Wolff Award 1997. Involvement of a Ca2+ channel gene in familial hemiplegic migraine and migraine with and without aura. Dutch Migraine Genetics Research Group

Migraine and Its Equivalents: What Do They Share? A Narrative Review on Common Pathophysiological Patterns

Migraine is the first in order of frequency of the neurological disorders, affecting both adult and paediatric populations. It is also the first cause of primary headaches in children. Migraine equivalents are periodic disorders that can be associated with migraine or considered as prognostic features of a future migraine manifestation. Despite the mechanisms underlying migraine and its equivalents are not entirely clear, several elements support the hypothesis of common pathophysiological patterns shared by these conditions. The aim of this review is thus to analyze the literature in order to highlight which currently known mechanisms may be common between migraine and its equivalents.

Primary headaches during lifespan

Primary headaches are one of the most prevalent neurological disorders and can occur during a wide range of lifespan. Primary headaches, especially migraine, are cyclic disorders with a complex sequence of symptoms within every headache attack. There is no systematic review of whether these symptoms changes during lifespan. Indeed, the clinical presentation of migraine shows an age-dependent change with a significantly shorter duration of the attacks and occurrence of different paroxysmal symptoms, such as vomiting, abdominal pain or vertigo, in childhood and, in contrast, largely an absence of autonomic signs and a more often bilateral headache in the elderly. The age-dependent differences in the clinical presentation are less distinct in cluster headache and, especially, in tension-type headache. The differences in the clinical presentation are in agreement with the idea that the connectivity of hypothalamic areas with different brainstem areas, especially the central parasympathetic areas, is important for the clinical manifestation of migraine, as well as, the change during lifespan.

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.

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.

R583Q CACNA1A variant in SHM1 and ataxia: case report and literature update

Familial hemiplegic migraine (FHM) type 1 is a rare monogenic dominant autosomal disease due to CACNA1A gene mutations. Besides the classical phenotype, mutations on CACNA1A gene are associated with a broader spectrum of clinical features including cerebellar ataxia, making FHM1 a complex channelopathy. We report the case of a patient carrying the p.Arg583Gln mutation affected by hemiplegic migraine and late onset ataxia and we performed a literature review about the clinical features of p.Arg583Gln. Although p.Arg583Gln mutations are associated with a heterogeneous phenotype, carriers present cerebellar signs which consisted generally in ataxia and dysmetria, with intention tremor appearing mostly in advanced age, often progressive and permanent. The heterogeneous spectrum of CACNA1A gene mutations probably causes sporadic hemiplegic migraine (SHM) to be misdiagnosed. Given the therapeutic opportunities, SHM/FHM1 should be considered in differential diagnosis of patients with cerebellar ataxia and migraine with aura.

Migraine: an endemic disease inside the blood–brain barrier

Migraine is a complex neurological disorder that in recent years has received more and more attention. Knowledge regarding this primary headache has increased substantially, both with respect to its pathogenesis and how to effectively treat its symptoms. Over the years, the proposed location of the onset of migraine has moved from the periphery of the nervous system toward deeper parts of the brain. Migraine can be viewed as an inherited failure of trigeminal sensory processing with abnormal neuronal excitability in the trigeminal nucleus caudalis, which, in turn, causes central sensitization and amplification of the pain. Increased activation of the trigeminal nerve during a migraine attack causes release of the calcitonin gene-related peptide (CGRP) inside and outside the BBB. Within the CNS, CGRP promotes trigeminal sensory input and facilitates central sensitization. The future introduction of CGRP antagonists in clinical practice could represent significant progress for acute migraine therapy.

CADASIL: the most common hereditary subcortical vascular dementia

Cerebral autosomal dominant arteriopathy with subcortical infarct and leukoencephalopathy (CADASIL) is the most common hereditary subcortical vascular dementia. It is caused by the defective NOTCH3 gene, which encodes a transmembrane receptor; over 170 different mutations are known. The main clinical features are migraine with aura (often atypical or isolated), strokes, cognitive decline/dementia and psychiatric symptoms. Executive and organizing cognitive functions are impaired first, memory is affected late. Typical MRI findings are T2 weighted hyperintensities in temporopolar white matter and the capsula externa. Smooth muscle cells in small arteries throughout the body degenerate and vessel walls become fibrotic. In the brain, this results in circulatory disturbances and lacunar infarcts, mainly in cerebral white matter and deep gray matter. The exact pathogenesis is still open: a dominant-negative toxic effect is suggested, possibly related to Notch3 misfolding. Diagnosis is reached either by identifying a pathogenic NOTCH3 mutation or by electron microscopic demonstration of granular osmiophilic material in a (skin) biopsy. Only symptomatic treatment is available at present.

A genome-wide linkage scan provides evidence for both new and previously reported loci influencing common migraine

Latent class analysis was performed on migraine symptom data collected in a Dutch population sample (N = 12,210, 59% female) in order to obtain empirical groupings of individuals suffering from symptoms of migraine headache. Based on these heritable groupings (h(2) = 0.49, 95% CI: 0.41-0.57) individuals were classified as affected (migrainous headache) or unaffected. Genome-wide linkage analysis was performed using genotype data from 105 families with at least 2 affected siblings. In addition to this primary phenotype, linkage analyses were performed for the individual migraine symptoms. Significance levels, corrected for the analysis of multiple traits, were determined empirically via a novel simulation approach. Suggestive linkage for migrainous headache was found on chromosomes 1 (LOD = 1.63; pointwise P = 0.0031), 13 (LOD = 1.63; P = 0.0031), and 20 (LOD = 1.85; P = 0.0018). Interestingly, the chromosome 1 peak was located close to the ATP1A2 gene, associated with familial hemiplegic migraine type 2 (FHM2). Individual symptom analysis produced a LOD score of 1.97 (P = 0.0013) on chromosome 5 (photo/phonophobia), a LOD score of 2.13 (P = 0.0009) on chromosome 10 (moderate/severe pain intensity) and a near significant LOD score of 3.31 (P = 0.00005) on chromosome 13 (pulsating headache). These peaks were all located near regions previously reported in migraine linkage studies. Our results provide important replication and support for the presence of migraine susceptibility genes within these regions, and further support the utility of an LCA-based phenotyping approach and analysis of individual symptoms in migraine genetic research. Additionally, our novel "2-step" analysis and simulation approach provides a powerful means to investigate linkage to individual trait components.

Neuro-ophthalmologic manifestations of primary headache disorders

Headaches are the most common disorders of the central nervous system affecting 46% of the adult population worldwide. Headaches may be lifelong illnesses, often associated with substantial disability for the individual and the population as a whole. The International Classification of Headache Disorders (ICHD-II) codifies headache disorders into fourteen categories, predominantly primary headaches and secondary headache disorders. Primary headache disorders, mainly migraine and trigeminal autonomic cephalgias (TACs), are frequently associated with neuro-ophthalmologic manifestations. Ophthalmologists are often the first physicians to be involved in the deciphering of headache-related visual disturbances. This article reviews two major primary headache disorders, migraine and trigeminal autonomic cephalgias, and discusses their neuro-ophthalmic complications, clinical presentation, and treatment.

CADASIL: a common form of hereditary arteriopathy causing brain infarcts and dementia

Cerebral autosomal dominant arteriopathy with subcortical infarcts and leukoencephalopathy (CADASIL) is a hereditary cerebrovascular disease leading to cognitive decline and dementia. CADASIL usually begins with migraine in about one third of the patients. More severe manifestations, transient ischemic attacks or recurrent strokes, appear between 30 and 50 years of age. CADASIL, however, may be diagnosed well before the first stroke on the basis of characteristic white matter hyperintensities upon magnetic resonance imaging and presence of pathognomonic granular osmiophilic material in arterial walls, including dermal arteries, since the arteriopathy is generalized. Gradual destruction of vascular smooth muscle cells (VSMC) leads to progressive wall thickening and fibrosis and luminal narrowing in small and medium-sized penetrating arteries. The reduced cerebral blood flow finally causes lacunar infarcts, mainly in the basal ganglia and fronto-temporal white matter, which lead to cognitive deficits and dementia of the subcortical vascular type. CADASIL is caused by single missense mutations or small deletions in Notch3 gene encoding a transmembrane receptor Notch3, of which upon ligand binding a nuclear signaling protein is generated by regulated intramembrane proteolysis. Notch signaling is essential during development, regulating cellular differentiation. In adults Notch3 is expressed only in VSMCs and it may promote cell survival by inhibiting apoptosis, but its exact function is unknown. Mutations result in either a gain or loss of one (or rarely, 3) cysteine residue(s) in one of the 34 epidermal growth factor-like repeats in the extracellular amino-terminal region of Notch3. It is as yet unclear which disturbance in the Notch signaling pathway leads to the characteristic vascular pathology of CADASIL.

Genomewide significant linkage to migrainous headache on chromosome 5q21

Familial typical migraine is a common, complex disorder that shows strong familial aggregation. Using latent-class analysis (LCA), we identified subgroups of people with migraine/severe headache in a community sample of 12,245 Australian twins (60% female), drawn from two cohorts of individuals aged 23-90 years who completed an interview based on International Headache Society criteria. We report results from genomewide linkage analyses involving 756 twin families containing a total of 790 independent sib pairs (130 affected concordant, 324 discordant, and 336 unaffected concordant for LCA-derived migraine). Quantitative-trait linkage analysis produced evidence of significant linkage on chromosome 5q21 and suggestive linkage on chromosomes 8, 10, and 13. In addition, we replicated previously reported typical-migraine susceptibility loci on chromosomes 6p12.2-p21.1 and 1q21-q23, the latter being within 3 cM of the rare autosomal dominant familial hemiplegic migraine gene (ATP1A2), a finding which potentially implicates ATP1A2 in familial typical migraine for the first time. Linkage analyses of individual migraine symptoms for our six most interesting chromosomes provide tantalizing hints of the phenotypic and genetic complexity of migraine. Specifically, the chromosome 1 locus is most associated with phonophobia; the chromosome 5 peak is predominantly associated with pulsating headache; the chromosome 6 locus is associated with activity-prohibiting headache and photophobia; the chromosome 8 locus is associated with nausea/vomiting and moderate/severe headache; the chromosome 10 peak is most associated with phonophobia and photophobia; and the chromosome 13 peak is completely due to association with photophobia. These results will prove to be invaluable in the design and analysis of future linkage and linkage disequilibrium studies of migraine.

The migraine variants

The migraine variants are unique to pediatrics and are a fascinating and challenging group of disorders characterized by the onset of focal neurological signs and symptoms such as hemiparesis, altered consciousness nystagmus, or ophthalmoparesis followed by headache. Because all of the diagnoses discussed represent diagnoses of exclusion, only after a careful medical history, a physical examination, and appropriate neurodiagnostic studies can they be entertained comfortably. Often, these ominous neurological signs initially lead the clinician in the direction of epileptic, cerebrovascular, traumatic, or metabolic disorders, and only after thorough neurodiagnostic testing does the diagnosis become apparent. Some of these entities occur in infants and young children in which the medical history is limited.

Depolarisation phenomena in traumatic and ischaemic brain injury

1. Cortical spreading depression is a non-physiological global depolarisation of neurones and astrocytes that can be initiated with varying degrees of difficulty in the normally perfused cerebral cortex in the experimental laboratory. Induction is typically with electrical stimulation, needling of the cerebral cortex, or superfusion of isotonic or more concentrated potassium chloride solution. The phenomenon propagates across the cerebral cortex at a rate of 2-5 mm per minute, and is accompanied by marked but transient increases in cerebral blood flow, in local tissue oxygen tension, and most probably in metabolic rate. 2. Peri-infarct depolarisation is also a depolarisation event affecting neurones and glia, with an electrophysiological basis similar or identical to CSD, but occurring spontaneously in the ischaemic penumbra or boundary zone in focal cerebral cortical ischaemia. Most such events arise from the edge of the ischaemic core, and propagate throughout the penumbra, at a rate similar to that of cortical spreading depression. 3. Cortical spreading depression in the normally perfused cortex does not result in histological damage whereas peri-infarct depolarisations augment neuronal damage in the penumbra, and are believed by many authors to constitute an important, or the principal, mechanism by which electrophysiological penumbra progressively deteriorates, ultimately undergoing terminal depolarisation and thus recruitment into an expanded core lesion. 4. There is some experimental evidence to suggest that under some circumstances induction of episodes of cortical spreading depression can confer protection against subsequent ischaemic insults. 5. Although cortical spreading depression and peri-infarct depolarisations have been extensively studied in the experimental in vivo models, there is now clear evidence that depolarisations also occur and propagate in the human brain in areas surrounding a focus of traumatic contusion. 6. Whether such events in the injured human brain represent cortical spreading depression or peri-infarct depolarisation is unclear. However, invasive and probably non-invasive monitoring methods are available which may serve to distinguish which event has occurred. 7. Much further work will be needed to examine the relationship of depolarisation events in the injured brain with outcome from cerebral ischaemia or head injury, to examine the factors which influence the frequency of depolarisation events, and to determine which depolarisation events in the human brain augment the injury and should be prevented.

Search for intracranial aneurysm susceptibility gene(s) using Finnish families

BACKGROUND

Cerebrovascular disease is the third leading cause of death in the United States, and about one-fourth of cerebrovascular deaths are attributed to ruptured intracranial aneurysms (IA). Epidemiological evidence suggests that IAs cluster in families, and are therefore probably genetic. Identification of individuals at risk for developing IAs by genetic tests will allow concentration of diagnostic imaging on high-risk individuals. We used model-free linkage analysis based on allele sharing with a two-stage design for a genome-wide scan to identify chromosomal regions that may harbor IA loci.

METHODS

We previously estimated sibling relative risk in the Finnish population at between 9 and 16, and proceeded with a genome-wide scan for loci predisposing to IA. In 85 Finnish families with two or more affected members, 48 affected sibling pairs (ASPs) were available for our genetic study. Power calculations indicated that 48 ASPs were adequate to identify chromosomal regions likely to harbor predisposing genes and that a liberal stage I lod score threshold of 0.8 provided a reasonable balance between detection of false positive regions and failure to detect real loci with moderate effect.

RESULTS

Seven chromosomal regions exceeded the stage I lod score threshold of 0.8 and five exceeded 1.0. The most significant region, on chromosome 19q, had a maximum multipoint lod score (MLS) of 2.6.

CONCLUSIONS

Our study provides evidence for the locations of genes predisposing to IA. Further studies are necessary to elucidate the genes and their role in the pathophysiology of IA, and to design genetic tests.

A susceptibility locus for migraine with aura, on chromosome 4q24

Migraine is a complex neurovascular disorder with substantial evidence supporting a genetic contribution. Prior attempts to localize susceptibility loci for common forms of migraine have not produced conclusive evidence of linkage or association. To date, no genomewide screen for migraine has been published. We report results from a genomewide screen of 50 multigenerational, clinically well-defined Finnish families showing intergenerational transmission of migraine with aura (MA). The families were screened using 350 polymorphic microsatellite markers, with an average intermarker distance of 11 cM. Significant evidence of linkage was found between the MA phenotype and marker D4S1647 on 4q24. Using parametric two-point linkage analysis and assuming a dominant mode of inheritance, we found for this marker a maximum LOD score of 4.20 under locus homogeneity (P=.000006) or locus heterogeneity (P=.000011). Multipoint parametric (HLOD = 4.45; P=.0000058) and nonparametric (NPL(all) = 3.43; P=.0007) analyses support linkage in this region. Statistically significant linkage was not observed in any other chromosomal region.

Static stabilometry in patients with migraine and tension-type headache during a headache-free period

The vestibulospinal system was evaluated using a stabilometric method in patients with migraine and episodic tension-type headache during headache-free periods. Migraine patients often complain of dizziness or vertigo during headache attacks and some exhibit these symptoms between attacks. Computerized static stabilometry is a reliable and non-invasive technique to evaluate the equilibrium function in various diseases. The subjects consisted of 21 patients with migraine, 12 patients with episodic tension-type headache and, age- and sex-matched controls. We performed two sets of static stabilometric measurements with eyes open (EO) and eyes closed (EC) for 30 s. The averages of two sessions of the following six stabilometric parameters were used for the analysis: locus length (LNG), environmental area (ENV-AREA), rectangle area (REC-AREA), locus length per second, locus length per environ area (L/E), and root mean square area. Romberg quotients (EC/EO) of these six parameters were also analyzed. The mean values of LNG, ENV-AREA and REC-AREA in the EC session in the migraine group were significantly greater than those in the controls (P < 0.05, Mann-Whitney rank sum test). Romberg quotients of all stabilometric parameters except the L/E in the migraine group were significantly greater than in the controls. Patients with episodic tension-type headache did not show any differences in the stabilometric study from the controls. The present findings suggest that patients with migraine show a significant increase of the body sway during the EC session, which indicates an underlying dysfunction in the vestibulospinal system.

CACNA1A gene polymorphisms in cluster headache

Cluster headache (CH) is a primary headache disorder where the aetiological and pathophysiological mechanisms still are largely unknown. An increased risk of CH in first- and second-degree relatives suggests the importance of genetic factors. Mutations of the P/Q type calcium channel alpha 1 subunit (CACNA1A) gene on chromosome 19p13 have been shown to cause several neurological disorders with a wide clinical spectrum, mainly episodic diseases. Missense mutations of the gene cause familial hemiplegic migraine (FHM) and it is also likely to be involved in the more common forms of migraine. The CACNA1A gene is thus a promising candidate gene for CH. In this study we performed an association analysis of an intragenic polymorphic (CA)n-repeat with marker D19S1150 and a (CAG)n-repeat in the 3'UTR region, in 75 patients with CH according to IHS criteria and 108 matched controls. Genotypes and allele frequencies were similarly distributed in patients and controls. Linkage disequilibrium between the two markers was similar in patients and controls. We conclude that an importance of the CACNA1A gene in sporadic CH is unlikely.

Familial migraine with and without aura: clinical characteristics and co-occurrence

Migraine with aura (MwA) and migraine without aura (MwoA) are the two common forms of migraine. Many migraine patients suffer from both kinds of attacks. In a questionnaire-based study using the current International Headache Society (IHS) criteria we determined the clinical characteristics and occurrence of MwA + MwoA in 1000 migraine patients belonging to 210 Finnish migraine families. Nine hundred and six patients were able to indicate whether they suffered from MwA (but not MwoA), migraine aura without headache (migraine equivalent) (but not MwA) or MwA and MwoA. Of these patients, 3.2% had experienced MwoA, 11.1% MwA, 40.6% MwA + MwoA, 23.5% MwoA and 20.3% MwA-like symptoms not meeting the IHS criteria. The high prevalence of MwA attacks in the families studied supports the belief that aura has a strong hereditary component. The MwA + MwoA patients had significantly more severe attacks, more typical headache and more prodromal symptoms than the MwA and MwoA subjects. Therefore, it is possible that there is a continuum with pure MwA at the neural and pure MwoA at the headache end of the spectrum, and MwA + MwoA lying in between the two. The MwA + MwoA patients would thus be liable to both types of migraine, making their attacks more characteristic and more severe. This would also explain why the co-occurrence of MwA and MwoA is more common in the clinic compared with population based epidemiological studies. These findings have consequences for future research on liability genes for migraine.

Hyposerotonin-induced nitric oxide supersensitivity in the cerebral microcirculation

OBJECTIVE

To investigate the relationship between hyposerotonin and cranial microvascular responses to nitric oxide (NO).

BACKGROUND

Although the mechanism underlying NO supersensitivity in migraine is still unclear, an alteration of the serotonin system is a possible explanation.

METHODS

Wistar rats were divided into control and hyposerotonin groups. Serotonin was depleted by intraperitoneal injection with 300 mg/kg of para-chlorophenylalanine (PCPA), a tryptophan hydroxylase inhibitor. Three days after PCPA pretreatment, the animals were prepared for assessment of their NO-induced vasomotor response using glyceryl trinitrate (GTN: 8 to 10 mg/kg, intravenously) as an NO donor. Pial circulation was visualized by the intravital fluorescein videomicroscopic technique. Images of vessels at 0, 5, 15, 30, and 60 minutes post GTN infusion were digitized and measured. At the end of monitoring, the rat brains were removed for ultrastructural study of the brain microvessels.

RESULTS

Infusion of GTN produced dose-dependent pial arteriolar dilatation. This vasodilator effect was significantly increased in the PCPA-treated groups, especially at 30 and 60 minutes. The percentage change from baseline diameter at 30 minutes after the 8-mg/kg GTN infusion was 42.6 +/- 3.1 for the hyposerotonin group and 16.8 +/- 2.9 for the control group (P<.001). Electron microscopic study revealed that exposure to the NO donor produced considerable changes in cerebral microvessels, characterized by focal ballooning of endothelial cells, increased microvillous formation, and increased endothelial pinocytosis. These anatomical changes were significantly more prominent in the hyposerotonin group.

CONCLUSIONS

A hyposerotoninergic condition can facilitate the NO-induced physiological and pathological responses in meningeal and cerebral microvessels and, therefore, is a possible explanation for the supersensitivity to NO observed in patients with migraine.

Migraine

The enormous economic cost of migraine attacks is only now becoming evident. One estimate is that they cost $6 billion per year in the United States alone. If treatments are effective enough to keep patients at work, considerable expenditure for treatment can be justified. Most patients never seek medical advice, and one assumes that their headaches are under satisfactory control with simple over-the-counter analgesics. The minority seeking medical advice, who suffer the bulk of absences from work and loss of efficacy, should be offered treatment potent enough to enable them to function normally, if possible. The new serotonin agonist triptan drugs are proving immensely valuable, and there is little doubt that they are cost effective in patients who are severely affected. One should always be aware of the potential for these medications to cause headache if taken in excess. Regular preventive treatment and potent analgesia should be considered in patients with frequent spontaneous attacks of headache.

Migraine: clinical features and diagnosis

Migraine is a syndrome characterized by recurrent headaches with or without aura. Triggers include foods, hormonal changes, and stressors. Migraine must be differentiated from other unilateral headache disorders and from headaches due to other neurologic and systemic diseases.

CADASIL: hereditary disease of arteries causing brain infarcts and dementia

Cerebral autosomal dominant arteriopathy with subcortical infarcts and leukoencephalopathy (CADASIL) begins with migraine with aura in approximately one-third of the patients. More severe symptoms of recurrent strokes usually appear at 30-50 years of age. However, well before the first stroke, CADASIL may be diagnosed on the basis of characteristic hyperintensities in T2-weighted magnetic resonance images. Multiple lacunar infarcts located mainly in the basal ganglia and frontal white matter lead to a cognitive decline and finally to dementia. These infarcts result from a thickening and fibrosis of the walls of the small and medium-sized penetrating arteries with consequent obliteration and/or thrombosis. Although the symptoms are almost exclusively neurological, the arteriopathy is generalized. Thus, basophilic, periodic acid-Schiff-positive and, in electron microscopy, osmiophilic material accumulates between degenerating smooth muscle cells. This occurs even in dermal arteries, which renders skin a useful target for diagnostic biopsy. Presently, no specific therapy is available. CADASIL is caused by missense point mutations in the Notch3 gene, which encodes a transmembrane receptor protein. Each gene defect leads to either a gain or loss of a cysteine residue in the extracellular, N-terminal domain of the molecule, which most probably results in conformational alteration. The function of Notch3 in adults and the pathogenesis of CADASIL are still unknown.

[Migraine with aphasia. Report of a family]

We describe a Brazilian family in which one female patient and her three daughters present a clinical course compatible with migraine, preceded by language disorders (aphasia), without paresis. Several aspects related to genetics of migraine are reviewed. We conclude that further genetical studies are necessary to establish if these cases are different sources of well-known migraine subtypes as the familial hemiplegic migraine.

Ion channel mutations affecting muscle and brain

Voltage-gated ion channels control many aspects of signal transduction in both muscle and nerve. These channels are finely tuned, and either increased or decreased channel activity can adversely affect function. In skeletal muscle, mutations in ion channel genes have been shown to cause both myotonic discharges and episodic paralysis. In cardiac muscle, mutations in related ion channels can produce repolarization defects and fatal arrhythmias. During the past 2 years, a new chapter in the channelopathy story has been opened with the identification of ion channel mutations in the brain that cause disorders ranging from episodic ataxia to epilepsy.