gms | German Medical Science

Objective: Lesions caused by brain tumors in eloquent brain areas may trigger functional reorganization of language processing. A common finding is enhanced language-associated activation in contralesional homolog brain structures. There are indications in literature that contralesional activation might reflect a compensatory or dysfunctional process depending on the tumor localization (Thiel et al. 2006). The reasons for this are still unclear but certainly must be caused by processes in the microstructure. According to tumor localization there is the finding that frontal tumors more often express the isocitrate dehydrogenase 1 (IDH1) mutation than tumors in other brain areas (Lai et al. 2011). This might also effect aspects of brain activation patterns. Therefore, this study investigates a possible correlation of tumor localization and the IDH1 mutation.

Methods: 23 patients with left inferior frontal gyrus (including 13 patients with IDH1 mutation) and 28 patients with left temporoparietal (including 10 patients with IDH1 mutation) primary glial tumors in language critical areas and 34 healthy control subjects were included. Functional magnetic resonance imaging was performed at a 3T Siemens Allegra Scanner. During the language fMRI paradigm subjects had to perform covertly a verb generation task. Data analysis was done by using SPM 12 including the Marsbar toolbox and the Automated Anatomical Labeling Atlas for region of interest (ROI) definition and analysis.

Results: Patients with tumors in the left inferior frontal gyrus (IFG) and IDH1 mutation show increased activation in the left superior temporal gyrus and sulcus compared to patients without IDH1 mutation. In contrast these patients exhibit more activation in the left supramarginal gyrus and the right IFG compared to healthy controls. Patients with tumors in posterior language critical areas and IDHI1 mutation revealed more activation in the right IFG compared to patients without mutation. At least patients with posterior tumors and no IDH1 mutation exhibit increased activation in the right and left IFG and the right supramarginal gyrus in contrast to healthy control subjects.

Conclusion: This preliminary data provides first indications for the correlation of molecular markers and hemodynamic processes associated with cognitive functions as language processing. There might be an interaction of molecular markers as IDH1 and tumor location associated with processes of functional reorganization.