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Migraine is a common, disabling neurological disorder characterized by multiple phases: premonitory, aura, headache, postdrome, and interictal. Our understanding of the pathophysiology of each phase of migraine has evolved over recent years. The premonitory phase begins as early as 3 days before the headache phase, and involves a complex interplay between various cortical and subcortical brain regions, including the hypothalamus and brainstem nuclei that modulate nociceptive signaling. The headache phase involves activation of the trigeminovascular system, a pathway that is well characterized. In one‐third of patients, an aura phase may occur during some attacks and likely correlates with a cortical spreading depression‐like event; a slowly propagating wave of neuronal and glial cell depolarization and hyperpolarization. Improved characterization of the pathophysiological processes involved at each stage of the migraine attack will aid the identification of new therapeutic targets for migraine prevention. This review provides an update on prevailing concepts of migraine pathophysiology.

Objective To evaluate the efficacy and tolerability of single pulse transcranial magnetic stimulation (sTMS) for the preventive treatment of migraine. Background sTMS was originally developed for the acute treatment of migraine with aura. Open label experience has suggested a preventive benefit. The objective of this trial was to evaluate the efficacy and tolerability of sTMS for migraine prevention. Methods The eNeura SpringTMS Post-Market Observational U.S. Study of Migraine (ESPOUSE) Study was a multicenter, prospective, open label, observational study. From December 2014 to March 2016, patients with migraine (n = 263) were consented to complete a 1-month baseline headache diary followed by 3 months of treatment. The treatment protocol consisted of preventive (four pulses twice daily) and acute (three pulses repeated up to three times for each attack) treatment. Patients reported daily headache status, medication use, and device use with a monthly headache diary. The primary endpoint, mean reduction of headache days compared to baseline, was measured over the 28-day period during weeks 9 to 12. The primary endpoint was compared to a statistically-derived placebo estimate (performance goal). Secondary endpoints included: 50% responder rate, acute headache medication consumption, HIT-6, and mean reduction in total headache days from baseline of any intensity. Results Of a total of 263 consented subjects, 229 completed a baseline diary, and 220 were found to be eligible based on the number of headache days. The device was assigned to 217 subjects (Safety Data Set) and 132 were included in the intention to treat Full Analysis Set. For the primary endpoint, there was a −2.75 ± 0.40 mean reduction of headache days from baseline (9.06 days) compared to the performance goal (−0.63 days) ( p < 0.0001). The 50% responder rate of 46% (95% CI 37%, 56%) was also significantly higher ( p < 0.0001) than the performance goal (20%). There was a reduction of −2.93 (5.24) days of acute medication use, headache impact measured by HIT-6, −3.1 (6.4) ( p < 0.0001), and total headache days of any intensity −3.16 days (5.21) compared to the performance goal (−0.63 days) ( p < 0.0001). The most common adverse events were lightheadedness (3.7%), tingling (3.2%), and tinnitus (3.2%). There were no serious adverse events. Conclusions This open label study suggests that sTMS may be an effective, well-tolerated treatment option for migraine prevention. Trial registration number NCT02357381

Background Quality clinical trials form an essential part of the evidence base for the treatment of headache disorders. In 1991, the International Headache Society Clinical Trials Standing Committee developed and published the first edition of the Guidelines for Controlled Trials of Drugs in Migraine. In 2008, the Committee published the first specific guidelines on chronic migraine. Subsequent advances in drug, device, and biologicals development, as well as novel trial designs, have created a need for a revision of the chronic migraine guidelines. Objective The present update is intended to optimize the design of controlled trials of preventive treatment of chronic migraine in adults, and its recommendations do not apply to trials in children or adolescents.

Background Calcitonin gene-related peptide plays an important role in migraine pathophysiology. Erenumab, a human monoclonal antibody that inhibits the calcitonin gene-related peptide receptor, is being evaluated for migraine prevention. Methods In this randomized, double-blind, placebo-controlled, phase 3 study, 577 adults with episodic migraine were randomized to placebo or 70 mg erenumab; 570 patients were included in efficacy analyses. Primary endpoint was change in monthly migraine days. Secondary endpoints were ≥50% reduction in monthly migraine days, change in acute migraine-specific medication treatment days, and ≥5-point reduction in Physical Impairment and Impact on Everyday Activities domain scores measured by the Migraine Physical Function Impact Diary. All endpoints assessed change from baseline at month 3. Results Patients receiving erenumab experienced −2.9 days change in monthly migraine days, compared with −1.8 days for placebo, least-squares mean (95% CI) treatment difference of −1.0 (−1.6, −0.5) ( p < 0.001). A ≥ 50% reduction in monthly migraine days was achieved by 39.7% (erenumab) and 29.5% (placebo) of patients (OR:1.59 (95% CI: 1.12, 2.27) ( p = 0.010). Migraine-specific medication treatment days were reduced by −1.2 (erenumab) and −0.6 (placebo) days, a treatment difference of −0.6 (−1.0, −0.2) ( p = 0.002). The ≥5-point reduction rates in Migraine Physical Function Impact Diary – Physical Impairment were 33.0% and 27.1% (OR:1.33 (0.92, 1.90) ( p = 0.13) and in Migraine Physical Function Impact Diary – Everyday Activities were 40.4% and 35.8% (OR:1.22 (0.87, 1.71) ( p = 0.26). Safety and adverse event profiles of erenumab were similar to placebo. Most frequent adverse events were upper respiratory tract infection, injection site pain, and nasopharyngitis. Conclusions As a preventive treatment of episodic migraine, erenumab at a dosage of 70 mg monthly significantly reduced migraine frequency and acute migraine-specific medication use. (Funded by Amgen). Trial registration ClinicalTrials.gov, NCT02483585.

AbstractThe response of diffuse noxious inhibitory controls (DNIC) is often decreased, or lost, in stress-related functional pain syndromes. Because the dynorphin/kappa opioid receptor (KOR) pathway is activated by stress, we determined its role in DNIC using a model of stress-induced functional pain. Male, Sprague-Dawley rats were primed for 7 days with systemic morphine resulting in opioid-induced hyperalgesia. Fourteen days after priming, when hyperalgesia was resolved, rats were exposed to environmental stress and DNIC was evaluated by measuring hind paw response threshold to noxious pressure (test stimulus) after capsaicin injection in the forepaw (conditioning stimulus). Morphine priming without stress did not alter DNIC. However, stress produced a loss of DNIC in morphine-primed rats in both hind paws that was abolished by systemic administration of the KOR antagonist, nor-binaltorphimine (nor-BNI). Microinjection of nor-BNI into the right, but not left, central nucleus of the amygdala (CeA) prevented the loss of DNIC in morphine-primed rats. Diffuse noxious inhibitory controls were not modulated by bilateral nor-BNI in the rostral ventromedial medulla. Stress increased dynorphin content in both the left and right CeA of primed rats, reaching significance only in the right CeA; no change was observed in the rostral ventromedial medulla or hypothalamus. Although morphine priming alone is not sufficient to influence DNIC, it establishes a state of latent sensitization that amplifies the consequences of stress. After priming, stress-induced dynorphin/KOR signaling from the right CeA inhibits DNIC in both hind paws, likely reflecting enhanced descending facilitation that masks descending inhibition. Kappa opioid receptor antagonists may provide a new therapeutic strategy for stress-related functional pain disorders.