Reference Values for Healthy Swallowing Across the Range From Thin to Extremely Thick Liquids

Establishing a method for quantifying spinal curvature during videofluoroscopic swallow studies: Applying the modified Cobb angle to healthy young and older adults

The Cobb angle is traditionally used for quantifying the degree of spinal curvature through evaluation of the full spinal cord. When conducting measurements on videofluoroscopy swallowing studies (VFSS), the Cobb angle can measure degree of cervical vertebrae curvature, which may have implications for swallowing. Given that this measure may have utility in dysphagia research, the reliability of this measure taken from C2-C4 and establishing the presence of changes with age were the focus of the current, proof-of-principle study. VFSS from 19 healthy young adults and 39 healthy older adults were retrospectively analyzed. The C2-C4 Cobb angle was measured between cervical vertebrae two and four on frames of laryngeal vestibule closure (LVC) and post-swallow rest. Results revealed excellent levels of inter- and intra-rater reliability for frame of post-swallow rest (ICCs = 0.788 and 0.793), and fair to good levels of agreement for frame of LVC (ICCs = 0.667 and 0.621). Significant differences in the C2-C4 Cobb angle were found between the healthy young and old data (p < 0.01). Healthy younger adults had a mean angle of 5.8±9.0 degrees at LVC and 7.7±4.5 degrees at swallow rest, whereas healthy older adults had a mean angle of 12.5±9.0 degrees at LVC and 12.4±9.7 degrees at rest. Consistent with the existing spine literature, the curvature of cervical vertebrae appears to increase with age. With established reliability, we propose that the C2-C4 Cobb angle may be used to determine the degree of spinal curvature in a variety of patient populations in order to determine impacts on swallowing function.

Mechanisms of Impaired Swallowing on Thin Liquids Following Radiation Treatment for Oropharyngeal Cancer

Purpose Dysphagia is one of the most debilitating chronic symptoms experienced by patients who undergo radiation treatment for head and neck cancer. Despite the high prevalence of dysphagia in patients with head and neck cancer, we lack understanding of the specific changes in swallowing physiology that arise in the short-term following radiation therapy and how these changes impact the key functions of swallowing safety and efficiency. This study sought to identify pathophysiological mechanisms underlying impairments in swallowing safety and efficiency on thin liquids following (chemo)radiation for oropharyngeal cancer. Method Videofluoroscopic swallowing studies were completed in 12 male patients within 6 months following completion of (chemo)radiation and in 12 healthy male controls. To compare swallowing function and physiology between groups, we analyzed three discrete sips of 20% w/v thin liquid barium per participant. The videofluoroscopic swallowing study recordings were rated for swallowing safety, efficiency, timing parameters, and pixel-based measures of structural area or movement. Results The oropharyngeal cancer cohort displayed significantly higher frequencies of penetration-aspiration, incomplete laryngeal vestibule closure, prolonged time-to-laryngeal vestibule closure, and poor pharyngeal constriction. Incomplete or delayed laryngeal vestibule closure was associated with airway invasion, while poor pharyngeal constriction was associated with pharyngeal residue. Conclusions This study highlights the primary mechanisms behind impaired safety and efficiency of the swallow in patients following (chemo)radiation for oropharyngeal cancer.

Visuoperceptual Analysis of the Videofluoroscopic Study of Swallowing: An International Delphi Study

INTRODUCTION

The Videofluoroscopic Swallow Study (VFSS) is a commonly used dysphagia assessment that is routinely analysed visuoperceptually. However, no consensus exists regarding which visuoperceptual measures should be used to analyse VFSSs. Current visuoperceptual measures for VFSSs are limited by poor quality and incomplete or indeterminate psychometric properties.

OBJECTIVE

This study aimed to establish the content validity for a new visuoperceptual VFSS measure for oropharyngeal dysphagia in adults, by identifying relevant domains of the construct and generating items and corresponding response scales.

METHODS

Consensus among experts in dysphagia and VFSS from over 20 countries was achieved across three rounds of anonymous online surveys, using the Delphi technique. Participants judged relevance and comprehensiveness of definitions of visuoperceptual domains of VFSS and the relevance of various domains to the overall construct. After reaching consensus on definitions of relevant domains, consensus on items were established using the same process.

RESULTS

Participants achieved consensus on definitions of 32 domains recommended for analysis, and at least one item per domain (range 1-4). Domains selected by participants included both those which occur in existing measures and domains which have not been included in any measures to date. This study will form the basis for content validity of a new measure for VFSS.

CONCLUSIONS

This first phase of developing a visuoperceptual measure of VFSS resulted in the identification of 32 domains and 60 items for oropharyngeal dysphagia. Developers can now advance to the next phase of measure construction; prototype development and psychometric testing.

Swallowing, Chewing and Speaking: Frequently Impaired in Oculopharyngeal Muscular Dystrophy

Background:

Oculopharyngeal muscular dystrophy (OPMD) is a late onset progressive neuromuscular disorder. Although dysphagia is a pivotal sign in OPMD it is still not completely understood.

Objective:

The aim of this study was to systematically investigate oropharyngeal functioning in a large OPMD population.

Methods:

Forty-eight genetically confirmed OPMD patients completed questionnaires, performed clinical tests on swallowing, chewing, speaking, tongue strength and bite force, and underwent videofluoroscopy of swallowing. Descriptive statistics was used for all outcomes and logistic regression to investigate predictors of abnormal swallowing.

Results:

Eighty-two percent reported difficulties with swallowing, 27% with chewing and 67% with speaking. Patients performed significantly worse on all oropharyngeal tests compared to age-matched controls except for bite force. Also asymptomatic carriers performed worse than controls: on chewing time, swallowing speed and articulation rate. During videofluoroscopy, all patients (except one asymptomatic) had abnormal residue and 19% aspirated. Independent predictors of abnormal residue were reduced swallowing capacity for thin liquids (OR 10 mL = 0.93; 20 mL = 0.95) and reduced tongue strength for thick liquids (OR 10 mL = 0.95); 20 mL = 0.90). Aspiration of thin liquids was predicted by disease duration (OR = 1.11) and post-swallow residue with 20 mL (OR = 4.03).

Conclusion:

Next to pharyngeal dysphagia, chewing and speaking are also frequently affected in OPMD patients, even in asymptomatic carriers. Residue after swallowing is a very early sign, while aspiration is a later sign in OPMD. For clinical follow-up monitoring of subjective complaints, swallowing capacity and tongue strength seems relevant.

Swallowing, Chewing and Speaking: Frequently Impaired in Oculopharyngeal Muscular Dystrophy

BACKGROUND

Oculopharyngeal muscular dystrophy (OPMD) is a late onset progressive neuromuscular disorder. Although dysphagia is a pivotal sign in OPMD it is still not completely understood.

OBJECTIVE

The aim of this study was to systematically investigate oropharyngeal functioning in a large OPMD population.

METHODS

Forty-eight genetically confirmed OPMD patients completed questionnaires, performed clinical tests on swallowing, chewing, speaking, tongue strength and bite force, and underwent videofluoroscopy of swallowing. Descriptive statistics was used for all outcomes and logistic regression to investigate predictors of abnormal swallowing.

RESULTS

Eighty-two percent reported difficulties with swallowing, 27% with chewing and 67% with speaking. Patients performed significantly worse on all oropharyngeal tests compared to age-matched controls except for bite force. Also asymptomatic carriers performed worse than controls: on chewing time, swallowing speed and articulation rate. During videofluoroscopy, all patients (except one asymptomatic) had abnormal residue and 19% aspirated. Independent predictors of abnormal residue were reduced swallowing capacity for thin liquids (OR 10 mL = 0.93; 20 mL = 0.95) and reduced tongue strength for thick liquids (OR 10 mL = 0.95); 20 mL = 0.90). Aspiration of thin liquids was predicted by disease duration (OR = 1.11) and post-swallow residue with 20 mL (OR = 4.03).

CONCLUSION

Next to pharyngeal dysphagia, chewing and speaking are also frequently affected in OPMD patients, even in asymptomatic carriers. Residue after swallowing is a very early sign, while aspiration is a later sign in OPMD. For clinical follow-up monitoring of subjective complaints, swallowing capacity and tongue strength seems relevant.

How Important Is Randomization of Swallows During Kinematic Analyses of Swallow Function?

Purpose In dysphagia research involving kinematic analyses on individual swallow parameters, randomization is used to ensure judges are not influenced by judgments made for other parameters within the same swallow or by judgments made for other swallows from the same participant. Yet, the necessity of randomizing swallows to avoid bias during kinematic analyses is largely assumed and untested. This study investigated whether randomization of the order of swallows presented to judges impacts analyses of temporal kinematic events from videofluoroscopic swallow studies. Method One hundred twenty-seven swallows were analyzed from 18 healthy adults who underwent standardized videofluoroscopic swallow studies. Swallows were first analyzed by two trained raters sequentially, analyzing all kinematic events within each swallow, and then a second time in random order, measuring one kinematic event at a time. Intrarater reliability measurements were calculated between random and sequential swallow judgments for all kinematic events using intraclass correlation coefficient and percent exact agreement within a three-frame tolerance. Results Intraclass correlation coefficients (1.00) and percent exact agreement (89%) were excellent for all kinematic events between analyses methods, indicating there were no significant differences in measurements performed in random or sequential order. Conclusions This study provides preliminary evidence that randomization may be unnecessary during temporal swallow kinematic data analyses for research, which may lead to more efficient analyses and dissemination of findings, and alignment of findings with clinical interpretations. Replication of this design with swallows from people with dysphagia would strengthen the generalizability of the results.

The Risk of Penetration-Aspiration Related to Residue in the Pharynx

Purpose Reference data from healthy adults under the age of 60 years suggest that the 75th and 95th percentiles for pharyngeal residue on swallows of thin liquids are 1% and 3%(C2-4)2, respectively. We explored how pharyngeal residue below versus above these values prior to a swallow predicts penetration-aspiration. Method The study involved retrospective analysis of a previous research data set from 305 adults at risk for dysphagia. Participants swallowed six thin boluses and three each of mildly, moderately, and extremely thick barium in videofluoroscopy. Raters measured preswallow residue in %(C2-4)2 units and Penetration-Aspiration Scale (PAS) scores for each swallow. Swallows were classified as (a) "clean baseline" (with no preswallow residue), (b) "clearing" swallows of residue with no new material added, or (c) swallows of "additional material" plus preswallow residue. Frequencies of PAS scores of ≥ 3 were compared across swallow type by consistency according to residue severity (i.e., ≤ vs. > 1%(C2-4)2 and ≤ vs. > 3%(C2-4)2. Results The data set comprised 2,541 clean baseline, 209 clearing, and 1,722 swallows of additional material. On clean baseline swallows, frequencies of PAS scores of ≥ 3 were 5% for thin and mildly thick liquids and 1% for moderately/extremely thick liquids. Compared to clean baseline swallows, the odds of penetration-aspiration on thin liquids increased 4.60-fold above the 1% threshold and 4.20-fold above the 3% threshold (mildly thick: 2.11-fold > 1%(C2-4)2, 2.26-fold > 3%(C2-4)2). PAS scores of ≥ 3 did not occur with clearing swallows of moderately/extremely thick liquids. Lower frequencies of above-threshold preswallow residue were seen for swallows of additional material than for clearing swallows. Compared to clean baseline swallows, the odds of PAS scores of ≥ 3 on swallows of additional material increased ≥ 1.86-fold above the 1% threshold and ≥ 2.15-fold above the 3% threshold, depending on consistency. Conclusion The data suggest that a pharyngeal residue threshold of 1%(C2-4)2 is a meaningful cut-point for delineating increased risk of penetration-aspiration on a subsequent swallow.

Measurement of Pharyngeal Residue From Lateral View Videofluoroscopic Images

Purpose The field lacks consensus about preferred metrics for capturing pharyngeal residue on videofluoroscopy. We explored four different methods, namely, the visuoperceptual Eisenhuber scale and three pixel-based methods: (a) residue area divided by vallecular or pyriform sinus spatial housing ("%-Full"), (b) the Normalized Residue Ratio Scale, and (c) residue area divided by a cervical spine scalar (%(C2-4)2). Method This study involved retrospective analysis of an existing data set of videofluoroscopies performed in 305 adults referred on the basis of suspected dysphagia, who swallowed 15 boluses each (six thin and three each of mildly, moderately, and extremely thick 20% w/v barium). The rest frame at the end of the initial swallow of each bolus was identified. Duplicate measures of pharyngeal residue were made independently by trained raters; interrater reliability was calculated prior to discrepancy resolution. Frequency distributions and descriptive statistics were calculated for all measures. Kendall's τb tests explored associations between Eisenhuber scale scores and pixel-based measures, that is, %-Full and %(C2-4)2. Cross-tabulations compared Eisenhuber scale scores to 25% increments of the %-Full measure. Spearman rank correlations evaluated relationships between the %-Full and %(C2-4)2 measures. Results Complete data were available for 3,545 boluses: 37% displayed pharyngeal residue (thin, 36%; mildly thick, 41%; moderately thick, 35%; extremely thick, 34%). Eisenhuber scale scores showed modest positive associations with pixel-based measures but inaccurately estimated residue severity when compared to %-Full measures with errors in 20.6% of vallecular ratings and 14.2% of pyriform sinus ratings. Strong correlations (p < .001) were seen between the %-Full and %(C2-4)2 measures, but the %-Full measures showed inflation when spatial housing area was small. Conclusions Generally good correspondence was seen across different methods of measuring pharyngeal residue. Pixel-based measurement using an anatomical reference scalar, for example, (C2-4)2 is recommended for valid, reliable, and precise measurement.

Swallowing in Obese Individuals before and after Bariatric Surgery

PURPOSE

To evaluate the oral and pharyngeal phases of swallowing in obese patients before and after bariatric surgery.

MATERIAL AND METHOD

Swallowing was evaluated by videofluoroscopy before and after 80 to 123 days from bariatric surgery in 19 individuals with obesity (15 women), aged 25-60 years. The body mass index (BMI) before surgery was from 40.1 to 57.0 kg/m². The surgical treatment was performed with laparoscopic Roux-en-Y gastric by-pass (RYGB). After surgery, the BMI ranged from 31.7 to 48.4 kg/m². The control group had 19 healthy volunteers (15 women), aged 22-56 years and BMI from 19.4 to 29.7 kg/m². Swallowing was evaluated with swallows of 5 mL of liquid and paste boluses in triplicate, and a solid bolus in duplicate.

RESULTS

With swallowing of liquid bolus, individuals with obesity had, before and after surgery, an increased frequency of premature posterior spillage. Before the surgery, the obese subjects had longer pharyngeal clearance of liquid compared with the control group and with individuals after the surgery. After the surgery, obese individuals had longer duration of the hyoid movement with liquid and paste boluses, compared with before surgery. Also, there was a reduction of the interval between the bolus entering the phaynx and the onset of upward hyoid excursion.

CONCLUSION

Non-operated obese patients had a longer pharyngeal clearance for liquid bolus compared with healthy controls. After bariatric surgery, there was an increase in hyoid movement duration.

A Cross-Sectional, Quantitative Videofluoroscopic Analysis of Swallowing Physiology and Function in Individuals With Amyotrophic Lateral Sclerosis

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.

Genetic Taster Status as a Mediator of Neural Activity and Swallowing Mechanics in Healthy Adults

As part of a larger study examining relationships between taste properties and swallowing, we assessed the influence of genetic taster status (GTS) on measures of brain activity and swallowing physiology during taste stimulation in healthy men and women. Twenty-one participants underwent videofluoroscopic swallowing study (VFSS) and functional magnetic resonance imaging (fMRI) during trials of high-intensity taste stimuli. The precisely formulated mixtures included sour, sweet-sour, lemon, and orange taste profiles and unflavored controls. Swallowing physiology was characterized via computational analysis of swallowing mechanics plus other kinematic and temporal measures, all extracted from VFSS recordings. Whole-brain analysis of fMRI data assessed blood oxygen responses to neural activity associated with taste stimulation. Swallowing morphometry, kinematics, temporal measures, and neuroimaging analysis revealed differential responses by GTS. Supertasters exhibited increased amplitude of most pharyngeal movements, and decreased activity in the primary somatosensory cortex compared to nontasters and midtasters. These preliminary findings suggest baseline differences in swallowing physiology and the associated neural underpinnings associated with GTS. Given the potential implications for dysphagia risk and recovery patterns, GTS should be included as a relevant variable in future research regarding swallowing function and dysfunction.

Use of the Penetration-Aspiration Scale in Dysphagia Research: A Systematic Review

The penetration-aspiration scale (PAS) is an 8-point scale used to characterize the depth and response to airway invasion during videofluoroscopy. Though widely used in the field of deglutition, there is a lack of consensus regarding the statistical properties of the scale. In order to better understand the state of the literature and the statistical use of the PAS, a systematic review was undertaken to descriptively examine trends in statistical and reporting practices of the PAS since its inception. Online databases were searched for studies citing the original PAS article, which yielded 754 unique articles. Of these, 183 studies were included in the review. Results showed inconsistencies in the statistical use of the scale; 79 studies treated the PAS as ordinal, 71 as categorical, and 49 as interval. Ten types of categorizations were identified. Reporting of power analyses (9%), as well as inter- (26%) and intra-rater (17%) reliability, was uncommon. Among studies that administered multiple bolus volumes or consistencies, 55% reported PAS analyses at the participant/group level only. This review confirms the existence of discrepancies in the statistical treatment of the PAS. A lack of consensus among researchers limits comparisons between studies. The approach to handling this scale dictates the statistical tests used, potentially affecting results and interpretations. Consistent application of statistically sound approaches to PAS analyses is vital for the future of deglutition research.

Pharyngeal Area Changes in Parkinson's Disease and Its Effect on Swallowing Safety, Efficiency, and Kinematics

Pharyngeal area can increase as a function of normal healthy aging and muscle atrophy. These increases in pharyngeal area can negatively affect swallowing function in healthy older adults (HOA). However, the presence of pharyngeal area changes and their effects on swallowing function in Parkinson's disease (PD) remain unknown. Therefore, we compared the pharyngeal area of people with PD to HOA to determine if pharyngeal area changes were present in PD above and beyond what is seen in HOA. Within PD, we also evaluated if and how an increase in pharyngeal area affects swallowing kinematics, swallowing safety, and swallowing efficiency. A secondary analysis of videofluoroscopic swallow studies was completed comparing 41 HOA and 40 people with PD. Measures of pharyngeal area, swallowing kinematics, swallowing safety (penetration/aspiration), and swallowing efficiency (residue) were analyzed. An analysis of covariance (ANCOVA) was used to determine if pharyngeal area was significantly different between the HOA and PD groups while controlling for age, sex, and height. Regression analyses were used to examine if and how pharyngeal area influenced swallowing kinematics, swallowing safety, and swallowing efficiency in PD. Pharyngeal areas were significantly larger for people with PD when compared to HOA (p = .008). An increase in pharyngeal area was associated with less pharyngeal constriction (p = .022), shorter duration of airway closure (p = .017), worse swallowing safety (p < .0005), and worse swallowing efficiency (p = .037). This study revealed that pharyngeal areas are larger in people with PD when compared to HOA, and that this increase in pharyngeal area is associated with maladaptive changes to swallowing kinematics, residue, and penetration/aspiration. These findings support the notion that pharyngeal muscle atrophy may be exacerbated in PD above and beyond what is seen in normal, healthy aging group. Results from this study highlight the need to consider pharyngeal muscle atrophy as a source for swallowing dysfunction in PD, and as a potential treatment target for swallowing rehabilitation.