Migraine affects white-matter tract integrity: A diffusion-tensor imaging study

Involvement of the cerebellum in structural connectivity enhancement in episodic migraine

BACKGROUND

The pathophysiology of migraine remains poorly understood, yet a growing number of studies have shown structural connectivity disruptions across large-scale brain networks. Although both structural and functional changes have been found in the cerebellum of migraine patients, the cerebellum has barely been assessed in previous structural connectivity studies of migraine. Our objective is to investigate the structural connectivity of the entire brain, including the cerebellum, in individuals diagnosed with episodic migraine without aura during the interictal phase, compared with healthy controls.

METHODS

To that end, 14 migraine patients and 15 healthy controls were recruited (all female), and diffusion-weighted and T1-weighted MRI data were acquired. The structural connectome was estimated for each participant based on two different whole-brain parcellations, including cortical and subcortical regions as well as the cerebellum. The structural connectivity patterns, as well as global and local graph theory metrics, were compared between patients and controls, for each of the two parcellations, using network-based statistics and a generalized linear model (GLM), respectively. We also compared the number of connectome streamlines within specific white matter tracts using a GLM.

RESULTS

We found increased structural connectivity in migraine patients relative to healthy controls with a distinct involvement of cerebellar regions, using both parcellations. Specifically, the node degree of the posterior lobe of the cerebellum was greater in patients than in controls and patients presented a higher number of streamlines within the anterior limb of the internal capsule. Moreover, the connectomes of patients exhibited greater global efficiency and shorter characteristic path length, which correlated with the age onset of migraine.

CONCLUSIONS

A distinctive pattern of heightened structural connectivity and enhanced global efficiency in migraine patients compared to controls was identified, which distinctively involves the cerebellum. These findings provide evidence for increased integration within structural brain networks in migraine and underscore the significance of the cerebellum in migraine pathophysiology.

White matter and cortical gray matter microstructural abnormalities in new daily persistent headache: a NODDI study

BACKGROUND

New daily persistent headache (NDPH) is a rare primary headache with unclear pathogenesis. Neuroimaging studies of NDPH are limited, and controversy still exists. Diffusion tensor imaging (DTI) is commonly used to study the white matter. However, lacking specificity, the potential pathological mechanisms of white matter microstructural changes remain poorly understood. In addition, the intricacy of gray matter structures impedes the application of the DTI model. Here, we applied an advanced diffusion model of neurite orientation dispersion and density imaging (NODDI) to study the white matter and cortical gray matter microstructure in patients with NDPH.

METHODS

This study assessed brain microstructure, including 27 patients with NDPH, and matched 28 healthy controls (HCs) by NODDI. The differences between the two groups were assessed by tract-based spatial statistics (TBSS) and surface-based analysis (SBA), focusing on the NODDI metrics (neurite density index (NDI), orientation dispersion index (ODI), and isotropic volume fraction (ISOVF)). Furthermore, we performed Pearson's correlation analysis between the NODDI indicators and clinical characteristics.

RESULTS

Compared to HCs, patients with NDPH had a reduction of density and complexity in several fiber tracts. For robust results, the fiber tracts were defined as comprising more than 100 voxels, including bilateral inferior fronto-occipital fasciculus (IFOF), left superior longitudinal fasciculus (SLF) and inferior longitudinal fasciculus (ILF), as well as right corticospinal tract (CST). Moreover, the reduction of neurite density was uncovered in the left superior and middle frontal cortex, left precentral cortex, and right lateral orbitofrontal cortex and insula. There was no correlation between the NODDI metrics of these brain regions and clinical variables or scales of relevance after the Bonferroni correction.

CONCLUSIONS

Our research indicated that neurite loss was detected in both white matter and cortical gray matter of patients with NDPH.

Phenotyping Pain in Patients With Fibrous Dysplasia/McCune-Albright Syndrome

CONTEXT

Pain is a poorly managed aspect in fibrous dysplasia/McCune-Albright syndrome (FD/MAS) because of uncertainties regarding the clinical, behavioral, and neurobiological underpinnings that contribute to pain in these patients.

OBJECTIVE

Identify neuropsychological and neurobiological factors associated with pain severity in FD/MAS.

DESIGN

Prospective, single-site study.

PATIENTS

Twenty patients with FD/MAS and 16 age-sex matched healthy controls.

INTERVENTION

Assessments of pain severity, neuropathic pain, pain catastrophizing (pain rumination, magnification, and helplessness), emotional health, and pain sensitivity with thermal quantitative sensory testing. Central nervous system (CNS) properties were measured with diffusion tensor imaging, structural magnetic resonance imaging, and functional magnetic resonance imaging.

MAIN OUTCOME MEASURES

Questionnaire responses, detection thresholds and tolerances to thermal stimuli, and structural and functional CNS properties.

RESULTS

Pain severity in patients with FD/MAS was associated with more neuropathic pain quality, higher levels of pain catastrophizing, and depression. Quantitative sensory testing revealed normal detection of nonnoxious stimuli in patients. Individuals with FD/MAS had higher pain tolerances relative to healthy controls. From neuroimaging studies, greater pain severity, neuropathic pain quality, and psychological status of the patient were associated with reduced structural integrity of white matter pathways (superior thalamic radiation and uncinate fasciculus), reduced gray matter thickness (pre-/paracentral gyri), and heightened responses to pain (precentral, temporal, and frontal gyri). Thus, properties of CNS circuits involved in processing sensorimotor and emotional aspects of pain were altered in FD/MAS.

CONCLUSION

These results offer insights into pain mechanisms in FD/MAS, while providing a basis for implementation of comprehensive pain management treatment approaches that addresses neuropsychological aspects of pain.

Microstructural differences in migraine: A diffusion-tensor imaging study

BACKGROUND

Diffusion-tensor imaging can be applied to describe the microstructural integrity of the whole brain. As findings about microstructural alterations in migraine are inconsistent, we aimed to replicate the most frequent results and assess a relationship between migraine parameters and changes in microstructure.

METHODS

Diffusion-weighted MRI data of 37 migraine patients and 40 controls were collected. Two indices of diffusion of water molecules, fractional anisotropy and mean diffusivity were used in a voxel-wise analysis. Group comparisons were carried out in SPM12 using age and sex as covariates. Statistically significant results survived family-wise error correction (pFWE < 0.05). Migraine intensity, frequency, and duration were self-reported and correlated with mean fractional anisotropy and mean diffusivity values across clusters.

RESULTS

Migraine patients showed significantly lower fractional anisotropy in occipital regions, and significantly higher fractional anisotropy in thirteen clusters across the brain. Mean diffusivity of migraine patients was significantly decreased in the cerebellum and pons, but it was not increased in any area. Correlation between migraine duration and fractional anisotropy was significantly positive in the frontal cortex and significantly negative in the superior parietal lobule.

CONCLUSION

We suggest that microstructural integrity of the migraine brain is impaired in visual areas and shows duration-related alterations in regions of the default mode network.

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.

Functional MRI and Diffusion Tensor Imaging in Migraine: A Review of Migraine Functional and White Matter Microstructural Changes

Migraine is a complex and heterogenous disorder whose disease mechanisms remain disputed. This narrative review summarizes functional MRI (fMRI) and diffusion tensor imaging (DTI) findings and interprets their association with migraine symptoms and subtype to support and expand our current understanding of migraine pathophysiology. Our PubMed search evaluated and included fMRI and DTI studies involving comparisons between migraineurs vs healthy controls, migraineurs with vs without aura, and episodic vs chronic migraineurs. Migraineurs demonstrate changes in functional connectivity (FC) and regional activation in numerous pain-related networks depending on migraine phase, presence of aura, and chronicity. Changes to diffusion indices are observed in major cortical white matter tracts extending to the brainstem and cerebellum, more prominent in chronic migraine and associated with FC changes. Reported changes in FC and regional activation likely relate to pain processing and sensory hypersensitivities. Diffuse white matter microstructural changes in dysfunctional cortical pain and sensory pathways complement these functional differences. Interpretations of reported fMRI and DTI measure trends have not achieved a clear consensus due to inconsistencies in the migraine neuroimaging literature. Future fMRI and DTI studies should establish and implement a uniform methodology that reproduces existing results and directly compares migraineurs with different subtypes. Combined fMRI and DTI imaging may provide better pathophysiological explanations for nonspecific FC and white matter microstructural differences.

Advanced brain MRI may help understand the link between migraine and multiple sclerosis

BACKGROUND

There is a clinical association between migraine and multiple sclerosis.

MAIN BODY

Migraine and MS patients share similar demographics, with the highest incidence among young, female and otherwise healthy patients. The same hormonal constellations/changes trigger disease exacerbation in both entities. Migraine prevalence is increased in MS patients, which is further enhanced by disease-modifying treatment. Clinical data show that onset of migraine typically starts years before the clinical diagnosis of MS, suggesting that there is either a unidirectional relationship with migraine predisposing to MS, and/or a "shared factor" underlying both conditions. Brain imaging studies show white matter lesions in both MS and migraine patients. Neuroinflammatory mechanisms likely play a key role, at least as a shared downstream pathway. In this review article, we provide an overview of the literature about 1) the clinical association between migraine and MS as well as 2) brain MRI studies that help us better understand the mechanistic relationship between both diseases with implications on their underlying pathophysiology.

CONCLUSION

Studies suggest a migraine history predisposes patients to develop MS. Advanced brain MR imaging may shed light on shared and distinct features, while helping us better understand mechanisms underlying both disease entities.

Shared alterations in hippocampal structural covariance in subjective cognitive decline and migraine

Introduction

Subjective cognitive decline (SCD) and migraine are often comorbid. Hippocampal structural abnormalities have been observed in individuals with both SCD and migraine. Given the known structural and functional heterogeneity along the long axis (anterior to posterior) of the hippocampus, we aimed to identify altered patterns of structural covariance within hippocampal subdivisions associated with SCD and migraine comorbidities.

Methods

A seed-based structural covariance network analysis was applied to examine large-scale anatomical network changes of the anterior and posterior hippocampus in individuals with SCD, migraine and healthy controls. Conjunction analyses were used to identify shared network-level alterations in the hippocampal subdivisions in individuals with both SCD and migraine.

Results

Altered structural covariance integrity of the anterior and posterior hippocampus was observed in the temporal, frontal, occipital, cingulate, precentral, and postcentral areas in individuals with SCD and migraine compared with healthy controls. Conjunction analysis revealed that, in both SCD and migraine, altered structural covariance integrity was shared between the anterior hippocampus and inferior temporal gyri and between the posterior hippocampus and precentral gyrus. Additionally, the structural covariance integrity of the posterior hippocampus-cerebellum axis was associated with the duration of SCD.

Conclusion

This study highlighted the specific role of hippocampal subdivisions and specific structural covariance alterations within these subdivisions in the pathophysiology of SCD and migraine. These network-level changes in structural covariance may serve as potential imaging signatures for individuals who have both SCD and migraine.

Viability of AMURA biomarkers from single-shell diffusion MRI in clinical studies

Diffusion Tensor Imaging (DTI) is the most employed method to assess white matter properties using quantitative parameters derived from diffusion MRI, but it presents known limitations that restrict the evaluation of complex structures. The objective of this study was to validate the reliability and robustness of complementary diffusion measures extracted with a novel approach, Apparent Measures Using Reduced Acquisitions (AMURA), with a typical diffusion MRI acquisition from a clinical context in comparison with DTI with application to clinical studies. Fifty healthy controls, 51 episodic migraine and 56 chronic migraine patients underwent single-shell diffusion MRI. Four DTI-based and eight AMURA-based parameters were compared between groups with tract-based spatial statistics to establish reference results. On the other hand, following a region-based analysis, the measures were assessed for multiple subsamples with diverse reduced sample sizes and their stability was evaluated with the coefficient of quartile variation. To assess the discrimination power of the diffusion measures, we repeated the statistical comparisons with a region-based analysis employing reduced sample sizes with diverse subsets, decreasing 10 subjects per group for consecutive reductions, and using 5,001 different random subsamples. For each sample size, the stability of the diffusion descriptors was evaluated with the coefficient of quartile variation. AMURA measures showed a greater number of statistically significant differences in the reference comparisons between episodic migraine patients and controls compared to DTI. In contrast, a higher number of differences was found with DTI parameters compared to AMURA in the comparisons between both migraine groups. Regarding the assessments reducing the sample size, the AMURA parameters showed a more stable behavior than DTI, showing a lower decrease for each reduced sample size or a higher number of regions with significant differences. However, most AMURA parameters showed lower stability in relation to higher coefficient of quartile variation values than the DTI descriptors, although two AMURA measures showed similar values to DTI. For the synthetic signals, there were AMURA measures with similar quantification to DTI, while other showed similar behavior. These findings suggest that AMURA presents favorable characteristics to identify differences of specific microstructural properties between clinical groups in regions with complex fiber architecture and lower dependency on the sample size or assessing technique than DTI.

Causal relationships between migraine and microstructural white matter: a Mendelian randomization study

BACKGROUND

Migraine is a disabling neurological disorder with the pathophysiology yet to be understood. The microstructural alteration in brain white matter (WM) has been suggested to be related to migraine in recent studies, but these evidence are observational essentially and cannot infer a causal relationship. The present study aims to reveal the causal relationship between migraine and microstructural WM using genetic data and Mendelian randomization (MR).

METHODS

We collected the Genome-wide association study (GWAS) summary statistics of migraine (48,975 cases / 550,381 controls) and 360 WM imaging-derived phenotypes (IDPs) (31,356 samples) that were used to measure microstructural WM. Based on instrumental variables (IVs) selected from the GWAS summary statistics, we conducted bidirectional two-sample MR analyses to infer bidirectional causal associations between migraine and microstructural WM. In forward MR analysis, we inferred the causal effect of microstructural WM on migraine by reporting the odds ratio (OR) that quantified the risk change of migraine for per 1 standard deviation (SD) increase of IDPs. In reverse MR analysis, we inferred the causal effect of migraine on microstructural WM by reporting the β value that represented SDs of changes in IDPs were caused by migraine.

RESULTS

Three WM IDPs showed significant causal associations (p < 3.29 × 10- 4, Bonferroni correction) with migraine and were proved to be reliable via sensitivity analysis. The mode of anisotropy (MO) of left inferior fronto-occipital fasciculus (OR = 1.76, p = 6.46 × 10- 5) and orientation dispersion index (OD) of right posterior thalamic radiation (OR = 0.78, p = 1.86 × 10- 4) exerted significant causal effects on migraine. Migraine exerted a significant causal effect on the OD of left superior cerebellar peduncle (β = - 0.09, p = 2.78 × 10- 4).

CONCLUSIONS

Our findings provided genetic evidence for the causal relationships between migraine and microstructural WM, bringing new insights into brain structure for the development and experience of migraine.

Pathophysiology of Chronic Migraine: Insights from Recent Neuroimaging Research

PURPOSE OF REVIEW

Chronic migraine (CM) is a highly disabling primary headache disorder with a substantial impact on patients' quality of life. Episodic migraine (EM) and CM are dynamic states; CM usually evolves from EM alongside increased headache frequency, comorbidities, and medication overuse, supporting the notion that migraine is a spectrum disorder. This narrative review aims to summarize neuroimaging studies to better understand the pathophysiology of CM.

RECENT FINDINGS

Positron emission tomography studies have revealed abnormal energy metabolism and metabolic changes in the dorsal rostral pons in individuals with CM, suggesting that this structure has a key role in the pathophysiology of migraine generation and chronification. Magnetic resonance spectroscopy studies have suggested that thalamocortical pathway dysfunction may contribute to migraine chronification, while functional magnetic resonance imaging studies have highlighted that hypothalamic activity may be involved. Recent evidence highlights functional and structural alterations in cortical and subcortical pain-related brain regions in patients with CM. Whether these functional and structural abnormalities of the brain cause migraine chronification or are a consequence of repeated attacks is still debated. In the future, imaging patterns that predict the transformation from EM to CM should be identified.

Reframing postconcussional syndrome as an interface disorder of neurology, psychiatry and psychology

Persistent symptoms following a minor head injury can cause significant morbidity, yet the underlying mechanisms for this are poorly understood. The shortcomings of the current terminology that refer to non-specific symptom clusters is discussed. This update considers the need for a multi-dimensional approach for the heterogenous mechanisms driving persistent symptoms after mild traumatic brain injury. Relevant pathophysiology is discussed to make the case for mild traumatic brain injury to be conceptualized as an interface disorder spanning neurology, psychiatry and psychology. The relevance of pre-injury factors, psychological co-morbidities and their interaction with the injury to produce persistent symptoms are reviewed. The interplay with psychiatric diagnoses, functional and somatic symptom disorder presentations and the influence of the medicolegal process is considered. The judicious use and interpretation of investigations given the above complexity is discussed, with suggestions of how the explanation of the diagnostic formulation to the patient can be tailored, including insight into the above processes, to aid recovery. Moving beyond the one-dimensional concept of 'postconcussional syndrome' and reframing the cause of persistent symptoms following mild traumatic brain injury in a bio-psycho-socio-ecological model will hopefully improve understanding of the underlying contributory mechanistic interactions and facilitate treatment.

Microstructural white matter alterations associated with migraine headaches: a systematic review of diffusion tensor imaging studies

The pathophysiology of migraine as a headache disorder is still undetermined. Diffusion tensor imaging (DTI) has significantly improved our knowledge about brain microstructure in this disease. Here, we aimed to systematically review DTI studies in migraine and survey the sources of heterogeneity by investigating diffusion parameter changes associated with clinical characteristics and migraine subtypes. Microstructural changes, as revealed by widespread alteration of diffusion metrics in white matter (WM) tracts, subcortical and cortical regions, were reported by several migraine DTI studies. Specifically, we reported changes in the corpus callosum, thalamic radiations, corona radiata, and brain stem. These alterations showed high variability across migraine cycle phases. Additionally, migraine associated with depressive/anxiety symptoms revealed significant changes in the corpus callosum, internal capsule, and superior longitudinal fasciculus. No significant WM microstructural differences were observed between migraine patients with and without aura. Overall, differences between chronic and episodic migraine showed inconsistency across studies. Migraine is associated with microstructural changes in widespread regions including thalamic radiations, corpus callosum, and brain stem. These alterations can highlight neuronal damage and neuronal plasticity mechanisms either following pain stimulations occurring in migraine cycle or as a compensatory response to pain in chronic migraine. Longitudinal studies applying advanced modalities may shed new light on the underlying microstructural changes in migraine subtypes.

Diffusion tensor magnetic resonance imaging: is it valuable in the detection of brain microstructural changes in patients having migraine without aura?

Purpose

The aim of this study is to assess the diagnostic value of diffusion tensor magnetic resonance imaging (MRI) in the detection of brain microstructural changes in patients having migraine without aura.

Material and methods

Our prospective study included 33 patients having migraine without aura and 15 volunteers with matched age and sex, who underwent brain MRI with diffusion tensor imaging (DTI). The fractional anisotropy (FA) and mean diffusivity (MD) of selected grey and white matter regions on both sides were measured and correlated with the neurological clinical examination.

Results

Significant differences were detected in MD values in the thalamus, globus pallidus, and hippocampus head on the right side of patients versus controls. Also, significant differences of the FA values were detected in the thalamus, globus pallidus, and hippocampus head on the right side of patients versus controls. Regarding the FA values of the same regions on the left side, a significant difference in the FA value was detected only in the hippocampus head. There was a statistically significant difference in the FA values on both sides of the white matter of the frontal lobes, posterior limbs of the internal capsules, and cerebellar hemispheres in patients compared to controls. There was a statistically significant difference in MD values in the white matter of both frontal lobes, posterior limb of the right internal capsule, and both cerebellar hemispheres in patients compared to controls.

Conclusions

DTI can detect microstructural changes of the grey and white matter in patients having migraine without aura that could not be detected by conventional MRI.

Widespread White Matter Alterations in Patients With Visual Snow Syndrome

Background: Visual snow is considered a disorder of central visual processing resulting in a perturbed perception of constant binocular flickering or pixilation of the whole visual field. The underlying neurophysiological and structural alterations remain elusive. Methods: In this study, we included patients (final n = 14, five dropouts; five females, mean age: 32 years) with visual snow syndrome (VSS) and age- and sex-matched controls (final n = 20, 6 dropouts, 13 females, mean age: 28.2 years). We applied diffusion tensor imaging to examine possible white matter (WM) alterations in patients with VSS. Results: The patient group demonstrated higher (p-corrected < 0.05, adjusted for age and sex) fractional anisotropy (FA) and lower mean diffusivity (MD) and radial diffusivity (RD) compared to controls. These changes were seen in the prefrontal WM (including the inferior fronto-occipital fascicle), temporal and occipital WM, superior and middle longitudinal fascicle, and sagittal stratum. When additionally corrected for migraine or tinnitus-dominant comorbidities in VSS-similar group differences were seen for FA and RD, but less pronounced. Conclusions: Our results indicate that patients with VSS present WM alterations in parts of the visual cortex and outside the visual cortex. As parts of the inferior fronto-occipital fascicle and sagittal stratum are associated with visual processing and visual conceptualisation, our results suggest that the WM alterations in these regions may indicate atypical visual processing in patients with VSS. Yet, the frequent presence of migraine and other comorbidities such as tinnitus in VSS makes it difficult to attribute WM disruptions solely to VSS.

Altered trigeminothalamic spontaneous low-frequency oscillations in migraine without aura: a resting-state fMRI study

Background

Recent resting-state fMRI studies demonstrated functional dysconnectivity within the central pain matrix in migraineurs. This study aimed to investigate the spatial distribution and amplitude of low-frequency oscillations (LFOs) using fractional amplitude of low-frequency fluctuation (fALFF) analysis in migraine patients without aura, and to examine relationships between regional LFOs and clinical variables.

Methods

Resting-state fMRI data were obtained and preprocessed in 44 migraine patients without aura and 31 matched controls. fALFF was computed according to the original method, z-transformed for standardization, and compared between migraineurs and controls. Correlation analysis between regional fALFF and clinical variables was performed in migraineurs as well.

Results

Compared with controls, migraineurs had significant fALFF increases in bilateral ventral posteromedial (VPM) thalamus and brainstem encompassing rostral ventromedial medulla (RVM) and trigeminocervical complex (TCC). Regional fALFF values of bilateral VPM thalamus and brainstem positively correlated with disease duration, but not with migraine attack frequency or Migraine Disability Assessment Scale score.

Conclusions

We have provided evidence for abnormal LFOs in the brainstem including RVM/TCC and thalamic VPM nucleus in migraine without aura, implicating trigeminothalamic network oscillations in migraine pathophysiology. Our results suggest that enhanced LFO activity may underpin the interictal trigeminothalamic dysrhythmia that could contribute to the impairments of pain transmission and modulation in migraine. Given our finding of increasing fALFF in relation to increasing disease duration, the observed trigeminothalamic dysrhythmia may indicate either an inherent pathology leading to migraine headaches or a consequence of repeated attacks on the brain.

Altered brain structural topological properties and its correlations with clinical characteristics in episodic migraine without aura

PURPOSE

To investigate the topological alterations of the whole-brain white matter structural networks in episodic migraine (EM) without aura.

METHODS

Forty-five EM patients without aura and 35 age- and sex-matched healthy controls were registered, and underwent diffusion tensor MRI acquisition at interictal. Graph theory-based analyses were then performed for the characterization of brain structural network properties. Pearson correlation analysis was performed on each network metric between the EM patients and healthy controls.

RESULTS

The EM patients exhibited abnormal global network properties and local network topology that were characterized by more strongly integrated, more efficient, and faster information transferring. These network differences were widely located in the occipital, temporal, and parietal regions. Additionally, the local efficient of global parameters showed positive correlation with visual analogue scale, and along with prolonging disease duration, the nodal efficiency would be reduced, and the nodal shortest path length would be increased. Headache Impact Test version 6 scores have negative correlation with the nodal shortest path length, and positive correlations with the nodal efficiency.

CONCLUSION

The results indicate that EM patients had aberrant topological structure and make a better understanding of structural connectivity in EM; it may provide imaging evidence for clinical study of migraine pathogenesis.

Distinguishing persistent post-traumatic headache from migraine: Classification based on clinical symptoms and brain structural MRI data

BACKGROUND

Persistent post-traumatic headache most commonly has symptoms that overlap those of migraine. In some cases, it can be clinically difficult to differentiate persistent post-traumatic headache with a migraine phenotype from migraine. The objective of this study was to develop a classification model based on questionnaire data and structural neuroimaging data that distinguishes individuals with migraine from those with persistent post-traumatic headache.

METHODS

Questionnaires assessing headache characteristics, sensory hypersensitivities, cognitive functioning, and mood, as well as T1-weighted magnetic resonance imaging and diffusion tensor data from 34 patients with migraine and 48 patients with persistent post-traumatic headache attributed to mild traumatic brain injury were included for analysis. The majority of patients with persistent post-traumatic headache had a migraine/probable migraine phenotype (77%). A machine-learning leave-one-out cross-validation algorithm determined the average accuracy for distinguishing individual migraine patients from individual patients with persistent post-traumatic headache.

RESULTS

Based on questionnaire data alone, the average classification accuracy for determining whether an individual person had migraine or persistent post-traumatic headache was 71.9%. Adding imaging data features to the model improved the classification accuracy to 78%, including an average accuracy of 97.1% for identifying individual migraine patients and an average accuracy of 64.6% for identifying individual patients with persistent post-traumatic headache. The most important clinical features that contributed to the classification accuracy included questions related to anxiety and decision making. Cortical brain features and fibertract data from the following regions or tracts most contributed to the classification accuracy: Bilateral superior temporal, inferior parietal and posterior cingulate; right lateral occipital, uncinate, and superior longitudinal fasciculus. A post-hoc analysis showed that compared to incorrectly classified persistent post-traumatic headache patients, those who were correctly classified as having persistent post-traumatic headache had more severe physical, autonomic, anxiety and depression symptoms, were more likely to have post-traumatic stress disorder, and were more likely to have had mild traumatic brain injury attributed to blasts.

DISCUSSION

A classification model that included a combination of questionnaire data and structural imaging parameters classified individual patients as having migraine versus persistent post-traumatic headache with good accuracy. The most important clinical measures that contributed to the classification accuracy included questions on mood. Regional brain structures and fibertracts that play roles in pain processing and pain integration were important brain features that contributed to the classification accuracy. The lower classification accuracy for patients with persistent post-traumatic headache compared to migraine may be related to greater heterogeneity of patients in the persistent post-traumatic headache cohort regarding their traumatic brain injury mechanisms, and physical, emotional, and cognitive symptoms.

The Usefulness of Diffusion Tensor Tractography in Diagnosing Neuropathic Pain: A Narrative Review

Diffusion tensor tractography (DTT) is derived from diffusion tensor imaging. It has allowed visualization and estimation of neural tract injury, which may be associated with the pathogenesis of neuropathic pain (NP). The aim of the present study was to review DTT studies that demonstrated the relationship between neural injuries and NP and to describe the potential use of DTT in the evaluation of neural injuries that are involved in the pathophysiological process of NP. A PubMed search was conducted for articles published until July 3, 2020, which used DTT to investigate the association between neural injuries and NP. The key search phrase for identifying potentially relevant articles was (diffusion tensor tractography AND pain). The following inclusion criteria were applied for article selection: (1) studies involving patients with NP and (2) studies in which DTT was applied for the evaluation of NP. Review articles were excluded. Altogether, 108 potentially relevant articles were identified. After reading the titles and abstracts and assessment of eligibility based on the full-text articles, 46 publications were finally included in our review. The results of the included studies suggested that DTT may be beneficial in identifying the pathophysiological mechanism of NP of various origins including central pain caused by brain injuries, trigeminal neuralgia, sciatica, and some types of headache. Further studies are needed to validate the efficacy of DTT in investigating the pathophysiology of other types of NP.

White Matter Lesions in Migraine

Migraine, the third most common disease worldwide, is a well-known independent risk factor for subclinical focal deep white matter lesions (WMLs), even in young and otherwise healthy individuals with no cardiovascular risk factors. These WMLs are more commonly seen in migraine patients with transient neurologic symptoms preceding their headaches, the so-called aura, and those with a high attack frequency. The pathophysiology of migraine-related deep white matter hyperintensities remains poorly understood despite their prevalence. Characteristic differences in their distribution related to chronic small vessel ischemic disease compared with that of common periventricular WMLs in the elderly suggest a different underlying mechanism. Both ischemic and inflammatory mechanisms have been proposed, as there is increased cerebral vulnerability to ischemia in migraineurs, whereas there is also evidence of blood-brain barrier disruption with associated release of proinflammatory substances during migraine attacks. An enhanced susceptibility to spreading depolarization, the electrophysiological event underlying migraine, may be the mechanism that causes repetitive episodes of cerebral hypoperfusion and neuroinflammation during migraine attacks. WMLs can negatively affect both physical and cognitive function, underscoring the public health importance of migraine, and suggesting that migraine is an important contributor to neurologic deficits in the general population.

Approximation to pain-signaling network in humans by means of migraine

Nociceptive signals are processed within a pain-related network of the brain. Migraine is a rather specific model to gain insight into this system. Brain networks may be described by white matter tracts interconnecting functionally defined gray matter regions. Here, we present an overview of the migraine-related pain network revealed by this strategy. Based on diffusion tensor imaging data from subjects in the Human Connectome Project (HCP) database, we used a global tractography approach to reconstruct white matter tracts connecting brain regions that are known to be involved in migraine-related pain signaling. This network includes an ascending nociceptive pathway, a descending modulatory pathway, a cortical processing system, and a connection between pain-processing and modulatory areas. The insular cortex emerged as the central interface of this network. Direct connections to visual and auditory cortical association fields suggest a potential neural basis of phono- or photophobia and aura phenomena. The intra-axonal volume (Vintra ) as a measure of fiber integrity based on diffusion microstructure was extracted using an innovative supervised machine learning approach in form of a Bayesian estimator. Self-reported pain levels of HCP subjects were positively correlated with tract integrity in subcortical tracts. No correlation with pain was found for the cortical processing systems.

Alternative Microstructural Measures to Complement Diffusion Tensor Imaging in Migraine Studies with Standard MRI Acquisition

The white matter state in migraine has been investigated using diffusion tensor imaging (DTI) measures, but results using this technique are conflicting. To overcome DTI measures, we employed ensemble average diffusion propagator measures obtained with apparent measures using reduced acquisitions (AMURA). The AMURA measures were return-to-axis (RTAP), return-to-origin (RTOP) and return-to-plane probabilities (RTPP). Tract-based spatial statistics was used to compare fractional anisotropy, mean diffusivity, axial diffusivity and radial diffusivity from DTI, and RTAP, RTOP and RTPP, between healthy controls, episodic migraine and chronic migraine patients. Fifty healthy controls, 54 patients with episodic migraine and 56 with chronic migraine were assessed. Significant differences were found between both types of migraine, with lower axial diffusivity values in 38 white matter regions and higher RTOP values in the middle cerebellar peduncle in patients with a chronic migraine (p < 0.05 family-wise error corrected). Significantly lower RTPP values were found in episodic migraine patients compared to healthy controls in 24 white matter regions (p < 0.05 family-wise error corrected), finding no significant differences using DTI measures. The white matter microstructure is altered in a migraine, and in chronic compared to episodic migraine. AMURA can provide additional results with respect to DTI to uncover white matter alterations in migraine.

Changes in Empathy in Patients With Chronic Low Back Pain: A Structural-Functional Magnetic Resonance Imaging Study

Objective: Many pieces of research have focused on pain within individuals, but little attention has been paid to whether pain can change an individual’s empathic ability and affect social relationships. The purpose of this study is to explore how chronic low back pain changes empathy.

Methods: Twenty-four chronic low back pain patients and 22 healthy controls were recruited. We set up an experimental pain-exposed model for each healthy subject. All subjects received a painful-empathic magnetic resonance scan. After the scan, all subjects rated the pain intensity and multiple empathy-related indicators. The clinical assessment scale was the 20-item Basic Empathy Scale in Adults.

Result: The chronic low back pain patients reported lower scores on the total scores of BES-A, the subscale scores of emotional disconnection and cognitive empathy, and the discomfort rating. The fMRI results in the chronic low back pain patients showed that there were multiple abnormal brain pathways centered on the anterior insula. The DTI results in the chronic low back pain patients showed that there were reduced fractional anisotropy values in the corpus callosum, bilateral anterior thalamic radiation (ATR), right posterior thalamic radiation (PTR), right superior longitudinal fasciculus (SLF), and left anterior corona radiate (ACR).

Conclusion: Our study found that patients with chronic low back pain have impaired empathy ability. The abnormal functional connectivity of multiple brain networks, multiple damaged white matter tracts, and the lower behavioral scores in chronic low back pain patients supported our findings.

Magnetic Resonance Imaging in Pediatric Migraine

This literature review provides an overview of the research using magnetic resonance imaging (MRI) in pediatric migraine and compares findings with the adult migraine literature. A literature search using PubMed was conducted using all relevant sources up to February 2019. Using MRI methods to categorize and explain pediatric migraine in comparison with adult migraine is important, in order to recognize and appreciate the differences between the two entities, both clinically and physiologically. We aim to demonstrate the differences and similarities between pediatric and adult migraine using data from white matter and gray matter structural studies, cerebral perfusion, metabolites, and functional MRI (fMRI) studies, including task-based and resting-state blood oxygen level-dependent studies. By doing this we identify areas that need further research, as well as possible areas where intervention could alter outcomes.

Individual differences of maladaptive brain changes in migraine and their relationship with differential effectiveness of treatments

Migraine is a difficult disorder to identify with regard to its pathophysiological mechanisms, and its treatment has been primarily difficult owing to interindividual differences. Substantial rates of nonresponsiveness to medications are common, making migraine treatment complicated. In this review, we systematically analyzed recent studies concerning neuroimaging findings regarding the neurophysiology of migraine. We linked the current imaging research with anecdotal evidence from interindividual factors such as duration and pain intensity of migraine, age, gender, hormonal interplay, and genetics. These factors suggested the use of nonpharmacological therapies such as transcranial magnetic stimulation, transcranial direct current stimulation, and placebo therapy for the treatment of migraine. Finally, we discussed how interindividual differences are related to such nondrug treatments.

White matter and cerebellar involvement in alternating hemiplegia of childhood

OBJECTIVE

To determine whether brain volumetric and white matter microstructural changes are present and correlate with neurological impairment in subjects with alternating hemiplegia of childhood (AHC).

METHODS

In this prospective single-center study, 12 AHC subjects (mean age 22.9 years) and 24 controls were studied with 3DT1-weighted MR imaging and high angular resolution diffusion imaging at 3T. Data obtained with voxel-based morphometry and tract-based spatial statistics were correlated with motor impairment using the International Cooperative Ataxia Rating Scale (ICARS) and Movement and Disability sub-scales of Burke-Fahn-Marsden Dystonia Rating Scale (BFMMS and BFMDS).

RESULTS

Compared to healthy controls, AHC subjects showed lower total brain volume (P < 0.001) and white matter volume (P = 0.002), with reduced clusters of white matter in frontal and parietal regions (P < 0.001). No significant regional differences were found in cortical or subcortical grey matter volumes. Lower cerebellar subvolumes correlated with worse ataxic symptoms and global motor impairment in AHC group (P < 0.001). Increased mean and radial diffusivity values were found in the corpus callosum, corticospinal tracts, superior and inferior longitudinal fasciculi, subcortical frontotemporal white matter, internal and external capsules, and optic radiations (P < 0.001). These diffusion scalar changes correlated with higher ICARS and BFMDS scores (P < 0.001).

INTERPRETATION

AHC subjects showed prevalent white matter involvement, with reduced volume in several cerebral and cerebellar regions associated with widespread microstructural changes reflecting secondary myelin injury rather than axonal loss. Conversely, no specific pattern of grey matter atrophy emerged. Lower cerebellar volumes, correlating with severity of neurological manifestations, seems related to disrupted developmental rather than neurodegenerative processes.

White matter changes in chronic and episodic migraine: a diffusion tensor imaging study

BACKGROUND

White matter alterations have been observed in patients with migraine. However, no microstructural white matter alterations have been found particularly in episodic or chronic migraine patients, and there is limited research focused on the comparison between these two groups of migraine patients.

METHODS

Fifty-one healthy controls, 55 episodic migraine patients and 57 chronic migraine patients were recruited and underwent brain T1-weighted and diffusion-weighted MRI acquisition. Using Tract-Based Spatial Statistics (TBSS), fractional anisotropy, mean diffusivity, radial diffusivity and axial diffusivity were compared between the different groups. On the one hand, all migraine patients were compared against healthy controls. On the other hand, patients from each migraine group were compared between them and also against healthy controls. Correlation analysis between clinical features (duration of migraine in years, time from onset of chronic migraine in months, where applicable, and headache and migraine frequency, where applicable) and Diffusion Tensor Imaging measures was performed.

RESULTS

Fifty healthy controls, 54 episodic migraine and 56 chronic migraine patients were finally included in the analysis. Significant decreased axial diffusivity (p < .05 false discovery rate and by number of contrasts corrected) was found in chronic migraine compared to episodic migraine in 38 white matter regions from the Johns Hopkins University ICBM-DTI-81 White-Matter Atlas. Significant positive correlation was found between time from onset of chronic migraine and mean fractional anisotropy in the bilateral external capsule, and negative correlation between time from onset of chronic migraine and mean radial diffusivity in the bilateral external capsule.

CONCLUSIONS

These findings suggest global white matter structural differences between episodic migraine and chronic migraine. Patients with chronic migraine could present axonal integrity impairment in the first months of chronic migraine with respect to episodic migraine patients. White matter changes after the onset of chronic migraine might reflect a set of maladaptive plastic changes.

Structural connectivity alterations in chronic and episodic migraine: A diffusion magnetic resonance imaging connectomics study

OBJECTIVE

To identify possible structural connectivity alterations in patients with episodic and chronic migraine using magnetic resonance imaging data.

METHODS

Fifty-four episodic migraine, 56 chronic migraine patients and 50 controls underwent T1-weighted and diffusion-weighted magnetic resonance imaging acquisitions. Number of streamlines (trajectories of estimated fiber-tracts), mean fractional anisotropy, axial diffusivity and radial diffusivity were the connectome measures. Correlation analysis between connectome measures and duration and frequency of migraine was performed.

RESULTS

Higher and lower number of streamlines were found in connections involving regions like the superior frontal gyrus when comparing episodic and chronic migraineurs with controls (p < .05 false discovery rate). Between the left caudal anterior cingulate and right superior frontal gyri, more streamlines were found in chronic compared to episodic migraine. Higher and lower fractional anisotropy, axial diffusivity, and radial diffusivity were found between migraine groups and controls in connections involving regions like the hippocampus. Lower radial diffusivity and axial diffusivity were found in chronic compared to episodic migraine in connections involving regions like the putamen. In chronic migraine, duration of migraine was positively correlated with fractional anisotropy and axial diffusivity.

CONCLUSIONS

Structural strengthening of connections involving subcortical regions associated with pain processing and weakening in connections involving cortical regions associated with hyperexcitability may coexist in migraine.

Fluctuating Regional Brainstem Diffusion Imaging Measures of Microstructure across the Migraine Cycle

The neural mechanisms responsible for the initiation and expression of migraines remain unknown. Although there is growing evidence of changes in brainstem anatomy and function between attacks, very little is known about brainstem function and structure in the period immediately prior to a migraine. The aim of this investigation is to use brainstem-specific analyses of diffusion weighted images to determine whether the brainstem pain processing regions display altered structure in individuals with migraine across the migraine cycle, and in particular immediately prior to a migraine. Diffusion tensor images (29 controls, 36 migraineurs) were used to assess brainstem anatomy in migraineurs compared with controls. We found that during the interictal phase, migraineurs displayed greater mean diffusivity (MD) in the region of the spinal trigeminal nucleus (SpV), dorsomedial pons (dmPons)/dorsolateral pons (dlPons), and midbrain periaqueductal gray matter (PAG)/cuneiform nucleus (CNF). Remarkably, the MD returned to controls levels during the 24-h period immediately prior to a migraine, only to increase again within the three following days. Additionally, fractional anisotropy (FA) was significantly elevated in the region of the medial lemniscus/ventral trigeminal thalamic tract in migraineurs compared with controls over the entire migraine cycle. These data show that regional brainstem anatomy changes over the migraine cycle, with specific anatomical changes occurring in the 24-h period prior to onset. These changes may contribute to the activation of the ascending trigeminal pathway by either an increase in basal traffic or by sensitizing the trigeminal nuclei to external triggers, with activation ultimately resulting in perception of head pain during a migraine attack.

Diffusion tensor imaging in middle-aged headache sufferers in the general population: a cross-sectional population-based imaging study in the Nord-Trøndelag health study (HUNT-MRI)

BACKGROUND

Several studies have investigated white matter with diffusion tensor imaging (DTI) in those suffering from headache, but so far only in clinic based samples and with conflicting results.

METHODS

In the present study, 1006 individuals (50-66 years) from the general population (Nord-Trøndelag Health Study) participated in an imaging study of the head at 1.5 T (HUNT-MRI). Hundred and ninety-six individuals were excluded because of errors in the data acquisition or brain pathology. Two hundred and forty-six of the remaining participants reported suffering from headache (69 from migraine and 76 from tension-type headache) the year prior to the scanning. DTI data were analysed with Tract-Based Spatial Statistics and automated tractography. Type of headache, frequency of attacks and evolution of headache were investigated for an association with white matter fractional anisotropy (FA), mean diffusivity (MD), axonal diffusivity (AD), radial diffusivity (RD) and tract volume. Correction for various demographical and clinical variables were performed.

RESULTS

Headache sufferers had widespread higher white matter MD, AD and RD compared to headache free individuals (n = 277). The effect sizes were mostly small with the largest seen in those with middle-age onset headache, who also had lower white matter FA. There were no associations between white matter microstructure and attack frequency or type of headache.

CONCLUSION

Middle-age onset headache may be related to a widespread process in the white matter leading to altered microstructure.

Differences in fibertract profiles between patients with migraine and those with persistent post-traumatic headache

Objectives

Often, persistent post-traumatic headache and migraine are phenotypically similar. However, the similarities and differences in the neuropathological underpinnings of persistent post-traumatic headache and migraine require further understanding. We used diffusion tensor imaging (DTI) and a novel method for detecting subtle changes in fibertract integrity by measuring node-by-node parameters along each tract to compare fibertract profiles between those with migraine and those with persistent post-traumatic headache, and compared both cohorts to a group of controls.

Methods

Eighteen fibertracts were reconstructed for 131 subjects, including 49 patients with persistent post-traumatic headache attributed to mild traumatic brain injury, 41 with migraine, and 41 controls. Node-by-node diffusion parameters of mean diffusivity and radial diffusivity were calculated along each tract. Mean diffusivity and radial diffusivity measurements were averaged along quartiles of each tract for statistical interpretation and group comparison. Using a post-hoc analysis, correlations between tract quartile measurements and headache frequency were calculated.

Results

There were significant differences between migraine and persistent post-traumatic headache cohorts for quartile measurements of mean diffusivity or radial diffusivity in the bilateral anterior thalamic radiations, cingulum (angular bundles and cingulate gyri), inferior longitudinal fasciculi, and uncinate fasciculi, the left corticospinal tract, and the right superior longitudinal fasciculi-parietal portion. For migraine patients, there was a significant positive correlation between headache frequency and forceps major mean diffusivity, whereas for persistent post-traumatic headache there was a positive correlation between headache frequency and cingulum angular bundle mean diffusivity and radial diffusivity.

Conclusions

Quartile measurements of radial diffusivity and mean diffusivity indicate unique differences in fibertract profiles between those with migraine vs. persistent post-traumatic headache. Although for both migraine and persistent post-traumatic headache there was a positive relationship between fibertract alterations and headache frequency, there were disease-specific differences between headache frequency and fibertract injury patterns. These findings might suggest potential differences in the neuropathological mechanisms underlying migraine and persistent post-traumatic headache.

Relation between migraine pattern and white matter hyperintensities in brain magnetic resonance imaging

Background

Migraine is a common disorder in general population. Presence of white matter hyperintensities (WMHs) in brain MRI of migraine patients was not studied clearly. Detection of the prevalence of white matter hyperintensities in migraine patients determines its correlation with migraine severity, type and duration.

Methods

Cross sectional analytic study was conducted on migraine patients attending neurology clinic Suez Canal University Hospital. Sixty-five patients with migraine aged from 18 to 50 years were included. We excluded smokers and patients with hypertension, cardiac disease, diabetes mellitus, endocrine dysfunction, oncological and hematological diseases, infectious diseases, demyelinating disorders, and Alzheimer disease. Brain MRI and laboratory investigation was done for all patients.

Results

White matter hyperintensities were significant more frequent in migraine with aura than those without aura. According to MIGSEV scale, white matter hyperintensities were highly significantly more frequent in grade III severity than grades II and I. The number of white matter hyperintensities increases significantly with increase intensity of pain during attack. The number of white matter hyperintensities increases significantly with increase intensity of nausea, disability, tolerability during attack and age. Resistance to treatment also shows statistically significant difference in increase number of WMHs.

Conclusions

White matter hyperintensities are present in 43.1% of migraine patients. Age, presence of aura, nausea, disability during attack, resistance to treatment, and severity of headache and duration of migraine are considered a risk factor for development of white matter hyperintensities.

Migraine with aura and white matter tract changes

We aimed to explore whether a migraine with aura (MA) is associated with structural changes in tracts of a white matter and to compare parameters of diffusivity between subgroups in migraineurs. Forty-three MA and 20 healthy subjects (HS), balanced by sex and age, were selected for this study. Analysis of diffusion tensor parameters was used to identify differences between MA patients and HS, and then between MA subgroups. A diffusion tensor probabilistic tractography analysis showed that there is no difference between MA patients and HS. However, using more-liberal uncorrected statistical threshold, we noted a trend in MA patients toward lower diffusivity indices of selected white matter tracts located in the forceps minor and right anterior thalamic radiation (ATR), superior longitudinal fasciculus (temporal part) (SLFT), cingulum-cingulate tract, and left uncinate fasciculus. Migraineurs who experienced somatosensory and dysphasic aura, besides visual symptoms, had tendency toward lower diffusivity indices, relative to migraineurs who experienced only visual symptoms, in the right inferior longitudinal fasciculus, forceps minor, and right superior longitudinal fasciculus (parietal part), SLFT, and cingulum-angular bundle. Aura frequency were negatively correlated with axial diffusivity and mean diffusivity of the right ATR (partial correlation = - 0.474; p = 0.002; partial correlation = - 0.460; p = 0.002), respectively. There were no significant differences between MA patients and HS, neither between MA subgroups. Migraineurs with abundant symptoms during the aura possibly have more myelinated fibers relative to those who experience only visual symptoms. Lower diffusivity indices of the right ATR are linked to more frequent migraine with aura attacks.

Advances in migraine neuroimaging and clinical utility: from the MRI to the bedside

INTRODUCTION

In current migraine clinical practice, no specific diagnostic investigations are available and therefore the diagnosis is an eminently clinical process where instrumental examinations may have a part to exclude possible causes of secondary headaches. While migraine clinical phenotype has been widely characterized, migraine pathophysiology has still a gap that might be partly bridged by structural and functional neuroimaging investigations. Areas covered: This article aims to review the recent advances in functional neuroimaging, the consequent progress in the knowledge of migraine pathophysiology and their putative application and impact in the clinical setting. A comprehensive review was conducted of PubMed citations by entering the key word 'MRI' combined with 'migraine' AND/OR 'headache.' Other key words included 'gray matter' OR 'white matter,' 'structural' OR 'functional.' The only restriction was English-language publication. The abstracts of all articles meeting these criteria were reviewed, and full texts were examined for relevant references. Expert commentary: Advanced magnetic resonance imaging (MRI) techniques are tremendously improving our knowledge about brain abnormalities in migraine patients. However, advanced MRI could nowadays overcome the limits linked to the clinicians' judgment through the identification of objectively measurable neuroimaging findings (quantitative biomarkers) concerning the diagnosis, the prognosis and 'tailored' therapeutic-care pathways.

Evidence for Plastic Processes in Migraine with Aura: A Diffusion Weighted MRI Study

Background: Formerly white matter abnormalities in a mixed group of migraine patients with and without aura were shown. Here, we aimed to explore white matter alterations in a homogeneous group of migraineurs with aura and to delineate possible relationships between white matter changes and clinical variables.

Methods: Eighteen patients with aura, 25 migraine patients without aura and 28 controls were scanned on a 1.5T MRI scanner. Diffusivity parameters of the white matter were estimated and compared between patients’ groups and controls using whole-brain tract-based spatial statistics.

Results: Decreased radial diffusivity (p < 0.036) was found bilaterally in the parieto-occipital white matter, the corpus callosum, and the cingular white matter of migraine with aura (MwA) patients compared to controls. Migraine without aura (MwoA) patients showed no alteration compared to controls. MwA compared to MwoA showed increased fractional anisotropy (p < 0.048) in the left parieto-occipital white matter. In MwA a negative correlation was found between axial diffusivity and disease duration in the left superior longitudinal fascicle (left parieto-occipital region) and in the left corticospinal tract (p < 0.036) and with the number of the attacks in the right superior longitudinal fascicle (p < 0.048).

Conclusion: We showed for the first time that there are white matter microstructural differences between these two subgroups of migraine and hence it is important to handle the two groups separately in further researches. We propose that degenerative and maladaptive plastic changes coexist in the disease and the diffusion profile is a result of these processes.

Lower inhibitory control interacts with greater pain catastrophizing to predict greater pain intensity in women with migraine and overweight/obesity

BACKGROUND

Pain catastrophizing (PC) is associated with more severe and disabling migraine attacks. However, factors that moderate this relationship are unknown. Failure of inhibitory control (IC), or the ability to suppress automatic or inappropriate responses, may be one such factor given previous research showing a relationship between higher PC and lower IC in non-migraine samples, and research showing reduced IC in migraine. Therefore, we examined whether lower IC interacts with increased PC to predict greater migraine severity as measured by pain intensity, attack frequency, and duration.

METHODS

Women (n = 105) aged 18-50 years old (M = 38.0 ± 1.2) with overweight/obesity and migraine who were seeking behavioral treatment for weight loss and migraine reduction completed a 28-day smartphone-based headache diary assessing migraine headache severity. Participants then completed a modified computerized Stroop task as a measure of IC and self-report measures of PC (Pain Catastrophizing Scale [PCS]), anxiety, and depression. Linear regression was used to examine independent and joint associations of PC and IC with indices of migraine severity after controlling for age, body mass index (BMI) depression, and anxiety.

RESULTS

Participants on average had BMI of 35.1 ± 6.5 kg/m2and reported 5.3 ± 2.6 migraine attacks (8.3 ± 4.4 migraine days) over 28 days that produced moderate pain intensity (5.9 ± 1.4 out of 10) with duration of 20.0 ± 14.2 h. After adjusting for covariates, higher PCS total (β = .241, SE = .14, p = .03) and magnification subscale (β = .311, SE = .51, p < .01) scores were significant independent correlates of longer attack duration. IC interacted with total PCS (β = 1.106, SE = .001, p = .03) rumination (β = 1.098, SE = .001, p = .04), and helplessness (β = 1.026, SE = .001, p = .04) subscale scores to predict headache pain intensity, such that the association between PC and pain intensity became more positive at lower levels of IC.

CONCLUSIONS

Results showed that lower IC interacted with higher PC, both overall and specific subcomponents, to predict higher pain intensity during migraine attacks. Future studies are needed to determine whether interventions to improve IC could lead to less painful migraine attacks via improvements in PC.

The role of migraine headache severity, associated features and interactions with overweight/obesity in inhibitory control

AIM OF THE STUDY

While migraine and obesity are related and both conditions are associated with reduced executive functioning, no study has examined whether obesity exacerbates executive dysfunction in migraine. This cross-sectional study examined whether overweight/obesity moderated associations of migraine severity and associated features with inhibitory control, one aspect of executive function.

MATERIALS AND METHODS

Women (n = 124) aged 18-50 years old with overweight/obesity body mass index (BMI) = 35.1 ± 6.4 kg/m² and migraine completed a 28-day smartphone-based headache diary assessing migraine headache severity (attack frequency, pain intensity) and frequency of associated features (aura, photophobia, phonophobia, nausea). They then completed computerized measures of inhibitory control during an interictal (headache-free) period.

RESULTS

Participants with higher migraine attack frequency performed worse on the Flanker test (accuracy and reaction time; p < .05). Migraine attack frequency and pain intensity interacted with BMI to predict slower Stroop and/or Flanker Reaction Time (RT; p < .05). More frequent photophobia, phonophobia and aura were independently related to slower RT on the Stroop and/or Flanker tests (p < .05), and BMI moderated the relationship between the occurrence of aura and Stroop RT (p = .03).

CONCLUSIONS

Associations of migraine severity and presence of associated features with inhibitory control varied by BMI in overweight/obese women with migraine. These findings warrant consideration of weight status in clarifying the role of migraine in executive functioning.

Increased Amplitude of Thalamocortical Low-Frequency Oscillations in Patients with Migraine

For many years, neurobiological theories have emphasized the importance of neuronal oscillations in the emergence of brain function. At the same time, clinical studies have shown that disturbances or irregularities in brain rhythms may relate to various common neurological conditions, including migraine. Increasing evidence suggests that the CNS plays a fundamental role in the predisposition to develop different forms of headache. Here, we present human imaging data that strongly support the presence of abnormal low-frequency oscillations (LFOs) in thalamocortical networks of patients in the interictal phase of migraine. Our results show that the main source of arrhythmic activity was localized to the higher-order thalamic relays of the medial dorsal nucleus. In addition, spontaneous LFOs in the thalamus were selectively associated with the headache attack frequency, meaning that the varying amplitude of dysrhythmia could predispose patients to recurrent attacks. Rhythmic cortical feedback to the thalamus is a major factor in the amplification of thalamocortical oscillations, making it a strong candidate for influencing neuronal excitability. We further speculate that the intrinsic dynamics of thalamocortical network oscillations are crucial for early sensory processing and therefore could underlie important pathophysiological processes involved in multisensory integration.

SIGNIFICANCE STATEMENT

In many cases, migraine attacks are thought to begin centrally. A major obstacle to studying intrinsic brain activity has been the identification of the precise anatomical structures and functional networks that are involved in migraine. Here, we present imaging data that strongly support the presence of abnormal low-frequency oscillations in thalamocortical networks of patients in the interictal phase of migraine. This arrhythmic activity was localized to the higher-order thalamic relays of the medial dorsal nucleus and was selectively associated with headache attack frequency. Rhythmic cortical feedback to the thalamus is a major factor in the amplification of thalamocortical oscillations, making it a strong candidate for influencing neuronal excitability and higher-level processes involved in multisensory integration.

Migraine Subclassification via a Data-Driven Automated Approach Using Multimodality Factor Mixture Modeling of Brain Structure Measurements

BACKGROUND

The current subclassification of migraine is according to headache frequency and aura status. The variability in migraine symptoms, disease course, and response to treatment suggest the presence of additional heterogeneity or subclasses within migraine.

OBJECTIVE

The study objective was to subclassify migraine via a data-driven approach, identifying latent factors by jointly exploiting multiple sets of brain structural features obtained via magnetic resonance imaging (MRI).

METHODS

Migraineurs (n = 66) and healthy controls (n = 54) had brain MRI measurements of cortical thickness, cortical surface area, and volumes for 68 regions. A multimodality factor mixture model was used to subclassify MRIs and to determine the brain structural factors that most contributed to the subclassification. Clinical characteristics of subjects in each subgroup were compared.

RESULTS

Automated MRI classification divided the subjects into two subgroups. Migraineurs in subgroup #1 had more severe allodynia symptoms during migraines (6.1 ± 5.3 vs. 3.6 ± 3.2, P = .03), more years with migraine (19.2 ± 11.3 years vs 13 ± 8.3 years, P = .01), and higher Migraine Disability Assessment (MIDAS) scores (25 ± 22.9 vs 15.7 ± 12.2, P = .04). There were not differences in headache frequency or migraine aura status between the two subgroups.

CONCLUSIONS

Data-driven subclassification of brain MRIs based upon structural measurements identified two subgroups. Amongst migraineurs, the subgroups differed in allodynia symptom severity, years with migraine, and migraine-related disability. Since allodynia is associated with this imaging-based subclassification of migraine and prior publications suggest that allodynia impacts migraine treatment response and disease prognosis, future migraine diagnostic criteria could consider allodynia when defining migraine subgroups.

Brain structural investigation and hippocampal tractography in medication overuse headache: a native space analysis

BACKGROUND

Spatial normalization of brain images, a prerequisite for voxel based morphometry analysis, may account for the large variability of the volumetric data in medication overuse headache (MOH); possibly because this disease concerns patients differing on both sex and age, and hence with different brain size and shape.

METHODS

The present study aimed at providing a subject-based analysis of macrostructure using a native space volumes segmentation (Freesurfer), and microstructure using a region of interest (ROI: i.e. hippocampus) tractography approach in MOH patients.

RESULTS

The results show that MOH patients had decreased volumes of left hemisphere temporal gyri (temporal superior, fusiform) and occipital middle gyrus, together with an increased volume of the left inferior (temporal) lateral ventricle. The left temporal volume was negatively correlated with depression score and medication dependence parameters. Seed-based tractography of the hippocampus revealed a decreased number of reconstructed fibers passing through the left hippocampus.

CONCLUSION

To our knowledge, these alterations have not been described with methods involving brain normalization, and they indicate that left hemisphere temporal areas, including the hippocampus, may play a role in MOH pathophysiology. Trial registration number NCT00833209. Registered 29 January 2009.