Effect of repetitive transcranial magnetic stimulation on patients with brain injury and 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.

Evidence for Intermittent Theta Burst Transcranial Magnetic Stimulation for Dysphagia after Stroke: A Systematic Review and Meta-analysis

Dysphagia is the most common serious complication after stroke, with an incidence of about 37-78%, which seriously affects the independence of patients in daily life and clinical recovery. Repetitive transcranial magnetic stimulation (rTMS), as a non-invasive neuromodulation technique, is an emerging option for post-stroke dysphagia. Theta burst stimulation (TBS) is a new mode of transcranial magnetic stimulation that simulates the frequency of pulses released in the hippocampus.Intermittent theta burst stimulation (iTBS) has been shown to increase cortical excitability and improve swallowing function in patients. Our study sought to summarize existing clinical randomized controlled trials to provide evidence-based medical evidence for the clinical use of iTBS. A computer search was conducted on 4 Chinese (Chinese Biomedical Literature Database, VIP Information Resource System, CNKI, and Wanfang Medical Science) and 4 English (including Cochrane Library, Embase, PubMed, Web of Science) databases to retrieve all randomized controlled trials in Chinese and English that explored the effects of Intermittent Theta Burst Stimulation for post-stroke dysphagia. The retrieval years are from database construction to 23 November 2023. The primary outcome measure was a change in Penetration/Aspiration Scale (PAS), Standardized Swallowing Assessment (SSA) and Functional Oral Intake Scale (FOIS), Secondary outcomes included Fiberoptic Endoscopic Dysphagia Severity Scale (FEDSS), water-swallowing test (WST) etc. A meta-analysis by Standardized Mean Difference (SMD) and 95% confidence interval (CI) was performed with RevMan 5.3. we appraise risk of bias(RoB) of each study with the Cochrane RoB tool. Detailed instructions for using the Cochrane RoB tool are provided in the Cochrane Handbook for Systematic Reviews of Interventions (The Cochrane Handbook). Nine studies were obtained from eight databases after screening by inclusion and exclusion criteria, 567 patients from 9 studies were included in the meta-analysis, and one study was included in the qualitative analysis due to different control groups. Two of the nine studies had an unclear risk of bias, and four studies were at low risk. The results showed that iTBS significantly improved SSA, PAS, FOIS, and PAS scores in stroke patients compared to the control group(P < 0.05), and promoted swallowing function recovery. Our systematic review provides the first evidence of the efficacy of iTBS in improving dysphagia in stroke patients. However, the number of available studies limits the persuasiveness of the evidence and further validation by additional randomized controlled trials is needed.

Comparison of the efficacy and tolerability of different repetitive transcranial magnetic stimulation modalities for post-stroke dysphagia: a systematic review and Bayesian network meta-analysis protocol

INTRODUCTION

Up to 78% of patients who had a stroke develop post-stroke dysphagia (PSD), a significant consequence. Life-threatening aspiration pneumonia, starvation, and water and electrolyte abnormalities can result. Several meta-analyses have shown that repeated transcranial magnetic stimulation (rTMS) improves swallowing in patients who had a stroke; however, the optimum model is unknown. This study will be the first Bayesian network meta-analysis (NMA) to determine the best rTMS modalities for swallowing of patients who had a stroke.

METHODS AND ANALYSIS

PubMed, Web of Science, Embase, Google Scholar, Cochrane, the Chinese National Knowledge Infrastructure, the Chongqing VIP Database and WanFang Data will be searched from their creation to 2 September 2023. All randomised controlled trials associated with rTMS for PSD will be included. Only Chinese or English results will be studied. Two researchers will independently review the literature and extract data, then use the Cochrane Collaboration's Risk of Bias 2.0 tool to assess the included studies' methodological quality. The primary outcome is swallowing function improvement, whereas secondary outcomes include side effects (eg, paraesthesia, vertigo, seizures) and quality of life. A pairwise meta-analysis and NMA based on a Bayesian framework will be conducted using Stata and R statistical software. The Grading of Recommendations Assessment, Development, and Evaluation system will assess outcome indicator evidence quality.

ETHICS AND DISSEMINATION

As all data in this study will be taken from the literature, ethical approval is not needed. We will publish our work in peer-reviewed publications and present it at academic conferences.

PROSPERO REGISTRATION NUMBER

CRD42023456386.

Exploration of treatment methods for patients with post-stroke dysphagia: a network meta-analysis

To compare the effects of various therapies in patients with post-stroke dysphagia.

DATA SOURCES

We searched databases between January 1980 and 2022.

STUDY ELIGIBILITY CRITERIA

Randomized controlled trials (RCTs) on therapy for dysphagia after stroke.

STUDY APPRAISAL AND SYNTHESIS METHODS

The outcomes were improvement in dysphagia, case fatality, and chest infection or pneumonia, reported as OR (odd ratio), 95% CrI (confidence interval), and SUCRA (the surface under the cumulative ranking curve analysis) score. Forty-two randomized controlled trials (2,993 patients, seven therapies, and one control) were included. In the improvement of dysphagia analysis, the following therapies were superior to the control: Acupuncture, behavioral interventions, drug therapy, neuromuscular electrical stimulation (NMES) and pharyngeal electrical stimulation (PES). In the case fatality analysis, OR and 95% CrI indicated none of the therapies were superior to the control. In the chest infection or pneumonia analysis, OR values showed that no therapy was superior to the control. Our Network Meta-analysis suggests that commonly used therapies for dysphagia after stroke have equal efficacies.

Effect of repetition of rTMS at different frequencies on the efficacy of swallowing disorders after stroke: A systematic review and meta-analysis

BACKGROUND

To systematically evaluate the curative effect of repeated transcranial magnetic stimulation at different frequencies on swallowing disorders after stroke.

METHODS

A search was conducted for randomized controlled trials of repeated transcranial magnetic stimulation for stroke patients in CNKI, Wanfang, VIP, ProQuest, PubMed, Cochrane Library, Scopus, and Web of Science databases until December 2022. The 2 researchers strictly screened and checked the included documents, extracted relevant data, assessed the risk quality of the literature using the Cochrane manual, and conducted a network meta-analysis of the data using State16.0.

RESULTS

Eighteen studies included 680 participants. The results of the reticular meta-analysis showed that in the leakage-aspiration scale (PAS) indicators, 1 Hz, 3 Hz, 5 Hz, and 10 Hz were all better treatment effects compared with the control group, and there was a statistically significant difference (P < .05). In the standard swallowing function assessment (SSA) index, 3 Hz, 5 Hz, and 10 Hz compared with the control group were statistically significant (P < .05); there was no difference between 1 Hz and the control group (P > .05). The cumulative probability ranking results showed that the intervention effect of 3 Hz was the best in the PAS index, much greater than that of other frequencies, and the intervention effects of 10 Hz and 5 Hz were similar. For the SSA index, the intervention effect was optimal at 10 Hz, followed by 5 Hz. Note that the treatment effect of 1 Hz ranked last, even lower than that of the control group. The results of the 5 Hz treatment site grouping analysis showed that the affected side was > bilateral > healthy in PAS and > bilateral > healthy in SSA.

CONCLUSION SUBSECTIONS

Based on the current study, the optimal frequency and site selection results of the 2 evaluation indicators are not uniform, but from the combination of the 2 evaluation indicators, the treatment effect of 10H is good, and the effect of bilateral stimulation for the selection of stimulation sites is good. The above conclusions need to be verified in high-quality studies.

Effectiveness of antidepressant repetitive transcranial magnetic stimulation in a patient with refractory psychogenic dysphagia: A case report and review of literature

BACKGROUND

Dysphagia is a common condition in older as well as young patients, and a variety of treatments have been reported depending on the cause. However, clinicians are challenged when the cause is unclear. This is the case with psychogenic dysphagia, which has typically been treated with supportive psychotherapy, medication, swallowing exercise, and dysphagia rehabilitation therapy. Here, we aimed to relieve the symptoms of a patient with refractory psychogenic dysphagia, who was unresponsive to conventional swallowing therapy, with repetitive transcranial magnetic stimulation (rTMS).

CASE SUMMARY

A relatively calm-looking 35-year-old female patient presented with a 2-year history of dysphagia. She showed little improvement with conventional swallowing treatments over the past 2 years. She was relatively compliant with in-hospital dysphagia therapy, but uncooperative with home exercise and medication. In particular, since she was resistant to drug treatment, we had to take a different approach than the treatment she had been receiving for the past 2 years. After much deliberation, we decided to initiate antidepressant rTMS treatment with her consent (IRB No. 2023-05-021). Antidepressant rTMS treatment was performed twice weekly for a total of 20 sessions over 10 wk. The results showed improvement in subjective symptoms and video fluoroscopic swallowing study findings. To the best of our knowledge, this is the first report of symptomatic improvement using antidepressant rTMS protocol for refractory psychogenic dysphagia.

CONCLUSION

This case demonstrates that rTMS with antidepressant protocol can be used to improve swallowing in patients with refractory psychogenic dysphagia.

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.

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.

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/ ).

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.

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.

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.

The Effect of Repetitive Transcranial Magnetic Stimulation of Cerebellar Swallowing Cortex on Brain Neural Activities: A Resting-State fMRI Study

Objective

The effects and possible mechanisms of cerebellar high-frequency repetitive transcranial magnetic stimulation (rTMS) on swallowing-related neural networks were studied using resting-state functional magnetic resonance imaging (rs-fMRI).

Method

A total of 23 healthy volunteers were recruited, and 19 healthy volunteers were finally included for the statistical analysis. Before stimulation, the cerebellar hemisphere dominant for swallowing was determined by the single-pulse TMS. The cerebellar representation of the suprahyoid muscles of this hemisphere was selected as the target for stimulation with 10 Hz rTMS, 100% resting motor threshold (rMT), and 250 pulses, with every 1 s of stimulation followed by an interval of 9 s. The motor evoked potential (MEP) amplitude of the suprahyoid muscles in the bilateral cerebral cortex was measured before and after stimulation to evaluate the cortical excitability. Forty-eight hours after elution, rTMS was reapplied on the dominant cerebellar representation of the suprahyoid muscles with the same stimulation parameters. Rs-fMRI was performed before and after stimulation to observe the changes in amplitude of low-frequency fluctuation (ALFF) and regional homology (ReHo) at 0.01–0.08 Hz, 0.01–0.027 Hz, and 0.027–0.073 Hz.

Results

After cerebellar high-frequency rTMS, MEP recorded from swallowing-related bilateral cerebral cortex was increased. The results of rs-fMRI showed that at 0.01–0.08 Hz, ALFF was increased at the pons, right cerebellum, and medulla and decreased at the left temporal lobe, and ReHo was decreased at the left insular lobe, right temporal lobe, and corpus callosum. At 0.01–0.027 Hz, ALFF was decreased at the left temporal lobe, and ReHo was decreased at the right temporal lobe, left putamen, and left supplementary motor area.

Conclusion

Repetitive transcranial magnetic stimulation of the swallowing cortex in the dominant cerebellar hemisphere increased the bilateral cerebral swallowing cortex excitability and enhanced pontine, bulbar, and cerebellar spontaneous neural activity, suggesting that unilateral high-frequency stimulation of the cerebellum can excite both brainstem and cortical swallowing centers. These findings all provide favorable support for the application of cerebellar rTMS in the clinical practice.

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.

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.

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.

Scoping review to identify and map non-pharmacological, non-surgical treatments for dysphagia following moderate-to-severe acquired brain injury

INTRODUCTION

Dysphagia is a common and critical consequence of acquired brain injury (ABI) and can cause severe complications. Dysphagia rehabilitation is transforming from mainly compensatory strategies to the retraining of swallowing function using principles from neuroscience. However, there are no studies that map interventions available to retrain swallowing function in patients with moderate-to-severe ABI.

OBJECTIVE

To systematically map the accessible research literature to answer the research question: Which non-surgical, non-pharmacological interventions are used in the treatment of dysphagia in patients with moderate and severe ABI in the acute and subacute phase? DESIGN: Scoping review based on the methodology of Arksey and O'Malley and methodological advancement by Levac et al. DATA SOURCES: MEDLINE, Embase, Cochrane Library, CINAHL, PsycINFO, Web of Science, OTseeker, speechBITE and PEDro were searched up until 14 March 2021.

ELIGIBILITY CRITERIA

All studies reporting rehabilitative interventions within 6 months of injury for patients with moderate-to-severe ABI and dysphagia were included.

DATA EXTRACTION AND SYNTHESIS

Data was extracted by two independent reviewers and studies were categorised based on treatment modality.

RESULTS

A total of 21 396 records were retrieved, and a final of 26 studies were included. Interventions were categorised into cortical or non-cortical stimulation of the swallowing network. Cortical stimulation interventions were repetitive transcranial magnetic stimulation (rTMS) and transcranial direct current stimulation. Non-cortical were complex swallowing interventions, neuromuscular electrical stimulation, pharyngeal electrical stimulation (PES), sensory stimulation, strengthening exercises and respiratory muscle training.

CONCLUSION

This scoping review provides an overview of rehabilitative dysphagia interventions for patients with moderate and severe ABI, predominantly due to stroke, in the acute and subacute phase. Positive tendencies towards beneficial effects were found for rTMS, complex swallowing interventions, PES and cervical strengthening. Future studies could benefit from clear reporting of patient diagnosis and disease severity, the use of more standardised treatment protocols or algorithms and fewer but standardised outcome measures to enable comparison of effects across studies and interventions.

The effects of different frequencies of repetitive transcranial magnetic stimulation (rTMS) on patients with swallowing disorders after cerebral infarction

BACKGROUND

Swallowing disorders represent one of the most common complications after cerebral infarction.

OBJECTIVE

To study the effects of different frequencies of repetitive transcranial magnetic stimulation (rTMS) on swallowing disorders after cerebral infarction.

METHODS

Ninety patients with swallowing disorder after cerebral infarction were enrolled and randomly assigned to three groups: the 10 Hz frequency rTMS group (30 patients), the 5 Hz frequency rTMS group (30 patients), and the 1 Hz frequency rTMS group (30 patients); another 90 healthy persons without swallowing disorders were included as the control group. The Kubota's water-swallow test, the video fluoroscopic swallow study (VFSS), and the Electroencephalograph (EEG) were analyzed before and after treatment; the EEG of the control group was detected as the baseline.

RESULTS

The Kubota's water-swallow test scores were significantly decreased while the scores of pharynx period and the aspiration degree of VFSS significantly increased in 10 Hz frequency rTMS group than before treatment (P≤0.05); the amplitudes of C3 of the EEG significantly increased in three frequency groups than before treatment (P≤0.05).

CONCLUSIONS

10 Hz frequency of rTMS is effective for the treatment of swallowing disorder after cerebral infarction, the excitement of C3 area maybe the therapeutic target of rTMS on swallowing disorder after cerebral infarction.

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.

Noninvasive Brain Stimulation for Poststroke Dysphagia: A Meta-Analysis for Randomized Controlled Trials

BACKGROUND

Past research has indicated that repetitive transcranial magnetic stimulation (rTMS) on the pharyngeal motor cortex may be beneficial to poststroke dysphagic patients. In addition, some studies have supported that transcranial direct current stimulation (tDCS) over the pharyngeal motor cortex can improve swallowing function in poststroke dysphagia. However, some studies showed that rTMS and tDCS show no effect on poststroke dysphagia. This study aims to make a meta-analysis to investigate the therapy effect of rTMS and tDCS on poststroke dysphagia in randomized controlled trials (RCTs).

METHODS

We searched for studies published before March 2021 in databases (PubMed, Web of Science, MEDLINE, EMBASE, and Google Scholar). Meta-analysis was made to compute the results of included studies using STATA 12.0 software.

RESULTS

The present study shows a significant increase in the swallowing function in poststroke dysphagia given rTMS compared to those given sham rTMS (standardized mean difference [SMD] = 1.08, 95% confidence interval [CI] = 0.37-1.80, I2 = 81.2%, p < 0.001). In addition, the study shows a significant increase in the swallowing function in poststroke dysphagia given tDCS (combined or not combined with conventional swallowing therapy), compared to those given sham tDCS (combined or not combined with conventional swallowing therapy) (SMD = 1.43, 95% CI = 0.73-2.13, I2 = 77.6%, p < 0.001).

CONCLUSIONS

The study demonstrates that rTMS and tDCS over the pharyngeal motor cortex show therapy effects on poststroke dysphagia. Many more large-scale, blinded RCTs are essential to investigate the effect of rTMS and tDCS on poststroke dysphagia.

Videofluoroscopic Swallowing Study Findings Associated With Subsequent Pneumonia in Patients With Dysphagia Due to Frailty

Dysphagia in frailty or deconditioning without specific diagnosis that may cause dysphagia such as stroke, traumatic brain injury, or laryngeal pathology, has been reported in previous studies; however, little is known about which findings of the videofluoroscopic swallowing study (VFSS) are associated with subsequent pneumonia and how many patients actually develop subsequent pneumonia in this population. In this study, we followed 190 patients with dysphagia due to frailty or deconditioning without specific diagnosis that may cause dysphagia for 3 months after VFSS and analyzed VFSS findings for the risk of developing pneumonia. During the study period, the incidence of subsequent pneumonia was 24.74%; regarding the VFSS findings, (1) airway penetration (PAS 3) and aspiration (PAS 7 and 8) were associated with increased risk of developing pneumonia, and (2) the functional dysphagia scale (FDS) scores of the patients who developed subsequent pneumonia were higher than those of the patients who did not develop subsequent pneumonia. Our study findings might assist clinicians in making clinical decisions based on the VFSS findings in this population.

The efficacy of repetitive transcranial magnetic stimulation on emotional processing in apathetic patients with Parkinson's disease: A Placebo-controlled ERP study

BACKGROUND

Few studies have examined the effect of rTMS on impaired emotional processing in apathetic Parkinson's disease (PD) patients, which impelled us to use a combination of repetitive transcranial magnetic stimulation (rTMS) with event-related potentials (ERPs) to gain insight into the underlying mechanisms.

METHODS

Apathetic and non-apathetic patients diagnosed with PD performed a facial emotion categorization task, and ERP data were collected before and after HF-rTMS or sham stimulation over the right dorsolateral prefrontal cortex (DLPFC). We observed the behavioural results and early components of P100 and N170.

RESULTS

After rTMS, accuracy (ACC) was higher for negative expressions, and reaction times (RTs) were shorter for all expressions in both apathetic and non-apathetic patients. P100 amplitudes significantly increased except for negative expressions in the right hemisphere, and hemisphere lateralization was reversed in apathetic patients. P100 amplitudes increased for all expressions bilaterally in non-apathetic patients. N170 amplitudes in apathetic patients increased, and hemisphere lateralization was normalized. Neither the apathetic sham group nor the non-apathetic cohort of patients showed changes in P100 or N170 lateralization.

LIMITATIONS

The effects of rTMS on PD patients relative to normal subjects should be compared and observed over a long period of time.

CONCLUSIONS

HF-rTMS over the right DLPFC is beneficial for emotional processing in both apathetic and non-apathetic PD patients but shows different sensitivities. The effect of rTMS on emotional processing impairments in apathetic PD patients is profound. Treatment with rTMS may be an important, novel nonpharmaceutical approach for apathy in PD patients.

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.

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.

Dysphagia in Lateral Medullary Syndrome: A Narrative Review

Dysphagia is a common clinical feature of lateral medullary syndrome (LMS) and is clinically relevant because it is related to aspiration pneumonia, malnutrition, increased mortality, and prolonged hospital stay. Herein, the pathophysiology, prognosis, and treatment of dysphagia in LMS are reviewed. The pathophysiology, prognosis, and treatment of dysphagia in LMS are closely interconnected. Although the pathophysiology of dysphagia in LMS has not been fully elucidated, previous studies have suggested that the medullary central pattern generators coordinate the pharyngeal phases of swallowing. Investigation of the extensive neural connections of the medulla oblongata is important in understanding the pathophysiologic mechanism of dysphagia in LMS. Previous studies have reported that most patients with dysphagia in LMS have a relatively good prognosis. However, some patients require tube feeding for several months, even years, due to severe dysphagia, and little has been reported about conditions associated with a poor prognosis of dysphagia in LMS. Concerning specific therapeutic modalities for dysphagia in LMS, in addition to general modalities used for dysphagia treatment in stroke patients, non-invasive modalities, including repetitive transcranial magnetic stimulation and transcranial direct current stimulation, as well as invasive modalities, such as botulinum toxin injection, balloon catheter dilatation, and myotomy for relaxation of the cricopharyngeal muscle, have been applied. For the appropriate application of therapeutic modalities, clinicians should be aware of the recovery mechanisms and prognosis of dysphagia in LMS. Further studies on this topic, as well as studies involving large numbers of subjects on specific therapeutic modalities, should be encouraged.

Advances in the Use of Neuromodulation for Neurogenic Dysphagia: Mechanisms and Therapeutic Application of Pharyngeal Electrical Stimulation, Transcranial Magnetic Stimulation, and Transcranial Direct Current Stimulation

Purpose The swallowing motor system and, specifically, its cortical substrates appear to have certain unique properties that make it highly susceptible to brain plasticity, both driven and following injury. Furthermore, neurogenic dysphagia is a common complication of brain disease, associated with poor outcomes, and yet treatment options remain limited. Therefore, translating the physiology of neurostimulation into clinical populations becomes imperative. In this review, we describe therapeutic application of neuroplasticity in the human swallowing motor system by initially examining the role of pharyngeal electrical stimulation from a mechanistic perspective and then reporting on clinical studies using this approach. Thereafter, we explore the application of noninvasive brain stimulation, which has previously been used to treat nervous system disorders such as depression, pain modulation, and cognitive impairment. Transcranial brain stimulations, in particular, transcranial magnetic stimulation and transcranial direct current stimulation, have been utilized by a number of investigators for rehabilitation in early-stage clinical trials, including dysphagia after neurological disease. In this review, we assess its usefulness in neurogenic dysphagia. Conclusion Early studies indicate these emerging neurostimulatory techniques hold future therapeutic promise. However, both a greater number of and larger clinical trials are required to provide evidence delineating their efficacy and scope of application.

Use of the Penetration-Aspiration Scale in Dysphagia Research: A Systematic Review

The penetration-aspiration scale (PAS) is an 8-point scale used to characterize the depth and response to airway invasion during videofluoroscopy. Though widely used in the field of deglutition, there is a lack of consensus regarding the statistical properties of the scale. In order to better understand the state of the literature and the statistical use of the PAS, a systematic review was undertaken to descriptively examine trends in statistical and reporting practices of the PAS since its inception. Online databases were searched for studies citing the original PAS article, which yielded 754 unique articles. Of these, 183 studies were included in the review. Results showed inconsistencies in the statistical use of the scale; 79 studies treated the PAS as ordinal, 71 as categorical, and 49 as interval. Ten types of categorizations were identified. Reporting of power analyses (9%), as well as inter- (26%) and intra-rater (17%) reliability, was uncommon. Among studies that administered multiple bolus volumes or consistencies, 55% reported PAS analyses at the participant/group level only. This review confirms the existence of discrepancies in the statistical treatment of the PAS. A lack of consensus among researchers limits comparisons between studies. The approach to handling this scale dictates the statistical tests used, potentially affecting results and interpretations. Consistent application of statistically sound approaches to PAS analyses is vital for the future of deglutition research.

Genetic influences on the variability of response to repetitive transcranial magnetic stimulation in human pharyngeal motor cortex

BACKGROUND

Recent studies have reported substantial variability in response to repetitive transcranial magnetic stimulation (rTMS). We hypothesized that an individual's genetic predisposition may contribute to such variability in the pharyngeal motor cortex. This study aimed to investigate the response to 1 and 5 Hz rTMS paradigms on pharyngeal motor cortex in healthy participants and its relationship with genetic predisposition.

METHODS

Forty-one healthy participants (25.4 ± 4.6 years old) received either or both 1 Hz (n = 39) and 5 Hz rTMS (n = 40) over pharyngeal motor cortex. Pharyngeal and thenar motor-evoked potentials were recorded at baseline and for 1 hour post-rTMS. The participants were then classified according to their response. The associations between rTMS response and gender, time of day of the stimulation, and eight prespecified single nucleotide polymorphisms (SNPs) were analyzed.

KEY RESULTS

There was no direction-specific response to either paradigm (1 Hz: F[3.69, 129.21] = 0.78, P = 0.56; 5 Hz: F[4.08, 146.85] = 1.38, P = 0.25). Only 13% of participants showed the expected bidirectional response (inhibition for 1 Hz and excitation for 5 Hz). Significant associations were found between response and COMT (1 Hz: P = 0.03) and DRD2 (1 Hz: P = 0.02; 5 Hz: P = 0.04) polymorphisms. Carriers of minor allele G from SNP rs6269 (COMT) were more likely to show inhibitory or excitatory outcomes after 1 Hz rTMS. By contrast, carriers of minor allele A from SNP rs1800497 (DRD2) were more likely to show no response to 1 Hz rTMS and inhibition after 5 Hz rTMS.

CONCLUSIONS & INFERENCES

Two SNPs from COMT and DRD2 genes may partially explain the response variability to rTMS in the pharyngeal motor system. Further research should focus on stratified approaches for neurostimulatory dysphagia treatment using rTMS.

Effects of Low-Frequency Repetitive Transcranial Magnetic Stimulation on Swallowing Function and Quality of Life of Post-stroke Patients

Repetitive transcranial magnetic stimulation (rTMS) is one of the non-invasive techniques, which is used to modulate cortical regions in patients with stroke. The aim of this single blind, controlled study was to investigate the effect of rTMS on swallowing function and quality of life of mono-hemispheric post-stroke patients with dysphagia. Twenty-eight patients were randomized and split between study and control group. Each group received conventional dysphagia rehabilitation 3 days a week for 4 weeks, and study group also received 1 Hz rTMS to unaffected hemisphere in the final week. The descriptive information was noted. The clinical and radiological swallowing evaluation and quality of life assessment have been performed at four different times including before and after the treatment, 1 month and 3 months after the treatment. At baseline, no significant differences were observed between groups in terms of demographic and clinical features (p > 0.05). Swallowing function and quality of life of the patients were statistically improved in both groups towards the third month (p < 0.05). Swallowing function was comparable between two groups. However, a significant improvement was observed on appetite, fear of eating, and mental health parameters of quality of life assessment in the study group compared to the control group (p < 0.05). In conclusion, despite positive changes in some aspects of quality of life, rTMS did not enhance the swallowing function when compared conventional dysphagia rehabilitation. Therefore, the application of 1 Hz rTMS should be reconsidered to improve swallowing function in the chronic period.

Swallowing therapy for dysphagia in acute and subacute stroke

BACKGROUND

Dysphagia (swallowing problems), which is common after stroke, is associated with increased risk of death or dependency, occurrence of pneumonia, poor quality of life, and longer hospital stay. Treatments provided to improve dysphagia are aimed at accelerating recovery of swallowing function and reducing these risks. This is an update of the review first published in 1999 and updated in 2012.

OBJECTIVES

To assess the effects of swallowing therapy on death or dependency among stroke survivors with dysphagia within six months of stroke onset.

SEARCH METHODS

We searched the Cochrane Stroke Group Trials Register (26 June 2018), the Cochrane Central Register of Controlled Trials (CENTRAL; 2018, Issue 6) in the Cochrane Library (searched 26 June 2018), MEDLINE (26 June 2018), Embase (26 June 2018), the Cumulative Index to Nursing and Allied Health Literature (CINAHL) (26 June 2018), Web of Science Core Collection (26 June 2018), SpeechBITE (28 June 2016), ClinicalTrials.Gov (26 June 2018), and the World Health Organization International Clinical Trials Registry Platform (26 June 2018). We also searched Google Scholar (7 June 2018) and the reference lists of relevant trials and review articles.

SELECTION CRITERIA

We sought to include randomised controlled trials (RCTs) of interventions for people with dysphagia and recent stroke (within six months).

DATA COLLECTION AND ANALYSIS

Two review authors independently applied the inclusion criteria, extracted data, assessed risk of bias, used the GRADE approach to assess the quality of evidence, and resolved disagreements through discussion with the third review author (PB). We used random-effects models to calculate odds ratios (ORs), mean differences (MDs), and standardised mean differences (SMDs), and provided 95% confidence intervals (CIs) for each.The primary outcome was functional outcome, defined as death or dependency (or death or disability), at the end of the trial. Secondary outcomes were case fatality at the end of the trial, length of inpatient stay, proportion of participants with dysphagia at the end of the trial, swallowing ability, penetration aspiration score, or pneumonia, pharyngeal transit time, institutionalisation, and nutrition.

MAIN RESULTS

We added 27 new studies (1777 participants) to this update to include a total of 41 trials (2660 participants).We assessed the efficacy of swallowing therapy overall and in subgroups by type of intervention: acupuncture (11 studies), behavioural interventions (nine studies), drug therapy (three studies), neuromuscular electrical stimulation (NMES; six studies), pharyngeal electrical stimulation (PES; four studies), physical stimulation (three studies), transcranial direct current stimulation (tDCS; two studies), and transcranial magnetic stimulation (TMS; nine studies).Swallowing therapy had no effect on the primary outcome (death or dependency/disability at the end of the trial) based on data from one trial (two data sets) (OR 1.05, 95% CI 0.63 to 1.75; 306 participants; 2 studies; I² = 0%; P = 0.86; moderate-quality evidence). Swallowing therapy had no effect on case fatality at the end of the trial (OR 1.00, 95% CI 0.66 to 1.52; 766 participants; 14 studies; I² = 6%; P = 0.99; moderate-quality evidence). Swallowing therapy probably reduced length of inpatient stay (MD -2.9, 95% CI -5.65 to -0.15; 577 participants; 8 studies; I² = 11%; P = 0.04; moderate-quality evidence). Researchers found no evidence of a subgroup effect based on testing for subgroup differences (P = 0.54). Swallowing therapy may have reduced the proportion of participants with dysphagia at the end of the trial (OR 0.42, 95% CI 0.32 to 0.55; 1487 participants; 23 studies; I² = 0%; P = 0.00001; low-quality evidence). Trial results show no evidence of a subgroup effect based on testing for subgroup differences (P = 0.91). Swallowing therapy may improve swallowing ability (SMD -0.66, 95% CI -1.01 to -0.32; 1173 participants; 26 studies; I² = 86%; P = 0.0002; very low-quality evidence). We found no evidence of a subgroup effect based on testing for subgroup differences (P = 0.09). We noted moderate to substantial heterogeneity between trials for these interventions. Swallowing therapy did not reduce the penetration aspiration score (i.e. it did not reduce radiological aspiration) (SMD -0.37, 95% CI -0.74 to -0.00; 303 participants; 11 studies; I² = 46%; P = 0.05; low-quality evidence). Swallowing therapy may reduce the incidence of chest infection or pneumonia (OR 0.36, 95% CI 0.16 to 0.78; 618 participants; 9 studies; I² = 59%; P = 0.009; very low-quality evidence).

AUTHORS' CONCLUSIONS

Moderate- and low-quality evidence suggests that swallowing therapy did not have a significant effect on the outcomes of death or dependency/disability, case fatality at the end of the trial, or penetration aspiration score. However, swallowing therapy may have reduced length of hospital stay, dysphagia, and chest infections, and may have improved swallowing ability. However, these results are based on evidence of variable quality, involving a variety of interventions. Further high-quality trials are needed to test whether specific interventions are effective.

Repetitive transcranial magnetic stimulation in combination with neuromuscular electrical stimulation for treatment of post-stroke dysphagia

Objective

This study was performed to determine whether repetitive transcranial magnetic stimulation (rTMS) combined with neuromuscular electrical stimulation (NMES) effectively ameliorates dysphagia and how rTMS protocols (bilateral vs. unilateral) combined with NMES can be optimized.

Methods

Sixty-four patients were randomly divided into four groups using a random distribution table: the sham rTMS plus NMES (Sham-rTMS/NMES), ipsilesional 10-Hz rTMS plus NMES (Ipsi-rTMS/NMES), contralesional 1-Hz rTMS plus NMES (Contra-rTMS/NMES), and bilateral rTMS plus NMES (Bi-rTMS/NMES) groups. Cortical excitability as measured by the amplitude of the motor evoked potential at the mylohyoid muscle cortical representative area, swallowing function as measured by the Standardized Swallowing Assessment, and the degree of dysphagia were evaluated at baseline, after the stimulation course, and at the 1-month follow-up.

Results

Bi-rTMS/NMES produced higher cortical excitability and better swallowing function recovery. Compared with NMES alone, unilateral rTMS plus NMES had additional effects on cortical excitability and rehabilitation of dysphagia, but there were no differences between the Contra-rTMS/NMES and Ipsi-rTMS/NMES groups. No adverse events occurred.

Conclusion

The combination of rTMS with NMES was superior to NMES alone in improving the recovery of post-stroke dysphagia, and the combination of bilateral rTMS with NMES was more effective than unilateral rTMS combined with NMES.

Effects of Hand Training During the Aftereffect Period of Low-Frequency rTMS in Subacute Stroke Patients

Objective

To investigate the effects of hand training using low-frequency repetitive transcranial magnetic stimulation (rTMS) within the aftereffect period on hand function in patients with subacute stroke.

Methods

The subacute stroke patients with hand weaknesses were divided randomly into two groups. Patients in the intervention group underwent hand training within the aftereffect period, that is, immediately after receiving low-frequency rTMS treatment. Patients in the control group underwent hand training 2 hours after the low-frequency rTMS treatment. A manual function test (MFT) for ‘grasp and pinch’ and ‘hand activities’; a manual muscle test (MMT) for ‘grasp’, ‘release’, and ‘abductor pollicis brevis (APB)’; and the Modified Ashworth Scale for finger flexion were performed and measured before and immediately after combined therapy as well as 2 weeks after combined therapy.

Results

Thirty-two patients with hand weakness were enrolled in this study. The intervention group patients showed more improvements in grasp MMT and MMT APB tested immediately after combined therapy. However, the changes in all measurements were not significantly different between the two groups 2 weeks after the combined therapy. In both groups, hand functions improved significantly immediately after combined therapy and 2 weeks after combined therapy.

Conclusion

Hand training immediately after low-frequency rTMS showed more rapid improvement in the motor power of hands than hand training conducted 2 hours after low-frequency rTMS. Our results suggest that conducting hand training immediately after low-frequency rTMS could be an improved useful therapeutic option in subacute stroke patients.

Dual Transcranial Direct Current Stimulation for Poststroke Dysphagia: A Randomized Controlled Trial

BACKGROUND

Poststroke dysphagia is associated with considerable morbidity and has high health care cost implications.

OBJECTIVE

To evaluate whether anodal transcranial direct current stimulation (tDCS) over the lesioned hemisphere and cathodal tDCS to the contralateral one during the early stage of rehabilitation can improve poststroke dysphagia.

METHODS

A total of 40 patients referred to our neurorehabilitation department were randomized to receive anodal tDCS over the damaged hemisphere plus cathodal stimulation over the contralateral one versus sham stimulation during swallowing maneuvers over the course of 10 sessions of treatment. Swallowing function was evaluated before and after stimulation using the Dysphagia Outcome and Severity Scale (DOSS).

RESULTS

The percentage of patients who reached various thresholds of improvement was higher in the tDCS group than in the sham group, but the differences were not significant (eg, DOSS score ≥ 20% increase from baseline: 55% in the tDCS group vs 40% in the sham group; P = .53). Among all variables recorded at baseline, only a subgroup of patients without nasogastric tube showed a significantly higher improvement with tDCS treatment versus sham (DOSS score ≥10% and ≥20% from baseline: 64.29% vs 0%, P = .01).

CONCLUSIONS

In patients with poststroke dysphagia, treatment with dual tDCS in the early phase of rehabilitation does not significantly increase the probability of recovery compared with sham stimulation.

Low-frequency rTMS of the unaffected hemisphere in stroke patients: A systematic review

The aim of this review was to summarize the evidence for the effectiveness of low-frequency (LF) repetitive transcranial magnetic stimulation (rTMS) over the unaffected hemisphere in promoting functional recovery after stroke. We performed a systematic search of the studies using LF-rTMS over the contralesional hemisphere in stroke patients and reviewed the 67 identified articles. The studies have been gathered together according to the time interval that had elapsed between the stroke onset and the beginning of the rTMS treatment. Inhibitory rTMS of the contralesional hemisphere can induce beneficial effects on stroke patients with motor impairment, spasticity, aphasia, hemispatial neglect and dysphagia, but the therapeutic clinical significance is unclear. We observed considerable heterogeneity across studies in the stimulation protocols. The use of different patient populations, regardless of lesion site and stroke aetiology, different stimulation parameters and outcome measures means that the studies are not readily comparable, and estimating real effectiveness or reproducibility is very difficult. It seems that careful experimental design is needed and it should consider patient selection aspects, rTMS parameters and clinical assessment tools. Consecutive sessions of rTMS, as well as the combination with conventional rehabilitation therapy, may increase the magnitude and duration of the beneficial effects. In an increasing number of studies, the patients have been enrolled early after stroke. The prolonged follow-up in these patients suggests that the effects of contralesional LF-rTMS can be long-lasting. However, physiological evidence indicating increased synaptic plasticity, and thus, a more favourable outcome, in the early enrolled patients, is still lacking. Carefully designed clinical trials designed are required to address this question. LF rTMS over unaffected hemisphere may have therapeutic utility, but the evidence is still preliminary and the findings need to be confirmed in further randomized controlled trials.

Vagus nerve magnetic modulation facilitates dysphagia recovery in patients with stroke involving the brainstem - A proof of concept study

BACKGROUND & AIMS

Stroke involving the brainstem (SBS) causes severe oropharyngeal dysphagia (OD). Research on the therapeutic efficacy of vagus nerve modulation (VNM) by using repetitive transcranial magnetic stimulation (rTMS) in SBS patients with OD has been limited thus far. We aimed to assess the effect of VNM by using rTMS in improving swallowing function after SBS.

METHOD

We conducted a sham-controlled, double-blinded, parallel pilot study in 28 SBS patients with OD randomly allocated to a real rTMS group (n = 13; TMS_real) or a sham group (n = 15; TMS_sham). For VNM, 5-Hz rTMS was applied to the left mastoid in 10 sessions. We evaluated all patients for swallowing function before and after rTMS conditioning, assessed on the 8-point Penetration-Aspiration Scale (PAS) through videofluoroscopy and the Australian Therapy Outcome Measures-Swallowing scale (AusTOMs). We measured the amplitude and latency of cricopharyngeal motor evoked potentials (CP-MEPs) as the neurophysiological parameters.

RESULTS

TMS_real exhibited significant improvement in all swallowing outcomes-neurophysiological, radiological, and functional-compared with TMS_sham: We noted higher CP-MEP amplitude (p = 0.004), shorter CP-MEP latency (p = 0.004), a lower PAS score (p = 0.001), and a higher AusTOMs score (p < 0.001) following rTMS in TMS_real. Moreover, the neurophysiological improvements were significantly correlated with the functional outcomes (p < 0.05).

CONCLUSIONS

Our results encourage the application of VNM by using rTMS for improving swallowing function after SBS. The immediate therapeutic effects suggest that this novel intervention can be an effective complementary therapy to traditional oropharyngeal rehabilitation.

CLINICAL TRIAL REGISTRATION

URL: https://www.clinicaltrials.gov. Unique identifier: NCT02893033.

Noninvasive brain stimulation for dysphagia after acquired brain injury: a systematic review

The purpose of this study was to review the best available evidence of noninvasive brain stimulation, including repetitive transcranial magnetic stimulation (rTMS) and transcranial direct current stimulation (tDCS) for dysphagia after acquired brain injury. We searched randomized controlled trials that compared noninvasive brain stimulation with control used to improve dysphagia after acquired brain injury. We assessed dysphagia severity rating scales and penetration-aspiration scale as outcomes immediately after intervention. We calculated the pooled estimate of the standardized mean difference (SMD) to combine individual results. We included 8 published studies. Two heterogenous trials of 48 patients showed that rTMS was associated with a significant improvement in the dysphagia severity rating scale score (SMD 2.95). Three homogeneous trials of 88 patients showed a significant effect of rTMS on the penetration-aspiration scale score (SMD 0.77). Two homogeneous trials of 34 patients showed that tDCS was associated with a significant improvement in the dysphagia severity rating scale score (SMD 1.20). The review provided low-quality evidence for the effectiveness of noninvasive brain stimulation in improving dysphagia after acquired brain injury. Further trials of larger sample sizes are needed to determine the most appropriate noninvasive brain stimulation protocol. J. Med. Invest. 63: 153-158, August, 2016.