Pharyngeal Swallowing Research Articles

Pharyngeal Swallowing Pressures in Patients with Radiation-Associated Dysphagia.

Dysphagia associated with radiotherapy for head and neck cancer is complex and can be difficult to treat. Videofluoroscopic swallow studies (VFSS) are the current gold-standard instrumented swallow assessment. High-resolution manometry (HRM) is an additional approach that provides objective measurements of swallowing-related pressures in the pharynx and esophagus. This can provide functional information on the pressure gradients underlying bolus propulsion, and is relevant for this patient population, where radiation-related fibrosis can lead to weakness and impaired pressure generation. The purpose of this preliminary study was to describe pharyngeal swallowing pressures in patients with radiation-associated dysphagia (RAD) and late radiation-associated dysphagia (LRAD) using HRM. RAD occurs during and immediately following treatment, whereas LRAD is a more recently described phenomenon in which the patient experiences an onset of dysphagia at least 5years post-treatment. We performed a retrospective analysis of pharyngeal swallowing pressures from 21 patients with RAD or LRAD and 21 healthy sex/age-matched controls. Patients with RAD or LRAD exhibited decreased swallowing pressure durations throughout the pharynx (p ≤ 0.002), as well as decreased hypopharynx maximum pressure (p = 0.003) and pharyngeal contractile integral ( p < 0.0001). Understanding how pharyngeal pressure generation is altered in patients with a history of radiotherapy can help clinicians form more precise treatment plans.

Pilot Study of Quantitative Methods for Differentiating Pharyngeal Swallowing Mechanics by Dysphagia Etiology.

Quantitative analysis of modified barium swallow (MBS) imaging is useful to determine the impact of various disease states on pharyngeal swallowing mechanics. In this retrospective proof of concept study, kinematic analysis and computational analysis of swallowing mechanics (CASM) were used to demonstrate how these methods differentiate swallowing dysfunction by dysphagia etiology. Ten subjects were randomly selected from four cohorts of dysphagic patients including COPD, head and neck cancer (HNC), motor neuron disease, and stroke. Each subject was age- and gender-matched with healthy, non-dysphagic controls. MBS videos of 5ml thin and 5ml thick bolus trials from each subject were used. A MATLAB tracker tool was adapted and updated to collect and compile data for each video (n = 160). For kinematic measurements, a MANOVA was performed with post-hoc analyses to determine group differences. For CASM measurements, a morphometric canonical variate analysis with post hoc analysis was performed to determine group differences. Kinematic analyses indicated statistically significant differences between HNC cohort and controls in distance measurements forhyolaryngeal approximation (p = .001), laryngeal elevation (p = 0.0001), pharyngeal shortening (p = 0.0002), and stage transition duration timing (p = 0.002). Timing differences were noted between the stroke cohort and controlsforpharyngeal transit time (p = 0.007). Multivariate morphometric canonical variate analysis showed significant differences between etiology groups (p < 0.0001) with eigenvectors indicating differing patterns of swallowing mechanics. This study demonstrated that swallowing mechanics among cohorts of dysphagic patients can be differentiated using kinematics and CASM, providing different but complementary quantitative methods for investigating the impact of various disease states on swallowing function.

Swallowing Pressure Variability as a Function of Pharyngeal Region, Bolus Volume, Age, and Sex

Within-individual movement variability occurs in most motor domains. However, it is unknown how pharyngeal swallowing pressure varies in healthy individuals. We hypothesized that: 1) variability would differ among pharyngeal regions; 2) variability would decrease with increased bolus volume; 3) variability would increase with age; and 4) there would be no sex differences. Case series. We used pharyngeal high-resolution manometry to measure swallowing pressure in the following regions: velopharynx, tongue base, hypopharynx, and upper esophageal sphincter. Data were collected from 97 healthy adults (41 male) aged 21 to 89 years during thin liquid swallows: 2 mL, 10 mL, and participant-selected comfortable volume. Pressure variability was measured using coefficient of variation. Repeated measures analysis of variance was used to assess impacts of region, bolus volume, age, and sex on pressure variability. There was a significant region × volume interaction (P < .001) and significant main effect of age (P = .005). Pressures in the hypopharynx region were more variable than all other regions (P ≤ .028), and pressures in the tongue base region were less variable than all other regions (P ≤ .002) except at 2 mL volumes (P = .065). Swallowing pressure variability was significantly different in the velopharynx and upper esophageal sphincter regions, with comfortable volume and 2 mL swallows having greater variability than 10 mL swallows (P ≤ .026). Pressure variability significantly increased with increasing age (P = .002). There were no effects of sex on pressure variability (P ≥ .15). Pharyngeal swallowing pressure variability differs according pharyngeal region, volume, and age but not sex. Abnormal swallowing pressure variability may reflect deviations in motor control in persons with swallowing impairment, and results from this study can be used as normative data for future investigations evaluating swallowing pressure generation. 4 Laryngoscope, 131:E52-E58, 2021.

A Systematic Review of the Influence of Bolus Characteristics on Respiratory Measures in Healthy Swallowing.

There have been a number of studies on the effect of bolus volume, consistency, texture, temperature and taste on the oropharyngeal swallowing physiology. However, its influence on the respiratory function associated with swallow is not well understood. This study aimed at systematically analysing and documenting the prevailing research literature on respiratory functions before, during, and after healthy swallows of boluses with varied characteristics. The PRISMA guidelines were followed for retrieval of relevant research. From among the 48,329 reports screened for inclusion criteria, 25 articles were included for data extraction. Each of these reports was evaluated for its design, methodology and reporting quality and also the level of evidence provided by them. The results revealed that the scientific evidence in this regard was restricted to level II. Majority of the studies included considered bolus volume as the variable than bolus consistency, taste or temperature. Expiratory phase was preferred surrounding the apnea irrespective of volume, consistency or taste but changed with temperature variations across age groups. The reports are equivocal on the duration of respiratory apnea, and length of respiratory cycles before and after the apnea. The temporal coordination of pharyngeal swallow events was found to be independent of bolus volume. This review concluded that bolus characteristics have differential effects on the respiratory functions during swallow beyond a 'central sensory threshold' level. Objective standardization of bolus characteristics may be the immediate requirement for generalization of future research findings in this direction.

Relationship Between Tongue Pressure and Pharyngeal Function Assessed Using High-Resolution Manometry in Older Dysphagia Patients with Sarcopenia: A Pilot Study.

Tongue pressure is often used to evaluate swallowing muscle strength in dysphagia patients with sarcopenia. However, the amount of tongue pressure that reflects pharyngeal swallowing function is unclear. The aims of this descriptive study were (1) to assess the association between tongue pressure and swallowing function using high-resolution manometry (HRM), (2) to evaluate whether manometric parameters were related to maximum tongue pressure (MTP) and other sarcopenia-related factors, and (3) to evaluate the manometric characteristics of pharyngeal swallowing in sarcopenic dysphagia. Sixteen patients with dysphagia (13 men; mean age 85.0 ± 6.6) who were diagnosed with sarcopenia and sixteen healthy subjects (10 men; mean age 33.6 ± 7.2) were included. Evaluation of HRM parameters including velopharyngeal contractile integral (VPCI), mesohypopharyngeal contractile integral (MHPCI), upper esophageal sphincter (UES) relaxation duration, and UES nadir pressure was performed. HRM parameters of patients were compared with MTP, sarcopenia factors, and manometric parameters of healthy subjects. The VPCI showed no statistically significant differences between patient and healthy groups. In the patient group, the MHPCI was significantly lower (126.1 ± 76.6 vs 193.2 ± 34.1mmHgcms; p = 0.003), UES nadir pressure was significantly higher (10.5 ± 27.5 vs -11.2 ± 6.7mmHg; p < 0.001), and UES relaxation duration (318.0 ± 152.4 vs 520.6 ± 60.0ms; p = 0.007) was significantly shorter than those in the healthy group. HRM parameters were not significantly correlated with MTP and sarcopenia factors. Older dysphagia patients with sarcopenia had weaker pharyngeal contractility and UES dysfunction. Manometric evaluation of pharyngeal function may not be significantly associated with MTP and sarcopenia-related factors. Further study is needed to clinically apply tongue pressure for evaluating sarcopenic dysphagia.

The effects of tongue pressure resistance feedback training on post-stroke dysphagia

Objective To explore the clinical utility of tongue pressure resistance feedback training in the treatment of post-stroke dysphagia. Methods Twenty stroke survivors with dysphagia were randomly divided into an experimental group and a control group. Both groups were given conventional swallowing rehabilitation training, while the experimental group was additionally provided with tongue pressure resistance feedback training. Before and after the treatment, MBSImp analysis and the Rosenbek penetration aspiration scale were used to quantify the control of the tongue, food delivery, oral residue, laryngeal elevation, hyoid bone movement, epiglottis turnover, larynx closure, vestibular larynx closure, pharyngal peristalsis and contraction, opening of the upper esophageal sphincter UES, contraction of the base of the tongue, pharyngeal residue and aspiration. Results No significant differences were observed between the two groups before the intervention. Afterward the average pharyngeal period and aspiration score of the experimental group had decreased significantly compared with the control group′s values. Conclusions Tongue pressure resistance feedback training is effective in improving pharyngeal swallowing and reducing the risk of aspiration after swallowing. Key words: Tongue pressure resistance feedback training; Stroke; Dysphagia

Obstructive sleep apnea syndrome (OSAS) and swallowing function-a systematic review.

The purpose of this systematic review was to summarize and qualitatively analyze published evidence elucidating the prevalence of dysphagia and detail alterations in swallowing function in patients with OSAS. Computerized literature searches were performed from four search engines. The studies were selected based on the inclusion and exclusion criteria. The studies were screened using Covidence (Cochrane tool) and followed the Preferred Reporting Items for Systematic Reviews and Meta-Analyses statement standards (PRISMA-2009). A total 2645 studies were initially retrieved, of which a total of 17 studies met inclusion criteria. Two reviewers, blinded to each other, evaluated level and strength of evidence using the Oxford Centre for Evidence-based Medicine Levels of Evidence and QualSyst, respectively. Dysphagia prevalence ranged from 16 to 78% among the eligible studies. Studies varied in operational definitions defining swallowing dysfunction (dysphagia) and method used to assess swallowing function. Approximately 70% of eligible studies demonstrated strong methodological quality. The majority of studies (n = 11; 65%) reported pharyngeal swallowing impairments in patients with OSAS, including delayed initiation of pharyngeal swallow and penetration/aspiration. This systematic review describes swallowing function in patients with OSAS. However, due to the variability in defining OSAS and dysphagia, in the assessment method used to determine dysphagia, and heterogeneity of study designs, true prevalence is difficult to determine. Clinicians involved in the management of OSAS patients should employ validated assessment measures to determine if swallow dysfunction is present.

Endoscopic Submucosal Dissection of the Angiolipoma at Hypopharynx-Esophageal Introitus.

Angiolipoma in the region of the hypopharynx-esophageal introitus is a rare occurrence. Surgical treatment was performed in the few cases reported in the literature. Endoscopic submucosal dissection (ESD) is a minimally invasive treatment for hypopharyngeal and esophageal lesions. Our objective was to evaluate the feasibility, safety, and efficacy of ESD for treatment of angiolipoma at the hypopharynx-esophageal introitus. The patients with submucosal tumors at the hypopharynx-esophageal introitus were diagnosed as angiolipoma by preoperative evaluation with endoscopy, endoscopic ultrasonography, and computed tomography (CT). The patients who were diagnosed with angiolipoma agreed to undergo endoscopic submucosal dissection. Under general anesthesia and endotracheal intubation, ESD was used to remove the lesions. Preoperative, intraoperative, and postoperative data were collected and analyzed to evaluate the feasibility, safety, and effectiveness of endoscopic submucosal dissection. From January 2013 to December 2018, 6 cases of angiolipoma were treated with ESD with a success rate of 100%. The average operation time was 107.0 ± 69.4 minutes. Intraoperative blood loss is the main risk. Endoscopic thermocoagulation successfully stopped bleeding in all cases. Pharyngeal pain and painful swallowing were the main clinical signs. There was no stricture at the hypopharynx-esophageal introitus after the operation. ESD treatment of angiolipoma at hypopharynx-esophageal introitus is feasible, safe, and effective.

Adaptations to Oral and Pharyngeal Swallowing Function Induced by Injury to the Mylohyoid Muscle.

Muscle injury is a frequent side effect of radiation treatment for head and neck cancer. To understand the pathophysiology of injury-related dysfunction, we investigated the effects of a single muscle injury to the mylohyoid on oropharyngeal swallowing function in the rat. The mylohyoid protects the airway from food/liquid via hyolaryngeal elevation and plays an active role during both oral and pharyngeal swallowing. We hypothesized (1) that fibrosis to the mylohyoid alters swallowing bolus flow and licking patterns and (2) that injury to the mylohyoid changes normal activity of submental, laryngeal, and pharyngeal muscles during swallowing. A chilled cryoprobe was applied to the rat mylohyoid muscle to create a localized injury. One and two weeks after injury, swallowing bolus transit was assessed via videofluoroscopy and licking behavior via an electrical lick sensor. The motor activity of five swallow-related muscles was analyzed immediately after injury using electromyography (EMG). Comparisons were made pre- and post-injury. Fibrosis was confirmed in the mylohyoid at 2 weeks after injury by measuring collagen content. One week after injury, bolus size decreased, swallowing rate reduced, and licking patterns were altered. Immediately post-injury, there was a significant depression in mylohyoid and thyropharyngeus EMG amplitudes during swallowing. Our results demonstrated that injury to the mylohyoid is sufficient to cause changes in deglutition. These disruptions in oral and pharyngeal swallowing were detected prior to long-term fibrotic changes, including delays in tongue movement, alterations in bolus flow, and changes in sensorimotor function. Therefore, injuring a single important swallowing muscle can have dramatic clinical effects.

Application of agar thickener in dysphagia after radiotherapy for nasopharyngeal carcinoma

Objective To compare a new agar thickener with xanthan gum as a thickener in treating dysphagia patients with nasopharyngeal carcinoma after radiotherapy. Methods Twenty nasopharyngeal carcinoma patients with dysphagia after radiotherapy were asked to swallow moderately and extremely thick liquids thickened with the agar and xanthan gum, and their swallowing was recorded with a videofluoroscope. Results The average pharyngeal constriction ratio when swallowing agar thickener was significantly lower than when swallowing the traditional thickener. The average oral transit time, the initiation of pharyngeal swallowing were both significantly quicker. There was no significant difference in the average penetration aspiration scale scores between the two thickeners. In the subjective evaluation, the agar thickener was adjudged smoother and with better residual mouthfeel than the xanthan gum, but the scent of the xanthan gum was preferred. Conclusion The new agar thickener is smooth and not sticky. It produces faster transport with less oropharyngeal residue. It can be widely used among nasopharyngeal carcinoma patients with dysphagia after radiotherapy. Key words: Thickeners; Nasopharyngeal carcinoma; Dysphagia; Agar; Xanthan gum

Fiberoptic Endoscopic Evaluation of Swallowing in Infants and Children: Protocol, Safety, and Clinical Efficacy: 25 Years of Experience.

The application of fiberoptic endoscopic evaluation of swallowing (FEES) in the pediatric dysphagia protocol requires specialized knowledge of pediatric conditions that result in dysphagia, recognition of normal and abnormal laryngopharyngeal anatomy and function across ages, and the ability to identify maturational changes in anatomy and function of the aerodigestive tract that pertain to airway protection and swallowing function. Over the past 25 years, we have performed over 7,000 collaborative Otolaryngology and Speech-Language Pathology FEES examinations in patients ranging from 2 days of age to young adults. During this time period, we have monitored the safety of the procedure, explored the feasibility and utility of FEES across conditions, compared and contrasted FEES to the videofluoroscopic evaluation of swallowing (VFSS), and developed specific pediatric FEES protocols with operational definitions for identification and interpretation of swallowing parameters. FEES has proved to be a safe procedure in patients across ages. There have been no significant adverse events. FEES is comparable to the VFSS in the assessment of events before and after the swallow. It provides unique information regarding laryngopharyngeal anatomy and function, airway protection integrity, sensory threshold, and secretion management ability, as well as pharyngeal swallowing dynamics and the efficacy of compensatory swallowing strategies. There are specific indications and contraindications for pediatric FEES, and unique components that characterize the pediatric FEES protocols across ages and conditions. FEES procedures performed jointly by an Otolaryngologist and Speech-Language pathologist offer a team approach to interpretation and management recommendations.

Pharyngeal swallowing mechanics associated with upper esophageal sphincter pressure wave.

Opening of the upper esophageal sphincter (UES) is a critical element of swallowing. Understanding the functional pharyngeal anatomy during UES opening would be clinically useful for dysphagia evaluation and treatment. Simultaneous high-resolution pharyngeal manometry and videofluoroscopy (VFS) videos for 18 nondysphagic subjects were evaluated. UES pressure readings were segmented into six pressure phases, including a poorly understood pre-relaxation contraction. Anatomic landmarks were tracked in VFS imaging and evaluated morphometrically to determine the movement of key swallowing structures within each UES pressure phase. There were significant differences in pharyngeal mechanics by UES pressure stage (range of D-values = 1.7-2.2, P < .0001). The soft palate maximally elevates during the pre-relaxation contraction of the UES. Early during UES relaxation, the hyolaryngeal complex and pharyngeal structures maximally elevate and pharyngeal structures constrict around the bolus. The mechanics underlying the UES pressure wave suggest generation of a sealed pharyngeal cavity, possibly integral to pharyngeal pressure generation and bolus propulsion.

AGE-RELATED FUNCTIONAL RESERVE DECLINE IS NOT SEEN IN PHARYNGEAL SWALLOWING PRESSURES

Age-related decline in functional reserve has been described in tongue strength: tongue pressure during swallowing does not change with age, but maximal-effort isometric tongue pressure decreases with age. Healthy persons show a slight increase in pharyngeal swallowing pressure with age, but it is unknown if there is a similar decline in functional reserve. Fifty-six healthy adults (n=38 60 years) underwent pharyngeal high-resolution manometry during effortful and normal-effort thin liquid swallows. Repeated measures ANOVAs were performed on maximum pressures, pharyngeal contractile integral (PCI), pharyngeal pressure gradients, and upper esophageal sphincter minimum pressures. We hypothesized that older individuals would generate a less-robust pressure increase with effortful swallowing than younger individuals. Maximum pressures, PCI, and gradients increase during effortful swallowing (p<0.001), but there was no interaction effect with age, suggesting a lack of age-related functional reserve decline. Older individuals had greater UES minimum pressures than younger individuals in the effortful swallowing task (p=0.03), which may stem from reduced muscular compliance in this area. These findings do not align with those reported in tongue pressures, suggesting that muscle properties and pressure generation may be fundamentally different between the pharynx and the oral tongue. Alternatively, the effortful swallowing task may not elicit maximum contractility of the pharyngeal musculature. The preserved ability to increase pharyngeal pressure during effortful swallowing may support the use of the effortful swallow exercise in older adults with swallowing disorders.

Unsafe Chewing: Choking and Other Risks

Unsafe Chewing: Choking and Other Risks

Dysphagia in Progressive Supranuclear Palsy.

Progressive supranuclear palsy (PSP) is the most common Parkinson-Plus syndrome and is associated with early onset of dysphagia relative to Parkinson Disease. The current study contributes to the growing understanding of swallowing dysfunction in PSP by describing oropharyngeal swallowing characteristics in a large prospective cohort of participants with PSP employing a nationally standardized videofluoroscopy protocol and a disease severity scale developed expressly for PSP. Participants were 51 adults diagnosed with PSP. Each participant underwent a clinical interview and standardized videofluorographic assessment. Swallowing function was characterized with the Modified Barium Swallow Impairment Scale (MBSImP) and Penetration-Aspiration Scale (PAS). Variables of interest were participant-reported difficulties with liquids and/or solids; overall impression score for each of the 17 individual MBSImP components, as well as Oral Total Sum and Pharyngeal Total Sum; and PAS. Data were described with median interquartile range, counts, and proportions. Spearman's rank correlations were calculated between MBSImP scores and participant-reported indices, FOIS, and PSP Rating Scale. Approximately two-thirds of participants reported difficulties with liquids, solids, or both, although fewer than 15% reported modifying consistencies. Videofluorographic findings included predominant oral phase impairments, including back and forth rocking motion of the tongue, delayed initiation of the pharyngeal swallow, and oral residue. Pharyngeal phase impairments were relatively infrequent and comparatively mild, with the exception of reduced tongue base retraction contributing to pharyngeal residue, and mildly disrupted laryngeal vestibule closure. Disease severity correlated significantly with oral (r = .0.42, p = .0.002) and pharyngeal (r = 0.41, p = .0.003) total sum scores as well as with the oral phase components of oral transport (r = .0.33, p = .0.02) and initiation of the pharyngeal swallow (r = .0.38, p = .0.007), and PAS for thin liquids (r = .0.44, p = .0.001). The PSP Rating Scale was not more strongly correlated with swallowing impairment than has been reported for other disease severity rating scales. Dysphagia is a common complaint of patients with PSP. The current findings corroborate and expand upon those reported in the literature, detailing relatively more frequent and more severe oral phase impairments and relatively spared hyolaryngeal excursion. Further research is needed to characterize the progression of dysphagia in PSP and to determine whether dysphagia varies in character or in rate of progression across variants of PSP.

Capturing infant swallow impairment on videofluoroscopy: timing matters.

Infant videofluoroscopic swallow studies (VFSSs) require clinicians to make determinations about swallowing deficits based on a limited number of fluoroscopically observed swallows. Although airway protection is known to decline throughout a bottle-feed, the paucity of data regarding the timing of this degradation has limited the development of procedural protocols that maximize diagnostic validity. We tested the stability of key components of swallow physiology and airway protection at four standardized timepoints throughout the VFSS. Thirty bottle-fed infants with clinical signs of swallow dysfunction underwent VFSS. Fluoroscopy was turned on to allow visualization of five swallows at 0:00, 0:30, 1:30 and 2:30 (minutes:seconds [min:s]). We evaluated swallows for components of swallow physiology (oral bolus hold, initiation of pharyngeal swallow, timing of swallow initiation) and airway protection (penetration, aspiration). We used model-based linear contrasts to test differences in the percentage of swallows with low function component attributes. All components of swallow physiology exhibited a change throughout the VFSS (P≤0.0005). Changes were characterized by an increase in the number of sucks per swallow (P<0.0001), percentage of swallows with incomplete bolus hold (P=0.0005), delayed initiation of pharyngeal swallow (P<0.0001), delayed timing of swallow initiation (P=0.0004) and bolus airway entry (P<0.0001). These findings demonstrate that infants with dysphagia exhibit a change in swallow physiology throughout the videofluoroscopic swallow exam. Fluoroscopic visualization that is confined to the initial swallows of the bottle feed limit the exam's diagnostic validity. Developing evidence-based procedural guidelines for infant VFSS execution is crucial for maximizing the exam's diagnostic and treatment yield.

Pharyngeal Residue and Swallowing Treatment Recommendations After Stroke

To determine the degree of association between area of pharyngeal residue and swallow screen and ordinal pharyngeal residue rating, as well as the extent to which these measures drive therapy recommendations.

Relationship of CT Radiomics and Dose Texture to Radiation-Induced Swallow Dysfunction in Head and Neck Cancer

Recent studies have shown that radiotherapy (RT) dosimetry is associated with an increased incidence of dysphagia in head and neck cancer (HNC) patients. The purpose of this work was to develop a dysphagia model using a comprehensive atlas of swallow-related structures to determine the predictive value of imaging and dose features of HNC patients who were evaluated for dysphagia after RT. We hypothesized that imaging and dosimetry features would be significantly correlated to patient reported scores of dysphagia. CT images and dysphagia scores were prospectively collected in HNC patients. We used the 3 month post-RT patient reported Sydney Swallow Questionnaire (SSQ) that has been validated to measure pharyngeal swallow as the primary endpoint. CT images were acquired prior to RT at the time of simulation. Swallow-related structures identified as important to swallow function (e.g. ipsi/contralateral parotid and submandibular glands [iPG, cPG, iSG, cSG], middle constrictors [MPC], anterior and posterior digastrics [ADM, PDM], mylohyoid [MHM], genioglossus [GGM], hyoglossus [HM], and cricopharyngeus [CP]) were segmented. For each segmented salivary gland, high-dimensional image features were extracted from CT images using a python software package. For each swallow-related structure, high-dimensional features were extracted from the structure’s dose distribution. Major categories of extracted features included shape, first order statistics, gray level co-occurrence matrix (GLCM), gray level run length matrix (GLRLM), and gray level size zone matrix (GLSZM). Multivariate regression was performed using the Enter method to identify the predictors of SSQ. The variables considered for modeling were chosen based on statistically significant univariate relationships with SSQ (p<0.005). All statistical analysis was performed in statistical software. In 136 patients, total SSQ at 3 months post-RT was correlated with the MHM D10, GLCM informational measure of correlation of dose, and GLSZM gray level non-uniformity of dose; cSG minimum dose and D10, HM minimum dose; and MPC GLCM inverse difference of dose (r>0.30, p<0.005). In terms of CT image features, SSQ was related to cPG GLCM cluster shade and prominence, iSG GLCM difference variance, and iPG GLCM correlation (r>0.30, p<0.005). In a multivariate analysis (R=0.65, p<0.001), CT iPG GLCM correlation, iSG GLCM difference variance, MPC inverse difference of dose and MHM D10 contributed significantly to the model (p<0.05). Salivary gland image features of CT intensity heterogeneity such as the iSG difference variance as well as the dose to 10% of the MHM and homogeneity of the dose to the MPC (identified by the inverse difference of dose) were significant predictors of dysphagia post-RT. These results suggest that both salivary structure and dose to swallow muscles are important dysphagia predictors and the promise of this approach for a comprehensive RT-dysphagia model.

Functional Anatomy Underlying Pharyngeal Swallowing Mechanics and Swallowing Performance Goals

Purpose Rehabilitation of pharyngeal swallowing dysfunction requires a thorough understanding of the functional anatomy underlying the performance goals of pharyngeal swallowing. These goals include the safe and efficient transfer of a bolus through the hypopharynx into the esophagus. Penetration or aspiration of a bolus threatens swallowing safety. Bolus residue indicates swallowing inefficiency. Several primary mechanics, or elements of the swallowing mechanism, underlie these performance goals, with some elements contributing to both goals. These primary mechanics include velopharyngeal port closure, hyoid movement, laryngeal elevation, pharyngeal shortening, tongue base retraction, and pharyngeal constriction. Each element of the swallowing mechanism is under neuromuscular control and is therefore, in principle, a potential target for rehabilitation. Secondary mechanics of pharyngeal swallowing, those movements dependent on primary mechanics, include opening the upper esophageal sphincter and epiglottic inversion. Conclusion Understanding the functional anatomy of pharyngeal swallowing underlying swallowing performance goals will facilitate anatomically informed critical thinking in the rehabilitation of pharyngeal swallowing dysfunction.

Videofluoroscopic swallow study features of lower esophageal sphincter achalasia-like syndrome in dogs.

BackgroundMegaesophagus (ME) carries a poor long‐term prognosis in dogs. In people, lower esophageal sphincter (LES) disorders causing functional obstruction are rare causes of ME that may respond to targeted treatment. Functional LES disorders are reported rarely in dogs because of challenges in diagnostic methodologies.Hypothesis/ObjectivesTo identify dogs with videofluoroscopic swallow study (VFSS) features of LES achalasia‐like syndrome (LES‐AS). We hypothesized that dogs with LES‐AS could be distinguished from normal dogs using standardized VFSS criteria.AnimalsDogs with LES‐AS by VFSS (n = 19), healthy normal dogs (n = 20).MethodsRetrospective study. One‐hundred thirty dogs presented to the University of Missouri Veterinary Health Center (MU‐VHC) between April 2015 and December 2017 for a free‐feeding VFSS; 20 healthy dogs were included as controls. Swallow studies were evaluated for failure of the LES to relax during pharyngeal swallow (LES‐AS). Affected dogs subsequently were evaluated using standardized criteria to identify metrics important for identifying and characterizing dogs with LES‐AS.ResultsNineteen dogs with LES‐AS were identified out of 130 VFSS. Megaesophagus was present in 14 of 19 (73.7%) dogs with LES‐AS. A baseline esophageal fluid‐line and “bird beak” were present in 68.4% (95% confidence interval [CI], 47.5%‐89.3%) and 63.2% (95% CI, 41.5%‐84.8%) of affected dogs, respectively. The esophagus was graded as acontractile (8/19), hypomotile (8/19), or hypermotile (3/19).Conclusions and Clinical ImportanceDogs with LES‐AS may successfully be identified by VFSS using a free‐feeding protocol. These data are of critical clinical importance because a subpopulation of dogs with functional LES obstruction may be candidates for targeted intervention.