Neural correlates of cricopharyngeal dysfunction after supratentorial stroke: A voxel-based lesion-symptom mapping with propensity score matched case-control

The Cortical and Subcortical Neural Control of Swallowing: A Narrative Review

Swallowing is a sophisticated process involving the precise and timely coordination of the central and peripheral nervous systems, along with the musculatures of the oral cavity, pharynx, and airway. The role of the infratentorial neural structure, including the swallowing central pattern generator and cranial nerve nuclei, has been described in greater detail compared with both the cortical and subcortical neural structures. Nonetheless, accumulated data from analysis of swallowing performance in patients with different neurological diseases and conditions, along with results from neurophysiological studies of normal swallowing have gradually enhanced understanding of the role of cortical and subcortical neural structures in swallowing, potentially leading to the development of treatment modalities for patients suffering from dysphagia. This review article summarizes findings about the role of both cortical and subcortical neural structures in swallowing based on results from neurophysiological studies and studies of various neurological diseases. In sum, cortical regions are mainly in charge of initiation and coordination of swallowing after receiving afferent information, while subcortical structures including basal ganglia and thalamus are responsible for movement control and regulation during swallowing through the cortico-basal ganglia-thalamo-cortical loop. This article also presents how cortical and subcortical neural structures interact with each other to generate the swallowing response. In addition, we provided the updated evidence about the clinical applications and efficacy of neuromodulation techniques, including both non-invasive brain stimulation and deep brain stimulation on 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.

Theta-burst transcranial magnetic stimulation for dysphagia patients during recovery stage of stroke: a randomized controlled trial

BACKGROUND

The Theta-burst Transcranial Magnetic Stimulation (TBS) is an emerging modality of Repetitive Transcranial Magnetic Stimulation (rTMS). However, the efficacy of TBS on post-stroke recovery-stage patients with dysphagia remains unclear.

AIM

To investigate the effect of intermittent theta burst stimulation (iTBS) and continuous theta burst stimulation (cTBS) in post-stroke dysphagia patients within the recovery stage.

DESIGN

Randomized controlled double blinded trial.

SETTING

Inpatient.

POPULATION

Ninety patients with dysphagia after stroke within 1 to 6 months.

METHODS

Patients were divided into the supratentorial group and the brainstem group, and both of groups were further divided into three subgroups, including the sham subgroups, the iTBS subgroups, and the cTBS subgroups. Each of subgroups received 30 min of traditional swallowing rehabilitation treatment every day for 4 weeks. In addition, the iTBS subgroups received iTBS over the cortex of the suprahyoid muscles on the affected hemisphere, the cTBS subgroups received cTBS on the unaffected hemisphere, and the sham subgroups received sham stimulation on unilateral hemisphere. Standardized swallowing assessment (SSA), Oral Motor Function Scale (OMFS) and fiberoptic endoscopic examination of swallowing (FEES) were assessed before and after treatments.

RESULTS

In the supratentorial group, compared with the sham and cTBS subgroups, the iTBS subgroups showed significant improvement in SSA, OMFS, vocal folds movement, laryngeal sensation, and Rosenbek Penetration-Aspiration Scale (PAS) (P<0.05). In the brainstem group, compared with the sham subgroup, the iTBS subgroup significantly improved SSA, OMFS, Yale Pharyngeal Residue Severity Rating Scale (YPR-SRS) and PAS (P<0.05), and the cTBS subgroup significantly improved SSA, YPR-SRS and PAS (P<0.05).

CONCLUSIONS

This study demonstrated that iTBS might be an effective stimulation pattern to improve the overall swallowing function whether in supratentorial stroke patients or brainstem stroke patients.

CLINICAL REHABILITATION IMPACT

iTBS seems to be a promising approach for rehabilitation of overall swallowing function in post-stroke patients.

Striatal Dopaminergic Loss and Dysphagia in Parkinson Disease

PURPOSE

To better understand the development of dysphagia in patients with Parkinson disease (PD) and to identify possible neuromodulatory target regions of dysphagia, we studied the striatal dopamine transporter (DAT) availability distribution by subtype of dysphagia.

METHODS

In this retrospective cross-sectional study, patients with PD who underwent videofluoroscopic swallowing study and N-(3-[18F]fluoropropyl)-2β-carbon ethoxy-3β-(4-iodophenyl) nortropane (18F-FP-CIT) PET at intervals of less than 1 month were analyzed. The 14 binarized subitem scores of the Videofluoroscopic Dysphagia Scale were analyzed using a voxel-wise Firth's penalized binary logistic regression model, adjusting for age and disease duration at videofluoroscopic swallowing study.

RESULTS

Sixty-five patients with PD were finally included. Striatal mapping showed association of decreased DAT availability with 5 subitems with 1 or more clusters surviving the statistical threshold: 1 oral phase and 4 pharyngeal phase subitems. The overlap maps created by superimposing clusters for all 5 statistically significant subitems revealed associations of dysphagia in PD with decreased DAT availability in the bilateral ventral striatum. Of these, 4 subitems belonging to the pharyngeal phase-specific dysphagia were additionally found to be related to dopaminergic degeneration of the bilateral anterior-to-posterior caudate and ventral striatum.

CONCLUSIONS

These findings suggest that subitem/phase-specific striatal subregional dopaminergic depletion may explain the dysphagia of PD. This dopaminergic degeneration of striatal subregions specific to the phases of dysphagia may serve as a potential target for neuromodulatory brain stimulation through stimulation of cortices functionally connected.

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.

Assessment and treatment of neurogenic dysphagia in stroke and Parkinson's disease

PURPOSE OF REVIEW

Neurogenic dysphagia worsens quality of life and prognosis of patients with different neurological disorders. Management of neurogenic dysphagia can be challenging. This review provides a comprehensive overview of current evidence on screening, diagnosis, and treatment of neurogenic dysphagia in stroke and Parkinson's disease, suggesting clues for clinical practice.

RECENT FINDINGS

The pros and cons of diagnostic techniques are discussed in the light of updated evidence. Findings from recent meta-analyses of different treatment approaches, including traditional dysphagia therapy, peripheral and central neurostimulation techniques, and treatment with botulinum toxin, are critically discussed, emphasizing inconsistencies and controversial issues.

SUMMARY

Screening tests and clinical swallow examination should be routinely performed in neurological patients at risk for dysphagia. In patients testing positive for dysphagia, first-line instrumental investigations, represented by fiberoptic endoscopic evaluation of swallowing or videofluoroscopic swallow study, should be performed to confirm the presence of dysphagia, to assess its severity, and to inform the treatment. Second-line and third-line instrumental methods can be used in selected patients to clarify specific pathophysiological aspects of oropharyngeal dysphagia. Treatment strategies should be personalized, and combination of traditional dysphagia therapy with innovative treatment approaches may increase the chance of restoring effective and safe swallowing.

Effect of Cold Fluid Compensatory Swallowing Combined with Balloon Dilation on the Treatment of Poststroke Cricopharyngeal Achalasia: A Pilot Randomized Controlled Trial

Objective

This study is aimed at comparing the treatment efficacy between catheter balloon dilation combined with cold fluid compensatory swallowing training and catheter balloon dilation alone on poststroke cricopharyngeal achalasia (CPA).

Methods

We conducted a single-blind, randomized controlled trial (RCT). Poststroke patients with CPA were divided into two groups: the control group (treated with catheter balloon dilation) and the trial group (catheter balloon dilation combined with cold fluid compensatory swallowing). Videofluoroscopic swallowing study (VFSS) was performed, and functional oral intake scale (FOIS) was used to evaluate and compare the swallowing function of patients in the 2 groups before and after intervention. Posttreatment VAS pain scores and recovery time were also measured.

Results

VFSS and FOIS scores in the two groups were improved after treatment (P < 0.05). In the trial group, VFSS scores in the pharyngeal phase and aspiration degree were significantly higher compared with the control group (P < 0.05) but not in the oral phase (P > 0.05). The difference in FOIS scores and patients' recovery time from intervention to eating mushy food between the trial and control groups was significant (P < 0.05), but not the VAS scores (P > 0.05).

Conclusion

The catheter balloon dilation combined with cold fluid compensatory swallowing was superior to catheter balloon dilation alone in terms of relieving dysphagia and reducing aspiration in patients with CPA following stroke. Long-term efficacy should be followed up with more objective and quantitative indicators in future studies.