Simultaneous Laryngopharyngeal and Conventional Esophageal pH Monitoring.

In addition to typical reflux symptoms, many patients with gastroesophageal reflux disease (GERD) present with extraesophageal symptoms such as cough, hoarseness or asthma, which can be caused by laryngopharyngeal reflux (LPR). Due to their multifactorial origin, those symptoms can be a great diagnostic and therapeutic challenge. Esophageal pH-monitoring is commonly used to determine abnormal esophageal acid exposure and confirm the diagnosis of GERD. However, for better evaluation of acid exposure above the upper esophageal sphincter, a new laryngopharyngeal pH measurement system is now available and may lead to more reliable results in patients with predominantly extraesophageal symptoms. This article aims to present a standardized protocol for simultaneous pH measurement using esophageal and laryngopharyngeal pH probes in order to obtain acid exposure scores from both measurements.

A novel fluoroscopic method for multidimensional evaluation of swallowing function.

OBJECTIVE: Dynamic videofluoroscopic swallow study (VFSS) is used to investigate swallowing movements. However, it requires prolonged radiation exposure and mainly provides qualitative information. Herein, we present a multi-dimensional method for analyzing swallowing based on a pulsed, low-dose fluoroscopy technique that uses serial-shot images and evaluates the size, position, and temporal profile of the bolus to obtain a more comprehensive and realistic analysis of swallowing movements. METHODS: Fifteen healthy adults drank two liquids: 20mL of pure water followed by 20mL of contrast medium mixture in a fluoroscopic study. Data were recorded in serial-shot images (7.5 frames/second, 1024×1024-pixel resolution, DICOM format). The images from the water and contrast swallows were inverted, synchronized, and subtracted to visualize the bolus in each frame. The pathway of the bolus was divided into 15 parts traversing the oropharynx, hypopharynx, and upper esophagus, and the total gray value was measured in each section. The results were presented as contour graphs. RESULTS: The contour graphs allowed for information on the size, anatomical location, and temporal location of the bolus during swallowing to be displayed simultaneously. Two distinct swallowing patterns were observed in the subjects. The bolus showed two peaks-one in the hypopharynx and one in the upper esophagus-in all subjects. However, in nine of the 15 subjects, the two peaks were in different frames, whereas in six of the subjects, the two peaks were in the same frame. CONCLUSION: We developed a new method for quantitatively evaluating swallowing. The technique allows for multidimensional assessment of the size, position, and temporal profile of the movement of the bolus across the pharynx. This method evaluates the swallowing movements using sharp, high-resolution images obtained by serial-shot, pulsed fluoroscopy with low radiation exposure. Additional studies are required to further clarify the variability of swallowing patterns and their clinical relevance in the evaluation of swallowing movements in healthy subjects and in patients with swallowing disorders.

[Effect of incisor retraction on three-dimensional morphology of upper airway and fluid dynamics in adult class â patients with bimaxillary protrusion].

Objective: To investigate the effect of incisor retraction on three-dimensional morphology of upper airway and fluid dynamics in class Ⅰ adult patients with bimaxillary protrusion. Methods: Thirty class Ⅰ patients with bimaxillary protrusion that received fixed orthodontic treatment in Department of Stomatology, The First Affiliated Hospital of Wenzhou Medical University from January 2011 to September 2014 were selected using random number table. All the patients were treated with extraction of four first premolars and retraction of anterior teeth using implant anchorage. Cone-beam CT (CBCT) scans were performed before and after incisor retraction for all patients. The CBCT data of the upper airway were constructed using Mimics 16.0, and the flow field characteristics inside the upper airway were simulated using Ansys 14.0. The changes of volume (V), mean cross-sectional area (mCSA), maximum lateral diameters/maximum anteroposterior diameters (LP/AP) of cross section, the maximum pressure of airflow (P(max)), the minimum pressure of airflow (P(min)) and pressure drop (△P) of nasopharynx, oropharynx and hypopharynx before and after incisor retraction were measured and compared using paired t test. The correlation between the variation of △P in the most significant pharyngeal part and the morphological variables after incisor retraction was analyzed using Pearson correlation test. Results: No statistical differences were observed in the morphology and flow field in nasopharynx before and after incisor retraction (P>0.05). Before incisor retraction, the oropharyngeal volume and mCSA were (7 580±622) mm(3) and (217±40) mm(2), respectively, and the hypopharyngeal volume and mCSA were (2 564±162) mm(3), and (239±43) mm(2), respectively. After incisor retraction, the volumes of oropharynx and hypopharynx were (6 885±601) mm(3) and (2 535±156) mm(3), respectively, and mCSA of oropharynx and hypopharynx were (197±37) mm(2) and (236±42) mm(2), respectively. The volume and mCSA of oropharynx and hypopharynx were significantly decreased after incisor retraction (P<0.05). The greatest changes in pharyngeal volume and mCSA occurred in the oropharynx. In addition, the LP/AP of oropharynx after incisor retraction was changed from 1.9±0.6 to 2.1±0.7, which was significantly increased compared with the levels before incisor retraction (P<0.05). After simulation of pharyngeal airflow, the oropharyngeal P(min), hypopharyngeal P(max) and P(min) were (-13.7±4.3), (-8.3±3.8) and (-42.8±9.5) Pa, respectively, whereas the values turned to (-16.4±6.5), (-11.9±3.6) and (-46.0±11.0) Pa, respectively after incisor retraction, which was significantly reduced (P<0.05). △P of oropharynx was significantly increased from (42.7±10.1) Pa to (45.2±13.0) Pa after incisor retraction (P<0.05) and the variation of oropharyngeal △P was negatively correlated with the variation of V and mCSA in oropharynx before and after incisor retraction (r=-0.681, P=0.001; r=-0.844, P=0.000). Conclusions: The oropharynx was constricted and the pharyngeal resistance was increased after incisor retraction in adult class Ⅰ patients with bimaxillary protrusion. A comprehensive and systematic evaluation of the pharyngeal morphology and ventilatory function were very important for making a scientific and rational clinical treatment plan.

Hypopharyngeal multichannel intraluminal impedance leads to the promising outcome of antireflux surgery in Japanese population with laryngopharyngeal reflux symptoms.

BACKGROUND: Clinical characteristics of laryngopharyngeal reflux (LPR) in Japanese population remain unclear, and its treatment outcome is suboptimal. The objectives of this study were to evaluate Japanese patients with LPR symptoms using hypopharyngeal multichannel intraluminal impedance (HMII) and to assess the outcome of antireflux surgery (ARS). METHODS: Subjects included patients who had LPR symptoms for > 12 weeks or laryngoscopic findings suggestive of LPR and underwent laryngoscopy and esophageal testing including HMII. Abnormal proximal exposure (APE) was defined as LPR ≥ 1/day and/or full column reflux (FCR) (reflux 2 cm distal to the upper esophageal sphincter) ≥ 5/day on HMII. Patients with APE were offered ARS and the outcome of ARS was objectively assessed using Reflux Symptom Index (RSI). RESULTS: From July 2015 to September 2016, 52 patients with LPR symptoms (28 men, 24 women, median BMI 22.3) underwent HMII, and 38 patients (73%) had APE. Of them, 29 (76%) patients were not obese (BMI < 25) and 19 (50%) patients had a negative DeMeester score. Approximately one-third of LPR and FCR events were non-acid in the distal esophagus. A positive symptom-association probability was seen only in 18 patients (35%). Mild esophagitis and hiatal hernia were found in 5 (10%) and 23 (48%) patients, respectively. All 12 patients (100%) who had undergone ARS were able to discontinue PPI and had a significant improvement in the RSI scores postoperatively (22.9 ± 10.0 vs. 6.8 ± 6.8, p < .001). CONCLUSIONS: APE was frequently observed in Japanese patients with LPR symptoms. Obesity and esophagitis were uncommon in this population. Since a large number of patients with APE had negative DeMeester score and proximal reflux events were often non-acid, a conventional pH monitoring is insufficient. HMII is crucial to evaluate patients with LPR symptoms as the documentation of APE is a key for successful outcome of ARS.

Hypopharynx in termites: Morphological and functional aspects.

The hypopharynx morphology in workers, pseudergates, and soldiers was described in six families of Isoptera using scanning electronic microscopy. This is the first comparative study to detail the hypopharynx among different species of termites, and included 4 one-piece type (OP) and 9 multiple-pieces type termites (MP). The results showed different arrangements of the hypopharynx trichomes, with fewer of these structures in the frontal region of the hypopharynx in pseudergates and soldiers of OP termites. These characteristics did not apply to Serritermes serrifer, since its pseudergates displayed a large quantity of trichomes on the frontal surface. This species may not resemble other OP termites because it does not live inside a piece of wood, but rather are inquilines inside Cornitermes spp. nests. Similar morphology of this mouthpart was observed in the different species of MP termites, with workers exhibiting many unidirectional trichomes on the frontal surface and soldiers presenting fewer of these trichomes. The morphology of the hypopharynx seems to reflect the lifestyle of these species, because MP termites are able to exploit external water sources. Since different arrangements of hypopharynx trichomes are used for water intake via capillary action, the present data reinforce the soldiers' dependence on workers to obtain water and food through the process of trophallaxis. Three different types of sensilla were observed on the lateral region of the hypopharynx: chaetica, basiconica and campaniformia. Chaetica act as chemoreceptors, while basiconica and campaniformia are mechanoreceptors, used in feeding and environmental perception. Better understanding of hypopharynx morphology permits the inference of ecological habits among OP and MP termites, and reflects the physiological differences between workers and soldiers.

Pharyngeal swallowing pressures in the base-of-tongue and hypopharynx regions identified with three-dimensional manometry.

OBJECTIVES: This study aims to use three-dimensional (3D) high-resolution manometry to identify circumferential pressure patterns generated within the asymmetrical base-of-tongue and hypopharynx regions of the pharynx during deglutition. STUDY DESIGN: Case series. METHODS: Radial pressures in the regions of interest were evaluated during swallowing events in 12 healthy subjects using 3D high-resolution manometry. RESULTS: Repeated measures analysis of variance revealed asymmetrical pharyngeal clearance pressures in the base-of-tongue and hypopharynx regions during swallowing. A significant main effect of direction on pressure was found at the time point of average maximum pressure (P < 0.001) and for pressure integral (P < 0.001), with pressure primarily generated from the posterior direction. An interaction was noted between direction and location when comparing maximum directional pressures, regardless of time (P =0.045), highlighting the differences in anterior pressure production between regions. In contrast to the high posterior pressures produced in the base-of-tongue region, an anteroposterior dominant pressure pattern was observed in the hypopharynx. Pressure waveform complexity in the hypopharynx also is likely attributed to activity in the anterior and posterior directions. Symmetrical pressure generation was observed during intrabolus flow within the hypopharynx. CONCLUSION: This study shows that pressure is asymmetrically generated in the base-of-tongue and hypopharynx regions during swallowing of a 10-mL bolus, reflecting the complex anatomy within the pharynx. Understanding of these complex pressure patterns aids in the interpretation of high-resolution manometry and can help guide further study in the clinical assessment and treatment of pharyngeal pathology. LEVEL OF EVIDENCE: 4. Laryngoscope, 127:1989-1995, 2017.

Coincidence of Eagle Syndrome and Diffuse Idiopathic Skeletal Hyperostosis Presenting With Dysphagia as a Result of Compression of the Hypopharynx.

Coincidence of the Eagle syndrome and diffuse idiopathic skeletal hyperostosis can very rarely result with compression of the hypopharynx. The authors here described a very rare case of hypopharyngeal airway compression secondary to cervical osteophytes in a patient with coincidence of Eagle syndrome and diffuse idiopathic skeletal hyperostosis. Multidetector computed tomography accuracy showed compression to the hypopharyngeal air column by the Eagle syndrome and diffuse idiopathic skeletal hyperostosis.

Effect of three different chin-down maneuvers on swallowing pressure in healthy young adults.

OBJECTIVES/HYPOTHESIS: To determine the effects of three different chin-down maneuvers on swallowing pressure (SP) in healthy young adults using high-resolution manometry (HRM). STUDY DESIGN: Repeated measures with subjects serving as their own controls. METHODS: Twenty-six healthy subjects (average age 26.4 [range 21-35] years) swallowed 5 mL of cold water to examine the maximum swallowing pressure (MSP) at the velopharynx, meso-hypopharynx, and upper esophageal sphincter (UES), and to determine the duration of lowered SP at the UES using HRM. The subjects swallowed in the neutral position as a control and in the following three chin-down positions: 1) head flexion (HF); 2) neck flexion (NF); and 3) combined head and neck flexion (HFNF). RESULTS: The MSP at the velopharynx and meso-hypopharynx did not significantly differ among the three chin-down positions. Upon swallowing in the NF posture, the MSP was significantly lower (P < 0.0001) at the UES, and the duration of the lowered SP at the UES was significantly prolonged (P = 0.0010) compared to the neutral position. In comparison, the duration of lowered SP at the UES was significantly (P = 0.0001) shorter in the HF position than in the neutral position. Moreover, the HFNF position significantly (P = 0.0276) lowered the MSP at the UES compared to the control position. CONCLUSION: In young healthy adults, NF maneuver resulted in significantly lower MSP and longer duration of the lowered swallowing pressure at the UES, which might assist bolus passage through the UES. LEVEL OF EVIDENCE: 3b.

Propagation Curve and Velocity of Swallowing Pressure in Healthy Young Adults.

The objective of this study is to construct a propagation curve and determine propagation velocities in young healthy adults examined using a 2.64-mm-diameter high-resolution manometry catheter with 36 circumferential sensors; to explore data reproducibility; and to determine whether the swallowing pressure (SP) propagation velocity correlated with bolus volume. Repeated measures with subjects serving as their own controls. Thirty healthy subjects (average age 25.3 years) swallowed saliva and 2, 5, and 10 mL of cold water to determine the maximum SP from the soft palate to the cervical esophagus. The SP propagation curve was obtained by plotting the duration to reach each SP peak. The SP propagation velocity was calculated for each region. These parameters were examined according to bolus size and gender. The intra-class correlation coefficient for estimating the SP propagation curves was >0.61 (i.e., highly consistent). The propagation velocity was maximal at the meso-hypopharynx and minimal at the UES and cervical esophagus. The SP propagation curve was very reproducible within any subject. Neither the water volume (with the exception of 2 and 5 mL) nor gender exerted any apparent effect on velocity in any region. However, the velocity was quite variable at the cervical esophagus.

Computational fluid dynamics analysis of the upper airway after rapid maxillary expansion: a case report.

BACKGROUND: Assessment of the upper airway volume, morphology, and mechanics is of great importance for the orthodontic patient. We hypothesize that upper airway dimensions have significant effects on the dynamics of the airway flow and that both the dimensions and mechanics of the upper airway are greatly affected by orthodontic and orthopedic procedures such as rapid maxillary expansion (RME). The aim of the current study was to assess the effect of RME on the airway flow rate and pattern by comparing the fluid dynamics results of pre- and post-treatment finite element models. METHODS: Customized pre- and post-treatment computational fluid dynamics models of the patient's upper airway were built for comparison based on three-dimensional computed tomogram. The inhalation process was simulated using a constant volume flow rate for both models, and the wall was set to be rigid and stationary. Laminar and turbulent analyses were applied. RESULTS: Comparisons between before and after RME airway volume measurements showed that increases were only detected in nasal cavity volume, nasopharynx volume, and the most constricted area of the airway. Pressure, velocity, and turbulent kinetic energy decreased after dental expansion for laminar and turbulent flow. Turbulent flow shows relatively larger velocity and pressure than laminar flow. CONCLUSIONS: RME showed positive effects that may help understand the key reasons behind relieving the symptom of breathing disorders in this patient. Turbulence occurs at both nasal and oropharynx areas, and it showed relatively larger pressure and velocity compared to laminar flow.

Surface electrical stimulation perturbation context determines the presence of error reduction in swallowing hyolaryngeal kinematics.

PURPOSE: Error-based learning (EBL) involves gradually reducing movement errors caused by a perturbation. When the perturbation has been unexpectedly removed, exaggerated movements occur in the opposite direction of a perturbation effect, known as aftereffects. Our goal was to determine whether the perturbation type impacts error reduction or aftereffects in swallowing hyolaryngeal kinematics. METHOD: We perturbed peak hyolaryngeal elevation during swallowing in 16 healthy adults with surface electrical stimulation (SES) in 2 different ways during videofluoroscopy: intermittent SES (I-SES) was applied only during swallowing, and continuous SES (C-SES) was applied during swallowing and during interswallow intervals. In C-SES and I-SES, the onset and offset of the perturbation were unmasked. RESULTS: Only the C-SES perturbation caused error reduction (gradually increasing peak elevation). Aftereffects were absent in both perturbations, unlike findings from our previous study with masked perturbation. Furthermore, the duration of laryngeal vestibule closure (dLVC) increased during the I-SES perturbation but was unchanged during C-SES perturbation. CONCLUSION: EBL of swallowing airway protection events was strongly influenced by the context of the perturbation. These findings also elucidate how the relationship among critical swallowing airway protection events (hyoid peak, laryngeal peak, and dLVC) can be modified during EBL.

Effect of bolus volume on pharyngeal swallowing assessed by high-resolution manometry.

OBJECTIVE: Solid-state high-resolution manometry (HRM) is fast becoming the gold standard for studying pharyngeal and esophageal motility. However, very few studies have ever evaluated the effect of bolus volume on the physiology of swallowing using HRM. We aimed to determine the effect of bolus volume on pressure, duration and velocity of the hypopharynx as well as the upper esophageal sphincter during pharyngeal swallowing using HRM. METHODS: Thirty-four healthy subjects completed nine swallows (3 ml, 5 ml and 10 ml of water, thick liquid, and paste, respectively) in the natural sitting position. Pressure and duration measurements were acquired from the hypopharynx and upper esophageal sphincter (UES) using HRM. The UES residual pressure, UES relaxation duration, maximum preopening UES pressure, maximum postclosure UES pressure, maximum hypopharyngeal pressure, maximum hypopharyngeal pressure rise rate and hypopharyngeal pressure duration were analyzed across bolus volumes using repeated measures of one-way analysis of variance. RESULTS: A significant increase in UES residual pressure associated with increased bolus volume during water and paste swallowing was observed. Furthermore, UES relaxation duration was significantly increased with increasing in bolus volume for all three material swallows. No significant volume effects were found on the hypopharynx. CONCLUSIONS: In summary, bolus volume has a significant effect on the residual pressure and relaxation duration, but no effect on maximum preopening pressure or maximum postclosure pressure of the UES. Maximum hypopharyngeal pressure, maximum hypopharyngeal pressure rise rate and pressure duration were also not affected by bolus volume. Consideration of these variables is paramount in understanding normal and pathological swallowing.

Effect of aging on hypopharyngeal safe volume and the aerodigestive reflexes protecting the airways.

OBJECTIVES/HYPOTHESIS: Studies on young volunteers have shown that aerodigestive reflexes are triggered before the maximum volume of fluid that can safely collect in the hypopharynx before spilling into the larynx is exceeded (hypopharyngeal safe volume [HPSV]). The objective of this study was to determine the influence of aging on HPSV and pharyngo-glottal closure reflex (PGCR), pharyngo-UES contractile reflex (PUCR), and reflexive pharyngeal swallow (RPS). STUDY DESIGN: Comparison between two groups of different age ranges. METHODS: Ten young (25 ± 3 standard deviation [SD] years) and 10 elderly (77 ± 3 SD years) subjects were studied. PGCR, PUCR, and RPS were elicited by perfusing water into the pharynx rapidly and slowly. HPSV was determined by abolishing RPS with pharyngeal anesthesia. RESULTS: Frequency-elicitation of PGCR and PUCR were significantly lower in the elderly compared to the young during slow water perfusion (47% vs. 97% and 40% vs. 90%, respectively, P < .001). RPS was absent in five of the 30 (17%) slow injections in the elderly group. In these elderly subjects, HPSV was exceeded and laryngeal penetration of the water was seen. The threshold volume to elicit PGCR, PUCR, and RPS was significantly lower than the HPSV during rapid injections. Except for RPS, these volumes were also significantly lower than HPSV during slow injections. CONCLUSIONS: PGCR, PUCR, and RPS reflexes are triggered at a threshold volume significantly lower than the HPSV in both young and elderly subjects. Lower frequency-elicitation of PGCR, PUCR, and RPS in the elderly can predispose them to the risks of aspiration.

A video-fiberscopic study of laryngopharyngeal behaviour in the human beatbox.

The human beatbox is the art of reproducing all types of sounds with the mouth while 'adapting' them for better control. To understand how these 'voice virtuosos' juggle with so many different sounds--instrumental, rhythmic, and vocal--at the same time, we have performed a descriptive analysis of three beatboxers by observing their vocal tract behaviour by fiberscopic imaging using an OCM visual scale. From an anatomical-dynamic point of view, beatboxers mobilize all the structures of their laryngopharynx separately. With this first physiological study of the human beatbox, we could observe a well-developed laryngopharyngeal system with extreme articulatory configurations to perform their art.

Skeletal muscle regeneration on protein-grafted and microchannel-patterned scaffold for hypopharyngeal tissue engineering.

In the field of tissue engineering, polymeric materials with high biocompatibility like polylactic acid and polyglycolic acid have been widely used for fabricating living constructs. For hypopharynx tissue engineering, skeletal muscle is one important functional part of the whole organ, which assembles the unidirectionally aligned myotubes. In this study, a polyurethane (PU) scaffold with microchannel patterns was used to provide aligning guidance for the seeded human myoblasts. Due to the low hydrophilicity of PU, the scaffold was grafted with silk fibroin (PU-SF) or gelatin (PU-Gel) to improve its cell adhesion properties. Scaffolds were observed to degrade slowly over time, and their mechanical properties and hydrophilicities were improved through the surface grafting. Also, the myoblasts seeded on PU-SF had the higher proliferative rate and better differentiation compared with those on the control or PU-Gel. Our results demonstrate that polyurethane scaffolds seeded with myoblasts hold promise to guide hypopharynx muscle regeneration.

Isometric and swallowing tongue strength in healthy adults.

OBJECTIVES/HYPOTHESIS: The tongue contributes to a safe swallow. It facilitates bolus control during mastication, maintains a bolus in the oral cavity to prevent premature entry of the bolus into the hypopharynx, and helps generate pressure in the hypopharynx during swallowing. This study examined isometric tongue strength and tongue pressure measured during swallowing in healthy young and older adults. STUDY DESIGN: Prospective group design. METHODS: One hundred twenty-six healthy individuals who were recruited as part of a larger study on swallowing participated in this study. Participants were divided into three age groups: 20 to 40 years, 41 to 60 years, and ≥61 years. A KayPentax Digital Swallowing Workstation with an air-filled bulb array was placed on the tongue of each participant (anterior to posterior). Participants completed three isometric tongue presses and three swallows. RESULTS: Repeated measures analyses of variance revealed a significant main effect of age (P = .01) and gender by tongue bulb location interaction (P = .02) for isometric tongue strength. That is, older adults had lower isometric tongue strength than young adults, and females had a greater difference between anterior and posterior tongue strength than males. Tongue strength during swallowing yielded significantly greater anterior versus posterior tongue pressure. CONCLUSIONS: This study comprises one of the largest in terms of number of healthy participants reported to date and confirms previous findings that isometric tongue strength decreases with age. Furthermore, given young and older adults generate similar swallowing pressures, swallowing is a submaximal strength activity, yet older adults have less functional reserve. LEVEL OF EVIDENCE: 4.

Hyoid expansion with titanium plate and screw: a human cadaveric study using computer-assisted airway measurement.

IMPORTANCE: Hyoid expansion with suspension can potentially increase the upper airway at the hypopharyngeal level, benefitting patients with sleep-related breathing disorder. OBJECTIVES: To document the effect of hyoid expansion using titanium plate and screw on retrolingual hypopharyngeal airway dimension and to compare the airway dimension after isolated hyoid expansion with hyoid expansion + hyomandibular suspension. DESIGN: Anatomical cadaveric dissection study. SETTING: This study was performed in a laboratory setting using human cadavers. INTERVENTION: This is an anatomical feasibility study of hyoid expansion using titanium plate and screw on 10 cadaveric human heads and necks. The hyoid bone is trifractured with bony cuts made just medial to the lesser cornu. The freed hyoid body and lateral segments are expanded and stabilized to a titanium adaptation plate. Computer-assisted airway measurement (CAM) was used to measure the airway dimension at the hypopharynx at the level of the tongue base before and after the hyoid expansion. The expanded hyoid bone was then suspended to the mandible, and the airway dimension was measured again with CAM. MAIN OUTCOMES AND MEASURES: Airway dimension after isolated hyoid expansion with hyoid expansion with hyomandibular suspension. RESULTS Hyoid expansion with titanium plate and screw resulted in statistical significant increase in the retrolingual hypopharyngeal airway space in all of the 10 human cadavers. The mean (SD) increase in retroglossal area was 33.4 (13.2) mm² (P < .005) (range, 6.0-58.7 mm²). Hyoid expansion with hyomandibular suspension resulted in a greater degree of airway enlargement. The mean (SD) increase in retroglossal area was 99.4 (15.0) mm² (P < .005) (range, 81.9-127.5 mm²). CONCLUSIONS AND RELEVANCE: The retrolingual hypopharyngeal airway space increased with hyoid expansion using titanium plate and screw in our human cadaveric study, measured using CAM. The degree of increase is further augmented with hyomandibular suspension.

The effect of bolus viscosity on laryngeal closure in swallowing: kinematic analysis using 320-row area detector CT.

The present study examined the effect of bolus viscosity on the onset of laryngeal closure (relative to hyoid elevation), the duration of laryngeal closure, and other key events of swallowing in ten healthy volunteers. All volunteers underwent 320-row area detector computed tomography swallow studies while swallowing 10 ml of honey-thick barium (5 % v/w) and thin barium (5 % v/w) in a 45° reclining position. Three-dimensional images of both consistencies were created in 29 phases at an interval of 0.10 s (100 ms) over a 2.90-s duration. The timing of the motions of the hyoid bone, soft palate, and epiglottis; the opening and closing of the laryngeal vestibule, true vocal cords (TVC), and pharyngoesophageal segment; and the bolus movement were measured and compared between the two consistencies. The result showed differing patterns of bolus movement for thin and thick liquids. With thin liquids, the bolus reached the hypopharynx earlier and stayed in the hypopharynx longer than with thick liquids. Among events of laryngeal closure, only the timing of TVC closure differed significantly between the two consistencies. With thin liquids, TVC closure started earlier and lasted longer than with thick liquids. This TVC movement could reflect a response to the faster flow of thin liquids. The results suggest that bolus viscosity alters the temporal characteristics of swallowing, especially closure of the TVC.

Swarming generates rebel workers in honeybees.

According to kin selection theory, the colony kin structure of eusocial insects motivates workers' altruistic behaviors and therefore their sterility or restricted reproduction [1]. Indeed, theory and cross-species comparison confirm that workers engage in their own reproduction depending on relatedness among colony members [2, 3]. We show that in a honeybee colony, the workers switch from their typical altruistic role to a more selfish one if at their larval stage there are environmental cues of an upcoming decline in intracolony relatedness. This happens inevitably when a colony multiplies by swarming and replaces the mother queen with her daughter, because the mother queen's workers are faced with rearing the sister queen's offspring related to them half as much as between sisters. Workers developing from the mother queen's eggs immediately after swarming, in a temporarily queenless colony, had more ovarioles in their ovaries and less-developed hypopharyngeal glands producing brood food than control workers reared in queenright conditions. These "rebel" workers were more engaged in laying their own male-determined eggs than in rearing offspring, whether or not the sister queen was present in the colony. The finding of this previously unknown rebel strategy confirms that kin selection shapes both cooperation and conflict in honeybee societies.

Individual-dependent effects of pharyngeal electrical stimulation on swallowing in healthy humans.

The present study tested whether electrical stimulation increases the number of voluntary repetitive swallows in humans. In addition, the potential of initiating both voluntary and involuntary swallows was compared using electrical stimulation. Fourteen normal male adults were instructed to perform repetitive voluntary swallowing as quickly as possible over 30 s, and the number of swallows was counted with and without repetitive electrical stimulation (80% of maximal tolerated intensity; 0.1 ms in pulse duration; 30 Hz) of the nasal cavity, nasopharynx, oropharynx, or laryngopharynx. Although the number of swallows was significantly increased during electrical stimulation of the laryngopharynx, oropharynx, and nasopharynx, there was a wide variation in the number among subjects. The number of reflexively evoked swallows (i.e., involuntary swallows) by pharyngeal stimulation also varied greatly, and there was a significant linear correlation in the number of swallows between voluntary and involuntary swallows. The present study demonstrated the facilitatory effects of pharyngeal electrical stimulation on voluntary swallowing in humans. Furthermore, the potentials of initiation of voluntary swallows are identical to those of involuntary swallows, which suggests that the swallowing central pattern generator is a common component of both neuronal networks and therefore is responsible for inter-individual variations.