Hemiconvulsion-hemiplegia-epilepsy syndrome associated with CACNA1A S218L mutation

Hemiconvulsion-hemiplegia-epilepsy syndrome involves sudden and prolonged unilateral seizures, followed by transient or permanent hemiplegia and epilepsy during infancy or early childhood. Some patients with familial hemiplegic migraine and demonstrating the S218L mutation in CACNA1A experience severe attacks with unilateral cerebral edema after trivial head trauma. We report on a 5-year-old Japanese girl presenting with hemiconvulsion-hemiplegia-epilepsy syndrome after infection with parvovirus B19. Magnetic resonance imaging performed 2 days after admission revealed cerebellar atrophy and marked hyperintensity in the left hemisphere on T(2)-weighted and diffusion-weighted imaging. Magnetic resonance angiography performed 7 days after admission demonstrated obliteration of the left proximal middle cerebral artery in the acute phase. However, this finding was not evident on brain angiography performed 25 hours after magnetic resonance angiography. Genetic analysis of familial hemiplegic migraine revealed a heterozygous S218L mutation in CACNA1A. Taken together, these results suggest that vasospasms of cerebral vascular smooth muscle, with possible cortical spreading depression, may have caused the hemiconvulsions and hemiplegia in the left hemisphere. This case report is the first, to the best of our knowledge, to associate CACNA1A with hemiconvulsion-hemiplegia-epilepsy syndrome and familial hemiplegic migraine, and to suggest that similar pathogenic mechanisms may underlie these two disorders.