Acute vestibular migraine treatment with noninvasive vagus nerve stimulation

Transcutaneous Auricular Vagus Nerve Stimulation for Visually Induced Motion Sickness: An eLORETA Study

Transcutaneous auricular vagus nerve stimulation (taVNS), a non-invasive form of electrical brain stimulation, has shown potent therapeutic potential for a wide spectrum of conditions. How taVNS influences the characterization of motion sickness - a long mysterious syndrome with a polysymptomatic onset - remains unclear. Here, to examine taVNS-induced effects on brain function in response to motion-induced nausea, 64-channel electroencephalography (EEG) recordings from 42 healthy participants were analyzed; collected during nauseogenic visual stimulation concurrent with taVNS administration, in a crossover randomized sham-controlled study. Cortical neuronal generators were estimated from the obtained EEG using exact low-resolution brain electromagnetic tomography (eLORETA). While both sham and taVNS increased insula activation during electrical stimulation, compared to baseline, taVNS additionally augmented middle frontal gyrus neuronal activity. Following taVNS, brain regions including the supramarginal, parahippocampal, and precentral gyri were activated. Contrasting sham, taVNS markedly increased activity in the middle occipital gyrus during stimulation. A repeated-measures ANOVA showed that taVNS reduced motion sickness symptoms. This reduction in symptoms correlated with taVNS-induced neural activation. Our findings provide new insights into taVNS-induced brain changes, during and after nauseogenic stimuli exposure, including accompanying behavioral response. Together, these findings suggest that taVNS has promise as an effective neurostimulation tool for motion sickness management.

An overview of the current and emerging treatment options for vestibular migraine

INTRODUCTION

Vestibular migraine is a relatively common syndrome characterized by the occurrence of vertigo and other vestibular symptoms, frequently -but not always- accompanied by migraine symptoms, such as headache, photophobia, and phonophobia.

AREAS COVERED

The authors review the acute or abortive treatment during an attack and prophylactic treatment of vestibular migraines, including pharmacological and non-pharmacological options.

EXPERT OPINION

Since its recognition as an independent clinical entity is recent, studies concerning its different treatment alternatives are still scarce, and the level of evidence of published studies is generally low. For acute treatment, although available data are conflicting, triptans are usually tried first. Neurostimulating devices can also be considered for acute treatment of vestibular migraine. Regarding the preventive treatment of vestibular migraine, based on the results of two randomized clinical trials and its pharmacological properties, flunarizine should be considered as the first treatment option. Second-line preventive treatments encompass propranolol, topiramate, venlafaxine, and valproic acid. Among non-pharmacological options, vestibular rehabilitation seems to be a sound prophylactic treatment option.

Effectiveness of Anti-Calcitonin Gene-Related Peptide Medication in Vestibular Migraine: A Retrospective Cohort Study in an Asian Population

BACKGROUND

Migraine and dizziness often coexist, with vestibular migraine (VM) presenting with vestibular symptoms and headaches. Calcitonin gene-related peptide (CGRP) may be involved in motion-induced symptoms; however, studies on the use of anti-CGRP monoclonal antibodies (mAbs) for the treatment of VM have yielded conflicting results. This study aimed to clarify the effectiveness of anti-CGRP mAbs in VM treatment.

METHODS

This retrospective observational cohort study, conducted between 1 January 2021 and 31 March 2023, assessed 12 Japanese patients with VM who were treated with anti-CGRP mAbs (CGRP group) for 6 months and 11 Japanese patients who received standard of care for VM and served as controls. Clinical questionnaires and equilibrium tests were administered, with primary outcomes including changes in Dizziness Handicap Inventory (DHI) scores compared with baseline values. Objective variables included the DHI score and explanatory variables included demographic data, balance test results, head-up tilt (HUT) test results, vestibular test results and questionnaire survey results. Analysis of variance was used to assess the treatment effects of anti-CGRP mAbs, and multivariate regression analysis was performed to identify mAb responders.

RESULTS

After 6 months, the CGRP group showed significant improvements in DHI scores [0 versus 6 months, odds ratio (95% confidence interval): 22.01 (0.13-43.88)] and number of vertigo/dizziness attacks per month [0 versus 6 months: 10.28 (2.80-17.76)]. No significant difference was observed in the control group [DHI scores, 0 versus 6 months: 0.65 (-26.84 to 28.14); number of vertigo/dizziness attacks per month, 0 versus 6 months: - 8.07 (- 23.77 to 7.62)]. Multivariate regression analysis showed that autonomic function at baseline was associated with mAb response in patients [β estimates (95% confidence interval): 3.63 (0.21-7.06)].

CONCLUSIONS

Treatment with anti-CGRP mAbs was more effective than conventional treatment in preventing migraine in patients with VM. While the identified factors associated with treatment responsiveness offer valuable insights into personalised treatment approaches, further prospective studies are warranted to validate the findings due to our study's retrospective design and limited sample size.

Integrative effects of transcutaneous auricular vagus nerve stimulation on esophageal motility and pharyngeal symptoms via vagal mechanisms in patients with laryngopharyngeal reflux disease

Background and aim

Laryngopharyngeal reflux disease (LPRD) is primarily characterized by discomfort in the pharynx and has limited treatment options. This research aimed to assess the efficacy of transcutaneous auricular vagus nerve stimulation (tVNS) in patients with LPRD and delve into the potential underlying mechanisms.

Methods

A total of 44 participants, diagnosed with LPRD were divided into two groups randomly. Twice-daily stimulation was delivered for 2 weeks for patients in experimental group, with stimulation ranging from 1.0 mA to 1.5 mA (n = 22), while the control group underwent sham tVNS (n = 22) with the same stimulation parameters and different anatomical location. The severity of symptoms and levels of anxiety and depression were monitored using questionnaires. High-resolution esophageal manometry data were collected, and the patients' autonomic function was assessed through heart rate variability analysis.

Results

There was a positive correlation between reflux symptom index (RSI) scores and low frequency/high frequency (LF/HF) ratio (r = 0.619; p < 0.001), Hamilton anxiety scale (HAMA) scores (r = 0.623; p < 0.001), and Hamilton depression scale (HAMD) scores (r = 0.593; p < 0.001). Compared to the pre-tVNS phase, RSI (p < 0.001), HAMA (p < 0.001), and HAMD (p < 0.001) scores were significantly reduced after 2 weeks of treatment. Additionally, the resting pressure of the upper esophageal sphincter (UESP; p < 0.05) and lower esophageal sphincter (LESP; p < 0.05) showed significant enhancement. Notably, tVNS led to an increase in root mean square of successive differences (RMSSD; p < 0.05) and high frequency (HF; p < 0.05) within heart rate variability compared to the pre-treatment baseline. Compared to the control group, RSI (p < 0.001), HAMA (p < 0.001), and HAMD (p < 0.001) scores in tVNS group were significantly lower at the end of treatment. Similarly, the resting pressure of UESP (p < 0.05) and LESP (p < 0.05) in tVNS group were significantly higher than that of control group. Notably, RMSSD (p < 0.05) and HF (p < 0.05) in tVNS group were significantly higher than that of control group.

Conclusion

This study demonstrated that tVNS as a therapeutic approach is effective in alleviating LPRD symptoms. Furthermore, it suggests that improvements in esophageal motility could be associated with vagus nerve-dependent mechanisms.

Vestibular Migraine Pathophysiology and Treatment: a Narrative Review

PURPOSE OF REVIEW

To review the diagnosis of vestibular migraine (VM) and update the clinician on the most recent developments in our understanding of its pathophysiology and treatment.

RECENT FINDINGS

Functional imaging studies have identified multiple regions of the brain with abnormal activity and connectivity in VM. There is evidence of abnormal sensory processing and integration in VM patients. Calcitonin gene-related peptide (CGRP) has also been found to play a role in trigeminal and vestibular nucleus pathways. Research into treatment modalities has identified several neuromodulation devices that may be effective in VM. There are a growing number of evidence-based preventive options for VM, including medications that target CGRP. VM is best understood as a sensory processing disorder. CGRP appears to play a role, and further research is needed to fully understand its effects. Treatment options are expanding, but there is still a need for more randomly controlled trials in this area.

Recent Developments in Vestibular Migraine: A Narrative Review

PURPOSE

The aim of this study was to review current literature regarding the epidemiology of vestibular migraine (VM), patient presentation, pathogenesis, and treatment.

RECENT FINDINGS

VM is becoming an increasingly recognized condition in the United States, currently affecting 2.7% of people. Patients may experience vestibular symptoms, such as vertigo and imbalance, with or without other migrainous symptoms. Recent evidence has also shown that patients with VM are at higher risk for cochlear dysfunction, such as sudden deafness, sensorineural hearing loss, and tinnitus. The heritability and genetics are not well understood, and the pathogenesis may involve calcitonin gene-related peptide, which is also implicated in migraine headaches. A disease-specific patient reported outcome measure, the Vestibular Migraine Patient Assessment Tool and Handicap Inventory, was recently developed and validated. A limited number of controlled trials have assessed various therapies for VM, including triptans and beta-blockers. More data are needed to understand whether or not currently available migraine treatments are effective for VM.

SUMMARY

VM is a common etiology of vertigo and dizziness, presenting with a characteristic spectrum of symptoms. Early data suggest that migraine treatments may be helpful in some cases.

Novel ways to modulate the vestibular system: Magnetic vestibular stimulation, deep brain stimulation and transcranial magnetic stimulation / transcranial direct current stimulation

BACKGROUND

Advances in neurotechnologies are revolutionizing our understanding of complex neural circuits and enabling new treatments for disorders of the human brain. In the vestibular system, electromagnetic stimuli can now modulate vestibular reflexes and sensations of self-motion by artificially stimulating the labyrinth, cerebellum, cerebral cortex, and their connections.

OBJECTIVE

In this narrative review, we describe evolving neuromodulatory techniques including magnetic vestibular stimulation (MVS), deep brain stimulation (DBS), transcranial magnetic stimulation (TMS), and transcranial direct-current stimulation (tDCS) and discuss current and potential future application in the field of neuro-otology.

RESULTS

MVS triggers both vestibular nystagmic (persistent) and perceptual (lasting ∼1 min) responses that may serve as a model to study central adaptational mechanisms and pathomechanisms of hemispatial neglect. By systematically mapping DBS electrodes, targeted stimulation of central vestibular pathways allowed modulating eye movements, vestibular heading perception, spatial attention and graviception, resulting in reduced anti-saccade error rates and hypometria, improved heading discrimination, shifts in verticality perception and transiently decreased spatial attention. For TMS/tDCS treatment trials have demonstrated amelioration of vestibular symptoms in various neuro-otological conditions, including chronic vestibular insufficiency, Mal-de-Debarquement and cerebellar ataxia.

CONCLUSION

Neuromodulation has a bright future as a potential treatment of vestibular dysfunction. MVS, DBS and TMS may provide new and sophisticated, customizable, and specific treatment options of vestibular symptoms in humans. While promising treatment responses have been reported for TMS/tDCS, treatment trials for vestibular disorders using MVS or DBS have yet to be defined and performed.

Cyclic alternating pattern in non-rapid eye movement sleep in patients with vestibular migraine

OBJECTIVE

This study aimed to analyze the microstructural features of sleep in patients with vestibular migraine and migraine, and to hypothesize the pathophysiological mechanism between vestibular migraine and sleep disorders.

METHODS

From March 2021 to June 2022, 35 vestibular migraine patients, 35 migraine patients, and 30 controls were collected from the Vertigo Center & Sleep Center of the Second Affiliated Hospital of Zhengzhou University. The anxiety and depression status, sleep quality, and cyclic alternating pattern (CAP) of the three groups were analyzed and compared using the Pittsburgh Sleep Quality Index, Hamilton Anxiety and Depression Scale, and polysomnography (PSG).

RESULTS

The vestibular migraine group had a higher CAP time (mean 173.64 vs. 122.11, P < 0.001), CAP index (mean 54.25 vs. 37.50, P < 0.001), CAP rate (mean 48.41 vs. 32.31, P < 0.001), CAP sequences (mean 42.60 vs. 29.83, P < 0.001), A3% (mean 45.58 vs. 17.50, P < 0.001) and A2%+A3% (mean 68.87 vs. 38.83, P < 0.001) compared to the control group, with a lower A1 index (mean 16.68 vs. 23.87, P < 0.001) and A1% (mean 31.13% vs. 61.17, P < 0.001).

CONCLUSION

Patients with vestibular migraine have poor sleep quality, thalamic-cortical hyperfunction and active arousal system. In addition, high CAP rate and high A2 to A3 ratio make the sleep structure more fragmented.

Vestibular Migraine

PURPOSE OF REVIEW

To explore recent developments in vestibular migraine (VM).

RECENT FINDINGS

This review discusses the current diagnostic criteria for VM in the adult and pediatric populations, as proposed by the International Headache Society and Bárány Society. Recent VM studies confirm the prior findings and reveal new insights, including the wide range of vestibular symptoms, symptoms in the attack-free period, and triggers. Many patients experience persistent vestibular symptoms, even in the absence of acute attacks, which often significantly impact patients' quality of life. The syndrome of benign recurrent vertigo and its relationship to migraine, VM, and Meniere's disease is also discussed. There is a dearth of randomized controlled trials in VM treatment. Prospective and retrospective studies support the benefit of many migraine treatments are effective in VM, including neuromodulation, and calcitonin gene-related peptide monoclonal antibodies. VM affects almost 3% of the population, but remains under-diagnosed. Recent diagnostic criteria can help clinicians diagnose VM in adults and children.

Vestibular migraine treatment: a comprehensive practical review

Vestibular migraine is an underdiagnosed but increasingly recognised neurological condition that causes episodic vertigo associated with other features of migraine. It is now thought to be the most common cause of spontaneous (non-positional) episodic vertigo, affecting up to 1% of the population. A meta-analysis of preventative treatments for vestibular migraine was published in 2021 but the authors were unable to establish a preferred treatment strategy due to low quality of evidence and heterogeneity of study design and outcome reporting. There remains therefore a clinical need for pragmatic management guidelines specific to vestibular migraine using the available evidence. Here we provide a practical review utilising a systematic qualitative assessment of the evidence for abortive and preventative interventions in adults. The overall evidence base for vestibular migraine treatment is of low quality. Nevertheless, we provide practical treatment recommendations based on the available evidence and our experience to help guide clinicians treating patients with vestibular migraine. We also discuss how future clinical trials could be designed to improve the quality of evidence in this condition.

Vestibular Migraine: Clinical Aspects and Pathophysiology

VM is a common yet debilitating migraine variant that has taken many monikers in the past. As a relatively new diagnostic entity, public and provider awareness of this disorder can be improved. Symptoms include vertigo episodes in addition to photophobia, phonophobia, nausea, and headache. Diagnosis is primarily based on clinical history as pathognomonic signs via testing are not reliable. Standardized treatment algorithms have yet to be created and current recommendations have been adopted from migraine guidelines.

Gut Microbiome and Metabolome Changes in Mice With Acute Vestibular Deficit

Vestibular deficit is a very common disorder in clinical practice and is characterized by vertigo, spontaneous nystagmus, and autonomic nervous symptoms, including nausea, vomiting, and sweating. In addition, the comorbidity of vestibular deficit and anxiety has long been an integral component of the medical literature. Previous studies have suggested that the mechanisms underlying this comorbidity involved overlap of vestibular and cerebellar networks. Emerging evidence has shown that the microbiota–gut–brain axis plays a key role in the regulation of affective disorders. Thus, we hypothesized that the gut microbiota may be involved in the comorbidity of vestibular deficit and anxiety. To verify this, we constructed a unilateral labyrinthectomy mouse model to simulate vestibular deficit. Then, 16S rRNA gene sequencing and liquid chromatography–mass spectrometry (LC-MS) were used to analyze the microbiome and metabolome of the cecal samples collected from mice in the unilateral labyrinthectomy, sham surgery, and control groups. Notably, unilateral labyrinthectomy shaped the composition of the mouse gut microbiome, resulting in increased abundance of Lachnospiraceae NK4A136 group, Odoribacter and Roseburia and decreased abundance of Prevotella and Parasutterella at the genus level. Tax4Fun functional prediction indicated a decrease in tryptophan metabolism in mice in the unilateral labyrinthectomy group. Moreover, functional correlation of changes in gut microbes and metabolites between different groups showed that the oleamide level was negatively correlated with Odoribacter abundance (r = -0.89, p = 0.0002). The butyric acid level was positively correlated with Parasutterella abundance (r = 0.85, p = 0.0010). The propanoate level was negatively correlated with Prevotella abundance (r = -0.81, p = 0.0020). The 20-HETE level was positively correlated with Parasutterella abundance (r = 0.84, p = 0.0013). The altered microbes and metabolites were closely related to the pathogenesis of affective disorders. Our results not only offer novel insights into the vestibular deficit comorbid with anxiety but also build an important basis for future research on this etiology.

Vestibular and auditory manifestations of migraine

PURPOSE OF REVIEW

The purpose of this narrative review is to discuss current literature about vestibular migraine and other cochleovestibular symptoms related to migraine.

RECENT FINDINGS

Vestibular migraine affects 2.7% of the US population. Misdiagnosis is common. The pathophysiology is currently unknown but new research shows that calcitonin gene-related peptide, which is implicated in migraine headaches, is expressed in the audiovestibular periphery. A recent large-scale placebo-controlled trial looking at metoprolol for vestibular migraine was terminated early due to poor recruitment; however, at study completion, no differences were seen between treatment arms. Many other audiovestibular symptoms have been shown to be associated with migraine, including tinnitus, hearing loss, aural fullness, otalgia, and sinus symptoms. Migraine is also associated with risk for developing numerous otologic conditions, including Meniere's disease, vestibular loss, Benign Paroxysmal Positional Vertigo, and sudden sensorineural hearing loss. There is now some evidence that patients may experience fluctuating hearing loss and aural fullness without vertigo in association with migraine, which is called cochlear migraine.

SUMMARY

Migraine can cause a variety of audiologic and vestibular symptoms, and further research is required to understand how migraine affects the inner ear.

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

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

The Efficacy and Safety of Acupuncture for Prophylaxis of Vestibular Migraine: A Study Protocol for a Randomized Controlled Trial

Introduction: With a high incidence rate and low diagnosis rate, vestibular migraine (VM) can seriously affect the quality of life of patients, but it remains difficult to manage by current treatment options. Acupuncture may be a potential treatment option for VM prophylaxis, but the currently available evidence is still uncertain. Therefore, this trial aims to evaluate the efficacy and safety of acupuncture for VM prophylaxis. Methods: This is a 28-week parallel, randomized, controlled clinical trial including 4 weeks of baseline, 8 weeks of treatment, and 16 weeks of follow-up. A total of 72 participants will be randomly assigned to two groups. The participants will receive acupuncture in the experimental group, while the participants in the control group will be treated with venlafaxine. The primary outcome measures are change in vertigo/migraine days and vertigo/migraine attacks, vertigo severity, and migraine intensity per 4 weeks from baseline. The secondary outcome measures are change in doses of rescue medication, anxiety level, depression level, and quality of life per 4 weeks from baseline. Adverse events will be recorded for safety evaluation. Discussion: This study will investigate the efficacy and safety of acupuncture for VM prophylaxis. The results will contribute to determining whether acupuncture can serve as an optional treatment strategy for treating VM. Clinical Trial Registration: www.ClinicalTrials.gov, identifier: NCT0464088.

Current Insights into Treating Vertigo in Older Adults

The number of older people has been increasing over recent decades in Western populations. Dizziness, imbalance, and vertigo constitute some of the most common complaints in older patients, and risk of falling is the most frequent and worrying consequence. It has been reported that 15–20% of the adult population experiences these debilitating symptoms. Among the diseases that may be associated with vertigo, the three classes of otological, central, and functional (psychological) dizziness may be distinguished. Overall, vestibular disorders account for 48% of vertiginous complaints in the older population. The main focus of this article is to review the forms of pharmacotherapy for vertigo, especially with regard to older patients, who may be treated simultaneously with other drugs for different comorbidities. Interactions with other drugs should be considered in the choice of a particular course of treatment. Moreover, overuse of pharmacotherapy for the management of vertigo in the elderly may prevent the development of the central compensatory mechanism that sustains both static and dynamic imbalance after a vertiginous crisis. In the majority of patients, vestibular and physical rehabilitation are strongly advised and rarely contraindicated.

Directional effects of whole-body spinning and visual flow in virtual reality on vagal neuromodulation

BACKGROUND

Neural circuits allow whole-body yaw rotation to modulate vagal parasympathetic activity, which alters beat-to-beat variation in heart rate. The overall output of spinning direction, as well as vestibular-visual interactions on vagal activity still needs to be investigated.

OBJECTIVE

This study investigated direction-dependent effects of visual and natural vestibular stimulation on two autonomic responses: heart rate variability (HRV) and pupil diameter.

METHODS

Healthy human male subjects (n = 27) underwent constant whole-body yaw rotation with eyes open and closed in the clockwise (CW) and anticlockwise (ACW) directions, at 90°/s for two minutes. Subjects also viewed the same spinning environments on video in a VR headset.

RESULTS

CW spinning significantly decreased parasympathetic vagal activity in all conditions (CW open p = 0.0048, CW closed p = 0.0151, CW VR p = 0.0019,), but not ACW spinning (ACW open p = 0.2068, ACW closed p = 0.7755, ACW VR p = 0.1775,) as indicated by an HRV metric, the root mean square of successive RR interval differences (RMSSD). There were no direction-dependent effects of constant spinning on sympathetic activity inferred through the HRV metrics, stress index (SI), sympathetic nervous system index (SNS index) and pupil diameter. Neuroplasticity in the CW eyes closed and CW VR conditions post stimulation was observed.

CONCLUSIONS

Only one direction of yaw spinning, and visual flow caused vagal nerve neuromodulation and neuroplasticity, resulting in an inhibition of parasympathetic activity on the heart, to the same extent in either vestibular or visual stimulation. These results indicate that visual flow in VR can be used as a non-electrical method for vagus nerve inhibition without the need for body motion in the treatment of disorders with vagal overactivity. The findings are also important for VR and spinning chair based autonomic nervous system modulation protocols, and the effects of motion integrated VR.

Episodic Spontaneous Dizziness

PURPOSE OF REVIEW

Conditions causing recurrent spontaneous episodes of dizziness or vertigo span several medical specialties, making it challenging for clinicians to gain confidence in evaluating and managing the spectrum of episodic vestibular disorders. Patients are often asymptomatic and have normal examinations at the time of evaluation. Thus, diagnosis depends heavily on eliciting key features from the history. Overreliance on symptom quality descriptions commonly leads to misdiagnosis. The goal of this article is to provide the reader with a straightforward approach to the diagnosis and management of conditions that cause episodic spontaneous dizziness.

RECENT FINDINGS

Consensus diagnostic criteria have been established for vestibular migraine, Ménière disease, vestibular paroxysmia, and hemodynamic orthostatic dizziness/vertigo. Vertigo has been recognized as a common symptom in vertebrobasilar ischemia, cardiogenic dizziness, and orthostatic hypotension. Treatment recommendations for vestibular migraine still lack high-quality evidence, but controlled trials are occurring.

SUMMARY

The evaluation should start with a detailed description of the episodes from the patient and any observers. Rather than focusing first on whether the symptom quality is most consistent with vertigo, dizziness, lightheadedness, or unsteadiness, the clinician should clarify the timing (episode frequency and duration), possible triggers or circumstances (eg, position changes, upright posture), and accompanying symptoms. History should identify any auditory symptoms, migraine features, posterior circulation ischemic symptoms, vascular risk factors, clues for anxiety, and potentially relevant medications. Carefully selected testing can help secure the diagnosis, but excessive and indiscriminate testing can lead to more confusion. Treatments for these conditions are vastly different, so an accurate diagnosis is critical.

The Treatment of Vestibular Migraine: A Narrative Review

Vestibular migraine (VM) is one of the most debilitating chronic diseases that is currently underdiagnosed and undertreated. The treatment of VM is a dynamic and rapidly advancing area of research. New developments in this field have the potential to improve the diagnosis and provide more individualized treatments for this condition. In this review, we discussed the progress of evidence-based treatment of VM, including pharmacotherapy and nonmedical methods. A search of the literature was conducted up to September 2019. In order to control or cure VM, patients should follow three steps. First, patients should comply with diet and behavioral medication; Second, during the attack of VM, patients should take medicine to control the symptoms. These acute attack treatment of VM consists of antiemetic medications (e.g., dimenhydrinate and benzodiazepines), anti-vertigo medicine, and analgesics (e.g. triptans). Third, prophylactic medicine (e.g., propranolol, topiramate, valproic aid, lamotrigine, and flunarizine) can be used to reduce the frequency and severity of VM attack. Also, vestibular rehabilitation (VR) treatment should be considered for all VM. Meanwhile, we also propose to establish a culture of prevention which is essential for reducing the personal, social and economic burden of VM.

Non-invasive vagus nerve stimulation for primary headache: A clinical update

Background

Non-invasive vagus nerve stimulation (nVNS) is a proven treatment for cluster headache and migraine. Several possible mechanisms of action by which nVNS mitigates headache have been identified.

Methods

We conducted a narrative review of recent scientific and clinical research into nVNS for headache, including findings from mechanistic studies and their possible relationships to the clinical effects of nVNS.

Results

Findings from animal and human studies have provided possible mechanistic explanations for nVNS efficacy in headache involving four core areas: Autonomic nervous system functions; cortical spreading depression inhibition; neurotransmitter regulation; and nociceptive modulation. We discuss how overlap and interplay among these areas may underlie the utility of nVNS in the context of clinical evidence supporting its safety and efficacy as acute and preventive therapy for both cluster headache and migraine. Possible future nVNS applications are also discussed.

Conclusion

Significant progress over the past several years has yielded valuable mechanistic and clinical evidence that, combined with the excellent safety and tolerability profile of nVNS, suggests that it should be considered a first-line treatment for both acute and preventive treatment of cluster headache, an effective option for acute treatment of migraine, and a highly relevant, practical option for migraine prevention.

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.

Peripheral neuromodulation for the treatment of migraine and headache: recent advances

Noninvasive neuromodulation is a rapidly developing field that offers an attractive nonpharmacologic treatment option for headache patients. Devices that stimulate peripheral nerves (e.g., vagus nerve, trigeminal sensory nerve, somatic sensory nerve) or brain parenchyma (e.g., occipital cortex) have been developed for this purpose, with promising results in clinical trials. There are currently four US FDA-cleared devices for the treatment of migraine and/or cluster headache: Cefaly®, a trigeminal nerve stimulator; gammaCore™, a vagus nerve stimulator; sTMS mini™, a transcranial magnetic stimulator and Nerivio™, a remote electrical neurostimulator. This narrative review will provide an overview of FDA-cleared neuromodulatory devices, including their proposed mechanisms of action as well as device safety and efficacy as demonstrated in clinical trials.