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

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.

Two distinct neuroanatomical subtypes of migraine without aura revealed by heterogeneity through discriminative analysis

The neurobiological heterogeneity in migraine is poorly studied, resulting in conflicting neuroimaging findings. This study used a newly proposed method based on gray matter volumes (GMVs) to investigate objective neuroanatomical subtypes of migraine. Structural MRI and clinical measures of 31 migraine patients without aura and 33 matched healthy controls (HCs) were explored. Firstly, we investigated whether migraine patients exhibited higher interindividual variability than HCs in terms of GMVs. Then, heterogeneity through discriminative analysis (HYDRA) was applied to categorize migraine patients into distinct subtypes by regional volumetric measures of GMVs. Voxel-wise volume and clinical characteristics among different subtypes were also explored. Migraine patients without aura exhibited higher interindividual GMVs variability. Two distinct and reproducible neuroanatomical subtypes of migraine were revealed. These two subtypes exhibited opposite neuroanatomical aberrances compared to HCs. Subtype 1 showed widespread decreased GMVs, while Subtype 2 showed increased GMVs in limited regions. The total intracranial volume was significantly positively correlated with cognitive function in Subtype 2. Subtype 1 showed significantly longer illness duration and less cognitive scores compared to Subtype 2. The present study shows that migraine patients without aura have high structural heterogeneity and uncovers two distinct and robust neuroanatomical subtypes, which provide a possible explanation for conflicting neuroimaging findings.

Structural imaging studies of patients with chronic pain: an anatomical likelihood estimate meta-analysis

ABSTRACT

Neuroimaging is a powerful tool to investigate potential associations between chronic pain and brain structure. However, the proliferation of studies across diverse chronic pain syndromes and heterogeneous results challenges data integration and interpretation. We conducted a preregistered anatomical likelihood estimate meta-analysis on structural magnetic imaging studies comparing patients with chronic pain and healthy controls. Specifically, we investigated a broad range of measures of brain structure as well as specific alterations in gray matter and cortical thickness. A total of 7849 abstracts of experiments published between January 1, 1990, and April 26, 2021, were identified from 8 databases and evaluated by 2 independent reviewers. Overall, 103 experiments with a total of 5075 participants met the preregistered inclusion criteria. After correction for multiple comparisons using the gold-standard family-wise error correction ( P < 0.05), no significant differences associated with chronic pain were found. However, exploratory analyses using threshold-free cluster enhancement revealed several spatially distributed clusters showing structural alterations in chronic pain. Most of the clusters coincided with regions implicated in nociceptive processing including the amygdala, thalamus, hippocampus, insula, anterior cingulate cortex, and inferior frontal gyrus. Taken together, these results suggest that chronic pain is associated with subtle, spatially distributed alterations of brain structure.

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.

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.

Evaluation of simple antioxidant blood parameters in patients with migraine

Background

The study aims to investigate the role of serum albumin (ALB) and creatinine (CRE), bilirubin (BIL), and uric acid (UA) as major intravascular antioxidants in migraine.

Methods

We enrolled 148 patients with migraine and 150 age- and sex-matched healthy controls. The serum levels of ALB, TBIL, CRE, and UA were measured in patients with migraine of different subtypes. The risk of migraine was assessed by multiple stepwise logistic regression analysis.

Results

The serum levels of ALB, total BIL (TBIL), CRE, and UA were significantly lower in the migraine group than in the HC group (p < 0.05). The ALB and UA levels were lower during migraine attack periods (p < 0.05). There were no statistically significant differences observed in serum ALB, TBIL, CRE, and UA levels between aura/without aura and episodic/chronic migraine subtypes (p > 0.05). The multiple stepwise logistic regression revealed that ALB [odds ratio (OR) 0.79, 95% confidence interval (CI) 0.69–0.89, p < 0.001], TBIL (OR 0.61, 95% CI 0.5–0.75, p < 0.001), and UA (OR 0.97, 95% CI 0.96–0.99, p = 0.014) were independently associated with migraine. In addition, the serum levels of ALB, TBIL, and UA were significantly lower in the migraine group when compared by sex.

Conclusion

The serum levels of UA, TBIL, ALB, and CRE were lower in the patients with migraine, indicating a lower antioxidant status. In addition, ALB, TBIL, and UA were independently related to migraine. These results could provide insights into the possible role of oxidative stress in the pathogenesis of migraine.

Gray Matter Volume Abnormality in Chronic Pain Patients With Depressive Symptoms: A Systemic Review and Meta-Analysis of Voxel-Based Morphometry Studies

Background

Gray matter volume (GMV) alteration in specific brain regions has been widely regarded as one of the most important neuroplasticity features in chronic pain patients with depressive symptoms (CP-D). However, the consistent and significant results were still lacking. Thus, further exploration was suggested to be performed.

Objectives

This study aimed to comprehensively collect the voxel-based morphometry (VBM) studies on GMV alteration between CP-D and healthy controls (HCs). And a systemic review and meta-analysis were made to explore the characteristic brain regions in chronic pain and depression comorbidity.

Methods

Search of PubMed, MEDLINE, Web of Science, and Cochrane Library databases updated to July 13, 2021. The altered GMV between CP-D and HCs in VBM studies was included in this meta-analysis. In total, 18 studies (20 datasets) and 1320 participants (520 patients and 800 HCs) were included. The significant coordinate information (x, y, z) reported in standard space and the effect size (t-value or z-score) were extracted and analyzed by anisotropic effect size-signed differential mapping (AES-SDM) 5.15 software.

Results

According to the main analysis results, CP-D showed significant and consistent increased GMV in the left hippocampus (HIP. L) and decreased GMV in the medial part of the left superior frontal gyrus (SFG. L, BA 10) compared to HCs. Subgroup analysis showed significant decreased GMV in the medial orbital part of SFG.R (BA 10) in neuropathic pain, as well as significant increased GMV in the right parahippocampal gyrus (PHG.R, BA 35), left hippocampus (HIP.L, BA 20), and right middle frontal gyrus (MFG.R) in musculoskeletal pain. Furthermore, meta-regression showed a positive relationship between the decreased GMV in the medial part of SFG.L and the percentage of female patients.

Conclusion

GMV abnormality in specific brain areas (e.g., HIP.L and SFG) was robust and reproducible, which could be significantly involved in this comorbidity disease. The findings in this study may be a valuable reference for future research.

Systematic Review Registration

[www.crd.york.ac.uk/prospero/].

Irritable bowel syndrome in women: Association between decreased insular subregion volumes and gastrointestinal symptoms

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All insular subregions are smaller in IBS compared to healthy women.

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Insular volume associates with GI symptoms independent of psychiatric comorbidity.

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GI symptoms associate with anterior but not posterior insular volume.

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More nausea associated with smaller dorsal anterior insula bilaterally.

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Insula in major depression is not significantly smaller than in healthy women.

Objective

Irritable bowel syndrome (IBS) is a chronic pain disorder characterized by disturbed interactions between the gut and the brain with depression as a common comorbidity. In both IBS and depression, structural brain alterations of the insular cortices, key structures for pain processing and interoception, have been demonstrated but the specificity of these findings remains unclear. We compared the gray matter volume (GMV) of insular cortex (IC) subregions in IBS women and healthy controls (HC) and examined relations to gastrointestinal (GI) symptoms and glutamate + glutamine (Glx) concentrations. We further analyzed GMV of IC subregions in women with major depression (MDD) compared to HC and addressed possible differences between depression, IBS, IBS with depression and HC.

Design

Women with IBS (n = 75), MDD (n = 41) and their respective HC (n = 39 and n = 43) underwent structural brain MRI. IC subregion volumes were estimated using statistical parametric mapping software. General linear model approaches were applied to IC volumetric data and FDR-corrected partial correlation analyses assessed relations between GMV, GI symptoms and Glx concentrations.

Results

IBS patients had significantly smaller IC subregions than HC in both hemispheres but there was no significant difference between MDD compared with IBS and HC for any insular subregion. In IBS, the dorsal anterior insular volumes were negatively correlated with symptoms of nausea and pain, and the left ventral subregion showed a positive correlation with straining to defecate, while the posterior subregion volumes showed no relation to symptoms. In the anterior insula, concentration of Glx showed positive correlations with GMV bilaterally in HC and with GMV of the right anterior insula in IBS.

Conclusion

As the interoceptive cortex, the insula shows substantial and disease-specific structural differences in patients with chronic interoceptive visceral pain. Particularly changes in the anterior proportions might be related to chronic exposure to or enhanced salience towards adverse interoceptive visceral signals and could be linked to biochemical changes, calling for further multimodal and longitudinal work.

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.