Randomized trial of transcranial direct current stimulation for poststroke dysphagia

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

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

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.

Interventions for oropharyngeal dysphagia in acute and critical care: a systematic review and meta-analysis

PURPOSE

To determine the effectiveness of dysphagia interventions compared to standard care in improving oral intake and reducing aspiration for adults in acute and critical care.

METHODS

We searched electronic literature for randomised and quasi-randomised trials and bibliography lists of included studies to March 2020. Study screening, data extraction, risk of bias and quality assessments were conducted independently by two reviewers. Meta-analysis used fixed effects modelling. The systematic review protocol is registered and published.

RESULTS

We identified 22 studies (19 stroke, 2 intensive care stroke and 1 general intensive care) testing 9 interventions and representing 1700 patients. Swallowing treatment showed no evidence of a difference in the time to return to oral intake (n = 33, MD (days) - 4.5, 95% CI - 10.6 to 1.6, 1 study, P = 0.15) (very low certainty) or in aspiration following treatment (n = 113, RR 0.79, 95% CI 0.44 to 1.45, 4 studies, I² = 0%, P = 0.45) (low certainty). Swallowing treatment showed evidence of a reduced risk of pneumonia (n = 719, RR 0.71, 95% CI 0.56 to 0.89, 8 studies, I² = 15%, P = 0.004) (low certainty) but no evidence of a difference in swallowing quality of life scores (n = 239, MD - 11.38, 95% CI - 23.83 to 1.08, I ² = 78%, P = 0.07) (very low certainty).

CONCLUSION

There is limited evidence for the effectiveness of swallowing treatments in the acute and critical care setting. Clinical trials consistently measuring patient-centred outcomes are needed.

The effect of transcranial direct current stimulation of pharyngeal motor cortex on swallowing function in patients with chronic dysphagia after stroke: A retrospective cohort study

About 11% to 13% of patients with acute dysphagia induced by stroke remain chronic dysphagia 6 months after stroke which usually leads to many severe complications and poor quality of life.To investigate the effect of transcranial direct current stimulation (tDCS) on swallowing function in the patients with chronic dysphagia after stroke.26 post-stroke patients with chronic dysphagia who received tDCS were identified by electronic medical records between July 2016 and April 2018. Of which, 13 were treated by unilateral hemispheric anodal tDCS at affected pharyngeal motor cortex. 13 eligible patients only treated by conventional therapies but without tDCS were randomly selected by matching on date of admission (±2 weeks) of the patients receiving unilateral tDCS. The swallowing function and quality of life were evaluated before and 2 weeks after treatment.The patients in three groups were comparable. The swallowing function and quality of life of the patients in all the 3 groups had been improved over time. Comparing to the group without tDCS, both the groups with unilateral or bilateral tDCS had shorter oral transit time (1.69 ± 0.95, 0.97 ± 0.71 seconds, respectively) and higher scores of quality of life (159.76 ± 12.59, 179.69 ± 11.81, respectively) after treatment.Both unilateral and bilateral hemispheric anodal tDCS combined with conventional therapies are helpful for recovery of swallowing function in patients with chronic dysphagia induced by stroke, but bilateral anodal tDCS substantially improve more.

Translating concepts of neural repair after stroke: Structural and functional targets for recovery

Stroke is among the most common causes of adult disability worldwide, and its disease burden is shifting towards that of a long-term condition. Therefore, the development of approaches to enhance recovery and augment neural repair after stroke will be critical. Recovery after stroke involves complex interrelated systems of neural repair. There are changes in both structure (at the molecular, cellular, and tissue levels) and function (in terms of excitability, cortical maps, and networks) that occur spontaneously within the brain. Several approaches to augment neural repair through enhancing these changes are under study. These include identifying novel drug targets, implementing rehabilitation strategies, and developing new neurotechnologies. Each of these approaches has its own array of different proposed mechanisms. Current investigation has emphasized both cellular and circuit-based targets in both gray and white matter, including axon sprouting, dendritic branching, neurogenesis, axon preservation, remyelination, blood brain barrier integrity, blockade of extracellular inhibitory signals, alteration of excitability, and promotion of new brain cortical maps and networks. Herein, we review for clinicians recovery after stroke, basic elements of spontaneous neural repair, and ongoing work to augment neural repair. Future study requires alignment of basic, translational, and clinical research. The field continues to grow while becoming more clearly defined. As thrombolysis changed stroke care in the 1990 s and thrombectomy in the 2010 s, the augmentation of neural repair and recovery after stroke may revolutionize care for these patients in the coming decade.

Randomized controlled trial of TDCS on cognition in 201 seniors with mild neurocognitive disorder

OBJECTIVE

To examine the efficacy and safety of combined transcranial direct current stimulation (tDCS) and working memory training (WMT) in enhancing the cognitive functions for individuals with mild neurocognitive disorder due to AD (NCD-AD).

METHODS

In this double-blind, sham-controlled randomized clinical trial (RCT), 201 patients with NCD-AD were randomly assigned for a 4-week intervention of either a combination of tDCS and WMT, sham tDCS and WMT, or tDCS and control cognitive training (CCT). Global cognition and domain-specific cognitive function were assessed before and after the intervention with Alzheimer's disease assessment scale-cognitive subscale (ADAS-Cog), category verbal fluency test, logical memory, digit, and visual span tests.

RESULTS

Study participants did not show intervention group differences in baseline demographics, or cognitive characteristics (ANOVA). Cognitive enhancement was found across three groups after 4 weeks intervention. Combined tDCS-WMT group showed significantly greater improvement compared with single-modality groups in delayed recall (P = 0.043, η²  = 0.036) and working memory capacity (P = 0.04, η²  = 0.038) at 4th week, and logical memory at 12th week (P = 0.042, η²  = 0.037). Adverse events, including skin lesions (2.2%), were similar between groups.

INTERPRETATION

tDCS or WMT could be a safe, feasible, and effective intervention for individuals with NCD-AD. A combination of tDCS and WMT presents greater cognitive enhancement, which may highlight the potential synergistic effects of combined modality intervention on cognition.

Effects of oral neuromuscular training on swallowing dysfunction among older people in intermediate care-a cluster randomised, controlled trial

OBJECTIVES

this prospective, cluster randomised, controlled trial investigated the effect of oral neuromuscular training among older people in intermediate care with impaired swallowing.

METHODS

older people (≥65 years) with swallowing dysfunction were cluster randomised according to care units for 5 weeks of neuromuscular training of the orofacial and pharyngeal muscles or usual care. The primary endpoint was the change in swallowing rate (assessed with a timed water swallow test) from baseline to the end-of-treatment and 6 months post-treatment. The secondary endpoints were changes in signs of aspiration during the water swallow test, and swallowing-related quality of life (QOL). An intention-to-treat principle was followed, and mixed-effects models were used for data analysis with the clustered study design as a random factor.

RESULTS

in total, 385 participants from 36 intermediate care units were screened, and 116 participants were randomly assigned to oral neuromuscular training (intervention; n = 49) or usual care (controls; n = 67). At the end of treatment, the geometric mean of the swallowing rate in the intervention group had significantly improved 60% more than that of controls (P = 0.007). At 6 months post-treatment, the swallowing rate of the intervention group remained significantly better (P = 0.031). Signs of aspiration also significantly reduced in the intervention group compared with controls (P = 0.01). No significant between-group differences were found for swallowing-related QOL.

CONCLUSIONS

oral neuromuscular training is a new promising swallowing rehabilitation method among older people in intermediate care with impaired swallowing.

TRIAL REGISTRATION

ClinicalTrials.gov: NCT02825927.

A pilot study on the efficacy of transcranial direct current stimulation applied to the pharyngeal motor cortex for dysphagia associated with brainstem involvement in multiple sclerosis

OBJECTIVE

we investigated the effect of anodal transcranial direct current stimulation (tDCS) applied over the pharyngeal motor area in dysphagia associated with multiple sclerosis (MS).

METHODS

Eighteen MS patients with dysphagia associated with brainstem involvement were randomized to receive either "real" or "sham" tDCS.

PRIMARY OUTCOME

The Penetration/Aspiration Scale (PAS).

SECONDARY OUTCOMES

changes in electromyographic (EMG) parameters and pharyngeal cortical motor evoked potentials (MEPs). Patients were evaluated at baseline (T₀), at the end of 5-session cycle of tDCS stimulations (T₁), after two (T₂), and four (T₃) weeks.

RESULTS

the PAS values were significantly lower in the active group than in "sham" group at T₁, and at T₃. Over the post-stimulation periods, PAS significantly improved only in the "real" group. As regards the secondary outcomes, we observed a statistically significant difference between the 2 groups only in the MEPs amplitude at T₁. The comparison between baseline and each of the post-stimulation times showed significant differences only of the "real" group across all the secondary parameters.

CONCLUSIONS

Our findings support a beneficial effect of anodal tDCS applied to the pharyngeal motor cortex in MS-associated dysphagia.

SIGNIFICANCE

Considering its safety and efficacy, tDCS may represent an important resource in MS-associated dysphagia.

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.