This case report indicates that the diagnosis of FHM should be taken into account when a patient manifests migraine accompanied with hemiplegia, acute encephalopathy, and abnormal CSF.
We describe four individuals, spanning three generations of a family, with episodic ataxia without hemiplegia and confusion, in association with a CACNA1A mutation.
Our data show that a heterozygous mutation in EAAT1 can lead to decreased glutamate uptake, which can contribute to neuronal hyperexcitability to cause seizures, hemiplegia, and episodic ataxia.
Autosomal dominant mutations in the human ATP1A3 gene encoding the neuron-specific Na(+)/K(+)-ATPase α3 isoform cause different neurological diseases, including rapid-onset dystonia-parkinsonism (RDP) and alternating hemiplegia of childhood (AHC) with overlapping symptoms, including hemiplegia, dystonia, ataxia, hyperactivity, epileptic seizures, and cognitive deficits.
Recent descriptions of Rasmussen syndrome and of the hemiconvulsion-hemiplegia syndrome in isolated patients with SCN1A mutations are of uncertain meaning but might indicate that co-occurring immunomediated or seizure-induced structural changes can, in turn, become a substrate for the severe epileptic encephalopathy.