Non-invasive Vagus Nerve Stimulation Research Articles

Non-invasive Vagus Nerve Stimulation for COVID-19: Results From a Randomized Controlled Trial (SAVIOR I).

BackgroundSevere coronavirus disease 2019 (COVID-19) is characterized, in part, by an excessive inflammatory response. Evidence from animal and human studies suggests that vagus nerve stimulation can lead to reduced levels of various biomarkers of inflammation. We conducted a prospective randomized controlled study (SAVIOR-I) to assess the feasibility, efficacy, and safety of non-invasive vagus nerve stimulation (nVNS) for the treatment of respiratory symptoms and inflammatory markers among patients who were hospitalized for COVID-19 (ClinicalTrials.gov identifier: NCT04368156).MethodsParticipants were randomly assigned in a 1:1 allocation to receive either the standard of care (SoC) alone or nVNS therapy plus the SoC. The nVNS group received 2 consecutive 2-min doses of nVNS 3 times daily as prophylaxis. Efficacy and safety were evaluated via the incidence of specific clinical events, inflammatory biomarker levels, and the occurrence of adverse events.ResultsOf the 110 participants who were enrolled and randomly assigned, 97 (nVNS, n = 47; SoC, n = 50) had sufficient available data and comprised the evaluable population. C-reactive protein (CRP) levels decreased from baseline to a significantly greater degree in the nVNS group than in the SoC group at day 5 and overall (i.e., all postbaseline data points collected through day 5, combined). Procalcitonin level also showed significantly greater decreases from baseline to day 5 in the nVNS group than in the SoC group. D-dimer levels were decreased from baseline for the nVNS group and increased from baseline for the SoC group at day 5 and overall, although the difference between the treatment groups did not reach statistical significance. No significant treatment differences were seen for clinical respiratory outcomes or any of the other biochemical markers evaluated. No serious nVNS-related adverse events occurred during the study.ConclusionsnVNS therapy led to significant reductions in levels of inflammatory markers, specifically CRP and procalcitonin. Because nVNS has multiple mechanisms of action that may be relevant to COVID-19, additional research into its potential use earlier in the course of COVID-19 and its potential to mitigate some of the symptoms associated with post-acute sequelae of COVID-19 is warranted.

Effects of Noninvasive Cervical Vagal Nerve Stimulation on Cognitive Performance But Not Brain Activation in Healthy Adults

ObjectivesWhile preliminary evidence suggests that noninvasive vagal nerve stimulation (nVNS) may enhance cognition, to our knowledge, no study has directly assessed the effects of nVNS on brain function and cognitive performance in healthy individuals. The aim of this study was therefore to assess whether nVNS enhances complex visuospatial problem solving in a normative sample. Functional magnetic resonance imaging (fMRI) was used to examine underlying neural substrates. Material and MethodsParticipants received transcutaneous cervical nVNS (N = 15) or sham (N = 15) stimulation during a 3 T fMRI scan. Stimulation lasted for 2 min at 24 V for nVNS and at 4.5 V for sham. Subjects completed a matrix reasoning (MR) task in the scanner and a forced-choice recognition task outside the scanner. An analysis of variance (ANOVA) was used to assess group differences in cognitive performance. And linear mixed effects (LMEs) regression analysis was used to assess main and interaction effects of experimental groups, level of MR task difficulty, and recall accuracy on changes in blood oxygen level-dependent (BOLD) signal. ResultsSubjects who received nVNS showed higher accuracy for both easy (p = 0.017) and hard (p = 0.013) items of the MR task, slower reaction times for hard items (p = 0.014), and fewer false negative errors during the forced-choice recognition task (p = 0.047). MR task difficulty related to increased activation in frontoparietal regions (p < 0.001). No difference between nVNS and sham stimulation was found on BOLD response during performance of the MR task. ConclusionsWe hypothesize that nVNS increased attention compared to sham, and that this effect led to enhanced executive functions, and consequently to better performance on visuospatial reasoning and recognition tasks. Results provide initial support that nVNS may be a low-risk, low-cost treatment for cognitive disorders.

439 The effect of non-invasive transcutaneous auricular vagus nerve stimulation (taVNS) on hypoxic-ischemic injury in newborn rats

OBJECTIVES/GOALS: Neonatal hypoxic-ischemic encephalopathy (HIE) is an acute neurologic syndrome where decreased blood flow and oxygen to the brain causes acute and chronic brain dysfunction. The only proven neuroprotective intervention for HIE is hypothermia treatment started within 6 hours of birth and 50% of survivors have long-term deficits. METHODS/STUDY POPULATION: Pre-clinical adult stroke studies demonstrated that vagus nerve stimulation (VNS) has anti-inflammatory effects and attenuates brain damage. Transcutaneous auricular VNS (taVNS) is safe and feasible in infants and may improve the motor skill of bottle feeding. We hypothesize that a combined hypothermia-taVNS treatment shortly after HIE birth will have neuroprotective effects, improve motor function, attenuate infarct volume inflammation compared to hypothermia alone. The HIE model includes ligation of the right common carotid artery in postnatal day 7 (P7) rats followed by 90min hypoxia (8% oxygen) and 2hr hypothermia. taVNS or sham taVNS was administered using a bipolar electrode placed on the auricular concha region for 30min, [30sec trains, 0.5msec duration, 20Hz frequency, followed by 4.5min breaks] RESULTS/ANTICIPATED RESULTS: Experimental groups include +HIE/+taVNS, +HIE/-taVNS, and -HIE/-taVNS. To assess motor function, grasping reflex and forelimb grip strength tasks were assessed prior to surgery through P10. Infarct volume was assessed at 72h after injury by staining coronal sections with cresyl-violet. Thirty-four rat pups underwent surgery with an 8.82% mortality rate. taVNS was well tolerated by the P7 rats when delivered below perceptual threshold (0.4-1.1mA). There was no difference in elementary motor function or infarct volume between any group. DISCUSSION/SIGNIFICANCE: Future studies will include 2.5hr hypoxia for a more severe brain injury and a -HIE/+taVNS control group. These initial pre-clinical studies in neonates are important in determining whether taVNS may translate as a treatment to improve outcomes after neonatal HIE.

Network meta-analysis of therapies for cluster headache: Effects of acute therapies for episodic and chronic cluster.

We used network meta-analysis (NMA) to characterize the relative effectiveness and harms of acute treatment options for cluster headache. There are few evidence-based acute treatments available for cluster headache. As most treatments were compared only against placebos in clinical trials, few head-to-head comparisons of treatments are available. An a priori registered scoping review was performed to identify randomized controlled trials evaluating treatments in adult patients (>18years old) with cluster headache per accepted diagnostic criteria. Bayesian NMAs were performed to compare treatments in terms of headache relief at 15 or 30min, and also the occurrence of adverse events. We report odds ratios (ORs) of relative treatment effects along with corresponding 95% credible intervals (CrIs), as well as measures of treatment ranking. A total of 13 randomized controlled trials informed NMAs. We found high flow oxygen to be the most effective therapy for headache response at 15 and 30min (OR 9.0, 95% CrI 5.3 to 15.9 vs. placebo), with injectable sumatriptan demonstrating the next highest effect (OR 6.4, 95% CrI 3.75 to 11.1 vs. placebo). High flow oxygen was also more effective than low flow oxygen (OR 2.55, 95% CrI 1.13 to 5.8), nasal spray zolmitriptan (OR 3.75, 95% CrI 1.72 to 8.4), octreotide (OR 4.5, 95% CrI 1.64 to 12.5), and non-invasive vagal nerve stimulation (nVNS; OR 5.2, 95% CrI 2.29 to 11.9). Sumatriptan injectable was also effective for headache relief and was found to be better than nasal spray zolmitriptan (OR 2.67, 95% CrI 1.21 to 5.9), octreotide (OR 3.20, 95% CrI 1.17 to 8.8), and nVNS (OR 3.69, 95% CrI 1.63 to 8.4). Octreotide (OR 4.1, 95% CrI 1.71 to 10.5) and sumatriptan (OR 2.40, 95% CrI 1.39 to 4.2) were associated with greater risk of adverse events compared to placebo, while other treatments did not demonstrate increased risk. When focusing on patients with episodic cluster headache, nVNS was significantly better than placebo (OR 4.9, 95% CrI 1.89 to 14.1). Our findings suggest that high flow oxygen is more efficacious when compared to low flow oxygen for headache relief. When low flow oxygen fails in patients who can tolerate oxygen, increased flow rates should be tried. Additionally, high flow oxygen is likely more effective than zolmitriptan nasal spray, nVNS, and octreotide. Sumatriptan injectable is more likely to be effective when compared to zolmitriptan nasal spray, octreotide, and nVNS.

Effects of acute and preventive therapies for episodic and chronic cluster headache: A scoping review of the literature.

Cluster headache is the most common primary headache disorder of the trigeminal autonomic cephalalgias, and it is highly disabling. We undertake a scoping review to characterize therapies to prevent and acutely treat cluster headache, characterize trial methodology utilized in studies, and recommend future trial "good practices." We also assess homogeneity of studies and feasibility for future network meta-analyses (NMAs) to compare acute and preventive treatments for cluster headache. A priori protocol for this scoping review was registered and available on Open Science Forum. We sought studies that enrolled adult patients with cluster headache as identified by accepted diagnostic criteria. Both randomized controlled trials (RCTs) and observational studies (with a control group) were included. The interventions of interest were medications, procedures, devices, surgeries, and behavioral/psychological interventions, whereas comparators of interest were placebo, sham, or other active treatments. Outcomes were predefined; however, we did not exclude studies lacking these outcomes. A systemic search was conducted in Ovid Medline, Embase, and Cochrane. We performed a targeted search for conference abstracts from journals prominent in the field. We identified 56 studies: 45 RCTs, four studies only available in clinical trial registries, and seven observational studies. Of the 45 RCTs, 20 focused on acute therapies and 25 on preventive therapies. Overall, we determined that it is feasible to pursue a NMA for acute therapy focusing on 15 or 30-min headache reduction for acute trials, as we identified 11 trials in the combined population of patients with either episodic or chronic cluster headache (2 trials in populations with chronic cluster headache were also found). For preventive therapy of cluster headache, we identified trials with common outcomes that may be considered for NMA, however, as these trials had differences in treatment effect modifiers that could not be corrected, NMAs appear infeasible for this indication. We identified new studies looking at noninvasive vagal nerve stimulation, sphenopalatine ganglion stimulation, prednisone, and oxygen published since the most recent systematic review in the field, although these acute treatments were previously identified as effective. However, for calcitonin gene-related peptide (CGRP) monoclonal antibodies, galcanezumab demonstrated effectiveness in episodic cluster headache, but a lack of effectiveness in chronic cluster headache, and fremanezumab was not effective for episodic nor chronic cluster headache. This finding highlights that CGRP monoclonal antibodies may not show a class effect in cluster headache prevention and need to be considered individually. We describe the treatment landscape of cluster headache for both acute and preventive treatments. Last, we present the NMAs we will undertake in acute therapies of cluster headache.

Non-invasive Vagus Nerve Stimulation in Cerebral Stroke: Current Status and Future Perspectives.

Stroke poses a serious threat to human health and burdens both society and the healthcare system. Standard rehabilitative therapies may not be effective in improving functions after stroke, so alternative strategies are needed. The FDA has approved vagus nerve stimulation (VNS) for the treatment of epilepsy, migraines, and depression. Recent studies have demonstrated that VNS can facilitate the benefits of rehabilitation interventions. VNS coupled with upper limb rehabilitation enhances the recovery of upper limb function in patients with chronic stroke. However, its invasive nature limits its clinical application. Researchers have developed a non-invasive method to stimulate the vagus nerve (non-invasive vagus nerve stimulation, nVNS). It has been suggested that nVNS coupled with rehabilitation could be a promising alternative for improving muscle function in chronic stroke patients. In this article, we review the current researches in preclinical and clinical studies as well as the potential applications of nVNS in stroke. We summarize the parameters, advantages, potential mechanisms, and adverse effects of current nVNS applications, as well as the future challenges and directions for nVNS in cerebral stroke treatment. These studies indicate that nVNS has promising efficacy in reducing stroke volume and attenuating neurological deficits in ischemic stroke models. While more basic and clinical research is required to fully understand its mechanisms of efficacy, especially Phase III trials with a large number of patients, these data suggest that nVNS can be applied easily not only as a possible secondary prophylactic treatment in chronic cerebral stroke, but also as a promising adjunctive treatment in acute cerebral stroke in the near future.

Validation of a new impedance cardiography analysis algorithm for clinical classification of stress states.

Pre-ejection period (PEP) is an index of sympathetic nervous system activity that can be computed from electrocardiogram (ECG) and impedance cardiogram (ICG) signals, but sensitive to speech/motion artifact. We sought to validate an ICG noise removal method, three-stage ensemble-average algorithm (TEA), in data acquired from a clinical trial comparing active versus sham non-invasive vagal nerve stimulation (tcVNS) after standardized speech stress. We first compared TEA's performance versus the standard conventional ensemble-average algorithm (CEA) approach to classify noisy ICG segments. We then analyzed ECG and ICG data to measure PEP and compared group-level differences in stress states with each approach. We evaluated 45 individuals, of whom 23 had post-traumatic stress disorder (PTSD). We found that the TEA approach identified artifact-corrupted beats with intraclass correlation coefficient>0.99 compared to expert adjudication. TEA also resulted in higher group-level differences in PEP between stress states than CEA. PEP values were lower in the speech stress (vs. baseline rest) group using both techniques, but the differences were greater using TEA (12.1ms) than CEA (8.0ms). PEP differences in groups divided by PTSD status and tcVNS (active vs. sham) were also greater when using the TEA versus CEA method, although the magnitude of the differences was lower. In conclusion, TEA helps to accurately identify noisy ICG beats during speaking stress, and this increased accuracy improves sensitivity to group-level differences in stress states compared to CEA, suggesting greater clinical utility.

The potential of invasive and non-invasive vagus nerve stimulation to improve verbal memory performance in epilepsy patients

It has been demonstrated that acute vagus nerve stimulation (VNS) improves word recognition memory in epilepsy patients. Transcutaneous auricular vagus nerve stimulation (taVNS) has gained interest as a non-invasive alternative to improve cognition. In this prospective randomized cross-over study, we investigated the effect of both invasive VNS and taVNS on verbal memory performance in 15 patients with drug-resistant epilepsy. All patients conducted a word recognition memory paradigm in 3 conditions: VNS ON, VNS OFF and taVNS (3-period 3-treatment cross-over study design). For each condition, patients memorized 21 highlighted words from text paragraphs. Afterwards, the intervention was delivered for 30 s. Immediate recall and delayed recognition scores were obtained for each condition. This memory paradigm was repeated after 6 weeks of VNS therapy in 2 conditions: VNS ON and VNS OFF (2-period 2-treatment cross-over study design). Acute VNS and taVNS did not improve verbal memory performance. Immediate recall and delayed recognition scores were significantly improved after 6 weeks of VNS treatment irrespective of the acute intervention. We can conclude that the previously described positive effects of invasive VNS on verbal memory performance could not be replicated with invasive VNS and taVNS. An improved verbal memory performance was seen after 6 weeks of VNS treatment, suggesting that longer and more repetitive stimulation of the vagal pathway is required to modulate verbal memory performance.Clinical trial registration number: NCT05031208.

Abstract WP141: Effect Of Non-invasive Vagus Nerve Stimulation In Hemorrhagic Brain Injury And Permanent Ischemic Stroke In Rats

Introduction: Non-invasive vagus nerve stimulation (nVNS) reduces infarct volume after transient ischemia in rats. Here, we tested the effect of nVNS in intracerebral hemorrhage (ICH) and permanent ischemic brain injury models. Methods: ICH was induced by whole blood (n=24) or collagenase (n=24) injection into the striatum of adult male and female Wistar rats. 1-hour sham stimulation (n=16) or nVNS (n=32) was initiated 30 minutes after injection. Spontaneous circling, hindlimb retraction, and grasp ability were tested at 24 hours to measure functional deficit. Rats were euthanized 24 hours or one week after injury, and brain tissue was processed for water content analysis (n=24) and histology (n=24), respectively. Permanent ischemia was induced by filament occlusion of the right middle cerebral artery in adult male Wistar rats (n=18). Sham stimulation and nVNS initiated 30 minutes after the induction of ischemia were applied for 1 hour and 3 hours (n=6 per group). Rats were euthanized 24 hours later to measure infarct volume. Results: 1-hour nVNS was associated with a non-significant reduction in hematoma volume in both models of ICH (Fig). Animals treated with nVNS demonstrated better functional outcome at 24 hours after ICH ( p =0.042). There was no difference in brain edema between control and active treatment arms in both models of ICH. 3-hour nVNS reduced infarct volume by 21% in permanent ischemia ( p =0.047, Fig). Conclusion: The results of this study support prior evidence that nVNS may have a therapeutic potential in ischemic stroke. nVNS is currently being evaluated in two clinical studies (NCT03733431 and NCT04050501) for the treatment of acute ischemic stroke. The lack of adverse events in two different models of ICH in this study suggests that nVNS could be safely administered as early as an ambulatory setting before the stroke etiology (ischemic vs. hemorrhagic) has been determined.

Abstract WMP5: Non-invasive Vagus Nerve Stimulation For The Acute Treatment Of Ischemic Or Hemorrhagic Stroke

Background: This first-in-human randomized, blinded, sham-controlled, multicenter study assessed the safety and feasibility of non-invasive vagus nerve stimulation (nVNS) for the acute treatment of ischemic and hemorrhagic stroke. Potential efficacy was also assessed. Methods: Eligible participants admitted to nine clinical sites received standard care for acute stroke and were randomly assigned to low-dose nVNS, sham (2-minute stimulation applied to the skin overlying the vagus nerve every 10 minutes for an hour; 7 stimulations) or high-dose nVNS (2-minute stimulation every 10 minutes during hour 1 and hour 5; 14 stimulations) within 6 hours of stroke onset. Safety endpoints included severe bradycardia (≤50 beats/min) or significant hypotension (≥20-mm Hg reduction in arterial blood pressure) evaluated at 2 and 5 minutes after each stimulation and 30 minutes after the final stimulation. Feasibility was measured as the proportion of eligible patients in whom nVNS could be initiated within 6 hours of stroke onset and the ability to deliver scheduled stimulations per protocol. Efficacy measurements included absolute and relative infarct growth 24 hours poststroke compared to baseline and the proportion of patients with an NIH Stroke Scale (NIHSS) score of ≤4 or a ≥8-point improvement at 24 hours. Results: Sixty-eight patients with ischemic (n=60) or hemorrhagic (n=8) stroke completed the study. Baseline characteristics did not differ between sham (n=24) and nVNS (n=44). No significant bradycardia (2.9% of sham vs 3.1% of nVNS; p =0.965) or hypotension (1.1% of sham vs 2.5% of nVNS; p =0.145) occurred with nVNS. No deaths, acute coronary syndrome, symptomatic intracerebral hemorrhage, or stimulation site reactions were noted. All patients received 100% of intended stimulations per protocol. Clinical efficacy measures were similar between sham and total nVNS. Relative infarct growth, measured by diffusion weighted imaging, in the high dose nVNS group (63.3%) was lower than in the sham group (185.8%; p =0.05). Conclusions: This study suggests that nVNS is safe and feasible for the acute treatment for ischemic and hemorrhagic stroke. Possible efficacy is suggested by a decrease in relative infarct growth.

Noninvasive vagus nerve stimulation modulates trigeminal but not extracephalic somatosensory perception: functional evidence for a trigemino-vagal system in humans.

Noninvasive vagus nerve stimulation (nVNS) is effective in several types of headache disorders. We sought to unravel the mechanism of how nVNS exhibits this efficacy. This study used a randomized, single-blind, sham-controlled, crossover design and comprised 3 projects with 3 independent cohorts of healthy participants. Project I (n = 15) was explorative. Six quantitative sensory test parameters, including mechanical pain threshold (MPT), were measured over the left V1 dermatome and forearm and compared before and after unilateral nVNS. Projects II (n = 20) and III (n = 21) were preregistered online ( https://osf.io/r4jb9 ). Quantitative sensory test parameters were compared over the left (Project II) or bilateral V1 and V3 dermatomes (Project III), respectively, in addition to the left forearm as a control. A secondary analysis of heart rate variability (HRV) using a historical control group was used to control for systemic effects of nVNS. Verum-nVNS induced trigeminal-specific modulation of pain threshold (ie, MPT) over the left V1 in Project I, left V1 and V3 in Project II, and bilateral V1 and V3 in Project III. Data pooled from Projects II and III demonstrated a greater increase in MPT in the V1 vs V3 dermatome. There were no differences associated with sham-nVNS in any projects. Heart rate variability parameters did not change after nVNS. Our results provide functional evidence of a long hypothesized functional trigemino-vagal system in humans and may explain why nVNS is effective in some headache disorders but not in somatic pain disorders. Because unilateral nVNS modulated the trigeminal thresholds bilaterally, this effect is probably indirect through a central top-down mechanism.

Different Transcutaneous Auricular Vagus Nerve Stimulation Parameters Modulate the Anti-Inflammatory Effects on Lipopolysaccharide-Induced Acute Inflammation in Mice.

Vagus nerve stimulation (VNS) is considered a potential method for anti-inflammation due to the involvement of the VN in the cholinergic anti-inflammatory pathway (CAP) formation of a connection between the central nervous system and peripheral immune cells that help relieve inflammation. However, whether a non-invasive transcutaneous auricular VNS (taVNS) modulates the inflammation levels via altering the parameter of taVNS is poorly understood. This study aimed to determine the differential inhibitory effects of taVNS on lipopolysaccharide (LPS)-induced systemic inflammation using electrical stimulation parameters such as pulse frequency and time. The taVNS-promoted CAP activity significantly recovered LPS-induced tissue injuries (lung, spleen, and intestine) and decreased inflammatory cytokine levels and tissue-infiltrated immune cells. Interestingly, the anti-inflammatory capacity of taVNS with 15 Hz was much higher than that of taVNS with 25 Hz. When a cytokine array was used to investigate the changes of inflammation and immune response-related cytokines/chemokines expression in taVNS with 15 Hz or 25 Hz treatment in LPS-induced endotoxemia in mice, most of the expression of cytokines/chemokines associated with pro-inflammation was severely decreased in taVNS with 15 Hz compared to 25 Hz. This study demonstrated that the taVNS parameter could differentially modulate the inflammation levels of animals, suggesting the importance of taVNS parameter selection for use in feasible interventions for acute inflammation treatment.

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

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

Non-Invasive Transcutaneous Vagus Nerve Stimulation for the Treatment of Fibromyalgia Symptoms: A Study Protocol.

Stimulation of the vagus nerve, a parasympathetic nerve that controls the neuro-digestive, vascular, and immune systems, induces pain relief, particularly in clinical conditions such as headache and rheumatoid arthritis. Transmission through vagal afferents towards the nucleus of the solitary tract (NST), the central relay nucleus of the vagus nerve, has been proposed as the main physiological mechanism that reduces pain intensity after vagal stimulation. Chronic pain symptoms of fibromyalgia patients might benefit from stimulation of the vagus nerve via normalization of altered autonomic and immune systems causing their respective symptoms. However, multi-session non-invasive vagal stimulation effects on fibromyalgia have not been evaluated in randomized clinical trials. We propose a parallel group, sham-controlled, randomized study to modulate the sympathetic–vagal balance and pain intensity in fibromyalgia patients by application of non-invasive transcutaneous vagus nerve stimulation (tVNS) over the vagal auricular and cervical branches. We will recruit 136 fibromyalgia patients with chronic moderate to high pain intensity. The primary outcome measure will be pain intensity, and secondary measures will be fatigue, health-related quality of life, sleep disorders, and depression. Heart rate variability and pro-inflammatory cytokine levels will be obtained as secondary physiological measures. We hypothesize that multiple tVNS sessions (five per week, for 4 weeks) will reduce pain intensity and improve quality of life as a result of normalization of the vagal control of nociception and immune–autonomic functions. Since both vagal branches project to the NST, we do not predict significantly different results between the two stimulation protocols.

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

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

The second brain in Parkinson's disease: fact or fantasy?

The second brain in Parkinson's disease: fact or fantasy?

The Future Is Noninvasive: A Brief Review of the Evolution and Clinical Utility of Vagus Nerve Stimulation.

Vagus nerve stimulation (VNS) is a form of neuromodulation that stimulates the vagus nerve. VNS had been suggested as an intervention in the late 1800s and was rediscovered in the late 1980s as a promising treatment for refractory epilepsy. Since then, VNS has been approved by the U.S. Food and Drug Administration (FDA) for treatment of epilepsy, morbid obesity, and treatment-resistant depression. Unfortunately, VNS is underutilized, as it is costly to implant and often only suggested when all other treatment options have been exhausted. Discovery of a noninvasive method of VNS known as transcutaneous auricular VNS (taVNS), which activates the vagus through stimulation of the auricular branch of the vagus nerve, has reignited excitement around VNS. taVNS has immense potential as a safe, at-home, wearable treatment for various neuropsychiatric disorders. Major strides are being made in both invasive and noninvasive VNS that aim to make this technology more accessible to patients who would find benefit, including the ongoing RECOVER trial, a randomized controlled trial in up to 1,000 individuals to further evaluate the efficacy of VNS for treatment-resistant depression. In this brief review, we first discuss the early history of VNS; then its clinical utility in FDA-approved indications; and, finally, noninvasive VNS.

Cluster Headache: Epidemiology, Pathophysiology, Clinical Features, and Diagnosis

Cluster headache is a primary headache disorder and is the most prevalent of the trigeminal autonomic cephalalgias. Cluster headache significantly impacts those affected, necessitating early diagnosis and management. Despite unique clinical features, such as patients experiencing attacks in a circannual pattern and often with a circadian rhythm within bouts, cluster headache patients often are misdiagnosed, mismanaged and have a delay in diagnosis. Preclinical, neuroimaging and clinical studies have advanced our understanding of cluster headache pathophysiology. The trigeminovascular system, the trigeminal autonomic reflex, and the hypothalamus are all involved in the pathophysiology of cluster headache. As our understanding of the pathophysiology of cluster headaches has evolved, new therapeutic options, such as calcitonin gene-related peptide monoclonal antibodies, non-invasive vagal nerve stimulation and sphenopalatine ganglion stimulation, have proved to have efficacy in the treatment of cluster headache. Herein, we aim to review developments to aid readers in their understanding of this debilitating disorder.

Sleep disturbance management in patients with trigeminal autonomic cephalalgias

Trigeminal autonomic cephalalgias (TACs) are rare but are the most intense primary headaches that severely limit patients’ ability to work and be socially active. This article reviews the modern classification of TACs, based on the International Classification of Headache Disorders-3, and the key differences between TAC types, as well as the pathophysiological mechanisms – the role of the trigeminovascular system, autonomic nervous system, hypothalamus and vagus nerve – and their relation to circadian rhythms. The sleep disturbances that can occur in patients with TACs, exacerbating the course of the disease, and the role of melatonin, hypothalamus and suprachiasmatic nucleus in these conditions are also discussed. In addition, current therapies for cluster headache are described, which include acute therapy and prophylactic therapy, with recommendations regarding the timing of prophylactic therapy discontinuation. The review also includes the available data on melatonin as well as new therapies such as CGRP monoclonal antibodies and neuromodulation, which includes the two most promising techniques: non-invasive vagus nerve stimulation and sphenopalatine ganglion microstimulation. Furthermore, the authors present the clinical case of a patient with chronic cluster headache, which was significantly reduced in frequency and intensity when melatonin was added to the therapy.

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.