Migraine pathophysiology: anatomy of the trigeminovascular pathway and associated neurological symptoms, CSD, sensitization and modulation of pain

Multi-region local field potential signatures and brain coherence alternations in response to nitroglycerin-induced migraine attacks

OBJECTIVE

To decipher the underlying mechanisms of nitroglycerin (NTG)-induced migraine electrophysiologically.

BACKGROUND

Migraine is a recurrent primary headache disorder with moderate to severe disability; however, the pathophysiology is not fully understood. Consequently, safe and effective therapies to alleviate migraine headaches are limited. Local field potential (LFP) recording, as a neurophysiological tool, has been widely utilized to investigate combined neuronal activity.

METHODS

We recorded LFP changes simultaneously from the anterior cingulate cortex, posterior nucleus of the thalamus, trigeminal ganglion, and primary visual cortex after NTG injection in both anesthetized and freely moving rats. Additionally, brain coherence was processed, and light-aversive behavior measurements were implemented.

RESULTS

Significant elevations of LFP powers with various response patterns for the delta, theta, alpha, beta, and gamma bands following NTG injection were detected in both anesthetized and freely moving rats; however, a surge of coherence alternations was exclusively observed in freely moving rats after NTG injection.

CONCLUSION

The multi-region LFP signatures and brain coherence alternations in response to NTG-induced migraine attacks were determined. Furthermore, the results of behavior measurements in the freely moving group indicated that NTG induced the phenomenon of photophobia in our study. All these findings offer novel insights into the interpretation of migraine mechanisms and related treatments.

Psychosocial factors associated with pain outcomes in patients with painful temporomandibular disorders and headaches

The objective of this study was to assess the association between psychosocial factors (in terms of anxiety, somatization, depression, and optimism) and pain (in terms of headache pain intensity and pain-related disability), in patients with a painful temporomandibular disorder (TMD) and one of the following headache types: migraine, tension-type headache (TTH), or headache attributed to TMD, corrected for the influence of bruxism. A retrospective study was conducted at an orofacial pain and dysfunction (OPD) clinic. Inclusion criteria were painful TMD, with migraine, TTH, and/or headache attributed to TMD. Linear regressions were performed to assess the influence of psychosocial variables on pain intensity and on pain-related disability, stratified per headache type. The regression models were corrected for bruxism and the presence of multiple headache types. A total of 323 patients (61% female; mean age 42.9, SD 14.4 years) were included. Headache pain intensity only had significant associations in TMD-pain patients with headache attributed to TMD, and anxiety showed the strongest relation (β = 0.353) with pain intensity. Pain-related disability was most strongly associated with depression in TMD-pain patients with TTH (β = 0.444), and with somatization in patients with headache attributed to TMD (β = 0.399). In conclusion, the influence of psychosocial factors on headache pain intensity and pain-related disability depends on the headache type presenting.

Manual Therapy and Exercise for the Management of Chronic Neck Pain With Multiple Neurovascular Comorbidities: A Case Report

This case describes the clinical decision-making behind the conservative clinical management of an individual presenting with chronic neck pain with myriad neuromuscular comorbidities. The focus of this case report is to support the safe utilization of manual therapy and describe the tolerable prescription of strength and endurance exercise in a patient with numerous complications to improve self-efficacy. A 22-year-old female college student presented with a chief complaint of chronic, non-specific neck pain with comorbid Chiari malformation, migraines, upper cervical spinal fusion, Ehlers-Danlos syndrome (EDS), and postural orthostatic tachycardia syndrome (POTS) to an outpatient physical therapy clinic for evaluation and treatment. Following four sessions of physical therapy treatment, no clinically significant improvement in the individual's symptoms and daily function was achieved. Despite the lack of measurable change, the patient reported the program's value on her ability to self-manage her complex condition. The patient responded well to manual therapy, specifically thrust manipulations. In addition, both endurance and strengthening exercises were well tolerated and provided a measure of self-management that may not have been achieved before physical therapy management. This case report highlights the need for exercise and pain-modulating interventions in highly complex individuals to reduce medical intervention by advancing the patient's self-efficacy. There is a need for further research about the utility of standardized outcome measures, joint manipulations, and the addition of cervico-ocular exercises for those who present with neck pain and pertinent neuromuscular comorbidities.

Electroacupuncture at Fengchi(GB20) and Yanglingquan(GB34) Ameliorates Paralgesia through Microglia-Mediated Neuroinflammation in a Rat Model of Migraine

Background: Multiple studies have suggested that paralgesia (hyperalgesia and cutaneous allodynia) in migraine reflects the activation and sensitisation of the trigeminovascular system (TGVS). In particular, it reflects the second-order and higher nerve centre sensitisation, which is caused and maintained by neuroinflammation. Microglia activation leads to the release of proinflammatory cytokines involved in inflammatory responses. Accumulating evidence indicates that electroacupuncture (EA) is effective in ameliorating paralgesia, but the underlying mechanisms of EA in migraine attacks caused by microglia and microglia-mediated inflammatory responses are still unclear. The purpose of this study was to explore whether EA could ameliorate the dysregulation of pain sensation by suppressing microglial activation and the resulting neuroinflammatory response, and to evaluate whether this response was regulated by Toll-like receptor 4 (TLR4)/nuclear factor-kappa B(NF-κB) in the trigeminal nucleus caudalis (TNC) in a rat model of migraine. Methods: Repeated Inflammatory Soup (IS) was infused into the dura for seven sessions to establish a recurrent migraine-like rat model, and EA treatment was administered at Fengchi (GB20) and Yanglingquan (GB34) after daily IS infusion. Facial mechanical withdrawal thresholds were measured to evaluate the change in pain perception, and plasma samples and the TNC tissues of rats were collected to examine the changes in calcitonin gene-related peptide (CGRP), the Ibal-1-labelled microglial activation, and the resulting inflammatory response, including interleukin-1β (IL-1β), tumour necrosis factor-α (TNF-α), interleukin-6 (IL-6), and their regulatory molecules TLR4/NF-κB, via enzyme-linked immunosorbent assay (ELISA), real-time polymerase chain reaction (RT-PCR), immunohistochemistry (IHC) and Western blot analysis. Results: Repeated IS injections into the dura induced facial mechanical paralgesia, which is the manifestation of migraine attacks, and increased the expression of CGRP, Ibal-1, microglial mediated inflammatory cytokines (IL-1β, TNF-α, IL-6), and regulatory molecules TLR4/NF-κB. EA at GB20/34 significantly attenuated repetitive IS-induced pain hypersensitivity. This effect was consistent with decreased levels of CGRP and inflammatory cytokines in the plasma and the TNC via the inhibition of microglia activation, and this response may be regulated by TLR4/NF-κB. Conclusions: EA ameliorated paralgesia in repetitive IS-induced migraine-like rats, which was mainly mediated by a reduction in microglial activation and microglial-mediated inflammatory responses that could be regulated by TLR4/NF-κB.

A study on the correlation of the asymmetric regulation between the periaqueductal gray and the bilateral trigeminal nucleus caudalis in migraine male rats

BACKGROUND

The study was designed to explore the correlation of the asymmetric regulation between periaqueductal gray (PAG) and bilateral trigeminal nucleus caudalis (TNC) in migraine rats through studying the changes of metabolites in pain regulatory pathway of acute migraine attack.

METHODS

Thirty male Sprague-Dawley (SD) rats were randomly divided into three groups: blank, control, model groups. Then, blank group was intraperitoneally injected with ultrapure water, while control group injected with saline and model group injected with Glyceryl Trinitrate (GTN). Two hours later, PAG and bilateral TNC were removed respectively, and metabolite concentrations of PAG, Left-TNC, Right-TNC were obtained. Lastly, the differences of metabolite among three brain tissues were compared.

RESULTS

The relative concentrations of rNAA, rGlu, rGln, rTau, rMI in PAG or bilateral TNC had interaction effects between groups and sites. The concentration of rLac of three brain tissues increased in migraine rats, however, the rLac of LTNC and RTNC increased more than that of PAG. Besides, the concentrations of rNAA and rGln increased in RTNC, while rGABA decreased in RTNC.

CONCLUSIONS

There is correlation between PAG, LTNC and RTNC in regulation of pain during acute migraine attack, and the regulation of LTNC and RTNC on pain is asymmetric.

Peroxynitrite Contributes to Behavioral Responses, Increased Trigeminal Excitability, and Changes in Mitochondrial Function in a Preclinical Model of Migraine

Administration of a nitric oxide (NO) donor triggers migraine attacks, but the mechanisms by which this occurs are unknown. Reactive nitroxidative species, including NO and peroxynitrite (PN), have been implicated in nociceptive sensitization, and neutralizing PN is antinociceptive. We determined whether PN contributes to nociceptive responses in two distinct models of migraine headache. Female and male mice were subjected to 3 consecutive days of restraint stress or to dural stimulation with the proinflammatory cytokine interleukin-6. Following resolution of the initial poststimulus behavioral responses, animals were tested for hyperalgesic priming using a normally non-noxious dose of the NO donor sodium nitroprusside (SNP) or dural pH 7.0, respectively. We measured periorbital von Frey and grimace responses in both models and measured stress-induced changes in 3-nitrotyrosine (3-NT) expression (a marker for PN activity) and trigeminal ganglia (TGs) mitochondrial function. Additionally, we recorded the neuronal activity of TGs in response to the PN generator SIN-1 [5-amino-3-(4-morpholinyl)-1,2,3-oxadiazolium chloride]. We then tested the effects of the PN decomposition catalysts Fe(III)5,10,15,20-tetrakis(N-methylpyridinium-4-yl) porphyrin (FeTMPyP) and FeTPPS [Fe(III)5,10,15,20-tetrakis(4-sulfonatophenyl)porphyrinato chloride], or the PN scavenger MnTBAP [Mn(III)tetrakis(4-benzoic acid)porphyrin] against these behavioral, molecular, and neuronal changes. Neutralizing PN attenuated stress-induced periorbital hypersensitivity and priming to SNP, with no effect on priming to dural pH 7.0. These compounds also prevented stress-induced increases in 3-NT expression in both the TGs and dura mater, and attenuated TG neuronal hyperexcitability caused by SIN-1. Surprisingly, FeTMPyP attenuated changes in TG mitochondrial function caused by SNP in stressed males only. Together, these data strongly implicate PN in migraine mechanisms and highlight the therapeutic potential of targeting PN.SIGNIFICANCE STATEMENT Among the most reliable experimental triggers of migraine are nitric oxide donors. The mechanisms by which nitric oxide triggers attacks are unclear but may be because of reactive nitroxidative species such as peroxynitrite. Using mouse models of migraine headache, we show that peroxynitrite-modulating compounds attenuate behavioral, neuronal, and molecular changes caused by repeated stress and nitric oxide donors (two of the most common triggers of migraine in humans). Additionally, our results show a sex-specific regulation of mitochondrial function by peroxynitrite following stress, providing novel insight into the ways in which peroxynitrite may contribute to migraine-related mechanisms. Critically, our data underscore the potential in targeting peroxynitrite formation as a novel therapeutic for the treatment of migraine headache.

Migraine as an inflammatory disorder with microglial activation as a prime candidate

BACKGROUND

The lower threshold of neuronal hyperexcitability has been correlated with migraines for decades but as technology has progressed, it has now become conceivable to learn more about the migraine disease. Apart from the "cortical spreading depression" and "activation of the trigeminovascular system", inflammation has been increasingly recognized as a possible pathogenic process that may have the possibility to regulate the disease severity. Microglial cells, the prime candidate of the innate immune cells of central nervous tissue, has been associated with numerous diseases; including cancer, neurodegenerative disorders, and inflammatory disorders.

AIM

In this review, we have attempted to link the dot of various microglial activation signaling pathways to enlighten the correlation between microglial involvement and the progression of migraine conditions.

METHOD

A structured survey of research articles and review of the literature was done in the electronic databases of Google Scholar, PubMed, Springer, and Elsevier until 31 December 2021.

RESULT & CONCLUSION

Of 1136 articles found initially and screening of 1047 records, 47 studies were included for the final review. This review concluded that inflammation and microglial overexpression as the prime candidate, plays an important role in the modulation of migraine and are responsible for the progression toward chronification. Therefore, this increases the possibility of preventing migraine development and chronification by blocking microglia overexpression.

Modulation of amygdala activity for emotional faces due to botulinum toxin type A injections that prevent frowning

According to the facial feedback hypothesis, when we see an angry or happy face, we contract or flex the relevant muscles to recreate the expression to assist in identifying and experiencing the emotion reflected. We investigated the facial feedback hypothesis by using botulinum toxin type A (onabotulinumtoxinA; onabotA) injections to induce temporary paralysis in the glabellar muscles (responsible for frowning) and measured functional brain activity during the processing of emotional faces. Ten females viewed pictures of happy and angry faces during two functional magnetic resonance imaging (fMRI) scan sessions: one prior (Pre) to onabotA and one following (Active) onabotA injections. We found Pre vs. Active onabotA modulation of activity in the amygdala for both happy and angry faces, as well as modulation of activity in the fusiform gyrus for happy faces. Consistent with our predictions, preventing frowning through inhibition of glabellar muscle contraction altered amygdala processing for emotional faces. The modulation of amygdala and fusiform gyrus activity following onabotA may reflect compensatory processes in a neuroanatomical circuit involved in emotional processing that is engaged when facial feedback is impaired. These data contribute to a growing literature suggesting that inhibition of glabellar muscle contraction alters neural activity for emotional processing.Clinical Trials.gov registration number: NCT03373162.

Predictors of response to galcanezumab in patients with chronic migraine: a real-world prospective observational study

BACKGROUND

Despite high efficacy and tolerability, not all patients with chronic migraine benefit from anti-CGRP monoclonal antibodies. We aimed to identify the clinical predictors of the response to galcanezumab treatment in patients with chronic migraine from real-world data.

METHODS

We prospectively recruited patients with CM who underwent galcanezumab injections between December 2019 and February 2022. Treatment response was determined after three months of follow-up and was defined as ≥ 50% reduction in monthly headache days. The migraine characteristics, comorbidities, and other treatment responses were compared between the responder and non-responder groups.

RESULTS

Of 238 patients with CM, 153 (64.3%) showed treatment response. The responder group was younger, had lower frequency of baseline headache days, and had more accompanying symptoms such as nausea, vomiting, and photophobia. Better triptan response and less depression were also observed in the responder group. Multivariable regression analysis revealed that the everyday headache (OR = 0.351, 95% CI = 0.133-0.874, p = 0.017), depression (OR = 0.439, 95% CI = 0.216-0.896, p = 0.024) and absence of accompanying symptoms (OR = 0.314, 95% CI = 0.118-0.834, p = 0.020) were significantly associated with response to galcanezumab treatment.

CONCLUSIONS

Our real-world data showed the efficacy of galcanezumab in patients with CM, regardless of medication overuse. Everyday headache, presence of depression, and absence of accompanying symptoms of migraine were significant predictors of a poor response.

Application of EEG in migraine

Migraine is a common disease of the nervous system that seriously affects the quality of life of patients and constitutes a growing global health crisis. However, many limitations and challenges exist in migraine research, including the unclear etiology and the lack of specific biomarkers for diagnosis and treatment. Electroencephalography (EEG) is a neurophysiological technique for measuring brain activity. With the updating of data processing and analysis methods in recent years, EEG offers the possibility to explore altered brain functional patterns and brain network characteristics of migraines in depth. In this paper, we provide an overview of the methodology that can be applied to EEG data processing and analysis and a narrative review of EEG-based migraine-related research. To better understand the neural changes of migraine or to provide a new idea for the clinical diagnosis and treatment of migraine in the future, we discussed the study of EEG and evoked potential in migraine, compared the relevant research methods, and put forwards suggestions for future migraine EEG studies.

Revisiting Migraine: The Evolving Pathophysiology and the Expanding Management Armamentarium

Migraine affects about one billion people worldwide yearly and is one of the most common neurologic illnesses, with a high prevalence and morbidity, particularly among young adults and females. Migraine is associated with many comorbidities, including stress, sleep difficulties, and suicidal ideation. Migraine, despite its widespread occurrence, is underdiagnosed and undertreated. Because of the complicated and primarily unknown mechanisms of migraine formation, several social and biological risk factors, such as hormone imbalances, genetic and epigenetic impacts, and cardiovascular, neurological, and autoimmune illnesses, have been proposed. Through the mid-20th century diversion of the now-defunct vascular theory, the pathophysiology of migraine has developed from a historical study of the "humours" to a distinct entity as a neurological disorder. The range of therapeutic targets has broadened significantly, increasing the number of specialized clinical trials. Understanding the biology of migraine through careful research has resulted in the identification of major therapeutic classes: (i) triptans, serotonin 5-HT1B/1D receptor agonists, (ii) gepants, calcitonin gene-related peptide (CGRP) receptor antagonists, (iii) ditans, 5-HT1F receptor agonists, (iv) CGRP monoclonal antibodies, and (v) glurants, mGlu5 modulators, with further targets being explored. This review provides a comprehensive overview of the most recent literature on epidemiology and risk factors and exposes knowledge gaps.

Spontaneous brain activity abnormalities in migraine: A meta-analysis of functional neuroimaging

Neuroimaging studies have demonstrated that migraine is accompanied by spontaneous brain activity alterations in specific regions. However, these findings are inconsistent, thus hindering our understanding of the potential neuropathology. Hence, we performed a quantitative whole-brain meta-analysis of relevant resting-state functional imaging studies to identify brain regions consistently involved in migraine. A systematic search of studies that investigated the differences in spontaneous brain activity patterns between migraineurs and healthy controls up to April 2022 was conducted. We then performed a whole-brain voxel-wise meta-analysis using the anisotropic effect size version of seed-based d mapping software. Complementary analyses including jackknife sensitivity analysis, heterogeneity test, publication bias test, subgroup analysis, and meta-regression analysis were conducted as well. In total, 24 studies that reported 31 datasets were finally eligible for our meta-analysis, including 748 patients and 690 controls. In contrast to healthy controls, migraineurs demonstrated consistent and robust decreased spontaneous brain activity in the angular gyrus, visual cortex, and cerebellum, while increased activity in the caudate, thalamus, pons, and prefrontal cortex. Results were robust and highly replicable in the following jackknife sensitivity analysis and subgroup analysis. Meta-regression analyses revealed that a higher visual analog scale score in the patient sample was associated with increased spontaneous brain activity in the left thalamus. These findings provided not only a comprehensive overview of spontaneous brain activity patterns impairments, but also useful insights into the pathophysiology of dysfunction in migraine.

Clinical Neuroimaging of Photophobia in Individuals With Chronic Ocular Surface Pain

PURPOSE

To examine neural mechanisms underlying photophobia in individuals with chronic ocular surface pain by using functional magnetic resonance imaging (fMRI).

DESIGN

Cross-sectional case/control analysis.

METHODS

A total of 16 individuals from the Miami Veterans Affairs eye clinic underwent comprehensive ocular surface evaluations and were surveyed for ocular surface symptoms. Case patients included patients who reported chronic ocular surface pain symptoms and light sensitivity at least most of the time over 1 week. Controls included persons without chronic ocular surface pain who reported no or minimal light sensitivity. All patients viewed light stimuli during 2 fMRI scans, one before and one after topical anesthetic instillation, and rated their level of pain intensity to the stimulus at the end of each scan. Areas of brain activation in response to light stimuli presentation were correlated with pain responses and examined post- vs pre-anesthesia.

RESULTS

Case patients (n = 8) reported higher pain intensity ratings than controls (n = 8) in response to light stimuli during fMRI. Case patient ratings correlated more with light-evoked activation in pain-related areas within the trigeminal brainstem, primary somatosensory cortex (S1), anterior mid-cingulate cortex (aMCC), and insula than in controls. Topical anesthesia led to varying responses in pain ratings among case patients as well as decreased light-evoked activation in S1 and aMCC.

CONCLUSIONS

The trigeminal nociceptive system may contribute to photophobia in individuals with chronic ocular surface pain. We demonstrate modulation of cortical structures in this pathway with topically applied anesthetic to the eyes. Further understanding of modulatory interactions that govern ocular surface pain and photophobia is critical for developing effective, precision-based therapies.

Orofacial Migraine or Neurovascular Orofacial Pain from Pathogenesis to Treatment

The purpose of the present study is to examine possible differences between orofacial migraine (OFM) and neurovascular orofacial pain (NVOP). Facial presentations of primary headache are comparable to primary headache disorders; but occurring in the V2 or V3 dermatomes of the trigeminal nerve. These were classified and recently published in the International Classification of Orofacial Pain, 1st edition (ICOP). A category in this classification is "orofacial pains resembling presentations of primary headaches," which encompasses OFM and NVOP. The differences between NVOP and OFM are subtle, and their response to therapy may be similar. While classified under two separate entities, they contain many features in common, suggesting a possible overlap between the two. Consequently, their separation into two entities warrants further investigations. We describe OFM and NVOP, and their pathophysiology is discussed. The similarities and segregating clinical signs and symptoms are analyzed, and the possibility of unifying the two entities is debated.

Decreased ALFF and Functional Connectivity of the Thalamus in Vestibular Migraine Patients

BACKGROUND

The thalamus has been reported to be associated with pain modulation and processing. However, the functional changes that occur in the thalamus of vestibular migraine (VM) patients remain unknown.

METHODS

In total, 28 VM patients and 28 healthy controls who were matched for age and sex underwent resting-state functional magnetic resonance imaging. They also responded to standardized questionnaires aimed at assessing the clinical features associated with migraine and vertigo. Differences in the amplitude of low-frequency fluctuation (ALFF) were analyzed and brain regions with altered ALFF in the two groups were used for further analysis of whole-brain functional connectivity (FC). The relationship between clusters and clinical features was investigated by correlation analyses.

RESULTS

The ALFF in the thalamus was significantly decreased in the VM group versus the control group. In the VM group, the ALFF in the left thalamus negatively correlated with VM episode frequency. Furthermore, the left thalamus showed significantly weaker FC than both regions of the medial prefrontal cortex, both regions of the anterior cingulum cortex, the left superior/middle temporal gyrus, and the left temporal pole in the VM group.

CONCLUSIONS

The thalamus plays an important role in VM patients and it is suggested that connectivity abnormalities of the thalamocortical region contribute to abnormal pain information processing and modulation, transmission, and multisensory integration in patients with VM.

The effect of bright light therapy in migraine patients with sleep disturbance: A prospective, observational cohort study protocol

Background

Migraine is a common disabling disorder, and its substantial burden is associated with a considerable negative impact on the patients' quality of life. Moreover, aging patients with migraine have more cognitive complaints. Additionally, the elderly are more likely to have sleep disturbances, which may also predict the risk of incident dementia. Migraines are reported to be closely associated with sleep and circadian rhythms. Sleep disturbance is a well-known trigger for migraine episodes; moreover, shift work or jet lag reportedly triggers some migraines. The hypothalamus is thought to be the migraine generator; sleep and circadian activity rhythm are also controlled by the hypothalamus. Evidence suggests an influence of both sleep and circadian system on migraine. Previously, light therapy has been show to stabilize sleep architecture and further improve insomnia related to circadian rhythm disorders. However, the beneficial effect of light therapy on migraine with sleep disturbance has not yet been determined. We aim to explore the effects of light therapy for migraine combined with sleep disturbance.

Methods and analysis

This project is a 2-year, randomized, double-blind, placebo-controlled clinical trial. The study design includes a 4-week monitoring period (baseline and pretest), a 4-week treatment period, and a posttest. The study participants will undergo assessments on headache frequency and severity and subjective and objective (wrist actigraphy and polysomnography) sleep disturbances, and quality of life and a series of blood tests for serum biomarkers.

Discussion

This study will establish evidence-based alternative medicine for the preventive effect of bright light therapy in migraine patients with sleep disturbances. Moreover, our data will be useful to comprehend the biochemical mechanism of light therapy in migraine prevention.Clinical Trial Registration: ClinicalTrials.gov, identifier NCT04890691.

Temporal alterations of pituitary adenylate cyclase activating polypeptide and its receptors in a rat model induced by recurrent chemical stimulations: Relevant to chronic migraine

Background: Migraine is a common type of primary headache with disabling brain dysfunction. It has been found that pituitary adenylate cyclase activating polypeptide (PACAP) is involved in the pathogenesis of migraine, however, the role of PACAP and its receptors in chronic migraine remains unclear. Therefore, the present study aimed to explore the changes of PACAP and its receptors in different duration after recurrent dural inflammation soup stimulations and to investigate the co-expression between PACAP and calcitonin gene-related peptide (CGRP). Methods: Adult male rats were implanted with cannula surrounding superior sagittal sinus, which was followed by dural infusion of inflammatory soup (IS) or normal saline (NS). The rats were randomly divided into 4 groups (n = 8 for each group): IS stimulation for seven days (IS-7 group), IS stimulation for 14 days (IS-14 group), IS stimulation for 21 days (IS-21 group), and NS control for 21 days (CON group). The facial mechanical withdrawal threshold was daily measured during the whole experiment. The behavioral changes (ipsilateral and bilateral face grooming behavior) in a plastic cage of rats were observed and recorded. The expression of PACAP, its receptors (PAC1, VPAC1, VPAC2), and CGRP in the trigeminal ganglia (TG) and the trigeminal nucleus caudalis (TNC) was examined by immunohistochemistry. Immunofluorescence was used to explore the co-expression of PACAP, PAC1 receptor, and CGRP after repeated IS administration in the TG. Results: The ipsilateral facial grooming time of IS-21 group displayed an apparent increase than CON group after repeated stimulation on day 2, while significant differences were observed on day 14. No differences were found between the IS-21 and CON group in bilateral facial grooming. Dural IS stimulation induced a significantly decrease in facial mechanical withdrawal thresholds. PACAP positive cells in the regions of TNC were gradually decreased with the IS days increasing. PACAP and PAC1 receptor expression in the TG had a trend of increasing first and then decreasing. There was no significant difference in expression of VPAC1 and VPAC2 in the TG and the TNC. Immunofluorescence showed that PACAP was mainly expressed in TG neurons. PACAP and PAC1 receptor co-expression decreased gradually after repetitive IS stimulation. While the co-expression between PACAP and CGRP reached the peak in IS-7 group after repetitive IS stimulation, and then decreased. Conclusions: This study demonstrated that repetitive chemical stimulations induced a gradual decrease of PACAP in the TNC, while the PACAP and PAC1 receptor expression in TG showed dynamical changes of increasing first and then decreasing after repeated IS administration. These results suggested exhaustion of PACAP could be involved in the duration of chronic migraine and implied PACAP may contribute to the pathology of migraine through the PAC1 receptor, which was associated with CGRP.

OnabotulinumtoxinA: Still the Present for Chronic Migraine

OnabotulinumtoxinA (BT-A) is one of the few drugs approved for the preventive treatment of chronic migraine (CM). Despite this, some aspects of its mechanism of action are still a matter of debate, and the precise magnitude of BT-A effects needs to be completely elucidated. BT-A acts primarily upon trigeminal and cervical nerve endings, by inhibiting the release of inflammatory mediators such as calcitonin gene-related peptide, as well as reducing the insertion of ionotropic and metabotropic receptors into the neuronal membrane. These actions increase the depolarization threshold of trigeminal and cervical nerve fibers, thus reducing their activation. The central actions of BT-A are still a matter of debate: a retrograde axonal transport has been postulated, but not clearly assessed in humans. Clinically, the efficacy of BT-A in CM has been assessed by large, randomized placebo-controlled trials, such as the Phase 3 REsearch Evaluating Migraine Prophylaxis Therapy (PREEMPT) trials. Those results were also confirmed in a wide range of open-label studies, even for long-term periods. Recently, novel findings have led to a better understanding of its pharmacological actions and clinical usefulness in migraine prevention. This narrative review summarizes, updates and critically revises the available data on BT-A and its possible implementation in chronic migraine. Moreover, the current role of BT-A in CM treatment has been discussed.

Neuropsychological and Neuropsychiatric Features of Chronic Migraine Patients during the Interictal Phase

This study aimed to examine the presence of neuropsychological deficits and their relationships with clinical, pharmacological, and neuropsychiatric characteristics in chronic migraine (CM) patients assessed during a headache-free period. We enrolled 39 CM patients (mean age: 45.4 years; male/female ratio: 3/36) and 20 age-, sex-, and education-matched healthy controls (HCs, mean age: 45.5 years; male/female ratio: 2/18) in a case-control study. All CM patients underwent a full and extensive clinical, neuropsychiatric, and neuropsychological evaluation to evaluate cognitive domains, including sustained attention (SA), information processing speed (IPS), visuospatial episodic memory, working memory (WM), and verbal fluency (VF), as well as depressive and anxiety symptoms. CM patients exhibited higher scores than HCs for all clinical and neuropsychiatric measures, but no differences were found in personality characteristics. Although more than half of the CM patients (54%) showed mild-to-severe neuropsychological impairment (NI), with the most frequent impairments occurring in short- and long-term verbal episodic memory and inhibitory control (in approximately 90% of these patients), almost half of the patients (46%) showed no NI. Moreover, the severity of NI was positively associated with the number of pharmacological treatments received. Remarkably, disease-related symptom severity and headache-related disability explained global neuropsychological performance in CM patients. The presence of cognitive and neuropsychiatric dysfunction during the interictal phase occurred in more than half of CM patients, increasing migraine-related disability and possibly exerting a negative impact on health-related quality of life and treatment adherence.

Management and outcomes of persistent headache after accidental dural puncture in the obstetric population: A 9-year prospective audit

OBJECTIVE

To assess the effectiveness and safety of a novel management pathway in the obstetric population presenting to a pain medicine clinic with persistent headache after accidental dural puncture (PHADP).

BACKGROUND

Accidental dural puncture (ADP) can result in headaches that persist for months to years. These headaches can be a therapeutic challenge, often cause severe disability, and management pathway remains obscure.

METHODS

Obstetric patients with PHADP referred to a pain medicine physician were prospectively followed up in a longitudinal audit of a novel management pathway. ADP reports dated from 2008 until 2019. Initial management included brain imaging and pharmacological agents. Patients who failed to respond were offered greater occipital nerve (GON) block with depot methylprednisolone followed by pulsed radiofrequency (PRF) treatment. A headache diary was completed for 4 weeks prior to commencing treatment and maintained for 24 weeks following an intervention. Data collected included use of epidural blood patch to manage postdural puncture headache, past history of headache, severity of headache, duration of persistent headache, low back pain, and employment status.

RESULTS

Over the 9-year period, a cohort of 54 obstetric patients with PHADP with a 16-gauge Tuohy needle were reviewed in the pain clinic. Forty patients presented with chronic daily headache (40/54, 74%). Brain imaging did not reveal any sign of intracranial hypotension in 50 patients (50/54, 93%). Mean follow-up period was 5.7 years. Two patients were lost to follow-up (2/54, 4%). Pharmacological management was effective in 17 patients (17/52, 33%). Medical management failed to improve symptoms in 35 patients (35/52, 67%), and they were offered GON block. Fourteen (14/35, 40%) patients refused the intervention. Nerve block was performed in 21 patients and produced durable benefit lasting 24 weeks in 18 patients (18/21, 86%). Three patients underwent PRF treatment to GONs and all three (100%) reported durable benefit. At final follow-up, mean monthly headache frequency was 5.9 for the medical management group, 8.6 for the refused nerve block group, and 4.1 in patients who received GON treatment (p < 0.001).

CONCLUSION

ADP can cause chronic headaches that persist beyond 3 years. Interventions targeting the GONs appear to have a role in the management of PHADP.

Benign paroxysmal vertigo of childhood

Benign paroxysmal vertigo of childhood (or recurrent vertigo of childhood) is the most common cause of vertigo in young children. It is considered a pediatric migraine variant or precursor disorder, and children with the condition have an increased likelihood of developing migraine later in life than the general population. Episodes are typically associated with room-spinning vertigo in conjunction with other migrainous symptoms (e.g. pallor, nausea, etc.), but it is rarely associated with headaches. Episodes typically only last for a few minutes and occur with a frequency of days to weeks without interictal symptoms or exam/test abnormalities. Treatment is rarely necessary, but migraine therapy may be beneficial in cases where episodes are particularly severe, frequent, and/or prolonged. An appreciation of the typical presentation and characteristics of this common condition is essential to any provider responsible for the care of children with migraine disorders and/or dizziness. This chapter will review the current literature on this condition, including its proposed pathophysiology, clinical presentation, and management. This chapter also includes a brief introduction to pediatric vestibular disorders, including relevant anatomy, physiology, embryology/development, history-taking, physical examination, testing, and a review of other common causes of pediatric dizziness/vertigo.

Cross-Trait Genetic Analyses Indicate Pleiotropy and Complex Causal Relationships between Headache and Thyroid Function Traits

Epidemiological studies have reported a comorbid relationship between headache and thyroid traits; however, little is known about the shared genetics and causality that contributes to this association. We investigated the genetic overlap and associations between headache and thyroid function traits using genome-wide association study (GWAS) data. We found a significant genetic correlation (rg) with headache and hypothyroidism (rg = 0.09, p = 2.00 × 10−4), free thyroxine (fT4) (rg = 0.08, p = 5.50 × 10−3), and hyperthyroidism (rg = −0.14, p = 1.80 × 10−3), a near significant genetic correlation with secondary hypothyroidism (rg = 0.20, p = 5.24 × 10−2), but not with thyroid stimulating hormone (TSH). Pairwise-GWAS analysis revealed six, 14, four and five shared (pleiotropic) loci with headache and hypothyroidism, hyperthyroidism, secondary hypothyroidism, and fT4, respectively. Cross-trait GWAS meta-analysis identified novel genome-wide significant loci for headache: five with hypothyroidism, three with secondary hypothyroidism, 12 with TSH, and nine with fT4. Of the genes at these loci, six (FAF1, TMX2-CTNND1, AARSD1, PLCD3, ZNF652, and C20orf203; headache-TSH) and six (HMGB1P45, RPL30P1, ZNF462, TMX2-CTNND1, ITPK1, SECISBP2L; headache-fT4) were significant in our gene-based analysis (pFisher’s combined p-value < 2.09 × 10−6). Our causal analysis suggested a positive causal relationship between headache and secondary hypothyroidism (p = 3.64 × 10−4). The results also suggest a positive causal relationship between hypothyroidism and headache (p = 2.45 × 10−3) and a negative causal relationship between hyperthyroidism and headache (p = 1.16 × 10−13). These findings suggest a strong evidence base for a genetic correlation and complex causal relationships between headache and thyroid traits.

Anatomical study of the carotid-trigeminal interface: The missing link in the trigeminovascular system?

The trigeminal system is considered a prominent actor in brain nociceptive innervation. The trigeminovascular system is mainly composed of pseudounipolar neurons located within the trigeminal ganglion, whose dendrites originate in cerebral blood vessels. Anatomical studies demonstrating anatomical continuity between perivascular fibers and the trigeminal system are lacking. This issue is addressed in this study. Eleven cadaveric heads obtained from a body donation program were fixed in formalin. We performed a microanatomical study of the cavernous carotid-trigeminal interface and a histological examination of the tissue bridges crossing the virtual space between the medial aspect of the trigeminal ganglion and ophthalmic nerve and the lateral aspect of the cavernous segment of the internal carotid artery. Very strong adhesion was observed between the horizontal segment of the artery and the ophthalmic nerve in all specimens. The virtual space in this interface was crossed by a web of delicate filaments. Histological examination demonstrated the presence of nerve fibers in all samples. In this study, the carotid-trigeminal interface has been described in greater detail than ever before and could provide insight into disorders related to the trigeminovascular system. As the present results do not allow the exact nature of the axons to be affirmed, further investigation is necessary.

Modulation of Glia Activation by TRPA1 Antagonism in Preclinical Models of Migraine

Preclinical data point to the contribution of transient receptor potential ankyrin 1 (TRPA1) channels to the complex mechanisms underlying migraine pain. TRPA1 channels are expressed in primary sensory neurons, as well as in glial cells, and they can be activated/sensitized by inflammatory mediators. The aim of this study was to investigate the relationship between TRPA1 channels and glial activation in the modulation of trigeminal hyperalgesia in preclinical models of migraine based on acute and chronic nitroglycerin challenges. Rats were treated with ADM_12 (TRPA1 antagonist) and then underwent an orofacial formalin test to assess trigeminal hyperalgesia. mRNA levels of pro- and anti-inflammatory cytokines, calcitonin gene-related peptide (CGRP) and glia cell activation were evaluated in the Medulla oblongata and in the trigeminal ganglia. In the nitroglycerin-treated rats, ADM_12 showed an antihyperalgesic effect in both acute and chronic models, and it counteracted the changes in CGRP and cytokine gene expression. In the acute nitroglycerin model, ADM_12 reduced nitroglycerin-induced increase in microglial and astroglial activation in trigeminal nucleus caudalis area. In the chronic model, we detected a nitroglycerin-induced activation of satellite glial cells in the trigeminal ganglia that was inhibited by ADM_12. These findings show that TRPA1 antagonism reverts experimentally induced hyperalgesia in acute and chronic models of migraine and prevents multiple changes in inflammatory pathways by modulating glial activation.

Src Family Kinases Facilitate the Crosstalk between CGRP and Cytokines in Sensitizing Trigeminal Ganglion via Transmitting CGRP Receptor/PKA Pathway

The communication between calcitonin gene-related peptide (CGRP) and cytokines plays a prominent role in maintaining trigeminal ganglion (TG) and trigeminovascular sensitization. However, the underlying regulatory mechanism is elusive. In this study, we explored the hypothesis that Src family kinases (SFKs) activity facilitates the crosstalk between CGRP and cytokines in sensitizing TG. Mouse TG tissue culture was performed to study CGRP release by enzyme-linked immunosorbent assay, cytokine release by multiplex assay, cytokine gene expression by quantitative polymerase chain reaction, and phosphorylated SFKs level by western blot. The results demonstrated that a SFKs activator, pYEEI (YGRKKRRQRRREPQY(PO3H2)EEIPIYL) alone, did not alter CGRP release or the inflammatory cytokine interleukin-1β (IL-1β) gene expression in the mouse TG. In contrast, a SFKs inhibitor, saracatinib, restored CGRP release, the inflammatory cytokines IL-1β, C-X-C motif ligand 1, C-C motif ligand 2 (CCL2) release, and IL-1β, CCL2 gene expression when the mouse TG was pre-sensitized with hydrogen peroxide and CGRP respectively. Consistently with this, the phosphorylated SFKs level was increased by both hydrogen peroxide and CGRP in the mouse TG, which was reduced by a CGRP receptor inhibitor BIBN4096 and a protein kinase A (PKA) inhibitor PKI (14–22) Amide. The present study demonstrates that SFKs activity plays a pivotal role in facilitating the crosstalk between CGRP and cytokines by transmitting CGRP receptor/PKA signaling to potentiate TG sensitization and ultimately trigeminovascular sensitization.

Efficacy and safety of eptinezumab as preventive treatment for episodic/chronic migraine: A systematic review and meta-analysis

Migraine, the third most common neurological disorders worldwide, can cause significant burden to the patients. Currently, it has been found that calcitonin gene-related peptide (CGRP) has a significant role in pathophysiology of migraine. This study sought to analyse the efficacy and safety of eptinezumab, one of the CGRP-monoclonal antibody as preventive treatment for episodic/chronic migraine. Specific keywords were used to comprehensively go through the potential articles on ClinicalTrials.gov, Europe PMC, Scopus and PubMed databases until April 2022. All published randomized clinical trials (RCTs) on eptinezumab and migraine were gathered. Statistical analysis was conducted by using Review Manager 5.4 and Comprehensive Meta-Analysis version 3 software. There were four RCTs with 2739 migraine patients in the meta-analysis. In terms of efficacy, our analysis revealed that eptinezumab corresponded with higher reduction in monthly migraine days from baseline to week 12 (standardized mean difference, -0.34 [95% confidence interval (CI), -0.41, -0.28], P < 0.00001; I2  = 0%), higher 75% and 50% migraine responder rate, reduction in rate of migraine on day-1 after dosing, lower headache impact test-6 score on week 4 and week 12. In terms of safety, eptinezumab has comparable adverse events when compared with placebo (risk ratio, 1.01 [95% CI 0.96-1.07], P = 0.63, I2  = 0%). Further regression analysis also revealed that the association between eptinezumab and each outcomes of interest were not influenced by age, gender, body mass index and duration of migraine. This study proposes that eptinezumab is generally effective and safe for the preventive treatment of episodic or chronic migraine.

Retinal migraine, a contentious clinical entity

" Retinal migraine (ophthalmic migraine, ocular migraine, anterior visual pathway migraine) is a rarely encountered medical condition, but with an interesting and complex clinical presentation. The goal of this article is to compile the literature on retinal migraine, detailing nomenclature, pathophysiology, differential diagnosis, and medical investigations including newer imaging modalities, like optical coherence tomography (OCT). We will approach topics of great concern such as risk factors, complications, treatment, and management of this condition. Retinal migraine is mainly a diagnosis of exclusion and it must be isolated from transient monocular vision loss (TMVL) developed from other causes, for instance, papilledema, giant cell arteritis, carotid artery disease (amaurosis fugax), intermittent angle closure glaucoma, and others. Its treatment is similar to migraine treatment; topiramate, amitriptyline, and nortriptyline are some of the pharmacological drugs successfully used."

Migraine Pathophysiology Revisited: Proposal of a New Molecular Theory of Migraine Pathophysiology and Headache Diagnostic Criteria

Various explanations for the pathophysiology of migraines have been proposed; however, none of these provide a complete explanation. The author critically reviews previous theories and proposes a new molecular theory of migraine pathophysiology. The diagnosis of primary headaches is generally based on clinical histories and symptoms only because there is no reliable diagnostic examination. The author proposes a new classification system and set of diagnostic criteria for headaches based on molecular markers.

Therapeutic applications and potential mechanisms of acupuncture in migraine: A literature review and perspectives

Acupuncture is commonly used as a treatment for migraines. Animal studies have suggested that acupuncture can decrease neuropeptides, immune cells, and proinflammatory and excitatory neurotransmitters, which are associated with the pathogenesis of neuroinflammation. In addition, acupuncture participates in the development of peripheral and central sensitization through modulation of the release of neuronal-sensitization-related mediators (brain-derived neurotrophic factor, glutamate), endocannabinoid system, and serotonin system activation. Clinical studies have demonstrated that acupuncture may be a beneficial migraine treatment, particularly in decreasing pain intensity, duration, emotional comorbidity, and days of acute medication intake. However, specific clinical effectiveness has not been substantiated, and the mechanisms underlying its efficacy remain obscure. With the development of biomedical and neuroimaging techniques, the neural mechanism of acupuncture in migraine has gained increasing attention. Neuroimaging studies have indicated that acupuncture may alter the abnormal functional activity and connectivity of the descending pain modulatory system, default mode network, thalamus, frontal-parietal network, occipital-temporal network, and cerebellum. Acupuncture may reduce neuroinflammation, regulate peripheral and central sensitization, and normalize abnormal brain activity, thereby preventing pain signal transmission. To summarize the effects and neural mechanisms of acupuncture in migraine, we performed a systematic review of literature about migraine and acupuncture. We summarized the characteristics of current clinical studies, including the types of participants, study designs, and clinical outcomes. The published findings from basic neuroimaging studies support the hypothesis that acupuncture alters abnormal neuroplasticity and brain activity. The benefits of acupuncture require further investigation through basic and clinical studies.

Activation of Meningeal Afferents Relevant to Trigeminal Headache Pain after Photothrombotic Stroke Lesion: A Pilot Study in Mice

Stroke can be followed by immediate severe headaches. As headaches are initiated by the activation of trigeminal meningeal afferents, we assessed changes in the activity of meningeal afferents in mice subjected to cortical photothrombosis. Cortical photothrombosis induced ipsilateral lesions of variable sizes that were associated with contralateral sensorimotor impairment. Nociceptive firing of mechanosensitive Piezo1 channels, activated by the agonist Yoda1, was increased in meningeal afferents in the ischemic hemispheres. These meningeal afferents also had a higher maximal spike frequency at baseline and during activation of the mechanosensitive Piezo1 channel by Yoda1. Moreover, in these meningeal afferents, nociceptive firing was active during the entire induction of transient receptor potential vanilloid 1 (TRPV1) channels by capsaicin. No such activation was observed on the contralateral hemi-skulls of the same group of mice or in control mice. Our data suggest the involvement of mechanosensitive Piezo1 channels capable of maintaining high-frequency spiking activity and of nociceptive TRPV1 channels in trigeminal headache pain responses after experimental ischemic stroke in mice.

Hypoxia-related mechanisms inducing acute mountain sickness and migraine

Experimental models of human diseases are vital for pathophysiological and therapeutic research. To investigate the initiation, maintenance, pathophysiology and even termination of a migraine/headache attack these models are urgently needed. Results from different studies promote the profound involvement of hypoxia in migraine and other primary/secondary headaches. The possible mechanisms that drive the induction of headaches through hypoxia are still unknown, but several modes of action, such as increased blood flow, dilation of cerebral arteries, the release of nitroglycerin, calcitonin gene-related peptide and adenosine or increased oxygen extraction are discussed intensively. In studies exposing healthy volunteers and people with a history of migraine to controlled normobaric hypoxia, our research group could demonstrate normobaric hypoxia to be an effective trigger of migraine headaches. Furthermore, a longitudinal measurement of calcitonin gene-related peptide (CGRP), during a hypoxic challenge in migraine patients, revealed increasing CGRP levels with prolonged hypoxic challenge. Since GRP has been linked to migraine and other headache disorders, hypoxia could be regarded as initiator for headaches on a neurotransmitter basis. Furthermore, it has been known for more than 2 decades from studies in vitro and in vivo that hypoxia can induce cortical spreading depression, a phenomenon believed to represent aura. Considering the increased prevalence of migraine in altitude populations and the solid pathophysiological changes on cellular and neurotransmitter level–the role of hypoxia should be investigated in greater detail by the headache community.

Different Involvement of ASIC and TRPA1 in Facial and Hindpaw Allodynia in Nitroglycerin-Induced Peripheral Hypersensitivities in Mice

The pathophysiological mechanism underlying migraine-associated peripheral hypersensitivity remains unclear. Acid-sensing ion channels (ASICs) and transient receptor potential ankyrin 1 (TRPA1) are known to be causative pathogenic factors of mechanical and cold allodynia, respectively. Here, we sought to investigate their involvement in cold and mechanical allodynia of the face and hindpaws, respectively, in a mouse model of repetitive nitroglycerin (NTG)-induced migraine. NTG (10 mg/kg) was administered to the mice every other day for 9 days, followed 90 min later by HC-030031 (a TRPA1 blocker) or amiloride (a non-selective ASIC blocker). Mechanical or cold sensitivity of the hindpaw and facial regions was quantified using von-Frey filaments or acetone solution, respectively. Immunohistochemistry revealed that c-Fos expression was significantly increased in the trigeminal nucleus caudalis region but not in the spinal cord. Amiloride treatment only reduced NTG-induced hindpaw mechanical allodynia, whereas HC-030031 treatment only improved facial cold allodynia. Interestingly, the number of c-Fos positive cells decreased to a similar level in each drug treatment group. These findings demonstrate that facial cold allodynia and hindpaw mechanical allodynia are differentially mediated by activation of TRPA1 and ASIC, respectively, in mice with repetitive NTG-induced hypersensitivity.

Effect of Electroacupuncture at Fengchi on Facial Allodynia, Microglial Activation, and Microglia-Neuron Interaction in a Rat Model of Migraine

The purpose of the work was to investigate whether electroacupuncture (EA) could ameliorate migraine central sensitization by modulating microglial activation and the subsequent release of inflammatory cytokines in the trigeminal nucleus caudalis (TNC) in a rat model. Establishment of a rat model of recurrent migraine was achieved through repeated dural electrical stimulation (DES). After nine sessions of acupuncture treatment at Fengchi (GB20), facial mechanical thresholds were measured by electronic von Frey measurements. Microglial activation and cytokine receptors of TNC were evaluated by immunofluorescence staining. The expression of microglial biological marker Ibal-1, proinflammatory cytokines, and cytokine receptors in the TNC were evaluated by Western blot and/or real-time polymerase chain reaction. In addition, the effects of inhibition of microglial activation on facial thresholds and neuronal activation (i.e., expression of c-Fos in the TNC) induced by DES were observed. After consecutive EA-GB20 treatments, the facial withdrawal threshold was significantly higher than in the model group at different time points (p < 0.05). The hyperreactivity of microglia induced by DES was significantly inhibited, and the expressions of Ibal-1, interleukin-1β, tumor necrosis factor-α, and their receptors in the TNC were also significantly decreased (p < 0.05). Inhibition of microglia by minocycline demonstrated an acupuncture-like role, which was manifested by ameliorated mechanical hyperalgesia and decreased neuronal expression of c-Fos, Iba-1, and inflammatory factors. EA at GB20 could ameliorate migraine facial allodynia by inhibiting microglial activation and the subsequent release of inflammatory cytokines and their receptors in the TNC.

Applying a biopsychosocial model to migraine: rationale and clinical implications

Migraine is a complex condition in which genetic predisposition interacts with other biological and environmental factors determining its course. A hyperresponsive brain cortex, peripheral and central alterations in pain processing, and comorbidities play a role from an individual biological standpoint. Besides, dysfunctional psychological mechanisms, social and lifestyle factors may intervene and impact on the clinical phenotype of the disease, promote its transformation from episodic into chronic migraine and may increase migraine-related disability.Thus, given the multifactorial origin of the condition, the application of a biopsychosocial approach in the management of migraine could favor therapeutic success. While in chronic pain conditions the biopsychosocial approach is already a mainstay of treatment, in migraine the biomedical approach is still dominant. It is instead advisable to carefully consider the individual with migraine as a whole, in order to plan a tailored treatment. In this review, we first reported an analytical and critical discussion of the biological, psychological, and social factors involved in migraine. Then, we addressed the management implications of the application of a biopsychosocial model discussing how the integration between non-pharmacological management and conventional biomedical treatment may provide advantages to migraine care.

Prevalence of symptoms in 1512 COVID-19 patients: have dizziness and vertigo been underestimated thus far?

The relationship between SARS-CoV-2 infection and dizziness is still unclear. The aim of this study is to assess the prevalence and characteristics of dizziness and vertigo among patients with mild-to-moderate COVID-19. Patients discharged from the emergency rooms with a confirmed SARS-CoV-2 diagnosis were assisted by daily telephone calls until nasopharyngeal swab negativization, and specific symptoms concerning balance disorders were investigated through targeted questions posed by experienced physicians. The study included 1512 subjects (765 females, 747 males), with a median age of 51 ± 18.4 years. New-onset dizziness was reported by 251 (16.6%) patients, among whom 110 (43.8%) complained of lightheadedness, 70 (27.9%) of disequilibrium, 41 (16.3%) of presyncope, and 30 (12%) of vertigo. This study analyzed in detail the prevalence and pathophysiological mechanisms of the different types of balance disorders in a large sample, and the results suggest that dizziness should be included among the main symptoms of COVID-19 because one-sixth of patients reported this symptom, with females being significantly more affected than males (20.3 vs 12.9%, P < 0.001). Most cases of dizziness were attributable to lightheadedness, which was probably exacerbated by psychophysical stress following acute infection and mandatory quarantine. Vertigo should not be underestimated because it might underlie serious vestibular disorders, and disequilibrium in elderly individuals should be monitored due to the possible risk of falls.

Provoked versus spontaneous migraine attacks: pathophysiological similarities and differences

BACKGROUND

The onset and duration of spontaneous migraine attacks are most often difficult to predict which, in turn, makes it challenging to study the neurobiologic underpinnings of the disease in a controlled experimental setting. To address this challenge, human provocation studies can be used to identify signaling molecules (e.g. calcitonin gene-related peptide, pituitary adenylate cyclase-activating polypeptide) that, upon intravenous or oral administration, induce migraine attacks in people with migraine and mild or no headache in healthy volunteers. This approach has proven to be valid for decades and plays an integral role in mapping signaling pathways underlying migraine pathogenesis and identification of novel drug targets. However, the question arises as to whether the pathogenic mechanisms of provoked and spontaneous migraine attacks differ. In this paper, we provide an opinionated discussion on the similarities and differences between provoked and spontaneous attacks based on the current understanding of migraine pathogenesis.

METHODS

The PubMed database was searched in July 2022 for original research articles on human provocation studies that included participants with migraine. The reference lists of originally identified articles were also searched and we selected those we judged relevant.

DISCUSSION

People with migraine describe that provoked attacks resemble their spontaneous attacks and can be treated with their usual rescue medication. From a neurobiologic standpoint, provoked and spontaneous migraine attacks appear to be similar, except for the source of migraine-inducing substances (exogenous vs. endogenous source). In addition, provoked attacks can likely not be used to study the events that precede the release of migraine-inducing signaling molecules from sensory afferents and/or parasympathetic efferents during spontaneous attacks.

Cerebro-Cerebellar Networks in Migraine Symptoms and Headache

The cerebellum is associated with the biology of migraine in a variety of ways. Clinically, symptoms such as fatigue, motor weakness, vertigo, dizziness, difficulty concentrating and finding words, nausea, and visual disturbances are common in different types of migraine. The neural basis of these symptoms is complex, not completely known, and likely involve activation of both specific and shared circuits throughout the brain. Posterior circulation stroke, or neurosurgical removal of posterior fossa tumors, as well as anatomical tract tracing in animals, provided the first insights to theorize about cerebellar functions. Nowadays, with the addition of functional imaging, much progress has been done on cerebellar structure and function in health and disease, and, as a consequence, the theories refined. Accordingly, the cerebellum may be useful but not necessary for the execution of motor, sensory or cognitive tasks, but, rather, would participate as an efficiency facilitator of neurologic functions by improving speed and skill in performance of tasks produced by the cerebral area to which it is reciprocally connected. At the subcortical level, critical regions in these processes are the basal ganglia and thalamic nuclei. Altogether, a modulatory role of the cerebellum over multiple brain regions appears compelling, mainly by considering the complexity of its reciprocal connections to common neural networks involved in motor, vestibular, cognitive, affective, sensory, and autonomic processing—all functions affected at different phases and degrees across the migraine spectrum. Despite the many associations between cerebellum and migraine, it is not known whether this structure contributes to migraine initiation, symptoms generation or headache. Specific cerebellar dysfunction via genetically driven excitatory/inhibitory imbalances, oligemia and/or increased risk to white matter lesions has been proposed as a critical contributor to migraine pathogenesis. Therefore, given that neural projections and functions of many brainstem, midbrain and forebrain areas are shared between the cerebellum and migraine trigeminovascular pathways, this review will provide a synopsis on cerebellar structure and function, its role in trigeminal pain, and an updated overview of relevant clinical and preclinical literature on the potential role of cerebellar networks in migraine pathophysiology.

A Review on Headaches Due to COVID-19 Infection

Since December 2019, the time when the severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) was spotted, numerous review studies have been published on COVID-19 and its neuro invasion. A growing number of studies have reported headaches as a common neurological manifestation of COVID-19. Although several hypotheses have been proposed regarding the association between headache and the coronavirus, no solid evidence has been presented for the mechanism and features of headache in COVID-19. Headache also is a common complaint with the omicron variant of the virus. COVID-19 vaccination also is a cause of new-onset headaches or aggravation of the previous headache in migraine or tension headache sufferers. In this review study, the types of headaches reported in previous studies and their possible pathogenic mechanisms are outlined. To accomplish this objective, various types of headaches are classified and their patterns are discussed according to ICHD-3 diagnostic criteria, including, headaches attributed to systemic viral infection, viral meningitis or encephalitis, non-infectious inflammatory intracranial disease, hypoxia and/or hypercapnia, cranial or cervical vascular disorder, increased cerebrospinal fluid (CSF) pressure, refractive error, external-compression headache, and cough headache. Then, their pathogeneses are categorized into three main categories, direct trigeminal involvement, vascular invasion, and inflammatory mediators. Furthermore, persistent headache after recovery and the predictors of intensity is further investigated. Post-vaccination headache is also discussed in this review.

Migraine and peripheral pain models show differential alterations in neuronal complexity

Objective

Our laboratory has recently shown that there is a decrease in neuronal complexity in head pain processing regions in mouse models of chronic migraine‐associated pain and aura. Importantly, restoration of this neuronal complexity corresponds with anti‐migraine effects of known and experimental pharmacotherapies. The objective of the current study was to expand this work and examine other brain regions involved with pain or emotional processing. We also investigated the generalizability of our findings by analyzing neuronal cytoarchitectural changes in a model of complex regional pain syndrome (CRPS), a peripheral pain disorder.

Methods

We used the nitroglycerin (NTG) model of chronic migraine‐associated pain in which mice receive 10 mg/kg NTG every other day for 9 days. Cortical spreading depression (CSD), a physiological corelate of migraine aura, was evoked in anesthetized mice using KCl. CRPS was induced by tibial fracture followed by casting. Neuronal cytoarchitecture was visualized with Golgi stain and analyzed with Simple Neurite Tracer.

Results

In the NTG model, we previously showed decreased neuronal complexity in the trigeminal nucleus caudalis (TNC) and periaqueductal gray (PAG). In contrast, we found increased neuronal complexity in the thalamus and no change in the amygdala or caudate putamen in this study. Following CSD, we observed decreased neuronal complexity in the PAG, in line with decreases in the somatosensory cortex and TNC reported with this model previously. In the CRPS model there was decreased neuronal complexity in the hippocampus, as reported by others; increased complexity in the PAG; and no change within the somatosensory cortex.

Conclusions

Collectively these results demonstrate that alterations in neuronal complexity are a feature of both chronic migraine and chronic CRPS. However, each type of pain presents a unique cytoarchitectural signature, which may provide insight on how these pain states differentially transition from acute to chronic conditions.

Association between migraine and risk of ocular motor cranial nerve palsy

To assess association between migraines and development of ocular motor cranial nerve palsy (CNP) and finding risk factors using the National Sample Cohort database from the Korea National Health Insurance Service. Data was analyzed from 4,234,341 medical screening examinees aged 20–90 years in 2009. Cox proportional hazard regression analysis was used to the adjusted hazard ratios (HR) for ocular motor CNP according to presence of migraine. Subgroup analysis was performed to evaluate effect of other factors on association of migraine with ocular motor CNP. A total of 5806 participants (0.14% of subjects) developed ocular motor CNP and were assigned to CNP group, 4,048,018 were assigned to control group, with an average of 8.22 ± 0.93 years of follow-up. Incidence of ocular motor CNP increased in migraine group compared to control. After adjusting potential confounding variables, HR for ocular motor CNP was 1.166 (confidence interval [CI] 1.013–1.343) in migraine group. Subgroups of relatively younger age less than 65 years (HR = 1.267, 95% CI 1.067–1.504), male gender (HR = 1.228, 95% CI 1.000–1.122), smokers (HR 1.426, 95% CI 1.127–1.803), and diabetes mellitus patients (HR = 1.378, 95% CI 1.045–1.378) showed a stronger association between migraines and development of ocular motor CNP. Our population-based cohort study demonstrated a significant association between presence of migraines and incidence of ocular motor CNP. Especially, relatively younger age, males, smokers, and diabetes patients with migraines could have a higher risk of developing ocular motor CNP.

The prevalence and characteristics of visceral autonomic symptoms among migraineurs: A population-based study

BACKGROUND

There is limited evidence about visceral autonomic symptoms in the different phases of migraine attack. We evaluated the prevalence of these symptoms in migraineurs before, during, and after headache attacks. In addition, the association between migraine characteristics and visceral autonomic symptoms was investigated.

METHODS

A total of 605 participants who met the entry criteria were enrolled prospectively in this cross-sectional study. Participants were 18-60 years old and met the ICHD-3 criteria for migraine with or without aura. Information on the migraine symptoms was gathered from all participants in face-to-face interviews. A structured questionnaire was used to evaluate the related symptoms before, during, and after attacks. Migraine features of frequency, duration, and severity were also assessed.

RESULTS

Considering all phases, the most commonly present visceral symptom was nausea (52.9%). About half of participants reported at least one visceral symptom before the onset of attacks. While, during and after attacks, 71% and 36% of participants reported such characteristics, respectively. Notably, the migraine headache in participants with visceral symptoms was longer during attacks compared to participants without them (24.4 ± 29.6 vs. 16.8 ± 19.8; P = 0.008). Additionally, subjects with positive visceral symptoms experienced more severe migraine attacks than participants without symptoms for both the premonitory (8 ± 1.7 vs. 7.6 ± 1.8; P = 0.02) and during-attack (8.01 ± 1.7 vs. 7.09 ± 1.9; P = 0.001) phases.

CONCLUSION

This study demonstrated that visceral symptoms were common in migraine sufferers not only during attacks but also in the premonitory and postdrome phases. Positive visceral symptoms were also associated with more burdensome headache attacks. Therefore, recognizing the phenotypic presentation of associated symptoms of migraine, especially during the pre-attack phase, could aid in early implementation of optimal management.

Patient-reported outcomes of migraine treatment with erenumab: results from a national patient survey

BACKGROUND

Despite development of new therapies, migraine remains an undertreated illness. It is important to understand patients' preferences and perceptions of using a certain therapy. We present data from a nationwide Lithuanian survey of patients' experience using erenumab for the treatment of high frequency episodic and chronic migraine.

METHODS

An anonymous internet survey was distributed on February-March 2021 to the members of Migraine Association of Lithuania. All adult respondents who reported using at least one dose of erenumab were included in the study.

RESULTS

Out of 145 respondents, 75.2% had chronic migraine, and 31.7% had medication overuse headache. Patients received an average of 6 (IQR 4-9) erenumab doses. 93.1% respondents found erenumab effective, and 72.6% experienced improvement during the first month. MHDs were reduced by 9.8 (SD 6.0) (P < 0.001), and MMDs by 7.2 (SD 5.2) days (P < 0.001). 78.6% respondents achieved ≥ 50% reduction and 47.6% achieved ≥ 75% reduction of MMDs. 13.8% patients indicated a wearing-off effect during the treatment course, and 37.8% - some wearing-off between injections. Constipation was the most frequent adverse event (32.6%). 47.2% of patients who had a positive erenumab effect and discontinued treatment experienced migraine rebound in 6 (SD 2.0) weeks.

CONCLUSION

Erenumab is perceived as an effective and safe treatment. Further studies are needed to investigate a post-cessation deterioration of achieved improvement.

HIGHLIGHTS

• Vast majority of patients experience stable or increasing effect of erenumab. • Erenumab efficacy usually becomes evident during the first month of treatment. • Erenumab is perceived significantly better than non-specific preventive medications. • Almost 40% of patients experienced some wearing-off between injections. • Almost half of patients experience migraine rebounds after treatment cessation.

Change in the second exteroceptive suppression period of the temporalis muscle during erenumab treatment

Comparative studies on the second exteroceptive suppression period (ES2) of the masseter or temporalis muscle in migraineurs and controls have provided conflicting results. As the interneurons responsible for ES2 are probably close to the trigeminal nucleus caudalis and receive afferents also from the anti-nociceptive system, the study of ES2 could provide information on neural circuits involved in migraine pathophysiology. The aim of this observational, pilot study was to assess whether erenumab treatment may affect the exteroceptive suppression reflex of the temporalis muscle activity in migraineurs. The exteroceptive suppression reflex of the temporalis muscle activity was previously studied in a small case series of three chronic female migraineurs and after 4 months of beneficial erenumab treatment, administered according to current clinical indications. There was a statistically significant decrease in ES2 latency (p-value 0.039) and duration (p-value 0.030) after treatment. The change observed in the temporalis ES2 during erenumab treatment indicates that ES2 may play some kind of role as a neurophysiological marker and that this monoclonal antibody can modulate the brainstem circuits involved in migraine pathophysiology, at least indirectly. Further studies are required to confirm this intriguing hypothesis.

Inhibiting Endocannabinoid Hydrolysis as Emerging Analgesic Strategy Targeting a Spectrum of Ion Channels Implicated in Migraine Pain

Migraine is a disabling neurovascular disorder characterized by severe pain with still limited efficient treatments. Endocannabinoids, the endogenous painkillers, emerged, alternative to plant cannabis, as promising analgesics against migraine pain. In this thematic review, we discuss how inhibition of the main endocannabinoid-degrading enzymes, monoacylglycerol lipase (MAGL) and fatty acid amide hydrolase (FAAH), could raise the level of endocannabinoids (endoCBs) such as 2-AG and anandamide in order to alleviate migraine pain. We describe here: (i) migraine pain signaling pathways, which could serve as specific targets for antinociception; (ii) a divergent distribution of MAGL and FAAH activities in the key regions of the PNS and CNS implicated in migraine pain signaling; (iii) a complexity of anti-nociceptive effects of endoCBs mediated by cannabinoid receptors and through a direct modulation of ion channels in nociceptive neurons; and (iv) the spectrum of emerging potent MAGL and FAAH inhibitors which efficiently increase endoCBs levels. The specific distribution and homeostasis of endoCBs in the main regions of the nociceptive system and their generation ‘on demand’, along with recent availability of MAGL and FAAH inhibitors suggest new perspectives for endoCBs-mediated analgesia in migraine pain.

Risk of Burning Mouth Syndrome in Patients with Migraine: A Nationwide Cohort Study

Migraine is a common neurological disease that causes a variety of symptoms, most notably throbbing, which is described as a pulsing headache on one side of the head. Burning mouth syndrome (BMS) is defined as an intra-oral burning sensation. Currently, no medical or dental cause has been identified for BMS. Interestingly, neuropathic pain is a characteristic feature of BMS; however, it remains unclear whether migraine can cause BMS. We aimed to identify the association of migraine with the risk of developing BMS. We used a representative nationwide cohort sample of approximately 1 million patients from 2002 to 2013 to investigate the prospective association between migraine and BMS. A total of 4157 migraine patients (migraine group) and 16,628 patients without migraine (comparison group) were enrolled after 1:4 propensity score matching. The overall incidence of BMS was significantly higher in the migraine group (0.15 per 1000 person-years) than in the comparison group (0.05 per 1000 person-years). The adjusted HR for patients with migraine who reported BMS events during the 10-year follow-up period was 2.96 (95% confidence interval, 1.02-8.56), after adjusting for other covariates. However, in the subgroup analysis, the adjusted HR for BMS events did not show a significant difference between the migraine and comparison group according to sex, age, and comorbidities. This study suggests that migraine is associated with an increased incidence of BMS. Therefore, clinicians should be attentive to detect BMS at an early stage when treating patients with migraine.

Effect of Xiongmatang Extract on Behavioral and TRPV1-CGRP/CGRP-R Pathway in Rats With Migraine

Migraine is a complex neurovascular disease, which seriously affects the quality of life in patients. This study aimed to evaluate the effect of Xiongmatang (XMT) extract on rats with migraine induced by inflammatory soup and the underlying mechanisms. First, 1 week after dural catheterization, inflammatory soup was injected through a microsyringe to stimulate the dura of rats for 6 times (12 days), once every 2 days, 10 μL each time, to establish a migraine model. According to pain threshold analysis, behavioral change detection, and pathological analysis, the effects of XMT extract on rats with migraine were evaluated. The positive, mRNA and protein expression of related factors were detected by immunohistochemistry, RT-QPCR, and Western blot analysis to elucidate the underlying mechanism. XMT extract improved the behavioral performance of rats, and improve the pathological changes in the trigeminal nerve in rats. Further experimental results show that XMT extract regulated the expression of migraine-related factors in the trigeminal nerve, manifested as transient receptor potential vanilloid 1 (TRPV1), calcitonin-gene-related peptide (CGRP), calcitonin receptor-like receptor (CRLR), and receptor activity-modifying protein 1 (RAMP1) positive expression, mRNA expression, and protein expression reduction. XMT extract can significantly improved the behavioral performance of rats with migraine, and its mechanism of action might involve regulating the activity of TRPV1-CGRP/CGRP-R pathway.

Cervical musculoskeletal impairments in the 4 phases of the migraine cycle in episodic migraine patients

OBJECTIVE

To assess cervical musculoskeletal impairments during the 4 phases of a migraine cycle in episodic migraine patients, controlling for the presence of concomitant neck pain.

METHODS

Differences in cervical musculoskeletal impairments were assessed during the 4 migraine phases in episodic migraine patients and compared with healthy controls controlling for concomitant neck pain. Cervical musculoskeletal impairments were assessed as follow: cervical active range of motion; flexion rotation test; craniocervical flexion test and calculation of activation pressure score; the total number of myofascial trigger points in head/neck muscles; the number of positivevertebral segments (headache's reproduction) during passive accessory intervertebral movement; pressure pain thresholds over C1, C2, C4, C6 vertebral segments bilaterally, trigeminal area, hand, and leg. Signs of pain sensitization were assessed by evaluating mechanical pain threshold over trigeminal area and hand, pressure pain thresholds, and the wind-up ratio. The Bonferroni-corrected p-value (05/4 = 0.013) was adopted to assess the difference between groups, while a p-value of 0.05 was considered significant for the correlation analysis.

RESULTS

A total of 159 patients and 52 controls were included. Flexion rotation test and craniocervical flexion test were reduced in all 4 phases of the migraine cycle versus healthy controls (p < 0.001). The number of myofascial trigger points and positive vertebral segments was increased in all 4 phases of the migraine cycle versus healthy controls (p < 0.001). Flexion, extension, and total cervical active range of motion and cervical pressure pain thresholds were reduced in episodic migraine in the ictal phase versus controls (p < 0.007) with no other significant differences. Outside the ictal phase, the total cervical active range of motion was positively correlated with trigeminal and leg pressure pain threshold (p < 0.026), the number of active myofascial trigger points and positive positive vertebral segments were positively correlated with higher headache frequency (p=0.045), longer headache duration (p < 0.008), and with headache-related disability (p = 0.031). Cervical pressure pain thresholds were positively correlated with trigeminal, hand, and leg pressure pain threshold (p < 0.001), and trigeminal and leg mechanical pain thresholds (p < 0.005), and negatively correlated with the wind-up ratio (p < 0.004).

CONCLUSION

In all phases of the migraine cycle, independent of the presence of concomitant neck pain, episodic migraine patients showed reduced flexion rotation test and craniocervical flexion test and an increased number of myofascial trigger points and passive accessory vertebral segments. These impairments are correlated with enhanced headache duration, headache-related disability, and signs of widespread pain sensitization. Reduction in active cervical movement and increased mechanical hyperalgesia of the cervical was consistent in ictal episodic migraine patients and the subgroups of episodic migraine patients with more pronounced widespread sensitization.