FUNCTIONAL MAPPING OF THE SENSORIMOTOR CORTEX - COMBINED USE OF MAGNETOENCEPHALOGRAPHY, FUNCTIONAL MRI, AND MOTOR EVOKED-POTENTIALS

Combined use of magnetoencephalography (MEG), functional magnetic reso nance imaging (f-MRI), and motor evoked potentials (MEPs) was carried out on one patient in an attempt to localise precisely a structural le sion to the central sulcus. A small cyst in the right frontoparietal r egion was thought to be the cause of generalised seizures in an otherw ise asymptomatic woman. First the primary sensory cortex was identifie d with magnetic source imaging (MSI) of somatosensory evoked magnetic fields using MEG and MRI. Second, the motor area of the hand was ident ified using f-MRI during hand-squeezing. Then transcranial magnetic st imulation localised the hand motor area on the scalp, which was mapped onto the MRI. There was a good agreement between MSI, f-MRI and MEP a s to the location of the sensorimotor cortex and its relationship to t he lesion. Multimodality mapping techniques may thus prove useful in t he precise localisation of cortical lesions, and in the preoperative d etermination of the best treatment for peri-rolandic lesions.