CACNA1A-related familial hemiplegic migraine presenting with prolonged impaired consciousness

Background

Familial hemiplegic migraine (FHM) is a subtype of migraine with three identified causative genes: CACNA1A, ATP1A2, and SCN1A. However, diagnosis and treatment of FHM are challenging because of the wide phenotypic variation. We describe a family with genetically diagnosed CACNA1A-related FHM1 in which the proband presented with acute encephalopathy-like symptoms.

Case presentation

The proband was a 10-year-old girl admitted to our hospital with headache, paresthesia, frequent vomiting, and impaired consciousness. Blood test results and brain imaging were unremarkable, but she had persistent impaired consciousness. Electroencephalography indicated cerebral dysfunction. Consequently, she was treated with intravenous methylprednisolone pulse therapy and intravenous immune globulin for suspected acute encephalopathy. After treatment, her level of consciousness gradually improved, but headache persisted. Detailed interviews revealed that several maternal relatives had similar symptoms; the proband's younger sister subsequently developed headaches and paralysis. Given these findings, we conducted genetic counseling and familial genetic analysis with informed consent, which led to the diagnosis of CACNA1A-related FHM1. The proband started acetazolamide therapy, which successfully prevented the recurrence of attacks. This genetic information was also beneficial for managing the mother's and sister's conditions.

Conclusion

In the proband, FHM attacks were severe and occurred at a young age, making genetic diagnosis particularly important. Genetic diagnosis was useful in understanding the symptoms and guiding management for the patient as well as affected family members.