Endocannabinoids in platelets of chronic migraine patients and medication-overuse headache patients: relation with serotonin levels

Effects of Fremanezumab on Psychiatric Comorbidities in Difficult-to-Treat Patients with Chronic Migraine: Post Hoc Analysis of a Prospective, Multicenter, Real-World Greek Registry

OBJECTIVE

this post hoc analysis aimed to evaluate the efficacy of fremanezumab in difficult-to-treat chronic migraine (CM) patients with and without psychiatric comorbidities (PCs), mainly anxiety and/or depression.

METHODS

We assessed data from CM patients with and without PCs who failed at least 3 preventives and eventually received at least 3 consecutive monthly doses of fremanezumab 225 mg. Outcomes included the crude response (≥50% reduction in monthly headache days (MHDs)) rates to fremanezumab from the baseline to the last clinical follow-up. The changes in MHDs; MHDs of moderate/greater severity; monthly days with intake of abortive medication; and the proportion of patients' changing status from with PCs to decreased/without PCs were also compared. Disability and quality of life (QOL) outcomes were also assessed.

RESULTS

Of 107 patients enrolled, 65 (60.7%) had baseline PCs. The percentage of patients with (n = 38/65; 58.5%) and without (n = 28/42; 66.6%) PCs that achieved a ≥50% reduction in MHDs with fremanezumab was comparable (p = 0.41), whereas MHDs were significantly reduced (difference vs. baseline) in both patients with PCs (mean -8.9 (standard error: 6.8); p < 0.001) and without PCs (-9.8 (7.5); p < 0.001). Both groups experienced significant improvements in all other efficacy, disability, and QOL outcomes at comparable rates, including in MHD reduction. A significant proportion of fremanezumab-treated patients with baseline PCs de-escalated in corresponding severities or even reverted to no PCs (28/65; 43.1%) post-fremanezumab.

CONCLUSIONS

fremanezumab appears to be effective as a preventive treatment in difficult-to-treat CM patients with and without PCs while also being beneficial in reducing the severity of comorbid anxiety and/or depression.

Biomarkers of Migraine: An Integrated Evaluation of Preclinical and Clinical Findings

In recent years, numerous efforts have been made to identify reliable biomarkers useful in migraine diagnosis and progression or associated with the response to a specific treatment. The purpose of this review is to summarize the alleged diagnostic and therapeutic migraine biomarkers found in biofluids and to discuss their role in the pathogenesis of the disease. We included the most informative data from clinical or preclinical studies, with a particular emphasis on calcitonin gene-related peptide (CGRP), cytokines, endocannabinoids, and other biomolecules, the majority of which are related to the inflammatory aspects and mechanisms of migraine, as well as other actors that play a role in the disease. The potential issues affecting biomarker analysis are also discussed, such as how to deal with bias and confounding data. CGRP and other biological factors associated with the trigeminovascular system may offer intriguing and novel precision medicine opportunities, although the biological stability of the samples used, as well as the effects of the confounding role of age, gender, diet, and metabolic factors should be considered.

Exploring Novel Therapeutic Targets in the Common Pathogenic Factors in Migraine and Neuropathic Pain

Migraine and neuropathic pain (NP) are both painful, disabling, chronic conditions which exhibit some symptom similarities and are thus considered to share a common etiology. The calcitonin gene-related peptide (CGRP) has gained credit as a target for migraine management; nevertheless, the efficacy and the applicability of CGRP modifiers warrant the search for more effective therapeutic targets for pain management. This scoping review focuses on human studies of common pathogenic factors in migraine and NP, with reference to available preclinical evidence to explore potential novel therapeutic targets. CGRP inhibitors and monoclonal antibodies alleviate inflammation in the meninges; targeting transient receptor potential (TRP) ion channels may help prevent the release of nociceptive substances, and modifying the endocannabinoid system may open a path toward discovery of novel analgesics. There may exist a potential target in the tryptophan-kynurenine (KYN) metabolic system, which is closely linked to glutamate-induced hyperexcitability; alleviating neuroinflammation may complement a pain-relieving armamentarium, and modifying microglial excitation, which is observed in both conditions, may be a possible approach. Those are several potential analgesic targets which deserve to be explored in search of novel analgesics; however, much evidence remains missing. This review highlights the need for more studies on CGRP modifiers for subtypes, the discovery of TRP and endocannabinoid modulators, knowledge of the status of KYN metabolites, the consensus on cytokines and sampling, and biomarkers for microglial function, in search of innovative pain management methods for migraine and NP.

Preclinical Studies of Posttraumatic Headache and the Potential Therapeutics

Posttraumatic headache (PTH) attributed to traumatic brain injury (TBI) is a secondary headache developed within 7 days after head injury, and in a substantial number of patients PTH becomes chronic and lasts for more than 3 months. Current medications are almost entirely relied on the treatment of primary headache such as migraine, due to its migraine-like phenotype and the limited understanding on the PTH pathogenic mechanisms. To this end, increasing preclinical studies have been conducted in the last decade. We focus in this review on the trigeminovascular system from the animal studies since it provides the primary nociceptive sensory afferents innervating the head and face region, and the pathological changes in the trigeminal pathway are thought to play a key role in the development of PTH. In addition to the pathologies, PTH-like behaviors induced by TBI and further exacerbated by nitroglycerin, a general headache inducer through vasodilation are reviewed. We will overview the current pharmacotherapies including calcitonin gene-related peptide (CGRP) monoclonal antibody and sumatriptan in the PTH animal models. Given that modulation of the endocannabinoid (eCB) system has been well-documented in the treatment of migraine and TBI, the therapeutic potential of eCB in PTH will also be discussed.

Exploring the Tryptophan Metabolic Pathways in Migraine-Related Mechanisms

Migraine is a complex neurovascular disorder, which causes intense socioeconomic problems worldwide. The pathophysiology of disease is enigmatic; accordingly, therapy is not sufficient. In recent years, migraine research focused on tryptophan, which is metabolized via two main pathways, the serotonin and kynurenine pathways, both of which produce neuroactive molecules that influence pain processing and stress response by disturbing neural and brain hypersensitivity and by interacting with molecules that control vascular and inflammatory actions. Serotonin has a role in trigeminal pain processing, and melatonin, which is another product of this pathway, also has a role in these processes. One of the end products of the kynurenine pathway is kynurenic acid (KYNA), which can decrease the overexpression of migraine-related neuropeptides in experimental conditions. However, the ability of KYNA to cross the blood-brain barrier is minimal, necessitating the development of synthetic analogs with potentially better pharmacokinetic properties to exploit its therapeutic potential. This review summarizes the main translational and clinical findings on tryptophan metabolism and certain neuropeptides, as well as therapeutic options that may be useful in the prevention and treatment of migraine.

Enxaqueca de alta frequência refratária a tratamento farmacológico usual e anticorpo e responsiva a canabidiol de amplo espectro: relato de caso

O uso de derivados da Cannabis sp. no tratamento de certas condições médicas, como dor neuropática, epilepsia e esclerose múltipla já é bem conhecido. Porém, estudos sobre seu benefício em cefaleias ainda são de baixa abrangência, sendo constituídos, em sua maior parte, por relatos e séries de casos. Apresentamos o caso de paciente masculino de 74 anos, portador de enxaqueca de alta frequência (2 a 3 vezes/semana) há vários anos, com importante limitação funcional associada a diversos gatilhos, fazendo uso apenas de triptanos durante as crises. Apresentou intolerância a 2 medicamentos profiláticos (topiramato e propranolol). Realizou 2 aplicações de Erenumabe 70 mg, havendo considerável melhora inicial seguida de novo aumento na frequência das crises após a segunda aplicação, com interrupção do tratamento. Fez uso de nutracêuticos por 6 meses, sem grande melhora. Após introdução de óleo de canabidiol, as crises reduziram em frequência (1 episódio/mês) e intensidade, com intervalo recorde de 30 dias seguidos sem dor, associado a eliminação de gatilhos. Estudos pré-clínicos avaliando a relação entre o sistema endocanabinoide e a fisiopatologia da migrânea apontam para os derivados da Cannabis sp. como potenciais armas para o tratamento dessa condição. No entanto, o papel desses derivados como profilaxia das crises de enxaqueca ainda é especulativo, necessitando de estudos controlados para maior definição.

Clinical Evidence of Cannabinoids in Migraine: A Narrative Review

The endocannabinoid system (ECS) influences many biological functions, and hence, its pharmacological modulation may be useful for several disorders, such as migraine. Preclinical studies have demonstrated that the ECS is involved in the modulation of trigeminal excitability. Additionally, clinical data have suggested that an endocannabinoid deficiency is associated with migraine. Given these data, phytocannabinoids, as well as synthetic cannabinoids, have been tried as migraine treatments. In this narrative review, the current clinical evidence of potential ECS involvement in migraine pathogenesis is summarized. Furthermore, studies exploring the clinical effects of phytocannabinoids and synthetic cannabinoids on migraine patients are reviewed.

The endocannabinoid system and related lipids as potential targets for the treatment of migraine-related pain

BACKGROUND

Migraine is a complex and highly disabling neurological disease whose treatment remains challenging in many patients, even after the recent advent of the first specific-preventive drugs, namely monoclonal antibodies that target calcitonin gene-related peptide. For this reason, headache researchers are actively searching for new therapeutic targets. Cannabis has been proposed for migraine treatment, but controlled clinical studies are lacking. A major advance in cannabinoid research has been the discovery of the endocannabinoid system (ECS), which consists of receptors CB1 and CB2; their endogenous ligands, such as N-arachidonoylethanolamine; and the enzymes that catalyze endocannabinoid biosynthesis or degradation. Preclinical and clinical findings suggest a possible role for endocannabinoids and related lipids, such as palmitoylethanolamide (PEA), in migraine-related pain treatment. In animal models of migraine-related pain, endocannabinoid tone modulation via inhibition of endocannabinoid-catabolizing enzymes has been a particular focus of research.

METHODS

To conduct a narrative review of available data on the possible effects of cannabis, endocannabinoids, and other lipids in migraine-related pain, relevant key words were used to search the PubMed/MEDLINE database for basic and clinical studies.

RESULTS

Endocannabinoids and PEA seem to reduce trigeminal nociception by interacting with many pathways associated with migraine, suggesting a potential synergistic or similar effect.

CONCLUSIONS

Modulation of the metabolic pathways of the ECS may be a basis for new migraine treatments. The multiplicity of options and the wealth of data already obtained in animal models underscore the importance of further advancing research in this area. Multiple molecules related to the ECS or to allosteric modulation of CB1 receptors have emerged as potential therapeutic targets in migraine-related pain. The complexity of the ECS calls for accurate biochemical and pharmacological characterization of any new compounds undergoing testing and development.

Expression of Selected microRNAs in Migraine: A New Class of Possible Biomarkers of Disease?

Preliminary but convergent findings suggest a role for microRNAs (miRNAs) in the generation and maintenance of chronic pain and migraine. Initial observations showed that serum levels of miR-382-5p and miR-34a-5p expression were increased in serum during the migraine attack, with miR-382-5p increasing in the interictal phase as well. By contrast, miR-30a-5p levels were lower in migraine patients compared to healthy controls. Of note, antimigraine treatments proved to be capable of influencing the expression of these miRNAs. Altogether, these observations suggest that miRNAs may represent migraine biomarkers, but several points are yet to be elucidated. A major concern is that these miRNAs are altered in a broad spectrum of painful and non-painful conditions, and thus it is not possible to consider them as truly “migraine-specific” biomarkers. We feel that these miRNAs may represent useful tools to uncover and define different phenotypes across the migraine spectrum with different treatment susceptibilities and clinical features, although further studies are needed to confirm our hypothesis. In this narrative review we provide an update and a critical analysis of available data on miRNAs and migraines in order to propose possible interpretations. Our main objective is to stimulate research in an area that holds promise when it comes to providing reliable biomarkers for theoretical and practical scientific advances.

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.

Genetic overlap and causality between blood metabolites and migraine

The availability of genome-wide association studies (GWASs) for human blood metabolome provides an excellent opportunity for studying metabolism in a heritable disease such as migraine. Utilizing GWAS summary statistics, we conduct comprehensive pairwise genetic analyses to estimate polygenic genetic overlap and causality between 316 unique blood metabolite levels and migraine risk. We find significant genome-wide genetic overlap between migraine and 44 metabolites, mostly lipid and organic acid metabolic traits (FDR < 0.05). We also identify 36 metabolites, mostly related to lipoproteins, that have shared genetic influences with migraine at eight independent genomic loci (posterior probability > 0.9) across chromosomes 3, 5, 6, 9, and 16. The observed relationships between genetic factors influencing blood metabolite levels and genetic risk for migraine suggest an alteration of metabolite levels in individuals with migraine. Our analyses suggest higher levels of fatty acids, except docosahexaenoic acid (DHA), a very long-chain omega-3, in individuals with migraine. Consistently, we found a causally protective role for a longer length of fatty acids against migraine. We also identified a causal effect for a higher level of a lysophosphatidylethanolamine, LPE(20:4), on migraine, thus introducing LPE(20:4) as a potential therapeutic target for migraine.

A Bidirectional View of Migraine and Diet Relationship

Migraine is a common headache with a large negative impact on health. Several endogenous and exogenous factors can influence the severity and frequency of migraine, for example, lifestyle factors including dietary factors. Consequently, lifestyle modifications and dietary considerations have been reported beneficial to moderate clinical features of migraine. Much effort has been invested in determining the lifestyle factors (eg, stress, exercise, sleep, and diet) that trigger migraine to develop recommendations and guidelines for prevention. Diet has also been investigated with a major focus on the content of the diet and to a lesser extent on the amount, pattern, and quality of diet. Identification of dietary factors in migraine has led to nutritional interventions with a major focus on elimination of triggers, and weight control strategies. Several so-called migraine diets have consequently been proposed, for example, the ketogenic diet. Some theories have considered epigenetic diets or functional food to help in altering components of migraine pathogenesis; however, these theories are less investigated. In contrast, evidence is being accumulated to support that some mechanisms underlying migraine may alter dietary choices, for example type, amount, or patterns. Since a causative relationship is not yet established in migraine-diet relationship as to which comes first, this concept is equally valuable and interesting to investigate. Only limited epidemiological data are available to demonstrate that dietary choices are different among patients with migraine compared with individuals without migraine. Differences are reflected on quality, composition, pattern, and the amount of consumption of dietary components. This view emphasizes a potential bidirectional relationship between migraine and diet rather than a one-way influence of one on the other. This targeted review presents examples from current literature on the effects of diet on migraine features and effects of migraine on dietary choices to draw a perspective for future studies.

Experience of migraine, its severity, and perceived efficacy of treatments among cannabis users

OBJECTIVES

As the legal and cultural landscape surrounding cannabis use in the United States continues to evolve, more Americans are turning to cannabis to self-medicate a number of ailments, including migraines. The purpose of the present study was to examine patterns of cannabis use and its associated relief among migraineurs.

DESIGN

Participants were N = 589 adult cannabis users living in states with full legal access. Using a cross-sectional design, participants completed an online survey assessing their cannabis use profiles, migraine experience, and self-reported relief from cannabis and non-cannabis treatments.

RESULTS

161 participants (27.3 %) reported experiencing migraines. 76.4 % of migraineurs (N = 123) endorsed using cannabis to treat their migraines. 69.9 % (N = 86) of migraineurs using cannabis for migraine relief also endorsed using non-cannabis products (e.g., over-the-counter pain medication, triptans) to treat their migraines. Although their subjective health was similar (p = .17), migraineurs who endorsed using cannabis to treat their migraines reported more severe migraines compared to those who did not (p = .02). Migraineurs reported significantly more migraine relief from cannabis compared to non-cannabis products, even after controlling for migraine severity (p = .03). The majority of migraineurs using cannabis to treat their migraines were not medical cardholders (65.0 %), suggesting that these individuals were self-medicating in lieu of physician guidance.

CONCLUSIONS

The present study provides insight into the prevalence of cannabis use for migraine relief in a sample of cannabis users, and suggests that these migraineurs experience a high level of migraine relief from cannabis. Future studies are needed to determine the cannabis forms, potencies, and dosages that are most effective at treating migraine pain.

Medication Overuse Withdrawal in Children and Adolescents Does Not Always Improve Headache: A Cross-Sectional Study

Background: MOH can be diagnosed in subjects with headache occurring 15 days/month in association with a regular medication overuse, but its existence is not universally accepted. ICHD-3 redefined criteria for MOH, removing the criterion associating drug suspension with headache course. The aim of our study was to compare the rate of patients diagnosed with medication overuse headache (MOH) according to ICHD-2 and ICHD-3 criteria, to verify the degree of concordance. The secondary aim was to verify if drug withdrawal was really associated with pain relief. Methods: In this cross-sectional study, we retrospectively analyzed a sample of 400 patients followed for primary chronic headache at the Headache Center of Bambino Gesù Children's Hospital. We then selected those presenting with a history of medication overuse, and we applied both ICHD-2 and ICHD-3 criteria to verify in which patients the criteria would identify a clinical diagnosis of MOH. Results: We identified 42 subjects (10.5%) with MOH; 23 of them (55%) presented a relief of headache withdrawing drug overuse. Regarding the applicability of the ICHD-2 criteria, 43% of patients (18/42) fulfilled all criteria, while all ICHD-3 diagnostic criteria were satisfied in 76% of patients (32/42). Eighteen patients (43%) satisfied both ICHD-2 and ICHD-3 criteria, while 10 patients (24%) did not satisfy either diagnostic criterion. Conclusions: Our study suggests that in children and adolescents, withdrawing medication overuse is not always associated with a clinical benefit. Therefore, though allowing a MOH diagnosis in a higher rate of patients as compared to ICHD-2, the application of ICHD-3 criteria does not guarantee a true a causal relationship between medication overuse and headache worsening.

Peripheral changes of endocannabinoid system components in episodic and chronic migraine patients: A pilot study

BACKGROUND

Preclinical and clinical evidence suggests a role for the dysregulation of the endocannabinoid system in migraine pain, particularly in subjects with chronic migraine.

METHODS

The gene expression of endocannabinoid system components was assayed in peripheral blood mononuclear cells of 25 subjects with episodic migraine, 26 subjects with chronic migraine with medication overuse (CM-MO) and 24 age-matched healthy controls. We also evaluated the protein expression of cannabinoid receptors 1 and 2 as well as DNA methylation changes in genes involved in endocannabinoid system components.

RESULTS

Both episodic migraine and CM-MO subjects showed higher cannabinoid receptor 1 and cannabinoid receptor 2 gene and protein expression compared to controls. Fatty acid amide hydrolase gene expression, involved in anandamide degradation, was lower in migraine groups compared to healthy control subjects. N-arachidonoyl phosphatidylethanolamine phospholipase D gene expression was significantly higher in all migraineurs, as were monoacylglycerol lipase and diacylglycerol lipase gene expressions. The above markers significantly correlated with the number of migraine days and with the days of acute drug intake.

CONCLUSION

The findings point to transcriptional changes in endocannabinoid system components occurring in migraineurs. These changes were detected peripherally, which make them amenable for a wider adoption to further investigate their role and applicability in the clinical field.clinicaltrials.gov NTC04324710.

The Role of the Kynurenine Signaling Pathway in Different Chronic Pain Conditions and Potential Use of Therapeutic Agents

Tryptophan (TRP) is an essential, aromatic amino acid catabolized by indoleamine 2,3-dioxygenase (IDO) and tryptophan 2,3-dioxygenase (TDO) enzymes into kynurenine. The IDO enzyme is expressed in peripheral tissues and the central nervous system. Another enzyme of interest in the kynurenine signaling pathway is kynurenine 3-monooxygenase (KMO). The purpose of this review is to discuss the role of TRP and the kynurenine signaling pathway in different chronic pain patients. The IDO-1, IDO-2, and KMO enzymes and the kynurenine metabolite have been shown to be involved in the pathogenesis of neuropathic pain and other painful conditions (migraine, cluster headache, etc.) as well as depressive behavior. We highlighted the analgesic potential of novel agents targeting the enzymes of the kynurenine signaling pathway to explore their efficacy in both future basic science and transitional studies. Upcoming studies conducted on animal models will need to take into consideration the differences in TRP metabolism between human and non-human species. Since chronic painful conditions and depression have common pathophysiological patterns, and the kynurenine signaling pathway is involved in both of them, future clinical studies should aim to have outcomes targeting not only pain, but also functionality, mood changes, and quality of life.

What is Needed for Evidence-Based Dietary Recommendations for Migraine: A Call to Action for Nutrition and Microbiome Research

BACKGROUND

The gastrointestinal symptoms of migraine attacks have invited numerous dietary hypotheses for migraine etiology through the centuries. Substantial efforts have been dedicated to identifying dietary interventions for migraine attack prevention, with limited success. Meanwhile, mounting evidence suggests that the reverse relationship may also exist - that the biological mechanisms of migraine may influence dietary intake. More likely, the truth involves some combination of both, where the disease influences food intake, and the foods eaten impact the manifestations of the disease. In addition, the gut's microbiota is increasingly suspected to influence the migraine brain via the gut-brain axis, though these hypotheses remain largely unsubstantiated.

OBJECTIVE

This paper presents an overview of the strength of existing evidence for food-based dietary interventions for migraine, noting that there is frequently evidence to suggest that a dietary risk factor for migraine exists but no evidence for how to best intervene; in fact, our intuitive assumptions on interventions are being challenged with new evidence. We then look to the future for promising avenues of research, notably the gut microbiome.

CONCLUSION

The evidence supports a call to action for high-quality dietary and microbiome research in migraine, both to substantiate hypothesized relationships and build the evidence base regarding nutrition's potential impact on migraine attack prevention and treatment.

Anandamide Is Related to Clinical and Cardiorespiratory Benefits of Aerobic Exercise Training in Migraine Patients: A Randomized Controlled Clinical Trial

Introduction: Since endocannabinoids have been implicated in migraine pathophysiology, we conducted a randomized, controlled clinical trial to test the effects of a 12-week aerobic exercise intervention on plasma anandamide (AEA) and its relation with clinical, psychological, and cardiorespiratory outcomes. Materials and Methods: Episodic migraine patients taking no preventive drugs and nonheadache individuals were recruited from Hospital São Paulo and a tertiary headache clinic between March 2012 and March 2015. Participants were randomly assigned to receive aerobic exercise or enter the waitlist. Primary outcome was changes in plasma AEA; secondary outcome was number of days with migraine/month; and other clinical variables, mood scores, and cardiorespiratory fitness were chosen as tertiary outcomes. Measurements were taken on headache-free days. Data were analyzed by generalized linear models. Discussion: Fifty participants concluded the study (mean±SD age=36.2±10.9, and BMI=26.5±4.5). The plasma AEA reduced in migraine exercise (p<0.05) and control exercise groups (p<0.01). The number of days with migraine (p<0.01), migraine attacks (p<0.05), and abortive medication used (p<0.05) reduced in the migraine exercise group, whereas cardiorespiratory fitness increased in migraine exercise and control exercise groups (both p<0.05). Anxiety, depression, anger, and fatigue scores improved in the migraine exercise group (p<0.05 for all). Significant correlations between reduction in abortive medication used and cardiorespiratory fitness (r=-0.81 p<0.001), and reduced AEA (r=0.68 p<0.05) were found. Conclusions: This study suggests that peripheral AEA metabolism may be partly linked to the clinical and cardiorespiratory benefits of regular aerobic exercise in migraine patients. Trials registration: #NCT01972607.

Chronic Headache Due to Overuse of Analgesics and Anti-Migraine Agents

BACKGROUND

The frequent or regular use of analgesics and anti-migraine drugs can make headache more frequent and induce the transformation of episodic to chronic headache. Chronic headache due to medication overuse is defined as headache that is present on ≥ 15 days per month for at least three months in a patient who previously suffered from primary headaches, and who takes analgesics on ≥ 15 days per month or anti-migraine drugs (triptans or ergot alkaloids), opioid drugs, or combined analgesics on ≥ 10 days per month.

METHODS

This review is based on pertinent articles published up to December 2017 that were retrieved by a selective search in PubMed employing the terms "medication overuse AND headache" and "medication overuse headache."

RESULTS

The prevalence of medication overuse headache in the general population in Germany is 0.7% -1%. This disorder is more common in women and in persons suffering from comorbid mental disorders or other painful conditions. The treatment of medication overuse headache consists of three steps. Patient education and counseling are given with the goal of reducing the intake of medication for acute headache treatment. The ensuing headache prophylaxis is with topiramate, amitriptyline, or onabotulinum toxin A. If these treatment strategies fail, a drug holiday is recommended. This can be in the outpatient, day clinic, or inpatient setting, depending on the severity of the condition and its comorbidities.

CONCLUSION

Patients who frequently take acute medication to treat headache episodes must be identified early in order to avoid headache chronification and medication overuse headache. The suggested treatment algorithm is still in need of validation by randomized trials.

Endocannabinoid System and Migraine Pain: An Update

The trigeminovascular system (TS) activation and the vasoactive release from trigeminal endings, in proximity of the meningeal vessels, are considered two of the main effector mechanisms of migraine attacks. Several other structures and mediators are involved, however, both upstream and alongside the TS. Among these, the endocannabinoid system (ES) has recently attracted considerable attention. Experimental and clinical data suggest indeed a link between dysregulation of this signaling complex and migraine headache. Clinical observations, in particular, show that the levels of anandamide (AEA)—one of the two primary endocannabinoid lipids—are reduced in cerebrospinal fluid and plasma of patients with chronic migraine (CM), and that this reduction is associated with pain facilitation in the spinal cord. AEA is produced on demand during inflammatory conditions and exerts most of its effects by acting on cannabinoid (CB) receptors. AEA is rapidly degraded by fatty acid amide hydrolase (FAAH) enzyme and its levels can be modulated in the peripheral and central nervous system (CNS) by FAAH inhibitors. Inhibition of AEA degradation via FAAH is a promising therapeutic target for migraine pain, since it is presumably associated to an increased availability of the endocannabinoid, specifically at the site where its formation is stimulated (e.g., trigeminal ganglion and/or meninges), thus prolonging its action.

Chronic migraine: A process of dysmodulation and sensitization

Chronic migraine is a common chronic daily headache featured by frequent headache attacks with at least 15 headache days per month, which brings great disease burden to both the sufferers and the society. Transformed from episodic migraine, the pathophysiology of chronic migraine is not fully understood, even though several risk factors have been associated with migraine progression. Recent studies have identified both structural and functional alterations in some brain regions of chronic migraine patients indicating that maladaptation of the top-down pain modulation and subsequent sensitization of trigeminal system may be important in the pathogenesis of chronic migraine. Moreover, biochemical analysis has confirmed several molecules related to chronic migraine, which may serve as biomarkers and potential therapeutic targets. Chronic migraine is undertreated because of its poor treatment response and limited therapy options. In this article, we reviewed the latest data to outline the clinical feature, pathophysiological mechanism, and management of chronic migraine, in the expectation to provide direction for future research and finally to take good care of chronic migraine patients.

Inhibition of monoacylglycerol lipase: Another signalling pathway for potential therapeutic targets in migraine?

Background

Drugs that modulate endocannabinoid signalling are effective in reducing nociception in animal models of pain and may be of value in the treatment of migraine.

Methods

We investigated the anti-nociceptive effects of inhibition of monoacylglycerol lipase (MGL), a key enzyme in the hydrolysis of the 2-arachidonoylglycerol, in a rat model of migraine based on nitroglycerin (NTG) administration. We evaluated c-fos expression in specific brain areas and nociceptive behavior in trigeminal and extra-trigeminal body areas.

Results

URB602, a reversible MGL inhibitor, did not show any analgesic effect in the tail flick test, but it inhibited NTG-induced hyperalgesia in both the tail flick test and the formalin test applied to the hind paw or to the orofacial area. Quite unexpectedly, URB602 potentiated formalin-induced hyperalgesia in the trigeminal area when used alone. The latter result was also confirmed using a structurally distinct, irreversible MGL inhibitor, JZL184. URB602 did not induce neuronal activation in the area of interest, but significantly reduced the NTG-induced neuronal activation in the ventrolateral column of the periaqueductal grey and the nucleus trigeminalis caudalis.

Conclusions

These findings support the hypothesis that modulation of the endocannabinoid system may be a valuable approach for the treatment of migraine. The topographically segregated effect of MGL inhibition in trigeminal/extra-trigeminal areas calls for further mechanistic research.

Interactions between the Kynurenine and the Endocannabinoid System with Special Emphasis on Migraine

Both the kynurenine and the endocannabinoid systems are involved in several neurological disorders, such as migraine and there are increasing number of reports demonstrating that there are interactions of two systems. Although their cooperation has not yet been implicated in migraine, there are reports suggesting this possibility. Additionally, the individual role of the endocannabinoid and kynurenine system in migraine is reviewed here first, focusing on endocannabinoids, kynurenine metabolites, in particular kynurenic acid. Finally, the function of NMDA and cannabinoid receptors in the trigeminal system-which has a crucial role in the pathomechanisms of migraine-will also be discussed. The interaction of the endocannabinoid and kynurenine system has been demonstrated to be therapeutically relevant in a number of pathological conditions, such as cannabis addiction, psychosis, schizophrenia and epilepsy. Accordingly, the cross-talk of these two systems may imply potential mechanisms related to migraine, and may offer new approaches to manage the treatment of this neurological disorder.

Plasma levels of the endocannabinoid anandamide, related N-acylethanolamines and linoleic acid-derived oxylipins in patients with migraine

There is evidence that patients with migraine have deficient levels of the endogenous cannabinoid receptor ligand anandamide (AEA). It is not known, however, if this is a localised or generalised phenomenon. In the present study, levels of AEA, related N-acylethanolamines (NAEs) and linoleic acid-derived oxylipins have been measured in the blood of 26 healthy women and 38 women with migraine (26 with aura, 12 without aura) who were matched for age and body-mass index. Blood samples were taken on two occasions: the first sample near the start of the menstrual cycle (when present) and the second approximately fourteen days later. For a subset of migraine patients, two additional blood samples were taken, one during a migraine attack and one approximately 1 month later (to be at the same stage in the menstrual cycle, when present). NAEs and oxylipins were measured by liquid chromatography coupled to mass spectrometry. Twenty-nine lipids were quantified, of which 16 were found to have a high reproducibility of measurement. There were no significant differences in the levels of AEA, the related NAEs stearoylethanolamide and oleoylethanolamide or any of the nine linoleic acid-derived oxylipins measured either between migraine patients with vs. without aura, or between controls and migraine patients (after stratification to take into account whether or not the individuals had regular menstruation cycles) in either of the first two samples. Levels of linoleoylethanolamide were lower in the patients with vs. without aura on the second sample but not in the first sample, but the biological importance of this finding is unclear. Due to time-dependent increases in their concentrations ex vivo prior to centrifugation, AEA and oleoylethanolamide levels in the samples collected during migraine attacks were not analysed, but for the other fourteen lipids, there were no significant differences in plasma concentrations during migraine vs. one month later. It is concluded that migraine is not associated with a generalised (as opposed to localised) deficiency in these lipids.

The Use of Cannabis for Headache Disorders

Headache disorders are common, debilitating, and, in many cases, inadequately managed by existing treatments. Although clinical trials of cannabis for neuropathic pain have shown promising results, there has been limited research on its use, specifically for headache disorders. This review considers historical prescription practices, summarizes the existing reports on the use of cannabis for headache, and examines the preclinical literature exploring the role of exogenous and endogenous cannabinoids to alter headache pathophysiology. Currently, there is not enough evidence from well-designed clinical trials to support the use of cannabis for headache, but there are sufficient anecdotal and preliminary results, as well as plausible neurobiological mechanisms, to warrant properly designed clinical trials. Such trials are needed to determine short- and long-term efficacy for specific headache types, compatibility with existing treatments, optimal administration practices, as well as potential risks.

Hypercoagulability and Migraine

BACKGROUND

A growing body of literature suggests that migraineurs, particularly those with aura, have an increased risk for ischemic stroke, but not via enhanced atherosclerosis. The theory that micro-emboli induced ischemia provokes cortical spreading depression (ie, symptomatic aura) in migraineurs but transient ischemic attacks in others highlights a potential role for hypercoagulability as a link between migraine (with aura) and stroke.

AIM

Our objective is to summarize the literature evaluating the association of migraine with various acquired or inheritable thrombophilic states, including those related to elevated estrogen levels, endothelial activation and dysfunction, antiphospholipid antibodies (aPL), deficiency of coagulation inhibitors, and presence of certain genetic polymorphisms.

FINDINGS

Although definitive studies are lacking, a preponderance of available evidence links migraine, and especially aura, to increased levels of estradiol (eg, oral contraceptive pill [OCP] use, pregnancy), thrombo- and erythrocytosis, von Willebrand factor (vWF) antigen, fibrinogen, tissue plasminogen activator (tPA) antigen, and endothelial microparticles. Studies of a link to migraine are conflicting for aPL, homocysteine, Protein S, and the methylenetetrahydrofolate reductase (MTHFR) C677T polymorphism. No association with migraine was found in meta-analyses of Factor V Leiden, and of prothrombin gene mutation. Within a large, young ischemic stroke sample, migraine with aura was associated with a thrombophilic state and with patent foramen ovale (PFO). In the non-stroke population, meta-analyses show an association of PFO and migraine with aura (MA), but two population-based studies do not support the link.

RECOMMENDATIONS

For persons with MA and (1) a personal history or family history of thrombosis, or (2) MRI evidence of micro-vascular ischemia or of stroke, an evaluation for hypercoagulability is warranted. In cases of MA alone, consider screening for markers of endothelial activation (eg, vWF, high sensitivity c-reactive protein [hs CRP], and fibrinogen). Rigorous management of other stroke risk factors is paramount, but efficacy of anti-thrombotic agents in the treatment of migraine is unproven. Closure of PFO is not routinely recommended based on negative randomized trials.

Clinical Endocannabinoid Deficiency Reconsidered: Current Research Supports the Theory in Migraine, Fibromyalgia, Irritable Bowel, and Other Treatment-Resistant Syndromes

Medicine continues to struggle in its approaches to numerous common subjective pain syndromes that lack objective signs and remain treatment resistant. Foremost among these are migraine, fibromyalgia, and irritable bowel syndrome, disorders that may overlap in their affected populations and whose sufferers have all endured the stigma of a psychosomatic label, as well as the failure of endless pharmacotherapeutic interventions with substandard benefit. The commonality in symptomatology in these conditions displaying hyperalgesia and central sensitization with possible common underlying pathophysiology suggests that a clinical endocannabinoid deficiency might characterize their origin. Its base hypothesis is that all humans have an underlying endocannabinoid tone that is a reflection of levels of the endocannabinoids, anandamide (arachidonylethanolamide), and 2-arachidonoylglycerol, their production, metabolism, and the relative abundance and state of cannabinoid receptors. Its theory is that in certain conditions, whether congenital or acquired, endocannabinoid tone becomes deficient and productive of pathophysiological syndromes. When first proposed in 2001 and subsequently, this theory was based on genetic overlap and comorbidity, patterns of symptomatology that could be mediated by the endocannabinoid system (ECS), and the fact that exogenous cannabinoid treatment frequently provided symptomatic benefit. However, objective proof and formal clinical trial data were lacking. Currently, however, statistically significant differences in cerebrospinal fluid anandamide levels have been documented in migraineurs, and advanced imaging studies have demonstrated ECS hypofunction in post-traumatic stress disorder. Additional studies have provided a firmer foundation for the theory, while clinical data have also produced evidence for decreased pain, improved sleep, and other benefits to cannabinoid treatment and adjunctive lifestyle approaches affecting the ECS.

Downstream effects of endocannabinoid on blood cells: implications for health and disease

Endocannabinoids (eCBs), among which N-arachidonoylethanolamine (AEA) and 2-arachidonoylglycerol (2-AG) are the most biologically active members, are polyunsaturated lipids able to bind cannabinoid, vanilloid and peroxisome proliferator-activated receptors. Depending on the target engaged, these bioactive mediators can regulate different signalling pathways, at both central and peripheral levels. The biological action of eCBs is tightly controlled by a plethora of metabolic enzymes which, together with the molecular targets of these substances, form the so-called "endocannabinoid system". The ability of eCBs to control manifold peripheral functions has received a great deal of attention, especially in the light of their widespread distribution in the body. In particular, eCBs are important regulators in blood, where they modulate haematopoiesis, platelet aggregation and apoptosis, as well as chemokine release and migration of immunocompetent cells. Here, we shall review the current knowledge on the pathophysiological roles of eCBs in blood. We shall also discuss the involvement of eCBs in those disorders affecting the haematological system, including cancer and inflammation. Knowledge gained to date underlines a fundamental role of the eCB system in blood, thus suggesting that it may represent a therapeutic promise for a broad range of diseases involving impaired hematopoietic cell functions.

Inhibition of FAAH reduces nitroglycerin-induced migraine-like pain and trigeminal neuronal hyperactivity in mice

There is evidence to suggest that a dysregulation of endocannabinoid signaling may contribute to the etiology and pathophysiology of migraine. Thus, patients suffering from chronic migraine or medication overuse headache showed alterations in the activity of the arachidonoylethanolamide (AEA) degrading enzyme fatty acid amide hydrolase (FAAH) and a specific AEA membrane transporter, alongside with changes in AEA levels. The precise role of different endocannabinoid system components is, however, not clear. We have therefore investigated mice with a genetic deletion of the two main cannabinoid receptors CB1 and CB2, or the main endocannabinoid degrading enzymes, FAAH and monoacylglycerol lipase (MAGL), which degrades 2-arachidonoylglycerol (2-AG), in a nitroglycerine-induced animal model of migraine. We found that nitroglycerin-induced mechanical allodynia and neuronal activation of the trigeminal nucleus were completely abolished in FAAH-deficient mice. To validate these results, we used two structurally different FAAH inhibitors, URB597 and PF3945. Both inhibitors also dose-dependently blocked nitroglycerin-induced hyperalgesia and the activation of trigeminal neurons. The effects of the genetic deletion of pharmacological blockade of FAAH are mediated by CB1 receptors, because they were completely disrupted with the CB1 antagonist rimonabant. These results identify FAAH as a target for migraine pharmacotherapy.

Medication overuse headache

Medication overuse headache (MOH) is a common and disabling headache disorder. It has a prevalence of about 1-2 % in the general population. The International Classification of Headache Disorders 3rd edition (beta version) has defined MOH as a chronic headache disorder in which the headache occurs on 15 or more days per month due to regular overuse of medication. These headaches must have been present for more than 3 months. The pathophysiology is complex and not completely known. It involves genetic and behavioural factors. There is evidence that cortical spreading depression, trigeminovascular system and neurotransmitters contribute to the pain pathway of MOH. The treatment of MOH includes patient education, stopping the offending drug(s), rescue therapy for withdrawal symptoms and preventative therapy. Relapse rates for MOH are high at 41 %. MOH can severely impact quality of life, so it is important to identify patients who are at risk of analgesic overuse.

Comprehensive Review of Medicinal Marijuana, Cannabinoids, and Therapeutic Implications in Medicine and Headache: What a Long Strange Trip It's Been …

BACKGROUND

The use of cannabis, or marijuana, for medicinal purposes is deeply rooted though history, dating back to ancient times. It once held a prominent position in the history of medicine, recommended by many eminent physicians for numerous diseases, particularly headache and migraine. Through the decades, this plant has taken a fascinating journey from a legal and frequently prescribed status to illegal, driven by political and social factors rather than by science. However, with an abundance of growing support for its multitude of medicinal uses, the misguided stigma of cannabis is fading, and there has been a dramatic push for legalizing medicinal cannabis and research. Almost half of the United States has now legalized medicinal cannabis, several states have legalized recreational use, and others have legalized cannabidiol-only use, which is one of many therapeutic cannabinoids extracted from cannabis. Physicians need to be educated on the history, pharmacology, clinical indications, and proper clinical use of cannabis, as patients will inevitably inquire about it for many diseases, including chronic pain and headache disorders for which there is some intriguing supportive evidence.

OBJECTIVE

To review the history of medicinal cannabis use, discuss the pharmacology and physiology of the endocannabinoid system and cannabis-derived cannabinoids, perform a comprehensive literature review of the clinical uses of medicinal cannabis and cannabinoids with a focus on migraine and other headache disorders, and outline general clinical practice guidelines.

CONCLUSION

The literature suggests that the medicinal use of cannabis may have a therapeutic role for a multitude of diseases, particularly chronic pain disorders including headache. Supporting literature suggests a role for medicinal cannabis and cannabinoids in several types of headache disorders including migraine and cluster headache, although it is primarily limited to case based, anecdotal, or laboratory-based scientific research. Cannabis contains an extensive number of pharmacological and biochemical compounds, of which only a minority are understood, so many potential therapeutic uses likely remain undiscovered. Cannabinoids appear to modulate and interact at many pathways inherent to migraine, triptan mechanisms ofaction, and opiate pathways, suggesting potential synergistic or similar benefits. Modulation of the endocannabinoid system through agonism or antagonism of its receptors, targeting its metabolic pathways, or combining cannabinoids with other analgesics for synergistic effects, may provide the foundation for many new classes of medications. Despite the limited evidence and research suggesting a role for cannabis and cannabinoids in some headache disorders, randomized clinical trials are lacking and necessary for confirmation and further evaluation.

Medication overuse headache

BACKGROUND

Medication overuse headache (MOH) affects between 1% and 2% of the general population but is present in up to 50% of patients seen in headache centers. There are currently no internationally accepted guidelines for treatment of MOH.

METHODS

A review of the current literature on MOH treatment and pathophysiology.

RESULTS

We conclude that headache frequency can be reduced to episodic headache in more than 50% of the patients by simple detoxification and information. Approximately half the patients will not have need for prophylactic medication after withdrawal. Pain perception is altered in patients with MOH but can be restored to a baseline pattern, indicating a reversible mechanism in the central sensitization leading to chronic pain. The great comorbidity with depression and anxiety could be a consequence of the altered serotonin metabolism indicating a reversible and potentially treatable condition.

CONCLUSION

Increased focus on MOH is extremely important, as MOH both can and should be treated and prevented. MOH is thus a diagnosis that should be considered in all chronic headache patients as the very first step in their management strategy. In the general population, prevention campaigns against MOH are essential to minimize chronic pain disability.

Medication-overuse headache: a review

Medication-overuse headache (MOH) is a worldwide health problem with a prevalence of 1%–2%. It is a severe form of headache where the patients often have a long history of headache and of unsuccessful treatments. MOH is characterized by chronic headache and overuse of different headache medications. Through the years, withdrawal of the overused medication has been recognized as the treatment of choice. However, currently, there is no clear consensus regarding the optimal strategy for management of MOH. Treatment approaches are based on expert opinion rather than scientific evidence. This review focuses on aspects of epidemiology, diagnosis, pathogenesis, prevention, and treatment of MOH. We suggest that information and education about the risk of MOH is important since the condition is preventable. Most patients experience reduction of headache days and intensity after successful treatment. The first step in the treatment of MOH should be carried out in primary care and focus primarily on withdrawal, leaving prophylactic medication to those who do not manage primary detoxification. For most patients, a general practitioner can perform the follow-up after detoxification. More complicated cases should be referred to neurologists and headache clinics. Patients suffering with MOH have much to gain by an earlier treatment-focused approach, since the condition is both preventable and treatable.

Medication-overuse headache: epidemiology, diagnosis and treatment

Medication-overuse headache (MOH) is one of the most common chronic headache disorders and a public health problem with a worldwide prevalence of 1-2%. It is a condition characterized by chronic headache and overuse of different headache medications, and withdrawal of the overused medication is recognised as the treatment of choice. However, the strategy for achieving withdrawal is, at present, based on expert opinion rather than scientific evidence, partly due to the lack of randomised controlled studies. This narrative review investigates different aspects of epidemiology, diagnosis, risk factors and pathogenesis as well as management for MOH. We suggest that the first step in the treatment of MOH should be carried out in general practice and should focus primarily on detoxification. For most patients, both prevention and follow up after detoxification can also be performed in general practice, thus freeing resources for referral of more complicated cases to headache clinics and neurologists. These suffering patients have much to gain by an earlier treatment-focused approach lower down on the treatment ladder.

Dexamethasone alleviates motion sickness in rats in part by enhancing the endocannabinoid system

Low-dose dexamethasone has been widely used for the prevention of nausea and vomiting after chemotherapy and surgical procedures and to treat motion sickness due to its minimal adverse effects, but the mechanisms underlying its anti-motion sickness effects are poorly understood. Previous studies have demonstrated that the endocannabinoid system is suppressed by motion sickness but stimulated by dexamethasone. The aim of the present study was to determine whether dexamethasone has an anti-motion sickness effect in rats and to elucidate the mechanism of this action. We used HPLC-MS/MS to measure the plasma concentrations of anandamide and 2-arachidonoylglycerol+1-arachidonoylglycerol, and we employed real-time quantitative PCR (qRT-PCR) and/or Western blot analysis to assay the expression of N-acylphosphatidyl-ethanolamine hydrolyzing phospholipase D, sn-1-selective diacylglycerol lipase, fatty acid hydrolase, monoacylglycerol lipase and endocannabinoid CB1 receptor in the dorsal vagal complex and stomach of rats exposed to a motion sickness protocol. The results showed that dexamethasone lowered the motion sickness index and restored the levels of endogenous cannabinoids and the expression of the endocannabinoid CB1 receptor, which declined after the induction of motion sickness, in the dorsal vagal complex and stomach.

Pathophysiology of medication overuse headache--an update

The pathogenesis of medication overuse headache is unclear. Clinical and preclinical studies have consistently demonstrated increased excitability of neurons in the cerebral cortex and trigeminal system after medication overuse. Cortical hyperexcitability may facilitate the development of cortical spreading depression, while increased excitability of trigeminal neurons may facilitate the process of peripheral and central sensitization. These changes may be secondary to the derangement of central, probably serotonin (5-HT)-, and perhaps endocannabinoid-dependent or other, modulating systems. Increased expression of excitatory cortical 5-HT2A receptors may increase the susceptibility to developing cortical spreading depression, an analog of migraine aura. A reduction of diffuse noxious inhibitory controls may facilitate the process of central sensitization, activate the nociceptive facilitating system, or promote similar molecular mechanisms to those involved in kindling. Low 5-HT levels also increase the expression and release of calcitonin gene-related peptide from the trigeminal ganglion and sensitize trigeminal nociceptors. Thus, derangement of central modulation of the trigeminal system as a result of chronic medication use may increase sensitivity to pain perception and foster or reinforce medication overuse headache.

Endocannabinoids in the brainstem modulate dural trigeminovascular nociceptive traffic via CB1 and "triptan" receptors: implications in migraine

Activation and sensitization of trigeminovascular nociceptive pathways is believed to contribute to the neural substrate of the severe and throbbing nature of pain in migraine. Endocannabinoids, as well as being physiologically analgesic, are known to inhibit dural trigeminovascular nociceptive responses. They are also involved in the descending modulation of cutaneous-evoked C-fiber spinal nociceptive responses from the brainstem. The purpose of this study was to determine whether endocannabinoids are involved in the descending modulation of dural and/or cutaneous facial trigeminovascular nociceptive responses, from the brainstem ventrolateral periaqueductal gray (vlPAG). CB1 receptor activation in the vlPAG attenuated dural-evoked Aδ-fiber neurons (maximally by 19%) and basal spontaneous activity (maximally by 33%) in the rat trigeminocervical complex, but there was no effect on cutaneous facial receptive field responses. This inhibitory vlPAG-mediated modulation was inhibited by specific CB1 receptor antagonism, given via the vlPAG, and with a 5-HT1B/1D receptor antagonist, given either locally in the vlPAG or systemically. These findings demonstrate for the first time that brainstem endocannabinoids provide descending modulation of both basal trigeminovascular neuronal tone and Aδ-fiber dural-nociceptive responses, which differs from the way the brainstem modulates spinal nociceptive transmission. Furthermore, our data demonstrate a novel interaction between serotonergic and endocannabinoid systems in the processing of somatosensory nociceptive information, suggesting that some of the therapeutic action of triptans may be via endocannabinoid containing neurons in the vlPAG.

Triptan safety during pregnancy: a Norwegian population registry study

Knowledge on triptan safety during pregnancy remains limited to their class effect or studies on sumatriptan. Our aim was to evaluate the individual effect of four most frequently used triptans on several pregnancy outcomes. We used the Norwegian prescription database to access information on triptans redeemed by pregnant women living in Norway between 2004 and 2007. This database was linked to the Medical Birth Registry of Norway covering every institutional delivery in Norway and providing information on pregnancy, delivery, maternal and neonatal health. Estimates of associations with pregnancy outcomes were obtained by Generalised Estimation Equations analysis. Of the 181,125 women in our study, 1,465 (0.8%) redeemed triptans during pregnancy, and 1,095 (0.6%) redeemed triptans before pregnancy only (disease comparison group). The population comparison group comprised the remaining 178,565 women. Using this group as reference, we found no associations between triptan redemption during pregnancy and congenital malformations. Second trimester redemption was associated with postpartum haemorrhage (adjusted OR 1.57; 95% CI 1.19-2.07). The disease comparison group had an increased risk of major congenital malformations (adjusted OR 1.48; 95% CI 1.11-1.97), low birth weight (adjusted OR 1.39; 95% CI 1.08-1.81), and preterm birth (adjusted OR 1.30; 95% CI 1.06-1.60). The association of triptans with postpartum hemorrhage could be attributable to decreased platelet agreeability occurring in severe migraine. Likewise, the increased risk of major congenital malformations and other adverse pregnancy outcomes in the disease comparison group might be attributable to migraine severity.

Predictive index for the onset of medication overuse headache in migraine patients

Migraine patients are particularly prone to develop medication overuse headache (MOH). However, the risk factors for the transformation of migraine to MOH are still not clear. We investigated gene polymorphisms, personality traits, and characteristics of headache and lifestyle in 47 migraine patients (aged 36.4 ± 10.3) and 22 MOH patients (aged 39.6 ± 9.9) who progressed from migraine and made a scoring system for a predictive index (PI) of the onset of MOH in patients with migraine. By multivariate logistic stepwise regression analysis, type of migraine, regular and sufficient dietary intake, and methylenetetrahydrofolate reductase (MTHFR) C677T (rs1801133) and dopamine D2 receptor (DRD2) C939T (rs6275) polymorphisms were selected as significant factors that contribute independently to the development from migraine to MOH (P < 0.05). The regression coefficients (β) of these four selected factors were approximated and scored. The PI score in MOH patients (7.32 ± 1.60) was significantly higher than that in migraine patients (4.62 ± 1.83, P < 0.001). The proposed scoring system should in the future be the object of larger studies to confirm its validity.

Medication-overuse headache and opioid-induced hyperalgesia: A review of mechanisms, a neuroimmune hypothesis and a novel approach to treatment

Introduction

Patients with chronic headache who consume large amounts of analgesics are often encountered in clinical practice. Excessive intake of analgesics is now considered to be a cause, rather than simply a consequence, of frequent headaches, and as such the diagnosis “medication-overuse headache” (MOH) has been formulated. Despite the prevalence and clinical impact of MOH, the pathophysiology behind this disorder remains unclear and specific mechanism-based treatment options are lacking.

Discussion

Although most acute headache treatments have been alleged to cause MOH, here we conclude from the literature that opioids are a particularly problematic drug class consistently associated with worsening headache. MOH may not be a single entity, as each class of drug implicated may cause MOH via a different mechanism. Recent evidence indicates that chronic opioid administration may exacerbate pain in the long term by activating toll-like receptor-4 on glial cells, resulting in a pro-inflammatory state that manifests clinically as increased pain. Thus, from the available evidence it seems opioid-overuse headache is a phenomenon similar to opioid-induced hyperalgesia, which derives from a cumulative interaction between central sensitisation, due to repeated activation of nociceptive pathways by recurrent headaches, and pain facilitation due to glial activation.

Conclusion

Treatment strategies directed at inhibiting glial activation may be of benefit alongside medication withdrawal in the management of MOH.

Targeting the endocannabinoid system for gastrointestinal diseases: future therapeutic strategies

Cannabinoids extracted from the marijuana plant (Cannabis sativa) and synthetic cannabinoids have numerous effects on gastrointestinal (GI) functions. Recent experimental data support an important role for cannabinoids in GI diseases. Genetic studies in humans have proven that defects in endocannabinoid metabolism underlie functional GI disorders. Mammalian cells have machinery, the so-called endocannabinoid system (ECS), to produce and metabolize their own cannabinoids in order to control homeostasis of the gut in a rapidly adapting manner. Pharmacological manipulation of the ECS by cannabinoids, or by drugs that raise the levels of endogenous cannabinoids, have shown beneficial effects on GI pathophysiology. This review gives an introduction into the functions of the ECS in the GI tract, highlights the role of the ECS in GI diseases and addresses its potential pharmacological exploitation.

Dependent behavior in patients with medication-overuse headache

Two thirds of patients with medication-overuse headache (MOH) fulfilled criteria for dependence on acute symptomatic treatments for pain, not exclusive of psychoactive medications, based on the fourth edition of the Diagnostic and Statistical Manual of Mental Disorders. Several questionnaires have been used to assess dependent behavior in patients with MOH. Findings regarding underlying psychological profiles of dependence and MOH are not consistent. Nevertheless, several neuroimaging, genetic, and neurobiological studies support the existence of the common pathophysiological features of dependence and MOH and suggest a link between them. This review highlights recent studies on the relationship between dependence and MOH. This issue is important because it implies a treatment strategy in managing patients with MOH by providing the treatment of dependence.

Habituation to pain in "medication overuse headache": a CO2 laser-evoked potential study

OBJECTIVE

Our aim was to investigate CO(2) laser-evoked potential (LEP) habituation to experimental pain in a group of patients affected by medication-overuse headache, with a history of episodic migraine becoming chronic, before and after treatment, consisting in acute medication withdrawal and a preventive treatment cycle.

BACKGROUND

One of the main features of LEPs in migraineurs is a lower habituation to repetitive noxious stimuli during the interictal phase.

METHODS

LEPs were recorded to stimulation of both the right hand and the right perioral region in 14 patients and in 14 healthy subjects. The habituation of both the N1 and the vertex N2/P2 components was assessed by measuring the LEP amplitude changes across 3 consecutive repetitions of 30 trials each.

RESULTS

In the 8 patients who had clinically improved after treatment, the N2/P2 amplitude habituation was significantly higher after treatment than before treatment following both hand (F = 43.2, P < .0001) and face stimulation (F = 6.9, P = .01). In these patients, the N2/P2 amplitude habituation after treatment was not different from that obtained in healthy controls (P = .18 and P = .73 for hand and face stimulation, respectively). On the contrary, in the patients who did not improve, the N2/P2 amplitude still showed reduced habituation after both hand (F = 3.1, P = .08) and face (F = 0.7, P = .4) stimulation.

CONCLUSION

The deficient habituation of the vertex N2/P2 complex was partly restored after successful treatment of medication-overuse headache, reflecting a modification in pain-processing pathways.

Fatty acids, membrane viscosity, serotonin and ischemic heart disease

Novel markers for ischemic heart disease are under investigation by the scientific community at international level.This work focuses on a specific platelet membrane fatty acid condition of viscosity which is linked to molecular aspects such as serotonin and G proteins, factors involved in vascular biology.A suggestive hypothesis is considered about the possibility to use platelet membrane viscosity, in relation to serotonin or, indirectly, the fatty acid profile, as indicator of ischemic risk.