The clinical spectrum of familial hemiplegic migraine associated with mutations in a neuronal calcium channel

Familial and sporadic hemiplegic migraine: diagnosis and treatment

OPINION STATEMENT

Hemiplegic migraine (HM) is a rare subtype of migraine with aura, characterized by transient hemiparesis during attacks. Diagnosis is based on the International Classification of Headache Disorders criteria (ICHD-II). Two types of HM are recognized: familial (FHM) and sporadic hemiplegic migraine (SHM). HM is genetically heterogeneous. Three genes have been identified (CACNA1A, ATP1A2, and SCN1A) but more, so far unknown genes, are involved. Clinically, attacks of the 3 subtypes cannot be distinguished. The diagnosis can be confirmed but not ruled out by genetic testing, because in some HM patients other, not yet identified, genes are involved. The presence of additional symptoms (such as chronic ataxia or epilepsy) may increase the likelihood of identifying a mutation. Additional diagnostics like imaging, CSF analysis, or an EEG are mainly performed to exclude other causes of focal neurological symptoms associated with headache. Conventional cerebral angiography is contraindicated in HM because this may provoke an attack. Because HM is a rare condition, no clinical treatment trials are available in this specific subgroup of migraine patients. Thus, the treatment of HM is based on empirical data, personal experience of the treating neurologist, and involves a trial-and-error strategy. Acetaminophen and NSAIDs often are the first choice in acute treatment. Although controversial in HM, triptans can be prescribed when headaches are not relieved sufficiently with common analgesics. An effective treatment for the severe and often prolonged aura symptoms is more warranted, but currently no such acute treatment is available. Prophylactic treatment can be considered when attack frequency exceeds 2 attacks per month, or when severe attacks pose a great burden that requires reduction of severity and frequency. In no strictly preferred order, flunarizine, sodium valproate, lamotrigine, verapamil, and acetazolamide can be tried. While less evidence is available for prophylactic treatment with topiramate, candesartan, and pizotifen, these drugs can also be considered. The use of propranolol in HM is more controversial, but evidence of adverse effects is insufficient to contraindicate beta-blockers.

Idiopathic focal epilepsies

In this chapter we include a series of epilepsies with onset in pediatric age characterized by focal seizures, idiopathic etiology, normal psychomotor development, and a benign course related to the spontaneous remission of seizures without sequelae. These entities are age-dependent and seizures tend to disappear spontaneously. For these reasons often the drug treatment is not necessary. On the basis of genetic assessment idiopathic focal epilepsies can be divided into two groups: nonautosomal dominant and autosomal dominant. In the group of nonautosomal entities we include benign epilepsy with centro-temporal spikes, Panayiotopoulos syndrome, idiopathic childhood occipital epilepsy described by Gastaut, and benign idiopathic midline spikes epilepsy. Seizures are rare, sometimes prolonged, as autonomic status in Panayiotopoulos syndrome. A common feature is the presence of peculiar EEG interictal paroxysmal abnormalities. In the group with an autosomal dominant mode of inheritance we include benign familial infantile seizures and benign familial neonatal-infantile seizures. These entities are characterized by partial seizures in cluster, self-limited in a brief period during the first months of life. There are no typical interictal EEG abnormalities. In some families a mutation in SCN2A, the gene coding for the 2α subunit of the voltage-gated sodium channel, has been described.

Calcium channels and migraine

Missense mutations in CACNA1A, the gene that encodes the pore-forming α1 subunit of human voltage-gated Ca(V)2.1 (P/Q-type) calcium channels, cause a rare form of migraine with aura (familial hemiplegic migraine type 1: FHM1). Migraine is a common disabling brain disorder whose key manifestations are recurrent attacks of unilateral headache that may be preceded by transient neurological aura symptoms. This review, first, briefly summarizes current understanding of the pathophysiological mechanisms that are believed to underlie migraine headache, migraine aura and the onset of a migraine attack, and briefly describes the localization and function of neuronal Ca(V)2.1 channels in the brain regions that have been implicated in migraine pathogenesis. Then, the review describes and discusses i) the functional consequences of FHM1 mutations on the biophysical properties of recombinant human Ca(V)2.1 channels and native Ca(V)2.1 channels in neurons of knockin mouse models carrying the mild R192Q or severe S218L mutations in the orthologous gene, and ii) the functional consequences of these mutations on neurophysiological processes in the cerebral cortex and trigeminovascular system thought to be involved in the pathophysiology of migraine, and the insights into migraine mechanisms obtained from the functional analysis of these processes in FHM1 knockin mice. This article is part of a Special Issue entitled: Calcium channels.

Long-term outcome of cognitive functions, emotional behavior, and quality of life in a family with familial hemiplegic migraine

OBJECTIVE

To investigate long-term cognitive outcome, mood, and quality of life in a family with genetically proven familial hemiplegic migraine (FHM).

BACKGROUND

FHM is a rare autosomal-dominant subtype of migraine with aura, characterized by some degree of hemiparesis during the aura. In a previous study, we showed preserved and impaired cognitive functions in patients with FHM. Until now, the progression of cognitive dysfunctions has not been known. However, the ability to predict progression is important for counseling patients about education, career, and family life.

METHODS

Seven years after extensive baseline neuropsychological testing, we retested 6 members of a family with FHM, including questionnaires about mood and quality of life.

RESULTS

The follow-up assessment revealed no global cognitive decline. All the patients' linguistic abilities and verbal memory remained intact; however, their figural memory, attention, and some aspects of executive function were impaired. Half the patients had a slight deterioration in their visuoconstructional functions. Half had higher scores on the trait and state anxiety measures.

CONCLUSIONS

Cognitive deficits in a family with FHM persisted, but without marked progression. Worsening of visuoconstructional abilities may be related to executive dysfunction, confirming a disturbance of cerebrocerebellar circuits.

Sporadic hemiplegic migraine presenting as acute encephalopathy

A 10-year-old boy with psychomotor developmental delay and cerebellar vermis atrophy developed right hemiplegia with vomiting, unconsciousness, convulsions, and late-onset fever. Slow delta activity was noted over the left hemisphere on electroencephalography, and neuroimaging revealed swelling of the left temporo-occipital cerebral cortex with restricted diffusivity, successive transient cortical atrophy, and hyperperfusion over the left cerebral hemisphere. Interleukin-6 was elevated in the cerebrospinal fluid. The acute symptoms resolved completely within 3 weeks after onset, but hypoperfusion persisted in the left posterior cortex thereafter. Another episode with transient left hemiplegia appeared 7 months later, followed by recurrence of migraine attacks. Analysis of the CACNA1A gene revealed a mutation of c.1997 C>T (p.T666M). None of his family members had migraine. This case represents an unusual evolution of sporadic hemiplegic migraine with manifestations of acute encephalopathy, for which the role of migraine-related inflammatory process is assumed.

Genetics of migraine: an update

An important genetic component of migraine was systematically established by epidemiological studies in the 1990s. Over the past 15 years, significant progress has been made in unraveling the genetic basis and pathophysiological mechanisms of familial hemiplegic migraine, a rare and severe autosomal-dominant subtype of migraine with aura. Three different causative genes (CACNA1A, ATP1A2 and SCN1A), all of which are involved in cerebral ion translocation, have been identified. Functional studies and mouse models have shown that mutations in these genes, by different mechanisms, cause a disturbed cerebral glutamate homeostasis and, thus, increase susceptibility to cortical spreading depression, the likely correlate of migraine aura. More recently, genome-wide association studies have, for the first time, detected robust risk variants associated with the more common, genetically complex types of migraine, which has generated new perspectives for genetic research in migraine. This review summarizes the current knowledge about migraine genetics, with a focus on both familial hemiplegic migraine and recent results of genome-wide association studies.

Familial hemiplegic migraine with prolonged coma and cerebellar atrophy: CACNA1A T666M mutation in a Korean family

We report the first Korean patient with familial hemiplegic migraine type 1, with clinical and multimodal imaging findings. A 43-yr-old man was admitted for right hemianopia and aphasia, followed by coma. MRI showed only cerebellar atrophy. CT angiography showed mild vasodilation of intracranial blood vessels and increased vascularity in the left hemisphere and perfusion-weighted imaging showed elevated cerebral blood flow. Gene analysis of the patient and his mother led to the identification of a heterozygous point mutation (1997C→T, T666M) in exon 16 of the CACNA1A gene. Familial hemiplegic migraine should be considered in patients with episodic neurological dysfunction with cerebellar atrophy.

A case of familial hemiplegic migraine associated with a novel ATP1A2 gene mutation

Hemiplegic migraine constitutes an unusual form, characterized by periodic attacks of migraine with a motor component (hemiplegia). Familial forms are dominantly inherited, and are attributable to mutations in genes encoding proteins involved in ion transportation, including ATP1A2, which codes for the α-2 isoform of the sodium-potassium adenosine triphosphatase, a P-type cation transport adenosine triphosphatase, and responsible for the so-called familial hemiplegic migraine type 2. We describe a 9-year-old boy affected by familial hemiplegic migraine, with a novel ATP1A2 gene mutation (c.1799T>C p.V600A) in exon 13. Long-term treatment with flunarizine resulted in a good clinical response and the prevention of further attacks.

Acute confusional migraine: our knowledge to date

Acute confusional migraine (ACM) is a rare migraine variant, affecting children and adolescents, as well as adults. Between 0.45 and 7.8% of children with migraine present with ACM, but the disorder may well be underdiagnosed. ACM is an exclusion diagnosis and some dangerous causes of confusion (e.g., epilepsy, ischemia, hemorrhagia, neoplasm, intoxication and encephalitis) should be ruled out. The confusional state often manifests with a wide diversity of cortical dysfunctions, such as speech difficulties, increased alertness, agitation and amnesia. Exact history taking, clinical examination, and laboratory, radiological and electroencephalographical findings lead the practitioner towards the diagnosis. Approximately half of the cases may be triggered by mild head trauma. Transient global amnesia is an important differential diagnosis, possibly caused by similar pathophysiological mechanisms. The exact pathomechanism remains unclear, with the common hypothesis comprising of the confusional state as a complex aura phenomenon, in which the cortical spreading depression wave reaches not only the occipital, but also the temporal, parietal and frontal cortex, as well as the brainstem and the hippocampi, leading to transient hypoperfusion and dysfunction of these brain areas.

Pathophysiological role of omega pore current in channelopathies

In voltage-gated cation channels, a recurrent pattern for mutations is the neutralization of positively charged residues in the voltage-sensing S4 transmembrane segments. These mutations cause dominant ion channelopathies affecting many tissues such as brain, heart, and skeletal muscle. Recent studies suggest that the pathogenesis of associated phenotypes is not limited to alterations in the gating of the ion-conducting alpha pore. Instead, aberrant so-called omega currents, facilitated by the movement of mutated S4 segments, also appear to contribute to symptoms. Surprisingly, these omega currents conduct cations with varying ion selectivity and are activated in either a hyperpolarized or depolarized voltage range. This review gives an overview of voltage sensor channelopathies in general and focuses on pathogenesis of skeletal muscle S4 disorders for which current knowledge is most advanced.

Psychotic aura symptoms in familial hemiplegic migraine type 2 (ATP1A2)

INTRODUCTION

Neuropsychological symptoms are rare in familial hemiplegic migraine (FHM). There are no reports of psychotic symptoms in FHM type 2 (ATP1A2). We examined a family with a FHM phenotype due to a M731T mutation in ATP1A2. A 10-year follow-up allowed us to observe complex auras, including psychotic symptoms in two siblings.

CASE REPORT

Male, 48 years old, with an aura that included complex illusions with a feeling of time travelling, coincident with other aura features. The aura was regarded as mystical by the patient. Female, 38 years old, with a complex migraine aura, during which she believed she had the ability to time travel and was being followed by lobbyists who wanted to steal this ability from her.

DISCUSSION

FHM type 2 must be included in the list of differential diagnoses of acute psychosis in patients with a previous history of migraine aura.

Familial hemiplegic migraine type 1 mutations W1684R and V1696I alter G protein-mediated regulation of Ca(V)2.1 voltage-gated calcium channels

Familial hemiplegic migraine type 1 (FHM-1) is a monogenic form of migraine with aura that is characterized by recurrent attacks of a typical migraine headache with transient hemiparesis during the aura phase. In a subset of patients, additional symptoms such as epilepsy and cerebellar ataxia are part of the clinical phenotype. FHM-1 is caused by missense mutations in the CACNA1A gene that encodes the pore-forming subunit of Ca(V)2.1 voltage-gated Ca(2+) channels. Although the functional effects of an increasing number of FHM-1 mutations have been characterized, knowledge on the influence of most of these mutations on G protein regulation of channel function is lacking. Here, we explored the effects of G protein-dependent modulation on mutations W1684R and V1696I which cause FHM-1 with and without cerebellar ataxia, respectively. Both mutations were introduced into the human Ca(V)2.1α(1) subunit and their functional consequences investigated after heterologous expression in human embryonic kidney 293 (HEK-293) cells using patch-clamp recordings. When co-expressed along with the human μ-opioid receptor, application of the agonist [d-Ala2, N-MePhe4, Gly-ol]-enkephalin (DAMGO) inhibited currents through both wild-type (WT) and mutant Ca(V)2.1 channels, which is consistent with the known modulation of these channels by G protein-coupled receptors. Prepulse facilitation, which is a way to characterize the relief of direct voltage-dependent G protein regulation, was reduced by both FHM-1 mutations. Moreover, the kinetic analysis of the onset and decay of facilitation showed that the W1684R and V1696I mutations affect the apparent dissociation and reassociation rates of the Gβγ dimer from the channel complex, suggesting that the G protein-Ca(2+) channel affinity may be altered by the mutations. These biophysical studies may shed new light on the pathophysiology underlying FHM-1.

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.

Neuronal P/Q-type calcium channel dysfunction in inherited disorders of the CNS

The past two decades have witnessed the emergence of a new and expanding field of neurological diseases--the genetic ion channelopathies. These disorders arise from mutations in genes that encode ion channel subunits, and manifest as paroxysmal attacks involving the brain or spinal cord, and/or muscle. The voltage-gated P/Q-type calcium channel (P/Q channel) is highly expressed in the cerebellum, hippocampus and cortex of the mammalian brain. The P/Q channel has a fundamental role in mediating fast synaptic transmission at central and peripheral nerve terminals. Autosomal dominant mutations in the CACNA1A gene, which encodes voltage-gated P/Q-type calcium channel subunit α(1) (the principal pore-forming subunit of the P/Q channel) are associated with episodic and progressive forms of cerebellar ataxia, familial hemiplegic migraine, vertigo and epilepsy. This Review considers, from both a clinical and genetic perspective, the various neurological phenotypes arising from inherited P/Q channel dysfunction, with a focus on recent advances in the understanding of the pathogenetic mechanisms underlying these disorders.

Episodic ataxias 1 and 2

The episodic ataxias are autosomal dominant disorders usually beginning in the first two decades of life. Episodic ataxia type 1 (EA1) is characterized by brief episodes of ataxia, typically lasting seconds, and interictal myokymia, while episodic ataxia type 2 (EA2) is manifested by longer episodes of ataxia (hours) with interictal nystagmus. The EA1 gene (KCNA1) codes for the six transmembrane segments (S1 to S6) of the Kv1.1 potassium channel subunit and the EA2 gene (CACNA1A) encodes for the Ca(v)2.1 subunit of the P/Q calcium channel complex. EA1 mutations are always missense while most EA2 mutations disrupt the reading frame. Studies of the biophysical properties of the mutant Kv1.1 and Ca(v)2.1 channels in Xenopus oocytes and mammalian cell lines demonstrate clear physiologic consequences of the genetic mutations although no consistent pattern for genotype-phenotype correlation has emerged. Genetic testing for EA1 and EA2 is available, but since no single mutation is prominent for either KCNA1 or CACNA1A, all of the coding regions of the genes need to be screened for mutations. Acetazolamide can be dramatic in controlling episodes of ataxia with EA2 but is typically less beneficial with EA1.

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.

CaV2.1 voltage activated calcium channels and synaptic transmission in familial hemiplegic migraine pathogenesis

Studies on the genetic forms of epilepsy, chronic pain, and migraine caused by mutations in ion channels have given crucial insights into the molecular mechanisms, pathogenesis, and therapeutic approaches to complex neurological disorders. In this review we focus on the role of mutated CaV2.1 (i.e., P/Q-type) voltage-activated Ca2+ channels, and on the ultimate consequences that mutations causing familial hemiplegic migraine type-1 (FHM1) have in neurotransmitter release. Transgenic mice harboring the human pathogenic FHM1 mutation R192Q or S218L (KI) have been used as models to study neurotransmission at several central and peripheral synapses. FHM1 KI mice are a powerful tool to explore presynaptic regulation associated with expression of CaV2.1 channels. Mutated CaV2.1 channels activate at more hyperpolarizing potentials and lead to a gain-of-function in synaptic transmission. This gain-of-function might underlie alterations in the excitatory/ inhibitory balance of synaptic transmission, favoring a persistent state of hyperexcitability in cortical neurons that would increase the susceptibility for cortical spreading depression (CSD), a mechanism believed to initiate the attacks of migraine with aura.

Hemiconvulsion-hemiplegia-epilepsy syndrome associated with CACNA1A S218L mutation

Hemiconvulsion-hemiplegia-epilepsy syndrome involves sudden and prolonged unilateral seizures, followed by transient or permanent hemiplegia and epilepsy during infancy or early childhood. Some patients with familial hemiplegic migraine and demonstrating the S218L mutation in CACNA1A experience severe attacks with unilateral cerebral edema after trivial head trauma. We report on a 5-year-old Japanese girl presenting with hemiconvulsion-hemiplegia-epilepsy syndrome after infection with parvovirus B19. Magnetic resonance imaging performed 2 days after admission revealed cerebellar atrophy and marked hyperintensity in the left hemisphere on T(2)-weighted and diffusion-weighted imaging. Magnetic resonance angiography performed 7 days after admission demonstrated obliteration of the left proximal middle cerebral artery in the acute phase. However, this finding was not evident on brain angiography performed 25 hours after magnetic resonance angiography. Genetic analysis of familial hemiplegic migraine revealed a heterozygous S218L mutation in CACNA1A. Taken together, these results suggest that vasospasms of cerebral vascular smooth muscle, with possible cortical spreading depression, may have caused the hemiconvulsions and hemiplegia in the left hemisphere. This case report is the first, to the best of our knowledge, to associate CACNA1A with hemiconvulsion-hemiplegia-epilepsy syndrome and familial hemiplegic migraine, and to suggest that similar pathogenic mechanisms may underlie these two disorders.

Trigger factors for familial hemiplegic migraine

Objective: The aim was to identify and describe migraine trigger factors in patients with familial hemiplegic migraine (FHM) from a population-based sample.

Methods: 127 FHM patients were sent a questionnaire listing 16 trigger factors. Distinction was made between attacks of hemiplegic migraine (HM) and migraine with aura (MA) or without aura (MO) within each patient.

Results: The response rate was 59% (75/127) of whom 57 (76%) had current HM attacks. Sixty-three per cent (47/75) reported at least one factor triggering HM, and 36% (27/75) reported at least one factor that often or always caused HM. Twenty per cent (15/75) reported only HM, whereas FHM in combinations with MA and MO were reported by 80% (60/75). Stress (with attacks either following or during the stress), bright light, intense emotional influences and sleeping too much or too little were the trigger factors mentioned by most.

Conclusion: Many FHM patients report trigger factors and one-third reported at least one trigger factor often or always triggering FHM. The typical triggers are the same as for MA. Patients should be educated to avoid these factors. The role of trigger factors in the onset of new or first attacks of FHM remains unknown.

Head tremor related to CACNA1A mutations

Introduction: Familial hemiplegic migraine (FHM) is characterized by the familial occurrence of migraine attacks with fully reversible transient hemiplegia. Mutations in three different genes have been identified; CACNA1A (FHM1), ATP1A2 (FHM2) and SCN1A (FHM3). Besides hemiplegia, several other symptoms have been described in FHM 1–3 mutation carriers, including epilepsy and cerebellar symptoms.

Case report: We describe two patients in whom hemiplegic attacks were not the presenting symptom, but in whom an otherwise unexplained head tremor led us to search for FHM mutations. Both patients carried a mutation in the CACNA1A gene.

Discussion: CACNA1A mutations can give significant symptoms other than (hemiplegic) migraine as reason for presentation.

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.

Genetic diagnosis and acetazolamide treatment of familial hemiplegic migraine

A female patient presented with horizontal gaze nystagmus, mild cerebellar ataxia, recurrent headache and hemiplegia since childhood with cerebellar atrophy on magnetic resonance imaging. Genetic analysis revealed a CACNA1A gene mutation, leading to a diagnosis of familial hemiplegic migraine (FHM1). FHM is very rare, but should be considered as a differential diagnosis for childhood cerebellar symptoms and/or cerebellar atrophy. To avoid missing FHM1, a detailed clinical history including headache or hemiplegia is essential. Oral acetazolamide during the aura phase, comprising mild headache and abnormal leg sensation, relieved these symptoms in this patient, suggesting that acetazolamide could represent a first line of treatment.

Overview of diagnosis and management of paediatric headache. Part I: diagnosis

Headache is the most common somatic complaint in children and adolescents. The evaluation should include detailed history of children and adolescents completed by detailed general and neurological examinations. Moreover, the possible role of psychological factors, life events and excessively stressful lifestyle in influencing recurrent headache need to be checked. The choice of laboratory tests rests on the differential diagnosis suggested by the history, the character and temporal pattern of the headache, and the physical and neurological examinations. Subjects who have any signs or symptoms of focal/progressive neurological disturbances should be investigated by neuroimaging techniques. The electroencephalogram and other neurophysiological examinations are of limited value in the routine evaluation of headaches. In a primary headache disorder, headache itself is the illness and headache is not attributed to any other disorder (e.g. migraine, tension-type headache, cluster headache and other trigeminal autonomic cephalgias). In secondary headache disorders, headache is the symptom of identifiable structural, metabolic or other abnormality. Red flags include the first or worst headache ever in the life, recent headache onset, increasing severity or frequency, occipital location, awakening from sleep because of headache, headache occurring exclusively in the morning associated with severe vomiting and headache associated with straining. Thus, the differential diagnosis between primary and secondary headaches rests mainly on clinical criteria. A thorough evaluation of headache in children and adolescents is necessary to make the correct diagnosis and initiate treatment, bearing in mind that children with headache are more likely to experience psychosocial adversity and to grow up with an excess of both headache and other physical and psychiatric symptoms and this creates an important healthcare problem for their future life.

Neurological channelopathies

Inherited ion channel mutations can affect the entire nervous system. Many cause paroxysmal disturbances of brain, spinal cord, peripheral nerve or skeletal muscle function, with normal neurological development and function in between attacks. To fully understand how mutations of ion channel genes cause disease, we need to know the normal location and function of the channel subunit, consequences of the mutation for biogenesis and biophysical properties, and possible compensatory changes in other channels that contribute to cell or circuit excitability. Animal models of monogenic channelopathies increasingly help our understanding. An important challenge for the future is to determine how more subtle derangements of ion channel function, which arise from the interaction of genetic and environmental influences, contribute to common paroxysmal disorders, including idiopathic epilepsy and migraine, that share features with rare monogenic channelopathies.

Sporadic hemiplegic migraine with seizures and transient MRI abnormalities

Hemiplegic migraines are characterised by attacks of migraine with aura accompanied by transient motor weakness. There are both familial and sporadic subtypes, which are now recognised as separate entities by the International Classification of Headache Disorders, edition II (ICHD-II). Sporadic hemiplegic migraine is a rare variant of migraine, We report a case of sporadic hemiplegic migraine and seizures with MRI features suggestive of cortical hyper intensity and edema on T2 and FLAIR images with no restriction pattern on diffusion and these changes completely resolving over time, suggesting that these changes are due prolonged neuronal depolarization and not of ischemic origin.

A novel mutation in CACNA1A associated with hemiplegic migraine, cerebellar dysfunction and late-onset cognitive decline

Hemiplegic migraine (HM) is a rare and severe subtype of migraine with aura, characterized by some degree of hemiparesis and other aura symptoms. Mutations in three genes (CACNA1A, ATP1A2 and SCN1A) have been detected in familial and, more rarely, in sporadic cases. The disease can be complicated by permanent neurological deficits, the most frequent one being a cerebellar syndrome; in addition, mental retardation has been recognized as part of the phenotypic spectrum. Here, we report a Caucasian male with a novel CACNA1A mutation and an unusual clinical phenotype: the patient, who had had a history of only two HM attacks, sought medical advice at age 49 primarily because of increasing cognitive decline accompanied by cerebellar dysfunction. While common neurodegenerative causes were excluded, neuropsychological evaluation revealed a distinct profile of deficits of a subcortico-prefrontal type as previously reported in patients with cerebellar dysfunction. This suggests a possible causal link between cerebellar and cognitive disturbances in this patient; in addition to these pathophysiological aspects, we review of the role of the cerebellum in cognition.

Contribution of calcium-dependent facilitation to synaptic plasticity revealed by migraine mutations in the P/Q-type calcium channel

The dynamics, computational power, and strength of neural circuits are essential for encoding and processing information in the CNS and rely on short and long forms of synaptic plasticity. In a model system, residual calcium (Ca(2+)) in presynaptic terminals can act through neuronal Ca(2+) sensor proteins to cause Ca(2+)-dependent facilitation (CDF) of P/Q-type channels and induce short-term synaptic facilitation. However, whether this is a general mechanism of plasticity at intact central synapses and whether mutations associated with human disease affect this process have not been described to our knowledge. In this report, we find that, in both exogenous and native preparations, gain-of-function missense mutations underlying Familial Hemiplegic Migraine type 1 (FHM-1) occlude CDF of P/Q-type Ca(2+) channels. In FHM-1 mutant mice, the alteration of P/Q-type channel CDF correlates with reduced short-term synaptic facilitation at cerebellar parallel fiber-to-Purkinje cell synapses. Two-photon imaging suggests that P/Q-type channels at parallel fiber terminals in FHM-1 mice are in a basally facilitated state. Overall, the results provide evidence that FHM-1 mutations directly affect both P/Q-type channel CDF and synaptic plasticity and that together likely contribute toward the pathophysiology underlying FHM-1. The findings also suggest that P/Q-type channel CDF is an important mechanism required for normal synaptic plasticity at a fast synapse in the mammalian CNS.

Cognitive functions, emotional behavior, and quality of life in familial hemiplegic migraine

OBJECTIVES

To describe the cognitive functions, mood, and quality of life in a family with genetically proved familial hemiplegic migraine (FHM), carrying a missense mutation on chromosome 19 (T666M), corresponding to the most frequent FHM subtype.

BACKGROUND

FHM is an autosomal dominant subtype of migraine with an aura, characterized by hemiparesis during the aura. Whereas the genetic background of FHM has been studied intensely, less attention has been paid to cognitive functions and mood between attacks.

METHOD

Six patients performed neuropsychologic assessment between attacks. Depression, anxiety, and quality of life were evaluated by questionnaires. Cerebral magnetic resonance imaging was performed.

RESULTS

Neuropsychologic assessment revealed a distinct pattern of preserved and impaired functions. Whereas linguistic abilities and verbal memory were intact, all patients showed deficits in figural memory, executive functions, in some aspects of attention, and in dexterity. Intelligence of 1 patient was below average. All but 1 patient reported normal quality of life; there were no symptoms of depression or state anxiety. All patients showed cerebellar atrophy and cerebellar ataxia.

CONCLUSION

Cognitive abnormalities and cerebellar atrophy were found in all patients. FHM-related cognitive deficits may be associated to a disturbance of cerebrocerebellar circuits.

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.

Defective membrane expression of the Na(+)-HCO(3)(-) cotransporter NBCe1 is associated with familial migraine

Homozygous mutations in SLC4A4, encoding the electrogenic Na(+)-HCO(3)(-) cotransporter NBCe1, have been known to cause proximal renal tubular acidosis (pRTA) and ocular abnormalities. In this study, we report two sisters with pRTA, ocular abnormalities, and hemiplegic migraine. Genetic analysis ruled out pathological mutations in the known genes for familial hemiplegic migraine, but identified a homozygous 65-bp deletion (Delta65bp) in the C terminus of NBCe1, corresponding to the codon change S982NfsX4. Several heterozygous members of this family also presented glaucoma and migraine with or without aura. Despite the normal electrogenic activity in Xenopus oocytes, the Delta65bp mutant showed almost no transport activity due to a predominant cytosolic retention in mammalian cells. Furthermore, coexpression experiments uncovered a dominant negative effect of the mutant through hetero-oligomer formation with wild-type NBCe1. Among other pRTA pedigrees with different NBCe1 mutations, we identified four additional homozygous patients with migraine. The immunohistological and functional analyses of these mutants demonstrate that the near total loss of NBCe1 activity in astrocytes can cause migraine potentially through dysregulation of synaptic pH.

Congenital ataxia, mental retardation, and dyskinesia associated with a novel CACNA1A mutation

The CACNA1A gene encodes the pore forming alpha-1A subunit of neuronal voltage-dependent P/Q-type Ca( 2+) channels. Mutations in this gene result in clinical heterogeneity, and present with either chronic progressive symptoms, paroxysmal events, or both, with clinical overlap among the different phenotypes. The authors describe a seven year-old boy with mental retardation and congenital cerebellar ataxia that developed dyskinesia at the age of a few months, and recurrent episodes of coma following mild head trauma associated with motor and autonomic signs, from the second year of life. An extensive metabolic evaluation, interictal electroencephalography (EEG), and muscle biopsy were normal. Brain magnetic resonance imaging (MRI) during one of these episodes revealed edema of the right hemisphere and cerebellar atrophy. Genetic testing revealed a R1350Q mutation in the CACNA1A gene. This is a novel de novo mutation.Congenital cerebellar ataxia can be a result of CACNA1A mutations, especially when associated with recurrent unexplained coma.

Calcium channel "gaiting" and absence epilepsy

Dysfunction of the Brain Calcium Channel Cav2.1 in Absence Epilepsy and Episodic Ataxia

Imbrici P, Jaffe SL, Eunson LH, Davies NP, Herd C, Robertson R, Kullmann DM, Hanna MG

Brain 2004;127(Pt 12):2682–2692

The molecular basis of idiopathic generalized epilepsy remains poorly understood. Absence epilepsy with 3-Hz spike–wave EEG is one of the most common human epilepsies and is associated with significant morbidity. Several spontaneously occurring genetic mouse models of absence epilepsy are caused by dysfunction of the P/Q-type voltage-gated calcium channel CaV2.1. Such mice exhibit a primary generalized spike–wave EEG, with frequencies in the range of 5 to 7 Hz, often associated with ataxia, evidence of cerebellar degeneration and abnormal posturing. Previously, we identified a single case of severe primary generalized epilepsy with ataxia associated with CaV2.1 dysfunction, suggesting a possible link between this channel and human absence epilepsy. We now report a family in which absence epilepsy segregates in an autosomal dominant fashion through three generations. Five members exhibit a combination of absence epilepsy (with 3-Hz spike–wave) and cerebellar ataxia. In patients with the absence epilepsy/ataxia phenotype, genetic marker analysis was consistent with linkage to the CACNA1A gene on chromosome 19, which encodes the main pore-forming α1A subunit of CaV2.1 channels (CaV2.1 α1). DNA sequence analysis identified a novel point mutation resulting in a radical amino acid substitution (E147K) in CaV2.1 α1, which segregated with the epilepsy/ataxia phenotype. Functional expression studies using human CACNA1A cDNA demonstrated that the E147K mutation results in impairment of calcium channel function. Impaired function of the brain calcium channel CaV2.1 may have a central role in the pathogenesis of certain cases of primary generalized epilepsy, particularly when associated with ataxia, which may be wrongly ascribed to anticonvulsant medication.

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.

CaV2.1 channelopathies

Mutations in the CACNA1A gene that encodes the pore-forming alpha1 subunit of human voltage-gated CaV2.1 (P/Q-type) Ca2+ channels cause several autosomal-dominant neurologic disorders, including familial hemiplegic migraine type 1 (FHM1), episodic ataxia type 2, and spinocerebellar ataxia type 6 (SCA6). For each channelopathy, the review describes the disease phenotype as well as the functional consequences of the disease-causing mutations on recombinant human CaV2.1 channels and, in the case of FHM1 and SCA6, on neuronal CaV2.1 channels expressed at the endogenous physiological level in knockin mouse models. The effects of FHM1 mutations on cortical spreading depression, the phenomenon underlying migraine aura, and on cortical excitatory and inhibitory synaptic transmission in FHM1 knockin mice are also described, and their implications for the disease mechanism discussed. Moreover, the review describes different ataxic spontaneous cacna1a mouse mutants and the important insights into the cerebellar mechanisms underlying motor dysfunction caused by mutant CaV2.1 channels that were obtained from their functional characterization.

Capillary endothelial Na(+), K(+), ATPase transporter homeostasis and a new theory for migraine pathophysiology

BACKGROUND

Cerebrospinal fluid sodium concentration ([Na(+)](csf)) increases during migraine, but the cause of the increase is not known.

OBJECTIVE

Analyze biochemical pathways that influence [Na(+)](csf) to identify mechanisms that are consistent with migraine.

METHOD

We reviewed sodium physiology and biochemistry publications for links to migraine and pain.

RESULTS

Increased capillary endothelial cell (CEC) Na(+), K(+), -ATPase transporter (NKAT) activity is probably the primary cause of increased [Na(+)](csf). Physiological fluctuations of all NKAT regulators in blood, many known to be involved in migraine, are monitored by receptors on the luminal wall of brain CECs; signals are then transduced to their abluminal NKATs that alter brain extracellular sodium ([Na(+)](e)) and potassium ([K(+)](e)).

CONCLUSIONS

We propose a theoretical mechanism for aura and migraine when NKAT activity shifts outside normal limits: (1) CEC NKAT activity below a lower limit increases [K(+)](e), facilitates cortical spreading depression, and causes aura; (2) CEC NKAT activity above an upper limit elevates [Na(+)](e), increases neuronal excitability, and causes migraine; (3) migraine-without-aura may arise from CEC NKAT over-activity without requiring a prior decrease in activity and its consequent spreading depression; (4) migraine triggers disturb, and treatments improve, CEC NKAT homeostasis; (5) CEC NKAT-induced regulation of neural and vasomotor excitability coordinates vascular and neuronal activities, and includes occasional pathology from CEC NKAT-induced apoptosis or cerebral infarction.

Identification of novel and recurrent CACNA1A gene mutations in fifteen patients with episodic ataxia type 2

Episodic ataxia type 2 is a rare autosomal dominant disease characterized by recurrent attacks of vertigo and cerebellar ataxia. The disease was caused by mutations in the CACNA1A gene, on chromosome 19p. We perform a mutational screening in a group of 43 unrelated patients. Forty-two patients presented episodes of disequilibrium and ataxia, and one child was studied because of the occurrence of episodic torticollis. The genetic analysis showed 15 mutated patients (35%). In 13 cases we found novel CACNA1A gene mutations, including missense, protein truncating, and aberrant splicing mutations. Two truncating mutations lead to the uppermost premature stop so far reported, challenging recent hypotheses on dominant negative effect. In patients without CACNA1A mutations, molecular testing for CACNB4 gene mutations excluded this genetic subtype. Clinical features of mutated subjects mostly confirmed previous sign and symptoms associated with EA2, including paroxysmal torticollis and mental retardation. CACNA1A mutated patients have an earlier age at onset, interictal nystagmus, and abnormalities of ocular movements. A review of all CACNA1A mutations so far reported showed that they are mainly located downstream exon 18. Our data substantially increase the number of the described CACNA1A mutations, and propose clinical and molecular criteria for a more focused genetic screening.

Sporadic hemiplegic migraine and epilepsy associated with CACNA1A gene mutation

Familial hemiplegic migraine (FHM) is a clinically and genetically heterogeneous disease most commonly linked to CACNA1A gene mutation. Epilepsy rarely occurs in FHM and is seen predominantly with specific CACNA1A gene mutations. Here we report a sporadic case of FHM1 linked to S218L CACNA1A gene mutation with the triad of prolonged hemiplegic migraine, cerebellar symptoms, and epileptic seizures. Epilepsy in this syndrome follows the pattern of isolated unprovoked seizures occurring only during childhood and hemiplegic migraine-provoked seizures occurring during adulthood. Clinical and electrographic status epilepticus can occur during prolonged migraine attacks. We suggest that patients with seizures, ataxia, and hemiplegic migraine be genetically tested for FHM. Patients with prolonged hemiplegic migraine attacks and confusion should be tested with continuous EEG recording to ascertain whether electrographic status is occurring, as intensive antiepileptic treatment not only resolves status but immediately stops hemiplegic migraine and improves associated neurological deficits.

A mutation in the first intracellular loop of CACNA1A prevents P/Q channel modulation by SNARE proteins and lowers exocytosis

Familial hemiplegic migraine (FHM)-causing mutations in the gene encoding the P/Q Ca(2+) channel alpha(1A) subunit (CACNA1A) locate to the pore and voltage sensor regions and normally involve gain-of-channel function. We now report on a mutation identified in the first intracellular loop of CACNA1A (alpha(1A(A454T))) that does not cause FHM but is associated with the absence of sensorimotor symptoms in a migraine with aura pedigree. Alpha(1A(A454T)) channels showed weakened regulation of voltage-dependent steady-state inactivation by Ca(V)beta subunits. More interestingly, A454T mutation suppressed P/Q channel modulation by syntaxin 1A or SNAP-25 and decreased exocytosis. Our findings reveal the importance of I-II loop structural integrity in the functional interaction between P/Q channel and proteins of the vesicle-docking/fusion machinery, and that genetic variation in CACNA1A may be not only a cause but also a modifier of migraine phenotype.