Cerebrovascular reactivity as a determinant of deep white matter hyperintensities in migraine

Shifts in structural connectome organization in the limbic and sensory systems of patients with episodic migraine

Migraine is a complex neurological condition characterized by recurrent headaches, which is often accompanied by various neurological symptoms. Magnetic resonance imaging (MRI) is a powerful tool for investigating whole-brain connectivity patterns; however, systematic assessment of structural connectome organization has rarely been performed. In the present study, we aimed to examine the changes in structural connectivity in patients with episodic migraines using diffusion MRI. First, we computed structural connectivity using diffusion MRI tractography, after which we applied dimensionality reduction techniques to the structural connectivity and generated three low-dimensional eigenvectors. We subsequently calculated the manifold eccentricity, defined as the Euclidean distance between each data point and the center of the data in the manifold space. We then compared the manifold eccentricity between patients with migraines and healthy controls, revealing significant between-group differences in the orbitofrontal cortex, temporal pole, and sensory/motor regions. Between-group differences in subcortico-cortical connectivity further revealed significant changes in the amygdala, accumbens, and caudate nuclei. Finally, supervised machine learning effectively classified patients with migraines and healthy controls using cortical and subcortical structural connectivity features, highlighting the importance of the orbitofrontal and sensory cortices, in addition to the caudate, in distinguishing between the groups. Our findings confirmed that episodic migraine is related to the structural connectome changes in the limbic and sensory systems, suggesting its potential utility as a diagnostic marker for migraine.

PFO-spectrum disorder: two different cerebrovascular diseases in patients with PFO as detected by AI brain imaging software

Background

Patent foramen ovale (PFO) is a prevalent cardiac remnant of fetal anatomy that may pose a risk factor for stroke in some patients, while others can present with asymptomatic white matter (WM) lesions. The current study aimed to test the hypothesis that patients with a PFO who have a history of stroke or transient ischemic attack, compared to those without such a history, have a different burden and distribution of cerebral WM hyperintensities. Additionally, we tested the association between PFO morphological characteristics and severity of shunt, and their impact on the occurrence of ischemic cerebral vascular events and on the burden of cerebral WM lesions.

Patients and methods

Retrospective, case-control study that included patients with PFO confirmed by transesophageal echocardiography. Right-to-left shunt size was assessed using transcranial Doppler ultrasound. Cerebral MRIs were analyzed for all participants using the semi-automated Quantib NDTM software for the objective quantification of WM lesions. WM lesions volume was compared between patients with and without a history of stroke. Additionally, the anatomical characteristics of PFOs were assessed to explore their relation to stroke occurrence and WM lesions volume.

Results

Of the initial 264 patients diagnosed with PFO, 67 met the inclusion criteria and were included in the analysis. Of them, 62% had a history of PFO-related stroke/TIA. Overall burden of WM lesions, including stroke volume, was not significantly different (p = 0.103). However, after excluding stroke volume, WM lesions volume was significantly higher in patients without stroke (0.27 cm3, IQR 0.03-0.60) compared to those with stroke/TIA (0.08 cm3, IQR 0.02-0.18), p = 0.019. Patients with a history of PFO-related stroke/TIA had a tendency to larger PFO sizes by comparison to those without, in terms of length and height, and exhibited greater right-to-left shunt volumes.

Discussion

We suggest that PFO may be associated with the development of two distinct cerebrovascular conditions (stroke and "silent" WM lesions), each characterized by unique imaging patterns. Further studies are needed to identify better the "at-risk" PFOs and gain deeper insights into their clinical implications.

Associations of Cerebrovascular Regulation and Arterial Stiffness With Cerebral Small Vessel Disease: A Systematic Review and Meta-Analysis

BACKGROUND

Cerebral small vessel disease (cSVD) is a major contributing factor to ischemic stroke and dementia. However, the vascular pathologies of cSVD remain inconclusive. The aim of this systematic review and meta-analysis was to characterize the associations between cSVD and cerebrovascular reactivity (CVR), cerebral autoregulation, and arterial stiffness (AS).

METHODS AND RESULTS

MEDLINE, Web of Science, and Embase were searched from inception to September 2023 for studies reporting CVR, cerebral autoregulation, or AS in relation to radiological markers of cSVD. Data were extracted in predefined tables, reviewed, and meta-analyses performed using inverse-variance random effects models to determine pooled odds ratios (ORs). A total of 1611 studies were identified; 142 were included in the systematic review, of which 60 had data available for meta-analyses. Systematic review revealed that CVR, cerebral autoregulation, and AS were consistently associated with cSVD (80.4%, 78.6%, and 85.4% of studies, respectively). Meta-analysis in 7 studies (536 participants, 32.9% women) revealed a borderline association between impaired CVR and cSVD (OR, 2.26 [95% CI, 0.99-5.14]; P=0.05). In 37 studies (27 952 participants, 53.0% women) increased AS, per SD, was associated with cSVD (OR, 1.24 [95% CI, 1.15-1.33]; P<0.01). Meta-regression adjusted for comorbidities accounted for one-third of the AS model variance (R2=29.4%, Pmoderators=0.02). Subgroup analysis of AS studies demonstrated an association with white matter hyperintensities (OR, 1.42 [95% CI, 1.18-1.70]; P<0.01).

CONCLUSIONS

The collective findings of the present systematic review and meta-analyses suggest an association between cSVD and impaired CVR and elevated AS. However, longitudinal investigations into vascular stiffness and regulatory function as possible risk factors for cSVD remain warranted.

Association of intracranial atherosclerosis with cerebral small vessel disease in a community-based population

BACKGROUND AND PURPOSE

The purpose of this study was to explore the relationship between intracranial atherosclerosis and cerebral small vessel disease (CSVD).

METHODS

Community-dwelling residents of Lishui, China in the PRECISE (Polyvascular Evaluation for Cognitive Impairment and Vascular Events) study were involved. Intracranial atherosclerosis was grouped by the severity of intracranial artery plaques with stenosis and burden. Four imaging markers including lacunes, white matter hyperintensity (WMH), cerebral microbleeds (CMBs), and perivascular spaces (PVS) as well as the CSVD burden scores were assessed. Logistic regression or ordinal logistic regression models with odds ratio (OR) or common OR (cOR) were used to estimate the relationship between intracranial atherosclerosis and CSVD markers and burdens.

RESULTS

The mean age was 61.20 ± 6.68 years, and 1424 (46.52%) were men among 3061 participants included at baseline. Intracranial atherosclerotic burden was associated with the severity of the lacunes (OR = 4.18, 95% confidence interval [CI] = 1.83-9.58), modified WMH burden (cOR = 1.94, 95% CI = 1.01-3.71), presence of CMBs (OR = 2.28, 95% CI = 1.05-4.94), and CMB burden (OR = 2.23, 95% CI = 1.03-4.80). However, it was not associated with the WMH burden and PVS. Intracranial atherosclerotic burden was associated with CSVD burden (Wardlaw: cOR = 2.73, 95% CI = 1.48-5.05; Rothwell: cOR = 2.70, 95% CI = 1.47-4.95). The association between intracranial atherosclerosis and CSVD was obvious in participants with both anterior and posterior circulation artery stenosis.

CONCLUSIONS

Based on a Chinese community population, there may be an association between intracranial atherosclerosis and CSVD, but its mechanism in relation to vascular risk factors still needs to be clarified.

Classification of white matter lesions and characteristics of small vessel disease markers

OBJECTIVES

Radiological markers for cerebral small vessel disease (SVD) may have different biological underpinnings in their development. We attempted to categorize SVD burden by integrating white matter signal abnormalities (WMSA) features and secondary presence of lacunes, microbleeds, and enlarged perivascular spaces.

METHODS

Data were acquired from 610 older adults (aged > 40 years) who underwent brain magnetic resonance imaging exam as part of a health checkup. The WMSA were classified individually by the number and size of non-contiguous lesions, distribution, and contrast. Age-detrended lacunes, microbleeds, and enlarged perivascular space were quantified to further categorize individuals. Clinical and laboratory values were compared across the individual classes.

RESULTS

Class I was characterized by multiple, small, deep WMSA but a low burden of lacunes and microbleeds; class II had large periventricular WMSA and a high burden of lacunes and microbleeds; and class III had limited juxtaventricular WMSA and lacked lacunes and microbleeds. Class II was associated with older age, diabetes, and a relatively higher neutrophil-to-lymphocyte ratio. Smoking and higher uric acid levels were associated with an increased risk of class I.

CONCLUSION

The heterogeneity of SVD was categorized into three classes with distinct clinical correlates. This categorization will improve our understanding of SVD pathophysiology, risk stratification, and outcome prediction.

KEY POINTS

• Classification of white matter signal abnormality (WMSA) features was associated with different characteristic of lacunes, microbleeds, and enlarged perivascular space and clinical variability. • Class I was characterized by multiple, small, deep WMSA but a low burden of lacunes and microbleeds. Class II had large periventricular WMSA and a high burden of lacunes and microbleeds. Class III had limited juxtaventricular WMSA and lacked lacunes and microbleeds. • Class II was associated with older age, diabetes, and higher neutrophil-to-lymphocyte ratio. Smoking and higher uric acid levels were associated with an increased risk of class I.

What imaging has revealed about migraine and chronic migraine

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

Prevalence and clinical characteristics of white matter hyperintensities in Migraine: A meta-analysis

BACKGROUND

Current evidences show an increased risk of white matter hyperintensities (WMHs) in migraineurs compared to age-matched controls. However, WMHs prevalence and the associations between WMHs and clinical characteristics in migraineurs have not been systematically evaluated using a meta-analytical approach. This study explored the pooled prevalence of WMHs and the associations of WMHs with the clinical characteristics in patients with migraine.

METHODS

A systematic review and meta-analysis of observational studies reporting the occurrence and clinical characteristics of patients with WMHs attributed to migraine was performed. We searched the PubMed, Web of Science, and Embase databases. Random-effects models were used to calculate the pooled prevalence rate, odds ratio (OR), or mean difference (MD) with corresponding 95% confidence intervals (CIs).

RESULTS

Thirty eligible studies were identified including 3,502 migraineurs aged 37.2 (mean) years. The pooled WMHs prevalence was 44 %, 45 %, and 38 % in migraine, migraine with aura, and migraine without aura groups, respectively. In migraineurs with WMHs, the frontal lobe and subcortical white matter were the most susceptible area. Compared with non-migraine controls, patients with migraine had increased odds for WMHs (OR 4.32, 95 % CI = 2.56-7.28, I² = 67 %). According to reported univariable results from included studies, pooled analysis showed that clinical characteristics including age, presence of aura, disease duration, hypertension, diabetes mellitus and right-to-left shunt were associated with the presence of WMHs. Migraine pain and aura characteristics were not related to WMHs.

CONCLUSIONS

These data suggest that WMHs are common in migraine, especially in those who are older or have aura, hypertension, diabetes mellitus, or right-to-left shunt. A better understanding of the WMHs attributed to migraine is needed in future studies.

Use of Hypoxic Respiratory Challenge for Differentiating Alzheimer's Disease and Wild-Type Mice Non-Invasively: A Diffuse Optical Spectroscopy Study

Alzheimer's disease is one of the most critical brain diseases. The prevalence of the disease keeps rising due to increasing life spans. This study aims to examine the use of hemodynamic signals during hypoxic respiratory challenge for the differentiation of Alzheimer's disease (AD) and wild-type (WT) mice. Diffuse optical spectroscopy, an optical system that can non-invasively monitor transient changes in deoxygenated (ΔRHb) and oxygenated (ΔOHb) hemoglobin concentrations, was used to monitor hemodynamic reactivity during hypoxic respiratory challenges in an animal model. From the acquired signals, 13 hemodynamic features were extracted from each of ΔRHb and -ΔOHb (26 features total) for more in-depth analyses of the differences between AD and WT. The hemodynamic features were statistically analyzed and tested to explore the possibility of using machine learning (ML) to differentiate AD and WT. Among the twenty-six features, two features of ΔRHb and one feature of -ΔOHb showed statistically significant differences between AD and WT. Among ML techniques, a naive Bayes algorithm achieved the best accuracy of 84.3% when whole hemodynamic features were used for differentiation. While further works are required to improve the approach, the suggested approach has the potential to be an alternative method for the differentiation of AD and WT.

Cerebrovascular reactivity and deep white matter hyperintensities in migraine: A prospective CO2 targeting study

Several studies suggested the association of migraine with deep white matter hyperintensities (WMHs). We aimed to explore the cerebrovascular reactivity (CVR), deep WMH burden, and their association in patients with migraine using a state-of-the-art methodology. A total of 31 patients with migraine without aura and 31 age/sex-matched controls underwent 3T MRI with prospective end-tidal carbon dioxide (CO₂) targeting. We quantified deep WMH clusters using an automated segmentation tool and measured voxel-wise CVR by changes in blood oxygen level-dependent signal fitted to subjects' end-tidal CO₂. The association of migraine and CVR with the presence of WMH in each voxel and interaction of migraine and CVR on WMH were analysed. Patients had a higher number of deep WMHs than controls (p = 0.015). Migraine and reduced CVR were associated with increased probability of having WMHs in each voxel (adjusted OR 30.78 [95% CI 1.89-500.53], p = 0.016 and adjusted OR 0.30 [0.29-0.32], p < 0.001, respectively). Migraine had an effect modification on CVR on deep WMHs (p for interaction <0.001): i.e. the association between CVR and WMH was greater in patients than in controls. We suggest that the migraine-WMH association can be explained by the effect modification on the CVR.

The putative role of trigemino-vascular system in brain perfusion homeostasis and the significance of the migraine attack

Besides representing the place where a migraine attack generates, what is the physiological role of peptidergic control of arteriolar caliber within the trigemino-vascular system? Considering that the shared goal of most human CGRP-based neurosensory systems is the protection from an acute threat, especially if hypoxic, what is the end meaning of a migraine attack? In this paper, we have reviewed available evidence on the possible role of the trigemino-vascular system in maintaining cerebral perfusion pressure homeostasis, despite the large physiological fluctuations in intracranial pressure occurring in daily life activities. In this perspective, the migraine attack is presented as the response to a cerebral hypoxic threat consequent to a deranged intracranial pressure control aimed at generating a temporary withdrawal from the environment with limitation of physical activity, a condition required to promote the restoration of cerebral fluids dynamic balance.

Evaluating the relationship between right-to-left shunt and white matter hyperintensities in migraine patients: A systematic review and meta-analysis

Introduction

White matter hyperintensities (WMHs) have been observed with greater frequency in patients with migraine and are thought to be associated with impaired cognition and function. The relationship between WMHs and right-to-left shunt (RLS) in migraine patients is unknown. We performed a systematic review to determine if there is an association between RLS and WMHs in patients with migraine.

Methods

A systematic search of the literature was performed in PubMed and Embase using a suitable keyword search strategy from inception up to 16th June 2021. All studies that included patients with migraine and studied RLS and WMHs were included.

Results

A total of 8 non-randomized observational studies comprising 1125 patients with migraine were included; 576 had an RLS, compared to 549 patients with no RLS. The mean age of the study populations ranged from 28.4 to 43 years, while the average duration from migraine diagnosis ranged from 5.1 to 19 years. The proportion of female to male patients was consistently higher in all studies (60.0–94.4%). Amongst migraine patients with RLS, 338 patients (58.7%) had WMHs. In contrast, 256 (46.6%) of migraine patients without RLS had WMHs. RLS was significantly associated with the presence of WMHs in migraine patients (OR: 1.56, 95% CI: 1.05–2.34, p = 0.03).

Conclusion

In migraine patients, RLS was significantly associated with the presence of WMHs. Longitudinal studies are warranted to establish RLS as a risk factor for WMHs in patients with migraine, and to establish the significance of these changes.

Cerebral Hemodynamics, Right-to-Left Shunt and White Matter Hyperintensities in Patients with Migraine with Aura, Young Stroke Patients and Controls

Background: Migraine with aura (MA) patients present an increased risk of cerebrovascular events. However, whether these patients present an increased white matter hyperintensities (WMHs) load compared to the general population is still under debate. Our study aimed to evaluate the relationship between cerebral hemodynamics, right-to-left shunt (RLS) and WMHs in MA patients, young patients with cryptogenic stroke or motor transient ischemic attack (TIA) and controls. Methods: We enrolled 30 MA patients, 20 young (<60 years) patients with cryptogenic stroke/motor TIA, and 10 controls. All the subjects underwent a transcranial Doppler bubble test to detect RLS and cerebral hemodynamics assessed by the breath holding index (BHI) for the middle (MCA) and posterior (PCA) cerebral arteries. Vascular risk factors were collected. The WMHs load on FLAIR MRI sequences was quantitatively assessed. Results: The stroke/TIA patients presented a higher prevalence of RLS (100%) compared with the other groups (p < 0.001). The MA patients presented a higher BHI compared with the other groups in the PCA (p = 0.010) and higher RLS prevalence (60%) than controls (30%) (p < 0.001). The WMHs load did not differ across groups. BHI and RLS were not correlated to the WMHs load in the groups. Conclusions: A preserved or more reactive cerebral hemodynamics and the presence of a RLS are likely not involved in the genesis of WMHs in MA patients. A higher BHI may counteract the risk related to their higher prevalence of RLS. These results need to be confirmed by further studies to be able to effectively identify the protective role of cerebral hemodynamics in the increased RLS frequency in MA patients.

Compromised cerebrovascular reactivity in migraineurs with right-to-left shunts: a potential mechanism of white matter hyperintensities

OBJECTIVE

Our study aims to explore the changes of cerebrovascular reactivity (CVR) in migraineurs with right-to-left shunts (RLS), and further evaluate the association between CVR and the occurrence of the white matter hyperintensities (WMHs).

METHODS

RLS was diagnosed based on a contrast enhancement transcranial Doppler (c-TCD) examination. The breath holding index (BHI), which represents CVR, was measured from the middle cerebral artery (MCA) using a TCD with the breath-holding method. WMHs was defined as clearly hyperintense areas in 3 T magnetic resonance imaging (MRI). All migraineurs underwent a standardized questionnaire for family and personal history and detailed migraine features.

RESULTS

Three hundred and ninety-seven migraineurs and 100 controls were included in our study. The BHI was significantly lower in migraineurs than controls (0.527 ± 0.709 vs. 0.674 ± 0.489, P = 0.016). Moreover, migraineurs with RLS had lower BHI than those without RLS (0.504 ± 0.671 vs. 0.674 ± 0.721, p = 0.024). Migraineurs with WMHs had lower BHI than those without (0.47 ± 0.71 vs. 0.75 ± 0.49, p = 0.035). The reduced BHI was an independent influencing factor for WMHs in our study (OR = 0.338; 95% CI = 0.142-0.806, p = 0.014).

CONCLUSION

Our results indicated that BHI was reduced in migraineurs, and the reduced BHI was associated with RLS. Moreover, the reduced CVR in migraineurs with RLS might be related to the occurrence of WMHs.

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

OBJECTIVE

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

BACKGROUND

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

METHODS

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

RESULTS

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

CONCLUSIONS

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

White matter hyperintensity in different migraine subtypes

The diagnostic value of white matter hyperintensities (WMH) in different types of migraineare unknown. To evaluate the WMH pattern of different subtypes in migraine patients with no vascular risk factors. 92 migraine patients (73 females, mean age 34.6 ± 8.9; 61 episodic migraine, 31 chronic migraine, 36 migraine with aura, 56 migraine without aura) without vascular risk factors underwent brain MRI (3 T). We also included a matched healthy control group with no migraine (n = 24). The prevalence of WMH in different types of migraine was similar and ranged from 38.7 to 44.4%; the control group showed no WMH at all. Lesions were located within frontal, parietal and temporal lobes (in order of decreasing incidence) in juxtacortical and/or deep white matter. WMH appeared as round or slightly elongated foci with a median size of 2.5 mm [1.5; 3]. Total number, size and prevalence of WMH by lobes and white matter regions were similar between groups, and no interaction with age or sex was found. The number of lesions within the frontal lobe juxtacortical white matter correlated with the age of patients (r = 0.331, p = 0.001) and the duration since migraine onset (r = 0.264, p = 0.012). Patients with different migraine subtypes and without vascular risk factors are characterized by a similar pattern of WMH in the absence of subclinical infarctions or microbleedings. Therefore, WMH have no relevant prognostic value regarding the course of migraine and vascular complications. WMH pattern may be used to differentiate migraine as a primary disorder and other disorders with migraine-like headache and WMH.

Cerebrovascular Reactivity Measures Are Associated With Post-traumatic Headache Severity in Chronic TBI; A Retrospective Analysis

OBJECTIVE

To characterize the relationship between persistent post-traumatic headache (pPTH) and traumatic cerebrovascular injury (TCVI) in chronic traumatic brain injury (TBI). Cerebrovascular reactivity (CVR), a measure of the cerebral microvasculature and endothelial cell function, is altered both in individuals with chronic TBI and migraine headache disorder (Amyot et al., 2017; Lee et al., 2019b). The pathophysiologies of pPTH and migraine are believed to be associated with chronic microvascular dysfunction. We therefore hypothesize that TCVI may contribute to the underlying migraine-like mechanism(s) of pPTH.

MATERIALS AND METHODS

22 moderate/severe TBI participants in the chronic stage (>6 months) underwent anatomic and functional magnetic resonance imaging (fMRI) scanning with hypercapnia gas challenge to measure CVR as well as the change in CVR (ΔCVR) after single-dose treatment of a specific phosphodiesterase-5 (PDE-5) inhibitor, sildenafil, which potentiates vasodilation in response to hypercapnia in impaired endothelium, as part of a Phase2a RCT of sildenafil in chronic TBI (NCT01762475). CVR and ΔCVR measures of each participant were compared with the individual's pPTH severity measured by the headache impact test-6 (HIT-6) survey.

RESULTS

There was a moderate correlation between HIT-6 and both CVR and ΔCVR scores [Spearman's correlation = -0.50 (p = 0.018) and = 0.46 (p = 0.03), respectively], indicating that a higher headache burden is associated with decreased endothelial function in our chronic TBI population.

CONCLUSION

There is a correlation between PTH and CVR in chronic moderate-severe TBI. This relationship suggests that chronic TCVI may underlie the pathobiology of pPTH. Further, our results suggest that novel treatment strategies that target endothelial function and vascular health may be beneficial in refractory pPTH.

Pathophysiological Bases of Comorbidity in Migraine

Despite that it is commonly accepted that migraine is a disorder of the nervous system with a prominent genetic basis, it is comorbid with a plethora of medical conditions. Several studies have found bidirectional comorbidity between migraine and different disorders including neurological, psychiatric, cardio- and cerebrovascular, gastrointestinal, metaboloendocrine, and immunological conditions. Each of these has its own genetic load and shares some common characteristics with migraine. The bidirectional mechanisms that are likely to underlie this extensive comorbidity between migraine and other diseases are manifold. Comorbid pathologies can induce and promote thalamocortical network dysexcitability, multi-organ transient or persistent pro-inflammatory state, and disproportionate energetic needs in a variable combination, which in turn may be causative mechanisms of the activation of an ample defensive system with includes the trigeminovascular system in conjunction with the neuroendocrine hypothalamic system. This strategy is designed to maintain brain homeostasis by regulating homeostatic needs, such as normal subcortico-cortical excitability, energy balance, osmoregulation, and emotional response. In this light, the treatment of migraine should always involves a multidisciplinary approach, aimed at identifying and, if necessary, eliminating possible risk and comorbidity factors.

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.

A Systematic Review and Meta-analysis of the Therapeutic Effect of Acupuncture on Migraine

Background: Migraine is an intractable headache disorder, manifesting as periodic attacks. It is highly burdensome for patients and society. Acupuncture treatment can be beneficial as a supplementary and preventive therapy for migraine.

Objectives: This systematic review and meta-analysis aimed to investigate the efficacy and safety of acupuncture for migraine, and to examine transcranial doppler changes after acupuncture.

Methods: Reports, conference, and academic papers published before March 15, 2019 in databases including PubMed, Cochrane library, Embase, China National Knowledge Infrastructure, WANFANG Database, Chinese journal of Science and Technology, and China Biomedical were searched. Randomized controlled trials (RCTs) involving acupuncture, sham acupuncture, and medication in migraine were included. The Cochrane Collaboration software, RevMan 5.3, was used for data processing and migration risk analysis.

Results: Twenty-eight RCTs were included. 15 RCTs included medication only, 10 RCTs included sham acupuncture only, and 3 RCTs included both. The study included 2874 patients, split into 3 groups: acupuncture treatment group (n = 1396), medication control group (n = 865), and sham acupuncture control group (n = 613). The results showed that treatment was more effective in the acupuncture group than in the sham acupuncture group (MD = 1.88, 95% CI [1.61, 2.20], P < 0.00001) and medication group (MD = 1.16, 95% CI [1.12, 1.21], P < 0.00001). Improvement in visual analog scale (VAS) score was greater in the acupuncture group than in the sham acupuncture group (MD = −1.00, 95% CI [-1.27,−0.46], P < 0.00001; MD = −0.59, 95% CI [-0.81,−0.38], P < 0.00001), and their adverse reaction rate was lower than that of the medication group (RR = 0.16, 95% CI [0.05, 0.52], P = 0.002). The improvement of intracranial blood flow velocity by acupuncture is better than that by medication, but the heterogeneity makes the result unreliable.

Conclusions: Acupuncture reduced the frequency of migraine attacks, lowered VAS scores, and increased therapeutic efficiency compared with sham acupuncture. Compared with medication, acupuncture showed higher effectiveness with less adverse reactions and improved intracranial blood circulation. However, owing to inter-study heterogeneity, a prospective, multicenter RCT with a large sample is required to verify these results.

Cerebral vasomotor reactivity in migraine: effect of patent foramen ovale and aerogenic microembolism

OBJECTIVE

The first data on the effect of presence of patent foramen ovale (PFO) with high-volume right-to-left shunt (RLS) on cerebral vasomotor reactivity (CVMR) in migraineurs are herein presented. In addition, the immediate effect of air microbubbles on CVMR has been determined.

METHODS

Breath-holding index (BHI) and percent velocity decrease during hyperventilation (HPV) tests were performed before and after agitated saline injections in bilateral middle and posterior cerebral arteries (MCA and PCA) in 38 migraineurs (19 with aura) and 18 control subjects.

RESULTS

Presence of PFO correlated with a significant decrease of MCA BHI (1.43 ± 0.39 vs 1.04 ± 0.67, p = 0.032) and marginal reduction of PCA BHI (1.25 ± 0.46 vs. 1.01 ± 0.39, p = 0.090) in migraineurs. After agitated saline injection, PCA BHI significantly decreased from 1.03 to 0.78 (p = 0.007) in patients with PFO, from 1.15 to 0.91 (p = 0.014) in those without PFO, and from 1.01 to 0.76 (p = 0.023) in subjects with migraine and PFO. No significant MCA BHI difference was noted soon after bubble injection.

CONCLUSIONS

The presence of high grade RLS is associated with reduced vasodilatory CVMR in migraineurs. Further decrease of CVMR of PCA upon aerogenic microemboli passage may support the mechanism of 'facilitation with subclinical cerebral ischemia caused by microembolism', hypothesis explaining the onset of migraine.

ABBREVIATIONS

BHI: Breath-holding index; BHT: Breath Holding Test; CVMR: Cerebral vasomotor reactivity; EDV: End-diastolic velocity; HIT-6: Headache Impact Test; HPV: Hyperventilation; MCA: Middle cerebral artery; MIDAS: migraine disability Assessment score; PCA: Posterior cerebral artery; PFO: Patent foramen ovale; PI: Pulsatility index; PSV: Peak systolic velocity; RLS: Right-to-left shunt; TCD: Transcranial Doppler; Vmean: Mean velocity.

The orbitofrontal cortex functionally links obesity and white matter hyperintensities

Many studies have linked dysfunction in cognitive control-related brain regions with obesity and the burden of white matter hyperintensities (WMHs). This study aimed to explore how functional connectivity differences in the brain are associated with WMH burden and degree of obesity using resting-state functional magnetic resonance imaging (fMRI) in 182 participants. Functional connectivity measures were compared among four different groups: (1) low WMH burden, non-obese; (2) low WMH burden, obese; (3) high WMH burden, non-obese; and (4) high WMH burden, obese. At a large-scale network-level, no networks showed significant interaction effects, but the frontoparietal network showed a main effect of degree of obesity. At a finer node level, the orbitofrontal cortex showed interaction effects between periventricular WMH burden and degree of obesity. Higher functional connectivity was observed when the periventricular WMH burden and degree of obesity were both high. These results indicate that the functional connectivity of the orbitofrontal cortex is affected by the mutual interaction between the periventricular WMHs and degree of obesity. Our results suggest that this region links obesity with WMHs in terms of functional connectivity.

Impaired endothelial function may predict treatment response in restless legs syndrome

While dopaminergic dysfunction is believed to be a crucial role in restless legs syndrome (RLS), changes in peripheral microvasculature system such as peripheral hypoxia and altered skin temperature, have been found. This study aimed to investigate whether patients with RLS would have a cerebral and peripheral endothelial dysfunction, and this may have association with treatment responsiveness. We evaluated cerebral endothelial function using breath-holding index (BHI) on transcranial Doppler in bilateral middle cerebral artery (MCA), posterior cerebral artery (PCA) and basilar artery (BA) and peripheral endothelial function using brachial flow-mediated dilation (FMD) in 34 patients with RLS compared with age and sex-matched controls. The values of BHI in both MCA and BA were significantly lower in RLS group than control group. The values of FMD also were significantly lower in RLS patients. There was a weak correlation between BHI and FMD (p = 0.038 in Rt MCA, p = 0.032 in Lt MCA, p = 0.362 in BA) in RLS, but not in controls. BHI differed according to treatment responsiveness. (p < 0.005). Our study suggests that RLS patients have poorer cerebral and peripheral endothelial function than controls, showing an underlying mechanism of RLS and further evidence of a possible association between RLS and cardiovascular disease.