The trigeminovascular system and migraine: studies characterizing cerebrovascular and neuropeptide changes seen in humans and cats

Inhibition of persistent sodium current reduces spreading depression-evoked allodynia in a mouse model of migraine with aura

ABSTRACT

We investigated the efficacy of inhibiting persistent Na + currents (I NaP ) in acute rodent models of migraine with aura. Cortical spreading depression (SD) is a slow wave of neuronal and glial depolarization that underlies the migraine aura. Minimally invasive optogenetic SD (opto-SD) causes periorbital mechanical allodynia in mice, suggesting SD activates trigeminal nociceptors. Persistent Na + currents contribute to neuronal intrinsic excitability and have been implicated in peripheral and cortical excitation. We examined a preferential inhibitor of I NaP, GS-458967, on SD-induced periorbital allodynia, SD susceptibility, and formalin-induced peripheral pain. Periorbital mechanical allodynia was tested in male and female Thy1-ChR2-YFP mice after a single opto-SD event using manual von Frey monofilaments. GS-458967 (1 mg/kg, s.c.) or vehicle was dosed immediately after opto-SD induction, and allodynia was tested 1 hour later. The electrical SD threshold and KCl-induced SD frequency were examined in the cortex in male Sprague-Dawley rats after 1 hour pretreatment with GS-458967 (3 mg/kg, s.c.) or vehicle. Effects of GS-458967 (0.5-5 mg/kg, p.o.) on spontaneous formalin hind paw behavior and locomotion were also examined in male CD-1 mice. GS-458967 suppressed opto-SD-induced periorbital allodynia and decreased susceptibility to SD. GS-458967 also diminished early and late phase formalin-induced paw-licking behavior with early phase paw licking responding to lower doses. GS-458967 up to 3 mg/kg had no impact on locomotor activity. These data provide evidence that I NaP inhibition can reduce opto-SD-induced trigeminal pain behavior and support I NaP inhibition as an antinociceptive strategy for both abortive and preventive treatment of migraine.

Pharmaceutical aspects of novel CGRP inhibitors used in the prophylaxis and treatment of migraine

Migraine is one of the most prevalent neurological disorders known to have an immense adverse socio-economic impact. Neurogenic inflammation is thought to mediate migraine, and CGRP is known to be released during acute attacks of migraine that causes vasodilation in extracerebral arteries. Hence, CGRP is believed to play a key role in triggering migraine. Although there are several classes of medications used in the prevention and treatment of migraine pain, targeted therapies are fewer. Therefore, CGRP receptor inhibitors which bind to CGRP receptors in the cranial vasculature have been developed as drugs for migraine therapy. In this review article, we describe the basic pathophysiologic mechanism that causes migraine headaches and the pharmacotherapeutic aspects of CGRP inhibitors available for clinical use. For the purpose of this review, a search was performed on the pharmacological, pharmacokinetic, pharmaceutical, and therapeutic aspects of the FDA-approved CGRP inhibitors viz. erenumab, ubrogepant, rimegepant, atogepant, eptinezumab, fremanezumab, and galcanezumab in UpToDate database and PubMed beginning year 2000. Based on the data collected, a risk-benefit comparison of different classes of novel CGRP inhibitors available for clinical use is provided. This comparative review may help the healthcare providers in choosing the best pharmacotherapeutic agent for their patients based on patient-specific information.

Update of Gepants in the Treatment of Chronic Migraine

PURPOSE OF REVIEW

Despite the unmet therapeutic needs of patients with chronic migraine (CM) and/or medication overuse, available treatment options are limited. Recently, four calcitonin gene-related peptide receptor antagonists, known as gepants, have been approved for the treatment of migraine. This review focuses on the preventive treatment of CM with gepants and highlights recent findings.

RECENT FINDINGS

Two randomized controlled trials (RCTs) have shown promising results for rimegepant and atogepant as preventive treatments for CM. In an RCT targeting patients with CM, atogepant demonstrated a significant reduction in the mean monthly migraine days, irrespective of acute medication overuse. Moreover, the patients reported no significant safety concerns and exhibited good tolerance to treatment. These findings highlight the potential of gepants as a new and effective therapeutic option for patients with CM and/or medication overuse. Gepant use will help improve the management and quality of life of individuals with this debilitating condition.

Serological Biomarkers of Chronic Migraine

PURPOSE OF REVIEW

Chronic migraine (CM) is a chronic form of migraine that differs from episodic migraine (EM) in terms of prevalence, comorbidities, response to treatment, and biomarkers. The aim of this review was to summarize the recent findings on serological biomarkers of CM.

RECENT FINDINGS

Neuronal, inflammatory, and vascular markers have been investigated to assess their diagnostic and prognostic ability and treatment effectiveness. Several markers showed significant alterations according to disease status and treatment response in CM. Calcitonin gene-related peptide (CGRP), glutamate, and adiponectin appear to be the most promising blood biomarkers for CM. Most studies have shown altered ictal and interictal levels of these markers in CM compared with those in EM and controls. Additionally, they showed a significant association with treatment outcomes. Total adiponectin and high-molecular-weight adiponectin levels were less studied as biomarkers of CM than CGRP and glutamate levels but showed promising results. The development of suitable biomarkers could revolutionize the diagnosis and treatment of CM and ultimately decrease the disability and societal costs of the disease.

Plasma calcitonin gene-related peptide and nerve growth factor as headache and pain biomarkers in recently deployed soldiers with and without a recent concussion

OBJECTIVE

The objective of this study was to characterize the utility of calcitonin gene-related peptide (CGRP) and nerve growth factor (NGF) as potential biomarkers for headache and pain disorders in the post-military deployment setting.

BACKGROUND

The need to improve recognition, assessment, and prognoses of individuals with posttraumatic headache or other pain has increased interest in the potential of CGRP and NGF as biomarkers.

METHODS

The Warrior Strong Study (NCT01847040) is an observational longitudinal study of United States-based soldiers who had recently returned from deployment to Afghanistan or Iraq from 2009 to 2014. The present nested cross-sectional analysis uses baseline data collected from soldiers returning to Fort Bragg, North Carolina.

RESULTS

In total, 264 soldiers (mean (standard deviation [SD] age 28.1 [6.4] years, 230/264 [87.1%] men, 171/263 [65.0%] White) were analyzed. Mean (SD) plasma levels of CGRP were 1.3 (1.1) pg/mL and mean levels of NGF were 1.4 (0.4) pg/mL. Age was negatively correlated with NGF (-0.01 pg/mL per year, p = 0.007) but was not associated with CGRP. Men had higher mean (SD) CGRP plasma levels than women (1.4 95% confidence interval [CI; 1.2] vs. 0.9 95% CI [0.5] pg/mL, p < 0.002, Kruskal-Wallis test). CGRP levels were lower in participants who had a headache at the time of the blood draw (1.0 [0.6] pg/mL vs. 1.4 [1.2] pg/mL, p = 0.024). NGF was lower in participants with continuous pain (all types; 1.2 [0.4] vs. 1.4 [0.4] pg/mL, p = 0.027) and was lower in participants with traumatic brain injury (TBI) + posttraumatic headache (PTH) versus TBI without PTH (1.3 [0.3] vs. 1.4 [0.4] pg/mL, p = 0.021). Otherwise, CGRP and NGF were not associated with migraine-like headache, TBI status, or headache burden as measured by the number of medical encounters in crude or adjusted models.

CONCLUSION

In this exploratory study, plasma levels of NGF and CGRP showed promise as biomarkers for headache and other types of pain. These findings need to be replicated in other cohorts.

Mode and site of action of therapies targeting CGRP signaling

Targeting CGRP has proved to be efficacious, tolerable, and safe to treat migraine; however, many patients with migraine do not benefit from drugs that antagonize the CGRPergic system. Therefore, this review focuses on summarizing the general pharmacology of the different types of treatments currently available, which target directly or indirectly the CGRP receptor or its ligand. Moreover, the latest evidence regarding the selectivity and site of action of CGRP small molecule antagonists (gepants) and monoclonal antibodies is critically discussed. Finally, the reasons behind non-responders to anti-CGRP drugs and rationale for combining and/or switching between these therapies are addressed.

Effects of CYP3A4 inhibition/induction and OATP inhibition on the pharmacokinetics of atogepant in healthy adults

Aim: Atogepant, a calcitonin gene-related peptide (CGRP) receptor antagonist, is a substrate of OATP and metabolized by CYP3A4. Effect of multiple-dose itraconazole (strong CYP3A4 inhibitor), single-dose rifampin (strong OATP inhibitor) and multiple-dose rifampin (strong CYP3A4 inducer) on single-dose pharmacokinetics (PK) and safety of atogepant were assessed. Methods: Two phase I, open-label, single-center, crossover trials enrolled healthy adults. Results: Cmax and AUC of atogepant increased when co-administered with itraconazole. Atogepant systemic exposure increased following co-administration with single-dose rifampin. Atogepant systemic exposure decreased with co-administration of multiple-dose rifampin. Treatment emergent adverse events (TEAEs) were predominantly mild or moderate, and included constipation, dizziness, headache and nauseas. Conclusion: Systemic exposure of atogepant increased significantly when co-administered with a strong CYP3A4 or OATP inhibitor and decreased significantly when co-administered with a strong CYP3A4 inducer.

The Role of Glial Cells in Different Phases of Migraine: Lessons from Preclinical Studies

Migraine is a complex and debilitating neurological disease that affects 15% of the population worldwide. It is defined by the presence of recurrent severe attacks of disabling headache accompanied by other debilitating neurological symptoms. Important advancements have linked the trigeminovascular system and the neuropeptide calcitonin gene-related peptide to migraine pathophysiology, but the mechanisms underlying its pathogenesis and chronification remain unknown. Glial cells are essential for the correct development and functioning of the nervous system and, due to its implication in neurological diseases, have been hypothesised to have a role in migraine. Here we provide a narrative review of the role of glia in different phases of migraine through the analysis of preclinical studies. Current evidence shows that astrocytes and microglia are involved in the initiation and propagation of cortical spreading depolarization, the neurophysiological correlate of migraine aura. Furthermore, satellite glial cells within the trigeminal ganglia are implicated in the initiation and maintenance of orofacial pain, suggesting a role in the headache phase of migraine. Moreover, microglia in the trigeminocervical complex are involved in central sensitization, suggesting a role in chronic migraine. Taken altogether, glial cells have emerged as key players in migraine pathogenesis and chronification and future therapeutic strategies could be focused on targeting them to reduce the burden of migraine.

Management of cluster headache: Treatments and their mechanisms

BACKGROUND

The management of cluster headache is similar to that of other primary headache disorders and can be broadly divided into acute and preventive treatments. Acute treatments for cluster headache are primarily delivered via rapid, non-oral routes (such as inhalation, nasal, or subcutaneous) while preventives include a variety of unrelated treatments such as corticosteroids, verapamil, and galcanezumab. Neuromodulation is becoming an increasingly popular option, both non-invasively such as vagus nerve stimulation when medical treatment is contraindicated or side effects are intolerable, and invasively such as occipital nerve stimulation when medical treatment is ineffective. Clinically, this collection of treatment types provides a range of options for the informed clinician. Scientifically, this collection provides important insights into disease mechanisms.

METHODS

Two authors performed independent narrative reviews of the literature on guideline recommendations, clinical trials, real-world data, and mechanistic studies.

RESULTS

Cluster headache is treated with acute treatments, bridge treatments, and preventive treatments. Common first-line treatments include subcutaneous sumatriptan and high-flow oxygen as acute treatments, corticosteroids (oral or suboccipital injections) as bridge treatments, and verapamil as a preventive treatment. Some newer acute (non-invasive vagus nerve stimulation) and preventive (galcanezumab) treatments have excellent clinical trial data for episodic cluster headache, while other newer treatments (occipital nerve stimulation) have been specifically tested in treatment-refractory chronic cluster headache. Most treatments are suspected to act on the trigeminovascular system, the autonomic system, or the hypothalamus.

CONCLUSIONS

The first-line treatments have not changed in recent years, but new treatments have provided additional options for patients.

Blocking the CGRP Receptor: Differences across Human Vascular Beds

Multiple drugs targeting the calcitonin gene-related peptide (CGRP) receptor have been developed for the treatment of migraine. Here, the effect of the small-molecule CGRP receptor antagonist zavegepant (0.1 nM-1 µM) on CGRP-induced relaxation in isolated human coronary arteries (HCAs) was investigated. A Schild plot was constructed and a pA2 value was calculated to determine the potency of zavegepant. The potency and Schild plot slopes of atogepant, olcegepant, rimegepant, telcagepant, ubrogepant and zavegepant in HCAs and human middle meningeal arteries (HMMAs), obtained from our earlier studies, were compared. Zavegepant shifted the concentration-response curve to CGRP in HCAs. The corresponding Schild plot slope was not different from unity, resulting in a pA2 value of 9.92 ± 0.24. No potency difference between HCAs and HMMAs was observed. Interestingly, olcegepant, atogepant and rimegepant, with a Schild plot slope < 1 in HCAs, were all >1 log unit more potent in HMMAs than in HCAs, while telcagepant, ubrogepant and zavegepant, with a Schild plot slope not different from unity, showed similar (<1 log difference) potency across both tissues. As a Schild plot slope < 1 may point to the involvement of multiple receptors, it is important to further identify the receptors involved in the relaxation to CGRP in HCAs, which may be used to improve the cardiovascular safety of future antimigraine drugs.

Molecular Mechanisms of Migraine: Nitric Oxide Synthase and Neuropeptides

Migraine is a common condition with disabling attacks that burdens people in the prime of their working lives. Despite years of research into migraine pathophysiology and therapeutics, much remains to be learned about the mechanisms at play in this complex neurovascular condition. Additionally, there remains a relative paucity of specific and targeted therapies available. Many sufferers remain underserved by currently available broad action preventive strategies, which are also complicated by poor tolerance and adverse effects. The development of preclinical migraine models in the laboratory, and the advances in human experimental migraine provocation, have led to the identification of key molecules likely involved in the molecular circuity of migraine, and have provided novel therapeutic targets. Importantly, the identification that vasoconstriction is neither necessary nor required for headache abortion has changed the landscape of migraine treatment and has broadened the therapy targets for patients with vascular risk factors or vascular disease. These targets include nitric oxide synthase (NOS) and several neuropeptides that are involved in migraine. The ability of NO donors and infusion of some of these peptides into humans to trigger typical migraine-like attacks has supported the development of targeted therapies against these molecules. Some of these, such as those targeting calcitonin gene-related peptide (CGRP), have already reached clinical practice and are displaying a positive outcome in migraineurs for the better by offering targeted efficacy without significant adverse effects. Others, such as those targeting pituitary adenylate cyclase activating polypeptide (PACAP), are showing promise and are likely to enter phase 3 clinical trials in the near future. Understanding these nitrergic and peptidergic mechanisms in migraine and their interactions is likely to lead to further therapeutic strategies for migraine in the future.

Evaluation of Plasma Calcitonin Gene-Related Peptide as a Biomarker for Painful Temporomandibular Disorder and Migraine

Objective

To assess associations of plasma calcitonin gene-related peptide (CGRP) with chronic temporomandibular disorder (TMD) myalgia/arthralgia or frequent/chronic migraine, alone and in combination, and to evaluate relations between the CGRP concentration and clinical, psychological, and somatosensory characteristics of participants.

Methods

The cross-sectional study selected four groups of adult volunteers: healthy controls (HCs), TMD without migraine, migraine without TMD, and TMD with migraine. Each group comprised 20 participants, providing 94% power to detect statistically significant associations with CGRP concentration for either TMD or migraine. TMD and headache were classified according to the Diagnostic Criteria for TMD and the International Classification for Headache Disorders, 3rd edition, respectively. Plasma CGRP was quantified with a validated high-sensitivity electrochemiluminescent Meso Scale Discovery assay. Questionnaires and clinical examinations were used to evaluate characteristics of TMD, headache, psychological distress, and pressure pain sensitivity. Univariate regression models quantified associations of the CGRP concentration with TMD, migraine, and their interaction. Univariate associations of the CGRP concentration with clinical, psychological, and pressure pain characteristics were also assessed.

Results

Among 80 participants enrolled, neither TMD nor migraine was associated with plasma CGRP concentration (P = 0.761 and P = 0.972, respectively). The CGRP concentration (mean ± SD) was similar in all 4 groups: HCs 2.0 ± 0.7 pg/mL, TMD 2.1 ± 0.8 pg/mL, migraine 2.1 ± 0.9 pg/mL, and TMD with migraine 2.2 ± 0.7 pg/mL. CGRP concentration was positively associated with age (P = 0.034) and marginally with body mass index (P = 0.080) but was unrelated to other participant characteristics.

Conclusion

In this well-powered study, interictal plasma concentration of CGRP was a poor biomarker for TMD and migraine.

Association Between Helicobacter pylori Infection and Migraine: A Systematic Review

Migraine is a highly debilitating disease affecting humans worldwide. Despite having known this disease for a long time, not many studies have been done to search for a chronic infectious cause of migraine. The goal of this study was to look for an association between migraine and Helicobacter pylori infection. Following the Preferred Reporting Items for Systematic Review and Meta-Analyses (PRISMA) standards, we conducted the analysis and literature search using PubMed, Google Scholar and Cochrane databases. After applying the inclusion and exclusion criteria, the search technique produced a total of 10 articles including one cross-sectional study, two randomized controlled trials (RCTs), one cohort study, five case-control studies and one meta-analysis. Analysis of these studies revealed that there could be an association between Helicobacter pylori infection and migraine, especially in the Asian population. However, the mechanism by which the infection could possibly cause this extra-gastric disorder needs further research and analysis.

αCGRP deficiency aggravates pulmonary fibrosis by activating the PPARγ signaling pathway

In order to explore whether αCGRP (Calca) deficiency aggravates pulmonary fibrosis (PF). Clinical data from patients with PF (n = 52) were retrospectively analyzed. Lung tissue from a bleomycin (BLM)-induced rat model was compared with that of Calca-knockout (KO) and wild type (WT) using immunohistochemistry, RNA-seq, and UPLC-MS/MS metabolomic analyses. The results showed that decreased αCGRP expression and activation of the type 2 immune response were detected in patients with PF. In BLM-induced and Calca-KO rats, αCGRP deficiency potentiated apoptosis of AECs and induced M2 macrophages. RNA-seq identified enrichment of pathways involved in nuclear translocation and immune system disorders in Calca-KO rats compared to WT. Mass spectrometry of lung tissue from Calca-KO rats showed abnormal lipid metabolism, including increased levels of LTB4, PDX, 1-HETE. PPAR pathway signaling was significantly induced in both transcriptomic and metabolomic datasets in Calca-KO rats, and immunofluorescence analysis confirmed that the nuclear translocation of PPARγ in BLM-treated and Calca-KO rats was synchronized with STAT6 localization in the cytoplasmic and nuclear fractions. In conclusion, αCGRP is protective against PF, and αCGRP deficiency promotes M2 polarization of macrophages, probably by activating the PPARγ pathway, which leads to activation of the type 2 immune response and accelerates PF development.

Real-world effectiveness of fremanezumab in patients with migraine switching from another mAb targeting the CGRP pathway: a subgroup analysis of the Finesse Study

BACKGROUND

Monoclonal antibodies targeting the CGRP pathway are effective and safe for prophylactic treatment of episodic (EM) and chronic migraine (CM). In case of treatment failure of a CGRP pathway targeting mAb, physician has to decide whether using another anti-CGRP pathway mAb is useful. This interim analysis of Finesse Study evaluates effectiveness of the anti-CGRP mAb fremanezumab in patients with a history of other prior anti-CGRP pathway mAb treatments (switch patients).

METHODS

FINESSE, a non-interventional, prospective, multicentre, two-country (Germany-Austria) study observing migraine patients receiving fremanezumab in clinical routine. This subgroup analysis presents data on documented effectiveness over 3 months after the first dose of fremanezumab in switch patients. Effectiveness was evaluated based on reduction in average number of migraine days per month (MMDs), MIDAS and HIT-6 scores changes as well as in number of monthly days with acute migraine medication use.

RESULTS

One hundred fifty-three out of 867 patients with a history of anti-CGRP pathway mAb treatment prior to initiation of fremanezumab were analysed. Switch to fremanezumab led to ≥ 50% MMD reduction in 42.8% of migraine patients, with higher response rate in EM (48.0%) than in CM patients (36.5%). A ≥ 30% MMD reduction was achieved by 58.7% in CM patients. After three months, monthly number of migraine days decreased by 6.4 ± 5.87 (baseline: 13.6 ± 6.5; p < 0.0001) in all patients, 5.2 ± 4.04 in EM and 7.7 ± 7.45 in CM patients. MIDAS scores decreased from 73.3 ± 56.8 (baseline) to 50.3 ± 52.9 (after 3 months; p = 0.0014), HIT-6 scores decreased from 65.9 ± 5.0 to 60.9 ± 7.2 (p < 0.0001). Concomitant use of acute migraine medication had decreased from 9.7 ± 4.98 (baseline) to 4.9 ± 3.66 (3 months) (p < 0.0001).

CONCLUSIONS

Our results show that about 42.8% of anti-CGRP pathway mAb-non-responder benefit from switching to fremanezumab. These results suggest that switching to fremanezumab may be a promising option for patients experiencing poor tolerability or inadequate efficacy with prior other anti-CGRP pathway mAb use.

TRIAL REGISTRATION

FINESSE Study is registered on the European Network of Centres for Pharmacoepidemiology and Pharmacovigilance (EUPAS44606).

Acidosis-related pain and its receptors as targets for chronic pain

Sensing acidosis is an important somatosensory function in responses to ischemia, inflammation, and metabolic alteration. Accumulating evidence has shown that acidosis is an effective factor for pain induction and that many intractable chronic pain diseases are associated with acidosis signaling. Various receptors have been known to detect extracellular acidosis and all express in the somatosensory neurons, such as acid sensing ion channels (ASIC), transient receptor potential (TRP) channels and proton-sensing G-protein coupled receptors. In addition to sense noxious acidic stimulation, these proton-sensing receptors also play a vital role in pain processing. For example, ASICs and TRPs are involved in not only nociceptive activation but also anti-nociceptive effects as well as some other non-nociceptive pathways. Herein, we review recent progress in probing the roles of proton-sensing receptors in preclinical pain research and their clinical relevance. We also propose a new concept of sngception to address the specific somatosensory function of acid sensation. This review aims to connect these acid-sensing receptors with basic pain research and clinical pain diseases, thus helping with better understanding the acid-related pain pathogenesis and their potential therapeutic roles via the mechanism of acid-mediated antinociception.

Monoclonal antibodies against CGRP (R): non-responders and switchers: real world data from an austrian case series

OBJECTIVE

Assessement of the responder and non-responder rate to consecutive monoclonal CGRP-antibody (CGRP-mAb) treatment, the presence of side effects, analysis of predictors of response and loss-of-effectiveness evaluation over time.

METHODS

We conducted a retrospective analysis including 171 patients with episodic (EM) or chronic migraine (CM), who received one, two or three different CGRP-mAbs. Non-response was defined as ≤ 50% reduction of monthly migraine days (MMDs) in EM and ≤ 30% reduction of MMDs in CM after 3 months of treatment.

RESULTS

123 (71.9%) responded to the first mAb. Side effects led to treatment discontinuation in 9 (5.3%) patients. Of the 26 patients who did not respond to the first mAb or experienced a loss of efficacy over time, 11 (42.3%) responded to the second and two (28.6%) of 7 to the third monoclonal antibody. Poor response to therapy was associated with a higher monthly migraine frequency (p = 0.028), a higher number of prior preventive migraine therapies (p = 0.011) and medication overuse (p = 0.022).

CONCLUSION

Our findings support mAb-class switch in non-responders or in patients experiencing a loss of effectiveness. The use of a third CGRP-mAb could be beneficial for some patients.

Pharmacological interventions for prophylaxis of vestibular migraine

BACKGROUND

Vestibular migraine is a form of migraine where one of the main features is recurrent attacks of vertigo. These episodes are often associated with other features of migraine, including headache and sensitivity to light or sound. These unpredictable and severe attacks of vertigo can lead to a considerable reduction in quality of life. The condition is estimated to affect just under 1% of the population, although many people remain undiagnosed. A number of pharmacological interventions have been used or proposed to be used as prophylaxis for this condition, to help reduce the frequency of the attacks. These are predominantly based on treatments that are in use for headache migraine, with the belief that the underlying pathophysiology of these conditions is similar.

OBJECTIVES

To assess the benefits and harms of pharmacological treatments used for prophylaxis of vestibular migraine.

SEARCH METHODS

The Cochrane ENT Information Specialist searched the Cochrane ENT Register; Central Register of Controlled Trials (CENTRAL); Ovid MEDLINE; Ovid Embase; Web of Science; ClinicalTrials.gov; ICTRP and additional sources for published and unpublished trials. The date of the search was 23 September 2022.

SELECTION CRITERIA

We included randomised controlled trials (RCTs) and quasi-RCTs in adults with definite or probable vestibular migraine comparing beta-blockers, calcium channel blockers, antiepileptics, antidepressants, diuretics, monoclonal antibodies against calcitonin gene-related peptide (or its receptor), botulinum toxin or hormonal modification with either placebo or no treatment. We excluded studies with a cross-over design, unless data from the first phase of the study could be identified.

DATA COLLECTION AND ANALYSIS

We used standard Cochrane methods. Our primary outcomes were: 1) improvement in vertigo (assessed as a dichotomous outcome - improved or not improved), 2) change in vertigo (assessed as a continuous outcome, with a score on a numerical scale) and 3) serious adverse events. Our secondary outcomes were: 4) disease-specific health-related quality of life, 5) improvement in headache, 6) improvement in other migrainous symptoms and 7) other adverse effects. We considered outcomes reported at three time points: < 3 months, 3 to < 6 months, > 6 to 12 months. We used GRADE to assess the certainty of evidence for each outcome.

MAIN RESULTS

We included three studies with a total of 209 participants. One evaluated beta-blockers and the other two evaluated calcium channel blockers. We did not identify any evidence for the remaining interventions of interest. Beta-blockers versus placebo One study (including 130 participants, 61% female) evaluated the use of 95 mg metoprolol once daily for six months, compared to placebo. The proportion of people who reported improvement in vertigo was not assessed in this study. Some data were reported on the frequency of vertigo attacks at six months and the occurrence of serious adverse effects. However, this is a single, small study and for all outcomes the certainty of evidence was low or very low. We are unable to draw meaningful conclusions from the numerical results. Calcium channel blockers versus no treatment Two studies, which included a total of 79 participants (72% female), assessed the use of 10 mg flunarizine once daily for three months, compared to no intervention. All of the evidence for this comparison was of very low certainty. Most of our outcomes were only reported by a single study, therefore we were unable to conduct any meta-analysis. Some data were reported on improvement in vertigo and change in vertigo, but no information was available regarding serious adverse events. We are unable to draw meaningful conclusions from the numerical results, as these data come from single, small studies and the certainty of the evidence was very low.

AUTHORS CONCLUSIONS

There is very limited evidence from placebo-controlled randomised trials regarding the efficacy and potential harms of pharmacological interventions for prophylaxis of vestibular migraine. We only identified evidence for two of our interventions of interest (beta-blockers and calcium channel blockers) and all evidence was of low or very low certainty. Further research is necessary to identify whether these treatments are effective at improving symptoms and whether there are any harms associated with their use.

Pharmacological interventions for acute attacks of vestibular migraine

BACKGROUND

Vestibular migraine is a form of migraine where one of the main features is recurrent attacks of vertigo. These episodes are often associated with other features of migraine, including headache and sensitivity to light or sound. The unpredictable and severe attacks of vertigo can lead to a considerable reduction in quality of life. The condition is estimated to affect just under 1% of the population, although many people remain undiagnosed. A number of pharmacological interventions have been used, or proposed to be used, at the time of a vestibular migraine attack to help reduce the severity or resolve the symptoms. These are predominantly based on treatments that are in use for headache migraine, with the belief that the underlying pathophysiology of these conditions is similar.  OBJECTIVES: To assess the benefits and harms of pharmacological interventions used to relieve acute attacks of vestibular migraine.

SEARCH METHODS

The Cochrane ENT Information Specialist searched the Cochrane ENT Register; Central Register of Controlled Trials (CENTRAL); Ovid MEDLINE; Ovid Embase; Web of Science; ClinicalTrials.gov; ICTRP and additional sources for published and unpublished trials. The date of the search was 23 September 2022.

SELECTION CRITERIA

We included randomised controlled trials (RCTs) and quasi-RCTs in adults with definite or probable vestibular migraine comparing triptans, ergot alkaloids, dopamine antagonists, antihistamines, 5-HT3 receptor antagonists, gepants (CGRP receptor antagonists), magnesium, paracetamol or non-steroidal anti-inflammatory drugs (NSAIDs) with either placebo or no treatment.  DATA COLLECTION AND ANALYSIS: We used standard Cochrane methods. Our primary outcomes were: 1) improvement in vertigo (assessed as a dichotomous outcome - improved or not improved), 2) change in vertigo (assessed as a continuous outcome, with a score on a numerical scale) and 3) serious adverse events. Our secondary outcomes were: 4) disease-specific health-related quality of life, 5) improvement in headache, 6) improvement in other migrainous symptoms and 7) other adverse effects. We considered outcomes reported at three time points: < 2 hours, 2 to 12 hours, > 12 to 72 hours. We used GRADE to assess the certainty of evidence for each outcome.  MAIN RESULTS: We included two RCTs with a total of 133 participants, both of which compared the use of triptans to placebo for an acute attack of vestibular migraine. One study was a parallel-group RCT (of 114 participants, 75% female). This compared the use of 10 mg rizatriptan to placebo. The second study was a smaller, cross-over RCT (of 19 participants, 70% female). This compared the use of 2.5 mg zolmitriptan to placebo.  Triptans may result in little or no difference in the proportion of people whose vertigo improves at up to two hours after taking the medication. However, the evidence was very uncertain (risk ratio 0.84, 95% confidence interval 0.66 to 1.07; 2 studies; based on 262 attacks of vestibular migraine treated in 124 participants; very low-certainty evidence). We did not identify any evidence on the change in vertigo using a continuous scale. Only one of the studies assessed serious adverse events. No events were noted in either group, but as the sample size was small we cannot be sure if there are risks associated with taking triptans for this condition (0/75 receiving triptans, 0/39 receiving placebo; 1 study; 114 participants; very low-certainty evidence).  AUTHORS' CONCLUSIONS: The evidence for interventions used to treat acute attacks of vestibular migraine is very sparse. We identified only two studies, both of which assessed the use of triptans. We rated all the evidence as very low-certainty, meaning that we have little confidence in the effect estimates and cannot be sure if triptans have any effect on the symptoms of vestibular migraine. Although we identified sparse information on potential harms of treatment in this review, the use of triptans for other conditions (such as headache migraine) is known to be associated with some adverse effects.  We did not identify any placebo-controlled randomised trials for other interventions that may be used for this condition. Further research is needed to identify whether any interventions help to improve the symptoms of vestibular migraine attacks and to determine if there are side effects associated with their use.

2-Deoxyglucose alleviates migraine-related behaviors by modulating microglial inflammatory factors in experimental model of migraine

Background

Targeting metabolic pathways has emerged as a new migraine treatment strategy as researchers realize the critical role metabolism plays in migraine. Activated inflammatory cells undergo metabolic reprogramming and rely on glycolysis to function. The objective of this study was to investigate the glycolysis changes in the experimental model of migraine and the effect of glycolysis inhibitor 2-Deoxy-D-glucose (2-DG) in the pathophysiology of migraine.

Methods

We used a rat model of migraine that triggered migraine attacks by applying inflammatory soup (IS) to the dura and examined changes in glycolysis. 2-DG was used to inhibit glycolysis, and the effects of 2-DG on mechanical ectopic pain, microglial cell activation, calcitonin gene-related peptides (CGRP), c-Fos, and inflammatory factors induced by inflammatory soup were observed. LPS stimulated BV2 cells to establish a model in vitro to observe the effects of 2-DG on brain-derived neurotrophic factor (BDNF) after microglia activation.

Results

In the experimental model of migraine, key enzymes involved in glycolysis such as phosphofructokinase platelet (PFKP), hexokinase (HK2), hypoxia inducible factor-1α (HIF-1α), lactate dehydrogenase (LDH) and pyruvate kinase (PKM2) were expressed in the medullary dorsal horn. While the expression of electronic respiratory transport chain complex IV (COXIV) decreased. There were no significant changes in glucose 6-phosphate dehydrogenase (G6PD), a key enzyme in the pentose phosphate pathway. The glycolysis inhibitor 2-DG alleviated migraine-like symptoms in an experimental model of migraine, reduced the release of proinflammatory cytokines caused by microglia activation, and decreased the expression of CGRP and c-Fos. Further experiments in vitro demonstrated that glycolysis inhibition can reduce the release of Iba-1/proBDNF/BDNF and inhibit the activation of microglia.

Conclusion

The migraine rat model showed enhanced glycolysis. This study suggests that glycolytic inhibitor 2-DG is an effective strategy for alleviating migraine-like symptoms. Glycolysis inhibition may be a new target for migraine treatment.

Shared and independent roles of CGRP and PACAP in migraine pathophysiology

The neuropeptides calcitonin gene-related peptide (CGRP) and pituitary adenylate cyclase-activating polypeptide (PACAP) have emerged as mediators of migraine pathogenesis. Both are vasodilatory peptides that can cause migraine-like attacks when infused into people and migraine-like symptoms when injected into rodents. In this narrative review, we compare the similarities and differences between the peptides in both their clinical and preclinical migraine actions. A notable clinical difference is that PACAP, but not CGRP, causes premonitory-like symptoms in patients. Both peptides are found in distinct, but overlapping areas relevant to migraine, most notably with the prevalence of CGRP in trigeminal ganglia and PACAP in sphenopalatine ganglia. In rodents, the two peptides share activities, including vasodilation, neurogenic inflammation, and nociception. Most strikingly, CGRP and PACAP cause similar migraine-like symptoms in rodents that are manifested as light aversion and tactile allodynia. Yet, the peptides appear to act by independent mechanisms possibly by distinct intracellular signaling pathways. The complexity of these signaling pathways is magnified by the existence of multiple CGRP and PACAP receptors that may contribute to migraine pathogenesis. Based on these differences, we suggest PACAP and its receptors provide a rich set of targets to complement and augment the current CGRP-based migraine therapeutics.

Migraine drugs

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

Graphical abstract

CGRP physiology, pharmacology, and therapeutic targets: migraine and beyond

Calcitonin gene-related peptide (CGRP) is a neuropeptide with diverse physiological functions. Its two isoforms (α and β) are widely expressed throughout the body in sensory neurons as well as in other cell types, such as motor neurons and neuroendocrine cells. CGRP acts via at least two G protein-coupled receptors that form unusual complexes with receptor activity-modifying proteins. These are the CGRP receptor and the AMY1 receptor; in rodents, additional receptors come into play. Although CGRP is known to produce many effects, the precise molecular identity of the receptor(s) that mediates CGRP effects is seldom clear. Despite the many enigmas still in CGRP biology, therapeutics that target the CGRP axis to treat or prevent migraine are a bench-to-bedside success story. This review provides a contextual background on the regulation and sites of CGRP expression and CGRP receptor pharmacology. The physiological actions of CGRP in the nervous system are discussed, along with updates on CGRP actions in the cardiovascular, pulmonary, gastrointestinal, immune, hematopoietic, and reproductive systems and metabolic effects of CGRP in muscle and adipose tissues. We cover how CGRP in these systems is associated with disease states, most notably migraine. In this context, we discuss how CGRP actions in both the peripheral and central nervous systems provide a basis for therapeutic targeting of CGRP in migraine. Finally, we highlight potentially fertile ground for the development of additional therapeutics and combinatorial strategies that could be designed to modulate CGRP signaling for migraine and other diseases.

Control of myeloid cell functions by nociceptors

The immune system has evolved to protect the host from infectious agents, parasites, and tumor growth, and to ensure the maintenance of homeostasis. Similarly, the primary function of the somatosensory branch of the peripheral nervous system is to collect and interpret sensory information about the environment, allowing the organism to react to or avoid situations that could otherwise have deleterious effects. Consequently, a teleological argument can be made that it is of advantage for the two systems to cooperate and form an “integrated defense system” that benefits from the unique strengths of both subsystems. Indeed, nociceptors, sensory neurons that detect noxious stimuli and elicit the sensation of pain or itch, exhibit potent immunomodulatory capabilities. Depending on the context and the cellular identity of their communication partners, nociceptors can play both pro- or anti-inflammatory roles, promote tissue repair or aggravate inflammatory damage, improve resistance to pathogens or impair their clearance. In light of such variability, it is not surprising that the full extent of interactions between nociceptors and the immune system remains to be established. Nonetheless, the field of peripheral neuroimmunology is advancing at a rapid pace, and general rules that appear to govern the outcomes of such neuroimmune interactions are beginning to emerge. Thus, in this review, we summarize our current understanding of the interaction between nociceptors and, specifically, the myeloid cells of the innate immune system, while pointing out some of the outstanding questions and unresolved controversies in the field. We focus on such interactions within the densely innervated barrier tissues, which can serve as points of entry for infectious agents and, where known, highlight the molecular mechanisms underlying these interactions.

Modification of the TRP Channel TRPA1 as a Relevant Factor in Migraine-Related Intracranial Hypersensitivity

Recently, the transient receptor potential ankyrin 1 (TRPA1) has gained more attention in migraine-related research. The involvement of the TRPA1 receptor in migraine headaches is proposed by the fact that TRPA1 may be a target of some migraine-triggering factors. Although it is doubtful that activation of TRPA1 alone is sufficient to induce pain, behavioral studies have demonstrated that TRPA1 is involved in injury- and inflammation-induced hypersensitivity. Here, we review the functional relevance of TRPA1 in headaches and its therapeutic potential, mainly focusing on its role in the development of hypersensitivity, referring to its altered expression in pathological conditions, and its functional interaction with other TRP channels.

The putative role of neuroinflammation in the complex pathophysiology of migraine: From bench to bedside

The implications of neurogenic inflammation and neuroinflammation in the pathophysiology of migraine have been clearly demonstrated in preclinical migraine models involving several sites relevant in the trigemino-vascular system, including dural vessels and trigeminal endings, the trigeminal ganglion, the trigeminal nucleus caudalis as well as central trigeminal pain processing structures. In this context, a relevant role has been attributed over the years to some sensory and parasympathetic neuropeptides, in particular calcitonin gene neuropeptide, vasoactive intestinal peptide and pituitary adenylate cyclase-activating polypeptide. Several preclinical and clinical lines of evidence also support the implication of the potent vasodilator and messenger molecule nitric oxide in migraine pathophysiology. All these molecules are involved in vasodilation of the intracranial vasculature, as well as in the peripheral and central sensitization of the trigeminal system. At meningeal level, the engagement of some immune cells of innate immunity, including mast-cells and dendritic cells, and their mediators, has been observed in preclinical migraine models of neurogenic inflammation in response to sensory neuropeptides release due to trigemino-vascular system activation. In the context of neuroinflammatory events implicated in migraine pathogenesis, also activated glial cells in the peripheral and central structures processing trigeminal nociceptive signals seem to play a relevant role. Finally, cortical spreading depression, the pathophysiological substrate of migraine aura, has been reported to be associated with inflammatory mechanisms such as pro-inflammatory cytokine upregulation and intracellular signalling. Reactive astrocytosis consequent to cortical spreading depression is linked to an upregulation of these inflammatory markers. The present review summarizes current findings on the roles of immune cells and inflammatory responses in the pathophysiology of migraine and their possible exploitation in the view of innovative disease-modifying strategies.

Safety, tolerability, and efficacy of zavegepant 10 mg nasal spray for the acute treatment of migraine in the USA: a phase 3, double-blind, randomised, placebo-controlled multicentre trial

BACKGROUND

Intranasal formulations can provide treatment options for people with migraine in whom oral drugs are ineffective, slow-acting, or intolerable because of nausea and vomiting. Zavegepant, an intranasally administered small molecule calcitonin gene-related peptide (CGRP) receptor antagonist, was previously assessed in a phase 2/3 trial. This phase 3 trial aimed to compare the efficacy, tolerability, safety, and timecourse of response for zavegepant nasal spray with placebo in the acute treatment of migraine.

METHODS

This double-blind, randomised, placebo-controlled, multicentre phase 3 trial, conducted at 90 academic medical centres, headache clinics, and independent research facilities in the USA, recruited adults (aged ≥18 years) with a history of two to eight moderate or severe migraine attacks per month. Participants were randomly assigned (1:1) to zavegepant 10 mg nasal spray or matching placebo and self-treated a single migraine attack of moderate or severe pain intensity. Randomisation was stratified by the use or non-use of preventive medication. Study centre personnel entered eligible participants into the study using an interactive web response system that was operated and managed by an independent contract research organisation. All participants, investigators, and the funder were masked to group assignment. The coprimary endpoints, freedom from pain and freedom from the most bothersome symptom at 2 h after the treatment dose, were assessed in all randomly assigned participants who took the study medication, had a migraine attack of moderate or severe pain intensity at baseline, and provided at least one evaluable post-baseline efficacy datapoint. Safety was analysed in all randomly assigned participants who received at least one dose. The study is registered with ClinicalTrials.gov, number NCT04571060, and is closed to accrual.

FINDINGS

Between Oct 27, 2020, and Aug 20, 2021, 1978 participants were recruited and assessed for eligibility. 1405 participants were eligible (703 were assigned to zavegepant and 702 to placebo), and 1269 were included in the efficacy analysis set (623 in the zavegepant group and 646 in the placebo group). 2 h after the treatment dose, more participants in the zavegepant group than in the placebo group had pain freedom (147 [24%] of 623 participants vs 96 [15%] of 646 participants, risk difference 8·8 percentage points, 95% CI 4·5-13·1; p<0·0001) and freedom from their most bothersome symptom (247 [40%] vs 201 [31%], risk difference 8·7 percentage points, 3·4-13·9; p=0·0012). The most common adverse events in either treatment group (≥2%) were dysgeusia (129 [21%] of 629 in the zavegepant group vs 31 [5%] of 653 in the placebo group), nasal discomfort (23 [4%] vs five [1%]), and nausea (20 [3%] vs seven [1%]). No signal of hepatotoxicity due to zavegepant was identified.

INTERPRETATION

Zavegepant 10 mg nasal spray was efficacious in the acute treatment of migraine, with favourable tolerability and safety profiles. Additional trials are needed to establish the long-term safety and consistency of effect across attacks.

FUNDING

Biohaven Pharmaceuticals.

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

BACKGROUND

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

METHODS

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

RESULTS

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

CONCLUSIONS

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

Migraine Disability Improvement during Treatment with Galcanezumab in Patients with Chronic and High Frequency Episodic Migraine

BACKGROUND

The aim of the present study was to assess the migraine outcome, in particular migraine disability, in chronic (CM) and high frequency episodic migraine (HFEM) patients in treatment with galcanezumab.

METHODS

The present study was conducted at the Headache Centre of Spedali Civili of Brescia. Patients were treated with galcanezumab 120 mg monthly. Clinical and demographical information were collected at the baseline (T0). Data about outcome, analgesics consumption and disability (MIDAS and HIT-6 scores) were collected quarterly.

RESULTS

Fifty-four consecutive patients were enrolled. Thirty-seven patients had a diagnosis of CM, 17 of HFEM. During treatment, patients reported a significant reduction in terms of mean headache/migraine days (p < 0.001), the attacks' pain intensity (p = 0.001) and monthly consumed analgesics (p < 0.001). The MIDAS and HIT-6 scores also documented a significant improvement (p < 0.001). At the baseline, all patients documented a severe degree of disability (MIDAS score ≥ 21). Following six months of treatment, only 29.2% of patients still documented a MIDAS score ≥ 21, with one third of patients documenting little or no disability. A > 50% MIDAS reduction, compared to baseline, was observed in up to 94.6% of patients, following the first three months of treatment. A similar outcome was found for HIT-6 scores. A significant positive correlation was found between headache days and MIDAS at T3 and T6 (T6 > T3), but not baseline.

DISCUSSION

Monthly prophylactic treatment with galcanezumab was found to be effective in both CM and HFEM, especially in reducing migraine burden and disability.

Calcitonin gene-related peptide (CGRP) monoclonal antibodies for migraine

The introduction of calcitonin gene-related peptide monoclonal antibodies represents a step forward in preventive migraine treatment as the first agents to target the underlying pathogenesis of migraine. In trials they act more quickly, have better long-term adherence and appear to be better tolerated than other treatments. Major disadvantages are their high cost and unknown safety in pregnancy and in cardiovascular disease. To mitigate these concerns, they should be used according to guidance produced by professional bodies, with defined starting and stopping criteria. We do not yet know whether they are more effective than standard care; many patients may still be better treated by other means, in particular addressing lifestyle factors and medication-overuse headache.

Open-label trials for CGRP-targeted drugs in migraine prevention: A narrative review

BACKGROUND

Calcitonin gene-related peptide-targeted drugs have proven safe and effective for migraine prevention in large randomized-controlled, double-blind trials with an average duration of six months. Open-label studies may provide additional information on the long-term safety and efficacy of these substances.

METHODS

We searched PubMed for open-label trials with calcitonin gene-related peptide(-receptor) monoclonal antibodies and calcitonin gene-related peptide-receptor antagonists. We summarized and critically analyzed the literature in a narrative way.

RESULTS

Overall, 13 open-label trials were included in this review (n = 4 for erenumab, n = 4 for galcanezumab, n = 3 for fremanezumab, n = 1 for eptinezumab, n = 1 for atogepant). Open-label trial duration ranged between 12 and 264 weeks. No safety concerns emerged, and the adverse events profile was similar to the double-blind study phase. Discontinuation rates were generally low with >75% of patients remaining in the trials after one year. Efficacy data showed a sustained reduction of migraine frequency throughout the trials, along with a lasting improvement in quality of life.

CONCLUSIONS

The open-label study program for calcitonin gene-related peptide-targeted migraine preventives confirms the favorable safety and efficacy profile of these drugs over time. Treatment adherence appears higher than with previous unspecific migraine preventives. Real-world data and post-marketing surveillance studies may corroborate and complement open-label results.

OnabotulinumtoxinA effects on trigeminal nociceptors

BACKGROUND

OnabotulinumtoxinA (onabotA) is approved globally for prevention of chronic migraine; however, the classical mechanism of action of onabotA in motor and autonomic neurons cannot fully explain the effectiveness of onabotulinumtoxinA in this sensory neurological disease. We sought to explore the direct effects of onabotulinumtoxinA on mouse trigeminal ganglion sensory neurons using an inflammatory soup-based model of sensitization.

METHODS

Primary cultured trigeminal ganglion neurons were pre-treated with inflammatory soup, then treated with onabotulinumtoxinA (2.75 pM). Treated neurons were used to examine transient receptor potential vanilloid subtype 1 and transient receptor potential ankyrin 1 cell-surface expression, calcium influx, and neuropeptide release.

RESULTS

We found that onabotulinumtoxinA cleaved synaptosomal-associated protein-25 kDa in cultured trigeminal ganglion neurons; synaptosomal-associated protein-25 kDa cleavage was enhanced by inflammatory soup pre-treatment, suggesting greater uptake of toxin under sensitized conditions. OnabotulinumtoxinA also prevented inflammatory soup-mediated increases in TRPV1 and TRPA1 cell-surface expression, without significantly altering TRPV1 or TRPA1 protein expression in unsensitized conditions. We observed similar inhibitory effects of onabotulinumtoxinA on TRP-mediated calcium influx and TRPV1- and TRPA1-mediated release of calcitonin gene-related peptide and prostaglandin 2 under sensitized, but not unsensitized control, conditions.

CONCLUSIONS

Our data deepen the understanding of the sensory mechanism of action of onabotulinumtoxinA and support the notion that, once endocytosed, the cytosolic light chain of onabotulinumtoxinA cleaves synaptosomal-associated protein-25 kDa to prevent soluble N-ethylmaleimide-sensitive factor attachment protein receptor-mediated processes more generally in motor, autonomic, and sensory neurons.

Neuropathic pain: Mechanisms and therapeutic strategies

The physiopathology and neurotransmission of pain are of an owe inspiring complexity. Our ability to satisfactorily suppress neuropathic or other forms of chronic pain is limited. The number of pharmacodynamically distinct and clinically available medications is low and the successes achieved modest. Pain Medicine practitioners are confronted with the ethical dichotomy imposed by Hippocrates: On one hand the mandate of primum non nocere, on the other hand, the promise of heavenly joys if successful divinum est opus sedare dolorem. We briefly summarize the concepts associated with nociceptive pain from nociceptive input (afferents from periphery), modulatory output [descending noradrenergic (NE) and serotoninergic (5-HT) fibers] to local control. The local control is comprised of the "inflammatory soup" at the site of pain origin and synaptic relay stations, with an ATP-rich environment promoting inflammation and nociception while an adenosine-rich environment having the opposite effect. Subsequently, we address the transition from nociceptor pain to neuropathic pain (independent of nociceptor activation) and the process of sensitization and pain chronification (transient pain progressing into persistent pain). Having sketched a model of pain perception and processing we attempt to identify the sites and modes of action of clinically available drugs used in chronic pain treatment, focusing on adjuvant (co-analgesic) medication.

Migraine and obesity: what is the real direction of their association?

INTRODUCTION

In recent decades, studies have addressed the issue of how migraine and obesity are related and have suggested obesity as a risk factor for migraine headache. However, the exact direction of this relationship remains under debate. In this review, the authors summarize the evidence that have suggested migraine as a risk factor for obesity and overweightness.

AREAS COVERED

This article reviews the results of the previous research published on PubMed and Scopus databases (from 2000 to 2020) concerning the association between migraine and obesity to determine the actual direction of their association. Special attention has been given to the common mechanistic pathways involved in the pathophysiology of migraine and obesity.

EXPERT OPINION

The majority of research conducted thus far has considered obesity as a risk factor for migraine. However, because of the cross-sectional design of available research, we cannot be certain of the proposed direction of this association. There is evidence supporting the hypothesis that obesity can serve as a consequence of migraine through the effects of neuropeptides, inflammatory mediators, adipokines, gut microbiota and modifications in eating behavior and lifestyle. However, the real direction of the relationship between migraine and obesity should be further investigated in large prospective studies.

Bilateral Superficial Trigeminal Nerve Blocks are not More Effective than a Placebo in Abolishing Post-operative Headache Pain in Pituitary Transsphenoidal Neurosurgery: A Prospective, Randomized, Doubleblinded Clinical Trial

BACKGROUND

Pituitary neurosurgery executed via the transsphenoidal endonasal approach is commonly performed for pituitary adenomas. Reasons for prolonged hospital stay include postoperative headache and protracted nausea with or without vomiting. Bilateral superficial trigeminal nerve blocks of the supra-orbital V1 and infra-orbital V2 (SION) nerves performed intra-operatively as a regional anesthetic adjunct to general anesthesia were hypothesized to decrease 6 hours postoperative morphine PCA (patient-controlled analgesia) use by patients.

METHODS

Forty-nine patients, following induction of general anesthesia for their transsphenoidal surgery, were prospectively randomized in a double-blinded fashion to receive additional regional anesthesia as either a block (0.5% ropivacaine with epi 1:200,000) or placebo/sham (0.9% normal saline). The primary endpoint of the study was systemic morphine PCA opioid consumption by the two groups in the first 6-hours postoperatively. The secondary endpoints included (1) pain exposure experienced postoperatively, (2) incidence of postoperative nausea and vomiting, and (3) time to eligibility for PACU discharge.

RESULTS

Of the 49 patients that were enrolled, 3 patients were excluded due to protocol violations. Ultimately, there was no statistically significant difference between morphine PCA use in the 6 hours postoperatively between the block and placebo/sham groups. There was, however, a slight visual tendency in the block group for higher pain scores, morphine use p=0.046, and delayed PACU discharge. False discovery rate corrected comparisons at each time point and then revealed no statistically significant difference between the two groups. There were no differences between the two groups for secondary endpoints.

CONCLUSION

It was found that a 6-hour postoperative headache after endoscopic trans-sphenoidal pituitary surgery likely has a more complicated mechanism involving more than the superficial trigeminovascular system and perhaps is neuro-modulated by other brain nuclei.

Migraine headache pathophysiology

In both episodic and chronic migraine, headache is the most disabling symptom that requires medical care. The migraine headache is the most well-studied symptom of migraine pathophysiology. The trigeminal system and the central processing of sensory information transmitted by the trigeminal system are of considerable importance in the pathophysiology of migraine headache. Glutamate is the main neurotransmitter that drives activation of the ascending trigeminal and trigeminothalamic pathways. The neuropeptide, calcitonin gene-related peptide (CGRP) that is released by the trigeminal system, plays a crucial role in the neurobiology of headache. Peripheral and central sensitizations associated with trigeminal sensory processing are neurobiologic states that contribute to both the development of headache during a migraine attack and the maintenance of chronic migraine.

Preclinical Studies of Posttraumatic Headache and the Potential Therapeutics

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

Dual therapy with Erenumab and onabotulinumtoxinA: No synergistic effect in chronic migraine: A retrospective cohort study

OBJECTIVE

To assess whether dual therapy with erenumab and onabotulinumtoxinA (BoNTA) was more effective than erenumab alone in chronic migraine.

BACKGROUND

Calcitonin gene-related peptide (CGRP) is crucial in migraine. Erenumab binds to the canonical CGRP receptor in Aδ-fibers, and BoNTA prevents the release of CGRP from meningeal and extracranial C-fibers. It is still unknown whether dual therapy is more effective.

METHODS

This was a retrospective study in a Headache Unit. There was a thorough revision of charts of patients receiving erenumab from December 2019 to March 2021. The cohort was divided into three groups according to BoNTA at the start of erenumab: (1) WBT: were on BoNTA and maintained it as dual therapy; (2) WoBT: were on BoNTA and discontinued; (3) NoBT: were not on BoNTA. Primary endpoint was reduction in monthly headache days (MHD) at 12 weeks. Secondary endpoints were percent improvement and ≥50% reduction in MHD.

RESULTS

Of 237 charts reviewed, 187 met the inclusion criteria. Seventy-three (39%) were included in WBT, 44 (23.5%) in WoBT, and 70 (37.4%) in NoBT. The reduction in MHD was less with dual therapy [WBT 4.7 ± 7.68, WoBT 5.12 ± 7.98 (p = 0.80), NoBT 8.21 ± 7.84 p = 0.009]. The percentage of improvement was higher in the erenumab-alone group [NoBT 35%, WoBT 22.3% (p = 0.92), WBT 21.7% (p = 0.001)]. The probability of achieving a ≥ 50% reduction in MHD was lower in WBT than in WoBT (OR 0.66, p = 0.35) and in the NoBT group (OR 0.57, p = 0.14).

CONCLUSIONS

Our findings suggest that dual therapy is less effective than erenumab alone. However, since the design has multiple limitations, further prospective studies are required to validate these data.

Serum CGRP in migraine patients using erenumab as preventive treatment

Aim

Serum levels of Calcitonin Gene-Related Peptide (CGRP)-like immunoreactivity (CGRP-LI) in migraine patients before and after starting treatment with erenumab were measured to evaluate the association with clinical treatment response.

Methods

Blood samples were collected from the cubital fossa before (T0) and 2–4 weeks after (T1) starting treatment with erenumab. Clinical response was monitored using a daily headache e-diary. Serum levels of CGRP-LI, assessed using radioimmunoassay, were compared between T0 and T1, correcting for migraine reduction. In addition, for both T0 and T1, linear regression models were constructed using migraine reduction as outcome and serum CGRP-LI as independent variable, corrected for age, gender and monthly migraine days (MMD) at baseline.

Results

Serum CGRP-LI did not differ between T0 and T1 (p = 0.30). However, there was an interaction between time and reduction in MMD (p = 0.01). Absolute reduction in MMD in the third month after treatment with erenumab was associated with serum CGRP-LI at T1, 2–4 weeks after starting treatment with erenumab (p = 0.003), but not with serum CGRP-LI at T0 (p = 0.24).

Conclusion

Lower serum CGRP-LI 2–4 weeks after starting treatment with erenumab was associated with a higher reduction in migraine days after three months of treatment. Although the underlying mechanisms remain to be determined, this suggests that changes in CGRP levels, shortly after starting erenumab, are important for its clinical effect.

• Lower serum levels of calcitonin gene-related peptide (CGRP)-like immunoreactivity (CGRP-LI) in migraine patients at 2–4 weeks after starting treatment with erenumab were associated with better treatment response after three months.

• Early changes in serum CGRP may be important for the clinical effect of erenumab in migraine.

Different dosage regimens of erenumab for the treatment of migraine: A systematic review and meta-analysis of the efficacy and safety of randomized controlled trials

BACKGROUND

Migraine is a worldwide epidemic neurological disorder that has a significant influence on the quality of life. Migraine attacks are considered to be related to a calcitonin gene-related peptide (CGRP) signaling molecule, and anti-CGRP medications are used to abort and prevent migraine attacks. Erenumab, a monoclonal antibody that targets the CGRP receptor, is the first migraine preventive medication approved by the US Food and Drug Administration. In the present study, we evaluate the efficacy and safety of erenumab.

OBJECTIVE

This study aims to systematically assess the efficacy and safety of erenumab as a migraine preventive treatment compared to a placebo.

METHODS

Randomized, placebo-controlled, single or double-blind trials were searched through MEDLINE, Embase, Cochrane Library, and ClinicalTrials.gov up to May 2022. The efficacy outcomes we collected include changes from baseline on monthly migraine days, monthly acute migraine-specific medication days, ≥50% responder rate, ≥75% responder rate, and 100% responder rate at week 12. Safety outcomes include treatment emergent adverse events, serious adverse events, and any adverse event that leads to discontinuation of treatment. The study was registered with PROSPERO (Registry number: CRD42022338861).

RESULT

In all eight included trials, we found that erenumab (28, 70, and 140 mg) is very effective and has a significantly greater reduction in baseline monthly migraine days (28 mg: mean difference [MD] = -1.1, 95% confidence interval [CI]: -2.0 to -0.2, p = 0.020; 70 mg: MD = -1.4, 95% CI: -1.8 to -1.1, p < 0.001, I²  = 26%; 140 mg: MD = -1.8, 95% CI: -2.1 to -1.4, p < 0.001, I²  = 0%) than placebo at week 12, especially with 140 mg. Otherwise, we found that there were no statistical differences in the occurrence of adverse events (7 mg: risk ratio [RR] = 0.9, 95% CI: 0.7 to 1.2, p = 0.570; 21 mg: RR = 1.0, 95% CI: 0.8 to 1.2, p = 0.730; 28 mg: RR = 0.9, 95% CI: 0.7 to 1.1, p = 0.340; 70 mg: RR = 1.0, 95% CI: 0.9 to 1.0, p = 0.230, I²  = 0%; 140 mg: RR = 1.0, 95% CI: 0.9 to 1.1, p = 0.880, I²  = 40%) between the erenumab and placebo groups.

CONCLUSIONS

In our study, we found that erenumab, especially at the dose of 140 mg, is an effective and well-tolerated preventive treatment for migraine.

Involvement of the cerebellum in migraine

Migraine is a disabling neurological disease characterized by moderate or severe headaches and accompanied by sensory abnormalities, e.g., photophobia, allodynia, and vertigo. It affects approximately 15% of people worldwide. Despite advancements in current migraine therapeutics, mechanisms underlying migraine remain elusive. Within the central nervous system, studies have hinted that the cerebellum may play an important sensory integrative role in migraine. More specifically, the cerebellum has been proposed to modulate pain processing, and imaging studies have revealed cerebellar alterations in migraine patients. This review aims to summarize the clinical and preclinical studies that link the cerebellum to migraine. We will first discuss cerebellar roles in pain modulation, including cerebellar neuronal connections with pain-related brain regions. Next, we will review cerebellar symptoms and cerebellar imaging data in migraine patients. Lastly, we will highlight the possible roles of the neuropeptide calcitonin gene-related peptide (CGRP) in migraine symptoms, including preclinical cerebellar studies in animal models of migraine.

European Headache Federation (EHF) consensus on the definition of effective treatment of a migraine attack and of triptan failure

Background

Triptans are migraine-specific acute treatments. A well-accepted definition of triptan failure is needed in clinical practice and for research. The primary aim of the present Consensus was to provide a definition of triptan failure. To develop this definition, we deemed necessary to develop as first a consensus definition of effective treatment of an acute migraine attack and of triptan-responder.

Main body

The Consensus process included a preliminary literature review, a Delphi round and a subsequent open discussion. According to the Consensus Panel, effective treatment of a migraine attack is to be defined on patient well-being featured by a) improvement of headache, b) relief of non-pain symptoms and c) absence of adverse events. An attack is considered effectively treated if patient’s well-being, as defined above, is restored within 2 hours and for at least 24 hours. An individual with migraine is considered as triptan-responder when the given triptan leads to effective acute attack treatment in at least three out of four migraine attacks. On the other hand, an individual with migraine is considered triptan non-responder in the presence of failure of a single triptan (not matching the definition of triptan-responder). The Consensus Panel defined an individual with migraine as triptan-resistant in the presence of failure of at least 2 triptans; triptan refractory, in the presence of failure to at least 3 triptans, including subcutaneous formulation; triptan ineligibile in the presence of an acknowledged contraindication to triptan use, as specified in the summary of product characteristics.

Conclusions

The novel definitions can be useful in clinical practice for the assessment of acute attack treatments patients with migraine. They may be helpful in identifying people not responding to triptans and in need for novel acute migraine treatments. The definitions will also be of help in standardizing research on migraine acute care.

Supplementary Information

The online version contains supplementary material available at 10.1186/s10194-022-01502-z.

Focus on zavegepant: the first intranasal third-generation gepant

Migraine is the leading cause of years lived with disability in people under 50 and its burden is increased by calcitonin gene-related peptide (CGRP)-driven chronicity. Newly approved small molecules that antagonize the CGRP receptor, gepants, have advanced from the hepatotoxic first-generation telcagepant to third-generation intranasal zavegepant; during this process of drug development, rimegepant, ubrogepant and atogepant, which are orally administered, have been launched and approved for clinical use with no warning for hepatotoxicity. Real-world, long-term postmarketing data about the efficacy and safety of gepants are awaited. The aim of the present drug evaluation study was to provide an overview of the novel, third-generation intranasal Zavegepant, encompassing its development and future perspectives.

Calcitonin gene-related peptide (CGRP) is a key molecule released in acute migraine attacks-Successful translation of basic science to clinical practice

Migraine is a highly prevalent neurovascular disorder afflicting more than 15% of the global population. Nearly three times more females are afflicted by migraine in the 18-50 years age group, compared to males. Migraine attacks are most often sporadic, but a subgroup of individuals experience a gradual increase in frequency over time; among these, up to 1%-2% of the global population develop chronic migraine. Although migraine symptoms have been known for centuries, the underlying mechanisms remain largely unknown. Two theories have dominated the current thinking-a neurovascular theory and a central neuronal theory with the origin of the attacks in the hypothalamus. During the last decades, the understanding of migraine has markedly advanced. This is supported by the early seminal demonstration of the trigeminovascular reflex 35 years ago and the insight that calcitonin gene-related peptide (CGRP) is a key molecule released in acute migraine attacks. The more recent findings that gepants, small molecule CGRP receptor blockers, and monoclonal antibodies generated against CGRP, or its canonical receptor are useful for the treatment of migraine, are other important issues. CGRP has been established as a key molecule in the neurobiology of migraine. Moreover, monoclonal antibodies to CGRP or the CGRP receptor represent a breakthrough in the understanding of migraine pathophysiology and have emerged as an efficacious prophylactic treatment for patients with severe migraine with excellent tolerability. This review describes the progression of research to reach the clinical usefulness of a large group of molecules that have in common the interaction with CGRP mechanisms in the trigeminal system to alleviate the burden for individuals afflicted by migraine.

Prevention of Migraine

Migraine, a primary headache disorder is a chronic and complex neurological disease that affects millions of people worldwide, impacting their quality of life. It is one of the most common reasons why individuals seek the advice of their physician, and is one of the most common referrals seen in the offices of general neurologists and headache specialists. In the past decade, there has been robust research on not only the pathophysiology of migraine but in the efforts to treat and, importantly, prevent. The introduction of calcitonin gene related peptide antagonists (CGRP-A) have opened new doors for preventive treatment options. OnabotulinumtoxinA (BoNTA) has remained a staple in the treatment of chronic migraine with data emerging with combination therapy. Neurostimulation has offered additional nonpharmacologic approaches to migraine treatment. In addition to lifestyle and behavioral modifications, these have changed the landscape of migraine prevention.

Real-World Patient Experience of CGRP-Targeting Therapy for Migraine: a Narrative Review

PURPOSE OF REVIEW

To summarize available calcitonin gene-related peptide (CGRP)-targeting therapies for migraine and discuss their use in real-world populations.

BACKGROUND

CGRP has long been a topic of interest in migraine pathophysiology, with new therapies targeting CGRP since 2018 for both the preventive and acute treatment of migraine.

METHODS

We searched PubMed using keywords including "migraine," "CGRP," "real-world," "erenumab," "galcanezumab," "fremanezumab," "eptinezumab," "ubrogepant," "rimegepant," and "atogepant." We reviewed all pertinent studies and summarized main findings. We also compiled detailed patient characteristics (e.g., migraine diagnoses, medication overuse, prior treatment failures) and treatment outcome measures, such as 50% responder rates, reduction in migraine days, and adverse event rates in several tables. Overall, studies reporting real-world patient experiences of CGRP-targeting therapies suggested meaningful effectiveness for migraine treatment with response rates comparable to the numbers reported in clinical trials. Furthermore, studies suggested benefit in patients with multiple prior unsuccessful treatment trials, medication overuse, and complex medical comorbidities. In some studies, adverse event rates have been notably higher than reported in clinical trials. Additional long-term data is needed to further evaluate sustained efficacy, predictors of treatment response, and adverse events.

Sumatriptan prevents central sensitisation specifically in the trigeminal dermatome in humans

BACKGROUND

The exact mechanism and site of action of triptans in aborting migraine attacks remain under debate. We hypothesized that the clinical efficacy of triptans lies in aborting central sensitization and focused on the question of why triptans are headache-specific, i.e. highly effective in migraine and cluster headache and ineffective in extracephalic pain.

METHODS

Forty healthy participants were enrolled in this double-blinded, randomized, placebo-controlled study. The effect of sumatriptan (n=20) vs placebo (n=20) was investigated in a cephalic (V1) vs an extracephalic dermatome (forearm) using a topical capsaicin sensitization model. Capsaicin-induced primary and secondary hyperalgesia were evaluated using quantitative sensory testing.

RESULTS

After capsaicin application, primary hyperalgesia developed in both sumatriptan and placebo groups in both dermatomes. However, sumatriptan exclusively prevented secondary hyperalgesia in the V1 dermatome but not on the forearm. Placebo exerted no effects on secondary hyperalgesia in both trigeminal and extracephalic dermatomes. Additionally, sumatriptan reduced the flare size exclusively in the V1 dermatome.

CONCLUSIONS

Our data suggest that sumatriptan reduces central sensitization (secondary hyperalgesia) without modulating peripheral sensitization (primary hyperalgesia) in a human pain model of capsaicin-induced sensitization. Moreover, despite a systemic administration of sumatriptan, the modulatory effects are trigeminal-specific, echoing the clinical effect of triptans in aborting headaches, but not extracephalic pain.

Nitroglycerin as a model of migraine: Clinical and preclinical review

Migraine stands as one of the most disabling neurological conditions worldwide. It is a disorder of great challenge to study given its heterogeneous representation, cyclic nature, and complexity of neural networks involved. Despite this, clinical and preclinical research has greatly benefitted from the use of the nitric oxide donor, nitroglycerin (NTG), to model this disorder, dissect underlying mechanisms, and to facilitate the development and screening of effective therapeutics. NTG is capable of triggering a migraine attack, only in migraineurs or patients with a history of migraine and inducing migraine-like phenotypes in rodent models. It is however unclear to what extent NTG and NO, as its breakdown product, is a determinant factor in the underlying pathophysiology of migraine, and importantly, whether it really does facilitate the translation from the bench to the bedside, and vice-versa. This review provides an insight into the evidence supporting the strengths of this model, as well as its limitations, and shines a light into the possible role of NO-related mechanisms in altered molecular signalling pathways.