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

The effects of simulated gastroesophageal reflux on infant pig oropharyngeal feeding physiology

The neural connectivity among the oral cavity, pharynx, and esophagus is a critical component of infant feeding physiology. Central integration of oral and pharyngeal afferents alters motor outputs to structures that power swallowing, but the potential effects of esophageal afferents on preesophageal feeding physiology are unclear. These effects may explain the prevalence of oropharyngeal dysphagia in infants suffering from gastroesophageal reflux (GER), though the mechanism underlying this relationship remains unknown. Here we use the validated infant pig model to assess the impacts of simulated GER on preesophageal feeding parameters. We used high-speed videofluoroscopy and electromyography to record bottle-feeding before and following the infusion of a capsaicin-containing solution into the lower esophagus. Sucking parameters were minimally affected by capsaicin exposure, such that genioglossus activity was unchanged and tongue kinematics were largely unaffected. Aspects of the pharyngeal swallow were altered with simulated GER, including increased thyrohyoid muscle activity, increased excursions of the hyoid and thyroid per swallow, decreased swallow frequency, and increased bolus sizes. These results suggest that esophageal afferents can elicit changes in pharyngeal swallowing. In addition, decreased swallowing frequency may be the mechanism by which esophageal pathologies induce oropharyngeal dysphagia. Although recent work indicates that oral or pharyngeal capsaicin may improve dysphagia symptoms, the decreased performance following esophageal capsaicin exposure highlights the importance of designing sensory interventions based upon neurophysiology and the mechanisms underlying disordered feeding. This mechanistic approach requires comprehensive data collection across the entirety of the feeding process, which can be achieved using models such as the infant pig.NEW & NOTEWORTHY Simulated gastroesophageal reflux (GER) in an infant pig model resulted in significant changes in pharyngeal swallowing, which suggests that esophageal afferents are centrally integrated to alter motor outputs to the pharynx. In addition, decreased swallow frequency and increased bolus sizes may be underlying mechanisms by which esophageal pathologies induce oropharyngeal dysphagia. The infant pig model used here allows for a mechanistic approach, which can facilitate the design of intervention strategies based on neurophysiology.

Gustatory stimulus interventions for older adults with dysphagia: a scoping review

BACKGROUND

Gustatory stimulus interventions have been shown to improve swallowing function in older adults with dysphagia. However, the optimal intervention strategies as well as their effects and safety remain unclear.

AIMS

To explore current evidence regarding gustatory stimulus interventions for dysphagia in older adults.

METHODS

Nine electronic databases (PubMed, Web of Science, Embase, CINAHL, Cochrane Library, China National Knowledge Infrastructure, Wanfang Database, China Science and Technology Journal Database, and Sinomed) were searched from their inception to August 2022.

RESULTS

This review identified 263 articles, and 15 met the inclusion criteria. The types of gustatory stimulus interventions included spicy (n = 10), sour (n = 3), and mixed (sour-sweet) stimuli (n = 2), with most studies focusing on spicy stimuli. The most frequently reported spicy stimulus was capsaicin. Further, the most commonly reported intervention frequency was thrice a day before meals for 1-4 weeks. The stimuli concentrations and dosages could not be standardized due to the among-study heterogeneity. These studies reported 16 assessment tools and 42 outcomes, which mainly included videofluoroscopy and swallowing response time respectively. More than half of the included studies reported no adverse effects of gustatory stimulus interventions.

CONCLUSION AND DISCUSSIONS

Gustatory stimulus interventions improved swallowing function in older adults with dysphagia. However, assessment tools and outcomes for dysphagia should be standardized in the future, and explore personalized interventions based on different diseases and their stages, to determine the most cost-effective interventions, and to prevent its complications.

Oropharyngeal dysphagia and cachexia: Intertwined in head and neck cancer

BACKGROUND

This study aims to investigate the relationship between cancer cachexia and oropharyngeal dysphagia (OD) in patients with head and neck cancer (HNC) prior to chemoradiotherapy or bioradiotherapy (CRT/BRT).

METHODS

A prospective cohort study with patients with HNC undergoing CRT/BRT (2018-2021) was conducted. Body composition and skeletal muscle function were evaluated using bioelectrical impedance analysis, handgrip strength, and the short physical performance battery (SPPB). The M. D. Anderson Dysphagia Inventory (MDADI), Eating Assessment Tool (EAT)-10 questionnaire, and patient characteristics were collected. A standardized videofluoroscopic swallowing study was offered to patients.

RESULTS

Sixty-six patients were included. Twenty-six patients scored EAT-10 ≥ 3 and seventeen were cachectic. ACE-27 score >1, cachexia, abnormal SPPB-derived repeated chair-stand test, lower MDADI scores, and higher overall stage grouping showed potential predictive value (p ≤ 0.10) for EAT-10 ≥ 3. Using multivariable regression analysis, only cachexia remained a significant predictor of EAT-10 ≥ 3 (HR 9.000 [95%CI 2.483-32.619], p = 0.001).

CONCLUSION

Cachexia independently predicted the presence of patient-reported OD.

Reversal of the effects of focal suppression on pharyngeal corticobulbar tracts by chemesthesis coupled with repeated swallowing

BACKGROUND

Previous reports suggested the potential benefit of chemesthesis in the form of carbonated water (CW) integrated within dysphagia rehabilitation protocols. Here, we examined the effects of CW within a repeated swallowing protocol following focal suppression to pharyngeal cortical representation as a prelude to its application in dysphagic patients.

METHODS

Fourteen healthy volunteers participated in a 3-arm study. Each participant underwent baseline corticobulbar pharyngeal and thenar motor-evoked potential (MEP) measurements with Transcranial Magnetic Stimulation (TMS). Subjects were then conditioned with 1Hz repetitive (r)TMS to induce focal unilateral suppression of the corticopharyngeal hotspot before randomization to each of three arms with 40 swallows of CW, non-CW and saliva swallowing on separate days. Corticobulbar and thenar MEPs were collected for up to 1 h and analyzed using repeated measures (rm)ANOVA.

RESULTS

A 2-way rmANOVA for Intervention x Time showed a significant effect of Intervention (F_(1,13)  = 7.519, p = 0.017) in both ipsi- and contra-lesional corticopharyngeal projections. Carbonation showed superiority in facilitating change by increasing pharyngeal cortical MEPs compared to non-CW (z = -3.05, p = 0.002) and saliva swallowing (z = -2.6, p = 0.008). No change in thenar representation (control) was observed nor in MEP latencies from both pharyngeal and thenar musculature.

CONCLUSIONS

We conclude that interventional paradigms with CW have the capacity to reverse the effects of a focal suppression with 1Hz rTMS more strongly than non-CW or saliva swallowing alone, producing site specific bi-hemispheric changes in corticopharyngeal excitability. Our data suggest that carbonation produces the effects through a mainly cortical mechanism.

Molecular and Neural Mechanism of Dysphagia Due to Cancer

Cancer is one of the most common causes of death worldwide. Along with the advances in diagnostic technology achieved through industry–academia partnerships, the survival rate of cancer patients has improved dramatically through treatments that include surgery, radiation therapy, and pharmacotherapy. This has increased the population of cancer “survivors” and made cancer survivorship an important part of life for patients. The senses of taste and smell during swallowing and cachexia play important roles in dysphagia associated with nutritional disorders in cancer patients. Cancerous lesions in the brain can cause dysphagia. Taste and smell disorders that contribute to swallowing can worsen or develop because of pharmacotherapy or radiation therapy; metabolic or central nervous system damage due to cachexia, sarcopenia, or inflammation can also cause dysphagia. As the causes of eating disorders in cancer patients are complex and involve multiple factors, cancer patients require a multifaceted and long-term approach by the medical care team.

A Difficult Pill to Swallow: An Investigation of the Factors Associated with Medication Swallowing Difficulties

BACKGROUND

Many medications are available as solid oral dosage forms such as tablets and capsules; however, some people find these medications difficult to swallow.

AIM

To identify whether certain psychological, oral sensory, and oral motor characteristics contribute to medication swallowing difficulties.

METHODS

A sample of healthy adults from two academic institutions in Brisbane were assessed for their experiences with swallowing solid oral dosage forms, food preferences, and food neophobia. The gag reflex, oral cavity size, fungiform papillae count, and chewing efficacy were also evaluated followed by a capsule-swallowing task. Primary outcome was the incidence of medication swallowing difficulties. Secondary outcomes were the association of medication swallowing difficulties with psychological, oral sensory, and oral motor factors.

RESULTS

Of 152 subjects, 32% reported difficulty swallowing tablets or capsules whole. This group was significantly more likely to have had a memory of choking on medications compared to those without medication swallowing difficulties (OR = 7.25, p < 0.05). Current medication swallowing difficulties were significantly associated with a smaller mouth cavity size (OR = 2.98, p < 0.05), a higher density of taste receptors on the tongue (OR = 3.27, p < 0.05), and were higher among those who chewed a jelly candy to non-homogenous particle size (OR = 4.1, p < 0.05). Current medication swallowing difficulties were associated with lower confidence in swallowing large capsules (000 size: OR = 0.47, 00 size: OR = 0.39, p < 0.05). No associations were found between medication swallowing difficulties and the gag reflex or food neophobia.

CONCLUSION

A combination of heightened oral perception characterized by a small oral cavity and high taste sensitivity compounded by a past choking episode on medications may be precipitating factors for medication swallowing difficulties. These factors may be helpful in identifying individuals who are more likely to experience difficulty swallowing medications.

Mechanical tongue cleaning is a worthwhile procedure to improve the taste sensation

BACKGROUND

There are still only a few therapeutic strategies to improve taste sensation, which is part of oral health and quality of life.

OBJECTIVE

Therefore, here we aimed to investigate gustatory functions of healthy subjects performing mechanical tongue cleaning (MTC), an easy-to-perform oral hygiene procedure, to demonstrate taste changes and to describe possible negative side effects.

METHODS

Prior to and 14 days following MTC with an Orabrush^® , the following tests were conducted in 65 healthy participants including both non-smokers (n = 50, 76.9%) and smokers (n = 15, 23.1%): 'taste strips' test, the Winkel Tongue Coating Index (WTCI), and subjective self-assessment.

RESULTS

Among non-smokers, subjective self-assessments of gustatory function (P < .01), halitosis (P = .03) and tongue coating (P < .01) improved after 14 days of MTC; furthermore, they exhibited higher total taste (P < .01) and lower WTCI (P < .01) values. Their age and sex did not correlate with the differences between the pre- and post-MTC WTCI scores; however, differences between pre- and post-MTC total taste values were correlated with age. The total taste value improvements were greater in non-smokers aged 45-91 years than in those aged 20-44 years (P = .01). In smokers, total taste values (P < .01), as well as sweet (P = .03) and sour (P = .04) taste values, were significantly improved after 14 days of MTC.

CONCLUSION

Fourteen days of MTC using an Orabrush^® can improve gustatory functions in non-smokers and smokers. Therefore, MTC might be a useful, costless and easy option to improve taste and should be considered as a part of the daily oral care.

Potential Influence of Olfactory, Gustatory, and Pharyngolaryngeal Sensory Dysfunctions on Swallowing Physiology in COVID-19

Persistent smell and taste disorders have been reported as some of the most common symptoms after COVID-19 (coronavirus disease 2019). Sensory, olfactory, and gustatory functions perform an important role in the initiation and modulation of oropharyngeal swallow biomechanics and salivation as well as in mealtime enjoyment and appetite. Yet, the details of this interaction remain relatively unknown in patients who are infected with and recovering from COVID-19. In this commentary, we discuss the possible impacts of SARS-CoV-2 on the central and peripheral nervous system and consider the pathophysiology of olfactory, gustatory, and pharyngolaryngeal sensory deficits and its influence on deglutition, describing hypotheses and offering guidance for future research.

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.

Feasibility of high-resolution manometry for decision of feeding methods in patients with amyotrophic lateral sclerosis

As amyotrophic lateral sclerosis (ALS) progresses, dysphagia gets worse due to the weakening of pharyngeal musculature. As oral feeding becomes more difficult or dangerous due to worsening dysphagia, tracheal aspiration, or undernutrition, the necessity for tube feeding becomes increasingly important. This study aims to establish a standard pressure point by applying pharyngeal pressure using high-resolution manometry (HRM) to start tube feeding in patients with ALS.This study was designed as a retrospective analysis of prospectively collected data. Forty-one patients with ALS and 20 healthy subjects were participated. Both groups were evaluated using HRM, videofluoroscopic swallowing study (VFSS), and pulmonary function test. The swallowing pressure along the velopharynx (VP), tongue base (TB), pre-upper esophageal sphincter (UES), lower pharynx, and cricopharyngeus, as well as minimal UES pressure were measured using HRM.There was significantly positive correlation between the pressure of cricopharyngeus and forced expiratory volume in 1 second (FEV1). And there were significant correlations between results of VFSS and FEV1, FEV1%, forced vital capacity (FVC), and FVC%. There was a significant difference in the pressure of TB and cricopharyngeus between the control group and the ALS patient group. The pressures of VP, TB, lower pharynx, and cricopharyngeus have a significant correlation with the recommended feeding type by VFSS.Because it is possible to use HRM to quantitatively assess pharyngeal and respiratory weaknesses and it is more sensitive than other evaluation tools, the cutoff value of HRM parameters may be used to decide the feeding type in patients with ALS.

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.