A review of the genetic relation between migraine and epilepsy

A possible relation between migraine and epilepsy has been a matter of debate for many decades. Clinical, epidemiological and therapeutic similarities may be coincidental and are no proof of a common aetiological background. However, a genetically determined dysfunction of ion channels seems to point to a common underlying mechanism for both paroxysmal disorders. For example, mutations in the three known genes for familial hemiplegic migraine can cause epilepsy. It is likely that the development of specific drugs aimed at restoring ion-channel function and/or related cellular signalling pathways might benefit patients with epilepsy as well as those with migraine. This review will briefly summarize the clinical, epidemiological, pathophysiological and therapeutic similarities between migraine and epilepsy. Most attention will be paid to the genetic relationship between these two paroxysmal disorders.

[Trigeminal autonomic cephalalgias: three forms of unilateral, short-lasting headache with facial autonomic symptoms]

--Trigeminal autonomic cephalalgias (TACs) include cluster headache, paroxysmal hemicranias and short-lasting unilateral neuralgiform headache attacks with conjunctival injection and tearing (SUNCTs). --Because they are rare, it is often difficult to recognise TACs in practice. Hallmarks of TACs include the strictly unilateral pain near the eye or temple, the accompanying autonomic symptoms, and the specific pattern in the timing of the attacks. --The TAC subtypes differ in the duration and frequency of attacks. Differentiating TAC subtypes is important because it affects the treatment approach. --In rare cases, TAC results from an underlying structural disorder. Neuroimaging (cerebral MRI) is advised in all patients with TAC.

Systematic analysis of three FHM genes in 39 sporadic patients with hemiplegic migraine

BACKGROUND

Familial (FHM) and sporadic (SHM) hemiplegic migraine are severe subtypes of migraine associated with transient hemiparesis. For FHM, three genes have been identified encoding subunits of a calcium channel (CACNA1A), a sodium-potassium pump (ATP1A2), and a sodium channel (SCN1A). Their role in SHM is unknown. Establishing a genetic basis for SHM may further the understanding of its pathophysiology and relationship with common types of migraine. It will also facilitate the often difficult differential diagnosis from other causes of transient hemiparesis.

METHODS

We systematically scanned 39 well-characterized patients with SHM without associated neurologic features for mutations in the three FHM genes. Functional assays were performed for all new sequence variants.

RESULTS

Sequence variants were identified in seven SHM patients: one CACNA1A mutation, five ATP1A2 mutations, and one SCN1A polymorphism. All six mutations caused functional changes in cellular assays. One SHM patient later changed to FHM because another family member developed FHM attacks.

CONCLUSION

We show that FHM genes are involved in at least a proportion of SHM patients without associated neurologic symptoms. Screening of ATP1A2 offers the highest likelihood of success. Because FHM gene mutations were also found in family members with "nonhemiplegic" typical migraine with and without aura, our findings reinforce the hypothesis that FHM, SHM, and "normal" migraine are part of a disease spectrum with shared pathogenetic mechanisms.

[Migraine and cardiovascular risk]

New epidemiological studies suggest a relationship between migraine (especially migraine with aura) and cardiovascular disease. However, the absolute risk of cardiovascular disease for migraine patients is still low even though the relative risk is 2-4-fold higher. Further research will have to show whether migraine is an independent risk factor for cardiovascular disease and whether prophylactic treatment of migraine attacks will lower this increased risk for cardiovascular disease.

C-terminal truncations in human 3′-5′ DNA exonuclease TREX1 cause autosomal dominant retinal vasculopathy with cerebral leukodystrophy

Autosomal dominant retinal vasculopathy with cerebral leukodystrophy is a microvascular endotheliopathy with middle-age onset. In nine families, we identified heterozygous C-terminal frameshift mutations in TREX1, which encodes a 3'-5' exonuclease. These truncated proteins retain exonuclease activity but lose normal perinuclear localization. These data have implications for the maintenance of vascular integrity in the degenerative cerebral microangiopathies leading to stroke and dementias.

The novel p.L1649Q mutation in the SCN1A epilepsy gene is associated with familial hemiplegic migraine: genetic and functional studies. Mutation in brief #957. Online

Familial hemiplegic migraine (FHM) is a severe subtype of migraine with hemiparesis during attacks. We scanned 10 families with FHM without mutations in the CACNA1A (FHM1) and ATP1A2 (FHM2) genes. We identified the novel p.L1649Q mutation (c.4946T>A) in Na(v)1.1 sodium channel gene SCN1A (FHM3) in a North American kindred with FHM without associated ataxia or epilepsy. Functional analysis of the mutation, introduced in the highly homologous human SCN5A, revealed markedly slowed inactivation and a two-fold faster recovery from fast inactivation predicting enhanced neuronal excitation. Our findings establish the role of neuronal Na(v)1.1 sodium channels in FHM and reinforce the involvement of ion channel dysfunction in the pathogenesis of this episodic brain disorder.

Migraine: gene mutations and functional consequences

PURPOSE OF REVIEW

Genetic and functional studies of mutations in familial hemiplegic migraine reveal a major role for disturbed ion transport. Gene identification in common, multifactorial migraine remains challenging.

RECENT FINDINGS

Several new mutations have been identified in FHM1, FHM2 and FHM3 genes. Functional consequences of familial hemiplegic migraine mutations point to an important role for cortical spreading depression in migraine pathophysiology. New genetic approaches have been tested in common migraine - novel chromosomal loci - but no gene variants have been identified.

SUMMARY

Identification and analysis of gene mutations in familial hemiplegic migraine revealed a major role for disturbed ion transport in this disorder. Cellular and transgenic mouse models of familial hemiplegic migraine genes suggest that increased potassium and glutamate play a role in the pathophysiology of the disorder. Despite progress, no genes have been discovered for common migraine.

First case of compound heterozygosity in Na,K-ATPase gene ATP1A2 in familial hemiplegic migraine

Familial hemiplegic migraine (FHM) is a rare autosomal-dominant subtype of migraine with aura, associated with hemiparesis during the aura. Here we describe a unique FHM family in which two novel allelic missense mutations in the Na,K-ATPase gene ATP1A2 segregate in the proband with hemiplegic migraine. Both mutations show reduced penetrance in family members of the proband. Cellular survival assays revealed Na,K-ATPase dysfunction for both ATP1A2 mutants, indicating that both mutations are disease causative. This is the first case of compound heterozygosity for any of the known FHM genes.

Typical cluster headache caused by granulomatous pituitary involvement

A young woman had typical cluster headache attacks and a pituitary mass lesion. The headache attacks resolved after transsphenoidal resection of the tumour, which was diagnosed as a granulomatous inflammation. The association between cluster headache and granulomatous enlargement of the pituitary gland has never been described before. This case reinforces the growing evidence that even in typical cases of cluster headache, neuroimaging is mandatory to exclude structural lesions.

Lacunar Infarcts Are the Main Correlate With Cognitive Dysfunction in CADASIL

Background and Purpose— Cerebral autosomal dominant arteriopathy with subcortical infarcts and leukoencephalopathy is caused by mutations in the NOTCH3 gene and is clinically characterized by recurrent stroke and cognitive decline. Previous studies have shown an association between white matter hyperintensities on brain MRI and cognitive dysfunction in cerebral autosomal dominant arteriopathy with subcortical infarcts and leukoencephalopathy. In the general population the presence of lacunar infarcts and microbleeds is also associated with cognitive dysfunction. The objective of this study was to determine to what extent lacunar infarcts and microbleeds on MRI contribute to cognitive decline in cerebral autosomal dominant arteriopathy with subcortical infarcts and leukoencephalopathy.

Methods— NOTCH3 mutation analysis was performed in 62 symptomatic and asymptomatic members of 15 cerebral autosomal dominant arteriopathy with subcortical infarcts and leukoencephalopathy families. Neuropsychological tests were performed on the same day as the MRI examination. MRI was semi-quantitatively scored for white matter hyperintensities, infarct lesion load, and microbleeds. Regression analysis was performed to test the association between MRI abnormalities and neuropsychological test results.

Results— Forty individuals had a NOTCH3 mutation and 22 did not. Severity of cognitive dysfunction in mutation carriers was independently associated with MRI infarct lesion load ( P <0.05). In contrast, WMH lesion load and microbleeds were not associated with cognitive dysfunction after correcting for age.

Conclusions— Lacunar infarct lesion load is the most important MRI parameter associated with cognitive dysfunction in cerebral autosomal dominant arteriopathy with subcortical infarcts and leukoencephalopathy.

A review of genetic causes of ischemic and hemorrhagic stroke

Genetic predisposition to stroke has been proven in animal models and in humans. Unraveling the genetic factors that play a role in common stroke is very difficult, as the causation of stroke is multifactorial (a combination of environmental and genetic risk factors) and the genetic part is very complex (polygenic, multiple genes play a role). Many common risk factors for stroke like diabetes and arterial hypertension are partly inherited, so many genetic loci contribute more or less to the stroke phenotype. Recent knowledge is increased for monogenic forms of stroke, such as cerebral autosomal dominant arteriopathy with subcortical infarcts and leukoencephalopathy and the amyloid angiopathies. These disorders can serve as models to study environmental or genetic factors that contribute also to the common forms of stroke. Animal model of stroke can also provide valuable information on genetic factors involved in stroke predisposition. In this review, the focus lies on monogenic forms of stroke that can serve as models to study the more common phenotypes.

Trigeminal Autonomic Cephalgias Due to Structural Lesions

Trigeminal autonomic cephalgias (TACs) include cluster headache, paroxysmal hemicrania, and short-lasting unilateral neuralgiform headache with conjunctival injection and tearing. Associated structural lesions may be found, but a causal relationship is often difficult to establish. We sought to identify clinical predictors of underlying structural abnormalities by reviewing previously described and new TAC and TAC-like cases associated with a structural lesion. We found that even typical TACs can be caused by an underlying lesion. Clinical warning signs and symptoms are relatively rare. We recommend neuroimaging in all patients with a TAC or TAC-like syndrome.

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.

Alternating hemiplegia of childhood: no mutations in the glutamate transporter EAAT1

Alternating hemiplegia of childhood (AHC) is a severe brain disorder, mainly characterised by episodes of hemiplegia, progressive mental retardation, and other severe paroxysmal and permanent neurological symptoms. Clinically and genetically, there is some overlap with sporadic (SHM) and familial (FHM) hemiplegic migraine, a severe monogenic subtype of migraine. Although no mutations were detected in the FHM1 CACNA1A and FHM2 ATP1A2 genes in sporadic AHC patients, a mutation was found in the FHM2 ATP1A2 gene in a family with AHC. Recently, a missense mutation was found in the SLC1A3 gene that encodes the glutamate transporter EAAT1, in a patient with alternating hemiplegia, episodic ataxia, seizures, and headache. Because of the remarkable clinical similarities and the potential role of glutamate in AHC, we analysed six sporadic patients with AHC for mutations in the SLC1A3 gene. No mutations were found. The SLC1A3 EAAT1 glutamate transporter gene does not seem to be involved in the pathogenesis of AHC.

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.

['Migraine and a hole in the heart': causal relationship between migraine and patent foramen ovale not established]

The relationship between patent foramen ovale (PFO) and migraine is controversial. A common genetic background seems possible, but there is no evidence for a causal relationship. Despite the lack of evidence, PFO closure is recommended in many countries as a remedy for migraine. At present, PFO closure for migraine should only be carried out under strictly controlled clinical trial conditions.

Cluster headache in women: relation with menstruation, use of oral contraceptives, pregnancy, and menopause

In contrast with migraine, little is known about the relation between cluster headache and menstrual cycle, oral contraceptives, pregnancy, and menopause. A population based questionnaire study was performed among 224 female cluster headache patients, and the possible effect of hormonal influences on cluster headache attacks studied. For control data, a similar but adjusted questionnaire was sent to healthy volunteers and migraine patients. It was found that menstruation, use of oral contraceptives, pregnancy, and menopause had a much smaller influence on cluster headache attacks than in migraine. Cluster headache can, however, have a large impact on individual women, for example to refrain from having children.

Migraine: new treatment options from molecular biology

Migraine is a common, disabling, multifactorial, episodic neurovascular disorder of largely unknown etiology. The disease is typically characterized by recurrent attacks of headaches and associated autonomic and neurologic symptoms. Current acute and prophylactic treatment options are far from optimal and in many cases, empirically chosen. Clearly, improved treatment is desperately needed. New drug targets may emerge from molecular research as the unravelling of the molecular basis of migraine should improve our understanding of the disease, notably why patients experience attacks so frequently. The first two migraine genes discovered in families with hemiplegic migraine encode ion transporters, emphasising that dysfunction of ion transport may be an important factor in migraine. Therefore, ion transporters can be considered as novel targets for the development of future antimigraine drugs. Molecular biologic research will increasingly become important in understanding the pathophysiology of migraine and in identifying potential molecular targets for novel treatments.

Microbleeds in hereditary cerebral hemorrhage with amyloidosis-Dutch type

In a hereditary variant of cerebral amyloid angiopathy (CAA), cerebral hemorrhage with amyloidosis-Dutch type, supratentorial microbleeds were found to occur independently of the presence of hypertension, whereas hypertension probably contributed to the development of cerebellar microbleeds. This predictable hereditary variant of CAA may be a useful model to study microbleeds in relation to CAA.

Cerebral autosomal dominant arteriopathy with subcortical infarcts and leukoencephalopathy: structural MR imaging changes and apolipoprotein E genotype

BACKGROUND AND PURPOSE

Apolipoprotein E (apoE) genotype plays an important role in the development, maintenance, and response to injury of the central nervous system. It has been suggested that apoE epsilon4 genotype is a risk factor for several neurologic disorders. We investigated the correlation between the apoE genotype and radiologic data in patients with cerebral autosomal dominant arteriopathy with subcortical infarcts and leukoencephalopathy (CADASIL).

METHODS

T1-weighted, dual fast spin-echo, T2*-weighted gradient echo, and fluid-attenuated inversion recovery MR imaging scans were obtained from 36 CADASIL patients (21-59 years of age). The number of lacunar infarcts and microbleeds and the presence of subcortical lacunar lesions were determined. The amount of white matter hyperintensities was assessed by using semiautomated segmentation software. The relation between the radiologic endophenotype of CADASIL and the apoE genotype was assessed by using a Student t test for unpaired data and Fisher exact test.

RESULTS

White matter hyperintensities, lacunar infarcts, microbleeds, and subcortical lacunar lesions were not found to be associated with the presence of an epsilon4 allele.

CONCLUSION

The variability of structural MR imaging lesions in CADASIL is independent of apoE genotype and other processes must underlie the variable natural history of the disease.

Severe episodic neurological deficits and permanent mental retardation in a child with a novel FHM2ATP1A2mutation

OBJECTIVE

Attacks of familial hemiplegic migraine (FHM) are usually associated with transient, completely reversible symptoms. Here, we studied the ATP1A2 FHM2 gene in a young girl with episodes of both very severe and transient neurological symptoms that were triggered by mild head trauma as well as permanent mental retardation. Her family members suffered from hemiplegic and confusional migraine attacks.

METHODS

Mutation analysis of the ATP1A2 gene was performed by direct sequencing of all exons and flanking intronic regions, using genomic DNA of the proband. Functional consequences of the mutation were analyzed by cellular survival assays.

RESULTS

We identified a novel G615R ATP1A2 mutation in the proband and several of her family members. Functional analysis of mutant Na,K-ATPase in cellular survival assays showed a complete loss-of-function effect.

INTERPRETATION

Permanent mental retardation in children may be caused by ATP1A2 mutations.

Chronic cluster headache: a review

Cluster headache (CH) is a rare but severe headache disorder characterised by repeated unilateral head pain attacks accompanied by ipsilateral autonomic features. In episodic CH, there are periods of headache attacks with pain-free intervals of weeks, months or years in between. A minority of patients have the chronic form, without pain-free intervals between the headache attacks. Chronic CH can occur as primary or secondary chronic CH; the rarest form is episodic CH arising from chronic CH. In this article, we give a review of the chronic forms of CH and focus on demographics, clinical manifestations, social habits, predictive factors, head injury, genetics, neuroimaging and therapy. It is remarkable that little is known about risk factors that make CH chronic.

Cerebral autosomal dominant arteriopathy with subcortical infarcts and leukoencephalopathy (CADASIL)

Cerebral autosomal dominant arteriopathy with subcortical infarcts and leukoencephalopathy (CADASIL) is an adult-onset hereditary syndrome characterized by recurrent TIAs and strokes, cognitive decline and dementia, migraine with aura (+/-40% of patients), and psychiatric disturbances (+/-30% of patients). Affected individuals have prominent signal abnormalities on brain MRI. Symmetrical white matter abnormalities are invariably seen and often small subcortical infarcts are also present. The extent of the MRI lesions increases with age, from subtle white matter abnormalities in the anterior temporal poles in the early 20 years to confluent white matter lesions with subcortical infarcts and microbleeds in the 6(th) decade. A typical arteriopathy with electron dense granular depositions in the media of small cerebral arteries underlies this disorder. These arterial lesions can be found, to a lesser extent, in extra-cerebral arteries such as skin arterioles. In 1996, the defective gene in CADASIL was discovered to be NOTCH3. NOTCH3 encodes a 300-kd transmembrane protein with a receptor and cell signal transduction function. Mutations are almost always missense mutations causing the loss or gain of a cysteine residue and are detected in over 90% of patients. How alterations in NOTCH3 lead to the CADASIL phenotype has yet to be elucidated.

Alternating hemiplegia of childhood: no mutations in the second familial hemiplegic migraine gene ATP1A2

Alternating hemiplegia of childhood (AHC) is a rare disorder mainly characterised by attacks of hemiplegia and mental retardation. AHC has often been associated with migraine. Previously, we have excluded the involvement of the familial hemiplegic migraine (FHM) CACNA1A gene in four patients with AHC. A second gene for FHM was discovered recently: the ATP1A2 gene on chromosome 1q23, coding for the alpha 2 subunit of Na+,K+-ATPase. We performed a mutation analysis of the ATP1A2 gene in six patients, using direct sequencing, but found no mutations in any of the 23 exons. Other cerebral ion channel genes remain candidate genes for AHC.

[From gene to disease; familial hemiplegic migraine as a result of mutations in a sodium-potassium pump gene]

Familial hemiplegic migraine (FHM) is a rare, autosomal dominant subtype of migraine, associated in half of the families with mutations in the CACNA1A gene located on chromosome 19p13, which encodes the Cav2.1-subunit of brain-specific P/Q-type calcium channels. Recently, mutations in a second gene, ATP1A2 on chromosome 1q23, which encodes a sodium-potassium exchange pump subunit, have been identified. The first functional studies indicate that A TP1A2 FHM mutations result in a loss of function of the pump, leading to an increase in extracellular potassium. This is known to evoke cortical spreading depression, the underlying mechanism of migraine aura.

Recent findings in headache genetics

PURPOSE OF REVIEW

The progress in headache genetics, especially migraine genetics, recently jumped ahead with some major discoveries.

RECENT FINDINGS

Family and epidemiological studies further strengthen the genetic contribution to migraine and two recent observations gave new molecular insights in the disease. Studies on the genetics of familial hemiplegic migraine revealed, in addition to the previously identified familial hemiplegic migraine type 1 gene CACNA1A on chromosome 19, the familial hemiplegic migraine type 2 gene ATP1A2, encoding the alpha2-subunit of sodium/potassium pumps. Recent genome screens in families with migraine identified susceptibility loci on chromosomes 4, 6, 11 and 14.

SUMMARY

The findings in familial hemiplegic migraine confirm that dysfunction in ion transport is a key factor in migraine pathophysiology and might help us in the elucidation of migraine molecular pathways. The identification of several migraine susceptibility loci underline its genetically complex nature.

Toward a molecular genetic classification of familial hemiplegic migraine

The genetics of migraine is a fascinating and rapidly moving research area. Familial hemiplegic migraine, a rare subtype of migraine with a Mendelian pattern of inheritance, is caused by mutations in the chromosome 19 CACNA1A gene or in the chromosome 1 ATP1A2 gene. Familial migraine variants are classified on the basis of clinical, descriptive criteria, but this is insufficient. In the future, a diagnostic classification based on mutation-analysis is needed.

Hereditary cerebral hemorrhage with amyloidosis Dutch type (AbetaPP 693): decreased plasma amyloid-beta 42 concentration

Hereditary cerebral hemorrhage with amyloidosis-Dutch type (HCHWA-D) is a rare autosomal dominant disorder caused by an amyloid-beta precursor protein (AbetaPP) 693 mutation that clinically leads to recurrent hemorrhagic strokes and dementia. The disease is pathologically characterised by the deposition of Abeta in cerebral blood vessels and as plaques in the brain parenchyma. This study measured the Abeta40 and Abeta42 concentration in plasma of Dutch AbetaPP693 mutation carriers and controls. We found that the Abeta40 concentration was not different between AbetaPP693 mutation carriers and controls. However, the Abeta42 concentration was significantly decreased in the mutation carriers. No correlation exists between the APOE(epsilon)4 allele and the plasma of Abeta40 and Abeta42 levels in HCHWA-D patients. This finding contrasted with the increased concentrations found in Alzheimer's disease. Therefore it is suggested that the Dutch AbetaPP693 mutation located within the Abeta coding region of the AbetaPP gene has a different effect not only on clinical and pathological expression but also on Abeta processing.

Cerebral autosomal dominant arteriopathy with subcortical infarcts and leukoencephalopathy: MR imaging findings at different ages--3rd-6th decades

PURPOSE

To depict various brain lesions that have been described in patients who have cerebral autosomal dominant arteriopathy with subcortical infarcts and leukoencephalopathy (CADASIL) with prospective standardized magnetic resonance (MR) imaging in patients of different age groups.

MATERIALS AND METHODS

Forty patients with CADASIL in different age groups (20-30 years, n = 5; 31-40 years, n = 4; 41-50 years, n = 16; 51-60 years, n = 15) underwent transverse MR imaging with T1-weighted dual fast spin-echo, fluid-attenuated inversion-recovery, and T2*-weighted gradient-echo sequences. Images were analyzed by one neuroradiologist for the presence of areas of hyperintensity, lacunar infarcts, microbleeds, and subcortical lacunar lesions (SLLs) in different anatomic locations. Descriptive statistics were obtained for the presence of MR imaging abnormalities in various brain areas and for distribution according to age.

RESULTS

The mean age of the 40 mutation carriers (21 women, 19 men) was 45 years +/- 10 (SD). In patients with CADASIL who were 20-30 years old, characteristic hyperintense lesions in the anterior temporal lobe (100% [five of five]) and SLLs (20% [one of five]) were the only abnormalities seen on MR images. In patients who were 30-40 years old, lacunar infarcts were found in 75% (three of four) of cases. More areas of hyperintensity were noted, and they frequently involved the external capsule, basal ganglia, and brainstem. In patients 41-50 years old, microbleeds were observed in 19% (three of 16). In patients older than 50 years, areas of hyperintensity (100% [15 of 15]), SLLs (73% [11 of 15]), lacunar infarcts (93% [14 of 15]), and microbleeds (47% [seven of 15]) were frequently observed.

CONCLUSION

The four types of brain lesions that are observed in patients with CADASIL were seen in patients of different age groups.

Novel mutations in the Na+, K+-ATPase pump gene ATP1A2 associated with familial hemiplegic migraine and benign familial infantile convulsions

Familial hemiplegic migraine (FHM) is a rare, severe, autosomal dominant subtype of migraine with aura. Up to 75% of FHM families have a mutation in the P/Q-type calcium channel Ca(v)2.1 subunit CACNA1A gene on chromosome 19p13. Some CACNA1A mutations also may cause epilepsy. Here, we describe novel missense mutations in the ATP1A2 Na(+),K(+)-ATPase pump gene on chromosome 1q23 in two families with FHM. The M731T mutation was found in a family with pure FHM. The R689Q mutation was identified in a family in which FHM and benign familial infantile convulsions partially cosegregate. In this family, all available affected family members with FHM, benign familial infantile convulsions, or both, carry the ATP1A2 mutation. Like FHM linked to 19p13, FHM linked to 1q23 also involves dysfunction of ion transportation and epilepsy is part of its phenotypic spectrum.

Evaluation of diagnostic NOTCH3 immunostaining in CADASIL

CADASIL is caused by mutations in the NOTCH3 gene. Although increasingly recognized as a disease entity, the diagnostic confirmation can be lengthy or inconclusive. Recently, NOTCH3 immunostaining of skin biopsy specimens has been introduced as a new diagnostic test. The aim of this study was to independently assess the diagnostic value of NOTCH3 immunostaining, and determine whether the degree of immunostaining correlates with other disease parameters. We determined NOTCH3 mutation carrier status in 62 symptomatic and asymptomatic individuals from 15 CADASIL families. Skin biopsy specimens of these individuals, as well as of a disease control group, were immunostained with NOTCH3 antibody and blindly analyzed by two independent observers to determine sensitivity and specificity. A semiquantitative NOTCH3 immunostaining score was correlated with clinical, genetic and MRI parameters. The sensitivity was 90.2% and 85.4%, respectively, for the two observers, the specificity 95.2% and 100%; both lower than previously reported. Certain NOTCH3 mutations may underlie false-negative results. False-positive results were found in a non-mutated control, and also in one disease control. There was no difference in immunostaining between symptomatic and asymptomatic NOTCH3 mutated individuals. Furthermore, the NOTCH3 immunostaining score did not correlate with clinical or MRI parameters. NOTCH3 immunostaining is a supportive, but not definitive, CADASIL diagnostic test, and should be interpreted in the context of clinical and radiological data. Confirmation by DNA analysis is requisite for positive results, and when there exists high clinical suspicion, also for negative results.

Features involved in the diagnostic delay of cluster headache

BACKGROUND

Cluster headache (CH) is a comparatively rare, very severe primary headache. Although circumscript and recognisable criteria are available, the diagnosis is often missed or delayed. Besides, while adequate and evidence based treatment is available in diagnosed cases, CH seems to be poorly managed. The authors performed a nationwide survey among CH patients, and looked for factors involved in the diagnostic delay.

METHODS

The authors performed a nationwide mailing to all Dutch general practitioners (about 5800), and neurologists (about 560) and invited them to refer patients in whom the diagnosis CH was made or considered. Patients could also apply via the Dutch Headache Patients Society. A variety of clinical characteristics were assessed by means of questionnaires. Specifically, patients were asked about the time between their first episode and the diagnosis.

RESULTS

The IHS criteria for CH were met by 1429 of 2001 responders, and 1163 of these filled in an extended questionnaire. The male to female ratio was 3.7:1. Mean age at onset was 32 (SD 14) years. Seventy three per cent had episodic CH, 21% had chronic CH, and in 6% the periodicity was undetermined. The time between the first episode and the diagnosis ranged from 1 week to 48 years (median 3 years): 34% had consulted a dentist and 33% an ENT specialist before the diagnosis was established. Among factors that increased the diagnostic delay were the presence of photophobia or phonophobia, nausea, an episodic attack pattern and a low age at onset (p<0.01). Sex or presence of restlessness during episodes did not influence the diagnostic delay.

CONCLUSION

CH remains unrecognised or misdiagnosed in many cases for many years. Photophobia or phonophobia and nausea were in part responsible for this delay, and should be recognised as part of the clinical spectrum of CH. Many patients were first seen by a dentist or ENT specialist for their CH episodes, so more attention should be paid to educate first line physicians to recognise CH, to improve the diagnostic process and so to expose patients to earlier and better treatment of CH.

Myocardial infarction in cerebral autosomal dominant arteriopathy with subcortical infarcts and leukoencephalopathy (CADASIL)

Cerebral autosomal dominant arteriopathy with subcortical infarcts and leukoencephalopathy (CADASIL) is an angiopathy caused by mutations in the NOTCH3 gene. Typical microvascular changes are found throughout the arterial tree, but the documented disease expression is confined to the central nervous system. In an ongoing CADASIL study, we noted a number of patients with early acute myocardial infarction (before the age of 50 years), as well as patients with electrocardiogram (ECG) abnormalities. We analyzed these data to determine whether myocardial ischemia is associated with NOTCH3 mutations. ECGs were recorded in mutated (n = 41) and nonmutated (n = 22) individuals from 15 genetically confirmed CADASIL families, and blindly classified according to the Minnesota code. Cardiologic history was assessed and cardiovascular disease risk factors were determined. Evidence for myocardial infarction was defined as a positive history for acute myocardial infarction and/or a Minnesota Code 1 (Q-waves) on ECG. We examined CADASIL myocardial tissue ultrastructurally and immunohistochemically for evidence of microangiopathy. We found that almost 25% (10/41) of mutation carriers had evidence of myocardial infarction, versus none of the 22 nonmutation carriers (p = 0.011). Five had a medical history of acute myocardial infarction, and 5 had current pathologic Q-waves on ECG. Acute myocardial infarction occurred at a mean age of 39.6 +/- 5.22 years, and predated major neurologic symptoms of CADASIL in all cases. Pathologic examination of myocardial tissue revealed typical CADASIL arteriopathic changes of the coronary microvasculature. To our knowledge, this is the first study showing that NOTCH3 mutation carriers may be at increased risk of early acute myocardial infarction, expanding CADASIL disease expression beyond the central nervous system to include the heart.

The genetics of migraine: implication for treatment approaches

Migraine is a paroxysmal neurological disorder affecting up to 12% of males and 24% of females in the general population, demonstrated to have a strong, but complex, genetic component. Genetic investigation of migraine bears great promise in providing new targets for drug development and optimization of individual specific therapy. Better, preferably prophylactic, treatment of migraine patients is desired because the presently used drugs are not effective in all patients, allow recurrence of the headache in a high percentage of patients and sometimes have severe adverse side effects. With the recent identification of the brain-specific P/Q-type calcium channel gene CACNA1A in the pathogenesis of migraine, the first step has been taken to identify primary biochemical pathways leading to migraine. Here, we summarize the current knowledge about the genetics of migraine and focus on the implication for treatment approaches.

Migraine genetics

The genetics of migraine is a fascinating and moving research area. Familial hemiplegic migraine, a rare subtype of migraine with a Mendelian pattern of inheritance, is caused by mutations in the chromosome 19 CACNA1A gene in approximately 75% of the families. The finding of mutations in an ionchannel subunit defines migraine as a channelopathy (eg, epilepsy). The genetics of the more frequent variants, migraine with and without aura, is more complex. Several loci have been studied in families and case-control studies, but need to be confirmed.

Cerebral hemodynamics and white matter hyperintensities in CADASIL

Cerebral autosomal dominant arteriopathy with subcortical infarcts and leukoencephalopathy (CADASIL) is a hereditary small-vessel disease caused by mutations in the NOTCH3 gene on chromosome 19. On magnetic resonance imaging (MRI), subcortical white matter hyperintensities and lacunar infarcts are visualized. It is unknown whether a decrease in cerebral blood flow or cerebrovascular reactivity is primarily responsible for the development of white matter hyperintensities and lacunar infarcts. The authors used phase-contrast MRI in 40 NOTCH3 mutation carriers (mean age 45 +/- 10 years) and 22 nonmutated family members (mean age 39 +/- 12 years), to assess baseline total cerebral blood flow (TCBF) and cerebrovascular reactivity after acetazolamide. Mean baseline TCBF was significantly decreased in NOTCH3 mutation carriers. In young subjects, baseline TCBF was significantly lower than in nonmutation carriers (mean difference 124 mL/min). Furthermore, baseline TCBF did not differ significantly between mutation carriers with minimal and mutation carriers with moderate or severe white matter hyperintensities. No significant difference in mean cerebrovascular reactivity was found between mutation carriers and nonmutation carriers. This study suggests that a decrease in baseline TCBF in NOTCH3 mutation carriers precedes the development of white matter hyperintensities.

Expanding the phenotypic spectrum of the CACNA1A gene T666M mutation: a description of 5 families with familial hemiplegic migraine

BACKGROUND

Familial hemiplegic migraine (FHM) is a rare autosomal dominant subtype of migraine with aura. Missense mutations in the chromosome 19 CACNA1A calcium channel gene have been found in approximately half of the families. The T666M mutation, replacing a threonine by a methionine at residue number 666, is the most frequent mutation, reported in 14 independent FHM families; other mutations have so far been described in only 1 or 2 families each. The clinical features of T666M families have been reported, but the course is unknown.

OBJECTIVE

To present a detailed description of the clinical features of new FHM families in which we identified the T666M mutation in our CACNA1A screening program.

METHODS

As part of our ongoing genetic screening, mutation analysis of the CACNA1A gene was performed by single-strand conformational polymorphism analysis in 33 probands of families with FHM.

RESULTS

We identified the T666M mutation in 5 unrelated FHM families. In 3 of the families, patients displayed cerebellar ataxia. In 1 family, some affected members with the mutation had attacks with confusion but without hemiparesis. In 1 family, patients had progressive cognitive dysfunction.

CONCLUSIONS

The T666M mutation is the most frequent CACNA1A mutation in FHM; it was found in 5 of 33 FHM families at our laboratory, and in 19 of 39 families with a known mutation reported in the literature (including the present study). Screening for the T666M mutation should therefore be the first step when screening families with FHM. There is a remarkable clinical heterogeneity among families with the T666M mutation.

Incipient CADASIL

BACKGROUND

Cerebral autosomal dominant arteriopathy with subcortical infarcts and leukoencephalopathy (CADASIL) is caused by mutations in the NOTCH3 gene. Knowledge of disease expression in young adult NOTCH3 mutation carriers (MCs) is limited.

OBJECTIVE

To characterize clinical, neuropsychological, and radiological status in NOTCH3 MCs younger than 35 years.

DESIGN

Clinical characterization and blinded survey comparing MCs with non-MCs.

SETTING

Referral center.

PARTICIPANTS

Individuals younger than 35 years who were at a 50% risk of a NOTCH3 mutation, from our CADASIL database. Thirteen individuals, from 8 families, met the criteria.

METHODS

Comprehensive clinical, genetic, neuropsychological, and radiological investigations. Magnetic resonance images were scored according to a standardized white matter hyperintensities rating scale.

RESULTS

Six individuals, from 5 families, were MCs. Clinical symptoms consisted of migraine (with aura), stroke, and stroke-like episodes. We did not find evidence for psychiatric disturbances, functional disability, or cognitive dysfunction, compared with non-MCs. Radiologically, a characteristic magnetic resonance imaging lesion pattern emerged for all MCs. This comprised white matter hyperintensities in the anterior temporal lobes, the frontal lobes, and the periventricular frontal caps.

CONCLUSIONS

Migraine (with aura) and stroke can present in NOTCH3 MCs younger than 35 years; however, more importantly, physical function and cognition are intact. Possible subtle cognitive dysfunction needs to be assessed in a larger study. White matter hyperintensities on magnetic resonance imaging are characteristic, and are consistently visualized from the age of 21 years and onward. Awareness of the clinical and radiological features of CADASIL in those younger than 35 years should increase early diagnosis and allow for customized counseling of young adults from families with CADASIL.