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

Videofluoroscopic Swallowing Studies: A Proposed Checklist

PURPOSE

The videofluoroscopic swallowing study (VFSS) is used widely in dysphagia research. However, variations exist in the conduct and interpretation of VFSS, including differences in contrast agents, food and fluid consistencies tested, patient positioning, intervention strategies trialed, fluoroscopy settings, resolution, and image storage solutions. It cannot be assumed that VFSS exams yield directly comparable results across different studies. It is essential that relevant elements of VFSS be clearly reported in research. The goal of this article is to outline optimal VFSS reporting as part of the Framework for RigOr aNd Transparency In REseaRch on Swallowing (FRONTIERS), a critical appraisal tool intended to promote rigor and transparency in dysphagia research.

METHOD

We developed a set of 27 questions regarding the rigor and transparency of VFSS reporting, based on review of previous research articles. These were reviewed by all members of the FRONTIERS Framework collaborative, to determine which questions were mandatory, unnecessary, or needed revision, prior to inclusion in the final critical appraisal tool.

RESULTS

The final FRONTIERS Framework tool contains 20 questions and seven subquestions regarding VFSS. These are grouped into four themes: patient/participant positioning, equipment and recording settings, contrast agents, and rating methods, including operational definitions and reliability.

CONCLUSIONS

The VFSS section of the FRONTIERS Framework tool is intended to facilitate and promote rigorous and transparent reporting of all elements that may influence the interpretation of VFSS in research. This critical appraisal tool can also be used to guide research design and the evaluation of study outcomes contributing to best practices in the field of dysphagia research.

Sustained Effects of Capsaicin Infusion into the Oropharynx on Swallowing in Perfused Rats

OBJECTIVES

To examine the sustained effects of oropharyngeal capsaicin stimulation on the regulation of swallowing, we recorded the swallowing-related nerve activities during continuous infusion of capsaicin solution into the oropharynx.

METHODS

In 33 in situ perfused brainstem preparation of rats, we recorded the activities of the vagus, hypoglossal, and phrenic nerves during fictive swallowing. The interburst intervals (IBIs) of the swallowing-related nerves during sequential pharyngeal swallowing (sPSW) elicited by electrical stimulation of the superior laryngeal nerve (SLN) during concurrent capsaicin stimulation of 10, 1, and 0.1 μM (n = 28) were compared with those during oropharyngeal infusion of saline (control) (n = 5).

RESULTS

The IBIs during SLN-induced sPSW were reduced at 5 min after initiation of continuous infusion of 10 and 1 μM capsaicin solution. The IBIs showed significant decreases to -25.8 ± 6.9%, -25.9 ± 5.3, -18.3 ± 3.7, and -12.0 ± 1.6 at 30 min following 1 μM capsaicin stimulation at SLN stimulus conditions at 5 Hz of 1.2 times threshold, 10 Hz of 40 μA, 5 Hz of 60 μA, and 10 Hz of 60 μA, respectively. Continuous capsaicin stimulation of 0.1 μM solution did not show significant sustained effects.

CONCLUSION

Pharmacological stimulation of capsaicin could provide time-dependent effects on the likelihood of swallowing, particularly subserving sustained facilitation of swallowing reflex with appropriate concentration of capsaicin.

LEVEL OF EVIDENCE

NA Laryngoscope, 134:305-314, 2024.

Research hotspots and trends in post-stroke dysphagia: a bibliometric analysis

Background

Dysphagia represents one of the common complications following a stroke, and post-stroke dysphagia (PSD) can lead to aspiration, pneumonia, and malnutrition, thus prolonging hospital stay, escalating medical expenditures, and imposing a substantial economic strain on both patients and society. The utilization of bibliometric analysis offers a quantitative approach for investigating the existing literature and recognizes the current status of the research. However, bibliometric analysis on the subject of PSD remains absent. Consequently, we carried out this study to provide researchers with insights, facilitating their further exploration of PSD.

Methods

Conducting a bibliometric analysis of articles pertaining to PSD retrieved over the past two decades enables us to acquire the research hotspots and trends in this area. The publications concerning PSD were searched from the Core Collection of Web of Science, spanning the period ranging from 2003 to 2023. Articles or reviews published in English were included in this study. Subsequently, we employed CiteSpace and VOSviewer software to visualize the retrieved articles, thereby identifying the cooperative relationships of authors, institutions, and countries, as well as relevant information about journals and references.

Results

This study comprised 866 papers in total, and the number of articles published each year shows an overall growth trend. As for the analysis of the authors, Dziewas R. was the most prolific author with 21 articles. The most frequently published institutions, countries, and journals were the University of Manchester, China, and Dysphagia, with 28, 254, and 75 publications, respectively. And the co-cited authors and journals with the highest counts were Martino R and Stroke. According to the analysis of keywords and references, dysphagia screening and assessment, prevention of pneumonia, rehabilitation approaches, and nutritional management of PSD are considered research hotpots. Additionally, future research may focus on the topics of systematic review and meta-analysis, noninvasive brain stimulation, and lesion location.

Conclusion

Through the bibliometrics analysis of PSD, we can capture the research hotspots and frontiers of PSD, thereby providing inspiration and reference for subsequent studies in this field.

Statistical Power and Swallowing Rehabilitation Research: Current Landscape and Next Steps

Despite rapid growth in the number of treatments to rehabilitate dysphagia, studies often demonstrate mixed results with non-significant changes to functional outcomes. Given that power analyses are infrequently reported in dysphagia research, it remains unclear whether studies are adequately powered to detect a range of treatment effects. Therefore, this review sought to examine the current landscape of statistical power in swallowing rehabilitation research. Databases were searched for swallowing treatments using instrumental evaluations of swallowing and the penetration-aspiration scale as an outcome. Sensitivity power analyses based on each study's statistical test and sample size were performed to determine the minimum effect size detectable with 80% power. Eighty-nine studies with 94 treatment comparisons were included. Sixty-seven percent of treatment comparisons were unable to detect effects smaller than d = 0.80. The smallest detectable effect size was d = 0.29 for electrical stimulation, d = 0.49 for postural maneuvers, d = 0.52 for non-invasive brain stimulation, d = 0.61 for combined treatments, d = 0.63 for respiratory-based interventions, d = 0.70 for lingual strengthening, and d = 0.79 for oral sensory stimulation. Dysphagia treatments examining changes in penetration-aspiration scale scores were generally powered to reliably detect larger effect sizes and not smaller (but potentially clinically meaningful) effects. These findings suggest that non-significant results may be related to low statistical power, highlighting the need for collaborative, well-powered intervention studies that can detect smaller, clinically meaningful changes in swallowing function. To facilitate implementation, a tutorial on simulation-based power analyses for ordinal outcomes is provided ( https://osf.io/e6usd/ ).