Differences in Cortical Morphology in People With and Without Migraine: A Registry for Migraine (REFORM) MRI Study

BACKGROUND AND OBJECTIVES

Structural imaging can offer insights into the cortical morphometry of migraine, which might reflect adaptations to recurring nociceptive messaging. This study compares cortical morphometry between a large sample of people with migraine and healthy controls, as well as across migraine subtypes.

METHODS

Adult participants with migraine and age-matched and sex-matched healthy controls attended a single MRI session with magnetization-prepared rapid acquisition gradient echo and fluid-attenuated inversion recovery sequences at 3T. Cortical surface area, thickness, and volume were compared between participants with migraine (including subgroups) and healthy controls across the whole cortex within FreeSurfer and reported according to the Desikan-Killiany atlas. The analysis used cluster-determining thresholds of p < 0.0001 and cluster-wise thresholds of p < 0.05, adjusted for age, sex, and total intracranial volume.

RESULTS

A total of 296 participants with migraine (mean age 41.6 years ± 12.4 SD, 261 women) and 155 healthy controls (mean age 41.1 years ± 11.7 SD, 133 women) were included. Among the participants with migraine, 180 (63.5%) had chronic migraine, 103 (34.8%) had migraine with aura, and 88 (29.7%) experienced a migraine headache during the scan. The total cohort of participants with migraine had reduced cortical surface area in the left insula, compared with controls (p < 0.0001). Furthermore, participants with chronic migraine (n = 180) exhibited reduced surface area in the left insula (p < 0.0001) and increased surface area in the right caudal anterior cingulate cortex (p < 0.0001), compared with controls. We found no differences specific to participants with aura or ongoing migraine headache. Post hoc tests revealed a positive correlation between monthly headache days and surface area within the identified anterior cingulate cluster (p = 0.014).

DISCUSSION

The identified cortical changes in migraine were limited to specific pain processing regions, including the insula and caudal anterior cingulate gyrus, and were most notable in participants with chronic migraine. These findings suggest persistent cortical changes associated with migraine.

TRIAL REGISTRATION INFORMATION

The REFORM study (clinicaltrials.gov identifier: NCT04674020).

Potential of focal cortical dysplasia in migraine pathogenesis

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

Grey matter structure within the visual networks in migraine with aura: multivariate and univariate analyses

BACKGROUND

The visual cortex is involved in the generation of migraine aura. Voxel-based multivariate analyses applied to this region may provide complementary information about aura mechanisms relative to the commonly used mass-univariate analyses.

METHODS

Structural images constrained within the functional resting-state visual networks were obtained in migraine patients with (n = 50) and without (n = 50) visual aura and healthy controls (n = 50). The masked images entered a multivariate analysis in which Gaussian process classification was used to generate pairwise models. Generalizability was assessed by five-fold cross-validation and non-parametric permutation tests were used to estimate significance levels. A univariate voxel-based morphometry analysis was also performed.

RESULTS

A multivariate pattern of grey matter voxels within the ventral medial visual network contained significant information related to the diagnosis of migraine with visual aura (aura vs. healthy controls: classification accuracy = 78%, p < 0.001; area under the curve = 0.84, p < 0.001; migraine with aura vs. without aura: classification accuracy = 71%, p < 0.001; area under the curve = 0.73, p < 0.003). Furthermore, patients with visual aura exhibited increased grey matter volume in the medial occipital cortex compared to the two other groups.

CONCLUSIONS

Migraine with visual aura is characterized by multivariate and univariate patterns of grey matter changes within the medial occipital cortex that have discriminative power and may reflect pathological mechanisms.

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.

Structural brain morphology in young adult women who have been choked/strangled during sex: A whole-brain surface morphometry study

INTRODUCTION

Being choked/strangled during partnered sex is an emerging sexual behavior, particularly prevalent among young adult women. Using a multiparameter morphometric imaging approach, we aimed to characterize neuroanatomical differences between young adult women (18-30 years old) who were exposed to frequent sexual choking and their choking naïve controls.

METHODS

This cross-sectional study consisted of two groups (choking [≥4 times in the past 30 days] vs. choking-naïve group). Participants who reported being choked four or more times during sex in the past 30 days were enrolled in the choking group, whereas those without were assigned to the choking naïve group. High-resolution anatomical magnetic resonance imaging (MRI) data were analyzed using both volumetric features (cortical thickness) and geometric features (fractal dimensionality, gyrification, sulcal depth).

RESULTS

Forty-one participants (choking n = 20; choking-naïve n = 21) contributed to the final analysis. The choking group showed significantly increased cortical thickness across multiple regions (e.g., fusiform, lateral occipital, lingual gyri) compared to the choking-naïve group. Widespread reductions of the gyrification were observed in the choking group as opposed to the choking-naïve group. However, there was no group difference in sulcal depth. The fractal dimensionality showed bi-directional results, where the choking group exhibited increased dimensionality in areas including the postcentral gyrus, insula, and fusiform, whereas decreased dimensionality was observed in the bilateral superior frontal gyrus and pericalcarine cortex.

CONCLUSION

These data in cortical morphology suggest that sexual choking events may be associated with neuroanatomical alteration. A longitudinal study with multimodal assessment is needed to better understand the temporal ordering of sexual choking and neurological outcomes.

Brain structure and cortical activity changes of new daily persistent headache: multimodal evidence from MEG/sMRI

BACKGROUND

New daily persistent headache (NDPH) is a rare but debilitating primary headache disorder that poses a significant burden on individuals and society. Despite its clinical importance, the underlying pathophysiological mechanisms of NDPH remain unclear. In this study, we aimed to investigate the brain structural changes and neural activity patterns in patients with NDPH using multimodal brain imaging analysis of structural magnetic resonance imaging (sMRI) combined with magnetoencephalography (MEG).

METHODS

Twenty-eight patients with NDPH and 37 healthy controls (HCs) were recruited for this study, and their structural and resting-state data were collected by 3.0 Tesla MRI and MEG. We analyzed the brain morphology using voxel-based morphometry and source-based morphometry. In each brain region, MEG sensor signals from 1 to 200 Hz were analyzed using an adapted version of Welch's method. MEG source localization was conducted using the dynamic statistical parametric mapping, and the difference of source distribution between patients with NDPH and HCs was examined.

RESULTS

Our results revealed significant differences in the regional grey matter volume, cortical thickness, and cortical surface area between the two groups. Specifically, compared with HCs, patients with NDPH showed a significant decrease in cortical thickness of the left rostral cortex in the middle frontal gyrus, decreased cortical surface area of the left fusiform gyrus, decreased grey matter volume of the left superior frontal gyrus and the left middle frontal gyrus, and increased grey matter volume of the left calcarine. Furthermore, the power of the whole brain, bilateral frontal lobes, and right temporal lobe in the NDPH group were higher than that in HCs in the ripple frequency band (80-200 Hz). Functional and structural analysis suggested that there were structural changes and abnormal high frequency cortical activity in both frontal and temporal lobes in patients with NDPH.

CONCLUSION

Our findings indicated that patients with NDPH have abnormalities in brain morphology, such as cortical area, cortical thickness, and grey matter volume, accompanied by abnormal cortical neural activity. Brain structural changes in the frontotemporal cortex and abnormalities in cortical ripple activity may be involved in the pathogenesis of NDPH.

Mapping the aberrant brain functional connectivity in new daily persistent headache: a resting-state functional magnetic resonance imaging study

BACKGROUND AND PURPOSE

The pathogenesis of new daily persistent headache (NDPH) is not fully understood. We aim to map aberrant functional connectivity (FC) in patients with NDPH using resting-state functional magnetic resonance imaging (MRI).

METHODS

Brain structural and functional MRI data were acquired from 29 patients with NDPH and 37 well-matched healthy controls (HCs) in this cross-sectional study. Region of interest (ROI) based analysis was used to compare FC between patients and HCs, with 116 brain regions in the automated anatomical labeling (AAL) atlas were defined as seeds. The correlations between aberrant FC and patients' clinical characteristics, and neuropsychological evaluation were also investigated.

RESULTS

Compared with HCs, patients with NDPH showed increased FC in the left inferior occipital gyrus, right thalamus and decreased FC in right lingual gyrus, left superior occipital gyrus, right middle occipital gyrus, left inferior occipital gyrus, right inferior occipital gyrus, right fusiform gyrus, left postcentral gyrus, right postcentral gyrus, right thalamus and right superior temporal gyrus. There were no correlation between FC of these brain regions and clinical characteristics, neuropsychological evaluation after Bonferroni correction (p > 0.05/266).

CONCLUSIONS

Patients with NDPH showed aberrant FC in multiple brain regions involved in perception and regulation of emotion and pain.

TRIAL REGISTRATION

ClinicalTrials.gov Identifier: NCT05334927.

A systematic review and meta-analysis of voxel-based morphometric studies of migraine

OBJECTIVES

To comprehensively summarize and meta-analyze the concurrence across voxel-based morphometric (VBM) neuroimaging studies of migraine.

METHODS

Neuroimaging studies published from origin to August 1, 2021 were searched in six databases including PubMed, Web of Science, Excerpta Medica Database (EMBASE), China National Knowledge Infrastructure (CNKI), Wanfang Database, and Chongqing VIP. Study selection, quality assessment, and data extraction were conducted by two independent researchers. Anisotropic effect size-signed differential mapping (AES-SDM) and activation likelihood estimation (ALE) were used to perform the meta-analysis of available studies reporting whole-brain gray matter (GM) structural data in migraine patients. Clinical variables correlation analysis and migraine subgroup analysis were also conducted.

RESULTS

40 articles were included after the strict screening, containing 1616 migraine patients and 1681 matched healthy subjects (HS) in total. Using the method of AES-SDM, migraine patients showed GM increase in the bilateral amygdala, the bilateral parahippocampus, the bilateral temporal poles, the bilateral superior temporal gyri, the left hippocampus, the right superior frontal gyrus, and the left middle temporal gyrus, as well as GM decrease in the left insula, the bilateral cerebellum (hemispheric lobule IX), the right dorsal medulla, the bilateral rolandic operculum, the right middle frontal gyrus, and the right inferior parietal gyrus. Using the method of ALE, migraine patients showed GM increase in the left parahippocampus and GM decrease in the left insula. The results of correlation analysis showed that many of these brain regions were associated with migraine headache frequency and migraine disease duration. Migraine patients in different subtypes (such as migraine without aura (MwoA), migraine with aura (MwA), episodic migraine (EM), chronic migraine (CM), vestibular migraine (VM), etc.), and in different periods (in the ictal and interictal periods) presented not entirely consistent GM alterations.

CONCLUSION

Migraine patients have GM alterations in multiple brain regions associated with sensation, affection, cognition, and descending modulation aspects of pain. These changes might be a consequence of repeated migraine attacks. Further studies are required to determine how these GM changes can be used to diagnose, monitor disease progression, or exploit potential therapeutic interventions for migraine patients.

Pathophysiology of migraine aura

Migraine aura occurs in about a third of patients with migraine and consists of a group of transient focal neurological symptoms that appear from 5 to 60min and then resolve prior to or in the early phase of a migraine headache attack. Migraine auras may consist of visual, language, unilateral sensory, or motor symptoms. There has been considerable debate as to the origins of the migrainous aura. Investigations during physiologically induced visual auras suggest that the phenomenon of cortical spreading depression or its human equivalent underpins the migraine aura. Single gene defects have been linked to relatively rare forms of the motor subtypes of aura known as familial hemiplegic migraine (FHM). These include CACNA1A (FHM1), ATP1A2 (FHM2), and SCN1A (FHM3). In the familial hemiplegic forms of migraine, the more typical forms of aura are almost always also present. Despite ample epidemiological evidence of increased heritability of migraine with aura compared to migraine without aura, identification of the specific variants driving susceptibility to the more common forms of aura has been problematic thus far. In the first genome-wide association study (GWAS) that focused migraine with aura, a single SNP rs835740 reached genome-wide significance. Unfortunately, the SNP did show statistical significance in a later meta-analysis which included GWAS data from subsequent studies. Here, we review the clinical features, pathophysiological theories, and currently available potential evidence for the genetic basis of migraine aura.

What imaging has revealed about migraine and chronic migraine

Although migraine pathophysiology is not yet entirely understood, it is now established that migraine should be viewed as a complex neurological disease, which involves the interplay of different brain networks and the release of signaling molecules, instead of a pure vascular disorder. The field of migraine research has also progressed significantly due to the advancement of brain imaging techniques. Numerous studies have investigated the relation between migraine pathophysiology and cerebral hemodynamic changes, showing that vascular changes are neither necessary nor sufficient to cause the migraine pain. Abnormal function and structure of key cortical, subcortical, and brainstem regions involved in multisensory, including pain, processing have been shown to occur in migraine patients during both an acute attack and the interictal phase. Whether brain imaging alterations represent a predisposing trait or are the consequence of the recurrence of headache attacks is still a matter of debate. It is highly likely that brain functional and structural alterations observed in migraine patients derive from the interaction between predisposing brain traits and experience-dependent responses. Neuroimaging studies have also enriched our knowledge of the mechanisms responsible for migraine chronification and have shed light on the mechanisms of actions of acute and preventive migraine treatments.

Evaluating migraine with typical aura with neuroimaging

Objective

To provide an up-to-date narrative literature review of imaging in migraine with typical aura, as a means to understand better migraine subtypes and aura biology.

Background

Characterizing subtypes of migraine with typical aura and appreciating possible biological differences between migraine with and without aura, are important to understanding the neurobiology of aura and trying to advance personalized therapeutics in this area through imaging biomarkers. One means of doing this over recent years has been the use of increasingly advanced neuroimaging techniques.

Methods

We conducted a literature review of neuroimaging studies in migraine with aura, using a PubMed search for terms 'imaging migraine', 'aura imaging', 'migraine with aura imaging', 'migraine functional imaging' and 'migraine structural imaging'. We collated the findings of the main studies, excluding small case reports and series with n < 6, and have summarized these and their implications for better understanding of aura mechanisms.

Results

Aura is likely mediated by widespread brain dysfunction in areas involving, but not limited to, visual cortex, somatosensory and insular cortex, and thalamus. Higher brain excitability in response to sensory stimulation and altered resting-state functional connectivity in migraine sufferers with aura could have a genetic component. Pure visual aura compared to visual aura with other sensory or speech symptoms as well, may involve different functional reorganization of brain networks and additional mitochondrial dysfunction mediating more aura symptoms.

Conclusion

There is a suggestion of at least some distinct neurobiological differences between migraine with and without aura, despite the shared phenotypic similarity in headache and other migraine-associated symptoms. It is clear from the vast majority of aura phenotypes being visual that there is a particular predisposition of the occipital cortex to aura mechanisms. Why this is the case, along with the relationships between cortical spreading depression and headache, and the reasons why aura does not consistently present in affected individuals, are all important research questions for the future.

Aberrant Modulations of Neurocognitive Network Dynamics in Migraine Comorbid With Tinnitus

Purpose

The possible relationship between migraine and tinnitus still remains elusive although migraine is often accompanied by chronic tinnitus. Several neuroimaging studies have reinforced the cognitive network abnormality in migraine and probably as well as tinnitus. The present work aims to investigate the dynamic neurocognitive network alterations of migraine comorbid with tinnitus.

Materials and Methods

Participants included migraine patients (n = 32), tinnitus patients (n = 20), migraine with tinnitus (n = 27), and healthy controls (n = 47), matched for age and gender. Resting-state functional magnetic resonance imaging (rs-fMRI) with independent component analysis (ICA), sliding window cross-correlation, and clustering state analysis was used to detect the dynamic functional network connectivity (dFNC) of each group. Correlation analyses illustrated the association between clinical symptoms and abnormal dFNC in migraine as well as tinnitus.

Results

Compared with healthy controls, migraine patients exhibited decreased cerebellar network and visual network (CN-VN) connectivity in State 2; migraine with tinnitus patients showed not only decreased CN-VN connectivity in State 2 but also decreased cerebellar network and executive control network (CN-ECN) connectivity in State 2 and increased cerebellar network and somatomotor network (SMN-VN) connectivity in State 1. The abnormal cerebellum dFNC with the executive control network (CN-ECN) was negatively correlated with headache frequency of migraine (rho = −0.776, p = 0.005).

Conclusion

Brain network characteristics of migraine with tinnitus patients may indicate different mechanisms for migraine and tinnitus. Our results demonstrated a transient pathologic state with atypical cerebellar-cortical connectivity in migraine with tinnitus patients, which might be used to identify the neuro-pathophysiological mechanisms in migraine accompanied by tinnitus.

Functional Connectivity Features of Resting-State Functional Magnetic Resonance Imaging May Distinguish Migraine From Tension-Type Headache

Background

Migraineurs often exhibited abnormalities in cognition, emotion, and resting-state functional connectivity (rsFC), whereas patients with tension-type headache (TTH) rarely exhibited these abnormalities. The aim of this study is to explore whether rsFC alterations in brain regions related to cognition and emotion could be used to distinguish patients with migraine from patients with TTH.

Methods

In this study, Montreal Cognitive Assessment (MoCA), Self-Rating Anxiety Scale (SAS), Self-Rating Depression Scale (SDS), and rsFC analyses were used to assess the cognition, anxiety, and depression of 24 healthy controls (HCs), 24 migraineurs, and 24 patients with TTH. Due to their important roles in neuropsychological functions, the bilateral amygdala and hippocampus were chosen as seed regions for rsFC analyses. We further assessed the accuracy of the potential rsFC alterations for distinguishing migraineurs from non-migraineurs (including HCs and patients with TTH) by the receiver operating characteristic (ROC) analysis. Associations between headache characteristics and rsFC features were calculated using a multi-linear regression model. This clinical trial protocol has been registered in the Chinese Clinical Trial Registry (registry number: ChiCTR1900024307, Registered: 5 July 2019-Retrospectively registered, http://www.chictr.org.cn/showproj.aspx?proj=40817).

Results

Migraineurs showed lower MoCA scores (p = 0.010) and higher SAS scores (p = 0.017) than HCs. Migraineurs also showed decreased rsFC in the bilateral calcarine/cuneus, lingual gyrus (seed: left amygdala), and bilateral calcarine/cuneus (seed: left hippocampus) in comparison to HCs and patients with TTH. These rsFC features demonstrated significant distinguishing capabilities and got a sensitivity of 82.6% and specificity of 81.8% with an area under the curve (AUC) of 0.868. rsFC alterations showed a significant correlation with headache frequency in migraineurs (p = 0.001, Pc = 0.020).

Conclusion

The rsFC of amygdala and hippocampus with occipital lobe can be used to distinguish patients with migraine from patients with TTH.

Clinical Trial Registration

[http://www.chictr.org.cn/showproj.aspx?proj=40817], identifier [ChiCTR1900024307].

MRI Study of Cerebral Cortical Thickness in Patients with Herpes Zoster and Postherpetic Neuralgia

Objective

To measure the changes in cerebral cortical thickness in patients with herpes zoster (HZ) and postherpetic neuralgia (PHN) by surface-based morphometry (SBM) and further estimate its correlation with clinical scores.

Materials and Methods

Twenty-nine HZ patients, 30 PHN patients and 30 well-matched healthy controls (HCs) were included. Magnetic resonance imaging (MRI) data from all subjects were collected and then analyzed by SBM. The changes in cortical thickness among the HZ, PHN and HC groups were analyzed by ANOVA and correlated with clinical scores.

Results

The thickness of the bilateral primary visual cortex (V1, V2) and right primary visual cortex (V3), left somatosensory cortex (L3A), right anterior cingulate gyrus and medial prefrontal cortex (RS32) increased in PHN group, and the thickness the left insular and frontal opercular cortex (LFOP4), left motor cortex (L3B), and right superior temporal visual cortex (RSTV) were decreased in the HZ and PHN groups compared to the HC group. The thickness measurements of RS32, LFOP4, and (L3B) in HZ and PHN patients were correlated with the duration of disease. In HZ and PHN patients, the Hamilton Anxiety Scale (HAMA) and Hamilton Depression Scale (HAMD) scores were significantly positively correlated.

Conclusion

Changes in cortical thickness in the areas related to sensory, motor, and cognitive/emotional changes in patients with PHN affect the neuroplasticity process of the brain, which may be the reason for the transformation of HZ into PHN and provide a possible explanation for the neuropathological mechanism of pain persistence in PHN patients.

Occipital bending in migraine with visual aura

OBJECTIVE

To analyze occipital bending (OB) frequency in patients with migraine with visual aura compared with those without aura.

BACKGROUND

A unique type of asymmetry in the human brain in which one occipital pole crosses the midline and bends over the other pole is called OB. OB frequency has been shown to be related to major psychiatric diseases. Hence, it may suggest more than an anatomical variation. Structural differences in the brain have been demonstrated but unequivocally between patients with migraine with aura and without aura. OB is newly recognized, and we aimed to evaluate its frequency among patients with migraine.

METHODS

For this retrospective cohort study, we reviewed our records from 2016 to 2021 from a database of the outpatient headache clinic of Koç University Hospital.

RESULTS

We found 84 patients with migraine who fulfilled diagnostic criteria for migraine with aura and migraine without aura and also had cranial magnetic resonance imaging. The median age of the population was 40 (IQR, 32-52). The female-to-male ratio of participants was 2:1. A quarter of the patients had visual aura. The prevalence of OB in patients with migraine in our retrospective study was 33.3% (28/84). Between our study groups, OB was significantly higher in patients with migraine with visual aura (57.1%, 12 out of 21 patients) than in those without aura (25.4%, 16 out of 63), (odds ratio 3.9 (95% confidence interval 1.4 to 11.0), p = 0.015).

CONCLUSION

OB frequency is two times higher in patients with migraine with visual aura. It may have pathophysiological implications.

Tracking tDCS induced grey matter changes in episodic migraine: a randomized controlled trial

BACKGROUND

Occipital transcranial direct current stimulation (tDCS) is an effective and safe treatment for migraine attack prevention. Structural brain alterations have been found in migraineurs in regions related to pain modulation and perception, including occipital areas. However, whether these structural alterations can be dynamically modulated through tDCS treatment is understudied.

OBJECTIVE

To track longitudinally grey matter volume changes in occipital areas in episodic migraineurs during and up to five months after occipital tDCS treatment in a single-blind, and sham-controlled study.

METHODS

24 episodic migraineurs were randomized to either receive verum or sham occipital tDCS treatment for 28 days. To investigate dynamic grey matter volume changes patients underwent structural MRI at baseline (prior to treatment), 1.5 months and 5.5 months (after completion of treatment). 31 healthy controls were scanned with the same MRI protocol. Morphometry measures assessed rate of changes over time and between groups by means of tensor-based morphometry.

RESULTS

Before treatment, migraineurs reported 5.6 monthly migraine days on average. A cross-sectional analysis revealed grey matter volume increases in the left lingual gyrus in migraineurs compared to controls. Four weeks of tDCS application led to a reduction of 1.9 migraine days/month and was paralleled by grey matter volume decreases in the left lingual gyrus in the treatment group; its extent overlapping with that seen at baseline.

CONCLUSION

This study shows that migraineurs have increased grey matter volume in the lingual gyrus, which can be modified by tDCS. Tracking structural plasticity in migraineurs provides a potential neuroimaging biomarker for treatment monitoring.

TRIAL REGISTRATION

ClinicalTrials.gov , NCT03237754 . Registered 03 August 2017 - retrospectively registered, https://clinicaltrials.gov/ct2/show/NCT03237754 .

Structural aberrations of the brain associated with migraine: A narrative review

OBJECTIVE

To summarize major results from imaging studies investigating brain structure in migraine.

BACKGROUND

Neuroimaging studies, using several different imaging and analysis techniques, have demonstrated aberrations in brain structure associated with migraine. This narrative review summarizes key imaging findings and relates imaging findings with clinical features of migraine.

METHODS

We searched PubMed for English language articles using the key words "neuroimaging" AND/OR "MRI" combined with "migraine" through August 20, 2020. The titles and abstracts of resulting articles were reviewed for their possible inclusion in this manuscript, followed by examination of the full texts and reference lists of relevant articles.

RESULTS

Migraine is associated with structural brain aberrations within regions that participate in pain processing, the processing of other sensory stimuli, multisensory integration, and in white matter fiber tracts. Furthermore, migraine is associated with magnetic resonance imaging T2/fluid-attenuated inversion recovery white matter hyperintensities. Some structural aberrations are correlated with the severity and clinical features of migraine, whereas others are not. These findings suggest that some structural abnormalities are associated with or amplified by recurrent migraine attacks, whereas others are intrinsic to the migraine brain.

CONCLUSIONS

Migraine is associated with aberrant brain structure. Structural neuroimaging studies contribute to understanding migraine pathophysiology and identification of brain regions associated with migraine and its individual symptoms. Additional work is needed to determine the extent to which structural aberrations are a result of recurrent migraine attacks, and perhaps reversible with effective treatment or migraine resolution, versus being intrinsic traits of the migraine brain.

Narrative review of neuroimaging in migraine with aura

OBJECTIVE

To improve the understanding of the role and utility of various neuroimaging modalities (clinical and research) for the evaluation of migraine aura (MA) and hemiplegic migraine during the ictal and interictal phases.

BACKGROUND

MA is defined by reversible neurologic symptoms and is considered a manifestation of a primary condition. As such, most patients with MA do not require imaging. However, if there are atypical features, change in symptom pattern, or it is a first-time presentation, neuroimaging may be used to evaluate for secondary conditions. Neuroimaging includes many modalities, and it is important to consider what information is being captured by these modalities (i.e., structural vs. functional). Imaging abnormalities may be noted both during (ictal) and between (interictal) MA attacks, and it is important for clinicians to be familiar with neuroimaging findings reported in migraine with aura (MWA) compared with other conditions.

METHODS

With the assistance of a medical librarian, we performed a review of the literature pertaining to MWA and neuroimaging in PubMed. Search terms included were magnetic resonance imaging, positron-emission tomography, single photon-emission computed tomography, functional magnetic resonance imaging, and migraine with aura. We hand-searched these references to inform our subsequent literature review.

RESULTS

Acute MA can be associated with several unique neuroimaging findings-reversible cortical diffusion restriction, cortical venous engorgement, and a "biphasic" transition from hypoperfusion to hyperperfusion. Imaging findings during MA tend to span more than one vascular territory. Between acute attacks, neuroimaging in people with MWA can resemble migraine without aura in terms of white matter abnormalities and "infarct-like lesions." Research imaging modalities such as volumetric analysis and functional imaging have demonstrated unique findings in migraine with aura.

CONCLUSION

Although migraine is a clinical diagnosis, understanding of neuroimaging findings in MWA can help clinicians interpret imaging findings and improve patient care.

Assessment of normalized cerebral blood flow and its connectivity with migraines without aura during interictal periods by arterial spin labeling

BACKGROUND

Migraine constitutes a global health burden, and its pathophysiology is not well-understood; research evaluating cerebral perfusion and altered blood flow between brain areas using non-invasive imaging techniques, such as arterial spin labeling, have been scarce. This study aimed to assess cerebral blood flow (CBF) and its connectivity of migraine.

METHODS

This study enrolled 40 patients with episodic migraine without aura (MwoA), as well as 42 healthy patients as control (HC). Two groups of normalized CBF and CBF connectivity were compared, and the relationship between CBF variation and clinical scale assessment was further evaluated.

RESULTS

In comparison to HC subjects, MwoA patients exhibited higher CBF in the right middle frontal orbital gyrus (ORBmid.R) and the right middle frontal gyrus, while that in Vermis_6 declined. The increased CBF of ORBmid.R was positively correlated with both the Visual Light Sensitivity Questionnaire-8 (VLSQ-8) and the monthly attack frequency score. In MwoA, significantly decreased CBF connectivity was detected between ORBmid.R and the left superior frontal gyrus, the right putamen, the right caudate, as well as the right angular gyrus. In addition, increased CBF connectivity was observed between the left calcarine cortex and ORBmid.R.

CONCLUSIONS

Our results indicate that migraine patients exhibit abnormalities in regional CBF and feature CBF connection defects at the resting state. The affected areas involve information perception, information integration, and emotional, pain and visual processing. Our findings might provide important clues for the pathophysiology of migraine.

Gray Matter Structural Alterations in Chronic and Episodic Migraine: A Morphometric Magnetic Resonance Imaging Study

OBJECTIVE

This study evaluates different parameters describing the gray matter structure to analyze differences between healthy controls, patients with episodic migraine, and patients with chronic migraine.

DESIGN

Cohort study.

SETTING

Spanish community.

SUBJECTS

Fifty-two healthy controls, 57 episodic migraine patients, and 57 chronic migraine patients were included in the study and underwent T1-weighted magnetic resonance imaging acquisition.

METHODS

Eighty-four cortical and subcortical gray matter regions were extracted, and gray matter volume, cortical curvature, thickness, and surface area values were computed (where applicable). Correlation analysis between clinical features and structural parameters was performed.

RESULTS

Statistically significant differences were found between all three groups, generally consisting of increases in cortical curvature and decreases in gray matter volume, cortical thickness, and surface area in migraineurs with respect to healthy controls. Furthermore, differences were also found between chronic and episodic migraine. Significant correlations were found between duration of migraine history and several structural parameters.

CONCLUSIONS

Migraine is associated with structural alterations in widespread gray matter regions of the brain. Moreover, the results suggest that the pattern of differences between healthy controls and episodic migraine patients is qualitatively different from that occurring between episodic and chronic migraine patients.

Migraine: disease characterisation, biomarkers, and precision medicine

Migraine is a disabling neurological disorder, diagnosis of which is based on clinical criteria. A shortcoming of these criteria is that they do not fully capture the heterogeneity of migraine, including the underlying genetic and neurobiological factors. This complexity has generated momentum for biomarker research to improve disease characterisation and identify novel drug targets. In this Series paper, we present the progress that has been made in the search for biomarkers of migraine within genetics, provocation modelling, biochemistry, and neuroimaging research. Additionally, we outline challenges and future directions for each biomarker modality. We also discuss the advances made in combining and integrating data from multiple biomarker modalities. These efforts contribute to developing precision medicine that can be applied to future patients with migraine.

Structural brain network characteristics in patients with episodic and chronic migraine

Background

Migraine is a primary headache disorder that can be classified into an episodic (EM) and a chronic form (CM). Network analysis within the graph-theoretical framework based on connectivity patterns provides an approach to observe large-scale structural integrity. We test the hypothesis that migraineurs are characterized by a segregated network.

Methods

19 healthy controls (HC), 17 EM patients and 12 CM patients were included. Cortical thickness and subcortical volumes were computed, and topology was analyzed using a graph theory analytical framework and network-based statistics. We further used support vector machines regression (SVR) to identify whether these network measures were able to predict clinical parameters.

Results

Network based statistics revealed significantly lower interregional connectivity strength between anatomical compartments including the fronto-temporal, parietal and visual areas in EM and CM when compared to HC. Higher assortativity was seen in both patients’ group, with higher modularity for CM and higher transitivity for EM compared to HC. For subcortical networks, higher assortativity and transitivity were observed for both patients’ group with higher modularity for CM. SVR revealed that network measures could robustly predict clinical parameters for migraineurs.

Conclusion

We found global network disruption for EM and CM indicated by highly segregated network in migraine patients compared to HC. Higher modularity but lower clustering coefficient in CM is suggestive of more segregation in this group compared to EM. The presence of a segregated network could be a sign of maladaptive reorganization of headache related brain circuits, leading to migraine attacks or secondary alterations to pain.

Supplementary Information

The online version contains supplementary material available at 10.1186/s10194-021-01216-8.

Cortical Thickness in Migraine: A Coordinate-Based Meta-Analysis

Cortical thickness (CTh) via surface-based morphometry analysis is a popular method to characterize brain morphometry. Many studies have been performed to investigate CTh abnormalities in migraine. However, the results from these studies were not consistent and even conflicting. These divergent results hinder us to obtain a clear picture of brain morphometry regarding CTh alterations in migraine. Coordinate-based meta-analysis (CBMA) is a promising technique to quantitatively pool individual neuroimaging studies to identify consistent brain areas involved. Electronic databases (PubMed, EMBASE, Web of Science, China National Knowledge Infrastructure, WanFang, and SinoMed) and other sources (bioRxiv and reference lists of relevant articles and reviews) were systematically searched for studies that compared regional CTh differences between patients with migraine and healthy controls (HCs) up to May 15, 2020. A CBMA was performed using the Seed-based d Mapping with Permutation of Subject Images approach. In total, we identified 16 studies with 17 datasets reported that were eligible for the CBMA. The 17 datasets included 872 patients with migraine (average sample size 51.3, mean age 39.6 years, 721 females) and 949 HCs (average sample size 59.3, mean age 44.2 years, 680 females). The CBMA detected no statistically significant consistency of CTh alterations in patients with migraine relative to HCs. Sensitivity analysis and subgroup analysis verified this result to be robust. Metaregression analyses revealed that this CBMA result was not confounded by age, gender, aura, attack frequency per month, and illness duration. Our CBMA adds to the evidence of the replication crisis in neuroimaging research that is increasingly recognized. Many potential confounders, such as underpowered sample size, heterogeneous patient selection criteria, and differences in imaging collection and methodology, may contribute to the inconsistencies of CTh alterations in migraine, which merit attention before planning future research on this topic.

Abnormal cortical thickening and thinning in idiopathic normal-pressure hydrocephalus

We investigated differences in cortical thickness between idiopathic normal-pressure hydrocephalus (INPH) patients and healthy controls. We also explored whether a relationship exists between cortical thinning and gait disturbance in INPH patients. Forty-nine INPH patients and 26 healthy controls were imaged with MRI, including 3-dimensional volumetric images, for automated surface-based cortical thickness analysis across the entire brain. Compared with age- and gender-matched healthy controls, unexpectedly, INPH patients showed statistically significant cortical thickening mainly in areas located in the high convexity of the frontal, parietal, and occipital regions. Additionally, cortical thinning mainly in temporal and orbitofrontal regions was observed in the INPH group relative to the control group. The Gait Status Scale (GSS) scores were negatively correlated with cortical thickness in the medial orbital part of the superior frontal gyrus, gyrus rectus, superior temporal gyrus, temporal pole, and insula. A distinctive pattern of cortical thickness changes was found in INPH patients. We cautiously suggest that cortical thickening in INPH can result from reactive gliosis. Further, our results support the hypothesis that cortical thinning in INPH can result from neuronal degeneration. In addition, cortical thinning can play an important role in gait disturbances in INPH patients.

In silico analysis of gene expression in V3a and the superior occipital gyrus: Relevance for migraine

Introduction:

Visual manifestations are the most prominent non-painful features of migraine. During the last decades, visual area V3a has gathered attention of headache scientists because of its apparent implication on aura initiation, photophobia and cortical hyper-responsiveness related to visual motion perception. In this hypothesis-generating study, we performed an in silico analysis of gene expression in left V3a and the cerebral gyrus that harbours it (left superior occipital gyrus (lSOG)) searching for transcriptomic patterns that could be linked with migraine’s pathophysiology.

Materials and methods:

Neurotransmitter receptor gene expression levels in left V3a were extracted from validated brain mRNA expression models using a probabilistic volumetric mask of this region. The primary visual cortex and other sensory cortices (auditory, olfactory and somatosensory) were used as comparators. Genome-wide transcriptomic differences between the gyrus harbouring left V3a (lSOG) and the rest of the cerebral cortex were assessed using the Allen Brain Institute Human RNA micro array atlas/database.

Results:

Adrenergic receptor β1, dopaminergic receptor D3 and serotoninergic receptors 1B, 1F and 2A, which have been previously implicated in migraine’s pathophysiology and/or treatment, showed significantly higher expression levels on left V3a. Transcriptomic differences between the lSOG harbouring V3a and the rest of the cortex comprise genes whose products are involved in neuronal excitability (SLC17A6, KCNS1, KCNG1 and GABRQ), activation of multiple signal transduction pathways (MET) and cell metabolism (SPHKAP via its interaction with cAMP-dependent protein kinase).

Conclusions:

Focal gene expression analysis of V3a suggests some clues about its implication in migraine. Further studies are warranted.

Functional gene networks reveal distinct mechanisms segregating in migraine families

Migraine is the most common neurological disorder worldwide and it has been shown to have complex polygenic origins with a heritability of estimated 40-70%. Both common and rare genetic variants are believed to underlie the pathophysiology of the prevalent types of migraine, migraine with typical aura and migraine without aura. However, only common variants have been identified so far. Here we identify for the first time a gene module with rare mutations through a systems genetics approach integrating RNA sequencing data from brain and vascular tissues likely to be involved in migraine pathology in combination with whole genome sequencing of 117 migraine families. We found a gene module in the visual cortex, based on single nuclei RNA sequencing data, that had increased rare mutations in the migraine families and replicated this in a second independent cohort of 1930 patients. This module was mainly expressed by interneurons, pyramidal CA1, and pyramidal SS cells, and pathway analysis showed association with hormonal signalling (thyrotropin-releasing hormone receptor and oxytocin receptor signalling pathways), Alzheimer's disease pathway, serotonin receptor pathway and general heterotrimeric G-protein signalling pathways. Our results demonstrate that rare functional gene variants are strongly implicated in the pathophysiology of migraine. Furthermore, we anticipate that the results can be used to explain the critical mechanisms behind migraine and potentially improving the treatment regime for migraine patients.

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.

Mapping migraine to a common brain network

Inconsistent findings from migraine neuroimaging studies have limited attempts to localize migraine symptomatology. Novel brain network mapping techniques offer a new approach for linking neuroimaging findings to a common neuroanatomical substrate and localizing therapeutic targets. In this study, we attempted to determine whether neuroanatomically heterogeneous neuroimaging findings of migraine localize to a common brain network. We used meta-analytic coordinates of decreased grey matter volume in migraineurs as seed regions to generate resting state functional connectivity network maps from a normative connectome (n = 1000). Network maps were overlapped to identify common regions of connectivity across all coordinates. Specificity of our findings was evaluated using a whole-brain Bayesian spatial generalized linear mixed model and a region of interest analysis with comparison groups of chronic pain and a neurologic control (Alzheimer's disease). We found that all migraine coordinates (11/11, 100%) were negatively connected (t ≥ ±7, P < 10-6 family-wise error corrected for multiple comparisons) to a single location in left extrastriate visual cortex overlying dorsal V3 and V3A subregions. More than 90% of coordinates (10/11) were also positively connected with bilateral insula and negatively connected with the hypothalamus. Bayesian spatial generalized linear mixed model whole-brain analysis identified left V3/V3A as the area with the most specific connectivity to migraine coordinates compared to control coordinates (voxel-wise probability of ≥90%). Post hoc region of interest analyses further supported the specificity of this finding (ANOVA P = 0.02; pairwise t-tests P = 0.03 and P = 0.003, respectively). In conclusion, using coordinate-based network mapping, we show that regions of grey matter volume loss in migraineurs localize to a common brain network defined by connectivity to visual cortex V3/V3A, a region previously implicated in mechanisms of cortical spreading depression in migraine. Our findings help unify migraine neuroimaging literature and offer a migraine-specific target for neuromodulatory treatment.

Cortical morphological changes in chronic migraine in a Taiwanese cohort: Surface- and voxel-based analyses

BACKGROUND

Previous voxel- or surface-based morphometric analysis studies have revealed alterations in cortical structure in patients with chronic migraine, yet with inconsistent results. The discrepancies may be derived partly from the sample heterogeneity. Employing both methods in a clinically homogenous group may provide a clearer view.

METHODS

Structural MRI data from 30 prevention-naïve patients with chronic migraine without medication overuse headache or a history of major depression and 30 healthy controls were analyzed. Vertex-wise (surface-based) or voxel-wise (voxel-based) linear models were applied, after controlling for age and gender, to investigate between-group differences. Averaged cortical thicknesses and volumes from regions showing group differences were correlated with parameters related to clinical profiles.

RESULTS

Surface-based morphometry showed significantly thinner cortices in the bilateral insular cortex, caudal middle frontal gyrus, precentral gyrus, and parietal lobes in patients with chronic migraine relative to healthy controls. Additionally, the number of migraine days in the month preceding MRI examination was correlated negatively with right insular cortical thickness. Voxel-based morphometry (VBM) did not show any group differences or clinical correlations.

CONCLUSION

Patients with chronic migraine without medication overuse headache, major depression, or prior preventive treatment had reduced cortical thickness in regions within the pain-processing network. Compared to voxel-based morphometry, surface-based morphometry analysis may be more sensitive to subtle structural differences between healthy controls and patients with chronic migraine.

Altered lateral geniculate nucleus functional connectivity in migraine without aura: a resting-state functional MRI study

OBJECTIVES

To investigate the structural and functional connectivity changes of lateral geniculate nucleus (LGN) and their relationships with clinical characteristics in patients without aura.

METHODS

Conventional MRI, 3D structure images and resting state functional MRI were performed in 30 migraine patients without aura (MwoA) and 22 healthy controls (HC). The lateral geniculate nucleus volumes and the functional connectivity (FC) of bilateral lateral geniculate nucleus were computed and compared between groups.

RESULTS

The lateral geniculate nucleus volumes in patient groups did not differ from the controls. The brain regions with increased FC of the left LGN mainly located in the left cerebellum and right lingual gyrus in MwoA compared with HC. The increased FC of right LGN located in left inferior frontal gyrus in MwoA compared with HC. The correlation analysis showed a positive correlation between VLSQ-8 score and the increased FC of left cerebellum and right lingual gyrus.

CONCLUSIONS

Photophobia in MwoA could be mediated by abnormal resting state functional connectivity in visual processing regions, the pain perception regulatory network and emotion regulation network. This result is valuable to further understanding about the clinical manifestation and pathogenesis of migraine.

Imaging the Visual Network in the Migraine Spectrum

The involvement of the visual network in migraine pathophysiology has been well-known for more than a century. Not only is the aura phenomenon linked to cortical alterations primarily localized in the visual cortex; but also migraine without aura has shown distinct dysfunction of visual processing in several studies in the past. Further, the study of photophobia, a hallmark migraine symptom, has allowed unraveling of distinct connections that link retinal pathways to the trigeminovascular system. Finally, visual snow, a recently recognized neurological disorder characterized by a continuous visual disturbance, is highly comorbid with migraine and possibly shares with it some common pathophysiological mechanisms. Here, we review the most relevant neuroimaging literature to date, considering studies that have either attempted to investigate the visual network or have indirectly shown visual processing dysfunctions in migraine. We do this by taking into account the broader spectrum of migrainous biology, thus analyzing migraine both with and without aura, focusing on light sensitivity as the most relevant visual symptom in migraine, and finally analyzing the visual snow syndrome. We also present possible hypotheses on the underlying pathophysiology of visual snow, for which very little is currently known.

Interictal Hyperperfusion in the Higher Visual Cortex in Patients With Episodic Migraine

BACKGROUND

Migraine pathophysiology is complex and probably involves cortical and subcortical alterations. Structural and functional brain imaging studies indicate alterations in the higher order visual cortex in patients with migraine. Arterial spin labeling magnetic resonance imaging (ASL-MRI) is a non-invasive imaging method for assessing changes in cerebral blood flow (CBF) in vivo.

OBJECTIVE

To examine if interictal CBF differs between patients with episodic migraine (EM) with or without aura and healthy controls (HC).

METHODS

We assessed interictal CBF using 2D pseudo-continuous ASL-MRI on a 3 Tesla Philips scanner (University Hospital Zurich, Switzerland) in EM (N = 17, mean age 32.7 ± 9.9, 13 females) and HC (N = 19, mean age 31.0 ± 9.3, 11 females).

RESULTS

Compared to HC, EM showed exclusively hyperperfusion in the right MT+ and Cohen's d effect size was 0.99 (HC mean CBF ± SD: 33.1 ± 5.9 mL/100 g/minutes; EM mean CBF: 40.9 ± 9.4 mL/100 g/minutes). EM with aura (N = 13, MwA) revealed hyperperfusion compared to HC in the right MT+ and superior temporal gyrus. For MT, Cohen's d effect size was 1.34 (HC mean CBF ± SD: 33.1 ± 5.9 mL/100 g/minutes; MwA mean CBF: 43.3 ± 8.6 mL/100 g/minutes). For the superior temporal gyrus, Cohen's d effect size was 1.28 (HC mean CBF ± SD: 40.1 ± 4.9 mL/100 g/minutes; MwA mean CBF: 47.4 ± 6.4 mL/100 g/minutes). In EM, anxiety was positively associated with CBF in the parietal operculum and angular gyrus.

CONCLUSIONS

Our results suggest that extrastriate brain regions probably involved in cortical spreading depression are associated with CBF changes in the interictal state. We conclude that ASL-MRI is a sensitive method to identify local neuro-functional abnormalities in CBF in patients with EM in the interictal state.

Application of the Migraine Aura Complexity Score (MACS): Clinical and Neuroimaging Study

Background: Manifestations of typical migraine aura can be numerous. Investigation of its pathophysiological mechanisms can be challenging if a stratification of phenotypes is not performed. In this context, the Migraine Aura Complexity Score (MACS), recently developed, may help. Here we aimed to categorize migraine patients into homogenous groups using MACS and to compare those groups with respect to patients' characteristics and neuroimaging findings. Methods: Participants who have a migraine with aura (MwA) were interviewed after each attack in order to obtain the characteristics of migraine aura. Thereafter, we scored the complexity of their auras by MACS. The MACS was used to categorize patients into three groups: MwA-S (with simple aura), MwA-MC (with moderately complex aura), and MwA-C (with complex aura). The patient characteristics and estimated cortical thickness of regions of interest, which are potentially linked to the symptoms that develop during the aura, were used to compare these groups. Results: In total, 338 MwA attacks were recorded in analyzed groups. Scotoma was the most frequently reported symptom in the groups, followed by somatosensory aura in the MwA-C group and zig-zag lines in the MwA-MC and MwA-S groups. Patients in the MwA-C and MwA-MC groups had a thicker cortex in the left primary visual cortex with respect to MwA-S group. In addition, patients in the MwA-C group had a thicker cortex in several visual and somatosensory cortical regions relative to the MwA-S group. Conclusions: Our results show that the newly developed MACS can be used for the stratification of MwA patients, herewith allowing the better investigation of changes in migraineurs' brains.

Clinical correlates of mathematical modeling of cortical spreading depression: Single-cases study

INTRODUCTION

Considerable connections between migraine with aura and cortical spreading depression (CSD), a depolarization wave originating in the visual cortex and traveling toward the frontal lobe, lead to the hypothesis that CSD is underlying migraine aura. The highly individual and complex characteristics of the brain cortex suggest that the geometry might impact the propagation of cortical spreading depression.

METHODS

In a single-case study, we simulated the CSD propagation for five migraine with aura patients, matching their symptoms during a migraine attack to the CSD wavefront propagation. This CSD wavefront was simulated on a patient-specific triangulated cortical mesh obtained from individual MRI imaging and personalized diffusivity tensors derived locally from diffusion tensor imaging data.

RESULTS

The CSD wave propagation was simulated on both hemispheres, despite in all but one patient the symptoms were attributable to one hemisphere. The CSD wave diffused with a large wavefront toward somatosensory and prefrontal regions, devoted to pain processing.

DISCUSSION

This case-control study suggests that the cortical geometry may contribute to the modality of CSD evolution and partly to clinical expression of aura symptoms. The simulated CSD is a large and diffuse phenomenon, possibly capable to activate trigeminal nociceptors and to involve cortical areas devoted to pain processing.

Transient Neurologic Dysfunction in Migraine

Transient disturbances in neurologic function are disturbing features of migraine attacks. Aura types include binocular visual, hemi-sensory, language and unilateral motor symptoms. Because of the gradual spreading quality of visual and sensory symptoms, they were thought to arise from the cerebral cortex. Motor symptoms previously included as a type of migraine aura were reclassified as a component of hemiplegic migraine. ICHD-3 criteria of the International Headache Society, added brainstem aura and retinal aura as separate subtypes. The susceptibility to all types of aura is likely to be included by complex and perhaps epigenetic factors.

Delineating conditions and subtypes in chronic pain using neuroimaging

Differentiating subtypes of chronic pain still remains a challenge—both from a subjective and objective point of view. Personalized medicine is the current goal of modern medical care and is limited by the subjective nature of patient self-reporting of symptoms and behavioral evaluation. Physiology-focused techniques such as genome and epigenetic analyses inform the delineation of pain groups; however, except under rare circumstances, they have diluted effects that again, share a common reliance on behavioral evaluation. The application of structural neuroimaging towards distinguishing pain subtypes is a growing field and may inform pain-group classification through the analysis of brain regions showing hypertrophic and atrophic changes in the presence of pain. Analytical techniques such as machine-learning classifiers have the capacity to process large volumes of data and delineate diagnostically relevant information from neuroimaging analysis. The issue of defining a “brain type” is an emerging field aimed at interpreting observed brain changes and delineating their clinical identity/significance. In this review, 2 chronic pain conditions (migraine and irritable bowel syndrome) with similar clinical phenotypes are compared in terms of their structural neuroimaging findings. Independent investigations are compared with findings from application of machine-learning algorithms. Findings are discussed in terms of differentiating patient subgroups using neuroimaging data in patients with chronic pain and how they may be applied towards defining a personalized pain signature that helps segregate patient subgroups (eg, migraine with and without aura, with or without nausea; irritable bowel syndrome vs other functional gastrointestinal disorders).

Shedding light on migraine with aura: the clarifying role of advanced neuroimaging investigations

Introduction: While migraine with aura is a complex neurological syndrome with a well-characterized clinical phenotype, its pathophysiology still has grey areas which could be partially clarified by microstructural and functional neuroimaging investigations. Areas covered: This article, summarizing the most significant findings from advanced neuroimaging studies, aims to achieve a unifying pathophysiological model of the migraine aura. A comprehensive review has been conducted of PubMed citations by entering the key word 'neuroimaging' combined with 'migraine with aura' AND/OR 'MRI.' Other keywords included 'grey matter' OR 'white matter', 'structural' OR 'functional'. Expert opinion: Converging evidence from advanced neuroimaging investigations underlined the critical role of the extrastriate visual cortex, and in particular the lingual gyrus, in the genesis of the aura phenomenon. However, the relationship between the aura and the headache phase of migraine attacks has not been completely clarified, to date, and underlying pathophysiological mechanisms need to be further elucidated.

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.

Primary headaches during lifespan

Primary headaches are one of the most prevalent neurological disorders and can occur during a wide range of lifespan. Primary headaches, especially migraine, are cyclic disorders with a complex sequence of symptoms within every headache attack. There is no systematic review of whether these symptoms changes during lifespan. Indeed, the clinical presentation of migraine shows an age-dependent change with a significantly shorter duration of the attacks and occurrence of different paroxysmal symptoms, such as vomiting, abdominal pain or vertigo, in childhood and, in contrast, largely an absence of autonomic signs and a more often bilateral headache in the elderly. The age-dependent differences in the clinical presentation are less distinct in cluster headache and, especially, in tension-type headache. The differences in the clinical presentation are in agreement with the idea that the connectivity of hypothalamic areas with different brainstem areas, especially the central parasympathetic areas, is important for the clinical manifestation of migraine, as well as, the change during lifespan.

Neuroimaging clues of migraine aura

While migraine headaches can be provoked, or predicted by the presence of an aura or premonitory symptoms, the prediction or elicitation of the aura itself is more problematic. Therefore, imaging studies directly examining the aura phenomenon are sparse. There are however interictal imaging studies that can shed light on the pathophysiology of the migraine with aura (MWA) cascade. Here, we review findings pointing to the involvement of cortical spreading depression (CSD) and neuroinflammation in MWA. Whether asymptomatic CSD also happens in some migraine without aura is still under debate. In addition, new evidence points to glial activation in MWA, indicating the involvement of astrocytes in the neuroinflammatory cascade that follows CSD, as well as dural macrophages, supporting the involvement of the trigeminovascular system in migraine pain.

Volume alterations of brainstem subregions in migraine with aura

Background

The brainstem plays a significant role in migraine pathogenesis, but a relationship between volume alterations of brainstem subregions and migraine aura characteristics has not been sufficiently investigated. The aim of this study is to compare the volume of the brainstem, and its subregions, between patients with a migraine with aura (MwA) and healthy controls (HC), and also to correlate characteristics of MwA and the volume of the brainstem subregions.

Methods

Forty-two MwA and 42 HCs, balanced by sex and age, were selected for this study. Total brainstem volume changes as well as volume changes in the pons, medulla, midbrain and the superior cerebellar peduncles were investigated in MwA relative to HCs. In addition, the relationships between brainstem subregions and aura characteristics (aura duration, the frequency of the aura, occurrence of somatosensory and dysphasic aura, duration of a headache, intensity of headache pain and disease duration) were explored in MwA.

Results

MwA patients had a larger brainstem volume relative to HCs (25,941.35 ± 2559.2 mm³ vs. 25,179.32 ± 2019.1 mm³; p = .008), as well as the midbrain and pons (6155.98 ± 565.7 mm³ vs. 5964.22 ± 457.0 mm³, p = .002; 15,105.13 ± 1765.5 mm³ vs. 14,539.89 ± 1408.4 mm³, p = .007, respectively). Total brainstem volume, as well as volumes of brainstem subregions, were not significantly correlated to the MwA characteristics.

Conclusion

The results of this study reveal that a migraine with aura is associated with a larger volume of the brainstem with a particular involvement of the midbrain and pons.

•

Migraineurs with aura had larger volume of pons and midbrain relative to controls.

•

Medulla did not significantly differ in volume size between migraineurs and controls.

•

Volume of brainstem is not linked to disease duration and intensity of headache pain.

Influence of hemispheric white matter lesions and migraine characteristics on cortical thickness and volume

Background/Aim

Migraine-related intracerebral white matter lesions (WMLs) are likely to be microvascular in nature and can be found in all hemispheric lobes. The aim of this study was to investigate migraine patients with or without WMLs to see the effects of these tissue damages on cortical thickness and volume. The role of migraine characteristics (duration of headache, attack frequency, estimated lifetime attack number, aura) was also tested.

Methods

As study participants, 161 female migraine patients (63 with aura; 52 with WMLs) and 40 age-matched healthy female subjects were enrolled in the study. None of the included migraine patients’ headache or aura (where present) was unilaterally side-locked. Patients and controls were all right handed. Except for migraine, patients were free of any medical comorbidity. Cortical reconstruction and segmentation were performed on the 3D T1-weighted images using Freesurfer 5.3 image analysis suite. The automatic cortical parcellation was based on Freesurfer’s Desikan–Killiany–Tourville atlas, which has 31 cortical regions per hemisphere. The segmented regions were divided into five lobes (frontal, parietal, temporal, occipital, insula). Since the left and right differences in lobar and insular volumes/thicknesses were not different among our groups, volume and cortical thickness were calculated for corresponding bilateral lobes.

Results

There was no significant difference in age between the whole migraine and the control groups. Migraineurs with WMLs (L+ patients) were significantly older than lesion-free (L-) patients (P = 0.0003) and controls (P = 0.018). Disease duration (P = 0.003), the total number of migraine attacks (P = 0.022) and the rate of aura (P = 0.0003) were significantly higher in L+ patients than in L- patients. Cortical thickness and volume measurements of lobes were not statistically different between the three groups (L+, L-, control). Age showed a significant negative association with both thickness and volume in each examined lobe (P < 0.001). Intracranial volume (ICV) showed a significant positive association with all regional volumes (P < 0.001). There were no significant group*age, group*ICV, or age*ICV interactions. None of the migraine characteristics were selected by stepwise linear regression as significant predictors of cortical thickness or volume. Only age (for both thickness and volume) and ICV (for volume) were identified as significant predictors (P < 0.001). When the L + group was divided into two subgroups by median split of total and lobar lesion number and volume, the cortical measures did not show any significant difference between the groups with low vs. high lesion number/volume by stepwise linear regression.

Conclusions

In a female migraine group, we found that the WMLs and clinical migraine characteristics have no effect on cortical thickness and volume of bilateral lobes. Lobar cortical thicknesses were equivalent within the range of ±0.1 mm. Only age and ICV proved to be significant predictors; the former for both cortical thickness and volume, while the latter for cortical volume.

Cortical abnormalities in episodic migraine: A multi-center 3T MRI study

BACKGROUND

Several previous studies have investigated cortical abnormalities, specifically cortical thickness, in patients with migraine, with variable results. The relatively small sample sizes of most previous studies may partially explain these inconsistencies.

OBJECTIVE

To investigate differences of cortical thickness between control subjects and migraineurs in a large cohort.

METHODS

Three Tesla MRI data of 131 patients (38 with and 93 without aura) and 115 control subjects were analysed. A vertex-wise linear model was applied controlling for age, gender and MRI scanner to investigate differences between groups and determine the impact of clinical factors on cortical thickness measures.

RESULTS

Migraineurs showed areas of thinned cortex compared with controls bilaterally in the central sulcus, in the left middle-frontal gyrus, in left visual cortices and the right occipito-temporal gyrus. Frequency of migraine attacks and the duration of the disorder had a significant impact on cortical thickness in the sensorimotor cortex and middle-frontal gyrus. Patients without aura showed thinner cortex than controls bilaterally in the central sulcus and in the middle frontal gyrus, in the left primary visual cortices, in the left supramarginal gyrus and in the right cuneus. Patients with aura showed clusters of thinner cortex bilaterally in the subparietal sulcus (between the precuneus and posterior cingulate cortex), in the left intraparietal sulcus and in the right anterior cingulate.

CONCLUSION

These results indicate cortical abnormalities in specific brain regions in migraineurs. Some of the observed abnormalities may reflect a genetic susceptibility towards developing migraine attacks, while others are probably a consequence of repeated head pain attacks.