Cervical non-invasive vagus nerve stimulation (nVNS) for preventive and acute treatment of episodic and chronic migraine and migraine-associated sleep disturbance: a prospective observational cohort study

Comparison of the efficacy of auricular vagus nerve stimulation and conventional low back rehabilitation in patients with chronic low back pain

BACKGROUND

In recent years, human and animal studies have provided increasing evidence that vagus nerve stimulation (VNS) can produce analgesic effects as well as alleviating resistant epilepsy and depression. Our study was designed to compare the efficacy of transcutaneous auricular vagus nerve stimulation with conventional low back rehabilitation in patients with chronic low back pain (CLBP).

METHODS

Sixty patients with LBP were randomly divided into two groups. Group 1 received conventional rehabilitation and home exercise, and Group 2 received transcutaneous auricular VNS and home exercise. Both groups received treatment five days a week for three weeks. Trunk mobility (Modified Schober test, fingertip-to-floor test), muscle strength (CSMI-Cybex Humac-Norm isokinetic dynamometer and Lafayette manual muscle strength measuring device), trunk endurance, balance tests, Visual Analog Scale, Beck Depression Scale, Pittsburgh Sleep Quality Index, Oswestry Disability Index were evaluated.

RESULTS

At the end of three weeks, within-group assessment results showed positive effects on mobility, functional status, depression and sleep in all groups (p < 0.05). Pain level, endurance time and flexion trunk muscle strength results showed more improvement in Group 2 (p < 0.05). Some parameters of isokinetic lower extremity quadriceps muscle strength and fall risk scores showed a significant improvement in Group 1 (p < 0.05).

DISCUSSION

VNS has been observed to be more effective on pain, trunk muscle strength and endurance duration and sleep status. Auricular VNS may be included in the treatment of patients with CLBP in whom conventional physical therapy is inadequate or not applicable.

Brain effect of transcutaneous vagal nerve stimulation: A meta-analysis of neuroimaging evidence

BACKGROUND

Dysfunction in the autonomic nervous system is common throughout many functional gastrointestinal diseases (FGIDs) that have been historically difficult to treat. In recent years, transcutaneous vagal nerve stimulation (tVNS) has shown promise for improving FGID symptoms. However, the brain effects of tVNS remain unclear, which we investigated by neuroimaging meta-analysis.

METHODS

A total of 157 studies were identified, 4 of which were appropriate for inclusion, encompassing 60 healthy human participants. Using activation likelihood analysis estimation, we statistically quantified functional brain activity changes across three domains: (1) tVNS vs. null stimulation, (2) tVNS vs. sham stimulation, and (3) sham stimulation vs. null stimulation.

KEY RESULTS

tVNS significantly increased activity in the insula, anterior cingulate, inferior and superior frontal gyri, caudate and putamen, and reduced activity in the hippocampi, occipital fusiform gyri, temporal pole, and middle temporal gyri, when compared to null stimulation (all corrected p < 0.005). tVNS increased activity in the anterior cingulate gyrus, left thalamus, caudate, and paracingulate gyrus and reduced activity in right thalamus, posterior cingulate cortex, and temporal fusiform cortex, when compared to sham stimulation (all corrected p < 0.005). Sham stimulation significantly increased activity in the insula and reduced activity in the posterior cingulate and paracingulate gyrus (all corrected p < 0.001), when contrasted to null stimulation.

CONCLUSIONS

Brain effects of tVNS localize to regions associated with both physiological autonomic regulation and regions whose activity is modulated across numerous FGIDs, which may provide a neural basis for efficacy of this treatment. Functional activity differences between sham and null stimulation illustrate the importance of robust control procedures for future trials.

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.

Non-Pharmacological Treatment for Chronic Migraine

PURPOSE OF REVIEW

Chronic migraine (CM) affects a large proportion of the population and is a significant source of disability and lost productivity. Numerous non-pharmacological approaches have been attempted during the past decades. This review discusses the most recent and evidence-based advances in acute and preventive non-pharmacological therapeutic approaches for CM, offering alternatives to drug treatment.

RECENT FINDINGS

A growing number of non-pharmacological treatment options, including non-invasive or invasive neuromodulation, acupuncture, psychotherapy, and physiotherapy, have shown promising efficacy in CM. There is strong evidence for the effectiveness of non-invasive neuromodulation such as transcranial magnetic stimulation, transcranial direct current stimulation, and transcutaneous electrical nerve stimulation (TENS) in CM, but less evidence for approaches such as invasive neuromodulation, physical therapy, or dietary approaches. Acupuncture for migraine remains controversial, with the main point of contention still being the placebo effect. Non-pharmacological approaches can be offered as a reliable alternative for patients with CM, and more research is being done to evaluate the efficacy of non-invasive neuromodulation with different parameters and the combination of different treatments in CM.

Altered functional brain network patterns in patients with migraine without aura after transcutaneous auricular vagus nerve stimulation

Transcutaneous auricular vagus nerve stimulation (taVNS) shows excellent effects on relieving clinical symptoms in migraine patients. Nevertheless, the neurological mechanisms of taVNS for migraineurs remain unclear. In recent years, voxel-wise degree centrality (DC) and functional connectivity (FC) methods were extensively utilized for exploring alterations in patterns of FC in the resting-state brain. In the present study, thirty-five migraine patients without aura and thirty-eight healthy controls (HCs) were recruited for magnetic resonance imaging scans. Firstly, this study used voxel-wise DC analysis to explore brain regions where abnormalities were present in migraine patients. Secondly, for elucidating neurological mechanisms underlying taVNS in migraine, seed-based resting-state functional connectivity analysis was employed to the taVNS treatment group. Finally, correlation analysis was performed to explore the relationship between alterations in neurological mechanisms and clinical symptoms. Our findings indicated that migraineurs have lower DC values in the inferior temporal gyrus (ITG) and paracentral lobule than in healthy controls (HCs). In addition, migraineurs have higher DC values in the cerebellar lobule VIII and the fusiform gyrus than HCs. Moreover, after taVNS treatment (post-taVNS), patients displayed increased FC between the ITG with the inferior parietal lobule (IPL), orbitofrontal gyrus, angular gyrus, and posterior cingulate gyrus than before taVNS treatment (pre-taVNS). Besides, the post-taVNS patients showed decreased FC between the cerebellar lobule VIII with the supplementary motor area and postcentral gyrus compared with the pre-taVNS patients. The changed FC of ITG-IPL was significantly related to changes in headache intensity. Our study suggested that migraine patients without aura have altered brain connectivity patterns in several hub regions involving multisensory integration, pain perception, and cognitive function. More importantly, taVNS modulated the default mode network and the vestibular cortical network related to the dysfunctions in migraineurs. This paper provides a new perspective on the potential neurological mechanisms and therapeutic targets of taVNS for treating migraine.

Effect of transcutaneous auricular vagal nerve stimulation on the fatigue syndrome in patients with gastrointestinal cancers - FATIVA: a randomized, placebo-controlled pilot study protocol

BACKGROUND

Cancer-related fatigue (CRF) is defined as a "distressing, persistent, subjective sense of physical, emotional, and/or cognitive tiredness or exhaustion related to cancer or cancer treatment that is not proportional to recent activity and interferes with usual functioning." CRF is frequently observed in cancer patients even before the initiation of tumor therapy. Its cause is not clear, but in addition to primary effects of therapy, a tumor-induced elevated level of inflammatory cytokines may play a role. Transcutaneous auricular vagal nerve stimulation (taVNS) is a noninvasive way to activate central nervous pathways and modulate pain perception and the immune system. It has positive effects on autoimmune conditions and can also improve fatigue associated with Sjogren's syndrome. It is the main purpose of this feasibility study to investigate the feasibility of daily taVNS against CRF. Therefore, the stimulation protocol of the newly introduced smartphone app of the manufacturer is evaluated. Additionally, the effect taVNS on CRF and quality of life (QoL) shall be evaluated.

METHODS

Thirty adult patients with gastrointestinal tumors during or after treatment, relevant CRF (Hornheide questionnaire) and life expectancy > 1 year, are enrolled. Patients are randomized to treatment or sham arm and be informed that they will either feel the stimulation or not. Treatment group will receive left-sided tragus above-threshold stimulation with 25 Hz, 250 µs pulse width, and 28-s/32-s on/off paradigm for 4 h throughout the day for 4 weeks. Sham group will receive no stimulation via a nonfunctional electrode. A daily stimulation protocol with time and average intensity is automatically created by a smartphone app connected to the stimulator via Bluetooth®. Multidimensional Fatigue Inventory-20, Short-Form 36 and Beck Depression Inventory questionnaires will be filled out before and after 4 weeks of stimulation.

DISCUSSION

Primarily, the patients' daily stimulation time and intensity will be evaluated through the electronic protocol after 4 weeks. Secondarily, the effect of taVNS on cancer-related fatigue and QoL will be measured through the questionnaires. As taVNS seems to modulate inflammatory cytokines, this noninvasive method may - if accepted by the patients - be a promising adjunct in the treatment of cancer-related fatigue.

TRIAL REGISTRATION

The study was approved by local ethics committee (21-7395) and registered at the DRKS database (DRKS00027481).

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.

Pain is reduced by transcutaneous cervical vagus nerve stimulation and correlated with cardiorespiratory variability measures in the context of opioid withdrawal

Over 100,000 individuals in the United States lost their lives secondary to drug overdose in 2021, with opioid use disorder (OUD) being a leading cause. Pain is an important component of opioid withdrawal, which can complicate recovery from OUD. This study's objectives were to assess the effects of transcutaneous cervical vagus nerve stimulation (tcVNS), a technique shown to reduce sympathetic arousal in other populations, on pain during acute opioid withdrawal and to study pain's relationships with objective cardiorespiratory markers. Twenty patients with OUD underwent opioid withdrawal while participating in a two-hour protocol. The protocol involved opioid cues to induce opioid craving and neutral conditions for control purposes. Adhering to a double-blind design, patients were randomly assigned to receive active tcVNS (n = 9) or sham stimulation (n = 11) throughout the protocol. At the beginning and end of the protocol, patients' pain levels were assessed using the numerical rating scale (0–10 scale) for pain (NRS Pain). During the protocol, electrocardiogram and respiratory effort signals were measured, from which heart rate variability (HRV) and respiration pattern variability (RPV) were extracted. Pre- to post- changes (denoted with a Δ) were computed for all measures. Δ NRS Pain scores were lower (P = 0.045) for the active group (mean ± standard deviation: −0.8 ± 2.4) compared to the sham group (0.9 ± 1.0). A positive correlation existed between Δ NRS pain scores and Δ RPV (Spearman's ρ = 0.46; P = 0.04). Following adjustment for device group, a negative correlation existed between Δ HRV and Δ NRS Pain (Spearman's ρ = −0.43; P = 0.04). This randomized, double-blind, sham-controlled pilot study provides the first evidence of tcVNS-induced reductions in pain in patients with OUD experiencing opioid withdrawal. This study also provides the first quantitative evidence of an association between breathing irregularity and pain. The correlations between changes in pain and changes in objective physiological markers add validity to the data. Given the clinical importance of reducing pain non-pharmacologically, the findings support the need for further investigation of tcVNS and wearable cardiorespiratory sensing for pain monitoring and management in patients with OUD.

Assessment of safety and feasibility of non-invasive vagus nerve stimulation for treatment of acute stroke

BACKGROUND

Non-invasive vagus nerve stimulation (nVNS) using a hand-held stimulator placed on the neck is an FDA-approved treatment for primary headache disorders. The safety of nVNS is unknown in stroke patients.

OBJECTIVE

To assess the safety and feasibility of nVNS for the acute treatment of stroke.

METHODS

TR-VENUS (clinicaltrials.gov identifier NCT03733431) was a randomized, sham-controlled, open-label, multicenter trial conducted in patients with acute ischemic stroke (IS) or intracerebral hemorrhage (ICH). Patients were randomly assigned to standard-dose nVNS, high-dose nVNS, or sham stimulation. The primary endpoint was a composite safety outcome defined as bradycardia or reduction in mean arterial blood pressure during treatment or progression of neurological or death within 24 h of treatment. The feasibility endpoints were the proportion of eligible subjects receiving nVNS within 6 h of symptom onset and the proportion completing all pre-specified treatment doses. Efficacy assessments included infarct growth from baseline to 24 h after treatment.

RESULTS

Sixty-nine patients (61 IS, 8 ICH) completed the study. The composite safety outcome was achieved in 32.0% in sham and 47.7% in nVNS group (p = 0.203). Treatment was initiated in all but two randomized patients. All dosed subjects received 100% of prespecified stimulations. A non-significant reduction in infarct growth was observed in the high-dose nVNS group (184.2% in sham vs. 63.3% in high-dose nVNS; p = 0.109).

CONCLUSIONS

The results of this study suggest that nVNS may be safe and feasible in the setting of acute stroke. These findings support further development of nVNS as a potential treatment for acute ischemic stroke.

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.

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.

Neuromodulation for Chronic Daily Headache

Purpose of Review

We reviewed the literature that explored the use of central and peripheral neuromodulation techniques for chronic daily headache (CDH) treatment.

Recent Findings

Although the more invasive deep brain stimulation (DBS) is effective in chronic cluster headache (CCH), it should be reserved for extremely difficult-to-treat patients. Percutaneous occipital nerve stimulation has shown similar efficacy to DBS and is less risky in both CCH and chronic migraine (CM). Non-invasive transcutaneous vagus nerve stimulation is a promising add-on treatment for CCH but not for CM. Transcutaneous external trigeminal nerve stimulation may be effective in treating CM; however, it has not yet been tested for cluster headache. Transcranial magnetic and electric stimulations have promising preventive effects against CM and CCH.

Summary

Although the precise mode of action of non-invasive neuromodulation techniques remains largely unknown and there is a paucity of controlled trials, they should be preferred to more invasive techniques for treating CDH.

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.

Current Perspectives on the Impact of Chronic Migraine on Sleep Quality: A Literature Review

OBJECTIVE

Recent studies have shown that sleep problems occur in migraineurs and poor sleep causes chronification, but the mechanisms by which chronic migraine affects sleep quality are still unknown. This review aims to analyze commonly reported sleep disturbances in chronic migraine (CM) and determine the effect of CM on sleep quality.

MATERIALS AND METHODS

We conducted a comprehensive review of all published articles on CM and sleep quality from inception to March 2022 in the literature. Clinical trials, observational studies, and case series (≥20 cases) were included. Two reviewers and a supervisor reviewed the titles and abstracts of all search results with predefined inclusion and exclusion criteria. PubMed search for randomized controlled trials and open studies on CM and sleep quality reported in English between 1983 and 2022 was conducted using the keywords including chronic migraine, sleep, insomnia, sleep quality, polysomnography, and Pittsburgh Sleep Quality Index.

RESULTS

A total of 535 potentially relevant articles were found. A total of 455 articles and reviews, meta-analyses published in any language other than English, with other exclusion criteria, were excluded from the review. In the remaining articles, 36 clinical studies, reviewing sleep quality and its association with migraine, were identified and reviewed. Evidence from this review shows that poor sleep and migraine chronicity are intertwined with other accompanying comorbidities and dysregulation of circadian rhythm that innovative treatments promise to bring relief to both poor sleep as well as migraine.

CONCLUSION

Sleep disorders are common in CM and the association between migraine chronification and sleep quality is bidirectional. Comorbid conditions with accompanying frequent attacks in migraine may impair sleep quality. While the maladaptive pain process worsens sleep, poor sleep quality also negatively affects migraine pain. Sleep disturbance, which is affected by worsening migraine attacks, causes deterioration in the quality of life, loss of workforce, and economic burden.

Vagus nerve afferent stimulation: Projection into the brain, reflexive physiological, perceptual, and behavioral responses, and clinical relevance

The afferent vagus nerves project to diverse neural networks within the brainstem and forebrain, based on neuroanatomical, neurophysiological, and functional (fMRI) brain imaging evidence. In response to afferent vagal stimulation, multiple homeostatic visceral reflexes are elicited. Physiological stimuli and both invasive and non-invasive electrical stimulation that activate the afferent vagus elicit perceptual and behavioral responses that are of physiological and clinical significance. In the present review, we address these multiple roles of the afferent vagus under normal and pathological conditions, based on both animal and human evidence.

Neurosensory Prosthetics: An Integral Neuromodulation Part of Bioelectronic Device

Bioelectronic medicines (BEMs) constitute a branch of bioelectronic devices (BEDs), which are a class of therapeutics that combine neuroscience with molecular biology, immunology, and engineering technologies. Thus, BEMs are the culmination of thought processes of scientists of varied fields and herald a new era in the treatment of chronic diseases. BEMs work on the principle of neuromodulation of nerve stimulation. Examples of BEMs based on neuromodulation are those that modify neural circuits through deep brain stimulation, vagal nerve stimulation, spinal nerve stimulation, and retinal and auditory implants. BEDs may also serve as diagnostic tools by mimicking human sensory systems. Two examples of in vitro BEDs used as diagnostic agents in biomedical applications based on in vivo neurosensory circuits are the bioelectronic nose and bioelectronic tongue. The review discusses the ever-growing application of BEDs to a wide variety of health conditions and practices to improve the quality of life.

Peripheral Nerve Stimulation for Treatment of Headaches: An Evidence-Based Review

Headaches are one of the most common medical complaints worldwide, and treatment is often made difficult because of misclassification. Peripheral nerve stimulation has emerged as a novel treatment for the treatment of intractable headaches in recent years. While high-quality evidence does exist regarding its use, efficacy is generally limited to specific nerves and headache types. While much research remains to bring this technology to the mainstream, clinicians are increasingly able to provide safe yet efficacious pain control.

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.

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.

Vagus nerve stimulation in brain diseases: Therapeutic applications and biological mechanisms

Brain diseases, including neurodegenerative, cerebrovascular and neuropsychiatric diseases, have posed a deleterious threat to human health and brought a great burden to society and the healthcare system. With the development of medical technology, vagus nerve stimulation (VNS) has been approved by the Food and Drug Administration (FDA) as an alternative treatment for refractory epilepsy, refractory depression, cluster headaches, and migraines. Furthermore, current evidence showed promising results towards the treatment of more brain diseases, such as Parkinson's disease (PD), autistic spectrum disorder (ASD), traumatic brain injury (TBI), and stroke. Nonetheless, the biological mechanisms underlying the beneficial effects of VNS in brain diseases remain only partially elucidated. This review aims to delve into the relevant preclinical and clinical studies and update the progress of VNS applications and its potential mechanisms underlying the biological effects in brain diseases.

Behavioral and neurophysiological signatures of interoceptive enhancements following vagus nerve stimulation

An accruing body of research has shown that interoception (the sensing of signals from the body's internal milieu) relies on both a direct route (afforded by the vagus nerve) and a secondary route (supported by somatosensory mechanisms). However, no study has causally tested the differential role of these pathways, let alone via direct stimulation. To bridge this gap, we tested whether multidimensional signatures of interoception are modulated by noninvasive vagus nerve stimulation (nVNS). Sixty-three participants were divided into an nVNS and a sham-stimulation group. Before and after stimulation, both groups performed a validated heartbeat detection (HBD) task including a genuinely interoceptive condition (monitoring one's own heartbeat) and a control exteroceptive condition (tracking an aurally presented heartbeat). Electroencephalographic signals were obtained during both conditions to examine modulations of the heartbeat-evoked potential (HEP). Moreover, before and after stimulation, participants were asked to complete a somatosensory heartbeat localization task. Results from the interoceptive condition revealed that, after treatment, only the nVNS group exhibited improved performance and greater HEP modulations. No behavioral differences were found for the exteroceptive control condition, which was nonetheless associated with significant HEP modulations. Finally, no between-group differences were observed regarding the localization of the heartbeat sensations or relevant cardiodynamic variables (heart rate and or heart rate variability). Taken together, these results constitute unprecedented evidence that the vagus nerve plays a direct role in neurovisceral integration during interoception. This finding can constrain mechanistic models of the domain while informing a promising transdiagnostic agenda for interoceptive impairments across neuropsychiatric conditions.

Study protocol for a multicentre, randomised, parallel group, sham-controlled clinical trial investigating the effect of transcutaneous vagal nerve stimulation on gastrointestinal symptoms in people with diabetes complicated with diabetic autonomic neuropathy: the DAN-VNS Study

INTRODUCTION

A high proportion of people with diabetes experience gastrointestinal (GI) symptoms, which may be manifestations of diabetic autonomic neuropathy (DAN). The current treatment regime is ineffective and associated with major side effects. Transcutaneous vagal nerve stimulation (tVNS) is a new therapeutic option, which has been shown to increase GI motility and reduce inflammatory responses. As vagus is the main neuronal pathway for extrinsic coordination of GI secretion and motility, we hypothesise that tVNS will improve DAN-induced GI symptoms in subjects with diabetes.

METHODS AND ANALYSIS

The DAN-VNS study is a randomised multicentre clinical trial investigating the effect of short-term, high intensity as well as long-term, medium-intensity tVNS on GI symptom alleviation in 120 subjects with diabetes. The primary outcome consists of changes from baseline in subjective ratings of symptom severity. Secondary outcomes include changes in gastric motility and GI transit time measured by MRI and wireless motility capsule. Moreover, cardiovascular and sudomotor function, glycaemic control, brain sensory processing and presence of low-grade inflammation will be investigated as secondary outcome measures. Lastly, 15 responders of tVNS treatment will be included in an explorative, randomised, cross-over study, in which the acute endocrine and metabolic response to short-term tVNS will be investigated.

ETHICS AND DISSEMINATION

The study has been approved by the North Denmark Region Committee on Health Research Ethics (N-20190020). Results will be published in relevant international peer-reviewed journals.

TRIAL REGISTRATION NUMBER

NCT04143269.

Mapping Assessments Instruments for Headache Disorders against the ICF Biopsychosocial Model of Health and Disability

Headache disorders have a strong impact on sufferers’ lives. However, the “content” of assessment instruments addressing concepts, such as disability and quality of life (QoL), has not comprehensively been addressed. We searched SCOPUS for research papers in which outcome measures were used in adult populations of patients with migraine, tension-type headache (TTH), and cluster headache (CH). The content of single instruments was then mapped against the International Classification of Functioning, Disability, and Health. A total of 150 papers and 26 instruments were included: 15 addressed disability or impact, two addressed work-related difficulties, and nine addressed QoL. Few instruments were commonly used across the conditions and covered domains of functioning were impact on daily life activities, homework, school, and work-related tasks, leisure time, informal and family relations, pain, emotional difficulties, energy level, and impulse control. Most of the research is based on instruments that were developed for migraine, which is critical for CH, and the impact of headache disorders on work-related activities is poorly acknowledged. Further research is needed to expand the scope of headaches impact on daily life activities, and on environmental factors relevant to headache disorders to raise knowledge on the less represented areas, e.g., TTH impact.

Noninvasive vagus nerve stimulation and morphine transiently inhibit trigeminal pain signaling in a chronic headache model

Noninvasive vagus nerve stimulation suppressed persistent trigeminal nociception in a chronic headache model similarly to morphine and may provide a safe, nonaddictive abortive therapy for chronic headache.

Introduction:

Chronic headache conditions are characterized by persistent sensitization of the trigeminal system, which involves dysfunction of descending pain modulation. We previously reported that noninvasive vagus nerve stimulation (nVNS) inhibits trigeminal nociception in models of episodic migraine through a mechanism involving enhanced serotonergic and GABAergic descending pain signaling.

Objectives:

The analgesic effectiveness of nVNS and morphine were investigated in an animal model of chronic headache mediated by the combination of the 3 migraine risk factors of neck muscle tension, paradoxical sleep deprivation, and pungent odors.

Methods:

Sprague–Dawley rats were injected with complete Freund's adjuvant in the trapezius and sleep deprived for 1 night to promote trigeminal sensitization. After 7 days, animals were exposed to a pungent odor, and mechanical nocifensive head withdrawal responses were determined using von Frey filaments. Beginning on day 3 after odor exposure, animals were treated daily with either nVNS or morphine for 7 days.

Results:

Exposure of animals sensitized by neck inflammation and sleep deprivation to a pungent odor resulted in a prolonged state of trigeminal nociception. Daily administration of nVNS or morphine significantly repressed the nocifensive response; however, cessation resulted in a return to heightened pretreatment nocifensive levels.

Conclusions:

The combination of reported migraine risk factors promotes a state of sustained trigeminal hypersensitivity characteristic of chronic headache. Daily nVNS was similarly effective as morphine in inhibiting nociception and may represent a safer, opioid-sparing therapeutic option for other chronic pain disorders involving sensitization of the trigeminal system by promoting descending pain modulation.

Noninvasive Neuromodulation in Migraine

PURPOSE OF REVIEW

The past two decades has seen an influx of noninvasive neuromodulation devices aimed at treatment of various primary headache disorders, including cluster headache and migraine. This narrative review is to summarize the current options in noninvasive neuromodulation in migraine.

RECENT FINDINGS

A variety of noninvasive neuromodulation devices have been FDA cleared and marketed for use in migraine, including single-pulse transcranial magnetic stimulation (sTMS), noninvasive vagal nerve stimulators (nVNS), and external trigeminal nerve stimulators (eTNS). Newer devices include peripheral electrical stimulation devices (PES), caloric stimulation, and others. Each has varying levels of evidence supporting its use in migraine, tolerability profiles, and access issues. Noninvasive neuromodulation devices can be beneficial when used in patients with migraine, with minimal side effects. As more devices are developed, approved, and marketed in the future, rigorous research on efficacy and safety remain a top priority.

The Instant Effects of Continuous Transcutaneous Auricular Vagus Nerve Stimulation at Acupoints on the Functional Connectivity of Amygdala in Migraine without Aura: A Preliminary Study

Background

A growing body of evidence suggests that both auricular acupuncture and transcutaneous auricular vagus nerve stimulation (taVNS) can induce antinociception and relieve symptoms of migraine. However, their instant effects and central treatment mechanism remain unclear. Many studies proved that the amygdalae play a vital role not only in emotion modulation but also in pain processing. In this study, we investigated the modulation effects of continuous taVNS at acupoints on the FC of the bilateral amygdalae in MwoA.

Methods

Thirty episodic migraineurs were recruited for the single-blind, crossover functional magnetic resonance imaging (fMRI) study. Each participant attended two kinds of eight-minute stimulations, taVNS and sham-taVNS (staVNS), separated by seven days in random order. Finally, 27 of them were included in the analysis of seed-to-voxel FC with the left/right amygdala as seeds.

Results

Compared with staVNS, the FC decreased during taVNS between the left amygdala and left middle frontal gyrus (MFG), left dorsolateral superior frontal gyrus, right supplementary motor area (SMA), bilateral paracentral lobules, bilateral postcingulum gyrus, and right frontal superior medial gyrus, so did the FC of the right amygdala and left MFG. A significant positive correlation was observed between the FC of the left amygdala and right SMA and the frequency/total time of migraine attacks during the preceding four weeks.

Conclusion

Continuous taVNS at acupoints can modulate the FC between the bilateral amygdalae and pain-related brain regions in MwoA, involving the limbic system, default mode network, and pain matrix, with obvious differences between the left amygdala and the right amygdala. The taVNS may produce treatment effects by modulating the abnormal FC of the amygdala and pain networks, possibly having the same central mechanism as auricular acupuncture.

Feasibility of Non-Invasive Vagus Nerve Stimulation (gammaCore VET™) for the Treatment of Refractory Seizure Activity in Dogs

Idiopathic epilepsy is the most common chronic neurologic condition in dogs. Approximately 20–30% of those dogs are refractory to standard medical therapy and commonly experience side effects from antiepileptic drugs. Non-invasive vagus nerve stimulation (nVNS) has been frequently used in human medicine as an adjunct seizure therapy with low incidence of adverse events. Canine studies are limited to invasive surgical implants with no non-invasive evaluations currently published. We investigated the feasibility and efficacy of nVNS (gammaCore VET) as an adjunct treatment for refractory epilepsy in dogs. In total, 14 client-owned dogs completed the trial of either 8- or 16-week treatment periods during which they received 90–120 s stimulation three times per day in the region of the left cervical vagus nerve. Owners recorded seizure type (focal or generalized) and frequency as well as any adverse effects. Out of 14 dogs, nine achieved a reduction in seizure frequency and four were considered responders with a 50% or greater reduction in seizures from baseline to the final treatment period. However, there was no statistically significant difference in overall seizure frequency (p = 0.53) or percent change in seizure frequency between groups (p = 0.75). Adverse effects occurred in 25% of dogs originally enrolled, with reports of a hoarse bark and limb trembling, lethargy, behavioral changes, and an increase in seizure frequency. Non-invasive VNS was found to be safe and easy to administer with mild adverse events. It is considered a feasible treatment option as an adjunct therapy in refractory seizures and should be further investigated.

Update on noninvasive neuromodulation for migraine treatment-Vagus nerve stimulation

Noninvasive neurostimulation methods are particularly suited for migraine treatment thanks to their most favorable adverse event profile. Among them, noninvasive vagus nerve stimulation (nVNS) has raised great hope because of the role the vagus nerve is known to play in pain modulation, inflammation and brain excitability. We will critically review the clinical studies performed for migraine attack treatment and migraine prevention with the GammaCore® device, which allows cervical vagus nerve stimulation. nVNS is effective for the abortive treatment of migraine attacks, although the effect size is modest and numbers-to-treat appear not superior to those of other noninvasive neurostimulation methods, and inferior to those of oral triptans. The effect of nVNS with the GammaCore® in migraine prevention is not superior to sham stimulation, except possibly in patients with high adherence to the treatment. Both in acute and preventive trials, nVNS was characterized by an outstanding tolerance and safety profile, like the other noninvasive neurostimulation techniques. In physiological animal and human studies, cervical nVNS was shown to generate somatosensory evoked responses, to modulate pain perception and several areas of the cerebral pain network, and to inhibit experimental cortical spreading depression, which are relevant effects for migraine therapy.

Therapeutic implications of cortical spreading depression models in migraine

Migraine is among the most common and disabling neurological diseases in the world. Cortical spreading depression (CSD) is a wave of near-complete depolarization of neurons and glial cells that slowly propagates along the cortex creating the perception of aura. Evidence suggests that CSD can trigger migraine headache. Experimental models of CSD have been considered highly translational as they recapitulate migraine-related phenomena and have been validated for screening migraine therapeutics. Here we outline the essential components of validated experimental models of CSD and provide a comprehensive review of potential modulators and targets against CSD. We further focus on novel interventions that have been recently shown to suppress CSD susceptibility that may lead to therapeutic targets in migraine.

Electrical stimulation of cranial nerves in cognition and disease

The cranial nerves are the pathways through which environmental information (sensation) is directly communicated to the brain, leading to perception, and giving rise to higher cognition. Because cranial nerves determine and modulate brain function, invasive and non-invasive cranial nerve electrical stimulation methods have applications in the clinical, behavioral, and cognitive domains. Among other neuromodulation approaches such as peripheral, transcranial and deep brain stimulation, cranial nerve stimulation is unique in allowing axon pathway-specific engagement of brain circuits, including thalamo-cortical networks. In this review we amalgamate relevant knowledge of 1) cranial nerve anatomy and biophysics; 2) evidence of the modulatory effects of cranial nerves on cognition; 3) clinical and behavioral outcomes of cranial nerve stimulation; and 4) biomarkers of nerve target engagement including physiology, electroencephalography, neuroimaging, and behavioral metrics. Existing non-invasive stimulation methods cannot feasibly activate the axons of only individual cranial nerves. Even with invasive stimulation methods, selective targeting of one nerve fiber type requires nuance since each nerve is composed of functionally distinct axon-types that differentially branch and can anastomose onto other nerves. None-the-less, precisely controlling stimulation parameters can aid in affecting distinct sets of axons, thus supporting specific actions on cognition and behavior. To this end, a rubric for reproducible dose-response stimulation parameters is defined here. Given that afferent cranial nerve axons project directly to the brain, targeting structures (e.g. thalamus, cortex) that are critical nodes in higher order brain networks, potent effects on cognition are plausible. We propose an intervention design framework based on driving cranial nerve pathways in targeted brain circuits, which are in turn linked to specific higher cognitive processes. State-of-the-art current flow models that are used to explain and design cranial-nerve-activating stimulation technology require multi-scale detail that includes: gross anatomy; skull foramina and superficial tissue layers; and precise nerve morphology. Detailed simulations also predict that some non-invasive electrical or magnetic stimulation approaches that do not intend to modulate cranial nerves per se, such as transcranial direct current stimulation (tDCS) and transcranial magnetic stimulation (TMS), may also modulate activity of specific cranial nerves. Much prior cranial nerve stimulation work was conceptually limited to the production of sensory perception, with individual titration of intensity based on the level of perception and tolerability. However, disregarding sensory emulation allows consideration of temporal stimulation patterns (axon recruitment) that modulate the tone of cortical networks independent of sensory cortices, without necessarily titrating perception. For example, leveraging the role of the thalamus as a gatekeeper for information to the cerebral cortex, preventing or enhancing the passage of specific information depending on the behavioral state. We show that properly parameterized computational models at multiple scales are needed to rationally optimize neuromodulation that target sets of cranial nerves, determining which and how specific brain circuitries are modulated, which can in turn influence cognition in a designed manner.

Critical Review of Transcutaneous Vagus Nerve Stimulation: Challenges for Translation to Clinical Practice

Several studies have illustrated that transcutaneous vagus nerve stimulation (tVNS) can elicit therapeutic effects that are similar to those produced by its invasive counterpart, vagus nerve stimulation (VNS). VNS is an FDA-approved therapy for the treatment of both depression and epilepsy, but it is limited to the management of more severe, intervention-resistant cases as a second or third-line treatment option due to perioperative risks involved with device implantation. In contrast, tVNS is a non-invasive technique that involves the application of electrical currents through surface electrodes at select locations, most commonly targeting the auricular branch of the vagus nerve (ABVN) and the cervical branch of the vagus nerve in the neck. Although it has been shown that tVNS elicits hypo- and hyperactivation in various regions of the brain associated with anxiety and mood regulation, the mechanism of action and influence of stimulation parameters on clinical outcomes remains predominantly hypothetical. Suppositions are largely based on correlations between the neurobiology of the vagus nerve and its effects on neural activity. However, tVNS has also been investigated for several other disorders, including tinnitus, migraine and pain, by targeting the vagus nerve at sites in both the ear and the neck. As most of the described methods differ in the parameters and protocols applied, there is currently no firm evidence on the optimal location for tVNS or the stimulation parameters that provide the greatest therapeutic effects for a specific condition. This review presents the current status of tVNS with a focus on stimulation parameters, stimulation sites, and available devices. For tVNS to reach its full potential as a non-invasive and clinically relevant therapy, it is imperative that systematic studies be undertaken to reveal the mechanism of action and optimal stimulation modalities.

Noninvasive vagus nerve stimulation and the trigeminal autonomic reflex

Objective

The trigeminal autonomic reflex is a physiologic reflex that plays a crucial role in primary headache and particularly in trigeminal autonomic cephalalgias, such as cluster headache. Previous studies have shown that this reflex can be modulated by the vagus nerve, leading to an inhibition of the parasympathetic output of the reflex in healthy participants. The aim of the present study was to characterize neural correlates of the modulatory effect of noninvasive vagus nerve stimulation (nVNS) on the trigeminal autonomic reflex.

Methods

Twenty-one healthy participants were included in a 2-day, randomized, single-blind, within-subject design. The reflex was activated inside the MRI scanner using kinetic oscillation stimulation placed in the left nostril, resulting in an increase in lacrimation. After the first fMRI session, the participants received either sham vagus nerve stimulation or nVNS outside the scanner and underwent a subsequent fMRI session.

Results

nVNS prompted an increase in activation of the left pontine nucleus and a decreased activation of the right parahippocampal gyrus. Psychophysiologic interaction analyses revealed an increased functional connectivity between the left pontine nucleus and the right hypothalamus and a decreased functional connectivity between the right parahippocampal gyrus and the bilateral spinal trigeminal nuclei (sTN).

Conclusions

These findings indicate a complex network involved in the modulatory effect of nVNS including the hypothalamus, the sTN, the pontine nucleus, and the parahippocampal gyrus.

[Peripheral neurostimulation in headache treatment]

According to rough estimates, at least one third of the population in developed countries suffers, to varying degrees, from certain forms of primary headache, the modern pharmacotherapy of which is not always effective and has a number of limitations. The non-pharmacological treatment of headache can be an alternative to the prescription of pharmacological agents and the only possible assistance option for patients developing drug-resistant cephalalgias. This review describes various methods of electrical neuromodulation that are used for the management of primary headaches. The authors provide information on current stages in implementation of implantable and non-invasive equipment into clinical practice, which makes possible electrical stimulations of peripheral nerves and of the sphenopalatine ganglion, as well as allows transcranial magnetic stimulation. Also the appearance and usage of portable electrical devices available on the world market are described, and mechanisms that can underlie anticephalgic action of neuromodulation therapy are discussed. Special attention is paid to the methods that are applied for electrostimulation of the vagus nerve and occipital nerves.

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

INTRODUCTION

Non-invasive vagus nerve stimulation (nVNS; gammaCore®) has the potential to prevent migraine days in patients with migraine on the basis of mechanistic rationale and pilot clinical data.

METHODS

This multicentre study included a 4-week run-in period, a 12-week double-blind period of randomised treatment with nVNS or sham, and a 24-week open-label period of nVNS. Patients were to administer two 120-second stimulations bilaterally to the neck three times daily (6-8 hours apart).

RESULTS

Of 477 enrolled patients, 332 comprised the intent-to-treat (ITT) population. Mean reductions in migraine days per month (primary outcome) were 2.26 for nVNS (n = 165; baseline, 7.9 days) and 1.80 for sham (n = 167; baseline, 8.1 days) (p = 0.15). Results were similar across other outcomes. Upon observation of suboptimal adherence rates, post hoc analysis of patients with ≥ 67% adherence per month demonstrated significant differences between nVNS (n = 138) and sham (n = 140) for outcomes including reduction in migraine days (2.27 vs. 1.53; p = 0.043); therapeutic gains were greater in patients with aura than in those without aura. Most nVNS device-related adverse events were mild and transient, with application site discomfort being the most common.

CONCLUSIONS

Preventive nVNS treatment in episodic migraine was not superior to sham stimulation in the ITT population. The "sham" device inadvertently provided a level of active vagus nerve stimulation. Post hoc analysis showed significant effects of nVNS in treatment-adherent patients. Study identification and registration: PREMIUM; NCT02378844; https://clinicaltrials.gov/ct2/show/NCT02378844.

Acute vestibular migraine treatment with noninvasive vagus nerve stimulation

Objective

To report on the benefits of noninvasive vagus nerve stimulation (nVNS) on acute vestibular migraine (VM) treatment.

Methods

This was a retrospective chart review of patients with VM treated with nVNS in a single tertiary referral center between November 2017 and January 2019. Eighteen patients (16 women) were identified (mean age 45.7 [±14.8] years); 14 were treated for a VM attack and 4 for bothersome interictal dizziness consistent with persistent perceptual postural dizziness (PPPD). Patients graded the severity of vestibular symptoms and headache using an 11-point visual analog scale (VAS; 0 = no symptoms, 10 = worst ever symptoms) before and 15 minutes after nVNS.

Results

In those with acute VM, vertigo improved in 13/14 (complete resolution in 2, at least 50% improvement in 5). The mean vertigo intensity before nVNS was 5.2 (±1.6; median 6), and 3.1 (±2.2; median 3) following stimulation; mean reduction in vertigo intensity was 46.9% (±31.5; median 45%). Five experienced headache with the VM attack; all reported improvement following nVNS. Mean headache severity was 6 (±1.4; median 6) prior to treatment and 2.4 (±1.5; median 3) following nVNS; mean reduction in headache intensity was 63.3% (±21.7; median 50). All 4 treated with nVNS for interictal PPPD reported no benefit.

Conclusion

Our study provides preliminary evidence that nVNS may provide rapid relief of vertigo and headache in acute VM, and supports further randomized, sham-controlled studies into nVNS in VM.

Classification of evidence

This study provides Class IV evidence that for patients with acute VM, nVNS rapidly relieves vertigo and headache.

Current and emerging evidence-based treatment options in chronic migraine: a narrative review

Background

Chronic migraine is a disabling condition that is currently underdiagnosed and undertreated. In this narrative review, we discuss the future of chronic migraine management in relation to recent progress in evidence-based pharmacological treatment.

Findings

Patients with chronic migraine require prophylactic therapy to reduce the frequency of migraine attacks, but the only currently available evidence-based prophylactic treatment options for chronic migraine are topiramate and onabotulinumtoxinA. Improved prophylactic therapy is needed to reduce the high burden of chronic migraine in Italy. Monoclonal antibodies that target the calcitonin gene-related peptide (CGRP) pathway of migraine pathogenesis have been specifically developed for the prophylactic treatment of chronic migraine. These anti-CGRP/R monoclonal antibodies have demonstrated good efficacy and excellent tolerability in phase II and III clinical trials, and offer new hope to patients who are currently not taking any prophylactic therapy or not benefitting from their current treatment.

Conclusions

Treatment of chronic migraine is a dynamic and rapidly advancing area of research. New developments in this field have the potential to improve the diagnosis and provide more individualised treatments for this condition. Establishing a culture of prevention is essential for reducing the personal, social and economic burden of chronic migraine.

Vagus nerve stimulation for primary headache disorders: An anatomical review to explain a clinical phenomenon

BACKGROUND

Non-invasive stimulation of the vagus nerve has been proposed as a new neuromodulation therapy to treat primary headache disorders, as the vagus nerve is hypothesized to modulate the headache pain pathways in the brain. Vagus nerve stimulation can be performed by placing an electrode on the ear to stimulate the tragus nerve, which contains about 1% of the vagus fibers. Non-invasive vagus nerve stimulation (nVNS) conventionally refers to stimulation of the cervical branch of the vagus nerve, which is made up entirely of vagal nerve fibers. While used interchangeably, most of the research to date has been performed with nVNS or an implanted vagus nerve stimulation device. However, the exact mechanism of action of nVNS remains hypothetical and no clear overview of the effectiveness of nVNS in primary headache disorders is available.

METHODS

In the present study, the clinical trials that investigated the effectiveness, tolerability and safety of nVNS in primary headache disorders were systematically reviewed. The second part of this study reviewed the central connections of the vagus nerve. Papers on the clinical use of nVNS and the anatomical investigations were included based on predefined criteria, evaluated, and results were reported in a narrative way.

RESULTS

The first part of this review shows that nVNS in primary headache disorders is moderately effective, safe and well-tolerated. Regarding the anatomical review, it was reported that fibers from the vagus nerve intertwine with fibers from the trigeminal, facial, glossopharyngeal and hypoglossal nerves, mostly in the trigeminal spinal tract. Second, the four nuclei of the vagus nerve (nuclei of the solitary tract, nucleus ambiguus, spinal nucleus of the trigeminal nerve and dorsal motor nucleus (DMX)) show extensive interconnections. Third, the efferents from the vagal nuclei that receive sensory and visceral input (i.e. nuclei of the solitary tract and spinal nucleus of the trigeminal nerve) mainly course towards the main parts of the neural pain matrix directly or indirectly via other vagal nuclei.

CONCLUSION

The moderate effectiveness of nVNS in treating primary headache disorders can possibly be linked to the connections between the trigeminal and vagal systems as described in animals.

Acute Treatment of Migraine

PURPOSE OF REVIEW

This article provides a framework to help providers formulate a plan for the acute treatment of migraine. Topics covered include the cost-effective patient-centered approach known as stratified care and a summary of evidence-based treatment options that are currently available. Strategies for improving treatment response, troubleshooting suboptimal results, and addressing the needs of special populations are also reviewed.

RECENT FINDINGS

Both the American Headache Society and the Canadian Headache Society have released evidence-based assessments and reviews of acute treatments for migraine that can be used to help guide treatment decisions. Although several older medications have been re-released with new formulations or new delivery systems, several new medications have also become available or are in the final phases of study, further increasing the number of options available for patients.

SUMMARY

The acute management of migraine should incorporate a stratified care model in concert with evidence-based treatment options. The response to treatment should be monitored regularly, and measures should be taken to identify suboptimal tolerability or efficacy.

Saliva molecular inflammatory profiling in female migraine patients responsive to adjunctive cervical non-invasive vagus nerve stimulation: the MOXY Study

Background

Rising evidence indicate that oxytocin and IL-1β impact trigemino-nociceptive signaling. Current perspectives on migraine physiopathology emphasize a cytokine bias towards a pro-inflammatory status. The anti-nociceptive impact of oxytocin has been reported in preclinical and human trials. Cervical non-invasive vagus nerve stimulation (nVNS) emerges as an add-on treatment for the preventive and abortive use in migraine. Less is known about its potential to modulate saliva inflammatory signaling in migraine patients. The rationale was to perform inter-ictal saliva measures of oxytocin and IL-1ß along with headache assessment in migraine patients with 10 weeks adjunctive nVNS compared to healthy controls.

Methods

12 migraineurs and 12 suitably matched healthy control were studied with inter-ictal saliva assay of pro- and anti-neuroinflammatory cytokines using enzyme-linked immuno assay techniques along with assessment of headache severity/frequency and associated functional capacity at baseline and after 10 weeks adjunctive cervical nVNS.

Results

nVNS significantly reduced headache severity (VAS), frequency (headache days and total number of attacks) and significantly improved sleep quality compared to baseline (p < 0.01). Inter-ictal saliva oxytocin and IL-1β were significantly elevated pre- as well as post-nVNS compared to healthy controls (p < 0.01) and similarly showed changes that may reflect the observed clinical effects.

Conclusions

Our results add to accumulating evidence for a therapeutic efficacy of adjunct cervical non-invasive vagus nerve stimulation in migraine patients. This study failed to provide an evidence-derived conclusion addressed to the predictive value and usefulness of saliva assays due to its uncontrolled study design. However, saliva screening of mediators associated with trigemino-nociceptive traffic represents a novel approach, thus deserve future targeted headache research.

Trial registration This study was indexed at the German Register for Clinical Trials (DRKS No. 00011089) registered on 21.09.2016

Modern approaches to diagnostics and treatment of migraine in children

This article reviews modern approaches to diagnostics and treatment of a very common and simultaneously underestimated and often maltreated disorder in children. It is fallacious management of migraine masked behind the diagnoses such as autonomic vessel dysfunction and vascular headache here in Ukraine. This is a tremendous problem and it should be solved with appropriate information spread across the medical community. Up-to-date classification according to the International Headache Society, diagnostic criteria, differential diagnosis, investigation and treatment strategies are presented in the article. All supported data are com-pliant with guidelines of developed countries with evidence-based medicine (US, Canada, Great Britain, Japan, Australia, New Zealand) enhanced with new trials and approved methods. Migraine management is a rapidly evolving concept, where major changes were done during recent years (transcranial Deep Brain Stimulation, vagus stimulation, CGRP-receptor mono-clonal antibodies). Considering disorder incidence and its impact on life quality and the existence of options for alleviating symptoms, this information is important for physicians who work with children, especially for general practitioners, pediatrics, pediatric and adult neurologists.

Neurostimulation for the treatment of chronic migraine and cluster headache

Small subsets of patients who fail to respond to pharmacological treatment may benefit from alternative treatment methods. In the last decade, neurostimulation is being explored as a potential treatment option for the patients with chronic, severely disabling refractory primary headaches. To alleviate pain, specific nerves and brain areas have been stimulated, and various methods have been explored: deep brain stimulation, occipital nerve stimulation, and sphenopalatine ganglion stimulation are among the more invasive ones, whereas transcranial magnetic stimulation and supraorbital nerve stimulation are noninvasive. Vagal nerve stimulation can be invasive or noninvasive, though this review included only data for noninvasive VNS. Most of these methods have been tested in small open-label patient series; recently, more data from randomized, controlled, and blinded studies are available. Although neurostimulation treatments have demonstrated good efficacy in many studies, it still has not been established as a standard treatment in refractory patients. This review analyzes the available evidence regarding efficacy and safety of different neurostimulation modalities for the treatment of chronic migraine and cluster headache.

Vagus nerve stimulation modulates the cranial trigeminal autonomic reflex

OBJECTIVE

The trigeminal autonomic reflex plays an important role in primary headache syndromes. Noninvasive vagal nerve stimulation (nVNS) may be an effective modulator of this reflex.

METHODS

Twenty-two healthy volunteers underwent kinetic oscillation stimulation (KOS) of the left nostril as a reliable trigger of the trigeminal autonomic reflex. Previous to KOS, left cervical nVNS, sham simulation, or no stimulation was applied. Lacrimation was quantified using the standardized Schirmer ll test.

RESULTS

Treatment with cervical nVNS significantly reduced lacrimation between no stimulation and nVNS on the ipsilateral side (minute 5: p = 0.026, ηp² = 0.85, 95% confidence interval [CI] = 1.39-18.04; no stimulation: minute 5, 14.4 ± 9.3 mm; nVNS: minute 5, 4.7 ± 8.6 mm, mean ± standard deviation) as well as between sham stimulation and nVNS (minute 5: p = 0.030, ηp² = 0.85, 95% CI = 1.04-17.24; sham: minute 5, 13.9 ± 6.4 mm). On the contralateral side, no significant increase between baseline and KOS was observed for nVNS (minute 5: p = 0.614, d = 0.12, 95% CI = -7.09 to 4.31; minute 5, 1.4 ± 11.5 mm) compared to both sham stimulation (minute 5: p = 0.023, d = 0.57, 95% CI = -11.46 to -0.96; minute 5, 6.2 ± 10.9 mm) and no stimulation (minute 5: p < 0.030, d = 0.62, 95% CI = -13.45 to -0.81; minute 5, 7.1 ± 11.4 mm).

INTERPRETATION

Cervical nVNS resulted in a robust bilateral reduction of provoked lacrimation. This effect could be mediated either by direct bilateral activation of structures such as the nucleus of the solitary tract or by a top-down modulation via the hypothalamus. Ann Neurol 2018;84:886-892.

Consistent effects of non-invasive vagus nerve stimulation (nVNS) for the acute treatment of migraine: additional findings from the randomized, sham-controlled, double-blind PRESTO trial

BACKGROUND

Non-invasive vagus nerve stimulation (nVNS) has been shown to be practical, safe, and well tolerated for treating primary headache disorders. The recent multicenter, randomized, double-blind, sham-controlled PRESTO trial provided Class I evidence that for patients with episodic migraine, nVNS significantly increases the probability of having mild pain or being pain-free 2 h post stimulation. We report additional pre-defined secondary and other end points from PRESTO that demonstrate the consistency and durability of nVNS efficacy across a broad range of outcomes.

METHODS

After a 4-week observation period, 248 patients with episodic migraine with/without aura were randomly assigned to acute treatment of migraine attacks with nVNS (n = 122) or a sham device (n = 126) during a double-blind period lasting 4 weeks (or until the patient had treated 5 attacks). All patients received nVNS therapy during the subsequent 4-week/5-attack open-label period.

RESULTS

The intent-to-treat population consisted of 243 patients. The nVNS group (n = 120) had a significantly greater percentage of attacks treated during the double-blind period that were pain-free at 60 (P = 0.005) and 120 min (P = 0.026) than the sham group (n = 123) did. Similar results were seen for attacks with pain relief at 60 (P = 0.025) and 120 min (P = 0.018). For the first attack and all attacks, the nVNS group had significantly greater decreases (vs sham) in pain score from baseline to 60 min (P = 0.029); the decrease was also significantly greater for nVNS at 120 min for the first attack (P = 0.011). Results during the open-label period were consistent with those of the nVNS group during the double-blind period. The incidence of adverse events (AEs) and adverse device effects was low across all study periods, and no serious AEs occurred.

CONCLUSIONS

These results further demonstrate that nVNS is an effective and reliable acute treatment for multiple migraine attacks, which can be used safely while preserving the patient's option to use traditional acute medications as rescue therapy, possibly decreasing the risk of medication overuse. Together with its practicality and optimal tolerability profile, these findings suggest nVNS has value as a front-line option for acute treatment of migraine.

TRIAL REGISTRATION

ClinicalTrials.gov identifier: NCT02686034 .

Practical and clinical utility of non-invasive vagus nerve stimulation (nVNS) for the acute treatment of migraine: a post hoc analysis of the randomized, sham-controlled, double-blind PRESTO trial

BACKGROUND

The PRESTO study of non-invasive vagus nerve stimulation (nVNS; gammaCore®) featured key primary and secondary end points recommended by the International Headache Society to provide Class I evidence that for patients with an episodic migraine, nVNS significantly increases the probability of having mild pain or being pain-free 2 h post stimulation. Here, we examined additional data from PRESTO to provide further insights into the practical utility of nVNS by evaluating its ability to consistently deliver clinically meaningful improvements in pain intensity while reducing the need for rescue medication.

METHODS

Patients recorded pain intensity for treated migraine attacks on a 4-point scale. Data were examined to compare nVNS and sham with regard to the percentage of patients who benefited by at least 1 point in pain intensity. We also assessed the percentage of attacks that required rescue medication and pain-free rates stratified by pain intensity at treatment initiation.

RESULTS

A significantly higher percentage of patients who used acute nVNS treatment (n = 120) vs sham (n = 123) reported a ≥ 1-point decrease in pain intensity at 30 min (nVNS, 32.2%; sham, 18.5%; P = 0.020), 60 min (nVNS, 38.8%; sham, 24.0%; P = 0.017), and 120 min (nVNS, 46.8%; sham, 26.2%; P = 0.002) after the first attack. Similar significant results were seen when assessing the benefit in all attacks. The proportion of patients who did not require rescue medication was significantly higher with nVNS than with sham for the first attack (nVNS, 59.3%; sham, 41.9%; P = 0.013) and all attacks (nVNS, 52.3%; sham, 37.3%; P = 0.008). When initial pain intensity was mild, the percentage of patients with no pain after treatment was significantly higher with nVNS than with sham at 60 min (all attacks: nVNS, 37.0%; sham, 21.2%; P = 0.025) and 120 min (first attack: nVNS, 50.0%; sham, 25.0%; P = 0.018; all attacks: nVNS, 46.7%; sham, 30.1%; P = 0.037).

CONCLUSIONS

This post hoc analysis demonstrated that acute nVNS treatment quickly and consistently reduced pain intensity while decreasing rescue medication use. These clinical benefits provide guidance in the optimal use of nVNS in everyday practice, which can potentially reduce use of acute pharmacologic medications and their associated adverse events.

TRIAL REGISTRATION

ClinicalTrials.gov identifier: NCT02686034 .