Interictal metabolic changes in episodic migraine: a voxel-based FDG-PET study

Simultaneous arterial spin labeling functional MRI and fluorodeoxyglucose PET in mild chronic traumatic brain injury

BACKGROUND AND PURPOSE

To determine the effect of mild chronic traumatic brain injury (cTBI) on cerebral blood flow and metabolism.

METHODS

62 cTBI and 40 healthy controls (HCs) with no prior history of cTBI underwent both pulsed arterial spin labeling functional magnetic resonance imaging (PASL-fMRI) and fluorodeoxyglucose positron emission tomography (FDG-PET) scanning via a Siemens mMR (simultaneous PET/MRI) scanner. 30 participants also took part in a series of neuropsychological clinical measures (NCMs). Images were processed using statistical parametric mapping software relevant to each modality to generate relative cerebral blood flow (rCBF) and glucose metabolic standardized uptake value ratio (gSUVR) grey matter maps. A voxel-wise two-sample T-test and two-tailed gaussian random field correction for multiple comparisons was performed.

RESULTS

cTBI patients showed a significant increase in rCBF and gSUVR in the right thalamus as well as a decrease in bilateral occipital lobes and calcarine sulci. An inverse relationship between rCBF and gSUVR was found in the left frontal lobe, the left precuneus and regions in the right temporal lobe. Within those regions rCBF values correlated with 9 distinct NCMs and gSUVR with 3.

CONCLUSION

Simultaneous PASL-fMRI and FDG-PET can identify functional changes in a mild cTBI population. Within this population FDG-PET identified more regions of functional disturbance than ASL fMRI and NCMs are shown to correlate with rCBF and glucose metabolism (gSUVR) in various brain regions. As a result, both imaging modalities contribute to understanding the underlying pathophysiology and clinical course of mild chronic traumatic brain injury.

Mediterranean ketogenic diet accounts for reduced pain frequency and intensity in patients with chronic migraine: A pilot study

BACKGROUND

An increasing amount of evidence suggests that migraine is a response to cerebral energy deficiencies or oxidative stress levels that exceed antioxidant capacity. Current pharmacological options are inadequate in treating patients with chronic migraine, and a growing interest focuses on nutritional approaches as non-pharmacological treatments. The ketogenic diet, mimicking fasting that leads to an elevation of ketone bodies, is a therapeutic intervention targeting cerebral metabolism that has recently shown great promise in the prevention of migraines. Moreover, Mediterranean elements like vegetables, nuts, herbs, spices, and olive oil that are sources of anti-inflammatory elements (omega-3 fatty acids, polyphenols, vitamins, essential minerals, and probiotics) may create a positive brain environment by reducing imbalance in the gut microbiome.

METHODS

On the basis of these indications, a combined Mediterranean-ketogenic diet was administered to chronic migraine patients for 4 (T1) and 8 weeks (T2), and anthropometric estimations were collected at T1 and T2 while biochemical parameters at only T2.

RESULTS

A significant reduction (p < 0.01) in migraine frequency and intensity was detected as early as 4 weeks of dietary intervention, which was associated with a reduced fat mass (p < 0.001) as well as Homa index (p < 0.05) and insulin levels (p < 0.01) after 8 weeks.

CONCLUSION

Overall, Mediterranean-ketogenic diet may be considered an effective non-pharmacological intervention for migraine, with positive outcomes on body composition.

Mind the Metabolic Gap: Bridging Migraine and Alzheimer's disease through Brain Insulin Resistance

Brain insulin resistance has recently been described as a metabolic abnormality of brain glucose homeostasis that has been proven to downregulate insulin receptors, both in astrocytes and neurons, triggering a reduction in glucose uptake and glycogen synthesis. This condition may generate a mismatch between brain's energy reserve and expenditure, mainly during high metabolic demand, which could be involved in the chronification of migraine and, in the long run, at least in certain subsets of patients, in the prodromic phase of Alzheimer's disease, along a putative metabolic physiopathological continuum. Indeed, the persistent disruption of glucose homeostasis and energy supply to neurons may eventually impair protein folding, an energy-requiring process, promoting pathological changes in Alzheimer's disease, such as amyloid-β deposition and tau hyperphosphorylation. Hopefully, the "neuroenergetic hypothesis" presented herein will provide further insight on there being a conceivable metabolic bridge between chronic migraine and Alzheimer's disease, elucidating novel potential targets for the prophylactic treatment of both diseases.

Gastrodin alleviates NTG-induced migraine-like pain via inhibiting succinate/HIF-1α/TRPM2 signaling pathway in trigeminal ganglion

BACKGROUND

Increasing evidence highlights the involvement of metabolic disorder and calcium influx mediated by transient receptor potential channels in migraine; however, the relationship between these factors in the pathophysiology of migraine remains unknown. Gastrodin is the major component of the traditional Chinese medicine Tianma, which is extensively used in migraine therapy.

PURPOSE

Our work aimed to explore the analgesic action of gastrodin and its regulatory mechanisms from a metabolic perspective.

METHODS/RESULTS

After being treated with gastrodin, the mice were given nitroglycerin (NTG) to induce migraine. Gastrodin treatment significantly raised the threshold of sensitivity in response to both mechanical and thermal stimulus evidenced by von Frey and hot plate tests, respectively, and decreased total contact numbers in orofacial operant behavioral assessment. We found that the expression of transient receptor potential melastatin 2 (TRPM2) channel was increased in the trigeminal ganglion (TG) of NTG-induced mice, resulting in a sustained Ca2+ influx to trigger migraine pain. The content of succinate, a metabolic biomarker, was elevated in blood samples of migraineurs, as well as in the serum and TG tissue from NTG-induced migraine mice. Calcium imaging assay indicated that succinate insult elevated TRPM2-mediated calcium flux signal in TG neurons. Mechanistically, accumulated succinate upregulated hypoxia inducible factor-1α (HIF-1α) expression and promoted its translocation into nucleus, where HIF-1α enhanced TRPM2 expression through transcriptional induction in TG neurons, evidenced by luciferase reporter measurement. Gastrodin treatment inhibited TRPM2 expression and TRPM2-dependent Ca2+ influx by attenuating succinate accumulation and downstream HIF-1α signaling, and thereby exhibited analgesic effect.

CONCLUSION

This work revealed that succinate was a critical metabolic signaling molecule and the key mediator of migraine pain through triggering TRPM2-mediated calcium overload. Gastrodin alleviated NTG-induced migraine-like pain via inhibiting succinate/HIF-1α/TRPM2 signaling pathway in TG neurons. These findings uncovered the anti-migraine effect of gastrodin and its regulatory mechanisms from a metabolic perspective and provided a novel theoretical basis for the analgesic action of gastrodin.

Abnormal causal connectivity of anterior cingulate cortex-visual cortex circuit related to nonsteroidal anti-inflammatory drug efficacy in migraine

The anterior cingulate cortex (ACC) and visual cortex are integral components of the neurophysiological mechanisms underlying migraine, yet the impact of altered connectivity patterns between these regions on migraine treatment remains unknown. To elucidate this issue, we investigated the abnormal causal connectivity between the ACC and visual cortex in patients with migraine without aura (MwoA), based on the resting-state functional magnetic resonance imaging data, and its predictive ability for the efficacy of nonsteroidal anti-inflammatory drugs (NSAIDs). The results revealed increased causal connectivity from the bilateral ACC to the lingual gyrus (LG) and decreased connectivity in the opposite direction in nonresponders compared with the responders. Moreover, compared with the healthy controls, nonresponders exhibited heightened causal connectivity from the ACC to the LG, right inferior occipital gyrus (IOG) and left superior occipital gyrus, while connectivity patterns from the LG and right IOG to the ACC were diminished. Based on the observed abnormal connectivity patterns, the support vector machine (SVM) models showed that the area under the receiver operator characteristic curves for the ACC to LG, LG to ACC and bidirectional models were 0.857, 0.898, and 0.939, respectively. These findings indicate that neuroimaging markers of abnormal causal connectivity in the ACC-visual cortex circuit may facilitate clinical decision-making regarding NSAIDs administration for migraine management.

Migraine: Advances in the Pathogenesis and Treatment

This article presents a comprehensive review on migraine, a prevalent neurological disorder characterized by chronic headaches, by focusing on their pathogenesis and treatment advances. By examining molecular markers and leveraging imaging techniques, the research identifies key mechanisms and triggers in migraine pathology, thereby improving our understanding of its pathophysiology. Special emphasis is given to the role of calcitonin gene-related peptide (CGRP) in migraine development. CGRP not only contributes to symptoms but also represents a promising therapeutic target, with inhibitors showing effectiveness in migraine management. The article further explores traditional medical treatments, scrutinizing the mechanisms, benefits, and limitations of commonly prescribed medications. This provides a segue into an analysis of emerging therapeutic strategies and their potential to enhance migraine management. Finally, the paper delves into neuromodulation as an innovative treatment modality. Clinical studies indicating its effectiveness in migraine management are reviewed, and the advantages and limitations of this technique are discussed. In summary, the article aims to enhance the understanding of migraine pathogenesis and present novel therapeutic possibilities that could revolutionize patient care.

Imaging Correlates between Headache and Breast Cancer: An [18F]FDG PET Study

This study aimed to examine brain metabolic patterns on [18F]Fluorodeoxyglucose ([18F]FDG) positron emission tomography (PET) in breast cancer (BC), comparing patients with tension-type headache (TTH), migraine (MiG), and those without headache. Further association with BC response to neoadjuvant chemotherapy (NAC) was explored. In this prospective study, BC patients eligible for NAC performed total-body [18F]FDG PET/CT with a dedicated brain scan. A voxel-wise analysis (two-sample t-test) and a multiple regression model were used to compare brain metabolic patterns among TTH, MiG, and no-headache patients and to correlate them with clinical covariates. A single-subject analysis compared each patient's brain uptake before and after NAC with a healthy control group. Primary headache was diagnosed in 39/46 of BC patients (39% TTH and 46% MiG). TTH patients exhibited hypometabolism in specific brain regions before NAC. TTH patients with a pathological complete response (pCR) to NAC showed hypermetabolic brain regions in the anterior medial frontal cortex. The correlation between tumor uptake and brain metabolism varied before and after NAC, suggesting an inverse relationship. Additionally, the single-subject analysis revealed that hypometabolic brain regions were not present after NAC. Primary headache, especially MiG, was associated with a better response to NAC. These findings suggest complex interactions between BC, headache, and hormonal status, warranting further investigation in larger prospective cohorts.

Effect of acupuncture on the modulation of functional brain regions in migraine: A meta-analysis of fMRI studies

Background

Acupuncture, a traditional Chinese medicine therapy, is an effective migraine treatment, especially in improving pain. In recent years, many acupuncture brain imaging studies have found significant changes in brain function following acupuncture treatment of migraine, providing a new perspective to elucidate the mechanism of action of acupuncture.

Objective

To analyse and summarize the effects of acupuncture on the modulation of specific patterns of brain region activity changes in migraine patients, thus providing a mechanism for treating migraine by acupuncture.

Methods

Chinese and English articles published up to May 2022 were searched in three English databases (PubMed, Embase and Cochrane) and four Chinese databases (China national knowledge infrastructure, CNKI; Chinese Biomedical Literature database, CBM; the Chongqing VIP database, VIP; and the Wanfang database, WF). A neuroimaging meta-analysis on ALFF, ReHo was performed on the included studies using Seed-based d Mapping with Permutation of Subject Images (SDM-PSI) software. Subgroup analyses were used to compare differences in brain regions between acupuncture and other groups. Meta-regression was used to explore the effect of demographic information and migraine alterations on brain imaging outcomes. Linear models were drawn using MATLAB 2018a, and visual graphs for quality evaluation were produced using R and RStudio software.

Results

A total of 7 studies comprising 236 patients in the treatment group and 173 in the control group were included in the meta-analysis. The results suggest that acupuncture treatment helps to improve pain symptoms in patients with migraine. The left angular gyrus is hyperactivation, and the left superior frontal gyrus and the right superior frontal gyrus are hypoactivated. The migraine group showed hyperactivation in the corpus callosum compared to healthy controls.

Conclusion

Acupuncture can significantly regulate changes in brain regions in migraine patients. However, due to the experimental design of neuroimaging standards are not uniform, the results also have some bias. Therefore, to better understand the potential mechanism of acupuncture on migraine, a large sample, multicenter controlled trial is needed for further study. In addition, the application of machine learning methods in neuroimaging studies could help predict the efficacy of acupuncture and screen migraine patients suitable for acupuncture treatment.

Defining metabolic migraine with a distinct subgroup of patients with suboptimal inflammatory and metabolic markers

Emerging evidence suggest migraine is a response to cerebral energy deficiency or oxidative stress in the brain. Beta-hydroxybutyrate (BHB) is likely able to circumvent some of the meta-bolic abnormalities reported in migraine. Exogenous BHB was given to test this assumption and, in this post-hoc analysis, multiple metabolic biomarkers were identified to predict  clinical improvements. A randomized clinical trial, involving 41 patients with episodic migraine. Each treatment period was 12 weeks long, followed by eight weeks of washout phase / second run-in phase before entering the corresponding second treatment period. The primary endpoint was the number of migraine days in the last 4 weeks of treatment adjusted for baseline. BHB re-sponders were identified (those with at least a 3-day reduction in migraine days over placebo) and its predictors were evaluated using Akaike's Information Criterion (AIC) stepwise boot-strapped analysis and logistic regression. Responder analysis showed that metabolic markers could identify a "metabolic migraine" subgroup, which responded to BHB with a 5.7 migraine days reduction compared to the placebo. This analysis provides further support for a "metabolic migraine" subtype. Additionally, these analyses identified low-cost and easily accessible biomarkers that could guide recruitment in future research on this subgroup of patients.This study is part of the trial registration: ClinicalTrials.gov: NCT03132233, registered on 27.04.2017, https://clinicaltrials.gov/ct2/show/NCT03132233.

Spontaneous brain activity abnormalities in migraine: A meta-analysis of functional neuroimaging

Neuroimaging studies have demonstrated that migraine is accompanied by spontaneous brain activity alterations in specific regions. However, these findings are inconsistent, thus hindering our understanding of the potential neuropathology. Hence, we performed a quantitative whole-brain meta-analysis of relevant resting-state functional imaging studies to identify brain regions consistently involved in migraine. A systematic search of studies that investigated the differences in spontaneous brain activity patterns between migraineurs and healthy controls up to April 2022 was conducted. We then performed a whole-brain voxel-wise meta-analysis using the anisotropic effect size version of seed-based d mapping software. Complementary analyses including jackknife sensitivity analysis, heterogeneity test, publication bias test, subgroup analysis, and meta-regression analysis were conducted as well. In total, 24 studies that reported 31 datasets were finally eligible for our meta-analysis, including 748 patients and 690 controls. In contrast to healthy controls, migraineurs demonstrated consistent and robust decreased spontaneous brain activity in the angular gyrus, visual cortex, and cerebellum, while increased activity in the caudate, thalamus, pons, and prefrontal cortex. Results were robust and highly replicable in the following jackknife sensitivity analysis and subgroup analysis. Meta-regression analyses revealed that a higher visual analog scale score in the patient sample was associated with increased spontaneous brain activity in the left thalamus. These findings provided not only a comprehensive overview of spontaneous brain activity patterns impairments, but also useful insights into the pathophysiology of dysfunction in migraine.

Resting-state abnormalities in functional connectivity of the default mode network in migraine: A meta-analysis

Migraine-a disabling neurological disorder, imposes a tremendous burden on societies. To reduce the economic and health toll of the disease, insight into its pathophysiological mechanism is key to improving treatment and prevention. Resting-state functional magnetic resonance imaging (rs-fMRI) studies suggest abnormal functional connectivity (FC) within the default mode network (DMN) in migraine patients. This implies that DMN connectivity change may represent a biomarker for migraine. However, the FC abnormalities appear inconsistent which hinders our understanding of the potential neuropathology. Therefore, we performed a meta-analysis of the FC within the DMN in migraine patients in the resting state to identify the common FC abnormalities. With efficient search and selection strategies, nine studies (published before July, 2022) were retrieved, containing 204 migraine patients and 199 healthy subjects. We meta-analyzed the data using the Anisotropic Effect Size version of Signed Differential Mapping (AES-SDM) method. Compared with healthy subjects, migraine patients showed increased connectivity in the right calcarine gyrus, left inferior occipital gyrus, left postcentral gyrus, right cerebellum, right parahippocampal gyrus, and right posterior cingulate gyrus, while decreased connectivity in the right postcentral gyrus, left superior frontal gyrus, right superior occipital gyrus, right orbital inferior frontal gyrus, left middle occipital gyrus, left middle frontal gyrus and left inferior frontal gyrus. These results provide a new perspective for the study of the pathophysiology of migraine and facilitate a more targeted treatment of migraine in the future.

Alterations in metabolic flux in migraine and the translational relevance

BACKGROUND

Migraine is a highly prevalent disorder with significant economical and personal burden. Despite the development of effective therapeutics, the causes which precipitate migraine attacks remain elusive. Clinical studies have highlighted altered metabolic flux and mitochondrial function in patients. In vivo animal experiments can allude to the metabolic mechanisms which may underlie migraine susceptibility. Understanding the translational relevance of these studies are important to identifying triggers, biomarkers and therapeutic targets in migraine.

MAIN BODY

Functional imaging studies have suggested that migraineurs feature metabolic syndrome, exhibiting hallmark features including upregulated oxidative phosphorylation yet depleted available free energy. Glucose hypometabolism is also evident in migraine patients and can lead to altered neuronal hyperexcitability such as the incidence of cortical spreading depression (CSD). The association between obesity and increased risk, frequency and worse prognosis of migraine also highlights lipid dysregulation in migraine pathology. Calcitonin gene related peptide (CGRP) has demonstrated an important role in sensitisation and nociception in headache, however its role in metabolic regulation in connection with migraine has not been thoroughly explored. Whether impaired metabolic function leads to increased release of peptides such as CGRP or excessive nociception leads to altered flux is yet unknown.

CONCLUSION

Migraine susceptibility may be underpinned by impaired metabolism resulting in depleted energy stores and altered neuronal function. This review discusses both clinical and in vivo studies which provide evidence of altered metabolic flux which contribute toward pathophysiology. It also reviews the translational relevance of animal studies in identifying targets of biomarker or therapeutic development.

Proteomic and metabolomic profiling of acupuncture for migraine reveals a correlative link via energy metabolism

Migraine is a neurovascular disease with a high disability rate. Acupuncture treatment has emerged as a safe and viable alternative prophylactic therapy that can effectively alleviate the duration and frequency of migraine attacks. However, the therapeutic mechanisms underlying the effects of acupuncture are yet to be systematically elucidated. In this study, we enrolled female patients with migraine without aura (n = 20) and healthy controls (n = 10). Patients received acupuncture treatment on DU20, DU24, bilateral GB13, GB8, and GB20, applied three times per week over the course of 4 weeks for 12 sessions in total. Blood samples were collected from the median cubital vein before and after acupuncture treatment. Proteomic and metabolomic profiling was performed using liquid chromatography-mass spectrometry to determine the characteristics of differentially expressed molecules and expression of their corresponding biological pathways as well as to elucidate the pathogenesis of migraine and the biological effects underlying the treatment of migraine with acupuncture. Proteomic and metabolomic profiling of plasma samples from patients with migraine without aura before and after acupuncture treatment revealed enrichment of immune-related pathway functions and the arginine synthesis pathway. Joint pathway analyses revealed significant enrichment of the pentose phosphate and glycolysis/gluconeogenesis pathways in patients with migraine. The glycolysis/gluconeogenesis and riboflavin metabolism pathways were significantly enriched after acupuncture treatment. The expression levels of various key proteins and metabolites, including α-D-glucose, flavin adenine dinucleotide, biliverdin reductase B, and L-glutamate, were significantly differentially expressed before and after acupuncture treatment in patients with migraine without aura. Treatment of migraine with acupuncture was associated with significant changes in key molecules and pathways, indicative of physiological changes in the trigeminovascular system, glutamate neurotoxicity, and other migraine-related physiological changes. Overall, our comprehensive analysis using proteomic and metabolomic profiling demonstrates that energy metabolism may serve as a key correlative link in the occurrence of migraine and the therapeutic effects of acupuncture treatment. Our findings may facilitate the identification of diagnostic and therapeutic modalities in the ongoing search for effective treatments for migraine attacks.

Migraine, Brain Glucose Metabolism and the "Neuroenergetic" Hypothesis: A Scoping Review

Increasing evidence suggests that migraine may be the result of an impaired brain glucose metabolism. Several studies have reported brain mitochondrial dysfunction, impaired brain glucose metabolism and gray matter volume reduction in specific brain areas of migraineurs. Furthermore, peripheral insulin resistance, a condition demonstrated in several studies, may extend to the brain, leading to brain insulin resistance. This condition has been proven to downregulate insulin receptors, both in astrocytes and neurons, triggering a reduction in glucose uptake and glycogen synthesis, mainly during high metabolic demand. This scoping review examines the clinical, epidemiologic and pathophysiologic data supporting the hypothesis that abnormalities in brain glucose metabolism may generate a mismatch between the brain's energy reserve and metabolic expenditure, triggering migraine attacks. Moreover, alteration in glucose homeostasis could generate a chronic brain energy deficit promoting migraine chronification. Lastly, insulin resistance may link migraine with its comorbidities, like obesity, depression, cognitive impairment and cerebrovascular diseases. PERSPECTIVE: Although additional experimental studies are needed to support this novel "neuroenergetic" hypothesis, brain insulin resistance in migraineurs may unravel the pathophysiological mechanisms of the disease, explaining the migraine chronification and connecting migraine with comorbidities. Therefore, this hypothesis could elucidate novel potential approaches for migraine treatment.

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.

Identification of disease- and headache-specific mediators and pathways in migraine using blood transcriptomic and metabolomic analysis

BACKGROUND

Recent data suggest that gene expression profiles of peripheral white blood cells can reflect changes in the brain. We aimed to analyze the transcriptome of peripheral blood mononuclear cells (PBMC) and changes of plasma metabolite levels of migraineurs in a self-controlled manner during and between attacks.

METHODS

Twenty-four patients with migraine were recruited and blood samples were collected in a headache-free (interictal) period and during headache (ictal) to investigate disease- and headache-specific alterations. Control samples were collected from 13 age- and sex-matched healthy volunteers. RNA was isolated from PBMCs and single-end 75 bp RNA sequencing was performed using Illumina NextSeq 550 instrument followed by gene-level differential expression analysis. Functional analysis was carried out on information related to the role of genes, such as signaling pathways and biological processes. Plasma metabolomic measurement was performed with the Biocrates MxP Quant 500 Kit.

RESULTS

We identified 144 differentially-expressed genes in PBMCs between headache and headache-free samples and 163 between symptom-free patients and controls. Network analysis revealed that enriched pathways included inflammation, cytokine activity and mitochondrial dysfunction in both headache and headache-free samples compared to controls. Plasma lactate, succinate and methionine sulfoxide levels were higher in migraineurs while spermine, spermidine and aconitate were decreased during attacks.

CONCLUSIONS

It is concluded that enhanced inflammatory and immune cell activity, and oxidative stress can play a role in migraine susceptibility and headache generation.

Migraine attacks as a result of hypothalamic loss of control

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Hypothalamo-limbic connectivity reflects the cyclic nature of migraine.

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Hypothalamo-limbic connectivity is largest just before the attack.

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Hypothalamo-limbic connectivity is collapsing during the attack.

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Limbic perfusion is increasing and has a maximum during the attack.

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The disrupted connectivity allows high limbic perfusion, resulting in migraine attack.

Migraine is a complex neurological disorder affecting approximately 12% of the population. The pathophysiology is not yet fully understood, however the clinical features of the disease, such as the cyclic behaviour of attacks and vegetative symptoms, suggest a prominent role of the hypothalamus. Previous research has observed neuronal alterations at different time points during the migraine interval, specifically just before the headache is initiated. We therefore aimed to assess the trajectory of migraineurs’ brain activity over an entire migraine cycle.

Using functional magnetic resonance imaging (fMRI) with pseudo-continuous arterial spin labelling (ASL), we designed a longitudinal intra-individual study to detect the rhythmicity of (1) the cerebral perfusion and (2) the hypothalamic connectivity over an entire migraine cycle. Twelve episodic migraine patients were examined in 82 sessions during spontaneous headache attacks with follow-up recordings towards the next attack.

We detected cyclic changes of brain perfusion in the limbic circuit (insula and nucleus accumbens), with the highest perfusion during the headache attack. In addition, we found an increase of hypothalamic connectivity to the limbic system over the interictal interval towards the attack, then collapsing during the headache phase.

The present data provide strong evidence for the predominant role of the hypothalamus in generating migraine attacks. Due to a genetically-determined cortical hyperexcitability, migraineurs are most likely characterised by an increased susceptibility of limbic neurons to the known migraine trigger. The hypothalamus as a metronome of internal processes is suggested to control these limbic circuits: migraine attacks may occur as a result of the hypothalamus losing control over the limbic system. Repetitive psychosocial stress, one of the leading trigger factors reported by patients, might make the limbic system even more vulnerable and lead to a premature triggering of a migraine attack. Potential therapeutic interventions are therefore suggested to strengthen limbic circuits with dedicated medication or psychological approaches.

Early alterations of cortical thickness and gyrification in migraine without aura: a retrospective MRI study in pediatric patients

Background

Migraine is the most common neurological disease, with high social-economical burden. Although there is growing evidence of brain structural and functional abnormalities in patients with migraine, few studies have been conducted on children and no studies investigating cortical gyrification have been conducted on pediatric patients affected by migraine without aura.

Methods

Seventy-two pediatric patients affected by migraine without aura and eighty-two controls aged between 6 and 18 were retrospectively recruited with the following inclusion criteria: MRI exam showing no morphological or signal abnormalities, no systemic comorbidities, no abnormal neurological examination. Cortical thickness (CT) and local gyrification index (LGI) were obtained through a dedicated algorithm, consisting of a combination of voxel-based and surface-based morphometric techniques. The statistical analysis was performed separately on CT and LGI between: patients and controls; subgroups of controls and subgroups of patients.

Results

Patients showed a decreased LGI in the left superior parietal lobule and in the supramarginal gyrus, compared to controls. Female patients presented a decreased LGI in the right superior, middle and transverse temporal gyri, right postcentral gyrus and supramarginal gyrus compared to male patients. Compared to migraine patients younger than 12 years, the ≥ 12-year-old subjects showed a decreased CT in the superior and middle frontal gyri, pre- and post-central cortex, paracentral lobule, superior and transverse temporal gyri, supramarginal gyrus and posterior insula. Migraine patients experiencing nausea and/or vomiting during headache attacks presented an increased CT in the pars opercularis of the left inferior frontal gyrus.

Conclusions

Differences in CT and LGI in patients affected by migraine without aura may suggest the presence of congenital and acquired abnormalities in migraine and that migraine might represent a vast spectrum of different entities. In particular, ≥ 12-year-old pediatric patients showed a decreased CT in areas related to the executive function and nociceptive networks compared to younger patients, while female patients compared to males showed a decreased CT of the auditory cortex compared to males. Therefore, early and tailored therapies are paramount to obtain migraine control, prevent cerebral reduction of cortical thickness and preserve executive function and nociception networks to ensure a high quality of life.

Cortical metabolic and structural differences in patients with chronic migraine. An exploratory 18FDG-PET and MRI study

Background

To describe interictal brain structural and metabolic differences between patients with episodic migraine (EM), chronic migraine (CM) and healthy controls (HC).

Methods

This is an exploratory study including right-handed age-matched women with EM, CM and HC. On the same day, a sequential interictal scan was performed with ¹⁸FDG-PET and MRI. 3D T1-weighted images were segmented with FreeSurfer, normalized to a reference atlas and the mean values of metabolism, cortical thickness (CTh) and local gyrification index (IGI) were determined. Groups were compared using age-adjusted linear models, corrected for multiple comparisons. ¹⁸FDG-PET measurements between groups were also analysed adjusting by patient’s age, CTh and lGI. The variables independently associated with diagnosis were obtained using a logistic regression analysis.

Results

Fifteen patients (8 EM, 7 CM) and 11 HC were included. Morphometric data showed an increased CTh in 6 frontal areas (L/R-Caudal Middle Frontal, L/R-Rostral Middle Frontal, L-Medial Orbitofrontal and L-Superior Frontal) in CM patients compared to HC without differences for IGI. The structural adjusted analysis in CM showed a statistically significantly hypometabolism in 9 frontal areas (L-Lateral Orbitofrontal, L/R-Medial Orbitofrontal, L-Frontal Superior, R-Frontal pole, R-Parts Triangularis, L/R-Paracentral and R-Precentral) and 7 temporal areas (L/R-Insula, L/R-Inferior temporal, L/R-Temporal pole and R-Banks superior temporal sulcus) compared to HC. EM patients presented intermediate metabolic values ​​between EM and HC (non-significant).

Conclusions

CM patients showed frontotemporal hypometabolism and increased frontal cortical thickness when compared to HC that may explain some cognitive and behavioural pain-processing and sensory integration alterations in CM patients. Combined information from sequential or simultaneous PET and MRI could optimize the study of complex functional neurological disorders such as migraine.

Supplementary Information

The online version contains supplementary material available at 10.1186/s10194-021-01289-5.

Migraine Is More Than Just Headache: Is the Link to Chronic Fatigue and Mood Disorders Simply Due to Shared Biological Systems?

Migraine is a symptomatically heterogeneous condition, of which headache is just one manifestation. Migraine is a disorder of altered sensory thresholding, with hypersensitivity among sufferers to sensory input. Advances in functional neuroimaging have highlighted that several brain areas are involved even prior to pain onset. Clinically, patients can experience symptoms hours to days prior to migraine pain, which can warn of impending headache. These symptoms can include mood and cognitive change, fatigue, and neck discomfort. Some epidemiological studies have suggested that migraine is associated in a bidirectional fashion with other disorders, such as mood disorders and chronic fatigue, as well as with other pain conditions such as fibromyalgia. This review will focus on the literature surrounding alterations in fatigue, mood, and cognition in particular, in association with migraine, and the suggested links to disorders such as chronic fatigue syndrome and depression. We hypothesize that migraine should be considered a neural disorder of brain function, in which alterations in aminergic networks integrating the limbic system with the sensory and homeostatic systems occur early and persist after headache resolution and perhaps interictally. The associations with some of these other disorders may allude to the inherent sensory sensitivity of the migraine brain and shared neurobiology and neurotransmitter systems rather than true co-morbidity.

Evidence of Potential Mechanisms of Acupuncture from Functional MRI Data for Migraine Prophylaxis

PURPOSE OF REVIEW

To summarize the clinical neuroimaging evidence pertaining to the potential mechanisms of acupuncture for migraine prophylaxis.

RECENT FINDINGS

From a descriptive perspective, converging evidence from recent neuroimaging studies, mainly from functional MRI (fMRI) studies, has demonstrated that when compared with sham acupuncture, verum acupuncture could normalize the decrease of the functional connectivity of the rostral ventromedial medulla-trigeminocervical complex (RVM/TCC) network, frontal-parietal network, cingulo-opercular networks, and default mode network and could normalize sensorimotor network connectivity with sensory-, affective-, and cognitive-related brain areas. These areas overlap with those of the pain matrix. Verum acupuncture works in a more targeted and unique manner compared with sham acupuncture in patients with migraine. These findings from neuroimaging studies may provide new perspectives on the validation of acupoints specificity and confirm the central modulating effects of acupuncture as a migraine prevention treatment. However, the exact mechanism by which acupuncture works for migraine prophylaxis remains unclear and warrants investigation. Future studies with larger sample sizes are still needed to confirm the current results and to further evaluate the complex and specific effects of acupuncture by analyzing different stimulus conditions, such as verum vs. sham acupuncture, deqi vs. no deqi, different acupuncture points or meridians, and different manipulation methods. Moreover, instead of focusing on the changes in a single area of the brain, researchers should focus more on the relationships among the functional connectivity network of brain areas such as the RVM/TCC, thalamus, anterior cingulate cortex (ACC), superior temporal gyrus (STG), and supplementary motor area (SMA) to explore the underlying mechanism of the effects of acupuncture.

The Role of Metabolism in Migraine Pathophysiology and Susceptibility

Migraine is a highly prevalent and disabling primary headache disorder, however its pathophysiology remains unclear, hindering successful treatment. A number of key secondary headache disorders have headaches that mimic migraine. Evidence has suggested a role of mitochondrial dysfunction and an imbalance between energetic supply and demand that may contribute towards migraine susceptibility. Targeting these deficits with nutraceutical supplementation may provide an additional adjunctive therapy. Neuroimaging techniques have demonstrated a metabolic phenotype in migraine similar to mitochondrial cytopathies, featuring reduced free energy availability and increased metabolic rate. This is reciprocated in vivo when modelling a fundamental mechanism of migraine aura, cortical spreading depression. Trials assessing nutraceuticals successful in the treatment of mitochondrial cytopathies including magnesium, coenzyme q10 and riboflavin have also been conducted in migraine. Although promising results have emerged from nutraceutical trials in patients with levels of minerals or vitamins below a critical threshold, they are confounded by lacking control groups or cohorts that are not large enough to be representative. Energetic imbalance in migraine may be relevant in driving the tissue towards maximum metabolic capacity, leaving the brain lacking in free energy. Personalised medicine considering an individual's deficiencies may provide an approach to ameliorate migraine.

Mitochondrial function and oxidative stress markers in higher-frequency episodic migraine

Increasing evidence points towards the role of mitochondrial functioning, energy metabolism, and oxidative stress in migraine. However not all previous research has been conclusive and some mitochondrial function/oxidative stress markers have not yet been examined. To this end, alpha-lipoic acid (ALA), total thiols, total plasma antioxidant capacity (TAC), lipid peroxide (PerOx), oxidised LDL (oxLDL), HbA1c and lactate were determined in the serum of 32 higher frequency episodic migraineurs (5-14 migraine days/ months, 19 with aura, 28 females) in this cross-sectional study. The majority of patients had abnormally low ALA and lactate levels (87.5% and 78.1%, respectively). 46.9% of the patients had abnormally high PerOx values, while for thiols and TAC over one third of patients had abnormally low values (31.2% and 37.5%, respectively). 21.9% of patients had abnormally low HbA1c and none had an HbA1c level above 5.6%. oxLDL was normal in all but one patient. This study provides further evidence for a role of oxidative stress and altered metabolism in migraine pathophysiology, which might represent a suitable therapeutic target. ALA, being too low in almost 90% of patients, might represent a potential biomarker for migraine. Further research is needed to replicate these results, in particular a comparison with a control group.This study is part of the trial registration: ClinicalTrials.gov: NCT03132233, registered on 27.04.2017, https://clinicaltrials.gov/ct2/show/NCT03132233 .

Aberrant activity within auditory network is associated with psychiatric comorbidities in interictal migraineurs without aura

The present study aimed to explore associations between brain activity in the auditory cortex and clinical and psychiatric characteristics in patients with migraine without aura (MwoA) during interictal periods. Resting-state data were acquired from patients with episodic MwoA (n = 34) and healthy controls (n = 30). Independent component analysis was used to extract and calculate the resting-state auditory network. Subsequently, we analyzed the correlations between spontaneous activity in the auditory cortex and clinical and psychiatric features in interictal MwoA. Compared with healthy controls, patients with MwoA showed increased activity in the left superior temporal gyrus (STG), postcentral gyrus (PoCG) and insula. Brain activity in the left STG was positively correlated with anxiety scores, and activity in the left PoCG was negatively correlated with anxiety and depression scores. No significant differences were found in intracranial volume between the two groups. This study indicated that functional impairment and altered integration linked to the auditory cortex existed in patients with MwoA in the interictal period, suggesting that auditory-associated cortex disruption as a biomarker may be implemented for the early diagnosis and prediction of neuropsychiatric impairment in interictal MwoA patients.

Structural and functional footprint of visual snow syndrome

Patients with visual snow syndrome suffer from a continuous pan-field visual disturbance, additional visual symptoms, tinnitus, and non-perceptional symptoms. The pathophysiology of visual symptoms might involve dysfunctional visual cortex. So far, the extra-visual system has not been investigated. We aimed at identifying structural and functional correlates for visual and non-visual symptoms in visual snow syndrome. Patients were compared to age- and sex-matched controls using ¹⁸F-2-fluoro-2-deoxy-d-glucose PET (n = 20 per group) and voxel-based morphometry (n = 17 per group). Guided by the PET results, region of interest analysis was done in voxel-based morphometry to identify structural-functional correspondence. Grey matter volume was assessed globally. Patients had corresponding hypermetabolism and cortical volume increase in the extrastriate visual cortex at the junction of the right lingual and fusiform gyrus. There was hypometabolism in the right superior temporal gyrus and the left inferior parietal lobule. Patients had grey matter volume increases in the temporal and limbic lobes and decrease in the superior temporal gyrus. The corresponding structural and functional alterations emphasize the relevance of the visual association cortex for visual snow syndrome. The broad structural and functional footprint, however, confirms the clinical impression that the disorder extends beyond the visual system.

Metabolomics markers in Neurology: current knowledge and future perspectives for therapeutic targeting

INTRODUCTION

Metabolomics is an emerging approach providing new insights into the metabolic changes and underlying mechanisms involved in the pathogenesis of neurological disorders.

AREAS COVERED

Here, the authors present an overview of the current knowledge of metabolic profiling (metabolomics) to provide critical insight on the role of biochemical markers and metabolic alterations in neurological diseases.

EXPERT OPINION

Elucidation of characteristic metabolic alterations in neurological disorders is crucial for a better understanding of their pathogenesis, and for identifying potential biomarkers and drug targets. Nevertheless, discrepancies in diagnostic criteria, sample handling protocols, and analytical methods still affect the generalizability of current study results.

Disrupted functional connectivity between sub-regions in the sensorimotor areas and cortex in migraine without aura

Background

Migraine is a severe and disabling brain disorder, and the exact neurological mechanisms remain unclear. Migraineurs have altered pain perception, and headache attacks disrupt their sensory information processing and sensorimotor integration. The altered functional connectivity of sub-regions of sensorimotor brain areas with other brain cortex associated with migraine needs further investigation.

Methods

Forty-eight migraineurs without aura during the interictal phase and 48 age- and sex-matched healthy controls underwent resting-state functional magnetic resonance imaging scans. We utilized seed-based functional connectivity analysis to investigate whether patients exhibited abnormal functional connectivity between sub-regions of sensorimotor brain areas and cortex regions.

Results

We found that patients with migraineurs without aura exhibited disrupted functional connectivities between the sensorimotor areas and the visual cortex, temporal cortex, posterior parietal lobule, prefrontal areas, precuneus, cingulate gyrus, sensorimotor areas proper and cerebellum areas compared with healthy controls. In addition, the clinical data of the patients, such as disease duration, pain intensity and HIT-6 score, were negatively correlated with these impaired functional connectivities.

Conclusion

In patients with migraineurs without aura, the functional connectivities between the sensorimotor brain areas and other brain regions was reduced. These disrupted functional connectivities might contribute to abnormalities in visual processing, multisensory integration, nociception processing, spatial attention and intention and dysfunction in cognitive evaluation and modulation of pain. Recurrent headache attacks might lead to the disrupted network between primary motor cortex and temporal regions and between primary somatosensory cortex and temporal regions. Pain sensitivity and patient quality of life are closely tied to the abnormal functional connectivity between sensorimotor regions and other brain areas.

The functional alterations in primary migraine: A systematic review and meta-analysis protocol

INTRODUCTION

Accumulating neuroimaging studies have found abnormal cerebral activity in migraine patients. However, the findings of studies exist many differences. Hence, this protocol aims to investigate concurrence across the neuroimaging studies to verify the functional cerebral alterations based on the latest evidence.

METHODS AND ANALYSIS

Functional neuroimaging studies comparing migraineur with healthy subjects will be searched in the 4 online databases (EMBASE, the Cochrane Library, PubMed, and Web of Science) up to June 2019. The selection of studies, quality assessment, and data extraction will be conducted by 2 independent researchers. The Anisotropic effect size version of signed differential mapping (AES-SDM) methods will be used to conduct a coordinate-based meta-analysis. The bias of publication will be confirmed via the P value of Egger test. The quality of studies will be evaluated by the Newcastle-Ottawa Scale (NOS). This study is registered with PROSPERO, number CRD42019129043.

RESULTS

This study will deepen the understanding of functional cerebral alterations of migraine.

CONCLUSION

The study will provide clear conclusion of the functional cerebral alterations based on the latest evidence.

The metabolic face of migraine - from pathophysiology to treatment

Migraine can be regarded as a conserved, adaptive response that occurs in genetically predisposed individuals with a mismatch between the brain's energy reserve and workload. Given the high prevalence of migraine, genotypes associated with the condition seem likely to have conferred an evolutionary advantage. Technological advances have enabled the examination of different aspects of cerebral metabolism in patients with migraine, and complementary animal research has highlighted possible metabolic mechanisms in migraine pathophysiology. An increasing amount of evidence - much of it clinical - suggests that migraine is a response to cerebral energy deficiency or oxidative stress levels that exceed antioxidant capacity and that the attack itself helps to restore brain energy homeostasis and reduces harmful oxidative stress levels. Greater understanding of metabolism in migraine offers novel therapeutic opportunities. In this Review, we describe the evidence for abnormalities in energy metabolism and mitochondrial function in migraine, with a focus on clinical data (including neuroimaging, biochemical, genetic and therapeutic studies), and consider the relationship of these abnormalities with the abnormal sensory processing and cerebral hyper-responsivity observed in migraine. We discuss experimental data to consider potential mechanisms by which metabolic abnormalities could generate attacks. Finally, we highlight potential treatments that target cerebral metabolism, such as nutraceuticals, ketone bodies and dietary interventions.

Is There Any MRI Pattern That Discriminates Female From Male Migraine Patients?

There has been accumulating evidence on sex disparity in incidence, prevalence, symptomology, and burden of migraine. Several neuroimaging studies on migraine patients attempted to unravel the mechanisms of the disease, yet very few of them examined the sex-related differences. Here, we will first discuss some of the reported neuroimaging patterns that discriminate females from males in migraine. We will then re-examine the salient neuroimaging findings in migraine and discuss them in relation to sex-related influences. Finally, we will discuss some of the intriguing recent data suggesting the presence of sex-specific traits in migraineurs. These findings may have potential implications for future neuroimaging studies to identify underlying correlating patterns in the brain to (1) explain the neural basis for higher prevalence of migraine in women, and (2) better understand migraine-specific changes during different stages of life in both men and women.

Alterations in Regional Homogeneity Assessed by fMRI in Patients with Migraine Without Aura

The aim of this study was to investigate the alterations in regional homogeneity assessed by fMRI in patients with migraine without aura (MWoA). Fifty-six eligible MWoA patients and 32 matched healthy volunteers were enrolled in this study. MWoA patients were divided into three groups according to the headache days per month within 3 months: infrequent episodic migraine (IEM) group, frequent episodic migraine (FEM) group, and chronic migraine (CM) group. Data collection and rest-state fMRI examination were performed in all cases. The ReHo method was used to analyze the blood oxygen level dependent (BLOD) signals of the adjacent voxels in the brain regions of each patient, and the consistency of their fluctuations in the sequences of same time. Compared with normal controls, ReHo values of bilateral thalami, right insula and right middle temporal gyrus increased and both precentral gyri decreased in the IEM group; ReHo values of bilateral thalami and the right middle temporal gyrus increased; ReHo values of both anterior cingulate cortex, precentral gyri and putamen decreased in the FEM group. Compared with control group, ReHo values of left olfactory cortex, right hippocampus, parahippocampal gyrus, suboccipital gyrus and precuneus increased, both precentral gyri, precuneus, putamen and anterior cingulate cortex decreased in the CM group. Compared with IEM group, ReHo values of both putamen, left middle frontal gyrus, right superior frontal gyrus increased, and the left precuneus decreased in the FEM group. Compared with FEM group, ReHo values of left olfactory and left precuneus increased, and the right superior frontal gyrus, insula, middle temporal gyrus, thalami, both superior temporal gyri decreased in the CM group. In the IEM group, the changes of function focus on the regions associated with coding, conduction and regulation of pain signals. In the FEM group, functional alterations mainly concentrated on the regions associated with pain regulation and emotion cognition. In the CM group, the changes focus on the regions related to spatial attention and cognition, affective disorders and pain feedback, which may be associated with migraine production, development and chronification.

Advanced Imaging in the Evaluation of Migraine Headaches

The use of advanced imaging in routine diagnostic practice appears to provide only limited value in patients with migraine who have not experienced recent changes in headache characteristics or symptoms. However, advanced imaging may have potential for studying the biological manifestations and pathophysiology of migraine headaches. Migraine with aura appears to have characteristic spatiotemporal changes in structural anatomy, function, hemodynamics, metabolism, and biochemistry, whereas migraine without aura produces more subtle and complex changes. Large, controlled, multicenter imaging-based observational trials are needed to confirm the anecdotal evidence in the literature and test the scientific hypotheses thought to underscore migraine pathophysiology.

Potential Protective Mechanisms of Ketone Bodies in Migraine Prevention

An increasing amount of evidence suggests that migraines are a response to a cerebral energy deficiency or oxidative stress levels that exceed antioxidant capacity. The ketogenic diet (KD), a diet mimicking fasting that leads to the elevation of ketone bodies (KBs), is a therapeutic intervention targeting cerebral metabolism that has recently shown great promise in the prevention of migraines. KBs are an alternative fuel source for the brain, and are thus likely able to circumvent some of the abnormalities in glucose metabolism and transport found in migraines. Recent research has shown that KBs-D-β-hydroxybutyrate in particular-are more than metabolites. As signalling molecules, they have the potential to positively influence other pathways commonly believed to be part of migraine pathophysiology, namely: mitochondrial functioning, oxidative stress, cerebral excitability, inflammation and the gut microbiome. This review will describe the mechanisms by which the presence of KBs, D-BHB in particular, could influence those migraine pathophysiological mechanisms. To this end, common abnormalities in migraines are summarised with a particular focus on clinical data, including phenotypic, biochemical, genetic and therapeutic studies. Experimental animal data will be discussed to elaborate on the potential therapeutic mechanisms of elevated KBs in migraine pathophysiology, with a particular focus on the actions of D-BHB. In complex diseases such as migraines, a therapy that can target multiple possible pathogenic pathways seems advantageous. Further research is needed to establish whether the absence/restriction of dietary carbohydrates, the presence of KBs, or both, are of primary importance for the migraine protective effects of the KD.

Imaging of neuroinflammation in migraine with aura: A [11C]PBR28 PET/MRI study

OBJECTIVE

To determine if migraine with aura is associated with neuroinflammation, which has been suggested by preclinical models of cortical spreading depression (CSD) as well as imaging of human pain conditions.

METHODS

Thirteen migraineurs with aura and 16 healthy controls received integrated PET/MRI brain scans with [¹¹C]PBR28, a radioligand that binds to the 18 kDa translocator protein, a marker of glial activation. Standardized uptake value ratio (SUVR) was compared between groups, and regressed against clinical variables, using region of interest and whole-brain voxelwise analyses.

RESULTS

Compared to healthy controls, migraineurs demonstrated SUVR elevations in nociceptive processing areas (e.g., thalamus and primary/secondary somatosensory and insular cortices) as well as in areas previously shown to be involved in CSD generation (visual cortex). SUVR levels in frontoinsular cortex, primary/secondary somatosensory cortices, and basal ganglia were correlated with frequency of migraine attacks.

CONCLUSIONS

These findings demonstrate that migraine with aura is associated with neuroimmune activation/neuroinflammation, and support a possible link between CSD and glial activation, previously observed in animals.

Age related metabolic modifications in the migraine brain

Purpose

The aim of this study was to evaluate the possibility that migraine patients exhibit specific age-related metabolic changes in the brain, which occur regardless of disease duration or the frequency of attacks.

Methods

We analysed the relation between brain glucose (18F-fluorodeoxyglucose) uptake and age in healthy volunteers (n = 20) and episodic migraine patients (n = 19). In the latter, we additionally compared the correlation between 18F-fluorodeoxyglucose uptake and disease duration and monthly migraine days.

Results

In contrast to controls, in migraine patients advancing age was positively correlated to increased metabolism in the brainstem (especially the posterior pons), hippocampus, fusiform gyrus and parahippocampus. Conversely, no significant correlations between cerebral metabolism and disease duration or migraine days were observed.

Conclusions

Findings of this cross-sectional study show that episodic migraine patients exhibit specific metabolic brain modifications while ageing. As such, age is correlated with metabolic changes in key regions of the brain previously associated with migraine's pathophysiology to a better extent than disease duration or the number of monthly migraine days. More than the repeated headache attacks, the continuous interaction with the environment seemingly models the brain of migraine sufferers in an adaptive manner. A positive control (e.g. chronic pain) is missing in this study and therefore findings cannot be proven to be migraine-specific.

Evidence of an increased neuronal activation-to-resting glucose uptake ratio in the visual cortex of migraine patients: a study comparing 18FDG-PET and visual evoked potentials

BACKGROUND

Migraine attacks might be triggered by a disruption of cerebral homeostasis. During the interictal period migraine patients are characterized by abnormal sensory information processing, but this functional abnormality may not be sufficient to disrupt the physiological equilibrium of the cortex unless it is accompanied by additional pathological mechanisms, like a reduction in energetic reserves. The aim of this study was to compare resting cerebral glucose uptake (using positron emission tomography (18fluorodeoxyglucose-PET)), and visual cortex activation (using visual evoked potentials (VEP)), between episodic migraine without aura patients in the interictal period and healthy volunteers.

METHODS

Twenty episodic migraine without aura patients and twenty healthy volunteers were studied. 18FDG-PET and VEP recordings were performed on separate days. The overall glucose uptake in the visual cortex-to-VEP response ratio was calculated and compared between the groups. Additionally, PET scan comparisons adding area under the VEP curve as a covariate were performed. For case-wise analysis, eigenvalues from a specific region exhibiting significantly different FDG-PET signal in the visual cortex were extracted. Standardized glucose uptake values from this region and VEP values from each subject were then coupled and compared between the groups.

RESULTS

The mean area under the curve of VEP was greater in migraine patients compared to healthy controls. In the same line, patients had an increased neuronal activation-to-resting glucose uptake ratio in the visual cortex. Statistical parametric mapping analysis revealed that cortical FDG-PET signal in relation to VEP area under the curve was significantly reduced in migraineurs in a cluster extending throughout the left visual cortex, from Brodmann's areas 19 and 18 to area 7. Within this region, case-wise analyses showed that a visual neuronal activation exceeding glucose uptake was present in 90% of migraine patients, but in only 15% of healthy volunteers.

CONCLUSION

This study identifies an area of increased neuronal activation-to-resting glucose uptake ratio in the visual cortex of migraine patients between attacks. Such observation supports the concept that an activity-induced rupture of cerebral metabolic homeostasis may be a cornerstone of migraine pathophysiology. This article has been selected as the winner of the 2018 Enrico Greppi Award. The Enrico Greppi Award is made to an unpublished paper dealing with clinical, epidemiological, genetic, pathophysiological or therapeutic aspects of headache. Italian Society for the Study of Headaches (SISC) sponsors this award, and the award is supported through an educational grant from Teva Neuroscience. This article did not undergo the standard peer review process for The Journal of Headache and Pain. The members of the 2018 Enrico Greppi Award Selection Committee were: Francesco Pierelli, Paolo Martelletti, Lyn Griffiths, Simona Sacco, Andreas Straube and Cenk Ayata.

Sex-related influences in migraine

Migraine is a common neurological disorder with significantly higher incidence and prevalence in women than men. The presentation of the disease in women is modulated by changes in sex hormones from adolescence to pregnancy and menopause. Yet, the effect of sex influences has often been neglected in both basic and clinical and in clinical management of the disease. In this review, evidence from epidemiological, clinical, animal, and neuroimaging studies on the significance of the sex-related influences in migraine is presented, and the unmet needs in each area are discussed. © 2016 Wiley Periodicals, Inc.

Physiopathology of Migraine: What Have We Learned from Functional Imaging?

PURPOSE OF REVIEW

This review aims to provide an overview of the most recent and significant functional neuroimaging studies which have clarified the complex mechanisms underlying migraine pathophysiology.

RECENT FINDINGS

The recent data allow us to overcome the concept of a migraine generator suggesting that functional networks abnormalities may lead to changes in different brain area activities and consequent reduced migraine thresholds susceptibility, likely associated with higher migraine severity and burden. Although functional magnetic resonance imaging studies have allowed recognition of several migraine mechanisms, its pathophysiology is not completely understood and is still a matter of research. Nevertheless, in recent years, functional magnetic resonance imaging studies have allowed us to implement our knowledge of migraine pathophysiology. The pivotal role of both the brainstem and the hippocampus in the first phase of a migraine attack, the involvement of limbic pathway in the constitution of a migrainous pain network, the disrupted functional connectivity in cognitive brain networks, as well as the abnormal function of the visual network in patients with migraine with aura are the main milestones in migraine imaging achieved through functional imaging advances. We believe that further studies based on combined functional and structural techniques and the investigation of the different phases of migraine cycle may represent an efficient methodological approach for comprehensively looking into the migrainous brain secrets.

Cerebral metabolism before and after external trigeminal nerve stimulation in episodic migraine

Background and aim A recent sham-controlled trial showed that external trigeminal nerve stimulation (eTNS) is effective in episodic migraine (MO) prevention. However, its mechanism of action remains unknown. We performed 18-fluorodeoxyglucose positron emission tomography (FDG-PET) to evaluate brain metabolic changes before and after eTNS in episodic migraineurs. Methods Twenty-eight individuals were recruited: 14 with MO and 20 healthy volunteers (HVs). HVs underwent a single FDG-PET, whereas patients were scanned at baseline, directly after a first prolonged session of eTNS (Cefaly®) and after three months of treatment (uncontrolled study). Results The frequency of migraine attacks significantly decreased in compliant patients ( N = 10). Baseline FDG-PET revealed a significant hypometabolism in fronto-temporal areas, especially in the orbitofrontal (OFC) and rostral anterior cingulate cortices (rACC) in MO patients. This hypometabolism was reduced after three months of eTNS treatment. Conclusion Our study shows that metabolic activity of OFC and rACC, which are pivotal areas in central pain and behaviour control, is decreased in migraine. This hypometabolism is reduced after three months of eTNS. eTNS might thus exert its beneficial effects via slow neuromodulation of central pain-controlling areas, a mechanism also previously reported in chronic migraine and cluster headache after percutaneous occipital nerve stimulation. However, this finding needs to be confirmed by further studies using a sham condition.

Resting state connectivity between default mode network and insula encodes acute migraine headache

Background

Previous functional MRI studies have revealed that ongoing clinical pain in different chronic pain syndromes is directly correlated to the connectivity strength of the resting default mode network (DMN) with the insula. Here, we investigated seed-based resting state DMN-insula connectivity during acute migraine headaches.

Methods

Thirteen migraine without aura patients (MI) underwent 3 T MRI scans during the initial six hours of a spontaneous migraine attack, and were compared to a group of 19 healthy volunteers (HV). We evaluated headache intensity with a visual analogue scale and collected seed-based MRI resting state data in the four core regions of the DMN: Medial prefrontal cortex (MPFC), posterior cingulate cortex (PCC), and left and right inferior parietal lobules (IPLs), as well as in bilateral insula.

Results

Compared to HV, MI patients showed stronger functional connectivity between MPFC and PCC, and between MPFC and bilateral insula. During migraine attacks, the strength of MPFC-to-insula connectivity was negatively correlated with pain intensity.

Conclusion

We show that greater subjective intensity of pain during a migraine attack is associated with proportionally weaker DMN-insula connectivity. This is at variance with other chronic extra-cephalic pain disorders where the opposite was found, and may thus be a hallmark of acute migraine head pain.

In child and adult migraineurs the somatosensory cortex stands out … again: An arterial spin labeling investigation

Over the past decade, human brain imaging investigations have reported altered regional cerebral blood flow (rCBF) in the interictal phase of migraine. However, there have been conflicting findings across different investigations, making the use of perfusion imaging in migraine pathophysiology more difficult to define. These inconsistencies may reflect technical constraints with traditional perfusion imaging methods such as single-photon emission computed tomography and positron emission tomography. Comparatively, pseudocontinuous arterial spin labeling (pCASL) is a recently developed magnetic resonance imaging technique that is noninvasive and offers superior spatial resolution and increased sensitivity. Using pCASL, we have previously shown increased rCBF within the primary somatosensory cortex (S1) in adult migraineurs, where blood flow was positively associated with migraine frequency. Whether these observations are present in pediatric and young adult populations remains unknown. This is an important question given the age-related variants of migraine prevalence, symptomology, and treatments. In this investigation, we used pCASL to quantitatively compare and contrast blood flow within S1 in pediatric and young adult migraineurs as compared with healthy controls. In migraine patients, we found significant resting rCBF increases within bilateral S1 as compared with healthy controls. Furthermore, within the right S1, we report a positive correlation between blood flow value with migraine attack frequency and cutaneous allodynia symptom profile. Our results reveal that pediatric and young adult migraineurs exhibit analogous rCBF changes with adult migraineurs, further supporting the possibility that these alterations within S1 are a consequence of repeated migraine attacks. Hum Brain Mapp 38:4078-4087, 2017. © 2017 Wiley Periodicals, Inc.

Pathophysiology of Migraine: A Disorder of Sensory Processing

Plaguing humans for more than two millennia, manifest on every continent studied, and with more than one billion patients having an attack in any year, migraine stands as the sixth most common cause of disability on the planet. The pathophysiology of migraine has emerged from a historical consideration of the "humors" through mid-20th century distraction of the now defunct Vascular Theory to a clear place as a neurological disorder. It could be said there are three questions: why, how, and when? Why: migraine is largely accepted to be an inherited tendency for the brain to lose control of its inputs. How: the now classical trigeminal durovascular afferent pathway has been explored in laboratory and clinic; interrogated with immunohistochemistry to functional brain imaging to offer a roadmap of the attack. When: migraine attacks emerge due to a disorder of brain sensory processing that itself likely cycles, influenced by genetics and the environment. In the first, premonitory, phase that precedes headache, brain stem and diencephalic systems modulating afferent signals, light-photophobia or sound-phonophobia, begin to dysfunction and eventually to evolve to the pain phase and with time the resolution or postdromal phase. Understanding the biology of migraine through careful bench-based research has led to major classes of therapeutics being identified: triptans, serotonin 5-HT1B/1D receptor agonists; gepants, calcitonin gene-related peptide (CGRP) receptor antagonists; ditans, 5-HT1F receptor agonists, CGRP mechanisms monoclonal antibodies; and glurants, mGlu5 modulators; with the promise of more to come. Investment in understanding migraine has been very successful and leaves us at a new dawn, able to transform its impact on a global scale, as well as understand fundamental aspects of human biology.

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.

Altered functional connectivity architecture of the brain in medication overuse headache using resting state fMRI

Background

Functional connectivity density (FCD) could identify the abnormal intrinsic and spontaneous activity over the whole brain, and a seed-based resting-state functional connectivity (RSFC) could further reveal the altered functional network with the identified brain regions. This may be an effective assessment strategy for headache research. This study is to investigate the RSFC architecture changes of the brain in the patients with medication overuse headache (MOH) using FCD and RSFC methods.

Methods

3D structure images and resting-state functional MRI data were obtained from 37 MOH patients, 18 episodic migraine (EM) patients and 32 normal controls (NCs). FCD was calculated to detect the brain regions with abnormal functional activity over the whole brain, and the seed-based RSFC was performed to explore the functional network changes in MOH and EM.

Results

The decreased FCD located in right parahippocampal gyrus, and the increased FCD located in left inferior parietal gyrus and right supramarginal gyrus in MOH compared with NC, and in right caudate and left insula in MOH compared with EM. RSFC revealed that decreased functional connectivity of the brain regions with decreased FCD anchored in the right dorsal-lateral prefrontal cortex, right frontopolar cortex in MOH, and in left temporopolar cortex and bilateral visual cortices in EM compared with NC, and in frontal-temporal-parietal pattern in MOH compared with EM.

Conclusions

These results provided evidence that MOH and EM suffered from altered intrinsic functional connectivity architecture, and the current study presented a new perspective for understanding the neuromechanism of MOH and EM pathogenesis.

The sensorimotor network dysfunction in migraineurs without aura: a resting-state fMRI study

Migraine is a common recurrent neurological disorder combining nausea, vomiting, and hypersensitivities to visual, auditory, olfactory and somatosensory stimuli. However, the dysfunction of the sensorimotor network in migraineurs has not been well clarified. In the present study, we evaluated the dysfunction of the sensorimotor network in 30 migraineurs without aura and in 31 controls by combining regional homogeneity (ReHo), amplitudes of low-frequency fluctuation (ALFF) and degree centrality (DC) analysis methods based on resting-state fMRI. A seed-based functional connectivity (FC) analysis was used to investigate whether the dysfunctional areas within the sensorimotor network exhibited abnormal FC with other brain areas. Compared to the controls, the migraineurs without aura exhibited significantly smaller ReHo, ALFF and DC values in the primary somatosensory cortex (S1) and right premotor cortex (PMC). The migraineurs showed weaker FC between the S1 and brain areas within the pain intensity and spatial discrimination pathways and trigemino-thalamo-cortical nociceptive pathway. We proposed that the dysfunction of the S1 and PMC and the decreased FC between the S1 and brain areas in migraineurs without aura may disrupt the discrimination of sensory features of pain and affect nociception pathways, and would be involved in the dysfunctional mechanism in migraine.

Increased default mode network connectivity and increased regional homogeneity in migraineurs without aura

BACKGROUND

The precuneus/posterior cingulate cortex, which has been associated with pain sensitivity, plays a pivotal role in the default mode network. However, information regarding migraine-related alterations in resting-state brain functional connectivity in the default mode network and in local regional spontaneous neuronal activity is not adequate.

METHODS

This study used functional magnetic resonance imaging to acquire resting-state scans in 22 migraineurs without aura and in 22 healthy matched controls. Independent component analysis, a data-driven method, was used to calculate the resting-state functional connectivity of the default mode network in the patient and healthy control groups. Regional homogeneity (ReHo) was used to analyse the local features of spontaneous resting-state brain activity in the migraineurs without aura.

RESULTS

Compared with the healthy controls, migraineurs without aura showed increased functional connectivity in the left precuneus/posterior cingulate cortex within the default mode network and significant increase in ReHo values in the bilateral precuneus/posterior cingulate cortex, left pons and trigeminal nerve entry zone. In addition, functional connectivity was decreased between the areas with abnormal ReHo (using the peaks in the precuneus/posterior cingulate cortex) and other brain areas.

CONCLUSIONS

The abnormalities in the precuneus/posterior cingulate cortex suggest that migraineurs without aura may exhibit information transfer and multimodal integration dysfunction and that pain sensitivity and pian processing may also be affected.

Altered functional connectivity of the marginal division in migraine: a resting-state fMRI study

BACKGROUND

The marginal division of neostriatum (MrD) is a flat, pan-shaped zone between the neostriatum and the globus pallidus, and previous documents demonstrated that it was involved in the modulation of pain. The aim of this study is to investigate the roles of the MrD of the human brain in the chronicization migraine using resting state functional magnetic resonance imaging (rs-fMRI).

METHODS

Conventional MRI, 3D structure images, and rs-fMRI were performed in 18 patients with episodic migraines (EM), 16 patients with chronic migraine (CM), 44 patients with medication overuse headache plus chronic migraine (MOH + CM), and 32 normal controls (NC). MrD was defined using manual delineation on structural images, and was selected as the seed to calculate the functional connectivity (FC).

RESULTS

Compared with the NC group, the decreased FC of MrD was observed in the EM and CM groups, and increased FC of MrD was demonstrated in all patient groups. Compared with the EM group, the decreased FC of MrD was revealed in the CM and MOH + CM groups, and the increased FC occurred only in the CM group. Increased FC of MrD alone was observed in the MOH + CM group compared with that in the CM group.

CONCLUSION

This study confirmed the double neuromodulation network of MrD in pain modulation and migraine chronicization; however, the mechanism requires further investigation.

Different mean thickness implicates involvement of the cortex in migraine

The results of neuroimaging studies on migraines have shown that the functions and functional connectivity networks of some brain regions are altered in migraine patients, and different brain structure volumes have also been observed in recent years. However, it is still not known whether the mean thickness of the cortex is different in migraine patients.A total of 48 migraine without aura (MWoA) patients in interictal phase and 48 healthy controls were enrolled in this study. All subjects received neurological and magnetic resonance imaging (MRI) examinations. Automatic segmentation processing of high-resolution MRI structure images was performed using FreeSurfer software.The mean cortical thickness of many brain regions in the frontal lobe, temporal lobe, occipital lobe, parietal lobe, and insula in the migraine patient group was significantly decreased compared with that in the healthy control group. The mean cortical thickness of the insula anterior was positively correlated with the duration of the disease course, while the mean cortical thickness of insula superior and insula inferior was negatively correlated with the duration of the disease course.The results showed that MWoA results from a complex interactive reaction involving many brain regions and many brain network systems together. However, it is still not clear whether the difference in the brain structure of migraine patients is the result or the cause of headache, which is a topic that must be better elucidated. Therefore, longitudinal neuroimaging studies on migraine patients with large samples sizes should be performed using more advanced neuroimaging techniques.