A critical view on the role of migraine triggers in the genesis of migraine pain

Conceptualising migraine attacks from a biopsychosocial model using qualitative and functional behavioural analysis

OBJECTIVE

The aim of this study was to explore patients' experiences and management of pain in connection with a migraine attack in episodic migraine.

DESIGN, SETTING AND SUBJECTS

This qualitative study used a semi-structured interview format based on functional behavioural analysis as commonly used in cognitive behavioural therapy. We interviewed eight participants and analysed their responses using systematic text condensation.

RESULTS

Participants' descriptions of their experiences and management of pain from episodic migraine were sorted into three description First physical sensations, Automatic reactions and Acts according to the interpretation.

CONCLUSION

From a biopsychosocial perspective, a migraine attack is much more complex than just an experience of pain. The purely biological pain prompts a number of automatic reactions leading to strategies for pain management.

Migraine drugs

According to recent studies, migraine affects more than 1 billion people worldwide, making it one of the world’s most prevalent diseases. Although this highly debilitating illness has been known since ancient times, the first therapeutic drugs to treat migraine, ergotamine (Gynergen) and dihydroergotamine (Dihydergot), did not appear on the market until 1921 and 1946, respectively. Both drugs originated from Sandoz, the world’s leading pharmaceutical company in ergot alkaloid research at the time. Historically, ergot alkaloids had been primarily used in obstetrics, but with methysergide (1-methyl-lysergic acid 1′-hydroxy-butyl-(2S)-amide), it became apparent that they also held some potential in migraine treatment. Methysergide was the first effective prophylactic drug developed specifically to prevent migraine attacks in 1959. On the basis of significantly improved knowledge of migraine pathophysiology and the discovery of serotonin and its receptors, Glaxo was able to launch sumatriptan in 1992. It was the first member from the class of triptans, which are selective 5-HT1B/1D receptor agonists. Recent innovations in acute and preventive migraine therapy include lasmiditan, a selective 5-HT1F receptor agonist from Eli Lilly, the gepants, which are calcitonin gene-related peptide (CGRP) receptor antagonists discovered at Merck & Co and BMS, and anti-CGRP/receptor monoclonal antibodies from Amgen, Pfizer, Eli Lilly, and others.

Graphical abstract

Testing the Role of Glutamate NMDA Receptors in Peripheral Trigeminal Nociception Implicated in Migraine Pain

The pro-nociceptive role of glutamate in the CNS in migraine pathophysiology is well established. Glutamate, released from trigeminal afferents, activates second order nociceptive neurons in the brainstem. However, the function of peripheral glutamate receptors in the trigeminovascular system suggested as the origin site for migraine pain, is less known. In the current project, we used calcium imaging and patch clamp recordings from trigeminal ganglion (TG) neurons, immunolabelling, CGRP assay and direct electrophysiological recordings from rat meningeal afferents to investigate the role of glutamate in trigeminal nociception. Glutamate, aspartate, and, to a lesser extent, NMDA under free-magnesium conditions, evoked calcium transients in a fraction of isolated TG neurons, indicating functional expression of NMDA receptors. The fraction of NMDA sensitive neurons was increased by the migraine mediator CGRP. NMDA also activated slowly desensitizing currents in 37% of TG neurons. However, neither glutamate nor NMDA changed the level of extracellular CGRP. TG neurons expressed both GluN2A and GluN2B subunits of NMDA receptors. In addition, after removal of magnesium, NMDA activated persistent spiking activity in a fraction of trigeminal nerve fibers in meninges. Thus, glutamate activates NMDA receptors in somas of TG neurons and their meningeal nerve terminals in magnesium-dependent manner. These findings suggest that peripherally released glutamate can promote excitation of meningeal afferents implicated in generation of migraine pain in conditions of inherited or acquired reduced magnesium blockage of NMDA channels and support the usage of magnesium supplements in migraine.

The trigeminal system: The meningovascular complex- A review

Supratentorial sensory perception, including pain, is subserved by the trigeminal nerve, in particular, by the branches of its ophthalmic division, which provide an extensive innervation of the dura mater and of the major brain blood vessels. In addition, contrary to previous assumptions, studies on awake patients during surgery have demonstrated that the mechanical stimulation of the pia mater and small cerebral vessels can also produce pain. The trigeminovascular system, located at the interface between the nervous and vascular systems, is therefore perfectly positioned to detect sensory inputs and influence blood flow regulation. Despite the fact that it remains only partially understood, the trigeminovascular system is most probably involved in several pathologies, including very frequent ones such as migraine, or other severe conditions, such as subarachnoid haemorrhage. The incomplete knowledge about the exact roles of the trigeminal system in headache, blood flow regulation, blood barrier permeability and trigemino-cardiac reflex warrants for an increased investigation of the anatomy and physiology of the trigeminal system. This translational review aims at presenting comprehensive information about the dural and brain afferents of the trigeminovascular system, in order to improve the understanding of trigeminal cranial sensory perception and to spark a new field of exploration for headache and other brain diseases.

Natural Products and their (Semi-)Synthetic Forms in the Treatment of Migraine: History and Current Status

BACKGROUND

Migraine may be described as a headache with moderate to extreme pain that is often accompanied by incapacitating neurological symptoms. It is estimated that 12% of the world population suffers from migraine. Although a number of drugs have been used for treatment of migraine, most of these are not effective for every patient and may have undesirable side-effects. Thus, there is an enormous unmet need in current migraine therapy for discovering safer and more effective agents.

METHODS

The information summarized in this review was obtained through extensive literature review and search of relevant books and articles with the use of Web of Knowledge and SciVerse Scopus databases.

RESULTS

Greater understanding of the molecular mechanisms underlying the etiopathogenesis of migraine is helpful in identifying novel targets for antimigraine drugs such as cannabinoid, histamine, and melatonin receptors. In the past, natural product-derived constituents have served as an invaluable source of numerous medicinally useful antimigraine agents and it may be expected that further promising drug candidates from natural products will be discovered for antimigraine pharmacotherapy with better efficacy and fewer adverse-effects.

CONCLUSION

The discovery of novel targets in migraine therapy has opened new horizons for compounds that have not been clinically tested or that previously failed in clinical trials as potential antimigraine drugs. Ginkgolide B, melatonin, histamine, oxytocin, various ribosomal peptide toxins, kavalactones, devil's claw-derived compounds, salvinorin A and petasin are among those agents that show considerable promise as novel drugs in migraine prevention and treatment. It is necessary to conduct more research to better understand their antimigraine action, to confirm their effectiveness and safety, and to introduce them into clinical practice.

Is an "Epigenetic Diet" for Migraines Justified? The Case of Folate and DNA Methylation

Migraines are a common disease with limited treatment options and some dietary factors are recognized to trigger headaches. Although migraine pathogenesis is not completely known, aberrant DNA methylation has been reported to be associated with its occurrence. Folate, an essential micronutrient involved in one-carbon metabolism and DNA methylation, was shown to have beneficial effects on migraines. Moreover, the variability of the methylenetetrahydrofolate reductase gene, important in both folate metabolism and migraine pathogenesis, modulates the beneficial effects of folate for migraines. Therefore, migraine could be targeted by a folate-rich, DNA methylation-directed diet, but there are no data showing that beneficial effects of folate consumption result from its epigenetic action. Furthermore, contrary to epigenetic drugs, epigenetic diets contain many compounds, some yet unidentified, with poorly known or completely unknown potential to interfere with the epigenetic action of the main dietary components. The application of epigenetic diets for migraines and other diseases requires its personalization to the epigenetic profile of a patient, which is largely unknown. Results obtained so far do not warrant the recommendation of any epigenetic diet as effective in migraine prevention and therapy. Further studies including a folate-rich diet fortified with valproic acid, another modifier of epigenetic profile effective in migraine prophylaxis, may help to clarify this issue.

Role of Toll-like receptor 4 signaling in mast cell-mediated migraine pain pathway

Degranulation of meningeal mast cells leading to the sensitization of trigeminal vascular afferent processing is believed to be one of the mechanisms underlying the migraine pain pathway. Recent work suggests that Toll-like receptor 4 (TLR4) may be involved in signaling states of central sensitization. Using a murine model of light aversion produced by compound 48/80 (2 mg/kg, intraperitoneal) mast cell degranulation, employed as a surrogate marker for photophobia observed in migraineurs, we examined the role of TLR4 in migraine-like behavior and neuronal activation. Using a two-chambered light/dark box, we found that compound 48/80 administration in male and female C57Bl/6 mice produced light aversion lasting up to 2 h, and that pre-treatment with sumatriptan (1 mg/kg, i.p.) reliably prevented this effect. Genetic deletion and pharmacological blockade of TLR4 with TAK-242 (3 mg/kg, i.p.) reversed the light aversive effects of compound 48/80 in males but not in females. Assessing the downstream signaling pathway in mutant mice, we found that the TLR4-mediated, light aversion was dependent upon myeloid differentiation primary response gene 88 but not Toll-interleukin-1 receptor domain-containing adapter-inducing interferon-β signaling. In separate groups, male mice sacrificed at 10 min following compound 48/80 revealed a significant increase in the incidence of evoked p-extracellular signal–regulated kinases (+) neurons in the nucleus caudalis of wild type but not Tlr4−/− mice or in mice pre-treated with sumatriptan. This study thus provides the first evidence for involvement of TLR4 signaling through MyD88 in initiating and maintaining migraine-like behavior and nucleus caudalis neuronal activation in the mouse.

Protease activated receptor 2 (PAR2) activation causes migraine-like pain behaviors in mice

BACKGROUND

Pain is the most debilitating symptom of migraine. The cause of migraine pain likely requires activation of meningeal nociceptors. Mast cell degranulation, with subsequent meningeal nociceptor activation, has been implicated in migraine pathophysiology. Degranulating mast cells release serine proteases that can cleave and activate protease activated receptors. The purpose of these studies was to investigate whether protease activated receptor 2 is a potential generator of nociceptive input from the meninges by using selective pharmacological agents and knockout mice.

METHODS

Ratiometric Ca++ imaging was performed on primary trigeminal and dural cell cultures after application of 2at-LIGRL-NH2, a specific protease activated receptor 2 agonist. Cutaneous hypersensitivity and facial grimace was measured in wild-type and protease activated receptor 2-/- mice after dural application of 2at-LIGRL-NH2 or compound 48-80, a mast cell degranulator. Behavioral experiments were also conducted in mice after dural application of 2at-LIGRL-NH2 (2AT) in the presence of either C391, a selective protease activated receptor 2 antagonist, or sumatriptan.

RESULTS

2at-LIGRL-NH2 evoked Ca2+ signaling in mouse trigeminal neurons, dural fibroblasts and in meningeal afferents. Dural application of 2at-LIGRL-NH2 or 48-80 caused dose-dependent grimace behavior and mechanical allodynia that were attenuated by either local or systemic application of C391 as well as in protease activated receptor 2-/- mice. Nociceptive behavior after dural injection of 2at-LIGRL-NH2 was also attenuated by sumatriptan.

CONCLUSIONS

Functional protease activated receptor 2 receptors are expressed on both dural afferents and fibroblasts and activation of dural protease activated receptor 2 produces migraine-like behavioral responses. Protease activated receptor 2 may link resident immune cells to meningeal nociceptor activation, driving migraine-like pain and implicating protease activated receptor 2 as a therapeutic target for migraine in humans.

The impact of self-administered acupressure on sleep quality and fatigue among patients with migraine: A randomized controlled trial

BACKGROUND AND AIM

Poor sleep and fatigue are among the most common complaints of patients with migraine. These problems can lead to different negative consequences such as headaches. This study aimed to examine the impacts of self-administered acupressure on sleep quality and fatigue among patients with migraine.

METHODS

This double-blind randomized controlled trial was conducted in 2016 on 76 patients who suffered from migraine without aura. Patients were conveniently selected from the neurology clinic of Valiasr (PBUH) teaching hospital and randomly allocated to either an acupressure (n = 38) or a sham acupressure group (n = 38) group. Data collection instruments were a demographic questionnaire, Pittsburg Sleep Quality Index, and Fatigue Severity Scale. Patients in the acupressure and the sham acupressure groups were trained to apply acupressure on respectively acupoints and sham points thrice weekly at bedtime for four consecutive weeks. The data were analyzed through the Chi-square, the independent-sample t, the paired-sample t, and the ANCOVA tests at the significance level of less than 0.05.

RESULTS

After controlling sleep quality mean scores at baseline, no significant difference was found between the sleep quality of the two groups after intervention (P > 0.05). The mean scores of fatigue significantly decreased in both acupressure and sham acupressure groups (P < 0.05). However, the decrease in the acupressure group was significantly greater than in the sham acupressure group (P < 0.05).

CONCLUSION

As a noninvasive non-pharmacological therapy, acupressure can significantly reduce fatigue among patients with migraine.

TRP Channels as Potential Targets for Sex-Related Differences in Migraine Pain

Chronic pain is one of the most debilitating human diseases and represents a social and economic burden for our society. Great efforts are being made to understand the molecular and cellular mechanisms underlying the pathophysiology of pain transduction. It is particularly noteworthy that some types of chronic pain, such as migraine, display a remarkable sex dimorphism, being up to three times more prevalent in women than in men. This gender prevalence in migraine appears to be related to sex differences arising from both gonadal and genetic factors. Indeed, the functionality of the somatosensory, immune, and endothelial systems seems modulated by sex hormones, as well as by X-linked genes differentially expressed during development. Here, we review the current data on the modulation of the somatosensory system functionality by gonadal hormones. Although this is still an area that requires intense investigation, there is evidence suggesting a direct regulation of nociceptor activity by sex hormones at the transcriptional, translational, and functional levels. Data are being accumulated on the effect of sex hormones on TRP channels such as TRPV1 that make pivotal contributions to nociceptor excitability and sensitization in migraine and other chronic pain syndromes. These data suggest that modulation of TRP channels' expression and/or activity by gonadal hormones provide novel pathways for drug intervention that may be useful for targeting the sex dimorphism observed in migraine.

Association between Cervical Spondylosis and Migraine: A Nationwide Retrospective Cohort Study

Background: Few studies have investigated the longitudinal association between cervical spondylosis (CS) and migraine by using a nationwide population-based database. Methods: We conducted a retrospective cohort study from 2000 to 2011 identifying 27,930 cases of cervical spondylosis and 111,720 control subjects (those without cervical spondylosis) from a single database. The subjects were frequency-matched on the basis of sex, age, and diagnosis date. The non- cervical spondylosis cohort was four times the size of the cervical spondylosis cohort. To quantify the effects of cervical spondylosis on the risk of migraine, univariate and multivariate Cox proportional hazard regression analyses were used to calculate the hazard ratio (HR), and 95% confidence interval (CI). Results: After a 10-year follow-up controlling for potential confounding factors, overall migraine incidence was higher in the cervical spondylosis cohort than in the non-cervical spondylosis cohort (5.16 and 2.09 per 1000 people per year, respectively; crude hazard ratio = 2.48, 95% confidence interval = 2.28-2.69), with an adjusted hazard ratio of 2.03 (95% confidence interval = 1.86-2.22) after accounting for sex, age, comorbidities, and medication. Individuals with myelopathy in the cervical spondylosis cohort had a 2.19 times (95% confidence interval = 1.80-2.66) higher incidence of migraine when compared than did those in the non- cervical spondylosis cohort. Conclusions: Individuals with cervical spondylosis exhibited a higher risk of migraine than those without cervical spondylosis. The migraine incidence rate was even higher among individuals with cervical spondylotic myelopathy.

Cerebellar involvement in migraine

Background Although there is a great wealth of knowledge about the neurobiological processes underlying migraine and its accompanying symptoms, the mechanisms by which an attack starts remain elusive, and the disease remains undertreated. Although the vast majority of literature focuses on the involvement of the trigeminovascular systems and higher systems it innervates, such as thalamic and hypothalamic nuclei, several lines of evidence implicate the cerebellum in the pathophysiology of migraine. Aim In this review, we aim to summarize potential cerebellar involvement seen from different perspectives including the results from imaging studies, cerebellar connectivity to migraine-related brain structures, comorbidity with disorders implying cerebellar dysfunction, similarities in triggers precipitating both such disorders, and migraine and cerebellar expression of migraine-related genes and neuropeptides. We aim to inspire an increase in interest for future research on the subject. Conclusion It is hoped that future studies can provide an answer as to how the cerebellum may be involved and whether treatment options specifically targeting the cerebellum could provide alleviation of this disorder.

Trigger Factors in Childhood Migraine: A Prospective Clinic-Based Study From North of France

The objective was to study the prevalence and characterization of pediatric migraine triggers and to compare results to this retrospective study. A total of 101 pediatric patients with ICHD-II migraine with and/or without aura were instructed to prospectively complete a diary dealing with attacks triggers for a 3-month period. Each subject reported at least 1 trigger (range: 1-14) with a total number of 532 attacks and a median per subject of 3. Lack of sleep (51.4%), stress (44.6%), warm climate (41.9%), noise (32.4%), and excitation (29.7%) were the most frequently reported. The delay between trigger exposure and attack onset was between 0 and 3 hours in 67.6% of attacks. This prospective study confirmed the findings of the authors' previous study, with the exception that number of triggers was smaller, probably due to recall bias. The 4 most frequent triggers (lack of sleep, stress, hot weather, and noise) were identical in both studies.

Somatoform Dissociation, Fatigue Severity and Pain Behavior Compared in Patients with Migraine Headache and in Healthy Individuals

The prevalence of migraine in the world is about 15 and 7% among women and men, respectively. The purpose of this study was comparison of somatoform dissociation, fatigue severity and pain behavior in patients with migraine headache and its relationship with coping strategies. This descriptive analytical study has been done on 120 patients with migraine headache and 120 healthy subjects were selected randomly. Data collected by somatoform dissociation questionnaire (SDQ-20), fatigue severity scale, pain behavior scale and coping strategies scale. For data analysis we used SPSS.19. The means of the somatoform dissociation, pain behavior scale, help searching subscale and pain compliant in migraine and healthy subjects were statistically significant. There was not significant difference in avoidance subscales between the two groups. Comparison of fatigue severity in patients with migraine and control group was meaningful. There was significant positive correlation between all four scales and coping strategies. It seems that these symptoms can play an important role in this disease; thus, their careful evaluation in the treatment of migraine headache is essential.

Genetics of Migraine: Insights into the Molecular Basis of Migraine Disorders

Migraine is a complex, debilitating neurovascular disorder, typically characterized by recurring, incapacitating attacks of severe headache often accompanied by nausea and neurological disturbances. It has a strong genetic basis demonstrated by rare migraine disorders caused by mutations in single genes (monogenic), as well as familial clustering of common migraine which is associated with polymorphisms in many genes (polygenic). Hemiplegic migraine is a dominantly inherited, severe form of migraine with associated motor weakness. Family studies have found that mutations in three different ion channels genes, CACNA1A, ATP1A2, and SCN1A can be causal. Functional studies of these mutations has shown that they can result in defective regulation of glutamatergic neurotransmission and the excitatory/inhibitory balance in the brain, which lowers the threshold for cortical spreading depression, a wave of cortical depolarization thought to be involved in headache initiation mechanisms. Other putative genes for monogenic migraine include KCKN18, PRRT2, and CSNK1D, which can also be involved with other disorders. There are a number of primarily vascular disorders caused by mutations in single genes, which are often accompanied by migraine symptoms. Mutations in NOTCH3 causes cerebral autosomal dominant arteriopathy with subcortical infarcts and leukoencephalopathy (CADASIL), a hereditary cerebrovascular disease that leads to ischemic strokes and dementia, but in which migraine is often present, sometimes long before the onset of other symptoms. Mutations in the TREX1 and COL4A1 also cause vascular disorders, but often feature migraine. With respect to common polygenic migraine, genome-wide association studies have now identified single nucleotide polymorphisms at 38 loci significantly associated with migraine risk. Functions assigned to the genes in proximity to these loci suggest that both neuronal and vascular pathways also contribute to the pathophysiology of common migraine. Further studies are required to fully understand these findings and translate them into treatment options for migraine patients.

Grey matter alterations in migraine: A systematic review and meta-analysis

Objectives

To summarize and meta-analyze studies on changes in grey matter (GM) in patients with migraine. We aimed to determine whether there are concordant structural changes in the foci, whether structural changes are concordant with functional changes, and provide further understanding of the anatomy and biology of migraine.

Methods

We searched PubMed and Embase for relevant articles published between January 1985 and November 2015, and examined the references within relevant primary articles. Following exclusion of unsuitable studies, meta-analysis were performed using activation likelihood estimation (ALE).

Results

Eight clinical studies were analyzed for structural changes, containing a total of 390 subjects (191 patients and 199 controls). Five functional studies were enrolled, containing 93 patients and 96 controls. ALE showed that the migraineurs had concordant decreases in the GM volume (GMV) in the bilateral inferior frontal gyri, the right precentral gyrus, the left middle frontal gyrus and the left cingulate gyrus. GMV decreases in right claustrum, left cingulated gyrus, right anterior cingulate, amygdala and left parahippocampal gyrus are related to estimated frequency of headache attack. Activation was found in the somatosensory, cingulate, limbic lobe, basal ganglia and midbrain in migraine patients.

Conclusion

GM changes in migraineurs may indicate the mechanism of pain processing and associated symptoms. Changes in the frontal gyrus may predispose a person to pain conditions. The limbic regions may be accumulated damage due to the repetitive occurrence of pain-related processes. Increased activation in precentral gyrus and cingulate opposed to GMV decrease might suggest increased effort duo to disorganization of these areas and/or the use of compensatory strategies involving pain processing in migraine. Knowledge of these structural and functional changes may be useful for monitoring disease progression as well as for therapeutic interventions.

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There are some concordant structural changes in migraine.

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Some structural changes like frontal lobe and cingulate are also over-activated in interictal phase.

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Frontal gyrus may predispose a person to pain condition.

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Limbic regions may be accumulating brain damage due to pain-related processes.

Responses of dural mast cells in concussive and blast models of mild traumatic brain injury in mice: Potential implications for post-traumatic headache

BACKGROUND

Chronic post-traumatic headache (PTH) is one of the most common symptoms of mild traumatic brain injury (mTBI) but its underlying mechanisms remain unknown. Inflammatory degranulation of dural mast cells (MCs) is thought to promote headache, and may play a role in PTH. Whether mTBI is associated with persistent degranulation of dural MCs is yet to be determined.

METHODS

Histochemistry was used to evaluate time course changes in dural MC density and degranulation level in concussive head trauma and blast mouse models of mTBI. The effects of sumatriptan and the MC stabilizer cromolyn sodium on concussion-evoked dural MC degranulation were also investigated.

RESULTS

Concussive head injury evoked persistent MC degranulation for at least 30 days. Blast trauma gave rise to a delayed MC degranulation response commencing at seven days that also persisted for at least 30 days. Neither sumatriptan nor cromolyn treatment reduced concussion-evoked persistent MC degranulation.

CONCLUSIONS

mTBI evoked by closed head injury or blast exposure is associated with persistent dural MC degranulation. Such a response in mTBI patients may contribute to PTH. Amelioration of PTH by sumatriptan may not involve inhibition of dural MC degranulation. If persistent dural MC degranulation contributes to PTH, then cromolyn treatment may not be effective.

Management of headache and associated factors among undergraduate medicine and health science students of University of Gondar, North West Ethiopia

Background

The headache disorders, namely, migraine and tension type headache and the associated analgesic consumption is badly underestimated and thus makes a major current public health problem. The objective of this study was to determine the prevalence of migraine and tension type headaches and the associated management options used among undergraduate students of College of Medicine and Health Sciences, University of Gondar, Gondar, Ethiopia.

Method

Institution based cross sectional study was conducted among 720 students in May, 2014. Pretested and structured self-administered questionnaires were used as data collecting tool followed by short interview to diagnose the type of headache based on the International Headache Society diagnostic criteria. SPSS version 20 was also used to analyse the data descriptively as well as inferentially using logistic regression models to investigate factors associated with presence of headache and analgesic use.

Result

The prevalence of lifetime headache and headache in the last 12 months was 81.11 and 67.22 %, respectively. Migraine and tension type headache were having 94 (13.06 %) and 481 (66.81 %) prevalence, respectively. Prevalence of life time headache was significant among females, students with family history of headache and lack of adequate vacation time. Similarly, lifetime prevalence of analgesic use for headache was 72.45 % and it had statistical association with sex, age, type of headache, lack of adequate vacation time and family history of headache. Majority of the students, migraineurs (54.65 %) and the tension type headache sufferers (66.17 %) commonly used paracetamol.

Conclusion

High prevalence without adequate medical care seeking behaviour and the associated significant analgesic consumption necessitate the designing of all rounded strategies to improve the quality of life of individuals with such neurologic disorders.

Alcohol-induced headaches: Evidence for a central mechanism?

Alcoholic drinks (ADs) have been reported as a migraine trigger in about one-third of the migraine patients in retrospective studies. Some studies found that ADs trigger also other primary headaches. The studies concerning the role of ADs in triggering various types of primary headaches published after the International Headache Society classification criteria of 1988 were reviewed, and the pathophysiological mechanisms were discussed. Many studies show that ADs are a trigger of migraine without aura (MO), migraine with aura (MA), cluster headache (CH), and tension-type headache (TH). While data on MO and CH are well delineated, those in MA and TH are discordant. There are sparse reports that ADs are also triggers of less frequent types of primary headache such as familial hemiplegic migraine, hemicrania continua, and paroxysmal hemicrania. However, in some countries, the occurrence of alcohol as headache trigger is negligible, perhaps determined by alcohol habits. The frequency estimates vary widely based on the study approach and population. In fact, prospective studies report a limited importance of ADs as migraine trigger. If ADs are capable of triggering practically all primary headaches, they should act at a common pathogenetic level. The mechanisms of alcohol-provoking headache were discussed in relationship to the principal pathogenetic theories of primary headaches. The conclusion was that vasodilatation is hardly compatible with ADs trigger activity of all primary headaches and a common pathogenetic mechanism at cortical, or more likely at subcortical/brainstem, level is more plausible.

Utilisation of prescription and over-the-counter triptans: a cross-sectional study in Stockholm, Sweden

PURPOSE

Triptans are widely used in acute migraine, and in some countries, they are also available over-the-counter (OTC). In Sweden, sales have increased for both prescription and OTC triptans. This study aimed to describe current prescribing and utilisation patterns of prescription and OTC triptans in Stockholm, Sweden.

METHODS

Register data from 4759 patients dispensed triptans in 2014 were used to study documented diagnosis of migraine, concomitant acute and preventive treatment for migraine, and contraindications. Survey data from 49 patients purchasing OTC triptans in three pharmacies were used to capture physician-diagnosed migraine, concomitant acute and preventive treatment for migraine, a behaviour of combining or alternating between prescription and OTC triptans, and pharmacy counselling rates.

RESULTS

Among the prescription triptan users, 52 % had a recorded diagnosis of migraine, 48 % had no other acute treatment, preventive treatment was rare (12 %) and contraindications were found in 2 % of the patients. Among the OTC triptan users, the majority (63 %) had been diagnosed by a physician and had a history of prescription triptan use, but combining or alternating between OTC and prescription triptans was rare. Concomitant acute treatment was reported in 53 % and preventive treatment was rare (4 %), despite high self-reported migraine frequencies. Some off-label use was detected, despite moderate to high counselling rates.

CONCLUSION

Triptans are prescribed with attention to safety but with poor recording of migraine diagnosis. OTC triptan users generally have a history of prescription triptan use. Preventive treatment rates are low in both groups. Strategies to discern patients who need other treatment options should be considered.

Examination of fluctuations in atmospheric pressure related to migraine

Background

Japan has four seasons and many chances of low atmospheric pressure or approaches of typhoon, therefore it has been empirically known that the fluctuation of weather induces migraine in people. Generally, its mechanism has been interpreted as follows: physical loading, attributed by atmospheric pressure to human bodies, compresses or dilates human blood vessels, which leads to abnormality in blood flow and induces migraine. We report our examination of the stage in which migraine tends to be induced focusing on the variation of atmospheric pressure.

Findings

Subjects were 34 patients with migraine, who were treated in our hospital. The patients included 31 females and three males, whose mean age was 32 ± 6.7. 22 patients had migraine with aura and 12 patients had migraine without aura. All of patients with migraine maintained a headache diary to record atmospheric pressures when they developed a migraine. The standard atmospheric pressure was defined as 1013 hPa, and with this value as the criterion, we investigated slight fluctuations in the atmospheric pressure when they developed a migraine. It was found that the atmospheric pressure when the patients developed a migraine was within 1003–1007 hPa in the approach of low atmospheric pressure and that the patients developed a migraine when the atmospheric pressure decreased by 6–10 hPa, slightly less than the standard atmospheric pressure.

Conclusion

Small decreases of 6–10 hPa relative to the standard atmospheric pressure of 1013 hPa induced migraine attacks most frequently in patients with migraine.

Trigger factors in primary headaches subtypes: a cross-sectional study from a tertiary centre in Greece

Background

Previous studies have shown that common headache triggers contribute to the onset of headache attacks on predisposed individuals and are considered important in the prevention of headache. The aim of this study was to compare the different characteristics of triggers among the most common primary headache subtypes (migraine without aura, migraine with aura and tension type headache).

Methods

A total of 116 headache patients of the neurology outpatient department of a tertiary hospital in Athens were selected according to the criteria of the International Classification of Headaches—3nd Edition Beta. Patients were interviewed using a questionnaire that contained 35 potential trigger factors.

Results

The findings showed that migraine and tension-type headache patients report multiple triggers, on a frequent but variable basis. The most frequent triggers reported by all subjects were stressful life events followed by intense emotions. The same applies to both genders, as well as the three headache subgroups. Patients suffering from migraine with aura reported the highest mean number of trigger per person and the highest frequency in almost all the trigger categories. Furthermore, patients with migraine with aura were more likely to report the following triggers: oversleeping, premenstrual period, stressful life events, hot/cold weather, relaxation after stress, menstruation, wind, intense emotions, shining, hunger and bright sunlight. These associations were mostly independent of the sociodemographic characteristics and the presence of anxiety or depressive symptoms.

Conclusion

The sensitivity to trigger factors should be considered by both clinicians and headache sufferers.

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

Scientific evidence support the notion that migraine pathophysiology involves inherited alteration of brain excitability, intracranial arterial dilatation, recurrent activation and sensitization of the trigeminovascular pathway, and consequential structural and functional changes in genetically susceptible individuals. Evidence of altered brain excitability emerged from clinical and preclinical investigation of sensory auras, ictal and interictal hypersensitivity to visual, auditory and olfactory stimulation, and reduced activation of descending inhibitory pain pathways. Data supporting the activation and sensitization of the trigeminovascular system include the progressive development of cephalic and whole-body cutaneous allodynia during a migraine attack. Also, structural and functional alterations include the presence of subcortical white mater lesions, thickening of cortical areas involved in processing sensory information, and cortical neuroplastic changes induced by cortical spreading depression. Here, we review recent anatomical data on the trigeminovascular pathway and its activation by cortical spreading depression, a novel understanding of the neural substrate of migraine-type photophobia, and modulation of the trigeminovascular pathway by the brainstem, hypothalamus and cortex.

Sphenopalatine ganglion neuromodulation in migraine: what is the rationale?

OBJECTIVE

The objective of this article is to review the prospect of treating migraine with sphenopalatine ganglion (SPG) neurostimulation.

BACKGROUND

Fuelled by preliminary studies showing a beneficial effect in cluster headache patients, the potential of treating migraine with neurostimulation has gained increasing interest within recent years, as current treatment strategies often fail to provide adequate relief from this debilitating headache. Common migraine symptoms include lacrimation, nasal congestion, and conjunctival injection, all parasympathetic manifestations. In addition, studies have suggested that parasympathetic activity may also contribute to the pain of migraineurs. The SPG is the largest extracranial parasympathetic ganglion of the head, innervating the meninges, lacrimal gland, nasal mucosa, and conjunctiva, all structures involved in migraine with cephalic autonomic symptoms.

CONCLUSION

We propose two possible mechanisms of action: 1) interrupting the post-ganglionic parasympathetic outflow to inhibit the pain and cephalic autonomic symptoms, and 2) modulating the sensory processing in the trigeminal nucleus caudalis. To further explore SPG stimulation in migraineurs as regards therapeutic potential and mode of action, randomized clinical trials are warranted.

Headache and facial pain: differential diagnosis and treatment

Headaches affect 90% of the population sometime during their life. Most are benign and fleeting, some are serious and life-threatening, and others require ongoing medical consultation and treatment. A careful history and physical is necessary to establish a differential diagnosis and to guide the choice of testing to make an accurate diagnosis. The most common types of headaches are discussed in this review. They are divided into primary and secondary headache disorders as classified by the International Headache Society. Primary headache disorders include migraine without and with aura, cluster and tension-type headaches. Secondary headaches are those that occur as a result of some other disorder and include brain tumors, rhinosinusitis, diseases of intracranial and extracranial vasculature, and temporomandibular joint disease.

Is β endorphin related to migraine headache and its relief?

BACKGROUND

Low β endorphin level in serum and cerebrospinal fluid (CSF) has been reported in migraine. The basis of pain relief in migraine by repetitive transcranial magnetic stimulation (rTMS) may be related to β endorphin (BE), which has not been evaluated. It is proposed to measure plasma β endorphin level in migraine patients and the change in β endorphin level following rTMS, and to correlate these changes with migraine relief.

METHODS

Twenty-five patients with migraine diagnosed as per International Headache Society criteria and 20 gender- and age-matched controls were included. Their clinical characteristics including duration of migraine, its frequency, severity and functional disability, triggers, allodynia and number of analgesic used were noted. Plasma β endorphin level was estimated before and after the third rTMS session. rTMS was delivered on the hot spot of right abductor digiti minimi on alternate days for 3 days and each session consisted of 600 pulses at 10 Hz. The clinical response was noted weekly for 1 month and correlated with β endorphin level.

RESULTS

The median age of the patients was 35 (20-50) years and 19 were females. Eight patients had episodic and 17 chronic migraine. β endorphin level was significantly lower in migraine (4.35 ± 2.29 ng/ml) compared to controls (6.68 ± 2.93 ng/ml). β endorphin level was lower in chronic compared to episodic migraine (3.74 ± 2.20 versus 5.65 ± 2.02 ng/ml). Following rTMS, the headache frequency, severity, functional disability and analgesic intake significantly reduced on the seventh day of rTMS and remained significant until the fourth week compared to the baseline. The clinical improvement was associated with increase in β endorphin level (4.35 ± 2.29 versus 6.58 ± 3.33 ng/ml).

CONCLUSION

It can be concluded from this study that the basal plasma β endorphin level was low in migraine patients, especially in chronic migraine. The improvement in migraine after rTMS was associated with increase in β endorphin level.

How aware are migraineurs of their triggers?

BACKGROUND

Broad discrepancies in the number of migraine triggers have been reported in several studies. Migraineurs do not seem to recognize easily headache triggers in clinical practice.

OBJECTIVE

To evaluate how aware migraineurs are about their headache triggers.

MATERIALS AND METHODS

We recruited 120 consecutive migraineurs. Each patient was first asked to report spontaneously any migraine trigger. Subsequently, the patient selected from a list of commonly known triggers.

RESULTS

Ninety-seven patients (72.5%) spontaneously reported at least 1 migraine trigger, and 120 patients (100%) reported at least 1 migraine trigger selecting from a specific list of precipitants. The mean number of spontaneously identified triggers was 1.5 (±1.5), and the total number of triggers identified was 7.20 (±3.9).

CONCLUSIONS

A relevant discrepancy between the number of spontaneously recognized triggers and the total number of triggers was found. This may suggest that migraineurs display poor awareness about headache triggers.

Spontaneous trigeminal allodynia in rats: a model of primary headache

Animal models are essential for studying the pathophysiology of headache disorders and as a screening tool for new therapies. Most animal models modify a normal animal in an attempt to mimic migraine symptoms. They require manipulation to activate the trigeminal nerve or dural nociceptors. At best, they are models of secondary headache. No existing model can address the fundamental question: How is a primary headache spontaneously initiated? In the process of obtaining baseline periorbital von Frey thresholds in a wild-type Sprague-Dawley rat, we discovered a rat with spontaneous episodic trigeminal allodynia (manifested by episodically changing periorbital pain threshold). Subsequent mating showed that the trait is inherited. Animals with spontaneous trigeminal allodynia allow us to study the pathophysiology of primary recurrent headache disorders. To validate this as a model for migraine, we tested the effects of clinically proven acute and preventive migraine treatments on spontaneous changes in rat periorbital sensitivity. Sumatriptan, ketorolac, and dihydroergotamine temporarily reversed the low periorbital pain thresholds. Thirty days of chronic valproic acid treatment prevented spontaneous changes in trigeminal allodynia. After discontinuation, the rats returned to their baseline of spontaneous episodic threshold changes. We also tested the effects of known chemical human migraine triggers. On days when the rats did not have allodynia and showed normal periorbital von Frey thresholds, glycerol trinitrate and calcitonin gene related peptide induced significant decreases in the periorbital pain threshold. This model can be used as a predictive model for drug development and for studies of putative biomarkers for headache diagnosis and treatment.

The role of chemosensitive afferent nerves and TRP ion channels in the pathomechanism of headaches

The involvement of trigeminovascular afferent nerves in the pathomechanism of primary headaches is well established, but a pivotal role of a particular class of primary sensory neurons has not been advocated. This review focuses on the evidence that supports the critical involvement of transient receptor potential (TRP) channels in the pathophysiology of primary headaches, in particular, migraine. Transient receptor potential vanilloid 1 and transient receptor potential ankyrin 1 receptors sensitive to vanilloids and other irritants are localized on chemosensitive afferent nerves, and they are involved in meningeal nociceptive and vascular responses involving neurogenic dural vasodilatation and plasma extravasation. The concept of the trigeminal nocisensor complex is put forward which involves the trigeminal chemosensitive afferent fibers/neurons equipped with specific nocisensor molecules, the elements of the meningeal microcirculatory system, and the dural mast cells. It is suggested that the activation level of this complex may explain some of the specific features of migraine headache. Pharmacological modulation of TRP channel function may offer a novel approach to the management of head pain, in particular, migraine.

The young brain and concussion: imaging as a biomarker for diagnosis and prognosis

Concussion (mild traumatic brain injury (mTBI)) is a significant pediatric public health concern. Despite increased awareness, a comprehensive understanding of the acute and chronic effects of concussion on central nervous system structure and function remains incomplete. Here we review the definition, epidemiology, and sequelae of concussion within the developing brain, during childhood and adolescence, with current data derived from studies of pathophysiology and neuroimaging. These findings may contribute to a better understanding of the neurological consequences of traumatic brain injuries, which in turn, may lead to the development of brain biomarkers to improve identification, management and prognosis of pediatric patients suffering from concussion.

Nociceptive neuropeptide increases and periorbital allodynia in a model of traumatic brain injury

OBJECTIVE

This study tests the hypothesis that injury to the somatosensory cortex is associated with periorbital allodynia and increases in nociceptive neuropeptides in the brainstem in a mouse model of controlled cortical impact (CCI) injury.

METHODS

Male C57BL/6 mice received either CCI or craniotomy-only followed by weekly periorbital von Frey (mechanical) sensory testing for up to 28 days post-injury. Mice receiving an incision only and naïve mice were included as control groups. Changes in calcitonin gene-related peptide (CGRP) and substance P (SP) within the brainstem were determined using enzyme-linked immunosorbent assay and immunohistochemistry, respectively. Activation of ionized calcium-binding adaptor molecule-1-labeled macrophages/microglia and glial fibrillary acidic protein (GFAP)-positive astrocytes were evaluated using immunohistochemistry because of their potential involvement in nociceptor sensitization.

RESULTS

Incision-only control mice showed no changes from baseline periorbital von Frey mechanical thresholds. CCI significantly reduced mean periorbital von Frey thresholds (periorbital allodynia) compared with baseline and craniotomy-only at each endpoint, analysis of variance P < .0001. Craniotomy significantly reduced periorbital threshold at 14 days but not 7, 21, or 28 days compared with baseline threshold, P < .01. CCI significantly increased SP immunoreactivity in the brainstem at 7 and 14 days but not 28 days compared with craniotomy-only and controls, P < .001. CGRP levels in brainstem tissues were significantly increased in CCI groups compared with controls (incision-only and naïve mice) or craniotomy-only mice at each endpoint examined, P < .0001. There was a significant correlation between CGRP and periorbital allodynia (P < .0001, r = -0.65) but not for SP (r = 0.20). CCI significantly increased the number of macrophage/microglia in the injured cortex at each endpoint up to 28 days, although cell numbers declined over weeks post-injury, P < .001. GFAP(+) immunoreactivity was significantly increased at 7 but not 14 or 28 days after CCI, P < .001. Craniotomy resulted in transient periorbital allodynia accompanied by transient increases in SP, CGRP, and GFAP immunoreactivity compared with control mice. There was no increase in the number of macrophage/microglia cells compared with controls after craniotomy.

CONCLUSION

Injury to the somatosensory cortex results in persistent periorbital allodynia and increases in brainstem nociceptive neuropeptides. Findings suggest that persistent allodynia and increased neuropeptides are maintained by mechanisms other than activation of macrophage/microglia or astrocyte in the injured somatosensory cortex.

Where does a migraine attack originate? In the brainstem

Migraine is a common, paroxysmal, highly disabling primary headache disorder. The origin of migraine attacks is enigmatic. Numerous clinical and experimental results suggest that the activation of distinct brainstem nuclei is crucial in its pathogenesis, but the primary cause of this activation is not fully understood. We conclude that the initialization of a migraine attack can be explained as an altered function of the neuronal elements of the brainstem nuclei. In light of our findings and the literature data, we can assume that migraine is a subcortical disorder of a specific brainstem area.

CaV2.1 voltage activated calcium channels and synaptic transmission in familial hemiplegic migraine pathogenesis

Studies on the genetic forms of epilepsy, chronic pain, and migraine caused by mutations in ion channels have given crucial insights into the molecular mechanisms, pathogenesis, and therapeutic approaches to complex neurological disorders. In this review we focus on the role of mutated CaV2.1 (i.e., P/Q-type) voltage-activated Ca2+ channels, and on the ultimate consequences that mutations causing familial hemiplegic migraine type-1 (FHM1) have in neurotransmitter release. Transgenic mice harboring the human pathogenic FHM1 mutation R192Q or S218L (KI) have been used as models to study neurotransmission at several central and peripheral synapses. FHM1 KI mice are a powerful tool to explore presynaptic regulation associated with expression of CaV2.1 channels. Mutated CaV2.1 channels activate at more hyperpolarizing potentials and lead to a gain-of-function in synaptic transmission. This gain-of-function might underlie alterations in the excitatory/ inhibitory balance of synaptic transmission, favoring a persistent state of hyperexcitability in cortical neurons that would increase the susceptibility for cortical spreading depression (CSD), a mechanism believed to initiate the attacks of migraine with aura.

The prevalence of triggers in paediatric migraine: a questionnaire study in 102 children and adolescents

The prevalence and characterization of migraine triggers have not been rigorously studied in children and adolescents. Using a questionnaire, we retrospectively studied the prevalence of 15 predefined trigger factors in a clinic-based population. In 102 children and adolescents fulfilling the Second Edition of The International Headache Classification criteria for paediatric migraine, at least one migraine trigger was reported by the patient and/or was the parents’ interpretation in 100% of patients. The mean number of migraine triggers reported per subject was 7. Mean time elapsed between exposure to a trigger factor and attack onset was comprised between 0 and 3 h in 88 patients (86%). The most common individual trigger was stress (75.5% of patients), followed by lack of sleep (69.6%), warm climate (68.6%) and video games (64.7%). Stress was also the most frequently reported migraine trigger always associated with attacks (24.5%). In conclusion, trigger factors were frequently reported by children and adolescents with migraine and stress was the most frequent.

Effect of cortical spreading depression on basal and evoked traffic in the trigeminovascular sensory system

AIM

To use an animal model to test whether migraine pain arises peripherally or centrally.

METHODS

We monitored the spontaneous and evoked activity of second-order trigeminovascular neurons in rats to test whether traffic increased following a potential migraine trigger (cortical spreading depression, CSD) and by what mechanism any such change was mediated.

RESULTS

Neurons (n = 33) responded to stimulation of the dura mater and facial skin with A-δ latencies. They were spontaneously active with a discharge rate of 6.1 ± 6.4 discharges s(-1). Injection of 10 µg lignocaine into the trigeminal ganglion produced a fully reversible reduction of the spontaneous discharge rate of neurons. Neuronal discharge rate returned to normal by 90 min. Lignocaine reduced the evoked responses of neurons to dural stimulation to 37% and to facial skin stimulation to 53% of control. Induction of CSD by cortical injection of KCl increased the spontaneous discharge rate of neurons from 2.9 to 16.3 discharges s(-1) at 20 min post CSD. Injection of 10 µg lignocaine into the trigeminal ganglion at this time failed to arrest or reverse this increase. Injection of lignocaine prior to the initiation of CSD failed to prevent the subsequent development of CSD-induced increases in discharge rates.

CONCLUSIONS

These results suggest that there is a continuous baseline traffic in primary trigeminovascular fibres and that CSD does not act to increase this traffic by a peripheral action alone - rather, it must produce some of its effect by a mechanism intrinsic to the central nervous system. Thus the pain of migraine may not always be the result of peripheral sensory stimulation, but may also arise by a central mechanism.

Central nervous system mast cells in peripheral inflammatory nociception

BACKGROUND

Functional aspects of mast cell-neuronal interactions remain poorly understood. Mast cell activation and degranulation can result in the release of powerful pro-inflammatory mediators such as histamine and cytokines. Cerebral dural mast cells have been proposed to modulate meningeal nociceptor activity and be involved in migraine pathophysiology. Little is known about the functional role of spinal cord dural mast cells. In this study, we examine their potential involvement in nociception and synaptic plasticity in superficial spinal dorsal horn. Changes of lower spinal cord dura mast cells and their contribution to hyperalgesia are examined in animal models of peripheral neurogenic and non-neurogenic inflammation.

RESULTS

Spinal application of supernatant from activated cultured mast cells induces significant mechanical hyperalgesia and long-term potentiation (LTP) at spinal synapses of C-fibers. Lumbar, thoracic and thalamic preparations are then examined for mast cell number and degranulation status after intraplantar capsaicin and carrageenan. Intradermal capsaicin induces a significant percent increase of lumbar dural mast cells at 3 hours post-administration. Peripheral carrageenan in female rats significantly increases mast cell density in the lumbar dura, but not in thoracic dura or thalamus. Intrathecal administration of the mast cell stabilizer sodium cromoglycate or the spleen tyrosine kinase (Syk) inhibitor BAY-613606 reduce the increased percent degranulation and degranulated cell density of lumbar dural mast cells after capsaicin and carrageenan respectively, without affecting hyperalgesia.

CONCLUSION

The results suggest that lumbar dural mast cells may be sufficient but are not necessary for capsaicin or carrageenan-induced hyperalgesia.

TRPA1 receptors mediate environmental irritant-induced meningeal vasodilatation

The TRPA1 receptor is a member of the transient receptor potential (TRP) family of ion channels expressed in nociceptive neurons. TRPA1 receptors are targeted by pungent compounds from mustard and garlic and environmental irritants such as formaldehyde and acrolein. Ingestion or inhalation of these chemical agents causes irritation and burning in the nasal and oral mucosa and respiratory lining. Headaches have been widely reported to be induced by inhalation of environmental irritants, but it is unclear how these agents produce headache. Stimulation of trigeminal neurons releases CGRP and substance P and induces neurogenic inflammation associated with the pain of migraine. Here we test the hypothesis that activation of TRPA1 receptors is the mechanistic link between environmental irritants and peptide-mediated neurogenic inflammation. Known TRPA1 agonists and environmental irritants stimulate CGRP release from dissociated rat trigeminal ganglia neurons and this release is blocked by a selective TRPA1 antagonist, HC-030031. Further, TRPA1 agonists and environmental irritants increase meningeal blood flow following intranasal administration. Prior dural application of the CGRP antagonist, CGRP(8-37), or intranasal or dural administration of HC-030031, blocks the increases in blood flow elicited by environmental irritants. Together these results demonstrate that TRPA1 receptor activation by environmental irritants stimulates CGRP release and increases cerebral blood flow. We suggest that these events contribute to headache associated with environmental irritants.

An analysis of migraine triggers in a clinic-based population

BACKGROUND

Many migraineurs report attack "triggers," but relatively few published data exist regarding the relative prevalences of individual triggers, variations related to gender, duration of migraine or migraine subtype, or the existence of any regional variations in the prevalences and distributions of triggers.

OBJECTIVE

We sought to determine the prevalence and types of migraine triggers in our clinic population, to determine what influence gender, migraine subtype, or duration of migraine might have on the prevalences and types of triggers reported and to compare our findings with data derived from surveys we previously had conducted involving 2 clinic-based populations and 1 general population sample from other regions of the USA.

METHODS

We evaluated 200 consecutive new migraine patients referred to our clinic. All patients specifically were queried as to whether they had noted any of 7 specific factors to serve consistently as migraine attack triggers and additionally were surveyed as to whether they might have "other" triggers not listed on the intake questionnaire. Among the other data collected and analyzed were age, gender, age at time of migraine onset, and migraine subtype (ie, episodic vs chronic). Actively cycling females who reported menses as a trigger were questioned as to whether their menstrual migraine (MM) attacks differed from their non-menstrual migraines and, if so, how they differed.

RESULTS

One hundred and eighty-two patients (91%) reported at least 1 migraine trigger, and 165 (82.5%) reported multiple triggers. The most common trigger reported (59%) was "emotional stress," followed by "too much or little sleep" (53.5%), "odors" (46.5%), and "missing meals" (39%). Females or subjects of either gender with chronic migraine were no more likely than males or subjects with episodic migraine to report triggers or multiple triggers. Similarly, longer exposure to migraine did not correlate with a higher likelihood of reporting a trigger or multiple triggers. Fifty-three (62%) of 85 actively cycling females reported menses as a trigger, and of the 51 with menstrually related migraine, 34 (67%) reported their MM to be more severe, more refractory to symptomatic therapy or of longer duration than their non-menstrual attacks; 13 (24.5%) of the 53 women with apparent MM reported their MM to be at least occasionally manifested as status migrainosus. The prevalence and type of triggers reported by this predominantly white female population were similar to those reported by clinic-based populations in San Diego, California and Mobile, Alabama, and in a population-based sample of Hispanics in San Diego County.

CONCLUSIONS

A large majority of migraineurs report migraine attack triggers, and the triggers most commonly reported include emotional stress, a disrupted sleep pattern, and various odors. These findings do not appear to vary according to geographic region or race/ethnicity. Among the triggers, MM appears inclined to provoke headache that is more severe, less amenable to treatment, or longer in duration than headaches that occur at other times during the cycle.

Insights into migraine mechanisms and CaV2.1 calcium channel function from mouse models of familial hemiplegic migraine

Migraine is a very common disabling brain disorder with unclear pathogenesis. A subtype of migraine with aura (familial hemiplegic migraine type 1: FHM1) is caused by mutations in CaV2.1 (P/Q-type) Ca2+ channels. This review describes the functional consequences of FHM1 mutations in knockin mouse models carrying the mild R192Q or severe S218L mutations in the orthologous gene. The FHM1 knockin mice show allele dosage-dependent gain-of-function of neuronal P/Q-type Ca2+ current, reflecting activation of mutant channels at lower voltages, and allele dosage- and sex-dependent facilitation of induction and propagation of cortical spreading depression (CSD), the phenomenon that underlies migraine aura. Gain-of-function of neuronal Ca2+ current, facilitation of CSD and post-CSD motor deficits were larger in S218L than R192Q knockin mice, in correlation with the more severe human S218L phenotype. Enhanced cortical excitatory neurotransmission, due to increased action potential-evoked Ca2+ influx and increased probability of glutamate release at pyramidal cell synapses, but unaltered inhibitory neurotransmission at fast-spiking interneuron synapses, were demonstrated in R192Q knockin mice. Evidence for a causative link between enhanced glutamate release and CSD facilitation was obtained. The data from FHM1 mice strengthen the view of CSD as a key player in the pathogenesis of migraine, give insight into CSD mechanisms and point to episodic disruption of excitation-inhibition balance and neuronal hyperactivity as the basis for vulnerability to CSD ignition in migraine.