Update on the Pharmacological Treatment of Chronic Migraine

Comparison of Greater Occipital Nerve Blockade and Sphenopalatine Ganglion Blockade in Patients with Episodic Migraine

Objectives: Compare the effects of greater occipital nerve (GON) and sphenopalatine ganglion (SPG) blocks on headache intensity and duration, number of headache days, and disability in patients with episodic migraine. Methods: In this prospective single-blind randomized study, patients with episodic migraine were randomly divided into two groups: GON and SPG block groups. Patients received blocks once a week for 4 weeks, and once a month for 2 months. The number of headache days, the headache duration, numeric rating scale (NRS) scores, and number of acute medical treatments were assessed before the procedures and 1 month, 2 months, and 3 months after the procedures. Disability was evaluated using the migraine disability assessment (MIDAS) questionnaire at baseline and 3 months after treatment. This study protocol is registered at ClinicalTrials.gov (NCT06243874.). Results: 19 patients in the GON block group and 18 patients in the SPG block group were evaluated. Significant improvements in pain severity, headache duration, number of headache days, and the need for acute medical treatment were observed in the 1st, 2nd, and 3rd months compared to baseline in the two groups (p < 0.001). There were significant improvements in the MIDAS scores in the third month (p < 0.001). The GON block group showed a greater reduction in headache intensity, duration, number of headache days, and MIDAS scores compared to the SPG block group in the 3rd month (p < 0.001). Conclusions: GON block reduces headache duration, intensity, the number of headache days, and the need for acute medical treatment much more than SPG block in patients with episodic migraine.

Role of Vagus Nerve Stimulation in the Treatment of Chronic Pain

Vagus nerve stimulation (VNS) can modulate vagal activity and neuro-immune communication. Human and animal studies have provided growing evidence that VNS can produce analgesic effects in addition to alleviating refractory epilepsy and depression. The vagus nerve (VN) projects to many brain regions related to pain processing, which can be affected by VNS. In addition to neural regulation, the anti-inflammatory property of VNS may also contribute to its pain-inhibitory effects. To date, both invasive and noninvasive VNS devices have been developed, with noninvasive devices including transcutaneous stimulation of auricular VN or carotid VN that are undergoing many clinical trials for chronic pain treatment. This review aimed to provide an update on both preclinical and clinical studies of VNS in the management for chronic pain, including fibromyalgia, abdominal pain, and headaches. We further discuss potential underlying mechanisms for VNS to inhibit chronic pain.

Sex Differences in Chronic Migraine: Focusing on Clinical Features, Pathophysiology, and Treatments

PURPOSE OF REVIEW

This review provides an update on sex differences in chronic migraine (CM), with a focus on clinical characteristics, pathophysiology, and treatments.

RECENT FINDINGS

Approximately 6.8-7.8% of all migraineurs have CM, with an estimated prevalence of 1.4-2.2% in the general population. The economic burden caused by CM, including medical costs and lost working ability, is threefold higher than that caused by episodic migraine (EM). Notably, the prevalence of migraine is affected by age and sex. Female migraineurs with CM experience higher levels of headache-related disability, including longer headache duration, higher frequency of attacks, and more severely impacted efficiency at work. Sex hormones, including estrogen, testosterone, and progesterone, contribute to the sexually dimorphic characteristics and prevalence of migraine in men and women. Recent neuroimaging studies have indicated that migraine may have a greater impact and cause greater dysfunction in the organization of resting-state functional networks in women. Accumulating evidence suggests that topiramate, Onabotulinumtoxin A and calcitonin gene-related peptide (CGRP) monoclonal antibodies are effective as the preventative treatments for CM. Recent evidence highlights a divergence in the characteristics of CM between male and female populations. The data comparing the treatment response for CM regarding sex are lacking.

Nerivio® remote electrical neuromodulation for acute treatment of chronic migraine

Nerivio^® (by Theranica Bio-Electronics Ltd, Tel Aviv, Israel) is a wireless, wearable, noninvasive, battery-operated, remote electrical neuromodulation device controlled by a smartphone application. It is US FDA authorized for the acute treatment of migraine with or without aura in people 12 years and older in the US, and European Conformity (CE) marked for the same indication in the EU. The American Headache Society Consensus Statement recommends Nerivio as a tier 2 treatment for migraines. This review summarizes a series of five independent clinical trials and two real-world evidence studies that established safety, tolerability and efficacy of Nerivio in treating migraine attacks. It further provides up-to-date practical information on device usability. Based on findings of this review, Nerivio offers a safe and effective nonpharmacological alternative for acute treatment in patients with chronic (and nonchronic) migraine.

Plasma Lipolysis and Changes in Plasma and Cerebrospinal Fluid Signaling Lipids Reveal Abnormal Lipid Metabolism in Chronic Migraine

Background

Lipids are a primary storage form of energy and the source of inflammatory and pain signaling molecules, yet knowledge of their importance in chronic migraine (CM) pathology is incomplete. We aim to determine if plasma and cerebrospinal fluid (CSF) lipid metabolism are associated with CM pathology.

Methods

We obtained plasma and CSF from healthy controls (CT, n = 10) or CM subjects (n = 15) diagnosed using the International Headache Society criteria. We measured unesterified fatty acid (UFA) and esterified fatty acids (EFAs) using gas chromatography-mass spectrometry. Glycerophospholipids (GP) and sphingolipid (SP) levels were determined using LC-MS/MS, and phospholipase A₂ (PLA₂) activity was determined using fluorescent substrates.

Results

Unesterified fatty acid levels were significantly higher in CM plasma but not in CSF. Unesterified levels of five saturated fatty acids (SAFAs), eight monounsaturated fatty acids (MUFAs), five ω-3 polyunsaturated fatty acids (PUFAs), and five ω-6 PUFAs are higher in CM plasma. Esterified levels of three SAFAs, eight MUFAs, five ω-3 PUFAs, and three ω-6 PUFAs, are higher in CM plasma. The ratios C20:4n-6/homo-γ-C20:3n-6 representative of delta-5-desaturases (D5D) and the elongase ratio are lower in esterified and unesterified CM plasma, respectively. In the CSF, the esterified D5D index is lower in CM. While PLA₂ activity was similar, the plasma UFA to EFA ratio is higher in CM. Of all plasma GP/SPs detected, only ceramide levels are lower (p = 0.0003) in CM (0.26 ± 0.07%) compared to CT (0.48 ± 0.06%). The GP/SP proportion of platelet-activating factor (PAF) is significantly lower in CM CSF.

Conclusions

Plasma and CSF lipid changes are consistent with abnormal lipid metabolism in CM. Since plasma UFAs correspond to diet or adipose tissue levels, higher plasma fatty acids and UFA/EFA ratios suggest enhanced adipose lipolysis in CM. Differences in plasma and CSF desaturases and elongases suggest altered lipid metabolism in CM. A lower plasma ceramide level suggests reduced de novo synthesis or reduced sphingomyelin hydrolysis. Changes in CSF PAF suggest differences in brain lipid signaling pathways in CM. Together, this pilot study shows lipid metabolic abnormality in CM corresponding to altered energy homeostasis. We propose that controlling plasma lipolysis, desaturases, elongases, and lipid signaling pathways may relieve CM symptoms.

Chronic Migraine Pathophysiology and Treatment: A Review of Current Perspectives

Chronic migraine is a disabling neurological disorder that imposes a considerable burden on individual and socioeconomic outcomes. Chronic migraine is defined as headaches occurring on at least 15 days per month with at least eight of these fulfilling the criteria for migraine. Chronic migraine typically evolves from episodic migraine as a result of increasing attack frequency and/or several other risk factors that have been implicated with migraine chronification. Despite this evolution, chronic migraine likely develops into its own distinct clinical entity, with unique features and pathophysiology separating it from episodic migraine. Furthermore, chronic migraine is characterized with higher disability and incidence of comorbidities in comparison to episodic migraine. While existing migraine studies primarily focus on episodic migraine, less is known about chronic migraine pathophysiology. Mounting evidence on aberrant alterations suggest that pronounced functional and structural brain changes, central sensitization and neuroinflammation may underlie chronic migraine mechanisms. Current treatment options for chronic migraine include risk factor modification, acute and prophylactic therapies, evidence-based treatments such as onabotulinumtoxinA, topiramate and newly approved calcitonin gene-related peptide or receptor targeted monoclonal antibodies. Unfortunately, treatments are still predominantly ineffective in aborting migraine attacks and decreasing intensity and frequency, and poor adherence and compliance with preventative medications remains a significant challenge. Novel emerging chronic migraine treatments such as neuromodulation offer promising therapeutic approaches that warrant further investigation. The aim of this narrative review is to provide an update of current knowledge and perspectives regarding chronic migraine background, pathophysiology, current and emerging treatment options with the intention of facilitating future research into this debilitating and largely indeterminant disorder.

Calcitonin Gene-Related Peptide (CGRP) Antagonists: A comprehensive review of safety, efficacy and prescribing information

WHAT IS KNOWN AND OBJECTIVES

Migraine is a disabling disorder that affects individuals of all ages. To date, there are multiple limitations to using guidelines-recommended treatments and preventive therapies. The goal of this review was to provide a comprehensive clinical review of the safety, efficacy and prescribing information of the emerging calcitonin gene-related peptide (CGRP) antagonists. Agents in this new pharmacologic class were approved by the US Food and Drug Administration (FDA) for the treatment of acute migraine attack pain and the management of episodic and chronic migraine.

METHODS

A total of 12 randomized, placebo-controlled clinical trials were identified and included in the review utilizing databases such as clinicaltrial.gov, PubMed and EMBASE. The trials collectively evaluated six CGRP antagonists starting from the orally administered CGRPs such as rimegepant and ubrogepant, to the quarterly IV administered CGRP such as eptinezumab, and the monthly/quarterly subcutaneously administered agents such as erenumab, fremanezumab and galcanezumab.

RESULTS AND DISCUSSION

All agents displayed significant efficacy compared with placebo, measured by reduction in mean monthly migraine days (MMD). In addition, CGRP antagonists displayed a great tolerability profile with few adverse effects. These medications were neither associated with any cardiovascular-related adverse effects, nor do they currently have specific contraindications to pre-existing cardiovascular conditions. This can present a safe alternative to a wide range of patients who cannot be appropriately treated with first-line treatments such as triptans. No treatment-related death was reported in any of the clinical trials outlined and discussed.

WHAT IS NEW AND CONCLUSION

Calcitonin gene-related peptide antagonists are safe and efficacious medications both in treating acute migraine headache pain and the management of episodic and chronic migraine. Head-to-head comparative studies with current guideline-recommended treatments are needed. However, CGRP antagonists are promising agents that present an alternative solution for patients living with migraine.

Safety and tolerability of preventive treatment options for chronic migraine

INTRODUCTION

Relative to migraine generally, chronic migraine (CM) imposes greater disability, healthcare utilization and socioeconomic burden. Six therapies currently possess a credible evidence base for prevention/suppression of CM. This review is intended to provide an assessment of their relative utility, defined as a blend of safety, tolerability and efficacy, focusing in particular on their safety and tolerability.Areas Covered: We discuss all six medications currently FDA-approved for migraine prevention which also specifically possess credible evidence of efficacy in treating CM. While we do address the efficacy of each, our primary emphasis involves assessment of safety and tolerability data derived from clinical trials and post-marketing experience.Expert Opinion: Recent research involving CM has led to the identification of highly targeted and typically well-tolerated therapies. For patients who experience obstacles to accessing these newer therapies, topiramate is available as an evidence-based alternative, but contraindications, drug-drug interactions and poor tolerability may limit or prevent its use. Although data to support such intervention presently is limited, clinically challenging CM cases may benefit from combination therapy. 'Real world' studies are needed to evaluate such polytherapy, along with studies intended to assess the long-term safety of the individual therapies and their use during pregnancy and breast-feeding.

What is changing in chronic migraine treatment? An algorithm for onabotulinumtoxinA treatment by the Italian chronic migraine group

INTRODUCTION

OnabotulinumtoxinA (OBT-A) and monoclonal antibodies (mAbs) targeting the calcitonin gene-related peptide (CGRP) pathway are two of the few treatments that ameliorate chronic migraine (CM) in randomized controlled trials and real-life studies. Separate clinical practice guidelines have been developed for the management of CM with OBT-A or CGRP-targeting mAbs.

AREAS COVERED

Considering the concomitant availability of OBT-A and CGRP-targeting mAbs as therapeutic treatment options, Italian migraine experts reviewed the evidence supporting the efficacy of OBT-A and CGRP-targeting mAbs in CM in order to rationalize the management of CM patients treated with OBT-A. Experts addressed everyday practice needs to shape the optimal pharmacological management by balancing adherence to regulatory indications, ethical considerations, and clinical expertise. Considering the remarkable challenge of improving the health and quality of life of patients with CM, even partial improvements may be clinically meaningful, particularly for those who are resistant or intolerant to oral migraine treatments.

EXPERT OPINION

In this collaborative effort, we propose a treatment algorithm that integrates the relevant aspects of managing patients with CM to provide ready-to-use practical guidance regarding the appropriate use of OBT-A.

Influence of headache pain intensity and frequency on migraine-related disability in chronic migraine patients treated with OnabotulinumtoxinA

Background

There is a need to establish which are the more relevant headache-related outcomes that have an impact on our patient’s lives to accurately evaluate treatment response in daily clinical practice.

Objective

The aim of this study was to evaluate the relevance of clinical trial endpoints in clinical real-life disability improvement in response to migraine preventive treatment with OnabotulinumtoxinA.

Methods

This is an observational prospective study. We included patients with chronic migraine fulfilling ICHD-3beta/3 criteria. We prospectively collected data of 8 headache-related and acute medication use endpoints recommended by the Guidelines of the International Headache Society for controlled trials of preventive treatment of chronic migraine. We evaluated their impact on disability improvement after 6 months of treatment with OnabotulinumtoxinA. We defined as a responder in disability, patients with ≥50% MIDAS score reduction after 2 cycles of treatment following PREEMPT protocol. We performed an analysis to measure the impact of improvement in the evaluated outcome measures according to perceived disability in clinical practice.

Results

We included 395 patients (85.1% women, mean age 46.7 ± 12.6 years). Mean headache frequency at baseline was 26.5 ± 5.2 headache days/month. After 6 months, 49.1% of patients were headache-related disability responders. From all outcome measures collected, variables independently associated to disability improvement were headache days reduction (p = 0.02) and ≥ 50% pain intensity reduction (p = 0.04). A ≥ 50% reduction in headache frequency or pain intensity showed similar influence on disability improvement after treatment.

Conclusions

Headache pain intensity is as important as frequency when evaluating the clinical response and impact on patient headache-related disability after migraine preventive treatment with OnabotulinumtoxinA.

Transcutaneous Supraorbital Stimulation as a Preventive Treatment for Chronic Migraine: A Prospective, Open-Label Study

BACKGROUND AND OBJECTIVE

Successful preventive treatment in chronic migraine (CM) remains an unmet need in some cases, and new therapeutic strategies are emerging. We aimed to test the effect of noninvasive, transcutaneous supraorbital nerve stimulation (tSNS) in a group of patients with CM.

PATIENTS AND METHODS

This was an open label, quasi-experimental design. Twenty-five CM patients were recruited from two hospital headache clinics. After a one-month baseline period, monthly visits were scheduled during three months. Headache occurrence, its intensity, and symptomatic medication intake were recorded through a diary kept by each patient. Both a per-protocol analysis and an intention-to-treat analysis were performed for the main outcome measures.

RESULTS

Twenty-one and 24 patients were included in the per-protocol and the intention-to-treat analyses, respectively. In the per-protocol analysis, a significant four-day decrease in the mean monthly days with moderate or severe headache was observed from baseline to the end of the study (t test, P = 0.0163), and there was a nonsignificant reduction of 2.95 in the mean monthly total headache days. In the intention-to-treat analysis, a nonsignificant 3.37 reduction in the mean monthly days with moderate or severe headache was observed for the same period, and there was a significant 2.75 reduction in the mean monthly days with any headache (t test, P = 0.016).

CONCLUSIONS

tSNS could hold preventive properties in the treatment of CM, but the effect may be either mild or controversial. Double blind, sham-controlled studies are essential to confirm these findings and to outline their clinical relevance in the CM therapeutic scenario.

Images depicting headache pain - a tool to aid the diagnosis of cluster headache: a pilot study

Introduction and objective

The diagnosis of primary headaches is based on the International Classification of Headache Disorders (ICHD-3). Cluster headache (CH), a debilitating primary headache, is often misdiagnosed as migraine. In the absence of biological markers, a new visual screening tool with images depicting pain could aid the correct diagnosis of CH. The objective of the study is to test the tool on healthy participants and participants with CH and migraine.

Methods

In phase 1, 6 images portraying people with pain were tested on 150 healthy participants. The healthy participants were asked to rate the images as mild, moderate, severe or excruciating pain. In phase 2, the images were further tested on 116 participants with headache (16 participants with CH, 100 participants with migraine). The participants were recruited prospectively from a tertiary headache center between February and May 2017. The participants were asked to choose which image best illustrated their headache attacks.

Results

Phase 1 results showed that the images represent a range of headache pain severities from mild to excruciating as rated by healthy participants. They rated two images as excruciating, one image as severe, one image as moderate/severe, one image as moderate and one image as mild. Phase 2 results showed that two-thirds of participants with CH (69%) and half of the participants with migraine (52%) chose an image described as excruciating by the healthy participants.

Conclusion

We developed a screening tool with six drawings depicting headache pain severities from mild to excruciating as rated by the healthy participants. Although the images did not differentiate between CH and migraine, the study indicated the potential of using visual aids to assess headache severity.

Current and emerging evidence-based treatment options in chronic migraine: a narrative review

Background

Chronic migraine is a disabling condition that is currently underdiagnosed and undertreated. In this narrative review, we discuss the future of chronic migraine management in relation to recent progress in evidence-based pharmacological treatment.

Findings

Patients with chronic migraine require prophylactic therapy to reduce the frequency of migraine attacks, but the only currently available evidence-based prophylactic treatment options for chronic migraine are topiramate and onabotulinumtoxinA. Improved prophylactic therapy is needed to reduce the high burden of chronic migraine in Italy. Monoclonal antibodies that target the calcitonin gene-related peptide (CGRP) pathway of migraine pathogenesis have been specifically developed for the prophylactic treatment of chronic migraine. These anti-CGRP/R monoclonal antibodies have demonstrated good efficacy and excellent tolerability in phase II and III clinical trials, and offer new hope to patients who are currently not taking any prophylactic therapy or not benefitting from their current treatment.

Conclusions

Treatment of chronic migraine is a dynamic and rapidly advancing area of research. New developments in this field have the potential to improve the diagnosis and provide more individualised treatments for this condition. Establishing a culture of prevention is essential for reducing the personal, social and economic burden of chronic migraine.

Basic Considerations for the Use of Monoclonal Antibodies in Migraine

BACKGROUND

Migraine impacts more than 36 million people in the United States and 1 billion people worldwide. Despite the increasing availability of acute and preventive therapies, there is still tremendous unmet need. Potential treatments in development include monoclonal antibodies (mAbs). Appropriate use of these “biologic” treatments will necessitate an understanding of the aspects that distinguish them from traditional medications.

AIM

Many drug classes are prescribed for migraine treatment, but all have limitations. Recently, calcitonin gene-related peptide (CGRP) activity has shown a significant promise as a target for preventive therapy. In this review, we provide an overview of the potential role of CGRP mAbs in migraine, with a focus on their design, pharmacokinetics, safety, and immunogenicity.

CONCLUSIONS

The CGRP mAbs are an innovative new therapy for migraine and address the need for effective and tolerable preventive options. MAbs, including those that target CGRP or its receptor, bind to a target with high specificity and affinity and lead to few off-target adverse effects, although mechanism-based adverse reactions may occur. Unlike other therapeutic antibodies used to treat neurologic disease, CGRP mAbs do not have a target within the immune system and have been designed to avoid altering the immune system. The safety and efficacy of mAbs against CGRP or its receptors are being investigated in clinical development programs, and the first of these therapies has received regulatory approval in the United States.

Use of occipital nerve block in emergency department treatment of status migrainosus

Migraine headaches make up a significant proportion of emergency department visits. There are multiple pharmacologic treatment modalities for migraine abortive therapy; however, these treatments are rarely targeted to the precise area of pain and thus elicit multiple systemic effects. It has been well established in the anesthesia pain literature that occipital nerve blocks can provide not only immediate pain relief from occipital migraines, but can also result in a long-term resolution of occipital migraines. In this case report, we present how an occipital nerve block in the emergency department resulted in immediate and long-lasting resolution of a patient's occipital migraine.

OnabotulinumtoxinA: A Review in the Prevention of Chronic Migraine

An intramuscular formulation of onabotulinumtoxinA (onabotA; Botox®) is currently the only therapy specifically approved for the prevention of headaches in adults with chronic migraine (CM) in the EU and North America. This article provides a narrative review of relevant data on the drug in this indication from an EU perspective. OnabotA was originally approved on the basis of pooled data from two phase III studies (PREEMPT 1 and 2). In these pivotal studies, injection of up to five cycles of onabotA (155-195 U/cycle) at 12-week intervals was generally well tolerated and effective in producing statistically significant and clinically meaningful improvements in headache symptoms, acute headache pain medication usage, headache impact and health-related quality of life in adults with CM, of whom approximately two-thirds were acute medication overusers and approximately one-third had failed to respond to ≥ 3 prior oral prophylactic therapies. More recently, the efficacy and tolerability of onabotA over a period of 1 year in the PREEMPT programme has been substantiated and extended by the results of a long-term phase IV study (COMPEL), in which patients received up to nine treatment cycles over a period of 2 years, and by findings from several real-world clinical practice studies from Europe, including the prospective multinational REPOSE and CM-PASS studies. In conclusion, the totality of evidence from clinical trials and real-world studies indicates that onabotA is an effective and generally well tolerated option for the prevention of CM that may be particularly useful for patients who have previously failed to respond to or are intolerant of commonly prescribed oral prophylactics.

The efficacy of greater occipital nerve block for the treatment of migraine: A systematic review and meta-analysis

Greater occipital nerve (GON) block has some potential in treating migraine. We conduct a systematic review and meta-analysis to investigate the impact of GON block on pain management of migraine. We have systematically searched randomized controlled trials (RCTs) assessing the efficacy of GON block versus placebo for migraine in various databases including PubMed, EMbase, Web of science, EBSCO, and Cochrane library databases. The primary outcome is pain intensity. Meta-analysis is performed using the random-effect model. Seven RCTs are included in the meta-analysis. Compared with control intervention in migraine patients, GON block intervention can significantly reduce pain intensity (Mean difference = -1.24; 95% CI = -1.98 to -0.49; P = 0.001) and analgesic medication consumption (Mean difference = -1.10; 95% CI = -2.07 to -0.14; P = 0.02), but has no remarkable impact on head duration (Mean difference = -6.96; 95% CI = -14.09 to 0.18; P = 0.0.06) and adverse events (RR = 0.93; 95% CI = 0.52 to 1.65; P = 0.80). GON block intervention is able to significantly reduce pain intensity and analgesic medication consumption in migraine patients.

Chronic migraine: risk factors, mechanisms and treatment

Chronic migraine has a great detrimental influence on a patient's life, with a severe impact on socioeconomic functioning and quality of life. Chronic migraine affects 1-2% of the general population, and about 8% of patients with migraine; it usually develops from episodic migraine at an annual conversion rate of about 3%. The chronification is reversible: about 26% of patients with chronic migraine go into remission within 2 years of chronification. The most important modifiable risk factors for chronic migraine include overuse of acute migraine medication, ineffective acute treatment, obesity, depression and stressful life events. Moreover, age, female sex and low educational status increase the risk of chronic migraine. The pathophysiology of migraine chronification can be understood as a threshold problem: certain predisposing factors, combined with frequent headache pain, lower the threshold of migraine attacks, thereby increasing the risk of chronic migraine. Treatment options include oral medications, nerve blockade with local anaesthetics or corticoids, and neuromodulation. Well-defined diagnostic criteria are crucial for the identification of chronic migraine. The International Headache Society classification of chronic migraine was recently updated, and now allows co-diagnosis of chronic migraine and medication overuse headache. This Review provides an up-to-date overview of the classification of chronic migraine, basic mechanisms and risk factors of migraine chronification, and the currently established treatment options.

Short-term effects of greater occipital nerve blocks in chronic migraine: A double-blind, randomised, placebo-controlled clinical trial

Background Greater occipital nerve (GON) blocks are widely used for the treatment of headaches, but quality evidence regarding their efficacy is scarce. Objective The objective of this article is to assess the short-term clinical efficacy of GON anaesthetic blocks in chronic migraine (CM) and to analyse their effect on pressure pain thresholds (PPTs) in different territories. Participants and methods The study was designed as a double-blind, randomised, placebo-controlled clinical trial. Thirty-six women with CM were treated either with bilateral GON block with bupivacaine 0.5% ( n = 18) or a sham procedure with normal saline ( n = 18). Headache frequency was recorded a week after and before the procedure. PPT was measured in cephalic points (supraorbital, infraorbital and mental nerves) and extracephalic points (hand, leg) just before the injection (T0), one hour later (T1) and one week later (T2). Results Anaesthetic block was superior to placebo in reducing the number of days per week with moderate-or-severe headache (MANOVA; p = 0.027), or any headache ( p = 0.04). Overall, PPTs increased after anaesthetic block and decreased after placebo; after the intervention, PPT differences between baseline and T1/T2 among groups were statistically significant for the supraorbital (T0-T1, p = 0.022; T0-T2, p = 0.031) and infraorbital sites (T0-T1, p = 0.013; T0-T2, p = 0.005). Conclusions GON anaesthetic blocks appear to be effective in the short term in CM, as measured by a reduction in the number of days with moderate-to-severe headache or any headache during the week following injection. GON block is followed by an increase in PPTs in the trigeminal area, suggesting an effect on central sensitisation at the trigeminal nucleus caudalis. This trial is registered at ClinicalTrials.gov (NCT02188394).

Immunohistochemical localization of the calcitonin gene-related peptide binding site in the primate trigeminovascular system using functional antagonist antibodies

Calcitonin gene-related peptide (CGRP) is a potent vasodilator and a neuromodulator implicated in the pathophysiology of migraine. It binds to the extracellular domains of calcitonin receptor-like receptor (CLR) and receptor activity-modifying protein (RAMP) 1 that together form the CGRP receptor. Antagonist antibodies against CGRP and its binding site at the receptor are clinically effective in preventing migraine attacks. The blood-brain barrier penetration of these antagonist antibodies is limited, suggesting that a potential peripheral site of action is sufficient to prevent migraine attacks. To further understand the sites of CGRP-mediated signaling in migraine, we used immunohistochemical staining with recently developed antagonist antibodies specifically recognizing a fusion protein of the extracellular domains of RAMP1 and CLR that comprise the CGRP binding pocket at the CGRP receptor in monkey and man. We confirmed binding of the antagonist antibodies to human vascular smooth muscle cells (VSMCs) of dural meningeal arteries and neurons in the trigeminal ganglion, both of which are likely sites of action for therapeutic antibodies in migraine patients. We further used one of these antibodies for detailed mapping on cynomolgus monkey tissue and found antagonist antibody binding sites at multiple levels in the trigeminovascular system: in the dura mater VSMCs, in neurons and satellite glial cells in the trigeminal ganglion, and in neurons in the spinal trigeminal nucleus caudalis. These data reinforce and clarify our understanding of CGRP receptor localization in a pattern consistent with a role for CGRP receptors in trigeminal sensitization and migraine pathology.