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.

Risk of Stroke and Myocardial Infarction Among Initiators of Triptans

Importance

Triptans are contraindicated in patients with ischemic heart disease or previous myocardial infarction, and caution is advised when prescribing these drugs to patients with vascular risk factors. However, controlled observational studies have either shown no association or an apparent lower risk, possibly owing to a channeling of triptans to individuals at low risk of cardiovascular outcomes, and it remains unclear whether avoiding triptan treatment for these patients is meaningful.

Objective

To establish whether an association between triptans and ischemic events could be demonstrated using a self-controlled design because this type of design is robust to the previously mentioned type of confounding.

Design, Setting, and Participants

All people in nationwide Danish registries who were initiating triptans and all the ischemic events that they experienced were identified. A case-crossover design was used to estimate odds ratios (OR) for associations between first-ever triptan use and ischemic outcomes, comparing triptan exposure in the 2-week period up to the event with four 2-week reference periods. Data were obtained for the period January 1995 to August 2022. Included from the population of Denmark were individuals redeeming a prescription for any triptan and experiencing at least 1 of 3 predefined ischemic outcomes. No one was excluded.

Exposure

Initiation of any triptan.

Main Outcomes and Measures

Acute myocardial infarction, ischemic stroke, or nonspecified stroke.

Results

Identified were a total of 429 612 individuals (median [IQR] age, 38 [28-48] years; 325 687 female [75.8%]) who redeemed a first prescription for a triptan in the study period. Of these patients, 11 (0.003%) had a myocardial infarction with the first triptan prescription in either a focal or referent window (odds ratio [OR], 3.3; 95% CI, 1.0-10.9), 18 (0.004%) had ischemic stroke (OR, 3.2; 95% CI, 1.3-8.1), and 35 (0.008%) had ischemic/nonspecified stroke (OR, 3.0; 95% CI, 1.5-5.9). Case patients had a median age of approximately 60 years and had a high-risk cardiovascular profile.

Conclusions and Relevance

Results of this case-crossover study suggest that triptan initiation was associated with higher risk of ischemic stroke and myocardial infarction. For the individual patient with low background cardiovascular risk, the risk of an ischemic event after triptan initiation was very low.

Visual migraine aura iconography: A multicentre, cross-sectional study of individuals with migraine with aura

INTRODUCTION

Visual disturbances are the most common symptoms of migraine aura. These symptoms can be described systematically by subdividing them into elementary visual symptoms. Since visual symptoms of migraine aura are not easy to describe verbally, we developed a collection of images illustrating previously reported elementary visual symptoms.

OBJECTIVES

To test a standardised visual migraine aura iconography in a large population of migraine with aura patients and to improve it based on the participants' feedback.

METHODS

We created a set of images representing 25 elementary visual symptoms and a web-based survey where participants could report whether they recognised these images as part of their visual aura. Elementary visual symptoms could also be recognised via a corresponding text description or described in a free text by participants. Individuals with migraine aura recruited from four tertiary headache centres (in Switzerland, Denmark, Norway and Italy) were invited to complete the survey.

RESULTS

Two hundred and fifteen participants completed the study (78.9% women, median age 36). They recognised a total of 1645 elementary visual symptoms from our predefined list. Of those, 1291 (78.4%) where recognised via standardised iconography images. A new type of elementary visual symptom was reported by one participant.

CONCLUSION

Most elementary visual symptoms experienced by participants were recognised via the standardised iconography. This tool can be useful for clinical as well as research purposes.

Lack of reproducibility of resting-state functional MRI findings in migraine with aura

BACKGROUND

Several studies have applied resting-state functional MRI to examine whether functional brain connectivity is altered in migraine with aura patients. These studies had multiple limitations, including small sample sizes, and reported conflicting results. Here, we performed a large, cross-sectional brain imaging study to reproduce previous findings.

METHODS

We recruited women aged 30-60 years from the nationwide Danish Twin Registry. Resting-state functional MRI of women with migraine with aura, their co-twins, and unrelated migraine-free twins was performed at a single centre. We carried out an extensive series of brain connectivity data analyses. Patients were compared to migraine-free controls and to co-twins.

RESULTS

Comparisons were based on data from 160 patients, 30 co-twins, and 136 controls. Patients were similar to controls with regard to age, and several lifestyle characteristics. We replicated clear effects of age on resting-state networks. In contrast, we failed to detect any differences, and to replicate previously reported differences, in functional connectivity between migraine patients with aura and non-migraine controls or their co-twins in any of the analyses.

CONCLUSION

Given the large sample size and the unbiased population-based design of our study, we conclude that women with migraine with aura have normal resting-state brain connectivity outside of migraine attacks.

Investigations of the subarachnoid space as a potential link between aura and headache in migraine: A case-control MRI study

BACKGROUND

The connection between migraine aura and headache is poorly understood. Some patients experience migraine aura without headache, and patients with migraine aura with headache commonly experience milder headaches with age. The distance between the cerebral cortex and the overlying dura mater has been hypothesized to influence development of headache following aura. We tested this hypothesis by comparing approximated distances between visual cortical areas and overlying dura mater between female patients with migraine aura without headache and female patients with migraine aura with headache.

METHODS

Twelve cases with migraine aura without headache and 45 age-matched controls with migraine aura with headache underwent 3.0 T MRI. We calculated average distances between the occipital lobes, between the calcarine sulci, and between the skull and visual areas V1, V2 and V3a. We also measured volumes of corticospinal fluid between the occipital lobes, between the calcarine sulci, and overlying visual areas V2 and V3a. We investigated the relationship between headache status, distances and corticospinal fluid volumes using conditional logistic regression.

RESULTS

Distances between the occipital lobes, calcarine sulci and between the skull and V1, V2 and V3a did not differ between patients with migraine aura with headache and patients with migraine aura without headache. We found no differences in corticospinal fluid volumes between groups.

CONCLUSION

We found no indication for a connection between visual migraine aura and headache based on cortico-cortical, cortex-to-skull distances, or corticospinal fluid volumes overlying visual cortical areas. Longitudinal studies with imaging sequences optimized for measuring the cortico-dural distance and a larger sample of patients are needed to further investigate the hypothesis.

Migraine attacks are of peripheral origin: the debate goes on

BACKGROUND

Despite the pervasiveness of migraine, the underlying pathophysiological mechanisms initiating migraine attacks are far from well understood and are matter of scientific debate.

OBJECTIVE

In this narrative review, we discuss key evidence for that suggest a peripheral origin or central origin and provide directions for future studies that may provide further clarification.

DISCUSSION

Migraine pathogenesis is considered to involve the trigeminovascular system, a term that encompasses the trigeminal nerve and its axonal projections to the intracranial blood vessels. Beyond any doubt both peripheral and central mechanisms are involved in migraine pathogenesis, but an unresolved question is the how the initial activation occurs in a migraine attack. Evidence favoring a peripheral origin of migraine attacks, i.e., initial events occur outside of the blood-brain barrier, include the importance of sensitization of perivascular sensory afferents early on in a migraine attack. Evidence favoring a central origin include the occurrence of prodromal symptoms, migraine aura, and activation of structures within the central nervous system early in and during a migraine attack.

CONCLUSIONS

Both peripheral and central mechanisms are likely involved in a migraine attack, e.g., peripheral nociceptive input is necessary for pain transmission and cortical activity is necessary for pain perception. Yet, the debate of whether migraine attacks are initiated a peripheral or central site remains unresolved. The increased focus on prodromal symptoms and on the development of a human model of migraine aura will possibly provide key arguments needed to answer this question in the near future. Until then, we cannot draw firm conclusions and the debate goes on.

VIDEO LINK

Video recording of the debate held at the 1st International Conference on Advances in Migraine Sciences (ICAMS 2022, Copenhagen, Denmark) is available at: https://www.youtube.com/watch?v=NC0nlcKohz0 .

Migraine aura-like episodes following sclerotherapy for varicose veins of the lower extremities-A systematic review

OBJECTIVE

This systematic review provides a summary and evaluation of cases of migraine aura-like episodes elicited by sclerotherapy of veins of the lower extremities and discusses possible underlying mechanisms.

BACKGROUND

Sclerotherapy is a commonly used treatment for varicose veins. Symptoms resembling migraine aura have been reported during and following sclerotherapy of the lower extremities, suggesting that sclerotherapy may elicit migraine aura.

METHODS

We searched PubMed for articles reporting neurological complications that were transient and fully reversible following sclerotherapy treatment for varicose veins in the lower limbs. There were no restrictions regarding article language or publication date. Only original studies and case reports were included. Two authors independently reviewed included articles in detail. Data were extracted from each article, including details on symptoms, previous migraine history, sclerotherapy method, and the presence of a right-to-left cardiac shunt in patients. We evaluated whether episodes fulfilled modified International Classification of Headache Disorders, 3rd edition, criteria for 1.2 Migraine with aura or 1.5.2 Probable migraine with aura.

RESULTS

The search yielded 777 articles, 28 of which were included. Twenty-six articles reported 119 episodes of transient neurological symptoms in 34,500 sclerotherapy sessions. Two additional articles reported six episodes of transient neurological symptoms with no specification of the number of sessions. Of the 125 episodes, 119 involved transient visual disturbances, and eight met the modified criteria for Probable migraine with aura. In most episodes (98%), clinical information was insufficient to determine if the criteria were fulfilled.

CONCLUSIONS

Symptoms that are clinically indistinguishable from migraine with aura attacks may occur following sclerotherapy, although this likely is rare. Microembolization through a right-to-left shunt triggering cortical spreading depolarization is a possible mechanism. Our findings are limited by infrequent specific assessments for neurological complications and a low level of detail in the description of symptoms in the available literature. Future prospective studies are needed to determine this phenomenon's incidence and underlying mechanisms.

Interictal pontine metabolism in migraine without aura patients: A 3 Tesla proton magnetic resonance spectroscopy study

In the pons, glutamatergic mechanisms are involved in regulating inhibitory descending pain modulation, serotoninergic neurotransmission as well as modulating the sensory transmission of the trigeminovascular system. Migraine involves altered pontine activation and structural changes, while biochemical, genetic and clinical evidence suggests that altered interictal pontine glutamate levels may be an important pathophysiological feature of migraine abetting to attack initiation. Migraine without aura patients were scanned outside attacks using a proton magnetic resonance spectroscopy protocol optimized for the pons at 3 Tesla. The measurements were performed on two separate days to increase accuracy and compared to similar repeated measurements in healthy controls. We found that interictal glutamate (i.e. Glx) levels in the pons of migraine patients (n = 33) were not different from healthy controls (n = 16) (p = 0.098), while total creatine levels were markedly increased in patients (9%, p = 0.009). There was no correlation of glutamate or total creatine levels to migraine frequency, days since the last attack, usual pain intensity of attacks or disease duration. In conclusion, migraine is not associated with altered interictal pontine glutamate levels. However, the novel finding of increased total creatine levels suggests that disequilibrium in the pontine energy metabolism could be an important feature of migraine pathophysiology.

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.

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.

Glutamate levels and perfusion in pons during migraine attacks: A 3T MRI study using proton spectroscopy and arterial spin labeling

Migraine is a complex disorder, involving peripheral and central brain structures, where mechanisms and site of attack initiation are an unresolved puzzle. While abnormal pontine neuronal activation during migraine attacks has been reported, exact implication of this finding is unknown. Evidence suggests an important role of glutamate in migraine, implying a possible association of pontine hyperactivity to increased glutamate levels. Migraine without aura patients were scanned during attacks after calcitonin gene-related peptide and sildenafil in a double-blind, randomized, double-dummy, cross-over design, on two separate study days, by proton magnetic resonance spectroscopy and pseudo-continuous arterial spin labeling at 3T. Headache characteristics were recorded until 24 h after drug administrations. Twenty-six patients were scanned during migraine, yielding a total of 41 attacks. Cerebral blood flow increased in dorsolateral pons, ipsilateral to pain side during attacks, compared to outside attacks (13.6%, p = 0.009). Glutamate levels in the same area remained unchanged during attacks (p = 0.873), while total creatine levels increased (3.5%, p = 0.041). In conclusion, dorsolateral pontine activation during migraine was not associated with higher glutamate levels. However, the concurrently increased total creatine levels may suggest an altered energy metabolism, which should be investigated in future studies to elucidate the role of pons in acute migraine.

Feasibility of Glutamate and GABA Detection in Pons and Thalamus at 3T and 7T by Proton Magnetic Resonance Spectroscopy

Glutamate detection in pons and thalamus using proton magnetic resonance spectroscopy (¹H-MRS) after an intervention is of interest for studying various brain disorders. However, ¹H-MRS in these brain regions is challenging and time-consuming, especially in longitudinal study designs. ¹H-MRS of more cortical structures at the ultrahigh magnetic field strength of 7T yields an improved spectral output, including separation of the glutamate signal from the glutamine signal, in a shorter and more feasible scan time, as compared to conventional clinical field strengths. For this purpose, we compared the feasibility of ¹H-MRS at 3T and 7T in pons and thalamus by applying a longitudinal study design of repeated measures on same day and three separate days at both field strength in five healthy participants. Total ¹H-MRS acquisition time was reduced by a factor 3.75 for pons and by a factor 3 for thalamus at 7T as compared to 3T. We found higher spectral signal-to-noise ratio (SNR) (p < 0.001), lower linewidth (p = 0.001) and lower Cramér–Rao lower bounds (CRLB) (p < 0.001) for the combined glutamate and glutamine signal (Glx) in thalamus at 7T as compared to 3T. In pons, CRLB of Glx and SNR were lower at 7T (p = 0.002 and p = 0.006), with no differences in linewidth compared to 3T. Mean within-subject variability of Glx concentration estimates was lower at 7T compared to 3T for both pons and thalamus. At 7T, it was possible to assess glutamate and γ-aminobutyric acid (GABA) simultaneously in pons and thalamus. In conclusion, ¹H-MRS at 7T resulted in improved spectral quality while allowing shorter scan times than at 3T as well as estimation of the pure glutamate signal in pons and thalamus. This opens up the opportunity for multimodal study designs and multiregional subcortical ¹H-MRS research. Glutamate and GABA measurement at 7T in pons and thalamus is advantageous for future investigations of excitatory–inhibitory mechanisms in brain disorders.

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.

Cerebrovascular effects of endothelin-1 investigated using high-resolution magnetic resonance imaging in healthy volunteers

Endothelin-1 (ET-1) is a highly potent vasoconstrictor peptide released from vascular endothelium. ET-1 plays a major role in cerebrovascular disorders and likely worsens the outcome of acute ischaemic stroke and aneurismal subarachnoid haemorrhage through vasoconstriction and cerebral blood flow (CBF) reduction. Disorders that increase the risk of stroke, including hypertension, diabetes mellitus, and acute myocardial infarction, are associated with increased plasma levels of ET-1. The in vivo human cerebrovascular effects of systemic ET-1 infusion have not previously been investigated. In a two-way crossover, randomized, double-blind design, we used advanced 3 tesla MRI methods to investigate the effects of high-dose intravenous ET-1 on intra- and extracranial artery circumferences, global and regional CBF, and cerebral metabolic rate of oxygen (CMRO₂) in 14 healthy volunteers. Following ET-1 infusion, we observed a 14% increase of mean arterial blood pressure, a 5% decrease of middle cerebral artery (MCA) circumference, but no effects on extracerebral arteries and no effects on CBF or CMRO₂. Collectively, the findings indicate MCA constriction secondarily to blood pressure increase and not due to a direct vasoconstrictor effect of ET-1. We suggest that, as opposed to ET-1 in the subarachnoid space, intravascular ET-1 does not exert direct cerebrovascular effects in humans.

Migraine with aura in women is not associated with structural thalamic abnormalities

Migraine with aura is a highly prevalent disorder involving transient neurological disturbances associated with migraine headache. While the pathophysiology is incompletely understood, findings from clinical and basic science studies indicate a potential key role of the thalamus in the mechanisms underlying migraine with and without aura. Two recent, clinic-based MRI studies investigated the volumes of individual thalamic nuclei in migraine patients with and without aura using two different data analysis methods. Both studies found differences of thalamic nuclei volumes between patients and healthy controls, but the results of the studies were not consistent. Here, we investigated whether migraine with aura is associated with changes in thalamic volume by analysing MRI data obtained from a large, cross-sectional population-based study which specifically included women with migraine with aura (N = 156), unrelated migraine-free matched controls (N = 126), and migraine aura-free co-twins (N = 29) identified from the Danish Twin Registry. We used two advanced, validated analysis methods to assess the volume of the thalamus and its nuclei; the MAGeT Brain Algorithm and a recently developed FreeSurfer-based method based on a probabilistic atlas of the thalamic nuclei combining ex vivo MRI and histology. These approaches were very similar to the methods used in each of the two previous studies. Between-group comparisons were corrected for potential effects of age, educational level, BMI, smoking, alcohol, and hypertension using a linear mixed model. Further, we used linear mixed models and visual inspection of data to assess relations between migraine aura frequency and thalamic nuclei volumes in patients. In addition, we performed paired t-tests to compare volumes of twin pairs (N = 29) discordant for migraine with aura. None of our analyses showed any between-group differences in volume of the thalamus or of individual thalamic nuclei. Our results indicate that the pathophysiology of migraine with aura does not involve alteration of thalamic volume.

Association Between Sumatriptan Treatment During a Migraine Attack and Central 5-HT1B Receptor Binding

Importance

Triptans, the most efficient acute treatment for migraine attacks, are 5-HT1B/1D receptor agonists, but their precise mechanism of action is not completely understood. The extent to which triptans enter the central nervous system and bind to 5-HT1B receptors in the brain is unknown.

Objectives

To determine the occupancy of sumatriptan to central 5-HT1B receptors, and to investigate changes in brain serotonin levels during migraine attacks.

Design, Setting, and Participants

This study of 8 patients in Denmark used a within-participant design and was conducted from April 20, 2015, to December 5, 2016. Participants were otherwise healthy patients with untreated episodic migraine without aura, aged between 18 and 65 years, and recruited from the general community. Data analysis was performed from January 2017 to April 2018.

Interventions

All participants underwent positron emission tomographic scans after injection of [11C]AZ10419369, a specific 5-HT1B receptor radiotracer. All participants were scanned 3 times: (1) during an experimentally induced migraine attack, (2) after a subcutaneous injection of 6-mg subcutaneous sumatriptan, and (3) on a migraine attack-free day. Scans 1 and 2 were conducted on the same study day. Each scan lasted for 90 minutes.

Main Outcome and Measure

The primary outcome was the nondisplaceable binding potential of [11C]AZ10419369 across 7 brain regions involved in pain modulation. The binding potential reflects receptor density, and changes in binding potential reflects displacement of the radiotracer. The occupancy of sumatriptan was estimated from the 2 scans before and after sumatriptan administration.

Results

Eight patients with migraine were included in the study; of these participants, 7 (87%) were women. The mean (SD) age of participants on study day 1 was 29.5 (9.2) years and on study day 2 was 30.0 (8.9) years. Sumatriptan was associated with statistically significantly reduced 5-HT1B receptor binding across pain-modulating regions (mean [SD] binding potential, 1.20 [0.20] vs 1.02 [0.22]; P = .001), corresponding to a mean (SD) drug occupancy rate of 16.0% (5.3%). Furthermore, during migraine attacks, as compared with outside of attacks, 5-HT1B receptor binding was statistically significantly associated with reduced in pain-modulating regions (mean [SD] binding potential, 1.36 [0.22] vs 1.20 [0.20]; P = .02).

Conclusions and Relevance

Treatment with sumatriptan during migraine attacks appeared to be associated with a decrease in 5-HT1B receptor binding, a finding that is most likely associated with the binding of sumatriptan to central 5-HT1B receptors, but the contribution of ongoing cerebral serotonin release to the lower binding cannot be excluded; the migraine attack-associated decrease in binding could indicate that migraine attacks are associated with increases in endogenous serotonin.

The depiction of migraine visual aura on the internet

INTRODUCTION

The most common and multifaceted migraine aura symptoms are visual disturbances. Health information is one of the most popular topics on the internet but the quality and reliability of publicized information is unknown. The aim of this study was to analyze images of migraine aura on Google to determine the frequency of correct presentations of visual aura and distribution of visual aura phenotypes.

METHODS

Two authors screened the 100 highest indexed migraine aura related images on Google. The content of the images was categorized into elementary visual symptoms.

RESULTS

Forty out of 100 images were accurate representations of visual migraine aura. Such images included 31 different visual aura phenotypes. The majority had more than one elementary visual symptom (median 2, IQR 1-3), most commonly "bean-like" forms (45%), zigzag lines (40%), and foggy/blurred vision (33%).

DISCUSSION

Forty percent of images were accurate portrayals of visual migraine aura symptoms, but these presented limited phenotypes. The information derived from the internet photos may hinder the effective recognition of aura symptoms. Thus, there is a need to provide a more comprehensive representation of visual migraine aura symptoms on the internet.

Volume of the rectus capitis posterior minor muscle in migraine patients: a cross-sectional structural MRI study

Background

Neck pain in migraine patients is very prevalent between and during migraine attacks, but the underlying mechanism behind neck pain in migraine is unknown. The neck muscle rectus capitis posterior minor muscle (RCPmi) may be important since it is connected to the occipital dura mater. In this study, we examined the RCPmi volume in migraine patients and compared with controls.

Methods

We conducted a cross-sectional MRI study examining muscle volume in 40 episodic migraine patients and 40 controls in preexisting images from prior studies. Three-dimensional T1 weighted sequences were collected with a 3.0 T MRI Scanner. The volume of RCPmi was examined by manually tracing the muscle circumference with Horos medical image viewer. The observer was blinded to participant information. No information regarding neck pain status during or between migraine attacks were available.

Results

The mean RCPmi volume was 1.22cm³ in migraine patients and 1.17cm³ in controls (p = 0.549). We found no differences in RCPmi volume on the pain side vs. the non-pain side (p = 0.237) in patients with unilateral migraine. There were no association between the muscle volume and years with migraine, headache or migraine frequency, age or BMI.

Conclusions

We found no difference in RCPmi volume between migraine patients and controls, suggesting no structural RCPmi pathology in migraine.

Plasma Glucose Levels Increase During Spontaneous Attacks of Migraine With and Without Aura

OBJECTIVE

To investigate plasma glucose changes during the ictal state of migraine compared to the interictal state.

BACKGROUND

Previous studies suggest abnormal glucose metabolism in migraine patients during and outside of attacks. It is not known if plasma glucose levels change during spontaneous migraine attacks.

METHODS

Plasma glucose levels were measured during and outside of spontaneous migraine attacks with and without aura. Plasma glucose values were corrected for diurnal variation of plasma glucose by subtracting the difference between the moving average (intervals of 2 hours) and overall mean from the plasma glucose values.

RESULTS

This was a sub-study of a larger study conducted at Rigshospitalet Glostrup in the Capital Region of Denmark. Thirty-one patients (24 F, 7 M, 13 with aura, 18 without aura) were included in the study. Mean time from attack onset to blood sampling was 7.6 hours. Mean pain at the time of investigation was 6 on a 0-10 verbal rating scale. Plasma glucose was higher ictally compared to the interictal phase (interictal mean: 88.63 mg/dL, SD 11.70 mg/dL; ictal mean: 98.83 mg/dL, SD 13.16 mg/dL, difference 10.20 mg/dL, 95% CI = [4.30; 16.10]), P = .0014). The ictal increase was highest in patients investigated early during attacks and decreased linearly with time from onset of migraine (-1.57 mg/dL/hour from onset of attack, P = .020). The attack-related increase in blood glucose was not affected by pain intensity or presence of aura symptoms.

CONCLUSIONS

We demonstrated higher plasma glucose values during spontaneous migraine attacks, independent of the presence of aura symptoms and not related to pain intensity, peaking in the early phase of attacks. Additional studies are necessary to confirm our findings and explore the possible underlying mechanisms.

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.

Investigation of distinct molecular pathways in migraine induction using calcitonin gene-related peptide and sildenafil

Objective

Migraine displays clinical heterogeneity of attack features and attack triggers. The question is whether this heterogeneity is explained by distinct intracellular signaling pathways leading to attacks with distinct clinical features. One well-known migraine-inducing pathway is mediated by cyclic adenosine monophosphate and another by cyclic guanosine monophosphate. Calcitonin gene-related peptide triggers migraine via the cyclic adenosine monophosphate pathway and sildenafil via the cyclic guanosine monophosphate pathway. To date, no studies have examined whether migraine induction mediated via the cyclic adenosine monophosphate and cyclic guanosine monophosphate pathways yields similar attacks within the same patients.

Methods

Patients were subjected to migraine induction on two separate days using calcitonin gene-related peptide (1.5 µg/min for 20 minutes) and sildenafil (100 mg) in a double-blind, randomized, double-dummy, cross-over design. Data on headache intensity, characteristics and accompanying symptoms were collected until 24 hours after drug administration.

Results

Thirty-four patients were enrolled and 27 completed both study days. Seventeen patients developed migraine after both study drugs (63%; 95% CI: 42–81). Eight patients developed migraine on one day only (seven after sildenafil and one after calcitonin gene-related peptide). Two patients did not develop migraine on either day. Headache laterality, nausea, photophobia and phonophobia were similar between drugs in 77%, 65%, 100%, and 94%, respectively, of the 17 patients who developed attacks on both days.

Conclusion

A majority of patients developed migraine after both calcitonin gene-related peptide and sildenafil. This supports the hypothesis that the cyclic adenosine monophosphate and cyclic guanosine monophosphate intracellular signaling pathways in migraine induction converge in a common cellular determinator, which ultimately triggers the same attacks. Trial registration: ClinicalTrials.gov Identifier: NCT03143465.

Clinical features of visual migraine aura: a systematic review

Background

Migraine aura (MA) is a common and disabling neurological condition, characterized by transient visual, and less frequently sensory and dysphasic aura disturbances.

MA is associated with an increased risk of cardiovascular disorders and is often clinically difficult to distinguish from other serious neurological disorders such as transient ischemic attacks and epilepsy. Optimal clinical classification of MA symptoms is important for more accurate diagnosis and improved understanding of the pathophysiology of MA through clinical studies.

Main body

A systematic review of previous prospective and retrospective systematic recordings of visual aura symptoms (VASs) was performed to provide an overview of the different types of visual phenomena occurring during MA and their respective frequencies in patients. We found 11 retrospective studies and three prospective studies systematically describing VASs. The number of different types of VASs reported by patients in the studies ranged from two to 23. The most common were flashes of bright light, “foggy” vision, zigzag lines, scotoma, small bright dots and ‘like looking through heat waves or water’.

Conclusions

We created a comprehensive list of VAS types reported by migraine patients based on all currently available data from clinical studies, which can be used for testing and validation in future studies. We propose that, based on this work, an official list of VAS types should be developed, preferably within the context of the International Classification of Headache Disorders of the International Headache Society.

Brain functional connectivity in headache disorders: A narrative review of MRI investigations

Resting-state functional magnetic resonance imaging (rs-fMRI) is used to interrogate the functional connectivity and network organization amongst brain regions. Functional connectivity is determined by measuring the extent of synchronization in the spontaneous fluctuations of blood oxygenation level dependent (BOLD) signal. Here, we review current rs-fMRI studies in headache disorders including migraine, trigeminal autonomic cephalalgias, and medication overuse headache. We discuss (1) brain network alterations that are shared amongst the different headache disorders and (2) network abnormalities distinct to each headache disorder. In order to focus the section on migraine, the headache disorder that has been most extensively studied, we chose to include articles that interrogated functional connectivity: (i) during the attack phase; (ii) in migraine patients with aura compared to migraine patients without aura; and (iii) of regions within limbic, sensory, motor, executive and default mode networks and those which participate in multisensory integration. The results of this review show that headache disorders are associated with atypical functional connectivity of regions associated with pain processing as well as atypical functional connectivity of multiple core resting state networks such as the salience, sensorimotor, executive, attention, limbic, visual, and default mode networks.

Effect of hypoxia on BOLD fMRI response and total cerebral blood flow in migraine with aura patients

Experimentally induced hypoxia triggers migraine and aura attacks in patients suffering from migraine with aura (MA). We investigated the blood oxygenation level-dependent (BOLD) signal response to visual stimulation during hypoxia in MA patients and healthy volunteers. In a randomized double-blind crossover study design, 15 MA patients were allocated to 180 min of normobaric poikilocapnic hypoxia (capillary oxygen saturation 70-75%) or sham (normoxia) on two separate days and 14 healthy volunteers were exposed to hypoxia. The BOLD functional MRI (fMRI) signal response to visual stimulation was measured in the visual cortex ROIs V1-V5. Total cerebral blood flow (CBF) was calculated by measuring the blood velocity in the internal carotid arteries and the basilar artery using phase-contrast mapping (PCM) MRI. Hypoxia induced a greater decrease in BOLD response to visual stimulation in V1-V4 in MA patients compared to controls. There was no group difference in hypoxia-induced total CBF increase. In conclusion, the study demonstrated a greater hypoxia-induced decrease in BOLD response to visual stimulation in MA patients. We suggest this may represent a hypoxia-induced change in neuronal excitability or abnormal vascular response to visual stimulation, which may explain the increased sensibility to hypoxia in these patients leading to migraine attacks.

Migraine is associated with high brain 5-HT levels as indexed by 5-HT4 receptor binding

INTRODUCTION

Serotonin (5-HT) plays a role in migraine pathophysiology, but whether brain 5-HT is involved in the conversion from episodic to chronic migraine is unknown. Here, we investigated brain 5-HT levels, as indexed by 5-HT₄ receptor binding, in chronic migraine patients and evaluated whether these were associated with migraine frequency.

METHODS

Sixteen chronic migraine patients underwent a dynamic PET scan after injection of [¹¹C]SB207145, a specific 5-HT₄ receptor radioligand. Data from 15 episodic migraine patients and 16 controls were included for comparison. Quantification of 5-HT₄ receptor binding was used as a proxy for brain 5-HT levels, since 5-HT₄ receptor binding is inversely related to brain 5-HT levels.

RESULTS

Chronic migraine patients had 9.1% (95% CI: [-17%; -1.0%]) lower 5-HT₄ receptor binding compared to controls ( p = 0.039). There was no difference in 5-HT₄ receptor binding between chronic and episodic migraine patients ( p = 0.48) and no association between number of monthly migraine days and 5-HT₄ receptor binding (slope estimate 0.003, 95% CI: [-0.004; 0.715], p = 0.39).

CONCLUSION

The finding of low 5-HT₄ receptor binding suggests that cerebral levels of 5-HT are elevated in chronic migraine patients. This is in line with observations made in patients with episodic migraine. Elevated brain 5-HT levels may thus be an inherent trait of the migraine brain rather than a risk factor for conversion from episodic to chronic migraine.

Current understanding of thalamic structure and function in migraine

OBJECTIVE

To review and discuss the literature on the role of thalamic structure and function in migraine.

DISCUSSION

The thalamus holds an important position in our understanding of allodynia, central sensitization and photophobia in migraine. Structural and functional findings suggest abnormal functional connectivity between the thalamus and various cortical regions pointing towards an altered pain processing in migraine. Pharmacological nociceptive modulation suggests that the thalamus is a potential drug target.

CONCLUSION

A critical role for the thalamus in migraine-related allodynia and photophobia is well established. Additionally, the thalamus is most likely involved in the dysfunctional pain modulation and processing in migraine, but further research is needed to clarify the exact clinical implications of these findings.

Effects of sildenafil and calcitonin gene-related peptide on brainstem glutamate levels: a pharmacological proton magnetic resonance spectroscopy study at 3.0 T

BACKGROUND

Studies involving human pharmacological migraine models have predominantly focused on the vasoactive effects of headache-inducing drugs, including sildenafil and calcitonin gene-related peptide (CGRP). However, the role of possible glutamate level changes in the brainstem and thalamus is of emerging interest in the field of migraine research bringing forth the need for a novel, validated method to study the biochemical effects in these areas.

METHODS

We applied an optimized in vivo human pharmacological proton (¹H) magnetic resonance spectroscopy (MRS) protocol (PRESS, repetition time 3000 ms, echo time 37.6-38.3 ms) at 3.0 T in combination with sildenafil and CGRP in a double-blind, placebo-controlled, randomized, double-dummy, three-way cross-over design. Seventeen healthy participants were scanned with the ¹H-MRS protocol at baseline and twice (at 40 min and 140 min) after drug administration to investigate the sildenafil- and CGRP-induced glutamate changes in both brainstem and thalamus.

RESULTS

The glutamate levels increased transiently in the brainstem at 40-70 min after sildenafil administration compared to placebo (5.6%, P = 0.039). We found no sildenafil-induced glutamate changes in the thalamus, and no CGRP-induced glutamate changes in the brainstem or thalamus compared to placebo. Both sildenafil and CGRP induced headache in 53%-62% of participants. We found no interaction in the glutamate levels in the brainstem or thalamus between participants who developed sildenafil and/or CGRP-induced headache as compared to participants who did not.

CONCLUSIONS

The transient sildenafil-induced glutamate change in the brainstem possibly reflects increased excitability of the brainstem neurons. CGRP did not induce brainstem or thalamic glutamate changes, suggesting that it rather exerts its headache-inducing effects on the peripheral trigeminal pain pathways.

The Role of Endothelin in the Pathophysiology of Migraine-a Systematic Review

PURPOSE OF REVIEW

Vasoactive peptides play a key role in the attack-initiating cascade of migraine. Recent studies have highlighted a potentially important role for endothelin-1, a potent vasoconstrictor peptide, in migraine pathophysiology. Here, we review the current data on endothelin's involvement in migraine.

RECENT FINDINGS

We identified 23 articles. Nine studies reported on endothelin-1 plasma concentrations in patients with migraine, eight studies investigated relevant genetic associations, five studies investigated endothelin-1 and spreading depression in animals, and one randomized controlled clinical trial tested the efficacy of an endothelin antagonist in the acute treatment of migraine in patients both with and without aura. Elevated endothelin-1 plasma levels have been reported in the early phase of migraine attacks. Genetic abnormalities related to the endothelin type A receptor have been reported in migraineurs. Endothelin-1 potently induces spreading depression in animals, which may explain the connection between endothelial irritation and migraine aura. Endothelin-1 could be a primary factor in the attack-triggering cascade of migraine attacks with and without aura. Additional studies in humans and animal models are needed to further elucidate the role of endothelin-1 in migraine.

High brain serotonin levels in migraine between attacks: A 5-HT4 receptor binding PET study

Migraine has been hypothesized to be a syndrome of chronic low serotonin (5-HT) levels, but investigations of brain 5-HT levels have given equivocal results. Here, we used positron emission tomography (PET) imaging of the 5-HT4 receptor as a proxy for brain 5-HT levels. Given that the 5-HT4 receptor is inversely related to brain 5-HT levels, we hypothesized that between attacks migraine patients would have higher 5-HT4 receptor binding compared to controls. Eighteen migraine patients without aura (migraine free >48 h), and 16 age- and sex-matched controls underwent PET scans after injection of [11C]SB207145, a specific 5-HT4 receptor radioligand. An investigator blinded to group calculated a neocortical mean [11C]SB207145 binding potential (BPND). Three migraine patients reported a migraine attack within 48 h after the scan and were excluded from the primary analysis. Comparing 15 migraine patients and 16 controls, we found that migraine patients have significantly lower neocortical 5-HT4 receptor binding than controls (0.60 ± 0.09 vs. 0.67 ± 0.05, p = .024), corrected for 5-HTTLPR genotype, sex and age. We found no association between 5-HT4 receptor binding and attack frequency, years with migraine or time since last migraine attack. Our finding of lower 5-HT4 receptor binding in migraine patients is suggestive of higher brain 5-HT levels. This is in contrast with the current belief that migraine is associated with low brain 5-HT levels. High brain 5-HT levels may represent a trait of the migraine brain or it could be a consequence of migraine attacks.

Heterogenous migraine aura symptoms correlate with visual cortex functional magnetic resonance imaging responses

OBJECTIVE

Migraine aura is sparsely studied due to the highly challenging task of capturing patients during aura. Cortical spreading depression (CSD) is likely the underlying phenomenon of aura. The possible correlation between the multifaceted phenomenology of aura symptoms and the effects of CSD on the brain has not been ascertained.

METHODS

Five migraine patients were studied during various forms of aura symptoms induced by hypoxia, sham hypoxia, or physical exercise with concurrent photostimulation. The blood oxygenation level-dependent (BOLD) functional magnetic resonance imaging (fMRI) signal response to visual stimulation was measured in retinotopic mapping-defined visual cortex areas V1 to V4.

RESULTS

We found reduced BOLD response in patients reporting scotoma and increased response in patients who only experienced positive symptoms. Furthermore, patients with bilateral visual symptoms had corresponding bihemispherical changes in BOLD response.

INTERPRETATION

These findings suggest that different aura symptoms reflect different types of cerebral dysfunction, which correspond to specific changes in BOLD signal reactivity. Furthermore, we provide evidence of bilateral CSD recorded by fMRI during bilateral aura symptoms. Ann Neurol 2017;82:925-939.

Altered thalamic connectivity during spontaneous attacks of migraine without aura: A resting-state fMRI study

Background

Functional connectivity of brain networks may be altered in migraine without aura patients. Functional magnetic resonance imaging (fMRI) studies have demonstrated changed activity in the thalamus, pons and cerebellum in migraineurs. Here, we investigated the thalamic, pontine and cerebellar network connectivity during spontaneous migraine attacks.

Methods

Seventeen patients with episodic migraine without aura underwent resting-state fMRI scan during and outside of a spontaneous migraine attack. Primary endpoint was a difference in functional connectivity between the attack and the headache-free days. Functional connectivity was assessed in four different networks using seed-based analysis. The chosen seeds were in the thalamus (MNI coordinates x,y,z: right, 22,–24,0 and left, –22,–28,6), pons (right, 8,–24,–32 and left, –8,–24,–32), cerebellum crus I (right, 46,–58,–30 and left, –46,–58,–30) and cerebellum lobule VI (right, 34,–42,–36 and left, –32,–42,–36).

Results

We found increased functional connectivity between the right thalamus and several contralateral brain regions (superior parietal lobule, insular cortex, primary motor cortex, supplementary motor area and orbitofrontal cortex). There was decreased functional connectivity between the right thalamus and three ipsilateral brain areas (primary somatosensory cortex and premotor cortex). We found no change in functional connectivity in the pontine or the cerebellar networks.

Conclusions

The study indicates that network connectivity between thalamus and pain modulating as well as pain encoding cortical areas are affected during spontaneous migraine attacks.

Increased brainstem perfusion, but no blood-brain barrier disruption, during attacks of migraine with aura

See Moskowitz (doi:10.1093/brain/awx099) for a scientific commentary on this article.The migraine aura is characterized by transient focal cortical disturbances causing dramatic neurological symptoms that are usually followed by migraine headache. It is currently not understood how the aura symptoms are related to the headache phase of migraine. Animal studies suggest that cortical spreading depression, the likely mechanism of migraine aura, causes disruption of the blood-brain barrier and noxious stimulation of trigeminal afferents leading to activation of brainstem nuclei and triggering of migraine headache. We used the sensitive and validated technique of dynamic contrast-enhanced high-field magnetic resonance imaging to simultaneously investigate blood-brain barrier permeability and tissue perfusion in the brainstem (at the level of the lower pons), visual cortex, and brain areas of the anterior, middle and posterior circulation during spontaneous attacks of migraine with aura. Patients reported to our institution to undergo magnetic resonance imaging during the headache phase after presenting with typical visual aura. Nineteen patients were scanned during attacks and on an attack-free day. The mean time from attack onset to scanning was 7.6 h. We found increased brainstem perfusion bilaterally during migraine with aura attacks. Perfusion also increased in the visual cortex and posterior white matter following migraine aura. We found no increase in blood-brain barrier permeability in any of the investigated regions. There was no correlation between blood-brain barrier permeability, brain perfusion, and time from symptom onset to examination or pain intensity. Our findings demonstrate hyperperfusion in brainstem during the headache phase of migraine with aura, while the blood-brain barrier remains intact during attacks of migraine with aura. These data thus contradict the preclinical hypothesis of cortical spreading depression-induced blood-brain barrier disruption as a possible mechanism linking aura and headache.awx089media15422686892001.

Reproducibility of migraine-like attacks induced by phosphodiesterase-3-inhibitor cilostazol

Introduction

The phosphodiesterase-3-inhibitor cilostazol induces migraine-like attacks in patients with migraine without aura, and may be used as a pharmacological trigger in human experimental models of migraine. However, the reproducibility of cilostazol-induced migraine-like attacks has never been investigated.

Methods

We performed a post-hoc analysis of clinical data from two brain-imaging studies including subjects who had received cilostazol 200 mg orally. Only subjects who developed migraine-like attacks on study day 1 were included on study day 2. After cilostazol ingestion, subjects and the investigator recorded headache intensity and characteristics once every hour on a purpose-developed questionnaire. Primary end-points included incidence and time to onset of migraine-like attacks between two separate study days.

Results

Thirty-four subjects completed both experimental days and were included in this study. Thirty-four out of 34 subjects (100%) developed migraine-like attacks after cilostazol ingestion on both study days 1 and 2. Time to onset of migraine was five hours (range 1–8 hours) on study day 1 and four hours (range 1–8 hours) on study day 2, p = 0.16. We found no difference in median peak headache score, median time to peak headache score, or median time to intake of rescue medication between study days 1 and 2.

Conclusion

A second-time administration of cilostazol reproduces migraine-like attacks in all subjects who report an attack after their first cilostazol induction. There was no difference in time to migraine onset between separate inductions. Experimental migraine provocation using cilostazol is a highly efficient and useful approach for studying the ictal phase of migraine without aura.

Increased intrinsic brain connectivity between pons and somatosensory cortex during attacks of migraine with aura

The neurological disturbances of migraine aura are caused by transient cortical dysfunction due to waves of spreading depolarization that disrupt neuronal signaling. The effects of these cortical events on intrinsic brain connectivity during attacks of migraine aura have not previously been investigated. Studies of spontaneous migraine attacks are notoriously challenging due to their unpredictable nature and patient discomfort. We investigated 16 migraine patients with visual aura during attacks and in the attack-free state using resting state fMRI. We applied a hypothesis-driven seed-based approach focusing on cortical visual areas and areas involved in migraine pain, and a data-driven independent component analysis approach to detect changes in intrinsic brain signaling during attacks. In addition, we performed the analyses after mirroring the MRI data according to the side of perceived aura symptoms. We found a marked increase in connectivity during attacks between the left pons and the left primary somatosensory cortex including the head and face somatotopic areas (peak voxel: P = 0.0096, (x, y, z) = (-54, -32, 32), corresponding well with the majority of patients reporting right-sided pain. For aura-side normalized data, we found increased connectivity during attacks between visual area V5 and the lower middle frontal gyrus in the symptomatic hemisphere (peak voxel: P = 0.0194, (x, y, z) = (40, 40, 12). The present study provides evidence of altered intrinsic brain connectivity during attacks of migraine with aura, which may reflect consequences of cortical spreading depression, suggesting a link between aura and headache mechanisms. Hum Brain Mapp 38:2635-2642, 2017. © 2017 Wiley Periodicals, Inc.

Low 5-HT1B receptor binding in the migraine brain: A PET study

Background The pathophysiology of migraine may involve dysfunction of serotonergic signaling. In particular, the 5-HT_1B receptor is considered a key player due to the efficacy of 5-HT_1B receptor agonists for treatment of migraine attacks. Aim To examine the cerebral 5-HT_1B receptor binding in interictal migraine patients without aura compared to controls. Methods Eighteen migraine patients, who had been migraine free for >48 hours, and 16 controls were scanned after injection of the 5-HT_1B receptor specific radioligand [¹¹C]AZ10419369 for quantification of cerebral 5-HT_1B receptor binding. Patients who reported migraine <48 hours after the PET examination were excluded from the final analysis. We defined seven brain regions involved in pain modulation as regions of interest and applied a latent variable model (LVM) to assess the group effect on binding across these regions. Results Our data support a model wherein group status predicts the latent variable ( p = 0.038), with migraine patients having lower 5-HT_1B receptor binding across regions compared to controls. Further, in a whole-brain voxel-based analysis, time since last migraine attack correlated positively with 5-HT_1B receptor binding in the dorsal raphe and in the midbrain. Conclusion We report here for the first time that migraine patients have low 5-HT_1B receptor binding in pain modulating regions, reflecting decreased receptor density. This is either a primary constitutive trait of the migraine brain or secondary to repeated exposure to migraine attacks. We also provide indirect support for the dorsal raphe 5-HT_1B receptors being temporarily downregulated during the migraine attack, presumably in response to higher cerebral serotonin levels in the ictal phase.

Can migraine aura be provoked experimentally? A systematic review of potential methods for the provocation of migraine aura

Background

The nature of the migraine aura and its role in migraine pathophysiology is incompletely understood. In particular, the mechanisms underlying aura initiation and the causal relation between aura and headache are unknown. The scientific investigation of aura in patients is only possible if aura can be triggered. This paper reviews potential methods for the experimental provocation of migraine aura.

Methods

We systematically searched PubMed for studies of experimental migraine provocation, including case reports of patients with aura and reports of the occurrence of aura following exposure to any kind of suspected trigger.

Results

We identified 21 provocation studies, using 13 different prospective provocation methods, and 34 case reports. In the prospective studies, aura were reported following the administration of intravenous and sublingual glyceryl trinitrate, visual stimulation, physical activity, calcitonin gene-related peptide infusion, chocolate ingestion, and the intravenous injection of insulin. In addition, carotid artery puncture has consistently been reported as a trigger of aura.

Conclusions

No safe and efficient method for aura provocation exists at present, but several approaches could prove useful for this purpose.

General lack of use of placebo in prophylactic, randomised, controlled trials in adult migraine. A systematic review

Background

The Clinical Trials Subcommittee of the International Headache Society (IHS) recommends that a placebo arm is included in comparative randomised clinical trials (RCTs) of multiple prophylactic drugs due to the highly variable placebo response in migraine prophylaxis studies. The use of placebo control in such trials has not been systematically assessed.

Methods

We performed a systematic review of all comparative RCTs of prophylactic drug treatment of migraine published in English from 2002 to 2014. PubMed was searched using the Cochrane Highly Sensitive Search Strategy for identifying reports of RCTs.

Results

A placebo arm was used in <10% (three of 31) of prophylactic RCTs in migraine. In only 7.1% (two of 28) of the comparative RCTs without placebo was one drug superior to another drug. Thus in 26 RCTs, including one study requiring more than 75,000 patient days, no difference was identified across treatment arms and conclusions regarding drug superiority could not be drawn.

Conclusions

The majority of comparative, prophylactic migraine RCTs do not include a placebo arm. Failure to include a placebo arm may result in failure to demonstrate efficacy of potentially effective migraine-prophylactic agents. In order to benefit current and future patients, the current strong tendency to omit placebo-controls in these RCTs should be replaced by adherence to the guidelines of the IHS.

Serotonergic mechanisms in the migraine brain - a systematic review

Background Migraine is one of the most common and disabling of all medical conditions, affecting 16% of the general population, causing huge socioeconomic costs globally. Current available treatment options are inadequate. Serotonin is a key molecule in the neurobiology of migraine, but the exact role of brain serotonergic mechanisms remains a matter of controversy. Methods We systematically searched PubMed for studies investigating the serotonergic system in the migraine brain by either molecular neuroimaging or electrophysiological methods. Results The literature search resulted in 59 papers, of which 13 were eligible for review. The reviewed papers collectively support the notion that migraine patients have alterations in serotonergic neurotransmission. Most likely, migraine patients have a low cerebral serotonin level between attacks, which elevates during a migraine attack. Conclusion This review suggests that novel methods of investigating the serotonergic system in the migraine brain are warranted. Uncovering the serotonergic mechanisms in migraine pathophysiology could prove useful for the development of future migraine drugs.

Change in brain network connectivity during PACAP38-induced migraine attacks: A resting-state functional MRI study

OBJECTIVE

To investigate resting-state functional connectivity in the salience network (SN), the sensorimotor network (SMN), and the default mode network (DMN) during migraine attacks induced by pituitary adenylate cyclase-activating polypeptide-38 (PACAP38).

METHODS

In a double-blind, randomized study, 24 female migraine patients without aura received IV PACAP38 or vasoactive intestinal polypeptide (VIP) over 20 minutes. Both peptides are closely related and cause vasodilation, but only PACAP38 induces migraine attacks. VIP was therefore used as active placebo. Resting-state functional MRI was recorded before and during PACAP38-induced migraine attacks and before and after VIP infusion. We analyzed data by Statistical Parametric Mapping 8 and the Resting-State fMRI Data Analysis Toolkit for Matlab in a seed-based fashion.

RESULTS

PACAP38 (n = 16) induced migraine attacks and increased connectivity with the bilateral opercular part of the inferior frontal gyrus in the SN. In SMN, there was increased connectivity with the right premotor cortex and decreased connectivity with the left visual cortex. Several areas showed increased (left primary auditory, secondary somatosensory, premotor, and visual cortices) and decreased (right cerebellum and left frontal lobe) connectivity with DMN. We found no resting-state network changes after VIP (n = 15).

CONCLUSIONS

PACAP38-induced migraine attack is associated with altered connectivity of several large-scale functional networks of the brain.

Evidence of a Christmas spirit network in the brain: functional MRI study

OBJECTIVE

To detect and localise the Christmas spirit in the human brain.

DESIGN

Single blinded, cross cultural group study with functional magnetic resonance imaging (fMRI).

SETTING

Functional imaging unit and department of clinical physiology, nuclear medicine and PET in Denmark.

PARTICIPANTS

10 healthy people from the Copenhagen area who routinely celebrate Christmas and 10 healthy people living in the same area who have no Christmas traditions.

MAIN OUTCOME MEASURES

Brain activation unique to the group with Christmas traditions during visual stimulation with images with a Christmas theme.

METHODS

Functional brain scans optimised for detection of the blood oxygen level dependent (BOLD) response were performed while participants viewed a series of images with Christmas themes interleaved with neutral images having similar characteristics but containing nothing that symbolises Christmas. After scanning, participants answered a questionnaire about their Christmas traditions and the associations they have with Christmas. Brain activation maps from scanning were analysed for Christmas related activation in the "Christmas" and "non-Christmas" groups individually. Subsequently, differences between the two groups were calculated to determine Christmas specific brain activation.

RESULTS

Significant clusters of increased BOLD activation in the sensory motor cortex, the premotor and primary motor cortex, and the parietal lobule (inferior and superior) were found in scans of people who celebrate Christmas with positive associations compared with scans in a group having no Christmas traditions and neutral associations. These cerebral areas have been associated with spirituality, somatic senses, and recognition of facial emotion among many other functions.

CONCLUSIONS

There is a "Christmas spirit network" in the human brain comprising several cortical areas. This network had a significantly higher activation in a people who celebrate Christmas with positive associations as opposed to a people who have no Christmas traditions and neutral associations. Further research is necessary to understand this and other potential holiday circuits in the brain. Although merry and intriguing, these findings should be interpreted with caution.

Investigations of functional and structural changes in migraine with aura by magnetic resonance imaging

Migraine sufferers with aura often report visual discomfort outside of attacks and many consider bright or flickering light an attack-precipitating factor. The nature of this visual hypersensitivity and its relation to the underlying pathophysiology of the migraine aura is unknown. A useful technology to study these features of migraine with aura (MA) is functional magnetic resonance imaging (fMRI), which has the potential not only to detect, but also to localize hypersensitive cortex. The main objective of this thesis was to investigate the cortical responsivity of patients with MA during visual stimulation using fMRI. To optimize sensitivity, we applied a within-patient design by assessing functional interhemispheric differences in patients consistently experiencing visual aura in the same visual hemifield. To validate our data analysis methods, we initially studied healthy volunteers using single hemifield visual stimulation and compared the "stimulated" hemispheres (i.e. hemispheres contralateral to the visual stimulation) to the "non-stimulated" hemispheres. We then applied this validated method of interhemispheric comparison of fMRI-blood oxygenation level dependent (BOLD) activation to compare left versus right hemisphere responses to symmetric full-field visual stimulation in 54 healthy subjects (study I). This study concluded that, a) the applied visual stimulation is effective in activating large expanses of visual cortex, b) interhemispheric differences in fMRI-BOLD activation can be determined using the proposed method, and c) visual responses to symmetric full-field visual stimulation are asymmetrically distributed between the cerebral hemispheres. We investigated the effects of migraine aura, by including 20 patients with frequent side-fixed visual aura attacks, i.e. ≥= 90% of auras occurring in the same visual hemifield (study II). To circumvent bias relating to differences between right and left hemispheres (e.g. caused by physiological left/right bias, asymmetry of the visual stimulation or magnetic field inhomogeneity of the scanner), we included an equal number of patients with right- and left-sided symptoms. Further, we included 20 individually matched healthy controls with no history (including family history) of migraine. We compared the fMRI-BOLD responses to visual stimulation between symptomatic and asymptomatic hemispheres during the interictal phase and between migraine patients and controls. BOLD responses were selectively increased in the symptomatic hemispheres and localized in the inferior parietal lobule, the inferior frontal gyrus and the superior parietal lobule. The affected cortical areas comprise a visually driven functional network involved in oculomotor control, guidance of movement, motion perception, visual attention, and visual spatial memory. The patients also had significantly increased response in the same cortical areas when compared to controls. Since these findings theoretically could depend on aura-related differences in brain structure, we performed additional analyses (study III) to determine the relation between migraine aura and structural, cortical and subcortical, grey matter abnormalities. We analyzed structural MRI data from the same 20 patients and applied voxel-based morphometry and surface-based morphometry on a whole-hemisphere level and for specific anatomical regions of interest. Within-subject comparisons were made with regard to aura symptoms (N = 20 vs 20) and with regard to headache (N = 13 vs 13). We found no differences in grey matter structure with regard to aura symptoms in MA patients. Comparing the typical migraine headache side of the patients to the contralateral side revealed a difference in cortical thickness in the inferior frontal gyrus, which correlated significantly with the migraine attack frequency. In conclusion, we validated a method of interhemispheric comparison of fMRI-BOLD responses to visual stimulation. By using this method we discovered a lateralized alteration of a visually driven functional network in patients with side-fixed aura. These findings suggest a hyperexcitability of the visual system in the interictal phase of migraine with visual aura. Further, this abnormal function is not dependent on lateralized abnormalities of gray matter structure. However, alteration of the inferior frontal cortex related to headache lateralization could indicate structural reorganization of pain inhibitory circuits in response to the repeated intense nociceptive input due to the headache attacks.

Review of dose-response curves for acute antimigraine drugs: triptans, 5-HT1F agonists and CGRP antagonists

INTRODUCTION

Dose-response curves for efficacy and tolerability are the important determinants for the choice of doses of acute migraine drugs.

AREAS COVERED

Dose-response curves for the efficacy of seven triptans (5-HT1B/1D receptor agonists), a 5-HT1F receptor agonist (lasmiditan) and four oral calcitonin-gene related peptide receptor antagonists (telcagepant, MK-3207, BI 44370 TA and BMS-927711) in placebo-controlled trials were reviewed. In addition, dose-response curves for adverse events (AEs) were reviewed.

EXPERT OPINION

For most triptans, the dose-response curve for efficacy is flat, whereas AEs often increase with increasing doses. The two other groups of drugs also have flat dose-response curves for efficacy. Overall, the triptans still have the most favorable efficacy-tolerability profile. Current acute antimigraine drugs do not fulfill the expectations of the patients, and thus, there are many unmet needs. Although upcoming drugs may not be superior to triptans, migraine patients will potentially benefit greatly from these, especially patients who are triptan non-responders and patients with cardiovascular disease.

Cerebral Asymmetry of fMRI-BOLD Responses to Visual Stimulation

Hemispheric asymmetry of a wide range of functions is a hallmark of the human brain. The visual system has traditionally been thought of as symmetrically distributed in the brain, but a growing body of evidence has challenged this view. Some highly specific visual tasks have been shown to depend on hemispheric specialization. However, the possible lateralization of cerebral responses to a simple checkerboard visual stimulation has not been a focus of previous studies. To investigate this, we performed two sessions of blood-oxygenation level dependent (BOLD) functional magnetic resonance imaging (fMRI) in 54 healthy subjects during stimulation with a black and white checkerboard visual stimulus. While carefully excluding possible non-physiological causes of left-to-right bias, we compared the activation of the left and the right cerebral hemispheres and related this to grey matter volume, handedness, age, gender, ocular dominance, interocular difference in visual acuity, as well as line-bisection performance. We found a general lateralization of cerebral activation towards the right hemisphere of early visual cortical areas and areas of higher-level visual processing, involved in visuospatial attention, especially in top-down (i.e., goal-oriented) attentional processing. This right hemisphere lateralization was partly, but not completely, explained by an increased grey matter volume in the right hemisphere of the early visual areas. Difference in activation of the superior parietal lobule was correlated with subject age, suggesting a shift towards the left hemisphere with increasing age. Our findings suggest a right-hemispheric dominance of these areas, which could lend support to the generally observed leftward visual attentional bias and to the left hemifield advantage for some visual perception tasks.