Hemiconvulsion-hemiplegia-epilepsy (HHE) syndrome is a rare condition involving sudden and prolonged unilateral seizures in infancy and early childhood, followed by hemiplegia. The prolonged focal motor seizure usually occurs during the course of a febrile illness and is followed by hemiplegia ipsilateral to the side of convulsions. Although hemiplegia is usually permanent, it may disappear in about 20% of cases. Some patients with familial hemiplegic migraine and manifesting the S218L mutation in CACNA1A were reported to experience severe attacks with unilateral cerebral edema after trivial head trauma. It has shown that CACNA1A associate with HHE and familial hemiplegic migraine, and suggested that similar pathogenic mechanisms may underlie these two disorders.
