Increased cortical-medulla functional connectivity is correlated with swallowing in dysphagia patients with subacute infratentorial stroke

Exploring the Effects of Action Observation Therapy on Swallowing Disorders in Stroke: A Functional Connectivity-Based fMRI Study

Objective: This study aims to investigate the impact of action observation therapy (AOT) on swallowing disorders following a stroke. Utilizing functional magnetic resonance imaging (fMRI) technology, the study will examine adjustments in brain activity and functional connectivity (FC), providing novel insights for the rehabilitation of swallowing function in stroke patients. Methods: In this study, 11 healthy controls (HCs) and 11 stroke patients were included. The stroke patients underwent a 4-week AOT. To assess the differences in brain region activity between the patients before and after treatment and the HCs, regional homogeneity (ReHo), and degree centrality (DC) were calculated based on fMRI data separately. Important brain regions were selected as regions of interest (ROIs) for subsequent FC analysis, and finally, comparisons were made to evaluate the therapeutic effects. Results: Comparing stroke patients before treatment with HCs, the ReHo values were relatively higher in the inferior temporal gyrus, median cingulate, and paracingulate gyri, and relatively lower in the calcarine fissure and surrounding cortex, middle occipital gyrus, and paracentral lobule. The DC values were relatively higher in the cerebellum, middle frontal gyrus, inferior temporal gyrus, inferior frontal gyrus, orbital part, middle frontal gyrus, and supramarginal gyrus, and relatively lower in the cuneus and paracentral lobule. The FC between the parahippocampal gyrus and the superior parietal gyrus was relatively high, and the FC between the superior occipital gyrus and the superior parietal gyrus was relatively low. Comparing stroke patients after treatment with HCs, the ReHo values were relatively higher in the caudate nucleus, and relatively lower in the cerebellum, superior frontal gyrus, medial orbital, calcarine fissure and surrounding cortex, and middle temporal gyrus. The DC values were relatively higher in the middle frontal gyrus and superior frontal gyrus, and relatively lower in the temporal pole: superior temporal gyrus, calcarine fissure, and surrounding cortex. The FC between the caudate nucleus and the superior parietal gyrus was relatively high, and the FC between the calcarine fissure and surrounding cortex, middle frontal gyrus, orbital part, and the superior parietal gyrus was relatively low. There was no significant difference in ReHo values between stroke patients before and after treatment. The DC value in the superior parietal gyrus increased, and the FC in the superior parietal gyrus and precuneus gyrus was also significantly enhanced before and after treatment. Conclusion: The results of this study indicate that the AOT has a positive effect on enhancing the functional connection and information transmission capabilities of specific brain regions. The impact of this therapy on brain function helps us understand the potential mechanisms of swallowing function network reorganization deeper. Trial Registration: Chinese Clinical Trial Registry: ChiCTR1900021849.

Post-stroke dysphagia: Neurological regulation and recovery strategies

Swallowing is a complex process requiring precise coordination of numerous muscles in the head and neck to smoothly guide ingested material from the mouth to the stomach. Animal and human studies have revealed a complex network of neurons in the brainstem, cortex, and cerebellum that coordinate normal swallowing. The interactions between these regions ensure smooth and efficient swallowing. However, the current understanding of the neurophysiological mechanisms involved in post-stroke dysphagia (PSD) is incomplete, and complete functional connectivity for swallowing recovery remains understudied and requires further exploration. In this review, we discussed the neuroanatomy of swallowing and the pathogenesis of PSD and summarized the factors affecting PSD recovery. We also described the plasticity of neural networks affecting PSD, including enhancing activation of neural pathways, cortical reorganization, regulation of extracellular matrix dynamics and its components, modulation of neurotransmitter delivery, and identification of potential therapeutic targets for functional recovery in PSD. Finally, we discussed the therapeutic strategies based on functional compensation and motor learning. This review aimed to provide a reference for clinicians and researchers to promote the optimization of PSD treatments and explore future research directions.

Disconnection-Based Prediction of Poststroke Dysphagia

BACKGROUND AND PURPOSE

Dysphagia is a common deficit after a stroke and is associated with serious complications. It is not yet fully clear which brain regions are directly related to swallowing. Previous lesion symptom mapping studies may have overlooked structural disconnections that could be responsible for poststroke dysphagia. Here, we aimed to predict and explain the relationship between poststroke dysphagia and the topologic distribution of structural disconnection via a multivariate predictive framework.

MATERIALS AND METHODS

We enrolled first-ever ischemic stroke patients classified as full per-oral nutrition (71 patients) and nonoral nutrition necessary (43 patients). After propensity score matching, 43 patients for each group were enrolled (full per-oral nutrition group with 17 women, 68 ± 15 years; nonoral nutrition necessary group with 13 women, 75 ± 11 years). The structural disconnectome was estimated by using the lesion segmented from acute phase diffusion-weighted images. The prediction of poststroke dysphagia by using the structural disconnectome and demographics was performed in a leave-one-out manner.

RESULTS

Using both direct and indirect disconnection matrices of the motor network, the disconnectome-based prediction model could predict poststroke dysphagia above the level of chance (accuracy = 68.6%, permutation P = .001). When combined with demographic data, the classification accuracy reached 72.1%. The edges connecting the right insula and left motor strip were the most informative in prediction.

CONCLUSIONS

Poststroke dysphagia could be predicted by using the structural disconnectome derived from acute phase diffusion-weighted images. Specifically, the direct and indirect disconnection within the motor network was the most informative in predicting poststroke dysphagia.

Research trends and hotspots of post-stroke dysphagia rehabilitation: a bibliometric study and visualization analysis

Background

Post-stroke dysphagia (PSD) is one of the most prevalent stroke sequelae, affecting stroke patients' prognosis, rehabilitation results, and quality of life while posing a significant cost burden. Although studies have been undertaken to characterize the pathophysiology, epidemiology, and risk factors of post-stroke dysphagia, there is still a paucity of research trends and hotspots on this subject. The purpose of this study was to create a visual knowledge map based on bibliometric analysis that identifies research hotspots and predicts future research trends.

Methods

We searched the Web of Science Core Collection for material on PSD rehabilitation research from its inception until July 27, 2023. We used CiteSpace, VOSviewer, and Bibliometrix R software packages to evaluate the annual number of publications, nations, institutions, journals, authors, references, and keywords to describe present research hotspots and prospective research orientations.

Results

This analysis comprised 1,097 articles from 3,706 institutions, 374 journals, and 239 countries or regions. The United States had the most publications (215 articles), and it is the most influential country on the subject. "Dysphagia" was the most published journal (100 articles) and the most referenced journal (4,606 citations). Highly cited references focused on the pathophysiology and neuroplasticity mechanisms of PSD, therapeutic modalities, rehabilitation tactics, and complications prevention. There was a strong correlation between the terms "validity" and "noninvasive," which were the strongest terms in PSD rehabilitation research. The most significant words in PSD rehabilitation research were "validity" and "noninvasive brain stimulation," which are considered two of the most relevant hotspots in the field.

Conclusion

We reviewed the research in the field of PSD rehabilitation using bibliometrics to identify research hotspots and cutting-edge trends in the field, primarily including the pathogenesis and neurological plasticity mechanisms of PSD, complications, swallowing screening and assessment methods, and swallowing rehabilitation modalities, and this paper can provide in the follow-up research in the field of PSD rehabilitation. The results of this study can provide insightful data for subsequent studies in the field of PSD rehabilitation.

Efficacy and safety of oropharyngeal muscle strength training on poststroke oropharyngeal dysphagia: a systematic review and meta-analysis

OBJECTIVES

To investigate how oropharyngeal muscle strength training affected the safety and performance of swallowing in patients with poststroke oropharyngeal dysphagia.

DESIGN

Systematic review and meta-analysis.

DATA SOURCES

Cochrane Central Register of Controlled of Trials, Web of Science, PubMed, Embase databases and ClinicalTrials.gov were systematically searched, for publications in English, from database inception to December 2022.

ELIGIBILITY CRITERIA

Studies comparing the effect of oropharyngeal muscle strength training with conventional dysphagia therapy in patients with poststroke. Penetration-Aspiration Scale (PAS) and Functional Oral Intake Scale (FOIS) were assessed as the main outcomes.

DATA EXTRACTION AND SYNTHESIS

Two researchers independently screened the literature, extracted data and evaluated the quality of the included studies, with disagreements resolved by another researcher. The Cochrane risk-of-bias tool was used to assess the risk of bias. Review Manager V.5.3 was employed for the meta-analysis. Random effect models were used for meta-analysis.

RESULTS

Seven studies with 259 participants were included in this meta-analysis. The results showed that oropharyngeal muscle strength training could reduce PAS score compared with conventional dysphagia therapy (mean difference=-0.98, 95% CI -1.34 to -0.62, p<0.0001, I2=28%). The results also showed that oropharyngeal muscle strength training could increase FOIS score (mean difference=1.04, 95% CI 0.55 to 1.54, p<0.0001, I2=0%) and the vertical displacement of the hyoid bone (mean difference=0.20, 95% CI 0.01 to 0.38, p=0.04, I2=0%) compared with conventional dysphagia therapy.

CONCLUSION

In patients with poststroke oropharyngeal dysphagia, oropharyngeal muscle strength training can improve swallowing safety and performance.

PROSPERO REGISTRATION NUMBER

CRD42022302471.

Neural basis of dysphagia in stroke: A systematic review and meta-analysis

Objectives

Dysphagia is a major cause of stroke infection and death, and identification of structural and functional brain area changes associated with post-stroke dysphagia (PSD) can help in early screening and clinical intervention. Studies on PSD have reported numerous structural lesions and functional abnormalities in brain regions, and a systematic review is lacking. We aimed to integrate several neuroimaging studies to summarize the empirical evidence of neurological changes leading to PSD.

Methods

We conducted a systematic review of studies that used structural neuroimaging and functional neuroimaging approaches to explore structural and functional brain regions associated with swallowing after stroke, with additional evidence using a live activation likelihood estimation (ALE) approach.

Results

A total of 35 studies were included, including 20 studies with structural neuroimaging analysis, 14 studies with functional neuroimaging analysis and one study reporting results for both. The overall results suggest that structural lesions and functional abnormalities in the sensorimotor cortex, insula, cerebellum, cingulate gyrus, thalamus, basal ganglia, and associated white matter connections in individuals with stroke may contribute to dysphagia, and the ALE analysis provides additional evidence for structural lesions in the right lentiform nucleus and right thalamus and functional abnormalities in the left thalamus.

Conclusion

Our findings suggest that PSD is associated with neurological changes in brain regions such as sensorimotor cortex, insula, cerebellum, cingulate gyrus, thalamus, basal ganglia, and associated white matter connections. Adequate understanding of the mechanisms of neural changes in the post-stroke swallowing network may assist in clinical diagnosis and provide ideas for the development of new interventions in clinical practice.