Functional MRI in double cortex: functionality of heterotopia.

A 12-year-old boy with epilepsy and subcortical laminar heterotopia (band heterotopia) underwent a functional MRI protocol to study voluntary motor activity in the hand. Finger tapping produced an activation of a contralateral limited and focused frontal cortical area both in the subcortical band heterotopia and the overlying cortex. Despite its epileptogenic activity, subcortical laminar heterotopia seems to be responsible for part of the functional activity of the brain. This has to be pointed out for epilepsy surgery resecting cortical dysplasia.