PRESURGICAL EVALUATION OF BRAIN-TUMORS WI TH FUNCTIONAL MRI

Purpose. - To evaluate the capabilities and the limitations of motor f unctional magnetic resonance imaging (FMRI) in the presurgical plannin g of the cerebral tumors located in or near the motor homunculus and t o correlate each type of activation with the histologic characteristic s of each tumor. Materials and methods. - FMRI was performed in 17 pat ients (14 adults and 3 children), without motor deficit, presenting wi th various intra cerebral tumors. Three FMRI activation paradigms were used, controlateral to the lesion: ballistic opposition of the finger s, flexion-extension of the foot and click of the tongue. Four patient s, without motor deficit, with cerebral tumors far from the motor homu nculus were used as control group to look for non specific activations . In all cases, the histopathology of the tumor was known accurately. Results. - In 11 patients with infiltrating tumors, the activated area s were clearly displaced. They were often intratumoral and scattered i n correlation with the degree of infiltration. Two patients with non i nfiltrating tumors (meningioma) showed extratumoral shift of the activ ated areas. Four patients presenting cerebral tumors far from the homu nculus motor did not show intratumoral activation. The supplementary m otor area and the ipsilateral primary motor cortex were also sometimes activated during the motor tasks. The task of the tongue was often ar tifacted, probably because of the head motion. Conclusions. - These pr eliminary results suggest that the histopathologic characteristics of a tumor and especially its microscopic structure plays a role, with ot hers factors, on the motor functional area organization. In a small nu mber of cases. the data obtained from the FMRI could be used intraoper atively, with a neuronavigation system.