Usefulness of motor functional MRI correlated to cortical mapping in rolandic low-grade astrocytomas

The indications for surgery of slow growing tumours like low grade astrocyt omas in eloquent areas are difficult. The timing and the benefit/risk ratio of the surgery must be evaluated, taking into account the potential post o perative deficit. The purpose of this study was: a) to validate the data ob tained with functional MRI (FMRI) by direct cortical stimulation in patient s who are candidate for surgery; b) to demonstrate the usefulness of FMRI c oupled with cortical brain mapping and 3D reconstructions of the surfaces o f the brain in low grade astrocytoma. FMRI of the hand-motor cortex was per formed in 8 patients with low grade astrocytomas. They subsenquently underw ent direct cortical mapping to correlate the results of FMRI and resective surgery sparing the functional area. In the 8 cases, the results of direct cortical mapping in the precentral region matched accurately those obtained from FMRI. When surgical resection of low grade astrocytoma in the motor a reas is considered, FMRI used with intra-operative cortical mapping can hel p the surgeon to spare functional areas during tumour removal.