Familial hemiplegic migraine in the west of Scotland: a clinical and genetic study of seven families

Sporadic Hemiplegic Migraine

Sporadic hemiplegic migraine (SHM) is defined as migraine attacks associated with some degree of motor weakness/hemiparesis during the aura phase and where no first degree relative (parent, sibling or child) has identical attacks. The present review deals with recent scientific studies according to which: The SHM prevalence is estimated to be 0.005%; SHM patients have clinical symptoms identical to patients with familial hemiplegic migraine (FHM) and significantly different from patients with migraine with typical aura (typical MA); SHM affected had no increased risk of migraine without aura (MO), but a highly increased risk of typical MA compared to the general population; SHM patients only rarely have mutations in the FHM gene CACNA1A; SHM attacks in some cases can be treated with Verapamil. The reviewed data underlie the change in the International Classification of Headache Disorders 2nd edition where SHM became separated from migraine with typical aura or migraine with prolonged aura. All cases with motor weakness should be classified as either FHM or SHM.

Familial Hemiplegic Migraine: Follow-up Findings of Diffusion-Weighted Magnetic Resonance Imaging (MRI), Perfusion-MRI and [99mTc] HMPAO-SPECT in a Patient with Prolonged Hemiplegic Aura

Familial hemiplegic migraine (FHM) is a rare inherited autosomal dominant disorder. Migraine aura may last up to several weeks and then resolve without sequel. We report a 21-year-old male with FHM since the age of 3 years. Diffusion-weighted magnetic resonance imaging (DWI), perfusion-MR imaging (P-MRI) and [99mTc] hexamethyl-propyleneamine-oxime-single photon emission tomography (HMPAO-SPECT) were performed on day 2, when he was somnolent with right-sided hemiplegia, on day 9 when a mild hemiparesis was still present and on day 24 after recovery. The right central region showed normal findings in DWI, whereas P-MRI and SPECT revealed hyperperfusion on day 2, less marked on day 9, and normal findings on day 24. In conclusion, this case report indicates for the first time, by means of SPECT, P-MRI and DWI studies, that even extremely long-lasting migraine aura is not associated with cerebral ischaemia. Therefore, it supports the revised International Headache Society criteria where the term ‘persistent’ aura is proposed.

Migraine genetics: current findings and future lines of research

In the last two decades, migraine research has greatly advanced our current knowledge of the genetic contributions and the pathophysiology of this common and debilitating disorder. Nonetheless, this knowledge still needs to grow further and to translate into more effective treatments. To date, several genes involved in syndromic and monogenic forms of migraine have been identified, allowing the generation of animal models which have significantly contributed to current knowledge of the mechanisms underlying these rare forms of migraine. Common forms of migraine are instead posing a greater challenge, as they may most often stem from complex interactions between multiple common genetic variants, with environmental triggers. This paper reviews our current understanding of migraine genetics, moving from syndromic and monogenic forms to oligogenic/polygenic migraines most recently addressed with some success through genome-wide association studies. Methodological issues in study design and future perspectives opened by biomarker research will also be briefly addressed.

Increased risk of migraine with typical aura in probands with familial hemiplegic migraine and their relatives

We investigated the occurrence of migraine without aura (MO) and migraine with typical aura (MA) amongst probands with familial hemiplegic migraine (FHM) and their first degree relatives in order to evaluate the relations between these syndromes. A total of 44 FHM probands and 240 first degree relatives were identified in the Danish population. The pattern of familial aggregation was assessed by population relative risk (PRR) calculations. Amongst FHM probands the PRR of MO was 1.5 (95% CI: 0.8-2.2), whereas the PRR of MA was 7.1 (95% CI: 5.0-9.2). Thus, compared with the general population, FHM probands had no increased risk of MO but a significantly increased risk of MA. A similar pattern was seen amongst their first degree relatives, who had no increased risk of MO, whereas the risk of MA was significantly increased; 7.6 times in FHM-affected first degree relatives and 2.4-times in non-FHM-affected first degree relatives. These results are contrary to a sharing of genetic mechanisms between FHM and MO. Furthermore, they suggest that the genetic abnormality causing FHM may also cause attacks with the symptomatology of MA.

The genetics of migraine

The search for genes involved in the pathophysiology of migraine poses major difficulties. First, there is no objective diagnostic method to assess the status of the individuals studied. Second, migraine is a polygenic multifactorial disorder. Familial hemiplegic migraine (FHM) is the only known autosomal dominant subtype of migraine. In half the families with FHM who have been studied, there are mutations in the calcium-channel gene CACNA1A, located on chromosome 19. In other families, a locus has been mapped on chromosome 1. The role of these loci in typical migraine is still unknown. A susceptibility locus for migraine with aura has been located on chromosome 19 (but is distinct from CACNA1A) and a genome-wide linkage analysis has mapped a susceptibility locus on chromosome 4. Another locus for migraine may be on the X chromosome. Finally, many positive association studies have been published, but few have been replicated.

A population-based study of familial hemiplegic migraine suggests revised diagnostic criteria

Familial hemiplegic migraine (FHM) is a rare autosomal dominantly inherited subtype of migraine with aura. The clinical characteristics of FHM have been described previously in selected materials or case studies, but population-based studies are important in order to analyse the full spectrum of the disorder. The aim of the present study was to perform a systematic search for familial cases of migraine with an aura that included motor weakness in order to generate non-selected material of as many FHM cases as possible in the Danish population of 5.2 million inhabitants, and to compare this material with already available population-based clinical descriptions of migraine with typical aura (MA). Due to the rarity of FHM, traditional population-based methods were not feasible. Therefore, the search strategy employed a computer search of the National Patient Register, screening >27 000 case records from headache clinics and private neurologists, and advertisements. A total of 147 affected FHM patients from 44 families were identified. FHM patients most often had all four 'typical' aura symptoms (visual, sensory, aphasic and motor symptoms) and all had at least two of these aura symptoms during FHM attacks. The motor, sensory and visual aura symptoms were all similar in type to the motor, sensory and visual aura symptoms in MA, but FHM had a statistically significantly longer duration of the visual and sensory aura symptoms, and these and other aura symptoms often fulfilled the criteria of the International Headache Society for prolonged aura. In addition, 69% had basilar migraine (BM) symptoms during FHM attacks. The order of the aura symptoms was usually visual, followed by sensory, aphasic, motor and, lastly, basilar-type migraine symptoms. Headache was present in 99% of FHM patients during FHM attacks, whereas the aura symptoms more often occurred without headache in MA. Headache duration was significantly longer in FHM compared with MA. Based on these data, we suggest more precise diagnostic criteria for FHM and a more clear clinical distinction between FHM and BM. Our results have significant implications for case finding in genetic studies and for clinical migraine differential diagnosis.

An epidemiological survey of hemiplegic migraine

The objective of the present study was to use systematic nation-wide case-finding methods to establish the prevalence and sex ratio of hemiplegic migraine (HM) in the entire Danish population of 5.2 million inhabitants. Affected patients were identified from three different recruitment sources: the National Patient Register, case records from private practising neurologists and advertisements. Based on the observed number of affected patients from each case-finding method, it was attempted to estimate the total number of affected patients by means of the statistical method known as capture-recapture. Two hundred and ninety-one affected patients were identified; 147 were familial HM from 44 different families, 105 were sporadic HM and 39 were unclassifiable HM. The HM sex ratio (M:F) was 1:3. Based on the identified number of affected patients the prevalence of HM at the end of 1999 was estimated to be 0.01% in Denmark, where the familial and sporadic form were equally frequent.

Chromosome 6p-encoded HLA-DR2 determination discriminates migraine without aura from migraine with aura

Segregation analysis indicates that migraine without aura (MWoA) and migraine with aura (MWA) have multifactorial inheritance, but involved genetic and environmental factors are largely unknown. A controlled study was performed to assess the HLA-driven liability to migraine and to verify if the heterogeneity between MWoA and MWA is HLA-linked. Forty-five migraine patients (31 MWoA, 14 MWA) and 53 healthy blood donors as controls, coming from the same geographic area, were studied. Tissue typing was performed using the standard complement-dependent microlymphocytotoxicity technique for HLA Class I and by PCR-SSP (Sequences Specific Primers) typing for HLA Class II. Data emerging from the present study showed no altered distribution for HLA Class I A, B, C antigen frequency in migraine (MWoA, MWA) if compared to the control group. HLA Class II DR2 antigen showed a decreased frequency in MWA group if compared with both MWoA (p = 0.01) and control group (p = 0.039, RR = 0.21). These results seem to support the hypothesis of a protective role of DR2 antigen in MWA and provide additional basis for the proposed difference within MWoA and MWA.

Mapping of a second locus for familial hemiplegic migraine to 1q21-q23 and evidence of further heterogeneity

Familial hemiplegic migraine (FHM) is an autosomal dominant variety of migraine with aura. We previously mapped an FHM gene on the short arm of chromosome 19. Mutations in this gene, recently shown to be the alpha1 subunit of a P/Q-type voltage-dependent calcium channel, CACNL1A4, are involved in approximately 50% of unselected FHM families and in all families where migraine attacks are associated with permanent cerebellar ataxia. As a first step toward the identification of other FHM genes, we conducted a genetic linkage analysis in one large French pedigree and showed significant linkage to two microsatellite markers D1S2635 (Zmax: 3.33 at theta = 0.05) and D1S2705 (Zmax: 3.64 at theta = 0.05), establishing the existence of a second locus for FHM (FHM2) on chromosome 1q21-q23. Analysis of six additional FHM families favored linkage to this locus in two of them; linkage was excluded in the last four families, indicating further heterogeneity. Chromosome 1-linked families differ from the ones linked to chromosome 19, because penetrance in those families is much lower, and in some of their members, epileptic seizures occur during severe migraine attacks.