3D-CT Evaluation of Swallowing: Metrics of the Swallowing Response Using Swallowing CT

Timing of True Vocal Cords Closure for Safe Swallowing: A Review of 5 Studies Using 3D Analysis Using Computerized Tomography (CT)

Timely and complete laryngeal closure is critical for a successful swallow. Researchers have studied laryngeal closure, including true vocal cords (TVC) closure, closure of the arytenoids to the epiglottis base (laryngeal vestibule closure), and epiglottic inversion, but the most commonly available imaging tools have limitations that do not allow the study of these components individually. Swallowing computerized tomography (CT) has enabled three-dimensional dynamic visualization and quantitative evaluation of swallowing events providing a unique view of swallowing-related structures and their motion. Using CT, TVC closure can be visualized and evaluated on any plane or cross-section without being obscured by of laryngeal vestibule closure or epiglottis inversion. The current review summarizes the results of five papers evaluating the effects of bolus consistency and volume, posture, and age on TVC closure. The combined results of these studies suggest that TVC closure is responsive to oral sensory input based on bolus consistency and size and can be modulated in response to conditions perceived to increase the risk of airway invasion. These results are meaningful for dysphagia rehabilitation as it suggests that interventions to improve TVC closure are likely to enhance airway protection.

Polysaccharide-dextrin thickened fluids for individuals with dysphagia: recent advances in flow behaviors and swallowing assessment methods

The global aging population has brought about a pressing health concern: dysphagia. To effectively address this issue, we must develop specialized diets, such as thickened fluids made with polysaccharide-dextrin (e.g., water, milk, juices, and soups), which are crucial for managing swallowing-related problems like aspiration and choking for people with dysphagia. Understanding the flow behaviors of these thickened fluids is paramount, and it enables us to establish methods for evaluating their suitability for individuals with dysphagia. This review focuses on the shear and extensional flow properties (e.g., viscosity, yield stress, and viscoelasticity) and tribology (e.g., coefficient of friction) of polysaccharide-dextrin-based thickened fluids and highlights how dextrin inclusion influences fluid flow behaviors considering molecular interactions and chain dynamics. The flow behaviors can be integrated into the development of diverse evaluation methods that assess aspects such as flow velocity, risk of aspiration, and remaining fluid volume. In this context, the key in-vivo (e.g., clinical examination and animal model), in-vitro (e.g., the Cambridge Throat), and in-silico (e.g., Hamiltonian moving particles semi-implicit) evaluation methods are summarized. In addition, we explore the potential for establishing realistic assessment methods to evaluate the swallowing performance of thickened fluids, offering promising prospects for the future.

Prediction of Pharyngeal 3D Volume Using 2D Lateral Area Measurements During Swallowing

This study evaluated the validity of pharyngeal 2D area measurements acquired from the lateral view for predicting the actual 3D volume in healthy adults during swallowing. Seventy-five healthy adults (39 females, 36 males; mean age 51.3 years) were examined using 320-row area detector computed tomography (320-ADCT). All participants swallowed a 10 mL honey-thick barium bolus upon command while seated in a 45° semi-reclining position. Multi-planar reconstruction images and dynamic 3D-CT images were obtained using Aquilion ONE software. Pharyngeal 2D area and 3D volume measurements were taken before swallowing and at the frame depicting maximum pharyngeal constriction. Pharyngeal volume before swallowing (PVhold) was accurately predicted by 2D area (R2 = 0.816). Adding height and sex to the model increased R2 to 0.836. Regarding pharyngeal volume during maximum constriction (PVmax), 2D area also exhibited acceptable predictive power (R2 = 0.777). However, analysis of statistical residuals and outliers revealed a greater tendency for prediction errors when there is less complete constriction of the pharynx as well as asymmetry in bolus flow or movement. Findings highlight the importance of routinely incorporating anterior-posterior views during VFSS exams. Future work is needed to determine clinical utility of pharyngeal volume measurements derived from 320-ADCT.

Normative High-Resolution Pharyngeal Manometry: Impact of Age, Size of System, and Sex on Primary Metrics and Pressure Stability

There have been many reports of normative pharyngeal swallowing pressures using high-resolution pharyngeal manometry, but there is a fair amount of between-subject variance in reported pressure parameters. The purpose of this study was to put forward normative pharyngeal high-resolution manometry measures across the lifespan and investigate the effects of age, size of system, and sex. High-resolution pharyngeal manometry was performed on 98 healthy adults (43 males) between the ages 21 and 89. Pressure duration, maxima, integral, and within-individual variability metrics were averaged over 10 swallows of 10-ml thin liquid. Multiple linear and logistic regressions with model fitting were used to examine how pharyngeal pressures relate to age, pharyngeal size, and sex. Age was associated with tongue base maximum pressure, tongue base maximum variability, and upper esophageal sphincter-integrated relaxation pressure (F3,92 = 6.69; p < 0.001; adjusted R2 = 0.15). Pharyngeal area during bolus hold was associated with velopharynx integral (F1,89 = 5.362; p = 0.02; adjusted R2 = 0.05), and there was no significant model relating pharyngeal pressures to C2-C4 length (p < 0.05). Sex differences were best described by tongue base integral and hypopharynx maximum variability (χ2 = 10.27; p = 0.006; pseudo R2 = 0.14). Normative data reveal the distribution of swallow pressure metrics which need to be accounted for when addressing dysphagia patients, the importance of pressure interactions in normal swallow, and address the relative stability of swallow metrics with normal aging.

Sarcopenic Dysphagia and Simplified Rehabilitation Nutrition Care Process: An Update

Sarcopenic dysphagia is characterized by weakness of swallowing-related muscles associated with whole-body sarcopenia. As the number of patients with sarcopenia increases with the aging of the world, the number of patients with sarcopenic dysphagia is also increasing. The prevalence of sarcopenic dysphagia is high in the institutionalized older people and in patients hospitalized for pneumonia with dysphagia in acute care hospitals. Prevention, early detection and intervention of sarcopenic dysphagia with rehabilitation nutrition are essential. The diagnosis of sarcopenic dysphagia is based on skeletal and swallowing muscle strength and muscle mass. A reliable and validated diagnostic algorithm for sarcopenic dysphagia is used. Sarcopenic dysphagia is associated with malnutrition, which leads to mortality and Activities of Daily Living (ADL) decline. The rehabilitation nutrition approach improves swallowing function, nutrition status, and ADL. A combination of aggressive nutrition therapy to improve nutrition status, dysphagia rehabilitation, physical therapy, and other interventions can be effective for sarcopenic dysphagia. The rehabilitation nutrition care process is used to assess and problem solve the patient's pathology, sarcopenia, and nutrition status. The simplified rehabilitation nutrition care process consists of a nutrition cycle and a rehabilitation cycle, each with five steps: assessment, diagnosis, goal setting, intervention, and monitoring. Nutrition professionals and teams implement the nutrition cycle. Rehabilitation professionals and teams implement the rehabilitation cycle. Both cycles should be done simultaneously. The nutrition diagnosis of undernutrition, overnutrition/obesity, sarcopenia, and goal setting of rehabilitation and body weight are implemented collaboratively.

The dynamics of deglutition during head rotation using dynamic 320-row area detector computed tomography

Objective

We aimed to elucidate the dynamics of deglutition during head rotation by acquiring 320-row area detector computed tomography (320-ADCT) images and analyzing deglutition during head rotation.

Methods

This study included 11 patients experiencing globus pharyngeus. A 320-ADCT was used to acquire images in two types of viscosity (thin and thick), with the head rotated to the left. We measured the movement time of deglutition-related organs (soft palate, epiglottis, upper esophageal sphincter [UES], and true vocal cords) and pharyngeal volume (bolus ratio at the start of UES opening [Bolus ratio], pharyngeal volume contraction ratio [PVCR], and pharyngeal volume before swallowing [PVBS]). A two-way analysis of variance was performed for statistical analysis, and all items were compared for significant differences in terms of head rotation and viscosity. EZR was used for all statistical analyses (p-value <.05).

Results

Head rotation significantly accelerated the onset of epiglottis inversion and UES opening compared with no head rotation. The duration of epiglottis inversion with the thin viscosity fluid was significantly longer. The bolus ratio increased significantly with thick viscosity. There was no significant difference in viscosity and head rotation in terms of PVCR. PVBS increased significantly with head rotation.

Conclusion

The significantly earlier start of epiglottis inversion and UES opening due to head rotation could be caused by: (1) swallowing center; (2) pharyngeal volume; and (3) pharyngeal contraction force. Thus, we plan to further analyze swallowing with head rotation by combining swallowing CT with manometry and examine its relationship with pharyngeal contraction force.

Level of Evidence

3b.

Differences in pharyngeal swallow event timing: Healthy aging, Parkinson disease, and amyotrophic lateral sclerosis

Objective

The pharyngeal phase of swallowing involves a coordinated sequence of events. Event durations may be prolonged in people with Parkinson disease (PwPD), and amyotrophic lateral sclerosis (PwALS); however, the cumulative effect of these changes is unexplored. We compared event latencies relative to hyoid burst (HYB) (time zero) to understand differences in deglutatory event timing. We hypothesized PwPD and PwALS would display similarly prolonged cumulative pharyngeal phase durations compared to healthy controls, with greater prolongations with increasing bolus viscosity.

Method

We retrospectively evaluated videofluoroscopic data of healthy adults (n = 78), PwPD (n = 17), and PwALS (n = 20). Participants swallowed 15 boluses of 20% (w/v) barium across five liquid consistencies. Paired raters evaluated nine deglutitive events using the ASPEKT method. Latencies were plotted by consistency relative to HYB and compared across cohorts using Mann-Whitney U tests (p ≤ .05). Cohen's d was calculated for all statistically significant results to determine effect size.

Results

In PwPD, significantly prolonged latencies were observed on thin liquid boluses compared to healthy controls. Latencies to all post-HYB events were significantly prolonged except for maximum upper esophageal sphincter distension. In PwALS, significantly prolonged latencies for events preceding and following HYB were noted on all consistencies compared to healthy controls and PwPD.

Conclusion

In PwPD, event latencies for multiple components of the swallowing sequence were prolonged culminating in overall prolongation of the pharyngeal phase on thin liquid. A similar pattern, but with significantly greater prolongation, was seen in the PwALS, and extended to swallows of all liquid consistencies.

Effect of the Effortful Swallow on Pharyngeal Cavity Volume: Kinematic Analysis in Three Dimensions Using 320-Row Area Detector Computed Tomography

This study evaluated the effects of the effortful swallow (ES) on pharyngeal cavity volume using three-dimensional kinematic analyses. Nine healthy volunteers (30.7 ± 7.8 years old) underwent a CT scan while swallowing 10 ml of honey thick liquid using no maneuvers (control) and during an ES. Upper and lower volumes (bordered by valleculae) of the pharyngeal air column and the bolus were measured at every frame and were compared between ES and control swallows. Duration of pharyngeal obliteration and the timing of swallowing events were also measured. Maximum volume and volume at the onset of hyoid anterosuperior movement using ES were significantly smaller than those in control swallows (p = 0.012, p = 0.015) in the upper pharynx but not significantly different in lower pharynx. Minimum pharyngeal volume was sustained for a longer time when ES was used compared to control swallows in both upper and lower pharynx (upper p = 0.016, lower p = 0.027). Onset of velopharyngeal closure was earlier when comparing ES and control swallows (p = 0.04). Termination of all events was significantly delayed when the ES was used (p < 0.05). Changes in the upper pharyngeal volume and in the onset of velopharyngeal closure suggest earlier pharyngeal constriction when using the ES. Longer pharyngeal obliteration and prolonged termination of velopharyngeal closure and epiglottis inversion suggest the prolonged pharyngeal constriction during the ES. These findings suggest the ES can be useful for improving the efficiency of swallowing.