Interest and limits of the validation of language and motricity functionalMRI by persurgical cortical stimulation.

This chapter describes and discusses the value of the localization of funct ional areas obtained from functional MRI in brain tumor cases. Correlation method is cortical brain mapping by intraoperative stimulation. The experie nce reported here is focused on the study of motricity and language. Methods Twenty two patients with tumors of the rolandic region (n = 16) or in the t emporal lobe (n = 6) underwent functional MR mapping and subsequently corti cal mapping before tumor resection. The tasks chosen were a flexion and ext ension of the fingers or a naming task. We used 3D reconstructed images of the surface of the brain to assess intra and post operatively the functiona l MRI and stimulation data. Results For the motor correlation, in each case, the results of direct cortical map ping matched those obtained with functional MRI, both positively and negati vely, although the extent of the functional activations was larger than the area, required to elicit the corresponding movement during intraoperative brain mapping. For the language correlation and for the task chosen, only t he results of the precentral areas matched those of functional MRI. Conclusions Functional MRI can be used preoperatively to assess motor functional area i n patients with rolandic tumors. More studies are needed to validate intrao peratively the language areas and the real extent of functional MRI activat ions. Finally, the observed discrepancy between functional MRI and cortical stimulation is likely due to the rather profound differences between both techniques, in terms of neurophysiology practical applications and statisti cal analysis.