Basilar and Middle Cerebral Artery Reactivity in Patients With Migraine

Migraine chronification as an allostatic disorder: a proof-of-concept study

OBJECTIVE

The underpinning biologics of migraine chronification are not well understood. We aim to investigate the role of the cumulative burden of stress, namely the allostatic load, in migraine chronification.

METHODS

This was a cross-sectional study. The allostatic load was measured with a composite multi-system score (BALI: Bologna Allostatic Load Index), evaluating 20 biomarkers representing four physiological systems: immune, metabolic, cardiovascular, and neuroendocrinological systems. BALI score was subdivided into high score and low score based on the distribution in controls. Migraine patients were included and subclassified into low-frequency episodic migraine group (low-EM group), high-frequency episodic migraine group (high-EM group), and chronic migraine group (CM group).

RESULTS

The distribution of BALI high-score increased in parallel with headache attacks monthly frequency: 16% in low-EM group (n = 10), 24% in high-EM group (n = 12), and 40% in CM group (n = 21) (p = 0.017). In a multivariable analysis, the odds ratio of having a high-score BALI in CM patients (vs. low-EM patients) was 2.78 (95% CI 1.07-7.22; p = 0.036). Individual BALI biomarkers values which were significantly different among migraine subgroups included systolic blood pressure (p = 0.018), diastolic blood pressure (p < 0.001), and heart rate (p = 0.019).

CONCLUSION

Our study substantiates this emerging concept of migraine chronification as an allostatic disorder.

Optical Coherence Tomography Angiography: Revolutionizing Clinical Diagnostics and Treatment in Central Nervous System Disease

Optical coherence tomography angiography (OCTA), as a new generation of non-invasive and efficient fundus imaging technology, can provide non-invasive assessment of vascular lesions in the retina and choroid. In terms of anatomy and development, the retina is referred to as an extension of the central nervous system (CNS). CNS diseases are closely related to changes in fundus structure and blood vessels, and direct visualization of fundus structure and blood vessels provides an effective "window" for CNS research. This has important practical significance for identifying the characteristic changes of various CNS diseases on OCTA in the future, and plays a key role in promoting early screening, diagnosis, and monitoring of disease progression in CNS diseases. This article reviews relevant fundus studies by comparing and summarizing the unique advantages and existing limitations of OCTA in various CNS disease patients, in order to demonstrate the clinical significance of OCTA in the diagnosis and treatment of CNS diseases.

Prenatal dexamethasone exposure impaired vascular reactivity in adult male offspring cerebral arteries

BACKGROUND

Cerebrovascular disease is one of the leading causes of death worldwide. Middle cerebral artery (MCA) is the largest and most complex of cerebral arteries. The prenatal period is a critical time for development, which largely determines lifelong health. Clinically, glucocorticoids (GCs) administration to accelerate preterm fetal lung maturation has become standard practice. Prenatal GCs administration increases cardiovascular risks in offspring, but little is known regarding the side effects on offspring MCA function.

OBJECTIVE

We investigated the alterations of MCA reactivity following prenatal GCs administration in postnatal offspring.

METHOD AND RESULTS

Pregnant Sprague-Dawley rats received synthetic GCs (dexamethasone, DEX) during the last week of pregnancy, and we examined vascular reactivity, cellular electrophysiology, and gene promoter epigenetic modifications in the male offspring MCA. Our results showed that prenatal DEX exposure increased the sensitivity of offspring MCA to Angiotensin II, which was resulted from the increased Cav1.2 (L-type Ca2+ channels subunit alpha1 C). Mechanistically, prenatal DEX exposure resulted in a transcriptionally active chromatin structure at the Cav1.2 gene promoter by altering histone modifications. This activation led to increased expression of vascular Cav1.2 gene, ultimately resulting in increased MCA contractility in offspring.

CONCLUSION

The present study is the first to demonstrate that the adverse effects of prenatal GCs administration on cerebrovascular tone persist into adulthood, providing new insights into developmental origins of cerebrovascular disease.

Microvascular involvement in migraine: an optical coherence tomography angiography study

OBJECTIVE

The aim of this study was to evaluate the microvasculature of the macula and the optic nerve in patients affected by migraine with aura (MA) and without aura (MO) by optical coherence tomography angiography (OCTA), comparing the findings with healthy controls (HC).

METHODS

We collected data from ocular and orthotic examinations, including eye motility, intraocular pressure measurement, best-corrected visual acuity (BCVA) measurement, objective refraction measurement, fundus examination, macular and optic disk OCTA examination. All subjects were imaged with solix fullrange OCT. The following OCTA parameters were recorded: macular vessel density (VD), inside disc VD, peripapillary VD, disc whole image VD, fovea choriocapillaris VD, fovea VD, parafovea VD, peripapillary thickness, fovea thickness, parafovea thickness, macular full retinal thickness, and foveal avascular zone (FAZ) parameters. Clinical and demographical data about migraine patients were collected by a neurologist.

RESULTS

We included 56 eyes from 28 patients with a diagnosis of MO, 32 eyes from 16 patients with a diagnosis of MA, and 32 eyes from 16 HC subjects. The FAZ area was 0.230 ± 0.099 mm² in the MO group, 0.248 ± 0.091 mm² in the MA group and 0.184 ± 0.061 mm² in the control group. The FAZ area was significantly larger in the MA group than in the HC group (p = 0.007). The foveal choriocapillaris VD was significantly lower in MA patients (63.6 ± 2.49%) when compared with MO patients (65.27 ± 3.29%) (p = 0.02).

CONCLUSION

An impairment of retinal microcirculation can be detected in patients with MA, as demonstrated by the enlargement of FAZ. Moreover, the study of choroid circulation may reveal microvascular damage in patients with migraine with aura. OCTA is a useful non-invasive screening tool for the detection of microcirculatory disturbance in patients with migraine.

Cerebrovascular function in tension-type headache and migraine with or without aura: Transcranial Doppler study

The aim of the current study was to determine whether tension-type headache (TTH) and migraine with or without aura have altered anterior and posterior circulation compared with normal volunteers as assessed by Transcranial Doppler (TCD) ultrasonography. The study included 24 patients with chronic TTH and 37 patients with migraine (16 with aura and 21 without aura) classified according to the diagnostic criteria of the International Headache Society 2018. They were compared with a control group of 50 age- and sex-matched healthy volunteers. Each participant was examined with TCD ultrasonography of the middle, anterior and posterior cerebral and vertebral arteries (MCA, ACA, PCA, and VA) at rest. Patients in the TTH group had a significantly lower peak systolic velocity (PSV) and mean flow velocity (MFV) in the MCA compared with controls, whereas EDV and MFV in the ACA were significantly higher in the migraine without aura group than controls. Within the 3 groups of patients, the TTH group had significantly lower PSV in the MCA and PCA than the group of migraine with aura. In addition, the TTH group had significantly lower PSV and MFV in the MCA and a lower EDV in the VA than migraine patients without aura. In conclusion, the possibility of cerebrovascular changes is confirmed in the present study in both TTH and migraine without aura. The former has a low MFV in the MCA whereas the latter has a high MFV in the ACA.

Migraine-Associated Common Genetic Variants Confer Greater Risk of Posterior vs. Anterior Circulation Ischemic Stroke☆

OBJECTIVE

To examine potential genetic relationships between migraine and the two distinct phenotypes posterior circulation ischemic stroke (PCiS) and anterior circulation ischemic stroke (ACiS), we generated migraine polygenic risk scores (PRSs) and compared these between PCiS and ACiS, and separately vs. non-stroke control subjects.

METHODS

Acute ischemic stroke cases were classified as PCiS or ACiS based on lesion location on diffusion-weighted MRI. Exclusion criteria were lesions in both vascular territories or uncertain territory; supratentorial PCiS with ipsilateral fetal posterior cerebral artery; and cases with atrial fibrillation. We generated migraine PRS for three migraine phenotypes (any migraine; migraine without aura; migraine with aura) using publicly available GWAS data and compared mean PRSs separately for PCiS and ACiS vs. non-stroke control subjects, and between each stroke phenotype.

RESULTS

Our primary analyses included 464 PCiS and 1079 ACiS patients with genetic European ancestry. Compared to non-stroke control subjects (n=15396), PRSs of any migraine were associated with increased risk of PCiS (p=0.01-0.03) and decreased risk of ACiS (p=0.010-0.039). Migraine without aura PRSs were significantly associated with PCiS (p=0.008-0.028), but not with ACiS. When comparing PCiS vs. ACiS directly, migraine PRSs were higher in PCiS vs. ACiS for any migraine (p=0.001-0.010) and migraine without aura (p=0.032-0.048). Migraine with aura PRS did not show a differential association in our analyses.

CONCLUSIONS

Our results suggest a stronger genetic overlap between unspecified migraine and migraine without aura with PCiS compared to ACiS. Possible shared mechanisms include dysregulation of cerebral vessel endothelial function.

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.

The Vasodilatory Response to CGRP of the Anterior and Posterior Cerebral Circulation in Migraine

Introduction

Migraine aura can be associated with headache or it may occur without one, which suggests an independent mechanism for the aura and for migraine headache. The role of CGRP in migraine headache is well established, but the connection between CGRP and the aura is still lacking an explanation. Exogenous CGRP can induce CGRP headaches and migraine auras in patients with migraine. The results of our recent study suggest differences in the vascular response to CGRP stimulation between migraine without aura and migraine with aura. Therefore, we hypothesized that the magnitude of the posterior cerebral circulation response in migraine with aura is greater than in migraine without aura and that CGRP stimulation has different effects on the anterior and posterior circulation in migraine with aura and migraine without aura.

Methods

By using transcranial doppler, we studied the hemodynamic effects of CGRP intravenous infusion at a rate of 1.5 mcg/min in 20 min on the mean arterial velocity in the middle cerebral artery and in the posterior cerebral artery in twenty patients with migraine and in a control group of twenty healthy subjects. The same CGRP effects on cerebral hemodynamics were analyzed separately for the group of patients with migraine with aura and the group of patients with migraine without aura. Fifteen patients with migraine (75%) had migraine without aura and 5 patients (25%) had migraine with aura.

Results

We found that migraine has a significant impact on the vasodilatory response of the anterior (B = 4,249, SE = 1.023, r = 0.363, p < 0.001) and posterior cerebral circulation (B = 3.634, SE = 1.461, r = 0.227, p = 0.014). Migraine with aura was significantly associated with changes in the anterior (B = 2.558, SE = 0.880, r = 0.275, p = 0.005) and posterior cerebral circulation (B = 7.565, SE = 2,368, r = 0.359, p = 0.002), while migraine without aura was only significantly associated with changes in the anterior circulation. In addition, we established a significant impact of migraine with aura on VR PCA (B = 5.901, SE = 2,546, r = 0.291, p = 0.024).

Conclusion

We conclude that TVR in the posterior cerebral circulation might be enhanced in MA and that aura might be a consequence of TVR enhancement.

Basilar artery curvature is associated with migraine with aura in the Northern Manhattan Study

INTRODUCTION

Genetic and imaging studies demonstrate a link between vascular morphology and migraine with aura (MA). We examined the relationship between basilar artery (BA) curvature and MA in a population-based cohort of stroke-free participants.

METHODS

This cross-sectional study included participants from the MRI substudy of the Northern Manhattan Study. Participants had structured migraine assessments at enrollment and underwent brain MR angiography. BA curvature was defined as the sum of the total BA horizontal deviation from midline at the distal tip, mid-pons, and vertebrobasilar junction, and was the primary independent variable in logistic regression analyses. BA measurements were obtained blinded to migraine status. We compared groups of all migraine vs no migraine, migraine without aura (MwoA) vs no migraine, and MA vs no migraine.

RESULTS

Of 880 participants, 146 had MwoA and 32 had MA. Average BA curvatures were 15.2 ± 8.9 mm in non-migraineurs, 15.8 ± 9.3 mm in MwoA, and 18.5 ± 11.4 mm in MA. In an adjusted model, greater BA curvature was associated with MA (OR 1.042 per mm, 95% CI 1.006-1.080) but not with MwoA (OR 1.014 per mm, 95% CI 0.993-1.035), when compared to non-migraineurs.

CONCLUSIONS

Greater BA curvature was associated with MA. Given aura typically originates from the occipital cortex, understanding the physiopathology of this association may provide clues to migraine's underlying mechanisms and relationship with stroke.

Cerebrovascular Risk-Factors of Prevalent and Incident Brain Infarcts in the General Population: The AGES-Reykjavik Study

BACKGROUND AND PURPOSE

Studies on the association of cerebrovascular risk factors to magnetic resonance imaging detected brain infarcts have been inconsistent, partly reflecting limits of assessment to infarcts anywhere in the brain, as opposed to specific brain regions. We hypothesized that risk-factors may differ depending on where the infarct is located in subcortical-, cortical-, and cerebellar regions.

METHODS

Participants (n=2662, mean age 74.6±4.8) from the longitudinal population-based AGES (Age, Gene/Environment Susceptibility)-Reykjavik Study underwent brain magnetic resonance imaging at baseline and on average 5.2 years later. We assessed the number and location of brain infarcts (prevalent versus incident). We estimated the risk-ratios of prevalent (PRR) and incident (IRR) infarcts by baseline cerebrovascular risk-factors using Poisson regression.

RESULTS

Thirty-one percent of the study participants had prevalent brain infarcts and 21% developed new infarcts over 5 years. Prevalent subcortical infarcts were associated with hypertension (PRR, 2.7 [95% CI, 1.1-6.8]), systolic blood pressure (PRR, 1.2 [95% CI, 1.1-1.4]), and diabetes (PRR, 2.8 [95% CI, 1.9-4.1]); incident subcortical infarcts were associated with systolic (IRR, 1.2 [95% CI, 1.0-1.4]) and diastolic (IRR, 1.3 [95% CI, 1.0-1.6]) blood pressure. Prevalent and incident cortical infarcts were associated with carotid plaques (PRR, 1.8 [95% CI, 1.3-2.5] and IRR, 1.9 [95% CI, 1.3-2.9], respectively), and atrial fibrillation was significantly associated with prevalent cortical infarcts (PRR, 1.8 [95% CI, 1.2-2.7]). Risk-factors for prevalent cerebellar infarcts included hypertension (PRR, 2.45 [95% CI, 1.5-4.0]), carotid plaques (PRR, 1.45 [95% CI, 1.2-1.8]), and migraine with aura (PRR, 1.6 [95% CI, 1.1-2.2]). Incident cerebellar infarcts were only associated with any migraine (IRR, 1.4 [95% CI, 1.0-2.0]).

CONCLUSIONS

The risk for subcortical infarcts tends to increase with small vessel disease risk-factors such as hypertension and diabetes. Risk for cortical infarcts tends to increase with atherosclerotic/coronary processes and risk for cerebellar infarcts with a more mixed profile of factors. Assessment of risk-factors by location of asymptomatic infarcts found on magnetic resonance imaging may improve the ability to target and optimize preventive therapeutic approaches to prevent stroke.

Profiling cerebrovascular function in migraine: A systematic review and meta-analysis

Previous studies have investigated whether migraine is a circulatory disorder, as migraineurs are at heightened risk of cerebrovascular disease. However, in most cases, systemic vascular function was evaluated, which may not reflect abnormalities in the cerebral circulation. Therefore, we aimed to determine whether cerebrovascular function differs between migraineurs and controls. A systematic literature search was conducted across three electronic databases to search for studies that compared cerebrovascular function in migraineurs to controls. Where applicable, meta-analyses were used to determine standardised mean differences (SMD) between migraineurs and controls. Seventy articles were identified, 40 of which contained quantitative data. Meta-analyses showed pulsatility index (PI) was higher (SMD = 0.23; 95%CI = 0.05 to 0.42, P = 0.01) and cerebrovascular responsiveness (CVR) to hypercapnia was lower (SMD=-0.34; 95%CI=-0.67 to -0.01, P = 0.04) in the posterior circulation of migraineurs, particularly those without aura. The meta-analyses also indicated that migraineurs have higher resting mean blood flow velocity in both anterior (SMD = 0.14; 95%CI = 0.05 to 0.23, P = 0.003) and posterior circulations (SMD = 0.20; 95%CI = 0.05 to 0.34, P = 0.007). Compared to healthy controls, migraineurs have altered cerebrovascular function, evidenced by elevated PI (representing arterial stiffness) and impaired CVR to hypercapnia (representing cerebral vasodilator function). Future studies should investigate whether improvement of cerebrovascular function is able to alleviate migraine.

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.

The Role of Endothelial Dysfunction in the Pathophysiology and Cerebrovascular Effects of Migraine: A Narrative Review

Background and Purpose

Migraine is a complex neurovascular disorder whose triggers are not entirely understood. Endothelial dysfunction might play a role in migraine, and there have been numerous reports on endothelium dysfunction and migraine pathophysiology, but their reciprocal cause–effect relationship remains unclear. This review reports the current evidence on endothelium dysfunction, its link with migraine, and its possible consequences for cerebral hemodynamics.

Methods

We performed a systematic literature search of PubMed up to March 2020. We included 115 articles in a narrative review.

Results

Several studies have demonstrated that endothelium dysfunction may play an important role in migraine. Despite the lack of specific biomarkers, there is evidence of oxidative stress and inflammation—two of the primary causes of endothelial damage—in migraine. The main consequences of endothelial dysfunction are increased vascular tone, thrombosis, inflammation, and increased vascular permeability. As a consequence of oxidative stress, the activity of endothelin-1 is not counterbalanced by nitric oxide (NO), whose levels decrease to lead to vasoconstriction and a possible contribution to cortical spreading depression. NO is involved in pain perception via the cyclic guanosine monophosphate (cGMP) pathway and the induction of calcitonin gene-related peptide. Oxidative stress may induce a hypercoagulable state that mainly affects platelet function through different mechanisms. Endothelial dysfunction seems to be particularly pronounced in migraine with aura (MA). Endothelial dysfunction in migraine particularly involves intracranial vessels, since flow-mediated dilation cannot detect overt peripheral vascular dysfunction.

Conclusions

Endothelial dysfunction is a vascular risk marker. How it impacts migraine, and particularly MA, needs to be understood better by defining its possible role in increasing the stroke risk in migraine patients.

Transcranial Doppler Evaluation of the Cerebral Vasculature in Women Patients who Have Migraine with Aura

BACKGROUND

Previous studies suggest that increased cerebrovascular reactivity might be a feature of patients who have migraine with aura (MwA). The correlation between the clinical presentation of migraine with aura and transcranial Doppler parameters remains unclear.

OBJECTIVE

The main aim of this study was to explore cerebral blood flow, vascular resistance, and cerebrovascular reactivity in women MwA. Also, the relationships between hemodynamic conditions and aura characteristics are examined.

DESIGN

Cross-sectional study.

SETTING

Headache Center, Neurology Clinic, Clinical Center of Serbia.

SUBJECTS

Fifty-four women MwA and 49 healthy controls (HCs).

METHODS

Transcranial Doppler sonography examination was used to determine blood flow mean velocity (MV) and pulsatility index (PI), as well as breath-holding index (BHI), in 15 arterial segments comprising the circle of Willis.

RESULTS

A total of 54 women MwA and 49 HCs were studied. The PIs of all segments of the left and right middle cerebral arteries and the left and right anterior cerebral arteries were significantly higher in MwA with regards to HCs. Also, both the left and right BHIs were significantly higher in MwA than HCs. In addition, MVs of the right vertebral artery and the first segment of the basilar artery were significantly lower in MwA than HCs. Longer duration of migraine aura showed a weak negative correlation with the PI of the left posterior cerebral artery.

CONCLUSIONS

Our findings suggest increased vessel pulsatility, abnormal cerebrovascular reactivity, and decreased cerebral blood flow velocity in several arterial segments of the Willis circle in women MwA.

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.

Objective Diagnosis of Migraine without Aura with Migraine Vascular Index: A Novel Formula to Assess Vasomotor Reactivity

This pilot study was aimed at developing an objective method to diagnose migraine by measuring the difference in vasomotor reactivity between migraineurs and non-migraineurs. Thirty patients diagnosed with migraine without aura and 30 healthy patients were recruited. Vasomotor reactivity of all patients was then assessed by measuring the breath holding index (BHI), hyperventilation index and a novel formula, the migraine vascular index (MVI), of the middle cerebral artery using transcranial Doppler ultrasonography. Migraineurs were found to have significantly lower BHI and MVI values (p < 0.001). Logistic regression analysis revealed that MVI was a significant independent predictor of migraine (p = 0.007). The sensitivity and specificity of MVI in diagnosing migraine with a cutoff value of 1.035 were 86.7% and 86.7%, respectively. In conclusion, MVI measurement is a reliable method for objectively diagnosing migraine. Further research is needed to validate the usage of MVI for migraine diagnosis.

Cerebral vascular reactivity and the migraine-stroke relationship: A narrative review

Migraine, and especially migraine with aura, is associated with an increased risk of stroke and vascular events; however, the reasons for this association are unclear. Several studies evaluated cerebral autoregulation and vasomotor reactivity in patients with migraine compared with non-migraineurs, with conflicting results. Our narrative review aimed at summarizing their results to find the most reliable evidence in the field. Studies which used visual stimuli to evoke vascular responses consistently showed an increased vascular reactivity in migraineurs compared with non-migraineurs, while studies which used systemic stimuli such as hyper- or hypocapnia showed inconsistent results. Therefore, central neural mechanisms might be more important than peripheral vascular mechanisms in determining the cerebral vascular responses of patients with migraine. However, a large body of evidence supports the existence of peripheral vascular dysfunction in patients with migraine. Further studies are needed to explain the complex interactions between central neural and peripheral vascular mechanisms in determining migraine and its vascular risk. Migraine preventive treatments, and especially the most recent ones with a peripheral action, might provide important insights in this field.

Right-to-left shunts and hormonal therapy influence cerebral vasomotor reactivity in patients with migraine with aura

Patent Foramen Ovale and impaired cerebral hemodynamics were proposed among the pathophysiological mechanisms explaining the increased risk for stroke in patients with Migraine with Aura (MA). Our study aimed at comparing the vasomotor reactivity (VMR) of the anterior and the posterior cerebral circulation in patients with Migraine with Aura, in patients with acute vascular ischemic accidents, and in controls. We hypothesized that VMR in MA patients is preserved in the anterior circulation and reduced in the posterior circulation. We prospectively assessed with Transcranial Doppler the vasomotor reactivity to breath holding of the Middle and Posterior Cerebral Arteries (MCA, PCA) in MA patients, in acute vascular patients and healthy controls. We also evaluated the possible effect of clinical characteristics of MA (attack frequency, aura length or type, disease history), vascular factors and the presence of right-to-left shunt on VMR. Diverging from our hypothesis, MA patients displayed a higher breath-holding index (BHI) than controls in the MCA (1.84±0.47%/s vs 1.53±0.47%/s, p = .001) as well as in the PCA (1.87±0.65%/s vs 1.47±0.44%/s, p < .001). In MA patients, MCA BHI was higher in those with large right-to-left shunts (2.09±0.42 vs 1.79±0.47, p = .046) and lower in those taking estrogens (1.30±0.30%/s vs 1.9±0.45%/s, p = .009). We did not observe an effect of MA characteristics on BHI. The increased BHI in MA patients with large right-to-left shunts could be explained by the vasoactive effect in the cerebral circulation of substances bypassing the deactivating pulmonary filters or by a constitutional trait of the vascular system associating persistent right-to-left shunts and hyper-reactive hemodynamics. Our results discourage the hypothesis that altered hemodynamics contribute to increasing the stroke risk in all MA patients. However, estrogens can lower VMR, curtailing the hemodynamic resources of MA patients.

Cerebral Hemodynamic Changes During Migraine Attacks and After Triptan Treatments

Introduction

Migraine has been known for many years, but its mechanism remains unclear. Different cerebral hemodynamic changes have been observed at different stages of a migraine attack. Published results on cerebral hemodynamics are contradictory. For this reason, we aimed to investigate cerebral hemodynamic changes during attacks as well as the effects of frovatriptan and rizatriptan.

Methods

Forty migraine patients with aura using rizatriptan (n=20) and frovatriptan (n=20) and 20 healthy individuals were included in our study. Cerebral blood flow velocities and breath-holding indices were recorded bilaterally from middle and posterior cerebral arteries. All procedures were repeated one hour after treatments and one week after attacks.

Results

We observed similar values of cerebral blood flow velocities and breath holding indices in all patients with migraine during the attack-free period compared to the control group. All cerebral vascular structures in migraine patients had significantly lower cerebral blood flow velocities and higher values in breath-holding indices during attacks. After taking rizatriptan and frovatriptan for an attack, the changes in hemodynamics disappeared.

Conclusion

During attacks of migraineurs with aura, vasodilatation develops. In addition, higher vasomotor reactivity during attacks supports hypersensitivity in migraine pathophysiology. Triptans, acting as vasoconstrictor agents, were able to stop over-vasodilatation during attacks. In other words, it is possible that triptans show their effects by eliminating vascular hypersensitivity during acute attacks.

Interictal cerebral and systemic endothelial dysfunction in patients with migraine: a case-control study

BACKGROUND

Although systemic endothelial function is unimpaired in migraine, it is unknown whether cerebral endothelial function impairment exists in migraineurs.

MATERIALS AND METHODS

We conducted a prospective study to assess endothelial function in migraineurs (n=45) and healthy volunteers (n=44). Cerebral endothelial function was assessed by Breath Holding Index (BHI) on transcranial Doppler in bilateral middle cerebral artery (MCA at 30-60 mm), posterior cerebral artery (PCA at 60-80 mm) and basilar artery (BA at 80-120 mm) using bilateral monitoring probes fixed on headband. Brachial artery flow-mediated dilation (FMD) was used as measure of systemic endothelial function.

RESULTS

There was no difference in baseline mean velocities of MCA, PCA, BA among migraineurs and controls. Mean BHI was significantly lower in PCA (p<0.001) and BA (p<0.001) in patients with migraine with no difference in MCA (p=0.909, 0.450). Cerebral endothelial dysfunction (BHI<1.15) was present in 62.2% of migraineurs in the right PCA (p<0.001), 57.8% in left PCA (p<0.001) and 77.8% in BA (BHI <0.83, p<0.001). There was no difference in BHI among migraineurs without and with aura (n=15). Cerebral and systemic endothelial function had no correlation in migraineurs. Increasing BMI was identified as a predictor of impaired BHI in the BA in migraineurs (p=0.020). Age, sex, presence of aura, lateralisation of headache, headache frequency, time to last attack and impaired FMD were not associated with impaired PCA and BA BHI in migraineurs.

CONCLUSIONS

Migraineurs may have isolated cerebral endothelial dysfunction restricted to the posterior circulation in the absence of systemic endothelial dysfunction.

Systemic and cerebral endothelial dysfunction in chronic migraine. A case-control study with an active comparator

BACKGROUND AND OBJECTIVE

Unlike migraine and migraine with aura, little information exists regarding chronic migraine (CM) as a risk factor for cardiovascular disease. In this study we aim to determine whether an association between CM and endothelial dysfunction exists.

METHODS

Individuals 18 years and older diagnosed with episodic migraine (EM) and CM according to ICHD criteria were studied. After an overnight fast and abstinence from vasoactive drugs, ultrasound studies were performed and blood samples taken from patients and matched controls according to internationally agreed on protocols.

RESULTS

A total of 113 individuals were enrolled (35 CM, 37 EM, 41 controls). CM patients had a lower percentage of flow-mediated vasodilation (FMD; difference of means = 5.03%; p = 1.0E-6) and breath-holding index (BHI; difference of means 0.754; p = 2.0E-6), as well as increased carotid intima media thickness (cIMT; difference of means = 0.128 mm; p = 7.0E-5) than controls. The EM patients and controls comparison found similar, but less pronounced, differences: decreased BHI (p = 0.031), and increased cIMT (p = 0.028). Fibrinogen (r = 0.277; p = 0.006), C-reactive protein (r = 0.288; p = 0.003), and erythrocyte rate sedimentation (r = 0.298; p = 0.002) also correlated with cIMT, and inversely with BHImV and FMD.

CONCLUSIONS

Migraine is associated with systemic and cerebral endothelial dysfunction demonstrated by ultrasound studies and biological markers. The degree of these changes was strongly associated with the severity of migraine. Our data indicate that migraine may be a cerebral disorder with systemic endothelial damage.

Reduced breath holding index in patients with chronic migraine

Migraine is a neurovascular disorder characterized by autonomic nervous system dysfunction and severe headache attacks. Studies have shown that changes in the intracranial vessels during migraine have an important role in the pathophysiology. Many studies have been conducted on the increased risk of stroke in patients with migraine, but insufficient data are available on the mechanism underlying the increase. This study aimed to evaluate basal cerebral blood flow velocity and vasomotor reactivity in patients with chronic migraine. We evaluated 38 patients with chronic migraine. Three of them were excluded because they had auras and four of them were excluded because of their use of medication that can affect cerebral blood flow velocity and breath holding index (beta or calcium channel blockers). Our study population consisted of 31 patients with chronic migraine without aura and 29 age- and gender-matched healthy individuals who were not taking any medication. The mean blood flow velocity and breath holding index were measured on both sides from the middle cerebral artery and posterior cerebral artery, with temporal window insonation. The breath holding index for middle cerebral artery and posterior cerebral artery was significantly lower in the migraine group compared to that of the control group (p < 0.05).The vasomotor reactivity indicates the dilatation potential of a vessel, and it is closely related to autoregulation. According to our results, the vasodilator response of cerebral arterioles to hypercapnia was lower in patients with chronic migraine. These findings showed the existence of impairments in the harmonic cerebral hemodynamic mechanisms in patients with chronic migraine. This finding also supports the existing idea of an increased risk of stroke in patients with chronic migraine due to impaired vasomotor reactivity.

Is there a persistent dysfunction of neurovascular coupling in migraine?

Changes in cerebral blood flow are one of the main features of migraine attack and have inspired the vascular theory of migraine. This traditional view has been reshaped with recent experimental data, which gave rise to the neural theory of migraine. In this review, we speculate that there might be an important link between the two theories, that is, the dysfunction of neurovascular coupling.

Endothelial function in migraine with aura - a systematic review

BACKGROUND

An increased risk of ischemic stroke is repeatedly reported in young subjects with migraine with aura (MA). Such may be caused by changes in endothelial function. The present review evaluates current evidence on endothelial function in MA patients.

METHODS

A systematic search of electronic databases (Medline, Embase, Cochrane library) was performed, and a search in associated reference lists of identified studies was done.

RESULTS

In total, 27 studies met inclusion criteria for this review. Six studies assessed endothelial function by flow-mediated dilation; four reported no differences compared with healthy subjects, one study reported an increase and one study a decrease in migraineurs. Peripheral arterial tonometry was applied in one study where no changes were detected between groups. Likewise, applying venous occlusion plethysmography elicited comparable responses. Arterial function was investigated in six studies; increased augmentation index and decreased arterial distensibility were reported in migraineurs, whereas findings regarding pulse wave velocity were dissimilar. However, when investigating levels of endothelial progenitor cells, two studies reported reduced levels in migraineurs, and several studies on endothelial markers in the areas of inflammation, oxidative stress, and coagulation found increased endothelial activation in migraineurs, particularly in MA. One study, assessing cerebral endothelial function using transcranial Doppler sonography, reported lower cerebrovascular reactivity to L-arginine in the posterior cerebral arteries in migraineurs.

CONCLUSION

Endothelial dysfunction appears not to be of importance in MA patients. However, the studies were few with a wide variety of techniques applied in small groups of patients. Endothelial biomarkers were increased in patients indicating a possible subtle change in the endothelium. Further investigations on larger groups of patients combining testing of endothelial dysfunction as well as biomarkers are warranted to identify whether or not endothelial changes may play a role in the increased risk of stroke in young MA patients.

Migraine and stroke: in search of shared mechanisms

BACKGROUND

Migraine, particularly with aura, increases the risk for ischemic stroke, at least in a subset of patients. The underlying mechanisms are poorly understood and probably multifactorial.

METHODS

We carried out an extended literature review of experimental and clinical evidence supporting the association between migraine and ischemic stroke to identify potential mechanisms that can explain the association.

RESULTS

Observational, imaging and genetic evidence support a link between migraine and ischemic stroke. Based on clinical and experimental data, we propose mechanistic hypotheses to explain the link, such as microembolic triggers of migraine and enhanced sensitivity to ischemic injury in migraineurs.

DISCUSSION

We discuss the possible practical implications of clinical and experimental data, such as aggressive risk factor screening and management, stroke prophylaxis and specific acute stroke management in migraineurs. However, evidence from prospective clinical trials is required before modifying the practice in this patient population.

Understanding migraine through the lens of maladaptive stress responses: a model disease of allostatic load

The brain and body respond to potential and actual stressful events by activating hormonal and neural mediators and modifying behaviors to adapt. Such responses help maintain physiological stability ("allostasis"). When behavioral or physiological stressors are frequent and/or severe, allostatic responses can become dysregulated and maladaptive ("allostatic load"). Allostatic load may alter brain networks both functionally and structurally. As a result, the brain's responses to continued/subsequent stressors are abnormal, and behavior and systemic physiology are altered in ways that can, in a vicious cycle, lead to further allostatic load. Migraine patients are continually exposed to such stressors, resulting in changes to central and peripheral physiology and function. Here we review how changes in brain states that occur as a result of repeated migraines may be explained by a maladaptive feedforward allostatic cascade model and how understanding migraine within the context of allostatic load model suggests alternative treatments for this often-debilitating disease.

Peripheral endothelial function and arterial stiffness in women with migraine with aura: a case-control study

BACKGROUND

Vascular dysfunction may be involved in migraine pathophysiology and contribute to the increased risk of ischemic stroke in migraine, particularly in women with migraine with aura (MA). However, data on endothelial function in MA are controversial. Here, we investigated whether systemic endothelial function and arterial stiffness are altered in women with MA, using a novel peripheral arterial tonometry device for the first time.

METHODS

Twenty-nine female MA patients without comorbidities and 30 healthy women were included, and carotid intima-media thickness was assessed by a standardized procedure. Endothelial function was assessed using peripheral arterial tonometry. Reactive hyperaemic response of digital pulse amplitude was measured following 5 minutes of forearm occlusion of the brachial artery. Arterial stiffness was assessed by fingertip tonometry derived and heart-rate-adjusted augmentation index.

RESULTS

No differences were found in peripheral arterial tonometry ratio (2.3 ± 0.6 vs 2.2 ± 0.8; p = 0.58) and left carotid intima-media thickness (in µm: 484 ± 119 vs 508 ± 60; p = 0.37). Women with MA had higher heart-rate-averaged augmentation index [median (interquartile range, IQR) of 5 (IQR 0.5 to 18) vs -5 (IQR -16.8 to 8.3), p = 0.005] and heart-rate-adjusted augmentation index [1 (IQR -6 to 12.5) vs -8 (IQR -20.3 to 2.5), p = 0.008] than healthy controls.

CONCLUSION

Peripheral endothelial function is not impaired in women with MA, but they have greater arterial stiffness. This may contribute to the increased stroke risk in women with MA.

Cerebellar and Cerebral Autoregulation in Migraine

Background and Purpose—

Silent ischemic brain lesions frequently occur in migraine with aura and are most often located in cerebellar border zones. This may imply an impairment of cerebellar blood flow autoregulation. This study investigated the characteristics of interictal cerebellar autoregulation in migraine with and without aura.

Methods—

Thirty-four patients (n=17, migraine without aura; n=17, migraine with aura) and 35 age- and sex-matched controls were studied. Triple simultaneous transcranial Doppler monitoring of one posterior inferior cerebellar artery, right posterior cerebral artery, and left middle cerebral artery was performed. Autoregulation dynamics were assessed from spontaneous blood pressure fluctuations (correlation coefficient index Dx) and from respiratory-induced 0.1-Hz blood pressure oscillations (phase and gain).

Results—

Compared with controls, the autoregulatory index Dx was higher (indicating less autoregulation) in the posterior inferior cerebellar artery ( P =0.0062) and middle cerebral artery ( P =0.0078) in migraine with aura, but not in migraine without aura. Phase and gain did not significantly differ between migraine patients and controls. No significant associations of autoregulation with clinical factors were found, including frequency of migraine attacks and orthostatic intolerance.

Conclusions—

This first-time analysis of cerebellar autoregulation in migraine did not show a specific cerebellar dysautoregulation in the interictal period. More static autoregulatory properties (index Dx) are, however, impaired in persons with migraine with aura both in the cerebellar and anterior circulation. The cerebellar predilection of ischemic lesions in migraine with aura might be a combination of altered autoregulation and additional factors, such as the end artery cerebellar angioarchitecture.

Cerebrovascular reactivity to l-arginine in the anterior and posterior cerebral circulation in migraine patients

OBJECTIVE - Cerebral infarction preferentially affects the posterior cerebral artery distribution in migraine patients. The results obtained from the few known studies that have compared the anterior and posterior cerebral endothelial function are contradictory. To the best of our knowledge, cerebrovascular reactivity to L-arginine (CVR), measured by transcranial Doppler sonography (TCD), has not been previously used to determine the posterior cerebral endothelial function in migraine patients with (MwA) and without aura (MwoA). MATERIALS AND METHODS -  Forty migraine patients without comorbidities (20 MwA, 20 MwoA) and 20 healthy subjects were included. By employing strict inclusion criteria, we avoided the possible vascular risk factors. Mean arterial velocity in the middle cerebral artery (MCA) and the posterior cerebral artery (PCA) was measured by TCD before and after infusion of L-arginine, and CVR to L-arginine was then calculated. RESULTS - All migraine patients had lower CVR to L-arginine in PCA (P = 0.002) and similar in MCA (P = 0.29) compared to healthy subjects. This difference was also present in MwA and MwoA compared to healthy subjects (P = 0.003). CONCLUSIONS -  Lower CVR to L-arginine in PCA in migraine patients could associate migraine and cerebral infarcts that are more common in the posterior cerebral artery distribution.

Endothelium-dependent vasodilatation in migraine patients

BACKGROUND

Endothelial dysfunction could be involved in the pathophysiology of migraine. The results obtained from a few studies on endothelial dysfunction in migraine are controversial. We investigated brachial flow-mediated dilatation (FMD), which reflects systemic endothelial dysfunction, in migraine patients without comorbidities. By employing strict inclusion criteria we avoided the possible changes to FMD from confounding factors.

METHODS

Forty migraine patients without comorbidities (20 with and 20 without aura) and 20 healthy subjects were included. FMD of brachial arteries and carotid intima-media thickness were measured by using standard procedures.

RESULTS

We did not find any difference in FMD between migraine patients and healthy subjects (p = .96). Also, no differences were found among healthy subjects, migraine patients with aura and without aura (p = .99).

CONCLUSION

Our study showed that systemic endothelial function is not impaired in migraine patients without comorbidities, neither in those with or without aura. Considering these findings, the investigation of cerebral endothelial function would be useful in a further investigation of the role of endothelial (dys)function in migraine pathophysiology.

Evaluation of cerebral vasomotor reactivity in Parkinson's disease: is there any association with orthostatic hypotension?

OBJECTIVE

Our aim was to look for a probable relationship between cerebral vasomotor reactivity (VMR) and orthostatic hypotension (OH) in Parkinson's disease (PD).

MATERIALS AND METHODS

This study was conducted on 44 patients with PD. Assessment of cerebral VMR was performed by means of transcranial Doppler (TCD) of middle cerebral artery (MCA) before and after a vasodilatory stimulus, carbon dioxide test. Moreover, orthostatic hypotension was evaluated.

RESULTS

OH was presented in 12 (27.3%) Parkinson's patients. The average resting blood flow velocity (BFV) in the MCA was 30.20 (SD=9.58)cms(-1) which significantly increased to 46.25 (SD=16.23)cms(-1) after carbon dioxide test (P<0.001). Impaired VMR was observed in 15 (34.1%) of the subjects, while it was not associated with the presence of OH (P=0.770).

CONCLUSION

Evaluation of VMR in patients affected by PD, could assist in early diagnosis of cerebral autonomic dysfunction and prevent its serious consequences prior and more valid to OH.

Joint Metabonomic and Instrumental Analysis for the Classification of Migraine Patients with 677-MTHFR Mutations

Migraine is a neurological disorder that correlates with an increased risk of cerebrovascular lesions. Genetic mutations of the MTHFR gene are correlated to migraine and to the increased risk of artery pathologies. Also, migraine patients show altered hematochemical parameters, linked to an impaired platelet aggregation mechanism. Hence, the vascular assessment of migraineurs is of primary importance.Transcranial Doppler sonography (TCD) is used to measure cerebral blood flow velocity (CBFV) and vasomotor reactivity (by an index measured during breath-holding - BHI). Aim of this study was the metabolic profiling of migraine subjects with T/T677-MTHFR and C/T677-MTHFR mutations and its correlation with CBFV and BHI.Metabonomic multidimensional techniques were used to describe and cluster subjects. Fifty women suffering from migraine (age: 18-64; 21 with aura) underwent TCD examination, hematochemical blood analysis, Born test, and genetic tests for MTHFR mutation. Fourteen (7 with aura) had T/T677, 18 (8 with aura) had C/T677, and 18 (6 with aura) had no mutation. The total number of variables was 24.Unsupervised and supervised techniques_showed the correlation between CBFV and BHI with mutation. Discriminant analysis allowed for classifying the subjects with 95.9% sensitivity and 89.0% specificity. Aura was not correlated to mutation or variations of instrumental data.Our study showed that metabonomics could be effectively applied in clinical problems to show the overall correlation structure of complex systems in pathology. Specifically, our results confirmed the importance of TCD in the metabolic profiling and follow-up of migraine patients.

Migraine and patent foramen ovale: state of the science

Migraine is a prominent cause of recurrent pain, affecting 12% of the population. In several case series, approximately 50% of migraineurs with aura were found to have patent foramen ovale (PFO). The pathophysiological mechanism is speculated to be passage of microemboli and vasoactive chemicals through the PFO, thereby evading pulmonary filtration and triggering migraine symptoms. This article presents the results of retrospective and prospective research studies documenting the effects of PFO closure on migraine symptoms and presents emerging theories on possible pathologic mechanisms that may partially explain the increased risk of ischemic stroke in the migraine population. Finally, evidence-based recommendations are presented for health care providers for managing patients who have migraine and PFO.

Migraine as a systemic vasculopathy

Epidemiological studies suggests that migraine is associated with disorders of the cerebral, coronary, retinal, dermal and peripheral vasculature. There is evidence that migraine is associated with endothelial dysfunction, both as a cause and a consequence. Endothelial dysfunction, a vascular risk factor, is characterized by endothelial activation and impaired vascular reactivity. Plasma and genetic biomarkers for these conditions have been identified. The clinical significance lies in the potential for the rapid identification of migraineurs at increased risk of ischaemic stroke and vascular disease through ascertainment of endothelial dysfunction biomarkers. It is uncertain whether stroke, myocardial infarction and other vasculopathies can be prevented by migraine prophylaxis, endothelial repair, platelet inhibition or a combination of these strategies.

Effects of acute hypoxia and hyperthermia on the permeability of the blood-brain barrier in adult rats

Acute mountain sickness (AMS) develops within a few hours after arrival at high altitude and includes headache, anorexia, nausea, vomiting, and malaise. This afflicts 15-25% of the general tourist population at moderate altitudes. High-altitude cerebral edema (HACE) is considered to be the end stage of severe AMS and has been suggested to be a vasogenic edema, raising the possibility that acute hypoxia may increase blood-brain barrier (BBB) permeability. At present, there are no good small-animal models to study this syndrome. We hypothesize 1) that acute hypoxia can damage the BBB and 2) that rat can be used as a model to study hypoxia-induced changes in BBB permeability, especially if hypoxia-induced hypothermia could be minimized with high ambient temperature (HAT). Male Wistar rats were exposed to 1, 2, and 7 days of hypobaric hypoxia (equivalent to 0.5 atm), and changes in the temperature and BBB permeability were studied. The extravasation of endogenous immunoglobulin G, a large molecule, did not increase during room temperature hypoxia but did increase when hypoxia was combined with HAT. Hypoxia caused a significant increase in the leakage of sodium fluorescein (mol wt 376 Da). The expression of endothelial barrier antigen (EBA), a protein associated with the BBB, was reduced to 50% between 24 and 48 h after exposure to hypoxia, and the loss was exacerbated by HAT. The values almost returned to control levels by 7 days, showing adaptation to hypoxia. Hypoxic rats exhibited sodium fluorescein leakage mainly in focal areas in the brain parenchyma. In conclusion, it is possible to have transient BBB damage through exposure to acute hypoxia, and this damage is exacerbated by increasing body temperature to more of a normothermic value.

Increased cerebral vasomotor reactivity in migraine with aura: an autoregulation disorder? A transcranial Doppler and near-infrared spectroscopy study

Migraine with aura (MA) is associated with changes in cerebral blood flow (CBF), whereas the role of cerebral autoregulation is uncertain. This study aimed to evaluate basal CBF, cerebral blood volume (CBV) and vasomotor reactivity (VMR) in MA patients. Twenty-one controls and 16 MA patients (eight with side predominance) underwent simultaneous examination of flow velocity in the middle cerebral arteries by transcranial Doppler (TCD) and of near-infrared spectroscopy (NIRS) parameters [oxygen haemoglobin saturation: oxygen%, and total haemoglobin content (THC)] at rest and after hypercapnia. Cerebral VMR, THC and oxygen% increases were significantly greater on the predominant compared with the non-predominant migraine side, with both sides of patients without side predominance and with controls. These findings suggest altered autoregulation in MA patients, possibly secondary to impaired cerebrovascular autonomic control. Simultaneous TCD and NIRS investigation could represent a non-invasive approach to evaluate cerebral haemodynamics at the cortical and subcortical level.

Voxel-based morphometry reveals gray matter abnormalities in migraine

BACKGROUND

Migraine is generally considered a functional brain disorder lacking structural abnormalities. Recent magnetic resonance imaging (MRI) studies, however, suggested that migraine may be associated with subtle brain lesions.

OBJECTIVE

We evaluated the presence of global or focal gray or white matter alterations in migraine patients using voxel-based morphometry (VBM), a fully automated method of analyzing changes in brain structure. VBM data also were used to evaluate possible differences between episodic and chronic migraine.

METHODS

Twenty-seven migraine right-handed patients and 27 healthy controls were selected for the study. Sixteen patients fulfilled the International Headache Society criteria for episodic migraine and 11 for chronic migraine. MRI scans were analyzed with MATLAB 6.5 and SPM2 software, using VBM method.

RESULTS

In comparison with controls, migraineurs presented a significant focal gray matter reduction in the Right Superior Temporal Gyrus, Right Inferior Frontal Gyrus, and Left Precentral Gyrus. Chronic migraine patients, compared to episodic, showed a focal gray matter decrease in the bilateral Anterior Cingulate Cortex, Left Amygdala, Left Parietal Operculum, Left Middle and Inferior Frontal Gyrus, Right Inferior Frontal Gyrus, and bilateral Insula. Considering all the migraine patients, a significant correlation between gray matter reduction in anterior cingulate cortex and frequency of migraine attacks was found.

CONCLUSIONS

Our study shows that migraine is associated with a significant gray matter reduction in several of the cortical areas involved in pain circuitry. In addition, we found a significant correlation between frequency of migraine attacks and signal alteration in the Anterior Cingulate Cortex. Our data provide new insight into migraine pathophysiology and support the concept that migraine may be a progressive disorder.

Multimodal investigation of fMRI and fNIRS derived breath hold BOLD signals with an expanded balloon model

Multimodal investigation of blood oxygenation level-dependent (BOLD) signals, using both functional near-infrared spectroscopy (fNIRS) and functional magnetic resonance imaging (fMRI), may give further insight to the underlying physiological principles and the detailed transient dynamics of the vascular response. Utilizing a breath hold task (BHT), we measured deoxy-hemoglobin (HbR) and oxy-hemoglobin (HbO) changes via fNIRS and blood oxygen level dependent (BOLD) changes by fMRI. Measurements were taken in four volunteers asynchronously and carefully aligned for comparative analysis. In order to describe the main stimulus in BHT, partial pressure of carbon dioxide (PaCO(2)) parameter was integrated into the balloon model as the driving function of cerebral blood flow (CBF) which led to the development of an expanded balloon model (EBM). During BHT, the increase in HbR was observed later than the BOLD peak and coincided temporally with its post-stimulus undershoot. Further investigation of these transients with a PaCO(2) integrated balloon model suggests that post-stimulus undershoot measured by fMRI is dominated by slow return of cerebral blood volume (CBV). This was confirmed by fNIRS measurements. In addition, the BOLD signal decreased with the increase of the initial level of PaCO(2) derived from EBM, indicating an effect of basal CBF level on the BOLD signal. In conclusion, a multimodal approach with an appropriate biophysical model gave a comprehensive description of the hemodynamic response during BHT.