The Effects of Noninvasive Vagus Nerve Stimulation on Fatigue and Immune Responses in Patients With Primary Sjögren's Syndrome

Transcutaneous Auricular Vagus Nerve Stimulation Combined With Slow Breathing: Speculations on Potential Applications and Technical Considerations

OBJECTIVES

Transcutaneous auricular vagus nerve stimulation (taVNS) is a relatively novel noninvasive neurostimulation method that is believed to mimic the effects of invasive cervical VNS. It has recently been suggested that the effectiveness of taVNS can be enhanced by combining it with controlled slow breathing. Slow breathing modulates the activity of the vagus nerve and is used in behavioral medicine to decrease psychophysiological arousal. Based on studies that examine the effects of taVNS and slow breathing separately, this article speculates on some of the conditions in which this combination treatment may prove effective. Furthermore, based on findings from studies on the optimization of taVNS and slow breathing, this article provides guidance on how to combine taVNS with slow breathing.

MATERIALS AND METHODS

A nonsystematic review.

RESULTS

Both taVNS and slow breathing are considered promising add-on therapeutic approaches for anxiety and depressive disorders, chronic pain, cardiovascular diseases, and insomnia. Therefore, taVNS combined with slow breathing may produce additive or even synergistic beneficial effects in these conditions. Studies on respiratory-gated taVNS during spontaneous breathing suggest that taVNS should be delivered during expiration. Therefore, this article proposes to use taVNS as a breathing pacer to indicate when and for how long to exhale during slow breathing exercises.

CONCLUSIONS

Combining taVNS with slow breathing seems to be a promising hybrid neurostimulation and behavioral intervention.

Cholinergic anti-inflammatory pathway and connective tissue diseases

Connective tissue diseases (CTDs) consist of an extensive range of heterogeneous medical conditions, which are caused by immune-mediated chronic inflammation and influences the various connective tissues of the body. They include rheumatoid arthritis, systemic lupus erythematosus, systemic sclerosis, vasculitis, Sjögren's syndrome, Behcet's disease, and many other autoimmune CTDs. To date, several anti-inflammatory approaches have been developed to reduce the severity of inflammation or its subsequent organ manifestations. As a logical mechanism to harnesses the undesired inflammation, some studies investigated the role of the intrinsic cholinergic anti-inflammatory pathway (CAP) in the modulation of chronic inflammation. Many different experimental and clinical models have been developed to evaluate the therapeutic significance of the CAP in CTDs. On the other hand, an issue that is less emphasized in this regard is the presence of autonomic neuropathy in CTDs, which influences the efficiency of CAP in such clinical settings. This condition occurs during CTDs and is a well-known complication of patients suffering from them. The advantages and limitations of CAP in the control of inflammatory responses and its possible therapeutic benefits in the treatment of CTDs are the main subjects of the current study. Therefore, this narrative review article is provided based on the recent findings of the complicated role of CAP in CTDs which were retrieved by searching Science Direct, PubMed, Google Scholar, and Web of Science. It seems that delineating the complex influences of CAP would be of great interest in designing novel surgical or pharmacological therapeutic strategies for CTDs therapy.

The evolving obesity challenge: targeting the vagus nerve and the inflammatory reflex in the response

Obesity and the metabolic syndrome (MetS), which have reached pandemic proportions significantly increase the risk for type 2 diabetes, cardiovascular disease, and other serious conditions. Recent data with COVID-19 patients indicate that obesity also is a significant risk factor for this novel viral disease and poor outcome of associated critical illness. These findings considerably change the view of obesity as a driver of serious, but slowly-progressing chronic diseases, and emphasize the urgency to explore new therapeutic approaches. Inflammation is a recognized driver of metabolic derangements in obesity and MetS, and a core feature of COVID-19 pathobiology. Recent advances in our understanding of inflammatory regulation have highlighted the role of the nervous system and the vagus nerve-based inflammatory reflex. Current bioelectronic and pharmacological therapeutic explorations centered on the inflammatory reflex offer new approaches for conditions characterized by immune and metabolic dysregulation and for ameliorating the escalating burden of obesity, MetS, and COVID-19.

Overview of therapeutic applications of non-invasive vagus nerve stimulation: a motivation for novel treatments for systemic lupus erythematosus

Systemic lupus erythematosus (SLE) is a chronic systemic autoimmune disorder that commonly affects the skin, joints, kidneys, and central nervous system. Although great progress has been made over the years, patients still experience unfavorable secondary effects from medications, increased economic burden, and higher mortality rates compared to the general population. To alleviate these current problems, non-invasive, non-pharmacological interventions are being increasingly investigated. One such intervention is non-invasive vagus nerve stimulation, which promotes the upregulation of the cholinergic anti-inflammatory pathway that reduces the activation and production of pro-inflammatory cytokines and reactive oxygen species, culpable processes in autoimmune diseases such as SLE. This review first provides a background on the important contribution of the autonomic nervous system to the pathogenesis of SLE. The gross and structural anatomy of the vagus nerve and its contribution to the inflammatory response are described afterwards to provide a general understanding of the impact of stimulating the vagus nerve. Finally, an overview of current clinical applications of invasive and non-invasive vagus nerve stimulation for a variety of diseases, including those with similar symptoms to the ones in SLE, is presented and discussed. Overall, the review presents neuromodulation as a promising strategy to alleviate SLE symptoms and potentially reverse the disease.

Is the heart rate variability monitoring using the analgesia nociception index a predictor of illness severity and mortality in critically ill patients with COVID-19? A pilot study

Introduction

The analysis of heart rate variability (HRV) has proven to be an important tool for the management of autonomous nerve system in both surgical and critically ill patients. We conducted this study to show the different spectral frequency and time domain parameters of HRV as a prospective predictor for critically ill patients, and in particular for COVID-19 patients who are on mechanical ventilation. The hypothesis is that most severely ill COVID-19 patients have a depletion of the sympathetic nervous system and a predominance of parasympathetic activity reflecting the remaining compensatory anti-inflammatory response.

Materials and methods

A single-center, prospective, observational pilot study which included COVID-19 patients admitted to the Surgical Intensive Care Unit was conducted. The normalized high-frequency component (HFnu), i.e. ANIm, and the standard deviation of RR intervals (SDNN), i.e. Energy, were recorded using the analgesia nociception index monitor (ANI). To estimate the severity and mortality we used the SOFA score and the date of discharge or date of death.

Results

A total of fourteen patients were finally included in the study. ANIm were higher in the non-survivor group (p = 0.003) and were correlated with higher IL-6 levels (p = 0.020). Energy was inversely correlated with SOFA (p = 0.039) and fewer survival days (p = 0.046). A limit value at 80 of ANIm, predicted mortalities with a sensitivity of 100% and specificity of 85.7%. In the case of Energy, a limit value of 0.41 ms predicted mortality with all predictive values of 71.4%.

Conclusion

A low autonomic nervous system activity, i.e. low SDNN or Energy, and a predominance of the parasympathetic system, i.e. low HFnu or ANIm, due to the sympathetic depletion in COVID-19 patients are associated with a worse prognosis, higher mortality, and higher IL-6 levels.

Multidimensional fatigue in patients with nasopharyngeal carcinoma receiving concurrent chemoradiotherapy: incidence, severity, and risk factors

PURPOSE

To explore the incidence, severity, and risk factors of multidimensional fatigue in patients with nasopharyngeal carcinoma (NPC) receiving concurrent chemoradiotherapy (CCRT).

METHODS

This prospective study included 79 patients with NPC in Guangzhou (China) from June 2015 to July 2018. Data were collected before and after CCRT, including demographic and clinical characteristics, nutritional parameters, and fatigue scores, based on completion of the Multiple Dimensional Inventory-20 Questionnaire, with five subscales: General Fatigue, Mental Fatigue, Physical Fatigue, Reduced Activity, and Reduced Motivation.

RESULTS

Increased general fatigue was found to be associated with lower lymphocyte count and body mass index <23 kg/m². Increased physical fatigue was related to age > 42 years. Higher scores for reduced activity were associated with age > 42 years, female sex, and lower serum sodium. Increased mental fatigue was related with lower lymphocyte count and unemployment; and increased total fatigue was associated with lower lymphocyte count, age > 42 years, and 3-6 courses of treatment. Furthermore, 3-6 courses of treatment was an independent predictor of severe general fatigue, while age >42 years was an independent predictor of severe physical fatigue. Importantly, cancer stage IVB and 3-6 courses of treatment could predict severe total fatigue.

CONCLUSIONS

Our data demonstrate that fatigue is increased in all dimensions in NPC patients following CCRT, and that the predictors differ for each fatigue dimension. These results could guide the development of targeted interventions that may reduce the impact of cancer-related fatigue in patients with NPC.

Vagus nerve stimulation in musculoskeletal diseases

The vagus nerve is the main nerve of the parasympathetic autonomic nervous system. Beyond its vegetative functions, the vagus nerve possesses anti-inflammatory and analgesic properties. Initially developed in the treatment of refractory epilepsy, vagus nerve stimulation (VNS) is currently being evaluated in several musculoskeletal diseases. VNS can be invasive by placing an electrode around the cervical vagus nerve and connected to a generator implanted subcutaneously or non-invasive stimulating the cervical vagus nerve branch percutaneously (auricular or cervical). In rheumatoid arthritis (RA) patients, VNS has been shown to dampen the inflammatory response of circulatory peripheral cells. Several open-labeled small pilot studies have demonstrated that VNS, either invasive or transcutaneous, is associated with a significant decrease of RA disease activity. As well, other studies have shown that VNS could limit fatigue in Sjogren's syndrome and systemic lupus, or decrease pain in fibromyalgia as well as in erosive hand osteoarthritis. However, some questions remain, such as the settings of stimulation, the duration of treatment, or the optimal stimulation route. Finally, randomized controlled trials versus sham stimulation with large samples of patients are mandatory to definitively conclude about the efficacy of VNS.

Transcutaneous auricular vagus nerve stimulation reduces pain and fatigue in patients with systemic lupus erythematosus: a randomised, double-blind, sham-controlled pilot trial

OBJECTIVES

Musculoskeletal pain and fatigue are common features in systemic lupus erythematosus (SLE). The cholinergic anti-inflammatory pathway is a physiological mechanism diminishing inflammation, engaged by stimulating the vagus nerve. We evaluated the effects of non-invasive vagus nerve stimulation in patients with SLE and with musculoskeletal pain.

METHODS

18 patients with SLE and with musculoskeletal pain ≥4 on a 10 cm Visual Analogue Scale were randomised (2:1) in this double-blind study to receive transcutaneous auricular vagus nerve stimulation (taVNS) or sham stimulation (SS) for 4 consecutive days. Evaluations at baseline, day 5 and day 12 included patient assessments of pain, disease activity (PtGA) and fatigue. Tender and swollen joint counts and the Physician Global Assessment (PGA) were completed by a physician blinded to the patient's therapy. Potential biomarkers were evaluated.

RESULTS

taVNS and SS were well tolerated. Subjects receiving taVNS had a significant decrease in pain and fatigue compared with SS and were more likely (OR=25, p=0.02) to experience a clinically significant reduction in pain. PtGA, joint counts and PGA also improved. Pain reduction and improvement of fatigue correlated with the cumulative current received. In general, responses were maintained through day 12. Plasma levels of substance P were significantly reduced at day 5 compared with baseline following taVNS but other neuropeptides, serum and whole blood-stimulated inflammatory mediators, and kynurenine metabolites showed no significant change at days 5 or 12 compared with baseline.

CONCLUSION

taVNS resulted in significantly reduced pain, fatigue and joint scores in SLE. Additional studies evaluating this intervention and its mechanisms are warranted.

Transcutaneous vagal nerve stimulation blocks stress-induced activation of Interleukin-6 and interferon-γ in posttraumatic stress disorder: A double-blind, randomized, sham-controlled trial

Posttraumatic stress disorder (PTSD) is a highly disabling condition associated with alterations in multiple neurobiological systems, including increases in inflammatory function. Vagus nerve stimulation (VNS) decreases inflammation, however few studies have examined the effects of non-invasive VNS on physiology in human subjects, and no studies in patients with PTSD. The purpose of this study was to assess the effects of transcutaneous cervical VNS (tcVNS) on inflammatory responses to stress. Thirty subjects with a history of exposure to traumatic stress with (N ​= ​10) and without (N ​= ​20) PTSD underwent exposure to stressful tasks immediately followed by active or sham tcVNS and measurement of multiple biomarkers of inflammation (interleukin-(IL)-6, IL-2, IL-1β, Tumor Necrosis Factor alpha (TNFα) and Interferon gamma (IFNγ) over multiple time points. Stressful tasks included exposure to personalized scripts of traumatic events on day 1, and public speech and mental arithmetic (Mental Stress) tasks on days 2 and 3. Traumatic scripts were associated with a pattern of subjective anger measured with Visual Analogue Scales and increased IL-6 and IFNγ in PTSD patients that was blocked by tcVNS (p ​< ​.05). Traumatic stress had minimal effects on these biomarkers in non-PTSD subjects and there was no difference between tcVNS or sham. No significant differences were seen between groups in IL-2, IL-1β, or TNFα. These results demonstrate that tcVNS blocks behavioral and inflammatory responses to stress reminders in PTSD.

Transcutaneous cervical vagal nerve stimulation reduces sympathetic responses to stress in posttraumatic stress disorder: A double-blind, randomized, sham controlled trial

OBJECTIVE

Exacerbated autonomic responses to acute stress are prevalent in posttraumatic stress disorder (PTSD). The purpose of this study was to assess the effects of transcutaneous cervical VNS (tcVNS) on autonomic responses to acute stress in patients with PTSD. The authors hypothesized tcVNS would reduce the sympathetic response to stress compared to a sham device.

METHODS

Using a randomized double-blind approach, we studied the effects of tcVNS on physiological responses to stress in patients with PTSD (n = 25) using noninvasive sensing modalities. Participants received either sham (n = 12) or active tcVNS (n = 13) after exposure to acute personalized traumatic script stress and mental stress (public speech, mental arithmetic) over a three-day protocol. Physiological parameters related to sympathetic responses to stress were investigated.

RESULTS

Relative to sham, tcVNS paired to traumatic script stress decreased sympathetic function as measured by: decreased heart rate (adjusted β = -5.7%; 95% CI: ±3.6%, effect size d = 0.43, p < 0.01), increased photoplethysmogram amplitude (peripheral vasodilation) (30.8%; ±28%, 0.29, p < 0.05), and increased pulse arrival time (vascular function) (6.3%; ±1.9%, 0.57, p < 0.0001). Similar (p < 0.05) autonomic, cardiovascular, and vascular effects were observed when tcVNS was applied after mental stress or without acute stress.

CONCLUSION

tcVNS attenuates sympathetic arousal associated with stress related to traumatic memories as well as mental stress in patients with PTSD, with effects persisting throughout multiple traumatic stress and stimulation testing days. These findings show that tcVNS has beneficial effects on the underlying neurophysiology of PTSD. Such autonomic metrics may also be evaluated in daily life settings in tandem with tcVNS therapy to provide closed-loop delivery and measure efficacy.ClinicalTrials.gov Registration # NCT02992899.

Application of Noninvasive Vagal Nerve Stimulation to Stress-Related Psychiatric Disorders

BACKGROUND

Vagal Nerve Stimulation (VNS) has been shown to be efficacious for the treatment of depression, but to date, VNS devices have required surgical implantation, which has limited widespread implementation.

METHODS

New noninvasive VNS (nVNS) devices have been developed which allow external stimulation of the vagus nerve, and their effects on physiology in patients with stress-related psychiatric disorders can be measured with brain imaging, blood biomarkers, and wearable sensing devices. Advantages in terms of cost and convenience may lead to more widespread implementation in psychiatry, as well as facilitate research of the physiology of the vagus nerve in humans. nVNS has effects on autonomic tone, cardiovascular function, inflammatory responses, and central brain areas involved in modulation of emotion, all of which make it particularly applicable to patients with stress-related psychiatric disorders, including posttraumatic stress disorder (PTSD) and depression, since dysregulation of these circuits and systems underlies the symptomatology of these disorders.

RESULTS

This paper reviewed the physiology of the vagus nerve and its relevance to modulating the stress response in the context of application of nVNS to stress-related psychiatric disorders.

CONCLUSIONS

nVNS has a favorable effect on stress physiology that is measurable using brain imaging, blood biomarkers of inflammation, and wearable sensing devices, and shows promise in the prevention and treatment of stress-related psychiatric disorders.

Fatigue in inflammatory arthritis

Fatigue is highly prevalent in inflammatory arthritis, and people living with the symptom have described it as overwhelming and a challenge to manage. In this article, we explore the experience, impact and non-pharmacological management of fatigue from a multi-disciplinary perspective. We start by presenting qualitative evidence from people living with fatigue, including the physical, cognitive and emotional nature of the symptom and its impact on daily life. This is followed by discussion of current conceptual models of mechanisms and factors that may cause and maintain fatigue, within and between individuals. We then address the issue of fatigue measurement and modes of assessment, which is an integral aspect of management and evaluating support provision. This leads to a review of the research evidence for non-pharmacological interventions to reduce fatigue severity and impact. Finally, we consider implementation of this evidence in clinical practice and we introduce some key practical tools and techniques.

The Use of Non-invasive Vagus Nerve Stimulation to Treat Respiratory Symptoms Associated With COVID-19: A Theoretical Hypothesis and Early Clinical Experience

OBJECTIVES

Coronavirus disease 2019 (COVID-19), caused by severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2), is a pandemic with no specific therapeutic agents and substantial mortality, and finding new treatments is critical. Most cases are mild, but a significant minority of patients develop moderate to severe respiratory symptoms, with the most severe cases requiring intensive care and/or ventilator support. This respiratory compromise appears to be due to a hyperimmune reaction, often called a cytokine storm. Vagus nerve stimulation has been demonstrated to block production of cytokines in sepsis and other medical conditions. We hypothesize that non-invasive vagus nerve stimulation (nVNS) might provide clinical benefits in patients with respiratory symptoms similar to those associated with COVID-19.

MATERIALS AND METHODS

Information on two case reports was obtained via email correspondence and phone interviews with the patients.

RESULTS

Both patients reported clinically meaningful benefits from nVNS therapy. In case 1, the patient used nVNS to expedite symptomatic recovery at home after hospital discharge and was able to discontinue use of opioid and cough suppressant medications. In case 2, the patient experienced immediate and consistent relief from symptoms of chest tightness and shortness of breath, as well as an improved ability to clear his lungs.

CONCLUSIONS

Preliminary observations and a strong scientific foundation suggest that nVNS might provide clinical benefits in patients with COVID-19 via multiple mechanisms.

Bioelectronic Medicine: From Preclinical Studies on the Inflammatory Reflex to New Approaches in Disease Diagnosis and Treatment

Bioelectronic medicine is an evolving field in which new insights into the regulatory role of the nervous system and new developments in bioelectronic technology result in novel approaches in disease diagnosis and treatment. Studies on the immunoregulatory function of the vagus nerve and the inflammatory reflex have a specific place in bioelectronic medicine. These studies recently led to clinical trials with bioelectronic vagus nerve stimulation in inflammatory diseases and other conditions. Here, we outline key findings from this preclinical and clinical research. We also point to other aspects and pillars of interdisciplinary research and technological developments in bioelectronic medicine.

An Injectable Neural Stimulation Electrode Made from an In-Body Curing Polymer/Metal Composite

Implanted neural stimulation and recording devices hold vast potential to treat a variety of neurological conditions, but the invasiveness, complexity, and cost of the implantation procedure greatly reduce access to an otherwise promising therapeutic approach. To address this need, a novel electrode that begins as an uncured, flowable prepolymer that can be injected around a neuroanatomical target to minimize surgical manipulation is developed. Referred to as the Injectrode, the electrode conforms to target structures forming an electrically conductive interface which is orders of magnitude less stiff than conventional neuromodulation electrodes. To validate the Injectrode, detailed electrochemical and microscopy characterization of its material properties is performed and the feasibility of using it to stimulate the nervous system electrically in rats and swine is validated. The silicone-metal-particle composite performs very similarly to pure wire of the same metal (silver) in all measures, including exhibiting a favorable cathodic charge storage capacity (CSCC ) and charge injection limits compared to the clinical LivaNova stimulation electrode and silver wire electrodes. By virtue of its simplicity, the Injectrode has the potential to be less invasive, more robust, and more cost-effective than traditional electrode designs, which could increase the adoption of neuromodulation therapies for existing and new indications.

Study protocol for a randomised double-blinded, sham-controlled, prospective, cross-over clinical trial of vagal neuromodulation for pain treatment in patients with chronic pancreatitis

INTRODUCTION

The management of chronic pancreatitis (CP) is challenging and requires a personalised approach focused on the individual patient's main symptoms. Abdominal pain is the most prominent symptom in CP, where central pain mechanisms, including sensitisation and impaired pain modulation, often are involved. Recent clinical studies suggest that vagal nerve stimulation (VNS) induces analgesic effects through the modulation of central pain pathways. This study aims to investigate the effect of 2 weeks transcutaneous VNS (t-VNS) on clinical pain in patients with CP, in comparison to the effect of sham treatment.

METHODS AND ANALYSIS

Twenty-one patients with CP will be enrolled in this randomised, double-blinded, single-centre, sham-controlled, cross-over study. The study has two treatment periods: A 2-week active t-VNS using GammaCore device and a 2-week treatment with a sham device. During both treatment periods, the patients are instructed to self-administer VNS bilaterally to the cervical vagal area, three times per day. Treatment periods will be separated by 2 weeks. During the study period, patients will record their daily pain experience in a diary (primary clinical endpoint). In addition, all subjects will undergo testing which will include MRI, quantitative sensory testing, cardiac vagal tone assessment and collecting blood samples, before and after the two treatments to investigate mechanisms underlying VNS effects. The data will be analysed using the principle of intention to treat.

ETHICS AND DISSEMINATION

The regional ethics committee has approved the study: N-20170023. Results of the trial will be submitted for publication in peer-reviewed journals.

TRIAL REGISTRATION NUMBER

The study is registered at www.clinicaltrials.gov: NCT03357029.

Fatigue, Sleep, and Autoimmune and Related Disorders

Profound and debilitating fatigue is the most common complaint reported among individuals with autoimmune disease, such as systemic lupus erythematosus, multiple sclerosis, type 1 diabetes, celiac disease, chronic fatigue syndrome, and rheumatoid arthritis. Fatigue is multi-faceted and broadly defined, which makes understanding the cause of its manifestations especially difficult in conditions with diverse pathology including autoimmune diseases. In general, fatigue is defined by debilitating periods of exhaustion that interfere with normal activities. The severity and duration of fatigue episodes vary, but fatigue can cause difficulty for even simple tasks like climbing stairs or crossing the room. The exact mechanisms of fatigue are not well-understood, perhaps due to its broad definition. Nevertheless, physiological processes known to play a role in fatigue include oxygen/nutrient supply, metabolism, mood, motivation, and sleepiness-all which are affected by inflammation. Additionally, an important contributing element to fatigue is the central nervous system-a region impacted either directly or indirectly in numerous autoimmune and related disorders. This review describes how inflammation and the central nervous system contribute to fatigue and suggests potential mechanisms involved in fatigue that are likely exhibited in autoimmune and related diseases.

Managing fatigue in patients with primary Sjögren's syndrome: challenges and solutions

Primary Sjögren's syndrome (pSS) patients identify fatigue as their most important symptom and the one most difficult to cope with, but there are still many challenges and few solutions to manage this debilitating symptom. Promising pharmacological treatments, such as rituximab, have failed in more stringent tests including randomized controlled trials (RCTs) and meta-analysis. While non-pharmacological interventions may be safer, less costly, and address other common comorbidities, to date only aerobic exercise seems to be effective at reducing fatigue in pSS. All interventions, pharmacological or not, need to be tested in high-quality RCTs. The aim of this review is to provide an overview of fatigue management in pSS and discuss potential opportunities for future research.