The objective of this study was to compare the outcomes of two tongue resistance training protocols. One protocol (“Tongue-Pressure Profile Training”) emphasized the pressure-timing patterns that are typically seen in healthy swallows by focusing on gradual pressure release and saliva swallowing tasks. The second protocol (“Tongue-Pressure Strength and Accuracy Training”) emphasized strength and accuracy in tongue-palate pressure generation and did not include swallowing tasks. A prospective, randomized, parallel allocation trial was conducted. Of 26 participants who were screened for eligibility, 14 received up to 24 sessions of treatment. Outcome measures of posterior tongue strength, oral bolus control, penetration-aspiration and vallecular residue were made based on videofluoroscopy analysis by blinded raters. Complete data were available for 11 participants. Significant improvements were seen in tongue strength and post-swallow vallecular residue with thin liquids, regardless of treatment condition. Stage Transition Duration (a measure of the duration of bolus presence in the pharynx prior to swallow initiation, which had been chosen to capture impairments in oral bolus control) showed no significant differences. Similarly, significant improvements were not seen in median scores on the Penetration-Aspiration Scale. This trial suggests that tongue strength can be improved with resistance training for individuals with tongue weakness following stroke. We conclude that improved penetration-aspiration does not necessarily accompany improvements in tongue strength, however tongue-pressure resistance training does appear to be effective for reducing thin liquid vallecular residue.

Purpose Thickened liquids are frequently used as an intervention for dysphagia, but gaps persist in our understanding of variations in swallowing behavior based on incremental thickening of liquids. The goal of this study was to establish reference values for measures of bolus flow and swallowing physiology in healthy adults across the continuum from thin to extremely thick liquids. Method A sex-balanced sample of 38 healthy adults underwent videofluoroscopy and swallowed 20% weight-to-volume concentration barium prepared in thin and slightly, mildly, moderately, and extremely thick consistencies using a xanthan gum thickener. Participants took comfortable sips and swallowed without a cue; sip volume was measured based on presip and postsip cup weights. A standard operating procedure (the ASPEKT method: Analysis of Swallowing Physiology: Events, Kinematics and Timing) was used to analyze videofluoroscopy recordings. Results The results clarify that, for thin liquid sips (10–14 ml), a single swallow without clearing swallows is typical and is characterized by complete laryngeal vestibule closure, complete pharyngeal constriction, and minimal postswallow residue. Aspiration was not seen, and penetration was extremely rare. Bolus position at swallow onset was variable, extending as low as the pyriform sinuses in 37% of cases. With thicker liquids, no changes in event sequencing, laryngeal vestibule closure, pharyngeal constriction, or postswallow residue were seen. The odds of penetration were significantly reduced. A longer timing interval until onset of the hyoid burst movement was seen, with an associated higher bolus position at swallow onset. Other timing measures remained unaffected by changes in bolus consistency. Conclusion The results include new reference data for swallowing in healthy adults across the range from thin to extremely thick liquids.

The tongue plays a key role in the generation of pressures for transporting liquids and foods through the mouth in swallowing. Recent studies suggest that there is an age-related decline in tongue strength in healthy adults. However, whether age-related changes occur in tongue pressures generated for the purpose of swallowing remains unclear. Prior literature in this regard does not clearly explore the influence of task on apparent age-related differences in tongue pressure amplitudes. Furthermore, differences attributable to variations across individuals in strength, independent of age, have not clearly been elucidated. In this study, our goal was to clarify whether older adults have reduced tongue-palate pressures during maximum isometric, saliva swallowing, and water swallowing tasks, while controlling for individual variations in strength. Data were collected from 40 healthy younger adults (under age 40) and 38 healthy mature adults (over age 60). As a group, the mature participants had significantly lower maximum isometric pressures (MIPs). Swallowing pressures differed significantly by task, with higher pressures seen in saliva swallows than in water swallows. Age-group differences were not seen in swallowing pressures. Consideration of MIP as a covariate in the analysis of swallowing pressures revealed significant correlations between strength and swallowing pressures in the older participant group. Age-group differences were evident only when strength was considered in the model, suggesting that apparent age-related differences are, in fact, explained by differences in strength, which tends to be lower in healthy older adults. Our results show no evidence of independent differences in swallowing pressures attributable to age.

Pharyngeal constriction has been proposed as a parameter that may distinguish functional from impaired swallows. We employed anatomically normalized pixel-based measures of pharyngeal area at maximum constriction, and the ratio of this measure to area at rest, and explored the association between these measures and post-swallow residue using the normalized residue ratio scale (NRRS). Videofluoroscopy data for 5 ml boluses of 22 % (w/v) liquid barium were analyzed from 20 healthy young adults and 40 patients with suspected neurogenic dysphagia. The frames of maximum pharyngeal constriction and post-swallow hyoid rest were extracted. Pixel-based measures of pharyngeal area were made using ImageJ and size-normalized using the squared C2–C4 vertebral distance as a reference scalar. Post-swallow residue and the areas of the vallecular and pyriform sinus spaces were measured on the hyoid rest frame to calculate the NRRSv and NRRSp. The dataset was divided into swallows with residue within or exceeding the upper confidence interval boundary seen in the healthy participants. Mixed model repeated measures ANOVAs were used to compare pharyngeal area (rest, constriction) and the pharyngeal constriction ratio, between individuals with and without residue. Measures of pharyngeal area at maximum constriction were significantly larger (i.e., less constricted, p = 0.000) in individuals with post-swallow residue in either the valleculae or the pyriform sinus. These results support the idea that interventions targeted toward improving pharyngeal constriction have the potential to be effective in reducing post-swallow residue.

Hyoid movement in swallowing is biomechanically linked to closure of the laryngeal vestibule for airway protection and to opening of the upper esophageal sphincter. Studies suggest that the range of hyoid movement is highly variable in the healthy population. However, other aspects of hyoid movement such as velocity remain relatively unexplored. In this study, we analyze data from a sample of 20 healthy young participants (10 male) to determine whether hyoid movement distance, duration, velocity, and peak velocity vary systematically with increases in thin liquid bolus volume from 5 to 20 mL. The temporal correspondence between peak hyoid velocity and laryngeal vestibule closure was also examined. The results show that maximum hyoid position and peak velocity increase significantly for 20 mL bolus volumes compared to smaller volumes, and that the timing of peak velocity is closely linked to achieving laryngeal vestibule closure. This suggests that generating hyoid movements with increased power is a strategy for handling larger volumes.

We would like to congratulate Popa Nita and colleagues [1] for their article exploring the challenges of matching the rheological (i.e. flow) properties of contrast agents used in videofluoroscopy to thickened liquids used in dysphagia management. This article clearly illustrates the complexities of this challenge; however, there are three additional points that we feel would be clinically relevant and important to bring to the attention of the readers of the Dysphagia journal:1. The rheological characteristics of barium preparations need to be understood with respect to how they map to clinical categories of liquid consistency;2. The concentration of barium in commercially available suspensions affects both its visibility on the radiographic image, and the degree to which the suspension leaves a coating on the pharyngeal mucosa; 3.Mixing barium powder into already-thickened liquids may result in further thickening of the liquid.We will provide a brief elaboration on each of these points below. 1) Rheological characteristics of readily available barium preparationsBarium products for gastrointestinal imaging come in the form of powders or ready-mixed liquid suspensions. The Varibar® line of products (EZ-EM Canada, Bracco Diagnostics Inc., www.varibar.com) is specially formulated for oropharyngeal imaging, and is offered in thin, nectar, thin-honey, thick-honey and pudding consistencies. Varibar® products may, however, not be universally available to clinicians who perform videofluoroscopy. Regulatory approval has not yet been granted for the clinical use of Varibar® in countries outside the United States.When access to products like Varibar®, which are tailor made for oropharyngeal exmaination, it is not uncommon to find clinicians using other imaging products in videofluoroscopy; these products may be mixed in ways that differ from the manufacturer guidelines for intended use. For example, Fink and Ross [2] describe an "ultrathin" barium suspension that they mixed by diluting thin liquid Varibar in a 50:50 ratio with water, in attempts to create a stimulus that represents a true thin liquid more closely. Polibar (Bracco Diagnostics Inc., Princeton, NJ) is one ready-mixed liquid suspension with a barium concentration of 100% w/v (g/ml), which is quite commonly assumed to be a nectarthick liquid when it flows out of the bottle. In an article by Cichero, Nicholson and Dodrill [3], the viscosity of room temperature Polibar was reported to be 390 mPa.s at a shear rate of 50 reciprocal seconds, i.e., just above the lower boundary for honey-thick liquids specified in the National Dysphagia Diet (NDD) [4]. The focus of that article was to compare the viscosities of contrast media to infant formulas, and these were found to be markedly different.Recent rheological testing in our lab has explored the viscosity of liquid E-Z-Paque (EZ-EM Canada, Bracco Diagnostics Inc.), a 60% w/v barium suspension, and a diluted version of E-Z-Paque, mixed with water to achieve a 22% w/v barium suspension. These tests were conducted in ...

Thickened liquids are frequently recommended to reduce the risk of aspiration in patients with oropharyngeal dysphagia. Although it has previously been reported that tongue-palate pressures increase when swallowing spoon-thick and semi-solid consistencies compared to thin liquids, relatively little is known about how swallowing behaviors differ when swallowing liquids of nectar- or honey-thick consistency. Furthermore, previous studies have primarily used starch-based thickeners, and little is known about swallowing behaviors with xanthan gum-thickened liquids, which have recently been introduced for dysphagia management. In this study, we measured variations in tongue-palate pressures during the swallowing of liquids thickened to apparent viscosities of 190, 250, and 380 mPa s at 50/s using increasing concentrations of xanthan gum (0.5, 0.63 and 0.87 w/w%). The viscosity differences between these nectar- and honey-thick stimuli were confirmed to exceed sensory perceptual discrimination thresholds. Data were collected from 78 healthy adults in two sex-balanced age-groups (young; mature) and compared to reference values obtained during water swallowing. The results confirm that increased amplitudes of tongue-palate pressure were used when swallowing the thickened liquid stimuli, compared to swallows of water, and for the honey-thick liquid compared to the two nectar-thick liquids. Age-related reductions were seen in tongue strength but not in swallowing pressures, which fell below 40 % of maximum isometric pressure values. Thus, the use of xanthan gum-thickened liquids is unlikely to tax the swallowing system in terms of tongue pressure generation requirements, even in seniors with reduced maximum isometric tongue pressure measures.

Purpose To date, research characterizing swallowing changes in individuals with amyotrophic lateral sclerosis (ALS) has primarily relied on subjective descriptions. Thus, the degree to which swallowing physiology is altered in ALS, and relationships between such alterations and swallow safety and/or efficiency are not well characterized. This study provides a quantitative representation of swallow physiology, safety, and efficiency in a sample of individuals with ALS, to estimate the degree of difference in comparison to published healthy reference data and identify parameters that pose risk to swallow safety and efficiency. Secondary analyses explored the therapeutic effect of thickened liquids on swallowing safety and efficiency. Method Nineteen adults with a diagnosis of probable-definite ALS (El-Escorial Criteria–Revised) underwent a videofluoroscopic swallowing study, involving up to 15 sips of barium liquid (20% w/v), ranging in thickness from thin to extremely thick. Blinded frame-by-frame videofluoroscopy analysis yielded the following measures: Penetration–Aspiration Scale, number of swallows per bolus, amount of pharyngeal residue, degree of laryngeal vestibule closure (LVC), time-to-LVC, duration of LVC (LVCdur), pharyngeal area at maximum constriction, diameter of upper esophageal sphincter opening, and duration of UES opening (UESOdur). Measures of swallow physiology obtained from thin liquid trials were compared against published healthy reference data using unpaired t tests, chi-squared tests, and Cohen’s d effect sizes (adjusted p < .008). Preliminary relationships between parameters of swallowing physiology, safety, and efficiency were explored using nonparametric Cochrane’s Q, Friedman’s test, and generalized estimating equations ( p < .05). Results Compared to healthy reference data, this sample of individuals with ALS displayed a higher proportion of swallows with partial or incomplete LVC (24% vs. < 1%), increased time-to-LVC ( d = 1.09), reduced UESwidth ( d = 0.59), enlarged pharyngeal area at maximum constriction, prolonged LVCdur ( d = 0.64), and prolonged UESOdur ( d = 1.34). Unsafe swallowing (i.e., PAS ≥ 3) occurred more frequently when LVC was partial/incomplete or time-to-LVC was prolonged. Pharyngeal residue was associated with larger pharyngeal areas at maximum constriction. Unsafe swallowing occurred less frequently with extremely thick liquids, compared to thin liquids. No significant differences in pharyngeal residue were observed based on liquid thickness. Conclusions Quantitative videofluoroscopic measurements revealed moderate-to-large differences in swallow physiology between this sample of individuals with ALS and healthy reference data. Increased time-to-LVC, noncomplete LVC, and enlarged pharyngeal area at maximum constriction were associated with impaired swallow safety or efficiency. Thickened liquids may mitigate the risk of acute episodes of aspiration in individuals with ALS. Further work is needed to corroborate these preliminary findings and explore how swallowing profiles evolve throughout disease progression.