We report a 10-year-old girl who presented with a single episode of partial complex seizure. Neurological examination and psychological evaluation were normal. Electroencephalogram showed abnormalities in the left temporo-occipital region. Magnetic resonance imaging revealed a bilateral layer of tissue iso-intense with gray matter, between the wall of the lateral ventricle and the cortex, extending from the frontal to the occipital region, and enlarged left lateral ventricle. The images indicated diffuse cortical dysplasia, also known as band heterotopia or "double cortex", and left cortical hemiatrophy.