Sex and the migraine brain

Potential factors contributing to observed sex differences in virtual-reality-induced sickness

Virtual reality (VR) technology has been widely adopted for several professional and recreational applications. Despite rapid innovation in hardware and software, one of the long prevailing issues for end users of VR is the experience of VR sickness. Females experience stronger VR sickness compared to males, and previous research has linked susceptibility to VR sickness to the menstrual cycle (Munafo et al., Exp Brain Res 235(3):889-901). Here we investigated the female versus male experience in VR sickness while playing an immersive VR game, comparing days of the menstrual cycle when hormones peak: day 15 (ovulation-peak estrogen) and day 22 (mid-luteal phase-peak progesterone). We found that immersion duration was greater in the second session than the first, and discomfort was lessened, suggesting a powerful adaptation with repeated exposure. Due to the estrogen levels changing along with the exposure, there was no clear independent impact of that; note, though, that there was a significant difference between self-report and physiological measures implying that GSR is potentially an unreliable measure of motion sickness. Although prior work found a delay over 2 days between session would not allow adaptation and habituation to reduce VR sickness susceptibility, we found that a week delay has potential success.

Problems in management of medication overuse headache in transgender and gender non-conforming populations

Primary headache disorders, such as migraine, account for a significant portion of disability rates worldwide, yet patients still struggle to receive the adequate medical and emotional support necessary to improve health outcomes. Insufficient pain management through either impractical pharmaceutical treatments or absent emotional support networks can worsen physical and mental health outcomes since comorbidities commonly associated with headache include hypertension, diabetes, depression, and anxiety. A lack of awareness on headache pathology and its observable severity can lead to pain-related prejudice that destroys beneficial aspects of patient self-advocacy and self-efficacy, thus potentially discouraging the use of healthcare services in favor of maladaptive coping skills. Acute treatments for primary headache disorders include non-steroidal anti-inflammatory drugs (i.e., aspirin, ibuprofen), triptans (i.e., sumatriptan), and opioids; however, continuous use of these pain-relieving agents can generate a secondary headache known as medication overuse headache (MOH). Recent work highlighting the overlap of morphological and functional brain changes in MOH and substance use disorder (SUD) suggests that insufficient pain management encourages analgesic misuse. The LGBTQ+ community-specifically transgender and gender non-conforming persons-struggles with high rates of mental illness and substance abuse. Since gender-affirming sex hormone therapy influences migraine progression, transgender and gender non-conforming (trans*) patients on hormone therapy have a higher risk for worsening migraine symptoms. However, trans* patients are less likely to have access to appropriate pain management techniques, thus preventing positive health outcomes for this vulnerable population.

The Ovary-Brain Connection

The brain and the ovaries are in a state of continuous communication [...].

Headache disorders and relevant sex and socioeconomic patterns in adolescents and young adults across 204 countries and territories: an updated global analysis

BACKGROUND

Primary headache disorders are a group of highly prevalent and disabling neurological diseases that mainly consist of migraine and tension-type headache (TTH). A previous study showed that the burden of headaches peaked at a working age that ranged from 15 to 49, particularly among females, affecting their productivity and severely damaging their social interactions.

METHODS

The latest dataset was retrieved from the Global Burden of Disease (GBD) Study 2019. Three indicators, including prevalence, incidence, and years lived with disability (YLDs), were adopted for evaluation. The overall and specific headache burdens were fully compared and analysed at global, regional, and national levels. The ratio of female YLD rates to male YLD rates due to headaches was calculated to estimate the sex pattern. Finally, we utilized the two-tailed Spearman test to explore the potential association between socioeconomic background and headaches among young people.

RESULTS

Globally, for overall headache disorders, a total of 2,049,979,883 prevalent cases (95% uncertainty interval (UI): 1,864,148,110 to 2,239,388,034), 601,229,802 incident cases (95% UI: 530,329,914 to 681,007,934), and 38,355,993 YLDs (95% UI: 7,259,286 to 83,634,503) were observed for those aged 10 to 54 in 2019. Sex differences were widely found for all headache types among adolescents and young adults, especially migraine. However, the most interesting finding was that the associations we tested between the socioeconomic environment and young headache patients were positive, regardless of region or specific country or territory.

CONCLUSIONS

Overall, the global burden of headaches in adolescents and young adults largely increased from 1990 to 2019. Although slight declines were observed in sex differences, they remained significant and challenging. The positive correlations between headache and socioeconomic background among young people were relatively inconsistent with previous investigations, and several related hypotheses were proposed for explanation. Interdisciplinary actions involving education, policy- and law-making, and basic medical practice are desperately needed to further fight against the headache burden, promote gender equality in headache care, and eliminate the stigmatization of headache patients in student and working groups.

ABHD6 and MAGL control 2-AG levels in the PAG and allodynia in a CSD-induced periorbital model of headache

Introduction

The high prevalence and severe symptoms of migraines in humans emphasizes the need to identify underlying mechanisms that can be targeted for therapeutic benefit. Clinical Endocannabinoid Deficiency (CED) posits that reduced endocannabinoid tone may contribute to migraine development and other neuropathic pain conditions. While strategies that increase levels of the endocannabinoid n-arachidonoylethanolamide have been tested, few studies have investigated targeting the levels of the more abundant endocannabinoid, 2-arachidonoylgycerol, as an effective migraine intervention.

Methods

Cortical spreading depression was induced in female Sprague Dawley rats via KCl (potassium chloride) administration, followed by measures of endocannabinoid levels, enzyme activity, and neuroinflammatory markers. Efficacy of inhibiting 2-arachidonoylglycerol hydrolysis to mitigate periorbital allodynia was then tested using reversal and prevention paradigms.

Results

We discovered reduced 2-arachidonoylglycerol levels in the periaqueductal grey associated with increased hydrolysis following headache induction. Pharmacological inhibition of the 2-arachidonoylglycerol hydrolyzing enzymes, α/β-hydrolase domain-containing 6 and monoacylglycerol lipase reversed and prevented induced periorbital allodynia in a cannabinoid receptor-dependent manner.

Discussion

Our study unravels a mechanistic link between 2-arachidonoylglycerol hydrolysis activity in the periaqueductal grey in a preclinical, rat model of migraine. Thus, 2-arachidonoylglycerol hydrolysis inhibitors represent a potential new therapeutic avenue for the treatment of headache.

Glia Signaling and Brain Microenvironment in Migraine

Migraine is a complicated neurological disorder affecting 6% of men and 18% of women worldwide. Various mechanisms, including neuroinflammation, oxidative stress, altered mitochondrial function, neurotransmitter disturbances, cortical hyperexcitability, genetic factors, and endocrine system problems, are responsible for migraine. However, these mechanisms have not completely delineated the pathophysiology behind migraine, and they should be further studied. The brain microenvironment comprises neurons, glial cells, and vascular structures with complex interactions. Disruption of the brain microenvironment is the main culprit behind various neurological disorders. Neuron-glia crosstalk contributes to hyperalgesia in migraine. In the brain, microenvironment and related peripheral regulatory circuits, microglia, astrocytes, and satellite cells are necessary for proper function. These are the most important cells that could induce migraine headaches by disturbing the balance of the neurotransmitters in the nervous system. Neuroinflammation and oxidative stress are the prominent reactions glial cells drive during migraine. Understanding the role of cellular and molecular components of the brain microenvironment on the major neurotransmitters engaged in migraine pathophysiology facilitates the development of new therapeutic approaches with higher effectiveness for migraine headaches. Investigating the role of the brain microenvironment and neuroinflammation in migraine may help decipher its pathophysiology and provide an opportunity to develop novel therapeutic approaches for its management. This review aims to discuss the neuron-glia interactions in the brain microenvironment during migraine and their potential role as a therapeutic target for the treatment of migraine.

Prolactin and oxytocin: potential targets for migraine treatment

Migraine is a severe neurovascular disorder of which the pathophysiology is not yet fully understood. Besides the role of inflammatory mediators that interact with the trigeminovascular system, cyclic fluctuations in sex steroid hormones are involved in the sex dimorphism of migraine attacks. In addition, the pituitary-derived hormone prolactin and the hypothalamic neuropeptide oxytocin have been reported to play a modulating role in migraine and contribute to its sex-dependent differences. The current narrative review explores the relationship between these two hormones and the pathophysiology of migraine. We describe the physiological role of prolactin and oxytocin, its relationship to migraine and pain, and potential therapies targeting these hormones or their receptors.In summary, oxytocin and prolactin are involved in nociception in opposite ways. Both operate at peripheral and central levels, however, prolactin has a pronociceptive effect, while oxytocin appears to have an antinociceptive effect. Therefore, migraine treatment targeting prolactin should aim to block its effects using prolactin receptor antagonists or monoclonal antibodies specifically acting at migraine-pain related structures. This action should be local in order to avoid a decrease in prolactin levels throughout the body and associated adverse effects. In contrast, treatment targeting oxytocin should enhance its signalling and antinociceptive effects, for example using intranasal administration of oxytocin, or possibly other oxytocin receptor agonists. Interestingly, the prolactin receptor and oxytocin receptor are co-localized with estrogen receptors as well as calcitonin gene-related peptide and its receptor, providing a positive perspective on the possibilities for an adequate pharmacological treatment of these nociceptive pathways. Nevertheless, many questions remain to be answered. More particularly, there is insufficient data on the role of sex hormones in men and the correct dosing according to sex differences, hormonal changes and comorbidities. The above remains a major challenge for future development.

A study of differential microRNA expression profile in migraine: the microMIG exploratory study

BACKGROUND

Several studies have described potential microRNA (miRNA) biomarkers associated with migraine, but studies are scarcely reproducible primarily due to the heterogeneous variability of participants. Increasing evidence shows that disease-related intrinsic factors together with lifestyle (environmental factors), influence epigenetic mechanisms and in turn, diseases. Hence, the main objective of this exploratory study was to find differentially expressed miRNAs (DE miRNA) in peripheral blood mononuclear cells (PBMC) of patients with migraine compared to healthy controls in a well-controlled homogeneous cohort of non-menopausal women.

METHODS

Patients diagnosed with migraine according to the International Classification of Headache Disorders (ICHD-3) and healthy controls without familial history of headache disorders were recruited. All participants completed a very thorough questionnaire and structured-interview in order to control for environmental factors. RNA was extracted from PBMC and a microarray system (GeneChip miRNA 4.1 Array chip, Affymetrix) was used to determine the miRNA profiles between study groups. Principal components analysis and hierarchical clustering analysis were performed to study samples distribution and random forest (RF) algorithms were computed for the classification task. To evaluate the stability of the results and the prediction error rate, a bootstrap (.632 + rule) was run through all the procedure. Finally, a functional enrichment analysis of selected targets was computed through protein-protein interaction networks.

RESULTS

After RF classification, three DE miRNA distinguished study groups in a very homogeneous female cohort, controlled by factors such as demographics (age and BMI), life-habits (physical activity, caffeine and alcohol consumptions), comorbidities and clinical features associated to the disease: miR-342-3p, miR-532-3p and miR-758-5p. Sixty-eight target genes were predicted which were linked mainly to enriched ion channels and signaling pathways, neurotransmitter and hormone homeostasis, infectious diseases and circadian entrainment.

CONCLUSIONS

A 3-miRNA (miR-342-3p, miR-532-3p and miR-758-5p) novel signature has been found differentially expressed between controls and patients with migraine. Enrichment analysis showed that these pathways are closely associated with known migraine pathophysiology, which could lead to the first reliable epigenetic biomarker set. Further studies should be performed to validate these findings in a larger and more heterogeneous sample.

Migraine in childhood: Gender differences

Migraine is a common neurological disorder in developmental age, involving up to 20% of children and adolescents. Although gender differences in migraine epidemiology and clinical characteristics have been largely investigated in adulthood, this issue is considerably less known in pediatric patients. We aim at providing an overview of gender differences in pediatric migraine. The most recent literature was reviewed taking into account the epidemiological, pathophysiological, and clinical differences between boys and girls with migraine. Although many aspects need to undergo further investigation, we conclude that different aspects of childhood migraine syndrome may vary depending on the gender and age, especially with regard to pubertal development.

New onset headache during delivery and postpartum: Clinical characteristics of a case series

Introduction

There are abundant studies on headache and migraine in women but few or none about their occurrence during labor, delivery, and postpartum (2 hours after delivery) owing to the low incidence. A headache attack can be debilitating when a woman is trying to manage labor pain. Research at our Women's Headache Center within the Department of Gynecology and Obstetrics has begun to shed light on this potential association.

Methods

For the present study 474 women with singleton pregnancy were enrolled. A headache questionnaire was administered at two time points. Headache history was investigated on admission to prenatal care at 36 weeks gestation. The women were followed by a midwife who monitored labor progression and recorded the onset and features of headache pain. During examination before hospital discharge at 3 days post-delivery, the headache questionnaire was reviewed by a headache specialist who differentiated headache type according to International Classification of Headache Disorders (3rd edition) criteria.

Results

Data analysis showed that 145/474 women had a history of headache: 65/145 (44.82%) reported a diagnosis of migraine. Eight reported experiencing a probable migraine attack (4 with aura) and one reported probable tension-type headache during labor or postpartum. All nine women who reported migraine/headache attack during labor had no previous history of headache or neurological illness. All had vaginal delivery. No onset of headache pain in patients with a previous history of headache was noted during delivery and postpartum.

Discussion

The onset of a headache attack during labor in women who usually do not experience headache suggests other pathogenic mechanisms underlying the attack and merits further study.

Assessment of Parenting Attitudes by Children and Adolescents with Migraine

Purpose: We aimed to investigate the parenting attitudes reported by patients and their relationships with the characteristics of headaches in children and adolescents with migraine. Methods: We conducted a retrospective review of medical records of children and adolescents with migrainous headaches (n=115; 59.1% female; mean age, 11.89±2.00 years). Children evaluated parental attitudes using the Parenting Attitude Test-Youth (PAT-Y), which comprises eight subscales and four newly devised secondary subscales. Headache severity was calculated by the visual analog scale (VAS), monthly frequency (MF), and VAS×MF/4 (VF). The scores of PAT-Y subscales and the correlations between PAT-Y scores and headache severity were analyzed by age group and sex. Scores for children’s depression inventory, childhood behavior checklists, and an attention deficit hyperactivity disorder scale were also analyzed. Results: In the elementary school age group, VAS was weakly negatively correlated with the “achievement press” (r=–0.28, P<0.05) and “high expectation” (r=–0.25, P<0.05) attitudes, and VF was weakly negatively correlated with “achievement press” (r=–0.32, P<0.05), “punishment” (r=–0.27, P<0.05), and “high expectation” (r=–0.29, P<0.05). In the middle-school age group, MF and VF were moderately positively correlated with the “achievement press” attitude (r=0.48, P<0.01 and r=0.48, P<0.01, respectively), VF was weakly positively correlated with the “neglectful” attitude(r=0.31, P<0.05), and MF was weakly positively correlated with scores for depression (r=0.29, P<0.05) and internalized problems (r=0.31, P<0.05). Conclusion: Parenting attitudes perceived by children and adolescents with migrainous headaches varied by age, and some parenting attitudes were related to headache severity. Education on age-appropriate parenting attitudes may help cope with migrainous headaches.

Migraine: interactions between brain's trait and state

It is well established that migraine is a multifactorial disorder. A deep understanding of migraine should be based upon both the underlying traits and the current states affected by different physiological, psychological, and environmental factors. At this point, there is no framework fully meeting these criteria. Here, we describe a broader view of the migraine disorder defined as a dysfunctional brain state and trait interaction. In this model, we consider events that may enhance or diminish migraine responsivity based on an individual's trait and state. This could provide an expanded view for considering how migraine attacks are sometimes precipitated by "triggers" and sometimes not, how these factors only lead to migraine attacks in migraine patients, or how individuals with an increased risk for migraine do not show any symptoms at all. Summarizing recent studies and evidence that support the concept of migraine as a brain state-trait interaction can also contribute to improving patient care by highlighting the importance of precision medicine and applying measures that are able to capture how different traits and states work together to determine migraine.

Sex and Gender Considerations in Episodic Migraine

Purpose of Review

We seek to update readers on recent advances in our understanding of sex and gender in episodic migraine with a two part series. In part 1, we examine migraine epidemiology in the context of sex and gender, differences in symptomatology, and the influence of sex hormones on migraine pathophysiology (including CGRP). In part 2, we focus on practical clinical considerations for sex and gender in episodic migraine by addressing menstrual migraine and the controversial topic of hormone-containing therapies. We make note of data applicable to gender minority populations, when available, and summarize knowledge on gender affirming hormone therapy and migraine management in transgender individuals. Finally, we briefly address health disparities, socioeconomic considerations, and research bias.

Recent Findings

Migraine is known to be more prevalent, frequent, and disabling in women. There are also differences in migraine co-morbidities and symptomatology. For instance, women are likely to experience more migraine associated symptoms such as nausea, photophobia, and phonophobia. Migraine pathophysiology is influenced by sex hormones, e.g., estrogen withdrawal as a known trigger for migraine. Other hormones such as progesterone and testosterone are less well studied. Relationships between CGRP (the target of new acute and preventive migraine treatments) and sex hormones have been established with both animal and human model studies. The natural course of migraine throughout the lifetime suggests a contribution from hormonal changes, from puberty to pregnancy to menopause/post-menopause. Treatment of menstrual migraine and the use of hormone-containing therapies remains controversial. Re-evaluation of the data reveals that stroke risk is an estrogen dose- and aura frequency-dependent phenomenon. There are limited data on episodic migraine in gender minorities. Gender affirming hormone therapy may be associated with a change in migraine and unique risks (including ischemic stroke with high dose estrogen).

Summary

There are key differences in migraine epidemiology and symptomatology, thought to be driven at least in part by sex hormones which influence migraine pathophysiology and the natural course of migraine throughout the lifetime. More effective and specific treatments for menstrual migraine are needed. A careful examination of the data on estrogen and stroke risk suggests a nuanced approach to the issue of estrogen-containing contraception and hormone replacement therapy is warranted. Our understanding of sex and gender is evolving, with limited but growing research on the relationship between gender affirming therapy and migraine, and treatment considerations for transgender people with migraine.

Role of Estrogens in Menstrual Migraine

Migraine is a major neurological disorder affecting one in nine adults worldwide with a significant impact on health care and socioeconomic systems. Migraine is more prevalent in women than in men, with 17% of all women meeting the diagnostic criteria for migraine. In women, the frequency of migraine attacks shows variations over the menstrual cycle and pregnancy, and the use of combined hormonal contraception (CHC) or hormone replacement therapy (HRT) can unveil or modify migraine disease. In the general population, 18–25% of female migraineurs display a menstrual association of their headache. Here we present an overview on the evidence supporting the role of reproductive hormones, in particular estrogens, in the pathophysiology of migraine. We also analyze the efficacy and safety of prescribing exogenous estrogens as a potential treatment for menstrual-related migraine. Finally, we point to controversial issues and future research areas in the field of reproductive hormones and migraine.

Dysregulation of serum prolactin links the hypothalamus with female nociceptors to promote migraine

Migraine headache results from activation of meningeal nociceptors, however, the hypothalamus is activated many hours before the emergence of pain. How hypothalamic neural mechanisms may influence trigeminal nociceptor function remains unknown. Stress is a common migraine trigger that engages hypothalamic dynorphin/kappa opioid receptor (KOR) signalling and increases circulating prolactin. Prolactin acts at both long and short prolactin receptor isoforms that are expressed in trigeminal afferents. Following downregulation of the prolactin receptor long isoform, prolactin signalling at the prolactin receptor short isoform sensitizes nociceptors selectively in females. We hypothesized that stress may activate the kappa opioid receptor on tuberoinfundibular dopaminergic neurons to increase circulating prolactin leading to female-selective sensitization of trigeminal nociceptors through dysregulation of prolactin receptor isoforms. A mouse two-hit hyperalgesic priming model of migraine was used. Repeated restraint stress promoted vulnerability (i.e. first-hit priming) to a subsequent subthreshold (i.e. second-hit) stimulus from inhalational umbellulone, a TRPA1 agonist. Periorbital cutaneous allodynia served as a surrogate of migraine-like pain. Female and male KORCre; R26lsl-Sun1-GFP mice showed a high percentage of KORCre labelled neurons co-localized in tyrosine hydroxylase-positive cells in the hypothalamic arcuate nucleus. Restraint stress increased circulating prolactin to a greater degree in females. Stress-primed, but not control, mice of both sexes developed periorbital allodynia following inhalational umbellulone. Gi-DREADD activation (i.e. inhibition through Gi-coupled signalling) in KORCre neurons in the arcuate nucleus also increased circulating prolactin and repeated chemogenetic manipulation of these neurons primed mice of both sexes to umbellulone. Clustered regularly interspaced short palindromic repeats-Cas9 deletion of the arcuate nucleus KOR prevented restraint stress-induced prolactin release in female mice and priming from repeated stress episodes in both sexes. Inhibition of circulating prolactin occurred with systemic cabergoline, a dopamine D2 receptor agonist, blocked priming selectively in females. Repeated restraint stress downregulated the prolactin receptor long isoform in the trigeminal ganglia of female mice. Deletion of prolactin receptor in trigeminal ganglia by nasal clustered regularly interspaced short palindromic repeats-Cas9 targeting both prolactin receptor isoforms prevented stress-induced priming in female mice. Stress-induced activation of hypothalamic KOR increases circulating prolactin resulting in trigeminal downregulation of prolactin receptor long and pain responses to a normally innocuous TRPA1 stimulus. These are the first data that provide a mechanistic link between stress-induced hypothalamic activation and the trigeminal nociceptor effectors that produce trigeminal sensitization and migraine-like pain. This sexually dimorphic mechanism may help to explain female prevalence of migraine. KOR antagonists, currently in phase II clinical trials, may be useful as migraine preventives in both sexes, while dopamine agonists and prolactin/ prolactin receptor antibodies may improve therapy for migraine, and other stress-related neurological disorders, in females.

Sex Differences of Periaqueductal Grey Matter Functional Connectivity in Migraine

The existence of “sex phenotype” in migraine is a long-standing scientific question. Fluctuations of female sex hormones contribute to migraine attacks, and women also have enhanced brain activity during emotional processing and their functional brain networks seem to be more vulnerable to migraine-induced disruption compared to men. Periaqueductal grey matter (PAG) is a core region of pain processing and modulation networks with possible sex-related implications in migraine. In our study, sex differences of PAG functional resting-state connectivity were investigated in the interictal state in 32 episodic migraines without aura patients (16 women and 16 men). A significant main effect of sex was detected in PAG connectivity with postcentral, precentral, and inferior parietal gyri, and further differences were found between right PAG and visual areas (superior occipital gyrus, calcarine, and cuneus), supplementary motor area, and mid-cingulum connectivity. In all cases, PAG functional connectivity was stronger in female migraineurs compared to males. However, higher average pain intensity of migraine attacks correlated with stronger connectivity of PAG and middle temporal, superior occipital, and parietal gyri in male migraineurs compared to females. Migraine-related disability is also associated with PAG connectivity but without sex differences. Our results indicate that sex differences in PAG connectivity with brain regions involved in sensory and emotional aspects of pain might contribute to the “sex-phenotype” in migraine. The stronger functional connectivity between PAG and pain processing areas may be a sign of increased excitability of pain pathways even in resting-state in females compared to male migraineurs, which could contribute to female vulnerability for migraine. However, pain intensity experienced by male migraineurs correlated with increased connectivity between PAG and regions involved in the subjective experience of pain and pain-related unpleasantness. The demonstrated sex differences of PAG functional connectivity may support the notion that the female and male brain is differently affected by migraine.

Genome-wide analysis of 102,084 migraine cases identifies 123 risk loci and subtype-specific risk alleles

Migraine affects over a billion individuals worldwide but its genetic underpinning remains largely unknown. Here, we performed a genome-wide association study of 102,084 migraine cases and 771,257 controls and identified 123 loci, of which 86 are previously unknown. These loci provide an opportunity to evaluate shared and distinct genetic components in the two main migraine subtypes: migraine with aura and migraine without aura. Stratification of the risk loci using 29,679 cases with subtype information indicated three risk variants that seem specific for migraine with aura (in HMOX2, CACNA1A and MPPED2), two that seem specific for migraine without aura (near SPINK2 and near FECH) and nine that increase susceptibility for migraine regardless of subtype. The new risk loci include genes encoding recent migraine-specific drug targets, namely calcitonin gene-related peptide (CALCA/CALCB) and serotonin 1F receptor (HTR1F). Overall, genomic annotations among migraine-associated variants were enriched in both vascular and central nervous system tissue/cell types, supporting unequivocally that neurovascular mechanisms underlie migraine pathophysiology.

Gender Differences in 3-Month Outcomes of Erenumab Treatment-Study on Efficacy and Safety of Treatment With Erenumab in Men

Objective: We reported gender-specific data on the efficacy and safety of erenumab, a monoclonal antibody antagonizing the calcitonin gene-related peptide (CGRP) receptor.

Methods: Our pooled patient-level analysis of real-world data included patients treated with erenumab and followed up for 12 weeks. We considered the following outcomes at weeks 9–12 of treatment compared with baseline: 0–29%, 30–49%, 50–75%, and ≥75% responder rates, according to the decrease in monthly headache days (MHDs), rate of treatment stopping, change in MHDs, monthly migraine days (MMDs), monthly days of acute medication and triptan use, and Headache Impact Test-6 (HIT-6) score from baseline to weeks 9–12. Outcomes were compared between men and women by the chi-squared test or t-test, as appropriate. An analysis of covariance (ANCOVA) was performed to identify factors influencing the efficacy outcomes.

Results: We included 1,410 patients from 16 centers, of which 256 (18.2%) were men. Men were older than women and had a lower number of MHDs at baseline. At weeks 9–12, compared with baseline, 46 (18.0%) men had a ≥75% response, 75 (29.3%) had a 50–74% response, 35 (13.7%) had a 30–49% response, and 86 (33.6%) had a 0–29% response, while 14 (5.5%) stopped the treatment. The corresponding numbers for women were 220 (19.1%), 314 (27.2%), 139 (12.0%), 402 (34.8%), and 79 (6.8%). No gender difference was found in any of the outcomes. The ANCOVA showed that gender did not influence the efficacy of outcomes.

Conclusion: We found that erenumab is equally safe and effective in men compared with women after 12 weeks.

Prolactin signaling modulates stress-induced behavioral responses in a preclinical mouse model of migraine

OBJECTIVE

The aim of this study was to determine if prolactin signaling modulates stress-induced behavioral responses in a preclinical migraine model.

BACKGROUND

Migraine is one of the most complex and prevalent disorders. The involvement of sex-selective hormones in migraine pathology is highly likely as migraine is more common in women and its frequency correlates with reproductive stages. Prolactin has been shown to be a worsening factor for migraine. Normally prolactin levels are low; however levels can surge during stress. Dopamine receptor agonists, which suppress pituitary prolactin release, are an effective migraine treatment in a subset of patients. Previously, we showed that administration of prolactin onto the dura mater induces female-specific behavioral responses, suggesting that prolactin may play a sex-specific role in migraine.

METHODS

The effects of prolactin signaling were assessed using a preclinical migraine model we published recently in which behavioral sensitization is induced by repeated stress. Plasma prolactin levels were assessed in naïve and stressed CD-1 mice (n = 3-5/group) and transgenic mice with conditional deletion of the Prlr in Nav1.8-positive sensory neurons (Prlr conditional knock-out [CKO]; n = 3/group). To assess the contribution of prolactin release during stress, naïve or stressed male and female CD-1 mice were treated with the prolactin release inhibitor bromocriptine (2 mg/kg; n = 7-12/group) or vehicle for 5 days (8-12/group) and tested for facial hypersensitivity following stress. Additionally, the contribution of ovarian hormones in regulating the prolactin-induced responses was assessed in ovariectomized female CD-1 mice (n = 6-10/group). Furthermore, the contribution of Prlr activation on Nav1.8-positive sensory neurons was assessed. Naïve or stressed male and female Prlr CKO mice and their control littermates were tested for facial hypersensitivity (n = 8-9/group). Immunohistochemistry was used to confirm loss of Prlr in Nav1.8-positive neurons in Prlr CKO mice. The total sample size is n = 245; the full analysis sample size is n = 221.

RESULTS

Stress significantly increased prolactin levels in vehicle-treated female mice (39.70 ± 2.77; p < 0.0001). Bromocriptine significantly reduced serum prolactin levels in stressed female mice compared to vehicle-treated mice (-44.85 ± 3.1; p < 0.0001). Additionally, no difference was detected between female stressed mice that received bromocriptine compared to naïve mice treated with bromocriptine (-0.70 ± 2.9; p = 0.995). Stress also significantly increased serum prolactin levels in male mice, although to a much smaller extent than in females (0.61 ± 0.08; p < 0.001). Bromocriptine significantly reduced serum prolactin levels in stressed males compared to those treated with vehicle (-0.49 ± 0.08; p = 0.002). Furthermore, bromocriptine attenuated stress-induced behavioral responses in female mice compared to those treated with vehicle (maximum effect observed on day 4 post stress [0.21 ± 0.08; p = 0.03]). Bromocriptine did not attenuate stress-induced behavior in males at any timepoint compared to those treated with vehicle. Moreover, loss of ovarian hormones did not affect the ability of bromocriptine to attenuate stress responses compared to vehicle-treated ovariectomy mice that were stressed (maximum effect observed on day 4 post stress [0.29 ± 0.078; p = 0.013]). Similar to CD-1 mice, stress increased serum prolactin levels in both Prlr CKO female mice (27.74 ± 9.96; p = 0.047) and control littermates (28.68 ± 9.9; p = 0.041) compared to their naïve counterparts. There was no significant increase in serum prolactin levels detected in male Prlr CKO mice or control littermates. Finally, conditional deletion of Prlr from Nav1.8-positive sensory neurons led to a female-specific attenuation of stress-induced behavioral responses (maximum effect observed on day 7 post stress [0.32 ± 0.08; p = 0.007]) compared to control littermates.

CONCLUSION

These data demonstrate that prolactin plays a female-specific role in stress-induced behavioral responses in this preclinical migraine model through activation of Prlr on sensory neurons. They also support a role for prolactin in migraine mechanisms in females and suggest that modulation of prolactin signaling may be an effective therapeutic strategy in some cases.

Is There a Gender Difference in the Response to onabotulinumtoxinA in Chronic Migraine? Insights from a Real-Life European Multicenter Study on 2879 Patients

INTRODUCTION

Migraine is mostly a female disorder because of its lower prevalence in men. Less than 20% of patients included in the available studies on migraine treatments are men; hence, the evidence on migraine treatments might not apply to men. The aims of the present study were to provide reliable information on the effectiveness of onabotulinumtoxinA (BT-A) for chronic migraine in men and to compare clinical benefits between men and women.

METHODS

We performed a pooled patient-level gender-specific analysis of real-life data on BT-A for chronic migraine of patients followed-up to 9 months. We reported the 50% responder rates during each BT-A cycle, defined as percentage of reduction in monthly headache days (MHDs) compared to baseline, along with 75% and 30% responder rates. We also reported the mean decrease in MHDs and in days of acute medication use (DAMs) during each BT-A cycle as compared to baseline. We also evaluated the reasons for stopping the treatment within the third cycle.

RESULTS

We included an overall cohort of 2879 patients, 522 of whom (18.1%) were men. In men, 50% responder rates were 27.7% during the first BT-A cycle, 29.2% during the second, and 35.6% during the third cycle; in women, the corresponding rates were 26.6%, 33.5%, and 41.0%. In the overall cohort, responder rates did not differ between men and women during the first two cycles; during the third cycle, the distribution was different (P < 0.001) mostly because of higher rates of treatment stopping and non-responders in men. In the propensity score matched cohort, the trend was maintained but lost its statistical significance. Both men and women had a significant decrease in MHDs and in DAMs with BT-A treatment (P < 0.001). There were no gender differences in those changes with the only exception of MHD decrease which, during the third cycle, was lower in men than in women (7.4 vs 8.2 days, P = 0.016 in the overall cohort and 9.1 vs 12.5 days, P = 0.009 in the propensity score matched cohort). At the end of follow-up, 152 men and 485 women stopped BT-A treatment (29.1% vs 20.6%; P < 0.001). The relative proportion of patients stopping treatment because of inadequate response (less than 30% decrease in MHDs from baseline) was higher in men than in women (42.8% vs 39.6%), while the proportion of patients stopping because of adverse events was higher in women than in men (5.6% vs 0%; P = 0.031).

CONCLUSIONS

Our pooled analysis suggests that the response to BT-A is significant in both men and women with a small gender difference in favor of women. Men tended to stop the treatment more frequently than women. We emphasize the need for more gender-specific data on migraine treatments from randomized controlled trials and observational studies.

Cluster headache epidemiology including pediatric onset, sex, and ICHD criteria: Results from the International Cluster Headache Questionnaire

OBJECTIVE

To validate the diagnoses and to investigate epidemiological data from an international, non-clinic-based, and large (n = 1604) survey of participants with cluster headache.

BACKGROUND

There are several limitations in current epidemiological data in cluster headache including a lack of large non-clinic-based studies. There is also limited information on several aspects of cluster headache, such as pediatric incidence.

METHODS

The International Cluster Headache Questionnaire was an internet-based survey that included questions on cluster headache demographics, criteria from the International Classification of Headache Disorders (ICHD), and medications.

RESULTS

A total of 3251 subjects participated in the survey, and 1604 respondents met ICHD criteria for cluster headache. For validation, we interviewed a random sample of 5% (81/1604) of participants and confirmed the diagnosis of cluster headache in 97.5% (79/81). Pediatric onset was found in 27.5% (341/1583) of participants, and only 15.2% (52/341) of participants with pediatric onset were diagnosed before the age of 18. Men were more likely to have episodic cluster headache between ages 10 and 50, but the sex ratio was approximately equal for other ages. An overwhelming majority of respondents had at least one autonomic feature (99.0%, 1588/1604) and had restlessness (96.6%, 1550/1604), but many also had prototypical migrainous features including photophobia or phonophobia (50.1%, 804/1604), pain aggravated by physical activity (31.4%, 503/1604), or nausea and vomiting (27.5%, 441/1604). Interestingly, the first-line medications for acute treatment (oxygen) and preventive treatment (calcium channel blockers) were perceived as significantly less effective in chronic cluster headache (3.2 ± 1.1 and 2.1 ± 1.0 respectively on a 5-point ordinal scale) compared with episodic cluster headache (3.5 ± 1.0 and 2.4 ± 1.1, respectively, p < 0.001 for both comparisons).

CONCLUSIONS

Cluster headache often occurs in the pediatric population, although they are typically not diagnosed until adulthood. The onset of cluster headache is the inverse of that in migraine; in migraine women are more likely to have migraine between ages 10 and 50 but the sex ratio is approximately equal otherwise. Prototypical migrainous features are not useful in differentiating cluster headache from migraine. Participant data from a large international study also suggest that chronic cluster headache is not only less responsive to newer treatments (like noninvasive vagus nerve stimulation and galcanezumab), but to traditional first-line treatments as well.

Sex differences in the expression of the endocannabinoid system within V1M cortex and PAG of Sprague Dawley rats

BACKGROUND

Several chronic pain disorders, such as migraine and fibromyalgia, have an increased prevalence in the female population. The underlying mechanisms of this sex-biased prevalence have yet to be thoroughly documented, but could be related to endogenous differences in neuromodulators in pain networks, including the endocannabinoid system. The cellular endocannabinoid system comprises the endogenous lipid signals 2-AG (2-arachidonoylglycerol) and AEA (anandamide); the enzymes that synthesize and degrade them; and the cannabinoid receptors. The relative prevalence of different components of the endocannabinoid system in specific brain regions may alter responses to endogenous and exogenous ligands.

METHODS

Brain tissue from naïve male and estrous staged female Sprague Dawley rats was harvested from V1M cortex, periaqueductal gray, trigeminal nerve, and trigeminal nucleus caudalis. Tissue was analyzed for relative levels of endocannabinoid enzymes, ligands, and receptors via mass spectrometry, unlabeled quantitative proteomic analysis, and immunohistochemistry.

RESULTS

Mass spectrometry revealed significant differences in 2-AG and AEA concentrations between males and females, as well as between female estrous cycle stages. Specifically, 2-AG concentration was lower within female PAG as compared to male PAG (*p = 0.0077); female 2-AG concentration within the PAG did not demonstrate estrous stage dependence. Immunohistochemistry followed by proteomics confirmed the prevalence of 2-AG-endocannabinoid system enzymes in the female PAG.

CONCLUSIONS

Our results suggest that sex differences exist in the endocannabinoid system in two CNS regions relevant to cortical spreading depression (V1M cortex) and descending modulatory networks in pain/anxiety (PAG). These basal differences in endogenous endocannabinoid mechanisms may facilitate the development of chronic pain conditions and may also underlie sex differences in response to therapeutic intervention.

Hormonal therapies in migraine management: current perspectives on patient selection and risk management

INTRODUCTION

The link between sex hormones and migraines has long been investigated but the mechanisms underlying this altered interaction are not yet fully understood. Herein, we retrace the knowledge on this association in relationship with risk of stroke.

AREAS COVERED

Estrogens fluctuations could trigger migraine attacks and exogenous estrogens intake could be a risk factor for venous thromboembolism (VTE) and stroke. At the same time, ischemic heart diseases and stroke share a common substrate with migraine and other mood disorders, depression, and anxiety.

EXPERT OPINION

The use of hormonal therapies in the context of contraception or replacement therapy must be closely evaluated in a careful risk assessment. We highlight the complex interaction of hormone/neuroinflammation pathways underlying the pathophysiology of migraine glimpsing in mood disorders a possible common denominator of link between hormonal and neuronal systems.

A link between migraine and prolactin: the way forward

Migraine is an incapacitating neurological disorder that predominantly affects women. Sex and other hormones (e.g., oxytocin, and prolactin) may play a role in sexual dimorphic features of migraine. Initially, prolactin was recognized for its modulatory action in milk production and secretion; later, its roles in the regulation of the endocrine, immune and nervous systems were discovered. Higher prolactin levels in individuals with migraine were found in earlier studies, with a female sex-dominant trend. Studies that are more recent have identified that the expression of prolactin receptor in response to neuronal excitability and stress depends on sex with a dominant role in females. These findings have opened up potentials for explanation of sex-related pathophysiology of migraine, but have left some unanswered questions. This focused review examines the past and present of the link between prolactin and migraine, and presents open questions and directions for future experimental and clinical efforts.

Sex hormones (e.g., estrogen and progesterone) have been investigated to explain the sex-related manifestation of migraine, which is predominant in females. Prolactin is known for promoting lactation, but accumulating evidence supports that it can promote pain in females. An increasing number of studies have shown that the expression of a prolactin receptor in female nociceptors and their responses to external stimuli such as stress are different, which can help explain the female sex-dominant feature of migraine. In this focused review, the current knowledge is presented and the directions where prolactin research in migraine may evolve are proposed. The ultimate goal is to shape an overview toward considering sex-based treatments for migraine with highlighting the role of prolactin.

Hormonal influences in migraine - interactions of oestrogen, oxytocin and CGRP

Migraine is ranked as the second highest cause of disability worldwide and the first among women aged 15-49 years. Overall, the incidence of migraine is threefold higher among women than men, though the frequency and severity of attacks varies during puberty, the menstrual cycle, pregnancy, the postpartum period and menopause. Reproductive hormones are clearly a key influence in the susceptibility of women to migraine. A fall in plasma oestrogen levels can trigger attacks of migraine without aura, whereas higher oestrogen levels seem to be protective. The basis of these effects is unknown. In this Review, we discuss what is known about sex hormones and their receptors in migraine-related areas in the CNS and the peripheral trigeminovascular pathway. We consider the actions of oestrogen via its multiple receptor subtypes and the involvement of oxytocin, which has been shown to prevent migraine attacks. We also discuss possible interactions of these hormones with the calcitonin gene-related peptide (CGRP) system in light of the success of anti-CGRP treatments. We propose a simple model to explain the hormone withdrawal trigger in menstrual migraine, which could provide a foundation for improved management and therapy for hormone-related migraine in women.

Headache in people with epilepsy

Epidemiological estimates indicate that individuals with epilepsy are more likely to experience headaches, including migraine, than individuals without epilepsy. Headaches can be temporally unrelated to seizures, or can occur before, during or after an episode; seizures and migraine attacks are mostly not temporally linked. The pathophysiological links between headaches (including migraine) and epilepsy are complex and have not yet been fully elucidated. Correct diagnoses and appropriate treatment of headaches in individuals with epilepsy is essential, as headaches can contribute substantially to disease burden. Here, we review the insights that have been made into the associations between headache and epilepsy over the past 5 years, including information on the pathophysiological mechanisms and genetic variants that link the two disorders. We also discuss the current best practice for the management of headaches co-occurring with epilepsy and highlight future challenges for this area of research.

Headache in transgender and gender-diverse patients: A narrative review

OBJECTIVE

To summarize the unique aspects of managing headache in gender minorities and current research in this area including the potential relationship between gender-affirming hormone therapy (GAHT) and headache.

BACKGROUND

The study of headache in gender minorities is intrinsically important. Gender minorities are medically underserved, and their medical care to date has been limited by socioeconomic disadvantages including stigma and an unsupportive clinical environment. Despite the rising population of transgender and gender-diverse adults and youth, headache research has also been limited. Knowledge of hormonal effects on headache in cisgender patients raises the question of possible effects of GAHT on transgender patients.

METHODS/RESULTS

The manuscript is a narrative review of current best practices in treating transgender patients, including the use of appropriate terminology and ways to create a supportive environment. It also contains current guidelines on GAHT and reviews drug-drug interactions and secondary headache related to hormone therapy. We also review transgender headache research and related research on hormonal effects on headache in cisgender individuals.

CONCLUSION

Creating a supportive environment for transgender and gender-diverse patients and being knowledgeable about GAHT are key to providing quality headache care. This review identifies further research needs for this population including the epidemiology of headache disorders in sexual minorities and the potential effects of GAHT on headache disorders in transgender patients.

Dihydroergotamine infusion for pediatric refractory headache: A retrospective chart review

BACKGROUND

Headaches are a common symptom in children. Children with refractory headaches may be admitted for inpatient treatment with intravenous dihydroergotamine mesylate (DHE). However, very few studies have characterized these patients and their treatment outcomes using validated, self-reported, pain scales.

OBJECTIVE

The objective of this study was to describe demographic and clinical characteristics of children admitted for DHE infusion, determine DHE treatment outcomes by means of numeric pain scale ratings, and explore associations between treatment outcomes and clinical characteristics.

METHODS

Retrospective chart review was completed in patients ages 5-21 admitted for DHE infusion from January 2013 to July 2018 at a large, pediatric academic medical center and community-based satellite center. All primary headache types were included.

RESULTS

A total of 200 unique admissions for DHE were available for analysis. Overall, patients were predominantly White (87.5%, 175/200) and female (80.0%, 160/200) with an average age of 15.4 years (SD 2.3). Common comorbidities included obesity (42.0%, 81/193), anxiety (41.0%, 82/200), and depression (20.0%, 40/200). The mean length of stay was 2.4 days (SD 1.10; range 1-8 days). Most headaches (65.0%, 130/200) met the International Classification of Headache Disorders, 3rd edition criteria for migraine, followed by new daily persistent headache (25.5%, 51/200). Mean DHE maximum dose was 5.3 (SD 2.17; range 0.5-14.5 mg) with most patients requiring 3.5-6.5 mg. DHE was typically terminated at six doses (range 1-15). The most frequently reported adverse event was nausea (5.5%, 11/200). There was no difference in pain severity at admission across headache types, with an average baseline pain score of 8.1 (SD 1.6). Posttreatment reduction in pain score was statistically significant (range: -3.2 to -4.9; each p < 0.001) across all headache types. Overall, 84.0% (168/200) of the patients had some improvement in pain. More than half of the patients (53.5%, 107/200) showed at least moderate improvement (≥50.0% reduction in pain score), and 18.0% (36/200) had full headache resolution. Limited patients (16.0%, 32/200) experienced no improvement in pain.

CONCLUSIONS

Treatment with DHE resulted in at least some improvement for most patients regardless of headache type or number of doses. Clinical trials stratified by headache type and comorbid factors could help clarify treatment algorithms to optimize patient outcomes.

The prevalence and burden of recurrent headache in Australian adolescents: findings from the longitudinal study of Australian children

Background

Headache disorders are highly prevalent worldwide, but not well investigated in adolescents. Few studies have included representative nationwide samples. This study aimed to present the prevalence and burden of recurrent headache in Australian adolescents.

Methods

The prevalence of recurrent headache, headache characteristics (severity and frequency) and burden on health-related quality of life in Australian children aged 10–17 years were presented, using nationally representative data from the Longitudinal Study of Australian children (LSAC). The LSAC, commencing in 2004, collects data every 2 years from a sample of Australian children of two different age cohorts: B ‘baby’ cohort, aged 0–1 years and K ‘kindergarten’ cohort, aged 4–5 years at the commencement of the study. Face-to-face interviews and self-complete questionnaires have been conducted with the study child and parents of the study child (carer-reported data) at each data collection wave, with seven waves of data available at the time of the current study. Wave 7 of the LSAC was conducted in 2016, with B cohort children aged 12–13 years and K cohort children aged 16–17 years. For the current study, data were accessed for four out of seven waves of available data (Wave 4–7) and presented cross-sectionally for the two cohorts of Australian children, for the included age groups (10–11 years, 12–13 years, 14–15 years and 16–17 years). All available carer-reported questionnaire data pertaining to headache prevalence, severity and frequency, general health and health-related quality of life, for the two cohorts, were included in the study, and presented for male and female adolescents. Carer-reported general health status of the study child and health-related quality of life scores, using the parent proxy-report of the Paediatric Quality of Life Inventory™ 4.0, were compared for male and female adolescents with recurrent headache and compared with a healthy group. Finally, health-related quality of life scores were compared based on headache frequency and severity.

Results

The LSAC study initially recruited 10,090 Australian children (B cohort n = 5107, K cohort n = 4983), and 64.1% of the initial sample responded at wave 7. Attrition rates across the included waves ranged from 26.3% to 33.8% (wave 6 and 7) for the B cohort, and 16.3% to 38.0% (wave 4–7) for the K cohort. Recurrent headache was more common in females, increasing from 6.6% in 10–11 years old females to 13.2% in 16–17 years old females. The prevalence of headache in males ranged from 4.3% to 6.4% across the age groups. Health-related quality of life scores were lower for all functional domains in adolescents with recurrent headache, for both sexes. Headache frequency, but not severity, was significantly associated with lower health-related quality of life scores, in both males and females.

Conclusions

Recurrent headache was common among Australian adolescents and increased in prevalence for females, across the age groups. Frequent recurrent headache is burdensome for both male and female adolescents. This study provides information regarding the prevalence and burden of recurrent headache in the adolescent population based on findings from the Longitudinal Study of Australian Children.

Gender-related differences in migraine

Migraine is considered mostly a woman’s complaint, even if it affects also men. Epidemiological data show a higher incidence of the disease in women, starting from puberty throughout life. The sex-related differences of migraine hold clinical relevance too. The frequency, duration, and disability of attacks tend to be higher in women. Because of this, probably, they also consult specialists more frequently and take more prescription drugs than men. Different mechanisms have been evaluated to explain these differences. Hormonal milieu and its modulation of neuronal and vascular reactivity is probably one of the most important aspects. Estrogens and progesterone regulate a host of biological functions through two mechanisms: nongenomic and genomic. They influence several neuromediators and neurotransmitters, and they may cause functional and structural differences in several brain regions, involved in migraine pathogenesis. In addition to their central action, sex hormones exert rapid modulation of vascular tone. The resulting specific sex phenotype should be considered during clinical management and experimental studies.

Impact of Puberty in Girls on Prevalence of Primary Headache Disorder Among Female Schoolchildren in Kuwait

Background: The prevalence of primary headaches in the pediatric population is shaped by many factors, of which pubertal status may possibly play a substantial role. Epidemiological studies in the pediatric population in the gulf region remain scarce.

Aims and objectives: To examine the impact of puberty on the prevalence of primary headache disorders among female schoolchildren in Kuwait.

Methods: We conducted a cross-sectional study that included Kuwaiti primary and middle schoolgirls in randomly selected schools located in two governorates in Kuwait during the academic year 2018/2019. Prevalence of headache was assessed using the Headache-Attributed Restriction, Disability, Social Handicap and Impaired Participation (HARDSHIP) questionnaire for children and adolescents. Female students were asked about their menarchal status and whether they attained menarche before or after experiencing headaches.

Results: The questionnaire was completed by 669 girls with a mean age of 11.44 ± 2.14 years. The 1-year prevalence of migraine headache disorder among girls was 23.62%, and the lifetime prevalence of any headache was 84.9%, whereas the 1-year prevalence of primary headache disorders was 47.98%. The mean age of girls with headaches was 11.44 ± 2.14 years. With respect to diagnostic criteria, migraine headache was the most frequently reported (23.62%), followed by tension-type headaches (20.93%), chronic headaches (2.99%), and probable medication-overuse headaches (0.45%). Postpubertal females were at significantly higher risk of having primary headaches compared to their prepubertal counterparts (64.26 vs. 34%; p < 0.0001). All types of primary headaches were more significantly prevalent among postpubertal girls compared to those who are prepubertal.

Conclusion: Migraine headache is commonly reported among Kuwaiti schoolgirls. Postpubertal females are at higher risk of developing primary headaches compared to prepubertal females. Pubertal transition and female sex hormones may play a significant role in the pathophysiology of headaches, migraines in particular, and further research is therefore needed to investigate the underlying mechanisms.

Targeting BKCa Channels in Migraine: Rationale and Perspectives

Large (big)-conductance calcium-activated potassium (BK_Ca) channels are expressed in migraine-related structures such as the cranial arteries, trigeminal ganglion and trigeminal spinal nucleus, and they play a substantial role in vascular tonus and neuronal excitability. Using synthetic BK_Ca channels openers was associated with headache as a frequent adverse effect in healthy volunteers. Additionally, BK_Ca channels are downstream molecules in migraine signalling pathways that are activated by several compounds known to provoke migraine, including calcitonin gene-related peptide (CGRP), pituitary adenylate cyclase-activating polypeptide (PACAP) and glyceryl trinitrate (GTN). Also, there is a high affinity and a close coupling between BK_Ca channels and ATP-sensitive potassium (K_ATP) channels, the role of which has recently been established in migraine pathophysiology. These observations raise the question as to whether direct BK_Ca channel activation can provoke migraine in migraine patients, and whether the BK_Ca channel could be a potential novel anti-migraine target. Hence, randomized and placebo-controlled clinical studies on BK_Ca channel openers or blockers in migraine patients are needed.

Menstrual migraine: what it is and does it matter?

The diagnostic criteria of menstrual migraine (MM), migraine related to menstruation and pure menstrual migraine, are placed in the appendix of the International Classification of Headache Disorders and are still primarily considered as research criteria that need validation. Although there is a great wealth of knowledge about the neurobiological processes underlying MM and its symptoms, the mechanisms by which an attack starts during the menstrual cycle remain baffling, and the disease is still undertreated. In this narrative review, we aim to summarize recent data on pathophysiology, epidemiology, burden of disease and treatment of MM. The vast majority of the literature focuses on the relationship between MM and hormonal factors. The role of falling in estrogen levels is believed to increase the susceptibility of blood vessels to prostaglandins, which have been implicated in neurogenic inflammation. Moreover, fluctuations of ovarian steroid hormone levels modulate calcitonin gene-related peptide in the trigeminovascular system. In addition, it has been observed that gonadal hormones modulate cortical spreading depression susceptibility in animal models. Sex hormone influences on MM affect not only the frequency and severity of headache attack but also its treatment. Understanding the mechanisms that contribute to neuroendocrine vulnerability in some women and some menstrual cycles may yield possible marker of the disease opening treatment options specifically targeting MM. An increased interest for future research on the subject will further elucidate how to manage this debilitating type of migraine.

Allodynia in Menstrually Related Migraine: Score Assessment by Allodynia Symptom Checklist (ASC-12)

OBJECTIVE

The aim of this study was to compare the allodynia score in headache attacks related and not related to menstruation in women diagnosed with menstrually related migraine without aura.

BACKGROUND

Allodynia is an important symptom in migraine and has been associated with migraine chronification. No study has yet compared prospectively allodynia in menstrual vs non-menstrual attacks within the same cohort of patients.

METHODS

This is a prospective cohort study, where participants had the 12-item Allodynia Symptom Checklist (ASC-12) assessed after 1, 2, 4, and 24 hours from the onset of migraine attacks in 2 different conditions, with menstrual migraine attack (MM+) and with non-menstrual migraine attack (MM-).

RESULTS

A total of 600 women with headache complaints were screened from March 2013 to July 2014 in a headache outpatient or headache tertiary clinic. From these, 55 participants were recruited, and 32 completed the study. Participants' mean age was 27 years, BMI was 22.1, menarche age 12 years, migraine history was 11.5 years, and most women were young (ranged from 17 to 44 years of age), were in higher school (13/32 = 41%), single (20/32 = 63%), and used contraceptives (22/32 = 69%). Multiple pairwise comparisons of ANCOVA's test showed significant higher ASC-12 scores in MM+ group compared to MM- group at 2 hours [mean, 95% CI of difference: 2.3 (0.31, 4.7), P = .049)]. For the ASC-12 categorical scores (absent, mild, moderate, and severe) MM+ yielded higher scores than MM- at 1 hour (z = -3.08, P = .021) and 4 hours (z = -2.97, P = .03).

CONCLUSION

This study demonstrated that in the patents from tertiary headache center assessed, menstrual-related migraine attacks augment allodynia scores in the beginning of attacks compared to non-menstrual migraine attacks.

Sex Differences of Migraine: Results of a Nationwide Home-based Study in Turkey

Introduction

The prevalence of migraine was found to be more than three-fold higher in women as compared with men, and in addition to differences in prevalence rates, the characteristics and associated features might also differ between the sexes. The aim of this study was to compare sex-specific features of migraine and demographic parameters in a nationwide population-based study in Turkey.

Methods

Among 5323 subjects, a total of 871 patients who were diagnosed as having definite migraine according to the diagnostic criteria of the International Classification of Headache Disorders-III (ICHD-III) were included in our study. The demographic characteristics, associated features, and triggers of migraine were examined with regard to sex.

Results

The study group comprised 640 women (73.5%) and 231 men (26.5%), with a female to male ratio of 2.8:1. Attack duration, mean migraine disability assessment scores (MIDAS), frequencies of nausea, vomiting, osmophobia, vertigo/dizziness, and allodynia were found significantly different between women and men. When we compared these parameters between men and postmenopausal women, all these parameters were still significant except nausea. Odor was statistically more frequent as a reported trigger in women, whereas excessive sleep was a statistically more frequent triggering factor in men. The rates of depression and allergy were significantly higher in women when compared with men.

Conclusion

Longer attack duration, higher MIDAS scores, and the frequencies of nausea, vomiting, osmophobia, vertigo/dizziness, and allodynia were more significant in women and this variance in sex persisted after menopause. Also, some trigger factors and co-morbidities differed between the sexes. These findings might result from complex genetic factors besides sociocultural influences, biologic, and sociocultural roles. Future studies should continue to explore biologic and genetic factors with respect to sex in migraine.

Migraine in Women

Migraine is a lifelong condition that disproportionately affects women and, if not effectively managed, can lead to significant disability. It is important for clinicians to have a good understanding of the impact of the hormonal fluctuations that occur throughout a female migraineur's life, so that appropriate, stratified therapies can be implemented. In doing so, whether it is migraine onset at menarche in an adolescent young woman, or migraine worsening in a perimenopausal female migraineur, quality of life can be ensured.

Comparison of chronic daily headache with and without medication overuse headache using ICHD II R and ICHD 3 beta criteria

OBJECTIVE

To evaluate the frequency of Medication Overuse Headache (MOH) in the patients with Chronic Daily Headache (CDH) using International Classification of Headache Disorder II Revision (ICHD II R) and International Classification of Headache Disorder 3 Beta (ICHD-3 beta) criteria. We also compare the CHD patients with and without MOH using both the criteria.

PATIENTS AND METHODS

Consecutive CDH patients from neurology service between 2014 and 2015 were included. The patients with CDH was categorised to MOH was based on ICHDIIR and ICHD-3 beta criteria. Their demographic and headache characteristics including frequency, duration, severity and disability were noted. Severity of headache was assessed using Visual Analogue Scale (VAS). Predictors of MOH were evaluated by multivariate analysis. Demographic and headache characteristics of CDH patients without MOH were compared with those with MOH.

RESULTS

202 patients were included whose median age was 32 (range 18-65) years, and 151(74.8%) were females. 12.3% patients fulfilled ICHDIIR criteria for MOH and 46.5% fulfilled ICHD-3 beta criteria. The predictors of MOH were female gender (OR = 3.72; 95% CI 1.72-8.02, p = 0.001), low education level (OR = 1.07, 95%CI 1.02-1.13; p = 0.007) and higher VAS score (OR = 0.67, 95%CI 0.51-0.88; p = 0.004). MOH patients as per ICHD-3 beta criteria had higher education (p = 0.02) and consumed lesser abortive drugs (p = 0.03) as compared with ICHDIIR criteria.

CONCLUSION

The frequency of MOH increases by four-fold when using ICHD-3 beta criteria instead of ICHDIIR criteria. Females with lower education level predispose to MOH.

Migraine in the Young Brain: Adolescents vs. Young Adults

Migraine is a disease that peaks in late adolescence and early adulthood. The aim of this study was to evaluate age-related brain changes in resting state functional connectivity (rs-FC) in migraineurs vs. age-sex matched healthy controls at two developmental stages: adolescence vs. young adulthood. The effect of the disease was assessed within each developmental group and age- and sex-matched healthy controls and between developmental groups (migraine-related age effects). Globally the within group comparisons indicated more widespread abnormal rs-FC in the adolescents than in the young adults and more abnormal rs-FC associated with sensory networks in the young adults. Direct comparison of the two groups showed a number of significant changes: (1) more connectivity changes in the default mode network in the adolescents than in the young adults; (2) stronger rs-FC in the cerebellum network in the adolescents in comparison to young adults; and (3) stronger rs-FC in the executive and sensorimotor network in the young adults. The duration and frequency of the disease were differently associated with baseline intrinsic connectivity in the two groups. fMRI resting state networks demonstrate significant changes in brain function at critical time point of brain development and that potentially different treatment responsivity for the disease may result.

Neonatal treatment with ovarian hormones and suckling among distinct litter sizes: Differential effects on recognition memory and spreading depression at adulthood

OBJECTIVES

Ovarian hormones (OH) and early malnutrition may affect the developing brain, with repercussions on behavioral and excitability-dependent processes. However, the possible synergistic effects of both factors have not been analyzed. In this study, we investigated the effect of treatment in early life with OH and suckling among distinct litter sizes on recognition memory, anxiety behavior, and the excitability-dependent phenomenon known as cortical spreading depression (CSD).

METHODS

Female Wistar rats were suckled under favorable and unfavorable lactation, corresponding to litters with 9 and 15 pups (L9 and L15 groups, respectively). From postnatal days (P) 7 to 21, the animals received 50 µg/kg of β-estradiol or progesterone. From P80 to P84, we tested behavioral reactions. From P90 to P120, we analyzed CSD parameters.

RESULTS

Compared with the corresponding L9 groups, the OH-treated L15 groups performed worse in recognition memory tasks. No intergroup difference in the anxiety parameters was observed. Compared with naive and vehicle-treated controls, OH-treated groups displayed higher CSD velocities and amplitudes and shorter CSD durations.

DISCUSSION

Early treatment with OH facilitates recognition memory and CSD, and in association with unfavorable lactation (L15) impaired recognition memory, but not anxiety behavior, in the adult brain. OH treatment and L15 lactation condition seem to interact regarding OH action on memory, but not on CSD. Data suggest a long-lasting differential effect that might be related to the lasting hormonal action on brain excitability. We postulate and discuss the possibility that these findings may be implicated in human neurological diseases.

Living with Migraine in Canada – A National Community-Based Study

Objective: To develop a detailed profile of individuals living with migraine in Canada. Such a profile is important for planning and administration of services. Methods: The 2011–2012 Survey of Living with Neurological Conditions in Canada (SLNCC), a cross-sectional community-based survey, was used to examine a representative sample of migraineurs (N = 949) aged 15 years and older. Several health-related variables were examined (e.g., general health, health utility index (HUI) [a measure of health status and health-related quality of life, where dead = 0.00 and perfect health = 1.00], stigma, depression, and social support). Respondents were further stratified by sex, age, and age of migraine onset. Weighted overall and stratified prevalence estimates and odds ratios, both with 95% CIs, were used to estimate associations. Results: Overall, males had poorer health status compared with females (e.g., mean HUI was 0.67 in males vs. 0.82 in females; men had over two times the odds of their migraine limiting educational and job opportunities compared with females). Poorer health-related variables were seen in the older age groups (35–64 years/≥65 years) compared with the 15–34-year age group. There were no differences between those whose migraine symptoms began before versus after the age of 20 years. Conclusions: In this Canadian sample, migraine was associated with worse health-related variables in men compared with women. However, both men and women were significantly affected by migraine across various health-related variables. Thus, it is important to improve clinical and public health interventions addressing the impact of migraine across individuals of all ages, sexes, and sociodemographic backgrounds.

Emerging relevance of circadian rhythms in headaches and neuropathic pain

Circadian rhythms of physiology are the keys to health and fitness, as dysregulation, by genetic mutations or environmental factors, increases disease risk and aggravates progression. Molecular and physiological studies have shed important light on an intrinsic clock that drives circadian rhythms and serves essential roles in metabolic homoeostasis, organ physiology and brain functions. One exciting new area in circadian research is pain, including headache and neuropathic pain for which new mechanistic insights have recently emerged. For example, cluster headache is an intermittent pain disorder with an exceedingly precise circadian timing, and preliminary evidence is emerging linking several circadian components (eg, Clock and Nr1d1) with the disease. In this review, we first discuss the broad metabolic and physiological relevance of the circadian timing system. We then provide a detailed review of the circadian relevance in pain disease and physiology, including cluster headache, migraine, hypnic headache and neuropathic pain. Finally, we describe potential therapeutic implications, including existing pain medicines and novel clock-modulating compounds. The physiological basis for the circadian rhythms in pain is an exciting new area of research with profound basic and translational impact.

Male and female sex hormones in primary headaches

BACKGROUND

The three primary headaches, tension-type headache, migraine and cluster headache, occur in both genders, but all seem to have a sex-specific prevalence. These gender differences suggest that both male and female sex hormones could have an influence on the course of primary headaches. This review aims to summarise the most relevant and recent literature on this topic.

METHODS

Two independent reviewers searched PUBMED in a systematic manner. Search strings were composed using the terms LH, FSH, progesteron*, estrogen*, DHEA*, prolactin, testosterone, androgen*, headach*, migrain*, "tension type" or cluster. A timeframe was set limiting the search to articles published in the last 20 years, after January 1st 1997.

RESULTS

Migraine tends to follow a classic temporal pattern throughout a woman's life corresponding to the fluctuation of estrogen in the different reproductive stages. The estrogen withdrawal hypothesis forms the basis for most of the assumptions made on this behalf. The role of other hormones as well as the importance of sex hormones in other primary headaches is far less studied.

CONCLUSION

The available literature mainly covers the role of sex hormones in migraine in women. Detailed studies especially in the elderly of both sexes and in cluster headache and tension-type headache are warranted to fully elucidate the role of these hormones in all primary headaches.

Female sex hormones in men with migraine

Objective

To assess the role of estradiol and testosterone in men with migraine.

Methods

We measured 17β-estradiol (E2) and calculated free testosterone (Tf) in serum of 17 medication-free men with migraine and 22 men without migraine group-matched for age and body mass index (BMI), targeted at 20 to 28 kg/m2. Blood was sampled on a single, for migraineurs interictal, day at 9 am, 12 pm, 3 pm, and 6 pm. Migraineurs were subsequently measured 3 to 4 times daily until an attack occurred. Clinical androgen deficiency was assessed with the Androgen Deficiency of Ageing Men questionnaire and the Aging Males' Symptoms (AMS) scale. We analyzed interictal data (mean ± standard error) with repeated-measures analysis of covariance and longitudinal data by generalized estimated equations models.

Results

Compared to controls, men with migraine had a lower interictal Tf/E2 ratio (3.9 ± 0.4 vs 5.0 ± 0.3, p = 0.03) due to higher E2 (96.8 ± 6.1 vs 69.1 ± 5.6 pmol/L, p = 0.001) and similar Tf (357.5 ± 21.4 vs 332.6 ± 18.7 pmol/L, p = 0.35) levels. Preictal Tf levels were increased in men with migraine reporting premonitory symptoms (p = 0.03). Men with migraine more frequently reported symptoms of androgen deficiency (11 of 18 [61.1%] vs 6 of 22 [27.3%], p = 0.031), which were also more frequently severe (p = 0.006); their age- and BMI-adjusted AMS scores were higher (27.0 ± 1.2 vs 21.0 ± 1.0, p = 0.002).

Conclusions

In this study, nonobese men with migraine exhibited increased levels of the sex hormone estradiol and showed clinical evidence of relative androgen deficiency. The role of estradiol in modulating migraine susceptibility and activity in men deserves further investigations.

Cephalic cutaneous allodynia in children and adolescents with migraine of short duration: A retrospective cohort study

BACKGROUND

Allodynia is prevalent in adults with migraine and has been associated with long disease duration and severe course. Studies of the pediatric population are sparse. The aim of this study was to evaluate the rate of cephalic cutaneous allodynia in children and adolescents within the first 6 months of migraine onset and to identify associated clinical and migraine-related parameters.

METHODS

The electronic database of a tertiary pediatric headache clinic from 2014 to 2017 was retrospectively searched for all children and adolescents diagnosed with migraine headache within 6 months or less of symptom onset. Cephalic cutaneous allodynia was identified by validated questionnaire. Demographics, symptoms, and headache-related parameters were compared between patients with and without allodynia.

RESULTS

The cohort included 119 patients, 69 girls (58.0%) and 50 (42.0%) boys, of mean age 11.6 ± 3.6 years. Mean time since onset of migraine disease was 3.6 ± 1.8 months. Cephalic cutaneous allodynia was reported by 31.1% of patients. It was significantly associated with female gender ( p = 0.03), older age at admission ( p = 0.037), older age at onset ( p = 0.042) migraine with aura ( p = 0.002), and higher rate of awakening pain ( p = 0.017).

CONCLUSIONS

Cephalic cutaneous allodynia may occur in children and adolescents already in the first 6 months of migraine onset. Contrary to adult studies, we found no association of allodynia with migraine frequency or long disease duration. Allodynia was significantly associated with migraine with aura, female gender, and awakening pain. A genetic tendency may contribute to the appearance of allodynia in the pediatric age group.

17-β-Estradiol induces spreading depression and pain behavior in alert female rats

AIMS

Test the putative contribution of 17-β-estradiol in the development of spreading depression (SD) events and head pain in awake, non-restrained rats.

MAIN METHODS

Female, Sprague-Dawley rats were intact or underwent ovariectomy followed one week later by surgery to place electrodes onto the dura to detect epidural electroencephalographic activity (dEEG). dEEG activity was recorded two days later for 12 hours after systemic administration of 17-β-estradiol (180 μg/kg, i.p.). A separate set of rats were observed for changes in exploratory, ambulatory, fine, and rearing behaviors; periorbital allodynia was also assessed.

KEY FINDINGS

A bolus of 17-β-estradiol significantly elevated serum estrogen levels, increased SD episodes over a 12-hour recording period and decreased rearing behaviors in ovariectomized rats. Pre-administration of ICI 182,780, an estrogen receptor antagonist, blocked 17-β-estradiol-evoked SD events and pain behaviors; similar results were observed when the antimigraine therapeutic sumatriptan was used.

SIGNIFICANCE

These data indicate that an estrogen receptor-mediated mechanism contributes to SD events in ovariectomized rats and pain behaviors in both ovariectomized -and intact- rats. This suggests that estrogen plays a different role in each phenomenon of migraine where intense fluctuations in concentration may influence SD susceptibility. This is the first study to relate estrogen peaks to SD development and pain behaviors in awake, freely moving female rats, establishing a framework for future preclinical migraine studies.

Symptoms of central sensitization and comorbidity for juvenile fibromyalgia in childhood migraine: an observational study in a tertiary headache center

Background

Central sensitization is an important epiphenomenon of the adult migraine, clinically expressed by allodynia, pericranial tenderness and comorbidity for fibromyalgia in a relevant number of patients. This study aimed to evaluate the frequency and the clinical characteristics of allodynia, pericranial tenderness, and comorbidity for Juvenile Fibromialgia (JFM) in a cohort of migraine children selected in a tertiary headache center.

Methods

This was an observational cross-sectional study on 8–15 years old migraine patients. Allodynia was assessed by a questionnaire. Pericranial tenderness and comorbidity for JFM as well as their possible association with poor quality of life and migraine related disability, and with other clinical symptoms as anxiety, depression, sleep disorders and pain catastrophizing, were also evaluated.

Results

One hundred and fifty one patients were selected, including chronic migraine (n°47), migraine without aura (n° 92) and migraine with aura (n° 12) sufferers. Allodynia was reported in the 96,6% and pericranial tenderness was observed in the 68.8% of patients. Pericranial tenderness was more severe in patients with more frequent migraine and shorter sleep duration. Allodynia seemed associated with anxiety, pain catastrophizing and high disability scores. Comorbidity for JFM was present in the 0.03% ofpatients. These children presented with a severe depression and a significant reduction of quality of life as compared to the other patients.

Conclusions

This study outlined a relevant presence of symptoms of central sensitization among children with migraine. Severe allodynia and comorbidity for JFM seemed to cause a general decline of quality of life, which would suggest the opportunity of a routine assessment of these clinical features.