Familial hemiplegic migraine

Familial hemiplegic migraine (FHM) is a rare and genetically heterogeneous autosomal dominant subtype of migraine with aura. Mutations in the genes CACNA1A and SCNA1A, encoding the pore-forming α₁ subunits of the neuronal voltage-gated Ca²⁺ channels Ca_v2.1 and Na⁺ channels Na_v1.1, are responsible for FHM1 and FHM3, respectively, whereas mutations in ATP1A2, encoding the α₂ subunit of the Na⁺, K⁺ adenosinetriphosphatase (ATPase), are responsible for FHM2. This review discusses the functional studies of two FHM1 knockin mice and of several FHM mutants in heterologous expression systems (12 FHM1, 8 FHM2, and 1 FHM3). These studies show the following: (1) FHM1 mutations produce gain-of-function of the Ca_v2.1 channel and, as a consequence, increased Ca_v2.1-dependent neurotransmitter release from cortical neurons and facilitation of in vivo induction and propagation of cortical spreading depression (CSD: the phenomenon underlying migraine aura); (2) FHM2 mutations produce loss-of-function of the α₂ Na⁺,K⁺-ATPase; and (3) the FHM3 mutation accelerates recovery from fast inactivation of Na_v1.5 (and presumably Na_v1.1) channels. These findings are consistent with the hypothesis that FHM mutations share the ability of rendering the brain more susceptible to CSD by causing either excessive synaptic glutamate release (FHM1) or decreased removal of K⁺ and glutamate from the synaptic cleft (FHM2) or excessive extracellular K⁺ (FHM3). The FHM data support a key role of CSD in migraine pathogenesis and point to cortical hyperexcitability as the basis for vulnerability to CSD and to migraine attacks. Hence, they support novel therapeutic strategics that consider CSD and cortical hyperexcitability as key targets for preventive migraine treatment.     

Minor head trauma-induced sporadic hemiplegic migraine coma

Familial hemiplegic migraine is a severe, rare subtype of migraine. Gene mutations on chromosome 19 have been identified in the calcium channel, voltage-dependent, P/Q type, alpha-1A subunit gene (chromosome 19p13) for familial hemiplegic migraine. Recently a gene mutation (Serine-218-Leucine) for a dramatic syndrome associated with familial hemiplegic migraine, commonly named "migraine coma", has implicated exon 5 of this gene. The occurrence of trivial head trauma, in such familial hemiplegic migraine patients, may also be complicated by severe, sometimes even fatal, cerebral edema and coma occurring after a lucid interval. Sporadic hemiplegic migraine shares a similar spectrum of clinical presentation and genetic heterogeneity. The case report presented in this article implicates the involvement of the Serine-218-Leucine mutation in the extremely rare disorder of minor head trauma-induced migraine coma. We conclude that the Serine-218-Leucine mutation in the calcium channel, voltage-dependent, P/Q type, alpha-1A subunit gene is involved in sporadic hemiplegic migraine, delayed cerebral edema and coma after minor head trauma.     

Familial hemiplegic migraine,nystagmus, and cerebellar atrophy

Familial hemiplegic migraine (FHM) is an autosomal dominant disorder characterized by transient hemiplegia during the aura phase of a migraine attack. Nystagmus has been reported in individuals affected with this disorder, but the origin of the ocular motility findings is unknown. A three-generation family with FHM is described and clinical histories are outlined. Ocular motility evaluations were performed on 7 family members, 5 with a history of hemiplegic migraine and 2 without history of migraine. All affected family members had abnormal eye movements consistent with vestibulocerebellar dysfunction. Magnetic resonance imaging scans in affected family members revealed cerebellar vermian atrophy. DNA linkage analysis revealed a common marker in all the affected family members on chromosome 19. We suggest that the hemiplegic migraine attacks and the cerebellar degeneration are linked genetically and that the eye movements are not the ischemic sequelae of recurrent migraine. Strikingly similar ocular motility findings and cerebellar degeneration are reported in both FHM and a genetically related disorder, hereditary paroxysmal cerebellar ataxia (HPCA). The significance of these similarities is discussed along with a proposed pathophysiology for FHM.     

Familial hemiplegic migraine with cerebellar ataxia and paroxysmal psychosis

Familial hemiplegic migraine is a rare autosomal dominant disorder associated with stereotypic neurologic aura phenomena including hemiparesis. So far two chromosomal loci have been identified. Families linked to the chromosome 19 locus display missense mutations within the CACNL1A4 gene. Here we report on a family with familial hemiplegic migraine and cerebellar ataxia with recurrent episodes of acute paranoid psychosis with anxiety and visual hallucinations associated with migraine attacks. Based on the clinical and haplotype evidence indicating linkage to chromosome 19 in this family, we hypothesize that a dysfunction of the mutated calcium channel may be involved not only in the development of hemiplegic migraine but also in the acute psychotic episodes observed in these patients.     

Familial hemiplegic migraine: a ion channel disorder

At present, little information is available on the genetics of common migraines, most likely to be considered a multifactorial disease. Recently, the CACNA1A gene encoding the brain-specific P/Q type calcium channel alpha(1) subunit, has been cloned and mutations in this gene, located on chromosome 19p13, have been shown to be involved in familial hemiplegic migraine (FHM), a rare autosomal dominantly inherited subtype of migraine with aura. Being part of the migraine spectrum, FHM represents a good model to study the genetics of more common forms of migraine. Different classes of mutations within the CACNA1A gene have been associated with different diseases, thus identifying a new member among 'channelopathies'. Variable clinical expression and genetic heterogeneity of FHM will be discussed.     

Treatment of sporadic hemiplegic migraine with calcium-channel blocker verapamil

Gene mutations within the P/Q type neuronal calcium channel in familial hemiplegic migraine (FHM) suggest a therapeutic role for calcium-channel blockade. The authors have previously reported abortive therapy of FHM with IV verapamil. Here the authors describe four cases of sporadic hemiplegic migraine (SHM) responsive to verapamil, administered either orally or IV. The findings indicate that verapamil is effective therapy for both SHM and FHM.     

Familial hemiplegic migraine and autosomal dominant arteriopathy with leukoencephalopathy (CADASIL)

Cerebral autosomal dominant arteriopathy with subcortical infarcts and leukoencephalopathy (CADASIL) is a recently described familial cerebrovascular disorder shown to map to chromosome 19q12. Familial hemiplegic migraine has also been shown in some families to map close to the CADASIL locus. The fully developed CADASIL phenotype consists of recurrent strokes developing in the fourth decade, progressing to a pseudobulbar palsy, spastic quadriparesis, and subcortical dementia. In an Irish family 15 members were fully investigated by magnetic resonance scanning; 10 had typical magnetic resonance features of CADASIL. Five members of this family had familial hemiplegic migraine and 4 of these had magnetic resonance evidence of CADASIL. Two other members had migraine with and without aura as a presenting clinical symptom of CADASIL. This disorder has been shown by linkage analysis to map to the CADASIL locus at chromosome 19. The phenotype at presentation of CADASIL in this family was variable and age related and included familial hemiplegic migraine, migraine with and without aura, transient ischemic attacks, strokes, and spinal cord infarction. This family study increases our understanding of the spectrum of clinical manifestations of this underrecognized familial cerebrovascular disorder.     

Familial hemiplegic migraine: EEG and CT scan study of two cases

The cases of a woman and her son with a long history (24 and 9 years, respectively) of hemiplegic migraine are presented. The mother demonstrated exclusively right-sided paralysis; in the son, paralysis occurred on each side. Electroencephalograms recorded during the attacks were characterized by pseudoperiodic slow sharp waves over the hemisphere contralateral to the hemiplegia. Between attacks the neurological examination and EEG were normal. CT scans performed during and between attacks showed no abnormalities.     

The genetic features of 24 patients affected by familial and sporadic hemiplegic migraine

Familial hemiplegic migraine (FHM) is the only migraine subtype for which a monogenic mode of inheritance, autosomal dominant has been clearly established. It is genetically heterogeneous and at least three different genes exist (CACNA1A, ATP1A2, and SCN1A), the so-called FHM1, FHM2, and FHM3 genes, respectively. Sporadic hemiplegic migraine (SHM) is a disorder, in which some patients may have their pathophysiology identical to FHM, but others, possibly the majority, may have different pathophysiology, probably related to the mechanisms of typical migraine with aura. In our study, we have screened the DNA of 24 patients affected by FHM and SHM. Only in three patients, 2 sporadic and 1 familial cases, we have described genetic mutations, all of them in the ATP1A2 gene. In our opinion, these results demonstrate a more frequent involvement of the ATP1A2 gene not only in the sporadic form, but probably also in the Italian FHM patients without permanent cerebellar signs. Moreover, the absence of CACNA1A, ATP1A2 and SCN1A mutations in the other 12 familial cases suggests the involvement of still unknown genes.

     

Prolonged hemiplegic migraine

Hemiplegic migraine is a rare form of migraine variant. It is characterized by recurrent attacks of headache associated with temporary neurological deficit, usually unilateral hemiparesis or hemiplegia. It can be difficult to distinguish from migrainous stroke clinically, and a full neurological work-up and careful review of medical history and symptoms are necessary for the diagnosis. Two forms of hemiplegic migraine are known: familial and sporadic, phenotypically similar, differentiated by the absence of family history of similar attacks in the sporadic form. We report a case of sporadic hemiplegic migraine with unusually prolonged deficit and progression to quadriplegia with complete return to baseline 7 days after onset. Diffusion weighted images helped in excluding infarction.