Perfusion-weighted imaging defects during spontaneous migrainous aura

Mapping the migraine: Intracranial recording of cortical spreading depression in migraine with aura

Migraine with aura is a common neurological disorder. Cortical spreading depression is the hypothetical pathophysiologic correlate, but it has never been directly recorded during migraine in a human. A 32-year-old female with a history of migraine underwent a presurgical workup for comorbid epilepsy. While implanted for stereotactic electroencephalography with 94 electrode contacts across bilateral hemispheres, she experienced a typical migraine with aura. Stereotactic electroencephalography demonstrated low-voltage suppression starting in the left mesial occipital cortex and propagating anteriorly at 3 mm/min, clinically correlating with a contralateral right superior scintillating scotoma and ipsilateral headache. Intracranial stereotactic electroencephalographic recording demonstrated cortical spreading depression during migraine with aura. Our findings add to the body of evidence implicating cortical spreading depression in the pathophysiology of migraine with aura.

Migraine and Stroke: A Scoping Review

An increased risk of ischemic stroke in migraine with aura (MA) has been consistently demonstrated. The pathophysiology of risk factors is not yet well understood. Several mechanisms have been proposed to explain the association between MA and ischemic stroke including decreased focal cerebral blood flow and other phenomena linked with cortical spreading depression (CSD) as well as neurovascular pathology, which appear to play a key role in MA. In addition to genetic predisposition, other classic stroke risk factors such as atrial fibrillation, emboli, migraine-associated vasculopathy, endothelial dysfunction, platelet dysfunction, coagulation pathway abnormalities, and inflammatory factors have been examined and investigated. For further clarification, distinctions have been made between features of migrainous infarctions and non-migrainous infarctions among migraineurs. Furthermore, the association is less clear when considering the mixed results studying the risk of ischemic stroke in migraines without aura (MO) and the risk of hemorrhagic stroke in people with all types of migraine. Translational research is investigating the role of biomarkers which can help identify vascular links between stroke and migraine and lead to further treatment developments. We performed a scoping review of the PubMed database to further characterize and update the clinical connections between migraine and stroke.

Cortical spreading depolarization-induced constriction of penetrating arteries can cause watershed ischemia: A potential mechanism for white matter lesions

Periventricular white matter lesions (WMLs) are common MRI findings in migraine with aura (MA). Although hemodynamic disadvantages of vascular supply to this region create vulnerability, the pathophysiological mechanisms causing WMLs are unclear. We hypothesize that prolonged oligemia, a consequence of cortical spreading depolarization (CSD) underlying migraine aura, may lead to ischemia/hypoxia at hemodynamically vulnerable watershed zones fed by long penetrating arteries (PAs). For this, we subjected mice to KCl-triggered single or multiple CSDs. We found that post-CSD oligemia was significantly deeper at medial compared to lateral cortical areas, which induced ischemic/hypoxic changes at watershed areas between the MCA/ACA, PCA/anterior choroidal and at the tip of superficial and deep PAs, as detected by histological and MRI examination of brains 2-4 weeks after CSD. BALB-C mice, in which MCA occlusion causes large infarcts due to deficient collaterals, exhibited more profound CSD-induced oligemia and were more vulnerable compared to Swiss mice such that a single CSD was sufficient to induce ischemic lesions at the tip of PAs. In conclusion, CSD-induced prolonged oligemia has potential to cause ischemic/hypoxic injury at hemodynamically vulnerable brain areas, which may be one of the mechanisms underlying WMLs located at the tip of medullary arteries seen in MA patients.

Migraine Aura-Catch Me If You Can with EEG and MRI-A Narrative Review

Roughly one-third of migraine patients suffer from migraine with aura, characterized by transient focal neurological symptoms or signs such as visual disturbance, sensory abnormalities, speech problems, or paresis in association with the headache attack. Migraine with aura is associated with an increased risk for stroke, epilepsy, and with anxiety disorder. Diagnosis of migraine with aura sometimes requires exclusion of secondary causes if neurological deficits present for the first time or are atypical. It was the aim of this review to summarize EEG an MRI findings during migraine aura in the context of pathophysiological concepts. This is a narrative review based on a systematic literature search. During visual auras, EEG showed no consistent abnormalities related to aura, although transient focal slowing in occipital regions has been observed in quantitative studies. In contrast, in familial hemiplegic migraine (FHM) and migraine with brain stem aura, significant EEG abnormalities have been described consistently, including slowing over the affected hemisphere or bilaterally or suppression of EEG activity. Epileptiform potentials in FHM are most likely attributable to associated epilepsy. The initial perfusion change during migraine aura is probably a short lasting hyperperfusion. Subsequently, perfusion MRI has consistently demonstrated cerebral hypoperfusion usually not restricted to one vascular territory, sometimes associated with vasoconstriction of peripheral arteries, particularly in pediatric patients, and rebound hyperperfusion in later phases. An emerging potential MRI signature of migraine aura is the appearance of dilated veins in susceptibility-weighted imaging, which may point towards the cortical regions related to aura symptoms ("index vein"). Conclusions: Cortical spreading depression (CSD) cannot be directly visualized but there are probable consequences thereof that can be captured Non-invasive detection of CSD is probably very challenging in migraine. Future perspectives will be elaborated based on the studies summarized.

Occipital transcranial direct current stimulation in episodic migraine patients: effect on cerebral perfusion

Cerebral blood flow differs between migraine patients and healthy controls during attack and the interictal period. This study compares the brain perfusion of episodic migraine patients and healthy controls and investigates the influence of anodal transcranial direct current stimulation (tDCS) over the occipital cortex. We included healthy adult controls and episodic migraineurs. After a 28-day baseline period and the baseline visit, migraine patients received daily active or sham anodal tDCS over the occipital lobe for 28 days. All participants underwent a MRI scan at baseline; migraineurs were also scanned shortly after the stimulation period and about five months later. At baseline, brain perfusion of migraine patients and controls differed in several areas; among the stimulated areas, perfusion was increased in the cuneus of healthy controls. At the first visit, the active tDCS group had an increased blood flow in regions processing visual stimuli and a decreased perfusion in other areas. Perfusion did not differ at the second follow-up visit. The lower perfusion level in migraineurs in the cuneus indicates a lower preactivation level. Anodal tDCS over the occipital cortex increases perfusion of several areas shortly after the stimulation period, but not 5 months later. An increase in the cortical preactivation level could mediate the transient reduction of the migraine frequency.Trial registration: NCT03237754 (registered at clincicaltrials.gov; full date of first trial registration: 03/08/2017).

Regional cerebral perfusion during the premonitory phase of triggered migraine: A double-blind randomized placebo-controlled functional imaging study using pseudo-continuous arterial spin labeling

OBJECTIVE

To identify changes in regional cerebral blood flow (CBF) associated with premonitory symptoms (PS) of nitroglycerin (NTG)-triggered migraine attacks.

BACKGROUND

PS could provide insights into attack initiation and alterations in neuronal function prior to headache onset.

METHODS

We undertook a functional imaging study using a double-blind placebo-controlled randomized approach in patients with migraine who spontaneously experienced PS, and in whom PS and migraine-like headache could be induced by administration of NTG. All study visits took place in a dedicated clinical research facility housing a monitoring area with clinical beds next to a 3Tesla magnetic resonance imaging scanner. Fifty-three patients with migraine were enrolled; imaging on at least one triggered visit was obtained from 25 patients, with 21 patients completing the entire imaging protocol including a placebo visit. Whole brain CBF maps were acquired using 3D pseudo-continuous arterial spin labeling (3D pCASL).

RESULTS

The primary outcome was that patients with migraine not taking preventive treatment (n = 12) displayed significant increases in CBF in anterior cingulate cortex, caudate, midbrain, lentiform, amygdala and hippocampus (p < 0.05 family-wise error-corrected) during NTG-induced PS. A separate region of interest analysis revealed significant CBF increases in the region of the hypothalamus (p = 0.006, effect size 0.77). Post hoc analyses revealed significant reductions in CBF over the occipital cortices in participants with a history of migraine with underlying aura (n = 14).

CONCLUSIONS

We identified significant regional CBF changes associated with NTG-induced PS, consistent with other investigations and with novel findings, withstanding statistical comparison against placebo. These findings were not present in patients who continually took preventive medication. Additional findings were identified only in participants who experience migraine with aura. Understanding this biological and treatment-related heterogeneity is vital to evaluating functional imaging outcomes in migraine research.

Symptoms and patterns of symptom propagation in incipient ischemic stroke and migraine aura

Background and objectives

Taking a detailed history of symptoms is important for differentiating incipient ischemic stroke and migraine aura. The aim of our study is to describe in detail symptom type and temporal pattern of symptom evolution (i.e., symptom succession and the time lapse between symptoms) and to identify differentiating clinical features in patients with ischemic stroke and migraine with aura.

Methods

Consecutive patients with ischemic stroke and migraine with aura were interviewed using a structured questionnaire. Stroke diagnosis was confirmed by imaging and migraine with aura was diagnosed according to the current criteria of the International Headache Society. Wake-up strokes and patients with severe cognitive deficits were excluded.

Results

In stroke patients and migraine patients, respectively, 50/78 (64%) vs. 123/326 (37%) had one, 18 (23%) vs. 127 (38%) had two, 5 (6%) vs. 69 (21%) had three, 2 (2%) vs. 4 (1%) had four, and 3 (3%) vs. 3 (1%) had five visual symptoms. In respect of sensory symptoms, 76/145 (52.4%) vs. 116/175 (66%) reported paresthesia and 92/145 (63.4%) vs. 132 (75%) numbness. Looking at the beginning, visual symptoms were the first symptom more often in migraine aura than in ischemic stroke (72.1 vs 18.8%, P < 0.001; PPV 86.8%). Sensory (29 vs 13.9%, P = 0.001; PPV 54.8%) and motor symptoms (20.5 vs 1.4%, P < 0.001; PPV 88.9%) were the first symptom more frequently in ischemic stroke. Of patients with consecutive symptoms, 39 of 201 (19%) compared to 34 of 117 (29%) (P = 0.02; PPV 46.6%) reported at least two simultaneous symptoms. A time lapse between symptoms of < 1 min (18.6 vs 6.3%, P < 0.001; PPV 57.1%) and > 360 min (15.8 vs 0%, χ² = 39.61, P < 0.001; PPV 100%) was more frequent in stroke whereas a time lapse between 5 and 60 min was more frequent in migraine aura (41.1 vs 68.7%, χ² = 23.52, P < 0.001; PPV 78.7%).

Conclusion

There is a significant overlap in the clinical presentation of stroke and migraine aura. In particular, a substantial proportion of patients in one group had symptoms that are traditionally attributed to the other group. This study highlights the similarities and differences between symptoms of ischemic stroke and migraine aura and challenges our reasoning in daily clinical practice.

Pathophysiology of migraine aura

Migraine aura occurs in about a third of patients with migraine and consists of a group of transient focal neurological symptoms that appear from 5 to 60min and then resolve prior to or in the early phase of a migraine headache attack. Migraine auras may consist of visual, language, unilateral sensory, or motor symptoms. There has been considerable debate as to the origins of the migrainous aura. Investigations during physiologically induced visual auras suggest that the phenomenon of cortical spreading depression or its human equivalent underpins the migraine aura. Single gene defects have been linked to relatively rare forms of the motor subtypes of aura known as familial hemiplegic migraine (FHM). These include CACNA1A (FHM1), ATP1A2 (FHM2), and SCN1A (FHM3). In the familial hemiplegic forms of migraine, the more typical forms of aura are almost always also present. Despite ample epidemiological evidence of increased heritability of migraine with aura compared to migraine without aura, identification of the specific variants driving susceptibility to the more common forms of aura has been problematic thus far. In the first genome-wide association study (GWAS) that focused migraine with aura, a single SNP rs835740 reached genome-wide significance. Unfortunately, the SNP did show statistical significance in a later meta-analysis which included GWAS data from subsequent studies. Here, we review the clinical features, pathophysiological theories, and currently available potential evidence for the genetic basis of migraine aura.

Calcitonin gene related peptide in migraine: current therapeutics, future implications and potential off-target effects

Migraine is the second largest cause of years lost to disability globally among all diseases, with a worldwide prevalence over 1 billion. Despite the global burden of migraine, few classes of therapeutics have been specifically developed to combat migraine. After 30 years of translational research, calcitonin gene-related peptide (CGRP) inhibitors have emerged as a promising new tool in the prevention of migraine. Like all new therapeutics; however, we have limited real-world experience and CGRP has several known systemic actions that warrant consideration. This article provides a narrative review of the evidence for CGRP antagonists and summarises the known and potential side effects that should be considered.

Parenchymal neuroinflammatory signaling and dural neurogenic inflammation in migraine

Background

Pain is generally concomitant with an inflammatory reaction at the site where the nociceptive fibers are activated. Rodent studies suggest that a sterile meningeal inflammatory signaling cascade may play a role in migraine headache as well. Experimental studies also suggest that a parenchymal inflammatory signaling cascade may report the non-homeostatic conditions in brain to the meninges to induce headache. However, how these signaling mechanisms function in patients is unclear and debated. Our aim is to discuss the role of inflammatory signaling in migraine pathophysiology in light of recent developments.

Body

Rodent studies suggest that a sterile meningeal inflammatory reaction can be initiated by release of peptides from active trigeminocervical C-fibers and stimulation of resident macrophages and dendritic/mast cells. This inflammatory reaction might be needed for sustained stimulation and sensitization of meningeal nociceptors after initial activation along with ganglionic and central mechanisms. Most migraines likely have cerebral origin as suggested by prodromal neurologic symptoms. Based on rodent studies, a parenchymal inflammatory signaling cascade has been proposed as a potential mechanism linking cortical spreading depolarization (CSD) to meningeal nociception. A recent PET/MRI study using a sensitive inflammation marker showed the presence of meningeal inflammatory activity in migraine with aura patients over the occipital cortex generating the visual aura. These studies also suggest the presence of a parenchymal inflammatory activity, supporting the experimental findings. In rodents, parenchymal inflammatory signaling has also been shown to be activated by migraine triggers such as sleep deprivation without requiring a CSD because of the resultant transcriptional changes, predisposing to inadequate synaptic energy supply during intense excitatory transmission. Thus, it may be hypothesized that neuronal stress created by either CSD or synaptic activity-energy mismatch could both initiate a parenchymal inflammatory signaling cascade, propagating to the meninges, where it is converted to a lasting headache with or without aura.

Conclusion

Experimental studies in animals and emerging imaging findings from patients warrant further research to gain deeper insight to the complex role of inflammatory signaling in headache generation in migraine.

OnabotulinumtoxinA affects cortical recovery period but not occurrence or propagation of cortical spreading depression in rats with compromised blood-brain barrier

ABSTRACT

OnabotulinumtoxinA (BoNT-A) is an Food and Drug Administration-approved, peripherally acting preventive migraine drug capable of inhibiting meningeal nociceptors. Expanding our view of how else this neurotoxin attenuates the activation of the meningeal nociceptors, we reasoned that if the stimulus that triggers the activation of the nociceptor is lessened, the magnitude and/or duration of the nociceptors' activation could diminish as well. In the current study, we further examine this possibility using electrocorticogram recording techniques, immunohistochemistry, and 2-photon microscopy. We report (1) that scalp (head) but not lumbar (back) injections of BoNT-A shorten the period of profound depression of spontaneous cortical activity that follows a pinprick-induced cortical spreading depression (CSD); (2) that neither scalp nor lumbar injections prevent the induction, occurrence, propagation, or spreading velocity of a single wave of CSD; (3) that cleaved SNAP25-one of the most convincing tools to determine the anatomical targeting of BoNT-A treatment-could easily be detected in pericranial muscles at the injection sites and in nerve fibers of the intracranial dura, but not within any cortical area affected by the CSD; (4) that the absence of cleaved SNAP25 within the cortex and pia is unrelated to whether the blood-brain barrier is intact or compromised; and (5) that BoNT-A does not alter vascular responses to CSD. To the best of our knowledge, this is the first report of peripherally applied BoNT-A's ability to alter a neuronal function along a central nervous system pathway involved in the pathophysiology of migraine.

Migraine pharmacology and brain ischemia

Introduction: The aim of this review article was to analyze in details the mechanism of drugs’ effects in the treatment and prevention of a migraine attack, as well as to discuss the hypotheses of migraine pathogenesis.

Migraine attack treatment agents: The main agents for migraine attack treatment have an anti-nociceptive activity.

Agents for migraine preventive treatment: β-blocker propranolol also has anti-serotonin and analgesic activities, and most drugs used for the prophylactic treatment of migraine have a vasodilating activity.

Vascular hypothesis of migraine pathogenesis: Despite numerous studies that have expanded our understanding of migraine pathogenesis, the importance of the vascular component in the pathogenesis of this disease has not questioned yet.

Neurogenic hypotheses of cortical spreading depression: It is necessary to take into account the points of this hypothesis in the context of the pathophysiology of migraine.

Neurochemical serotonin hypotheses of migraine pathogenesis: Serotonin plays an important role in the pathogenesis of migraine.

Trigemino-vascular hypotheses of migraine pathogenesis: The trigemino-vascular hypothesis claims to solve the problem of migraine pain.

Migraine and ischemic brain damage: Migraine is a risk factor for ischemic stroke and cognitive disorders.

Search for the new anti-ischemic anti-migraine preparations: A methodology for the search for new anti-ischemic anti-serotonin drugs for the treatment of migraine is proposed.

Conclusion: Belonging of a drug to one or another pharmacological group does not always correspond to its therapeutic effect on the pathogenetic processes of migraine. Migraine with its variety of forms cannot fit only one of the proposed hypotheses on the pathogenesis of this disease.

Graphical abstract:

Current perspectives on neuroimaging techniques used to identify stroke mimics in clinical practice

INTRODUCTION

Urgent clinical assessment and brain imaging are essential for differentiating stroke mimics from stroke and to avoid unnecessary initiation of reperfusion and other therapies in stroke mimic patients.

AREAS COVERED

In this article, the authors will review acute stroke imaging and then the imaging patterns of the most common stroke mimics. The authors have focused our review on brain CT scan, and more specifically CT perfusion, as this is the most commonly available and emerging tool in emergency settings. The authors also provide information on acute brain MRI and MR perfusion.

EXPERT OPINION

Imaging can contribute to the detection and diagnosis of acute stroke mimics. Knowledge of imaging findings in different stroke mimics can help distinguish these from patients with stroke who require timely reperfusion therapy. CT and MRI perfusion and diffusion-weighted imaging (DWI) MRI are useful imaging modalities for the assessment of acute stroke patients as they provide more accurate information than plain CT scan. Some of these modalities should be available in the emergency setting. The authors recommended CT perfusion as a useful tool for stroke management and differentiation with stroke mimics.

Recurrent vestibulopathy: are cVEMP, oVEMP and inner ear MRI useful to distinguish patients with Menière's disease and vestibular migraine?

PURPOSE

The aim of this study was to assess the rate of endolymphatic hydrops (EH) on MRI and the rate of otolithic dysfunction with cVEMP and oVEMP, in patients with recurrent vertigo such as Menière's disease (MD), vestibular migraine (VM) and vestibular Menière's disease (vMD).

METHODS

In this retrospective study, we performed 3D-FLAIR sequences with delayed acquisition in 20 MD, 20 VM and 20 vMD patients. Each subject was then assessed for the presence of EH on MRI. All patients underwent pure-tone audiometry, cVEMP and oVEMP.

RESULTS

In MD patients, EH was observed in 18 (90%) out of 20 patients while EH was observed in only 1 MV (5%) and 1 vMD (5%) patients. We found significant differences between groups for the presence of EH on MRI (p = 0.001). MD patients had significant higher PTA level (p < 0.001) and oVEMP impairment than MV and vMD (p = 0.08 and p = 0.06, respectively). However, no significant differences were observed for cVEMP impairment, either asymmetric ratio (p = 0.36) and 1000/500 ratio (p = 0.20).

CONCLUSIONS

Concerning cVEMP, we observed no significant differences between VM, vMD and MD. However, we observed higher oVEMP impairment, PTA level and EH on MRI in MD patients. We believe that MRI could be used to differentiate MD from VM patients with cochlear symptoms. However, in cases of migraine associated with recurrent vertigo and without cochlear symptoms, we believe that MRI is not a useful tool to differentiate between VM and vMD.

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.

Findings in susceptibility weighted imaging in pediatric patients with migraine with aura

BACKGROUND

Migraine with aura (MwA) in pediatric patients is clinically frequent. Clinically complex symptoms need to be differentiated to exclude mimicking conditions.

PURPOSE

We hypothesize that MwA in children induces abnormalities readily visible in perfusion time to peak (TTP) maps as well as non-enhanced susceptibility weighted magnetic resonance imaging (SWI).

MATERIALS AND METHODS

Between 2010 and 2018, we retrospectively evaluated symptoms and imaging of consecutive pediatric patients <18 years with MwA. We visually scored abnormalities on SWI and TTP maps in 12 regions of interest on both hemispheres on three axial slices, as normal, slightly, distinctly or severely abnormal.

RESULTS

99 patients (69.7% female), mean age 14.07 y (±2.8) were included. Focally increased deoxygenation (FID) in SWI was present in 61.6%. FID on SWI was dominant for the left hemisphere (60.7% vs. 31.1%, (p < .001)), and in 8.2% symmetric. Side of aura symptoms and contralateral hemispheric imaging alterations in patients with FID correlated significantly (p = .002.). 61 of 99 patients had perfusion MR and 59% of these patients showed focal increase of TTP. Age correlated significantly with FID in SWI (r = -.248, p = .013) and increase of TTP in perfusion (r = -.252, p = .05). Focal abnormalities correlated significantly between SWI and TTP maps. Brain regions most often abnormal were the temporal superior, occipital and fronto-parietal regions.

CONCLUSIONS

This study provides confidence in recognizing FID, and linking FID in SWI to acute MwA in pediatric patients. FID phenomenon had a left hemispheric significant dominance, and can be found bilaterally.

May lamotrigine be an alternative to topiramate in the prevention of migraine with aura? Results of a retrospective study

Background

Evidence suggests that lamotrigine could be effective in reducing aura frequency and duration. However, studies comparing lamotrigine to other, first-line prophylactic agents solely involving patients suffering from migraine with aura are still lacking. The aim of this study was to compare the efficacy of lamotrigine and topiramate for the preventive treatment of migraine with aura.

Methods

Fifty-three patients suffering from migraine with aura treated with lamotrigine or topiramate for at least 6 months were included. Pre- and post-treatment clinical data regarding monthly aura frequency and duration, monthly migraine frequency, days of headache and rescue medication used per month were collected.

Results

Responder rates were similar between the two treatment groups at 6-month follow-up. Interestingly, responder rates for aura frequency and duration were higher in the lamotrigine group compared with the topiramate group (88% vs 79% and 73% vs 54%). Moreover, 50% of the lamotrigine-treated patients reported a complete disappearance of migraine aura compared with 37% of topiramate-treated patients. Side effects were more frequent in topiramate group compared with lamotrigine group (p=0.004).

Conclusions

Lamotrigine should be considered in clinical practice for the preventive treatment of migraine with aura especially for patients reporting prolonged aura and who do not respond, have contraindications or discontinue topiramate treatment due to side effects.

An Update: Pathophysiology of Migraine

Migraine is the most common disabling primary headache globally. Attacks typically present with unilateral throbbing headache and associated symptoms including, nausea, multisensory hypersensitivity, and marked fatigue. In this article, the authors address the underlying neuroanatomical basis for migraine-related headache, associated symptomatology, and discuss key clinical and preclinical findings that indicate that migraine likely results from dysfunctional homeostatic mechanisms. Whereby, abnormal central nervous system responses to extrinsic and intrinsic cues may lead to increased attack susceptibility.

Fremanezumab and its isotype slow propagation rate and shorten cortical recovery period but do not prevent occurrence of cortical spreading depression in rats with compromised blood-brain barrier

Most centrally acting migraine preventive drugs suppress frequency and velocity of cortical spreading depression (CSD). The purpose of the current study was to determine how the new class of peripherally acting migraine preventive drug (ie, the anti-CGRP-mAbs) affect CSD-an established animal model of migraine aura, which affects about 1/3 of people with migraine-when allowed to cross the blood-brain barrier (BBB). Using standard electrocorticogram recording techniques and rats in which the BBB was intentionally compromised, we found that when the BBB was opened, the anti-CGRP-mAb fremanezumab did not prevent the induction, occurrence, or propagation of a single wave of CSD induced by a pinprick, but that both fremanezumab and its isotype were capable of slowing down the propagation velocity of CSD and shortening the period of profound depression of spontaneous cortical activity that followed the spreading depolarization. Fremanezumab's inability to completely block the occurrence of CSD in animals in which the BBB was compromised suggests that calcitonin gene-related peptide (CGRP) may not be involved in the initiation of CSD, at least not to the extent that it can prevent its occurrence. Similarly, we cannot conclude that CGRP is involved in the propagation velocity or the neuronal silencing period (also called cortical recovery period) that follows the CSD because similar effects were observed when the isotype was used. These finding call for caution with interpretations of studies that claim to show direct central nervous system effects of CGRP-mAbs.

[Recent advances in the elucidation of migraine pathophysiology]

Three hypotheses have been proposed so far regarding the pathophysiology of migraine: one is the "vascular theory", which posits cerebral vascular dysfunction as the etiological factor. The second is the "neuronal theory", which suggests that migraine is triggered by cortical spreading depression. The third is the "trigemino-vascular theory", which postulates that migraine is triggered by inflammation of trigeminal nerves and vessels around trigeminal ganglion cells. Nowadays, the "trigemino-vascular theory" is widely accepted. However, recent advances in imaging analysis indicate that the origin of migraine lies in a premonitory phase which precedes the aura phase. Modern imaging techniques such as functional MRI and PET reveal high activity of the hypothalamic area during the premonitory phase of migraine. These findings suggest that hypothalamic activation might be a generator of a migraine attack. On the other hand, current analyses show that the photosensitivity of migraine (photophobia) could be caused by dysfunction of the newly discovered intrinsically photosensitive retinal ganglion cells (ipRGCs). In the absence of visual signaling from rods and cones, light activation of ipRGCs expressing melanopsin photopigment is sufficient to produce photophobia during migraine. The ipRGCs project to the hypothalamus; their activation might be the trigger for migraine attacks. Significant advances in molecular biology and imaging in recent years have clarified the previous hypotheses of migraine pathophysiology.

Aura and Head pain: relationship and gaps in the translational models

Migraine is a complex brain disorder and initiating events for acute attacks still remain unclear. It seems difficult to explain the development of migraine headache with one mechanism and/or a single anatomical location. Cortical spreading depression (CSD) is recognized as the biological substrate of migraine aura and experimental animal studies have provided mechanisms that possibly link CSD to the activation of trigeminal neurons mediating lateralized head pain. However, some CSD features do not match the clinical features of migraine headache and there are gaps in translating CSD to migraine with aura. Clinical features of migraine headache and results from research are critically evaluated; and consistent and inconsistent findings are discussed according to the known basic features of canonical CSD: typical SD limited to the cerebral cortex as it was originally defined. Alternatively, arguments related to the emergence of SD in other brain structures in addition to the cerebral cortex or CSD initiated dysfunction in the thalamocortical network are proposed. Accordingly, including thalamus, particularly reticular nucleus and higher order thalamic nuclei, which functions as a hub connecting the visual, somatosensory, language and motor cortical areas and subjects to modulation by brain stem projections into the CSD theory, would greatly improve our current understanding of migraine.

Computed tomography perfusion in stroke mimics

OBJECTIVE

To describe the prevalence and patterns of abnormal findings on automated computed tomography perfusion in patients with stroke mimic.

METHODS

We reviewed a retrospective multi-site cohort of consecutive patients undergoing computed tomography perfusion for suspected acute ischemic stroke within 24 h from last normal (June 2017 to December 2017). The primary outcome was the diagnosis of stroke mimic. Hypoperfusion abnormalities on iSchemaView RAPID automated computed tomography perfusion were compared between patients with stroke/transient ischemic attack and stroke mimic using mixed-effects multivariable logistic regression, focusing on absence of perfusion abnormalities and discordance with clinical symptoms and computed tomography angiography findings.

RESULTS

Of 410 consecutive patients who underwent computed tomography perfusion, 348 met inclusion criteria (178 (51%) stroke, 19 (6%) transient ischemic attack, and 151 (43%) mimic). Time-to-maximum of the tissue residue function (T_max>6s) abnormalities were seen in 42 (28%) patients with stroke mimic and 122 (62%) patients with stroke/transient ischemic attack (p < 0.001). Patients with stroke mimic were more likely to have a normal T_max pattern (volume = 0mL; adjusted OR: 2.2, 95% CI: 1.1-4.3, p = 0.02). When the T_max pattern was abnormal, a higher proportion of patients with stroke mimic had T_max patterns fully discordant with clinical symptoms than patients with stroke/transient ischemic attack (28/39 (71%) vs. 10/115 (9%), p < 0.001). Fully discordant T_max abnormalities were strongly associated with stroke mimic (adjusted OR: 48.6, 95% CI: 7.0-336, p < 0.001), with a negative predictive value for identifying mimic of 91% (95% CI: 85-94%).

CONCLUSION

While one-quarter of patients with stroke mimic show T_max abnormalities on automated RAPID computed tomography perfusion imaging, the majority of patterns were discordant with symptoms and vessel status. Normal or fully discordant T_max abnormalities are were more common with stroke mimic and may inform stroke treatment decision making.

Getting to the Heart of the Matter: Migraine, Triptans, DHE, Ditans, CGRP Antibodies, First/Second-Generation Gepants, and Cardiovascular Risk

PREMISE

The science of migraine pathophysiology has advanced significantly since the 1930's. Imaging techniques, neurochemical analysis, clinical trials, and the clinical experience of providers treating migraine patients have not only sharpened our understanding of the disease, but have also led to the development of novel neural-based targets. Targeted therapies such as calcitonin gene-related peptide (CGRP) antibodies and "Second Generation" CGRP receptor antagonists (Gepants) have not only demonstrated efficacy, but have not resulted in any significant cardiovascular nor other serious adverse events. "First Generation" Gepants were associated with liver toxicity.

PROBLEM

Triptans and dihydroergotamine (DHE) are contraindicated in patients with hemiplegic and basilar migraine based on theories of migraine pathophysiology from the 1930s. While our understanding of migraine has evolved substantially, perceived concerns of safety from almost a century ago continue to preclude their use in certain patient populations.

POTENTIAL SOLUTION

While migraine aura was once thought to be primarily due to vasoconstriction, current evidence debunks this concept. For instance, hemiplegic migraine is the consequence of genetic mutations resulting in channelopathies without evidence of cerebral ischemia or infarction. Evidence of basilar artery constriction as postulated in basilar migraine is also lacking. This recognition has led the International Headache Society to rename basilar-type migraine to migraine with brainstem aura. The following discussion reviews current literature with respect to migraine as a neuronal disorder, as well as the published data on the safety of triptans, DHE, Ditans (a novel class of 5-HT_1f receptor agonists), CGRP antibodies, and Gepants.

Shedding light on migraine with aura: the clarifying role of advanced neuroimaging investigations

Introduction: While migraine with aura is a complex neurological syndrome with a well-characterized clinical phenotype, its pathophysiology still has grey areas which could be partially clarified by microstructural and functional neuroimaging investigations. Areas covered: This article, summarizing the most significant findings from advanced neuroimaging studies, aims to achieve a unifying pathophysiological model of the migraine aura. A comprehensive review has been conducted of PubMed citations by entering the key word 'neuroimaging' combined with 'migraine with aura' AND/OR 'MRI.' Other keywords included 'grey matter' OR 'white matter', 'structural' OR 'functional'. Expert opinion: Converging evidence from advanced neuroimaging investigations underlined the critical role of the extrastriate visual cortex, and in particular the lingual gyrus, in the genesis of the aura phenomenon. However, the relationship between the aura and the headache phase of migraine attacks has not been completely clarified, to date, and underlying pathophysiological mechanisms need to be further elucidated.

Application of amplitude of low‑frequency fluctuation to altered spontaneous neuronal activity in classical trigeminal neuralgia patients: A resting‑state functional MRI study

Recent studies have reported structural and functional abnormalities in multiple brain regions of classical trigeminal neuralgia (CTN) patients. Differences in spontaneous neuronal activity between CTN patients and healthy subjects, however, remain unknown. The aim of the present study was to investigate alterations in brain activity by application of amplitude of low frequency fluctuation (ALFF), thus analyzing the correlation between durations of spontaneous pain intensity and ALFF values in CTN patients. A total of 28 CTN patients (male, n=12; female, n=16) and 28 healthy controls (HCs; male, n=12; female, n=16) matched for age and sex were enrolled. All subjects underwent resting‑state functional magnetic resonance imaging and changes in spontaneous brain activity were investigated using an ALFF method. Receiver operating characteristic (ROC) curve analysis was applied to differentiate ALFF values of CTN patients from HCs. Altered ALFF values and clinical manifestations were evaluated using Pearson's correlation analysis. ALFF values of the bilateral inferior cerebellum, bilateral fusiform gyrus, right precentral gyrus, left inferior temporal gyrus, right superior cerebellum, left inferior occipital gyrus and right superior occipital gyrus were significantly higher in CTN patients when compared to HCs. ROC curve analysis of each brain revealed a near‑perfect AUC accuracy. Pearson's correlation analysis revealed the visual analog scale of the right eye to be positively correlated with both left inferior temporal and occipital gyral findings, while episode duration likewise was positively associated with left inferior temporal gyral findings. CTN patients exhibited abnormal spontaneous activity in multiple brain regions closely related to pain regulation and perception, while VAS and CTN episode duration were positively correlated with ALFF signal values in some brain regions. The present findings provide further insight into the pathological mechanisms underlying CTN.

Abnormalities of interhemispheric functional connectivity in individuals with acute eye pain: a resting-state fMRI study

AIM

To study the changes of the resting state functional connectivity (rsFC) between acute eye pain (EP) subjects and healthy controls (HCs) in the two hemispheres by using voxel-mirrored homotopic connectivity (VMHC) method.

METHODS

Totally 20 patients with EP and 20 HCs were enrolled, sex, age, and education were matched, and all subjects were examined by functional magnetic resonance imaging (fMRI) scans at resting-state. The changes of rsFC between the hemispheres were evaluated by the VMHC method according to Gaussian random field (GRF) theory. In order to identify the VMHC, as biomarkers for distinguishing EP and from HC, the receiver operating characteristic curves (ROC) had been analyzed. The relationships were evaluated with Pearson correlation analysis between the mean VMHC signal values and clinical features in these patients.

RESULTS

By comparing with health subjects, the significant decreased VMHC values was observed in lingual/calcarine (Brodmann area, BA 30), precentral/postcentral gyrus (PreCG/PosCG; BA 4) and medial frontal gyrus (MFG; BA 8) (false discovery rate corrected <0.01) in the acute EP individuals. The accuracy of area under curve was excellent indicated by the ROC curve analysis of each brain regions.

CONCLUSION

Our study demonstrates preliminary evidence of disrupted interhemispheric rsFC in acute EP in sensorimotor and limbic system and somatosensory cortex, which might give some useful information for understanding the neurological mechanisms in acute EP individuals.

Cerebral hemodynamics in the different phases of migraine and cluster headache

Headache is one of the most common ailments; migraine is one of the most prevalent and disabling neurological disorders and cluster headache presents as one of the most excruciating pain disorders. Both are complex disorder characterized by recurrent episodes of headache. A key feature is that various triggers can set off an attack providing the opportunity to explore disease mechanisms by experimentally inducing attacks. This review summarizes neuroimaging and hemodynamic studies in human in provoked and spontaneous attacks of migraine and cluster headache. Cerebral hemodynamics during different phases of the migraine attack demonstrate alterations in cerebral blood flow and perfusion, vessel caliber, cortical and sub-cortical function, underscoring that migraine pathophysiology is highly complex. Migraine attacks might begin in diencephalic and brainstem areas, whereas migraine aura is a cortical phenomenon. In cluster headache pathophysiology, the hypothalamus might also play a pivotal role, whereas the pattern of cerebral blood flood differs from migraine. For both disorders, alterations of arterial blood vessel diameter might be more an epiphenomenon of the attack than a causative trigger. Studying cerebral hemodynamics in provocation models are important in the search for specific biomarkers in the hope to discover future targets for more specific and effective mechanism-based anti-headache treatment.

Altered intrinsic brain activity in patients with toothaches using the amplitude of low-frequency fluctuations: a resting-state fMRI study

BACKGROUND

The results of previous studies have indicated that pain-associated diseases can result in marked functional and anatomical alterations in the brain. However, differences in spontaneous brain activity occurring in toothache (TA) patients remain unclear.

OBJECTIVE

This study investigated intrinsic brain activity changes in TA subjects using the amplitude of low-frequency fluctuation (ALFF) technique.

METHODS

A total of 18 patients with TA (eight males, and 10 females) and 18 healthy controls (HCs) who were matched for gender, age, and educational status were enrolled. Resting-state functional MRI was used to examine the participants. Spontaneous cerebral activity variations were investigated using the ALFF technique. The mean ALFF values of the TA patients and the HCs were classified using receiver operating characteristic (ROC) curves. The correlations between ALFF signals of distinct regions of the cerebrum and the clinical manifestations of the TA patients were evaluated using Pearson's correlation analysis.

RESULTS

Compared with HCs, TA patients showed notably higher ALFF in the left postcentral gyrus, right paracentral lobule, right lingual gyrus, right inferior occipital gyrus, left fusiform gyrus, and right superior occipital gyrus. ROC curve analysis of each brain region showed that the accuracy area under the curve was excellent. In the TA group, the visual analog scale of the left side was positively correlated with the ALFF signal values of the right paracentral lobule (r=0.639, P=0.025).

CONCLUSION

Multiple brain regions, including pain- and vision-related areas, exhibited aberrant intrinsic brain activity patterns, which may help to explain the underlying neural mechanisms in TA.

Episodic Migraine With and Without Aura: Key Differences and Implications for Pathophysiology, Management, and Assessing Risks

PURPOSE OF REVIEW

To review the pathophysiologic, epidemiologic, and clinical evidence for similarities and differences between migraine with and without aura.

RECENT FINDINGS

The ICHD-3 has recently refined the diagnostic criteria for aura to include positive symptomatology, which better differentiates aura from TIA. Although substantial evidence supports cortical spreading depression as the cause of visual aura, the role (if any) of CSD in headache pain is not well understood. Recent imaging evidence suggests a possible hypothalamic origin for a headache attack, but further research is needed. Migraine with aura is associated with a modest increase in the risk of ischemic stroke. The etiology for this association remains unclear. There is a paucity of evidence regarding treatments specifically aimed at the migraine with aura subtype, or whether migraine with vs without aura responds to treatment differently. Migraine with typical aura is therefore often treated similarly to migraine without aura. Lamotrigine, daily aspirin, and flunarizine have evidence for efficacy in prevention of migraine with aura, and magnesium, ketamine, furosemide, and single-pulse transcranial magnetic stimulation have evidence for use as acute treatments. Although triptans have traditionally been contraindicated in hemiplegic migraine and migraine with brainstem aura, this prohibition is being reconsidered in the face of evidence suggesting that use may be safe. The debate as to whether migraine with and without aura are different entities is ongoing. In an era of sophisticated imaging, genetic advancement, and ongoing clinical trials, efforts to answer this question are likely to yield important and clinically meaningful results.

Systematic review of the pharmacological agents that have been tested against spreading depolarizations

Spreading depolarization (SD) occurs alongside brain injuries and it can lead to neuronal damage. Therefore, pharmacological modulation of SD can constitute a therapeutic approach to reduce its detrimental effects and to improve the clinical outcome of patients. The major objective of this article was to produce a systematic review of all the drugs that have been tested against SD. Of the substances that have been examined, most have been shown to modulate certain SD characteristics. Only a few have succeeded in significantly inhibiting SD. We present a variety of strategies that have been proposed to overcome the notorious harmfulness and pharmacoresistance of SD. Information on clinically used anesthetic, sedative, hypnotic agents, anti-migraine drugs, anticonvulsants and various other substances have been compiled and reviewed with respect to the efficacy against SD, in order to answer the question of whether a drug at safe doses could be of therapeutic use against SD in humans.

PhD AM, Burstein R. Activation of pial and dural macrophages and dendritic cells by cortical spreading depression

OBJECTIVE

Cortical spreading depression (CSD) has long been implicated in migraine attacks with aura. The process by which CSD, a cortical event that occurs within the blood-brain barrier (BBB), results in nociceptor activation outside the BBB is likely mediated by multiple molecules and cells. The objective of this study was to determine whether CSD activates immune cells inside the BBB (pia), outside the BBB (dura), or in both, and if so, when.

METHODS

Investigating cellular events in the meninges shortly after CSD, we used in vivo two-photon imaging to identify changes in macrophages and dendritic cells (DCs) that reside in the pia, arachnoid, and dura and their anatomical relationship to TRPV1 axons.

RESULTS

We found that activated meningeal macrophages retract their processes and become circular, and that activated meningeal DCs stop migrating. We found that CSD activates pial macrophages instantaneously, pial, subarachnoid, and dural DCs 6-12 minutes later, and dural macrophages 20 minutes later. Dural macrophages and DCs can appear in close proximity to TRPV1-positive axons.

INTERPRETATION

The findings suggest that activation of pial macrophages may be more relevant to cases where aura and migraine begin simultaneously, that activation of dural macrophages may be more relevant to cases where headache begins 20 to 30 minutes after aura, and that activation of dural macrophages may be mediated by activation of migratory DCs in the subarachnoid space and dura. The anatomical relationship between TRPV1-positive meningeal nociceptors, and dural macrophages and DCs supports a role for these immune cells in the modulation of head pain. Ann Neurol 2018;83:508-521.

Arterial Spin Labeling Cerebral Perfusion Magnetic Resonance Imaging in Migraine Aura: An Observational Study

BACKGROUND

Changes in cerebral perfusion during migraine with aura (MA) have been assessed mainly using dynamic susceptibility contrast (DSC) magnetic resonance perfusion imaging. A contrast agent-free method to assess these changes would be desirable. We assessed changes in cerebral perfusion during MA using arterial spin labeling (ASL) perfusion magnetic resonance imaging.

METHODS

We investigated 4 patients with a standardized protocol including ASL perfusion imaging during MA (n = 2) or early headache phase (n = 2) and asymptomatic follow-up. Semiquantitative evaluation was done using a region of interest (ROI) within hypoperfused or hyperperfused areas and corresponding ROIs in the contralateral hemisphere. Relative ratios of mean perfusion in the corresponding ROIs were calculated. DSC imaging was done at initial time points and compared visually with ASL findings.

RESULTS

In all patients, regional perfusion changes were detected in the acute phase. These abnormalities did not respect the boundaries of major cerebral vascular territories but overlapped onto adjoining regions. During MA, adjacent hypoperfused and hyperperfused areas were found, whereas during headache, regional hyperperfusion only was observed. Perfusion abnormalities normalized on follow-up.

CONCLUSIONS

ASL perfusion imaging is a contrast agent-free method suitable for assessment of reversible perfusion changes during or immediately after MA.

Stroke-like migraine attacks after radiation therapy: A misnomer?

OBJECTIVE

To understand the frequency of electrographic and clinical seizures in patients with stroke-like migraine attacks after radiation therapy (SMART), and determine whether SMART warrants comprehensive electroencephalographic (EEG) monitoring and aggressive seizure management.

METHODS

We searched our magnetic resonance brain imaging report database for all patients between January 2013 and December 2015 for suspected SMART syndrome. Clinical inclusion criteria were further applied as follows: inpatient adults (>18 years of age) with history of cranial radiation presenting with acute neurologic deficits as primary admission reason who lacked evidence of recurrent or new brain malignancy, stroke, or infectious agents in cerebrospinal fluid. Six patients were identified. All 6 patients underwent prolonged video EEG monitoring as part of our standard protocol.

RESULTS

All patients but 1 were found to have multiple or prolonged electrographic seizures consistent with status epilepticus during video EEG monitoring. Their neurological deficit and/or mental status change improved in parallel with resolution of the seizure activity.

SIGNIFICANCE

SMART is likely a misnomer that underestimates the significance of seizures and status epilepticus in the pathophysiology and clinical presentation of the syndrome. Systematic continuous EEG monitoring and appropriate seizure management is warranted to reduce symptom duration and optimize clinical outcome.

The efficacy of transcranial magnetic stimulation on migraine: a meta-analysis of randomized controlled trails

OBJECTIVES

As a non-invasive therapy, whether transcranial magnetic stimulation (TMS) is effective on migraine. This article was aimed to assess the efficacy of TMS on migraine based on randomized controlled trails (RCTs).

METHODS

We searched PubMed, Embase and Cochrane Library electronic databases for published studies which compared TMS group with sham group, conducted a meta-analysis of all RCTs.

RESULTS

Five studies, consisting of 313 migraine patients, were identified. Single-pulse transcranial magnetic stimulation is effective for the acute treatment of migraine with aura after the first attack (p = 0.02). And, the efficacy of TMS on chronic migraine was not significant (OR 2.93; 95% CI 0.71-12.15; p = 0.14).

CONCLUSIONS

TMS is effective for migraine based on the studies included in the article.

Region-specific disruption of the blood-brain barrier following repeated inflammatory dural stimulation in a rat model of chronic trigeminal allodynia

Background The blood-brain barrier (BBB) has been hypothesized to play a role in migraine since the late 1970s. Despite this, limited investigation of the BBB in migraine has been conducted. We used the inflammatory soup rat model of trigeminal allodynia, which closely mimics chronic migraine, to determine the impact of repeated dural inflammatory stimulation on BBB permeability. Methods The sodium fluorescein BBB permeability assay was used in multiple brain regions (trigeminal nucleus caudalis (TNC), periaqueductal grey, frontal cortex, sub-cortex, and cortex directly below the area of dural activation) during the episodic and chronic stages of repeated inflammatory dural stimulation. Glial activation was assessed in the TNC via GFAP and OX42 immunoreactivity. Minocycline was tested for its ability to prevent BBB disruption and trigeminal sensitivity. Results No astrocyte or microglial activation was found during the episodic stage, but BBB permeability and trigeminal sensitivity were increased. Astrocyte and microglial activation, BBB permeability, and trigeminal sensitivity were increased during the chronic stage. These changes were only found in the TNC. Minocycline treatment prevented BBB permeability modulation and trigeminal sensitivity during the episodic and chronic stages. Discussion Modulation of BBB permeability occurs centrally within the TNC following repeated dural inflammatory stimulation and may play a role in migraine.

Pathophysiology of Migraine: A Disorder of Sensory Processing

Plaguing humans for more than two millennia, manifest on every continent studied, and with more than one billion patients having an attack in any year, migraine stands as the sixth most common cause of disability on the planet. The pathophysiology of migraine has emerged from a historical consideration of the "humors" through mid-20th century distraction of the now defunct Vascular Theory to a clear place as a neurological disorder. It could be said there are three questions: why, how, and when? Why: migraine is largely accepted to be an inherited tendency for the brain to lose control of its inputs. How: the now classical trigeminal durovascular afferent pathway has been explored in laboratory and clinic; interrogated with immunohistochemistry to functional brain imaging to offer a roadmap of the attack. When: migraine attacks emerge due to a disorder of brain sensory processing that itself likely cycles, influenced by genetics and the environment. In the first, premonitory, phase that precedes headache, brain stem and diencephalic systems modulating afferent signals, light-photophobia or sound-phonophobia, begin to dysfunction and eventually to evolve to the pain phase and with time the resolution or postdromal phase. Understanding the biology of migraine through careful bench-based research has led to major classes of therapeutics being identified: triptans, serotonin 5-HT1B/1D receptor agonists; gepants, calcitonin gene-related peptide (CGRP) receptor antagonists; ditans, 5-HT1F receptor agonists, CGRP mechanisms monoclonal antibodies; and glurants, mGlu5 modulators; with the promise of more to come. Investment in understanding migraine has been very successful and leaves us at a new dawn, able to transform its impact on a global scale, as well as understand fundamental aspects of human biology.

Cortical Spreading Depression in Migraine

Cortical spreading depression (CSD) is associated with a dramatic failure of brain ion homeostasis as well as efflux of excitatory amino acids from nerve cells and increased energy metabolism. There is strong clinical and experimental evidence to suggest that CSD is involved in the mechanism of migraine. This paper will, based on the experience related to the detection of CSD in humans, discuss pitfalls and possible strategies for detection of CSD in man. Development of reliable methods for detection of CSD in humans will determine the extent to which the large body of experimental findings from animal studies of CSD can be applied to the investigation and treatment of human brain disease. The paper is based on the experience that has been gained from two decades of studies of CSD in relation to clinical neurological diseases.

Enhanced Interictal Responsiveness of the Migraineous Visual Cortex to Incongruent Bar Stimulation: A Functional MRI Visual Activation Study

Since visual aura is usually described as expanding zigzag lines, neurones involved with the perception of line orientation may initiate this phenomenon. A visual incongruent line stimulation protocol was developed to obtain functional magnetic resonance images (fMRI) interictally in 5 female migraine patients with typical fortification spectra and in 5 normal matched controls. Activation in the visual cortex was present contralateral to the side of stimulation in 4 of 5 patients, notably in the extrastriate visual cortex. In 4 of 5 controls activation was observed in the medial and anterior orbitofrontal cortex. In one of them additional activation at the right nucleus accumbens/ventral striatum and right ventral pallidum was present. In the remaining control subject activation was present in the left primary visual cortex. The enhanced interictal reactivity of the visual cortex in migraineurs supports the hypothesis of abnormal cortical excitability as an important pathophysiological mechanism in migraine aura, though the role of specific regions of the visual cortex remains to be explored.

Familial Hemiplegic Migraine: Follow-up Findings of Diffusion-Weighted Magnetic Resonance Imaging (MRI), Perfusion-MRI and [99mTc] HMPAO-SPECT in a Patient with Prolonged Hemiplegic Aura

Familial hemiplegic migraine (FHM) is a rare inherited autosomal dominant disorder. Migraine aura may last up to several weeks and then resolve without sequel. We report a 21-year-old male with FHM since the age of 3 years. Diffusion-weighted magnetic resonance imaging (DWI), perfusion-MR imaging (P-MRI) and [99mTc] hexamethyl-propyleneamine-oxime-single photon emission tomography (HMPAO-SPECT) were performed on day 2, when he was somnolent with right-sided hemiplegia, on day 9 when a mild hemiparesis was still present and on day 24 after recovery. The right central region showed normal findings in DWI, whereas P-MRI and SPECT revealed hyperperfusion on day 2, less marked on day 9, and normal findings on day 24. In conclusion, this case report indicates for the first time, by means of SPECT, P-MRI and DWI studies, that even extremely long-lasting migraine aura is not associated with cerebral ischaemia. Therefore, it supports the revised International Headache Society criteria where the term ‘persistent’ aura is proposed.

Evaluation and Proposal for Optimization of Neurophysiological Tests In Migraine: Part 2—Neuroimaging and The Nitroglycerin Test

Neuroimaging methods have been widely used in headache and migraine research. They have provided invaluable information on brain perfusion, metabolism and structure during and outside of migraine attacks, contributing to an improved understanding of the pathophysiology of the disorder. Human models of migraine attacks are indispensable tools in pathophysiological and therapeutic research. This review of neuroimaging methods and the attack-provoking nitroglycerin test is part an initiative by a task force within the EUROHEAD project (EU Strep LSHM-CT-2004-5044837-Workpackage 9) with the objective of critically evaluating neurophysiological tests used in migraine. The first part, presented in a companion paper, is devoted to electrophysiological methods, this second part to neuroimaging methods such as functional magnetic resonance imaging, positron emission tomography and voxel-based morphometry, as well as the nitroglycerin test. For each of these methods, we summarize the results, analyse the methodological limitations and propose recommendations for improved methodology and standardization of research protocols.

Diffusion- and Perfusion-Weighted MR Imaging in Persistent Migrainous visual Disturbances

Pathological changes on diffusion-weighted MR scans had been described in hemiplegic migraine and perfusion changes had been demonstrated in typical migraine aura with radio-isotope studies and, more recently, MR perfusion imaging. However, there is relatively little knowledge of the pathophysiology of long-lasting migraine aura and its possibly variant phenotype, visual snow. Our aim was to investigate with advanced MR techniques whether patients with long-lasting visual disturbance showed regional alterations in cerebral water diffusion and perfusion. We have studied four patients using MR perfusion and MR diffusion imaging. Two patients had typical visual aura and two had a primary persistent visual disturbance (visual snow phenomenon). All patients had normal conventional structural MR imaging. MR diffusion-weighted images were acquired with a b-value of up to 1000 s/mm2. From the diffusion weighted images we generated maps of apparent diffusion coefficient (ADC), which were inspected visually and used for ADC measurements of predefined regions of interest, which included the visual, frontal, insular and temporal cortices. MR perfusion imaging was performed using a bolus tracking technique with dynamic susceptibility-weighted images. Colour coded maps of relative cerebral blood volume, mean transit time and bolus arrival time were generated, as well as time-signal intensity curves over the anterior, middle and posterior cerebral artery territories. The maps of the ADC and above perfusion parameters appeared symmetrical in all patients with no evidence of decreased water diffusion or cerebral perfusion in the occipital regions, or elsewhere. There was no statistically significant difference between the ADC measurements of the primary visual cortices and other cortical regions. Our findings suggest that regional changes in cerebral water diffusion and perfusion do not play an important part in the pathophysiology of persistent migraine aura or primary persistent visual disturbance.