Non-invasive vagus nerve stimulation (nVNS) for the preventive treatment of episodic migraine: The multicentre, double-blind, randomised, sham-controlled PREMIUM trial

Vagus nerve stimulation (VNS): recent advances and future directions

PURPOSE

Vagus nerve stimulation (VNS) is emerging as a unique and potent intervention, particularly within neurology and psychiatry. The clinical value of VNS continues to grow, while the development of noninvasive options promises to change a landscape that is already quickly evolving. In this review, we highlight recent progress in the field and offer readers a glimpse of the future for this bright and promising modality.

METHODS

We compiled a narrative review of VNS literature using PubMed and organized the discussion by disease states with approved indications (epilepsy, depression, obesity, post-stroke motor rehabilitation, headache), followed by a section highlighting novel, exploratory areas of VNS research. In each section, we summarized the current role, recent advancements, and future directions of VNS in the treatment of each disease.

RESULTS

The field continues to gain appreciation for the clinical potential of this modality. VNS was initially developed for treatment-resistant epilepsy, with the first depression studies following shortly thereafter. Overall, VNS has gained approval or clearance in the treatment of medication-refractory epilepsy, treatment-resistant depression, obesity, migraine/cluster headache, and post-stroke motor rehabilitation.

CONCLUSION

Noninvasive VNS represents an opportunity to bridge the translational gap between preclinical and clinical paradigms and may offer the same therapeutic potential as invasive VNS. Further investigation into how VNS parameters modulate behavior and biology, as well as how to translate noninvasive options into the clinical arena, are crucial next steps for researchers and clinicians studying VNS.

Neuromodulation treatments for migraine: a contemporary update

PURPOSE OF REVIEW

Neuromodulation approaches have been a part of a revolution in migraine therapies with multiple devices approved or in development. These devices vary in the nerve(s) being targeted, implantable versus noninvasive form factors as well as their effectiveness for acute pain reduction or migraine prevention. This review will summarize these recent advancements and approaches that are being developed which build upon prior work and improved technology that may help enhance the effectiveness as well as the patient experience.

RECENT FINDINGS

Both noninvasive and implantable devices primarily targeting cranial nerves have shown the ability to help alleviate migraine symptoms. Multiple prospective and retrospective studies have demonstrated clinically meaningful reductions in headache intensity with noninvasive approaches, while prevention of migraine demonstrates more modest effects. Implantable neuromodulation technologies focusing on occipital and supraorbital stimulation have shown promise in migraine/headache prevention in chronic migraine patients, but there is a need for improvements in technology to address key needs for surgical approaches.

SUMMARY

Electrical neuromodulation approaches in the treatment of migraine is undergoing a transformation towards improved outcomes with better technologies that may suit various patient needs on a more individualized basis.

Transcutaneous vagus nerve stimulation effects on chronic pain: systematic review and meta-analysis

Chronic pain is one of the major causes of disability with a tremendous impact on an individual's quality of life and on public health. Transcutaneous vagus nerve stimulation (tVNS) is a safe therapeutic for this condition. We aimed to evaluate its effects in adults with chronic pain. A comprehensive search was performed, including randomized controlled trials published until October 2023, which assessed the effects of noninvasive tVNS. Cohen's d effect size and 95% confidence intervals (CIs) were calculated, and random-effects meta-analyses were performed. Fifteen studies were included. The results revealed a mean effect size of 0.41 (95% CI 0.17-0.66) in favor of tVNS as compared with control, although a significant heterogeneity was observed (χ2 = 21.7, df = 10, P = 0.02, I 2 = 53.9%). However, when compared with nonactive controls, tVNS shows a larger effect size (0.79, 95% CI 0.25-1.33), although the number of studies was small (n = 3). When analyzed separately, auricular tVNS and cervical tVNS against control, it shows a significant small to moderate effect size, similar to that of the main analysis, respectively, 0.42 (95% CI 0.08-0.76, 8 studies) and 0.36 (95% CI 0.01-0.70, 3 studies). No differences were observed in the number of migraine days for the trials on migraine. This meta-analysis indicates that tVNS shows promise as an effective intervention for managing pain intensity in chronic pain conditions. We discuss the design of future trials to confirm these preliminary results, including sample size and parameters of stimulation.

Research hotspots and trends of non-invasive vagus nerve stimulation: a bibliometric analysis from 2004 to 2023

Objectives

Non-invasive vagus nerve stimulation (nVNS) is an emerging neuromodulation technique in recent years, which plays a role in nervous system diseases, psychiatric diseases, and autoimmune diseases. However, there is currently no comprehensive analysis of all the literature published in this field. Therefore, in this article, a bibliometric analysis will be conducted on all the literature published in the field of nVNS in the past 20 years.

Methods

All articles and reviews published in this field from 2004 to 2023 were extracted from the WOS core database. VOSviewer 1.6.18.0, Scimago Graphica, CiteSpace 6.2.R2, and Excel 2021 were used to analyze the number of publications, participating countries, institutions, authors, references, and research hotspots in this field.

Results

A total of 843 articles were included in the bibliometric analysis of nVNS. Over the past 20 years, the number of publications in this field has gradually increased, reaching a peak in 2023. The United States and China ranked top two in terms of publication volume, and institutions from these two countries also ranked high in terms of publication volume, citation count, and collaboration intensity. Rong Peijing is the author with the most publications, while Bashar W Badran is the most cited author. Articles in the field of nVNS were most frequently published in Frontiers in Neuroscience, while Brain Stimulation had the most citations. Currently, research hotspots in nVNS mainly focus on its application in diseases and related mechanisms.

Conclusion

We conducted a comprehensive analysis of the field of nVNS, clarifying the previous research directions, which is helpful to expand its indications and promote clinical application.

Transcutaneous vagus nerve stimulation: a bibliometric study on current research hotspots and status

Background

Transcutaneous Vagal Nerve Stimulation (tVNS) has been used as a promising noninvasive neuromodulation technique for the treatment of various systems.The aim of this study was to analyze the research hotspots and future directions of tVNS in the 21st century by using bibliometric methods.

Methods

The study object was the literature related to tVNS from the Web of Science database from 2000 to May 2024. In order to measure and analyze the number of literature issuance, institutions, authors, countries, keywords, co-citations, and journals of publication, we used VOSviewer, Citespace, Bibliometrix R-package, and Scimago Graphica software. A narrative review of the current research content of tVNS was conducted to gain a better understanding of the current state of the field.

Results

A total of 569 papers were included in the study. The results show that from 2000 to 2024, the number of publications shows an increasing trend year by year, involving a total of 326 research institutions. The United States, China, and Germany are the major research centers. The study identified 399 keywords, which roughly formed 11 natural clusters, revealing that the current hotspots of related research are mainly reflected in 3 areas: intervention efficacy on nervous system diseases, mechanism of action of tVNS, and stimulation mode of tVNS. The top 10 most cited references focus on research into the mechanism of action of tVNS.

Conclusion

The efficacy and safety of tVNS have been confirmed in previous studies, but a standardized tVNS treatment protocol has not yet been developed, and most clinical studies have small sample sizes and lack multicenter and multidisciplinary collaboration. Currently, tVNS is used in the treatment of neurological diseases, psychiatric diseases, cardiovascular diseases, and some autoimmune diseases. It is expected that future research in this field will continue to focus on the application of tVNS in central nervous system diseases and the exploration of related mechanisms, and at the same time, with the rise of non-invasive neuromodulation technology, the application of tVNS in other diseases also has great potential for development.

Effect of different non-pharmacologic placebo treatments on migraine prevention: a network meta-analysis of randomized controlled trials

BACKGROUND

Placebo control plays an important role in evaluating the effectiveness of interventions. Specifying differential effects of various placebo controls on migraine prevention would be essential in the explanation of preventive treatment for migraine and the indirect comparison between different prophylactic therapeutics.

OBJECTIVES

To access the impact of different non-pharmacologic placebo types on different outcomes in migraine patients.

METHODS

We searched PubMed, Cochrane Controlled Register of Trials, Embase, and Web of Science databases from the date of creation to June 19, 2023. Randomized controlled trials of migraine that included sham intervention of acupuncture or cognitive behavioural therapy (CBT) or non-invasive Vagus Nerve Stimulation (nVNS) or repetitive Transcranial Magnetic Stimulation (rTMS) or transcranial Direct Current Stimulation (tDCS) were conducted. The primary outcome was the migraine days, and the secondary outcomes were the number of migraine attacks, headache days, headache frequency, and responder's rate. Placebo effects were assessed using five individual placebos for network meta-analysis, using mean differences to measure the relative effect of pair-wise comparisons between interventions.

RESULT

A total of 50 trials with 4880 subjects were included. Twenty-seven trials were evaluated for low risk of bias. The results of indirect comparisons show that sham rTMS and sham tDCS had optimal and similar effects in reducing migraine days; sham acupuncture has the greatest effect on reducing the number of migraine attacks and relieving headache frequency; sham rTMS had a highly significant advantage in reducing headache days compared with the other placebo controls.

CONCLUSION

Based on the network meta-analysis results, we found that sham acupuncture had the greatest effect on migraine prophylaxis. The strong placebo effect of sham acupuncture should be considered when assessing the therapeutic effect.

Refractory primary and secondary headache disorders that dramatically responded to combined treatment of ultrasound-guided percutaneous suprazygomatic pterygopalatine ganglion blocks and non-invasive vagus nerve stimulation: a case series

In 1981, Devoghel achieved an 85.6% success rate in treating patients with treatment-refractory cluster headaches with alcoholization of the pterygopalatine ganglion (PPG) via the percutaneous suprazygomatic approach. Devoghel's study led to the theory that interrupting the parasympathetic pathway by blocking its transduction at the PPG could prevent or treat symptoms related to primary headache disorders (PHDs). Furthermore, non-invasive vagus nerve stimulation (nVNS) has proven to treat PHDs and has been approved by national regulatory bodies to treat, among others, cluster headaches and migraines.In this case series, nine desperate patients who presented with 11 longstanding treatment-refractory primary headache disorders and epidural blood patch-resistant postdural puncture headache (PDPH) received ultrasound-guided percutaneous suprazygomatic pterygopalatine ganglion blocks (PPGB), and seven also received nVNS. The patients were randomly selected and were not part of a research study. They experienced dramatic, immediate, satisfactory, and apparently lasting symptom resolution (at the time of the writing of this report). The report provides the case descriptions, briefly reviews the trigeminovascular and neurogenic inflammatory theories of the pathophysiology, outlines aspects of these PPGB and nVNS interventions, and argues for adopting this treatment regime as a first-line or second-line treatment rather than desperate last-line treatment of PDPH and PHDs.

Investigation of non-invasive focused ultrasound efficacy on depressive-like behavior in hemiparkinsonian rats

Depression is a common non-motor symptom in Parkinson's disease (PD) that includes anhedonia and impacts quality of life but is not effectively treated with conventional antidepressants clinically. Vagus nerve stimulation improves treatment-resistant depression in the general population, but research about its antidepressant efficacy in PD is limited. Here, we administered peripheral non-invasive focused ultrasound to hemiparkinsonian ('PD') and non-parkinsonian (sham) rats to mimic vagus nerve stimulation and assessed its antidepressant-like efficacy. Following 6-hydroxydopamine (6-OHDA) lesion, akinesia-like immobility was assessed in the limb-use asymmetry test, and despair- and anhedonic-like behaviors were evaluated in the forced swim test and sucrose preference test, respectively. After, tyrosine hydroxylase immuno-staining was employed to visualize and quantify dopaminergic degeneration in the substantia nigra pars compacta, ventral tegmental area, and striatum. We found that PD rats exhibited akinesia-like immobility and > 90% reduction in tyrosine hydroxylase immuno-staining ipsilateral to the lesioned side. PD rats also demonstrated anhedonic-like behavior in the sucrose preference test compared to sham rats. No 6-OHDA lesion effect on immobility in the forced swim test limited conclusions about the efficacy of ultrasound on despair-like behavior. However, ultrasound improved anhedonic-like behavior in PD rats and this efficacy was sustained through the end of the 1-week recovery period. The greatest number of animals demonstrating increased sucrose preference was in the PD group receiving ultrasound. Our findings here are the first to posit that peripheral non-invasive focused ultrasound to the celiac plexus may improve anhedonia in PD with further investigation needed to reveal its potential for clinical applicability.

Vagus nerve stimulation in medically refractory epilepsy: Adverse effects and clinical correlates

OBJECTIVES

To assess the frequency of adverse effects among pediatric and adult patients and the clinical variables associated with a higher probability of developing side effects.

METHODS

This retrospective study enrolled pediatric and adult patients who underwent Vagus nerve stimulation (VNS) implantation at our institution and had documented follow-up during clinic visits for at least 6 months after implantation. Data collected included demographic information, epilepsy diagnosis, and device data.

RESULTS

A total of 43 patients with drug-resistant epilepsy who received a VNS device at our institution were enrolled. The median follow-up period was 12 months. Fourteen patients (32.55%) reported no side effects from VNS therapy. Side effects ranged from mild to severe, with significant side effects observed in 8 patients. Data on therapy efficacy were collected, and 10 patients (23.26%) reported no change in seizure frequency following device implantation.

CONCLUSION

This study demonstrates that VNS is an important adjunct treatment option for epilepsy patients. Dysphagia and dyspnea can be significant adverse effects leading to treatment discontinuation, aspiration pneumonia, intensive care unit (ICU) admission, and prolonged hospital stay. These effects are more frequent in patients with symptomatic generalized epilepsy, global developmental delay at baseline, previous ICU admissions, abnormal brain magnetic resonance imaging findings, and seizures with multiple semiologies.

Neuromodulation for Craniofacial Pain and Headaches

Headaches and facial pain are highly prevalent diseases but are often difficult to treat. Though there have been significant advances in medical management, many continue to suffer from refractory pain. Neuromodulation has been gaining interest for its therapeutic purposes in many chronic pain conditions, including headaches and facial pain. There are many potential targets of neuromodulation for headache and facial pain, and some have more robust evidence in favor of their use than others. Despite the need for more high-quality research, the available evidence for the use of neuromodulation in treating headaches and facial pain is promising. Considering the suffering that afflicts patients with intractable headache, neuromodulation may be an appropriate tool to improve not only pain but also disability and quality of life.

Nonpharmacologic Treatments for Chronic and Episodic Migraine: A Systematic Review and Meta-Analysis

BACKGROUND

Minimally invasive techniques for treatment-resistant migraine have been developed on recent insights into the peripheral pathogenesis of migraines. Although there is a growing body of evidence supporting these techniques, no study has yet compared the effects of these treatments on headache frequency, severity, duration, and cost.

METHODS

PubMed, Embase, and Cochrane Library databases were searched to identify randomized placebo-controlled trials that compared radiofrequency ablation, botulinum toxin type A (BT-A), nerve block, neurostimulation, or migraine surgery to placebo for preventive treatment. Data on changes from baseline to follow-up in headache frequency, severity, duration, and quality of life were analyzed.

RESULTS

A total of 30 randomized controlled trials and 2680 patients were included. Compared with placebo, there was a significant decrease in headache frequency in patients with nerve block ( P = 0.04) and surgery ( P < 0.001). Headache severity decreased in all treatments. Duration of headaches was significantly reduced in the BT-A ( P < 0.001) and surgery cohorts ( P = 0.01). Quality of life improved significantly in patients with BT-A, nerve stimulator, and migraine surgery. Migraine surgery had the longest lasting effects (11.5 months) compared with nerve ablation (6 months), BT-A (3.2 months), and nerve block (11.9 days).

CONCLUSIONS

Migraine surgery is a cost-effective, long-term treatment to reduce headache frequency, severity, and duration without significant risk of complication. BT-A reduces headache severity and duration, but it is short-lasting and associated with greater adverse events and lifetime cost. Although efficacious, radiofrequency ablation and implanted nerve stimulators have high risks of adverse events and explantation, whereas benefits of nerve blocks are short in duration.

Episodic Migraine and POTS

PURPOSE OF REVIEW

Migraine is prevalent in patients with postural orthostatic tachycardia syndrome (POTS). The purpose of this review is to summarize and interpret studies that examine stress response systems in patients with migraine, focusing on their relevance to the pathologies associated with POTS. Important structural and functional components of the stress response network are also reviewed.

RECENT FINDINGS

In patients with migraine, studies examining the autonomic nervous system have demonstrated interictal sympathetic hypofunction and ictal sympathetic hyperfunction, while those focusing on the hypothalamic-pituitary-adrenal axis have demonstrated elevated responsivity. There is evidence that activation of these stress response systems during a migraine episode may exacerbate vascular dysfunction and play a role in the development of central sensitization. Activation of the stress response systems during an episode of migraine has the potential to exacerbate the pathology of POTS. Treatment approaches for the patient with comorbid episodic migraine and POTS should consider the etiology of POTS.

Beyond the Guidelines: A Narrative Review of Treatments on the Horizon for Migraine in Children and Adolescents

Migraine is common in children and adolescents and can cause significant disability. There are relatively limited evidence-based treatment options available, especially when compared with treatment of migraine in adults. The Pediatric Research Equity Act requires the study of a new drug or biologic in pediatric populations. As such it is mandatory that the newest migraine treatment options available for adults be evaluated in children and adolescents. It will take years before results from clinical trials in pediatric patients become available. In the meantime, there is eagerness among clinicians to seek out the existing evidence that may help provide clarity on utilization of the newer migraine therapies in children and adolescents because many of the currently available, guideline-recommended treatments do not provide benefit for all patients. In this narrative review, the literature regarding onabotulinumtoxinA, neuromodulatory devices, calcitonin gene-related peptide (CGRP) monoclonal antibodies, 5-hydroxytryptamine (1F) agonists (i.e., ditans), and CGRP small-molecule receptor antagonists (i.e., gepants) for the treatment of migraine in children and adolescents will be summarized.

Efficacy of transcutaneous auricular vagus nerve stimulation on radiotherapy-related neuropathic pain in patients with head and neck cancers (RELAX): protocol for a multicentre, randomised, double-blind, sham-controlled trial

INTRODUCTION

Radiotherapy-related neuropathic pain (RRNP) is one of the most distressing complications after radiotherapy for head and neck cancers. Drug therapy is not sufficiently effective and has limitations in terms of dose titration period and side effects. Transcutaneous auricular vagus nerve stimulation (taVNS), which stimulates the auricular branches of the vagus nerve through electrical impulses, has been proven to have analgesic effects in certain diseases. However, it is unknown whether taVNS can relieve RRNP.

METHODS AND ANALYSIS

This is a multicentre, randomised, double-blind, parallel, sham-controlled trial. We will include adult patients newly diagnosed with neuropathic pain after radiotherapy for head and neck cancers. One hundred and sixteen individuals will be recruited and randomly assigned in a 1:1 ratio to receive taVNS or sham stimulation. The interventions will last for 7 days, twice daily for 30 min each. The primary efficacy outcome is pain reduction on day 7. The secondary outcomes are changes in functional interference, psychological distress, fatigue, quality of life and serum inflammatory factors. The study may provide a new early intervention strategy for RRNP among patients with head and neck cancers.

ETHICS AND DISSEMINATION

This study has been approved by the Medical Research Ethics Committee of Sun Yat-sen University (SYSKY-2022-109-01) and will be conducted in strict accordance with the Declaration of Helsinki. Ethical approvals will be obtained separately for all centres involved in the study. Study results will be published in peer-reviewed academic journals. The database of the study will be available from the corresponding author on reasonable request.

TRIAL REGISTRATION NUMBER

NCT05543239.

Neuroimmunomodulation of vagus nerve stimulation and the therapeutic implications

Vagus nerve stimulation (VNS) is a technology that provides electrical stimulation to the cervical vagus nerve and can be applied in the treatment of a wide variety of neuropsychiatric and systemic diseases. VNS exerts its effect by stimulating vagal afferent and efferent fibers, which project upward to the brainstem nuclei and the relayed circuits and downward to the internal organs to influence the autonomic, neuroendocrine, and neuroimmunology systems. The neuroimmunomodulation effect of VNS is mediated through the cholinergic anti-inflammatory pathway that regulates immune cells and decreases pro-inflammatory cytokines. Traditional and non-invasive VNS have Food and Drug Administration (FDA)-approved indications for patients with drug-refractory epilepsy, treatment-refractory major depressive disorders, and headaches. The number of clinical trials and translational studies that explore the therapeutic potentials and mechanisms of VNS is increasing. In this review, we first introduced the anatomical and physiological bases of the vagus nerve and the immunomodulating functions of VNS. We covered studies that investigated the mechanisms of VNS and its therapeutic implications for a spectrum of brain disorders and systemic diseases in the context of neuroimmunomodulation.

Migraine and treatment-resistant depression

Migraine and major depressive disorders (MDD) or treatment resistant depression (TRD) represent a significant global burden and are often comorbid, further complicating diagnosis and treatment. Epidemiological studies have demonstrated a bidirectional relationship between migraine and MDD/TRD, with patients suffering from one disorder exhibiting a heightened risk of developing the other. This association is believed to result from shared genetic factors, neurotransmitter dysregulation, inflammation, hormonal alteration, and other conditions comorbid with both disorders. Emerging evidence suggests that therapeutics targeting common pathways in both disorders may be beneficial for comorbid patients. Novel therapeutics for migraine or MDD/TRD, such as calcitonin gene-related peptide (CGRP)-targeting therapy, onabotulinumtoxinA, ketamine/esketamine, vagus nerve stimulation or transcranial magnetic stimulation, may be helpful in selected patients with comorbid migraine-MDD/TRD. Nevertheless, continued efforts are needed to improve early detection and intervention, to better understand the complex interplay between genetic, environmental, and psychosocial factors contributing to this comorbidity, to identify novel therapeutic targets, and ultimately, to alleviate the disease burden caused by this comorbidity.

Non-invasive brain stimulation treatments for migraine prophylaxis: a network meta-analysis of randomized controlled trials

BACKGROUND AND OBJECTIVES

Migraine is a major public health problem owing to its long disease duration and disease relapse. Non-invasive brain stimulation treatments were reported effective for the management of migraine, but the comparative effectiveness of three main NIBSs, rTMS, nVNS, and tDCS, has not been studied. We aimed to explore the relative efficacy of rTMS, tDCS, and nVNS in migraine prophylaxis by using network meta-analysis (NMA).

METHODS

We searched OVID Medline, Embase, Cochrane Controlled Register of Trials, and Web of Science from inception to 1 January 2022. Randomized controlled trials that reported the efficacy of rTMS, tDCS or nVNS in the prophylactic treatment of migraine were included. The primary outcome was monthly migraine frequency, and secondary outcomes were headache intensity and the impact of headaches on daily life. The relative effects of the treatments in contrast to the others were measured by using standard mean difference (SMD).

RESULTS

We included 31 trials with 1659 participants. Fourteen trials were rated as low risk of bias. The results showed that tDCS (SMD - 1.58; 95%CI, - 2.38 to  - 0.79; P-score = 0.92) had the largest effect on migraine frequency when compared with sham interventions in reducing monthly migraine frequency, and tDCS had a larger effect than rTMS (SMD - 0.62; 95%CI, - 1.81 to 0.57) and nVNS (SMD - 1.39; 95%CI, - 3.27 to 0.49). tDCS had also the largest effect in reducing pain intensity when compared with sham intervention (SMD - 1.49; 95%CI, - 2.46 to  - 0.52) and rTMS (SMD - 0.48; 95%CI, - 2.06 to 1.09).

CONCLUSIONS

For the prophylactic treatment of migraine, tDCS was relatively more effective than rTMS and nVNS. Head-to-head comparison trials are needed to confirm the findings.

Noninvasive vagus nerve stimulation for migraine: a systematic review and meta-analysis of randomized controlled trials

Background

Medication is commonly used to treat migraine. However, patients may experience adverse events or fail to respond to medication. In recent years, neuromodulation techniques have emerged as potential non-pharmacological therapy for migraine. This article focuses on a systematic review and meta-analysis of randomized controlled trials of non-invasive vagus nerve stimulation (n-VNS) for migraine to determine the efficacy, safety and tolerability of n-VNS.

Methods

We searched PUBMED, EMBASE, and Cochrane Center Register of Controlled Trials databases up to July 15, 2022. Primary outcomes were monthly reduced migraine/headache days, and pain-free rates within 2 h. Secondary outcomes were  ≥ 50% responder rate, headache intensity, monthly acute medication reduction days, and adverse events.

Results

Meta-analysis shows that non-invasive cervical vagus nerve stimulation (n-cVNS) significantly impacted ≥50% responder rate (OR, 1.64; 95% CI, 1.1 to 2.47; p = 0.02), but had no significant effect on reducing migraine days (MD, -0.46; 95% CI, -1.21 to 0.29; p = 0.23) and headache days (MD, -0.68; 95% CI, -1.52 to 0.16; p = 0.11). In contrast, low-frequency non-invasive auricular vagus nerve stimulation (n-aVNS) was found to significantly reduce the number of migraine days (MD, -1.8; 95% CI, -3.34 to -0.26; p = 0.02) and headache intensity (SMD, -0.7; 95% CI, -1.23 to -0.17; p = 0.009), but not the number of acute medication days per month (MD, -1.1; 95% CI, -3.84 to 1.64; p = 0.43). In addition, n-cVNS was found safe and well-tolerated in most patients.

Conclusion

These findings show that n-VNS is a promising method for migraine management.

Clinical benefits and economic cost-savings of Remote Electrical Neuromodulation (REN) for migraine prevention

AIMS

Assess the clinical benefits and associated direct and indirect cost-savings from Remote Electrical Neuromodulation (REN) for migraine prevention.

METHODS

REN, a prescribed, wearable, FDA-cleared neuromodulation-device for the acute and/or treatment of migraine, recently demonstrated efficacy for migraine prevention when used every-other-day, in a prospective, randomized, double-blind, placebo-controlled, multi-center study. Following baseline (4-weeks), subjects underwent treatment with REN (or placebo; 8-weeks), and electronically reported migraine symptoms and acute treatments daily. Therapeutic-gain was the between-groups difference (REN minus placebo) in change from baseline to the second month of intervention. Health-economics impact was derived as cost-savings associated with REN's clinical benefits.

RESULTS

Out of 248 subjects randomized (128 active, 120 placebo), 179 (95:84) qualified for modifiedintention-to-treat (mITT) analysis. Significant therapeutic gains favoring REN vs placebo were found (Tepper et al., 2023), including mean (±SD) reduction in number of acute medication days (3.4 ± 0.4 vs 1.2 ± 0.5; gain = 2.2; p = 0.001) and presenteeism days (2.7 ± 0.3 vs 1.1 ± 0.4; p = 0.001). Mean changes of provider visits (reduction of 0.09 ± 0.1 vs increase of 0.08 ± 0.2; p = 0.297), and reduction of absenteeism days (0.07 ± 0.1 vs 0.07 ± 0.2; p = 0.997) were not significant. Mean annual cost-saving for one patient using REN for migraine prevention estimated $10,000 (±$1,777) from reductions in these four clinical outcomes relative to baseline without REN treatment. Extrapolated to a hypothetical US commercial health-plan of one-million covered lives, assuming the national prevalence of migraine patients on preventive treatment, annual mean (±SE) cost-saving from using REN migraine prevention estimated $560.0 million (±$99.5 million) from reduction in direct and indirect metrics measured.

LIMITATIONS

Clinical and cost-savings benefits presented are conservative, assessed only from endpoints measured in the clinical trial. Moreover, some of the endpoints had only scarce or no occurrences during the study period.

CONCLUSIONS

Demonstrated significant and meaningful clinical, and cost-savings benefits for patients, health insurance systems, and employers, from utilizing REN for migraine prevention.

Migraine: from pathophysiology to treatment

Migraine is an extremely disabling, common neurological disorder characterized by a complex neurobiology, involving a series of central and peripheral nervous system areas and networks. A growing increase in the understanding of migraine pathophysiology in recent years has facilitated translation of that knowledge into novel treatments, which are currently becoming available to patients in many parts of the world and are substantially changing the clinical approach to the disease. In the first part of this review, we will provide an up to date overview of migraine pathophysiology by analyzing the anatomy and function of the main regions involved in the disease, focusing on how these give rise to the plethora of symptoms characterizing the attacks and overall disease. The second part of the paper will discuss the novel therapeutic agents that have emerged for the treatment of migraine, including molecules targeting calcitonin gene-related peptide (gepants and monoclonal antibodies), serotonin 5-HT_1F receptor agonists (ditans) and non-invasive neuromodulation, as well as providing a brief overview of new evidence for classic migraine treatments.

Primary headache disorders: From pathophysiology to neurostimulation therapies

Primary headache disorders including migraine, cluster headache, and tension-type headache are among the most common disabling diseases worldwide. The unclear pathogenesis of primary headache disorders has led to high rates of misdiagnosis and limited available treatment options. In this review, we have summarized the pathophysiological factors for a better understanding of primary headache disorders. Advances in functional neuroimaging, genetics, neurophysiology have indicated that cortical hyperexcitability, regional brain dysfunction, central sensitization and neuroplasticity changes play vital roles in the development of primary headache disorders. Moreover, we have also discussed a series of neurostimulation approaches with their stimulation mechanism, safety and efficacy for prevention and treatment of primary headache disorders. Noninvasive or implantable neurostimulation techniques show great promise for treating refractory primary headache disorders.

Oxygen inhalation has no effect on provoked cranial autonomic symptoms using kinetic oscillation stimulation in healthy volunteers

OBJECTIVE

Inhalation of oxygen is highly effective in cluster headache, a subtype of trigeminal autonomic cephalgias. Since oxygen has no effect on nociceptive pain, the mechanism of action is still unknown. The present study investigated whether oxygen inhalation modifies the trigeminal autonomic reflex arc in healthy volunteers.

METHODS

21 healthy volunteers participated in a randomized, placebo controlled, double-blind, cross-over, and within-subject study design. In a randomized order demand valve inhalation of 100% oxygen or medical air were administered. Capillary blood samples were collected to control for blood gas changes. Cranial parasympathetic output (lacrimation) was provoked using kinetic oscillation stimulation of the nasal mucosa. Standardized measurement of lacrimation between baseline and kinetic oscillation stimulation served as a measure of induced cranial autonomic output.

RESULTS

There was no significant difference in parasympathetic output after oxygen inhalation when compared to inhalation of medical air.

CONCLUSION

The inhalation of 100% oxygen does not affect the parasympathetic reflex arc of the trigeminal autonomic reflex.

Non-invasive neuromodulation of the cervical vagus nerve in rare primary headaches

Primary headache disorders can be remarkably disabling and the therapeutic options available are usually limited to medication with a high rate of adverse events. Here, we discuss the mechanism of action of non-invasive vagal nerve stimulation, as well as the findings of the main studies involving patients with primary headaches other than migraine or cluster headache, such as hemicrania continua, paroxysmal hemicrania, cough headache, or short-lasting neuralgiform headache attacks (SUNCT/SUNA), in a narrative analysis. A bibliographical search of low-prevalence disorders such as rare primary headaches retrieves a moderate number of studies, usually underpowered. Headache intensity, severity, and duration showed a clinically significant reduction in the majority, especially those involving indomethacin-responsive headaches. The lack of response of some patients with a similar diagnosis could be due to a different stimulation pattern, technique, or total dose. The use of non-invasive vagal nerve stimulation for the treatment of primary headache disorders represents an excellent option for patients with these debilitating and otherwise refractory conditions, or that cannot tolerate several lines of preventive medication, and should always be considered before contemplating invasive, non-reversible stimulation techniques.

Remote electrical neuromodulation for migraine prevention: A double-blind, randomized, placebo-controlled clinical trial

OBJECTIVE

To assess the clinical efficacy of remote electrical neuromodulation (REN), used every other day, for the prevention of migraine.

BACKGROUND

Preventive treatment is key to managing migraine, but it is often underutilized. REN, a non-pharmacological acute treatment for migraine, was evaluated as a method of migraine prevention in patients with episodic and chronic migraine.

METHODS

We conducted a prospective, randomized, double-blind, placebo-controlled, multi-center trial, with 1:1 ratio. The study consisted of a 4-week baseline observation phase, and an 8-week double-blind intervention phase in which participants used either REN or a placebo stimulation every other day. Throughout the study, participants reported their symptoms daily, via an electronic diary.

RESULTS

Two hundred forty-eight participants were randomized (128 active, 120 placebo), of which 179 qualified for the modified intention-to-treat (mITT) analysis (95 active; 84 placebo). REN was superior to placebo in the primary endpoint, change in mean number of migraine days per month from baseline, with mean reduction of 4.0 ± SD of 4.0 days (1.3 ± 4.0 in placebo, therapeutic gain = 2.7 [confidence interval -3.9 to -1.5], p < 0.001). The significance was maintained when analyzing the episodic (-3.2 ± 3.4 vs. -1.0 ± 3.6, p = 0.003) and chronic (-4.7 ± 4.4 vs. -1.6 ± 4.4, p = 0.001) migraine subgroups separately. REN was also superior to placebo in reduction of moderate/severe headache days (3.8 ± 3.9 vs. 2.2 ± 3.6, p = 0.005), reduction of headache days of all severities (4.5 ± 4.1 vs. 1.8 ± 4.6, p < 0.001), percentage of patients achieving 50% reduction in moderate/severe headache days (51.6% [49/95] vs. 35.7% [30/84], p = 0.033), and reduction in days of acute medication intake (3.5 ± 4.1 vs. 1.4 ± 4.3, p = 0.001). Similar results were obtained in the ITT analysis. No serious device-related adverse events were reported in any group.

CONCLUSION

Applied every other day, REN is effective and safe for the prevention of migraine.

Novel Therapeutic Targets for Migraine

Migraine, a primary headache disorder involving a dysfunctional trigeminal vascular system, remains a major debilitating neurological condition impacting many patients' quality of life. Despite the success of multiple new migraine therapies, not all patients achieve significant clinical benefits. The success of CGRP pathway-targeted therapy highlights the importance of translating the mechanistic understanding toward effective therapy. Ongoing research has identified multiple potential mechanisms in migraine signaling and nociception. In this narrative review, we discuss several potential emerging therapeutic targets, including pituitary adenylate cyclase-activating polypeptide (PACAP), adenosine, δ-opioid receptor (DOR), potassium channels, transient receptor potential ion channels (TRP), and acid-sensing ion channels (ASIC). A better understanding of these mechanisms facilitates the discovery of novel therapeutic targets and provides more treatment options for improved clinical care.

Novel Migraine Treatments: A Review

Aims: To present a review of the mechanisms of action, available clinical data, and safety profiles of novel migraine therapeutics to inform practice. Methods: PubMed, Medline, and Google Scholar were searched for randomized controlled trials (24 publications), review articles (15 publications), and other pertinent literature (16 publications) discussing the novel migraine therapeutics available between the years 2010 and 2021. All publications were reviewed to assess the mechanism of action, relevant clinical data, and side effect profile for each novel treatment. Therapeutic gain was also recorded in studies that included a placebo arm. Results: A total of 55 studies were included in the final analysis. In the preventive treatment of migraine, novel medications target calcitonin gene-related peptide (CGRP) and fall into either the monoclonal anti-CGRP or gepant class. For the acute treatment of migraine, novel medications fall into either the ditan or gepant class. Several medical devices have been developed for the acute and preventive treatment of migraine. Conclusion: Novel therapeutics are available for both the prevention and acute treatment of migraine headaches. These new medications and neuromodulatory devices appear overall to be safe and effective in the management of migraine headaches.

Outpatient Approach to Resistant and Refractory Migraine in Children and Adolescents: a Narrative Review

PURPOSE OF REVIEW

Migraine is one of the top reasons for consulting a pediatric neurologist. Although the majority of children and adolescents who receive evidence-based first-line interventions for migraine will improve substantially, a subset of patients develop resistant or refractory migraine.

RECENT FINDINGS

In this review, we summarize the level of evidence for a variety of acute and preventive treatment options to consider in children and adolescents with resistant or refractory migraine. We describe the level of evidence for interventional procedures (onabotulinumtoxinA injections, greater occipital and other nerve blocks), neuromodulation (single-pulse transcranial magnetic stimulation, external trigeminal nerve stimulation, remote electrical neuromodulation, and non-invasive vagal nerve stimulation), calcitonin gene-related peptide (CGRP) pathway antagonists (anti-CGRP monoclonal antibodies and gepants), psychological therapies, and manual therapies (acupuncture, craniosacral therapy, massage and physical therapy, and spinal manipulation).

Vagus nerve stimulation as a novel treatment for systemic lupus erythematous: study protocol for a randomised, parallel-group, sham-controlled investigator-initiated clinical trial, the SLE-VNS study

INTRODUCTION

Systemic lupus erythematosus (SLE) is a chronic autoimmune disease. SLE is treated with immunosuppressants with suboptimal efficacy and high risk of serious side effects. Patients with SLE have increased risk of mortality, organ damage and debilitating treatment-resistant fatigue. Autonomic nervous system dysfunction (AD) is present in approximately half of the patients and may promote autoimmunity by weakening the vagally mediated anti-inflammatory reflex. Recent studies suggest that transcutaneous vagus nerve stimulation (tVNS) has few side effects and beneficial effects on fatigue, pain, disease activity and organ function. This study investigates whether adjuvant tVNS improves measures of fatigue (primary end point), AD, clinical disease activity, inflammation, pain, organ function and quality of life.Hence, this study will contribute to the understanding of AD as a potentially important precursor of fatigue, disease activity, progression and complications in SLE, and how tVNS mechanistically may attenuate this. As adjuvant tVNS use may reduce the need for traditional immunosuppressive therapy, this trial may prompt a shift in the treatment of SLE and potentially other autoimmune disorders.

METHODS AND ANALYSIS

Eighty-four patients with SLE with fatigue and AD will be randomised 1:1 to active or sham tVNS in this double-blinded parallel-group study. In period 1 (1 week), participants will receive a 4 min tVNS 4 times daily and report on fatigue daily. After a 2-week pause, period 2 (8 weeks) will entail tVNS twice daily and participants will report on fatigue, pain and disease activity weekly. Secondary end points will be assessed before and after each period and after 1 week in period 2.

ETHICS AND DISSEMINATION

The study is approved by the Danish Medical Research Ethical Committees (case no: 2120231) and results will be published in international peer-reviewed journals.

TRIAL REGISTRATION NUMBER

NCT05315739.

The Role of the Autonomic Nervous System in Headache: Biomarkers and Treatment

Purpose of Review

In this review, the role of the autonomic nervous system in tension-type headache and migraine is reviewed.

Recent Findings

A pathophysiological model for tension-type headache is proposed that is compatible with most physiological and behavioral literature.

Summary

A treatment protocol is described that follows from this model. For migraine, incorporating autonomic factors into the pathophysiology offers rationales for behavioral interventions that have been shown to be useful in migraine treatment and a biofeedback protocol is proposed.

Predicting response to tVNS in patients with migraine using functional MRI: A voxels-based machine learning analysis

Background

Migraine is a common disorder, affecting many patients. However, for one thing, lacking objective biomarkers, misdiagnosis, and missed diagnosis happen occasionally. For another, though transcutaneous vagus nerve stimulation (tVNS) could alleviate migraine symptoms, the individual difference of tVNS efficacy in migraineurs hamper the clinical application of tVNS. Therefore, it is necessary to identify biomarkers to discriminate migraineurs as well as select patients suitable for tVNS treatment.

Methods

A total of 70 patients diagnosed with migraine without aura (MWoA) and 70 matched healthy controls were recruited to complete fMRI scanning. In study 1, the fractional amplitude of low-frequency fluctuation (fALFF) of each voxel was calculated, and the differences between healthy controls and MWoA were compared. Meaningful voxels were extracted as features for discriminating model construction by a support vector machine. The performance of the discriminating model was assessed by accuracy, sensitivity, and specificity. In addition, a mask of these significant brain regions was generated for further analysis. Then, in study 2, 33 of the 70 patients with MWoA in study 1 receiving real tVNS were included to construct the predicting model in the generated mask. Discriminative features of the discriminating model in study 1 were used to predict the reduction of attack frequency after a 4-week tVNS treatment by support vector regression. A correlation coefficient between predicted value and actual value of the reduction of migraine attack frequency was conducted in 33 patients to assess the performance of predicting model after tVNS treatment. We vislized the distribution of the predictive voxels as well as investigated the association between fALFF change (post-per treatment) of predict weight brain regions and clinical outcomes (frequency of migraine attack) in the real group.

Results

A biomarker containing 3,650 features was identified with an accuracy of 79.3%, sensitivity of 78.6%, and specificity of 80.0% (p &lt; 0.002). The discriminative features were found in the trigeminal cervical complex/rostral ventromedial medulla (TCC/RVM), thalamus, medial prefrontal cortex (mPFC), and temporal gyrus. Then, 70 of 3,650 discriminative features were identified to predict the reduction of attack frequency after tVNS treatment with a correlation coefficient of 0.36 (p = 0.03). The 70 predictive features were involved in TCC/RVM, mPFC, temporal gyrus, middle cingulate cortex (MCC), and insula. The reduction of migraine attack frequency had a positive correlation with right TCC/RVM (r = 0.433, p = 0.021), left MCC (r = 0.451, p = 0.016), and bilateral mPFC (r = 0.416, p = 0.028), and negative with left insula (r = −0.473, p = 0.011) and right superior temporal gyrus/middle temporal gyrus (r = −0.684, p &lt; 0.001), respectively.

Conclusions

By machine learning, the study proposed two potential biomarkers that could discriminate patients with MWoA and predict the efficacy of tVNS in reducing migraine attack frequency. The pivotal features were mainly located in the TCC/RVM, thalamus, mPFC, and temporal gyrus.

Manipulation of the inflammatory reflex as a therapeutic strategy

The cholinergic anti-inflammatory pathway is the efferent arm of the inflammatory reflex, a neural circuit through which the CNS can modulate peripheral immune responses. Signals communicated via the vagus and splenic nerves use acetylcholine, produced by Choline acetyltransferase (ChAT)+ T cells, to downregulate the inflammatory actions of macrophages expressing α7 nicotinic receptors. Pre-clinical studies using transgenic animals, cholinergic agonists, vagotomy, and vagus nerve stimulation have demonstrated this pathway's role and therapeutic potential in numerous inflammatory diseases. In this review, we summarize what is understood about the inflammatory reflex. We also demonstrate how pre-clinical findings are being translated into promising clinical trials, and we draw particular attention to innovative bioelectronic methods of harnessing the cholinergic anti-inflammatory pathway for clinical use.

Vagus nerve stimulation for conservative therapy-refractive epilepsy and depression

Numerous studies confirm that the vagus nerve stimulation (VNS) is an efficient, indirect neuromodulatory therapy with electrically induced current for epilepsy that cannot be treated by epilepsy surgery and is therapy-refractory and for drug therapy-refractory depression. VNS is an established, evidence-based and in the long-term cost-effective therapy in an interdisciplinary overall concept.Long-term data on the safety and tolerance of the method are available despite the heterogeneity of the patient populations. Stimulation-related side effects like hoarseness, paresthesia, cough or dyspnea depend on the stimulation strength and often decrease with continuing therapy duration in the following years. Stimulation-related side effects of VNS can be well influenced by modifying the stimulation parameters. Overall, the invasive vagus nerve stimulation may be considered as a safe and well-tolerated therapy option.For invasive and transcutaneous vagus nerve stimulation, antiepileptic and antidepressant as well as positive cognitive effects could be proven. In contrast to drugs, VNS has no negative effect on cognition. In many cases, an improvement of the quality of life is possible.iVNS therapy has a low probability of complete seizure-freedom in cases of focal and genetically generalized epilepsy. It must be considered as palliative therapy, which means that it does not lead to healing and requires the continuation of specific medication. The functional principle is a general reduction of the neuronal excitability. This effect is achieved by a slow increase of the effectiveness sometimes over several years. Responders are those patients who experience a 50% reduction of the seizure incidence. Some studies even reveal seizure-freedom in 20% of the cases. Currently, it is not possible to differentiate between potential responders and non-responders before therapy/implantation.The current technical developments of the iVNS generators of the new generation like closed-loop system (cardiac-based seizure detection, CBSD) reduce also the risk for SUDEP (sudden unexpected death in epilepsy patients), a very rare, lethal complication of epilepsies, beside the seizure severity.iVNS may deteriorate an existing sleep apnea syndrome and therefore requires possible therapy interruption during nighttime (day-night programming or magnet use) beside the close cooperation with sleep physicians.The evaluation of the numerous iVNS trials of the past two decades showed multiple positive effects on other immunological, cardiological, and gastroenterological diseases so that additional therapy indications may be expected depending on future study results. Currently, the vagus nerve stimulation is in the focus of research in the disciplines of psychology, immunology, cardiology as well as pain and plasticity research with the desired potential of future medical application.Beside invasive vagus nerve stimulation with implantation of an IPG and an electrode, also devices for transdermal and thus non-invasive vagus nerve stimulation have been developed during the last years. According to the data that are currently available, they are less effective with regard to the reduction of the seizure severity and duration in cases of therapy-refractory epilepsy and slightly less effective regarding the improvement of depression symptoms. In this context, studies are missing that confirm high evidence of effectiveness. The same is true for the other indications that have been mentioned like tinnitus, cephalgia, gastrointestinal complaints etc. Another disadvantage of transcutaneous vagus nerve stimulation is that the stimulators have to be applied actively by the patients and are not permanently active, in contrast to implanted iVNS therapy systems. So they are only intermittently active; furthermore, the therapy adherence is uncertain.

Outcomes of transcutaneous nerve stimulation for migraine headaches: a systematic review and meta-analysis

BACKGROUND

Implanted and transcutaneous nerve stimulators have shown promise as novel non-pharmacologic treatment for episodic and chronic migraines. The purpose of this study was to summarize the reported efficacy of transcutaneous single nerve stimulators in management of migraine frequency and severity.

METHODS

A systematic review of five databases identified studies treating migraines with transcutaneous stimulation of a single nerve. Random effects model meta-analyses were conducted to establish the effect of preventive transcutaneous nerve stimulation on headache days per month and 0-10 numeric rating scale pain severity of headaches for both individuals with episodic and chronic migraines.

RESULTS

Fourteen studies, which treated 995 patients, met inclusion criteria, including 7 randomized controlled trials and 7 uncontrolled clinical trials. Transcutaneous nerve stimulators reduced headache frequency in episodic migraines (2.81 fewer headache days per month, 95% CI 2.18-3.43, I² = 21%) and chronic migraines (2.97 fewer headache days per month, 95% CI 1.66-4.28, I² = 0%). Transcutaneous nerve stimulators reduced headache severity in episodic headaches (2.23 fewer pain scale points, 95% CI 1.64-2.81, I² = 88%).

CONCLUSIONS

Preventive use of transcutaneous nerve stimulators provided clinically significant reductions in headache frequency in individuals with chronic or episodic migraines. Individuals with episodic migraines also experienced a reduction in headache pain severity following preventive transcutaneous nerve stimulation.

Devices for Episodic Migraine: Past, Present, and Future

PURPOSE OF REVIEW

Historically, therapies for migraine have generally involved pharmacological treatments using non-selective or selective analgesics and preventive treatments. However, for many patients these treatments are not effective, while others prefer to use non-pharmacological-based therapies. To fill this need, over the last 15 years, neuromodulatory devices have entered the market for migraine treatment. Here, we will review the most recent findings for the use of these devices in the treatment of migraine.

RECENT FINDINGS

Non-invasive vagus nerve stimulation and spring-pulse transcranial magnetic stimulation are both cleared for the treatment of migraine, supported by preclinical studies that validate efficacy and mechanism of action, and complemented with clinical trial data. Other options also authorized for use include transcutaneous supraorbital nerve stimulation and remote electrical neuromodulation. Various options are available to treat migraine using authorized neuromodulatory devices. These data support their efficacy in the treatment of episodic migraine, although further studies are necessary to elucidate their mechanism of action and to provide rigor to clinical trial data.

Early Fractional Amplitude of Low Frequency Fluctuation Can Predict the Efficacy of Transcutaneous Auricular Vagus Nerve Stimulation Treatment for Migraine Without Aura

Migraine is a common primary headache disorder. Transcutaneous auricular vagus nerve stimulation (taVNS) has been verified to be effective in patients with migraine without aura (MWoA). However, there are large interindividual differences in patients’ responses to taVNS. This study aimed to explore whether pretreatment fractional amplitude of low frequency fluctuation (fALFF) features could predict clinical outcomes in MWoA patients after 4-week taVNS. Sixty MWoA patients and sixty well-matched healthy controls (HCs) were recruited, and migraineurs received 4-week taVNS treatment. Resting-state functional magnetic resonance imaging (rs-fMRI) data were collected, and the significant differences of fALFF were detected between MWoA patients and HCs using two-sample t-test. A mask of these significant regions was generated and used for subsequent analysis. The abnormal fALFF in the mask was used to predict taVNS efficacy for MWoA using a support vector regression (SVR) model combining with feature select of weight based on the LIBSVM toolbox. We found that (1) compared with HCs, MWoA patients exhibited increased fALFF in the left thalamus, left inferior parietal gyrus (IPG), bilateral precentral gyrus (PreCG), right postcentral gyrus (PoCG), and bilateral supplementary motor areas (SMAs), but decreased in the bilateral precuneus and left superior frontal gyrus (SFG)/medial prefrontal cortex (mPFC); (2) after 4-week taVNS treatment, the fALFF values significantly decreased in these brain regions based on the pretreatment comparison. Importantly, the decreased fALFF in the bilateral precuneus was positively associated with the reduction in the attack times (r = 0.357, p = 0.005, Bonferroni correction, 0.05/5), whereas the reduced fALFF in the right PoCG was negatively associated with reduced visual analog scale (VAS) scores (r = −0.267, p = 0.039, uncorrected); (3) the SVR model exhibited a good performance for prediction (r = 0.411, p < 0.001),which suggests that these extracted fALFF features could be used as reliable biomarkers to predict the treatment response of taVNS for MWoA patients. This study demonstrated that the baseline fALFF features have good potential for predicting individualized treatment response of taVNS in MWoA patients, and those weight brain areas are mainly involved in the thalamocortical (TC) circuits, default mode network (DMN), and descending pain modulation system (DPMS). This will contribute to well understanding the mechanism of taVNS in treating MWoA patients and may help to screen ideal patients who respond well to taVNS treatment.

Effectiveness and acceptability of noninvasive brain and nerve stimulation techniques for migraine prophylaxis: a network meta-analysis of randomized controlled trials

BACKGROUND

Current pharmacologic prophylactic strategies for migraine have exhibited limited efficacy, with response rates as low as 40%-50%. In addition to the limited efficacy, the acceptability of those pharmacologic prophylactic strategies were unacceptable. Although noninvasive brain/nerve stimulation strategies may be effective, the evidence has been inconsistent. The aim of this network meta-analysis (NMA) was to compare strategies of noninvasive brain/nerve stimulation for migraine prophylaxis with respect to their effectiveness and acceptability.

METHODS

The PubMed, Embase, ScienceDirect, ProQuest, ClinicalTrials.gov , ClinicalKey, Cochrane CENTRAL, Web of Science, and ClinicalTrials.gov databases were systematically searched to date of June 4th, 2021 for randomized controlled trials (RCTs). Patients with diagnosis of migraine, either episodic migraine or chronic migraine, were included. All NMA procedures were conducted under the frequentist model.

RESULTS

Nineteen RCTs were included (N = 1493; mean age = 38.2 years; 82.0% women). We determined that the high frequency repetitive transcranial magnetic stimulation (rTMS) over C3 yielded the most decreased monthly migraine days among all the interventions [mean difference = - 8.70 days, 95% confidence intervals (95%CIs): - 14.45 to - 2.95 compared to sham/control groups]. Only alternating frequency (2/100 Hz) transcutaneous occipital nerve stimulation (tONS) over the Oz (RR = 0.36, 95%CIs: 0.16 to 0.82) yielded a significantly lower drop-out rate than the sham/control groups did.

CONCLUSIONS

The current study provided a new direction for the design of more methodologically robust and larger RCTs based on the findings of the potentially beneficial effect on migraine prophylaxis in participants with migraine by different noninvasive brain/nerve stimulation, especially the application of rTMS and tONS.

TRIAL REGISTRATION

CRD42021252638. The current study had been approval by the Institutional Review Board of the Tri-Service General Hospital, National Defense Medical Center (TSGHIRB No. B-109-29).

Efficacy profile of noninvasive vagus nerve stimulation on cortical spreading depression susceptibility and the tissue response in a rat model

Background

Noninvasive vagus nerve stimulation (nVNS) has recently emerged as a promising therapy for migraine. We previously demonstrated that vagus nerve stimulation inhibits cortical spreading depression (CSD), the electrophysiological event underlying migraine aura and triggering headache; however, the optimal nVNS paradigm has not been defined.

Methods

Various intensities and doses of nVNS were tested to improve efficacy on KCl-evoked CSD frequency and electrical threshold of CSD in a validated rat model. Chronic efficacy was evaluated by daily nVNS delivery for four weeks. We also examined the effects of nVNS on neuroinflammation and trigeminovascular activation by western blot and immunohistochemistry.

Results

nVNS suppressed susceptibility to CSD in an intensity-dependent manner. Two 2-minute nVNS 5 min apart afforded the highest efficacy on electrical CSD threshold and frequency of KCl-evoked CSD. Daily nVNS for four weeks did not further enhance efficacy over a single nVNS 20 min prior to CSD. The optimal nVNS also attenuated CSD-induced upregulation of cortical cyclooxygenase-2, calcitonin gene-related peptide in trigeminal ganglia, and c-Fos expression in trigeminal nucleus caudalis.

Conclusions

Our study provides insight on optimal nVNS parameters to suppress CSD and suggests its benefit on CSD-induced neuroinflammation and trigeminovascular activation in migraine treatment.

Supplementary Information

The online version contains supplementary material available at 10.1186/s10194-022-01384-1.

Non-invasive vagus nerve stimulation for prevention of migraine: The multicenter, randomized, double-blind, sham-controlled PREMIUM II trial

AIM

Evaluate the efficacy and safety of non-invasive vagus nerve stimulation for migraine prevention.

METHODS

After completing a 4-week diary run-in period, adults who had migraine with or without aura were randomly assigned to receive active non-invasive vagus nerve stimulation or sham therapy during a 12-week double-blind period.

RESULTS

Of 336 enrolled participants, 113 (active, n = 56; sham, n = 57) completed ≥70 days of the double-blind period and were ≥66% adherent with treatment, comprising the prespecified modified intention-to-treat population. The COVID-19 pandemic led to early trial termination, and the population was ∼60% smaller than the statistical target for full power. Mean reduction in monthly migraine days (primary endpoint) was 3.12 for the active group and 2.29 days for the sham group (difference, -0.83; p = 0.2329). Responder rate (i.e. the percentage of participants with a ≥50% reduction in migraine days) was greater in the active group (44.87%) than the sham group (26.81%; p = 0.0481). Prespecified subgroup analysis suggested that participants with aura responded preferentially. No serious device-related adverse events were reported.

CONCLUSIONS

These results suggest clinical utility of non-invasive vagus nerve stimulation for migraine prevention, particularly for patients who have migraine with aura, and reinforce the well-established safety and tolerability profile of this therapy.Trial Registration: ClinicalTrials.gov (NCT03716505).

Role of the Cholinergic Anti-Inflammatory Reflex in Central Nervous System Diseases

In several central nervous system diseases, it has been reported that inflammation may be related to the etiologic process, therefore, therapeutic strategies are being implemented to control inflammation. As the nervous system and the immune system maintain close bidirectional communication in physiological and pathological conditions, the modulation of inflammation through the cholinergic anti-inflammatory reflex has been proposed. In this review, we summarized the evidence supporting chemical stimulation with cholinergic agonists and vagus nerve stimulation as therapeutic strategies in the treatment of various central nervous system pathologies, and their effect on inflammation.

tVNS in the management of headache and pain

First clinical observations of the therapeutic effect of vagus nerve stimulation were of patients who were treated for refractory epilepsy with a fully implanted vagus nerve stimulator, who also reported an improvement of their migraine and cluster headache. With the development of non-invasive vagus nerve stimulation, first clinical studies concerning a possible therapeutic effect in migraine and cluster headache were performed. In a controlled study, transcutaneous cervical vagus nerve stimulation (tcVNS) showed a significant but limited effect in acute treatment of a migraine attack. There was no significant prophylactic effect in episodic migraine. Concerning cluster headache, there was a clear beneficial effect in the prophylaxis of chronic cluster headache and in the attack treatment in episodic cluster headache. There are fewer studies in the literature on the effect of transcutaneous auricular vagus nerve stimulation (taVNS), with a partial overlap with studies on electrical ear acupuncture. In a small controlled clinical trial, there was a significant effect of taVNS in the prevention of chronic migraine. In less defined clinical studies, there were some positive signs that the method may be beneficial in chronic back pain and in unspecific gastro-intestinal pain in adolescents. Based on the available evidence, it is probable that vagus nerve stimulation can have a clinically meaningful influence on pain syndromes, but there are still several questions (e.g. frequency of the stimulation; duration of the stimulation; differential effects of auricular vagus stimulation and cervical vagus stimulation) to answer before vagus stimulation can be used widely in the clinic.

The Use of Electrical Nerve Stimulation to Treat Migraines: A Systematic Review

Migraines have been defined as an intense unilateral throbbing or pulsating sensation lasting anywhere between a few hours to multiple days. They are the sixth most prevalent disease in the United States, with approximately 18% of women and 6% of men experiencing some form of a migraine throughout their lifetime. In addition, they pose a significant economic burden, accounting for anywhere between $13 and $17 billion in medical costs annually in the United States. While there are a wide variety of treatments for migraines on the market, such as nonsteroidal anti-inflammatory drugs (NSAIDS), beta-blockers, and anti-epileptics, there is still no standard treatment. Moreover, each of these medications has a wide range of side effects, ranging from stomach ulcers to light-headedness. Within the last few decades, the presence of electrical nerve stimulation has emerged as a possible treatment option. These methods are almost free of harmful side effects and may be able to reduce the economic burden on those who suffer from migraines. However, studies have shown mixed results in regard to their efficacy. In this paper, we performed a systematic review to detail the current state of the literature regarding electrical nerve stimulation as a treatment modality for migraines.

Revised guidelines of the French headache society for the diagnosis and management of migraine in adults. Part 3: Non-pharmacological treatment

The French Headache Society proposes updated French guidelines for the management of migraine. This article presents the third part of the guidelines, which is focused on the non-pharmacological treatment of migraine, including physical exercise, dietary supplements and plants, diets, neuromodulation therapies, acupuncture, behavioral interventions and mindfulness therapy, patent foramen ovale closure and surgical nerve decompression.

Non-Invasive Neurostimulation Methods for Acute and Preventive Migraine Treatment-A Narrative Review

Neurostimulation methods have now been studied for more than 20 years in migraine treatment. They can be divided into invasive and non-invasive methods. In this narrative review, the non-invasive methods are presented. The most commonly studied and used methods are vagal nerve stimulation, electric peripheral nerve stimulation, transcranial magnetic stimulation, and transcranial direct current stimulation. Other stimulation techniques, including mechanical stimulation, play only a minor role. Nearly all methods have been studied for acute attack treatment and for the prophylactic treatment of migraine. The evidence of efficacy is poor for most procedures, since no stimulation device is based on consistently positive, blinded, controlled trials with a sufficient number of patients. In addition, most studies on these devices enrolled patients who did not respond sufficiently to oral drug treatment, and so the role of neurostimulation in an average population of migraine patients is unknown. In the future, it is very important to conduct large, properly blinded and controlled trials performed by independent researchers. Otherwise, neurostimulation methods will only play a very minor role in the treatment of migraine.

Future prophylactic treatments in migraine: Beyond anti-CGRP monoclonal antibodies and gepants

Migraine is ranked as a leading cause of years lived with disability among all neurological disorders. Therapies targeting the calcitonin gene-related peptide (CGRP) signaling pathway, including monoclonal antibodies against the receptor or ligand and small molecule CGRP receptor antagonists (gepants), are today approved for migraine prophylaxis with additional compounds expected to be introduced to the market soon. In this review, we consider other putative prophylactic migraine drugs in development, including compounds targeting G-protein coupled receptors, glutamate, ion channels, and neuromodulatory devices. Emergence of these new interventions could complement our current treatment armamentarium for migraine management.

Updated review on the link between cortical spreading depression and headache disorders

INTRODUCTION

Experimental animal studies have revealed mechanisms that link cortical spreading depression (CSD) to the trigeminal activation mediating lateralized headache. However, conventional CSD as seen in lissencephalic brain is insufficient to explain some clinical features of aura and migraine headache.

AREAS COVERED

The importance of CSD in headache development including dysfunction of the thalamocortical network, neuroinflammation, calcitonin gene-related peptide, transgenic models, and the role of CSD in migraine triggers, treatment options, neuromodulation and future directions are reviewed.

EXPERT OPINION

The conventional understanding of CSD marching across the hemisphere is invalid in gyrencephalic brains. Thalamocortical dysfunction and interruption of functional cortical network systems by CSD, may provide alternative explanations for clinical manifestations of migraine phases including aura. Not all drugs showing CSD blocking properties in lissencephalic brains, have efficacy in migraine headache and monoclonal antibodies against CGRP ligand/receptors which are effective in migraine treatment, have no impact on aura in humans or CSD properties in rodents. Functional networks and molecular mechanisms mediating and amplifying the effects of limited CSD in migraine brain remain to be investigated to define new targets.

Noninvasive Neuromodulation in Headache: An Update

Background

Migraine is a common disabling primary headache condition. Although strives have been made in treatment, there remains an unmet need for safe, effective acute, and preventative treatments. The promising concept of neuromodulation of relevant neuronal targets in a noninvasive fashion for the treatment of primary headache disorders has led to the trial of numerous devices over the years.

Objective

We aimed to review the evidence on current neuromodulation treatments available for the management of primary headache disorders.

Methods

Randomized controlled trial as well as open-label and real-world studies on central and peripheral cephalic and noncephalic neuromodulation modalities in primary headaches were critically reviewed.

Results

The current evidence suggests a role of single-pulse transcranial magnetic stimulation, supraorbital nerve stimulation, and remote noncephalic electrical stimulation as migraine abortive treatments, with stronger evidence in episodic rather than in chronic migraine. Single-pulse transcranial magnetic stimulation and supraorbital nerve stimulation also hold promising evidence in episodic migraine prevention and initial positive evidence in chronic migraine prevention. More evidence should clarify the therapeutic role of the external vagus nerve stimulation and transcranial direct current stimulation in migraine. However, external vagus nerve stimulation may be effective in the acute treatment of episodic but not chronic cluster headache, in the prevention of hemicrania continua and paroxysmal hemicrania but not of short-lasting neuralgiform headache attacks. The difficulty in setting up sham-controlled studies has thus far prevented the publication of robust trials. This limitation along with the cost of these therapies has meant that their use is limited in most countries.

Conclusion

Neuromodulation is a promising nonpharmacological treatment approach for primary headaches. More studies with appropriate blinding strategies and reduction of device cost may allow more widespread approval of these treatments and in turn increase clinician's experience in neuromodulation.

Vagus nerve stimulation inhibits cortical spreading depression exclusively through central mechanisms

Experimental and clinical data strongly support vagus nerve stimulation (VNS) as a novel treatment in migraine. Vagus nerve stimulation acutely suppresses cortical spreading depression (CSD) susceptibility, an experimental model that has been used to screen for migraine therapies. However, mechanisms underlying VNS efficacy on CSD are unknown. Here, we interrogated the central and peripheral mechanisms using VNS delivered either invasively (iVNS) or noninvasively (nVNS) in male Sprague-Dawley rats. Cortical spreading depression susceptibility was evaluated 40 minutes after the stimulation. iVNS elevated the electrical CSD threshold more than 2-fold and decreased KCl-induced CSD frequency by 22% when delivered to intact vagus nerve. Distal vagotomy did not alter iVNS efficacy (2-fold higher threshold and 19% lower frequency in iVNS vs sham). By contrast, proximal vagotomy completely abolished iVNS effect on CSD. Pharmacological blockade of nucleus tractus solitarius, the main relay for vagal afferents, by lidocaine or glutamate receptor antagonist CNQX also prevented CSD suppression by nVNS. Supporting a role for both norepinephrine and serotonin, CSD suppression by nVNS was inhibited by more than 50% after abrogating norepinephrinergic or serotonergic neurotransmission alone using specific neurotoxins; abrogating both completely blocked the nVNS effect. Our results suggest that VNS inhibits CSD through central afferents relaying in nucleus tractus solitarius and projecting to subcortical neuromodulatory centers providing serotonergic and norepinephrinergic innervation to the cortex.

The bottom-up approach: Non-invasive peripheral neurostimulation methods to treat migraine: A scoping review from the child neurologist's perspective

Migraine is a common and invalidating disorder worldwide. Patients of all ages experience the disorder as very impairing regarding their personal and occupational lives. The current approach in migraine therapy is multimodal including lifestyle management, psychoeducation and, if available, psychotherapeutic interventions, and pharmacotherapy. The lack of non-pharmacological and non-invasive treatment options call for new and innovative therapeutic approaches. Peripheral neurostimulation is a relatively new method in migraine management offering a painless and non-pharmacological way of targeting specific mechanisms involved in migraine. This review summarizes 15 recent randomized clinical trials to provide an overview of non-invasive peripheral neurostimulation methods currently available for the treatment of migraine. Efficacy, tolerability, and safety of the different interventions and their feasibility in the pediatric setting are evaluated. Vagal nerve stimulation (VNS), remote electrical neuromodulation (REN) and supraorbital nerve stimulation (SNS) are considered effective in treating acute migraine attacks, the latter being more pronounced in migraine without aura. Regarding migraine prevention, occipital nerve stimulation (ONS) and supraorbital nerve stimulation (SNS) demonstrated efficacy, whereas repetitive neuromuscular magnetic stimulation (rNMS) may represent a further effective option in episodic migraine. REN and rNMS were found to be well-accepted with fewer patients discontinuing treatment than those receiving direct cranial nerve stimulation. In summary, peripheral neurostimulation represents a promising option to complement the multimodal therapy concept for pediatric migraine. In particular, rNMS opens a new field for research and treatment fitting the requirements of "non-invasiveness" for children. Given the reported efficacy, safety, and feasibility, the therapy decision should be made on an individual level.