Prolonged Sporadic Hemiplegic Migraine Associated With a Novel De Novo Missense ATP1A2 Gene Mutation

Two pediatric patients with hemiplegic migraine presenting as acute encephalopathy: case reports and a literature review

Introduction

Hemiplegic migraine (HM) is a rare subtype of migraine. HM in children may be atypical in the initial stage of the disease, which could easily lead to misdiagnosis.

Methods

We report two cases of atypical hemiplegic migraine that onset as an acute encephalopathy. And a comprehensive search was performed using PubMed, Web of Science, and Scopus. We selected only papers that reported complete clinical information about the patients with CACNA1A or ATP1A2 gene mutation.

Results

Patient #1 showed a de novo mutation, c.674C>A (p. Pro225His), in exon 5 of the CACNA1A gene. And patient #2 showed a missense mutation (c.2143G>A, p. Gly715Arg) in exon 16 of the ATP1A2. Together with our two cases, a total of 160 patients (73 CACNA1A and 87 ATP1A2) were collected and summarized finally.

Discussion

Acute encephalopathy is the main manifestation of severe attacks of HM in children, which adds to the difficulty of diagnosis. Physicians should consider HM in the differential diagnosis of patients presenting with somnolence, coma, or convulsion without structural, epileptic, infectious, or inflammatory explanation. When similar clinical cases appear, gene detection is particularly important, which is conducive to early diagnosis and treatment. Early recognition and treatment of the disease can help improve the prognosis.

Genetics of migraine: where are we now?

Migraine is a complex brain disorder explained by the interaction of genetic and environmental factors. In monogenic migraines, including familial hemiplegic migraine and migraine with aura associated with hereditary small-vessel disorders, the identified genes code for proteins expressed in neurons, glial cells, or vessels, all of which increase susceptibility to cortical spreading depression. The study of monogenic migraines has shown that the neurovascular unit plays a prominent role in migraine. Genome-wide association studies have identified numerous susceptibility variants that each result in only a small increase in overall migraine risk. The more than 180 known variants belong to several complex networks of "pro-migraine" molecular abnormalities, which are mainly neuronal or vascular. Genetics has also highlighted the importance of shared genetic factors between migraine and its major co-morbidities, including depression and high blood pressure. Further studies are still needed to map all of the susceptibility loci for migraine and then to understand how these genomic variants lead to migraine cell phenotypes.

Novel missense mutation in the ATP1A2 gene associated with atypical sporapedic hemiplegic migraine

Hemiplegic migraine (HM) is a rare subtype of migraine with aura in which attacks include transient motor weakness or hemiparesis that can last several days. HM is linked to mutations in three different genes, CACNA1A, ATP1A2 and SCN1A, which encode for ion transporters. The clinical spectrum includes atypical symptoms such as impaired consciousness, epileptic seizures, permanent cerebellar ataxia or mental retardation. We describe a novel mutation found in the ATP1A2 gene in a patient with late-onset HM. His attacks were characterised by motor weakness associated with altered mental status, diplopia and ataxia. He also showed up MRI abnormalities and incomplete response to prophylactic therapy with verapamil. Late-onset HM should be considered among the possible causes of focal neurological deficits even in older patients with cerebrovascular risk factors when a stroke appears to be more likely.

Clinical Benefit of NMDA Receptor Antagonists in a Patient With ATP1A2 Gene Mutation

Mutations in the ATP1A2 gene cause familial hemiplegic migraine type 2, alternating hemiplegia of childhood, and cerebellar function deficits, epilepsy, and mental retardation. These symptoms are likely related to glutamatergic hyperexcitability. Our patient is a 12-year-old boy with a history of complex partial seizures, attention-deficit/hyperactivity disorder, and fine motor difficulty. During early childhood, he had episodes of a self-resolving right-sided hemiparesis and focal epilepsy. His seizures did not respond to several antiepileptic medications but stopped after he received valproate. His intermittent episodes of hemiplegia persisted. Additionally, he had pronounced bilateral fine motor impairment and significant executive deficits that gradually worsened. The whole exome sequencing revealed a de novo missense mutation in the ATP1A2 gene and a maternally inherited POLG gene mutation of unknown clinical significance. We hypothesized that glutamatergic excitotoxicity due to the ATP1A2 mutation contributed to the pathogenesis of our patient's condition. He was started on N-methyl-D-aspartate receptor antagonists (memantine and dextromethorphan), as well as coenzyme Q₁₀ One year later, he showed significant improvement in sustained attention, learning efficiency, general cognitive efficiency, and fine motor dexterity. We postulate that N-methyl-D-aspartate receptor antagonists were effective for behavioral, cognitive, and cerebellar symptoms in our patient with ATP1A2 gene mutation.

Migraine with prolonged aura: phenotype and treatment

We review the published literature on migraine with prolonged aura (PA), specifically with regards to the phenotype and treatment options. PA is not uncommon. A recent study found that about 17% of migraine auras are prolonged and that 26% of patients with migraine with aura have experienced at least one PA. The characteristics of PA are similar to most typical auras with the exception of a higher number of aura symptoms (in particular sensory and/or dysphasic). There are no well-established treatments at present which target the aura component of migraine. Other than case reports, there have been open-label studies of lamotrigine and greater occipital nerve blocks. The only randomised, blinded, controlled trial to date has been of nasal ketamine showing some reduction in aura severity but not duration. A small open-labelled pilot study of amiloride was also promising. Larger randomised, controlled trials are needed to establish whether any of the existing or novel compounds mentioned are significantly effective and safe.

Familial Hemiplegic Migraine with Severe Attacks: A New Report with ATP1A2 Mutation

Introduction. Familial hemiplegic migraine (FHM) is a rare disorder characterized by migraine attacks with motor weakness during the aura phase. Mutations in CACNA1A, ATP1A2, SCN1A, and PRRT2 genes have been described. Methods. To describe a mutation in ATP1A2 gene in a FHM case with especially severe and prolonged symptomatology. Results. 22-year-old woman was admitted due to migraine-type headache and sudden onset of right-sided weakness and aphasia; she had similar episodes in her childhood. Her mother was diagnosed with hemiplegic migraine without genetic confirmation. She presented with fever, decreased consciousness, left gaze preference, mixed aphasia, right facial palsy, right hemiplegia, and left crural paresis. Computed tomography (CT) showed no lesion and CT perfusion study evidenced oligohemia in left hemisphere. A normal brain magnetic resonance (MR) was obtained. Impaired consciousness and dysphasia began to improve three days after admission and mild dysphasia and right hemiparesis lasted for 10 days. No recurrences were reported during a follow-up of two years. We identified a variant in heterozygous state in ATP1A2 gene (p.Thr364Met), pathogenic according to different prediction algorithms (SIFT, PolyPhen2, MutationTaster, and Condel). Conclusion. Prolonged and severe attacks with diffuse hypoperfusion in a FHM seemed to be specially related to ATP1A2 mutations, and p.T364M should be considered.

Recurrent coma and fever in familial hemiplegic migraine type 2. A prospective 15-year follow-up of a large family with a novel ATP1A2 mutation

Background Familial hemiplegic migraine (FHM) is a rare monogenic migraine subtype characterised by attacks associated with transient motor weakness. Clinical information is mainly based on reports of small families with only short follow-up. Here, we document a prospective 15-year follow-up of an extended family with FHM type 2. Patients and methods After diagnosing FHM in a patient with severe attacks associated with coma and fever, we identified eight more family members with FHM and one with possible FHM. All family members were prospectively followed for 15 years. In total 13 clinically affected and 21 clinically non-affected family members were genetically tested and repeatedly investigated. Results A novel p.Arg348Pro ATP1A2 mutation was found in 14 family members: 12 with clinical FHM, one with psychomotor retardation and possible FHM, and one without FHM features. In 9/12 (75%) family members with genetically confirmed FHM, attacks were severe, long-lasting, and often associated with impaired consciousness and fever. Such attacks were frequently misdiagnosed and treated as viral meningitis or stroke. Epilepsy was reported in three family members with FHM and in the one with psychomotor retardation and possible FHM. Ataxia was not observed. Conclusion FHM should be considered in patients with recurrent coma and fever.

A missense variant of the ATP1A2 gene is associated with a novel phenotype of progressive sensorineural hearing loss associated with migraine

Hereditary sensorineural hearing loss is an extremely clinical and genetic heterogeneous disorder in humans. Especially, syndromic hearing loss is subdivided by combinations of various phenotypes, and each subtype is related to different genes. We present a new form of progressive hearing loss with migraine found to be associated with a variant in the ATP1A2 gene. The ATP1A2 gene has been reported as the major genetic cause of familial migraine by several previous studies. A Korean family presenting progressive hearing loss with migraine was ascertained. The affected members did not show any aura or other neurologic symptoms during migraine attacks, indicating on a novel phenotype of syndromic hearing loss. To identify the causative gene, linkage analysis and whole-exome sequencing were performed. A novel missense variant, c.571G>A (p.(Val191Met)), was identified in the ATP1A2 gene that showed co-segregation with the phenotype in the family. In silico studies suggest that this variant causes a change in hydrophobic interactions and thereby slightly destabilize the A-domain of Na(+)/K(+)-ATPase. However, functional studies failed to show any effect of the p.(Val191Met) substitution on the catalytic rate of this enzyme. We describe a new phenotype of progressive hearing loss with migraine associated with a variant in the ATP1A2 gene. This study suggests that a variant in Na(+)/K(+)-ATPase can be involved in both migraine and hearing loss.

Pearls and pitfalls in genetic studies of migraine

Purpose of review

Migraine is a prevalent neurovascular brain disorder with a strong genetic component, and different methodological approaches have been implemented to identify the genes involved. This review focuses on pearls and pitfalls of these approaches and genetic findings in migraine.

Summary

Common forms of migraine (i.e. migraine with and without aura) are thought to have a polygenic make-up, whereas rare familial hemiplegic migraine (FHM) presents with a monogenic pattern of inheritance. Until a few years ago only studies in FHM yielded causal genes, which were identified by a classical linkage analysis approach. Functional analyses of FHM gene mutations in cellular and transgenic animal models suggest abnormal glutamatergic neurotransmission as a possible key disease mechanism. Recently, a number of genes were discovered for the common forms of migraine using a genome-wide association (GWA) approach, which sheds first light on the pathophysiological mechanisms involved.

Conclusions

Novel technological strategies such as next-generation sequencing, which can be implemented in future genetic migraine research, may aid the identification of novel FHM genes and promote the search for the missing heritability of common migraine.

Acute striatal necrosis in hemiplegic migraine with de novo CACNA1A mutation

We report the case of a 9-year-old girl with early-onset developmental delay, chronic ataxia and prolonged hemiplegic migraine episodes bringing about progressive deterioration. Two days into one episode, diffusion-weighted magnetic resonance imaging disclosed unilateral striatal abnormal signal consistent with cytotoxic edema, which evolved into atrophy on follow-up scans. Mutational screen of CACNA1A gene identified a de novo p.Tyr1387Cys mutation.

Late cytotoxic edema in 2 children with hemiplegia: hemiplegic migraine or stroke?

Hemiplegic migraine (HM) is a rare variant of migraine with aura, characterized by migrainous headache and fully reversible motor deficit within 24 hours. Both sporadic and familial forms of HMs are genetically heterogenous with little information on neuroimaging during and after acute attacks. We report 2 cases of children with presumed HM and late cytotoxic edema.

Migraine- and dystonia-related disease-mutations of Na+/K+-ATPases: relevance of behavioral studies in mice to disease symptoms and neurological manifestations in humans

The two autosomal dominantly inherited neurological diseases: familial hemiplegic migraine type 2 (FHM2) and familial rapid-onset of dystonia-parkinsonism (Familial RDP) are caused by in vivo mutations of specific alpha subunits of the sodium-potassium pump (Na(+)/K(+)-ATPase). Intriguingly, patients with classical FHM2 and RDP symptoms additionally suffer from other manifestations, such as epilepsy/seizures and developmental disabilities. Recent studies of FHM2 and RDP mouse models provide valuable tools for dissecting the vital roles of the Na(+)/K(+)-ATPases, and we discuss their relevance to the complex patient symptoms and manifestations. Thus, it is interesting that mouse models targeting a specific α-isoform cause different, although still comparable, phenotypes consistent with classical symptoms and other manifestations observed in FHM2 and RDP patients. This review highlights that use of mouse models have broad potentials for future research concerning migraine and dystonia-related diseases, which will contribute towards understanding the, yet unknown, pathophysiologies.