Curvilinear reformations show relative position of subdural electrode contacts to a cortical dysplasia located deep in the left frontal lobe. Curvilinear reformations show relative position of subdural electrode contacts to a cortical dysplasia located deep in the left frontal lobe. In this 23-year-old man with pharmacoresistant focal epilepsy with hypermotor and right tonic seizures from his first year of life, an 8 × 8 subdural grid electrode was implanted over the left frontal cortex for identification of the seizure-onset zone and mapping of language and motor cortex. As mapping of the speech area using electrical stimulation showed a wide extension of the language area, which corresponded to extended activated areas at functional MR imaging during language tasks, the relative position to an underlying suspected cortical dysplasia was crucial for the possibility of removing the lesion without language deficit. Identification of the electrode contacts overlying the dysplasia was based on the results of curvilinear reformatting of 3D MR imaging data. They were found to be part of both the seizure-onset zone and language area. Because of the possible risk of aphasia with a resection of the seizure-onset zone, surgery was deferred in this patient.A, Projection of grid positions to the underlying cortical dysplasia at a depth of 20 mm.B, Selected grid positions are indicated by green markers, and the dysplastic cortex showing blurred gray matter–white matter junction is indicated by a green arrow. Andreas H.-J. Schulze-Bonhage et al. AJNR Am J Neuroradiol 2002;23:400-403 ©2002 by American Society of Neuroradiology