Intraoperative validation of functional magnetic resonance imaging and cortical reorganization patterns in patients with brain tumors involving the primary motor cortex.

Object: The purpose of the present study was to compare the results of functional magnetic resonance (fMR) imaging with those of intraoperative cortical stimulation in patients who harbored tumors close to or involving the primary motor area and to assess the usefulness of fMR imaging in the objective evaluation of motor function as part of the surgical strategy in the treatment of these patients.
Methods: A total of 11 consecutive patients, whose tumors were close to or involving the central region, underwent presurgical blood oxygen level-dependent fMR imaging while performing a motor paradigm that required them to clench and spread their hands contra- and ipsilateral to the tumor. Statistical cross-correlation functional maps covering the primary and secondary motor cortical areas were generated and overlaid onto high-resolution anatomical MR images. Intraoperative electrical cortical stimulation was performed to validate the presurgical fMR imaging findings. In nine (82%) of 11 patients, the anatomical fMR imaging localization of motor areas could be verified by intraoperative electrical cortical stimulation. In seven patients two or more activation sites were demonstrated on fMR imaging, which were considered a consequence of reorganization phenomena of the motor cortex: contralateral primary motor area (nine patients), contralateral premotor area (four patients), ipsilateral primary motor area (two patients), and ipsilateral premotor area (four patients).
Conclusions: Functional MR imaging can be used to perform objective evaluation of motor function and surgical planning in patients who harbor lesions near or involving the primary motor cortex. Correlation between fMR imaging findings and the results of direct electrical brain stimulation is high, although not 100%. Based on their study, the authors believe that cortical reorganization patterns of motor areas might explain the differences in motor function and the diversity of postoperative motor function among patients with central tumors.