and prolonged apnea during deglutition, enabled them to avoid aspiration. However, upward head movement and downward chin tilting during deglutition as compensatory mechanisms used by patients with no epiglottic movement did not reduce the aspiration risk in the early postoperative period and were found to accompany incompetent swallowing attempts.

Effect of mandibular position on three-dimensional shape of the oropharynx in seated posture.

Dysphagia rehabilitation in the elderly includes direct therapy to alter the three-dimensional shape of the oropharynx so that food boluses can pass safely through the poorly functioning pharynx. Alteration of the mandibular position is thought to affect oropharyngeal shape, but this relationship remains poorly understood. We therefore studied the relationship between mandibular position and three-dimensional shape of the oropharynx in the seated posture normal for feeding. Ten healthy, dentate subjects participated (average age, 28·1 years). Experimental mandibular positions were the intercuspal position, bite-raised position and mandible-advanced position. The oropharynx was scanned in a 90° seated posture using dental cone-beam computed tomography, and the effects of changes in mandibular position were analysed after obtaining oropharyngeal volume, height, sectional area, average sectional area of oropharynx and the position of the epiglottis. Oropharyngeal volume and average sectional area increased significantly in the mandible-advanced position compared with other mandibular positions. Notably, the volume and average sectional area of the inferior part of the oropharynx increased significantly. Oropharyngeal height and sectional area at the base of the epiglottis showed no significant difference in bite-raised position and mandible-advanced position compared with intercuspal position. The position of the epiglottis moved significantly forward in the mandible-advanced position. The results of this study show that in a seated posture, volume of the oropharynx increases as a result of changes in the mandible-advanced position. The increase in oropharyngeal volume demands greater muscular constriction to generate swallowing pressure and could lead to a decrease in reserve capacity of swallowing.

Analogy between laryngeal gesture in Mongolian Long Song and supracricoid partial laryngectomy.

This article reports the results of a multiparametrical analysis of Mongolian Long Song, characterised by multiple ornamentation and shows the similarities between the laryngeal behaviour observed during these ornamentations and the compensatory gesture produced by patients after supracricoid partial laryngectomy. This study includes (1) a physiological analysis of videofiberscopic laryngeal data from a healthy Mongolian singer and from three non-singer French-speaking clinical patients; and (2) an acoustical analysis (fundamental frequency and intensity). For the singer, the fiberoptic analysis showed two main laryngeal behaviours in producing ornamentations: (1) 'lyrical' vibratos mobilising the entire laryngeal block; (2) 'Mongolian' trills with essentially supraglottic movements, the arytenoids being mobilised independently of the rest of the laryngeal block. Patients demonstrated similar aryepiglottic trilling to fulfil a function of voicing. The acoustic analysis showed that the fundamental frequency and the intensity were in phase for vibrato, contrary to the 'Mongolian' trills which were in opposite phase, underlying a change of laryngeal vibratory mechanisms.

Head rotation improves airway obstruction, especially in patients with less severe obstructive sleep apnea without oropharyngeal collapse.

PURPOSE: Head rotation is thought to have an effect on obstructive sleep apnea (OSA) severity. However, keeping the head rotated fully during sleep is difficult to maintain, and the effect of head rotation is not the same in all OSA patients. Thus, this study aimed to identify whether less head rotation has an effect on airway patency and determine the responder characteristics to the head rotation maneuver (HRM). METHODS: We recruited 221 patients who underwent overnight polysomnography and drug-induced sleep endoscopy (DISE) in a tertiary hospital from June 2019 to July 2020. Airway patency and the site of airway collapse were determined in the supine position with the head at 0, 30, and 60 degrees of rotation (HRM0°, HRM30°, and HRM60°, respectively) during DISE. The site of collapse was determined using the VOTE classification system: the velum (palate), oropharyngeal lateral walls, tongue base, and epiglottis. Each structure was labeled as 0, 1, or 2 (patent, partially obstructed, and completely obstructed, respectively). Airway response to the HRM30° and 60° and the clinical characteristics associated with airway opening were analyzed. RESULTS: The study population had a median age of 52 (25-61) years, a body mass index of 26.7(24.6-29.4) kg/m2, and the apnea-hypopnea index (AHI) of 28.2(13.7-71.9) events/h. HRM influenced airway patency positively not only with HRM60° (p<0.001) but also following limited rotation (HRM30°, p<0.001). Patients with tongue base (40.0% with HRM 60°) and epiglottic (52.6% with HRM 60°) collapse responded particularly well to HRM. Multivariate analysis revealed that lower AHI (p<0.001) and an absence of oropharyngeal lateral walls collapse (p = 0.011) were significant predictors of responders to HRM. CONCLUSION: Head rotation improved airway obstruction in OSA patients, even with a small degree of rotation, and should be further explored as a potential form of therapy in appropriately selected patients.

Observation of arytenoid movement during laryngeal elevation using videoendoscopic evaluation of swallowing.

The purpose of this study was to confirm that the arytenoid regions dynamically adduct and extend upward toward the epiglottis during laryngeal elevation. While 14 healthy volunteers aged 19-32 years old swallowed 5 ml of white soft yogurt in one gulp without chewing, the movement of the arytenoid regions was observed for videoendoscopic evaluation of swallowing (VE). Each moving image was stored simultaneously on videotape. A cross-sectional area surrounded by the epiglottis and the bilateral arytenoid regions (S) and the length of a straight line passing through the anterior borders of the left and right arytenoid regions (L) were measured. The relative area of the entrance in the laryngeal vestibule was calculated as [S/L (2)] before the swallowing reflex (resting condition), just before laryngeal closure, and just after laryngeal closure. [S/L (2)] was smaller just before epiglottal descent than at the resting condition, and became smallest just after the epiglottis started to ascend. The mean area narrowed to 37.9% of the resting area just after laryngeal closure and in the most extreme case to 8.7% of the resting area. It was demonstrated that the arytenoid regions adducted and extended up toward the epiglottis during laryngeal elevation. The technique used to measure the cross-sectional area of the entrance in the laryngeal vestibule employing VE was an effective analytical procedure.

Influence of aging on movement of the hyoid bone and epiglottis during normal swallowing: a motion analysis.

BACKGROUND: The age-related effects on various aspects of swallowing have been reported in studies on the temporal relationship between hyolaryngeal movement and bolus location, as well as the extent of hyolaryngeal movement. However, few studies have described the temporal and spatial relationships concurrently. OBJECTIVE: The main purpose of this study was to define the kinematics of the hyoid bone and epiglottis, during swallowing, on the temporal and spatial relationships concurrently in healthy subjects, and to investigate the influence of aging on hyolaryngeal movement. METHODS: We performed a two-dimensional motion analysis of the hyoid bone and epiglottis using videofluoroscopy images in 69 normal subjects. The trajectories of the hyolaryngeal movement and passage of a bolus were superimposed to form one plot. Temporal measurements included initiation and duration of the hyoid bone and epiglottis movement compared to their movement with the bolus. The spatial measurements included vertical and horizontal excursion of the hyoid bone, and the rotational angle of the epiglottis. RESULTS: The duration of supraglottis closure, and the maximal vertical excursion of the hyoid bone were increased in older subjects, more than 65 years of age, compared to younger subjects (p<0.05). Other temporal and spatial measurements were not statistically significant in the comparisons among the age groups. The vertical distance of the cervical vertebra was related to vertical excursion of the hyoid bone (p=0.002), and the horizontal distance from the chin to the cervical vertebra was related to the horizontal excursion of the hyoid bone (p=0.003). CONCLUSION: This paper describes a method for assessing temporal and spatial relationships of hyolaryngeal movement, and the passage of a bolus during swallowing. The two-dimensional kinematic swallowing motion analyses that were developed provided useful data that changed with age.

Epiglottis is not essential for successful swallowing in humans.

Controversy has continued for well over 100 years regarding the role of the epiglottis in deglutition. We describe the effect of isolated epiglottectomy on swallowing success in a case series of 3 adult human subjects with isolated epiglottectomy due to trauma, surgery, or cancerous erosion. The patients were 42, 51, and 70 years of age, and swallowing was analyzed objectively with videofluoroscopy. All subjects exhibited successful swallowing with all food types: thin liquid, puree, and solid food. Specifically, the patient with traumatic epiglottectomy exhibited rapid swallowing success, the patient with surgical epiglottectomy exhibited a short period of dysphagia due to postoperative edema, followed by swallowing success, and the patient with epiglottectomy due to cancerous erosion of the entire epiglottis exhibited long-term adaptation, with successful swallowing maintained. We conclude that the epiglottis is not essential for successful swallowing in humans, because individuals can readily adapt to isolated epiglottectomy and avoid tracheal aspiration.

Age-related changes in the hyoepiglottic ligament: functional implications based on histopathologic study.

PURPOSE: The study aimed to identify age-related changes in the hyoepiglottic ligament associated with function of the epiglottis during swallowing and respiration. MATERIALS AND METHODS: Normal postmortem laryngeal tissue samples were obtained at autopsy from 20 individuals with no history of laryngeal disease. The subjects were divided into 2 groups: those aged 81-91 years (elderly group, n = 11) and those aged 31-48 years (non-elderly group, n = 9). Specimens were subjected to Elastica van Gieson and hematoxylin-eosin staining, and characteristics of the hyoepiglottic ligament were compared between groups. RESULTS: The hyoepiglottic ligament extended from the epiglottis to both lingual muscles and the hyoid bone (pars lingualis and pars hyoideus). The numbers of muscle fibers (P < .001), collagenous fibers (P < .01), and elastic fibers (P < .001) were significantly decreased in the elderly group in comparison to those in the non-elderly group. CONCLUSION: Age-related changes in the hyoepiglottic ligament appear to be associated with aspiration, obstructive sleep apnea syndrome, and acquired laryngomalacia in the elderly.

A high-speed laryngoscopic investigation of aryepiglottic trilling.

Six aryepiglottic trills with varied laryngeal parameters were recorded using high-speed laryngoscopy to investigate the nature of the oscillatory behavior of the upper margin of the epilaryngeal tube. Image analysis techniques were applied to extract data about the patterns of aryepiglottic fold oscillation, with a focus on the oscillatory frequencies of the folds. The acoustic impact of aryepiglottic trilling is also considered, along with possible interactions between the aryepiglottic vibration and vocal fold vibration during the voiced trill. Overall, aryepiglottic trilling is deemed to be correctly labeled as a trill in phonetic terms, while also acting as a means to alter the quality of voicing to be auditorily harsh. In terms of its characterization, aryepiglottic vibration is considerably irregular, but it shows indications of contributing quasi-harmonic excitation of the vocal tract, particularly noticeable under conditions of glottal voicelessness. Aryepiglottic vibrations appear to be largely independent of glottal vibration in terms of oscillatory frequency but can be increased in frequency by increasing overall laryngeal constriction. There is evidence that aryepiglottic vibration induces an alternating vocal fold vibration pattern. It is concluded that aryepiglottic trilling, like ventricular phonation, should be regarded as a complex, if highly irregular, sound source.

Endoscopic evaluation of arytenoid function and epiglottic structure in Thoroughbred yearlings and association with racing performance at two to four years of age: 2,954 cases (1998-2001).

OBJECTIVE-To determine the association between results of endoscopic evaluation of arytenoid function (AF) and epiglottic structure (ES) in Thoroughbred yearlings and racing performance at 2 to 4 years of age. DESIGN-Retrospective case series. ANIMALS-2,954 Thoroughbred yearlings. Procedures-Records of yearlings that had endoscopic evaluation of the larynx between 1998 and 2001 were obtained, and results were graded by use of standardized scales. A modified Havemeyer scale (grade I, II.1, II.2, III, or IV) was used to evaluate AF; ES was graded on a scale of 0 to IV. Records were annotated if the epiglottis was subjectively short or narrow. Racing performance data were obtained from an online database. RESULTS-Horses with grade II.2 AF had significantly less earnings at 4 years of age, compared with earnings of horses with AF grades < II.2. Grade III AF was associated with fewer starts and less earnings at 3 and 4 years of age. No horses met the criteria for grade IV AF. Horses with ES grades > II had less earnings at 2 and 4 years of age, compared with earnings of horses with ES grades < II. A short epiglottis was associated with less earnings at 2 and 3 years of age. CONCLUSIONS AND CLINICAL RELEVANCE-Analysis suggested that yearlings with grade III AF had a decrease in athletic potential. Yearlings with grade II.2 AF, an ES grade > II, or a short epiglottis typically had decreases in racing performance. These factors should be evaluated carefully when developing purchase recommendations.

Postoperative Skeletal Stability and Pharyngeal Airway: Counterclockwise versus Clockwise Rotation during Mandibular Setback Surgery.

PURPOSE: To compare the effects of counterclockwise rotation (CCR) and clockwise rotation (CR) of the mandible on the pharyngeal airway during mandibular setback surgery. Materials and Methods. Serial cephalograms of 40 patients with mandibular prognathism, including 20 who underwent CCR and 20 who underwent CR, were taken at the following time intervals: preoperatively (T1), immediately postoperatively (T2), >1 year after surgery (T3), final surgical changes (T31), postoperative stability (T32), and immediate surgical change (T21). Changes in menton (Me) and hyoid (H) positions, soft palate width, soft palate length, soft palate angle and craniovertebral angle (C2C4-SN), and pharyngeal airway spaces (nasal pharyngeal airway (NOP), uvula pharyngeal airway (UOP), tongue pharyngeal airway (TOP), and epiglottis pharyngeal airway (EOP)) were evaluated. RESULTS: The mean Me (T31) setback for CCR and CR was 12.56 and 13.06 mm, respectively, with 2.41 mm upward and 3.29 mm downward, respectively. The vertical Me position of CR exhibited significant downward movement compared with that of CCR. The mean H setback results for CCR and CR were 4.42 and 5.75 mm, respectively, with 1.47 mm downward and 2.97 mm downward, respectively. The C4C2-SN angles for CCR and CR increased by 2.68° and 3.65°, respectively, whereas their palatal angles increased by 2.35° and 5.25°, respectively. Pearson's correlation analysis (T31) revealed that for CCR, no pharyngeal airway spaces were significantly correlated with any measured variables. In CR, NOP was significantly correlated (r = 0.58) with the vertical Me position. Significant relapse (T32) was observed after CR in the horizontal (r = 0.58) with the vertical Me position. Significant relapse (T32) was observed after CR in the horizontal (r = 0.58) with the vertical Me position. Significant relapse (T32) was observed after CR in the horizontal (. CONCLUSION: Pharyngeal airway space narrowed postoperatively, and its patency was appropriately maintained through natural physiological regulation of the craniovertebral angle (C2C4-SN). Significant postoperative relapse was correlated with CR.

Effects of Angle of Epiglottis on Aerodynamic and Acoustic Parameters in Excised Canine Larynges.

OBJECTIVES: The aim of this study is to explore the effects of the angle of epiglottis (Aepi) on phonation and resonance in excised canine larynges. METHODS: The anatomic Aepi was measured for 14 excised canine larynges as a control. Then, the Aepis were manually adjusted to 60° and 90° in each larynx. Aerodynamic and acoustic parameters, including mean flow rate, sound pressure level, jitter, shimmer, fundamental frequency (F0), and formants (F1'-F4'), were measured with a subglottal pressure of 1.5 kPa. Simple linear regression analysis between acoustic and aerodynamic parameters and the Aepi of the control was performed, and an analysis of variance comparing the acoustic and aerodynamic parameters of the three treatments was carried out. RESULTS: The results of the study are as follows: (1) the larynges with larger anatomic Aepi had significantly lower jitter, shimmer, formant 1, and formant 2; (2) phonation threshold flow was significantly different for the three treatments; and (3) mean flow rate and sound pressure level were significantly different between the 60° and the 90° treatments of the 14 larynges. CONCLUSIONS: The Aepi was proposed for the first time in this study. The Aepi plays an important role in phonation and resonance of excised canine larynges.