Recent Advances in Pharmacotherapy for Migraine Prevention: From Pathophysiology to New Drugs

Migraine treatment: quo vadis? Real-world data study (2015-2022) in Spain

BACKGROUND

Migraine is a leading cause of disability, estimated to affect one-in-ten people in Spain. This study aimed to describe the management of migraine in Spain and identify improvement areas.

METHODS

Non-interventional, retrospective, cross-sectional cohort study conducted using an electronic medical records database covering visits to public healthcare providers for 3% of the Spanish population. Patients with a migraine diagnosis (ICD-9 346) between 01/2015 and 04/2022 were included, as well as their demographic and clinical characteristics, prescribed migraine treatments and the specialty of the prescribing physicians.

RESULTS

The database included 61,204 patients diagnosed with migraine. A migraine treatment had been prescribed to 50.6% of patients over the last 24 months (only acute to 69.5%, both acute and preventive to 24.2%, and only preventive to 6.3%). The most frequently prescribed treatments were NSAIDs (56.3%), triptans (44.1%) and analgesics (28.9%). Antidepressants were the most common preventive treatment (prescribed to 17.9% of all treated patients and 58.7% of those treated with a preventive medication), and anti-CGRP monoclonal antibodies the least prescribed (1.7%; 5.7%). In 13.4% of cases, preventive medications were the first treatment: alone in 5.8% of cases and together with an acute medication in 7.6%. A fifth of patients who were initially prescribed with only acute treatment were later prescribed a preventive medication (20.7%). On average, it took 29.4 months for this change to occur. Two-thirds of patients started their preventive treatment in primary care (64.2%). The percentage of patients treated by a neurologist increased with the number of received preventive medications. However, 28.8% of patients who had already been prescribed five or more distinct preventive treatments were not treated by a neurologist. Migraine patients had between 1.2- and 2.2-times higher prevalence of comorbidities than the general population, age-gender adjusted.

CONCLUSIONS

Our study emphasizes the need for improved management of migraine in Spain to reduce the risk of chronification and improve patient outcomes. More training and coordination across healthcare professionals is necessary to recognize and address risk factors for migraine progression, including multiple associated comorbidities and several lines of treatment, and to provide personalized treatment plans that address the complex nature of the condition.

Approach to headache disorders and the management of migraine: consensus guidelines from the Headache Society of Singapore, first edition (2023)

Headache disorders, particularly migraine, are one of the most common and disabling neurological disorders. There is a need for high-quality, accessible care for patients with headache disorders across all levels of the healthcare system in Singapore. The role of the Headache Society of Singapore is to increase awareness and advance the understanding of these disorders and to advocate for the needs of affected patients. In this first edition of local consensus guidelines, we focus on treatment approaches for headaches and provide consensus recommendations for the management of migraine in adults. The recommendations in these guidelines can be used as a practical tool in routine clinical practice by primary care physicians, neurologists and other healthcare professionals who have a common interest in headache disorders.

Temporal analysis of remote electric neuromodulation for the prevention of migraine

Aim: To evaluate the onset, magnitude and persistence of efficacy of remote electrical neuromodulation (REN) compared with placebo for the preventive treatment of migraine. Materials & methods: Analysis was conducted on data from a prospective, double-blind, placebo-controlled clinical trial, which assessed the efficacy of REN for the prevention of migraine. The number of monthly migraine days (MMD) per group was calculated in 2-week intervals and compared between the groups. Results: Differences between the active (N = 95) and placebo (N = 84) groups reached significance at 2 weeks: therapeutic gain 0.84 MMD; p = 0.036. 4 weeks gain 1.59 MMD; p = 0.025, 6 weeks gain 2.27 MMD; p < 0.001, 8 weeks gain 2.68 MMD; p < 0.001. Conclusion: REN provides rapid and consistent efficacy in preventive treatment of migraine.

Remote electrical neuromodulation for migraine prevention: A double-blind, randomized, placebo-controlled clinical trial

OBJECTIVE

To assess the clinical efficacy of remote electrical neuromodulation (REN), used every other day, for the prevention of migraine.

BACKGROUND

Preventive treatment is key to managing migraine, but it is often underutilized. REN, a non-pharmacological acute treatment for migraine, was evaluated as a method of migraine prevention in patients with episodic and chronic migraine.

METHODS

We conducted a prospective, randomized, double-blind, placebo-controlled, multi-center trial, with 1:1 ratio. The study consisted of a 4-week baseline observation phase, and an 8-week double-blind intervention phase in which participants used either REN or a placebo stimulation every other day. Throughout the study, participants reported their symptoms daily, via an electronic diary.

RESULTS

Two hundred forty-eight participants were randomized (128 active, 120 placebo), of which 179 qualified for the modified intention-to-treat (mITT) analysis (95 active; 84 placebo). REN was superior to placebo in the primary endpoint, change in mean number of migraine days per month from baseline, with mean reduction of 4.0 ± SD of 4.0 days (1.3 ± 4.0 in placebo, therapeutic gain = 2.7 [confidence interval -3.9 to -1.5], p < 0.001). The significance was maintained when analyzing the episodic (-3.2 ± 3.4 vs. -1.0 ± 3.6, p = 0.003) and chronic (-4.7 ± 4.4 vs. -1.6 ± 4.4, p = 0.001) migraine subgroups separately. REN was also superior to placebo in reduction of moderate/severe headache days (3.8 ± 3.9 vs. 2.2 ± 3.6, p = 0.005), reduction of headache days of all severities (4.5 ± 4.1 vs. 1.8 ± 4.6, p < 0.001), percentage of patients achieving 50% reduction in moderate/severe headache days (51.6% [49/95] vs. 35.7% [30/84], p = 0.033), and reduction in days of acute medication intake (3.5 ± 4.1 vs. 1.4 ± 4.3, p = 0.001). Similar results were obtained in the ITT analysis. No serious device-related adverse events were reported in any group.

CONCLUSION

Applied every other day, REN is effective and safe for the prevention of migraine.

Eptinezumab-jjmr, a humanized monoclonal specific to Calcitonin Gene Related Peptide, for the preventive treatment of migraine in adults

Purpose of Review

Migraines are prevalent and cause significant morbidity, decline in quality of life and healthcare costs universally. Treatment options are varied, but efficacy is limited. This review centers on Eptinezumab-jjmr, a humanized monoclonal specific to CGRP for the prevention of migraines in adults. Herein presented are the science and mechanism of action, indication and clinical evidence for use.

Recent Findings

Migraines are severe, recurrent headaches, which are either episodic or chronic in nature. The pain is severe, often accompanied by co-morbid symptoms, such as photophobia, phonophobia, nausea and emesis, and is limiting in nature. It is a prevalent disorder that causes significant, worldwide disability, morbidity, suffering, and costs.

The pathophysiology of migraines is actively studied, though recent research points to an initiating event causing migraine generation, that is then propagated by other brain regions, a significant one being the trigeminocervical complex. This is driven by biochemical transmitters, chiefly CGRP. This discovery led to the development of CGRP-targeting drugs, including gepants (small molecular antagonists) and anti-CGRP antibodies, such as Eptinezumab-jjmr.

Traditional therapy includes preventative and abortive treatment; however, adherence with preventative treatment has been historically poor, and certain types of abortive therapy carry risks and side effects that preclude them from a large patient population. Moreover, traditional therapy often falls short in migraine therapy. CGRP antagonist, including Eptinezumab, aims to cover the gaps in migraine therapy. We present here evidence to support the safe and effective use of Eptinezumab for the prevention of migraines.

Summary

Migraines are a prevalent primary headache disorder causing significant morbidity worldwide. Traditional abortive and preventative treatments fall short for many patients. Eptinezumab is part of new generation of CGRP-targeting medications and has shown significant evidence to support its use for the prevention of migraines. Further research is required to properly compare eptinezumab with existing pharmacotherapy and update guidelines on the appropriate combinations of therapies that are not available and the correct patient selection for each.

Rimegepant for the treatment of migraine

Migraine is a common form of primary headache, affecting up to 1 in every 6 Americans. The pathophysiology is an intricate interplay of genetic factors and environmental influence and is still being elucidated in ongoing studies. The trigeminovascular system is now known to have a significant role in the initiation of migraines, including the release of pain mediators such as CGRP and substance P. Traditional treatment of migraine is usually divided into acute and preventive treatment. Acute therapy includes non-specific therapy, such as NSAIDs and other analgesics, which may provide relief in mild to moderate migraines. 5-HT1 agonists may provide relief in severe migraine, but are not universally effective and carry a significant side-effect profile with frequent redosing requirement. Prophylactic therapy may reduce the occurrence of acute migraine attacks in selected patients, but does not completely eliminate it. More recently, CGRP antagonism has been studied and shown to be effective in both abortion and prevention of migraine. Novel medications, targeting CGRP, divide into CGRP antibodies and receptor antagonists (gepants). Rimegepant, a second-generation gepant, has shown efficacy in several clinical trials in treating acute migraine. Ongoing trials are also evaluating its role in migraine prophylaxis, and results are promising. It is also generally safer for use than existing options, does not appear to increase the chance of developing chronic migraines, and carries a very tolerable side effects profile. It is a part of a growing arsenal in migraine treatment, and may present the silver bullet for treatment of this disease.

A Comprehensive Review of Zavegepant as Abortive Treatment for Migraine

Migraine headache is a widespread and complex neurobiological disorder that is characterized by unilateral headaches that are often accompanied by photophobia and phonophobia. Migraine is one of the leading chief complaints in the emergency department with negative impacts on quality of life and activities of daily living. The high number of emergency presentations also results in a significant economic burden. Its risk factors include family history, genetics, sex, race, socioeconomics, the existence of comorbid conditions, and level of education. Triggers include stress, light, noise, menstruation, weather, changes in sleep pattern, hunger, dehydration, dietary factors, odors, and alcohol. The International Headache Society has defined criteria for the diagnosis of migraine with and without aura. The pathophysiology of migraine headaches is multifactorial so there are a variety of treatment approaches. The current treatment approach includes abortive medications and prophylactic medications. Abortive medications include the first-line treatment of triptans, followed by ergot alkaloids, and calcitonin gene-related peptide (CGRP) receptor antagonists along with supplemental caffeine and antiemetics. Trigeminal afferents from the trigeminal ganglion innervate most cranial tissues and many areas of the head and face. These trigeminal afferents express certain biomarkers such as calcitonin gene-related peptide (CGRP), substance P, neurokinin A, and pituitary adenylate cyclase-activating polypeptide that are important to the pain and sensory aspect of migraines. In this comprehensive review, we discuss Zavegepant, a calcitonin gene-related peptide receptor antagonist, as a new abortive medication for migraine headaches.

Headaches in Pregnancy and Postpartum: ACOG Clinical Practice Guideline No. 3

PURPOSE

To provide updated evidence-based recommendations for the evaluation and treatment of primary and secondary headaches in pregnancy and postpartum.

TARGET POPULATION

Pregnant and postpartum patients with a history of or experiencing primary or new secondary headaches.

METHODS

This guideline was developed using an a priori protocol in conjunction with a writing team consisting of two specialists in obstetrics and gynecology appointed by the ACOG Committee on Clinical Practice Guidelines-Obstetrics and one external subject matter expert. ACOG medical librarians completed a comprehensive literature search for primary literature within Cochrane Library, Cochrane Collaboration Registry of Controlled Trials, EMBASE, PubMed, and MEDLINE. Studies that moved forward to the full-text screening stage were assessed by two authors from the writing team based on standardized inclusion and exclusion criteria. Included studies underwent quality assessment, and a modified GRADE (Grading of Recommendations Assessment, Development, and Evaluation) evidence-to-decision framework was applied to interpret and translate the evidence into recommendation statements.

RECOMMENDATIONS

This Clinical Practice Guideline includes recommendations on interventions to prevent primary headache in individuals who are pregnant or attempting to become pregnant, postpartum, or breastfeeding; evaluation for symptomatic patients presenting with primary and secondary headaches during pregnancy; and treatment options for primary and secondary headaches during pregnancy and lactation. Recommendations are classified by strength and evidence quality. Ungraded Good Practice Points are included to provide guidance when a formal recommendation could not be made because of inadequate or nonexistent evidence.

Myocardial infarction, stroke and cardiovascular mortality among migraine patients: a systematic review and meta-analysis

BACKGROUND

An increasing number of studies have shown an association between migraine and cardiovascular disease, in particular cardio- and cerebro-vascular events.

METHODS

Three electronic databases (PubMed, Embase and Scopus) were searched from inception to May 22, 2021 for prospective cohort studies evaluating the risk of myocardial infarction, stroke and cardiovascular mortality in migraine patients. A random effects meta-analysis model was used to summarize the included studies.

RESULTS

A total of 18 prospective cohort studies were included consisting of 370,050 migraine patients and 1,387,539 controls. Migraine was associated with myocardial infarction (hazard ratio, 1.36; 95% CI, 1.23-1.51; p =  < 0.001), unspecified stroke (hazard ratio, 1.30; 95% CI, 1.07-1.60; p = 0.01), ischemic stroke (hazard ratio, 1.35; 95% CI, 1.03-1.78; p = 0.03) and hemorrhagic stroke (hazard ratio, 1.43; 95% CI, 1.07-1.92; p = 0.02). Subgroup analysis of migraine with aura found a further increase in risk of myocardial infarction and both ischemic and hemorrhagic stroke, as well as improved substantial statistical heterogeneity. Migraine with aura was also associated with an increased risk of cardiovascular mortality (hazard ratio, 1.27; 95% CI, 1.14-1.42; p =  < 0.001).

CONCLUSION

Migraine, especially migraine with aura, is associated with myocardial infarction and stroke. Migraine with aura increases the risk of overall cardiovascular mortality.

Was it something I ate? Understanding the bidirectional interaction of migraine and appetite neural circuits

Migraine attacks can involve changes of appetite: while fasting or skipping meals are often reported triggers in susceptible individuals, hunger or food craving are reported in the premonitory phase. Over the last decade, there has been a growing interest and recognition of the importance of studying these overlapping fields of neuroscience, which has led to novel findings. The data suggest additional studies are needed to unravel key neurobiological mechanisms underlying the bidirectional interaction between migraine and appetite. Herein, we review information about the metabolic migraine phenotype and explore migraine therapeutic targets that have a strong input on appetite neuronal circuits, including the calcitonin gene-related peptide (CGRP), the pituitary adenylate cyclase-activating polypeptide (PACAP) and the orexins. Furthermore, we focus on potential therapeutic peptide targets that are involved in regulation of feeding and play a role in migraine pathophysiology, such as neuropeptide Y, insulin, glucagon and leptin. We then examine the orexigenic - anorexigenic circuit feedback loop and explore glucose metabolism disturbances. Additionally, it is proposed a different perspective on the most reported feeding-related trigger - skipping meals - as well as a link between contrasting feeding behaviors (skipping meals vs food craving). Our review aims to increase awareness of migraine through the lens of appetite neurobiology in order to improve our understanding of the earlier phase of migraine, encourage better studies and cross-disciplinary collaborations, and provide novel migraine-specific therapeutic opportunities.

Cannabinoid Use in a Tertiary Headache Clinic: A Cross-Sectional Survey

OBJECTIVE

This study seeks to determine the prevalence and nature of cannabis use in patients with headache in a tertiary headache clinic and to explore patients' empiric experience in using cannabinoids therapeutically.

BACKGROUND

Many patients with headache report cannabinoid use as an effective abortive and/or preventive therapy. Mounting evidence implicates cannabinoids in pain mechanisms pertaining to migraine and other headache types.

METHODS

A cross-sectional study surveyed 200 patients presenting with any headache disorder to a tertiary headache clinic in Calgary, Alberta. Descriptive analyses were applied to capture information about headache diagnoses and the frequency, doses and methods of cannabinoid delivery employed, as well as patients' perceptions of therapeutic benefit and selected negative side effects.

RESULTS

Active cannabinoid users comprised 34.0% of respondents. Approximately 40% of respondents using cannabinoids engaged in very frequent use (≥300 days/year). Of cannabinoid modalities, liquid concentrates were most popular (39.2%), followed by smoked cannabis (33.3%). Patients endorsed cannabinoid use for both prevention and acute therapy of headaches, often concurrently. Sixty percent of respondents felt cannabinoids reduced headache severity, while 29.2% perceived efficacy in aborting headaches. Nearly 5% of respondents volunteered that they had encountered a serious problem such as an argument, fight, accident, or work issue as a result of their cannabis use. Approximately 35.4% of users had attempted to reduce their use.

CONCLUSION

This survey shows that over one-third of patients with headache disorders in a tertiary headache clinic use cannabis as a treatment for their headaches. Of these, about 25% and 60% perceive improvements in headache frequency and severity, respectively. The results of this survey will aid neurologists and headache specialists in understanding the landscape of cannabinoid use in a more severely affected population and inform future-controlled studies of cannabinoids in headache patients.

Galcanezumab: A Review in the Prevention of Migraine and Treatment of Episodic Cluster Headache

Galcanezumab (Emgality^®) is a humanized monoclonal antibody targeting the calcitonin gene-related peptide (CGRP), thereby inhibiting its physiological activity, with CGRP playing a key role in the pathophysiology of migraine and headache disorders. In pivotal phase 3 trials, recommended dosages of subcutaneous galcanezumab once monthly were significantly more effective than placebo as preventive therapy in adults with episodic (EVOLVE-1 and -2; over 6 months) or chronic (REGAIN; over 3 months) migraine (±  aura), including in patients who had failed several prior preventive migraine drugs (CONQUER; over 3 months). The beneficial effects of galcanezumab preventive treatment in reducing the number of monthly migraine headache days (MHDs) and improving health-related quality of life (HR-QOL) were sustained during up to 1 year of treatment. In adults with episodic cluster headache, galcanezumab treatment was associated with a significant reduction in the weekly frequency of cluster headache attacks across weeks 1-3 compared with placebo (primary endpoint), albeit during weeks 4-8, there was a convergence of results between these treatment groups. Although further evidence from the clinical setting is required to determine its long-term safety profile, given its convenient administration regimen, efficacy and short-term tolerability profile, monthly galcanezumab represents an important emerging option for the prevention of episodic and chronic migraine (±  aura) and the treatment of episodic cluster headache.

An Evidence-Based Review of Galcanezumab for the Treatment of Migraine

PURPOSE OF REVIEW

This is a comprehensive review of the current literature on the usage of galcanezumab for migraine treatment. It reviews the biology, pathophysiology, epidemiology, diagnosis, and conventional treatment of migraines, then compares the literature available for galcanezumab with historical treatment options.

RECENT FINDINGS

Migraine is a common headache disorder and constitutes a significant source of distress from both a personal and societal perspective. Conventional treatment includes abortive and preventive treatment. Treatment options are limited and may be only partially or minimally effective in some of the population. Recent evidence points to metabolic changes in the brain as possible causes of migraine, via reduced available energy or a spiking need for it, resulting in a relative insufficiency. This leads to trigeminocervical complex (TCC) activation and a headache episode, modulated by calcitonin gene-related peptide (CGRP). Galcanezumab (Emgality) is a monoclonal antibody targeting CGRP that is given in a monthly injection for the prevention of migraines. Its safety was previously shown in phase 1 and 2 trials, and recent phase 3 trials showed efficacy, with up to 50% reduction in monthly migraine days and improved functional capacity in migraineurs. Studies show that the drug is well tolerated and safe. Migraine headache is a common neurological syndrome that causes great pain and suffering. Treatment options today are limited. Galcanezumab does not prevent migraines, but it is effective in decreasing their frequency and length. It is also much better tolerated than the currently existing therapies. While it is unlikely to provide monotherapy for migraines, it is a novel therapy that may be added for cases of severe or frequent migraines.

Treatment patterns and medication adherence among newly diagnosed patients with migraine: a drug utilisation study

OBJECTIVES

Prophylactic drugs currently used for migraine treatment are not specific. Furthermore, few studies in existing literature describe drugs utilisation patterns and adherence to migraine prophylactic treatment. This study is aimed to describe utilisation patterns of migraine drugs, evaluate adherence to prophylactic medications and investigate drug-related costs.

DESIGN

Retrospective population-based study using an administrative health-related database.

SETTING

Primary care setting in the Campania region, Southern Italy.

PARTICIPANTS

This study was carried out between 1 January 2016 and 31 December 2018, involving 12 894 subjects with any primary or secondary hospital discharge with migraine diagnosis, or at least two medical dispensations of migraine-specific acute or prophylactic medications (triptans or pizotifen). Subjects were classified into four treatment cohorts: no treatment, acute, prophylactic and both acute and prophylactic. Subjects were followed-up for 1 year.

OUTCOME MEASURES

Utilisation patterns of migraine drugs at treatment initiation; adherence to prophylactic treatment; discontinuation, restart and switching rates; annual migraine drug costs per patient.

RESULTS

Overall, 81.1% of subjects received acute treatment as their initial migraine treatment regimen, 10.7% prophylactic treatment, 8.2% both acute and prophylactic treatment. 599 patients were treated prophylactically; of these, 26.2% adhered to their initial treatment while 73.8% reported interruptions in treatment. Among the latter, 46.4% of patients discontinued the treatment completely within 103 days (IQR 89.0), 31% restarted treatment 46 days after interruption (IQR 60.0) and 22.6% switched to another treatment within 98 days (IQR 57.5) (p<0.001). The median annual cost of drugs per patient was €103 for those treated acutely, €75 for those treated prophylactically, €163 for those treated both.

CONCLUSIONS

Migraine treatment with acute medications is still prevalent in Italy; only few patients received prophylactic treatment with poor adherence to treatment. These findings reflect an unmet need for improved prophylactic therapies in order to provide a better disease management.

Translation and validation of an extended German version of ID Migraine™ as a migraine screening tool

Background and purpose:

Diagnosing a patient with headache as a migraineur is critical for state-of-the-art migraine management. Screening tools are imperative means to improve the diagnostic yield in the primary care settings and specialized clinics. This study aims to translate and assess the diagnostic accuracy of a German version of the ID Migraine™ as a widely used and efficient screening instrument.

Methods:

The Functional Assessment of Chronic Illness Therapy translation methodology was used to translate the original three-item ID Migraine™, including a fourth question for aura, from the English language into the German language. Diagnostic accuracy of the German ID Migraine™ and predictors of false screening results were assessed among patients presenting to a headache outpatient clinic of a tertiary care center in Germany over a 6-month period.

Results:

The translation procedure yielded a harmonized German ID Migraine™ and its diagnostic accuracy was assessed in 105 patients (80 female, 46.5 ± 17.2 years of age), including 79 patients (75.2%) with migraine. The three-item German ID Migraine™ provides a sensitivity of 99%, specificity of 68%, and positive and negative predictive values of 90% and 95%, respectively, using a cutoff of ≥2. Positive and negative predictive values in a general headache population are estimated to be 74% and 98%, respectively. The aura question identified 18 out of 20 migraineurs with aura.

Conclusions:

The German ID Migraine™ is an accurate screening tool for migraine even in a challenging population of a specialized outpatient clinic. Its diagnostic accuracy indicates a potential utility for screening in primary health care.

Safety and efficacy of galcanezumab in Taiwanese patients: a post-hoc analysis of phase 3 studies in episodic and chronic migraine

OBJECTIVE

Migraine is a chronic, disabling neurological disease affecting >1 billion people worldwide. Migraine remains undertreated in Asia, including Taiwan. Galcanezumab is a humanized monoclonal antibody that selectively binds calcitonin gene-related peptide, a peptide firmly established in the pathophysiology of migraine, with demonstrated efficacy and safety in patients with episodic or chronic migraine. Our objective was to evaluate the efficacy and safety of galcanezumab in Taiwanese patients with episodic or chronic migraine.

METHODS

We conducted a sub-group analysis of the Taiwanese cohort from two double-blind, placebo-controlled, Phase 3 clinical trials of galcanezumab in the prevention of episodic and chronic migraine, EVOLVE-2 (NCT02614196) and REGAIN (NCT02614261), respectively. During the EVOLVE-2 and REGAIN double-blind periods, 2092 patients were randomly assigned to receive monthly injections of either placebo, 120 mg galcanezumab (240 mg loading dose), or 240 mg galcanezumab. In REGAIN, a 9-month open-label period followed. Post-hoc analysis on the Taiwanese population across both trials included 106 patients, 45 of whom continued into the open-label period in REGAIN.

RESULTS

Our findings show that galcanezumab has similar efficacy and safety in the Taiwanese population, as compared to the "All Patients" population included in the study. Galcanezumab treatment reduced the number of monthly migraine headache days, determined a higher percentage of patients with a ≥ 50% response, and positively impacted quality of life.

CONCLUSION

Galcanezumab is a promising therapeutic for the preventive treatment of migraine in the Taiwanese population.

The Spectrum of Response to Erenumab in Patients With Episodic Migraine and Subgroup Analysis of Patients Achieving ≥50%, ≥75%, and 100% Response

Objective

To assess the efficacy of erenumab at the ≥50%, ≥75%, and 100% reduction in monthly migraine days (MMD) response thresholds, using data from the 6‐month double‐blind treatment phase (DBTP) of the Study to Evaluate the Efficacy and Safety of Erenumab in Migraine Prevention (STRIVE) pivotal clinical trial.

Methods

Enrolled patients with episodic migraine (EM; ≥4 MMD and <15 monthly headache days) were randomized (1:1:1) to erenumab 70 mg (n = 312), erenumab 140 mg (n = 318), or placebo (n = 316) once monthly. We determined the proportions of patients with ≥50%, ≥75% and 100% reduction in MMD over the last 3 months of the STRIVE DBTP (months 4 through 6) and conducted post hoc analyses to contextualize the treatment benefit in patient subgroups achieving, and not achieving, these response thresholds. Outcome measures included changes in MMD, acute migraine‐specific medication days (MSMD), and patient‐reported outcomes.

Results

The proportions of patients with a reduction in MMD from baseline were greater for erenumab than for placebo at all response thresholds. As previously reported for the ≥50% response threshold, 135/312 (43.3%) of patients on erenumab 70 mg and 159/318 (50.0%) on erenumab 140 mg responded, vs 84/316 (26.6%) for placebo. At months 4 through 6, 65/312 (20.8%) and 70/318 (22.0%) of those on erenumab 70 mg and erenumab 140 mg, respectively, achieved ≥75% reductions vs 25/316 (7.9%) on placebo. A reduction of 100% response, which required no migraine days over 3 consecutive months based on observed data, was achieved by 10/312 (3.2%) of patients treated with erenumab 70 mg and 16/318 (5.0%) for erenumab 140 mg, vs 9/316 (2.8%) for placebo. At all response thresholds, responders achieved numerically greater reductions in mean MMD and MSMD, and greater improvements in disability than did the overall population; importantly, these remarkable responses were noted early. Meanwhile, 60/312 (19.2%) and 53/318 (16.7%) patients on erenumab 70 and 140 mg, respectively, had no reduction in MMD from baseline in months 4 through 6, compared with 104/316 (32.9%) patients on placebo.

Conclusions

The responses at the ≥50%, ≥75%, and 100% thresholds provide context for establishing realistic patient and physician expectations regarding the magnitude of treatment benefit that may be achieved by patients with EM responding to erenumab (STRIVE, NCT02456740).

The Role of Magnesium in Pathophysiology and Migraine Treatment

Migraine is one of the most common recurrent types of headache and is the seventh cause of disability. This neurological disorder is characterized by having pain in head and other various symptoms such as nausea, emesis, photophobia, phonophobia, and sometimes visual sensory disorders. Magnesium (Mg) is a necessary ion for human body and has a crucial role in health and life maintenance. One of the main roles of Mg is to conserve neurons electric potential. Therefore, magnesium deficiency can cause neurological complications. Migraine is usually related to low amounts of Mg in serum and cerebrospinal fluid (CSF). Deficits in magnesium have significant role in the pathogenesis of migraine. Mg has been extensively used in migraine prophylaxis and treatment. This review summarizes the role of Mg in migraine pathogenesis and the potential utilizations of Mg in the prevention and treatment of migraine with the emphasis on transdermal magnesium delivery.

Enhanced mindfulness-based stress reduction in episodic migraine: a randomized clinical trial with magnetic resonance imaging outcomes

We aimed to evaluate the efficacy of an enhanced mindfulness-based stress reduction (MBSR+) vs stress management for headache (SMH). We performed a randomized, assessor-blind, clinical trial of 98 adults with episodic migraine recruited at a single academic center comparing MBSR+ (n = 50) with SMH (n = 48). MBSR+ and SMH were delivered weekly by group for 8 weeks, then biweekly for another 8 weeks. The primary clinical outcome was reduction in headache days from baseline to 20 weeks. Magnetic resonance imaging (MRI) outcomes included activity of left dorsolateral prefrontal cortex (DLPFC) and cognitive task network during cognitive challenge, resting state connectivity of right dorsal anterior insula to DLPFC and cognitive task network, and gray matter volume of DLPFC, dorsal anterior insula, and anterior midcingulate. Secondary outcomes were headache-related disability, pain severity, response to treatment, migraine days, and MRI whole-brain analyses. Reduction in headache days from baseline to 20 weeks was greater for MBSR+ (7.8 [95% CI, 6.9-8.8] to 4.6 [95% CI, 3.7-5.6]) than for SMH (7.7 [95% CI 6.7-8.7] to 6.0 [95% CI, 4.9-7.0]) (P = 0.04). Fifty-two percent of the MBSR+ group showed a response to treatment (50% reduction in headache days) compared with 23% in the SMH group (P = 0.004). Reduction in headache-related disability was greater for MBSR+ (59.6 [95% CI, 57.9-61.3] to 54.6 [95% CI, 52.9-56.4]) than SMH (59.6 [95% CI, 57.7-61.5] to 57.5 [95% CI, 55.5-59.4]) (P = 0.02). There were no differences in clinical outcomes at 52 weeks or MRI outcomes at 20 weeks, although changes related to cognitive networks with MBSR+ were observed. Enhanced mindfulness-based stress reduction is an effective treatment option for episodic migraine.

Multidimensional assessment of the effects of erenumab in chronic migraine patients with previous unsuccessful preventive treatments: a comprehensive real-world experience

BACKGROUND

erenumab was safe and effective in clinical trials for the prevention of migraine. However, real-life data are still lacking. Here we report the clinical experience from an Italian real-world setting using erenumab in patients with chronic migraine experiencing previous unsuccessful preventive treatments.

METHODS

Seventy patients with chronic migraine and failure to ≥4 migraine preventive medication classes initially received monthly erenumab 70 mg s.c. Patients without a clinically meaningful improvement, considered as a > 30% reduction in headache days per month, after ≥3 months of therapy switched to monthly erenumab 140 mg. At the first administration and after 3 and 6 months, patients underwent extensive interviews to assess clinical parameters of disease severity and migraine-related disability and impact, and validated questionnaires to explore depression/anxiety, sleep, and quality of life (QoL). Finally, the Pain Catastrophizing Scale, Allodynia Symptom Checklist-12 and MIGraine attacks-Subjective COGnitive impairments scale (MIG-SCOG) were administered.

RESULTS

70% of patients were "responders" after the third administration of erenumab 70 mg, whereas 30% switched to erenumab 140 mg; 29% (6 pts) responded after the sixth administration. The headache-day frequency was reduced from 21.1 ± 0.7 to 11.4 ± 0.9 days after the third administration (p < 0.001) and to 8.9 ± 0.7 days after the sixth administration (p < 0.001). 53% and 70% of patients, respectively, showed a reduction of ≥50% of headache days/month after the third and the sixth administrations. Also improved were headache pain severity, migraine-related disability, and impact on daily living, QoL, pain catastrophizing and allodynia (all p < 0.001), quality of sleep, symptoms of depression or anxiety (p < 0.05) but not MIG-SCOG. There were no new adverse event signals.

CONCLUSION

These real-world data support monthly erenumab 70 or 140 mg s.c. as a safe and effective preventive treatment to reduce headache frequency and severity in chronic migraine patients experiencing previous unsuccessful preventive treatments.

Migraine Pathophysiology

Migraine is the leading cause of years lost due to disability in individuals aged 15 to 49 years. Much has changed over the last three decades about our understanding of this complex neurological disorder. Various phases of migraine have been characterized and are the focus of this review. The premonitory phase involves bothersome symptoms experienced hours to days before migraine pain. Behavioral changes and functional neuroimaging studies point toward hypothalamic involvement during the premonitory and other migraine phases. Migraine aura is a disruptive, reversible neurological phenomenon that affects up to one-third of all migraineurs, and can overlap with the headache phase. The mechanism responsible for this phase is thought to be cortical spreading depolarization through the cortex. This process leads to temporary disruptions in ion homeostasis and the ensuing neuronal dysfunction. The headache phase involves activation of the trigeminocervical complex. Neuropeptides are implicated in trigeminal activation, and calcitonin gene-related peptide in particular has become a promising target of therapeutic intervention for migraine. The final phase of migraine is the postdrome, the period of time from the resolution of headache symptoms until return to baseline following a migraine. People often report neuropsychiatric, sensory, gastrointestinal, and general symptoms during this time, which can limit activity. Elucidating the neuroanatomical, chemical, and neuroimaging correlates of these migraine phases allows for an improved comprehension of the underlying changes associated with migraine symptomatology and can assist with evaluation of arising therapeutics for migraine management.

Inpatient Management of Migraine

Migraine is a frequently disabling neurologic condition which can be complicated by medication overuse headache and comorbid medical disorders, including obesity, anxiety and depression. Although most migraine management takes place in outpatient clinics, inpatient treatment is indicated for migraine refractory to multiple outpatient treatments, with intractable nausea or vomiting, need for detoxification from medication overuse (such as opioids and barbiturates), and significant medical and psychiatric disease. The goals of inpatient treatment include breaking the current cycle of headache pain, reducing the frequency and/or severity of future attacks, monitored detoxification of overused medications, and reducing disability and improving quality of life.

Emerging Treatment Options for Migraine

Migraine is one of top 5 medical conditions that contribute to Years Lived with Disability and affects approximately 1 billion people from around the world. To date, preventive treatment and acute therapies for migraine are limited, have undesirable side effects and are poorly tolerated in patients. In the last few decades, considerable advances in our understanding of migraine and its pathophysiology have paved the way for the development of targeted treatment options. Calcitonin gene-related peptide (CGRP) plays an integral role in the neurobiology of migraine, and new classes of drugs that target the CGRP pathway have included gepants and CGRP pathway monoclonal antibodies. Serotonin 5-HT1F receptor agonists—namely ditans—have also been developed to treat acute migraine. Lastly, non-invasive neuromodulation offers another treatment option for migraine patients who prefer treatments that have fewer side effects and are well tolerated. In this review, we discussed emerging treatment options for migraine that were made available in recent years. Ann Acad Med Singapore 2020;49:226–35 Key words: Calcitonin gene-related peptide monoclonal antibody, Gepants, Headache, Lasmiditan, Neuromodulation

Acid-sensing ion channel 3 blockade inhibits durovascular and nitric oxide-mediated trigeminal pain

Background and Purpose

There is a major unmet need to develop new therapies for migraine. We have previously demonstrated the therapeutic potential of the acid‐sensing ion channel (ASIC) blockade in migraine, via an ASIC1 mechanism. ASIC3 is expressed in the trigeminal ganglion and its response is potentiated by NO that can trigger migraine attacks in patients. Thus we sought to explore the potential therapeutic effect of ASIC3 blockade in migraine.

Experimental Approach

To investigate this, we utilised validated electrophysiological and behavioural rodent preclinical models. In rats, ASIC3 blockade using APETx2 (50 or 100 μg·kg⁻¹, i.v.) was measured by using durovascular and NO‐evoked trigeminal nociceptive responses along with cortical spreading depression models. In mice, we sought to determine if periorbital mechanical sensitivity, induced by acute nitroglycerin (10 mg·kg⁻¹, i.p.), was attenuated by APETx2 (230 μg·kg⁻¹, i.p.), as well as latent sensitisation induced by bright light stress in a chronic nitroglycerin model.

Key Results

Here, we show that the ASIC3 blocker APETx2 inhibits durovascular‐evoked and NO‐induced sensitisation of trigeminal nociceptive responses in rats. In agreement, acute and chronic periorbital mechanosensitivity induced in mice by nitroglycerin and subsequent bright light stress‐evoked latent sensitivity as a model of chronic migraine are all reversed by APETx2.

Conclusion and Implications

These results support the development of specific ASIC3 or combined ASIC1/3 blockers for migraine‐related pain and point to a potential role for ASIC‐dependent NO‐mediated attack triggering. This has key implications for migraine, given the major unmet need for novel therapeutic targets.

Economic burden of migraine in Singapore

Objective:

Despite the high prevalence and disabling nature of migraine, studies evaluating its economic burden in Singapore remain scant. This study aims to quantify the per capita and aggregate economic cost of episodic migraine (EM; ≤14 monthly headache days) without aura among full-time employees in Singapore.

Methods:

We administered a cross-sectional online survey to full-time employees in Singapore who met the International Classification of Headache Disorders (third edition, 2018) criteria for EM without aura. Eligible participants were classified by the frequency of monthly migraine days (MMDs): lower end episodic migraine (LEM; ≤3 MMDs) and upper end episodic migraine (UEM; 4–14 MMDs). The survey captured per capita healthcare resource utilization and lost work productivity (absenteeism and presenteeism) for each subgroup. Healthcare costs were obtained by multiplying unit costs by healthcare utilization. Finally, per capita (patient) costs of each subgroup were then imputed and multiplied by prevalence data to quantify the aggregate burden of migraine in Singapore.

Results:

Of the 606 participants who completed the survey, 81% experienced ≤3 MMDs. Total annual per capita costs were SGD4925 (USD 3620; 95% confidence interval (CI): SGD 4438–5411) and SGD14,476 (USD 10,639; 95% CI: SGD 11,908–17,045) for the LEM and UEM subgroup, respectively. Healthcare costs on average accounted for 17.6% of per capita costs, of which was driven primarily by diagnostic tests (33.6%), followed by consultations (17.1%), medications (16.7%), alternative medications (16.6%) and hospitalizations (14.8%). Lost productivity accounted for 82.4% of costs, chiefly attributable to absenteeism in the LEM group (38.2%), followed by presenteeism in the UEM group (26.0%), absenteeism in the UEM group (18.8%) and presenteeism in the LEM group (17.1%). The total cost to Singapore for EM in 2018 was approximately SGD 1 billion (USD 0.75 billion; SGD 1.00 = USD 0.74).

Conclusion:

Overall, EM imposes a substantial economic burden on society in Singapore. Total migraine cost per capita is greater in the UEM (4–14 MMDs) as compared to the LEM subgroup. Majority of the overall costs result from missed workdays and lost work productivity. Future research should determine the extent to which optimized migraine treatments could improve productivity, and by extension, mitigate the staggering costs of this disorder.

Efficacy of galcanezumab in patients with episodic migraine and a history of preventive treatment failure: results from two global randomized clinical trials

BACKGROUND AND PURPOSE

The efficacy of galcanezumab, a monoclonal antibody for migraine prevention, has been demonstrated in two pivotal trials in patients with episodic migraine.

METHODS

EVOLVE-1 and EVOLVE-2 were identical phase 3, randomized, double-blind, placebo-controlled studies in patients with episodic migraine. Mean migraine headache days per month at baseline was 9. Patients were randomized 2:1:1 to monthly injections of placebo, galcanezumab 120 mg/240 mg during the 6-month double-blind treatment period. Key efficacy outcomes were assessed in subgroups amongst patients for whom, previously, for efficacy and/or safety/tolerability reasons (i) one or more (≥1) preventives failed, (ii) two or more (≥2) preventives failed and (iii) preventives were never used, or used but not failed (no prior failure).

RESULTS

In an integrated analysis of EVOLVE studies, galcanezumab 120 mg/240 mg versus placebo led to larger overall mean (SE) reductions in monthly migraine headache days across 6 months in patients with prior preventive failures (P < 0.001): ≥1 failure: 120 mg: -4.0 (0.4); 240 mg: -4.2 (0.5); placebo: -1.3 (0.4); ≥2 failures: 120 mg: -3.1 (0.7); 240 mg: -3.8 (0.8); placebo: -0.5 (0.6). Similar results were observed amongst patients with no prior failure, but the placebo response was larger: 120 mg: -4.7 (0.2); 240 mg: -4.5 (0.2); placebo: -3.0 (0.2) (P < 0.001 versus placebo). Significant improvements were observed with galcanezumab versus placebo for ≥50% and ≥75% reduction in monthly migraine headache days.

CONCLUSION

In patients with episodic migraine treated with galcanezumab, those with ≥1 or ≥2 prior preventive failures had significantly larger improvements, versus placebo, in efficacy outcomes. Similar results were observed in patients with no prior failure, with a larger placebo response.

Safety and tolerability of ubrogepant following intermittent, high-frequency dosing: Randomized, placebo-controlled trial in healthy adults

BACKGROUND

Ubrogepant is a novel, oral calcitonin gene-related peptide (CGRP) receptor antagonist in development for the acute treatment of migraine. This trial evaluated the safety and tolerability of ubrogepant, focusing on hepatic safety, when administered intermittently with high-frequency dosing to healthy participants.

METHODS

In this phase 1, multicenter, double-blind, parallel-group trial, healthy adults (age 18-50 years) were randomized 1:1 to placebo or ubrogepant. Ubrogepant was dosed at 100 mg (2 × 50 mg tablets) on 2 consecutive days followed by 2 consecutive days of placebo, alternating for 8 weeks. Primary outcome measures were safety and tolerability.

RESULTS

Of participants randomized (n = 518), 516 were included in the safety population (n = 260 placebo; n = 256 ubrogepant). Treatment-emergent adverse events were reported in 45% of placebo and 44% of ubrogepant participants. The most common was headache (10% placebo; 11% ubrogepant). Overall, seven cases of alanine aminotransferase and/or aspartate aminotransferase levels ≥ 3 × the upper limit of normal (five placebo, two ubrogepant) were reported and adjudicated by a panel of independent liver experts blinded to treatment. Four cases were judged unlikely related to treatment. Two cases (one placebo, one ubrogepant) were judged possibly related, and one (ubrogepant) probably related. Alanine aminotransferase increases to ≥ 3 × the upper limit of normal in the two ubrogepant cases (possibly or probably related) were transient and resolved with continued dosing; both cases were asymptomatic, with no concurrent bilirubin elevation.

CONCLUSION

Ubrogepant was well tolerated following intermittent, high-frequency dosing in healthy participants, with no clinically relevant signal of hepatotoxicity.

TRIAL REGISTRATION

NA.

Problematic presentation and use of efficacy measures in current trials of CGRP monoclonal antibodies for episodic migraine prevention: A mini-review

Background

In trials of monoclonal antibodies against calcitonin gene-related peptide or its receptor for prevention of episodic migraine, we observed two problematic aspects: a) The graphic presentations; b) the methods of calculating “response rates” (≥50% decrease of monthly migraine days from baseline).

Observations

Decrease in monthly migraine days is presented, over time, in figures on a downward (negative) scale from zero at baseline, with the ordinate stopped just beyond the maximum effect of the active drugs. In one trial, decreases in monthly migraine days were −1.8 after placebo, −3.2 after erenumab 70 mg and −3.7 after erenumab 140 mg, with the ordinate stopped at −4.5. The reader can perceive only a relative 2-fold benefit of erenumab versus placebo. If, however, treatment periods are compared with baseline in bar charts, MMDs persisting after treatment in the same trial can be illustrated as follows, creating a different perception: 78% for placebo, 61% for erenumab 70 mg, and 55% for erenumab 140 mg. In the nine trials, “response rates” defined as above were calculated in five different ways, taking different numbers of treatment months into account in comparisons with the one-month baseline. This makes comparisons impossible.

Suggestions for improvements

Mean monthly migraine days before and after treatment should be presented in a bar chart. Such figures, presenting persisting MMDs, are more clinically relevant and less misleading than decreases from baseline. The definition and methods of calculating and presenting “50% response rates” should be standardized by the Drug Trial Committee of the International Headache Society.

CGRP in Animal Models of Migraine

With the approval of calcitonin gene-related peptide (CGRP) and CGRP receptor monoclonal antibodies by the Federal Drug Administration, a new era in the treatment of migraine patients is beginning. However, there are still many unknowns in terms of CGRP mechanisms of action that need to be elucidated to allow new advances in migraine therapies. CGRP has been studied both clinically and preclinically since its discovery. Here we review some of the preclinical data regarding CGRP in animal models of migraine.

Onset of efficacy and duration of response of galcanezumab for the prevention of episodic migraine: a post-hoc analysis

BACKGROUND AND OBJECTIVE

As new migraine prevention treatments are developed, the onset of a preventive effect, how long it is maintained and whether patients initially non-responsive develop clinically meaningful responses with continued treatment can be assessed.

METHODS

Analyses were conducted post-hoc of a double-blind, placebo-controlled, phase II-a study in patients with episodic migraine receiving galcanezumab 150 mg or placebo biweekly for 12 weeks (Lancet Neurol 13:885, 2014). The number of migraine headache days per week, and onset of efficacy measured as the first week galacanezumab separated from placebo were determined. Patients with ≥50%, ≥75% and 100% reduction in migraine headache days from baseline at months 1, 2 and 3 were calculated and defined as sustained responses. Non-responders (<50% response) at month 1 or 2 who then showed ≥50%, ≥75% and 100% response at later time-points were calculated.

RESULTS

Patients were randomised to galcanezumab (n=107) or placebo (n=110). A significant (p=0.018) change of -0.89±0.11 (galcanezumab) vs -0.53±0.11 (placebo) migraine headache days indicated onset at week 1. Forty-seven per cent of galcanezumab and 25% of placebo patients responding at month 1 maintained response through months 2 and 3. Of non-responders at month 1, 27% on galcanezumab and 20% on placebo responded on months 2 and 3, and 50% of galcanezumab non-responders in months 1 and 2 responded on month 3, vs 24% on placebo.

CONCLUSIONS

The onset of efficacy of galcanezumab is within 1 week in a majority of patients, and patients receiving galcanezumab are twice more likely to maintain responses than placebo patients. Early non-responders may respond by month 2 or month 3.

TRIAL REGISTRATION NUMBER

NCT01625988.

The discovery and development of inhaled therapeutics for migraine

INTRODUCTION

Migraine is a disabling primary headache disorder that requires effective treatments. Inhalation is currently being explored for the delivery of drugs for migraine. Pulmonary-route delivery of drugs shows potential advantages for its use as a treatment, particularly compared the oral route. Areas covered: The authors highlight the current state of the literature and review multiple therapies for migraine-utilizing inhalation as the route of administration. The following therapeutics are discussed: inhaled ergotamine, inhaled dihydroergotamine mesylate (MAP0004), inhaled prochlorperazine, and inhaled loxapine. Coverage is also given to normobaric oxygen, hyperbaric oxygen, and nitrous oxide therapies. Expert opinion: Inhalation of MAP0004 showed promising results in terms of efficacy for acute migraine treatment in phase 3 studies, together with a more favorable tolerability profile compared to parenteral dosing and a better pharmacokinetic profile versus oral or intranasal delivery. In phase 2 trials, inhaled prochlorperazine shows good pharmacokinetics and efficacy, in contrast to inhaled loxapine that did not provide encouraging results in terms of efficacy. The authors see the potential for the use of dihydroergotamine mesylate in clinical practice pending regulatory approval.

Divergent influences of the locus coeruleus on migraine pathophysiology

Migraine is a common disabling neurological condition that is associated with several premonitory symptoms that can occur days before the headache onset. The most commonly reported premonitory symptom is marked fatigue that has been shown to be highly predictive of an ensuing migraine attack. The locus coeruleus (LC) is a key nucleus involved in arousal that has also been shown to impact pain processing. It provides one of the major sources of noradrenaline to the dorsal horn of the spinal cord and neocortex. Given the clinical association between migraine, sleep-wake regulation, and fatigue, we sought to determine whether LC modulation could impact migraine-related phenotypes in several validated preclinical models of migraine. To determine its role in migraine-related pain, we recorded dural nociceptive-evoked responses of neurons in the trigeminocervical complex, which receives trigeminal primary afferents from the durovascular complex. In addition, we explored the susceptibility to cortical spreading depression initiation, the presumed underlying phenomenon of migraine aura. Our experiments reveal a potent role for LC disruption in the differential modulation of migraine-related phenotypes, inhibiting dural-evoked activation of wide dynamic neurons in the trigeminocervical complex while increasing cortical spreading depression susceptibility. This highlights the potential divergent impact of LC disruption in migraine physiology, which may help explain the complex interactions between dysfunctional arousal mechanisms and migraine.

Peripherally administered calcitonin gene-related peptide induces spontaneous pain in mice: implications for migraine

Migraine is the third most common disease in the world (behind dental caries and tension-type headache) with an estimated global prevalence of 15%, yet its etiology remains poorly understood. Recent clinical trials have heralded the potential of therapeutic antibodies that block the actions of the neuropeptide calcitonin gene-related peptide (CGRP) or its receptor to prevent migraine. Calcitonin gene-related peptide is believed to contribute to trigeminal nerve hypersensitivity and photosensitivity in migraine, but a direct role in pain associated with migraine has not been established. In this study, we report that peripherally administered CGRP can act in a light-independent manner to produce spontaneous pain in mice that is manifested as a facial grimace. As an objective validation of the orbital tightening action unit of the grimace response, we developed a squint assay using a video-based measurement of the eyelid fissure, which confirmed a significant squint response after CGRP injection, both in complete darkness and very bright light. These indicators of discomfort were completely blocked by preadministration of a monoclonal anti-CGRP-blocking antibody. However, the nonsteroidal anti-inflammatory drug meloxicam failed to block the effect of CGRP. Interestingly, an apparent sex-specific response to treatment was observed with the antimigraine drug sumatriptan partially blocking the CGRP response in male, but not female mice. These results demonstrate that CGRP can induce spontaneous pain, even in the absence of light, and that the squint response provides an objective biomarker for CGRP-induced pain that is translatable to humans.

Refining the Benefit/Risk Profile of Anti-Epileptic Drugs in Headache Disorders

Anti-epileptic drugs are among the most effective drugs for migraine prophylaxis, and will likely continue to have a role even as new therapies emerge. Topiramate and valproate are effective for the preventive treatment of migraine, and other medications such as gabapentin or lamotrigine may have a role in the treatment of those with allodynia or frequent aura, respectively. Oxcarbazepine, carbamazepine, phenytoin, gabapentin, and others may alleviate pain in trigeminal neuralgia. While many anti-epileptic drugs can be effective in those with migraine or other headaches, most of these agents can potentially cause serious side effects. In particular, valproate, topiramate, carbamazepine, and phenytoin may lead to adverse outcomes for infants of exposed mothers. Valproate should not be given to women of childbearing potential for migraine prevention.

Cortical spreading depression as a site of origin for migraine: Role of CGRP

PREMISE

Migraine is a complex neurologic disorder that leads to significant disability, yet remains poorly understood.

PROBLEM

One potential triggering mechanism in migraine with aura is cortical spreading depression, which can activate the trigeminal nociceptive system both peripherally and centrally in animal models. A primary neuropeptide of the trigeminal system is calcitonin gene-related peptide, which is a potent vasodilatory peptide and is currently a major therapeutic target for migraine treatment. Despite the importance of both cortical spreading depression and calcitonin gene-related peptide in migraine, the relationship between these two players has been relatively unexplored. However, recent data suggest several potential vascular and neural connections between calcitonin gene-related peptide and cortical spreading depression.

CONCLUSION

This review will outline calcitonin gene-related peptide-cortical spreading depression connections and propose a model in which cortical spreading depression and calcitonin gene-related peptide act at the intersection of the vasculature and cortical neurons, and thus contribute to migraine pathophysiology.