Mechanisms of airway protection during chin-down swallowing

The effect of craniocervical flexors endurance training on suprahyoid muscle activation in healthy adults: A randomised controlled trial

BACKGROUND

Cervical posture affects swallowing function through contractile and non-contractile structures. Craniocervical flexor endurance training (CCFET), which focuses on the activation of deep cervical muscles, is used to ensure cervical posture stability.

OBJECTIVE

The aim of this study was to investigate the effect of CCFET on the suprahyoid muscles (SH), which play an important role in swallowing function.

METHODS

Eighty healthy individuals (52 female and 28 male, mean age 21.77 ± 1.81 years) were recruited and randomly assigned to groups that underwent either deep cervical flexor (DCF) training with a pressure biofeedback unit (CCFET group, n = 41) or no intervention (control group, n = 39). The intervention was applied for 4 weeks (five sessions per week). Static endurance and activation of DCF muscles (Craniocervical Flexion Test, CCFT), tragus-wall distance (TWD) for forward head posture and surface electromyographic (sEMG) activation of suprahyoid muscles were evaluated.

RESULTS

The endurance and activation of the DCF muscles were significantly increased in the CCFET group (p = <.001). In the CCFET group, TWD significantly lower than the control group (p = <.001) Peak SH amplitude and mean SH amplitude were lower in the CCFET group compared to the control group (p = .013, p = .003).

CONCLUSION

The study shows that 4 weeks of CCFET reduced SH muscle activation, allowing the same work to be done with fewer motor units. CCFET can be included in rehabilitation programs as an additional method that has an effect on the muscles involved in swallowing by providing cervical motor control.

A Tutorial on Diagnostic Benefit and Radiation Risk in Videofluoroscopic Swallowing Studies

The videofluoroscopic swallowing study (VFSS) is a key tool in assessing swallowing function. As with any diagnostic procedure, the probable benefits of the study must be weighed against possible risks. The probable benefit of VFSS is an accurate assessment of swallowing function, enabling patient management decisions potentially leading to improved patient health status and quality of life. A possible (though highly unlikely) risk in VFSS is carcinogenesis, arising from the use of ionizing radiation. Clinicians performing videofluoroscopic swallowing studies should be familiar with both sides of the risk benefit equation in order to determine whether the study is medically justified. The intent of this article is to provide the necessary background for conversations about benefit and risk in videofluoroscopic swallowing studies.

Chin-tuck assistant system (CAS)-A novel method using auditory feedback for postural maintenance in a chin-tuck maneuver: A randomized trial

INTRODUCTION

Chin-tuck are effective in patients with dysphagia, where aspiration can occur due to pharyngeal swallowing delays. This study aims to verify whether Chin-tuck Assistant System Maneuver (CAS-M) supplemented with Chin-Tuck Maneuver (CTM) is effective for learning and maintaining correct chin-tuck postures. In addition, we investigated the possibility of using CAS-M as a customized rehabilitation treatment program for patients with poor cognitive ability, attention issues, and general swallowing disorders.

INTERVENTION

To demonstrate the effectiveness of CAS, we recruited 52 healthy adults and assigned them to 2 groups. The CTM group was trained to maintain the correct chin-tuck posture using the general Chin-Tuck Maneuver, while the CAS-M group was trained using CAS. Four evaluations were conducted using CAS to investigate the degree of postural maintenance of chin-tuck before and after intervention.

RESULTS

The CAS-M group showed a statistically significant difference in TIME, BEEP, and change (P < .05), but the CTM group showed no statistically significant differences (P < .05). YZ evaluation showed no statistically significant differences in both groups.

CONCLUSION

After examining the effects of CAS-M using CAS on healthy adults, we confirmed this to be a more effective method for correct chin-tuck posture than conventional CTM.

Advances in the Treatment of Dysphagia in Neurological Disorders: A Review of Current Evidence and Future Considerations

Dysphagia, which refers to difficult and/or disordered swallowing, is a common problem associated with various neurological diseases such as stroke, motor neuron diseases and neurodegenerative diseases. Traditionally, dysphagia treatments are either compensatory, which includes modifications of bolus texture or feeding posture, or rehabilitative, which includes behavioral exercises and sensory stimulation. Despite being widely adopted in clinical practice, recent views have challenged the clinical efficacy of these treatments due to the low level of evidence supported by mainly non-controlled studies. As such, with advancements in technology and scientific research methods, recent times have seen a surge in the development of novel dysphagia treatments and an increasing number of robust randomized controlled clinical trials. In this review, we will review the clinical evidence of several newly introduced treatments for dysphagia in the last two decades, including rehabilitative exercises, biofeedback, pharmacological treatments, neuromodulation treatments and soft robotics. Despite the recent improvements in the quality of evidence for the efficacy of dysphagia treatments, several critical issues, including heterogeneity in treatment regimens, long-term treatment effects, underlying mechanisms of some neuromodulation treatments, and the effects of these techniques in non-stroke dysphagia, remain to be addressed in future clinical trials.

Effects of head flexion posture in patients with dysphagia

BACKGROUND

The chin-down posture is often used as a compensatory maneuver for patients with dysphagia. This posture presumably involves flexion of the head and/or neck, but this is not clearly defined.

OBJECTIVE

This study aimed to assess the effects of head flexion posture in a retrospective study of videofluoroscopic examination of swallowing (VF).

METHODS

A total of 73 patients who underwent VF both with and without head flexion posture in the lateral projection were included in the analysis. The head and neck angles at the initiation of the swallowing reflex, penetration-aspiration scale (PAS), nasopharyngeal closure time, stage transition duration, duration of laryngeal closure, time from swallowing reflex to laryngeal closure and to opening of the upper esophageal sphincter (UES), duration of UES opening, location of the bolus leading edge at swallowing reflex, and bolus transition time were evaluated.

RESULTS

The head flexion angle increased (p < 0.001), but the neck flexion angle did not change in the head flexion posture. Moreover, PAS improved (p < 0.001), aspiration was reduced (p < 0.001), the time between the swallowing reflex and the onset of laryngeal closure was shortened (p = 0.006), and the leading edge of the bolus at swallowing reflex became shallower (p = 0.004) in the head flexion posture. Other parameters did not significantly change.

CONCLUSION

The head flexion posture resulted in earlier laryngeal closure and a shallower position of the leading bolus edge at swallowing reflex, resulting in PAS improvement and decreased aspiration.

Reliability of the Penetration-Aspiration Scale and Temporal and Clearance Measures in Poststroke Dysphagia: Videofluoroscopic Analysis From the Swallowing Treatment using Electrical Pharyngeal Stimulation Trial

PURPOSE

Information on reliability of outcome measures used to assess the effectiveness of interventions in dysphagia rehabilitation is lacking, particularly when used by different research groups. Here, we report on reliability of the penetration-aspiration scale (PAS) and temporal and clearance measures, determined using videofluoroscopy.

METHOD

Secondary analysis used videofluoroscopies from the Swallowing Treatment using Electrical Pharyngeal Stimulation trial in subacute stroke. PAS scores (719 scores from 18 participants) were evaluated and compared to the original PAS scores from the trial. Five conditions were assessed, including reliability for every swallow and overall mean of the worst PAS score. Operational rules for assessing temporal and clearance measures were also developed using the same data, and reliability of these rules was assessed. Reliability of component-level and derivative-level scores was assessed using the intraclass correlation coefficient (ICC) and weighted kappa.

RESULTS

Image quality was variable. Interrater reliability for the overall mean of the worst PAS score was excellent (ICC = .914, 95% confidence interval [CI] [.853, .951]) but moderate for every swallow in the bolus (ICC = .743, 95% CI [.708, .775]). Intrarater reliability for PAS was excellent (all conditions). Excellent reliability (both inter- and intrarater > .90) was seen for temporal measures of stage transition duration (ICC = .998, 95% CI [.993, .999] and ICC = .995, 95% CI [.987, .998], respectively) as well as initiation of laryngeal closure and pharyngeal transit time and all individual swallow events. Strong scores were obtained for some clearance measures; others were moderate or weak.

CONCLUSIONS

Interrater reliability for PAS is acceptable but depends on how the PAS scores are handled in the analysis. Interrater reliability for most temporal measures was high, although some measures required additional training. No clearance measures had excellent reliability.

SUPPLEMENTAL MATERIAL

https://doi.org/10.23641/asha.19090088.

Effects of Pharyngeal Electrical Stimulation on Swallow Timings, Clearance and Safety in Post-Stroke Dysphagia: Analysis from the Swallowing Treatment Using Electrical Pharyngeal Stimulation (STEPS) Trial

Swallowing impairment (dysphagia) post-stroke results in poorer outcomes. Pharyngeal electrical stimulation (PES) is a potential treatment for post-stroke dysphagia. In a post hoc analysis, we investigated PES using videofluoroscopy swallow studies (VFSS) from the STEPS trial incorporating multiple measures of safety (penetration aspiration scale-PAS), speed and duration (timing), and efficiency (clearance), as opposed to the original trial which only measured PAS scores. 81 randomised participants (PES (N = 43) versus sham (N = 38)) were analysed at baseline and 2 weeks. Participants swallowed up to 6 × 5 ml and 1 × 50 ml of thin liquid barium at 40% w/v, images at ≥25 fps. Based on PAS, the 5 ml mode bolus (most frequently occurring PAS from 6 × 5 ml) and the worst 50 ml bolus were chosen for further analysis. Eight timing measures were performed, including stage transition duration (STD) and pharyngeal transit time (PTT). Clearance measures comprised oral and pharyngeal residue and swallows to clear. Comparisons of change of scoring outcomes between PES and sham were done at 2 weeks. Wilcoxon Signed Ranks Test was also used to evaluate longitudinal changes from both groups' combined results at two weeks. Between-group analysis showed no statistically significant differences. Issues with suboptimal image quality and frame rate acquisition affected final numbers. At two weeks, both groups demonstrated a significant improvement in most safety scores (PAS) and STD, possibly due to spontaneous recovery or a combination of spontaneous recovery and swallowing treatment and usual care. A nonsignificant trend for improvement was seen in other timing measures, including PTT. This study, which conducted additional measurements of kinematic and residue analysis on the STEPS data did not detect “missed” improvements in swallowing function that the PAS is not designed to measure. However, more studies with greater numbers are required.

Impact of the Chin-Down Posture on Temporal Measures of Patients With Dysphagia: A Pilot Study

Purpose The chin-down position is a commonly prescribed posture by health care professionals to alleviate the symptoms of dysphagia. Yet, how the technique influences swallowing physiology lacks clarity. Our goal was to examine the impact of the postural technique on patients with various medical conditions and swallowing impairments. Method Temporal and functional measures were examined with videofluoroscopy in the chin-down and neutral head position on 15 patients. Also, timing differences between head positions were examined to determine the presence of improvement during the chin-down posture. Results The primary finding was chin-down posture swallows prolonged the elapsed time between when the prematurely spilled bolus entered the pharynx relative to swallow onset compared to the neutral head position (p = .006). Also, no improvement in airway protection was found when performing the postural technique. Conclusions The chin-down posture may benefit patients with specific swallowing impairments. However, the general use of the technique for all patients who experience swallowing difficulty might be negligent and could potentially have adverse or no effect on patient outcomes. Future studies examining patients with the same pathophysiology are needed to understand the benefit of the chin-down posture based on swallowing impairment.

Effectiveness of Chin Tuck on Laryngeal Penetration: Quantitative Assessment

The effectiveness of the chin tuck maneuver is still controversial, despite being widely used in clinical practice. The chin tuck maneuver has been shown to be able to reduce or eliminate aspiration in a group of patients with a number of favorable conditions, but its effectiveness in preventing or managing penetration remains unclear. This study was designed to investigate whether the chin tuck maneuver is effective in reducing penetration. Images from a videofluoroscopic swallowing study (VFSS) taken from 76 patients with penetration were collected and reviewed retrospectively. The severity of penetration was assessed by the penetration ratio (ratio of the penetration depth to the length of the epiglottis) measured and calculated from the images in which the deepest penetration was observed. The penetration ratio was significantly decreased in the chin tuck posture compared with the ratio in the neutral position (p = 0.001). Significant reducing effect was observed in 26 (34.2%) out of 76 patients. When comparing other parameters of VFSS, residues in the vallecular and pyriformis sinuses were less severe in the effective group. Chin tuck significantly decreased residues in both effective and ineffective group. The results demonstrate that the chin tuck maneuver can reduce penetration, but its effectiveness is limited.

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.

A Preliminary Videofluoroscopic Investigation of Swallowing Physiology and Function in Individuals with Oculopharyngeal Muscular Dystrophy (OPMD)

Dysphagia is one of the primary symptoms experienced by individuals with Oculopharyngeal Muscular Dystrophy (OPMD). However, we lack understanding of the discrete changes in swallowing physiology that are seen in OPMD, and the resulting relationship to impairments of swallowing safety and efficiency. This study sought to describe the pathophysiology of dysphagia in a small sample of patients with OPMD using a videofluoroscopy examination (VFSS) involving 3 × 5 mL boluses of thin liquid barium (22% w/v). The aim of this study is to extend what is known about the pathophysiology of dysphagia in OPMD, by quantifying changes in swallow timing, kinematics, safety, and efficiency, measured from VFSS. This study is a secondary analysis of baseline VFSS collected from 11 adults (4 male), aged 48-62 (mean 57) enrolled in an industry-sponsored phase 2 therapeutic drug trial. Blinded raters scored the VFSS recordings for safety [Penetration-Aspiration Scale (PAS)], efficiency [Normalized Residue Ratio Scale (NRRS)], timing [Pharyngeal Transit Time (PTT), Swallow Reaction Time (SRT), Laryngeal Vestibule Closure Reaction Time (LVCrt), Upper Esophageal Sphincter Opening Duration (UESD)], and kinematics (hyoid movement, pharyngeal constriction, UES opening width). Impairment thresholds from existing literature were defined to characterize swallowing physiology and function. Further, Fisher's Exact tests and Pearson's correlations were used to conduct a preliminary exploration of associations between swallowing physiology (e.g., kinematics, timing) and function (i.e., safety, efficiency). Compared to published norms, we identified significant differences in the degree of maximum pharyngeal constriction, hyoid movement distance and speed, as well as degree and timeliness of airway closure. Unsafe swallowing (PAS ≥ 3) was seen in only 3/11 patients. By contrast, clinically significant residue (i.e., NRRS scores ≥ 0.09 vallecular; ≥ 0.2 pyriform) was seen in 7/11 patients. Fisher's Exact tests revealed associations between prolonged SRT, PTT, and unsafe swallowing. Weak associations were also identified between post-swallow residue and poor pharyngeal constriction during the swallow. Detailed analysis of swallowing physiology in this series of adults with OPMD aligns with impaired muscular function (e.g., reduced pharyngeal constriction, incomplete laryngeal vestibule closure) associated with the disease, and primary functional challenges with swallow efficiency. Further work is needed to explore a greater range of food and liquid textures, and to identify additional physiological mechanisms underlying swallowing impairment in OPMD.

LVC Timing in Infant Pig Swallowing and the Effect of Safe Swallowing

Recurrent laryngeal nerve (RLN) injury in neonates, a complication of head and neck surgeries, leads to increased aspiration risk and swallowing dysfunction. The severity of resulting sequelae range from morbidity, such as aspiration pneumonia, to mortality from infection and failure to thrive. The timing of airway protective events including laryngeal vestibule closure (LVC) is implicated in aspiration. We unilaterally transected the RLN in an infant pig model to observe changes in the timing of swallowing kinematics with lesion and aspiration. We recorded swallows using high-speed video-fluoroscopic swallow studies (VFSS) and scored them using the Infant Mammalian Penetration and Aspiration Scale (IMPAS). We hypothesized that changes would occur in swallowing kinematics (1) between RLN lesion and control animals, and (2) among safe swallows (IMPAS 1), penetration swallows (IMPAS 3), and aspiration swallows (IMPAS 7). We observed numerous changes in timing following RLN lesion in safe and unsafe swallows, suggesting pervasive changes in the coordination of oropharyngeal function. The timing of LVC, posterior tongue, and hyoid movements differed between pre- and post-lesion in safe swallows. Posterior tongue kinematics differed for post-lesion swallows with penetration. The timing and duration of LVC and posterior tongue movement differed between aspiration swallows pre- and post-lesion. After lesion, safe swallows and swallows with aspiration differed in timing of LVC, laryngeal vestibule opening, and posterior tongue and hyoid movements. The timing of thyrohyoid muscle activity varied with IMPAS, but not lesion. Further study into the pathophysiology of RLN lesion-induced swallowing dysfunction is important to developing novel therapies.

Reflections on Clinical and Statistical Use of the Penetration-Aspiration Scale

The 8-point Penetration-Aspiration Scale (PAS) was introduced to the field of dysphagia in 1996 and has become the standard method used by both clinicians and researchers to describe and measure the severity of airway invasion during swallowing. In this article, we review the properties of the scale and explore what has been learned over 20 years of use regarding the construct validity, ordinality, intervality, score distribution, and sensitivity of the PAS to change. We propose that a categorical revision of the PAS into four levels of increasing physiological severity would be appropriate. The article concludes with a discussion of common errors made in the statistical analysis of the PAS, proposing that frequency distributions and ordinal logistic regression approaches are most appropriate given the properties of the scale. A hypothetical dataset is included to illustrate both the problems and strengths of different statistical approaches.

Laryngeal Closure during Swallowing in Stroke Survivors with Cortical or Subcortical Lesion

BACKGROUND

One of the major, and most harmful, symptoms of dysphagia in stroke survivors is aspiration. Survivors of unilateral cortical strokes with dysphagia and resulting aspiration have been reported to have greater initiation delays in laryngeal closure than those who did not aspirate. Few studies have reported such data in survivors of subcortical stroke.

METHODS

This study measured initiation of laryngeal closure (ILC) and laryngeal closure duration (LCD) in 2 groups of subjects: 15 stroke survivors with cortical lesions and 15 stroke survivors with subcortical lesions. Means and standard deviations of ILC and LCD were analyzed on 5-mL thin liquid and 5-mL puree boluses using a 100-ms timer during subsequent analysis of videofluoroscopic swallowing examinations. Statistical comparisons were used by repeated measures analysis of variance. Significance level was set at P < .05.

RESULTS

ILC was significantly longer in stroke survivors with a subcortical lesion than in those with a cortical lesion for both bolus consistencies. However, there were no significant differences between the 2 groups in LCD. Stroke survivors with a subcortical lesion had a greater incidence of penetration or aspiration and silent aspiration than those with a cortical lesion and a longer delay in the ILC.

CONCLUSIONS

Subcortical lesions may put these survivors at greater risk of aspiration due to delayed initial laryngeal closure and reduced oral and laryngeal sensation. The subcortical damage, which occurs at the basal ganglia, may interrupt the ILC.

Examination of swallowing maneuver training and transfer of practiced behaviors to laryngeal vestibule kinematics in functional swallowing of healthy adults

Swallowing maneuvers are routinely trained in dysphagia rehabilitation with the assumption that practiced behaviors transfer to functional swallowing, however transfer is rarely examined in the deglutition literature. The goal of this study was to train the volitional laryngeal vestibule closure (vLVC) maneuver, which is a swallowing maneuver that targets prolonged laryngeal vestibule closure (LVC). In two different training experiments, 69 healthy adults underwent Long-hold (hold vLVC as long as possible) or Short-hold vLVC training (hold vLVC for 2s). Before and after vLVC training, natural swallows (swallowing without a therapeutic technique) were completed. The outcome variables included laryngeal vestibule closure reaction time and the duration of laryngeal vestibule closure. Results indicate that during both Long-hold and Short-hold vLVC trainings, vLVC swallows had faster laryngeal vestibule closure reaction times and longer durations of laryngeal vestibule closure than in pre-training 5ml liquid swallows. However, only faster laryngeal vestibule closure reaction times transferred to post-training 5ml liquid swallows (20-24% faster), but not prolonged durations of laryngeal vestibule closure. Our findings suggest that swallowing maneuver training has the potential to induce transfer of what was practiced to functional swallowing behavior, although not all practiced behaviors may generalize. These findings are significant for bolstering the effectiveness of dysphagia management in medical settings and should be tested in individuals with dysphagia.

Effects of chin-up posture on the sequence of swallowing events

BACKGROUND

Chin-up posture is frequently used to manage oral dysphagia after head and neck cancer. This prospective study investigates the effects of chin-ups on the sequence of pharyngeal swallowing events.

METHODS

Twelve healthy young adults performed 45 consecutive swallows of 5 mL water across 3 phases on videofluoroscopy: 5 swallows in the neutral head position; 30 swallows during chin-up posture; and 10 swallows in the neutral head position. Swallowing kinematic and bolus flow measures for 9 swallowing events were recorded. Linear trends were analyzed across 30 chin-up swallows; pairwise comparison was used to compare the 3 phases.

RESULTS

Time to hyoid peak and laryngeal vestibule closure changed abruptly during chin-up swallowing compared to the initial neutral position. No measure changed across 30 chin-up swallows. Time of hyoid burst decreased upon returning to the neutral position.

CONCLUSION

Our findings indicate that chin-up posture challenges the pharyngeal sequence of events for both swallowing kinematics and bolus flow. © 2017 Wiley Periodicals, Inc. Head Neck 39: 947-959, 2017.

Case Reports: Trial Dysphagia Interventions Conducted via Telehealth

The diagnosis of dysphagia, defined as swallowing dysfunction or difficulty, is estimated to affect 40–60% of the institutionalized geriatric population, and is the leading cause of aspiration pneumonia, one of the primary contributors of geriatric mortality. In the United States, statistics suggest that at least 50% of these individuals have limited access to treatment due to mobility, distance, and socioeconomic constraints. While “tele-dysphagia intervention” – the delivery of dysphagia therapy services via telecommunications technology – may provide a solution, there is limited research investigating its validity or reliability. The following three case reports of individuals successfully participating in trial tele-dysphagia therapy sessions lend credibility to this service delivery approach, and highlight the need for future research.

The effectiveness of the head-turn-plus-chin-down maneuver for eliminating vallecular residue

Purpose When swallowing efficiency is impaired, residue accumulates in the pharynx. Cued or spontaneous swallows in the head neutral position do not always successfully clear residue. We investigated the impact of a novel maneuver on residue clearance by combining a head turn with the chin down posture. Methods Data were collected from 26 participants who demonstrated persistent vallecular residue after an initial head neutral clearance swallow in videofluoroscopy. Participants were cued to perform a head-turn-plus-chin-down swallow, with the direction of head turn randomized. Pixel-based measures of residue in the vallecular space before and after the maneuver were made on still frame lateral images using ImageJ software. Measures of % full and the Normalized Residue Ratio Scale (NRRS) were extracted. Univariate analyses of variance were used to detect significant reductions in residue. Results On average, pre-maneuver measures showed residue filling 56-73% of the valleculae, depending on stimulus consistency (NRRS scores: 0.2-0.4). More than 80% of pre-swallow measures displayed NRRS ratios > 0.06, a threshold previously linked to increased risk of post-swallow aspiration. Conclusion The head-turn-plus-chin-down maneuver achieved significant reductions in residue for thin and nectar-thick fluids, suggesting that this maneuver can be effective in reducing persistent vallecular residue with these consistencies.

A systematic review and meta-analysis of pneumonia associated with thin liquid vs. thickened liquid intake in patients who aspirate

OBJECTIVE

To investigate whether drinking thin liquids with safety strategies increases the risk for pneumonia as compared with thickened liquids in patients who have demonstrated aspiration of thin liquids.

DATA SOURCES

Seven electronic databases, one clinical register, and three conference archives were searched. No language or publication date restrictions were imposed. Reference lists were scanned and authors and experts in the field were contacted.

REVIEW METHODS

A blind review was performed by two reviewers for published or unpublished randomized controlled trials and prospective non-randomized trials comparing the incidence of pneumonia with intake of thin liquids plus safety strategies vs. thickened liquids in adult patients who aspirated on thin liquids. The data were extracted from included studies. Odds ratios (OR) for pneumonia were calculated from the extracted data. Risk of bias was also assessed with the included published trials.

RESULTS

Seven studies out of 2465 studies including 650 patients met the inclusion criteria. All of the seven studies excluded patients with more than one known risk factor for pneumonia. Six studies compared thin water protocols to thickened liquids for pneumonia prevention. A meta-analysis was done on the six studies, showing no significant difference for pneumonia risk (OR = 0.82; 95% CI = 0.05-13.42; p = 0.89).

CONCLUSIONS

There was no significant difference in the risk of pneumonia in aspirating patients who took thin liquids with safety strategies compared with those who took thickened liquids only. This result, however, is generalizable only for patients with low risk of pneumonia.

Multisensor Classification System for Triggering FES in Order to Support Voluntary Swallowing

In dysphagia the ability of elevating the larynx and hyoid is usually impaired. Electromyography (EMG) and Bioimpedance (BI) measurements at the neck can be used to trigger functional electrical stimulation (FES) of swallowing related muscles. Nahrstaedt et al.¹ introduced an algorithm to trigger the stimulation in phase with the voluntary swallowing to improve the airway closure and elevation speed of the larynx and hyoid. However, due to non-swallow related movements like speaking, chewing or head turning, stimulations might be unintentionally triggered. So far a switch was used to enable the BI/EMG-triggering of FES when the subject was ready to swallow, which is inconvenient for practical use. In this contribution, a range image camera system is introduced to obtain data of head, mouth, and jaw movements. This data is used to apply a second classification step to reduce the number of false stimulations. In experiments with healthy subjects, the amount of potential false stimulations could be reduced by 47% while 83% of swallowing intentions would have been correctely supported by FES.

The Sequence of Swallowing Events During the Chin-Down Posture

PURPOSE

This study investigated the effect of the chin-down posture on the sequence of swallowing events in healthy adults.

METHOD

Sixteen healthy participants performed 45 5-ml thin liquid swallows during videofluoroscopy: 5 neutral head position, 30 chin-down posture, and then 10 neutral head position. Eight swallowing events were measured: the time of hyoid burst, bolus head in the pharynx, bolus tail in the pharynx, laryngeal vestibule closure (LVC), upper esophageal sphincter (UES) opening, bolus head in the UES, bolus tail exiting the pharynx, and laryngeal vestibule opening (LVO).

RESULTS

Our key finding is that LVC was one of the first 3 swallowing events in 69% of neutral swallows and in 78% of chin-down swallows (p = .006). Also, LVO occurred last in 14% of chin-down swallows but never occurred last in the preceding neutral swallows (p ≤ .001). Thus, in chin-down swallows, LVC occurred earlier and LVO occurred later.

CONCLUSIONS

The chin-down posture may be beneficial for individuals with delayed onset of LVC and reduced duration of the LVC. Future studies are needed to examine this effect in individuals with dysphagia.

Effectiveness of Chin-tuck Maneuver to Facilitate Swallowing in Neurologic Dysphagia

Introduction The chin-tuck maneuver is the most frequently employed postural maneuver in the treatment of neurogenic oropharyngeal dysphagia caused by encephalic vascular strokes and degenerative diseases.

Objective The purpose of this study was to investigate the effectiveness of this maneuver in patients with neurogenic dysphagia and factors that could interfere in it.

Methods In this retrospective cohort, we analyzed the medical files and videofluoroscopy exams of 35 patients (19 male – 54% and 16 female – 46%; age range between 20 and 89 years old; mean = 69 years).

Results The results suggest that the effectiveness of chin-tuck maneuver is related to the overall degree of dysphagia: the more severe the dysphagia, the less effective the maneuver.

Conclusion Chin-tuck maneuver should benefit dysphagic patients with delay in the swallowing trigger, reduced laryngeal elevation, and difficulties to swallow liquids, but is not the best compensatory strategy for patients with severe dysphagia.

The perturbation paradigm modulates error-based learning in a highly automated task: outcomes in swallowing kinematics

Traditional motor learning studies focus on highly goal-oriented, volitional tasks that often do not readily generalize to real-world movements. The goal of this study was to investigate how different perturbation paradigms alter error-based learning outcomes in a highly automated task. Swallowing was perturbed with neck surface electrical stimulation that opposes hyo-laryngeal elevation in 25 healthy adults (30 swallows: 10 preperturbation, 10 perturbation, and 10 postperturbation). The four study conditions were gradual-masked, gradual-unmasked, abrupt-masked, and abrupt-unmasked. Gradual perturbations increasingly intensified overtime, while abrupt perturbations were sustained at the same high intensity. The masked conditions reduced cues about the presence/absence of the perturbation (pre- and postperturbation periods had low stimulation), but unmasked conditions did not (pre- and postperturbation periods had no stimulation). Only hyo-laryngeal range of motion measures had significant outcomes; no timing measure demonstrated learning. Systematic-error reduction occurred only during the abrupt-masked and abrupt-unmasked perturbations. Only the abrupt-masked perturbation caused aftereffects. In this highly automated task, gradual perturbations did not induce learning similarly to findings of some volitional, goal-oriented adaptation task studies. Furthermore, our subtle and brief adjustment of the stimulation paradigm (masked vs. unmasked) determined whether aftereffects were present. This suggests that, in the unmasked group, sensory predictions of a motor plan were quickly and efficiently modified to disengage error-based learning behaviors.

Characterizing functional connectivity patterns during saliva swallows in different head positions

BACKGROUND

The anatomical rationale and efficacy of the chin tuck in improving airway protection for some people with swallowing disorders have been well researched and established. However, there are still open questions regarding whether brain activity for swallowing control is altered while performing this chin-tuck maneuver.

METHODS

In this study, we collected EEG signals from 55 healthy adults while swallowing in the neutral and chin-tuck head positions. The time-frequency based synchrony measure was used to form brain networks. We investigated both the small-world properties of these brain networks and differences among the constructed brain networks for the two head positions during swallowing tasks.

RESULTS

We showed that brain networks for swallowing in both head positions exhibit small-world properties. Furthermore, we showed that swallowing in the chin-tuck head position affects brain networks in the Alpha and Gamma frequency bands.

CONCLUSIONS

According to these results, we can tell that the parameter of head position should be considered in future investigations which utilize EEG signals during swallowing activity.

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.