Effects of a Sour Bolus on the Intramuscular Electromyographic (EMG) Activity of Muscles in the Submental Region

The impact of physical therapy on dysphagia in neurological diseases: a review

A neurogenic dysphagia is dysphagia caused by problems with the central and peripheral nervous systems, is particularly prevalent in conditions such as Parkinson's disease and stroke. It significantly impacts the quality of life for affected individuals and causes additional burdens, such as malnutrition, aspiration pneumonia, asphyxia, or even death from choking due to improper eating. Physical therapy offers a non-invasive treatment with high efficacy and low cost. Evidence supporting the use of physical therapy in dysphagia treatment is increasing, including techniques such as neuromuscular electrical stimulation, sensory stimulation, transcranial direct current stimulation, and repetitive transcranial magnetic stimulation. While initial studies have shown promising results, the effectiveness of specific treatment regimens still requires further validation. At present, there is a lack of scientific evidence to guide patient selection, develop appropriate treatment regimens, and accurately evaluate treatment outcomes. Therefore, the primary objectives of this review are to review the results of existing research, summarize the application of physical therapy in dysphagia management, we also discussed the mechanisms and treatments of physical therapy for neurogenic dysphagia.

Difference in the Electromyographic Behavior of the Masticatory and Swallowing Muscles During Cued Versus Spontaneous Swallowing

The risk of dysphagia and/or aspiration is determined using screening tests, such as the repeated saliva swallowing test and modified water swallowing test, which evaluate cued swallowing. However, humans masticate and swallow foods with various consistencies, forms, and amounts, without conscious awareness. Therefore, this study aimed to examine the difference in the behavior of masticatory and swallowing muscles during spontaneous versus cued swallowing through a series of mastication and swallowing processes by evaluating surface electromyogram (sEMG) signals. The effect of the consistency and amount of food on the behavior of these muscles was also investigated. The sEMG recordings of the masseter muscles and anterior belly of the digastric muscle for 12 subjects, and genioglossus muscle for 5 subjects were obtained. The genioglossus activity was recorded using custom-made ball electrodes. The test foods were cookies and tofu, in amounts of 2 g and 4 g. The normalized muscle activity (integrated EMG), duration of the muscle activity, initial activation timepoint of each muscle, and total duration of swallowing were compared among four conditions. The activity of each muscle was significantly higher during the swallowing of cookies than tofu, for 4 g vs 2 g, and for cued versus spontaneous swallowing. The duration of each muscle activity, initial activation timepoint, and total duration of swallowing were significantly longer for cookies versus tofu, for 4 g vs 2 g, and for spontaneous versus cued swallowing. These results suggest that the behavior of the masticatory and swallowing muscles is affected by cued swallowing and by the consistency and amount of food.

Assessment of Oral Masticatory Muscle Activity With Different Chewing Gums: A Cross-Sectional Study Based on Electromyogram Analysis

BACKGROUND

Facial muscles, particularly those involved in mastication, play a pivotal role in the chewing process. Despite their influence on chewing, these muscles undergo alterations during mastication. Examining the relationship between chewed substances and muscle activity can provide insights into various pathological processes and aid in the development of therapeutic chewing techniques.

AIM

This study aimed to evaluate the impact of different commercially available chewing gums on the activity of key masticatory muscles.

METHOD

Twenty-two participants were recruited for the study. They were instructed to chew four commercially available gums: group 1 comprised sugar gum with a strong flavor; group 2 included gum containing sorbitol; group 3 consisted of gum containing xylitol; and group 4 provided sugar gum with a mild flavor. Electromyogram (EMG) recordings were utilized to assess muscle activity. Various aspects of muscle activity, including chewing time, maximum muscle potential, and coordination between different muscles, were evaluated. Data tabulation and analysis were performed using IBM SPSS software version 23.0 (IBM Corp., Armonk, NY).

RESULT

Analysis revealed that in terms of temporalis symmetry, group 2 exhibited the highest mean deviation, while for masseter symmetry, group 3 demonstrated the highest mean deviation. The total deviation for the temporalis and masseter muscles was 72.16% and 65.55%, respectively, indicating greater symmetry in the temporalis muscle. Additionally, group 3 displayed the highest mean deviation in both left and right-sided synergic activity of the muscles. The total deviation for the right and left sides was 64.34% and 65.67%, respectively.

CONCLUSION

The findings suggest that sugar-free chewing gums elicit increased muscle activity compared to sugar-containing chewing gums. Furthermore, the utilization of calorie-free chewing gums with a firm texture was associated with better-coordinated muscle activity. These results provide valuable insights into the effects of different chewing gums on masticatory muscle function and coordination, which may have implications for therapeutic interventions and oral health management.

The importance of taste on swallowing function

The world's population is aging. Pneumonia is the leading cause of death among the older adults, with aspiration pneumonia being particularly common. Aspiration pneumonia is caused by a decline in swallowing function. Causes can include age-related sarcopenia of swallowing muscles, cognitive decline, cerebrovascular and other diseases or even changes in individual taste preference. Currently, the main treatment approach for dysphagia is resistance training of swallowing-related muscles. This approach has not been effective and establishment of novel methods are required. In this review, we introduce and discuss the relationship between taste, taste preference, carbonation and swallowing function. Taste and preference improve swallowing function. Recently, it has been shown that a carbonated beverage that combines the functionality of a thickening agent, the appeal of taste, and the stimulation of carbonation improves swallowing function. This may be very useful in the recovery of swallowing function. It is important to note that deliciousness is based not only on taste and preference, but also on visual information such as food form. Umami taste receptors are expressed not only in taste buds but also in skeletal muscle and small intestine. These receptors may be involved in homeostasis of the amino acid metabolic network, i.e., the process of amino acid ingestion, intestine absorption, and storage in skeletal muscle. Proper stimulation of umami receptors in organs other than taste buds may help maintain nutritional status and muscle mass. Umami receptors are therefore a potential therapeutic target for dysphagia.

A Matter of Taste: Roles of Taste Preference on Performance and Psychological Responses during Anaerobic Exercise

Various tastes including sweet, bitter, and sour have been shown to differentially influence physiological and psychological processes. Furthermore, ingestion of bitter and sweet solutions has been shown to acutely enhance exercise performance. However, the taste is highly individualized, and it is unclear if preference influences the ergogenic potential of taste. The purpose of this study was to investigate the effects of preferred and non-preferred drink tastes on anaerobic performance and psychological responses thereof. Physically active females participated in two counterbalanced sprint trials each with a different condition: (1) non-preferred taste (NPT), (2) Preferred taste (PT). Participants self-reported taste preferences (sweet, sour, bitter) with the highest-ranked taste being used for the PT condition and the lowest-ranked for NPT. For each visit, participants completed a 15 s Wingate Anaerobic Test (WAnT) prior to (PRE) ingestion of ~20 mL of their NP or PREF taste. Following ingestion, participants completed 2 min of active recovery, rated their taste preference of the solution, and completed another 15 s WAnT. The rate of perceived exertion (RPE), motivation, and enjoyment were measured through a visual analog scale following each WAnT. Anaerobic performance measures and heart rate (HR) were also obtained at the succession of each WAnT. Findings revealed no differences between taste conditions for mean power (p = 0.455), peak power (p = 0.824), or HR (p = 0.847). RPE was significantly lower with PT versus NPT (p = 0.006). Exercise enjoyment (p = 0.022) was higher with PT compared to NPT. NPT resulted in worse motivation compared to PRE (p = 0.001) while no changes were observed between PT and PRE (p = 0.197). These findings suggest that preferred drink taste may not enhance acute performance but improves psychological responses to maximal anaerobic exercise which may have implications for improving exercise training and adherence.

Toward a robust swallowing detection for an implantable active artificial larynx: a survey

Total laryngectomy consists in the removal of the larynx and is intended as a curative treatment for laryngeal cancer, but it leaves the patient with no possibility to breathe, talk, and swallow normally anymore. A tracheostomy is created to restore breathing through the throat, but the aero-digestive tracts are permanently separated and the air no longer passes through the nasal tracts, which allowed filtration, warming, humidification, olfaction, and acceleration of the air for better tissue oxygenation. As for phonation restoration, various techniques allow the patient to talk again. The main one consists of a tracheo-esophageal valve prosthesis that makes the air passes from the esophagus to the pharynx, and makes the air vibrate to allow speech through articulation. Finally, swallowing is possible through the original tract as it is now isolated from the trachea. Yet, many methods exist to detect and assess a swallowing, but none is intended as a definitive restoration technique of the natural airway, which would permanently close the tracheostomy and avoid its adverse effects. In addition, these methods are non-invasive and lack detection accuracy. The feasibility of an effective early detection of swallowing would allow to further develop an implantable active artificial larynx and therefore restore the aero-digestive tracts. A previous attempt has been made on an artificial larynx implanted in 2012, but no active detection was included and the system was completely mechanic. This led to residues in the airway because of the imperfect sealing of the mechanism. An active swallowing detection coupled with indwelling measurements would thus likely add a significant reliability on such a system as it would allow to actively close an artificial larynx. So, after a brief explanation of the swallowing mechanism, this survey intends to first provide a detailed consideration of the anatomical region involved in swallowing, with a detection perspective. Second, the swallowing mechanism following total laryngectomy surgery is detailed. Third, the current non-invasive swallowing detection technique and their limitations are discussed. Finally, the previous points are explored with regard to the inherent requirements for the feasibility of an effective swallowing detection for an artificial larynx. Graphical Abstract.

Effects of Food and Liquid Properties on Swallowing Physiology and Function in Adults

Foods and liquids have properties that are often modified as part of clinical dysphagia management to promote safe and efficient swallowing. However, recent studies have questioned whether this practice is supported by the evidence. To address this, a scoping review was conducted to answer the question: "Can properties of food and liquids modify swallowing physiology and function in adults?" Online search in six databases yielded a set of 4235 non-duplicate articles. Using COVIDENCE software, two independent reviewers screened the articles by title and abstract, and 229 full-text articles were selected for full-text review. One-hundred eleven studies met the inclusion criteria for qualitative synthesis and assessment of risk of bias. Three randomized controlled trials and 108 non-randomized studies were analyzed. Large amounts of variability in instrumental assessment, properties of food and liquids, and swallowing measures were found across studies. Sour, sweet, and salty taste, odor, carbonation, capsaicin, viscosity, hardness, adhesiveness, and cohesiveness were reported to modify the oral and pharyngeal phase of swallowing in both healthy participants and patients with dysphagia. Main swallow measures modified by properties of food and liquids were penetration/aspiration, oral transit time, lingual pressures, submental muscle contraction, oral and pharyngeal residue, hyoid and laryngeal movement, pharyngeal and upper esophageal sphincter pressures, and total swallow duration. The evidence pooled in this review supports the clinical practice of food texture and liquid consistency modification in the management of dysphagia with the caveat that all clinical endeavors must be undertaken with a clear rationale and patient-specific evidence that modifying food or liquid benefits swallow safety and efficiency while maintaining quality of life.

Effects of Carbonated Thickened Drinks on Pharyngeal Swallowing with a Flexible Endoscopic Evaluation of Swallowing in Older Patients with Oropharyngeal Dysphagia

This study aimed to determine the efficacy of carbonated and sweetened drinks added to thickened liquids, which are routinely used for patients with dysphagia to improve dysphagia. Patients swallowed thin liquid (Thin), thickened liquid (Thick), carbonated thin drink (C-Thin), and carbonated thickened drink (C-Thick) in random order. Penetration and/or aspiration were scored using the Penetration−Aspiration Scale (PAS). The residue was scored using the Yale Pharyngeal Residue Severity Rating Scale (YPR-SRS). Swallowing reflex initiation was scored using the Hyodo score. The subjective difficulty of swallowing was scored on a face scale. We analyzed 13 patients with a mean age of 79.6 ± 9.6 years. PAS was significantly lower in the C-Thick group than the Thin group (p < 0.05). Swallowing reflex initiation was significantly different between the Thin and Thick (p < 0.01) groups; moreover, post hoc analysis revealed that it was significantly lower in the C-Thick group than the Thin group (p < 0.01). The subjective difficulty of swallowing in the C-Thick was significantly lower than the Thick group (p < 0.05). C-Thick was easier to swallow than Thick and may improve penetration and/or aspiration in older patients with dysphagia with complex diseases.

The effect of taste on swallowing: A scoping and systematic review

Consuming foods and liquids for nutrition requires the coordination of several muscles. Swallowing is triggered and modified by sensory inputs from the aerodigestive tract. Taste has recently received attention as a potential modulator of swallowing physiology, function, and neural activation; additionally, taste impairment is a sequela of COVID-19. This review presents factors impacting taste and swallowing, systematically summarizes the existing literature, and assesses the quality of included studies. A search was conducted for original research including taste stimulation, deglutition-related measure(s), and human participants. Study design, independent and dependent variables, and participant characteristics were coded; included studies were assessed for quality and risk of bias. Forty-eight articles were included after abstract and full-text review. Synthesis was complicated by variable sensory components of stimuli (taste category and intensity, pure taste vs. flavor, chemesthesis, volume/amount, consistency, temperature), participant characteristics, confounding variables such as genetic taster status, and methods of measurement. Most studies had a high risk of at least one type of bias and were of fair or poor quality. Interpretation is limited by wide variability in methods, taste stimulation, confounding factors, and lower-quality evidence. Existing studies suggest that taste can modulate swallowing, but more rigorous and standardized research is needed.

White Paper by the European Society for Swallowing Disorders: Screening and Non-instrumental Assessment for Dysphagia in Adults

This White Paper by the European Society for Swallowing Disorders (ESSD) reports on the current state of screening and non-instrumental assessment for dysphagia in adults. An overview is provided on the measures that are available, and how to select screening tools and assessments. Emphasis is placed on different types of screening, patient-reported measures, assessment of anatomy and physiology of the swallowing act, and clinical swallowing evaluation. Many screening and non-instrumental assessments are available for evaluating dysphagia in adults; however, their use may not be warranted due to poor diagnostic performance or lacking robust psychometric properties. This white paper provides recommendations on how to select best evidence-based screening tools and non-instrumental assessments for use in clinical practice targeting different constructs, target populations and respondents, based on criteria for diagnostic performance, psychometric properties (reliability, validity, and responsiveness), and feasibility. In addition, gaps in research that need to be addressed in future studies are discussed. The following recommendations are made: (1) discontinue the use of non-validated dysphagia screening tools and assessments; (2) implement screening using tools that have optimal diagnostic performance in selected populations that are at risk of dysphagia, such as stroke patients, frail older persons, patients with progressive neurological diseases, persons with cerebral palsy, and patients with head and neck cancer; (3) implement measures that demonstrate robust psychometric properties; and (4) provide quality training in dysphagia screening and assessment to all clinicians involved in the care and management of persons with dysphagia.

Influence of Thermal and Gustatory Stimulus in the Initiation of the Pharyngeal Swallow and Bolus Location Instroke

INTRODUCTION/OBJECTIVE

The aim of this study is to analyze the influence of sour taste and cold temperature in the initiation of the pharyngeal swallow (IPS) and bolus location at pharyngeal swallow onset in individuals after stroke.

METHODS

Cross-sectional prospective study. The study included 52 individuals with unilateral ischemic stroke. Each individual was assessed by videofluoroscopic swallowing study with 5ml of paste bolus offering four different stimuli (natural, cold, sour, and sour-cold). The individuals were divided into two groups according to the offer sequence. Group 1 (G1) - received a randomized sequence of stimuli (24 individuals), and Group 2 (G2) -the stimuli were offered in the following order: natural, cold, sour, and sour-cold(28 individuals). The IPS time and bolus location at pharyngeal swallow onset were analyzed. The bolus location at pharyngeal swallow onset was defined using six different levels.

RESULTS

Individuals in G1 did not show a significant difference in IPS time between stimuli. However, individuals in G2 presented a significantly shorter IPS time with the sour and sour-cold stimuli than with natural or cold stimuli. The bolus location at pharyngeal swallow onset did not show significant difference between stimuli in both groups. On the other hand, in the G2 it was observed higher frequency of swallowing with sour-cold stimulus at level 1 (the bolus head was located in any region between the fauces pillar and the point where the tongue crosses the inferior border of the mandible).

CONCLUSION

The sour and sour-cold stimuli influenced the IPS time when they were offered in a sequential order. Moreover, both the IPS time and bolus location at pharyngeal swallow onset were not influenced by the sour and sour cold-bolus when offered in a random sequence.

Targeting Chemosensory Ion Channels in Peripheral Swallowing-Related Regions for the Management of Oropharyngeal Dysphagia

Oropharyngeal dysphagia, or difficulty in swallowing, is a major health problem that can lead to serious complications, such as pulmonary aspiration, malnutrition, dehydration, and pneumonia. The current clinical management of oropharyngeal dysphagia mainly focuses on compensatory strategies and swallowing exercises/maneuvers; however, studies have suggested their limited effectiveness for recovering swallowing physiology and for promoting neuroplasticity in swallowing-related neuronal networks. Several new and innovative strategies based on neurostimulation in peripheral and cortical swallowing-related regions have been investigated, and appear promising for the management of oropharyngeal dysphagia. The peripheral chemical neurostimulation strategy is one of the innovative strategies, and targets chemosensory ion channels expressed in peripheral swallowing-related regions. A considerable number of animal and human studies, including randomized clinical trials in patients with oropharyngeal dysphagia, have reported improvements in the efficacy, safety, and physiology of swallowing using this strategy. There is also evidence that neuroplasticity is promoted in swallowing-related neuronal networks with this strategy. The targeting of chemosensory ion channels in peripheral swallowing-related regions may therefore be a promising pharmacological treatment strategy for the management of oropharyngeal dysphagia. In this review, we focus on this strategy, including its possible neurophysiological and molecular mechanisms.

The investigation of asymptomatic swallowing disorder through surface electromyography in the geriatric population

AIM

Swallowing is a vital activity. The difficulty while swallowing, referred to as swallowing disorder, is strongly associated with serious health problems in the elderly. The aim of this study is to enable early recognition of the swallowing function developing as an asymptomatic condition.

METHOD

Our study was conducted on elderly populations aged 65 years and over who met the exclusion criteria. Firstly, to be able to reach the number of sampling, "EAT-10 questionnaire", which also has a Turkish validation, was used to eliminate those with symptomatic swallowing disorders. The number of patients we reached was 320, but 7 dropped out of the study and therefore the study was carried out with a total of 313 [reached as 97.8% (up 95% G-power)].

RESULT

We used validated sEMG test in the quantitative (objective) detection of asymptomatic swallowing disorder. In this method, asymptomatic swallowing disorder was detected in 39 cases (12.4%).

CONCLUSION

Swallowing disorder without symptoms is frequent and the sEMG test is useful in detecting it in the elderly population.

Variations in the amplitude and duration of hyolaryngeal elevation during swallow: Effect of sour and carbonated liquid bolus

BACKGROUND

Altering sensory properties of food is relevant to the management of swallowing disorders. The current investigation aimed to examine the influence of sour and carbonated stimuli on measures of hyolaryngeal elevation.

METHOD

Sixty healthy adults in the age range of 18 to 35 years were assessed using Digital Accelerometry Swallowing Imaging (DASI) while swallowing 5 ml of neutral, sour and carbonated liquid bolus.

RESULTS

Sour stimulus was significantly different with higher amplitude and longer durational measures of hyolaryngeal elevation compared to the two other stimuli.

CONCLUSION

Sour stimulus facilitates better hyolaryngeal elevation, which implicates its usage in dysphagia management.

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

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

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.

Taste Manipulation and Swallowing Mechanics in Trauma-Related Sensory-Based Dysphagia

Purpose This study explored the effects of high-concentration taste manipulation trials on swallow function in persons with sensory-based dysphagia. Method Dysphagia researchers partnered with clinical providers to prospectively identify traumatically injured U.S. military service members (N = 18) with sensory-based dysphagia as evidenced by delayed initiation and/or decreased awareness of residue/penetration/aspiration. Under videofluoroscopy, participants swallowed trials of 3 custom-mixed taste stimuli: unflavored (40% weight/volume [wt/vol] barium sulfate in distilled water), sour (2.7% wt/vol citric acid in 40% wt/vol barium suspension), and sweet-sour (1.11% wt/vol citric acid plus 8% wt/vol sucrose in 40% wt/vol barium suspension). Trials were analyzed and compared via clinical rating tools (the Modified Barium Swallow Impairment Profile [Martin-Harris et al., 2008] and the Penetration-Aspiration Scale [Rosenbek, Robbins, Roecker, Coyle, & Wood, 1996]). Additionally, a computational analysis of swallowing mechanics (CASM) was applied to a subset of 9 swallows representing all 3 tastants from 3 participants. Results Friedman's tests for the 3 stimuli revealed significantly (p < .05) improved functional ratings for Penetration-Aspiration Scale and pharyngoesophageal opening. CASM indicated differences in pharyngeal swallowing mechanics across all tastant comparisons (p ≤ .0001). Eigenvectors revealed increased tongue base retraction, hyoid elevation, and pharyngeal shortening for sweet-sour and, to a lesser extent, sour than for unflavored boluses. Conclusion Advantageous changes in certain parameters of oropharyngeal swallowing physiology were noted with high-intensity tastants per both clinical ratings and subsequent CASM, suggesting potential therapeutic application for taste manipulation.

A pilot study of modified resection for anterior floor of the mouth squamous cell carcinoma without infiltration of the mandible

OBJECTIVE

To explore the application of modified resection compared with traditional segmental resection of the mandible for patients with anterior floor of the mouth and tongue squamous cell carcinoma (SCC) without infiltration of the mandible.

SUBJECTS AND METHODS

This is a retrospective study including 36 eligible patients with anterior floor of the mouth SCC(9 patients received modified mandibulectomy, and 27 patients received segmental mandibulectomy).

RESULTS

No patients in the modified mandibulectomy group developed recurrence in the floor of the mouth, and all of the patients survived. Only one patient developed osteoradionecrosis. When the modified mandibulectomy group was compared with the segmental mandibulectomy group, the former exhibited a lower recurrence rate in the floor of the mouth (0.0% vs. 14.8%), less blood loss (516.7 ± 70.7 ml vs. 533.3 ± 93.0 ml), shorter durations of gastric tube placement (11.4 ± 4.5 days vs. 20.7 ± 11.9 days) and tracheostomy (6.9 ± 0.6 days vs. 8.5 ± 1.6 days), a lower postoperative infection rate (11.1% vs. 18.5%), and a shorter postoperative hospital stay (13.7 ± 3.8 days vs. 15.9 ± 5.1 days).

CONCLUSION

This modified mandibulectomy method is safe and feasible and is recommended for further prospective study in a clinical setting.

Saliva Production and Enjoyment of Real-Food Flavors in People with and Without Dysphagia and/or Xerostomia

Non-food gustatory stimulation has multiple potential therapeutic benefits for people with dysphagia and xerostomia. This study examined palatability and saliva flow associated with dissolvable flavored films. Taste strips with real-food flavors dissolved on the tongues of 21 persons with dysphagia and/or xerostomia and 21 healthy age- and sex-matched adults while sublingual gauze pads absorbed saliva over randomized 3-min trials. Participants rated taste enjoyment for each trial on a hedonic general labeled magnitude scale. Flavored strips elicited more saliva than baseline for both groups, and production was higher for controls than patients (M = 2.386 and 1.091 g, respectively; p = 0.036). Main effects of flavor were observed for saliva production (p = 0.002) and hedonics (p < 0.001). Hedonic ratings and saliva production were weakly correlated (r = 0.293, p < 0.001). Results support dissolvable taste strips as a tool for providing low-risk taste stimulation in dysphagia and for eliciting an increase in saliva flow that may provide temporary relief from dry mouth symptoms. The preferred flavors were, on average, also the ones that elicited greater saliva production. Taste strips have the potential to be beneficial for swallowing-related neural activity, timing, and safety in dysphagia. Further, they may ameliorate complications of xerostomia.

Orosensory contributions to dysphagia: a link between perception of sweet and sour taste and pharyngeal delay time

Pharyngeal delay is a significant swallowing disorder often resulting in aspiration. It is suspected that pharyngeal delay originates from sensory impairment, but a direct demonstration of a link between oral sensation and pharyngeal delay is lacking. In this study involving six patients with complaints of dysphagia, taste sensation of the oral tongue was measured and subsequently related to swallowing kinematics. It was found that a response bias for sour taste was significantly correlated with pharyngeal delay time on paste, highlighting oral sensory contributions to swallow motor dysfunctions. Investigating the precise nature of such a link between oral sensation and dysphagia would constitute a basis for understanding the disorder. The results of this study highlight oral sensory contributions to pharyngeal swallow events and provide impetus to examine this link in larger samples of dysphagic patients.

Using sensory properties of food to trigger swallowing: a review

The effect of food consistency on swallowing function has been widely studied, and it is well recognized that by delaying the flow of the food bolus, thickened liquids can help in the management of swallowing dysfunction. However, fewer studies have been carried out on the impact of food sensory properties and related liking on swallowing function. This paper reviews the role of taste, olfaction, and trigeminal perceptions on swallowing function and highlights the need for a deeper investigation of this aspect of patient diet modification.

Electromyography of Swallowing with Fine Wire Intramuscular Electrodes in Healthy Human: Amplitude Difference of Selected Hyoid Muscles

Few studies have examined the intensity of muscle activity during swallowing in healthy humans. We examined selected hyoid muscles using fine wire intramuscular electromyography (EMG) during swallowing of four food consistencies. Thirteen healthy adults were studied using videofluorography and EMG of the anterior belly of digastric (ABD), geniohyoid (GH), sternohyoid (SH), and masseter (MA; surface electrodes) while ingesting thin liquid (three trials) and solid food of three consistencies (banana, tofu, and cookie, three trials each). After rectification, integration, and normalization, peak EMG amplitudes for each muscle in each trial were measured. Hyoid displacements were measured in two dimensions. Data were analyzed using repeated measures ANOVA with Bonferroni correction. GH had the highest adjusted amplitude for both solids and liquid. For MA and ABD, amplitude was highest with triturated cookie. For ABD, amplitude was lowest with liquid. There were no significant food consistency effects for GH or SH. Hyoid displacements were greatest for cookie and the lowest for liquid. EMG amplitude varied with initial food consistency. The high peak EMG amplitude of GH is consistent with its essential role in opening the upper esophageal sphincter. High MA amplitude with hard solid foods is likely due to the higher tongue-palate pressure with triturated solids. The higher ABD amplitude with solid food is associated with greater hyoid displacement. These findings support the existence of a central pattern generator that modifies the level of muscle activity during pharyngeal swallowing in response to input from mechanoreceptors in the oral cavity.

ACIDIC AND NEUTRAL LIQUID INGESTION IN PATIENTS WITH GASTROESOPHAGEAL REFLUX DISEASE

Context Sour acidic liquid has a slower distal esophageal transit than a neutral liquid. Our hypothesis was that an acidic sour bolus has a different ingestion dynamic than a neutral bolus. Method In 50 healthy volunteers and 29 patients with gastroesophageal reflux disease (GERD), we evaluated the ingestion dynamics of 100 mL of acidic sour liquid (concentrated lemon juice, pH: 3.0) and 100 mL of water (pH: 6.8). The time to ingest the total volume, the number of swallows to ingest the volume, the interval between swallows, the flux of ingestion and the volume ingested in each swallow was measured. Results In both groups, healthy volunteers and patients in treatment for GERD, the acidic liquid took longer to be ingested, a higher number of swallows, a slower flux of ingestion and a smaller volume in each swallow than the neutral bolus. There was no difference between healthy volunteers and patients with GERD. The ingestion in women was longer than in men for acidic and neutral liquids. Conclusion Acidic liquid has a different dynamic of ingestion than the neutral liquid, which may be consequence of the slower transit through the distal esophageal body or an anticipation to drink a sour bolus. Patients with GERD have the same prolonged ingestion of the acidic liquid bolus as seen in healthy volunteers.

Barium versus nonbarium stimuli: differences in taste intensity, chemesthesis, and swallowing behavior in healthy adult women

PURPOSE

The authors examined the impact of barium on the perceived taste intensity of 7 different liquid tastant stimuli and the modulatory effect that these differences in perceived taste intensity have on swallowing behaviors.

METHOD

Participants were 80 healthy women, stratified by age group (<40; >60) and genetic taste status (supertasters; nontasters). Perceived taste intensity and chemesthetic properties (fizziness; burning-stinging) were rated for 7 tastant solutions (each prepared with and without barium) using the general Labeled Magnitude Scale. Tongue-palate pressures and submental surface electromyography (sEMG) were simultaneously measured during swallowing of these same randomized liquids. Path analysis differentiated the effects of stimulus, genetic taste status, age, barium condition, taste intensity, and an effortful saliva swallow strength covariate on swallowing.

RESULTS

Barium stimuli were rated as having reduced taste intensity compared with nonbarium stimuli. Barium also dampened fizziness but did not influence burning-stinging sensation. The amplitudes of tongue-palate pressure or submental sEMG did not differ when swallowing barium versus nonbarium stimuli.

CONCLUSIONS

Despite impacting taste intensity, the addition of barium to liquid stimuli does not appear to alter behavioral parameters of swallowing. Barium solutions can be considered to elicit behaviors that are similar to those used with nonbarium liquids outside the assessment situation.

Differences in swallowing between high and low concentration taste stimuli

Taste is a property that is thought to potentially modulate swallowing behavior. Whether such effects depend on taste, intensity remains unclear. This study explored differences in the amplitudes of tongue-palate pressures in swallowing as a function of taste stimulus concentration. Tongue-palate pressures were collected in 80 healthy women, in two age groups (under 40, over 60), stratified by genetic taste status (nontasters, supertasters). Liquids with different taste qualities (sweet, sour, salty, and bitter) were presented in high and low concentrations. General labeled magnitude scale ratings captured perceived taste intensity and liking/disliking of the test liquids. Path analysis explored whether factors of taste, concentration, age group, and/or genetic taste status impacted: (1) perceived intensity; (2) palatability; and (3) swallowing pressures. Higher ratings of perceived intensity were found in supertasters and with higher concentrations, which were more liked/disliked than lower concentrations. Sweet stimuli were more palatable than sour, salty, or bitter stimuli. Higher concentrations elicited stronger tongue-palate pressures independently and in association with intensity ratings. The perceived intensity of a taste stimulus varies as a function of stimulus concentration, taste quality, participant age, and genetic taste status and influences swallowing pressure amplitudes. High-concentration salty and sour stimuli elicit the greatest tongue-palate pressures.

Influence of the perceived taste intensity of chemesthetic stimuli on swallowing parameters given age and genetic taste differences in healthy adult women

PURPOSE

This study examined whether the perceived taste intensity of liquids with chemesthetic properties influenced lingua-palatal pressures and submental surface electromyography (sEMG) in swallowing, compared with water.

METHOD

Swallowing was studied in 80 healthy women, stratified by age group and genetic taste status. General Labeled Magnitude Scale ratings of taste intensity were collected for deionized water; carbonated water; 2.7% w/v citric acid; and diluted ethanol. These stimuli were swallowed, with measurement of tongue-palate pressures and submental sEMG. Path analysis differentiated stimulus, genetic taste status, age, and perceived taste intensity effects on swallowing. Signal amplitude during effortful saliva swallowing served as a covariate representing participant strength.

RESULTS

Significant differences (p < .05) in taste intensity were seen across liquids: citric acid > ethanol > carbonated water > water. Supertasters perceived greater taste intensity than did nontasters. Lingua-palatal pressure and sEMG amplitudes were correlated with the strength covariate. Anterior palate pressures and sEMG amplitudes were significantly higher for the citric acid stimulus. Perceived taste intensity was a significant mediator of stimulus differences.

CONCLUSION

These data provide confirmatory evidence that high-intensity sour stimuli do influence swallowing behaviors. In addition, taste genetics influence the perception of taste intensity for stimuli with chemesthetic properties, which modulates behavioral responses.

Dynamic change in hyoid muscle length associated with trajectory of hyoid bone during swallowing: analysis using 320-row area detector computed tomography

Research on muscle activation patterns during swallowing has been limited. Newly developed 320-row area detector computed tomography (320-ADCT) has excellent spatial and temporal resolution, which facilitates identification of laryngopharyngeal structures and quantitative kinematic analysis of pharyngeal swallowing. We investigated muscle activity patterns by observing the changes in length of hyoid muscles. 320-ADCT was performed in 26 healthy males while swallowing. The following parameters were analyzed three-dimensionally: 1) origins and insertions of the stylohyoid, anterior and posterior digastric, mylohyoid, geniohyoid, and thyrohyoid muscles; and 2) movement of the hyoid bone. The stylohyoid, posterior digastric, and mylohyoid muscles began to shorten simultaneously during the initial stage of swallowing. The shortening of these muscles occurred during the upward movement of the hyoid bone. Subsequently, the geniohyoid, thyrohyoid, and anterior digastric muscles began to shorten, synchronizing with the forward movement of the hyoid bone. A significant correlation was observed between the shortened muscle lengths of the stylohyoid, posterior digastric, and mylohyoid muscles and the upward movement of the hyoid bone ( r = 0.45–0.65). A correlation was also observed between the shortened muscle length of the geniohyoid muscle and the forward movement of the hyoid bone ( r = 0.61). In this study, the sequence of muscle activity during pharyngeal swallowing remained constant. Serial shortening of the hyoid muscles influenced the trajectory of the hyoid bone. The stylohyoid, posterior digastric, and mylohyoid muscles initiated the swallowing reflex and contributed to upward movement of the hyoid bone. The geniohyoid is a key muscle in the forward movement of the hyoid bone.

The effect of barium on perceptions of taste intensity and palatability

Barium may affect the perception of taste intensity and palatability. Such differences are important considerations in the selection of dysphagia assessment strategies and interpretation of results. Eighty healthy women grouped by age (younger, older) and genetic taste status (supertaster, nontaster) rated intensity and palatability for seven tastants prepared in deionized water with and without 40 % w/v barium: noncarbonated and carbonated water, diluted ethanol, and high concentrations of citric acid (sour), sodium chloride (salty), caffeine (bitter), and sucrose (sweet). Mixed-model analyses explored the effects of barium, taster status, and age on perceived taste intensity and acceptability of stimuli. Barium was associated with lower taste intensity ratings for sweet, salty, and bitter tastants, higher taste intensity in carbonated water, and lower palatability in water, sweet, sour, and carbonated water. Older subjects reported lower palatability (all barium samples, sour) and higher taste intensity scores (ethanol, sweet, sour) compared to younger subjects. Supertasters reported higher taste intensity (ethanol, sweet, sour, salty, bitter) and lower palatability (ethanol, salty, bitter) than nontasters. Refusal rates were highest for younger subjects and supertasters, and for barium (regardless of tastant), bitter, and ethanol. Barium suppressed the perceived intensity of some tastes and reduced palatability. These effects are more pronounced in older subjects and supertasters, but younger supertasters are least likely to tolerate trials of barium and strong tastant solutions.

Effect of bolus taste on the esophageal transit of patients with stroke

Stroke is a frequent cause of oropharyngeal dysphagia but may also cause alterations in esophageal motility. The aim of this investigation was to evaluate the effect of bolus taste on the esophageal transit of patients with stroke and controls. Esophageal transit and clearance were evaluated by scintigraphy in 36 patients in the chronic phase of stroke (44-82 years, mean: 63 years) and in 30 controls (33-85 years, mean: 59 years). The patients had a stroke 1-84 months (median: 5.5 months) before the evaluation of esophageal transit. Eight had dysphagia. Each subject swallowed in random order and in the sitting position 5 mL of liquid boluses with bitter (pH=6.0), sour (pH=3.0), sweet (pH=6.9), and neutral (pH=6.8) taste. Transit and clearance duration and the amount of residues were measured in the proximal, middle, and distal esophageal body. There was no difference between patients and controls in esophageal transit or clearance duration. In the distal esophagus, the transit and clearance durations were longer with the sour bolus than with the other boluses in both patients and controls. The amount of residues in the esophageal body was greater in patients than in controls after swallows of the neutral bolus. In control subjects, after swallows of a sour bolus, there was an increase in the amount of residues in the middle and distal esophagus compared with the other boluses. In conclusion, a sour bolus with low pH causes a longer transit and clearance duration in the distal esophageal body. There was no effect of bolus taste or pH on the esophageal transit of patients in the chronic phase of stroke compared with normal volunteers. The longer transit and clearance duration in the distal esophageal body with the sour bolus appears to be a consequence of the low pH of the bolus.

Sour taste and cold temperature in the oral phase of swallowing in patients after stroke

PURPOSE: To determine the effect of sour flavor and cold temperature on oral transit time during swallowing. METHODS: Participants were 52 subjects (28 male and 24 female) with ages between 50 and 80 years (median=66 years), after ischemic stroke involving right or left side damage and mild to moderate oropharyngeal dysphagia. Videofluoroscopy was performed to analyze the swallowing times. Each subject was assessed during swallowing of a paste consistency bolus offered in 5 ml spoons, with a total of four different stimuli (natural, cold, sour and sour-cold). After the exam, the oral transit time was measured using specific software. The oral transit time (starting at the beginning of the bolus movement in the mouth) and the total oral transit time (starting at the moment that the bolus is placed in the mouth) were measured. RESULTS: The association between sour and cold stimuli caused a significant decrease of oral transit time and total oral transit time. CONCLUSION: Sour flavor and cold temperature reduced oral transit time in stroke patients.

New directions for understanding neural control in swallowing: the potential and promise of motor learning

Oropharyngeal swallowing is a complex sensorimotor phenomenon that has had decades of research dedicated to understanding it more thoroughly. However, the underlying neural mechanisms responsible for normal and disordered swallowing remain very vague. We consider this gap in knowledge the result of swallowing research that has been broad (identifying phenomena) but not deep (identifying what controls the phenomena). The goals of this review are to address the complexity of motor control of oropharyngeal swallowing and to review the principles of motor learning based on limb movements as a model system. We compare this literature on limb motor learning to what is known about oropharyngeal function as a first step toward suggesting the use of motor learning principles in swallowing research.

Taste and temperature in swallowing transit time after stroke

Background

Oropharyngeal dysphagia is common in individuals after stroke. Taste and temperature are used in dysphagia rehabilitation. The influence of stimuli, such as taste and temperature, on swallowing biomechanics has been investigated in both healthy individuals and in individuals with neurological disease. However, some questions still remain unanswered, such as how the sequence of offered stimuli influences the pharyngeal response. The goal of the present study was to determine the influence of the sequence of stimuli, sour taste and cold temperature, on pharyngeal transit time during deglutition in individuals after stroke.

Methods

The study included 60 individuals with unilateral ischemic stroke, 29 males and 31 females, aged 41–88 years (mean age: 66.2 years) examined 0–50 days after ictus (median: 6 days), with mild to moderate oropharyngeal dysphagia. Exclusion criteria were hemorrhagic stroke patients, patients with decreased level of consciousness, and clinically unstable patients, as confirmed by medical evaluation. The individuals were divided into two groups of 30 individuals each. Group 1 received a nonrandomized sequence of stimuli (i.e. natural, cold, sour, and sour-cold) and group 2 received a randomized sequence of stimuli. A videofluoroscopic swallowing study was performed to analyze the pharyngeal transit time. Four different stimuli (natural, cold, sour, and sour-cold) were offered. The images were digitalized and specific software was used to measure the pharyngeal transit time. Since the values did not present regular distribution and uniform variances, nonparametric tests were performed.

Results

Individuals in group 1 presented a significantly shorter pharyngeal transit time with the sour-cold stimulus than with the other stimuli. Individuals in group 2 did not show a significant difference in pharyngeal transit time between stimuli.

Conclusions

The results showed that the sequence of offered stimuli influences the pharyngeal transit time in a different way in individuals after stroke and suggest that, when the sour-cold stimulus is offered in a randomized sequence, it can influence the response to the other stimuli in stroke patients. Hence, the sour-cold stimulus could be used as a therapeutic aid in dysphagic stroke patients.

Main taste effects on swallowing apnea duration in healthy adults

OBJECTIVE

This study examined swallowing apnea duration (SAD) and respiratory phase patterns as a function of taste, tastes combined with barium, age, and genetic taste group.

STUDY DESIGN

Prospective group design.

SETTING

University medical center.

SUBJECTS AND METHODS

Eighty healthy adult women were identified as nontasters and supertasters and equally comprised 2 age groups: 18 to 35 years (n = 40) and 60+ years (n = 40). The KayPentax Swallowing Signals Lab was used to acquire SAD and respiratory phase patterns via nasal cannula during randomized 5-mL swallows of water, 1.0 M sucrose (sweet), 1.0 M sodium chloride (salty), and 0.032 M caffeine (bitter) alone and mixed with barium. The SAD and respiratory patterns were analyzed in a linear mixed model and a binary logistic regression generalized estimating equation model, respectively.

RESULTS

A significant main effect of age was found (P = .007). Older women demonstrated longer SAD than younger women. There were no significant effects of taste or genetic taste group on SAD. There was a significant interaction between barium and supertaster status; SAD was shorter in supertasters when barium was included. There were no significant differences in respiratory patterns between age groups, genetic taste groups, or among taste stimuli.

CONCLUSION

Advanced age elicited longer SAD, a robust finding in repeated investigations from multiple laboratories. Main tastes did not affect SAD or respiratory phase patterns. Genetic taste group altered SAD when barium was combined with the taste. That is, taste + barium shortened SAD in supertasters. This finding may affect clinical management of dysphagia patients and warrants further investigation.

Adaptation of swallowing hyo-laryngeal kinematics is distinct in oral vs. pharyngeal sensory processing

Before a bolus is pushed into the pharynx, oral sensory processing is critical for planning movements of the subsequent pharyngeal swallow, including hyoid bone and laryngeal (hyo-laryngeal) kinematics. However, oral and pharyngeal sensory processing for hyo-laryngeal kinematics is not fully understood. In 11 healthy adults, we examined changes in kinematics with sensory adaptation, sensitivity shifting, with oropharyngeal swallows vs. pharyngeal swallows (no oral processing), and with various bolus volumes and tastes. Only pharyngeal swallows showed sensory adaptation (gradual changes in kinematics with repeated exposure to the same bolus). Conversely, only oropharyngeal swallows distinguished volume differences, whereas pharyngeal swallows did not. No taste effects were observed for either swallow type. The hyo-laryngeal kinematics were very similar between oropharyngeal swallows and pharyngeal swallows with a comparable bolus. Sensitivity shifting (changing sensory threshold for a small bolus when it immediately follows several very large boluses) was not observed in pharyngeal or oropharyngeal swallowing. These findings indicate that once oral sensory processing has set a motor program for a specific kind of bolus (i.e., 5 ml water), hyo-laryngeal movements are already highly standardized and optimized, showing no shifting or adaptation regardless of repeated exposure (sensory adaptation) or previous sensory experiences (sensitivity shifting). Also, the oral cavity is highly specialized for differentiating certain properties of a bolus (volume) that might require a specific motor plan to ensure swallowing safety, whereas the pharyngeal cavity does not make the same distinctions. Pharyngeal sensory processing might not be able to adjust motor plans created by the oral cavity once the swallow has already been triggered.

The influence of stimulus taste and chemesthesis on tongue movement timing in swallowing

PURPOSE

To explore the influence of taste and trigeminal irritation (chemesthesis) on durational aspects of tongue movement in liquid swallowing, controlling for the influence of perceived taste intensity.

METHOD

Electromagnetic midsagittal articulography was used to trace tongue movements during discrete liquid swallowing with 5 liquids: water, 3 moderate concentration tastants without odor (sweet, sour, sweet-sour), and a high concentration of citric acid (sour taste plus chemesthesis). Participants were 33 healthy adults in 2 gender-balanced, age-stratified groups (under/over 50). Perceived taste intensity was measured using the Generalized Labeled Magnitude Scale (Bartoshuk, 2000; Bartoshuk et al., 2004). Tongue movement sequencing and durations of the composite tongue movement envelope and component events (rise phase, location of first movement peak, release phase) were calculated.

RESULTS

No obligate sequence of tongue segment movement was observed. Overall durations and the timing of the first movement peak were significantly longer with water than with the moderate concentration of sweet-sour liquid. Perceived taste intensity did not modulate stimulus effects in a significant way. The expected pattern of shorter movement durations with the high concentration of citric acid was not seen.

CONCLUSIONS

A chemesthetic-taste stimulus of high citric acid did not influence the durations of tongue movements compared with those seen during the swallowing of moderate concentration tastants and water.