The value of preoperative fMRI in drawing attention to possible unexpected language area representations in a patient with anaplastic astrocytoma

This is a case study of a right handed patient with a/INS; grade III /INS;anaplastic astrocytoma in the superior frontal cortex with intra-axial extensions to the corpus callosum. Presurgical functional MR imaging (fMRI) was done to visualize language network distribution. Intraoperative direct cortical stimulation (DCS) was accordingly done to prevent eloquent functional regions from resection. fMRI results showed a distributed language network including the left inferior frontal gyrus (pars opercularis), the left and right frontal orbital cortices, the left insular cortex, the left superior and middle temporal gyri, the left precentral and postcentral gyri, and the supplementary area. Additionally, statistically stable but unusual activation was found in the left superior frontal gyrus (SFG). During surgery, DCS demonstrated that the stimulation of the SFG – /INS;involved in language function according to the fMRI – /INS;led to anomic disturbances. These deficits in word finding were persistently reproducible when stimulating the same area. Afterwards, tumor removal was performed under navigation and fluorescence guidance as well as subcortical electrostimulation, thus preserving eloquent motor and language areas and tracts. Regarding the results of the fMRI and DCS in this patient, it can be speculated that the altered distribution of eloquent language areas could be the result of tumor-induced reorganization processes. This case study demonstrates that presurgical fMRI was able to identify a localized unusual language network distribution, which was validated with direct cortical mapping during awake surgery. It underlines the importance of careful presurgical planning, keeping in mind the limitations of all used methods.