Familial hemiplegic migraine type 2 with cerebral vasospasm and acute encephalopathy caused by an ATP1A2 gene variant: a case report.

Background: Hemiplegic migraine (HM) is a rare monogenic subtype of migraine characterized by a broad spectrum of symptoms, ranging from transient hemiplegic episodes to recurrent coma. Imaging documentation of cerebral vasospasm during acute HM attacks is exceedingly rare. We present a pediatric case of familial HM (FHM) with cerebral vasospasm and acute encephalopathy caused by an ATP1A2 gene variant to enhance clinical recognition of this condition. Case Description: An 11-year-old Asian female with a 2-year history of recurrent HM presented with fever, headache, altered consciousness, and right-sided weakness for 48 hours. The current acute episode occurred without identifiable triggers and was characterized by fever, prolonged headache, acute encephalopathy, and persistent hemiplegia. Acute-phase magnetic resonance imaging revealed left cerebral cortical swelling with mild diffusion restriction. Magnetic resonance angiography demonstrated dynamic cerebral vasospasm, with spontaneous resolution observed on follow-up imaging. A heterozygous c.2464G>A (p.Glu822Lys) missense variant in the ATP1A2 gene was identified; this variant was inherited from her mother, who has a history of recurrent headaches. Conclusions: This report describes a unique case of internal carotid artery vasospasm occurring in HM, which, to our knowledge, has not been previously reported in the literature. Investigating alterations in the cerebrovascular system contributes significantly to understanding the clinical manifestations and underlying mechanisms of HM.