Focal cortical myoclonus in rolandic cortical dysplasia presenting as hemifacial twitching.

A 2-year-old girl presented with brief episodes of left hemifacial twitching. On ictal electroencephalography, repetitive focal spike discharges appeared at the right fronto-centro-temporal regions; these discharges preceded the onset of each twitch by 12 ms. Magnetic resonance imaging showed a linear abnormal signal intensity in the subcortical white matter at the right postcentral gyrus, where a cluster of dipole sources was detected by magnetoencephalography. These findings suggested that the patient had focal cortical myoclonus due to rolandic focal cortical dysplasia.