Correspondence between functional magnetic resonance imaging somatotopy and individual brain anatomy of the central region: comparison with intraoperative stimulation in patients with brain tumors

Object. The goal of this study was to determine the somatotopical structure -function relationships of the primary motor cortex in individual patients by using functional magnetic resonance (fMR) imaging. This was done to asse ss whether there is a displacement of functional areas compared with anatom ical landmarks in patients harboring brain tumors close to the central regi on, and to validate these findings with intraoperative cortical stimulation . Methods. One hundred twenty hemispheres in 60 patients were studied by obta ining blood oxygen level-dependent fMR images in patients while they perfor med movements of the foot, hand, and face on both sides. There was a good c orrespondence between anatomical landmarks in the deep portion of the centr al sulcus on axial slices and the somatotopical organization of primary mot or areas. Pixels activated during hand movements were centered on a small c haracteristic digitation; those activated during movements in the face and foot areas were located in the lower portion of the central sulcus (lateral to the hand area) and around the termination of the central sulcus, respec tively. In diseased hemispheres, signal-intensity changes were still observ ed in the projection of the expected anatomical area. The fMR imaging data mapped intraoperative electrical stimulation in 92% of positive sites. Conclusions. There was a high correspondence between the somatotopical anat omy and function in the central sulcus, which was similar in normal and dis eased hemispheres. The fMR imaging and electrical stimulation data were hig hly concordant. These findings may enable the neurosurgeon to locate primar y motor areas more easily during surgery.