Combined functional magnetic resonance imaging and diVusion tensor imaging demonstrate widespread modified organisation in malformation of cortical development

A patient with a mild left hemiparesis and a malformation of cortical development in the right hemisphere was investigated with fMRI (functional magnetic resonance imaging) and DTI (diVusion tensor imaging). The motor cortex was studied using a finger tapping fMRI experiment. The fibre orientation was studied by displaying the principal eigenvector of the diVusion tensor in the spatially normalised brain of the patient and of control subjects. In addition, the anisotropy (directionality) of water diVusion of the patient was statistically compared with control subjects. The malformation was located in the right central region in the expected position of the motor cortex. fMRI showed activation anterior and posterior to the malformation. DTI disclosed that fibres with rostrocaudal orientation, presumably representing the pyramidal tract, were deviating from their normal orientation and passing around the malformation. There were widespread regions of reduced anisotropy aVecting both hemispheres. In conclusion, fMRI and DTI provided concordant information showing widespread modified functional and structural organisation including regions which appeared normal on standard imaging. (J Neurol Neurosurg Psychiatry 2001;70:521–523)