Teaching NeuroImages: Transient Cytotoxic Edema in a Child with a Novel ATP1A2 Mutation.

A seven-year-old boy with prior episodes of hemiplegia and family history of hemiplegic migraine presented with fevers, waxing and waning encephalopathy (lethargic and poorly interactive), and left-sided weakness persistent throughout his five-week hospitalization. Diagnostic testing revealed a suspected pathogenic mutation in ATP1A2 (c.2285G>C; p.Gly762Ala), a gene associated with a broad phenotypic spectrum encompassing familial hemiplegic migraine type two (FHM2) and alternating hemiplegia of childhood. Previous case series illustrate that FMH2 attacks can be prolonged, debilitating, and associated with impaired consciousness and fever.1 While cortical edema is previously described, transient diffusion restriction can be another radiologic feature2.