Headache and Autonomic Dysfunction: a Review

Cardiovascular and sympathetic neural responses during acute vagus nerve stimulation and subsequent static handgrip exercise in healthy adults

PURPOSE

This study aimed to investigate cardiovascular and sympathetic neural responses during acute cervical non-invasive vagus nerve stimulation (nVNS) and subsequent static handgrip (SHG) exercise with post-exercise circulatory occlusion (PECO) in healthy humans.

METHODS

Ten healthy adults (5 men and 5 women, 33 ± 9 [standard deviation] yrs) participated in this double-blinded, randomized, crossover study. Each participant was studied twice on two separate days, with approximately 4 weeks apart: once during the actual cervical nVNS and once during sham stimulation for 4 min each. Mean arterial pressure (MAP), heart rate (HR), and muscle sympathetic nerve activity (MSNA) were measured during nVNS and sham stimulation. In addition, participants performed SHG at 40 % of maximal voluntary contraction until fatigue, followed by 2-min PECO to isolate muscle metaboreflex activation before and after each stimulation.

RESULTS

During both nVNS and sham stimulation, HR decreased (△-4 ± 4 and △-4 ± 5 bpm; both P < 0.001), and MSNA increased (△4 ± 6 and △2 ± 3 bursts/min; both P < 0.001) in all participants, although MAP remained unchanged (P = 0.312). However, these responses did not differ between nVNS and sham stimulation (all P > 0.05). Additionally, there were no differences in cardiovascular and MSNA responses to fatiguing SHG and PECO between stimulations (all P > 0.05).

CONCLUSION

Compared to the sham condition, cervical nVNS had no significant impact on cardiovascular variables and MSNA during acute stimulation, nor on the responses to SHG or PECO. These findings suggest that cervical nVNS has no or minimal acute effect on sympathetic neural (re)activity in healthy adults.

Migraine and stroke: correlation, coexistence, dependence - a modern perspective

BACKGROUND

Migraine is a chronic neurological condition that has a well-documented, yet not fully understood connection to stroke, particularly in patients who experience migraine with aura (MA). Although migraine can rarely be directly related to stroke, in the form of migrainous infarction, it serves as an independent risk factor, particularly when combined with other factors such as smoking or hypertension. This study will thoroughly review and summarize the existing literature regarding the relationship between migraine and stroke.

MAIN TEXT

Several key processes are common to both stroke and migraine. These include cortical spreading depression, particularly in MA, endothelial dysfunction, which activates local inflammatory responses, and vasculopathy, which often appears as white matter hyperintensities on neuroimaging. Furthermore, microRNAs also play a significant role in the pathogenesis of both migraine and stroke by targeting genes such as CALCA, which regulates calcitonin gene-related peptide, a factor involved in the pathophysiology of both conditions. There are also several genetic links between migraine and stroke, including both monogenic diseases and common risk loci. Moreover, various conditions are linked to both migraine and stroke, including patent foramen ovale (PFO), atrial fibrillation, carotid artery dissection, platelet dysfunction, dyslipidemia, obesity, hyperhomocysteinemia, and elevated estrogen levels, such as in combined hormonal contraceptives. Notably, PFO is often found in patients who have experienced a cryptogenic stroke, as well as in those with MA. While microemboli associated with PFO may provoke ischemic events and migraine attacks, the effectiveness of PFO closure in alleviating migraine symptoms has produced varying results. Migraine is linked to worse outcomes after ischemic stroke, including larger stroke volumes and poorer functional outcomes, while the connection between migraines and hemorrhagic stroke is less understood. Furthermore, migraine may serve as a stroke mimic (condition presenting with symptoms similar to ischemic stroke) or a stroke chameleon (unrecognized stroke misdiagnosed as migraine), leading to significant diagnostic and treatment errors.

CONCLUSIONS

The interplay between migraine and stroke is complex, involving shared pathophysiology and overlapping risk factors. While migraine can serve as both a cause and a risk factor for stroke, the precise mechanisms remain unclear, warranting further research to clarify their connection and enhance clinical management.

Migraine and gastroesophageal reflux disease: Disentangling the complex connection with depression as a mediator

OBJECTIVE

Gastroesophageal reflux disease (GERD) and migraine are public health concerns worldwide. No observational study has conclusively elucidated the causal relationship between these two conditions. We employed Mendelian randomization (MR) methods to explore the potential causal links between GERD and migraine.

METHODS

Genome-wide association studies were subjected to MR to infer the causality between GERD and migraine. Bidirectional two-sample MR was performed to establish causal relationships. Multivariable MR analysis was conducted to adjust potential confounding factors, and mediation MR analysis was utilized to assess the role of depression between GERD and migraine as a mediator. We primarily utilized the inverse variance weighted method (IVW) and sensitivity analysis methods, including MR-Egger, weighted median, and leave-one-out methods. We assessed heterogeneity and pleiotropy to ensure the reliability of the results.

RESULTS

Bidirectional two-sample MR revealed a positive causal effect of GERD on migraine (IVW: OR = 1.49, 95% CI: 1.34-1.66, p = 3.70E-13). Migraine did not increase the risk of GERD (IVW: OR = 1.07, 95% CI: 0.98-1.17, p = 0.1139). Multivariable MR indicated that the positive causal effect of GERD on migraine remained after adjustment for factors, such as smoking, alcohol consumption, obesity, type 2 diabetes, and depression. Mediation MR revealed that depression mediated 28.72% of GERD's effect on migraine. MR analysis was supported by all sensitivity analyses and was replicated and validated in another independent dataset on migraine.

CONCLUSION

Our findings elucidate the positive causal effect of GERD on migraine and underscores the mediating role of depression in increasing the risk of migraine due to GERD. Effective control of GERD, particularly interventions targeting depression, may aid in preventing the occurrence of migraine. Future research should delve deeper into the specific pathophysiological mechanisms through which GERD affects migraine risk, facilitating the development of more effective drug targets or disease management strategies.

Headaches Attributed to Disorders of Homeostasis

Headaches attributed to disorders of homeostasis include those different headache types associated with metabolic and systemic diseases. These are headache disorders occurring in temporal relation to a disorder of homeostasis including hypoxia, high altitude, airplane travel, diving, sleep apnea, dialysis, autonomic dysreflexia, hypothyroidism, fasting, cardiac cephalalgia, hypertension and other hypertensive disorders like pheochromocytoma, hypertensive crisis, and encephalopathy, as well as preeclampsia or eclampsia. The proposed mechanism behind the causation of these headache subtypes including diagnostic criteria, evaluation, treatment, and overall management will be discussed.

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

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

The evolutionary meaning of migraine

INTRODUCTION

Migraine's astonishing prevalence and preserved genetic background contrast with the definition of a disease and the biological meaning of experiencing recurrent, severe headache attacks is still puzzling.

METHODS

To provide a comprehensive explanation of the migraine evolutionary meaning, we review (i) the putative role of the autonomic nervous system in migraine attacks, (ii) the inter-ictal autonomic, functional, and metabolic signature of migraine patients, (iii) the bio-behavioral perspective of pain, and (iv) the allostatic perception of migraine chronification.

RESULTS

Migraineurs have inter-ictal cortical hyperexcitability and metabolic dysfunction that predisposes to brain energetic imbalance. Multiple precipitating factors may lead to brain energy consumption over the migraine attack generation threshold. In response, the brain engenders adaptive, evolutionary conserved, autonomic-behavior responses through the antidromic activation of the trigeminovascular system. The sickness behavior and severe pain experienced during migraine attacks result in avoiding mental and physical activity, allowing brain energy restoration. Chronic exposure to stressors may result in an allostatic overload, leading to maladaptive chronic activation of these responses. In this bio-behavioral perspective, the chronification of migraine should be envisioned as a pathological process, whereas the migraine itself should not.

CONCLUSION

Migraine has an evolutionary (Darwinian) meaning.

Narrative Review of Postural Orthostatic Tachycardia Syndrome: Associated Conditions and Management Strategies

Postural orthostatic tachycardia syndrome (POTS) is a heterogeneous disorder that presents with positional tachycardia and a constellation of other symptoms. Peer-reviewed evidence for treatment options is limited. In addition, there are various associated conditions with overlapping symptoms. These factors can make the diagnosis and management of POTS a frustrating experience for both providers and patients. This paper aims to combine available scientific data with anecdotal evidence derived from extensive clinical experience to provide information on recognizing the clinical features of POTS, identifying associated conditions, and understanding treatment strategies to help providers better diagnose and manage patients with this condition.

Sleep and Chronobiology as a Key to Understand Cluster Headache

The cluster headache is a primary headache characterized by attacks of unilateral pain associated with ipsilateral cranial autonomic features. These attacks recur in clusters during the years alternating with periods of complete remission, and their onset is often during the night. This annual and nocturnal periodicity hides a strong and mysterious link among CH, sleep, chronobiology and circadian rhythm. Behind this relationship, there may be the influence of genetic components or of anatomical structures such as the hypothalamus, which are both involved in regulating the biological clock and contributing even to the periodicity of cluster headaches. The bidirectional relationship manifests itself also with the presence of sleep disturbances in patients affected by cluster headaches. What if the key to studying the physiopathology of such disease could rely on the mechanisms of chronobiology? The purpose of this review is to analyze this link in order to interpret the pathophysiology of cluster headaches and the possible therapeutic implications.