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.

The neurorehabilitation of post-stroke dysphagia: Physiology and pathophysiology.

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

The relationships between sarcopenia, frailty, bioelectrical impedance analysis, and anthropometry in patients with type two intestinal failure.

INTRODUCTION: SARC-F (Strength, Assistance in walking, Rise from a chair, Climb stairs and Falls) is a validated screening questionnaire for rapidly assessing sarcopenia in older adults with a variety of diseases while the Rockwood clinical frailty scale (RCFS) is a commonly used tool for assessing frailty in older adults. However, there are no data regarding the use of these tools in patients with type two intestinal failure (T2IF). We aimed to compare SARC-F and RCFS to bioelectrical impedance analysis (BIA) and anthropometry in patients with T2IF. METHODS: In this cross-sectional study, patients with T2IF admitted to a national U.K. reference centre had SARC-F, RCFS, BIA and anthropometry performed. A SARC-F score ≥4 indicated potential sarcopenia while a RCFS ≥5 indicated frailty. Statistical analyses were conducted to assess correlation, concordance and differences between measurements. RESULTS: The study comprised 76 patients, of whom 59.2 % were female, with a mean age of 56.5 years ± 16. Seventy percent of patients had short bowel syndrome as an underlying cause of IF. Thirty eight percent of patients had a SARC-F ≥4 and 20 % had a RCFS ≥5. SARC-F was correlated with RCFS (rs 0.43, p < 0.001), phase angle (PA) (rs -0.55, p < 0.001) and hand grip strength (HGS) (rs -0.34, p 0.004). RCFS was correlated with HGS (rs -0.31, p 0.009). Significant differences emerged between PA (p 0.002) and HGS (p 0.003) values in patients with SARC-F scores ≥4 and < 4 and with HGS for patients with RCFS ≥5 and < 5 (p 0.01). Patients with SARC-F scores ≥4 had longer lengths of stays than those with scores <4 (p 0.002). Compared to PA and HGS, SARC-F had sensitivities of 39 % and 37 % and specificities of 92 % and 73 % respectively. CONCLUSION: We demonstrated SARC-F is correlated with PA and HGS with comparable sensitivity and specificity to its original use in older individuals. There is a role for SARC-F as a means of rapidly assessing muscle quality and function in hospitalised patients with IF with RCFS providing some useful information about muscle function.

The consequences of limited training in disorders of gut-brain interaction: Results from a national survey of gastroenterology trainees in the United Kingdom.

BACKGROUND: Despite their high prevalence and burden, disorders of gut-brain interaction (DGBI) are undertaught and underrepresented in medical curricula. We evaluated the exposure of UK gastroenterology trainees to DGBI and their comfort managing these conditions. METHODS: An electronic survey was distributed to trainees via UK training program directors. The survey included questions on stage of training; subspecialty interest; access to DGBI training opportunities, and comfort levels with DGBI diagnosis and management. Responses were compared between junior and senior trainees, by subspecialty interest (luminal and non-luminal), by geographical region, and training program size. KEY RESULTS: One hundred twelve trainees from across the UK participated (21.4% of national training post holders). Exposure to DGBI lectures (32.8% junior vs. 73.3% senior trainees, p = 0.00003) and clinics (9.0% junior vs. 42.2% senior trainees, p = 0.00003), increased with seniority. Regardless of seniority, most trainees were rarely comfortable making a DGBI diagnosis (39.5% senior vs. 33.9% junior trainees, p = 0.69), and were not comfortable initiating neuromodulators (50% senior vs. 25.8% junior trainees, p = 0.08). Trainees without a luminal subspecialty interest (50%) accessed fewer DGBI clinics (p = 0.04), had less communication skills training (p = 0.04) and were less likely to have been observed during DGBI consultations (p = 0.002). Responses were similar across UK regions and did not differ between smaller and larger programs. CONCLUSIONS & INFERENCES: DGBI training opportunities are limited in UK gastroenterology training across training grades. Most trainees lack confidence with DGBI diagnosis and management. Urgent interventions need to be targeted at all stages of training to ensure DGBI competencies for future gastroenterologists and improve patient outcomes.

The Role of the Cerebellum in Swallowing.

Swallowing is a complex activity requiring a sophisticated system of neurological control from neurones within the brainstem, cerebral cortices and cerebellum. The cerebellum is a critical part of the brain responsible for the modulation of movements. It receives input from motor cortical and sensory areas and fine tunes these inputs to produce coordinated motor outputs. With respect to swallowing, numerous functional imaging studies have demonstrated increased activity in the cerebellum during the task of swallowing and damage to the cerebellum following differing pathological processes is associated with dysphagia. Single pulses of transcranial magnetic stimulation (TMS) have been applied to the cerebellum and have been shown to evoke motor responses in the pharynx. Moreover, repetitive TMS (rTMS) over the cerebellum can modulate cerebral motor (pharyngeal) cortical activity. Neurostimulation has allowed a better understanding of the connections that exist between the cerebellum and cerebral swallowing motor areas in health and provides a potential treatment for neurogenic dysphagia in illness. In this review we will examine what is currently known about the role of the cerebellum in the control of swallowing, explore new findings from neurostimulatory and imaging studies and provide an overview of the future clinical applications of cerebellar stimulation for treating dysphagia.

Dysphagia treatments in Parkinson's disease: A systematic review and meta-analysis.

BACKGROUND: The majority of patients with Parkinson's disease (PD) develop oropharyngeal dysphagia during the course of their disease. However, the efficacy of dysphagia treatments for these patients remains controversial. Therefore, we conducted this systematic review and meta-analysis to evaluate treatment efficacy based on the evidence from randomized controlled trials (RCTs). METHODS: Five electronic databases were systematically searched from inception date to April 2022. Two reviewers independently extracted and analyzed the data. The outcome measures were changes in swallowing-related characteristics based on instrumental swallowing assessments. KEY RESULTS: An initial search identified 187 RCT studies of relevance. After screening, nine studies with a total sample size of 286 were included in the meta-analysis. The pooled effect size for all dysphagia treatments compared with control comparators was significant and medium (SMD [95% CI] = 0.58 [0.22, 0.94], p = 0.001; I2  = 50%). Subgroup analysis revealed a significant and medium pooled effect size for stimulation treatments (brain stimulation, peripheral neurostimulation and acupuncture) (SMD [95% CI] = 0.54 [0.15, 0.92]; p = 0.006; I2  = 22%). Specifically, the effect sizes for the single RCTs on neuromuscular stimulation (SMD [95% CI] = 1.58 [0.49, 2.86]; p = 0.005) and acupuncture (SMD [95% CI] = 0.82 [0.27, 1.37]; p = 0.003) were significant and large. CONCLUSIONS AND INFERENCES: Our results showed that overall, dysphagia treatments, particularly stimulation treatments, can potentially benefit PD patients. However, given the limited number of small RCTs for each type of treatment, the evidence remains weak and uncertain. Further large-scale, multicenter RCTs are warranted to fully explore their clinical efficacy in the PD population.

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.

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.

Experience and clinical efficacy of gut-directed hypnotherapy in an Asian population with refractory irritable bowel syndrome.

Background and Aim: Recent studies have highlighted the high worldwide prevalence of irritable bowel syndrome (IBS) and disparities in its management between ethnic groups. For instance, gut-directed hypnotherapy (GDH), one of the most effective evidence-based treatments for IBS, is not recommended in Asian countries partly due to lack of population-specific outcome data. In this context, we evaluated the outcomes of GDH in an Asian population. Methods: Consecutive British Asian patients with refractory IBS who received 12-sessions of GDH using the Manchester protocol were included. Patients were treated by a team including a therapist able to speak several Asian languages. All patients prospectively completed the following questionnaires before and after GDH: IBS symptom severity score (IBS-SSS), hospital anxiety and depression scale (HADS), non-colonic symptom score, and the quality-of-life (QOL) score. The primary outcome measure was response to GDH defined by ≥50-point reduction in IBS-SSS. Pre- and post-treatment data were compared statistically. Results: Forty-four Asian patients with IBS (age 49 ± 13 years; 29 [66%] female; baseline IBS-SSS: 332.8 ± 94.6) completed GDH. Overall, 37 of 44 (84%) achieved a ≥50-point reduction in IBS-SSS and 25 of 44 (57%) achieved ≥30% reduction in abdominal pain scores. Following GDH, there were also significant mean improvements in IBS-SSS (-132.1, P < 0.0001), non-colonic symptom score (P < 0.0001), QOL score (P < 0.0001), HADS-anxiety (P < 0.0001), and HADS-depression (P < 0.0001), compared with baseline. Conclusion: Regardless of the ethnicity of the therapist, GDH was highly effective with similar response rates to outcomes in other IBS populations, supporting the development of GDH in Asian countries.

A feasibility pilot study of the effects of neurostimulation on swallowing function in Parkinson's Disease [version 2; peer review: 1 approved, 3 approved with reservations, 1 not approved].

Introduction: Dysphagia often occurs during Parkinson's disease (PD) and can have severe consequences. Recently, neuromodulatory techniques have been used to treat neurogenic dysphagia. Here we aimed to compare the neurophysiological and swallowing effects of three different types of neurostimulation, 5 Hertz (Hz) repetitive transcranial magnetic stimulation (rTMS), 1 Hz rTMS and pharyngeal electrical stimulation (PES) in patients with PD. Method: 12 PD patients with dysphagia were randomised to receive either 5 Hz rTMS, 1 Hz rTMS, or PES. In a cross-over design, patients were assigned to one intervention and received both real and sham stimulation. Patients received a baseline videofluoroscopic (VFS) assessment of their swallowing, enabling penetration aspiration scores (PAS) to be calculated for: thin fluids, paste, solids and cup drinking. Swallowing timing measurements were also performed on thin fluid swallows only. They then had baseline recordings of motor evoked potentials (MEPs) from both pharyngeal and (as a control) abductor pollicis brevis (APB) cortical areas using single-pulse TMS. Subsequently, the intervention was administered and post interventional TMS recordings were taken at 0 and 30 minutes followed by a repeat VFS within 60 minutes of intervention. Results: All interventions were well tolerated. Due to lower than expected recruitment, statistical analysis of the data was not undertaken. However, with respect to PAS swallowing timings and MEP amplitudes, there was small but visible difference in the outcomes between active and sham. Conclusion: PES, 5 Hz rTMS and 1 Hz rTMS are tolerable interventions in PD related dysphagia. Due to small patient numbers no definitive conclusions could be drawn from the data with respect to individual interventions improving swallowing function and comparative effectiveness between interventions. Larger future studies are needed to further explore the efficacy of these neuromodulatory treatments in Parkinson's Disease associated dysphagia.

Effects of pharmacological agents for neurogenic oropharyngeal dysphagia: A systematic review and meta-analysis.

BACKGROUND: This systematic review and meta-analysis aimed to evaluate the effects of pharmacological agents for neurogenic oropharyngeal dysphagia based on evidence from randomized controlled trials (RCTs). METHODS: Electronic databases were systematically searched between January 1970 and March 2021. Two reviewers independently extracted and synthesized the data. The outcome measure was changed in (any) relevant clinical swallowing-related characteristics. KEY RESULTS: Data from 2186 dysphagic patients were collected from 14 RCT studies across a range of pharmacotherapies. The pooled effect size of transient receptor potential (TRP) channel agonists was large compared to placebo interventions (SMD[95%CI] =1.27[0.74,1.80], p < 0.001; I2  = 79%). Data were limited for other pharmacological agents and the overall pooled effect size of these agents was non-significant (SMD [95% CI] =0.25 [-0.24, 0.73]; p = 0.31; I2  = 85%). When analyzed separately, large effect sizes were observed with Nifedipine (SMD[95%CI] =1.13[0.09,2.18]; p = 0.03) and Metoclopramide (SMD[95%CI] =1.68[1.08,2.27]; p < 0.001). By contrast, the effects of angiotensin-converting enzyme (ACE) inhibitors (SMD[95%CI] = -0.67[-2.32,0.99]; p = 0.43; I2  = 61%), Physostigmine (SMD[95%CI] = -0.05[-1.03,0.93]; p = 0.92) and Glyceryl Trinitrate (GTN) (SMD [95% CI] = -0.01 [-0.11, 0.08]; p = 0.78) were non-significant. Within stroke patients, subgroup analysis showed that TRP channel agonists had a moderate pooled effect size (SMD[95%CI] =0.74[0.10,1.39]; p = 0.02; I2  = 82%) whereas the effects of other agents were non-significant (SMD[95%CI] =0.40[-0.04,0.84]; p = 0.07; I2  = 87%). CONCLUSIONS & INFERENCES: Our results showed that TRP channel agonists, Nifedipine and Metoclopromide may be beneficial for neurogenic dysphagic patients. Large scale, multicenter clinical trials are warranted to fully explore their therapeutic effects on swallowing.

A systematic review and meta-analysis of the effects of intraoral treatments for neurogenic oropharyngeal dysphagia.

BACKGROUND: Rehabilitative treatments for oropharyngeal dysphagia, including oromotor exercises and sensory stimulation, have been widely adopted into clinical practice. However, the effects of these treatments are mainly supported by exploratory studies. As such, their clinical efficacy remains uncertain. OBJECTIVE: Our systematic review and meta-analysis aimed to evaluate the efficacy of intraoral treatments for neurogenic oropharyngeal dysphagia based on evidence from randomised controlled trials (RCTs). METHODS: Six electronic databases were systematically searched between January 1970 and July 2021. Data were extracted and analysed by two independent reviewers. The outcome measure was changes in (any) relevant clinical swallowing-related characteristics. RESULTS: Data from 285 dysphagic patients were collected from 8 RCT studies across a range of intraoral dysphagia treatments. The pooled effect size of all intraoral dysphagia treatments was non-significant compared to control comparators (SMD [95%CI] = 0.23 [-0.22, 0.69], p = .31; I2  = 73%). Subgroup analysis revealed that the pooled effect sizes were also non-significant for oromotor exercises (device-facilitated lip resistance exercises and tongue exercises) (SMD [95%CI] = 0.11 [-0.76, 0.97]; p = .81; I2  = 88%) and sensory stimulation (thermal-tactile, thermo-chemical and electrical stimulation) (SMD [95%CI] = 0.35 [-0.03, 0.72]; p = .07; I2  = 0%). CONCLUSIONS: Our results showed that overall, intraoral dysphagia treatments, including oromotor exercises and sensory stimulation, do not show beneficial effects for neurogenic oropharyngeal dysphagia. The evidence for these treatments remains weak and currently inadequate to support clinical use. Large-scale, multi-centre RCTs are warranted to fully explore their clinical efficacy.

Exploring parameters of gamma transcranial alternating current stimulation (tACS) and full-spectrum transcranial random noise stimulation (tRNS) on human pharyngeal cortical excitability.

BACKGROUND: Transcranial alternating current stimulation (tACS) and transcranial random noise stimulation (tRNS) have been shown to have physiological and functional effects on brain excitability and motor behavior. Yet, little is known about their effects in the swallowing system. AIM: To examine the effects and optimal stimulation parameters of tACS and tRNS for modulating excitability of human pharyngeal motor cortex. METHODS: 10 Hz (alpha), 20 Hz (beta), 70 Hz (gamma) tACS, 0.1-640 Hz (full-spectrum) tRNS, and sham were applied over pharyngeal motor cortices at 1.5 mA current intensity for 10 min in 15 healthy participants. Pharyngeal motor-evoked and thenar motor-evoked potentials (PMEPs and TMEPs) were assessed before and up to 2 h after stimulation with single-pulse transcranial magnetic stimulation. Averaged MEP amplitude and latency changes were analyzed using repeated measures ANOVA (rmANOVA). KEY RESULTS: Two-way rmANOVA across all active interventions demonstrated a significant MEP interaction both in the stimulated pharyngeal cortex (F (4, 56) = 1.731, p = 0.038) and in the ipsilateral thenar cortex (F (4, 56) = 1.506, p = 0.048). Compared to sham, subsequent post hoc tests showed site-specific and sustained (60-120 min) increases in PMEPs with gamma tACS and tRNS (p = 0.005, p = 0.027, respectively) and for TMEPs with beta tACS (p = 0.006). CONCLUSIONS AND INFERENCES: Our findings suggest that the effects of tACS and tRNS are frequency-dependent and cortical (representation) site-specific with both gamma tACS and full-spectrum tRNS enhancing human pharyngeal cortical excitability. These techniques hold promise as potential treatments for neurological dysphagia.

Understanding racial disparities in the care of patients with irritable bowel syndrome: The need for a unified approach.

Irritable bowel syndrome (IBS) is a highly prevalent disorder of gut-brain interaction, which significantly erodes the quality of life of those it affects. Recent studies have confirmed that its prevalence varies quite markedly between countries, implying that it is affected by cultural and socioeconomic factors. In an important study, Silvernale at al. have recently reported racial disparities including potential referral biases, with reduced opportunities to access specialist care and differing patterns of healthcare utilization affecting ethnic minority populations with IBS. Similar disparities have also been reported for other gastrointestinal disorders. In this paper, we, therefore, discuss the potential implications of such disparities and how they can impact clinical outcomes, and discuss ways in which this problem could be addressed, and highlighting areas for future research.

Prevalence of Dysphagia in China: An Epidemiological Survey of 5943 Participants.

OBJECTIVE: To determine the prevalence of dysphagia among an older population and patients with stroke, head and neck cancers (HNCs) or neurodegenerative diseases (NDDs) in China, to identify the factors associated with this condition, and to explore the relationship between dysphagia and nutritional status. METHODS: This study included participants 65 years and older living in the community or in nursing homes and patients who had sustained a stroke, HNC, or NDD also recruited in hospitals from 14 provinces of China. The presence of dysphagia was determined by use of a questionnaire, water swallowing test, and/or a videofluoroscopic swallowing study. Logistic regression analysis was used to assess the possible associated risk factors. Body mass index was assessed as an indicator of malnutrition. RESULTS: A total of 5943 persons met the inclusion criteria and 2341 (39.4%) were identified with dysphagia, including the following: 51.14% of patients with stroke, 34.4% in HNCs, 48.3% in NDDs, and 19.2% of otherwise healthy older adults. The elderly with comorbidity (OR = 2.90, p < 0.01) and stroke patients (OR = 2.27, p < 0.01) were significantly more likely to exhibit signs of dysphagia. Dysphagic participants were at significantly greater risk of malnutrition (OR = 1.91, p < 0.01) compared to those without dysphagia. CONCLUSION: Dysphagia is prevalent in China among older individuals and people who have suffered a stroke, HNCs, or NDDs. The prevalence of dysphagia increases steadily with increasing age and presence of comorbid disease. People with dysphagia are more likely to suffer from malnutrition.

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.

The Effects of Midline Cerebellar rTMS on Human Pharyngeal Cortical Activity in the Intact Swallowing Motor System.

We sought to compare the effects of 10 Hz cerebellar vermis (vs. unilateral hemispheric and sham) repetitive transcranial magnetic stimulation (rTMS) on cortical neuroelectrical activity and thereafter 10 Hz cerebellar vermis (vs. sham) rTMS on swallowing behaviour. Healthy participants (n = 25) were randomly allocated to receive vermis, unilateral hemisphere or sham 10 Hz cerebellar rTMS. Recordings were made using pharyngeal electromyography and manometry catheters, obtaining motor-evoked potentials (MEPs) and pressure recordings. The amplitudes of MEPs elicited using single-pulse TMS delivered to the pharyngeal areas of the motor cortex bilaterally were measured pre- and post-cerebellar stimulation. As in previous studies, abductor policis brevis (APB) MEPs were measured to assess post-rTMS modulation specificity. Swallowing was assessed using a swallowing accuracy task. Measurements were made at baseline and 15-min intervals for an hour post-intervention. Measurements involved TMS being used to elicit 10 MEPs bilaterally over the pharyngeal areas of the motor cortex, over the APB cortical representation adjacent to the pharyngeal area with the lowest resting motor threshold and 5 MEPs bilaterally over pharyngeal areas of the cerebellar hemispheres. Swallowing accuracy was assessed by giving participants 10 attempts to swallow and hit a digital target. Cerebellar vermis rTMS caused significant suppression of cortical pharyngeal MEP amplitudes compared with unilateral rTMS and sham (P = 0.0005, 0.002). APB and cerebellar MEP amplitudes were unaffected as were pharyngeal and APB MEP latencies. Following cerebellar vermis rTMS there was a significant reduction in swallowing accuracy compared with sham (P = 0.001). Our findings demonstrate cerebellar vermis rTMS exerts a suppressive effect on pharyngeal motor cortical activity and swallowing behaviour.

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.

The effects of unilateral and bilateral cerebellar rTMS on human pharyngeal motor cortical activity and swallowing behavior.

The cerebellum is recognised to bilaterally modulate sensorimotor function and has recently been shown to play a role in swallowing. Unilateral cerebellar repetitive trans-cranial magnetic stimulation (rTMS) excites corticobulbar motor pathways to the pharynx but the effects of bilateral versus unilateral cerebellar rTMS on these pathways are unknown. In this three-part cross-over study, healthy participants (n = 13) were randomly allocated to receive unilateral or bilateral 10 Hz cerebellar rTMS. Participants were intubated with pharyngeal electromyography and/or manometry catheters for motor evoked potentials (MEPs) and pressure recordings. In part 1 of the study, single pulse TMS was used to measure baseline motor cortical pharyngeal MEP (PMEP) and hemispheric cerebellar MEP (CMEP) amplitudes, before cerebellar rTMS was administered. Repeat measures of PMEP amplitude were performed at 15-min intervals for an hour post unilateral and bilateral rTMS. Thereafter, in two further studies, a cortical 'virtual lesion' (V/L) was applied prior to cerebellar rTMS with pre and post PMEPs (part 2) and measurements of swallowing accuracy (part 3) using a behavioural task. Compared to baseline, unilateral and bilateral cerebellar rTMS provoked increases in pharyngeal cortical excitation (P = 0.028, 0.0005, respectively). Bilateral rTMS was significantly more effective than unilateral in causing cortical excitation (P = 0.0005) and in reversing the suppressive neurological (P = 0.0005) and behavioural (P = 0.0005) effects of a cortical V/L. Our findings suggest bilateral cerebellar rTMS has greater facilitatory effects on corticobulbar motor pathways to the pharynx than unilateral stimulation with the potential to be a more effective clinical therapy if its effects are reproduced in populations with neurogenic dysphagia.