Spontaneous Swallowing Frequency in Post-Stroke Patients with and Without Oropharyngeal Dysphagia: An Observational Study

Device-based solutions supporting patients with swallowing problems

INTRODUCTION

Swallowing is a highly complex activity requiring the coordination of numerous muscles within the head and neck through connections from multiple areas within the central nervous system. Dysphagia is common and has long been known to lead to significant adverse effects on morbidity, mortality, and quality of life. Classical approaches toward dysphagia management involve input by clinical deglutologists who teach rehabilitative exercises and recommend alteration of the consistency of food and fluids. However, the evidence base in support of some of these approaches is inconsistent and requires further and larger studies to support their widespread implementation.

AREAS COVERED

This paper shall explore some of these novel techniques and explore the evidence that they will alter the future of dysphagia care.

EXPERT OPINION

Medical devices form one aspect of these rehabilitation strategies, and over the past decade, numerous novel techniques targeting the complex swallowing sensorimotor pathway or swallowing associated musculature have come to prominence. These include interventions such as noninvasive brain stimulation, swallowing related biofeedback, and peripheral stimulation approaches, developed to bolster existing management methods. The evidence suggests that many of these approaches have the capability to enhance swallowing function and impact dysphagia recovery, however, more evidence is needed.

Establishment and validation of early prediction model for post-stroke dysphagia

BACKGROUND

Stroke is a leading cause of death and disability worldwide, with dysphagia being a common complication that worsens patient outcomes.

METHODS

Data from 200 stroke patients (development cohort) and 50 stroke patients (validation cohort) were analyzed to develop a nomogram for predicting post-stroke dysphagia (PSD). Risk factors were identified through univariate analysis, Least Absolute Shrinkage and Selection Operator (LASSO) regression, and multivariate logistic regression.

RESULTS

Univariate analysis revealed substantial differences in age, body mass index (BMI), diabetes, atrial fibrillation, National Institute of Health Stroke Scale (NIHSS) score, Activities of Daily Living (ADL) score, lesion site, stroke type, and several laboratory indicators across the groups. Further analysis of individual NIHSS items showed significant differences in consciousness level, best gaze, facial palsy, motor arm, motor leg, dysarthria, etc. LASSO regression identified three predictors: ADL score, motor leg, and dysarthria. Multivariable logistic regression revealed that ADL score [0.96 (0.94-0.97)], motor leg [5.70 (2.14-15.22)], and dysarthria [5.26 (2.00-13.82)] were independent risk factors for PSD. The prediction model's AUC was 0.915 (0.874-0.955), with a sensitivity of 0.920 (0.867-0.973), specificity of 0.800 (0.722-0.878), positive predictive value (PPV) of 0.821 (0.750-0.892), negative predictive value (NPV) of 0.909 (0.849-0.969), and F1 score of 0.859. External validation yielded an AUC of 0.995 (0.984-1.000).

CONCLUSIONS AND IMPLICATIONS

ADL score, motor leg, and dysarthria are independent predictors of PSD. The prediction model based on these factors shows high accuracy, sensitivity, balance, consistency, and clinical applicability. This nomogram can support decision-making for ultra-early rehabilitation care, ultimately improving patient prognosis.

Development and Validation of a GULP-Based Predictive Model for Dehydration in Elderly Patients with Post-Stroke Dysphagia

Aims/Background The background for establishing and verifying a dehydration prediction model for elderly patients with post-stroke dysphagia (PSD) based on General Utility for Latent Process (GULP) is as follows: For elderly patients with PSD, GULP technology is utilized to build a dehydration prediction model. This aims to improve the accuracy of dehydration risk assessment and provide clinical intervention, thereby offering a scientific basis and enhancing patient prognosis. This research highlights the innovative application of GULP technology in constructing complex medical prediction models and addresses the special health needs of elderly stroke patients. Based on GULP criteria, the study aims to establish and validate a dehydration prediction model for elderly patients with dysphagia following a stroke. Methods Two hundred patients with post-stroke dysphagia treated at Beijing Rehabilitation Hospital Affiliated with Capital Medical University, from January 2020 to December 2023, were selected retrospectively. The patients were randomly matched at a ratio of 1:4 to establish a verification group (n = 40) and a modelling group (n = 160). Based on the occurrence of dehydration, the modelling group patients were divided into two groups: the dehydration group (n = 55) and the non-dehydration group (n = 105). Univariate and multivariate logistic regression analyses were used to identify the influencing factors of dehydration in elderly patients with dysphagia after a stroke, and to establish a predictive model based on GULP. The predictive value of the model was evaluated using receiver operating characteristic (ROC) curve analysis. Results The results of univariate and multivariate logistic regression analyses showed significant differences in age, lesion location, muscle strength grade, homocysteine (Hcy), and swallowing function score (p < 0.05). When these influencing factors were included in the model, the slope of the calibration curve in both the training set and the validation set was close to 1, indicating that the predicted dehydration risk was consistent with the actual risk. ROC analysis results revealed that in the training set, the model predicted dehydration in elderly post-stroke patients with dysphagia with an area under the curve (AUC) of 0.934, a standard error of 0.034, and a 95% confidence interval (CI) of 0.916 to 0.981. The optimal cutoff value was 0.78, yielding a sensitivity of 88.84% and a specificity of 90.00%. In the validation set, the AUC was 0.867 with a standard error of 0.025 and a 95% CI of 0.694 to 0.934. The optimal cutoff value here was 0.66, with a sensitivity of 80.16% and a specificity of 85.94%. Conclusion This study successfully established and validated a GULP-based dehydration prediction model for elderly patients with dysphagia following a stroke, demonstrating high application value.

The Respiratory-Swallow Coordination may be Related to Aspiration in Infratentorial Stroke Patients

To investigate the characteristics of respiratory-swallow coordination (RSC) in poststroke dysphagia (PSD) patients following infratentorial stroke (IS) and further explore their association with aspiration. PSD patients after IS and age-matched healthy controls were recruited. Nasal airflow and sound signals were recorded using a nasal cannula-type flow sensor and contact microphone, which were synchronized with videofluoroscopic swallowing studies (VFSS). For healthy controls, only nasal airflow and sound signals recordings were conducted. A 5 ml thickened liquid was utilized during these assessments. The penetration-aspiration scale (PAS) score was determined through VFSS. Various parameters, including swallowing apnoea duration (SAD), swallowing duration (SD), swallowing latency duration (SLD), number of swallows (NS), and RSC patterns, were analysed to assess RSC. A total of 37 patients with PSD following IS-comprising 25 non-aspirators and 12 aspirators-and 31 age-matched healthy controls were included. The PSD patient group exhibited a shorter SAD (p = 0.016), a longer SD (p = 0.000), and fewer NS (p = 0.000) compared to the healthy control group. Among the PSD patients, those who aspirated exhibited a notably shorter SAD (p = 0.018) and longer SD (p = 0.028) compared to non-aspirators. The prevalence of the swallow-inspiration pattern was higher in PSD patients (p = 0.006), particularly among those who aspirated (p = 0.010). Logistic regression analysis and the area under the receiver operating characteristic curve (AUC) indicated that both SAD (AUC = 0.825, p = 0.002) and SD (AUC = 0.757, p = 0.020) were significant predictors of aspiration. The optimal cut-off values for SAD and SD were determined to be 0.19s and 1.93s, respectively. The RSC characteristics in patients with PSD following IS differed from those observed in healthy controls, particularly among patients who experienced aspiration. In these patients, a shorter SAD and longer SD may contribute to an increased risk of aspiration.

Acoustic Analysis of Swallowing of an Experimental Meal of Three Food Textures: A Comparative Aging Study

Swallowing disorders in the elderly represent a public health problem, their detections are a medico-economic issue. The acoustic analysis of swallowing has the advantages of being non-invasive with no radiation, compared to videofluoroscopy or fiberoptic swallowing assessments. Acoustic analysis of swallowing has been tested in many studies but only on small food boluses. The aim of this study was to compare the acoustic swallowing parameters of two groups of healthy subjects, before and after 70 years old, during the intake of a series of 3 food textures. A laryngophone was used to record the pharyngeal phase of swallowing. The experimental meal was composed of 100 ml of mashed potatoes, 100 ml of water, and 100 ml of yogurt. Group 1 (50-70 years old) comprised 21 subjects and group 2 (over 70 years old) 23 subjects. Acoustic parameters analyzed were the number of swallows, average duration of swallowing, average duration of inter-swallowing, meal duration, and the average frequency of swallowing per minute. These parameters for groups 1 and 2 were compared. The average duration of inter-swallowing and the meal duration were significantly higher in the older group (p < 0.001), with a mean duration of inter-swallowing that was 2.4 s longer than the younger group. The average swallowing frequency per minute was higher in the younger group (11.3 vs 7.9; p < 0.001). This study demonstrated that acoustic analysis of an experimental meal of three food textures generated usable data on swallowing. In the over 70 age group, there was a decrease in swallowing frequency, indicating a slowdown in food intake. A reduced swallowing frequency could become a criteria to assess presbyphagia.

The effect of real versus sham intermittent theta burst transcranial magnetic stimulation combined with conventional treatment on poststroke dysphagia: a randomized controlled trial

Repetitive transcranial magnetic stimulation to the pharyngeal motor cortex has shown beneficial effects on poststroke dysphagia. Previous studies, however, using intermittent theta burst stimulation (iTBS) for dysphagia have targeted the suprahyoid motor cortex. This study aimed to investigate the effects of iTBS to the pharyngeal motor cortex in patients with poststroke dysphagia, using ultrasound and videofluoroscopic swallowing studies (VFSS). A randomized controlled trial was conducted on patients with dysphagia due to a first-time unilateral stroke. Patients who had signs and symptoms of dysphagia and showed aspiration or penetration on VFSS were included. Twenty-eight patients were randomly assigned to either real or sham iTBS groups, and each patient underwent five sessions of iTBS to the ipsilesional pharyngeal motor cortex. Each iTBS session was followed by conventional dysphagia treatment for 30 min. The hyoid-larynx approximation measured by ultrasound, penetration-aspiration scale (PAS) and functional dysphagia scale (FDS) assessed by VFSS were evaluated before and after completion of iTBS. There were no significant differences between the two groups in terms of demographic and clinical characteristics, including age and type of stroke. The hyoid-larynx approximation ratio increased in the real iTBS group and decreased in the sham iTBS group (median values of pre-post differences were 0.27 vs. -0.01, P  < 0.001). The PAS and FDS showed greater improvements in the real iTBS group than in the sham iTBS group (median values of pre-post differences of the PAS were -2.50 vs. 0.00, P  = 0.004; median values of pre-post differences of the FDS were -12.50 vs. -2.50, P  < 0.001). No adverse effects were reported during or after iTBS sessions. Five-session iTBS to the pharyngeal motor cortex combined with conventional treatment led to a significant improvement in poststroke dysphagia in terms of hyoid-larynx approximation which is related to the suprahyoid muscle. Considering the short duration of one iTBS session, this can be an efficient and effective treatment tool for patients with this condition.

Combined systematic screening for malnutrition and dysphagia in hospitalized older adults: a scoping review

BACKGROUND

Dysphagia affects about 40% of patients admitted to acute geriatric wards, as it is closely associated with diseases that rise in prevalence with advancing age, such as stroke, Parkinson's disease, and dementia. Malnutrition is a highly associated predictive factor of dysphagia as well as one of the most common symptoms caused by dysphagia. Thus, the two conditions may exist simultaneously but also influence each other negatively and quickly cause functional decline especially in older adults. The purpose of this review was to determine whether institutions have established a protocol combining screenings for dysphagia and malnutrition on a global scale. If combined screening protocols have been implemented, the respective derived measures will be reported.

METHODS

A scoping review was conducted. A systematic database search was carried out in January and February 2024. Studies were included that examined adult hospitalized patients who were systematically screened for dysphagia and malnutrition. The results were managed through the review software tool Covidence. The screening of titles and abstracts was handled independently by two reviewers; conflicts were discussed and resolved by consensus between three authors. This procedure was retained for full-text analysis and extraction. The extraction template was piloted and revised following feedback prior to extraction, which was carried out in February 2024.

RESULTS

A total of 2014 studies were found, 1075 of which were included for abstract screening, 80 for full text screening. In the end, 27 studies were extracted and reported following the reporting guideline PRISMA with the extension for Scoping Reviews.

CONCLUSION

Most of the studies considered the prevalence and association of dysphagia and malnutrition with varying outcomes such as nutritional status, pneumonia, oral nutrition, and swallowing function. Only two studies had implemented multi-professional nutrition teams.

Extensive comparison of salivary collection, transportation, preparation, and storage methods: a systematic review

BACKGROUND

Human saliva as a bodily fluid-similar to blood-is utilized for diagnostic purposes. Unlike blood sampling, collecting saliva is non-invasive, inexpensive, and readily accessible. There are no previously published systematic reviews regarding different collection, transportation, preparation, and storage methods for human saliva.

DESIGN

This study has been prepared and organized according to the preferred reporting items for systematic reviews and meta-analyses (PRISMA) 2020 guidelines. This systematic review has been registered at PROSPERO (Registration ID: CRD42023415384). The study question according to the PICO format was as followed: Comparison of the performance (C) of different saliva sampling, handling, transportation, and storage techniques and methods (I) assessed for analyzing stimulated or unstimulated human saliva (P and O). An electronic search was executed in Scopus, Google Scholar, and PubMed.

RESULTS

Twenty-three descriptive human clinical studies published between 1995 and 2022 were included. Eight categories of salivary features and biomarkers were investigated (i.e., salivary flow rate, total saliva quantity, total protein, cortisol, testosterone, DNA quality and quantity, pH and buffering pH). Twenty-two saliva sampling methods/devices were utilized. Passive drooling, Salivette®, and spitting were the most utilized methods. Sampling times with optimum capabilities for cortisol, iodine, and oral cancer metabolites are suggested to be 7:30 AM to 9:00 AM, 10:30 AM to 11:00 AM, and 14:00 PM to 20:00 PM, respectively. There were 6 storage methods. Centrifuging samples and storing them at -70 °C to -80 °C was the most utilized storage method. For DNA quantity and quality, analyzing samples immediately after collection without centrifuging or storage, outperformed centrifuging samples and storing them at -70 °C to -80 °C. Non-coated Salivette® was the most successful method/device for analyzing salivary flow rate.

CONCLUSION

It is highly suggested that scientists take aid from the reported categorized outcomes, and design their study questions based on the current voids for each method/device.

Exploratory analysis of swallowing behaviour in community-dwelling older adults using a wearable device: Differences by age and ingestant under different task loads

Objective

To develop a new method of evaluating swallowing behaviour.

Methods

Sixty-nine healthy participants were divided into a younger (16 males and 16 females, mean age 39.09 ± 12.16 years) and older (18 males and 19 females, mean age 71.43 ± 5.50 years) group. The participants ingested water and yoghurt twice (directed and free swallowing) at rest and after performing simple daily life tasks (calculation and exercise). To measure swallowing frequency, we employed a smartphone-based, portable and neck-worn swallowing-sound-monitoring device. This device monitors swallowing behaviour continuously by collecting biological sounds from the neck without imposing behavioural restrictions. A neural network model of swallowing sound identification by deep learning was used for the subsequent evaluation. This device was used to obtain two types of saliva-swallowing sounds associated with different ingestants, at rest and after performing a stimulating task. Furthermore, we assessed the associated subjective psychological states.

Results

The younger group showed a higher directed swallowing frequency (for both water and yoghurt) than the older group did. Regarding the type of ingestant, the swallowing frequency for yoghurt was higher during free swallowing in both the young and the older groups. 'Feeling calm' was reported significantly more often in the older group after swallowing yoghurt following exercise.

Conclusions

Swallowing status in daily life was measured non-invasively using a wearable mobile device. It is important to consider the type of ingestant, daily living activities, and age when assessing swallowing.

Brain and Pharyngeal Responses Associated with Pharmacological Treatments for Oropharyngeal Dysphagia in Older Patients

Impaired pharyngo-laryngeal sensory function is a critical mechanism for oropharyngeal dysphagia (OD). Discovery of the TRP family in sensory nerves opens a window for new active treatments for OD. To summarize our experience of the action mechanism and therapeutic effects of pharyngeal sensory stimulation by TRPV1, TRPA1 and TRPM8 agonists in older patients with OD. Summary of our studies on location and expression of TRP in the human oropharynx and larynx, and clinical trials with acute and after 2 weeks of treatment with TRP agonists in older patients with OD. (1) TRP receptors are widely expressed in the human oropharynx and larynx: TRPV1 was localized in epithelial cells and TRPV1, TRPA1 and TRPM8 in sensory fibers mainly below the basal lamina. (2) Older people present a decline in pharyngeal sensory function, more severe in patients with OD associated with delayed swallow response, impaired airway protection and reduced spontaneous swallowing frequency. (3) Acute stimulation with TRP agonists improved the biomechanics and neurophysiology of swallowing in older patients with OD TRPV1 = TRPA1 > TRPM8. (4) After 2 weeks of treatment, TRPV1 agonists induced cortical changes that correlated with improvements in swallowing biomechanics. TRP agonists are well tolerated and do not induce any major adverse events. TRP receptors are widely expressed in the human oropharynx and larynx with specific patterns. Acute oropharyngeal sensory stimulation with TRP agonists improved neurophysiology, biomechanics of swallow response, and safety of swallowing. Subacute stimulation promotes brain plasticity further improving swallow function in older people with OD.

Origins of thirstiness sensation and current food solutions

The sensation of thirstiness is the desire to drink water. In certain situations, the ingestion of liquid water can be restricted. As a result, thirstiness is not relieved, resulting in an uncomfortable and distressing situation. The present review describes thirstiness and hydration, the food products and beverages that cause thirstiness, and the beverages and food products currently available to quench thirstiness in individuals with restricted access to liquid ingestion. It also discusses how to measure the effectiveness of calming thirstiness. To diminish thirstiness distress, different alternatives to liquids are proposed. Individuals with swallowing disorders are given thickened water, individuals with restricted water ingestion are given ice cubes or ice popsicles of different flavors, and sportspeople are given energy gels. However, current beverage solutions seem not to relieve thirst fully, although some stimuli like iced water, flavors (especially lemon and mint), or acids seem to work better than plain stimuli and could be added to existing products. Therefore, there is still a need to incorporate these strategies into beverage and food formulations and to test their effectiveness.

The assessment of dysphagia after stroke: state of the art and future directions

Dysphagia is a major complication following an acute stroke that affects the majority of patients. Clinically, dysphagia after stroke is associated with increased risk of aspiration pneumonia, malnutrition, mortality, and other adverse functional outcomes. Pathophysiologically, dysphagia after stroke is caused by disruption of an extensive cortical and subcortical swallowing network. The screening of patients for dysphagia after stroke should be provided as soon as possible, starting with simple water-swallowing tests at the bedside or more elaborate multi-consistency protocols. Subsequently, a more detailed examination, ideally with instrumental diagnostics such as flexible endoscopic evaluation of swallowing or video fluoroscopy is indicated in some patients. Emerging diagnostic procedures, technical innovations in assessment tools, and digitalisation will improve diagnostic accuracy in the future. Advances in the diagnosis of dysphagia after stroke will enable management based on individual patterns of dysfunction and predisposing risk factors for complications. Progess in dysphagia rehabilitation are essential to reduce mortality and improve patients' quality of life after a stroke.