Effect of Low-Frequency rTMS and NMES on Subacute Unilateral Hemispheric Stroke With Dysphagia

Repetitive Transcranial Magnetic Stimulation on Individualized Spots Based on Task functional Magnetic Resonance Imaging Improves Swallowing Function in Poststroke Dysphagia

Background: Functional magnetic resonance imaging (fMRI) has not previously been used to localize the swallowing functional area in repetitive transcranial magnetic stimulation (rTMS) treatment for poststroke dysphagia; Traditionally, the target area for rTMS is the hotspot, which is defined as the specific region of the brain identified as the optimal location for transcranial magnetic stimulation (TMS). This study aims to compare the network differences between the TMS hotspot and the saliva swallowing fMRI activation to determine the better rTMS treatment site and investigate changes in functional connectivity related to poststroke dysphagia using resting-state fMRI. Methods: Using an information-based approach, we conducted a single case study to explore neural functional connectivity in a patient with poststroke dysphagia before, immediately after rTMS, and 4 weeks after rTMS intervention. A total of 20 healthy participants underwent fMRI and TMS hotspot localization as a control group. Neural network alterations were assessed, and functional connections related to poststroke dysphagia were examined using resting-state fMRI. Results: Compared to the TMS-induced hotspots, the fMRI activation peaks were located significantly more posteriorly and exhibited stronger functional connectivity with bilateral postcentral gyri. Following rTMS treatment, this patient developed functional connection between the brainstem and the bilateral insula, caudate, anterior cingulate cortex, and cerebellum. Conclusion: The saliva swallowing fMRI activation peaks show more intense functional connectivity with bilateral postcentral gyri compared to the TMS hotspots. Activation peak-guided rTMS treatment improves swallowing function in poststroke dysphagia. This study proposes a novel and potentially more efficacious therapeutic target for rTMS, expanding its therapeutic options for treating poststroke dysphagia.

New and Evolving Treatments for Neurologic Dysphagia

Despite swallowing being a frequently performed daily function, it is highly complex. For a safe swallow to occur, muscles within the head, neck, and thorax need to contract in a concerted pattern, controlled by several swallowing centers at multiple levels of the central nervous system, including the midbrain, cerebral cortex, and cerebellum in addition to five cranial nerves. Dysphagia, or difficulty swallowing, is caused by a long list of pathologic processes and diseases, which can interfere with various stages along the swallowing sensorimotor pathway. When present, dysphagia leads to increased mortality, morbidity, hospital length of stay, and reduced quality of life. Current dysphagia management approaches, such as altering the texture and consistency of foods and fluids and teaching patients rehabilitative exercises, have been broadly unchanged for many years and, in the case of texture modification, are of uncertain effectiveness. However, evidence is emerging in support of new medication-based and neuromodulatory treatment approaches. Regarding medication-based therapies, most research has focused on capsaicinoids, which studies have shown are able to improve swallowing in patients with post-stroke dysphagia. Separately, albeit convergently, in the field of neuromodulation, there is a growing and positive evidential base behind three non-invasive brain stimulation techniques: repetitive transcranial magnetic stimulation (rTMS), transcranial direct current stimulation (TDCS), and pharyngeal electrical stimulation (PES). Should some or all of these emerging therapies fulfill their promise, dysphagia-related patient outcomes may be improved. This paper describes the current state of our understanding regarding new medication and neuromodulation-based neurogenic oropharyngeal dysphagia treatments.

Effects of different mylohyoid muscle stimulations on swallowing cortex excitability in healthy subjects

BACKGROUND

Dysphagia has been recognized by the World Health Organization as a medical disability. Improving mylohyoid muscle function plays an important role in pharyngeal dysphagia. The aim of this study was to evaluate the treatment of transcranial magnetic stimulation (TMS), peripheral magnetic stimulation (PMS), and electrical stimulation (ES) for dysphagia.

METHODS

Forty healthy subjects were randomly divided into four groups: TMS+PMS, TMS, PMS, and ES. TMS stimulated the cortical representative area of the mylohyoid muscle and the PMS was directly stimulating the mylohyoid muscle, both of them at a frequency of 10 Hz for a total of 1,800 pulses. The intensity of ES was based on the subject's tolerance level, usually 2-5 mA. Functional near infrared spectroscopy (fNIRS) and motor evoked potential (MEP) of the mylohyoid muscle were used to evaluate the immediate effects of stimulation on swallowing cortex excitability of healthy subjects before and after intervention.

RESULTS

The fNIRS results revealed notable activation across multiple channels in the four groups of healthy subjects both pre- and post- the intervention. Among these channels, the activation levels were most pronounced in the TMS+PMS group, followed by the TMS, PMS, and ES groups, respectively. Regarding the MEP results, post-intervention observations indicated a reduction in bilateral latency and an increase in bilateral amplitude in the TMS+PMS group. Additionally, the left amplitude exhibited an increase in the TMS group.

CONCLUSIONS

In fNIRS, all four stimulation methods significantly activated the swallowing cortex of healthy subjects, and the activation of TMS+PMS was the most obvious, followed by TMS, PMS, and ES.

Neuromuscular Electrical Stimulation for Post-Stroke Dysphagia Treatment: A Systemic Evaluation and Meta-Analysis of Randomized Controlled Trials

Neuromuscular electrical stimulation (NMES) is a novel treatment method that stimulates patients' swallowing functions. This systemic review was designed to evaluate the impact of NMES on dysphagia in stroke patients. Databases including PubMed, Embase, Web of Science, and Cochrane Library were searched from the date of establishment to January 28th, 2022. Two investigators identified all included studies and compared the swallowing function after NMES treatment with traditional therapy (TT). The Cochrane risk bias assessment tool was utilized to analyze the quality of included studies. Research outcomes included Swallowing Quality of Life (SWAL-QoL), Penetration-Aspiration Scale (PAS), Functional Oral Intake Scale (FOIS), Dysphagia Outcomes and Severity Scale (DOSS), the Repeat Salivary Swallowing Test (RSST), and Water Swallowing Test (WST). We extracted the mean and standard deviation of specific outcomes at the baseline level and after the treatment in both NMES and TT groups for subsequent meta-analysis. 9 randomized controlled trials (RCTs) and quasi-RCTs were included, and remarkable differences were found between patients treated with or without NMES in respect of FOIS scores (SMD = 0.48; 95% CI 0.26-0.70, P < 0.0001), PAS scores (SMD = - 0.56; 95% CI 1.01-0.10, P = 0.02), and SWAL-QoL scores (SMD = 0.57; 95% CI 0.00-1.14, P = 0.05). No significant difference was manifested in WST, RSST, and DOSS (SMD: - 0.02; 95% CI  0.38-0.35, P = 0.93). Evidence suggests that NMES is more effective for post-stroke dysphagia patients than treatment without NMES.

Effects of effortful swallowing against kinesiology taping resistance on the swallowing function in patients with poststroke dysphagia: A randomized controlled trial

BACKGROUND

A dysphagia rehabilitation method using kinesiology taping (KT) was recently introduced, and its potential for clinical efficacy was demonstrated by evaluating muscle activity and thickness. However, its effect on the swallowing function in patients with dysphagia remains unclear. This study aimed to investigate the effects of effortful swallowing against KT resistance on the swallowing function in patients with post stroke dysphagia.

METHODS

Thirty patients with poststroke dysphagia were recruited and randomly assigned to the experimental and placebo groups. In the experimental group, the KT was attached to the front of the neck (the hyoid bone between the sternum) with a tension of approximately 70% to 80%, and effortful swallowing was performed against the KT tension. In contrast, the placebo group performed effortful swallowing with KT applied at the same location without tension. The intervention was performed 30 times/day, 5 days/week for 6 weeks. The videofluoroscopic dysphagia scale (VDS) and penetration-aspiration scale (PAS) based on a videofluoroscopic swallowing study were used to analyze oropharyngeal swallowing function.

RESULTS

The experimental group showed statistically significant improvements in the oral and pharyngeal phases of the VDS (P = .029 and .007, respectively) and PAS (P = .034) compared with the placebo group. Effect sizes were observed for the oral (0.3) and pharyngeal phases (0.5) of the VDS and PAS (1.1).

CONCLUSION

This study demonstrated that effortful swallowing against resistance to KT is an effective therapeutic exercise for improving the swallowing function in patients with poststroke dysphagia.

The neurorehabilitation of post-stroke dysphagia: Physiology and pathophysiology

Swallowing is a complex process involving the precise contractions of numerous muscles of the head and neck, which act to process and shepherd ingested material from the oral cavity to its eventual destination, the stomach. Over the past five decades, information from animal and human studies has laid bare the complex network of neurones in the brainstem, cortex and cerebellum that are responsible for orchestrating each normal swallow. Amidst this complexity, problems can and often do occur that result in dysphagia, defined as impaired or disordered swallowing. Dysphagia is common, arising from multiple varied disease processes that can affect any of the neuromuscular structures involved in swallowing. Post-stroke dysphagia (PSD) remains the most prevalent and most commonly studied form of dysphagia and, as such, provides an important disease model to assess dysphagia physiology and pathophysiology. In this review, we explore the complex neuroanatomical processes that occur during normal swallowing and PSD. This includes how strokes cause dysphagia, the mechanisms through which natural neuroplastic recovery occurs, current treatments for patients with persistent dysphagia and emerging neuromodulatory treatments.

Efficacy of non-invasive brain stimulation for post-stroke dysphagia: a meta-analysis

BACKGROUND

Given the potential harms of dysphagia after stroke, we noticed the possibility of non-invasive brain stimulation treatments in the management process.

METHODS

The meta-analysis search for articles published before May 2023 in databases. We used STATA 12.0 software to compute the standard mean difference (SMD) and 95% confidence intervals (CI).

RESULTS

The study showed a greater improvement in swallowing function in post-stroke dysphagia given transcranial direct current stimulation (tDCS) immediately after treatment, compared to those given sham tDCS (SMD = 2.99, 95% CI = 1.86-4.11). The study showed a greater improvement in swallowing function in post-stroke dysphagia given tDCS some days after treatment, compared to those given sham tDCS (SMD = 2.01, 95% CI = 0.87-3.16). The study showed a greater improvement in swallowing function in post-stroke dysphagia given repetitive transcranial magnetic stimulation (rTMS) immediately after treatment, compared to those given sham rTMS (SMD = 4.17, 95% CI = 3.11-5.23). The study showed a greater improvement in swallowing function in post-stroke dysphagia given rTMS some days after treatment, compared to those given sham rTMS (SMD = 1.77, 95% CI = 0.94-2.60).

CONCLUSIONS

In conclusion, our study showed the beneficial effects of non-invasive brain stimulation on difficulty swallowing for stroke patients and speculated about the potential application of non-invasive brain stimulation on post-stroke dysphagia improvement.

Transcutaneous electrical stimulation for gastrointestinal motility disorders

BACKGROUND/PURPOSE

Gastrointestinal (GI) dysmotility is categorized by muscle or nerve dysfunctions in any portion of the GI tract, which leads to abnormalities in GI motor and sensory function. Symptoms may vary depending on the organ affected and can be debilitating. Treatment usually involves diet and lifestyle changes. Pharmacotherapy is limited in effectiveness with various side effects. Transcutaneous electrical stimulation (TES), a noninvasive, needleless technique that provides electrical stimulation using cutaneous non-needle electrodes, has become increasingly popular. It has been shown to be beneficial in treating GI motility disorders.

METHODS

This review paper navigates through the different TES techniques, including transcutaneous peripheral nerve (vagal/sacral/tibial nerves) electrical stimulation, transcutaneous electrical acustimulation (stimulation via acupuncture point), transcutaneous interferential current therapy, and transcutaneous electrical nerve stimulation.

KEY RESULTS

As we delve deeper, we explore the promising effects of TES on dysphagia, gastroesophageal reflux disease, functional dyspepsia, gastroparesis, postoperative ileus, constipation, and irritable bowel syndrome. The literature at hand speaks volumes about the therapeutic prowess of this noninvasive technique.

CONCLUSION & INFERENCES

The time is ripe to evaluate further the full therapeutic potential of TES, a noninvasive, nonpharmaceutical, nonsurgical, and home-based self-administrative technique in managing GI motility disorders.

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.

Investigation of the efficacy of low-frequency repetitive transcranial magnetic stimulation on upper-limb motor recovery in subacute ischemic stroke without cortical involvement: a protocol paper for a multi-center, double-blind randomized controlled trial

Introduction

The incidence of stroke is increasing steadily due to factors such as population aging. Approximately 80% of stroke survivors have motor disorders affecting their daily lives. Repetitive transcranial magnetic stimulation (rTMS) has been reported to maximize functional recovery after stroke along with exercise intervention in upper limb rehabilitation treatment. However, whether rTMS affects the recovery of upper limb function in patients with stroke remains unclear. Therefore, in this trial, we will investigate the efficacy of low-frequency rTMS in patients with subcortical and brainstem ischemic stroke.

Methods

This study has been designed as a multi-center, double-blind, randomized controlled trial to compare the efficacy of low-frequency rTMS over the contralesional M1 with sham stimulation. Overall, 88 participants will be allocated to the intervention or control group in a 1:1 ratio, with stratification according to their initial upper extremity Fugl-Meyer assessment (UE-FMA) score. The participants will receive either 30 min of real rTMS (intervention group) or sham rTMS (control group), followed by 30 min of occupational therapy for 10 consecutive workdays. All the participants will receive the same amount of rehabilitation therapy throughout the intervention period. Evaluations will be performed at baseline (T0), at the end of treatment (T1), and 4 weeks after the end of treatment (T2), including the box and block test (BBT), UE-FMA, Korean version of the Modified Barthel Index, and NIH Stroke Scale scores, Finger tapping test, Brunnstrom stage, modified Ashworth scale, and grip strength. The primary outcome will be the change in the BBT score between T0 and T2.

Conclusion

This study will provide evidence on the efficacy of low-frequency rTMS in motor function recovery of the upper limb in patients with subacute, subcortical, and brainstem ischemic stroke.

Clinical trial registration

ClinicalTrials.gov, identifier [NCT05535504].

Evaluating the Therapeutic Application of Neuromodulation in the Human Swallowing System

In the last two decades, the focus of neurogenic dysphagia management has moved from passive compensatory strategies to evidence-based rehabilitative approaches. Advances in technology have enabled the development of novel treatment approaches such as neuromodulation techniques, which target the promotion of neurological reorganization for functional recovery of swallowing. Given the rapid pace of development in the field, this review aims to summarize the current findings on the effects of neuromodulation techniques on the human swallowing system and evaluate their therapeutic potential for neurogenic dysphagia. Implications for future clinical research and practical considerations for using neuromodulation in clinical practice will also be discussed.

Gastrointestinal Dysfunction in Stroke

Gastrointestinal (GI) complications are seen in over 50% of ischemic stroke survivors; the most common complications are dysphagia, constipation, and GI bleeding. The bidirectional relationship of the gut-brain axis and stroke has recently gained traction, wherein stroke contributes to gut dysbiosis (alterations in the normal host intestinal microbiome) and gut dysbiosis perpetuates poor functional neurologic outcomes in stroke. It is postulated that the propagation of proinflammatory cells and gut metabolites (including trimethylamine N-oxide and short-chain fatty acids) from the GI tract to the central nervous system play a central role in gut-brain axis dysfunction. In this review, we discuss the known GI complications in acute ischemic stroke, our current knowledge from experimental stroke models for gut-brain axis dysfunction in stroke, and emerging therapeutics that target the gut-brain axis.

Clinical Practice Guidelines for Oropharyngeal Dysphagia

OBJECTIVE

Dysphagia is a common clinical condition characterized by difficulty in swallowing. It is sub-classified into oropharyngeal dysphagia, which refers to problems in the mouth and pharynx, and esophageal dysphagia, which refers to problems in the esophageal body and esophagogastric junction. Dysphagia can have a significant negative impact one's physical health and quality of life as its severity increases. Therefore, proper assessment and management of dysphagia are critical for improving swallowing function and preventing complications. Thus a guideline was developed to provide evidence-based recommendations for assessment and management in patients with dysphagia.

METHODS

Nineteen key questions on dysphagia were developed. These questions dealt with various aspects of problems related to dysphagia, including assessment, management, and complications. A literature search for relevant articles was conducted using Pubmed, Embase, the Cochrane Library, and one domestic database of KoreaMed, until April 2021. The level of evidence and recommendation grade were established according to the Grading of Recommendation Assessment, Development and Evaluation methodology.

RESULTS

Early screening and assessment of videofluoroscopic swallowing were recommended for assessing the presence of dysphagia. Therapeutic methods, such as tongue and pharyngeal muscle strengthening exercises and neuromuscular electrical stimulation with swallowing therapy, were effective in improving swallowing function and quality of life in patients with dysphagia. Nutritional intervention and an oral care program were also recommended.

CONCLUSION

This guideline presents recommendations for the assessment and management of patients with oropharyngeal dysphagia, including rehabilitative strategies.

A blended neurostimulation protocol to delineate cortico-muscular and spino-muscular dynamics following neuroplastic adaptation

In this paper we propose a novel neurostimulation protocol that provides an intervention-based assessment to distinguish the contributions of different motor control networks in the cortico-spinal system. Specifically, we use a combination of non-invasive brain stimulation and neuromuscular stimulation to probe neuromuscular system behavior with targeted impulse-response system identification. In this protocol, we use an in-house developed human-machine interface (HMI) for an isotonic wrist movement task, where the user controls a cursor on-screen. During the task, we generate unique motor evoked potentials based on triggered cortical or spinal level perturbations. Externally applied brain-level perturbations are triggered through TMS to cause wrist flexion/extension during the volitional task. The resultant contraction output and related reflex responses are measured by the HMI. These movements also include neuromodulation in the excitability of the brain-muscle pathway via transcranial direct current stimulation. Colloquially, spinal-level perturbations are triggered through skin-surface neuromuscular stimulation of the wrist muscles. The resultant brain-muscle and spinal-muscle pathways perturbed by the TMS and NMES, respectively, demonstrate temporal and spatial differences as manifested through the human-machine interface. This then provides a template to measure the specific neural outcomes of the movement tasks, and in decoding differences in the contribution of cortical- (long-latency) and spinal-level (short-latency) motor control. This protocol is part of the development of a diagnostic tool that can be used to better understand how interaction between cortical and spinal motor centers changes with learning, or injury such as that experienced following stroke.

Effects of transcutaneous neuromuscular electrical stimulation on post-stroke dysphagia: a systematic review and meta-analysis

Background

Dysphagia is one of the common complications after stroke. It is closely related to lung infection and malnutrition. Neuromuscular electrical stimulation (NMES) is widely used in the treatment of post-stroke dysphagia, but the evidence-based medical evidence of NMES is limited. Therefore, this study aimed to evaluate the clinical efficacy of NMES in patients with post-stroke dysphagia by systematic review and meta-analysis.

Methods

We searched the CNKI, Wanfang, VIP, SinoMed, PubMed, Embase, Cochrane Library, and Web of Science databases for all randomized controlled trials (RCTs) of NMES in the treatment of post-stroke dysphagia from the establishment of the database to 9 June 2022. The risk of bias assessment tool recommended by Cochrane and the GRADE method was used to assess the risk of bias and the quality of evidence. RevMan 5.3 was used for statistical analysis. Sensitivity and subgroup analyses were performed to evaluate the intervention effect more specifically.

Results

A total of 46 RCTs and 3,346 patients with post-stroke dysphagia were included in this study. Our meta-analysis showed that NMES combined with routine swallowing therapy (ST) could effectively improve swallowing function in Penetration-Aspiration Scale (MD = -0.63, 95% CI [-1.15, -0.12], P = 0.01), Functional Oral Intake Scale (MD = 1.32, 95% CI [0.81, 1.83], P < 0.00001), Functional Dysphagia Scale (MD = - 8.81, 95% CI [-16.48, -1.15], P = 0.02), the Standardized Swallowing Assessment (MD = -6.39, 95% CI [-6.56, -6.22], P < 0.00001), the Videofluoroscopic Swallow Study (MD = 1.42, 95% CI [1.28, 1.57], P < 0.00001) and the Water swallow test (MD = -0.78, 95% CI [-0.84, -0.73], P < 0.00001). Furthermore, it could improve the quality of life (MD = 11.90, 95% CI [11.10, 12.70], P < 0.00001), increase the upward movement distance of hyoid bone (MD = 2.84, 95% CI [2.28, 3.40], P < 0.00001) and the forward movement distance of hyoid bone (MD = 4.28, 95% CI [3.93, 4.64], P < 0.00001), reduce the rate of complications (OR = 0.37, 95%CI [0.24, 0.57], P < 0.00001). Subgroup analyses showed that NMES+ST was more effective at 25 Hz, 7 mA or 0-15 mA, and at courses ( ≤ 4 weeks). Moreover, patients with an onset of fewer than 20 days and those older than 60 years appear to have more positive effects after treatment.

Conclusion

NMES combined with ST could effectively increase the forward and upward movement distance of the hyoid bone, improve the quality of life, reduce the rate of complications, and improve the swallowing function of patients with post-stroke dysphagia. However, its safety needs to be further confirmed.

Systematic review registration

https://www.crd.york.ac.uk/PROSPERO, identifier: CRD42022368416.

The effects of intermittent theta burst stimulation of the unilateral cerebellar hemisphere on swallowing-related brain regions in healthy subjects

Objective

We aimed to investigate the effects and mechanisms of swallowing-related brain regions using resting-state functional magnetic resonance imaging (rs-fMRI) in healthy subjects who underwent intermittent theta burst stimulation (iTBS) on dominant or non-dominant cerebellar hemispheres.

Methods

Thirty-nine healthy subjects were randomized into three groups that completed different iTBS protocols (dominant cerebellum group, non-dominant cerebellum group and sham group). Before iTBS, the resting motor threshold (rMT) was measured by single-pulse transcranial magnetic stimulation (sTMS) on the cerebellar representation of the suprahyoid muscles, and the dominant cerebellar hemisphere for swallowing was determined. Forty-eight hours after elution, iTBS protocols were completed: in the dominant cerebellum group, iTBS was administered to the dominant cerebellar hemisphere, and the non-dominant cerebellar hemisphere was given sham stimulation; in the non-dominant cerebellum group, iTBS was administered to the non-dominant cerebellar hemisphere, and sham stimulation was delivered to the dominant cerebellar hemisphere; in the sham group, sham stimulation was applied to the cerebellum bilaterally. Rs-fMRI was performed before and after iTBS stimulation to observe changes in the fractional amplitude of low-frequency fluctuation (fALFF) in the whole brain.

Results

Compared with baseline, the dominant cerebellum group showed increased fALFF in the ipsilateral cerebellum, and decreased fALFF in the ipsilateral middle temporal gyrus and contralateral precuneus after iTBS; the iTBS of the non-dominant cerebellum group induced increased fALFF in the ipsilateral superior frontal gyrus, the calcarine fissure and the surrounding cortex, and the contralateral inferior parietal lobule; and in the sham group, there was no significant difference in fALFF. Exploring the effects induced by iTBS among groups, the dominant cerebellum group showed decreased fALFF in the contralateral calcarine fissure, and surrounding cortex compared with the sham group.

Conclusion

Intermittent theta burst stimulation of the dominant cerebellar hemisphere for swallowing excited the ipsilateral cerebellum, and stimulation of the non-dominant cerebellar hemisphere increased the spontaneous neural activity of multiple cerebrocortical areas related to swallowing. In conclusion, regardless of which side of the cerebellum is stimulated, iTBS can facilitate part of the brain neural network related to swallowing. Our findings provide supporting evidence that cerebellar iTBS can be used as a potential method to modulate human swallowing movement.

Sensory neuromuscular electrical stimulation for dysphagia rehabilitation: A literature review

BACKGROUND

Dysphagia is a common disorder following a cerebrovascular accident. It can cause detrimental effects on patient's quality of life and nutrition intake, especially in older adults. Neuromuscular electrical stimulation has been one of the management strategies for acceleration of the recovery. This review summarises the current evidence on sensory threshold stimulation of the procedure.

METHOD

This review compiled data from the Internet database PubMed, Cochrane Library and Scopus using combination of MeSH thesaurus: 'Sensory threshold', 'electrical stimulation', 'neuromuscular stimulation', 'Deglutition', 'Dysphagia'. Eleven studies were intergraded into the review.

RESULTS

Most of the studies show significant improvement to the outcomes of sensory neuromuscular electrical stimulation treatment. In many cases, the results of the treatment are comparable or superior to motor threshold stimulation and conventional therapy. However, the study design and parameters of the procedure varied greatly without conclusive standardised guidelines.

CONCLUSION

The sensory neuromuscular electrical stimulation (SNMES) is a viable treatment option for treating oropharyngeal dysphagia. The most suggested application parameters are an intensity at sensory threshold, a frequency of 80 Hz, an impulse time of 700 μs, a combined total duration of 20 h of stimulation in a 2-week period, and placing the electrodes in the submental area of the neck. However, further research is necessary to construct a definitive guideline for clinicians.

Effect of Repetitive Transcranial Magnetic Stimulation on Post-stroke Dysphagia: A Meta-analysis of Stimulation Frequency, Stimulation Site, and Timing of Outcome Measurement

Dysphagia is one of the most frequent sequelae of stroke. It can result in various complications such as malnutrition, dehydration, aspiration pneumonia, and poor rehabilitation outcomes. Repetitive transcranial magnetic stimulation (rTMS) has been reported to improve dysphagia after a stroke; however, effective treatment protocols have not been established yet. We evaluated the effect of the following rTMS parameters on post-stroke dysphagia: stimulation frequency [high frequency (≥ 3 Hz) or low frequency (1 Hz)] and stimulation site (ipsilesional or contralesional mylohyoid cortex). Outcomes were measured immediately, at 3 weeks, and at 4 weeks after the rTMS session. The PubMed, SCOPUS, Embase, and Cochrane Library databases were systematically searched for relevant studies published between January 01, 1980, and December 13, 2021. Randomized controlled trials on the effects of rTMS on post-stroke dysphagia were included. Six studies were finally included in the analysis. The selected studies included 158 patients (rTMS group: 81 patients; sham group: 77 patients). Regarding the effect of high-frequency rTMS on the ipsilesional cortex, the standardized swallowing assessment (SSA) scores showed significant improvement after rTMS sessions immediately and at 4 weeks [immediate: P = 0.02, standard mean difference (SMD) =  - 0.61, 95% confidence interval (CI) =  - 1.14 to - 0.08; 4 weeks: P = 0.006, SMD =  - 0.74, 95% CI =  - 1.27 to - 0.21]; however, there was no significant reduction in the Penetration-Aspiration Scale (PAS) scores between the rTMS and sham groups (immediate: P = 0.43, SMD = 0.25, 95% CI =  - 0.36, 0.86; 3 weeks: P = 0.39, SMD = 0.37, 95% CI =  - 0.47 to 1.22). After low-frequency rTMS on the ipsilesional cortex, a significantly greater improvement in the SSA scores was found in the rTMS group than in the sham group, both immediately and at 4 weeks after rTMS sessions (immediate: P = 0.03, SMD =  - 0.59, 95% CI =  - 1.12 to - 0.06; 4 weeks: P = 0.001, SMD =  - 0.92, 95% CI =  - 1.48 to - 0.37). In addition, immediately after the rTMS sessions, the PAS scores were significantly reduced in the rTMS group than in the sham group (P = 0.047, SMD =  - 0.60, 95% CI =  - 1.19 to - 0.01). However, at 4 weeks after rTMS sessions, there was no significant reduction in the PAS scores in the rTMS group compared to the sham group (P = 0.48, SMD =  - 0.19, 95% CI =  - 0.71 to 0.33). Both high-frequency rTMS of the ipsilesional cortex and low-frequency rTMS of the contralesional cortex improved some measurements of the swallowing function in stroke patients immediately and at 4 weeks after treatment.

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/ ).

The Effectiveness of Transcranial Stimulation in Improving Swallowing Outcomes in Adults with Poststroke Dysphagia: A Systematic Review and Meta-analysis

Transcranial stimulation has been proposed as an alternative rehabilitation therapy for adults with post-stroke dysphagia (PSD). This systematic review sought to determine the effectiveness of transcranial stimulation in patients with post-stroke dysphagia to improve swallowing function. From inception to January 3, 2021, an extensive search was conducted in PubMed, EMBASE, Cochrane, CINAHL, and Scopus, Web of Science. The randomized controlled trials (RCTs) included studies in adults aged 18 years and older who suffered from post-stroke dysphagia. Using Hedges' g as effect size, meta-analyses were conducted using random-effects models. To investigate potential sources of heterogeneity, subgroup analyses, and multivariable meta-regression analyses were conducted. Sixteen RCTs were included in this review, and 13 RCTs were used for meta-analysis. The meta-analysis showed that a large effect size in improving swallowing function after repetitive Transcranial Magnetic Stimulation (g = - 0.86, 95% CI - 1.57, - 0.16) and medium effect size in Transcranial Direct Current Stimulation (g = - 0.61, 95% CI - 1.04, - 0.17) at post-intervention, respectively. Subgroup and meta-regression analysis indicated that stimulation of the esophagus cortical area and middle-aged adults had a greater effect on swallowing function. The overall certainty of evidence assessed using the GRADE approach was low. Despite the positive results, transcranial stimulation requires additional research to reach definitive conclusions about the optimal stimulation protocol and to achieve the greatest benefit. Future trials should be more rigorous and include a larger sample size to demonstrate the efficacy of transcranial stimulation. Transcranial stimulation enables a more efficacious approach to dysphagia mitigation in PSD rehabilitation.

Advances in the Treatment of Dysphagia in Neurological Disorders: A Review of Current Evidence and Future Considerations

Dysphagia, which refers to difficult and/or disordered swallowing, is a common problem associated with various neurological diseases such as stroke, motor neuron diseases and neurodegenerative diseases. Traditionally, dysphagia treatments are either compensatory, which includes modifications of bolus texture or feeding posture, or rehabilitative, which includes behavioral exercises and sensory stimulation. Despite being widely adopted in clinical practice, recent views have challenged the clinical efficacy of these treatments due to the low level of evidence supported by mainly non-controlled studies. As such, with advancements in technology and scientific research methods, recent times have seen a surge in the development of novel dysphagia treatments and an increasing number of robust randomized controlled clinical trials. In this review, we will review the clinical evidence of several newly introduced treatments for dysphagia in the last two decades, including rehabilitative exercises, biofeedback, pharmacological treatments, neuromodulation treatments and soft robotics. Despite the recent improvements in the quality of evidence for the efficacy of dysphagia treatments, several critical issues, including heterogeneity in treatment regimens, long-term treatment effects, underlying mechanisms of some neuromodulation treatments, and the effects of these techniques in non-stroke dysphagia, remain to be addressed in future clinical trials.

The Effects of Neuromuscular Electrical Stimulation on Swallowing Functions in Post-stroke Dysphagia: A Randomized Controlled Trial

The study aimed to evaluate the effects of traditional dysphagia therapy (TDT) and neuromuscular electrical stimulation (NMES) combined with TDT on functionality of oral intake, dysphagia symptom severity, swallowing- and voice-related quality of life, leakage, penetration-aspiration, and residue levels in patients with post-stroke dysphagia (PSD). Thirty-four patients with PSD were included in our prospective, randomized, controlled, and single-blind study. The patients were divided into two groups: (1) TDT only (control group, n = 17) and (2) TDT with NMES (experimental group, n = 17). TDT was applied to both groups for three consecutive weeks, 5 days a week, 45 min a day. Sensory NMES was applied to the experimental group for 45 min per session. Patients were evaluated by the functional oral intake scale (FOIS), the eating assessment tool (EAT-10), the swallowing quality of life questionnaire (SWAL-QOL), and the voice-related quality of life questionnaire (VRQOL) at baseline, immediately post-intervention, and at the 3rd month post-intervention. Fiberoptic endoscopic evaluation of swallowing (FEES) with liquid and semi-solid food was performed pre- and post-intervention. A significant post-intervention improvement was observed on all scales in both groups, and these improvements were maintained 3 months post-intervention. Leakage and penetration-aspiration levels with semi-solid food declined only in the experimental group. In conclusion, TDT is a non-invasive and inexpensive method that leads to improvement in many swallowing-related features in stroke patients; however, NMES as an adjunct therapy is costly but can provide additional benefits for improving features, such as penetration-aspiration and residue levels.

High-Frequency Cerebellar rTMS Improves the Swallowing Function of Patients with Dysphagia after Brainstem Stroke

Objective

To explore the efficacy of high-frequency repetitive transcranial magnetic stimulation (rTMS) of the swallowing motor area of the cerebellum in patients with dysphagia after brainstem stroke.

Methods

A total of 36 patients with dysphagia after brainstem stroke were recruited and divided into 3 groups. Before stimulation, single-pulse transcranial magnetic stimulation (TMS) was used to determine the swallowing dominant cerebellar hemisphere and the representation of the mylohyoid muscle. The three groups of patients received bilateral cerebellar sham stimulation, dominant cerebellar rTMS + contralateral sham stimulation, or bilateral cerebellar rTMS. The stimulus plan for each side was 10 Hz, 80% resting movement threshold (rMT), 250 pulses, 1 s per stimulus, and 9 s intervals. Sham rTMS was performed with the coil held at 90° to the scalp. The changes in the motor evoked potential (MEP) amplitude and the clinical swallowing function scales of the patients after stimulation were compared among the three groups.

Results

34 patients were finally included for statistical analysis. The scores of penetration aspiration scale (PAS) and functional dysphagia scale (FDS) of the patients after 2 weeks of rTMS in the unilateral stimulation group and bilateral stimulation group were better than that in the sham stimulation group, and there was no significant difference between the two groups. The increase in the MEP amplitude of the cerebral hemisphere in the bilateral stimulation group was higher than that in the other two groups, and the increase in the MEP amplitude in the unilateral stimulation group was higher than that in sham stimulation group. There was no correlation between the improvement in patients' clinical swallowing function (PAS scores and FDS scores) and the increase in MEP amplitude in either the unilateral stimulation group or the bilateral stimulation group.

Conclusion

High-frequency rTMS in the cerebellum can improve swallowing function in PSD patients and increase the excitability of the representation of swallowing in the bilateral cerebral hemispheres. Compared with unilateral cerebellar rTMS, bilateral stimulation increased the excitability of the cerebral swallowing cortex more significantly, but there was no significant difference in clinical swallowing function.

Comparison Between Comprehensive Nursing Care Ward and Private Care Ward on Functional Recovery in Stroke Patients

The need for a comprehensive nursing care service ward (CNCW) is emerging, but few studies have investigated its medical validity. This study aimed to assess the effect of hospitalization on functional recovery and fall incidence in poststroke patients. This retrospective study enrolled 354 patients with subacute stroke between July 2017 and April 2020. CNCW provided full caregiving and nursing to the patient. Baseline demographic and hospital data, including fall occurrence, were collected. Functional outcomes, including the Medical Research Council (MRC), Korean version of the Modified Barthel Index (K-MBI), and Korean version of the Mini-Mental State Examination (K-MMSE), were evaluated upon admission and discharge. One hundred seventy-two patients were hospitalized in CNCW among the 354 stroke patients. Initial and final K-MMSE and K-MBI were significantly higher in the CNCW group. The K-MMSE score gain was significantly lower in the CNCW group (p < 0.05). The fall occurrence was significantly higher in the CNCW group (p < 0.01). Hospitalization in CNCW adversely affected cognitive function after stroke. Falls were detected more frequently and reported in CNCW.

Therapeutic Effect and Optimal Electrode Placement of Transcutaneous Neuromuscular Electrical Stimulation in Patients with Post-Stroke Dysphagia: A Systematic Review and Meta-Analysis of Randomized Controlled Trials

Background: To date, there is no conclusive evidence that transcutaneous neuromuscular electrical stimulation (TNMES) benefits patients with post-stroke dysphagia (PSD). In addition, the optimal TNMES electrode placement has not been well-established. This systematic review and meta-analysis were conducted to investigate these two research gaps. Methods: Five major databases were systematically searched for randomized controlled trials (RCTs) through January 2022. Effect sizes were computed using Hedges’ g statistic, which were then entered into the random-effects model to obtain pooled effect estimates. Results: Twenty-four RCTs met the eligibility criteria. On the improvement of swallowing function, TNMES alone was not superior to conventional swallowing therapies (CSTs); combined therapy of TNMES and CSTs significantly surpassed CSTs alone (standardized mean difference (SMD) = 0.91, 95% confidence interval (95% CI): 0.68 to 1.14, p < 0.0001; I2 = 63%). Moreover, significant pooled effect sizes were observed in subgroups with horizontal electrode placement above the hyoid bone (SMD = 0.94, 95% CI: 0.72 to 1.16; I2 = 0%) and horizontal electrode placement just above and below the hyoid bone (SMD = 0.87, 95% CI: 0.59 to 1.14; I2 = 0%). The largest pooled effect size was observed in the subgroup that individualized electrode placement according to dysphagia evaluation (SMD = 1.65, 95% CI: 0.38 to 2.91; I2 = 90%). Conclusion: TNMES should be used in combination with CSTs for PSD. Horizontal electrode placement should target suprahyoid muscles or both suprahyoid and thyrohyoid muscles.

Transcranial magnetic stimulation versus transcutaneous neuromuscular electrical stimulation in post stroke dysphagia: A clinical randomized controlled trial

OBJECTIVES

To evaluate the efficacy of high-frequency repeated transcranial magnetic stimulation (rTMS) applied contralesionally versus transcutaneous neuromuscular electrical stimulation (TNES) in acute post-stroke dysphagic patients.

MATERIALS AND METHODS

A randomized, parallel, comparative, controlled trial was conducted on patients with acute ischemic stroke who were admitted to our department. Fifteen patients received rTMS, 15 patients received TNES, and 15 patients were recruited as a control group. Between the second and tenth days after a stroke, patients were enrolled. The study and follow-up periods were completed by all patients.

RESULTS

Among the screened patients, 45 (31.47%) right-handed patients were diagnosed with post-stroke dysphagia with a mean age of 60.53 ± 8.23 years. Immediately after intervention both rTMS and TNES groups significantly improve the swallowing disturbance questionnaire (SDQ) and penetration aspiration scale (PAS), compared to the control (p < 0.001 and p = 0.027), respectively. rTMS was more effective than TNES in reducing SDQ and PAS (p < 0.05). rTMS and TNES improved the Yale Pharyngeal Residue Severity Rating Scale (YPRSRS) significantly (p = 0.002); however, their efficacy was comparable (p > 0.05). A significant (p < 0.001) strong negative correlation was observed between the grade of weakness and all scores.

CONCLUSION

Our findings showed that high-frequency rTMS and TNES effectively improved the clinical condition of acute post-stroke dysphagic patients in terms of swallowing disturbance assessed by SDQ, pharyngeal residue assessed by YPRSRS, and the severity of penetration and aspiration events evaluated by PAS, compared to the controls. The outcomes of high-frequency rTMS were more favorable than those of TNES in terms of SDQ and PAS.

Effectiveness of repetitive transcranial magnetic stimulation on poststroke dysphagia: a meta-analysis of randomized-controlled trials

Dysphagia is a common functional impairment after stroke, resulting in aspiration of liquids, ingested foods, or oral secretions and influencing the quality of life. Noninvasive repetitive transcranial magnetic stimulation has been widely used for rehabilitation of dysphagia. The purpose of this meta-analysis was to investigate the efficacy of repetitive transcranial magnetic stimulation on poststroke swallowing impairment. Four databases were systematically searched for eligible studies from their inception to 31 September 2021. Review Manager 5.4 software was used for this meta-analysis. The bias of included randomized controlled trials was assessed using the version 2 of the Cochrane risk-of-bias tool for randomized trials. Nine randomized controlled trials involving 393 patients were included according to the selection criteria. The results revealed significant benefit of repetitive transcranial magnetic stimulation as a treatment of dysphagia following the onset of stroke, when compared with intervention without repetitive transcranial magnetic stimulation. Applying repetitive transcranial magnetic stimulation on different stimulation sites effectively improved the dysphagia of poststroke patients, and no significant difference was observed among the different stimulation sites subgroups. Our findings support repetitive transcranial magnetic stimulation as an effectively treatment of the poststroke dysphagia, especially in unilateral hemispheric stroke patients.

Post-stroke Dysphagia: Prognosis and Treatment-A Systematic Review of RCT on Interventional Treatments for Dysphagia Following Subacute Stroke

Purpose

Post-stroke dysphagia is an underdiagnosed but relevant complication, associated with worse outcome, dependency and quality of life of stroke survivors. Detailed mechanisms of post-stroke dysphagia are not very well understood, but established therapeutic concepts are needed. Different interventional studies have been published dealing with post-stroke dysphagia. This systematic review wants to collect and give an overview over the published evidence.

Methods

PubMed, Embase, Cochrane, CINAHL were searched for relevant interventional studies on post-stroke dysphagia in the (sub-)acute setting (within 3 months of stroke onset). The search has been filtered for randomized trials with an inactive control and the relevant data extracted.

Results

After initially finding 2,863 trials, finally 41 trials have been included. Seven different therapeutic concepts have been evaluated (Acupuncture, behavioral/physical therapy, drug therapy, neuromuscular electrical stimulation, pharyngeal electrical stimulation, transcranial direct current stimulation and repetitive transcranial magnetic stimulation). Studies of all modalities have shown some effect on post-stroke dysphagia with several studies raising concerns about the potential bias.

Conclusion

The amount and quality of studies are not enough to suggest certain therapies. Some therapeutical concepts (intensive physical therapy, transcranial magnetic stimulation, drug therapy) seem to be good potential therapeutic options, but further research is needed.

Clinical effect of repetitive transcranial magnetic stimulation on dysphagia due to stroke

BACKGROUND

Repetitive transcranial magnetic stimulation (rT) could change the excitability of the cerebral cortex, and control the neurotransmitter release, with the therapeutic effect depending on stimulation intensity and position. In this study, we used 3 Hz rTMS to stimulate the pharyngeal cortical area of the lesioned hemisphere and to explore its clinical significance in the treatment of dysphagia after acute cerebral infarction.

METHODS

A total of 61 in-patients with acute dysphagia caused by cerebral infarction hospitalized in the department of neurology of our hospital were included in this study and were assigned into the control and rTMS group. Patients in the control group only accepted the basic treatment of rehabilitation training, while patients in the rTMS group received additional rTMS (3 Hz) stimulation. The levels of the water swallowing test (WST) 14 days before and after the treatment of rTMS (3 Hz) would be recorded.

RESULTS

After different therapies in two groups, 9 patients of the control group showed excellent curative effect, with a recovery rate of 31.0%. However, in the rTMS group, the swallowing function of 21 patients was significantly improved, with a recovery rate of 65.6%. Comparison results showed that the recovery rate of the rTMS group was much better than the control group (P < 0.05), indicating an effective therapeutic effect of 3 Hz rTMS on patients with dysphagia after acute cerebral infarction.

CONCLUSION

Stimulating the target cortical representation areas of pharyngeal of the lesioned hemisphere with cerebral infarction by the rTMS (3 Hz) could improve the patients' function.

The Effect and Optimal Parameters of Repetitive Transcranial Magnetic Stimulation on Poststroke Dysphagia: A Meta-Analysis of Randomized Controlled Trials

Objective

The objectives of the study were to evaluate the efficacy of repetitive transcranial magnetic stimulation (rTMS) treatment for poststroke dysphagia (PSD) and explore the optimal stimulation parameters.

Method

The databases of Medline, Embase, Web of Science, and Cochrane Library were searched from the establishment to June 2021. All randomized controlled trials about rTMS treatment for PSD were enrolled. Dysphagia Grade (DG) and Penetration Aspiration Scale (PAS) were applied as the major dysphagia severity rating scales to evaluate the outcomes.

Results

A total of 12 clinical randomized controlled studies were included in our study. The summary effect size indicated that rTMS had a positive effect on PSD (SMD = −0.67, p < 0.001). The subgroup analysis for treatment duration and different stroke stages showed significant differences (treatment duration >5 days: SMD = −0.80, p < 0.001; subacute phase after stroke: SMD = −0.60, p < 0.001). Furthermore, no significant differences were observed among the other stimulation parameter subgroups (including stimulation frequency, location, and a single stimulation time) (p > 0.05).

Conclusion

rTMS is beneficial to the recovery of PSD patients, while an intervention of more than 5 days and in the subacute phase after stroke might bring new strategies and rational therapeutics to the treatment of PSD.

Systematic Review Registration

http://www.crd.york.ac.uk/PROSPERO/, identifier: CRD42022299469.

Transcranial Magnetic Stimulation for Improving Dysphagia After Stroke: A Meta-Analysis of Randomized Controlled Trials

Background

Rehabilitation of post-stroke dysphagia is an urgent clinical problem, and repetitive transcranial magnetic stimulation (rTMS) has been widely used in the study of post-stroke function. However, there is no reliable evidence-based medicine to support the effect of rTMS on post-stroke dysphagia. This review aims to evaluate the effectiveness and safety of rTMS on post-stroke dysphagia.

Methods

English-language literature published before December 20, 2021, were searched in six electronic databases. Identified articles were screened, data were extracted, and the methodological quality of included trials was assessed. Meta-analysis was performed using RevMan 5.3 software. The GRADE method was used to assess the quality of the evidence.

Results

A total of 10 studies with 246 patients were included. Meta-analysis showed that rTMS significantly improved overall swallowing function (standardized mean difference [SMD]−0.76, 95% confidence interval (CI)−1.07 to−0.46, p < 0.0001, n = 206; moderate-quality evidence), Penetration Aspiration Scale (PAS) (mean difference [MD]−1.03, 95% CI−1.51 to−0.55, p < 0.0001, n = 161; low-quality evidence) and Barthel index scale (BI) (MD 23.86, 95% CI 12.73 to 34.99, p < 0.0001, n = 136; moderate-quality evidence). Subgroup analyses revealed that (1) rTMS targeting the affected hemisphere and targeting both hemispheres significantly enhanced overall swallowing function and reduced aspiration. (2) Low-frequency rTMS significantly enhanced overall swallowing function and reduced aspiration, and there was no significant difference between high-frequency rTMS and control group in reducing aspiration (p = 0.09). (3) There was no statistical difference in the dropout rate (low-quality evidence) and adverse effects (moderate-quality evidence) between the rTMS group and the control group.

Conclusion

rTMS improved overall swallowing function and activity of daily living ability and reduced aspiration in post-stroke patients with good acceptability and mild adverse effects.

Benefits from Repetitive Transcranial Magnetic Stimulation in Post-Stroke Rehabilitation

Stroke is an acute neurovascular central nervous system (CNS) injury and one of the main causes of long-term disability and mortality. Post-stroke rehabilitation as part of recovery is focused on relearning lost skills and regaining independence as much as possible. Many novel strategies in neurorehabilitation have been introduced. This review focuses on current evidence of the effectiveness of repetitive transcranial magnetic stimulation (rTMS), a noninvasive brain stimulation (NIBS), in post-stroke rehabilitation. Moreover, we present the effects of specific interventions, such as low-frequency or high-frequency rTMS therapy, on motor function, cognitive function, depression, and aphasia in post-stroke patients. Collected data suggest that high-frequency stimulation (5 Hz and beyond) produces an increase in cortical excitability, whereas low-frequency stimulation (≤1 Hz) decreases cortical excitability. Accumulated data suggest that rTMS is safe and can be used to modulate cortical excitability, which may improve overall performance. Side effects such as tingling sensation on the skin of the skull or headache are possible. Serious side effects such as epileptic seizures can be avoided by adhering to international safety guidelines. We reviewed clinical studies that present promising results in general recovery and stimulating neuroplasticity. This article is an overview of the current rTMS state of knowledge related to benefits in stroke, as well as its cellular and molecular mechanisms. In the stroke rehabilitation literature, there is a key methodological problem of creating double-blinding studies, which are very often impossible to conduct.

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.

Neurostimulation in People with Oropharyngeal Dysphagia: A Systematic Review and Meta-Analysis of Randomised Controlled Trials-Part II: Brain Neurostimulation

Objective. To assess the effects of brain neurostimulation (i.e., repetitive transcranial magnetic stimulation [rTMS] and transcranial direct current stimulation [tDCS]) in people with oropharyngeal dysphagia (OD). Methods. Systematic literature searches were conducted in four electronic databases (CINAHL, Embase, PsycINFO, and PubMed) to retrieve randomised controlled trials (RCTs) only. Using the Revised Cochrane risk-of-bias tool for randomised trials (RoB 2), the methodological quality of included studies was evaluated, after which meta-analysis was conducted using a random-effects model. Results. In total, 24 studies reporting on brain neurostimulation were included: 11 studies on rTMS, 9 studies on tDCS, and 4 studies on combined neurostimulation interventions. Overall, within-group meta-analysis and between-group analysis for rTMS identified significant large and small effects in favour of stimulation, respectively. For tDCS, overall within-group analysis and between-group analysis identified significant large and moderate effects in favour of stimulation, respectively. Conclusion. Both rTMS and tDCS show promising effects in people with oropharyngeal dysphagia. However, comparisons between studies were challenging due to high heterogeneity in stimulation protocols and experimental parameters, potential moderators, and inconsistent methodological reporting. Generalisations of meta-analyses need to be interpreted with care. Future research should include large RCTs using standard protocols and reporting guidelines as achieved by international consensus.

Neurostimulation in People with Oropharyngeal Dysphagia: A Systematic Review and Meta-Analyses of Randomised Controlled Trials-Part I: Pharyngeal and Neuromuscular Electrical Stimulation

Objective. To assess the effects of neurostimulation (i.e., neuromuscular electrical stimulation (NMES) and pharyngeal electrical stimulation (PES)) in people with oropharyngeal dysphagia (OD). Methods. Systematic literature searches were conducted to retrieve randomised controlled trials in four electronic databases (CINAHL, Embase, PsycINFO, and PubMed). The methodological quality of included studies was assessed using the Revised Cochrane risk-of-bias tool for randomised trials (RoB 2). Results. In total, 42 studies reporting on peripheral neurostimulation were included: 30 studies on NMES, eight studies on PES, and four studies on combined neurostimulation interventions. When conducting meta analyses, significant, large and significant, moderate pre-post treatment effects were found for NMES (11 studies) and PES (five studies), respectively. Between-group analyses showed small effect sizes in favour of NMES, but no significant effects for PES. Conclusions. NMES may have more promising effects compared to PES. However, NMES studies showed high heterogeneity in protocols and experimental variables, the presence of potential moderators, and inconsistent reporting of methodology. Therefore, only conservative generalisations and interpretation of meta-analyses could be made. To facilitate comparisons of studies and determine intervention effects, there is a need for more randomised controlled trials with larger population sizes, and greater standardisation of protocols and guidelines for reporting.

The Effect of Repetitive Transcranial Magnetic Stimulation on Dysphagia After Stroke: A Systematic Review and Meta-Analysis

Objective: The primary purpose of our study is to systemically evaluate the effect of repetitive transcranial magnetic stimulation (rTMS) on recovery of dysphagia after stroke.

Search Methods: We searched randomized controlled trials (RCTs) and non-RCTs published by PubMed, the Cochrane Library, ScienceDirect, MEDLINE, and Web of Science from inception until April 24, 2021. Language is limited to English. After screening and extracting the data, and evaluating the quality of the selected literature, we carried out the meta-analysis with software RevMan 5.3 and summarized available evidence from non-RCTs.

Results: Among 205 potentially relevant articles, 189 participants (from 10 RCTs) were recruited in the meta-analysis, and six non-RCTs were qualitatively described. The random-effects model analysis revealed a pooled effect size of SMD = 0.65 (95% CI = 0.04–1.26, p = 0.04), which indicated that rTMS therapy has a better effect than conventional therapy. However, the subgroup analysis showed that there was no significant difference between low-frequency and high-frequency groups. Even more surprisingly, there were no statistically significant differences between the two groups and the conventional training group in the subgroup analysis, but the combined effect was positive.

Conclusion: Our study suggests that rTMS might be effective in treating patients with dysphagia after stroke.

Systematic Review and Network Meta-Analysis of Noninvasive Brain Stimulation on Dysphagia after Stroke

Background

Dysphagia is a common sequelae after stroke. Noninvasive brain stimulation (NIBS) is a tool that has been used in the rehabilitation process to modify cortical excitability and improve dysphagia.

Objective

To systematically evaluate the effect of NIBS on dysphagia after stroke and compare the effects of two different NIBS.

Methods

Randomized controlled trials about the effect of NIBS on dysphagia after stroke were retrieved from databases of PubMed, Embase, Cochrane Library, Web of Science, CNKI, Wanfang Data, VIP, and CBM, from inception to June 2021. The quality of the trials was assessed, and the data were extracted according to the Cochrane Handbook for Systematic Reviews of Interventions. A statistical analysis was carried out using RevMan 5.3 and ADDIS 1.16.8. The effect size was evaluated by using the standardized mean difference (SMD) and a 95% confidence interval (CI).

Results

Ultimately, 18 studies involving 738 patients were included. Meta-analysis showed that NIBS could improve the dysphagia outcome and severity scale (DOSS) score (standard mean difference (SMD) = 1.44, 95% CI 0.80 to 2.08, P < 0.05) and the water swallow test score (SMD = 6.23, 95% CI 5.44 to 7.03, P < 0.05). NIBS could reduce the standardized swallowing assessment (SSA) score (SMD = −1.04, 95% CI -1.50 to -0.58, P < 0.05), the penetration-aspiration scale (PAS) score (SMD = −0.85, 95% CI -1.33 to -0.36, P < 0.05), and the functional dysphagia scale score (SMD = −1.05, 95% CI -1.48 to -0.62, P < 0.05). Network meta-analysis showed that the best probabilistic ranking of the effects of two different NIBS on the DOSS score is rTMS (P = 0.52) > tDCS (P = 0.48), the best probabilistic ranking of the SSA score is rTMS (P = 0.72) > tDCS (P = 0.28), and the best probabilistic ranking of the PAS score is rTMS (P = 0.68) > tDCS (P = 0.32).

Conclusion

Existing evidence showed that NIBS could improve swallowing dysfunction and reduce the occurrence of aspiration after stroke, and that rTMS is better than tDCS. Limited by the number of included studies, more large-sample, multicenter, double-blind, high-quality clinical randomized controlled trials are still needed in the future to further confirm the results of this research.

European Stroke Organisation and European Society for Swallowing Disorders guideline for the diagnosis and treatment of post-stroke dysphagia

Post-stroke dysphagia (PSD) is present in more than 50% of acute stroke patients, increases the risk of complications, in particular aspiration pneumonia, malnutrition and dehydration, and is linked to poor outcome and mortality. The aim of this guideline is to assist all members of the multidisciplinary team in their management of patients with PSD. These guidelines were developed based on the European Stroke Organisation (ESO) standard operating procedure and followed the Grading of Recommendations, Assessment, Development and Evaluation (GRADE) approach. An interdisciplinary working group identified 20 relevant questions, performed systematic reviews and meta-analyses of the literature, assessed the quality of the available evidence and wrote evidence-based recommendations. Expert opinion was provided if not enough evidence was available to provide recommendations based on the GRADE approach. We found moderate quality of evidence to recommend dysphagia screening in all stroke patients to prevent post-stroke pneumonia and to early mortality and low quality of evidence to suggest dysphagia assessment in stroke patients having been identified at being at risk of PSD. We found low to moderate quality of evidence for a variety of treatment options to improve swallowing physiology and swallowing safety. These options include dietary interventions, behavioural swallowing treatment including acupuncture, nutritional interventions, oral health care, different pharmacological agents and different types of neurostimulation treatment. Some of the studied interventions also had an impact on other clinical endpoints such as feedings status or pneumonia. Overall, further randomized trials are needed to improve the quality of evidence for the treatment of PSD.

Metaplasticity in the human swallowing system: clinical implications for dysphagia rehabilitation

Dysphagia is a common and devastating complication following brain damage. Over the last 2 decades, dysphagia treatments have shifted from compensatory to rehabilitative strategies that facilitate neuroplasticity, which is the reorganization of neural networks that is essential for functional recovery. Moreover, there is growing interest in the application of cortical and peripheral neurostimulation to promote such neuroplasticity. Despite some preliminary positive findings, the variability in responsiveness toward these treatments remains substantial. The purpose of this review is to summarize findings on the effects of neurostimulation in promoting neuroplasticity for dysphagia rehabilitation and highlight the need to develop more effective treatment strategies. We then discuss the role of metaplasticity, a homeostatic mechanism of the brain to regulate plasticity changes, in helping to drive neurorehabilitation. Finally, a hypothesis on how metaplasticity could be applied in dysphagia rehabilitation to enhance treatment outcomes is proposed.

Current perspectives on the benefits, risks, and limitations of noninvasive brain stimulation (NIBS) for post-stroke dysphagia

INTRODUCTION

Studies have shown that noninvasive brain stimulation (NIBS), including repetitive transcranial magnetic stimulation (rTMS) and transcranial direct current stimulation (tDCS), can promote neuroplasticity, which is considered important for functional recovery of swallowing after stroke. Despite extensive studies on NIBS, there remains a gap between research and clinical practice.

AREAS COVERED

In this article, we update the current knowledge on the benefits and challenges of rTMS and tDCS for post-stroke dysphagia. We identify some key limitations of these techniques that hinder the translation from clinical trials to routine practice. Finally, we discuss the future of NIBS as a treatment for post-stroke dysphagia in real-world settings.

EXPERT OPINION

Current evidence suggests that rTMS and tDCS show promise as a treatment for post-stroke dysphagia. However, these techniques are limited by the response variability, uncertainty on the safety in patients with comorbidities and difficulties in clinical study designs. Such limitations call for further work to enhance their utility through individualized approaches. Despite this, the last decade has seen a growing acceptance toward these techniques among clinical personnel. As such, we advocate caution but support optimism that NIBS will gradually be recognized as a mainstream treatment approach for post-stroke dysphagia in the future.

Comparative efficacy of non-invasive neurostimulation therapies for poststroke dysphagia: A systematic review and meta-analysis

OBJECTIVE

To explore the effect of non-invasive neurostimulation therapies on dysphagia patients after stroke.

METHODS

We searched MEDLINE (Ovid), PubMed, Embase, Web of Science, ScienceDirect, and Cochrane library databases until April 22, 2020. All published and unpublished randomized controlled trials (RCT) were included. Full texts were independently reviewed. The risk of RCT bias was evaluated by two independent assessors using the Cochrane risk of bias tool. The primary outcome measure was swallowing function before and after neurostimulation therapy. The effect sizes are calculated from the extracted data and combined into a comprehensive summary statistic.

RESULT

A total of 27 randomized controlled trials were included in this study, involving 914 stroke patients (27 intervention groups and 20 control groups). Meta-analysis showed that compared with the control group, noninvasive neurostimulation therapies (repetitive transcranial magnetic stimulation (rTMS), transcranial direct current stimulation (tDCS), surface neuromuscular electrical stimulation (sNMES) or pharyngeal electrical stimulation (PES)) had a better effect (SMD = 0.91; 95% CI: 0.54-1.27; Z = 4.84; P < 0.00001; I² = 86%). In the subgroup analysis based on type of stimulus, rTMS appeared to perform better. In the subgroup analysis based on clinical phase, stimulation applied in the acute phase may be more effective. In the subgroup analysis based on the site of injury, the brainstem injury group seemed to achieve better outcomes. In the subgroup analysis based on stroke type, the cerebral infarction group had better outcomes than the cerebral infarction/hemorrhage mixed group.

CONCLUSIONS

Non-invasive neurostimulation therapies can effectively promote the recovery of dysphagia after stroke.

Improvement of P ost S troke D ysphagia by I ntermittent T heta B urst S timulation

The present study aims to investigate the efficacy ofi ntermittent theta burst stimulation(iTBS) on post stroke dysphagia and its effect on the motor cortical excitability of thesuprahyoid muscle A total of 40 patients with post stroke dysphagia were randomlydivided into the iTBS and the sham stimulation groups, with the conduction of motorcortical iTBS and sham stimulation of the supraglottal muscle on the affected side,respectively . Swallowing function was assessed before (T0), immediately after (T1), andtwo weeks after (T2) cessation of the intervention using the water swallowing test (WST),standard swallowing assessment (SSA), Murray secretion scale (MSS), and PenetrationAspiration Scale ( PAS). The bilateral motor evoked potentials (MEP) of the suprahyoidmuscle were recorded After the intervention, the PAS, WST, SSA, and MSS scores weresignificantly improved in both groups (p < 0.05). The iTBS group showed a greaterchange in the PAS sco re than the sham stimulation group at T1 (p < 0.05) and a greaterchange in the WST and MSS scores at T2 (p < 0.05). The amplitude of the MEP wave ofthe suprahyoid muscle in the affected hemisphere was significantly higher in the iTBSgroup at T1 and in t he healthy hemisphere at T2 (p < 0.05). T he feasibility of applyingiTBS to the affected hemisphere for the treatment of post stroke dysphagia was directlyanalyzed for the first time. ITBS combined with conventional swallowing therapy couldbe adopted as a rehabilitation strategy to improve post stroke dysphagia.

Effects of Neurostimulation on Poststroke Dysphagia: A Synthesis of Current Evidence From Randomized Controlled Trials

Objectives

To evaluate the effects of neurostimulation, including repetitive transcranial magnetic stimulation (rTMS), transcranial direct current stimulation (tDCS) and pharyngeal electrical stimulation (PES), for poststroke dysphagia based on evidence from randomized controlled trials (RCTs).

Materials and Methods

Electronic databases were systematically searched between January 1985 and June 2020 and studies were included based on prespecified selection criteria. The quality of studies was evaluated and data were extracted and synthesized by two independent reviewers. The primary outcome measure was change in (any) relevant clinical swallowing‐related characteristic. Subgroup analysis were conducted based on follow‐up period and stimulation parameters.

Results

Data from 852 stroke patients were collected from 26 RCTs studies. Active neurostimulation treatments demonstrated a significant and moderate effect size compared to control treatment (0.69 [95% CI = 0.50, 0.89]; p < 0.001). The effect size of rTMS was the largest (0.73 [95% CI = 0.49, 0.98]; p < 0.001), followed by PES (0.68 [95% CI = 0.22, 1.14]; p = 0.004) and tDCS (0.65 [95% CI = 0.25, 1.04]; p = 0.001). All treatments showed comparable effect sizes within the first two weeks. Between three weeks and two months, tDCS demonstrated the largest effects (1.02 [95% CI = 0.45, 1.59]; p < 0.001) among the three treatments. No significant treatment effects were reported beyond three months. The combined effect size was large when applied in acute (<14 days) stroke (0.8 [95% CI = 0.34, 1.26]; p < 0.001). For noninvasive brain stimulation (NIBS), bihemispheric stimulation demonstrated the strongest effect size (0.93 [95% CI = 0.53, 1.33]; p < 0.001). In contrast, unilateral rTMS using ipsilesional high‐frequency stimulation had a combined effect size of 0.83 (95% CI = 0.14, 1.52; p = 0.02). For tDCS, a significant effect size was found only with anodal stimulation applied over the contralesional hemisphere (1.04 [95% CI = 0.54, 1.53]; p < 0.001).

Conclusions

The results show that neurostimulation can benefit patients with poststroke dysphagia. The treatment effects were the strongest in acute stroke patients and within the first two months of application. For NIBS, bihemispheric stimulation appeared to be most effective. The most beneficial hemisphere for unilateral stimulation differed between rTMS and tDCS. These findings provide a platform for future studies and clinical practice.

Effectiveness of Neuromuscular Electrical Stimulation on Post-Stroke Dysphagia: A Systematic Review of Randomized Controlled Trials

The purpose of this review was to summarize the latest best scientific evidence on the efficacy of neuromuscular electrical stimulation on swallowing function in dysphagic stroke patients. A comprehensive systematic search of literature published between November 2014 and May 2020 was performed using the following electronic databases: PubMed/Medline, CINAHL, PEDro, Science Direct, Google Scholar, EMBASE, and Scopus. Only randomized controlled trials (RCT) evaluating the effect of neuromuscular electrical stimulation on swallowing function in dysphagic stroke patients were included. Physiotherapy Evidence Database (PEDro) has been used to evaluate the risk of bias of included trials. This review was reported in accordance with PRISMA statement guideline. The methodological quality of the studies was determined using PEDro scale and GRADE approach. Evidence of overall quality was graded from moderate to high. Eleven RCTs involving 784 patients were analyzed. The primary outcome measures of this review were functional dysphagia scale (FDS) and standard swallowing assessment. This review found neuromuscular electrical stimulation (NMES) coupled with traditional swallowing therapy could be an optional intervention to improve swallowing function after stroke in rehabilitation department.

Short-term neurophysiological effects of sensory pathway neurorehabilitation strategies on chronic poststroke oropharyngeal dysphagia

BACKGROUND

Neurorehabilitation strategies for chronic poststroke (PS) oropharyngeal dysphagia (OD) have been mainly focused on the neurostimulation of the pharyngeal motor cortex with only marginal effects. In contrast, treatments targeting the PS oropharyngeal sensory pathway dysfunction offer very promising results, but there is little knowledge on the underlying mechanisms. We aimed to explore the neurophysiological mechanisms behind the effect of three sensory neurostimulation strategies.

METHODS

We carried out a randomized two-blinded parallel group's crossover sham-controlled clinical trial in 36 patients with unilateral stroke and chronic unsafe swallow to investigate the effect of repetitive transcranial magnetic stimulation (rTMS) of the primary sensory cortex (A), oral capsaicin (B) and intra-pharyngeal electrical stimulation (IPES; C). The effect was evaluated immediately after the interventions with videofluoroscopy (VFS) and motor/sensory evoked potentials (MEP/SEP).

KEY RESULTS

Interventions induced no changes in the biomechanics of the swallow response during VFS. However, an enhancement of motor cortex excitability (latency shortening and increased size of thenar MEP) was found with active interventions (A + B + C, and B/C alone; P < .05 for all) but not with sham. Active but not sham interventions shortened pharyngeal SEP latency in the ipsilesional hemisphere (A + B + C: P2-peak, P = .039; A: N2-peak, P = .034) and antagonized the physiological habituation in pharyngeal MEP (A + B + C and A alone, P < .05 for both).

CONCLUSIONS AND INFERENCES

Sensory pathway neurostimulation strategies caused immediate enhancement of motor cortex excitability with peripheral strategies (capsaicin and IPES) and of pharyngeal sensory conduction with rTMS. These changes support the use of sensory neurorehabilitation strategies in promoting swallow recovery in chronic PS-OD.

The impact of dysphagia on quality of life in stroke patients

The objective of this study was to investigate the quality of life in stroke patients using a swallowing quality of life (SWAL-QOL) questionnaire. The correlation between SWAL-QOL questionnaire outcome and videofluoroscopic dysphagia scale (VDS) scores in stroke patients was also determined.This cross-sectional study was retrospectively conducted with 75 stroke patients with dysphagia symptoms. Videofluoroscopic swallowing study (VFSS) and SWAL-QOL questionnaires were performed for all patients. These patients were divided into an oral feeding group and a tube feeding group. SWAL-QOL scores were compared between the 2 groups. The severity of dysphagia was estimated by VDS scores according to the videofluoroscopic swallowing study results. The relationships between SWAL-QOL scores and VDS scores were also investigated.The composite score was 48.82 ± 19.51 for the tube feeding group and 53.17 ± 25.42 for the oral feeding group. There were significant differences in burden and sleep subdomains of the SWAL-QOL between the 2 groups (P = .005 and P = .012, respectively). There was a significant negative correlation between the composite score of SWAL-QOL outcome and the total VDS score (r = -0.468, P = .012). The pharyngeal-phase score of the VDS had significant negative correlations with the SWAL-QOL subdomains of burden (r = -0.327, P = .013), mental health (r = -0.348, P = .008), and social functioning (r = -0.365, P = .029).To improve the quality of life of stroke patients, dysphagia rehabilitation should focus on the pharyngeal phase of dysphagia.