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

Symmetry differences of structural connectivity in multiple sclerosis and healthy state

Focal and diffuse cerebral damages occur in Multiple Sclerosis (MS) that promotes profound shifts in local and global structural connectivity parameters, mainly derived from diffusion tensor imaging. Most of the reconstruction analyses have applied conventional tracking algorithms largely based on the controversial streamline count. For a more credible explanation of the diffusion MRI signal, we used convex optimization modeling for the microstructure-informed tractography2 (COMMIT2) framework. All multi-shell diffusion data from 40 healthy controls (HCs) and 40 relapsing-remitting MS (RRMS) patients were transformed into COMMIT2-weighted matrices based on the Schefer-200 parcels atlas (7 networks) and 14 bilateral subcortical regions. The success of the classification process between MS and healthy state was efficiently predicted by the left DMN-related structures and visual network-associated pathways. Additionally, the lesion volume and age of onset were remarkably correlated with the components of the left DMN. Using complementary approaches such as global metrics revealed differences in WM microstructural integrity between MS and HCs (efficiency, strength). Our findings demonstrated that the cutting-edge diffusion MRI biomarkers could hold the potential for interpreting brain abnormalities in a more distinctive way.

Non-invasive brain stimulation on clinical symptoms in multiple sclerosis patients: A systematic review and meta-analysis

BACKGROUND

Non-invasive brain stimulation (NIBS) has demonstrated mixed effects on the clinical symptoms of multiple sclerosis. This systematic review and meta-analysis aimed to evaluate the effects of NIBS techniques on the most common symptoms of MS.

METHODS

A literature search was performed until October 2022 which included randomized controlled trials and quasi-experimental studies that used sham-controlled NIBS in patients with MS. We calculated the Hedge's effect sizes of each domain of interest and their 95% confidence intervals (95% CIs) and performed random effects meta-analyses.

RESULTS

A total of 49 studies were included in the systematic review (944 participants). Forty-four eligible studies were included for quantitative analysis, of which 33 applied transcranial direct current stimulation (tDCS), 9 transcranial magnetic stimulation (TMS), and 2 transcranial random noise stimulation (tRNS). We found a significant decrease in fatigue (ES:  - 0.86, 95% CI:  - 1.22 to - 0.51, p < 0.0001), pain (ES: - 1.91, 95% CI, - 3.64 to - 0.19, p=  0.03) and psychiatric symptoms (ES: - 1.44, 95% CI - 2.56 to - 0.32, p = 0.01) in favor of tDCS compared with the sham. On the other hand, there was no strong evidence showing tDCS effectiveness on motor performance and cognition (ES: - 0.03, 95% CI - 0.35 to 0.28, p = 0.83 and ES: 0.71, 95% CI, - 0.09 to 1.52, p = 0.08, respectively). Regarding TMS, we found a significant decrease in fatigue (ES: - 0.45, 95% CI: - 0.84 to -0.07, p = 0.02) and spasticity levels (ES: - 1.11, 95% CI: - 1.48 to - 0.75, p < 0.00001) compared to the sham. However, there was no strong evidence of the effectiveness of TMS on motor performance (ES: - 0.39, 95% CI - 0.95 to 0.16, p = 0.16). Finally, there was no significant evidence showing the effectiveness of tRNS on fatigue levels (ES: - 0.28, 95% CI: - 1.02 to 0.47, p = 0.46) and cognitive improvement (ES: - 0.04, 95% CI: - 0.6, 0.52, p = 0.88) compared with the sham.

CONCLUSIONS

Overall, most studies have investigated the effects of tDCS on MS symptoms, particularly fatigue. The symptom that most benefited from NIBS was fatigue, while the least to benefit was motor performance. In addition, we found that disability score was associated with fatigue improvement. Thus, these findings support the idea that NIBS could have some promising effects on specific MS symptoms. It is also important to underscore that studies are very heterogeneous regarding the parameters of stimulation, and this may also have influenced the effects on some specific behavioral domains.

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.

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/ ).

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

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

Pharyngeal electrical stimulation in amyotrophic lateral sclerosis: a pilot study

Background:

Patients with amyotrophic lateral sclerosis (ALS) suffer from dysphagia that increases the risk for aspiration, pneumonia and weight loss. Pharyngeal electrical stimulation (PES) is a therapeutic technique that applies electric stimuli to the patient’s pharynx in order to improve swallowing based on the principle of cortical plasticity and reorganization. Previous studies have demonstrated positive effects in patients with various neurological diseases.

Objective:

This study was initiated to investigate the effect of PES on swallowing function in patients with ALS.

Methods:

In all, 20 ALS patients with severe dysphagia [characterized by a Penetration Aspiration Scale (PAS) of at least 4 in thin liquid] were randomized to receive either PES for 10 min at 3 consecutive days in addition to Standard Logopaedic Therapy (SLT) or SLT alone. Swallowing function was evaluated by Fiberoptic Endoscopic Evaluation of Swallowing (FEES) at five timepoints: at baseline, 1 day, 4 days, 3 weeks and 3 months after treatment. Primary endpoint was the severity of penetrations or aspirations as classified by PAS. Secondary endpoints were adverse events, dysphagia-related quality of life, Swallowing Quality of Life (SWAL-QOL), Dysphagia Severity Rating Scale (DSRS), residues, leaking, ALS Functional Rating Scale Revised (ALSFRS-R), and the performance in Clinical Evaluation of Swallowing (CES). The trial is registered under the name of ‘Pharyngeal Electrical Stimulation in Amyotrophic Lateral Sclerosis’ with ClinialTrials.gov, number NCT03481348 (https://clinicaltrials.gov/ct2/show/NCT03481348).

Results:

Both groups combined showed a significant improvement (p = 0.003) of median Total-PAS from 3.6 [interquartile range (IQR) = 2.9–5.0] at baseline to 2.3 (IQR = 1.8–4.0) 1 day after treatment. During subsequent study visits, PAS increased again but remained below baseline. PES and control group did not differ significantly 1 day after intervention (p = 0.32). Similar effects were found in the majority of secondary endpoints.

Interpretation:

The findings suggest that PES may not provide an additional positive effect on swallowing function in ALS. SLT seems to yield at least short-term positive effects on swallowing function and swallowing-specific life quality in ALS.

Registration: ClinialTrials.gov: NCT03481348

Multiple sclerosis: Inflammation, autoimmunity and plasticity

In recent years, experimental studies have clarified that immune system influences the functioning of the central nervous system (CNS) in both physiologic and pathologic conditions. The neuro-immune crosstalk plays a crucial role in neuronal development and may be critically involved in mediating CNS response to neuronal damage. Multiple sclerosis (MS) represents a good model to investigate how the immune system regulates neuronal activity. Accordingly, a growing body of evidence has demonstrated that increased levels of pro-inflammatory mediators may significantly impact synaptic mechanisms, influencing overall neuronal excitability and synaptic plasticity expression. In this chapter, we provide an overview of preclinical data and clinical studies exploring synaptic functioning noninvasively with transcranial magnetic stimulation (TMS) in patients with MS. Moreover, we examine how inflammation-driven synaptic dysfunction could affect synaptic plasticity expression, negatively influencing the MS course. Contrasting CSF inflammation together with pharmacologic enhancement of synaptic plasticity and application of noninvasive brain stimulation, alone or in combination with rehabilitative treatments, could improve the clinical compensation and prevent the accumulating deterioration in MS.

Research on Influencing Factors of Clinical Efficacy of Meniscus Resection Based on Logistic Regression Analysis

In order to solve the factors affecting the clinical efficacy of meniscus resection, a method based on logistic regression analysis is proposed. From May 2019 to May 2020, 60 patients with discoid meniscus who underwent arthroscopic surgery in the Joint Department of the Second Hospital of a certain city were selected as the research objects; the surgical methods are divided into partial meniscus excision and plasty and total meniscus resection. The Lysholm function score was used to evaluate the clinical efficacy of arthroscopic surgery for discoid meniscus injuries before and 3, 6, and 12 months after surgery and postoperative application of Ikeuchi score and Tegner exercise ability score to assess age, gender, body mass index (BMI), duration of symptoms, and the influence of meniscus injury types and surgical methods on the efficacy of arthroscopic surgery for discoid meniscus injuries. Experimental results show that Ikeuchi's assessment of the excellent and good rate of arthroscopic knee joints was significantly higher than that of the control group, the incidence of postoperative pain was significantly lower than that of the control group, and the difference was statistically significant (P < 0.05). Postoperative pain and premature weight-bearing of discoid meniscus injury of knee joint, factors such as noncold compress after operation, articular cartilage damage, age, and time from onset to operation are closely related; the difference was statistically significant (P < 0.05). Postoperative evaluation according to Ikeuchi score: excellent in 38 cases, good in 14 cases, 8 cases were poor, and the excellent and good rate was 86.7%. The patient's age, type of meniscus tear, and duration of symptoms have a certain impact on the postoperative clinical efficacy of discoid meniscus injury; BMI and surgical methods have no significant impact. Logistic regression analysis results show that postoperative pain and premature weight-bearing of discoid meniscus injury of the knee joint, no cold compress after operation, accompanied by articular cartilage damage, age, and factors such as onset to operation time are closely related; the difference was statistically significant (P < 0.05). It proves that arthroscopic surgery for discoid meniscus injury has the advantages of less damage and faster recovery, it is the first choice for the treatment of discoid meniscus injury, and the postoperative effect is significant in young patients and those with short duration of symptoms; mixed tears have a greater impact on the postoperative recovery of patients with discoid meniscus injury; therefore, patients with discoid meniscus injury should undergo surgery as soon as possible and perform active rehabilitation exercises after the operation.

Efficacy of transcranial direct current stimulation in people with multiple sclerosis: a review

BACKGROUND AND PURPOSE

Multiple sclerosis (MS) is a chronic inflammatory disease causing a wide range of symptoms including motor and cognitive impairment, fatigue and pain. Over the last two decades, non-invasive brain stimulation, especially transcranial direct current stimulation (tDCS), has increasingly been used to modulate brain function in various physiological and pathological conditions. However, its experimental applications for people with MS were noted only as recently as 2010 and have been growing since then. The efficacy for use in people with MS remains questionable with the results of existing studies being largely conflicting. Hence, the aim of this review is to paint a picture of the current state of tDCS in MS research grounded on studies applying tDCS that have been done to date.

METHODS

A keyword search was performed to retrieve articles from the earliest article identified until 14 February 2021 using a combination of the groups (1) 'multiple sclerosis', 'MS' and 'encephalomyelitis' and (2) 'tDCS' and 'transcranial direct current stimulation'.

RESULTS

The analysis of the 30 articles included in this review underlined inconsistent effects of tDCS on the motor symptoms of MS based on small sample sizes. However, tDCS showed promising benefits in ameliorating fatigue, pain and cognitive symptoms.

CONCLUSION

Transcranial direct current stimulation is attractive as a non-drug approach in ameliorating MS symptoms, where other treatment options remain limited. The development of protocols tailored to the individual's own neuroanatomy using high definition tDCS and the introduction of network mapping in the experimental designs might help to overcome the variability between studies.

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.

Diagnosis and treatment of neurogenic dysphagia - S1 guideline of the German Society of Neurology

Introduction

Neurogenic dysphagia defines swallowing disorders caused by diseases of the central and peripheral nervous system, neuromuscular transmission, or muscles. Neurogenic dysphagia is one of the most common and at the same time most dangerous symptoms of many neurological diseases. Its most important sequelae include aspiration pneumonia, malnutrition and dehydration, and affected patients more often require long-term care and are exposed to an increased mortality. Based on a systematic pubmed research of related original papers, review articles, international guidelines and surveys about the diagnostics and treatment of neurogenic dysphagia, a consensus process was initiated, which included dysphagia experts from 27 medical societies.

Recommendations

This guideline consists of 53 recommendations covering in its first part the whole diagnostic spectrum from the dysphagia specific medical history, initial dysphagia screening and clinical assessment, to more refined instrumental procedures, such as flexible endoscopic evaluation of swallowing, the videofluoroscopic swallowing study and high-resolution manometry. In addition, specific clinical scenarios are captured, among others the management of patients with nasogastric and tracheotomy tubes. The second part of this guideline is dedicated to the treatment of neurogenic dysphagia. Apart from dietary interventions and behavioral swallowing treatment, interventions to improve oral hygiene, pharmacological treatment options, different modalities of neurostimulation as well as minimally invasive and surgical therapies are dealt with.

Conclusions

The diagnosis and treatment of neurogenic dysphagia is challenging and requires a joined effort of different medical professions. While the evidence supporting the implementation of dysphagia screening is rather convincing, further trials are needed to improve the quality of evidence for more refined methods of dysphagia diagnostics and, in particular, the different treatment options of neurogenic dysphagia. The present article is an abridged and translated version of the guideline recently published online (https://www.awmf.org/uploads/tx_szleitlinien/030-111l_Neurogene-Dysphagie_2020-05.pdf).

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.

Anodal transcranial direct current stimulation and intermittent theta-burst stimulation improve deglutition and swallowing reproducibility in elderly patients with dysphagia

BACKGROUND

Dysphagia in the elderly, known as presbydysphagia, has become a relevant public health problem in several countries. Swallowing disorders may be a consequence of different neurological disorders (secondary presbydysphagia) or the expression of the aging process itself (primary presbydysphagia). We aimed to test the therapeutic potential of two different non-invasive brain stimulation (NIBS) techniques in subjects with primary or secondary presbydysphagia.

METHODS

A blinded randomized controlled trial with crossover design was carried out in 42 patients, randomly assigned to anodal transcranial direct current stimulation (tDCS) or intermittent theta-burst stimulation (TBS) group. Both tDCS and TBS were applied for 5 consecutive days over the right swallowing motor cortex. The swallowing function was assessed before and 1 and 3 months after the stimulation using the Dysphagia Outcome and Severity Scale (DOSS), scored based on clinical assessment and fiberoptic endoscopic evaluation of swallowing. An electrophysiological method was also applied to evaluate changes in the reproducibility of the swallowing behavior.

KEY RESULTS

Both real tDCS and TBS had beneficial effects on the swallowing function in patients with primary and secondary presbydysphagia. Anodal tDCS resulted in an improvement of 0.5 points in DOSS at 1-month follow-up (P = .014), whereas intermittent TBS induced an increase of 0.7 and 0.6 points at 1- and 3-month follow-up evaluations, respectively (P = .0001 and P = .005, respectively). Reproducibility of both the oral and pharyngeal phases of swallowing significantly increased at 1-month follow-up.

CONCLUSIONS AND INFERENCES

Our results suggest that non-invasive cortical stimulation may be useful for dysphagia recovery in elderly patients.