Familial Hemiplegic Migraine

Bashir A. Soomro

Fri, 04 Apr 2025

Familial hemiplegic migraine (FHM) is a subclass of migraine with aura characterized by attacks typically lasting between 5-60 minutes fulfilling hemiplegic migraine criteria and at least one first- or second-degree relative also meeting hemiplegic migraine criteria.1 FHM causes brain hyperexcitability followed by cortical depression, leading to attacks of varying duration and symptomatology.2 FHM is classified into FHM1, FHM2, FHM3 defined, respectively, by their gene variants on CACNA1A, ATP1A2, and SCN1A. However, some FHMs do not yet have identified genes. FHM1 often presents with cerebellar deficits like ataxia, dysarthria, and nystagmus. FHM2 can be associated with seizures and intellectual disability. FHM3 is rare and symptomatology requires further exploration of its nuances.2,3 Treatment for all three FHMs include acute and prophylactic migraine medications.2

References

1. Headache Classification Committee of the International Headache Society (IHS). The International Classification of Headache Disorders, 3rd edition (beta version). Cephalalgia. 2013;33(9):629-808; doi: 10.1177/0333102413485658
2. Jen JC. Familial Hemiplegic Migraine. Published July 17, 2001. Updated July 4, 2024. In: Adam MP, Feldman J, Mirzaa GM, et al., editors. GeneReviews® [Internet]. Seattle (WA): University of Washington, Seattle; 1993-2024. Available from: https://www.ncbi.nlm.nih.gov/books/NBK1388/
3. Brunklaus A, Brünger T, Feng T, et al. The gain of function SCN1A disorder spectrum: novel epilepsy phenotypes and therapeutic implications. Brain. 2022;145(11):3816-3831; doi:10.1093/brain/awac210