Structural and Functional Reorganization of the Brain in Migraine Without Aura

Quantitative MRI texture analysis of the lateral pterygoid muscle in unilateral temporomandibular joint disorders

BACKGROUND

This study utilized MRI-based texture analysis to quantify structural alterations in the lateral pterygoid muscle (LPM) among MR images with unilateral anterior disc displacement (uADD) of the temporomandibular joint. Retrospective analysis of anonymized MR images from 232 uADD patients and 123 healthy individuals (January 2022- December 2024), approved by the Ethics Committee of Wenzhou Medical University Affiliated School of Stomatology (Ethics Number: WYKQ 2024008) with waived informed consent due to the use of de-identified retrospective data, was conducted to identify diagnostic markers and possible related pathological changes of disc displacement. According to the inclusion and exclusion criteria four groups of MR images were included in this study: the healthy temporomandibular joints (H-TMJ) of individuals with uADD, joints with anterior disc displacement with reduction (ADDwR), joints with anterior disc displacement without reduction (ADDwoR), and MR images from normal volunteers as the healthy group (HG). Four texture parameters were used for analysis: the angular second moment (ASM), Contrast, inverse difference moment (IDM) and Entropy.

RESULTS

Statistically significant differences (P < 0.05) were found between groups for the ASM, Contrast, IDM, and Entropy variables, indicating their potential as diagnostic markers. Additionally, Entropy values differed significantly between the ADDwoR and ADDwR groups (P < 0.05), highlighting its diagnostic potential in distinguishing these two conditions. The severity of ADD disease showed varying degrees of correlation with specific texture parameters, with significant associations observed for ASM, Contrast, IDM, and Entropy (P < 0.05).

CONCLUSIONS

The texture parameters of the LPM exhibit significant changes in MR images with anterior disc displacement(ADD). Notably, the Entropy value of the LPM demonstrates high diagnostic utility in distinguishing ADDwoR from ADDwR, particularly in cases of complex disc displacement involving deformation or remodeling. Furthermore, the severity of ADD disease shows varying degrees of correlation with specific texture parameters. However, further research is required to validate the relationship between numerical texture changes in the LPM and their corresponding pathological alterations.

CLINICAL TRIAL NUMBER

Not applicable.

Common neural correlates of chronic pain - A systematic review and meta-analysis of resting-state fMRI studies

Maladaptive brain plasticity has been reported in chronic pain (CP) conditions, though it remains unclear if there are common alterations across pathologies. Therefore, we systematically synthesized literature comparing resting-state functional magnetic resonance imaging (rs-fMRI) in CP patients and healthy controls (HC), and meta-analyzed data whenever applicable. Separate meta-analyses were performed for each method - (fractional) amplitude of low-frequency fluctuations (fALFF, ALFF), regional homogeneity (ReHo), seed-based connectivity (according to the seed) and independent component analysis (according to the network). In qualitative synthesis, sensory-discriminative pain processing - thalamus, insula, temporal and sensory cortices - and cognitive and emotional processing - cingulate, prefrontal and parietal cortices and precuneus - regions concentrated CP/HC differences. Meta-analyses revealed decreased ALFF and increased ReHo in the precuneus, increased fALFF in the left posterior insula and disrupted within- and cross-network connectivity of default mode network (DMN) nodes, as well as altered connectivity in top-down pain modulation pathways. Specifically, it showed decreased anterior and increased posterior components' representation within DMN, enhanced connectivity between the medial prefrontal cortex (mPFC, part of the DMN) and anterior insula (part of the salience network), and decreased mPFC connectivity with the periaqueductal gray matter (PAG). Collectively, results suggest that CP disrupts the natural functional organization of the brain, particularly impacting DMN nodes (mPFC and precuneus), insula and top-town pain modulation circuits.

Association between patent foramen ovale and migraine: evidence from a resting-state fMRI study

A relationship between migraine without aura (MO) and patent foramen ovale (PFO) has been observed, but the neural basis underlying this relationship remains elusive. Utilizing independent component analysis via functional magnetic resonance imaging, we examined functional connectivity (FC) within and across networks in 146 patients with MO (75 patients with and 71 patients without PFO) and 70 healthy controls (35 patients each with and without PFO) to elucidate the individual effects of MO and PFO, as well as their interaction, on brain functional networks. The main effect of PFO manifested exclusively in the FC among the visual, auditory, default mode, dorsal attention and salience networks. Furthermore, the interaction effect between MO and PFO was discerned in brain clusters of the left frontoparietal network and lingual gyrus network, as well as the internetwork FC between the left frontoparietal network and the default mode network (DMN), the occipital pole and medial visual networks, and the dorsal attention and salience networks. Our findings suggest that the presence of a PFO shunt in patients with MO is accompanied by various FC changes within and across networks. These changes elucidate the intricate mechanisms linked to PFO-associated migraines and provide a basis for identifying novel noninvasive biomarkers.

Revealing the mechanism of central pain hypersensitivity in primary dysmenorrhea: evidence from neuroimaging

Background

Primary dysmenorrhea (PDM) is the most common problem in menstruating women. A number of functional magnetic resonance imaging (fMRI) study have revealed that the brain plays a crucial role in the pathophysiology of PDM. However, these results have been inconsistent, and there is a lack of a comprehensive fMRI study to clarify the onset and long-term effects of PDM. The aim of this study was thus to investigate the onset and long-term effects of PDM in a cohort of patients with PDM.

Methods

This study employed a cross-sectional design with prospective data collection, in which 25 patients with PDM and 20 healthy controls (HCs) were recruited. The patients with PDM underwent fMRI scans both during the PDM during the pain phase (PDM-P) and nonpain phase (PDM-NP). The long-term effects of PDM on the brain was assessed by comparing PDM-NP findings with those of HCs, and the central mechanism of PDM was assessed by comparing the PDM-P findings with those of PDM-NP. To identify changes in brain function, the amplitude of low-frequency fluctuations and the regional homogeneity (ReHo) were measured. To assess changes in brain structure, voxel-based morphometry (VBM) was applied. The periaqueductal gray (PAG) was set as a region of for conducting seed-based whole-brain functional connectivity (FC) analysis. Subsequently, Pearson correlation analyses were employed to evaluate the associations between the abnormal brain region and the clinical information of the patients.

Results

There were neither functional nor structural differences between patients in the PDM-NP and HCs. Compared with those in PDM-NP, those in PDM-P showed increased ReHo in the left dorsolateral prefrontal cortex (DLPFC) but decreased FC between PAG and right superior parietal gyrus, bilateral inferior parietal gyrus, right calcarine gyrus, left superior occipital gyrus, left precentral gyrus, right DLPFC, and left crus I of the cerebellar hemisphere.

Conclusions

The results from this study suggest that the mechanism of central pain hypersensitivity of PDM may be related to the disorder of the FC between the PAG and descending pain modulation system, default mode network (DMN), and occipital lobe. These findings could help us better understand the pathophysiology of PDM from a neuroimaging perspective.

Brain functional connectivity patterns associated with symptoms of vestibular migraine

Background

Several functional magnetic resonance imaging (fMRI) investigations of patients with vestibular migraine (VM) have revealed abnormal functionality in different networks, indicating that VM is related to alterations in brain function. We sought to investigate the resting-state functional connectivity (FC) patterns during the interictal period in VM by combining data-driven voxel-wise degree centrality (DC) calculations and seed-based FC analyses, and thereby determine the associations between cerebral function and clinical symptoms.

Methods

Thirty-eight patients with VM and 33 matched normal controls were recruited. DC was calculated and compared between the groups, and the FC of locations showing DC alterations was further tested using a seed-based technique. The participants' clinical indicators were correlated with the DC and FC values of the brain areas.

Results

In contrast to the control group, the VM group showed considerably lower DC values in the bilateral medial prefrontal cortex (mPFC) and significantly higher DC values in the right occipital lobe. In the seed-based FC analyses, patients with VM demonstrated fewer connections of the bilateral mPFC with the bilateral posterior cingulate cortex, right parahippocampus, right cerebellar posterior lobe, bilateral cuneus, and left precuneus. In addition, clinical data from patients, such as pain intensity, episode frequency, and the Dizziness Handicap Inventory score, were negatively related to these FC and DC impairments.

Conclusion

Our findings showed changes in the default mode network and visual cortex in patients with VM, providing further insights into the complexity of the mechanisms underlying VM.

Arterial Spin Labeling in Migraine: A Review of Migraine Categories and Mimics

Migraine is a complex headache characterized by changes in functional connectivity and cerebral perfusion. The perfusion changes represent a valuable domain for targeted drug therapy. Arterial spin labeling is a noncontrast imaging technique of quantifying cerebral perfusion changes in the migraine setting. In this narrative review, we will discuss the pathophysiology of the different categories of migraine, as defined by the International Classification of Headache Disorders-3 and describe a category-based approach to delineating perfusion changes in migraine on arterial spin labeling images. We will also discuss the use of arterial spin labeling to differentiate migraine from stroke and/or seizures in the adult and pediatric populations. Our systematic approach will help improve the understanding of the complicated vascular changes that occur during migraines and identify potential areas of future research.

Predicting Sumatriptan Responsiveness Based on Structural Connectivity in Patients Newly Diagnosed With Migraine

BACKGROUND AND PURPOSE

We aimed to determine whether structural brain connectivity is significantly associated with the response to sumatriptan in patients with migraine.

METHODS

We retrospectively enrolled patients with newly diagnosed migraine who underwent brain diffusion-tensor imaging (DTI) at the time of diagnosis, with regular follow-up for at least 6 months after the initial diagnosis. Patients were classified into good- and poor-responder groups according to their response to sumatriptan. We analyzed the structural connectivity using DTI by applying graph theory using DSI Studio software.

RESULTS

We enrolled 59 patients (35 good responders and 24 poor responders) and 30 healthy controls. Global structural connectivity differed significantly between patients with migraine and healthy controls, while local structural connectivity differed significantly between good and poor responders. The betweenness centrality was lower in good responders than in poor responders in the left lateral geniculate thalamic nucleus (26.078 vs. 41.371, p=0.039) and right medial mediodorsal magnocellular thalamic nucleus (60.856 vs. 90.378, p=0.021), whereas was higher in good responders in the left lateral pulvinar thalamic nucleus (98.365 vs. 50.347, p=0.003) and right medial pulvinar thalamic nucleus (216.047 vs. 156.651, p=0.036).

CONCLUSIONS

We found that structural connectivity in patients with migraine differed from that in healthy controls. Moreover, the local structural connectivity varied with the response to sumatriptan, which suggests that structural connectivity is a useful factor for predicting how a patient will respond to sumatriptan.

Altered functional brain network patterns in patients with migraine without aura after transcutaneous auricular vagus nerve stimulation

Transcutaneous auricular vagus nerve stimulation (taVNS) shows excellent effects on relieving clinical symptoms in migraine patients. Nevertheless, the neurological mechanisms of taVNS for migraineurs remain unclear. In recent years, voxel-wise degree centrality (DC) and functional connectivity (FC) methods were extensively utilized for exploring alterations in patterns of FC in the resting-state brain. In the present study, thirty-five migraine patients without aura and thirty-eight healthy controls (HCs) were recruited for magnetic resonance imaging scans. Firstly, this study used voxel-wise DC analysis to explore brain regions where abnormalities were present in migraine patients. Secondly, for elucidating neurological mechanisms underlying taVNS in migraine, seed-based resting-state functional connectivity analysis was employed to the taVNS treatment group. Finally, correlation analysis was performed to explore the relationship between alterations in neurological mechanisms and clinical symptoms. Our findings indicated that migraineurs have lower DC values in the inferior temporal gyrus (ITG) and paracentral lobule than in healthy controls (HCs). In addition, migraineurs have higher DC values in the cerebellar lobule VIII and the fusiform gyrus than HCs. Moreover, after taVNS treatment (post-taVNS), patients displayed increased FC between the ITG with the inferior parietal lobule (IPL), orbitofrontal gyrus, angular gyrus, and posterior cingulate gyrus than before taVNS treatment (pre-taVNS). Besides, the post-taVNS patients showed decreased FC between the cerebellar lobule VIII with the supplementary motor area and postcentral gyrus compared with the pre-taVNS patients. The changed FC of ITG-IPL was significantly related to changes in headache intensity. Our study suggested that migraine patients without aura have altered brain connectivity patterns in several hub regions involving multisensory integration, pain perception, and cognitive function. More importantly, taVNS modulated the default mode network and the vestibular cortical network related to the dysfunctions in migraineurs. This paper provides a new perspective on the potential neurological mechanisms and therapeutic targets of taVNS for treating migraine.

The modulation effects of repeated transcutaneous auricular vagus nerve stimulation on the functional connectivity of key brainstem regions along the vagus nerve pathway in migraine patients

Background

Previous studies have shown a significant response to acute transcutaneous vagus nerve stimulation (taVNS) in regions of the vagus nerve pathway, including the nucleus tractus solitarius (NTS), raphe nucleus (RN) and locus coeruleus (LC) in both healthy human participants and migraine patients. This study aims to investigate the modulation effect of repeated taVNS on these brainstem regions by applying seed-based resting-state functional connectivity (rsFC) analysis.

Methods

70 patients with migraine were recruited and randomized to receive real or sham taVNS treatments for 4 weeks. fMRI data were collected from each participant before and after 4 weeks of treatment. The rsFC analyses were performed using NTS, RN and LC as the seeds.

Results

59 patients (real group: n = 33; sham group: n = 29) completed two fMRI scan sessions. Compared to sham taVNS, real taVNS was associated with a significant reduction in the number of migraine attack days (p = 0.024) and headache pain intensity (p = 0.008). The rsFC analysis showed repeated taVNS modulated the functional connectivity between the brain stem regions of the vagus nerve pathway and brain regions associated with the limbic system (bilateral hippocampus), pain processing and modulation (bilateral postcentral gyrus, thalamus, and mPFC), and basal ganglia (putamen/caudate). In addition, the rsFC change between the RN and putamen was significantly associated with the reduction in the number of migraine days.

Conclusion

Our findings suggest that taVNS can significantly modulate the vagus nerve central pathway, which may contribute to the potential treatment effects of taVNS for migraine.Clinical Trial Registration: http://www.chictr.org.cn/hvshowproject.aspx?id=11101, identifier ChiCTR-INR-17010559.

Changes in brain structure and related functional connectivity during menstruation in women with primary dysmenorrhea

Background

Neuroimaging studies have identified altered brain structures and functions in women with primary dysmenorrhea (PDM). However, previous studies focused on either structural or functional changes in specific brain regions rather than combining structural and functional analysis. Therefore, this prospective cross-sectional study aimed to investigate the changes in whole brain structure, and functional variation along with structural abnormalities in women with PDM during menstruation.

Methods

In all, 31 patients with PDM (PTs) and 31 healthy controls (HCs) were recruited. Voxel-based morphometry (VBM) and surface-based morphometry (SBM) analyses were applied to investigate structural changes based on high-resolution T1-weighted magnetic resonance images. Functional connectivity (FC) analysis was performed to evaluate functional variations related to the brain regions that showed structural group differences. Pearson correlation analysis was performed to assess the relationship between neuroimaging changes and clinical measures.

Results

Compared to HCs, PTs had reduced gray matter volume (GMV) in the right superior temporal gyrus (STG) and reduced thickness in the bilateral orbitofrontal cortex (OFC), left postcentral gyrus (PoCG), and left superior occipital gyrus (SOG). Among these areas, the STG and PoCG are responsible for altered resting-state FC patterns in PTs. Results showed decreased FC between the STG and the left cerebellar posterior lobe (poCb), the right dorsolateral prefrontal cortex (DLPFC), and the left precentral gyrus (PrCG). Results also showed decreased FC between the PoCG and the right precuneus and the right DLPFC. We also found greater FCs between the PoCG and the bilateral poCb, the left middle temporal gyrus (MTG), and the left angular gyrus. In addition, the FCs between the STG and poCb, and DLPFC in PTs were positively correlated with history and Cox menstrual symptom scale (CMSS) scores, respectively, while the FCs between STG and PrCG were negatively correlated with the onset age of PDM.

Conclusions

Our research found structural abnormalities and related FC changes in several brain regions that were mainly involved in the emotional and sensory aspects of menstrual pain in PDM. These findings could help us understand the occurrence of PDM from a neuroimaging perspective.

Structural MRI in Migraine: A Review of Migraine Vascular and Structural Changes in Brain Parenchyma

Migraine is a complex and common disorder that affects patients around the world. Despite recent advances in this field, the exact pathophysiology of migraine is still not completely understood. Structural MRI sequences have revealed a variety of changes to brain parenchyma associated with migraine, including white matter lesions, volume changes, and iron deposition. This Review highlights different structural imaging findings in various types of migraine and their relationship to migraine characteristics and subtypes in order to improve our understanding of migraine, its pathophysiologic mechanisms, and how to better diagnose and treat it.

The Virtual "Enfacement Illusion" on Pain Perception in Patients Suffering from Chronic Migraine: A Study Protocol for a Randomized Controlled Trial

BACKGROUND

given the limited efficacy, tolerability, and accessibility of pharmacological treatments for chronic migraine (CM), new complementary strategies have gained increasing attention. Body ownership illusions have been proposed as a non-pharmacological strategy for pain relief. Here, we illustrate the protocol for evaluating the efficacy in decreasing pain perception of the enfacement illusion of a happy face observed through an immersive virtual reality (VR) system in CM.

METHOD

the study is a double-blind randomized controlled trial with two arms, involving 100 female CM patients assigned to the experimental group or the control group. The experimental group will be exposed to the enfacement illusion, whereas the control group will be exposed to a pleasant immersive virtual environment. Both arms of the trial will consist in three VR sessions (20 min each). At the baseline and at the end of the intervention, the patients will fill in questionnaires based on behavioral measures related to their emotional and psychological state and their body satisfaction. Before and after each VR session, the level of pain, the body image perception, and the affective state will be assessed.

DISCUSSION

this study will provide knowledge regarding the relationship between internal body representation and pain perception, supporting the effectiveness of the enfacement illusion as a cognitive behavioral intervention in CM.

Propagation Structure of Intrinsic Brain Activity in Migraine without Aura

Previous studies have revealed highly reproducible patterns of temporally lagged brain activity in healthy human adults. However, it is unknown whether temporal organization of intrinsic activity is altered in migraines or if it relates to migraine chronification. In this resting-state functional magnetic resonance imaging study, temporal features of intrinsic activity were investigated using resting-state lag analysis, and 39 episodic migraine patients, 17 chronic migraine patients, and 35 healthy controls were assessed. Temporally earlier intrinsic activity in the hippocampal complex was revealed in the chronic migraine group relative to the other two groups. We also found earlier intrinsic activity in the medial prefrontal cortex in chronic compared with episodic migraines. Both migraine groups showed earlier intrinsic activity in the lateral temporal cortex and sensorimotor cortex compared with the healthy control group. Across all patients, headache frequency negatively correlated with temporal lag of the medial prefrontal cortex and hippocampal complex. Disrupted propagation of intrinsic activity in regions involved in sensory, cognitive and affective processing of pain may contribute to abnormal brain function during migraines. Decreased time latency in the lateral temporal cortex and sensorimotor cortex may be common manifestations in episodic and chronic migraines. The temporal features of the medial prefrontal cortex and hippocampal complex were associated with migraine chronification.

Intrinsic network activity reflects the ongoing experience of chronic pain

Analyses of intrinsic network activity have been instrumental in revealing cortical processes that are altered in chronic pain patients. In a novel approach, we aimed to elucidate how intrinsic functional networks evolve in regard to the fluctuating intensity of the experience of chronic pain. In a longitudinal study with 156 fMRI sessions, 20 chronic back pain patients and 20 chronic migraine patients were asked to continuously rate the intensity of their endogenous pain. We investigated the relationship between the fluctuation of intrinsic network activity with the time course of subjective pain ratings. For chronic back pain, we found increased cortical network activity for the salience network and a local pontine network, as well as decreased network activity in the anterior and posterior default mode network for higher pain intensities. Higher pain intensities in chronic migraine were accompanied with lower activity in a prefrontal cortical network. By taking the perspective of the individual, we focused on the variability of the subjective perception of pain, which include phases of relatively low pain and phases of relatively high pain. The present design of the assessment of ongoing endogenous pain can be a powerful and promising tool to assess the signature of a patient's endogenous pain encoding.

Alterations in Effective Connectivity of the Hippocampus in Migraine without Aura

Purpose

Neuroimaging studies on migraine have revealed structural and functional alterations in the hippocampus, a region involved in pain processing and stress response. This study was designed to investigate whether effective connectivity of this region is disrupted in migraine and relates to chronicity of this disease.

Patients and Methods

In 39 episodic migraine (EM) patients, 17 chronic migraine (CM) patients, and 35 healthy controls, we investigated differences in the directional influences between the hippocampus and the rest of the brain by combining resting-state functional magnetic resonance imaging and Granger causality analysis (GCA), with bilateral hippocampus as seed regions. The associations between directional influences and the clinical variables were also examined.

Results

Comparing each patient group to the control group, we found increased and decreased negative influence on the hippocampus exerted by the bilateral visual areas and right dorsolateral prefrontal cortex (dlPFC), respectively. The hippocampus showed increased positive influence on the right posterior insula and medial prefrontal cortex (mPFC), as well as increased negative influence on the left cerebellum in CM patients relative to EM patients and healthy controls. Furthermore, across all patients, the migraine frequency exhibited a positive and negative association with causal influence from the hippocampus to mPFC and left cerebellum, respectively.

Conclusion

Migraine patients have abnormal effective connectivity between the hippocampus and multiple brain regions involved in the sensory and cognitive processing of pain. Disrupted directional influences to the hippocampus exerted by dlPFC and bilateral visual areas were common features of EM and CM patients. Directional influences from the hippocampus to mPFC and left cerebellum may be useful imaging biomarkers for assessing migraine frequency.

Hypothalamic structural integrity and temporal complexity of cortical information processing at rest in migraine without aura patients between attacks

The hypothalamus has been attributed an important role during the premonitory phase of a migraine attack. Less is known about the role played by the hypothalamus in the interictal period and its relationship with the putative neurocognitive networks previously identified in the pathophysiology of migraine. Our aim was to test whether the hypothalamic microstructure would be altered during the interictal period and whether this co-existed with aberrant connectivity at cortical level. We collected multimodal MRI data from 20 untreated patients with migraine without aura between attacks (MO) and 20 healthy controls (HC) and studied fractional anisotropy, mean (MD), radial (RD), and axial diffusivity of the hypothalamus ROI as a whole from diffusion tensor imaging (DTI). Moreover, we performed an exploratory analysis of the same DTI metrics separately for the anterior and posterior hypothalamic ROIs bilaterally. From resting-state functional MRI, we estimated the Higuchi's fractal dimension (FD), an index of temporal complexity sensible to describe non-periodic patterns characterizing BOLD signature. Finally, we correlated neuroimaging findings with migraine clinical features. In comparison to HC, MO had significantly higher MD, AD, and RD values within the hypothalamus. These findings were confirmed also in the exploratory analysis on the sub-regions of the hypothalamus bilaterally, with the addition of lower FA values on the posterior ROIs. Patients showed higher FD values within the salience network (SN) and the cerebellum, and lower FD values within the primary visual (PV) network compared to HC. We found a positive correlation between cerebellar and SN FD values and severity of migraine. Our findings of hypothalamic abnormalities between migraine attacks may form part of the neuroanatomical substrate that predisposes the onset of the prodromal phase and, therefore, the initiation of an attack. The peculiar fractal dimensionality we found in PV, SN, and cerebellum may be interpreted as an expression of abnormal efficiency demand of brain networks devoted to the integration of sensory, emotional, and cognitive information related to the severity of migraine.

Lasmiditan: an additional therapeutic option for the acute treatment of migraine

Introduction: Migraine is currently listed as the second cause of 'years lived with disability' and the sixth cause of global disability. Despite the burden associated to the disease, availability of specific drugs is still limited.Areas covered: The authors have evaluated lasmiditan, the first 'ditan' approved by the Food and Drugs Administration in 2019, from a global perspective: basic chemistry, pharmacodynamic and pharmacokinetic profiles, efficacy in migraine as a 5-HT_1F receptor selective agonist, tolerability and clinical safety, and impact on migraine-related disability. Our evaluation considered original papers and review articles published from 2010 to 2020.Expert opinion: Available data point to the efficacy of lasmiditan in reducing migraine pain and the most bothersome symptoms within 2 hours from oral administration. Moreover, lasmiditan has a positive effect on migraine-related disability. Its side effects mostly reflect an involvement of the central nervous system or the vestibular system, while cardiovascular side effects are rare and mild.Lasmiditan can be safely prescribed in patients who have failed non-steroid anti-inflammatory drugs or triptans or with cardiovascular risk factors. Caution is advised in frequent users, due to lack of reliable data on its abuse potential. Further data are necessary to determine the usability of lasmiditan in particular populations, e.g. children and adolescents, pregnancy.

Abnormalities in cortical pattern of coherence in migraine detected using ultra high-density EEG

Individuals with migraine generally experience photophobia and/or phonophobia during and between migraine attacks. Many different mechanisms have been postulated to explain these migraine phenomena including abnormal patterns of connectivity across the cortex. The results, however, remain contradictory and there is no clear consensus on the nature of the cortical abnormalities in migraine. Here, we uncover alterations in cortical patterns of coherence (connectivity) in interictal migraineurs during the presentation of visual and auditory stimuli and during rest. We used a high-density EEG system, with 128 customized electrode locations, to compare inter- and intra-hemispheric coherence in the interictal period from 17 individuals with migraine (12 female) and 18 age- and gender-matched healthy control subjects. During presentations of visual (vertical grating pattern) and auditory (modulated tone) stimulation which varied in temporal frequency (4 and 6 Hz), and during rest, participants performed a colour detection task at fixation. Analyses included characterizing the inter- and intra-hemisphere coherence between the scalp EEG channels over 2-s time intervals and over different frequency bands at different spatial distances and spatial clusters. Pearson's correlation coefficients were estimated at zero-lag. Repeated measures analyses-of-variance revealed that, relative to controls, migraineurs exhibited significantly (i) faster colour detection performance, (ii) lower spatial coherence of alpha-band activity, for both inter- and intra-hemisphere connections, and (iii) the reduced coherence occurred predominantly in frontal clusters during both sensory conditions, regardless of the stimulation frequency, as well as during the resting-state. The abnormal patterns of EEG coherence in interictal migraineurs during visual and auditory stimuli, as well as at rest (eyes open), may be associated with the cortical hyper-responsivity that is characteristic of abnormal sensory processing in migraineurs.

The Instant Effects of Continuous Transcutaneous Auricular Vagus Nerve Stimulation at Acupoints on the Functional Connectivity of Amygdala in Migraine without Aura: A Preliminary Study

Background

A growing body of evidence suggests that both auricular acupuncture and transcutaneous auricular vagus nerve stimulation (taVNS) can induce antinociception and relieve symptoms of migraine. However, their instant effects and central treatment mechanism remain unclear. Many studies proved that the amygdalae play a vital role not only in emotion modulation but also in pain processing. In this study, we investigated the modulation effects of continuous taVNS at acupoints on the FC of the bilateral amygdalae in MwoA.

Methods

Thirty episodic migraineurs were recruited for the single-blind, crossover functional magnetic resonance imaging (fMRI) study. Each participant attended two kinds of eight-minute stimulations, taVNS and sham-taVNS (staVNS), separated by seven days in random order. Finally, 27 of them were included in the analysis of seed-to-voxel FC with the left/right amygdala as seeds.

Results

Compared with staVNS, the FC decreased during taVNS between the left amygdala and left middle frontal gyrus (MFG), left dorsolateral superior frontal gyrus, right supplementary motor area (SMA), bilateral paracentral lobules, bilateral postcingulum gyrus, and right frontal superior medial gyrus, so did the FC of the right amygdala and left MFG. A significant positive correlation was observed between the FC of the left amygdala and right SMA and the frequency/total time of migraine attacks during the preceding four weeks.

Conclusion

Continuous taVNS at acupoints can modulate the FC between the bilateral amygdalae and pain-related brain regions in MwoA, involving the limbic system, default mode network, and pain matrix, with obvious differences between the left amygdala and the right amygdala. The taVNS may produce treatment effects by modulating the abnormal FC of the amygdala and pain networks, possibly having the same central mechanism as auricular acupuncture.

Concurrent brain structural and functional alterations in patients with migraine without aura: an fMRI study

OBJECTIVES

To explore the possible concurrent brain functional and structural alterations in patients with migraine without aura (MwoA) patients compared to healthy subjects (HS).

METHODS

Seventy-two MwoA patients and forty-six HS were recruited. 3D-T1 and resting state fMRI data were collected during the interictal period for MwoA and HS. Voxel-based morphometry (VBM) for structure analysis and regional homogeneity (Reho) for fMRI analysis were applied. The VBM and Reho maps were overlapped to determine a possible brain region with concurrent functional and structural alteration in MwoA patients. Further analysis of resting state functional connectivity (FC) alteration was applied with this brain region as the seed.

RESULTS

Compared with HS, MwoA patients showed decreased volume in the bilateral superior and inferior colliculus, periaqueductal gray matter (PAG), locus ceruleus, median raphe nuclei (MRN) and dorsal pons medulla junction. MwoA patients showed decreased Reho values in the middle occipital gyrus and inferior occipital gyrus, and increased Reho values in the MRN. Only a region in the MRN showed both structural and functional alteration in MwoA patients. Pearson correlation analysis showed that there was no association between volume or Reho values of the MRN and headache frequency, headache intensity, disease duration, self-rating anxiety scale or self-rating depression scale in MwoA patients. Resting state functional connectivity (FC) with the MRN as the seed showed that MwoA patients had increased FC between the MRN and PAG.

CONCLUSIONS

MRN are involved in the pathophysiology of migraine during the interictal period. This study may help to better understand the migraine symptoms.

TRIAL REGISTRATION

NCT01152632 . Registered 27 June 2010.

Functional Alterations in the Posterior Insula and Cerebellum in Migraine Without Aura: A Resting-State MRI Study

Background: Hypothesis-driven functional connectivity (FC) analyses have revealed abnormal functional interaction of regions or networks involved in pain processing in episodic migraine patients. We aimed to investigate the resting-state FC patterns in episodic migraine by combining data-driven voxel-wise degree centrality (DC) calculation and seed-based FC analysis.

Methods: Thirty-nine patients suffering from episodic migraine without aura and 35 healthy controls underwent clinical assessment and functional MRI. DC was analyzed voxel-wise and compared between groups, and FC of regions with DC differences were further examined using a seed-based approach.

Results: Compared with the control group, the migraine group showed increased and decreased DC in the right posterior insula and left crus I, respectively. Seed-based FC analyses revealed that migraine patients demonstrated increased right posterior insula connections with the postcentral gyrus, supplementary motor area/paracentral lobule, fusiform gyrus and temporal pole. The left crus I showed decreased FC with regions of the default mode network (DMN), including the medial prefrontal cortex (mPFC), angular gyrus, medial and lateral temporal cortex in patients with migraine. Furthermore, pain intensity positively correlated with DC in the right amygdala/parahippocampal gyrus, and migraine frequency negatively correlated with FC between the left crus I and mPFC.

Conclusion: Patients with episodic migraine without aura have increased FC with the right posterior insula and decreased FC within the DMN, which may underlie disturbed sensory integration and cognitive processing of pain. The left crus I-mPFC connectivity may be a useful biomarker for assessing migraine frequency.

Tracking the Migraine Cycle Using Visual Tasks

There are a number of reports that perceptual, electrophysiological and imaging measures can track migraine periodicity. As the electrophysiological and imaging research requires specialist equipment, it has few practical applications. This study sought to track changes in performance on four visual tasks over the migraine cycle. Coherence thresholds were measured for two motion and two orientation tasks. The first part of the study confirmed that the data obtained from an online study produced comparable results to those obtained under controlled laboratory conditions. Thirteen migraine with aura, 12 without aura, and 12 healthy controls participated. The second part of the study showed that thresholds for discriminating vertical coherent motion varied with the migraine cycle for a majority of the participants who tested themselves multiple times (four with aura, seven without). Performance improved two days prior to a migraine attack and remained improved for two days afterwards. This outcome is as expected from an extrapolation of earlier electrophysiological research. This research points to the possibility of developing sensitive visual tests that patients can use at home to predict an impending migraine attack and so take steps to try to abort it or, if it is inevitable, to plan their lives around it.

Mechanisms of migraine as a chronic evolutive condition

Understanding the mechanisms of migraine remains challenging as migraine is not a static disorder, and even in its episodic form migraine remains an "evolutive" chronic condition. Considerable progress has been made in elucidating the pathophysiological mechanisms of migraine, associated genetic factors that may influence susceptibility to the disease, and functional and anatomical changes during the progression of a migraine attack or the transformation of episodic to chronic migraine. Migraine is a life span neurological disorder that follows an evolutive age-dependent change in its prevalence and even clinical presentations. As a disorder, migraine involves recurrent intense head pain and associated unpleasant symptoms. Migraine attacks evolve over different phases with specific neural mechanisms and symptoms being involved during each phase. In some patients, migraine can be transformed into a chronic form with daily or almost daily headaches. The mechanisms behind this evolutive process remain unknown, but genetic and epigenetic factors, inflammatory processes and central sensitization may play an important role.

Genetic Screening of Plasticity Regulating Nogo-Type Signaling Genes in Migraine

Migraine is the sixth most prevalent disease in the world and a substantial number of experiments have been conducted to analyze potential differences between the migraine brain and the healthy brain. Results from these investigations point to the possibility that development and aggravation of migraine may include grey matter plasticity. Nogo-type signaling is a potent plasticity regulating system in the CNS and consists of ligands, receptors, co-receptors and modulators with a dynamic age- and activity-related expression in cortical and subcortical regions. Here we investigated a potential link between migraine and five key Nogo-type signaling genes: RTN4, OMGP, MAG, RTN4R and LINGO1, by screening 15 single nucleotide polymorphisms (SNPs) within these genes. In a large Swedish migraine cohort (749 migraine patients and 4032 controls), using a logistic regression with sex as covariate, we found that there was no such association. In addition, a haplotype analysis was performed which revealed three haplotype blocks. These blocks had no significant association with migraine. However, to robustly conclude that Nogo-type genotypes signaling do not influence the prevalence of migraine, further studies are encouraged.

Altered functional connectivity of the red nucleus and substantia nigra in migraine without aura

Background

Functional connectivity (FC) has been used to investigate the pathophysiology of migraine. Accumulating evidence is pointing toward malfunctioning of brainstem structures, i.e., the red nucleus (RN) and substantia nigra (SN), as an important factor in migraine without aura (MwoA). We aimed to identify atypical FC between the RN and SN and other brain areas in patients with MwoA and to explore the association between RN and SN connectivity changes and performance on neuropsychological tests in these patients.

Methods

Resting-state functional magnetic resonance imaging (fMRI) data were obtained from 30 patients with MwoA and 22 age-, sex-, and years of education-matched healthy controls (HC). The FC of the brainstem structures was analyzed using a standard seed-based whole-brain correlation method. The results of the brainstem structure FC were assessed for correlations with other clinical features.

Results

Patients with MwoA exhibited reduced left RN-based FC with the left middle frontal gyrus, reduced right RN-based FC with the ipsilateral superior parietal lobe, and increased FC with the ipsilateral cerebellum. Additionally, patients with MwoA demonstrated significantly decreased right SN-based FC with the right postcentral gyrus, left parietal lobule, and left superior frontal gyrus. Hypo-connectivity between the right SN and right postcentral gyrus was negatively correlated with disease duration (r = − 0.506, P = 0.004). Additionally, increased connectivity of the right RN to the ipsilateral cerebellar lobes was positively correlated with the Headache Impact Test-6 scores (r = 0.437, P = 0.016).

Conclusions

The present study suggested that patients with MwoA have disruption in their RN and SN resting-state networks, which are associated with specific clinical characteristics. The changes focus on the regions associated with cognitive evaluation, multisensory integration, and modulation of perception and pain, which may be associated with migraine production, feedback, and development. Taken together, these results may improve our understanding of the neuropathological mechanism of migraine.