Variable clinical expression of mutations in the P/Q-type calcium channel gene in familial hemiplegic migraine. Dutch Migraine Genetics Research Group

Unravelling the Genetic Landscape of Hemiplegic Migraine: Exploring Innovative Strategies and Emerging Approaches

Migraine is a severe, debilitating neurovascular disorder. Hemiplegic migraine (HM) is a rare and debilitating neurological condition with a strong genetic basis. Sequencing technologies have improved the diagnosis and our understanding of the molecular pathophysiology of HM. Linkage analysis and sequencing studies in HM families have identified pathogenic variants in ion channels and related genes, including CACNA1A, ATP1A2, and SCN1A, that cause HM. However, approximately 75% of HM patients are negative for these mutations, indicating there are other genes involved in disease causation. In this review, we explored our current understanding of the genetics of HM. The evidence presented herein summarises the current knowledge of the genetics of HM, which can be expanded further to explain the remaining heritability of this debilitating condition. Innovative bioinformatics and computational strategies to cover the entire genetic spectrum of HM are also discussed in this review.

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

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

The Electrophysiological Findings in Spinocerebellar Ataxia Type 6: Evidence From 24 Patients

PURPOSE

Peripheral neuropathy has been reported commonly in several spinocerebellar ataxia (SCA) types. To date, there is a lack of robust evidence for neuropathy or neuronopathy in SCA type 6 (SCA6). Here, we aim to evaluate the presence of neuropathy or neuronopathy in a cohort of SCA6 patients.

METHODS

Twenty-four individuals with genetically confirmed SCA6 underwent detailed neurophysiological assessment. This included nerve conduction studies, and in some, cutaneous silent periods, blink reflexes, tilt table tests, quantitative sudomotor axon reflex tests, and somatosensory (median and tibial) evoked potentials.

RESULTS

Mean age was 56.1 years (range, 22-94 years) at the time of testing. Four patients were presymptomatic of SCA6 at recruitment. The mean disease duration of symptomatic patients was 11.9 years (range, 1-40 years). Most patients (79.2%, 19/24) had no neurophysiological evidence of a peripheral neuropathy. One with impaired glucose tolerance had mild, large, and small fiber sensorimotor polyneuropathy. One elderly patient had length-dependent axonal sensorimotor polyneuropathy. Two had minor sensory abnormalities (one had type II diabetes and previous chemotherapy). One other had minor small fiber abnormalities. Ten patients (41.7%) had median neuropathies at the wrist. All somatosensory evoked potential (15/15), and most autonomic function tests (13/14) were normal.

CONCLUSIONS

A large proportion of subjects (79.2%) in our cohort had no evidence of large or small fiber neuropathy. This study does not support the presence of neuropathy or neuronopathy as a common finding in SCA6 and confirms the importance of considering comorbidities as the cause of neurophysiological abnormalities.

Involvement of the cerebellum in migraine

Migraine is a disabling neurological disease characterized by moderate or severe headaches and accompanied by sensory abnormalities, e.g., photophobia, allodynia, and vertigo. It affects approximately 15% of people worldwide. Despite advancements in current migraine therapeutics, mechanisms underlying migraine remain elusive. Within the central nervous system, studies have hinted that the cerebellum may play an important sensory integrative role in migraine. More specifically, the cerebellum has been proposed to modulate pain processing, and imaging studies have revealed cerebellar alterations in migraine patients. This review aims to summarize the clinical and preclinical studies that link the cerebellum to migraine. We will first discuss cerebellar roles in pain modulation, including cerebellar neuronal connections with pain-related brain regions. Next, we will review cerebellar symptoms and cerebellar imaging data in migraine patients. Lastly, we will highlight the possible roles of the neuropeptide calcitonin gene-related peptide (CGRP) in migraine symptoms, including preclinical cerebellar studies in animal models of migraine.

The de novo CACNA1A pathogenic variant Y1384C associated with hemiplegic migraine, early onset cerebellar atrophy and developmental delay leads to a loss of Cav2.1 channel function

CACNA1A pathogenic variants have been linked to several neurological disorders including familial hemiplegic migraine and cerebellar conditions. More recently, de novo variants have been associated with severe early onset developmental encephalopathies. CACNA1A is highly expressed in the central nervous system and encodes the pore-forming Ca_Vα₁ subunit of P/Q-type (Cav2.1) calcium channels. We have previously identified a patient with a de novo missense mutation in CACNA1A (p.Y1384C), characterized by hemiplegic migraine, cerebellar atrophy and developmental delay. The mutation is located at the transmembrane S5 segment of the third domain. Functional analysis in two predominant splice variants of the neuronal Cav2.1 channel showed a significant loss of function in current density and changes in gating properties. Moreover, Y1384 variants exhibit differential splice variant-specific effects on recovery from inactivation. Finally, structural analysis revealed structural damage caused by the tyrosine substitution and changes in electrostatic potentials.

Advances in genetics of migraine

Background

Migraine is a complex neurovascular disorder with a strong genetic component. There are rare monogenic forms of migraine, as well as more common polygenic forms; research into the genes involved in both types has provided insights into the many contributing genetic factors. This review summarises advances that have been made in the knowledge and understanding of the genes and genetic variations implicated in migraine etiology.

Findings

Migraine is characterised into two main types, migraine without aura (MO) and migraine with aura (MA). Hemiplegic migraine is a rare monogenic MA subtype caused by mutations in three main genes - CACNA1A, ATP1A2 and SCN1A - which encode ion channel and transport proteins. Functional studies in cellular and animal models show that, in general, mutations result in impaired glutamatergic neurotransmission and cortical hyperexcitability, which make the brain more susceptible to cortical spreading depression, a phenomenon thought to coincide with aura symptoms. Variants in other genes encoding ion channels and solute carriers, or with roles in regulating neurotransmitters at neuronal synapses, or in vascular function, can also cause monogenic migraine, hemiplegic migraine and related disorders with overlapping symptoms. Next-generation sequencing will accelerate the finding of new potentially causal variants and genes, with high-throughput bioinformatics analysis methods and functional analysis pipelines important in prioritising, confirming and understanding the mechanisms of disease-causing variants.

With respect to common migraine forms, large genome-wide association studies (GWAS) have greatly expanded our knowledge of the genes involved, emphasizing the role of both neuronal and vascular pathways. Dissecting the genetic architecture of migraine leads to greater understanding of what underpins relationships between subtypes and comorbid disorders, and may have utility in diagnosis or tailoring treatments. Further work is required to identify causal polymorphisms and the mechanism of their effect, and studies of gene expression and epigenetic factors will help bridge the genetics with migraine pathophysiology.

Conclusions

The complexity of migraine disorders is mirrored by their genetic complexity. A comprehensive knowledge of the genetic factors underpinning migraine will lead to improved understanding of molecular mechanisms and pathogenesis, to enable better diagnosis and treatments for migraine sufferers.

Autoimmune episodic ataxia in patients with anti-CASPR2 antibody-associated encephalitis

Objective:

To report paroxysmal episodes of cerebellar ataxia in a patient with anti–contactin-associated protein-like 2 (CASPR2) antibody-related autoimmune encephalitis and to search for similar paroxysmal ataxia in a cohort of patients with anti–CASPR2 antibody-associated autoimmune encephalitis.

Methods:

We report a patient with paroxysmal episodes of cerebellar ataxia observed during autoimmune encephalitis with anti-CASPR2 antibodies. In addition, clinical analysis was performed in a retrospective cohort of 37 patients with anti-CASPR2 antibodies to search for transient episodes of ataxia. Paroxysmal symptoms were further specified from the referral physicians, the patients, or their relatives.

Results:

A 61-year-old man with limbic encephalitis and anti-CASPR2 antibodies developed stereotyped paroxysmal episodes of cerebellar ataxia, including gait imbalance, dysarthria, and dysmetria, 1 month after the onset of the encephalitis. The ataxic episodes were specifically triggered by orthostatism and emotions. Both limbic symptoms and transient ataxic episodes resolved after treatment with steroids and IV cyclophosphamide. Among 37 other patients with anti-CASPR2 antibodies, we identified 5 additional cases with similar paroxysmal ataxic episodes that included gait imbalance (5 cases), slurred speech (3 cases), limb dysmetria (3 cases), and nystagmus (1 case). All had concomitant limbic encephalitis. Paroxysmal ataxia was not observed in patients with neuromyotonia or Morvan syndrome. Triggering factors (orthostatism or anger) were reported in 4 patients. Episodes resolved with immunomodulatory treatments in 4 patients and spontaneously in 1 case.

Conclusions:

Paroxysmal cerebellar ataxia must be added to the spectrum of the anti-CASPR2 antibody syndrome.

Sporadic Hemiplegic Migraine is an Aetiologically Heterogeneous Disorder

In order to better understand sporadic hemiplegic migraine (SHM) and particularly its relation to familial hemiplegic migraine (FHM), migraine without aura (MO) and typical migraine with aura (typical MA), we investigated the occurrence of MO and typical MA among probands with SHM and their first-degree relatives. The pattern of familial aggregation of MO and typical MA was assessed by population relative risk calculations. A total of 105 SHM probands and 483 first-degree relatives were identified in the Danish population. Compared with the general population, SHM probands had no increased risk of MO, but a highly increased risk of typical MA. First-degree relatives of all SHM probands had an increased risk of both MO and typical MA, whereas first-degree relatives of probands with exclusively SHM had no increased risk of MO but an increased risk of typical MA. Our data suggest that SHM is a genetically heterogeneous disorder.

Sporadic Hemiplegic Migraine

Sporadic hemiplegic migraine (SHM) is defined as migraine attacks associated with some degree of motor weakness/hemiparesis during the aura phase and where no first degree relative (parent, sibling or child) has identical attacks. The present review deals with recent scientific studies according to which: The SHM prevalence is estimated to be 0.005%; SHM patients have clinical symptoms identical to patients with familial hemiplegic migraine (FHM) and significantly different from patients with migraine with typical aura (typical MA); SHM affected had no increased risk of migraine without aura (MO), but a highly increased risk of typical MA compared to the general population; SHM patients only rarely have mutations in the FHM gene CACNA1A; SHM attacks in some cases can be treated with Verapamil. The reviewed data underlie the change in the International Classification of Headache Disorders 2nd edition where SHM became separated from migraine with typical aura or migraine with prolonged aura. All cases with motor weakness should be classified as either FHM or SHM.

A Single Amino Acid Deletion (ΔF1502) in the S6 Segment of CaV2.1 Domain III Associated with Congenital Ataxia Increases Channel Activity and Promotes Ca2+ Influx

Mutations in the CACNA1A gene, encoding the pore-forming Ca_V2.1 (P/Q-type) channel α_1A subunit, result in heterogeneous human neurological disorders, including familial and sporadic hemiplegic migraine along with episodic and progressive forms of ataxia. Hemiplegic Migraine (HM) mutations induce gain-of-channel function, mainly by shifting channel activation to lower voltages, whereas ataxia mutations mostly produce loss-of-channel function. However, some HM-linked gain-of-function mutations are also associated to congenital ataxia and/or cerebellar atrophy, including the deletion of a highly conserved phenylalanine located at the S6 pore region of α_1A domain III (ΔF1502). Functional studies of ΔF1502 Ca_V2.1 channels, expressed in Xenopus oocytes, using the non-physiological Ba²⁺ as the charge carrier have only revealed discrete alterations in channel function of unclear pathophysiological relevance. Here, we report a second case of congenital ataxia linked to the ΔF1502 α_1A mutation, detected by whole-exome sequencing, and analyze its functional consequences on Ca_V2.1 human channels heterologously expressed in mammalian tsA-201 HEK cells, using the physiological permeant ion Ca²⁺. ΔF1502 strongly decreases the voltage threshold for channel activation (by ~ 21 mV), allowing significantly higher Ca²⁺ current densities in a range of depolarized voltages with physiological relevance in neurons, even though maximal Ca²⁺ current density through ΔF1502 Ca_V2.1 channels is 60% lower than through wild-type channels. ΔF1502 accelerates activation kinetics and slows deactivation kinetics of Ca_V2.1 within a wide range of voltage depolarization. ΔF1502 also slowed Ca_V2.1 inactivation kinetic and shifted the inactivation curve to hyperpolarized potentials (by ~ 28 mV). ΔF1502 effects on Ca_V2.1 activation and deactivation properties seem to be of high physiological relevance. Thus, ΔF1502 strongly promotes Ca²⁺ influx in response to either single or trains of action potential-like waveforms of different durations. Our observations support a causative role of gain-of-function Ca_V2.1 mutations in congenital ataxia, a neurodevelopmental disorder at the severe-most end of CACNA1A-associated phenotypic spectrum.

Two novel SCN1A mutations identified in families with familial hemiplegic migraine

BACKGROUND

Familial hemiplegic migraine (FHM) is a rare monogenic subtype of migraine with aura, characterized by motor auras. The majority of FHM families have mutations in the CACNA1A and ATP1A2 genes; less than 5% of FHM families are explained by mutations in the SCN1A gene. Here we screened two Spanish FHM families for mutations in the FHM genes.

METHODS

We assessed the clinical features of both FHM families and performed direct sequencing of all coding exons (and adjacent sequences) of the CACNA1A, ATP1A2, PRRT2 and SCN1A genes.

RESULTS

FHM patients in both families had pure hemiplegic migraine with highly variable severity and frequency of attacks. We identified a novel SCN1A missense mutation p.Ile1498Met in all three tested hemiplegic migraine patients of one family. In the other family, novel SCN1A missense mutation p.Phe1661Leu was identified in six out of eight tested hemiplegic migraine patients. Both mutations affect amino acid residues that either reside in an important functional domain (in the case of Ile(1498)) or are known to be important for kinetic properties of the NaV1.1 channel (in the case of Phe(1661)).

CONCLUSIONS

We identified two mutations in families with FHM. SCN1A mutations are an infrequent but important cause of FHM. Genetic testing is indicated in families when no mutations are found in other FHM genes.

Functional neuroimaging of primary headache disorders

Until recently, primary headache disorders, such as migraine and cluster headache were considered to be vascular in origin. However, advances in neuroimaging techniques, such as positron emission tomography, single photon emission computed tomography and functional magnetic resonance imaging have augmented the growing clinical evidence that these headaches are primarily driven from the brain. This review covers functional imaging studies in migraine, cluster headache, rarer headache syndromes and experimental head pain. Together with newer techniques, such as voxel-based morphometry and magnetic resonance spectrometry, functional imaging continues to play a role in elucidating and targeting the neural substrates in each of the primary headache syndromes.

Analysis of chromosome 1 microsatellite markers and the FHM2-ATP1A2gene mutations in migraine pedigrees

OBJECTIVES

The aims of the study were: (i) to extend our linkage analysis of chromosome 1q microsatellite markers in predominantly migraine with aura pedigrees and (ii) to test the novel FHM-2 ATP1A2 gene for involvement in these migraine affected pedigrees and a previous pedigree (MF14) showing evidence of linkage of markers to C1q31.

METHODS

A chromosome 1 scan (31 markers) was performed in 21 multiplex pedigrees affected predominantly with migraine with aura (MA). The known FHM-2 ATP1A2 gene mutations were tested, by sequencing, for the involvement in MA and migraine without aura (MO) in these pedigrees. Sequencing was performed in the coding areas of the ATP1A2 gene through three MA individuals from MF14.

RESULTS

Evidence for linkage was obtained at C1q23 to markers spanning the ATP1A2 gene. However, testing of the known ATP1A2 gene mutations (for FHM) in common migraine probands of pedigrees showing excess allele sharing was negative. Sequencing of the entire coding areas of the gene through all the three MA affected from MF14 was also negative for mutations.

DISCUSSION

Microsatellite markers on chromosome 1q23 show evidence of excess allele sharing in MA and some MO pedigrees, suggesting linkage to the common forms of migraine and the presence of a susceptibility gene in this region. The FHM-2 (ATP1A2 gene) does not seem to be involved in the common types of migraine. Despite certain clinical characteristics, the genetic correlation between FHM and familial typical migraine remains unclear. Several candidate genes lie within the C1q23 and C1q31 cytogenetic regions; therefore, further studies are needed.

Comparison of the effects of DC031050, a class III antiarrhythmic agent, on hERG channel and three neuronal potassium channels

AIM

This study was conducted to test the selectivity of DC031050 on cardiac and neuronal potassium channels.

METHODS

Human ether-à-go-go related gene (hERG), KCNQ and Kv1.2 channels were expressed in CHO cells. The delayed rectifier potassium current (I(K)) was recorded from dissociated hippocampal pyramidal neurons of neonatal rats. Whole-cell voltage patch clamp was used to record the voltage-activated potassium currents. Drug-containing solution was delivered using a RSC-100 Rapid Solution Changer.

RESULTS

Both DC031050 and dofetilide potently inhibited hERG currents with IC(50) values of 2.3 ± 1.0 and 17.9 ± 1.2 nmol/L, respectively. DC031050 inhibited the I(K) current with an IC(50) value of 2.7 ± 1.5 μmol/L, which was >1000 times the concentration required to inhibit hERG current. DC031050 at 3 μmol/L did not significantly affect the voltage-dependence of the steady activation, steady inactivation of I(K), or the rate of I(K) from inactivation. Intracellular application of DC031050 (5 μmol/L) was insufficient to inhibit I(K). DC031050 up to 10 μmol/L had no effects on KCNQ2 and Kv1.2 channel currents.

CONCLUSION

DC031050 is a highly selective hERG potassium channel blocker with a substantial safety margin of activity over neuronal potassium channels, thus holds significant potential for therapeutic application as a class III antiarrhythmic agent.

Migraine mutations increase stroke vulnerability by facilitating ischemic depolarizations

BACKGROUND

Migraine is an independent risk factor for stroke. Mechanisms underlying this association are unclear. Familial hemiplegic migraine (FHM), a migraine subtype that also carries an increased stroke risk, is a useful model for common migraine phenotypes because of shared aura and headache features, trigger factors, and underlying glutamatergic mechanisms.

METHODS AND RESULTS

Here, we show that FHM type 1 (FHM1) mutations in Ca(V)2.1 voltage-gated Ca(2+) channels render the brain more vulnerable to ischemic stroke. Compared with wild-type mice, 2 FHM1 mutant mouse strains developed earlier onset of anoxic depolarization and more frequent peri-infarct depolarizations associated with rapid expansion of infarct core on diffusion-weighted magnetic resonance imaging and larger perfusion deficits on laser speckle flowmetry. Cerebral blood flow required for tissue survival was higher in the mutants, leading to infarction with milder ischemia. As a result, mutants developed larger infarcts and worse neurological outcomes after stroke, which were selectively attenuated by a glutamate receptor antagonist.

CONCLUSIONS

We propose that enhanced susceptibility to ischemic depolarizations akin to spreading depression predisposes migraineurs to infarction during mild ischemic events, thereby increasing the stroke risk.

Enhanced subcortical spreading depression in familial hemiplegic migraine type 1 mutant mice

Familial hemiplegic migraine type 1, a monogenic migraine variant with aura, is linked to gain-of-function mutations in the CACNA1A gene encoding Ca(V)2.1 channels. The S218L mutation causes severe channel dysfunction, and paroxysmal migraine attacks can be accompanied by seizures, coma, and hemiplegia; patients expressing the R192Q mutation exhibit hemiplegia only. Familial hemiplegic migraine knock-in mice expressing the S218L or R192Q mutation are highly susceptible to cortical spreading depression, the electrophysiological surrogate for migraine aura, and develop severe and prolonged motor deficits after spreading depression. The S218L mutants also develop coma and seizures and sometimes die. To investigate underlying mechanisms for these symptoms, we used multielectrode electrophysiological recordings, diffusion-weighted magnetic resonance imaging, and c-fos immunohistochemistry to trace spreading depression propagation into subcortical structures. We showed that unlike the wild type, cortical spreading depression readily propagated into subcortical structures in both familial hemiplegic migraine type 1 mutants. Whereas the facilitated subcortical spread appeared limited to the striatum in R192Q, hippocampal and thalamic spread was detected in the S218L mutants with an allele-dosage effect. Both strains exhibited increased susceptibility to subcortical spreading depression and reverberating spreading depression waves. Altogether, these data show that spreading depression propagates between cortex, basal ganglia, diencephalon, and hippocampus in genetically susceptible brains, which could explain the prolonged hemiplegia, coma, and seizure phenotype in this variant of migraine with aura.

Migraine is associated with an increased risk of deep white matter lesions, subclinical posterior circulation infarcts and brain iron accumulation: the population-based MRI CAMERA study

Previous studies have suggested that migraine is a risk factor for brain lesions, but methodological issues hampered drawing definite conclusions. Therefore, we initiated the magnetic resonance imaging (MRI) ‘CAMERA’ (Cerebral Abnormalities in Migraine, an Epidemiological Risk Analysis) study. We summarize our previously published results. A total of 295 migraineurs and 140 controls were randomly selected from a previously diagnosed population-based sample (n = 6039), who underwent an interview, physical examination and a brain MRI scan. Migraineurs, notably those with aura, had higher prevalence of subclinical infarcts in the posterior circulation [odds ratio (OR) 13.7; 95% confidence interval (CI) 1.7, 112]. Female migraineurs were at independent increased risk of white matter lesions (WMLs; OR 2.1; 95% CI 1.0, 4.1), and migraineurs had a higher prevalence of brainstem hyperintense lesions (4.4% vs. 0.7%, P = 0.04). We observed a higher lifetime prevalence of (frequent) syncope and orthostatic insufficiency in migraineurs; future research needs to clarify whether autonomic nervous system dysfunction could explain (part of) the increased risk of WMLs in female migraineurs. Finally, in migraineurs aged < 50 years, compared with controls, we found evidence of increased iron concentrations in putamen (P = 0.02), globus pallidus (P = 0.03) and red nucleus (P = 0.03). Higher risks in those with higher attack frequency or longer disease duration were found consistent with a causal relationship between migraine and lesions. This summary of our population-based data illustrates that migraine is associated with a significantly increased risk of brain lesions. Longitudinal studies are needed to assess whether these lesions are progressive and have relevant (long-term) functional correlates.

Dementia, stroke and migraine--some common pathological mechanisms

Dementia, stroke and migraine are very common neurological disorders affecting a large percentage of the population, and leading to a high degree of disability. Often, adequate therapy is not available. Although the symptoms, the progression and the outcome differ in these disorders, to some extent they may share some common pathophysiological mechanisms. The genetic background, an energy deficit, and excitotoxicity, vascular and thrombotic properties can influence all three disorders, resulting in a neuronal dysfunction, increased cellular vulnerability, neurodegeneration and ultimately cell death. All these cellular events occur in dementias and stroke, moreover recent studies suggest that, besides a dysfunction, neuronal damage may be an issue in migraine too. One of the most central events in the multiple mechanisms involved in the pathogenesis of these disorders is a metabolic disturbance of certain brain cells. As mitochondria provide the cells with energy, realization of the importance of these organelles in the aetiopathogenesis of several disorders has emerged in recent years. This review surveys the most important features of the pathogenesis of dementia, stroke and migraine from the aspect of mitochondrial malfunction highlighting some of the considerable connections between these neurological disorders.

A long-term follow-up study of 18 patients with sporadic hemiplegic migraine

Objective: Our objective was to study the long-term prognosis of sporadic hemiplegic migraine (SHM).

Methods: We performed a longitudinal follow-up study in 18 patients who were diagnosed with SHM between 1993 and 1996. Follow-up time between the first and second survey ranged from nine to 14 years. These patients were included as part of a genetic study in which we systematically analysed the role of the three known familial hemiplegic migraine (FHM) genes.

Results: In 12 out of 18 patients the clinical diagnosis was unchanged. In two of the six remaining patients the attacks were no longer associated with hemiplegia; one of them had an ATP1A2 gene mutation (E120A). In the four other patients, the diagnosis changed into FHM, because a family member had developed hemiplegic migraine since the initial diagnosis was made. In two of the four patients a mutation was demonstrated ( CACNA1A [R583Q] and ATP1A2 [R834X]).

Conclusion: This study shows that the diagnosis of SHM changes into FHM in a considerable percentage of patients (22% [4 of 18]), almost a decade after the initial diagnosis. This indicates that a careful follow-up of SHM patients and their families is advisable for optimal care and counseling. Diagnostic screening of FHM genes in SHM patients can be of value. Our genetic and clinical follow-up studies reinforce the evidence that FHM and SHM are part of the same spectrum of migraine.

The Almirall European Headache Awards 2009

The Almirall European Headache Awards (AEHA) were organized in conjunction with the European Headache Federation. The awards were held in 2009, aiming to share clinical experience and best practice in headache-related disease management. 56 unusual and challenging cases of headache from 5 European countries (Belgium, France, Italy, Portugal and Spain) were judged by a Scientific Committee including expert representatives from participating countries, acting as reviewers. Three cases were selected from each country. The 15 resulting cases were presented to the Scientific Committee in Madrid, Spain in November 2009 and awards were given to the top 5 presentations. This article presents details of these cases, including the award winning entries. They have been categorized into four main groups: (a) headaches in rare syndromes; (b) secondary headaches to infectious/autoimmune causes or post-trauma/mass occupation; (c) headache in unresolved cases; and (d) other relevant cases. First prize was awarded to a case involving a 55-year-old male with familial thrombocytopenia and a unilateral neuralgiform headache secondary to trigeminal vascular contact, and which was successfully treated with carbamazepine. Conclusions from the meeting include: rare syndromes do occur and require appropriate treatment to improve outcomes; concomitant diseases may impair adequate diagnosis and should be investigated; physicians should be cautious and treat possible serious underlying disease, whilst accurately clarifying the correct diagnosis; neurological examination and complementary tests may be required; consideration should be given to possible rare medication events; and some cases may remain without a clear cause or diagnosis and symptoms should be treated whilst investigations continue.

High cortical spreading depression susceptibility and migraine-associated symptoms in Ca(v)2.1 S218L mice

OBJECTIVE

The CACNA1A gene encodes the pore-forming subunit of neuronal Ca(V)2.1 Ca2+ channels. In patients, the S218L CACNA1A mutation causes a dramatic hemiplegic migraine syndrome that is associated with ataxia, seizures, and severe, sometimes fatal, brain edema often triggered by only a mild head trauma.

METHODS

We introduced the S218L mutation into the mouse Cacna1a gene and studied the mechanisms for the S218L syndrome by analyzing the phenotypic, molecular, and electrophysiological consequences.

RESULTS

Cacna1a(S218L) mice faithfully mimic the associated clinical features of the human S218L syndrome. S218L neurons exhibit a gene dosage-dependent negative shift in voltage dependence of Ca(V)2.1 channel activation, resulting in enhanced neurotransmitter release at the neuromuscular junction. Cacna1a(S218L) mice also display an exquisite sensitivity to cortical spreading depression (CSD), with a vastly reduced triggering threshold, an increased propagation velocity, and frequently multiple CSD events after a single stimulus. In contrast, mice bearing the R192Q CACNA1A mutation, which in humans causes a milder form of hemiplegic migraine, typically exhibit only a single CSD event after one triggering stimulus.

INTERPRETATION

The particularly low CSD threshold and the strong tendency to respond with multiple CSD events make the S218L cortex highly vulnerable to weak stimuli and may provide a mechanistic basis for the dramatic phenotype seen in S218L mice and patients. Thus, the S218L mouse model may prove a valuable tool to further elucidate mechanisms underlying migraine, seizures, ataxia, and trauma-triggered cerebral edema.

Clinical and neuroimaging evidence of interictal cerebellar dysfunction in FHM2

We used multimodal magnetic resonance (MR) techniques [brain diffusion-weighted magnetic resonance imaging, diffusion-weighted imaging (DWI), proton MR spectroscopy (MRS), 1H-MRS; and skeletal muscle phosphorous MRS, 31P-MRS] to investigate interictal brain microstructural changes and tissue energy metabolism in four women with genetically determined familial hemiplegic migraine type 2 (FHM2), belonging to two unrelated families, compared with 10 healthy women. Brain DWI revealed a significant increase of the apparent diffusion coefficient median values in the vermis and cerebellar hemispheres of FHM2 patients, preceding in two subjects the onset of interictal cerebellar deficits. 31P-MRS revealed defective energy metabolism in skeletal muscle of FHM2 patients, while brain 1H-MRS showed a mild pathological increase in lactate in the lateral ventricles of one patient and a mild reduction of cortical N-acetyl-aspartate to creatine ratio in another one. Our MRS results showed that a multisystem energy metabolism defect in FHM2 is associated with microstructural cerebellar changes detected by DWI, even before the onset of cerebellar symptoms.

Migraine and ischemic stroke: a debated question

Numerous epidemiologic observations reporting high prevalence of migraine among young individuals with stroke as well as dysfunction of cerebral arteries during migraine attacks prompt speculation on the existence of a comorbidity between the two disorders. The recent finding of silent infarct-like brain lesions in migraineurs reinforced this hypothesis and raised questions on whether migraine may be a progressive disorder rather than simply an episodic disorder. Stroke can occur during the course of migraine attacks with aura, supporting the assumption of a causal relation between the two diseases. Migraine may accentuate other existing risk factors for stroke, and both jointly increase the risk of cerebral ischemia outside of migraine attacks. In this regard, the role of migraine might be that of predisposing condition for cerebral ischemia. Migraine and ischemic stroke may be the end phenotype of common pathogenic mechanisms. Evidence of a migraine-stroke relation in cases of specific disorders, such as CADASIL (cerebral autosomal-dominant arteriopathy with subcortical infarcts and leukoencephalopathy) and MELAS (mitochondrial myopathy, encephalopathy, lactic acidosis, and stroke-like episodes), strongly supports this concept. Finally, acute focal cerebral ischemia can trigger migraine attacks, and, thus, migraine may be the consequence of stroke. In this paper, we will review contemporary epidemiologic studies, discuss potential mechanisms of migraine-induced stroke and comorbid ischemic stroke, and pose new research questions.

Genetics of migraine headache in children

A family history of migraine is very frequently noted when evaluating a child for recurrent headaches. This implies an inherited or genetic basis as a component to the underlying pathophysiology. A variety of techniques have begun to elucidate this contribution, including historical observation, population-based studies including family and twin studies, gene polymorphism association studies, and specific gene identification for isolated migraine subtypes. This line of investigation should progress in the future to a better understanding of migraine and clarification of the diagnostic subtypes for a genotype-phenotype association.

Migraine: a complex genetic disorder

Although family and twin studies show that there is a genetic component to migraine, no genes predisposing to common forms of the disorder have been identified. The most encouraging findings have emerged from the identification of genes causing rare mendelian traits that phenotypically resemble migraine. These studies have pointed migraine research towards ion-transport genes; however, there is no direct evidence of the involvement of these genes in common forms of migraine. Family-based linkage studies have identified several chromosomal regions linked to common forms of migraine, but there is little consistency between studies. The modest success in the identification of contributing gene variants has stimulated research into more effective strategies. These include new phenotyping methods for genetic studies and new study designs-such as case-control and whole-genome association studies-to identify common variants contributing to the trait.

Targeting neuronal hyperexcitability for antimigraine drug development

Migraine is among the most prevalent neurological disorders worldwide, afflicting up to 16% of the population. Because it mostly affects patients between the most productive ages of 25 and 50 years, migraine costs employers more than US$13 billion per year in reduced productivity and missed days. It is therefore important to prevent and treat migraine attacks. Triptans were introduced in the early 1990s and effectively alleviate symptoms in most patients. Their success was based on the existence of the operational hypothesis implicating the trigemino-vascular system. Prophylactic medications have been available since beta-blockers, followed by agents belonging to other therapeutic classes. Most of them were found serendipitously to be effective. However, progress in the development of preventative agents has been hampered by the lack of animal models mimicking the early events of migraine pathophysiology. This review will examine how a recent theory on the origin of migraine attacks is likely to lead to the development of new animal models.

The phenotypic spectrum of rapid-onset dystonia-parkinsonism (RDP) and mutations in the ATP1A3 gene

Rapid-onset dystonia-parkinsonism (RDP) (also known as DYT12) is characterized by the abrupt onset of dystonia and parkinsonism and is caused by mutations in the ATP1A3 gene. We obtained clinical data and sequenced the ATP1A3 gene in 49 subjects from 21 families referred with 'possible' RDP, and performed a genotype-phenotype analysis. Of the new families referred for study only 3 of 14 families (21%) demonstrated a mutation in the ATP1A3 gene, but no new mutations were identified beyond our earlier report of 6. Adding these to previously reported families, we found mutations in 36 individuals from 10 families including 4 de novo mutations and excluded mutations in 13 individuals from 11 families. The phenotype in mutation positive patients included abrupt onset of dystonia with features of parkinsonism, a rostrocaudal gradient, and prominent bulbar findings. Other features found in some mutation carriers included common reports of triggers, minimal or no tremor at onset, occasional mild limb dystonia before the primary onset, lack of response to dopaminergic medications, rare abrupt worsening of symptoms later in life, stabilization of symptoms within a month and minimal improvement overall. In comparing ATP1A3 mutation positive and negative patients, we found that tremor at onset of symptoms, a reversed rostrocaudal gradient, and significant limb pain exclude a diagnosis of RDP. A positive family history is not required. Genetic testing for the ATP1A3 gene is recommended when abrupt onset, rostrocaudal gradient and prominent bulbar findings are present.

Genetic biomarkers for migraine

Biomarkers are physical signs or laboratory measurements that occur in association with a pathological process and have putative diagnostic and/or prognostic utility. In migraine, clinical, radiological, and biochemical biomarkers might be helpful to improve diagnosis, get insight in pathophysiology, and facilitate treatment choices. Genetic biomarkers are defined as genetic variations (mutations or polymorphisms) that can predict disease susceptibility, disease outcome, or treatment response. As yet, only a few genetic biomarkers for migraine are available. Mutations in 3 different genes responsible for familial hemiplegic migraine, a monogenetic subtype of migraine with aura, and the MTHFR C677T polymorphism in common forms of migraine are clear examples. Many positive findings from linkage studies and association studies in common forms of migraine have not been replicated, and are therefore of less clinical use. In this review, we will discuss genetic biomarkers in migraine.

Migraine genetics: an update

A growing interest in genetic research in migraine has resulted in the identification of several chromosomal regions that are involved in migraine. However, the identification of mutations in the genes for familial hemiplegic migraine (FHM) forms the only true molecular genetic knowledge of migraine thus far. The increased number of mutations in the FHM1 (CACNA1A) and the FHM2 (ATP1A2) genes allow studying the relationship between genetic findings in both genes and the clinical features in patients. A wide spectrum of symptoms is seen in patients. Additional cerebellar ataxia and (childhood) epilepsy can occur in FHM1 and FHM2. Functional studies show a dysfunction in ion transport as the key factor in the pathophysiology of (familial hemiplegic) migraine that predict an increased susceptibility to cortical spreading depression--the underlying mechanism of migraine aura.

Two de novo mutations in the Na,K-ATPase gene ATP1A2 associated with pure familial hemiplegic migraine

Familial hemiplegic migraine (FHM) is a rare autosomal dominantly inherited subtype of migraine, in which hemiparesis occurs during the aura. The majority of the families carry mutations in the CACNA1A gene on chromosome 19p13 (FHM1). About 20% of FHM families is linked to chromosome 1q23 (FHM2), and has mutations in the ATP1A2 gene, encoding the alpha2-subunit of the Na,K-ATPase. Mutation analysis in a Dutch and a Turkish family with pure FHM revealed two novel de novo missense mutations, R593W and V628M, respectively. Cellular survival assays support the hypothesis that both mutations are disease-causative. The identification of the first de novo mutations underscores beyond any doubt the involvement of the ATP1A2 gene in FHM2.

The CACNA1A and ATP1A2 genes are not involved in dominantly inherited migraine with aura

Epidemiological studies indicate that migraine with typical aura (MA) has a major genetic component but the genes for MA have not been identified. However, the autosomal dominantly inherited familial hemiplegic migraine (FHM) is often caused by mutations in the CACNA1A or ATP1A2 genes. The aim of the study was to investigate if the CACNA1A or ATP1A2 genes are involved in MA with an apparently autosomal dominant mode of inheritance. From a clinic population diagnosed by a trained physician we recruited 34 extended families (comprising 174 MA patients) with an apparently autosomal dominant mode of inheritance of MA. We performed a linkage analysis of 161 of 174 MA patients and 79 unaffected relatives using a framework marker set of 44 markers for chromosome 1 and 22 markers for chromosome 19. Linkage analysis was made with a non-parametric or autosomal dominant parametric model, either allowing for heterogeneity or not, using an affected only analysis. We identified no linkage to CACNA1A and ATP1A2 loci on chromosome 19 or 1, respectively. Additionally, at least two patients from each family and 92 healthy, unrelated controls were selected for a sequence analysis. We sequenced the 48 exons of CACNA1A and the 23 exons of ATP1A2, including promoter and flanking intron sequences. No polymorphism was identified in the CACNA1A or ATP1A2 genes with a strong correlation to MA. Our study shows that the CACNA1A or ATP1A2 genes are probably not involved in MA. To identify the genes involved in the common forms of migraine, future genetic studies should focus on MA and migraine without aura (MO) and not FHM.

Cough-induced hemiplegic migraine with impaired consciousness in cystic fibrosis

The coughing paroxysms of patients with cystic fibrosis may occasion neurological symptoms. Although cough syncope is well-known, and is associated with headache and paralysis, a migrainous mechanism has not been reported. We reviewed the medical records, autonomic testing results, and responses to treatment in two cystic fibrosis patients with similar presentations of cough-induced impairment of consciousness followed by headache and paralysis. A 24-year-old woman and an unrelated 38-year-old man, both with cystic fibrosis, developed post-tussive neurologic deficits. Both patients reported infrequent dramatic spells, always preceded by major hemoptysis, and associated with left-sided paralysis, transient blindness, nausea, and severe pulsating headaches. Autonomic testing demonstrated only postural tachycardia and a near-vasodepressor episode in the woman, and mild, generalized sympathetic dysfunction in the man. Treatment for presumptive migraine with aura with verapamil nearly eradicated symptoms in both patients. Discontinuation of verapamil in the woman was associated with symptom recurrence and a stroke, with significant persistent residual left hemiparesis. In conclusion, cough-induced neurologic deficits were previously reported with cystic fibrosis, without clear understanding of the mechanism of impairment of consciousness. Based on the hemiparesis, nausea, and throbbing headache, which repeatedly followed the events in both patients, and based on the response to verapamil, we hypothesize a migrainous mechanism in both of our patients. The pathophysiology that links the hemoptysis to the spells deserves further investigation.

Genomic abnormalities in patients with migraine and chronic migraine: preliminary blood gene expression suggests platelet abnormalities

BACKGROUND

Migraine has strong genetic and environmental components and may also be a significant contributor to chronic migraine (CM). It is hypothesized that gene expression changes in peripheral blood cells can be used to detect the interaction of these influences.

OBJECTIVE

Distinct genomic expression patterns for migraine and CM will be present. These genomic profiles will help clarify the interactions of inheritance and environment. This initial study begins to examine the feasibility of peripheral blood cell genomic analysis to assist in the understanding of the pathophysiology of migraine and CM.

METHODS

Blood samples from patients were obtained either during an acute migraine or CM. Genomic expression patterns were analyzed using Affymetrix U95A microarrays.

RESULTS

Expression patterns of 7 migraine and 15 CM patients were compared to four distinct control groups (total patients, n=56) including healthy subjects. A group of platelet genes were upregulated in both migraine and CM samples. Different gene expression patterns were also seen between migraine and CM. A group of immediate early genes including c-fos and cox-2 were expressed at higher levels in migraine, whereas specific mitochondrial genes were expressed at higher levels in CM.

CONCLUSIONS

Increased expression of platelet genes in patients with migraine and CM suggests similar underlying pathophysiology. The differences seen between migraine and CM in other genes suggest an overlapping but not identical pathophysiology. Further genomic profiling studies will help define these relationships and provide further insights into headache pathogenesis.

Neurobiology in primary headaches

Primary headaches such as migraine and cluster headache are neurovascular disorders. Migraine is a painful, incapacitating disease that affects a large portion of the adult population with a substantial economic burden on society. The disorder is characterised by recurrent unilateral headaches, usually accompanied by nausea, vomiting, photophobia and/or phonophobia. A number of hypothesis have emerged to explain the specific causes of migraine. Current theories suggest that the initiation of a migraine attack involves a primary central nervous system (CNS) event. It has been suggested that a mutation in a calcium gene channel renders the individual more sensitive to environmental factors, resulting in a wave of cortical spreading depression when the attack is initiated. Genetically, migraine is a complex familial disorder in which the severity and the susceptibility of individuals are most likely governed by several genes that vary between families. Genom wide scans have been performed in migraine with susceptibility regions on several chromosomes some are associated with altered calcium channel function. With positron emission tomography (PET), a migraine active region has been pointed out in the brainstem. In cluster headache, PET studies have implicated a specific active locus in the posterior hypothalamus. Both migraine and cluster headache involve activation of the trigeminovascular system. In support, there is a clear association between the head pain and the release of the neuropeptide calcitonin gene-related peptide (CGRP) from the trigeminovascular system. In cluster headache there is, in addition, release of the parasympathetic neuropeptide vasoactive intestinal peptide (VIP) that is coupled to facial vasomotor symptoms. Triptan administration, activating the 5-HT(1B/1D) receptors, causes the headache to subside and the levels of neuropeptides to normalise, in part through presynaptic inhibition of the cranial sensory nerves. These data suggest a central role for sensory and parasympathetic mechanisms in the pathophysiology of primary headaches. The positive clinical trial with a CGRP receptor antagonist offers a new promising way of treatment.