Délia Szok

White matter microstructural alterations in migraine: A diffusion-weighted MRI study

Summary White matter disintegration, as measured by diffusion‐weighted MRI, is reported in migraineurs, and is speculated to be either a marker of possible white matter disintegration or maladaptive plasticity. Abstract Migraine is a common and disabling neurological disease. The pathomechanism that underlies the disorder is not entirely understood, and reliable biomarkers are missing. In the current analysis we looked for microstructural alterations of the brain white matter in migraine patients by means of diffusion‐weighted magnetic resonance imaging. The measurements were carried out with a novel approach based on fine‐tuned nonlinear registration and nonparametric permutation test in an alignment‐invariant tract representation (Tract‐Based Spatial Statistics). We found reduced fractional anisotropy in the right frontal white matter cluster of migraine patients. In the same region we also found increased mean diffusivity and increased radial diffusivity. The probabilistic tractography showed connection of this cluster to other parts of the pain network (orbitofrontal cortex, insula, thalamus, dorsal midbrain). We speculate that these findings reflect maladaptive plastic changes or white matter disintegration.

In depth pharmacological characterization of endothelin B receptors in the rat middle cerebral artery.

Whereas the endothelin A receptor is generally believed to mediate vasoconstriction; the endothelin B receptor seems elusive; both dilative and constrictive responses have been reported. Using the in vitro arteriograph, a method allowing compartmentalized study of vessel segments, segments of rat middle cerebral artery were cannulated with micropipettes, pressurized and luminally perfused. Vessel diameters were evaluated using a microscope equipped with an imaging system. Both intra- and extraluminal applications of endothelin-1 produced constriction. Intraluminal administration of a selective endothelin B receptor agonist sarafotoxin 6c in precontracted cerebral arteries and in the presence of the endothelin A receptor blocker FR139317 caused vasodilation in a concentration-dependent manner. Inhibition of nitric oxide synthase significantly reduced the dilation induced by sarafotoxin 6c, whereas inhibition of cyclooxygenase and endothelium-derived hyperpolarizing factor did not.

Prophylactic Drug Treatment of Migraine in Children and Adolescents: An Update

Migraine as a highly disabling pain condition influences the daily activities of those affected, including children and adolescents. The pathomechanism of migraine is not fully understood, and the different types of prophylactic antimigraine drugs that are applied are not specific for migraine. There is a need for preventive treatment in the event of frequent migraine attacks, an impairment of the quality of life, severe accompanying or aura symptoms, and the failure of acute drug treatment. The following pharmacological classes are recommended: antidepressants, antiepileptics, antihistamines, beta-adrenergic receptor blockers, and calcium ion channel antagonists, besides onabotulinum toxin A and nutraceuticals (butterbur). The most urgent goal as concerns pharmaceutical innovation is the development of pathomechanism-based antimigraine drugs and personalized therapy tailored to the children and adolescents.

Migraine and neuropeptides

Migraine is a common disabling neurovascular primary headache disorder. The pathomechanism is not clear, but extensive preclinical and clinical studies are ongoing. The structural basis of the leading hypothesis is the trigeminovascular system, which includes the trigeminal ganglion, the meningeal vasculature, and the distinct nuclei of the brainstem, the thalamus and the somatosensory cortex. This review covers the effects of sensory (calcitonin gene-related peptide, pituitary adenylate cyclase-activating polypeptide and substance P), sympathetic (neuropeptide Y) and parasympathetic (vasoactive intestinal peptide) migraine-related neuropeptides and the functions of somatostatin, nociceptin and the orexins in the trigeminovascular system. These neuropeptides may take part in neurogenic inflammation (plasma protein extravasation and vasodilatation) of the intracranial vasculature and peripheral and central sensitization of the trigeminal system. The results of human clinical studies are discussed with regard to the alterations in these neuropeptides in the plasma, saliva and cerebrospinal fluid during or between migraine attacks, and the therapeutic possibilities involving migraine-related neuropeptides in the acute and prophylactic treatment of migraine headache are surveyed.

CGRP and adrenomedullin receptor populations in human cerebral arteries: in vitro pharmacological and molecular investigations in different artery sizes

The aim of the present study was to determine functional and molecular characteristics of receptors for calcitonin gene-related peptide (CGRP) and adrenomedullin in three different diameter groups of lenticulostriate arteries. Furthermore, the presence of perivascular neuronal sources of CGRP was evaluated in these arteries. In the functional studies, in vitro pharmacological experiments demonstrated that both CGRP and adrenomedullin induce alpha-CGRP-(8-37) sensitive vasodilation in artery segments of various diameters. The maximal amounts of vasodilation induced by CGRP and adrenomedullin were not different, whereas the potency of CGRP exceeded that of adrenomedullin by 2 orders of magnitude. Significant negative correlations between artery diameters and maximal responses were demonstrated for CGRP and adrenomedullin. In addition, the potency of both peptides tended to increase in decreasing artery diameter. In the molecular experiments, levels of mRNAs encoding CGRP receptors and receptor subunits were compared using reverse transcriptase polymerase chain reactions (RT-PCR). The larger the artery, the more mRNA encoding receptor activity-modifying proteins 1 and 2 (RAMP1 and RAMP2) was detected relative to the amount of mRNA encoding the calcitonin receptor-like receptor. By immunohistochemistry, perivascular CGRP containing nerve fibres were demonstrated in all the investigated artery sizes. In conclusion, both CGRP and adrenomedullin induced vasodilation via CGRP receptors in human lenticulostriate artery of various diameter. The artery responsiveness to the CGRP receptor agonists increased with smaller artery diameter, whereas the receptor-phenotype determining mRNA ratios tended to decrease. No evidence for CGRP and adrenomedullin receptor heterogeneity was present in lenticulostriate arteries of different diameters.

Expression of ET A and ET B receptor mRNA in human cerebral arteries

The vascular effects of endothelins (ET) are in mammals mediated via two receptor subtypes, endothelin A (ET A, mainly constrictive) and endothelin B (ET B, mainly dilating) receptors. We have examined the presence of ET A and ET B receptor mRNA using the reverse transcription polymerase chain reaction (RT-PCR) in both normal human cerebral arteries and cerebral arteries from patients with cerebrovascular disease. Two vessel preparations were studied: macroscopic arteries and microvessels, the latter obtained through a sensitive separation method. In endothelial cells both ET A and ET B receptor mRNA was detected. In almost all samples from normal cerebral arteries only ET A receptor mRNA was detected, whereas in vessel samples from patients with cerebrovascular disease as well as cerebral neoplasms, additional ET B receptor mRNA was detected significantly more frequently. The pathophysiological significance of this difference is at present speculative, but does point to a vascular involvement of this receptor in cerebrovascular disease.

Release of PACAP-38 in episodic cluster headache patients - an exploratory study

BackgroundActivation of the trigeminal-autonomic reflex, involving the trigeminal ganglion, the superior salivatory nucleus and the sphenopalatine ganglion (SPG) is crucial in the pathophysiology of cluster headache (CH). Since pituitary adenylate cyclase-activating polypeptide-38 (PACAP-38) is present both in the SPG and the trigeminal ganglion (TG) and its role in migraine has been described, our aim was to determine the plasma PACAP-38 levels in different phases of episodic CH (ECH).Peripheral cubital fossa blood samples were taken during the ictal and inter-bout periods of male ECH patients and from age-matched healthy controls (n = 9). Plasma PACAP-38-like immunoreactivity (LI) was measured with specific and sensitive radioimmunoassay.FindingsSignificantly lower plasma PACAP-38-LI was detected in the inter-bout period of ECH patients than in healthy controls. However, PACAP-38 was significantly elevated in the plasma during CH attacks as compared to the inter-bout phase in the same subjects (n = 5).ConclusionsThis exploratory study suggests that PACAP-38 may be released during the attacks of ECH. Further patients and long-term follow-up are necessary to reveal its function.

Where does a migraine attack originate? In the brainstem

Migraine is a common, paroxysmal, highly disabling primary headache disorder. The origin of migraine attacks is enigmatic. Numerous clinical and experimental results suggest that the activation of distinct brainstem nuclei is crucial in its pathogenesis, but the primary cause of this activation is not fully understood. We conclude that the initialization of a migraine attack can be explained as an altered function of the neuronal elements of the brainstem nuclei. In light of our findings and the literature data, we can assume that migraine is a subcortical disorder of a specific brainstem area.

Drug safety and tolerability in prophylactic migraine treatment

Introduction: Migraine is a frequent, disabling primary headache disorder, whose pathomechanism is not yet fully understood. Prophylactic treatment is advisable for migraineurs with severe or highly frequent attacks, which impair the quality of life. Areas covered: The different types of prophylactic migraine drugs are discussed, with particular regard to potential adverse effects and safety issues. β-Adrenergic blockers, antiepileptic drugs and calcium-channel blockers are drugs widely used for migraine prevention, whereas complementary medicine and onabotulinumtoxin A can be used in selected cases. Expert opinion: The background of the recurrence and chronification of migraine attacks has not been fully clarified, and causative preventive therapy is therefore not currently available. The tolerability and adverse effects of the currently used medications often limit their use. β-Adrenergic receptor blockers may induce adverse cardiovascular events, whereas flunarizine is frequently associated with a weight gain and depression. As most migraine sufferers are young women of child-bearing age, the use of valproate is limited. Topiramate is associated with central nervous system-related side effects. There is a need for future development of pathomechanism-based preventive drugs, and personalized therapy tailored to the patient.

White matter disintegration in cluster headache.

BackgroundPrevious studies in primary headache disorders showed microstructural alterations in the white matter as measured by diffusion imaging. However these investigations are not in full agreement and some of those, especially in cluster headache, restricted the analysis to only a limited number of diffusion parameters. Therefore, in the current study we examined white matter microstructure in cluster headache patients.MethodsDiffusion weighted MRI images with 60 directions were acquired from thirteen patients with cluster headache and sixteen age-matched healthy controls. Tract based spatial statistics were used to compare white matter integrity in the core of the fibre bundles. Correlation of the diffusion parameters with cumulative number of headache days was examined.ResultsThere was a significant increment of the mean, axial and perpendicular diffusivity in widespread white matter regions in the frontal, parietal, temporal and occipital lobes. Reduced fractional anisotropy was found in the corpus callosum and some frontal and parietal white matter tracts mainly in the contralateral side of the pain. Axial diffusivity showed negative correlation to the number of the headache attacks.ConclusionsThe in vivo analysis of microstructural alterations in cluster headache provides important features of the disease, which might offer a deeper insight into the pathomechanism of the disease.