Differences in swallow physiology in patients with left and right hemispheric strokes

Correlation between lesion location and dysphagia characteristics in post-stroke patients

OBJECTIVE

To assess the correlation between lesion location and swallowing function characteristics in post-stroke dysphagia (PSD) patients.

MATERIALS AND METHODS

We enrolled 133 PSD. The patients were divided into supratentorial and infratentorial stroke groups. We compared the measurements in the videofluoroscopic swallowing study (VFSS) with 3ml and 5 ml of diluted and thickened barium liquid data between supratentorial and brainstem stroke groups. We further compared the difference of VFSS measurements between patients with left hemispheric or right hemispheric lesions (further divided into unilateral hemispheric cortical and subcortical subgroups) and brianstem leison stroke group.To explore the lesion location's effect on different bolus volume, the VFSS measurements of 3ml and 5ml in each subgroups were compared respectively. The measurements of VFSS included the oral transit time, soft palate elevation duration, hyoid bone movement duration (HMD), UES opening duration, pharyngeal transit duration (PTD), stage of ansition duration, and laryngeal closure duration (LCD), the upper esophageal sphincter opening (UESO), hyoid bone superior horizontal displacement, and hyoid bone anterior horizontal displacement. General swallowing function was assessed using the Penetration Aspiration Scale (PAS) and Functional Oral Intake Scale (FOIS). We performed the paired t-test, Spearman's correlation, and Kruskal-Wallis test analysis to characterize the parameters among the groups.

RESULTS

Fifty-eight patients were assessed in the final analysis. The HMD (p = 0.019), PTD (p = 0.048) and LCD (p = 0.013) were significantly different between the supratentorial and brainstem lesion groups in 5ml volume. The HMD was significantly different (p = 0.045) between the left cortical and brainstem lesion groups. Significant differences in the HMD (p = 0.037) and LCD (p = 0.032) between the left subcortical and brainstem lesion groups were found in 5ml volume bolus. There was no group different when taking the 3ml volume bolus. Regarding the relationship between food bolus volume and swallowing functions, only the UESO demonstrated a significant difference in the subcortical lesion of the right hemisphere (p = 0.0032) compared the 3 ml and 5 ml volume bolus. The PTD demonstrated a moderate correlation with the PAS scores (r = 0.38, p = 0.0044). The HMD (r = 0.32, p = 0.018) and LCD (r = 0.29, p = 0.039) demonstrated weak correlations with the PAS scores. We did not identify any correlation between the VFSS parameters and FOIS scores in each subgroup level.

CONCLUSION

The PSD with brainstem lesion shows more sever dysfunction in the pharyngeal phases. The left hemisphere was engaged in both the oral and pharyngeal phases. Lesions in the bilateral cortical, subcortical, and brainstem regions may impair sensory input.

Prevalence and Risk Factors of Poststroke Dysphagia: A Meta-Analysis

INTRODUCTION

In patients with stroke, poststroke dysphagia (PSD) is a common complication that plays an important role in morbidity and mortality. The aim of this paper was to assess the prevalence and risk factors of PSD using a systemic review and meta-analysis.

METHODS

PubMed, Embase, Cochrane Library, and Web of Science databases were systematically searched for potentially eligible studies published until September 2023. Further, the pooled incidence and risk factors for PSD were determined using a random-effects model. Overall, 58 studies involving 37,404 patients with acute stroke were selected for the meta-analysis.

RESULTS

The pooled incidence of PSD in patients with acute stroke was 42% (95% confidence interval [CI]: 36-48%), which is the highest in South America (47%) and lowest in Asia (37%). Notably, older age (odds ratio [OR]: 2.13; 95% CI: 1.53-2.97; p < 0.001), hypertension (OR: 1.23; 95% CI: 1.06-1.44; p = 0.007), diabetes mellitus (OR: 1.22; 95% CI: 1.04-1.44; p = 0.014), stroke history (OR: 1.26; 95% CI: 1.04-1.53; p = 0.019), and atrial fibrillation (OR: 1.58; 95% CI: 1.02-2.44; p = 0.039) were found to be associated with an increased risk of PSD. Conversely, sex differences, smoking, alcoholism, obesity, hyperlipidemia, ischemic heart disease, stroke type, and the hemisphere affected were not associated with the risk of PSD.

CONCLUSION

The abstract reports the prevalence of PSD in patients with acute stroke and identified potential risk factors for PSD, including older age, hypertension, diabetes mellitus, stroke history, and atrial fibrillation.

Health Factors Associated With Development and Severity of Poststroke Dysphagia: An Epidemiological Investigation

BACKGROUND

Dysphagia after stroke is common and can impact morbidity and death. The purpose of this population-based study was to determine specific epidemiological and health risk factors that impact development of dysphagia after acute stroke.

METHODS AND RESULTS

Ischemic and hemorrhagic stroke cases from 2010 and 2015 were identified via chart review from the GCNKSS (Greater Cincinnati Northern Kentucky Stroke Study), a representative sample of ≈1.3 million adults from southwestern Ohio and northern Kentucky. Dysphagia status was determined on the basis of clinical assessments and necessity for alternative access to nutrition via nasogastric or percutaneous endoscopic gastrostomy tube placement. Comparisons between patients with and without dysphagia were made to determine differences in baseline characteristics and premorbid conditions. Multivariable logistic regression determined factors associated with increased risk of dysphagia. Dysphagia status was ascertained from 4139 cases (1709 with dysphagia). Logistic regression showed that increased age, Black race, higher National Institutes of Health Stroke Scale score at admission, having a hemorrhagic stroke (versus infarct), and right hemispheric stroke increased the risk of developing dysphagia after stroke. Factors associated with reduced risk included history of high cholesterol, lower prestroke modified Rankin Scale score, and white matter disease.

CONCLUSIONS

This study replicated previous findings of variables associated with dysphagia (older age, worse stroke, right-sided hemorrhagic lesions), whereas other variables identified were without clear biological rationale (eg, Black race, history of high cholesterol, and presence of white matter disease) and should be investigated in future studies to determine biological relevance and potential influence in stroke recovery.

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.

Short-term and long-term effects of unilateral external carotid artery ligation on orofacial functions in rats

The external carotid artery (ECA) plays a major role in supplying blood to the head and neck. Although impeded blood flow in the ECA is expected to affect orofacial functions, few studies have shown how blood flow obstruction in the ECA contributes to impairment of these functions, including chewing and swallowing. This study was performed to investigate the effects of ECA ligation (ECAL) on immediate and long-term changes in masticatory and swallowing functions as well as the jaw-opening reflex evoked in the digastric muscle. The experiments were carried out using male Sprague-Dawley rats. In the acute experiment, the digastric reflex evoked by low-threshold electrical stimulation of the inferior alveolar nerve and the swallow reflex, identified by digastric and thyrohyoid electromyographic (EMG) bursts, were compared between before and 1 h after ECAL. The chronic experiment was conducted on freely moving rats. EMGs of the masseter, digastric, and thyrohyoid muscles were chronically recorded. The long-term effects of ECAL on behavior and muscle histology were compared between rats with an intact ECA and rats with ECAL. In the acute experiment, the peak amplitude of the digastric reflex on the ECAL side was significantly decreased 1 h after ECAL. In the chronic experiment, although most parameters of the masticatory and swallowing EMGs were not significantly different between the groups, the results suggest wide variation of the effect of ECAL on the muscles. Blood supply compensation from collaterals of the internal carotid artery may be permanent in some animals.NEW & NOTEWORTHY The inhibitory effect of unilateral external carotid artery ligation (ECAL) on the ipsilateral digastric reflex was small but evident. Most parameters of masticatory and swallowing muscle activity were not significantly different after ECAL. Wide variation was noted in the effect of ECAL on the ipsilateral muscle activity. Blood supply compensation from collaterals of the internal carotid artery may occur in response to the impaired blood flow.

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.

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.

Health factors associated with development and severity of post-stroke dysphagia: an epidemiological investigation

Background and Purpose

Dysphagia is a common post-stroke occurrence and has been shown to impact patients' morbidity and mortality. The purpose of this study was to use a large population-based dataset to determine specific epidemiological and patient health risk factors that impact development and severity of dysphagia after acute stroke.

Methods

Using data from the Greater Cincinnati Northern Kentucky Stroke Study, GCNKSS, involving a representative sample of approximately 1.3 million people from Southwest Ohio and Northern Kentucky of adults (age ≥18), ischemic and hemorrhagic stroke cases from 2010 and 2015 were identified via chart review. Dysphagia status was determined based on bedside and clinical assessments, and severity by necessity for alternative access to nutrition via nasogastric (NG) or percutaneous endoscopic gastrostomy (PEG) tube placement. Comparisons between patients with and without dysphagia were made to determine differences in baseline characteristics and pre-morbid conditions. Multivariable logistic regression was used to determine factors associated with increased risk of developing dysphagia.

Results

Dysphagia status was ascertained from 4139 cases (1709 with dysphagia). Logistic regression showed: increased age, Black race, higher NIHSS score at admission, having a hemorrhagic stroke (vs infarct), and right hemispheric stroke increased risk of developing dysphagia after stroke. Factors associated with reduced risk included history of high cholesterol, lower pre-stroke mRS score, and white matter disease.

Conclusions

This study replicated many previous findings of variables associated with dysphagia (older age, worse stroke, right sided hemorrhagic lesions), while other variables identified were without clear biological rationale (e.g. Black race, history of high cholesterol and presence of white matter disease). These factors should be investigated in future, prospective studies to determine biological relevance and potential influence in stroke recovery.

Post-stroke dysphagia: Clinical characteristics and evolution in a single-primary stroke center

BACKGROUND

Dysphagia is a common manifestation after stroke and seems to play a major role in clinical and functional outcomes.

OBJECTIVES

To identify clinical predictors of higher degrees of dysphagia, as well as assess its burden in our hospital, in order to understand how to improve the approach to this symptom.

METHODS

We included 311 patients admitted in an acute stroke unit in a year-long period. The relationship of dysphagia with different outcomes, both in acute phase and within the first year after stroke, were investigated.

RESULTS

Using the Pearson Correlation Coefficient, NIHSS score at admission was positively correlated with the degree of dysphagia (r = 0,783; p <  0,001) and total anterior circulation infarcts and age (>  70 years) were also associated with higher risk of dysphagia (p <  0.001). During hospitalization both respiratory infections and mortality occurred at significantly higher rates for dysphagic patients (p <  0.001) and we observed an increasing trend towards a higher mortality rate, the higher the degree of dysphagia. These patients stayed longer in the stroke unit, with less chance to be discharged home and more frequently transferred to inpatient rehabilitation care. One year after admission, dysphagic patients were more frequently readmitted due to pneumonia and we observed a higher mortality rate compared to patients without dysphagia (p <  0.001).

CONCLUSION

The presence of the above-mentioned dysphagia predictive factors should alert us to the need for an early approach, starting in the stroke unit, but also after discharge, taking into account its impact on clinical outcomes, mortality and healthcare costs.

Physiological Mechanisms and Associated Pathophysiology of Dysphagia in Older Adults

Dysphagia can be a common secondary sequela of neurological and neurodegenerative disorders in older adults. Early screening, identification, and management of dysphagia is essential to avoid serious complications, including malnutrition, dehydration, aspiration pneumonia; and promote quality of life. Although individuals of all ages may experience swallowing difficulties, dysphagia and its complications are more common in older adults. This literature review aims to provide an overview of the physiological mechanisms of normal swallowing in healthy individuals and age-related changes to swallowing function, the pathophysiology of dysphagia associated with three common neurological disorders affecting older adults (stroke, Parkinson's disease, and dementia), and implications for interdisciplinary clinical practice. Increased awareness of these issues may contribute to a more timely and efficient identification of older adults with dysphagia and to improve overall dysphagia management.

Abnormal Esophageal Clearance Identified During Modified Barium Swallow Study in an Acute Poststroke Cohort

PURPOSE

Dysphagia impacts many poststroke survivors with wide-ranging prevalence in the acute and chronic phases. One relatively unexplored manifestation of poststroke swallowing impairment is that of primary or co-occurring esophageal dysphagia. The incidence of esophageal dysphagia in this population is unknown despite the shared neuroanatomy and physiology with the oropharynx. We aimed to determine the presence of abnormal esophageal clearance in an acute poststroke sample using the Modified Barium Swallow Impairment Profile (MBSImP) Component 17 (esophageal clearance) as our outcome measure.

METHOD

We performed a retrospective, cross-sectional, cohort study of 57 poststroke patients with acute, first-ever, ischemic strokes. All participants received a modified barium swallow study (MBSS) using the MBSImP protocol and scoring metrics. Swallowing impairment was determined using a combination of MBSImP scores and Penetration-Aspiration Scale scores. Swallowing outcome measures were collected including Functional Oral Intake Scale and International Dysphagia Diet Standardization Initiative (IDDSI) scores. We performed tests of association and logistic regression analysis to determine if statistically significant associations exist between judgments of esophageal clearance and other swallowing impairments and/or swallowing outcome measures.

RESULTS

In our study of poststroke patients who received an MBSS as part of their care, 57.9% had abnormal esophageal clearance. Statistically significant associations were also identified in measures of pharyngeal physiology (MBSImP scores) and swallowing outcome measures (IDDSI scores and alternate means of nutrition).

CONCLUSIONS

Abnormal esophageal clearance was identified in greater than half of our poststroke patients. There is a dearth of scientific research regarding esophageal function poststroke. While esophageal visualization during the MBSS is not diagnostic of esophageal impairment, it may serve as an indicator for those poststroke patients who require dedicated esophageal testing to best determine the full nature of their swallowing pathophysiology and make the most effective treatment recommendations.

Cerebral control of swallowing: An update on neurobehavioral evidence

This review aims to update the current knowledge on the cerebral control of swallowing. We review data from both animal and human studies spanning across the fields of neuroanatomy, neurophysiology and neuroimaging to evaluate advancements in our understanding in the brain's role in swallowing. Studies have collectively shown that swallowing is mediated by multiple distinct cortical and subcortical regions and that lesions to these regions can result in dysphagia. These regions are functionally connected in separate groups within and between the two hemispheres. While hemispheric dominance for swallowing has been reported in most human studies, the laterality is inconsistent across individuals. Moreover, there is a shift in activation location and laterality between swallowing preparation and execution, although such activation changes are less well-defined than that for limb motor control. Finally, we discussed recent neurostimulation treatments that may be beneficial for dysphagia after brain injury through promoting the reorganization of the swallowing neural network.

Modulating swallowing-related functional connectivity and behavior via modified pharyngeal electrical stimulation: A functional near-infrared spectroscopy evidence

Introduction

Modified pharyngeal electrical stimulation (mPES) is a novel therapeutic modality for patients with neurogenic dysphagia. However, the underlying neural mechanism remains poorly understood. This study aimed to use functional near-infrared spectroscopy (fNIRS) to explore the influence of mPES on swallowing-related frequency-specific neural networks and ethology.

Methods

Twenty-two healthy right-handed volunteers participated in the study. Each participant was randomly assigned to either the sham or the mPES group and provided a 10-min intervention program every day for 5 days. Oxyhemoglobin and deoxyhemoglobin concentration changes verified by fNIRS were recorded on days 1, 3, and 5. Five characteristic frequency signals (0.0095-2 Hz) were identified using the wavelet transform method. To calculate frequency-specific functional connectivity, wavelet phase coherence (WPCO) was adopted. Furthermore, behavioral performance was assessed pre- and post-mPES using a 150 ml-water swallowing stress test.

Results

Compared with sham stimulation on day 1, the significantly decreased WPCO values were mainly associated with the dorsolateral prefrontal lobe, Broca's area, and middle temporal lobe. Compared with the sham mPES on day 1, the mPES showed a noticeable effect on the total swallow duration. Compared with the baseline, the WPCO values on days 3 and 5 showed a stepwise decrease in connectivity with the application of mPES. Furthermore, the decreased WPCO was associated with a shortened time per swallow after mPES.

Conclusions

The mPES could modulate swallowing-related frequency-specific neural networks and evoke swallowing cortical processing more efficiently. This was associated with improved performance in a water swallowing stress test in healthy participants.

Swallowing function after acute ischemic stroke: Development and validation of a novel clinical prognostic model

Background

Predicting the duration of dysphagia after acute ischemic stroke (AIS) is important for clinical treatment decisions.

Objective

The purpose of this study is to assess the swallowing function of AIS patients and to develop and validate a prognostic model for the need for nasogastric tube (NGT) in these patients.

Materials and methods

We included 554 AIS patients during 2018–2019 as the development group and had 186 AIS patients as the external validation group. The primary end point of the study was the retention of NGT in patients 1 week after admission (Functional Oral Intake Scale ≤ 4). Swallowing function and stroke-associated pneumonia (SAP) at 1 month post-onset were also the objectives of this study. The volume-viscosity swallow test (V-VST) was used to assess the patient’s impaired swallowing function. The Predictive model was built by logistic regression.

Results

Overall, a total of 104 patients required indwelling NGT at 1 week of AIS onset in development group. The final prognostic model includes 5 variables: age (OR: 1.085, 95%CI: 1.049–1.123), neutrophil-to-lymphocyte ratio (NLR) (OR: 1.332, 95%CI: 1.090–1.626), NIHSS (OR: 1.092, 95%CI: 1.025–1.164), history of drinking (OR: 2.532, 95%CI: 1.452–4.417) and stroke location (Subtentorial vs. Supratentorial, OR: 1.954, 95%CI: 1.088–3.509). The prediction model had an AUC of 0.810, while the external validation group was 0.794.

Conclusion

In stroke patients, it is very important to decide early whether to indwell a NGT. The nomogram will support decision making for NGT insertion and help these patients recover from their condition.

Predictors of complete oral feeding resumption after feeding tube placement in patients with stroke and dysphagia: A systematic review

AIMS

The aim was to synthesise and discuss predictors of complete oral feeding resumption after feeding tube placement in stroke patients with dysphagia.

DESIGN

This was a systematic review, following the PRISMA 2020 checklist.

DATA SOURCES

Eight databases (PubMed, Web of Science, Embase, Cochrane, CINAHL, CNKI, WanFang and Vip) were searched for eligible studies from inception up to June 2021.

REVIEW METHODS

The JBI Manual for Evidence Synthesis was used to guide this systematic review. Any cross-sectional survey, longitudinal study, cohort study or case-control study that explored the recovery from tube feeding to complete oral feeding in patients with dysphagia after stroke was included. Qualitative studies, review articles, case reports and conference abstracts were excluded. Two reviewers independently screened and appraised the studies. The Newcastle-Ottawa scale was used for quality assessment. Content analysis was used to categorise factors predicting feeding tube removal in stroke patients with dysphagia.

RESULTS

This review included a total of 15 studies consisting of 1746 participants, of which 2 were case-control studies and 13 were cohort studies. Four studies were rated as having low risk of bias, and the other 11 had high risk of bias. The factors examined in the studies were categorised into demographic characteristics (age and sex), swallowing function (instrumental assessments and non-instrumental assessments), stroke characteristics (stroke severity, past stroke history and location of the stroke), functional status (cognitive function and physical function) and clinical measures (body mass index, geriatric nutritional risk index, white blood cell count and C-reactive protein level).

CONCLUSIONS

The major limitation of this review is the failure to identify predictors of different tube feeding types. Although the current evidence is insufficient to support or oppose the predictive effect of any single factor, these factors are still valuable data for clinical staff that provide information that researchers can use in developing prognostic models. Rigorously designed and high-quality research is needed to further explore the predictive value of these factors.

REGISTRATION

This review was registered prospectively with PROSPERO [CRD42021272552].

RELEVANCE TO CLINICAL PRACTICE

Healthcare providers should strengthen the monitoring of swallowing function in patients with stroke to promote complete oral feeding resumption. As the predictive value of the identified factors is still uncertain, large, well-designed, studies are needed to better clarify the importance of these predictors.

NO PATIENT OR PUBLIC CONTRIBUTION

No patient or public was involved in the design, analysis, preparation or writing of this review.

Prevalence of dysphagia and risk of pneumonia and mortality in acute stroke patients: a meta-analysis

Background

Post-stroke dysphagia (PSD) has been associated with high risk of aspiration pneumonia and mortality. However, limited evidence on pooled prevalence of post-stroke dysphagia and influence of individual, disease and methodological factors reveals knowledge gap. Therefore, to extend previous evidence from systematic reviews, we performed the first meta-analysis to examine the pooled prevalence, risk of pneumonia and mortality and influence of prognostic factors for PSD in acute stroke.

Methods

Our search was conducted in CINAHL, Cochrane Library, EMBASE, Ovid-Medline, PubMed, and Web of Science an initial search in October 2020 and a follow-up search in May 2021. Data synthesis was conducted using the Freeman-Tukey double-arcsine transformation model for the pooled prevalence rate and the DerSimonian-Lard random-effects model for prognostic factors and outcomes of PSD.

Results

The pooled prevalence of PSD was 42% in 42 studies with 26,366 participants. PSD was associated with higher pooled odds ratio (OR) for risk of pneumonia 4.08 (95% CI, 2.13–7.79) and mortality 4.07 (95% CI, 2.17–7.63). Haemorrhagic stroke 1.52 (95% CI, 1.13–2.07), previous stroke 1.40 (95% CI, 1.18–1.67), severe stroke 1.38 (95% CI, 1.17–1.61), females 1.25 (95% CI, 1.09–1.43), and diabetes mellitus 1.24 (95% CI, 1.02–1.51) were associated with higher risk of PSD. Males 0.82 (95% CI, 0.70–0.95) and ischaemic stroke 0.54 (95% CI, 0.46–0.65) were associated with lower risk of PSD. Haemorrhagic stroke, use of instrumental assessment method, and high quality studies demonstrated to have higher prevalence of PSD in the moderator analysis.

Conclusions

Assessment of PSD in acute stroke with standardized valid and reliable instruments should take into account stroke type, previous stroke, severe stroke, diabetes mellitus and gender to aid in prevention and management of pneumonia and thereby, reduce the mortality rate.

Trial registration

https://osf.io/58bjk/?view_only=26c7c8df8b55418d9a414f6d6df68bdb.

Supplementary information

The online version contains supplementary material available at 10.1186/s12877-022-02960-5.

Structural Validity, Internal Consistency, and Rater Reliability of the Modified Barium Swallow Impairment Profile: Breaking Ground on a 52,726-Patient, Clinical Data Set

PURPOSE

The purpose of this study was to extend the assessment of the psychometric properties of the Modified Barium Swallow Impairment Profile (MBSImP). Here, we re-examined structural validity and internal consistency using a large clinical-registry data set and formally examined rater reliability in a smaller data set.

METHOD

This study consists of a retrospective structural validity and internal consistency analysis of MBSImP using a large data set (N = 52,726) drawn from the MBSImP Swallowing Data Registry and a prospective study of the interrater and intrarater reliability of a subset of studies (N = 50) rated by four MBSImP-trained speech-language pathologists. Structural validity was assessed via exploratory factor analysis. Internal consistency was measured using Cronbach's alpha for each of the multicomponent MBSImP domains, namely, the oral and pharyngeal domains. Interrater reliability and intrarater reliability were measured using the intraclass correlation coefficient (ICC).

RESULTS

The exploratory factor analysis showed a two-factor solution with factors precisely corresponding to the scale's oral and pharyngeal domains, consistent with findings from the initial study. Component 17, that is, the esophageal domain, did not load onto either factor. Internal consistency was good for both the oral and pharyngeal domains (α_oral = .81, α_pharyngeal = .87). Interrater reliability was found to be good with ICC_interrater = .78 (95% confidence interval [CI; .76, .80]). Intrarater reliability was good for each rater, ICC_Rater-1 = .82 (95% CI [.77, .86]), ICC_Rater-2 = .83 (95% CI [.79, .87]), ICC_Rater-3 = .87 (95% CI [.83, .90]), and ICC_Rater-4 = .87 (95% CI [.83, .90]).

CONCLUSIONS

This study leverages a large-scale, clinical data set to provide strong, generalizable evidence that the MBSImP assessment method has excellent structural validity and internal consistency. In addition, the results show that MBSImP-trained speech-language pathologists can demonstrate good interrater and intrarater reliability.

The Effectiveness of Repetitive Transcranial Magnetic Stimulation for Post-stroke Dysphagia: A Systematic Review and Meta-Analysis

Background

Repetitive transcranial magnetic stimulation (rTMS) applied to the mylohyoid cortical region has positive clinical effects on post-stroke. Therefore, we conducted a meta-analysis to investigate the efficacy of rTMS for patients with post-stroke dysphagia.

Methods

According to PRISMA guidelines, we searched the databases of MEDLINE (PubMed), Cochrane Library, Embase, Web of Science, CNKI, Wangfang. We searched for studies of randomized controlled trials (RCTs) of rTMS to treat dysphagia after stroke and screened by inclusion and exclusion criteria. Features of RCTs were extracted. The heterogeneity of the trials was measured by I 2 statistic.

Results

In total, 11 RCTs with 463 dysphagia patients fulfilled our inclusion criteria. In our analysis, rTMS demonstrated a great beneficial effect for post-stroke dysphagia when combined with traditional swallowing exercises. Moreover, a greatly significant difference (P = 0.008) was noted based on stimulation frequency (high frequency vs. low frequency). Additionally, no significant difference (P = 0.53) was observed based on stimulation site (affected vs. unaffected hemisphere).

Conclusions

Overall, rTMS can effectively accelerate the improvement of swallowing function in patients with post-stroke swallowing disorders.

The Role of White Matter in the Neural Control of Swallowing: A Systematic Review

Background: Swallowing disorders (dysphagia) can negatively impact quality of life and health. For clinicians and researchers seeking to improve outcomes for patients with dysphagia, understanding the neural control of swallowing is critical. The role of gray matter in swallowing control has been extensively documented, but knowledge is limited regarding the contributions of white matter. Our aim was to identify, evaluate, and summarize the populations, methods, and results of published articles describing the role of white matter in neural control of swallowing.

Methods: We completed a systematic review with a multi-engine search following PRISMA-P 2015 standards. Two authors screened articles and completed blind full-text review and quality assessments using an adapted U.S. National Institute of Health's Quality Assessment. The senior author resolved any disagreements. Qualitative synthesis of evidence was completed.

Results: The search yielded 105 non-duplicate articles, twenty-two of which met inclusion criteria. Twenty were rated as Good (5/22; 23%) or Fair (15/22; 68%) quality. Stroke was the most represented diagnosis (n = 20; 91%). All studies were observational, and half were retrospective cohort design. The majority of studies (13/22; 59%) quantified white matter damage with lesion-based methods, whereas 7/22 (32%) described intrinsic characteristics of white matter using methods like fractional anisotropy. Fifteen studies (68%) used instrumental methods for swallowing evaluations. White matter areas commonly implicated in swallowing control included the pyramidal tract, internal capsule, corona radiata, superior longitudinal fasciculus, external capsule, and corpus callosum. Additional noteworthy themes included: severity of white matter damage is related to dysphagia severity; bilateral white matter lesions appear particularly disruptive to swallowing; and white matter adaptation can facilitate dysphagia recovery. Gaps in the literature included limited sample size and populations, lack of in-depth evaluations, and issues with research design.

Conclusion: Although traditionally understudied, there is sufficient evidence to conclude that white matter is critical in the neural control of swallowing. The reviewed studies indicated that white matter damage can be directly tied to swallowing deficits, and several white matter structures were implicated across studies. Further well-designed interdisciplinary research is needed to understand white matter's role in neural control of normal swallowing and in dysphagia recovery and rehabilitation.

Cortical and Subcortical Control of Swallowing-Can We Use Information From Lesion Locations to Improve Diagnosis and Treatment for Patients With Stroke?

Purpose Swallowing is a complex process, mediated by a broad bilateral neural network that spans from the brainstem to subcortical and cortical brain structures. Although the cortex's role in swallowing was historically neglected, we now understand, especially through clinical observations and research of patients with stroke, that it substantially contributes to swallowing control. Neuroimaging techniques (e.g., magnetic resonance imaging) have helped significantly to elucidate the role of cortical and subcortical brain areas, in general, and the importance of specific areas in swallowing control in healthy individuals and patients with stroke. We will review recent discoveries in cortical and subcortical neuroimaging research studies and their generalizability across patients to discuss their potential implications and translation to dysphagia diagnosis and treatment in clinical practice. Conclusions Stroke lesion locations have been identified that are commonly associated across patients with the occurrence and recovery of dysphagia, suggesting that clinical brain scans provide useful information for improving the diagnosis and treatment of patients with stroke. However, individual differences in brain structure and function limit the generalizability of these relationships and emphasize that the extent of the motor and sensory pathology in swallowing, and how the patient recovers, also depends on a patient's individual brain constitution. The involvement of the damaged brain tissue in swallowing control before the stroke and the health of the residual, undamaged brain tissue are crucial factors that can differ between individuals.

Reduced tongue force and functional swallowing changes in a rat model of post stroke dysphagia

PURPOSE

Dysphagia is a common problem after stroke that is often associated with tongue weakness. However, the physiological mechanisms of post-stroke tongue muscle weakness and optimal treatments have not been established. To advance understanding of physiological mechanisms of post stroke dysphagia, we sought to validate the unilateral transient middle cerebral artery occlusion (MCAO) rat model of ischemic stroke as a translational model of post stroke dysphagia. Our goal was to establish clinically relevant measures and chronicity of functional deficits; criteria that increase the likelihood that findings will translate to the clinic. We hypothesized that MCAO would cause tongue weakness and functional swallowing changes.

METHODS

Maximum voluntary tongue forces and videofluoroscopic swallowing studies were collected in 8-week old male Sprague-Dawley rats prior to receiving either a left MCAO (N = 10) or sham (N = 10) surgery. Tongue forces and VFSS were reassessed at 1 and 8 weeks post-surgery.

RESULTS

Maximum voluntary tongue force, bolus area, and bolus speed were significantly reduced in the MCAO group at the 1 and 8-week timepoints.

CONCLUSION

Clinically relevant changes to swallowing and tongue force support the use of the MCAO rat model as a translational model of post stroke dysphagia. This model will allow for future studies to improve our understanding of the physiology contributing to these functional changes as well as the impact of therapeutic interventions on physiological targets and function.

Factors Influencing Oral Intake Improvement and Feeding Tube Dependency in Patients with Poststroke Dysphagia

OBJECTIVE

To assess ischemic stroke patients regarding the relationship between lesion locations, swallowing impairment, medical and demographic factors and (1) oral intake improvement and (2) feeding tube dependency at discharge from their acute hospital stay.

METHODS

We conducted an exploratory, retrospective observational longitudinal cohort study of acute, first-ever, ischemic stroke patients. Patients who had an initial nonoral feeding recommendation from a speech and language pathologist and who underwent a modified barium swallow study within their hospital stay were included. Oral intake status was measured with the Functional Oral Intake Scale (FOIS) as the change in FOIS during the hospital stay and as feeding tube dependency at hospital discharge. Associations were assessed with multiple linear regression modeling controlling for age, comorbidities, and hospital length of stay.

RESULTS

We included 44 stroke patients. At hospital discharge, 93% of patients had oral intake restrictions and 30% were feeding tube dependent. Following multiple linear regression modeling, age, damage to the left superior frontal gyrus, dorsal anterior cingulate gyrus, hypothalamus, and nucleus accumbens were significant predictors for FOIS change. Feeding tube dependency showed no significant associations with any prognostic variables when controlling for confounders.

CONCLUSIONS

The vast majority of patients with an initial nonoral feeding recommendation are discharged with oral intake restrictions indicating a continued need for swallowing assessments and treatment after discharge. Lesion locations associated with motivation, reward, and drive to consume food as well as swallowing impairment, higher age, and more comorbidities were related to less oral intake improvement.

Mapping acute lesion locations to physiological swallow impairments after stroke

Dysphagia is a common deficit after a stroke, and it is frequently associated with pneumonia, malnutrition, dehydration, and poor quality of life. It is not yet fully clear which brain regions are directly related to swallowing, and how lesions affect swallow physiology. This study aimed to assess the statistical relationship between acute stroke lesion locations and impairment of specific aspects of swallow physiology. We performed lesion symptom mapping with 68 retrospectively recruited, acute, first-ever ischemic stroke patients. Lesions were determined on diffusion weighted MRI scans. Post-stroke swallow physiology was determined using the Modified Barium Swallow Study Impairment Profile (MBSImP©™). The relationship between brain lesion location and 17 physiological aspects of swallowing were tested using voxel-based and region-based statistical associations corrected for multiple comparisons using permutation thresholding. We found that laryngeal elevation, anterior hyoid excursion, laryngeal vestibular closure, and pharyngeal residue were associated with lesioned voxels or regions of interests. All components showed distinct and overlapping lesion locations, mostly in the right hemisphere, and including cortical regions (inferior frontal gyrus, pre- and postcentral gyrus, supramarginal gyrus, angular gyrus, superior temporal gyrus, insula), subcortical regions (thalamus, amygdala) and white matter tracts (superior longitudinal fasciculus, corona radiata, internal capsule, external capsule, ansa lenticularis, lenticular fasciculus). Our findings indicate that different aspects of post-stroke swallow physiology are associated with distinct lesion locations, primarily in the right hemisphere, and primarily including sensory-motor integration areas and their corresponding white matter tracts. Future studies are needed to expand on our findings and thus, support the development of a neuroanatomical model of post-stroke swallow physiology and treatment approaches targeting the neurophysiological underpinnings of swallowing post stroke.

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Different aspects of swallow physiology are associated with distinct stroke lesion locations.

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Sensory-motor integration areas and white matter tracts are crucial for swallow physiology.

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Mostly regions in the right and only few in the left hemisphere contribute to swallow physiology.