ATP1A3-related epileptic encephalopathy responding to ketogenic diet

Alternating Hemiplegia of Childhood (AHC) is a rare neurological disease caused by mutations in ATP1A3 gene codifying for alpha3 subunit of Na+-K+ ATPase pump. Repeated and transient attacks of hemiplegia, usually affecting one side of the body or the other, or both sides of the body at once, are the core features of AHC. Monocular nystagmus, other abnormalities in ocular movements, dystonic posturing and epilepsy are commonly associated to AHC. However, the spectrum of ATP1A3 related diseases is still expanding and new phenotypes have been reported. Here, we described a patient who developed a severe early onset drug-resistant epileptic encephalopathy and months later, he presented episodes of hemiplegic attacks and monocular nystagmus. Thus, AHC was hypothesized and a novel mutation in ATP1A3 gene was found. Interestingly, ketogenic diet (KD) was started and both epileptic seizures and classical AHC paroxysmal episodes stopped. Long-term follow-up shows a global improvement of neurological development. Our case reinforces the role of KD as a novel therapeutic option for ATP1A3-related conditions. However, proper dedicated confirmatory trials on KD are necessary.