Cortical spreading depression triggers migraine attack: pro

Focal brain cooling suppresses spreading depolarization and reduces endothelial nitric oxide synthase expression in rats

This study aimed to investigate the effects of focal brain cooling (FBC) on spreading depolarization (SD), which is associated with several neurological disorders. Although it has been studied from various aspects, no medication has been developed that can effectively control SD. As FBC can reduce neuronal damage and promote functional recovery in pathological conditions such as epilepsy, cerebral ischemia, and traumatic brain injury, it may also potentially suppress the onset and progression of SD. We created an experimental rat model of SD by administering 1 M potassium chloride (KCl) to the cortical surface. Changes in neuronal and vascular modalities were evaluated using multimodal recording, which simultaneously recorded brain temperature (BrT), wide range electrocorticogram, and two-dimensional cerebral blood flow. The rats were divided into two groups (cooling [CL] and non-cooling [NC]). Warm or cold saline was perfused on the surface of one hemisphere to maintain BrT at 37°C or 15°C in the NC and CL groups, respectively. Western blot analysis was performed to determine the effects of FBC on endothelial nitric oxide synthase (eNOS) expression. In the NC group, KCl administration triggered repetitive SDs (mean frequency = 11.57/h). In the CL group, FBC increased the duration of all KCl-induced events and gradually reduced their frequency. Additionally, eNOS expression decreased in the cooled brain regions compared to the non-cooled contralateral hemisphere. The results obtained by multimodal recording suggest that FBC suppresses SD and decreases eNOS expression. This study may contribute to developing new treatments for SD and related neurological disorders.

Potential of focal cortical dysplasia in migraine pathogenesis

Focal cortical dysplasias are abnormalities of the cerebral cortex associated with an elevated risk of neurological disturbances. Cortical spreading depolarization/depression is a correlate of migraine aura/headache and a trigger of migraine pain mechanisms. However, cortical spreading depolarization/depression is associated with cortical structural changes, which can be classified as transient focal cortical dysplasias. Migraine is reported to be associated with changes in various brain structures, including malformations and lesions in the cortex. Such malformations may be related to focal cortical dysplasias, which may play a role in migraine pathogenesis. Results obtained so far suggest that focal cortical dysplasias may belong to the causes and consequences of migraine. Certain focal cortical dysplasias may lower the threshold of cortical excitability and facilitate the action of migraine triggers. Migraine prevalence in epileptic patients is higher than in the general population, and focal cortical dysplasias are an established element of epilepsy pathogenesis. In this narrative/hypothesis review, we present mainly information on cortical structural changes in migraine, but studies on structural alterations in deep white matter and other brain regions are also presented. We develop the hypothesis that focal cortical dysplasias may be causally associated with migraine and link pathogeneses of migraine and epilepsy.

Rizatriptan benzoate-loaded dissolving microneedle patch for management of acute migraine therapy

In this study, dissolving microneedles (MNs) using polyvinyl alcohol (PVA) and poly (1-vinylpyrrolidone-co-vinyl acetate) (P(VP-co-VA)) as matrix materials were developed for transdermal delivery of rizatriptan benzoate (RB) for acute migraine treatment. In-vitro permeation studies were conducted to assess the feasibility of the as-fabricated dissolving MNs to release RB. Drug skin penetration were tested by Franz diffusion cells, showing an increase of the transdermal flux compared to passive diffusion due to the as-fabricated dissolving MNs having a sufficient mechanical strength to penetrate the skin and form microchannels. The pharmacological study in vivo showed that RB-loaded dissolving MNs significantly alleviated migraine-related response by up-regulating the level of 5-hydroxytryptamine (5-HT) and down-regulating the levels of calcitonin gene-related peptide (CGRP) and substance P (SP). In conclusion, the RB-loaded dissolving MNs have advantages of safety, convenience, and high efficacy over conventional administrations, laying a foundation for the transdermal drug delivery system treatment for acute migraine.

Investigations of the migraine-provoking effect of levcromakalim in patients with migraine with aura

BACKGROUND/HYPOTHESIS

Experimental provocation studies have yielded important insights in migraine pathophysiology. Levcromakalim has been previously shown to induce migraine-like attacks with and without aura. In this study, we aim to further explore the migraine aura-inducing potential of levcromakalim.

METHODS

In a double-blind, randomized, placebo-controlled cross-over study, 27 adult participants with migraine with aura received intravenous infusions of levcromakalim and saline. Headache, aura and associated symptoms were evaluated for 24 hours following administration of the study drug. The primary endpoint was occurrence of migraine-like attacks with or without aura in the 24-hour observation period.

RESULTS

Thirteen participants developed migraine-like attacks on the active day only (P = 0.0098), and four participants developed aura on the active day only (P = 0.68). The median time to onset of migraine-like headache was three hours, and the median time to onset of aura was 27.5 minutes.

CONCLUSION/INTERPRETATION

Our findings affirm the potent migraine-inducing effect of levcromakalim. We observed a lower induction-rate of migraine aura than previously reported. Further studies are warranted to identify predictors of migraine aura following levcromakalim.

CLINICALTRIALS.GOV IDENTIFIER

NCT04905654.

Vagus nerve stimulation inhibits cortical spreading depression via glutamate-dependent TrkB activation mechanism in the nucleus tractus solitarius

BACKGROUND

Vagus nerve stimulation (VNS) was recently found to inhibit cortical spreading depression (CSD), the underlying mechanism of migraine aura, through activation of the nucleus tractus solitarius (NTS), locus coeruleus (LC) and dorsal raphe nucleus (DRN). The molecular mechanisms underlying the effect of VNS on CSD in these nuclei remain to be explored. We hypothesized that VNS may activate glutamate receptor-mediated tropomyosin kinase B (TrkB) signaling in the NTS, thereby facilitating the noradrenergic and serotonergic neurotransmission to inhibit CSD.

METHODS

To investigate the role of TrkB and glutamate receptors in non-invasive VNS efficacy on CSD, a validated KCl-evoked CSD rat model coupled with intra-NTS microinjection of selective antagonists, immunoblot and immunohistochemistry was employed.

RESULTS

VNS increased TrkB phosphorylation in the NTS. Inhibition of intra-NTS TrkB abrogated the suppressive effect of VNS on CSD and CSD-induced cortical neuroinflammation. TrkB was found colocalized with glutamate receptors in NTS neurons. Inhibition of glutamate receptors in the NTS abrogated VNS-induced TrkB activation. Moreover, the blockade of TrkB in the NTS attenuated VNS-induced activation of the LC and DRN.

CONCLUSIONS

VNS induces the activation of glutamate receptor-mediated TrkB signaling in the NTS, which might modulate serotonergic and norepinephrinergic innervation to the cerebral cortex to inhibit CSD and cortical inflammation.

Reduction in retinal microvascular perfusion during migraine attacks

OBJECTIVE

To determine if there are changes in structure and function of the retinal vasculature during and between migraine attacks using optical coherence tomography angiography (OCTA).

BACKGROUND

Migraine attacks commonly include visual symptoms, but the potential role of the retina in these symptoms is not well understood. OCTA is a rapid, non-invasive imaging technique that is used to visualize the retinal microvasculature with high spatial resolution in a clinical setting. In this study we used OCTA to quantify different features of the retinal vasculature in patients with migraine during and between attacks, as well as in healthy controls (HCs).

METHODS

We performed a prospective cohort study of 37 patients with migraine with aura (MA) (median [interquartile range, IQR] age of 37 [14] years, 86% female) and 30 with migraine without aura (MO) (median [IQR] age of 37 [17] years, 77% female) and 20 HCs (median [IQR] age of 35 [7] years, 50% female). Macular OCTA scans were obtained for all participants for the interictal analysis. In 12 MA and eight MO, scans were captured both during and outside of migraine attacks and five HCs had initial and repeat scans. In addition to analyzing the morphology of the foveal avascular zone, we calculated the vessel flux index (VFI), which is an indicator of retinal perfusion and conventional metrics (such as vessel area density) in the foveal and parafoveal regions.

RESULTS

There was a significant difference in the parafoveal VFI in the ictal state between the groups (p = 0.009). During migraine attacks there was a significant reduction in the parafoveal region VFI in MA (-7%, 95% confidence interval [CI] -10% to -4%; p = 0.006) and MO (-7%, 95% CI -10% to -3%; p = 0.016) from their interictal baseline as compared to the change between repeat scans in HCs (2%, 95% CI -3% to 7%). Interictally, there was a mean (standard deviation [SD]) 13% (10%) (p = 0.003) lower blood perfusion in the MA group as compared to the MO group in the foveal region (mean [SD] 0.093 [0.023] vs. 0.107 [0.021], p = 0.003). Interictal analysis also revealed higher circularity in the superficial foveal avascular zone in the MA group compared with the MO group (mean [SD] 0.686 [0.088] vs. 0.629 [0.120], p = 0.004). In addition, interictal analysis of the patients with MA or MO and unilateral headache showed increased retinal vascular parameters consistent with greater perfusion in the eye ipsilateral to the side of the pain as compared with the contralateral eye.

CONCLUSIONS

These results indicate that perfusion is reduced in MA and MO in the parafoveal retina during the ictal period. Interictally, the foveal retina in MA has reduced perfusion when compared to the foveal retina in MO. Patients with unilateral headache showed interictal asymmetry of retinal perfusion between eyes. These results indicate that changes in retinal perfusion could be a part of migraine pathophysiology, and that distinct retinal vascular signatures identified with OCTA could represent biomarkers for migraine.

Persistent headache attributed to past ischemic stroke: A prospective cohort study

OBJECTIVE

To assess the incidence, characteristics, and risk factors for developing persistent headache attributed to past ischemic stroke.

BACKGROUND

Although the most recent International Classification of Headache Disorders has recognized the existence of persistent headache attributed to past ischemic stroke, there has been limited research in this area.

METHODS

This was a prospective cohort study. We initially assessed patients hospitalized with ischemic stroke admitted within 72 h of symptom onset. All patients underwent diffusion-weighted magnetic resonance imaging. These patients were re-interviewed by telephone 1 year after the stroke. Semi-structured questionnaires, the National Institutes of Health Stroke Scale (NIHSS), and six-item Headache Impact Test were used.

RESULTS

A total of 119 participants answered the interview conducted 1 year after the stroke. The mean (standard deviation) age was 64 (13.1) years, 82/119 (68.9%) were female, and the median (interquartile range) NIHSS score was 2 (1.0-4.0). The incidence rate of persistent headache attributed to past ischemic stroke was 12/119 (10.1%; 95% confidence interval [CI] 5.3-17.0%). The most frequent pattern presented was a migraine-like pattern in seven of the 12 (58.3%) patients, which had a substantial/severe impact on five of the 12 (41.7%). For most patients this headache continued, although it began to improve. Previous migraine (odds ratio 7.1, 95% CI 1.06-50.0; p = 0.043) and headache intensity in the acute phase of stroke (odds ratio 1.75, 95% CI 1.13-2.7; p = 0.012) were associated with the occurrence of persistent headache attributed to past ischemic stroke.

CONCLUSION

Persistent headache attributed to past ischemic stroke is a frequent complication after stroke. It often has a significant impact on patients' lives and presents a migraine-like pattern as its most frequent phenotype.

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.

A hyperthermic seizure unleashes a surge of spreading depolarizations in Scn1a-deficient mice

Spreading depolarization (SD) is a massive wave of cellular depolarization that slowly migrates across the brain gray matter. Cortical SD is frequently generated following brain injury, while less is understood about its potential contribution to genetic disorders of hyperexcitability, such as SCN1A-deficient epilepsy, in which febrile seizure often contributes to disease initiation. Here we report that spontaneous SD waves are predominant EEG abnormalities in the Scn1a-deficient mouse (Scn1a+/R1407X) and undergo sustained intensification following a single hyperthermic seizure. Chronic DC-band EEG recording detected spontaneous SDs, seizures, and seizure-SD complexes in Scn1a+/R1407X mice but not WT littermates. The SD events were infrequent, while a single hyperthermia-induced seizure robustly increased SD frequency over 4-fold during the initial postictal week. This prolonged neurological aftermath could be suppressed by memantine administration. Video, electromyogram, and EEG spectral analysis revealed distinct neurobehavioral patterns; individual seizures were associated with increased motor activities, while SDs were generally associated with immobility. We also identified a stereotypic SD prodrome, detectable over a minute before the onset of the DC potential shift, characterized by increased motor activity and bilateral EEG frequency changes. Our study suggests that cortical SD is a pathological manifestation in SCN1A-deficient epileptic encephalopathy.

Role of Vagus Nerve Stimulation in the Treatment of Chronic Pain

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

Estrogen modulation of cortical spreading depression

BACKGROUND AND AIMS

Cortical spreading depression (CSD), a transient neuronal and glial depolarization that propagates slowly across the cerebral cortex, is the putative electrophysiological event underlying migraine aura and a headache trigger. Migraine is three times more prevalent in women than men, linked to circulating female hormones. High estrogen levels or estrogen withdrawal may be a migraine trigger for many women. We, therefore, aimed to examine whether sex, gonadectomy, and female hormone supplementation and withdrawal affect the susceptibility to CSD.

METHODS

To determine CSD susceptibility, we recorded the frequency of CSDs triggered during 2-h topical KCl application in intact or gonadectomized female and male rats, without or with estradiol or progesterone supplementation via daily intraperitoneal injections. Estrogen or progesterone treatment followed by withdrawal was studied in a separate cohort. To take the first step towards identifying potential mechanisms, we studied glutamate and GABAA receptor binding using autoradiography.

RESULTS

The CSD frequency in intact female rats was higher than intact male and ovariectomized rats. We did not detect a change in CSD frequency during different stages of the estrous cycle in intact females. Daily estrogen injections for three weeks did not change CSD frequency. However, one-week estrogen withdrawal after two weeks of treatment significantly increased CSD frequency compared with the vehicle group in gonadectomized females. The same protocol of estrogen treatment and withdrawal was ineffective in gonadectomized males. In contrast to estrogen, daily progesterone injections for three weeks elevated CSD susceptibility, and one-week withdrawal after two weeks of treatment partially normalized this effect. Autoradiography did not reveal significant changes in glutamate or GABAA receptor binding density after estrogen treatment and withdrawal.

CONCLUSIONS

These data suggest that females are more susceptible to CSD, and sexual dimorphism is abrogated by gonadectomy. Moreover, estrogen withdrawal after prolonged daily treatment enhances CSD susceptibility. These findings may have implications for estrogen-withdrawal migraine, although the latter tends to be without aura.

Noninvasive vagus nerve stimulation for migraine: a systematic review and meta-analysis of randomized controlled trials

Background

Medication is commonly used to treat migraine. However, patients may experience adverse events or fail to respond to medication. In recent years, neuromodulation techniques have emerged as potential non-pharmacological therapy for migraine. This article focuses on a systematic review and meta-analysis of randomized controlled trials of non-invasive vagus nerve stimulation (n-VNS) for migraine to determine the efficacy, safety and tolerability of n-VNS.

Methods

We searched PUBMED, EMBASE, and Cochrane Center Register of Controlled Trials databases up to July 15, 2022. Primary outcomes were monthly reduced migraine/headache days, and pain-free rates within 2 h. Secondary outcomes were  ≥ 50% responder rate, headache intensity, monthly acute medication reduction days, and adverse events.

Results

Meta-analysis shows that non-invasive cervical vagus nerve stimulation (n-cVNS) significantly impacted ≥50% responder rate (OR, 1.64; 95% CI, 1.1 to 2.47; p = 0.02), but had no significant effect on reducing migraine days (MD, -0.46; 95% CI, -1.21 to 0.29; p = 0.23) and headache days (MD, -0.68; 95% CI, -1.52 to 0.16; p = 0.11). In contrast, low-frequency non-invasive auricular vagus nerve stimulation (n-aVNS) was found to significantly reduce the number of migraine days (MD, -1.8; 95% CI, -3.34 to -0.26; p = 0.02) and headache intensity (SMD, -0.7; 95% CI, -1.23 to -0.17; p = 0.009), but not the number of acute medication days per month (MD, -1.1; 95% CI, -3.84 to 1.64; p = 0.43). In addition, n-cVNS was found safe and well-tolerated in most patients.

Conclusion

These findings show that n-VNS is a promising method for migraine management.

Prolactin and oxytocin: potential targets for migraine treatment

Migraine is a severe neurovascular disorder of which the pathophysiology is not yet fully understood. Besides the role of inflammatory mediators that interact with the trigeminovascular system, cyclic fluctuations in sex steroid hormones are involved in the sex dimorphism of migraine attacks. In addition, the pituitary-derived hormone prolactin and the hypothalamic neuropeptide oxytocin have been reported to play a modulating role in migraine and contribute to its sex-dependent differences. The current narrative review explores the relationship between these two hormones and the pathophysiology of migraine. We describe the physiological role of prolactin and oxytocin, its relationship to migraine and pain, and potential therapies targeting these hormones or their receptors.In summary, oxytocin and prolactin are involved in nociception in opposite ways. Both operate at peripheral and central levels, however, prolactin has a pronociceptive effect, while oxytocin appears to have an antinociceptive effect. Therefore, migraine treatment targeting prolactin should aim to block its effects using prolactin receptor antagonists or monoclonal antibodies specifically acting at migraine-pain related structures. This action should be local in order to avoid a decrease in prolactin levels throughout the body and associated adverse effects. In contrast, treatment targeting oxytocin should enhance its signalling and antinociceptive effects, for example using intranasal administration of oxytocin, or possibly other oxytocin receptor agonists. Interestingly, the prolactin receptor and oxytocin receptor are co-localized with estrogen receptors as well as calcitonin gene-related peptide and its receptor, providing a positive perspective on the possibilities for an adequate pharmacological treatment of these nociceptive pathways. Nevertheless, many questions remain to be answered. More particularly, there is insufficient data on the role of sex hormones in men and the correct dosing according to sex differences, hormonal changes and comorbidities. The above remains a major challenge for future development.

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

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

The NMDA receptor antagonists memantine and ketamine as anti-migraine agents

Migraine is a debilitating disorder affecting females more frequently than males. There is some evidence that drugs targeting glutamate receptors: memantine and ketamine might be beneficial in the therapy of this entity. Therefore, the purpose of this work is to present NMDA receptor antagonists, memantine and ketamine, as potential anti-migraine agents. We searched PubMed/MEDLINE, Embase, and clinical trials submitted to ClinicalTrials.gov to find publications describing eligible trials published between database inception and December 31, 2021. This comprehensive literature review summarizes data on the use of the NMDA receptor antagonists memantine and ketamine in the pharmacotherapy of migraine. Results from 20 previous and recent preclinical experiments are discussed and correlated with 19 clinical trials (including case series, open-label, and randomized placebo-controlled trials). For the purposes of this review, the authors hypothesized that the propagation of SD is a major mechanism in the pathophysiology of migraine. In several animal studies and in vitro studies, memantine and ketamine inhibited or reduced propagation of the SD. In addition, the results of clinical trials suggest that memantine or ketamine may be an effective treatment option for migraine. However, most studies on these agents lack control group. Although further clinical trials are needed, the results suggest that ketamine or memantine may be promising molecules for the treatment of severe migraine. Particular attention should be paid to people who have a treatment-resistant form of migraine with aura or have exhausted existing treatment options. For them, the drugs under discussion could represent an interesting alternative in the future.

Acute headache attributed to ischemic stroke: assessment of its characteristics and associated factors

BACKGROUND

 It is estimated that headache attributed to ischemic stroke occurs in 7.4% to 34% of the cases. Despite its frequency, this headache has been little studied in terms of its risk factors and characteristics.

OBJECTIVE

 To assess the frequency and clinical characteristics of headache attributed to ischemic stroke and the factors associated with its occurrence.

METHODS

 The present was a cross-sectional study which included patients consecutively admitted within 72 hours of the onset of ischemic stroke. A semi-structured questionnaire was used. The patients underwent magnetic resonance imaging.

RESULTS

 A total of 221 patients were included, 68.2% of whom were male, and the mean age was of 68.2 ±  13.8 years. The frequency of headache attributed to ischemic stroke was of 24.9% (95% confidence interval [95%CI]: 19.6-31.1%). The headache had a median duration of 21 hours and most frequently began at the same time as the focal deficit (45.3%), with a gradual onset (83%). It was of moderate intensity, pulsatile (45.3%), bilateral (54.6%), and presented a similar pattern to that of tension-type headache (53.6%). Headache attributed to stroke was significantly associated with previous tension-type headache, and previous migraine with and without aura (logistic regression).

CONCLUSION

 Headache attributed to stroke is common, with a pattern similar to that of tension-type headache, and it is associated with a history of tension-type and migraine headaches.

Genome-wide DNA methylation analysis in an antimigraine-treated preclinical model of cortical spreading depolarization

BACKGROUND

Cortical spreading depolarization, the cause of migraine aura, is a short-lasting depolarization wave that moves across the brain cortex, transiently suppressing neuronal activity. Prophylactic treatments for migraine, such as topiramate or valproate, reduce the number of cortical spreading depression events in rodents.

OBJECTIVE

To investigate whether cortical spreading depolarization with and without chronic treatment with topiramate or valproate affect the DNA methylation of the cortex.

METHODS

Sprague-Dawley rats were intraperitoneally injected with saline, topiramate or valproate for four weeks when cortical spreading depolarization were induced and genome-wide DNA methylation was performed in the cortex of six rats per group.

RESULTS

The DNA methylation profile of the cortex was significantly modified after cortical spreading depolarization, with and without topiramate or valproate. Interestingly, topiramate reduced by almost 50% the number of differentially methylated regions, whereas valproate increased them by 17%, when comparing to the non-treated group after cortical spreading depolarization induction. The majority of the differentially methylated regions lay within intragenic regions, and the analyses of functional group over-representation retrieved several enriched functions, including functions related to protein processing in the cortical spreading depolarization without treatment group; functions related to metabolic processes in the cortical spreading depolarization with topiramate group; and functions related to synapse and ErbB, MAPK or retrograde endocannabinoid signaling in the cortical spreading depolarization with valproate group.

CONCLUSIONS

Our results may provide insights into the underlying physiological mechanisms of migraine with aura and emphasize the role of epigenetics in migraine susceptibility.

Decrease Retinal Thickness in Patients with Chronic Migraine Evaluated by Optical Coherence Tomography

The purpose of this study is to determine the possible alterations that may occur in the thickness of the retinal nerve fibre layer (RNFL), ganglion cell layer (GCL), and macular thickness in patients with chronic migraines compared with healthy controls. Hence, we examined some of the possibilities that are offered by optical coherence tomography (OCT) in order to study different neurological diseases and to study its application, in this case, how it may be applied to patients with chronic migraines. This was an observational cross-sectional study in adults aged 18-65 years. The study group consisted of 90 patients (90 eyes) with chronic migraines who met the inclusion criteria, and 90 healthy controls (90 eyes) matched for age and sex. Retinal thickness was measured by spectral domain OCT (SD-OCT). The thickness of the superior quadrant of the peripapillary RNFL, as well as the mean thickness in the macula, RNFL macular, and GCL was significantly thinner in chronic migraine patients than in healthy controls (p ≤ 0.05). Chronic migraines are associated with a decrease in retinal thickness which is detectable by an OCT diagnostic technique. The quantification of the axonal damage could be used as a biomarker to help in the diagnosis and monitoring of this pathology. Further studies will be needed to confirm these findings.

The ATP1A2 Mutation Associated with Hemiplegic Migraines: Case Report and Literature Review

Familial hemiplegic migraine type 2 is a premonitory subtype of migraine caused by an ATP1A2 gene mutation. It is an autosomal dominant genetic disease. Here, we report a 51-year-old woman who had a migraine attack due to a pathogenic ATP1A2 gene mutation. With frequent attacks, the patient developed complete left hemiplegia, a confusion of consciousness and partial seizures. Magnetic resonance imaging showed extensive angiogenic edema in the right cerebral hemisphere. In this article, we review the latest literature and try to explain the above symptoms in our patient with cortical spreading depression (CSD) and ATP1A2 gene mutations.

Migraine Pathophysiology Revisited: Proposal of a New Molecular Theory of Migraine Pathophysiology and Headache Diagnostic Criteria

Various explanations for the pathophysiology of migraines have been proposed; however, none of these provide a complete explanation. The author critically reviews previous theories and proposes a new molecular theory of migraine pathophysiology. The diagnosis of primary headaches is generally based on clinical histories and symptoms only because there is no reliable diagnostic examination. The author proposes a new classification system and set of diagnostic criteria for headaches based on molecular markers.

Hyperhomocysteinemia Increases Cortical Excitability and Aggravates Mechanical Hyperalgesia and Anxiety in a Nitroglycerine-Induced Migraine Model in Rats

Homocysteine is a sulfur-containing endogenous amino acid leading to neurotoxic effects at high concentrations. Population studies suggest an association between plasma homocysteine levels and the risk of migraine headaches. The aim of this study was to analyze the sensitivity of rats with prenatal hyperhomocysteinemia (hHCY) in respect of the development of behavioral correlates of headache and spreading cortical depolarization (CSD) in a migraine model induced by the administration of the nitric oxide (NO) donor nitroglycerin. Animals with hHCY were characterized by migraine-related symptoms such as mechanical hyperalgesia, high-level anxiety, photophobia, as well as an enhanced level of neuronal activity in the somatosensory cortex along with a lower threshold of CSD generation. Likewise, acute or chronic intermittent administration of nitroglycerin also induced the development of mechanical allodynia, photophobia and anxiety in control groups. However, these symptoms were more pronounced in rats with hHCY. Unlike hHCY, nitroglycerin administration did not affect the threshold of CSD generation, but like hHCY, increased the background neuronal activity in layers 2/3 and 4 of the cerebral cortex. The latter was more pronounced in animals with hHCY. Thus, the migraine profile associated with hHCY can be further exaggerated in conditions with enhanced levels of migraine triggering the gaseous transmitter NO. Our data are consistent with the view that high levels of plasma homocysteine can act as a risk factor for the development of migraine.

FKN/CX3CR1 axis facilitates migraine-Like behaviour by activating thalamic-cortical network microglia in status epilepticus model rats

Background

The incidence of migraines is higher among individuals with epilepsy than in healthy individuals, and these two diseases are thought to shared pathophysiological mechanisms. Excitation/inhibition imbalance plays an essential role in the comorbidity of epilepsy and migraine. Microglial activation is crucial for abnormal neuronal signal transmission. However, it remains unclear whether and how microglia are activated and their role in comorbidities after being activated. This study aimed to explore the characteristics and mechanism of microglial activation after seizures and their effect on migraine.

Methods

Model rats of status epilepticus (SE) induced by intraperitoneal injection of lithium chloride (LiCl)-pilocarpine and migraine induced by repeated dural injections of inflammatory soup (IS) were generated, and molecular and histopathologic evidence of the microglial activation targets of fractalkine (FKN) signalling were examined. HT22-BV2 transwell coculture assays were used to explore the interaction between neurons and microglia. LPS (a microglial agonist) and FKN stimulation of BV2 microglial cells were used to evaluate changes in BDNF levels after microglial activation.

Results

Microglia were specifically hyperplastic and activated in the temporal lobe cortex, thalamus, and spinal trigeminal nucleus caudalis (sp5c), accompanied by the upregulation of FKN and CX3CR1 four days after seizures. Moreover, SE-induced increases in nociceptive behaviour and FKN/CX3CR1 axis expression in migraine model rats. AZD8797 (a CX3CR1 inhibitor) prevented the worsening of hyperalgesia and microglial activation in migraine model rats after seizures, while FKN infusion in migraine model rats exacerbated hyperalgesia and microglial activation associated with BDNF-Trkb signalling. Furthermore, in neuron-microglia cocultures, microglial activation and FKN/CX3CR1/BDNF/iba1 expression were increased compared with those in microglial cultures alone. Activating microglia with LPS and FKN increased BDNF synthesis in BV2 microglia.

Conclusions

Our results indicated that epilepsy facilitated migraine through FKN/CX3CR1 axis-mediated microglial activation in the cortex/thalamus/sp5c, which was accompanied by BDNF release. Blocking the FKN/CX3CR1 axis and microglial activation are potential therapeutic strategies for preventing and treating migraine in patients with epilepsy.

The headache and aura-inducing effects of sildenafil in patients with migraine with aura

INTRODUCTION

It has not been established if migraine headache and migraine aura share common pathophysiological mechanisms. Sildenafil, a phosphodiesterase-5 inhibitor, causes cGMP accumulation and provokes migraine-like headache in patients with migraine without aura. We investigated if sildenafil induced aura and migraine-like headache in patients with migraine with aura.

METHODS

In a randomized, double-blinded, placebo-controlled crossover study, 16 patients with migraine with aura (of whom 11 patients exclusively had attacks of migraine with aura) received 100 mg sildenafil or placebo on two separate days. The development, duration, and characteristics of aura and headache were recorded using a questionnaire. The primary outcome was the incidence of migraine aura.

RESULTS

Aura symptoms were induced in three patients (19%) after sildenafil and none after placebo (P < 0.001). After administration of sildenafil, 12 patients (75%) developed headache compared with two patients (12.5%) after placebo (Fisher's exact test, P < 0.001). The headache in nine patients (56%) after sildenafil and one patient (6%) after placebo fulfilled the criteria for migraine-like attacks (Fisher's exact test, P = 0.002). All patients, who fulfilled the criteria for migraine-like attacks, reported that the attack mimicked the headache phase during their usual migraine attacks.

DISCUSSION

Sildenafil have a moderate migraine headache-inducing and a modest aura-inducing effect in patients with migraine with aura, even in those who exclusively experienced attacks of migraine with aura in their spontaneous attacks. These findings suggest that accumulation of cGMP by PDE5-inhibition do not play any significant role in the initiation of migraine aura and refute the hypothesis of sildenafil being a tool for pharmacological provocation of this phenomenon. These findings further support dissociation between the aura and the headache phase.Trial registration: ClinicalTrials.gov - NCT02795351.

CADASIL mutations sensitize the brain to ischemia via spreading depolarizations and abnormal extracellular potassium homeostasis

Cerebral autosomal dominant arteriopathy, subcortical infarcts and leukoencephalopathy (CADASIL) is the most common monogenic form of small vessel disease characterized by migraine with aura, leukoaraiosis, strokes and dementia. CADASIL mutations cause cerebrovascular dysfunction in both animal models and humans. Here, we show that two different human CADASIL mutations (Notch3 R90C or R169C) worsen ischemic stroke outcomes in transgenic mice, explained by a higher blood flow threshold to maintain tissue viability. Both mutants developed larger infarcts and worse neurological deficits compared with wild type regardless of age or sex after filament middle cerebral artery occlusion. However, full-field laser speckle flowmetry during distal middle cerebral artery occlusion showed comparable perfusion deficits in mutants and their respective wild type controls. Circle of Willis anatomy and pial collateralization also did not differ among the genotypes. In contrast, mutants had a higher cerebral blood flow threshold below which infarction ensued, suggesting increased sensitivity of brain tissue to ischemia. Electrophysiological recordings revealed a 1.5- to 2-fold higher frequency of peri-infarct spreading depolarizations in CADASIL mutants. Higher extracellular K+ elevations during spreading depolarizations in the mutants implicated a defect in extracellular K+ clearance. Altogether, these data reveal a novel mechanism of enhanced vulnerability to ischemic injury linked to abnormal extracellular ion homeostasis and susceptibility to ischemic depolarizations in CADASIL.

Efficacy profile of noninvasive vagus nerve stimulation on cortical spreading depression susceptibility and the tissue response in a rat model

Background

Noninvasive vagus nerve stimulation (nVNS) has recently emerged as a promising therapy for migraine. We previously demonstrated that vagus nerve stimulation inhibits cortical spreading depression (CSD), the electrophysiological event underlying migraine aura and triggering headache; however, the optimal nVNS paradigm has not been defined.

Methods

Various intensities and doses of nVNS were tested to improve efficacy on KCl-evoked CSD frequency and electrical threshold of CSD in a validated rat model. Chronic efficacy was evaluated by daily nVNS delivery for four weeks. We also examined the effects of nVNS on neuroinflammation and trigeminovascular activation by western blot and immunohistochemistry.

Results

nVNS suppressed susceptibility to CSD in an intensity-dependent manner. Two 2-minute nVNS 5 min apart afforded the highest efficacy on electrical CSD threshold and frequency of KCl-evoked CSD. Daily nVNS for four weeks did not further enhance efficacy over a single nVNS 20 min prior to CSD. The optimal nVNS also attenuated CSD-induced upregulation of cortical cyclooxygenase-2, calcitonin gene-related peptide in trigeminal ganglia, and c-Fos expression in trigeminal nucleus caudalis.

Conclusions

Our study provides insight on optimal nVNS parameters to suppress CSD and suggests its benefit on CSD-induced neuroinflammation and trigeminovascular activation in migraine treatment.

Supplementary Information

The online version contains supplementary material available at 10.1186/s10194-022-01384-1.

Migraine

Migraine is a common, chronic, disorder that is typically characterized by recurrent disabling attacks of headache and accompanying symptoms, including aura. The aetiology is multifactorial with rare monogenic variants. Depression, epilepsy, stroke and myocardial infarction are comorbid diseases. Spreading depolarization probably causes aura and possibly also triggers trigeminal sensory activation, the underlying mechanism for the headache. Despite earlier beliefs, vasodilation is only a secondary phenomenon and vasoconstriction is not essential for antimigraine efficacy. Management includes analgesics or NSAIDs for mild attacks, and, for moderate or severe attacks, triptans or 5HT_1B/1D receptor agonists. Because of cardiovascular safety concerns, unreliable efficacy and tolerability issues, use of ergots to abort attacks has nearly vanished in most countries. CGRP receptor antagonists (gepants) and lasmiditan, a selective 5HT1_F receptor agonist, have emerged as effective acute treatments. Intramuscular onabotulinumtoxinA may be helpful in chronic migraine (migraine on ≥15 days per month) and monoclonal antibodies targeting CGRP or its receptor, as well as two gepants, have proven effective and well tolerated for the preventive treatment of migraine. Several neuromodulation modalities have been approved for acute and/or preventive migraine treatment. The emergence of new treatment targets and therapies illustrates the bright future for migraine management.

Prevalence and impact of visual aura in migraine and probable migraine: a population study

Visual aura (VA) presents in 98% of cases of migraine with aura. However, data on its prevalence and impact in individuals with migraine and probable migraine (PM) are limited. Data from the nation-wide, population-based Circannual Change in Headache and Sleep Study were collected. Participants with VA rating scale scores ≥ 3 were classified as having VA. Of 3,030 participants, 170 (5.6%) and 337 (11.1%) had migraine and PM, respectively; VA prevalence did not differ between these cohorts (29.4% [50/170] vs. 24.3% [82/337], p = 0.219). Participants with migraine with VA had a higher headache frequency per month (4.0 [2.0–10.0] vs. 2.0 [1.0–4.8], p = 0.014) and more severe cutaneous allodynia (12-item Allodynia Symptom Checklist score; 3.0 [1.0–8.0] vs. 2.0 [0.0–4.8], p = 0.046) than those without VA. Participants with PM with VA had a higher headache frequency per month (2.0 [2.0–8.0] vs. 2.0 [0.6–4.0], p = 0.001), greater disability (Migraine Disability Assessment score; 10.0 [5.0–26.3] vs. 5.0 [2.0–12.0], p < 0.001), and more severe cutaneous allodynia (12-item Allodynia Symptom Checklist score, 2.5 [0.0–6.0] vs. 0.0 [0.0–3.0], p < 0.001) than those without VA. VA prevalence was similar between migraine and PM. Some symptoms were more severe in the presence of VA.

Gut microbiota and migraine

Migraine is a leading cause of disability among the adult population and is a significant burden on the economies of the world. Studies into the underlying causes of migraine have spanned centuries but its underlying mechanisms are still not fully understood. In recent years, accumulating evidence implicates that microbiota-mediated gut-brain crosstalk may contribute to the pathogenesis of migraine. This review provides a brief account of the history of migraine theories and summarizes the recent studies showing how gut microbiota is involved in the pathophysiology of migraine. Future research perspectives for better understanding the role of the gut microbiota in migraine are also discussed.

Cortical spreading depression and meningeal nociception

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CSD evoked persistent activation and mechanical sensitization of dural nociceptors is likely to drive the headache phase in migraine with aura.

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The development of neurogenic-mediated dural vasodilatation and increased plasma protein extravasation in the wake of CSD may not contribute to meningeal nociception.

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Cortical vasoconstriction and reduced oxygen availability following CSD do not contribute to meningeal nociception.

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Cortical neuroinflammation, involving neuronal pannexin1 and calcium-independent astrocytic signaling drive meningeal nociception following CSD.

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CSD-related closing of K(ATP) channels and release of COX-driven prostanoids mediate the activation and sensitization of dural nociceptors respectively.

Migraine results in an enormous burden on individuals and societies due to its high prevalence, significant disability, and considerable economic costs. Current treatment options for migraine remain inadequate, and the development of novel therapies is severely hindered by the incomplete understanding of the mechanisms responsible for the pain. The sensory innervation of the cranial meninges is now considered a key player in migraine headache genesis. Recent studies have significantly advanced our understanding of some of the processes that drive meningeal nociceptive neurons, which may be targeted therapeutically to abort or prevent migraine pain. In this review we will summarize our current understanding of the mechanisms that contribute to the genesis of the headache in one migraine subtype – migraine with aura. We will focus on animal studies that address the notion that cortical spreading depression is a critical process that drives meningeal nociception in migraine with aura, and discuss recent insights into some of the proposed underlying mechanisms.

Neurogenic Inflammation: The Participant in Migraine and Recent Advancements in Translational Research

Migraine is a primary headache disorder characterized by a unilateral, throbbing, pulsing headache, which lasts for hours to days, and the pain can interfere with daily activities. It exhibits various symptoms, such as nausea, vomiting, sensitivity to light, sound, and odors, and physical activity consistently contributes to worsening pain. Despite the intensive research, little is still known about the pathomechanism of migraine. It is widely accepted that migraine involves activation and sensitization of the trigeminovascular system. It leads to the release of several pro-inflammatory neuropeptides and neurotransmitters and causes a cascade of inflammatory tissue responses, including vasodilation, plasma extravasation secondary to capillary leakage, edema, and mast cell degranulation. Convincing evidence obtained in rodent models suggests that neurogenic inflammation is assumed to contribute to the development of a migraine attack. Chemical stimulation of the dura mater triggers activation and sensitization of the trigeminal system and causes numerous molecular and behavioral changes; therefore, this is a relevant animal model of acute migraine. This narrative review discusses the emerging evidence supporting the involvement of neurogenic inflammation and neuropeptides in the pathophysiology of migraine, presenting the most recent advances in preclinical research and the novel therapeutic approaches to the disease.

Cortical mechanisms in migraine

Migraine is the second most prevalent disorder in the world; yet, its underlying mechanisms are still poorly understood. Cumulative studies have revealed pivotal roles of cerebral cortex in the initiation, propagation, and termination of migraine attacks as well as the interictal phase. Investigation of basic mechanisms of the cortex in migraine not only brings insight into the underlying pathophysiology but also provides the basis for designing novel treatments. We aim to summarize the current research literatures and give a brief overview of the cortex and its role in migraine, including the basic structure and function; structural, functional, and biochemical neuroimaging; migraine-related genes; and theories related to cortex in migraine pathophysiology. We propose that long-term plasticity of synaptic transmission in the cortex encodes migraine.

Endothelin-1 axes in the framework of predictive, preventive and personalised (3P) medicine

Endothelin-1 (ET-1) is involved in the regulation of a myriad of processes highly relevant for physical and mental well-being; female and male health; in the modulation of senses, pain, stress reactions and drug sensitivity as well as healing processes, amongst others. Shifted ET-1 homeostasis may influence and predict the development and progression of suboptimal health conditions, metabolic impairments with cascading complications, ageing and related pathologies, cardiovascular diseases, neurodegenerative pathologies, aggressive malignancies, modulating, therefore, individual outcomes of both non-communicable and infectious diseases such as COVID-19. This article provides an in-depth analysis of the involvement of ET-1 and related regulatory pathways in physiological and pathophysiological processes and estimates its capacity as a predictor of ageing and related pathologies,a sensor of lifestyle quality and progression of suboptimal health conditions to diseases for their targeted preventionand as a potent target for cost-effective treatments tailored to the person.

Symptomatic migraine: A systematic review to establish a clinically important diagnostic entity

OBJECTIVE

To determine if a clinical presentation indistinguishable from migraine can occur due to an underlying condition or pathology, that is, "symptomatic migraine."

BACKGROUND

It is currently not clear whether migraine truly can be caused by an underlying condition or pathology. Characterization of the etiology and clinical features of possible symptomatic migraine is of significant clinical importance and further may help elucidate the pathophysiology of migraine.

METHODS

We devised operational diagnostic criteria for "symptomatic migraine" and "possible symptomatic migraine" requiring strong evidence for a causal relation between underlying cause and migraine symptoms adhering strictly to diagnostic criteria. PubMed was searched for case reports of symptomatic migraine from inception to March 2020. Only articles published in English or German were included. No restrictions were placed on study design. Relevant references in the articles were also included. Papers were systematically reviewed by two independent reviewers for detailed clinical features of migraine as well as the proposed underlying conditions and the effects of treatment of these conditions.

RESULTS

Our search retrieved 1726 items. After screening, 109 papers comprising 504 cases were reviewed in detail. Eleven patients with migraine with aura (MWA) fulfilled our working criteria for symptomatic migraine, and 39 patients fulfilled our criteria for possible symptomatic migraine. The most common etiologies of symptomatic migraine were arteriovenous malformations, carotid stenosis, dissection or aneurysm, brain infarctions, meningioma, and various intra-axial tumors.

CONCLUSIONS

Symptomatic MWA, indistinguishable from idiopathic MWA, may occur due to cortical lesions or microembolization. We found no clear evidence supporting the existence of symptomatic migraine without aura although we did identify possible cases. Our findings are limited by the available literature, and we suggest that prospective studies are needed.

Vagus nerve stimulation inhibits cortical spreading depression exclusively through central mechanisms

Experimental and clinical data strongly support vagus nerve stimulation (VNS) as a novel treatment in migraine. Vagus nerve stimulation acutely suppresses cortical spreading depression (CSD) susceptibility, an experimental model that has been used to screen for migraine therapies. However, mechanisms underlying VNS efficacy on CSD are unknown. Here, we interrogated the central and peripheral mechanisms using VNS delivered either invasively (iVNS) or noninvasively (nVNS) in male Sprague-Dawley rats. Cortical spreading depression susceptibility was evaluated 40 minutes after the stimulation. iVNS elevated the electrical CSD threshold more than 2-fold and decreased KCl-induced CSD frequency by 22% when delivered to intact vagus nerve. Distal vagotomy did not alter iVNS efficacy (2-fold higher threshold and 19% lower frequency in iVNS vs sham). By contrast, proximal vagotomy completely abolished iVNS effect on CSD. Pharmacological blockade of nucleus tractus solitarius, the main relay for vagal afferents, by lidocaine or glutamate receptor antagonist CNQX also prevented CSD suppression by nVNS. Supporting a role for both norepinephrine and serotonin, CSD suppression by nVNS was inhibited by more than 50% after abrogating norepinephrinergic or serotonergic neurotransmission alone using specific neurotoxins; abrogating both completely blocked the nVNS effect. Our results suggest that VNS inhibits CSD through central afferents relaying in nucleus tractus solitarius and projecting to subcortical neuromodulatory centers providing serotonergic and norepinephrinergic innervation to the cortex.

Vagus nerve stimulation in brain diseases: Therapeutic applications and biological mechanisms

Brain diseases, including neurodegenerative, cerebrovascular and neuropsychiatric diseases, have posed a deleterious threat to human health and brought a great burden to society and the healthcare system. With the development of medical technology, vagus nerve stimulation (VNS) has been approved by the Food and Drug Administration (FDA) as an alternative treatment for refractory epilepsy, refractory depression, cluster headaches, and migraines. Furthermore, current evidence showed promising results towards the treatment of more brain diseases, such as Parkinson's disease (PD), autistic spectrum disorder (ASD), traumatic brain injury (TBI), and stroke. Nonetheless, the biological mechanisms underlying the beneficial effects of VNS in brain diseases remain only partially elucidated. This review aims to delve into the relevant preclinical and clinical studies and update the progress of VNS applications and its potential mechanisms underlying the biological effects in brain diseases.

Clinical Features of Cluster Headache: A Hospital-Based Study in Taiwan

Most previous studies on cluster headache (CH) focus on Western populations. This study aimed to investigate the clinical characteristics of CH in a neurology outpatient population in Taiwan. A cross-sectional survey was conducted from July 2015 to June 2019 in a medical college affiliated with a tertiary care hospital (Tri-Service General Hospital) in Taiwan. All consecutive patients reporting headache as their chief complaint were asked to participate in a face-to-face interview with a qualified headache specialist and to complete a detailed self-administered questionnaire. The diagnosis of CH was made according to the Third edition of the International Classification of Headache Disorders. The subjects comprised 80 consecutive new CH patients (13 women and 67 men; ratio, 1:5). The mean age at presentation was 36.0 ± 10.8 years (range, 16-64 years), mean age at onset was 27.2 ± 12.1 years (range, 5-65 years), and mean time lag before diagnosis was 9.3 ± 10.5 years (range, 0-46.4 years). Of the total CH patients, 25.3% reported feelings of restlessness during headache episodes. A seasonal predilection was reported by 18% of the CH patients. The use of tobacco was the most common (44/80 patients). Chronic CH was only observed in 5% of the patients and only one patient (1.3%) reported both a positive family history for CH and aura. Features of CH in Taiwanese patients differed from that of Caucasian patients; a lower prevalence of chronic CH, positive family history of CH, and occurrence of aura may be less common in the former than in the latter.

Characterization of optogenetically-induced cortical spreading depression in awake mice using graphene micro-transistor arrays

Objective.The development of experimental methodology utilizing graphene micro-transistor arrays to facilitate and advance translational research into cortical spreading depression (CSD) in the awake brain.Approach.CSDs were reliably induced in awake nontransgenic mice using optogenetic methods. High-fidelity DC-coupled electrophysiological mapping of propagating CSDs was obtained using flexible arrays of graphene soultion-gated field-effect transistors (gSGFETs).Main results.Viral vectors targetted channelrhopsin expression in neurons of the motor cortex resulting in a transduction volume ⩾1 mm³. 5-10 s of continous blue light stimulation induced CSD that propagated across the cortex at a velocity of 3.0 ± 0.1 mm min^-1. Graphene micro-transistor arrays enabled high-density mapping of infraslow activity correlated with neuronal activity suppression across multiple frequency bands during both CSD initiation and propagation. Localized differences in the CSD waveform could be detected and categorized into distinct clusters demonstrating the spatial resolution advantages of DC-coupled recordings. We exploited the reliable and repeatable induction of CSDs using this preparation to perform proof-of-principle pharmacological interrogation studies using NMDA antagonists. MK801 (3 mg kg^-1) suppressed CSD induction and propagation, an effect mirrored, albeit transiently, by ketamine (15 mg kg^-1), thus demonstrating this models' applicability as a preclinical drug screening platform. Finally, we report that CSDs could be detected through the skull using graphene micro-transistors, highlighting additional advantages and future applications of this technology.Significance.CSD is thought to contribute to the pathophysiology of several neurological diseases. CSD research will benefit from technological advances that permit high density electrophysiological mapping of the CSD waveform and propagation across the cortex. We report anin vivoassay that permits minimally invasive optogenetic induction, combined with multichannel DC-coupled recordings enabled by gSGFETs in the awake brain. Adoption of this technological approach could facilitate and transform preclinical investigations of CSD in disease relevant models.

Opening of ATP sensitive potassium channels causes migraine attacks with aura

Migraine afflicts more than one billion individuals worldwide and is a leading cause of years lived with disability. In about a third of individuals with migraine aura occur in relation to migraine headache. The common pathophysiological mechanisms underlying migraine headache and migraine aura are yet to be identified. Based on recent data, we hypothesized that levcromakalim, an ATP-sensitive potassium channel opener, would trigger migraine attacks with aura in migraine with aura patients.

Retinal nerve fiber layer and ganglion cell layer changes using optical coherence tomography in patients with chronic migraine: a case-control study

Background

Migraine is a prevalent, chronic, and multifactorial neurovascular disease.

Objectives

Our work aimed to investigate if the retinal nerve fiber layer (RNFL) and ganglion cell layer (GCL) thickness are affected in patients with chronic migraine to improve the understanding of the etiology and pathophysiology of migraine.

Subjects and methods

A case-control study conducted on 30 patients with chronic migraine and 30 aged and sex-matched healthy controls. Subjects underwent full neurological and ophthalmological history, ophthalmological examination, and measuring RNFL and GCL thickness using the spectral domain-optical coherence tomography (SD-OCT).

Results

RNFL thinning (average, superior, inferior, nasal, and temporal) was significantly more in patients with chronic migraine than healthy control (P = 0.001, 0.022, 0.045, 0.034, and 0.001, respectively). No statistically significant difference was found between chronic migraine patients and healthy controls regarding GCL thickness (average, superior, and inferior) (P value ˃ 0.05).

The average RNFL thickness was significantly thinner in migraine with aura (MwA) than migraine without aura (MwoA) (P = 0.006). The average GCL thickness was thinner in MwA than MwoA (P = 0.039). No statistically significant difference was found between the eyes on the side of the headache and the eyes of the contralateral side regarding RNFL and GCL thickness (P value ˃ 0.05). Age at onset, disease duration, headache frequency, and headache intensity showed an insignificant correlation with OCT parameters.

Conclusion

Retinal changes could be an association with chronic migraine that may be used as a biomarker.

Optogenetic Spreading Depression Elicits Trigeminal Pain and Anxiety Behavior

OBJECTIVE

Cortical spreading depression (SD) is an intense depolarization underlying migraine aura. Despite the weight of evidence linking SD to the pain phase of migraine, controversy remains over a causal role of SD in cephalgia because of the invasive nature of previous SD induction methods. To overcome this problem, we used a novel minimally invasive optogenetic SD induction method and examined the effect of SD on behavior.

METHODS

Optogenetic SD was induced as a single event or repeatedly every other day for 2 weeks. End points, including periorbital and hindpaw mechanical allodynia, mouse grimace, anxiety, and working memory, were examined in male and female mice.

RESULTS

A single SD produced bilateral periorbital mechanical allodynia that developed within 1 hour and resolved within 2 days. Sumatriptan prevented periorbital allodynia when administered immediately after SD. Repeated SDs also produced bilateral periorbital allodynia that lasted 4 days and resolved within 2 weeks after the last SD. In contrast, the hindpaw withdrawal thresholds did not change after repeated SDs suggesting that SD-induced allodynia was limited to the trigeminal region. Moreover, repeated SDs increased mouse grimace scores 2 days after the last SD, whereas a single SD did not. Repeated SDs also increased thigmotaxis scores as a measure of anxiety. In contrast, neither single nor repeated SDs affected visuospatial working memory. We did not detect sexual dimorphism in any end point.

INTERPRETATION

Altogether, these data show a clinically congruent causal relationship among SD, trigeminal pain, and anxiety behavior, possibly reflecting SD modulation of hypothalamic, thalamic, and limbic mechanisms. ANN NEUROL 2021;89:99-110.

Intravascular Endothelin-1 does not trigger or increase susceptibility to Spreading Depolarizations

Objectives

Spreading depolarizations (SD) likely manifest as aura in migraineurs. Triggers are unknown although vascular events have been implicated. Direct carotid puncture has been reported to trigger migraine with aura. The potent vasoconstrictor endothelin-1 (ET-1), which can be released from the endothelium under pathological conditions, may play a role. Here, we tested whether intracarotid ET-1 infusion triggers SD and whether systemic ET-1 infusion increases the susceptibility to SD.

Methods

Carotid infusions were performed in mice (C57BL/6, male) through a catheter placed at the carotid bifurcation via the external carotid artery. Intracarotid ET-1 (1.25 nmol/ml) was infused at various rates (2–16 μl/min) with or without heparin in the catheter and compared with vehicle infusion (PBS with 0.01% acetic acid) or sham-operated mice (n = 5). Systemic infusions ET-1 (1 nmol/kg, n = 7) or vehicle (n = 7) infusions were performed in rats (Sprague-Dawley, male) via the tail vein. Electrical SD threshold and KCl-induced SD frequency were measured after the infusion.

Results

Intracarotid infusion of saline (n = 19), vehicle (n = 7) or ET-1 (n = 12) all triggered SDs at various proportions (21%, 14% and 50%, respectively). These were often associated with severe hypoperfusion prior to SD onset. Heparinizing the infusion catheter completely prevented SD occurrence during the infusions (n = 8), implicating microembolization from carotid thrombi as the trigger. Sham-operated mice never developed SD. Systemic infusion of ET-1 did not affect the electrical SD threshold or KCl-induced SD frequency.

Conclusion

Intravascular ET-1 does not trigger or increase susceptibility to SD. Microembolization was the likely trigger for migraine auras in patients during carotid puncture.

Retinal nerve fiber layer changes in migraine: A protocol for systematic review and meta-analysis

BACKGROUND

Migraine is a common neurological disease, which seriously affects the quality of life and daily activities of patients. Although migraine is a transient phenomenon of cerebral vasoconstriction, it is well documented that recurrent attacks of migraine may lead to abnormalities in retinal structure. Optical coherence tomography (OCT) is a sensitive method to detect subtle damage in retinal nerve fiber layer (RNFL). There have been many studies investigating the difference in RNFL thickness with optical coherence tomography (OCT) between migraine patients and healthy controls. However, the results were not consistent. Our purpose is to perform a meta-analysis to investigate RNFL alterations in migraine.

METHODS

We will search PubMed, Embase, Web of science for studies assessing the differences in RNFL measured by OCT between patients with migraine and healthy controls. Case-control studies published in English will be included. Two reviewers will independently screen eligible articles, extract data, and assess quality. This meta-analysis will synthesize selected research data and compare the difference in RNFL thickness between patients with migraine and healthy controls. We will use Stata 15 in this meta-analysis. I statistics will be used to assess heterogeneity. If I ≤ 50%, the data are synthesized will use a fixed effect model. Otherwise, a random effect model will be performed. Publication bias will be determined by the Egger test. The methodological quality of all included studies will be evaluated by the Newcastle-Ottawa Scale (NOS). We will perform subgroup analysis, sensitivity analysis, and meta-regression analysis to test the robustness of the results.

RESULTS

We will obtain quantitative results regarding the difference in RNFL thickness between migraine patients and healthy controls. The results will be published in a peer-reviewed journal.

CONCLUSIONS

The results of this study provide a high-quality synthesis of existing evidence and provide a basis for assessing the effect of migraine on the thickness of RNFL.

REGISTRATION NUMBER

INPLASY 202060033.

Comparison of the Prevalence of Infantile Colic Between Pediatric Migraine and Other Types of Pediatric Headache

BACKGROUND/OBJECTIVE

The International Headache Society lists infantile colic under "episodic syndromes that may be associated with migraine" in the ICHD3-beta version of its classification of headache disorders. The aim of this study was to examine whether this association is specific to migraine or applies to all pediatric headache types.

METHODS

A cross-sectional historical study was conducted including 219 patients aged 3-18 years who presented to a tertiary pediatric headache clinic in 2016-2017. Parents were asked a series of questions to determine if their child had had infantile colic as defined in the ICHD3-beta version. The prevalence of a positive history of colic was compared between children diagnosed with migraine or other primary headache types.

RESULTS

There were 132 girls (60.2%) and 87 boys (39.8%) of mean age 12.8 ± 3.48 years at presentation. Migraine headache was diagnosed in 170 patients (77.6%) and other types primary of headache (9 in total) in 49 patients (22.3%). Fifty-one patients had a history of infantile colic. They included 45 patients in the migraine group (26.5%) and 5 in the comparison groups (10.2%); the difference in the rate of colic was statistically significant (P = .0196; OR 3.17, 95% CI 0.1.17-6.17). There was no association of specific migraine parameters or symptoms with infantile colic.

CONCLUSION

There appears to be an association of infantile colic with pediatric migraine but not with other types of pediatric headache. These findings reinforce the theory that infantile colic has common pathogenic roots with migraine.

Non-invasive vagus nerve stimulation for primary headache: A clinical update

Background

Non-invasive vagus nerve stimulation (nVNS) is a proven treatment for cluster headache and migraine. Several possible mechanisms of action by which nVNS mitigates headache have been identified.

Methods

We conducted a narrative review of recent scientific and clinical research into nVNS for headache, including findings from mechanistic studies and their possible relationships to the clinical effects of nVNS.

Results

Findings from animal and human studies have provided possible mechanistic explanations for nVNS efficacy in headache involving four core areas: Autonomic nervous system functions; cortical spreading depression inhibition; neurotransmitter regulation; and nociceptive modulation. We discuss how overlap and interplay among these areas may underlie the utility of nVNS in the context of clinical evidence supporting its safety and efficacy as acute and preventive therapy for both cluster headache and migraine. Possible future nVNS applications are also discussed.

Conclusion

Significant progress over the past several years has yielded valuable mechanistic and clinical evidence that, combined with the excellent safety and tolerability profile of nVNS, suggests that it should be considered a first-line treatment for both acute and preventive treatment of cluster headache, an effective option for acute treatment of migraine, and a highly relevant, practical option for migraine prevention.

Characteristics of cortical spreading depression and c-Fos expression in transgenic mice having a mutation associated with familial hemiplegic migraine 2

BACKGROUND

Cortical spreading depression is thought to be the underlying mechanism of migraine aura. In 2006, three relatives having the point mutation E700K in ATP1A2 exon 15 were diagnosed with familial hemiplegic migraine 2 characterized by complicated forms of aura. Here, we generated a transgenic mouse model having the human E700K mutation in the Atp1a2 orthologous gene.

OBJECTIVE

To investigate the characteristics of cortical spreading depression in a mouse model with E700K mutation in the Atp1a2.

METHODS

Cortical spreading depression was induced by applying stepwise increases of KCl concentration or electrical stimulation intensity to C57BL/6J-Tg(Atp1a2*E700K)9151Kwk mice (Tg, both sexes) and corresponding wild-type animals. Under urethane anesthesia, the responsiveness and threshold to cortical spreading depression were examined and the distribution of c-Fos expression, a neuronal activity marker, was immunohistochemically determined.

RESULTS

Overall, Tg mice showed significantly faster propagation velocity (p < 0.01) and longer full-width-at-half-maximum (p < 0.01) than wild-type animals, representing a slower recovery from direct current potential deflection. The cortical spreading depression threshold tended to be lower in Tg, especially in females. c-Fos-positive cells were significantly enhanced in the ipsilateral somatosensory cortex, piriform cortex, amygdala and striatum (each p < 0.05 vs. contralateral side). Numbers of c-Fos positive cells were significantly higher in the ipsilateral amygdala of Tg, as compared with wild-type animals (p < 0.01).

CONCLUSION

The effect of cortical spreading depression may be greater in E700K transgenic mice than that in wild-type animals, while the threshold for cortical spreading depression shows little change. Higher c-Fos expression in the amygdala may indicate alterations of the limbic system in Tg, suggesting an enhanced linkage between cortical spreading depression and amygdala connectivity in familial hemiplegic migraine 2 patients.

Topographic changes measured by the swept source optical coherence tomography in retinal nerve fiber layer, optic nerve head and macula in children with migraine

As a vascular-inflammatory disease, migraine affects the brain and some other organs, such as the eye. The aim of this study was to measure and compare the peripapillary retinal nerve fiber layer (RNFL) thickness, macular ganglion cell layer thickness and optic nerve head parameters to detect structural damage in children with migraine using swept-source optical coherence tomography. Twenty-four children with migraine in the painless period and 26 controls were included in the study. The vast majority of the groups consisted of females (75% for patients and 77% for controls). Certain RNFL quadrants and optic disc parameters revealed significant differences between the patients and controls. In the right and left eyes of children with migraine, nasal quadrant RNFL was significantly thicker than that in healthy subjects (88.82 ± 11.03 vs 77.80 ± 13.77, P = 0.004 for right eyes and 87.71 ± 11.79 vs 77.80 ± 13.77, P = 0.01 for left eyes). Temporal quadrant RNFL in the left eyes was thinner (78.67 ± 9.57 vs 84.44 ± 9.68, P = 0.04). Disc area in the left eyes of the patients was greater (2.29 ± 0.46 vs 1.94 ± 0.28, P = 0.003). There were significant expansions in cup volumes in favor of the patients for right and left eyes (0.15 ± .0.19 vs 0.05 ± 0.05, P = 0.03 and 0.17 ± 0.14 vs 0.05 ± 0.05, P = 0.001, respectively). The only significant difference between the left and right eyes of the migraineurs was the RNFL thickness in the superior quadrant. Ganglion cell layer thickness did not differ between the right eyes, left eyes and controls. In conclusion, children with migraine showed significant variations in specific RNFL and optic disc parameters compared to control subjects.

Functional NHE1 expression is critical to blood brain barrier integrity and sumatriptan blood to brain uptake

Disruption of blood-brain barrier integrity and dramatic failure of brain ion homeostasis including fluctuations of pH occurs during cortical spreading depression (CSD) events associated with several neurological disorders, including migraine with aura, traumatic brain injury and stroke. NHE1 is the primary regulator of pH in the central nervous system. The goal of the current study was to investigate the role of sodium-hydrogen exchanger type 1 (NHE1) in blood brain barrier (BBB) integrity during CSD events and the contributions of this antiporter on xenobiotic uptake. Using immortalized cell lines, pharmacologic inhibition and genetic knockdown of NHE1 mitigated the paracellular uptake of radiolabeled sucrose implicating functional NHE1 in BBB maintenance. In contrast, loss of functional NHE1 in endothelial cells facilitated uptake of the anti-migraine therapeutic, sumatriptan. In female rats, cortical KCl but not aCSF selectively reduced total expression of NHE1 in cortex and PAG but increased expression in trigeminal ganglia; no changes were seen in trigeminal nucleus caudalis. Thus, in vitro observations may have a significance in vivo to increase brain sumatriptan levels. Pharmacological inhibition of NHE1 prior to cortical manipulations enhanced the efficacy of sumatriptan at early time-points but induced facial sensitivity alone. Overall, our results suggest that dysregulation of NHE1 contributes to breaches in BBB integrity, drug penetrance, and the behavioral sensitivity to the antimigraine agent, sumatriptan.

Non-invasively triggered spreading depolarizations induce a rapid pro-inflammatory response in cerebral cortex

Cortical spreading depolarization (CSD) induces pro-inflammatory gene expression in brain tissue. However, previous studies assessing the relationship between CSD and inflammation have used invasive methods that directly trigger inflammation. To eliminate the injury confounder, we induced CSDs non-invasively through intact skull using optogenetics in Thy1-channelrhodopsin-2 transgenic mice. We corroborated our findings by minimally invasive KCl-induced CSDs through thinned skull. Six CSDs induced over 1 h dramatically increased cortical interleukin-1β (IL-1β), chemokine (C-C motif) ligand 2 (CCL2), and tumor necrosis factor-α (TNF-α) mRNA expression peaking around 1, 2 and 4 h, respectively. Interleukin-6 (IL-6) and intercellular adhesion molecule-1 (ICAM-1) were only modestly elevated. A single CSD also increased IL-1β, CCL2, and TNF-α, and revealed an ultra-early IL-1β response within 10 min. The response was blunted in IL-1 receptor-1 knockout mice, implicating IL-1β as an upstream mediator, and suppressed by dexamethasone, but not ibuprofen. CSD did not alter systemic inflammatory indices. In summary, this is the first report of pro-inflammatory gene expression after non-invasively induced CSDs. Altogether, our data provide novel insights into the role of CSD-induced neuroinflammation in migraine headache pathogenesis and have implications for the inflammatory processes in acute brain injury where numerous CSDs occur for days.

Intravenous Endothelin-1 Infusion Does Not Induce Aura or Headache in Migraine Patients With Aura

OBJECTIVE

To investigate whether intravenously infused provokes migraine aura and migraine headache in migraine patients with aura.

BACKGROUND

Migraine with aura has been associated with endothelial dysfunction and increased stroke risk. The initiating mechanism of migraine aura symptoms is not known. Experimental provocation of migraine headache using vasoactive peptides has provided tremendous advances in the understanding of migraine pathophysiology but substances that can induce migraine aura have not been identified. Endothelin-1 (ET-1), an endogenous, potent vasoconstrictor peptide released from the vascular endothelium, has been proposed to trigger migraine aura. This hypothesis is based on reports of increased plasma ET-1 levels early during the migraine attacks and the observation that ET-1 applied to the cortical surface potently induces the cortical spreading depolarization, the underlying electrophysiological phenomenon of migraine aura, in animals. Further, endothelial damage due to, for example, carotid puncture and vascular pathology is known to trigger aura episodes.

METHODS

We investigated whether intravascular ET-1 would provoke migraine aura in patients. Using a two-way crossover, randomized, placebo-controlled, double-blind design, we infused high-dose (8 ng/kg/minutes for 20 minutes) intravenous ET-1 in patients with migraine with typical aura. The primary end-point was the difference in incidence of migraine aura between ET-1 and placebo. Experiments were carried out at a public tertiary headache center (Danish Headache Center, Rigshospitalet Glostrup, Denmark).

RESULTS

Fourteen patients received intravenous ET-1. No patients reported migraine aura symptoms or migraine headache during or up to 24 hours following the ET-1 infusion. Four patients reported mild to moderate headache only on the ET-1 day, 3 patients reported moderate headache on the placebo day, and 1 patient reported mild headache on both days. No serious adverse events occurred during or after infusion.

CONCLUSIONS

Provocation of migraine aura by procedures or conditions involving vascular irritation is unlikely to be mediated by ET-1.